recent status of chemical bath deposited metal chalcogenide and metal oxide thin films

d, Cngine, Che04

matoulstalis clarg

2010 Elsevier B.V. All rights reserved.

e thinast decn coatnic comarea p

sodium sulphide are generally used as sulphide precursors. Metallicprecursors are metal complexed ions with ammonia ligands, forinstance [2]. The reaction takes place between the dissolved

ion-exchanged water. Thus, precipitation formation i.e. wastage ofmaterial, is avoided in SILARmethod. Ristov et al. [9] reported SILARmethod in 1985. Pathan and Lokhande [10] have reviewed thepreparation of metal chalcogenide and oxide thin lms by thismethod in the year 2004.

Using these chemical methods, a large number of chalcogenidethin lms have been deposited. Although, the literature is

* Corresponding author. Tel.: 82 2 958 5217; fax: 82 2 958 5219.E-mail addresses: [email protected], [email protected]

Contents lists availab

Current Appl

w.e

Current Applied Physics 11 (2011) 117e161(C.D. Lokhande).selective coatings, solar cells, photoconductors, sensors, etc. Thechemical depositionmethods are lowcost processes and thelms arefound to be of comparable quality to those obtained by moresophisticated and expensive physical deposition process. Amongthese chemical methods, chemical bath deposition (CBD) which isalso known as solution growth, controlled precipitation, or simplychemical deposition, recently has emerged as the method for thedeposition of metal chalcogenide thin lms [1]. The CBD method ispresently attracting considerable attention, as these do not requiresophisticated instrumentation like vacuum system and otherexpensive equipments. Simple equipments like hot plate withmagnetic stirrer are needed. The starting chemicals are commonlyavailable and cheap. Thiourea, thioacetamide, thiosulphate and

work in this area. The subsequent progress in this area is contained ina 1991 review article written by Lokhande [4]. Many review articlesrelated to preparation of sulphides and selenides thin lms by CBDmethods have been appeared in the literature [5e8].

In CBD method, deposition of metal chalcogenide thin lmoccurs due to substrate maintained in contact with dilute chemicalbath containing metal and chalcogen ions. However, this resultsinto precipitate formation in the bulk of solution, which cannot beeliminated. In order to avoid such precipitation, a CBD is modied(M-CBD) which is also known as successive ionic layer adsorptionand reaction (SILAR) method. In this modication, thin lms areobtained by immersing substrate into separately placed cationicand anionic precursors and rinsing between every immersion withMetal oxidesChemical synthesis

1. Introduction

The deposition of materials in thsubject of intense research over the pin various elds such as antireectiosurface acoustic wave devices, electroand integrated), fabrication of large1567-1739/$ e see front matter 2010 Elsevier B.V.doi:10.1016/j.cap.2010.07.007lm form has been theades due to applicationsings and optical lters,ponents (both discretehotodiode arrays, solar

precursors generally in aqueous solution at low temperature(300e353 K).WithCBDmethods, a large numberof substrates can becoated in a single runwith a proper jig design. Electrical conductivityof the substrate is not the necessary requirement. The basic principlesunderlying the chemical bath deposition of semiconductor thin lmsand early research work in this area have been presented in a 1982review article [3], which has inspired many researchers to initiateThin lmsNanostructures by CBD and SILAR. Properties and applications of the thin lms are also summarized.Metal chalcogenidessuccessive ionic layer adsorption and reaction, SILAR) methods, a large number of thin lms have beendeposited. This review is on the status of synthesizing thin lms of metal chalcogenide and metal oxidesReview

Recent status of chemical bath depositeoxide thin lms

S.M. Pawar a, B.S. Pawar a, J.H. Kim a, Oh-Shim Joo b

a Photonic and Electronic Thin Film Laboratory, Department of Materials Science and EbClean Energy Research Center, Korea Institute of Science and Technology, P.O. Box 131c Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur 4160

a r t i c l e i n f o

Article history:Received 28 July 2009Accepted 9 July 2010Available online 23 July 2010

Keywords:

a b s t r a c t

Presently nanocrystallinesince material properties cThe synthesis of nanocrydeposition (CBD) methodsimple and convenient for

journal homepage: wwAll rights reserved.metal chalcogenide and metal

.D. Lokhande b,c,*

ering, Chonnam National University, 500 757 Gwangju, Republic of Koreaongryang, Seoul 130-650, Republic of Korea(M.S), India

erials have opened a new chapter in the eld of electronic applications,d be changed by changing the crystallite size and/or thickness of the lm.line metal chalcogenide and metal oxide thin lms by chemical bathurrently attracting considerable attention as it is relatively inexpensive,e area deposition. Using CBD and modied CBD (which is also known as

le at ScienceDirect

ied Physics

lsevier .com/locate/cap

dissociation reaction of water.

plienH2O5nOH nH (1)

Step 2, the association/dissociation equilibrium of the solvatedmetal complex, can be thought of as being replaced by a process inwhich the ligands of the complex are displaced by hydroxyl groupsto form a solid hydroxide compound.

nOH MLniki /MOHns iLk (2)

where, Mn is a metal cation complexed by i ligands Lk. Theformation of oxide can come about via deprotonation of thehydroxide compound to form the oxide (step 4).dominated by work on sulphide and selenide thin lms, themethods have also been used for the deposition of oxide thin lms.The work on metal oxide thin lms is relatively new. Therefore, therange of oxides that has been produced is much narrower, and theunderstanding of processing-property relationships is lessadvanced, than in the case with sulde and selenide lms.

The present review article is an extension of review articlespublished by Mane and Lokhande [7] in the year 2000 on CBD andPathan and Lokhande [10] in the year 2004 on SILAR depositedmetal chalcogenide andmetal oxide thin lms. In order to avoid therepetition of the data, the status of CBD thin lms after the year2000 and SILAR thin lms after the year 2003 is reported.

2. Theoretical background

2.1. Basics of chemical bath deposition

Most of the chemical baths (medium) consists of one or moremetal salts Mn, a source for the chalcogenide X (X S, Se, Te), andtypically a complexing agent, in an aqueous solution. The deposi-tion of metal chalcogenide occurs via following four steps.

(1) Equilibrium between the complexing agent and water;(2) Formation/dissociation of ionic metaleligand complexes [M

(L)i]nik, where Lk denotes one or more ligands;(3) Hydrolysis of the chalcogenide source; and(4) Formation of the solid.

During the step 3, the metal cations are pulled out of solution bythe desired non-metal species provided through the hydrolysis of thechalcogenidesource, to formthe solidlm. Thekinetics of the step3 ishighly sensitive to the solution pH and temperature, as well as to thecatalytic effects of certain solid species thatmay be present, which inturn decides rates of the formation of thin lm on the surface of thesubstrate or bulk precipitation. The basic principle involved behindthe formation of desired solid lm/bulk MmXn (step 4) is the risingconcentration of Xm from step 3 causes the ionic product [Mn]m

[Xm]n to exceed the solubility product. During step 2, the formationof complexed metal ions allows control over the rate of formation ofsolidmetalhydroxides,whichcompeteswith step4andwhichwouldotherwise occur immediately in the normal alkaline solutions. Thesesteps together determine the composition, growth rate, microstruc-ture, and topographies of the resulting thin lms.

The oxide deposition using CBD method also takes place byfollowing above four reaction steps. Step 1 in those cases wherea complexing agent is used, in the same for the non-oxide and oxidedepositions, where the function of the ligand remains one ofslowing down the rate of solid formation. The analogous process tostep 3, hydrolysis of the chalcogenide source, is essentially the

S.M. Pawar et al. / Current Ap118MOHns/MOn=2s n=2H2O (3)Cd2 NH22CS NH22CSeCd

2 (8)

This ion is hydrolyzed by breaking the SeC bond to form CdS.

NH22CSeCd22OH/CdS CN2H2 2H2O (9)

This would lead to CdS formation in solution. If Cd2 is absorbed onthe substrate (either directly or indirectly through a hydroxideHowever, the processes depicted from reactions (2) and (3) aresometimes called as a forced hydrolysis. In most of the reportedliterature, the hydroxide was converted to the oxide only afterheating the as-deposited lm at 423e673 K. Therefore, the netgeneral oxide formation scheme can be written as;

MLniki n=2H2O/MOn=2s nH iLk (4)

2.2. Thin lm deposition mechanisms in chemical bath

There are four main mechanisms for the compound formation,whose operation depends on the specic process and reactionparameters. The thin lm CBD deposition occurs via following fourpossible mechanisms [1].

2.2.1. Simple ion-by-ion mechanismIn most of the CBDs, the ion-by-ion conceptually simplest

mechanism,oftenassumedtobe theoperativeone ingeneral. Itoccursby sequential ionic reactions. The general reaction for themechanism

Mn Xm/MmXn Adsorbed on the substrate (5)

The formation of solid MmXn is based on the principle that whenthe ion product, [Mn][Xm], exceeds the solubility product, Ksp, ofMmXn, then MmXn can form as a solid phase, although a larger ionicproduct may be required if supersaturation occurs. If the ionproduct does not exceed Ksp, no solid phase will form, exceptpossibly transiently due to local uctuations in the solution, and thesmall solid nuclei will redissolve before growing to a stable size. Forthat reason, the precipitation process is an equilibrium rather thanas a one-way reaction.

2.2.2. Simple cluster (hydroxide) mechanismInmost of the CBDs, the preparative conditions are so chosen that

the formation of metal hydroxide should be avoided. However, inreality, CBDs are quite often carried out under conditions wherea metal hydroxide (or hydrated oxide) is formed. This might seem toimply that a precipitate ofmetal hydroxide [M(OH)n] is formed at thestart of the CBD. In fact, the metal hydroxide formed is either asa colloid rather than a precipitate or as an adsorbed species on thesubstrate but not in the bulk of the solution. In this case metal chal-cogenide (MmXn) is formed by reaction of Xm ion with the M(OH)n.

Mn nOH/MOHn (6)Followed by,

MOHnXm/MmXn nOH (7)

2.2.3. Complex-decomposition ion-by-ion mechanismIn this mechanism, complexation of free metal cations (Mn) by

thiourea gives M-thiourea complex ion. This is illustrated by theexample of CdS deposition.

d Physics 11 (2011) 117e161linkage) then above reaction occurs and CdS is formed on substrate,

SILAR process is intended to grow thin lms of water insoluble ionic

plieor ion covalent compounds of the type KpAa by heterogeneouschemical reaction at the solid solution interface between adsorbedcations, pKa and anion, aAp, following the reaction

pKaaq qXbaq

b0Yq0aq aAp

/KpAaSY qXbaq

b0Yq0aq With ap b0q 12

where K represents cation (Cd2, Zn2,Fe3, Cu2, etc), p representsthe number of cations, a represents the numerical value of charge oncation, X is a ion in cationic precursors having negative charge(X SO42,Cl, NO3, etc), q represents the number of X in cationicprecursors and b the numerical value of charges on X, b0 is thenumber of Y in the anionic solutions, q0 is the numerical value ofcharge onY, Y the ionwhich is attached to chalcogen ion, A representsthe anion (O, S, Se and Te), a0 the of anions. A is the chalcogen ion. Inthe presence of complexing agent, above reaction can be written as

PhKCa

iaqqXbaq b0Yq0aq aAp/Kp0Aa0SY C qXbaq

b0Yq0aq 13where C is complexing agent.

Fig. 1 represents the deposition of compound KA thin lm usingSILAR method. It consists of four different steps such as adsorption,the result would be lm growth by ion-by-ion. This mechanism isalso useful in acidic solution; thioacetamide decomposition atintermediate pH values, particularly in weakly acidic solution(pH 2) has been suggested to occur through a thioacetamidecomplex rather than through intermediate formation of sulphide.

2.2.4. Complex-decomposition cluster mechanismThe complex-decomposition cluster mechanism is based on the

formation of solid phase instead of reacting directly with a freeanion; it forms an intermediate complex with the anion-formingreagent. Continuing with CdS deposited from a thiourea bath byconsidering example given as

CdOH2NH22CS/CdOH2$SCNH22 (10)Cd (OH)2 is one molecule in the solid phase cluster. This complex ora similar one if contains ammine ligands then decomposes to CdS.

