research article rutherford backscattering spectrometry...

Research ArticleRutherford Backscattering Spectrometry Analysis andStructural Properties of Zn

119909Pb1minus119909

S Thin Films Deposited byChemical Spray Pyrolysis

Abiodun E Adeoye1 Emmanuel Ajenifuja2 Bidini A Taleatu3 and A Y Fasasi2

1Engineering Materials Development Institute Akure 340223 Nigeria2Center for Energy Research and Development Obafemi Awolowo University Ile-Ife 220005 Nigeria3Department of Physics and Engineering Physics Obafemi Awolowo University Ile-Ife 220005 Nigeria

Correspondence should be addressed to Emmanuel Ajenifuja eajenifujacerdgovng

Received 8 June 2015 Revised 11 August 2015 Accepted 11 August 2015

Academic Editor Rodrigo Martins

Copyright copy 2015 Abiodun E Adeoye et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Zinc lead sulphide ternary thin filmswere prepared by chemical spray pyrolysis on soda lime glass substrates using zinc acetate leadacetate and thiourea sources precursor The films were characterized using Rutherford backscattering (RBS) spectrometry energydispersive X-ray (EDX) spectroscopy scanning electronmicroscopy (SEM) and X-ray diffractometry (XRD) RBS studies revealedvariation in thickness and stoichiometry of the films with respect to compositional substitution between Zn and Pb thereby givingeffective composition Zn

119909Pb1minus119909

S where 119909 = 0 0035 0069 0109 0176 and 0217 Film thickness obtained by length conversionranged from 8102 nm to 9003 nm Microstructural analyses also indicated that the growth and particle distribution of the filmswere uniform across substratersquos surface Diffraction studies showed that the films possess FCC crystalline structure Crystallite sizereduced from 1428 to 98 nm with increase in Zn2+ in the Zn

119909Pb1minus119909

S samples

1 Introduction

Thin films of metal chalcogenides particularly Pb Cd andZn have received much attention due to their importancein photovoltaic and optoelectronic semiconductor devicesmostly due to the fulfillment of some of the requirements thatare essential for device fabrication [1ndash3] Most importantlyternary chalcogenide semiconductors are of special interest inrecent time based on the fact that their energy gap and latticeparameters can be adjusted to enhance their optoelectronicand photovoltaic characteristics [4 5] Many studies havebeen carried out on ternary chalcogenide semiconductorthin films These include Zn

1minus119909Cd119909Se [1] Zn

1minus119909Fe119909S [6]

Cd1minus119909

Fe119909Se [7 8] Cd

1minus119909Zn119909S [9 10] and Cd

119909Pb1minus119909

S How-ever to the authorsrsquo knowledge little or no reports are cur-rently available on synthesis of Zn

119909Pb1minus119909

S chalcogenide thinfilms using spray pyrolysis method Despite the promisingand novel characteristics of chalcogenide semiconductorsthin films the use of this class of material in optoelectronic

devices may be held back by the difficulty in preparing chem-ically stable thin films with desired properties Hence sometechnical challenges have to be surmounted in order to pre-pare chemically stable thin films that could be widely used inoptoelectronic device fabrication such as solar cell light emit-ting diode and photodiode Various deposition techniquessuch as chemical vapor deposition vacuum depositionsolution growth and sputtering have been widely reportedfor thin film preparation Limitations such as high costand stringent growth process conditions (eg temperaturepressure environment and time) attributed to most of thesetechniques have negative impacts on the desired filmrsquos proper-ties Spray pyrolysis is essentially thermally stimulated reac-tion between clusters of ions or atoms of different chemicalspecies In spray technique a solution containing soluble saltsof the constituent atoms of the desired compound is sprayedon a substrate maintained at elevated temperatures Spraypyrolysis is a useful alternative to the traditional methods forobtaining zinc lead sulphide ternary compound thin films

Hindawi Publishing CorporationJournal of MaterialsVolume 2015 Article ID 215210 8 pageshttpdxdoiorg1011552015215210

2 Journal of Materials

Table 1 Summary of Zn119909Pb1ndash119909S deposition precursor

Sample Precursors (concentration volume)ZPS1 Zn(CH

3COO)