CdOH2$SCNH22/CdS CN2H2 2H2O (11)The SeC bond of the thiourea breaks, leaving the S bond to Cd. It issuggested that Cd (OH)2 forms initially on the substrate and cata-lyzes the thiourea decomposition. The catalytic effect of the solidsurface could be to decompose thiourea to sulphide ion and notnecessarily to catalyse the complex-decomposition mechanism.

2.3. Basics of thin lm deposition in SILAR (M-CBD)

The collection of a substance on the surface of another substanceis known as adsorption, which is the fundamental building block ofthe SILARmethod. The adsorption is a surface phenomenon betweenions and surface of substrate and is possible due to attraction forcebetween ions in the solution and surface of the substrate. Theseforces may be cohesive forces or Van der Waals forces or chemicalattractive forces. Atoms or molecules of substrate surface possessunbalanced or residual force and hold the substrate particles.

The SILAR is based on sequential reaction at the substrate surface.Rinsing follows each reaction,which enables heterogeneous reactionbetween the solid phase and the solvated ions in the solution. The

S.M. Pawar et al. / Current Aprinsing (I), reaction and rinsing (II).Adsorption: In this rst step, the cations present in the precursorsolution are adsorbed on the surface of the substrate and form theHelmholtz electric double layer. This layer is composed of twolayers: the inner (positively charged) and outer (negativelycharged) layers. The positive layer consists of the cations and thenegative forms the counter ions. Rinsing (I): In this step, excessadsorbed ions, K and X are rinsed away from the diffusion layer.Reaction: In this reaction step, the anions from anionic precursorsolution are introduced to the system. Due to the low stability of thematerial, KA, a solid substance is formed on the interface. Thisprocess involves the reaction of K surface species with the anionicprecursor, A. Rinsing (II): In last step, the excess and unreactedspecies A, X, Y, and the reaction byproduct from the diffusion layerare removed.

By repeating these steps, a thin layer of material, KA, can begrown. Following the above-mentioned steps the maximumincrease in lm thickness per one reaction cycle is theoretically onemonolayer. This results into a solid layer of the compound KA. If themeasured growth rate exceeds the lattice constant of the material,a homogeneous precipitation in the solution could have takenplace. The facts affecting the growth phenomena are the quality ofthe precursor solutions, their pH values, concentrations, counterions, individual rinsing and dipping times. In addition, complexingagent and pretreatment of the substrate have been shown to affectthe SILAR growth.

3. Experimental details

The CBD experimental setup is shown in Fig. 2. In this method,substrates are stationary and solution is stirred with the help ofmagnetic stirrer. Water or parafn baths with constant stirring areused to heat the chemical bath to the desired temperature. In somecases, stirring is continuous from room temperature, while in somecases, it is started after attaining the desired temperature.

The critical operations for the deposition of thin lms by SILARmethod are adsorption of the cations, rinsing with deionized water,reaction of pre-adsorbed cations with newly adsorbed anions andagain rinsing with deionized water. The beakers containingprecursor solutions and deionized water are alternately placed asshown in Fig. 3. The immersion and rinsing of substrates are donemanually or using microprocessor based systems.

4. Metal chalcogenide and metal oxide thin lms by CBDmethod

The following section deals with chemical bath deposition ofvarious metal chalcogenide andmetal oxide thin lms. The detailedpreparative conditions and properties are presented in Table 1.

4.1. Metal sulphide thin lms

4.1.1. Cadmium sulphide (CdS)Because of the proven and potential applications in the photo-

conductors as well as in the photovoltaic devices, CdS thin lmshave been prepared by CBD from aqueous acidic and alkaline andnon-aqueous baths [11e37]. The CdS thin lms deposited underconstant magnetic eld showed low resistivity and high band gapenergy value compared to samples grown without magnetic eld[38]. Lejmi and Savadogo [39] deposited CdS thin lms using het-eropolyacids or phosphotungstic acid and found that the depositedCdS lms have a mixed structure (45% hexagonal and 55% cubic)with a predominance of the cubic phase for long growth periods.Lopez et al. [40] synthesized CdS thin lms from an ammonia freechemical bath. Montijo et al. [41] found that CBDeCdS is a good

d Physics 11 (2011) 117e161 119candidate for window layer in thin lm solar cells. The super

hydrophobic CdS thin lms with a porous micro/nano-binarystructure deposited by Liu et al. [42] using microwave assistedchemical bath deposition (MA-CBD) method. The effects ofdopants, such as; chlorine, iodine, boron and indium on propertiesof CdS thin lms have been reported [43e45]. Narayanan et al.[46,47] showed that nitrogen and boron ions implanted CdS thin

lms for fabricating homojunction CdS solar cells. The CBDeCdSthin lms are used for window and buffer layers in the solar cells[49e57] and thin lm transistors [58]. Boyle et al. [59] and Kosto-glou et al. [60] developed a comprehensive model useful in processdesign and optimization of CdS thin-lm growth and model con-taining the temporal variation of reactants concentrations as well

Fig. 1. Schematic representation of SILAR method (a) cationic precursor and (c) anionic precursor and (b, d) deionised water.

S.M. Pawar et al. / Current Applied Physics 11 (2011) 117e161120lms exist in CdS phase. Nair et al. [48] used nanostructure CdS thinFig. 2. Experimental set-up ofas of the precipitating solid phase, both in the bulk and on thechemical bath deposition.

plieS.M. Pawar et al. / Current Apsubstrate, respectively. The CdS thin lms on different substrateslike polycarbonate (PC), polyethyleneterephthalate (PET) andpatterned CdS thin lms on octadecyltrichlorosilane (OTS)patterned Si-substrate were used in exible solar cells and photo-detector applications [61e63].

4.1.2. Zinc sulphide (ZnS)Zinc sulphide (ZnS) is an important semiconducting material

with a wide direct band gap and n-type conductivity is promisingfor optoelectronic device applications, such as electroluminescentdevices and photovoltaic cells. It is of interest for replacement ofCdS as buffer layer of thin lm based solar cells due to higherenergy gap, good transparency, and general good lm properties.The chemical deposition of ZnS thin lms has been carried out fromaqueous acidic and alkaline baths [64e75]. The ZnS thin lmsdeposited using different complexing agents such as Na2EDTA,tartaric acid, sodium citrate are studied for their structural, opticaland electrical properties [76e79]. Ibanga and Luyer [80] depositedZnS thin lms on glass substrate and produced ZnO thin lms bythermal oxidation. The nanocrystalline ZnS thin lms have beendeposited by Yamaguchi et al. [81] on indium tin oxide (ITO) glasssubstrate and studied their growth. The CBDeZnS thin lms havebeen used as a buffer layer in solar cells [82e86].

4.1.3. Mercury sulphide (HgS)Patil et al. and Kale et al. [87,88] deposited nanocrystalline HgS

thin lms with FCC crystal structure onto the glass and uorinedoped tin oxide (FTO) coated glass substrates from the alkaline and

Fig. 3. Experimental set-d Physics 11 (2011) 117e161 121acidic baths. The HgS lmswith band gap 2.75 eVwere photo activein polysulphide and polyiodide electrolytes.

4.1.4. Silver sulphide (Ag2S)Thin lms of Ag2S have applications in photoconducting cells, IR

detectors, solar selective coating, photovoltaic cells and photoelectrochemical (PEC) storage cells. Rodrguez et al. [89] obtainedAg2S thin lms using thiosulphate as a complexing agent anddimethylthiourea and tetramethylthiourea as sulphide ion sources.These lms showed good uniformity and adherence on ZnS coatedand organosilane treated glass substrates. The lms showed opticalband gap of 1 eV with electrical conductivity ofw103 U cm1. Thehigh optical absorption coefcient in the visible region, >105 cm1,suggested it as an effective absorber material for solar energy.

4.1.5. Manganese sulphide (MnS)The MnS (Eg 3.1 eV) has potential use in short wavelength

optoelectronic devices and in solar cells as a window/buffermaterial. Fan et al. [90,91] have deposited crystalline MnS thin lmsusing HF pre-treated substrates. Gumus et al. [92,93] depositedhighly transparent crystalline MnS thin lms on glass substrate.These lms are of single-phase wurtzite crystal structure andpreferential orientation along the c-axis.

4.1.6. Bismuth trisulphide (Bi2S3)Bi2S3 with band gap energy of 1.7 eV is useful in optoelectronic,

thermoelectric, and PEC devices. The properties of nanocrystallineBi2S3 thin lms have been studied [94e100]. Pejova et al. [101]

up of SILAR method.

Table 1Preparative condition of metal chalcogenide and metal oxide thin lms by chemical bath deposition method.

Sr. No. Bath composition pH Thickness Depositiontemperature (K)

Substratesused

Deposition time Remarks Ref.

A. Metal sulphide thin lms1. Cadmium sulphide (CdS)1. Cd(CH3COO)2NH3/NH4OH CS

(NH2)2Alkaline 20e180 nm 333 Glass 20e80 min Nanocrystalline [11]

2. 1 M CdCl2 1 M CS(NH2)2 C6H15 NNH4OH

10.3e12.8 500 nm 300 Glass 5e8 h Uniform andtranslucent

[12]

3. 0.02 M CdCl2 0.05 M NH4Cl 0.4 M NH3 0.05 M CS(NH2)2

8.75 66 nm 358 Si, ITO 20 min Nanocrystalline,hexagonal withorientation along the(002) plane

[13]

4. CdSO4/CdCl2 KOH CS(NH2)2 nitrilotriacetic acid (NTA)

Alkaline 0.2e1 mm 328e358 Quartz, ITO 30 min Polycrystalline withcubic crystal structure.

[14]

5. 0.02 M CdSO4/CdI4/Cd.(CH3OO)2/CdCl2NH3 0.04 M CS(NH2)2

Alkaline e 343 Quartz 15 min CdCl2-based lms havea better transmissionand much smoothersurfaces than otherlms

[15]

6. 0.001 M CdCl2 0.012 M NH2eCH2eCH2eNH2 0.01M NaOH 0.01 M CS(NH2)2

12 e 303 Glass 75 min Nanocrystalline,homogenous, pinhole-free high quality thinlms on large area(10 10 cm)substrates. Suitable foruse in photovoltaicdevices

[16]

7. 1 M CdSO4 2.25 M hydrazine 1.4 M CS(NH2)2 25% NH3

Alkaline 1.4 mm 313e333 Glass 30 mine4 h The optical propertiesdepended on lmthickness,the deposition andannealing temperature.Annealing in airresulted decrease in theband gap value from2.45 to 2.38 eV

[17]

8. 0.0011 M CdCl2 0.013 M NH4Cl1.3 M NH4OH 0.0132 M CS(NH2)2 2.6 105 M PVA

e e 343e358 Glass, Si e The quantum size effectoccurred in the lms.

[18]

9. CdCl2 CS(NH2)2NH4Cl 10 e 358 Glass, ITO e The shorter time ofchlorine out-diffusionfrom lms causesstronger changes ofresistivity incomparison tosprayed CdS

[19]

10. 0.12 M CdCl2 2 M NH3 0.3 M CS(NH2)2

Alkaline 100e280 nm 348 FTO 15e180 min The growth rate isfaster when thequantityof thiourea is muchgreater than cadmiumchloride concentrationin the solution andalso when the S/Cdratio is higher,the band gapincreases

[20]

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11. 1 M CdCl2 1 M CS(NH2)2 C6H15 NNH3

9e11 2 mm 333e363 Glass 30e60 min The lms prepared withpH value 10, havebetter structural andoptical properties thanthe lms from bath ofpH value 11

[21]

12. 0.015 M CdCl2 0.045 M CS(NH2)2NH3

12 e 293 Glass 8e22 min Polycrystalline withsphalerite crystalstructure.The microwave heatingis more efcient

[22]

13. CdCl2 KOHNH4NO3 CS(NH2)2 polyglycol

e e 338e368 Glass, Si 1 h Hexagonal structurewith strong orientationalong (002) plane. Theband gaps calculatedfrom transmissionspectra are about 2.56e2.336 eV

[23]

14. 0.01 M CdSO4 0.1 M SC(NH2)2 0.1e0.325%NH4SO4 10 N NH3

9.5e11.5 e 343e263 Glass e As-deposited lms arecubic and after theannealing thecrystallinity increasedand structural changeoccured from cubic tohexagonal phase

[24]

15. 0.06 M CdSO4 0.12 M CS(NH2)2 1.74 M NH3

10.8 e 348e358 Glass e The band gap energyvaried from 2.48to 2.35 eV followingclosely the quantumconnementdependence of energyagainst crystalliteradius

[25]

16. 0.02 M CdCl2 0.05 M CS(NH2)2 0.05 M NH4Clor 0.01 M EDTA

11 e 353 ITO 30 min The effect ofcomplexing agent onthe crystal phase ofCdS lms is studied.The lms are ofhexagonal and cubicstructure whenammonia and EDTAare used ascomplexing agent

[26]

17. 1 M CdSO4 1.4 M CS(NH2)2 2.25 M hydrazine 25%NH3

Alkaline 1 mm 333 Glass 1e18 min The lms contain bothcubic and hexagonalstructures as a mixture.The percentage ofhexagonal structuredcrystallites in the lmswas increased afterannealing

[27]

18. 0.03 M Cd(CH3COO)2 1 MNH4(CH3COO)2 0.067M CS(NH2)2 28-30% NH4OH

Alkaline 26e95 nm 363 Glass 50 min Good quality, adherent,uniform andpinhole-free lms withhexagonal phaseand orientation in the(002) plane

[28]

(continued on next page)

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Table 1 (continued)


Substratesused


19. 0.05 M CdSO4 1.4 M NH3Ac 0.14 M CS(NH2)2

Alkaline 50 nm 353 Glass, FTO 20 min The lms are pinhole-free and adherent to thesubstrate

[29]

20. 0.5 M CdSO4 0.7 M potaiumnitriotriacetate 10%KOH 0.4 M CS(NH2)2

8.5 150e300 nm 296e363 Glass 50e200 min Closely packednanocrystals witha thickness of up to300 nm

[30]

21. 0.02 M CdCl2 0.5 M KOH 1.5 MNH4NO3 0.2 M CS(NH2)2

e e 353 Glass 30 min Resistivity valuesexhibit sharp increasein the region 533e573 K as a result ofthe changed lmestoichiometry onaccount of Cdevaporation

[31]

22. 0.1 M Cd(CH3COO)2 1.1 MNH4(CH3COO) 35% NH350% triethanolamine 0.25 M CS(NH2)2 1 M KOH

11.5 e 358 Glass 20 min The annealed lmsshowed mixed phaseof cubic and hexagonal,whereas the grown lmexhibited onlyhexagonal structure.The resistivity of as-deposited lms wasof the order of3 106 U cm

[32]

23. (0.1e1) M CdCl2 14 N NH3 1 MCS(NH2)2

9.5e11 e 323e363 Glass 30 min The structural changedue to varyingcadmium ionconcentration affectsthe optical andelectrical properties.

[33]

24. Cd(CH3COO)2NH4OH SC(NH2)2 e 0.04e2 mm 358 Glass 30e90 min Deposited cubic lmsare polycrystalline

[34]

25. 0.1 M Cd(NO3)2 1 M sodiumcitrate 1.5 M NH3 1 M SC(NH2)2

e 400 nm 348 Glass 4 h Air heating attemperatures643e773 K for about5 min has been foundto produce a conductiveCdO thin lm on achemically depositedCdS thin lm

[35]

26. 0.003MCdCl2 0.3 MNH3 0.02 MNH4Cl 0.0075 M CS(NH2)2

11 e 348 Glass 60 min The hexagonal phaselm has preferentialgrowth in the [002]direction

[36]

27. 0.02 M CdCl2 0.5 M KOH 1.5 MNH4NO3 0.2 M CS(NH2)2

e e 353 Glass 40 min The thermal annealinginuences thecrystalline structurequality, the latticeparameter, the grainsize and the opticalabsorption

[37]

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28 CdCl2NH4ClNH3 SC(NH2)2 Alkaline e 338e358 Glass 40 min Effect of magnetic eldstudied. Films aregrown at 338 K ofbath temperature,with c(thio)/c(CdCl2)1 and B 0.077 T.useful for window-material

[38]

29. 0.035 M Cd(CH3COO)2 0.035 M(CS(NH2)2 0.1 M NH4Ac 0.3 M NH4OH containing 105 Msolution of HPA or IPA

Alkaline 0.03e0.39 mm 363 Glass, ITO 20 mine6 h The deposited CdS lmshave a mixedstructure (45%hexagonal and 55%cubic) with apredominance of thecubic phase for longgrowth periods(20% hexagonal and80% cubic for morethan 1-h deposition)

[39]

30. 0.05 M CdCl2 0.5 MC6H5O7Na3O7 0.5 M KOH 0.5 MCS(NH2)2

10 190e200 nm 343 Glass 15e120 min The cadmiumesodiumcitrate system allowedthe deposition of highlyoriented CdS lms withtunable energy bandgap between 2.26and 2.5 eV

[40]

31. 0.05 M CdCl2 0.5 MNa2C6H5O7 0.5 M KOH0.5 M CS(NH2)2

11 343 Glass 15 s, 10 min The CdS layers are goodcandidates for windowlayers in thin lmsolar cells

[41]

32. 0.015 M CdCl2 0.045 M CS(NH2)2NH3

12 e 298 Glass 5e30 min The superhydrophobicsurface with watercontact angle (CA) of151

was obtained.

[42]

33. 0.025 M Cd(CH3COO)2 0.1 MNH4(COO) 30% NH30.05 M CS(NH2)2H3BO3

11 e 348 Glass 40 B-doped CdS lms havea hexagonal structurewith a preferentialorientation of the (002)plane. The grain sizeof B-doped CdS lmsslightly decreased, butno change of themicrostructure

[43]

34. 0.025 M Cd.(CH3COO)2 0.05 M CS(NH2)2NH3 0.1 M NH4(CH3COO)H3BO3

10.5e11 3 mm 348 Glass e Boron doping into CdSlms improved theoptical transmittance inthe visible region oflight and increased theoptical band gap

[44]

35. 0.001 M CdCl2 0.02 M NH4Cl 0.002 M CS(NH2)2H3BO3/InSO4 with various conc.

10.3 250 nm 358 Glass 20 min The electrical resistivityof CdS lms doped withboron and chlorine/indium was dependenton doping level

[45]

36. 1 M CdCl2 1 M CS(NH2)2 triethanolamine 30%NH3

Alkaline 200 nm 353 ITO, Glass e The n-doping CdS thinlms by boronimplantation

[46, 47]


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Table 1 (continued)


Substratesused


37. 1 M Cd.(CH3COO)2 13 MNH3 2 M CS(NH2)2 7.2 Mtriethanol amine

Alkaline e 358 Glass 25 min The decrease in bandgap with N

implantation uence isdue to implantation-induced latticedisorder. Theabsorption at longerwavelength region(w625 nm) isattributed to thesurface states createdduring implantation

[48]

38. Cd(CH3COO)2NH3 CS(NH2)2 e e 343 CIGS layered 15 min The highest efcienciesachieved with CdSbuffer layers producedby CBD

[49]

39. 0.024 M CdCl2 CS(NH2)2 2.3 MNH3 0.02 M NH4Cl

e 130e150 nm 348 FTO 100e150 s The deposited lms areused as window layersfor CdTe solar cells

[50]

40. 0.12 M CdCl2 2 M NH3 0.3 M CS(NH2)2NH4Cl

e e 348 Glass 60e120 min The lms havea hexagonal phase witha (002) orientation.

[51]

41. 0.02 M CdCl2 0.07 M NH4Cl 0.14 M CS(NH2)2

9.5 0.1e0.2 mm 363 Glass, FTO 15 min The lm is hexagonalwith (002) highlyorientation

[52]

42. 0.015 M CdSO4 28e30% NH4OH 1.5 M CS(NH2)2

Alkaline e 338e363 CIGS 2e6 min Device performancewas found to bedependent on the CdSlayer thickness, butrather independent ofthe growthtemperature

[53]

43. 0.025 M CdCl2 0.035 M CS(NH2)2 1.7 M NH3

12 e 333 FTO e Used as a window layerin solar cell

[54]

44. CdCl2NH4ClNH4OH CS(NH2)2

e 470 nm 348 GaSb, InP 5e20 min The surfacerecombination velocitycalculated from photoacoustic measurementsdecreased and theradiativerecombination rate asmeasured fromphotoluminescencespectra increased whenthe nominal S/Cd ratioin the layer depositionsolution increased

[55, 56, 57]

45. 0.02 M Cd(CH3COO)2 0.02 M CS(NH2)2 triethanolamine

Alkaline e 343 SiO2/Si 40 min Fabricated CdS thin-lm transistors (TFTs)using the preparedPDMS shadow masks.

[58]

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46. 0.025 M Cd(CH3COO)2 0.05 M CS(NH2)2NH3NH4(CH3COO)

11 300 nm 348 Glass, ITO, PC, PET e The CdS polycrystallinelms show very high H(002)/C(111)orientation whendeposited onto glasssubstrate, but suchpreferential orientationdecreased ordisappeared when thedeposition was madeonto PC or PETsubstrates

[61]

47. Cd(CH3COO)2 ethylenediamine CS(NH2)2

10.3e10.7 63e290 nm 308e348 OTS-patterned Sisubstrate

25e110 min The deposited lmswere hexagonal as wellas cubic phase and havedemonstrated that it ispossible to depositmicropatterned CdSlms on OTS-patternedSi substrate

[62]

48. 0.02 M CdCl2 0.5 M KOH 1.5 MNH4(NO3) 0.2 M CS(NH2)2

9.8 e 338e358 Glass e Longer deposition timegave better structuralstability for thedeposited CdS

[63]

2. Zinc sulphide (ZnS)1. 0.077 M ZnCl2 0.071 M CS

(NH2)2 1.39 M NH4OH 2.29 Mhydrazine hydrate

10e11.5 e 363 FTO 3 h The lms have cubicstructure (b-ZnS) witha better crystallinityobtained at pH equal to10. The decreasing ofthe pH value from 11.5to 10 is accompaniedwith the increasing ofthe (111) peak intensity

[64]

2. (0.01e0.1) M ZnSO4 (0.07e0.37)M NH3 (0.8-4) M CS(NH2)2

Alkaline 120e140 nm 353 Glass 80 min The ZnS lm is cubicwith granular structureand grain size about100 nm. The opticaltransmittance of theZnS lm is above 90% invisible light

[65]

3. 0.2 M ZnSO4 0.2 M CS(NH2)2 triethanolamine 3 MNaOH

13 e 363 Glass 4 h The lms arenanocrystalline and/orare amorphous withhexagonal crystalstructure. The opticalband gap was found tobe 3.72 eV

[66]

4. 0.4 M ZnCl2 0.4 M nitrilatriaceticacid (NTA)NaOH CS(CH3eNH2)

5 500 nm 343 Glass, quartz 6 h The ZnS lms arenanocrystalline andhave a cubic structure

[67]

5. 0.015 M Zn(CH3COO)2 0.007 Msodium citrate 0.6 M NH3 0.1 MSC(NH2)2

9.5e10.5 90 nm 355e359 Glass 250 min The ability of ZnS lmsto exhibit luminescentproperties

[68]

6. 0.5 M ZnSO4 0.5 M CS(CH3eNH2) e e 303e368 Glass, FTO 90e120 min Deposited lms arehighly transparent,adherent andnanocrystalline

[69]


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Table 1 (continued)


Substratesused


7. 1 M Zn(CH3COO)2 3.75 MtriethanolamineNH3 1M CS(NH2)2

10.55 e 353 Glass 3e4.5 h The thin lms havehexagonal phase andpreferred orientation inthe (008) plane. Thegrain sizes areestimated to be in therange of 40e82 nm. Thelms possess 66e87%transmittance in thevisible region

[70]

8. 1 N Zn(NO3)2 hydrazine 0.5 NNH4(NO3) nitrateNH4OH 1 NCS(NH2)2

10e10.6 0.18e0.25 mm 353 Glass 2 h The lms deposited ata pH 10.6 showeda resistivity ofz104 U cm. The bandgap of the lms variedfrom 3.66 to 3.93 evuseful for window layerfor solar cells