22H2O (01M 0mL) + Pb(CH

3COO)

2sdot3 H2O (01M 10mL) + CS(NH

2)2(01M 20mL)

ZPS2 Zn(CH3COO)

22H2O (01M 02mL) + Pb(CH

3COO)


2)2(01M 20mL)

ZPS3 Zn(CH3COO)

22H2O (01M 04mL) + Pb(CH

3COO)


2)2(01M 20mL)

ZPS4 Zn(CH3COO)

22H2O (01M 06mL) + Pb(CH

3COO)


2)2(01M 20mL)

ZPS5 Zn(CH3COO)

22H2O (01M 08mL) + Pb(CH

3COO)


2)2(01M 20mL)

ZPS6 Zn(CH3COO)

22H2O (01M 10mL) + Pb(CH

3COO)


2)2(01M 20mL)

It has several advantages over other deposition processeswhich include scalability of the process cost effectivenessallowance of intentional doping and low ormoderate growthtemperatures (100ndash400∘C) These unique properties createdifferent possibilities such as use of variety of substrateseasy control of thickness variation of film composition andpossibility of multilayer growth [11 12]

In this study we present results on zinc lead sulphide(Zn119909Pb1minus119909

S) thin films deposited on soda lime glass substrateusing chemical spray pyrolysis Rutherford backscatteringspectroscopy (RBS) was essentially used to study thicknessprofile and stoichiometric compositions of the films EDXwas used as complementary technique for identification offilms constituents Surface microstructure and crystal ori-entation were examined by scanning electron microscopy(SEM) and X-ray diffractometer (XRD)

2 Materials and Methods

21 Film Deposition Procedure Soda lime glass substrateswere cleaned by washing with detergent and rinsed with dis-tilled water before ultrasonic cleaning in acetone methanoland isopropyl alcohol (IPA) bath each for 20minutes respec-tivelyThe substrates were dried and kept in the vacuum ovenin order to minimize extraneous contamination The precur-sors for the Zn

119909Pb1minus119909

S thin films were obtained by preparingequal molar concentration of commercially available leadacetate zinc acetate and thiourea in varying proportionsdepending on the expected concentration of each cation inthe thin filmsThemixing ratio of the precursors correspond-ing to each sample designation (ZPS1ndashZPS6) is summarizedin Table 1 The freshly prepared solutions were stirred thor-oughly for several minutes before stepwise spraying ontopreheated clean substratesmaintained at (250 plusmn 5)∘C SuitableZn119909Pb1minus119909

S thin films were obtained by maintaining depo-sition parameters such as substrate temperature carrier gasflow rate and pressure that were at (250 plusmn 5)∘C (3ndash35) dm3min and 23 bar respectively The chemical reaction mecha-nism of Zn

119909Pb1minus119909

S thin film is as shown below in

Pb1minus119909(CH3COO)

2sdot 3H2O + Zn

119909(CH3COO)

2

sdot 2H2O +NH

2CSNH

2

997888rarr Zn119909Pb1minus119909

S + 2NH4+ 6CO

2+ 3CH

4+ 2H2

+H2O

(1)

22 Characterization Techniques Ion beam analysis (IBA) offilms was carried out at the Centre for Energy Research andDevelopment (CERD) Obafemi Awolowo University Ile-IfeNigeriaThe facility has a general purpose end station for par-ticle induced X-ray emission (PIXE) Rutherford backscat-tering spectrometry (RBS) elastic recoil detection analysis(ERDA) and particle induced gamma-ray emission (PIGE)Film composition thickness and depth profile were con-currently obtained by a 22MeV helium particle SIMNRAfitting code was used to carry out the spectra analyses of theRBS spectra Scanning electron microscope (Carl Zeiss MA-10 SEM) with attached EDX facility was used to investigatesurface morphology of the films Structural studies were car-ried out using GBC EMMA X-ray diffractometer with CuK120572radiation (120582 = 15418 A)