[71]

9. 0.2 M Zn(CH3COO)2 0.6 M CS(NH2)2NH3 hydrazine hydrate/trisodium citrate

10 220 nm 353 Glass 4 h The thin lms weresurface homogeneouswith pure wurtzitestructure and theoptical band gap of thelm was 3.53 eV

[72]

10. 0.1 M CS(NH2)2 0.08 M Zn(en)3SO4 4 M NaOH

Alkaline e 333 Glass, PE,PET 10 h The ZnS lms showedemission peaks at ca.450 and 485 nm

[73]

11. 0.2 M Zn(CH3COO)2 0.2 M CS(NH2)2NH3

8e11 76e332 nm 307e318 Glass 21 h The thermoelectricpower measurementshowed that the lmswere of n-type

[74]

12. 0.1 M Zn(CH3COO)2 0.15 M CS(NH2)2 0.2 M tartaric acid 0.1 Mtrisodium citrate

10 e 363 Glass 90 min Average transmittanceof 82.2% in the spectrarange from 350 nmto 800 nm and theoptical band gap isabout 3.76 eV wereobtained. Useful inelectroluminescent andphotovoltaic devices

[75]

13. 1 M Zn (CH3COO)2 0.2 MNa2EDTANaOH 0.4 M CS(CH3eNH2)

6 450 nm 343e346 Glass 30 mine7 h The lm showed a cubiczinc blend structureand a diameter of about2e5 nm for ZnSnanocrystals and 70%transmittance in thevisible region. Thedirect band gap rangedfrom 3.68 to 3.78 eV

[76]

14. 0.045 M Zn(CH3COO)2 0.065 M CS(NH2)2 0.133 M tartaric acid 80% hydrazine hydrate

10 110 nm 358 Glass 3 h Well-crystallized lmwith pure-wurtzitestructure afterannealing. The lmsshow hightransmittance in thevisible region and theband gap valueestimated to be 3.69 eV

[77]

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15. Zn CS(NH2)2 Alkaline 200 nm e Glass, quartz, ITO e Thiourea acts asa complexing agent aswell as a source ofsulphide ions. The lmshave a cubic (zincblende) structure withoptical transmittanceabove 75% in thevisible region

[78]

16. ZnSO4 trisodium citrateNH4OH CS(NH2)2

e e 333e353 Glass 50 min Films were depositedusing a novelcomplementarycomplexing agent,sodium citrate

[79]

17. 1 M ZnCl2 10 M NH3 1 M TEA 1 M CS(NH2)2

11.2 e 313 Glass 3 h After thermal oxidationZnS is converted in toZnO thin lms

[80]

18. 0.1 M Zn(CH3COO)2 (0.025e0.4)M CS(CH3eNH2)

6.5 39e199 nm 323e263 ITO 120 min The lm isnanocrystalline

[81]

19. 0.01 M ZnSO4 0.3 M CH3COOH 0.5 M CS(NH2)2

2 38e195 343 Glass, Au, CuInS2 e The absorptioncoefcient depends onthe CBD depositiontime, and showedabsorption edgesbetween 2.70 and3.65 eV

[82,83]

20. 0.01 M ZnSO4 1 M NH3 0.051 MCS(NH2)2

Alkaline 45 nm 333 CIS 45 min Used as a buffer layer inCIS electrodepositedsolar cells

[84]

21. 0.01 M ZnSO4 0.06 MNa2S2O3H2SO4

3.5 0.15 mm 300 Glass e The lms were nearlystoichiometric andshowedphotosensitivity

[85]

22. 0.16 M ZnSO4 7.5 M NH3 0.6 MCS(NH2)2

e 100 nm 353 CIGS 15 min Used as a buffur layer inCIGS solar cells

[86]

3. Mercury sulphide (HgS)1. 0.1 M Hg(CH3COO)2 0.1 M CS

(NH2)2 triethylmine 30% NH38 133 nm 300 Glass, FTO 4 h The nanocrystalline

HgS lm is depositedwith face centeredcubic structure. TheEDX showed theformation of sulphurrich HgS thin lms. Theoptical band gap of thelm was found to be2.75 eV and showedPEC properties inpolyiodide electrolyte

[87]

2. 0.05 M HgCl2 0.1 M Na2S2O3 2e3 510e1815 273e358 Glass, FTO 45 mine75 h The lms arephotoactive inpolysulphide andpolyiodide electrolytes.The Blue shift wasobserved in spectralresponse of HgS lmswith decrease in lmthickness due tosmaller grain size

[88]


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Table 1 (continued)


Substratesused


4. Silver sulphide (Ag2S)1. 0.1 M AgNO3 1 M

Na2S2O3 0.5 M dimethylthiourea(DMTU)

Alkaline 300 nm 343 glass 7 h The optical band gap isindirect forbidden,1 eV. The electricalconductivity is of theorder of 103e104

(U cm)1. The highoptical absorptioncoefcient in the visibleregion, >105 cm1

[89]

5.Manganese sulphide (MnS)1. 0.1 M Mn(CH3COO)2 98% TEA

0.1 M NH4Cl 80% hydrazinehydrate 0.1 M CS(CH3eNH2)

10.5 800 nm 313e343 glass 6 h The crystalline MnSthin lm is depositedand HF etching studied.

[90, 91]

2. Mn(CH3COO)2 3.75 MtriethanolamineNH3/NH4Cl 0.7 M trisodium citrate 1 M CS(CH3eNH2)

10.55 1120 nm 300 Glass 24 h The deposited lms areof single-phasewurtzite crystalstructure andpreferential orientationalong the c-axis.Trisodium citrate hasa signicant inuenceon the crystallization ofthe lm

[92, 93]

6. Bismuth trisulphide (Bi2S3)1. 0.1 M Bi(NO3)3 0.1 M EDTA

0.1 M CS(CH3eNH2)2.5 437 nm 279 Glass 25 min The lms were

nanocrystalline. Theoptical band gapenergy, crystal size, andelectrical resistivity oflms are found to belm thicknessdependent

[94]

2. 0.1 M Bi(NO3)3 1 M Na2S2O3 2 e 333 Glass e The lm material is theorthorhombicmodication ofbismuth(III) suldewith stibnite type ofstructure

[95]

3. 0.1 M Bi(NO3)3 0.1 M EDTA 0.1 M CS(CH3eNH2)

e e 279 Glass 5 Deposited lms arenanocrystalline

[96]

4. 0.2 M Bi(NO3)3 0.2 M Na2 EDTA 0.2 M Na2S2O3

0.5e1.5 145e195 nm 300 Glass e The band gap energywas decreased withincreasing at% ofsulphur in Bi2S3

[97]

5. 1 M BiCl3 4 M Na2S2O3 e e 323 Glass, plastic 2 h The broadorthorhombic Bi2S3peaks were observedafter annealing at 573 K

[98]

6. 0.1 M Bi(NO3)3 TEA 0.1 M CS(CH3eNH2)

8.5 e 328 Glass 90 min The optical gap of Bi2S3was 1.62 eV

[99]

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7. Bi(NO3)3NH4OH CS(NH2)2 e 0.51e0.65 mm Glass 6e7 h The spectraldistribution of theabsorption coefcientshowed the existenceof an indirect energygap. The values ofEg 1:43 eV and theEg 0:51 eV, suggestan allowed non-verticalabsorption

[100]

8. Bi(NO3)3Na2S2O3 2 e 333 Glass e Deposited lm isnanocrystalline andstudied PEC properties

[101]

9. 0.1 M Bi(NO3)3 0.1 M CS(CH3eNH2)

1.5e1.6 e 298 Glass, FTO 5 h Films were deposited innon-aqueous medium.Films showedphotovoltaic activity inpolysulphideelectrolyte

[102],

10. Bi(NO3)3 TEA CS(CH3eNH2) e e 27 Glass, 20e24 h Electro polymerizationof pyrrole onto Bi2S3lms, and thecodeposition of Bi2S3nanoparticles onto thesame substrates wereachieved

[103]

7. Antimony trisulphide (Sb2S3)1. 0.1 M SbCl3 0.1 M tartaric acid

0.1 M CS(CH3eNH2)e e 279 Glass 4 h The lms are

nanocrystalline withorthorhombic crystalstructure

[104]

2. 650 mg SbCl3 1 M Na2S2O3 3.5 e 300 Glass 30 mine5 h Upon heating innitrogen, these lmstransformed intopolycrystalline withstibnite structure. Thevalues of optical bandgap energy wereevaluated as 2.57 and1.73 eV for the as-deposited lm and thelm annealed innitrogen, respectively

[105]

3. 0.1 M SbCl3 0.1 M tartaric acid 0.1 M CS(CH3eNH2)

2 200 nm 279 Glass 4e20 h The optical band gapenergy isproportionallydecreased, the inverseof the grain size. Sb2S3lms showed n-typeconducting behavior.Films are stable inpolyiodide PEC cells

[106e108]

4. 650 mg SbCl3 1 M Na2S2O3 e 500 nm 283 Glass 6 h Used for photovoltaicsolar cell application

[109]


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Table 1 (continued)


Substratesused


8. Arsenic trisulphide (As2S3)1. 0.1 M As2O3 0.1 M CS(CH3eNH2)

0.1 M Na2EDTA2.5 185e520 nm 279 Glass 4e20 h The lms are found to

be amorphous orconsisting ofnanocrystalline grainsonto glass substrates.The AS2S3 is a directband gap material andband gap energydecreased from 2.58 to2.20 eV with increase inthickness from 185 to520 nm

[110,111]

2. As(III) solutionNa2SO3 2

3. 0.025 M InCl3 0.5 M CSCH3eNH2) 0.01 M HCl 0.3 M acetic acid

e e 343 Glass, ITO 25 min Tetragonal b-In2S3 wasobtained

[118, 119]

4 0.025 M InCl3 0.1e0.65 M CS(CH3eNH2) acetic acid

2.35e2.45 e 343 Glass 45e90 min Films contained b-In2S3(440) phase

[120]

5. 0.1 M InCl3 0.5 M acetic acid 1 M CS(CH3eNH2)

2.5 150 nm 303 Glass 48 h Annealing processinduced a structuraltransition froma mixture of cubic andtetragonal phases to thetetragonal one

[121]

6. 0.025 M InCl3 0.1 M CS(CH3eNH2) acetic acid

e 1220 343 Si, glass 25 min The lms are composedof amixture of the cubica- and b-In2S3 phases.The lm showed thesulphur deciency ofthe samples. S/In ratiosbetween 0.5 and 1.2

[122]

7. 0.1 M In2(SO4)3 1 M CS(CH3eNH2) 0.7 M acetic acid

>2 1 mm 353 Glass 40e80 min The lms werepolycrystalline withcubic crystal structure.The direct band gap of2.84 eV for as-preparedindium sulphide lms.The b-In2S3 thin lmused as a buffer layer ofCIS thin lm solar cell

[123]

8. 0.025 M InCl3 0.1 M CS(CH3eNH2) 0.1 M Acetic acid

e e 338 TiO2 1 h Used in ETA solar cellapplication

[124]

11. Lead sulphide(PbS)1. Pb(NO3)2 CS(NH2)2 0.69 M

NaOH 0.1 g SbCl311 e 297 Glass 60 min The infra-red (IR)

photosensitivityincreased of about 1000times when a reducingagent (hydroxylaminehydrochloride) is addedin the deposition bath

[125]

2. 0.0498 M Pb(NO3)2 0.02 M NaOH 0.118 M CS(NH2)2 PVA

e e 283e303 Glass, stainlesssteel

1 h The band gap values aremuch higher than thebulk value (0.41 eV)due to quantumconnement of thecarriers in thenanocrystallites

[127]

3. 0.5 M Pb(NO3)2 2 M NaOH 1 MCS(NH2)2 1 M triethanolamine

e e 283e303 Glass 60e120 min The lms were cubicphase with a preferredorientation growthalong the (200)direction

[128]

4. Pb(NO3)2 CS(NH2)2NaOH e 1650e2650 nm e Glass e Preferable (100) latticeplane orientationparallel to the substratesurface. All PbS crystalsshowed a triangularshape grains

[129]


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Table 1 (continued)


Substratesused


5. 0.175 M Pb(NO3)2 0.1 M CS(NH2)2NaOH

e 800 nm 298 Glass 10e90 min PbS with face-centeredcubic structure orientedaccording to the (200)perpendicular directionto the plane of thesubstrate

[130]

6. 0.01 M Pb(NO3)2 0.05 M CS(NH2)2 0.27 M NaOH

e 650 nm 293 GaAs(001) 1440 min The reagentconcentration hasa profound effect on themicrostructure of thelms and on themorphology evolution

[131]

7. (0.01e0.175) M Pb(NO3)2 (0.057e1) M CS(NH2)2 (0.146e0.57)MNaOH

>12 1000 nm 313 GaAs(111), (100) 20e60 min Depositiontemperature anddeposition time playa major role inobtainingmonocrystalline PbSlms.. The domain sizeincreased with lmthickness, resulting insingle-crystal lmswith fewer defects

[132]

8. 0.1 M Pb(NO3)2 0.1 M CS(NH2)2 9 290 nm 300 Glass 2e7 h The room temperatureelectrical resistivity ofnanocrystalline p-typePbS thin lm was104 U cm

[133]

12. Copper sulphide (CuxS)1. 0.5 M CuCl2 1 M sodium citrate

1 M CS(CH3eNH2)e 100 nm 300 PES foil 4e8 h The polyethersulfone

(PES) foils were used asthe stable substrate

[134]

2. 0.5 M CuCl2 3.7 M TEA 7.6 MNH3 1 M NaOH 1 M CS(NH2)2

8 30e40 298 Glass, Si 4 h The phasetransformation of theas-deposited CuxS lmfrom Cu2S to CuS at 473e573 K

[135]

3. 0.1 M CuSO4 1 M CS(NH2)2 TEA 11 200 nm 298 Glass 5e6 h Used for gas sensorapplication

[136]

4. 0.3 M CuCl2 0.3 M (CH3)NHCSNH(CH3) 0.3 M Na2S2O3

2.3 200 nm 343 Glass 3.5 h The lms were usefulfor opto-electronic andgas sensor applications

[137]

13. Cobalt sulphide (CoS)1. 0.001 M CoCl2 0.05 M Na2S

NH4OH>8 250 nm 333 Glass 2 h The lm is of indirect

band gap of 1.10 eV[138]

2. 0.5 M CoCl2 3.75 M TEANH3/NH4Cl CS(CH3eNH2)

10 650 nm 323, 300 Glass 95e175 min, 10e22 h

As-prepared cobalt (IV)sulphide lmsexhibited poorcrystallinity. Good-quality Co3S4 thin lmswere obtained afterannealing lms attemperatures between373 and 423 K

[139]

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14. Molybdenum disulphide (MoS2)1. 104 M Mo(NH4)2 (ammonium

molybdate) 1.5 M sodiumdithionite 1.5 M CS(CH3eNH2)

e e 300e363 Glass, quartz 30 mine5 h The lms are type-IIMoS2 lm with bandgap of about 1.87 eV

[140]

2. 0.2 M(NH4)2MoS4NH3 hydrazinehydrate

10 0.6 mm 333 Glass 1 h The annealed lmshowed about 80%transmission in thevisible range. The directband gap value was of1.74 eV, which agreedwell with the valuecharacteristic MoS2single crystal

[141]

3. 0.025 M (NH4)2[Mo(2N(CH2eCH2eO)3 0.025 M CS(CH3eNH2) TEA

9.5 e 338 Glass 90 min The lms areamorphous with bandgap 1. 86 eV

[142]

15.Thallium sulphide (Tl4S3 or Tl2S)1. 0.2 M Tl(NO3)2 1 M sodium

citrate 1 M NaOH 1 M CS(NH2)2e e 308e323 Glass, ZnS Few hourse4 days The lms are

photoconductive in thenearly amorphous Tl4S3composition or in Tl2S.Direct forbiddentransition with a bandgap of 1.12 eV

[143]

B. Metal selenide thin lms1. Cadmium selenide (CdSe)1. 0.1 M CdSO4 0.13 M

Na2SeSO3NH39e10 600e2400 273e358 Glass 45 mine75 h Due to the variation of

grain size and lmthickness, the electricalresistivity increasedand lms showed `blueshift of 0.5 eV

[144]

2. 0.0038 M CdCl2 0.01 M CSe(NH2)2 0.10 M NaOH 0.5 MNH4NO3

Alkaline 0.2 mm 348 Glass e The PL emission in thelow quality chemicallydeposited CdSe lmswas modieddrastically by laserannealing treatment inair

[145]

3. 0.5 M CdSO4 0.7 M K3NTA 0.4 MNa2SeSO3

9.5 100e300 nm 300 Glass 22 h Preparation of highquality lms of CdSenanocrystals. Thenanocrystal radii are 1.9e10 nm, which meanstailoring the band-gapbetween 500 and710 nm

[146]

4. 0.05 M CdSO4 0.05 M tartaric acidNH3 KOH 0.0625 M Na2SeSO3

12 0.22 mm 293 Glass 3 h N-type CdSe depositedin hexagonal phase,having optical band gap2.01 eV. The electricalresistivity was of theorder of 106 U cm

[147]

5. 0.01 M CdCl2 0.1 M KOH 0.5 MNH4NO3 0.01 M CSe(NH2)2

8.5 e 338 Glass 15 min After air annealing, thegradual phasetransformation fromcubic modication tohexagonal wurtzite (W)stable phase

[148]


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Table 1 (continued)


Substratesused


6. 1 M Cd(CH3COO)2 1 MNH3 0.25 M Na2SeSO3

e 0.43 mm 300 Glass 5 h The lms are n-typesemiconductor withelectrical resistivity ofthe order of 106 U cm

[149]

7. 1 M Cd(NO3)2 1 M TEA 25%NH3Na2SeSO3

e 1 mm 333 Glass 2 h The optical energy bandgap decreased form1.93 to 1.70 eV with theincreasing annealingtemperature

[150]

8. 0.1 M CdCl2 0.1 MNa2SeSO3 4 M NH4OH

11e12 100 nm 303e363 Glass e The lms deposited at333 K and lowertemperaturescrystallize in the cubicphase while the lmsprepared at 363 Kpresent a mixture ofcubic and hexagonalphases

[151]

9. 0.02 M CdSO4 1 M sodium citrate 0.1 M Na2SeSO3

8.5 e 338 Ti, Nickel, ITO 1 h The lms are ofhexagonal phase crystalstructure. The Eg forCdSe thin lm was1.80 eV. The lms arephotosensitive

[152]

10. 0.5 M Cd(CH3COO)2 25%NH3 0.25 M Na2SeSO3

10 0.25 mm 300 Glass 3e15 h The lms grew withNanocrystalline cubicphase, with band gap2.3 eV and electricalresistivity of the orderof 106 U cm. Airannealing increasedcrystallinity of the lmsalong withrecrystalization process

[153, 154, 155]

11. 1 M Cd(NO3)2 1 M TEA 15.2 MNH3 0.45 M Na2SeSO3

Alkaline e 343 TiO2 6 h The sensitization ofscreen printed andspray-painted titaniumdioxide coatings werecarried out withCdSe lms

[156,157]

12. CdSO4Na2SeSO3 with Sb3doping concentration from 0.005 to5 mol%

10 400 nm 333 Glass 30e90 min The crystallite sizedepends on the dopingmol% of antimony inCdSe and maximum at0.1 mol% Sb conc. inCdSe. The optical gapdecreased typicallyfrom 1.79 to 1.61 eVwith the increase in Sbcontent from 0 to0.1 mol% and thenincreased further onthe higher doping side

[158]

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13. 1 M CdSO4 TEANaOHNH3Na2SeSO3with doping of Tl(III)SO4 solution

10.5 e 333 Glass 90 min The lms are cubicstructured. The energygap decreased up to1.55 eV andconductivity increasedby one order ofmagnitude, as the Tl(III)concentrationincreased up to0.07 mol% of Tl3

[159]

14. 1 M CdSO4 0.01 N Hg(NO3)2 25% NH3 0.25 MNa2SeSO3

Alkaline e 300 Glass 3 h The lm showed cubicstructure. Optical bandgap of CdSe waspractically constant upto 0.05 mol% Hg dopinglevel, while it decreasedlinearly for higher Hgcontent. CdSe lmswith 0.05 mol% of Hgshowed higherabsorption coefcient,higher conductivity

[160]

15. 0.057 M CdSO4 0.08 M Na2SeSO3 7e8 e 300 e e The color changeduring the reactionwas due to sizequantization of theCdSe nanocrystals.This was correlatedwith the measuredCdSe crystal sizes

[161]

2. Zinc selenide(ZnSe)1. 0.2 M ZnSO4 1 M tartaric acid

2.8 M NH3 2% hydrazinehydrate 0.25 M Na2SeSO3

11.45 0.2 mm 333 Stainless steel 120 min The photo electrodeshowed n-typeconductivity. The llfactor and conversionefciency for the cellare maximum fora photo electrodeannealed at 473 K

[162e164]

2. ZnSO4Na2SeO3 Weak acidic e 300 ITO e The as-deposited lmswere amorphous

[165]

3. 0.03 M ZnSO4 0.015 M CSe(NH2eNH2) 1.4 M NH3 0.03 MNa2SO3 1.6 M NH2eNH2

11.5 e 323 Glass, SnO2 coatedglass sub.

60 min On glass substrate,amorphous lms aregrown with higherproportion of ZnSe. It isfound that thecomposition of lmsgrown on SnO2 hashigher proportion ofZnO than lms on glasssubstrate

[166, 167]

4. 0.25 M Zn(CH3COO)2 0.25 MNa2SeSO3 25% NH3 80%hydrazine hydrate 1 M NaOH

11 0.25 mm 343 Glass 5 h The lms showed red-shift of 0.15 eV afterannealing

[168]


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Table 1 (continued)


Substratesused


5. 1 M ZnSO4 2 M NaOH 80%hydrazine hydrate 1 M Na2SeSO3

e 300 nm 333 Glass 1 h Band gap energy of as-deposited three-dimensionally connedZnSe quantum dots isstrongly blue-shiftedwith respect to the bulkvalue

[169]

6. Na2SeSO3 ZnSO4 TEANH3 12 e 300 ITO e The nanostructure lmsexhibited a size-dependent blue shift

[170]

3. Bismuth triselenide (Bi2Se3)1. 0.1 M Bi(NO3)3 0.1 M sodium

citrate 10% NH3Na2SeSO3Alkaline 200 nm 333 Glass, polyester e The deposited lms are

amorphous with bandgap energy of 2.3 eV,which does not exhibitsignicant changesupon annealing

[171, 172]

2. 0.1 M Bi(NO3)3 0.1 M Na2SeSO3 8.2 35 nm 328 Glass 2 h The lms aremicrocrystalline. Directtransitions with a bandgap of 0.97 eV

[173]

3. Bi(NO3)3Na2SeSO3 9 e 300 Glass and FTO Deposited lms arephotosensitive

[174]

4. 0.01 M Bi(NO3)3 0.05 M K(SbO)C4H4O6 0.01 M Na2SeSO3

Alkaline 0.34 mm 300 Glass 2 h The Bi2Se3eSb2Se3lms are uniform andnanocrystalline. Theoptical band gap ofBi2Se3eSb2Se3 lieswithin the band gaps ofBi2Se3 and Sb2Se3.Annealing of Bi2Se3eSb2Se3 lm at 448 Kfor 4 h results in slightimproved crystallinity

[175]

5. Bi(NO3)3Na2SeSO3 doping withSb3

10 e 318 Glass e The lms aremechanically stable.Optical measurementrevealed a band gaptailoring when Sbdoping in the lmis varied

[176]

4.Antimony triselenide (Sb2Se3)1. 0.2 M K(SbO)C4H4O6 TEA

hydrazine hydrate (80%) 0.1 MNa2SeSO3

e e e Glass 10 h The lms arenanocrystalline withorthorhombic crystalstructure

[104]

2. (a) 0.1 M K(SbO)C4H4O6 3.7triethyanolamine 30%NH3 0.4 M Na2SeSO3

Alkaline 0.1e0.4 mm 288e303 Glass 1e6 h; 3e12 h The deposited lmsshowed an indirectband gap of 1e1.2 eV.The lms arephotosensitive

[177]

(b) SbCl3 1 M sodium citrate 30% NH3 0.4 M Na2SeSO3(c) 0.05 g SbCl3 1 M sodiumcitrate 30% NH3 0.1 MNa2SeSO3

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5. Lead selenide (PbSe)1. 0.25 M Pb(NO3)2 1 M tartaric acid

1 M KOH 0.25 M Na2SeSO3Alkaline 0.7 mm 293 Glass 3 h The lms are

polycrystalline in FCCstructure with welldened sphericalgrains. The electricalconductivity at roomtemperature is of theorder of 103 (U cm)1

[178]

2. 0.06 M Pb(CH3COO)2 0.05 MNa2SeSO3 0.6 M KOH

>13 e 303e313 GaAs 20e60 min The lm ismonocrystalline

[132]

3. 0.2 M Pb(CH3COO)2NH3 0.13 MNa2SeSO3

Alkaline 0.86 mm 300 Glass 28 h The nanocubes texturePbSe thin lmconsisting of preferredorientation along the(200) plane

[179]

4. 0.25 M Pb(NO3)2 0.25 MNa2SeSO3 6 M NaOH

10e11.5 e 343e363 Glass, quartz e The lms grew withtypical rock saltstructure of PbSe andthe lattice parametershowed a slightincrease with decreasein the grain size

[180]

5. 0.06 M Pb(CH3COO)2 0.05 MNa2SeSO3 trisodium citrate 0.6 M KOH

10.5e13 e e Glass e Films deposited from(higher pH) KOH bathsconsisted of ca. 4 nmPbSe nanocrystalsembedded in anamorphous leadoxide matrix

[181]

6. Copper selenide (CuSe)1. 0.1 M CuCl2 30% NH3 0.1 M

Na2SeSO310 0.37 mm 300 Glass 6 h The direct band gap of

2.03 eV. Semi-conducting behaviorwas observed

[182]

2. 0.1 M CuSO4 0.1 M trisodiumcitrate 0.1 M Na2SeSO3 0.1 MNaOH

9e12 200 nm 333 Polyester 15 min Synthesized Cu3Se2 andCuSe thin lms

[183]

3. CuCl2 TEANa2SeSO3NH4OH Alkaline 0.12e0.18 mm 300 Glass 15e180 min Both as-deposited andannealed lms showvery low resistivityabout 105 Um. Theband gap for directtransition varied in therange of 2.0e2.3 eV andfor indirect transition inthe range of 1.25e1.5 eV

[184]

4. 0.2 M CuSO4 0.3 M trisodiumcitrate 0.2 M Na2SeSO3

Alkaline e 283e300 Glass, FTO 30e70 min The lms of Cu2xSe andCu3Se2 phases could beprepared either byvarying the Cu:Se ratioin the reaction bath orby controlling the pH

[185]

7. Molybdenum diselenide (MoSe2)1. 0.25 M (NH4)2[Mo(2N(CH2eCH2

eO)3)] TEA 0.25 M Na2SeSO39.5 e 338 Glass 90 min MoSe2 nanocrystals

were deposited[142]


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Table 1 (continued)


Substratesused


2. 0.2 M ammonium molybdate 1 Mtartaric acid 10% hydrazinehydrate 0.25 M Na2SeSO3

Alkaline 0.4 mm 353 Glass 3 h The deposited lms arepolycrystalline and n-type with optical bandgap of 1.43 eV

[186]

8. Tin selenide (SnSe)1. 0.94 g SnCl2NaOHNa2SeSO3 11.4 63 nm 318 Glass, FTO 2 h The lms were

polycrystalline withpreferred orientationalong the [201]direction. The directband gap was found tobe about 1.25 eV. Theselms are used in PECcells

[187]

2. 0.1 M Na2SeSO3 4.4 M acetic acid Se thin lms heating a vacuumdeposited Sn thin lm in closecontact with the Se thin lm at473 K in nitrogen atmosphere

4.5 300 nm 297 vacuum evaporatedSn Glass

2 h An optical band gap of 1e1.27 eV, electricalconductivity of 0.01e0.2 U cm1 and thephotoconductivity ofthese materials fulllthe basic requirementsfor their integrationinto photovoltaicstructures

[188]

3. SnCl2 EDTANa2SeSO3NH4OH 9 e 333 Glass 3 h The SnSe orthorhombiccrystalline nanocrystalsdeposited as thin lms.The lms arecharacterized byindirect band gapenergy of 1.20 eVwhichexhibits a slight redshift to 1.10 eV uponannealing

[189]

9. Indium selenide (In2Se3)1. 0.2 M InCl3 1 M tartaric acid

10% hydrazine hydrate 0.25 MNa2SeSO3

12 0.55 mm 293 Glass 2 h The direct optical bandgap was 2.35 eV andspecic electricalconductivity was 102

(U cm)1

[190]

C. Mixed metal chalcogenide thin lms1. Cadmium sulphoselenide (CdSSe)1. 0.1 M CdCl2 0.1 M

Na2SeSO3 0.1 M CS(NH2)210 e 333 Glass, TiO2

deposited lms45 min Films were cubic,

hexagonal or mixed instructure andamorphous. Eg wasvaried from 2.5e1.8 eVwhile going from CdS toCdSe and r was3.3 106e7.2 104 U cm. lmswere n-type. Used inPEC solar cells

[191]

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2. Cd(CH3COO)2 CS(NH2)2Na2SeSO3 (InCl3 wasdoped from 0.01 to 1 mol%)

10.4 e 328 Glass, FTO coatedglass

75 min PEC cell performancewas improved afterdoping and is optimumat 0.05 mol% In doping

[193]

2. Cadmium zinc selenide (CdZnSe)1. CdSO4 ZnSO4Na2SeSO3 TEA

NH310 0.2e0.6 mm 343 Glass 3 h The optical gap

estimation showeda non-linear increase inthe band gap withincreasing Zn contentin the lm

[193]

2. 0.1 M Cd(CH3COO)2 0.5 M Zn(CH3COO)2NH3 0.25 MNa2SeSO3

Alkaline 0.23 mm 343 Glass 4 h The lms arenanocrystalline. Opticalband gap ofCd0.5Zn0.5Se in betweenindividual band-gaps ofCdSe and ZnSe and thedark electricalresistivity was about107 U cm. Films ndapplications as a bufferlayer in solar cells

[194]

3. 0.2 M CdSO4 0.2 M ZnSO4 2.5 Mtartaric acid 2% hydrazinehydrate 0.2 M Na2SeSO3

12 0.5 mm 300 Glass 240 min The lms are highlyabsorptive and showdirect type of transition

[195]

3. Cadmium lead selenide (CdPbSe)1. 0.25 M CdSO4 1 M tartaric acid

25% NH3 0.25 M Pb(NO3)2 1 M potassium hydrazine 0.25 M Na2SeSO3

12.35 0.58 mm 293 Glass 180 min Band gap decreasedmonotonically assystem parameter x isincreased

[196]

4. Cadmium zinc sulphide (CdZnS)1. 0.5 M Cd(CH3COO)2 0.5 M Zn

(CH3COO)2 1 M CS(NH2)2 7.4 Mtriethanolamine 13.4 M NH3

Alkaline e 363e368 Glass 15 min The resistivity in therange 109e1014 U cm

[197]

2. 0.015 M Cd(CH3COO)2 0.01 M Zn(CH3COO)2 0.05 M CS(NH2)2 0.6 M NH3 0.1 MNH4(CH3COO)2. Indium lmsdeposited by vacuum technique

Alkaline 300 nm 348 Glass 40 min The effect thickness ofindium lms and theannealing temperatureon structural, opticaland electricalproperties of CdZnSlms studied

[198,199]

3. 0.1 M (CdSO4 ZnSO4) 0.05 M CS(NH2)2 1.5 M NH3

11.4 e 353 Glass e The as-deposited lmsare dominantly of cubicphase for all mixtureratios. The cubic phaseremained dominantuntil the annealingtemperature wasaround 673 K

[200]

5. Cadmium lead sulphide (CdPbS)1. 0.1 M CdCl2 0.1 M Pb

(NO3)2 0.05 M EDTA 1 M CS(NH2)2 25% NH4OH

11 e 333 Glass 30 min The band gap increasedwith increasing Cdcontent

[201]

1 M Cd(CH3COO)2 1 M Pb(CH3OO)2 1 M CS(NH2)2NH3

9.5e11 0.25e2.04 mm 300e333 Glass, FTO 1e20 h The lms are used inPEC solar cells

[202]


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Table 1 (continued)


Substratesused


6. Cadmium mercury selenide (CdHgSe)1. 0.25 M CdSO4/Hg(NO3)2 0.25 M

Na2SeSO3e 0.8 mm 293 Glass 3 h Films of all

compositions showedcubic structure. Theband gap variedmonotonically from1.82 to 0.8 eV as systemparameter x isincreased

[203]

2. 0.25 M CdSO4 0.25 M Hg(NO3)2 25% NH4OH appropriateamount of 0.01 M InCl3

e e 293 Glass, FTO 3 h The deposited lms arepolycrystalline withdirect Band gap energyvaried from 1.44 to1.8 eV as dopingconcentrationincreased from 0 to0.1 mol% indium. Theconductivity increasedup to 0.1 mol% indium

[160,204,205]

7. Copper bismuth disulphide (CuBiS2)1. 0.2 M Cu(NO3)2 0.2 M Bi

(NO3)2 0.2 M Na2SO3Acidic 2.2 mm 333 Glass 120 min Films are

polycrystalline with n-type semiconductorand showedphotosensitivity

[206]

8. Cadmium chromium sulphide (CdCr2S4)1. 0.25 M CdCl2 0.25 CrO3 0.25 M

Na2EDTA 0.25 M CS(NH2)210 424 nm 343 Glass, FTO 90 min PEC cell with ll factor

59% and deviceconversion efciency of0.3% was formed

[207,208]

9. Mercury chromium sulphide (HgCr2S4)1. 0.1 M HgCl2 0.1 M Cr2O3 0.1 M

Na2EDTA 0.1 M CS(NH2)210 264 nm 338 Glass 30 min The lms were

polycrystalline withhighly (220)preferential orientation

[209,210]

10. Copper indium diselenide (CuInSe2)1. Cu(NH3)42

InCl3Na2SeSO3 sodiumcitrate

e e 333 Glass 2 h Films arenanocrystalline

[211]

11. Lead manganese sulphide (PbMnS)1. 0.04 M Pb(CH3COO)2 0.05 M

MnCl2 0.04 M CS(NH2)29 280 nm 288e353 Glass, Si, quartz 20e120 min Optical band gap in the

Pb1xMnxSnanoparticle lmsvaried from 1.50 to2.50 eV by changing xin the range0.03< x< 0.37

[212]

D. Metal oxide thin lms1. Titanium dioxide (TiO2)

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1. 3 mM TiOSO4 1 350 nm 333 FTO 6 h Oriented rutile TiO2nanowires witha diameter ofw2 nmhave been preparedand studiedelectrochemical, electrochromic andphotoelectrocatalyticproperties

[213]

2. 0.1 M TiCl4 0.2 M H2O2 0.12e0.15 M HCl

e 30e40 nm 353 SnO2 0.5e1 h The SnO2 lm as theseed layer to preparenely patterning ofrutile TiO2 around353 K

[214]

3. 2 ml TiCl3NH3H2O2 20 mldeionized water

3 and 7.5 e 300 ITO 6 h The rutile andnanocrystalline TiO2thin lms in threedifferent colors bychanging the pH of theaqueous depositionsolution

[215]

4. TiCl3 (20e30% HCl)NH3 1e2 e 300 Glass, ITO 18 h The lms werenanocrystalline andcomposed of crystalgrains of 2e3 nm

[216]

5. 0.1 M (NH4)2TiF6 0.2 M H3BO3 e 150 nm 303 Si, glass, gold wire 10 h The lms areamorphous. The lmspre-treated at 773 K inair for 1 h created ananatase TiO2 crystallinestate

[217]

6. TiSO4H2SO4 and 0.034 M uorinecomplexed Ti (IV) solution 0.068 M H3BO3

e e 300 ITO,FTO e Anatase phase grew onboth SnO2: F and ITO.Amorphous TiO2deposits were obtainedfrom titanyl sulphate.All lms showedphotovoltaic behavior

[218]

7. 0.034 M uorine complexed Ti (IV)solution 0.068 M H3BO3

e 300e500 nm

Table 1 (continued)


Substratesused


11. 0.15 M H2TiF6 0.856 M H3BO3 e 262 nm 348 GaAs e For GaAs substrate with(NH4)2Sx treatment, theelectricalcharacteristics weremuch improved. Thebest lm and interfacequality was obtainedwith H3BO3

[224,225]

12. 0.05 M (NH4)2TiF6 0.15 M H3BO3 e 260e600 nm 323 FTO 2e48 h The lms showedstrong intensity of(004) plane

[226]

13. 0.15 M TiCl4H2O2 1 M HCl e 600 nm 333 Si,Pt/Ti/SiO2/Si 6 h The present routeprovides anatase thinlms with highdielectric constant

[227]

14. TiCl3Na2EDTANH3 4e6 e 300 ITO 6 h As-deposited andannealed TiO2 lmsexhibited smaller watercontact angles whichresult in poorperformance of dye-sensitized solar cells

[228]

15. 20% TiCl3NH3 3e3.5 e 300 ITO 5 h Presence of twoabsorption edges in UVspectra impliesexistence of separatephases rather thancomposite formation.The stability tests ofPEC cells wereperformed

[229]

16. 0.005 M TiOSO4 0.025 M H2SO4 e e

3. 0.1 M Zn(NO3)2 0.1 Mmethenamine

e e 363 ITO 12 h The (002) reection isgreatly enhanced.Different morphologiesof ZnO nanorods wereobtained

[234]

4. 0.5 M Zn(NO3)2 0.1 M ammoniumcitrate tribasic 0.5 M NaOH

e 150e600 nm 323 Glass 20 min The lms exhibitedpolycrystalline wurtzitestructure. The opticalband gap was 3.26 eV.The dark electricalresistivity was of theorder of 103 U cm

[235]

5. 0.1 M Zn(NO3)2 0.01 Mdimethylamineborane

5.5 120 nm 338e353 p-Si substrate e ZnO lms with a highcrystal density with c-axis orientation andhigh refractive indexwere obtained

[236]

6. Zn(NO3)2 hexamethylenetetramine (HMTA)

e e 338 Al2O3 ceramic plate 24 h A novel microspherewith nanometer holesseparated by thin akesand ZnO hierarchicalstructure with rod likebranches were formed

[237,238]

7. 0.5 mM Zn(CH3COO)2 0.3 mMPVP 0.11 M NaOH

e e 328 Sulfonatefunctionalizedsubstrate

4.5 The lms showedpreferential growth onthe substrate indirection of the (002)and the (100) planes ofthe zincite structure

[239]

8 0.136 M Zn(NO3)2 0.816 M CO(NH2)2 0.1 M EDTA

e e e Glass, FTO 20e80 min The addition of EDTAinuenced the crystalshape of ZnO depositedparticles

[240]

9. 0.4 M ZnCl2 0.1 M NH4Cl 5.3 MNH4(OH) 30% H2O2

10.3e10.5 0.7 mm 298e348 Glass, quartz 60 min Zinc peroxide (ZnO2)with cubic structureand optical band gap of4.2 eV is obtained. Afterannealing ZnO2transformed in tohexagonal ZnO with3.25 eV of optical bandgap

[241]

10. 0.025e0.1 M Zn(Ac)2 C6H12N4(variation ofaqueous/alcoholic solution)

e e 353 ZnO layeredsubstrate

24 h The ZnO lms/nanorods of highcrystal quality wereobtained

[242]

11. 0.025e0.1 M Zn(NO3)2 0.05 Mdimethylamine (DMAB)

e e 343 Si 3 h ZnO nanorods grew fastalong the c-axisdirection due to thehigh surface energy ofthe polar (0001) planewhen the concentrationof OH ions is low inthe precursor solution

[243]


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Table 1 (continued)


Substratesused


12. Zn(NO3)2NH3 e e 333e363 Zinc metal layeredSi.

6 h Only ZnO (001) peak,indicating that ZnO(0001) planes areoriented parallel to thebasal plane of the Sisubstrate

[244]

13. ZnSO4NaOH adding LiSO4 asa dopant

e e 340e360 Glass e The electricalconductivity ofZn1_xLixO lmsincreased withincreasing x. The valueof dielectric constantfor undoped lm ishigher than that for thedoped lms

[245,246]

14. 0.1 M Zn(NO3)2 0.0005e0.1 Mdimethylamineborane (DMAB)

6.2 e 333 Glass e Wurtzite ZnO lm withoptical band gap energyof 3.3 eV was prepared.Small amounts of boronatoms originating fromthe DMAB wereincorporated into ZnOgrain and gave thelattice expansion

[247]

15. 0.1 M Zn(NO3)2NH4OH 12 2e14 mm 323 ITO 1 h The synthesis of ZnOfragile-free lms up to14 mm thickness. DSSCsrendered a maximumconversion efciency of2.21% with IPCE of 46%for 11 mm thickness

[248]

16. 0.05 M Zn(NO3)2 1.0 M CO(NH2)2 0.005 M nitric acid

4 4 mm 353 FTO 6 h The DSSC using ZnO/N-719 photo anodeexhibited the highshort-circuitphotocurrent density of13.8 mA/cm2 and theconversion efciency of3.3% with thickness of4 mm

[249]

17. 0.05 M ZnSO4 0.2 MNa2SO3 0.1 mMNa2S2O3 0.0015 M NH4OH

11 e 300 ITO, p-Si, n-Si 60 min The lms were n-typeand photoconductive.The ozone (O3)bubbling sampleshowed betterrectication properties.Photovoltaic effectconrmed for the O3bubbling sample

[250]

18. 0.1 M Zn(NO3)2NH3 12 e 323 Glass 40e100 min The lms consisting ofsub-micron rodsoriented along (002)plane with hexagonalcrystal structure andexhibited goodsensitivity and rapidresponseerecoverycharacteristics to LPG

[251]

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19. 0.1 M Zn(NO3)2 0.03 Mdimethylamineborane

e e 333 Glass, SiO2 e ZnO lms of wurtzitestructure and themorphologies consist ofhexagonal column.peak (002) wasobtained

[252]

20. 0.5 M Zn(NO3)2 4 M KOH e e 303 Zinc foil 12 h Highly orienteduniform ZnOnanoneedle/Hexagonalnanorods arraysfabricated by oxidationof zinc foil in zincate ionsolution

[253]

21. 0.4 M (CH3COO)2 0.5 M EDTA 5 M NH4OH

10 e 353 Glass 7 h High-density verticallyaligned ZnO rod arrayswith a multistageterrace structure on Aunanoparticle coveredglass substrates. Thesolar cell performanceis 10 times better thanthat of the disorderedZnO

[254]

22. (a) 0.05 M Zn(CH3COO)2 hexamethylenetetramine

e e 300 FTO 3 h A high efciency DSSCof 3.2% is achievedusinga mercurochrome-sensitized and 6.2 mmthick NWeNPcomposite lm

[255]

(b) 0.02 M ZnAcHMTA 368

23 0.2 M Zn(CH3COO)2 0.2 M Cd(CH3COO)2 5 M NH3

10 e 353 Glass 7 h The preferredorientation of the lmgrowth in these lms isalong c-axis

[256]

3. Cadmium oxide (CdO)1. 0.05e0.2 M Cd(NO3)2NH3 12 e 300 Glass 24 h The lms with high

orientations along(111) and (200) planeswith porous nano-brous morphologywere obtained

[257]

2. 0.03 M CdCl2NH4OH Alkaline 180 nm 300 Glass 48 h The as-deposited lmsare amorphous andconverted in tonanocrystalline afterannealing. AnnealedCdO nanowires are 60e65 nm in diameterand length rangestypically from 2.5 to3 mm

[258]

3. 0.4 M CdCl2 5.3 M NH4OH 30%H2O2 Sn(CO3)y complex[(NaCO3 SnCl4)]

e 200 nm 318 Glass e The predominantphases of the as-grownand annealed lmswere, respectively,cubic CdO2 and CdO. Alllms exhibiteda transmittance around80%

[259]


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Table 1 (continued)


Substratesused

Deposition tim Remarks Ref.

4. 0.1 M Cd(CH3COO)2 0.2 M NaOH e e 323 Glass e The lms werenanocrystalline.The resistivity was102e103 U cm

[260]

4. Nickel oxide (NiO)1. Ni(NO3)2 CO(NH2)2 Alkaline >1 mm 373 Glass 1 h The lms are insulating

with p-typesemiconductor havingdirect optical band gapis 3.6 eV

[261]

2. 0.3e1 M Ni(NO3)2 1 M CO(NH2)2 Alkaline e 363 Glass, silicon wafers 30e150 min The lms correspond tothe transparentturbostratic phase a(II)Ni(OH)2. Afterannealing in air attemperatures above of573 K, the lms aretransformed to the NiOphase and show a grey/black color

[262]

3. NiCl2 triblock C0-polymer e e 303 FTO 3 days The lms used asphoto-cathodes ofp-type dye-sensitizedsolar cells

[263]

4. 0.03 M NiCl2 40% HF 25%NH4OH

7.5e8.8 550 nm 333 Glass 2 h The F and NH3 inreactive solutionsplayed important rolesin the lm growthprocess and thesolution. NiO thin lmswere obtained byannealing the Ni(OH)2thin lms at 673 Kfor 2 h

[264]

5. 1 M Ni(NO3) 1 M CO(NH2)2 6 0.9 mm 373 Glass 2 h The optical band gap forheat-treated lms is3.6 eV

[265]

6. 0.1 M Ni(NO3)2NH3 12 0.17mm 333 glass 80 min The specic capacitancewas 167 F g1. PorousNiO lms are promisingcandidate forsupercapacitors

[266]

7. 1 M NiSO4 0.25 M potassiumpersulphateNH3

Alkaline 200 nm 300 Glass, oxidizedsilicon

30 min The as-deposited lmcontained a-Ni(OH)2and 4Ni(OH)2$NiOOH$xH2Ophases, whichconverted to NiO afterthermal annealing

[267]

8. 0.25 M Ni(NO3)2 0.25 M CO(NH2)2 Alkaline 1.3 mm 363 Glass 3 h Films arenanocrystalline andused for gas sensorapplication

[268]

9. 1 M NiSO4 0.25 potassiumpersulphateNH3

Alkaline 480 nm 293 ITO 20 min Highly porous lm usedfor electrochromism

[269,270]

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e

5. Silver oxide (Ag2O)1. AgNO3 TEA Alkaline 1.2 mm 318e323 Glass, polyester 90 min The lms are uniform

and specularlyreective

[271]

6. Cerium oxide (CeO2)1. 0.02 M Ce(NO3)3 4.5 10e20 nm 303e343 Ni 30 min The lms mainly

consisted of cerium (IV)oxide with a cubicuorite structure whilethe surface was coveredwith hydroxyl group

[272]

2. 0.01 M Ce(CH3COO)3 0.02 MKClO3

e e 318 Glass e The lm had a highdegree of porosity of41.3%. This signicantlylowered the elasticstiffness of the lm andmagnied strainsdeveloped at variousstages of the entire lmgrowth process

[273]

7. Bismuth oxide (Bi2O3)1. 0.1 M Bi(NO3)3 TEA 0.2 M NaOH 9 1.4 mm 300 Glass 60 min As-deposited lm

showed the presence ofmixed phases oftetragonal b-Bi2O3,monoclinic Bi2O3 andnon-stoichiometricphase Bi2O2.33. Afterannealing monoclinicphase of bismuth oxidewas obtained

[274]

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xincluding solar control coatings, solar energy conversion, electronic

pliedeposited Bi2S3 thin lms from aqueous medium and studiedoptical and PEC properties. Mane et al. [102] synthesized Bi2S3 thinlms in non-aqueous medium. The structural, optical and electricalproperties showed improvement after annealing at 423 K in N2atmosphere. Films were photoactive in polysulphide electrolyte.Rincon et al. [103] deposited Bi2S3 nanoparticles and studiedelectro polymerization of pyrrole on thin lms.

4.1.7. Antimony trisulphide (Sb2S3)Antimony trisulphide (Sb2S3) is a promising candidate as

a target material in television cameras, microwave devices,switching devices and various optoelectronic devices. The band gap(Eg 1.78e2.5 eV) of Bi2S3 covers the maximum scan of the visibleand near infrared ranges of the solar spectrum. The nanocrystallineSb2S3 thin lms deposited by CBD have been studied for theirproperties [104e107]. Mane et al. [108] and Messina et al. [109]have used nanocrystalline Sb2S3 thin lms in solar cell applications.

4.1.8. Arsenic trisulphide (As2S3)Arsenic trisulphide (As2S3) has applications in optical imaging,

hologram recording, electro-optic information storage devices andoptical mass memories. Mane et al. [110,111] studied the effect ofthickness of nanocrystalline As2S3 lms on structural, optical andelectrical properties. The band gap energy of As2S3 lm wasdecreased from 2.58 to 2.20 eV with increase in thickness from 185to 520 nm. Decrease in electrical resistivity with increase in lmthickness has been attributed to the removal of defect levels. Thecomposite lm of crystalline As2O3 and As2S3 deposited by Mendezet al. [112] when heated at 423e473 K was transformed to As2S3thin lm.

4.1.9. Tin (II) sulphide (SnS)Tin sulphide (SnS) is a p-type semiconductor with a band gap of

1.2 eV, a value close to that of silicon, and acceptor levels are createdby double ionized tin vacancies. Therefore, thin lms of SnS areuseful as an absorber layer for solar cells. Tanusevski [113] depos-ited polycrystalline orthorhombic SnS thin lms. Avellaneda et al.[114,115] synthesized SnS thin lms useful as p-absorber lms inall-chemically deposited photovoltaic structures.

4.1.10. Indium sulphide (In2S3)Indium sulphide (In2S3) exists in different modications (a,

b and g). Its band gap varies between 2.0 and 2.45 eV, dependingupon composition. The Cu(In,Ga)Se2 based solar cell prepared withchemically deposited In2S3 buffer layer has reached the efciencies(15.7%) near to those obtained by devices made with the standardCdS buffer layer.

The structural, optical and electrical properties of nanocrystal-line CBDeIn2S3 thin lms have been studied [116e122]. The porousnetwork of nano-platelets of In2S3 thin lms has been deposited byPuspitasari et al. [123]. Wienke et al. [124] synthesized hydroxylIn2S3 thin lms on TiO2 electrode for extremely thin absorber (ETA)solar cells.

4.1.11. Lead sulphide (PbS)Chemically deposited lead sulphide (PbS) thin lms with its

direct band gap of 0.4 eV on glass substrates have satisied thebasic requirements for solar control coatings for window glazingapplications in warm climates, where a low transmittance(10e30%) in the visible region is to be coupled with an appreciablereectance for infrared radiation. The CBDePbS thin lms on glasssubstrate have been studied for various properties [125e130].Osherov et al. [131,132] deposited PbS thin lms on GaAs (100)single-crystal substrates and concluded that the reagent concen-

S.M. Pawar et al. / Current Ap150trations have a profound effect on the microstructure andand low temperature gas sensor applications. In the bulk form CuxSexists in ve stable phases where x falls in the range between 1and 2. Nair et al. [134] deposited CuS thin lms on polyethersulfonefoil. Amorphous CuxS lms in the phase of chalcocite (x 2)deposited on Si and glass substrates by Nien et al. [135] showeda homogeneous distribution of copper and sulphur based on theelectron energy loss spectrometer (EELS) elemental mappingimages. Sagade and Sharma [136] synthesized CuxS (x 1, 1.4, and2) thin lms on glass substrates and used in gas sensor applications.The amorphous CuxS thin lms were deposited by Bagul et al. [137]using thiosulphate as both complexing and sulphiding agent.

4.1.13. Cobalt sulphide (CoS)Cobalt sulphide (CoS) is a semiconductor with band gap energy

equal to 0.9 eV, has potential applications in solar selective coat-ings, IR detectors and as a storage electrode in PEC storage devices.The microcrystalline CoS thin lms have been deposited on glasssubstrate by Yu et al. [138]. Eze [139] showed that after airannealing the lms transformed from Co3S4 to CoO. The decom-position of a 500 nm thick Co3S4 thin lm to a CoO lm involved thecreation of non-stoichiometric Co3S4, Co3S4 CoS2 mixed phaseand non-stoichiometric CoO. The CoO lms showed optical andelectrical properties, which make them potential candidates forultraviolet radiation lters and antireection coatings.

4.1.14. Molybdenum disulphide (MoS2)MoS2 crystallizes in three different types of structures, namely

2H, 3R and 1T-MoS2. MoS2 lms were prepared by Wei et al. [140]using Ni interlayer, which was deposited electrolessly on Sisubstrates. The deposited lms are type-II MoS2 lmwith band gapof about 1.87 eV. The nickel buffer layer favors the crystal growthoriented with the c-axis of the crystallites direction perpendicularto the substrate, which was ascribed to the formation of a liquidnickel sulphide. This may offer an easy method for the preparationof type-II MoS2 lm of better crystallite. MoS2 lms have beendeposited by Roy and Srivastava [141] on a glass/quartz substrateusing hydrazine hydrate as a reducing agent. The annealed lmsshow the formation of poorly crystalline 2H-MoS2 with a preferredorientation along c-axis and about 80% transmission in the visiblerange. Ajalkar et al. [142] deposited amorphousMoS2 thin lms andstudied structural, optical and electrical properties.

4.1.15. Thallium sulphide (Tl4S3 or Tl2S)Estrella et al. [143] synthesized thallium sulphide thin lms of

two different compositions, Tl4S3 or Tl2S, with different extent ofcrystallinity from chemical baths. When heated at differenttemperatures between 523 and 573 K depending on the lmthickness and bath composition, the lms tend to be crystallinewith structure and composition identical to that of the mineralcarlinite of composition Tl2S. The lmswere photoconductive in thenearly amorphous Tl4S3 composition or in Tl2S.

4.2. Metal selenide thin lms

4.2.1. Cadmium selenide (CdSe)Cadmium selenide (CdSe) is a promising semiconductor mate-

rial due to its wide range of technological applications in opto-morphology evolution of the lms. The nanocrystalline PbS thinlms deposited by Patil et al. [133] were used in PEC cells.

4.1.12. Copper sulphide (CuxS)Copper sulphides (Cu S) are potentially useful in a range of areas

d Physics 11 (2011) 117e161electronic devices such as PEC cells, solid state solar cells,

pliephotoconductors, gamma ray detectors, large screen liquid crystaldisplay, etc.

The properties of CdSe thin lms deposited by CBD have beenreported by many researchers [144e151]. Lokhande et al. [152]synthesized photoactive CdSe thin lms from ammonia-free bathusing sodium citrate as a complexant in weak alkaline bath(pH< 9.0). The nanocrystalline CdSe thin lms with band gap2.3 eV and electrical resistivity of the order of 106 U cm have beendeposited [153e155] from aqueous alkaline medium at roomtemperature. The sensitization of screen-printed and spray-paintedTiO2 coatings by chemically deposited CdSe thin lms has beenreported by Rincon et al. [156,157]. The structural, optical and PECcharacterization of the composite lms indicate the importance ofthermal treatments in improving the photocurrent quantum yieldand conversion efciency of the lms. The properties of Sb, Tl andHg doped CdSe thin lms have been studied [158e160]. Yochelisand Hodes [161] synthesized nanocrystalline CdSe by direct reac-tion between non-complexed Cd ions and sodium selenosulphate.The color changes during the reaction due to size quantization ofthe CdSe nanocrystals were correlated with the measured CdSecrystal sizes.

4.2.2. Zinc selenide (ZnSe)Zinc selenide (ZnSe) is a suitable candidate for red, blue and

green light emitting diodes, photovoltaic, laser screens, thin lmtransistors, PEC cells, etc. Also interest in ZnSeeGaAs heterojunctonhas greatly increased in recent years because of possible applica-tions in a number of high-speed optoelectronic devices. ZnSe isa promising candidate for the replacement of the toxic CdSmaterialin the buffer layer, due to its wide band gap (2.7 eV) than that of CdS(2.4 eV) and good lattice match with Cu(In,Ga)(S,Se)2.

The nanocrystalline ZnSe thin lms deposited on differentsubstrates like glass, stainless steel, ITO were used in solar cellapplications [162e167]. Kale and Lokhande [168] proposed the lmdeposition via cluster by cluster nucleation and growthmechanism.Air annealing was found to increase crystallinity of the ZnSe lmsalong with recrystalization process that changed nanocrystalline tometastable cubic to stable hexagonal phase with partial conversionof ZnSe into ZnO phase at high (673 K) annealing temperature.Pejova et al. [169] and Mazher et al. [170] deposited zinc selenidequantum dots in thin lm form on ITO coated glass substrates.

4.2.3. Bismuth triselenide (Bi2Se3)Bismuth selenide (Bi2Se3) has applications in various elds such

as PEC devices, solar selective coatings, optoelectronic devices,thermoelectric coolers and decorative coatings. Solid solutions ofbismuth selenide with bismuth telluride are well known thermo-electric cooling materials. The semiconducting Bi2Se3 thin lmshave been deposited on different substrates like glass, ITO, andpolyester [171e173]. The nanocrystalline Bi2Se3 thin lms preparedby Sankapal et al. [174] have been used in PEC solar cells. They alsodeposited nanocrystalline Bi2Se3eSb2Se3 composite thin lms[175]. Effect of Sb doping on structural, optical and electricalproperties has been reported [176].

4.2.4. Antimony triselenide (Sb2Se3)Antimony triselenide (Sb2Se3) has a ribbon-like polymeric

structure in which each Sb-atom and each Se-atom are bound tothree atoms of the opposite kind that are then held together in thecrystal by weak secondary bonds. Optical band gaps due to bothdirect and indirect transitions in the range of 1e1.13 eV are reportedfor Sb2Se3 lms. This makes it suitable for the use as an absorbermaterial in polycrystalline thin lm solar cells. Lokhande et al. [104]synthesized nanocrystalline Sb Se thin lms and studied their

S.M. Pawar et al. / Current Ap2 3properties. The amorphous Sb2Se3 thin lms were deposited fromchemical bath containing one or more soluble complexes of anti-mony and selenosulphate [177]. The heating of Sb2Se3 lms inpresence of selenium vapor at 573 K under nitrogen resulted in anenrichment of Se in the lms. The lms are photosensitive undertungsten halogen lamp illumination.

4.2.5. Lead selenide (PbSe)Lead selenide (PbSe) has a wide variety of applications in IR

detectors, photographic plates, photographic absorber, laser, etc.Hankare et al. [178] synthesized p-type PbSe thin lms on glasssubstrate. Osherov et al. [132] studied structural, optical and elec-trical properties of monocrystalline PbSe thin lms deposited onGaAs substrate. The nanocubes textured PbSe thin lms withpreferred orientation along (200) plane were deposited by Kale etal. [179]. The nanocrystalline PbSe thin lms have been depositedon glass and quartz substrates by Bhardwaj et al. [180] usingsodium selenosulphate, which acts both as a source of Se2 ionsand a complexing agent in the chemical bath. Sarakar et al. [181]synthesized PbSe thin lms of ca. 5 nm nanocrystals of PbSe withan oxidized and Se depleted surface.

4.2.6. Copper selenide (CuSe)Copper selenide (CuSe) is a semiconductor with a wide range of

stoichiometric compositions and also with various crystallographicforms for each of these compositions. Copper (I) selenide nds itsplace as a p-type material for solar cells and also as a super ionicconductor. Copper (II) selenide in the Cu3Se2 form has beenreported as an impurity along with copper (I) selenide used copperselenide as an absorber layer and has reported a Cu2xSe/CdSheterojunction solar cell with an efciency of 5.38%.

Polycrystalline

recent status of chemical bath deposited metal chalcogenide and metal oxide thin films

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