3 Results and Discussions

31 RBS Analyses The elemental composition stoichiome-try and thickness of the deposited Zn

119909Pb1minus119909

S thin films weredetermined using RBS techniqueThe SIMNRA Simplex codewas used to fit the simulation over experimental data and giveinformation regarding the stoichiometry and areal concen-tration Previous study [13] has shown that composition ofcompound semiconductors has a strong influence on theirpropertiesTherefore exact control of composition and accu-rate analysis of elements of these thin films are prerequisite forpreparing high quality and chemically stable thin films Boththe heavy elements (Pb Zn) and the relatively light element(S) were detected concurrently via the backscattering processThe spectra of simulated one-layer structure of Zn

119909Pb1minus119909

Sfilms with varying concentration of Zn are presented inFigures 1(a)ndash1(f) From distinct nature of the peaks shownin the spectra it can be inferred that the thin films are rel-atively uniform and adhere to the substrate well and withoutdiffusion between the layer of the films and the substrateThe results further suggested a thermal decomposition ofthe precursors to produce stable Zn-Pb-S compound withlittle or no trace of impurities such as carbon and hydrogenwhich were part of the constituents of the starting chemicalsPresence of such impurities affects film functionality In allthe spectra it is also observed that the peaks correspondingto each element are well separated This is due largely to thedifferences in the mass of the elements making up the targetnuclei namely zinc lead and sulphur Peak correspondingto Pb is more enhanced than that of S despite comparable

Journal of Materials 3

BIIRBSKASCSimulatedO Na

AlSiS K

CaFePb

S

Pb

ZPS1

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

Cou

nts

440400360320280240200160120

8040

0

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

(a)

Zn

ZPS2

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

Cou

nts

440400360320280240200160120

8040

0

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

S

Pb

SimulatedO Na

AlSiS K

CaFe

PbZn

BIIIRBSASC

(b)

ZnS

Pb

ZPS3

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

Cou

nts

440400360320280240200160120

8040

0

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

SimulatedO Na

AlSiS K

CaFe

PbZn

BIVRBSKASC

(c)

AIIRBSKASC

Cou

nts

280240200160120

8040

0

Pb

ZnS

ZPS4

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

SimulatedO Na

AlSiS K

CaFe

PbZn

(d)

Pb

ZnS

ZPS5

Cou

nts

280240200160120

8040

0

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

AIIRBSKASCSimulatedO Na

AlSiS K

CaFe

PbZn

(e)

AIIIRBSASC

Cou

nts

200180160140120100

80604020

0

Pb

ZnS

ZPS6

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

SimulatedO Na

AlSiS K

CaFe

PbZn

(f)

Figure 1 RBS spectra of deposited thin films of Zn119909Pb1minus119909

S for (a) ZPS1 (b) 119909 = ZPS2 (c) 119909 = ZPS3 (d) 119909 = ZPS4 (e) 119909 = ZPS5 and (f)119909 = ZPS6


Table 2 Elemental compositions and thickness profiles of Zn119909Pb1ndash119909S thin films

Sample code Compositions () RBS thickness (1015 atomscm) Linear thickness (nm)Zn Pb S

ZPS1 mdash 4058 5942 155220 81ZPS2 165 4737 5098 156147 82ZPS3 315 4583 5102 156121 82ZPS4 484 4457 5059 156318 82ZPS5 745 4230 5025 157452 82ZPS6 884 4082 5034 172465 90

concentrations during preparation This can be attributed todistinctive interaction of the projectile ion (4He+) with Pbnuclei which is much heavier than sulphur in the targetthereby yielding improved backscattering signal Composi-tional results of the Zn

119909Pb1minus119909

S films from the RBS experi-ment are presented in Table 2 Notable changes are observedin the concentration of elemental composition of the filmsThis is as a result of incremental variation of number of Znions with respect to volume of the zinc acetate in the precur-sor solution It therefore implies that using spraying pyrolysisit is convenient to build into the precursor the desired con-centration of dopants in thin films Expectedly as the concen-tration of zinc acetate was increased in the solution the con-centration of zinc ions increased reaching 884 per mL inthe 30mL precursor Film thickness was obtained in RBS unit(atomscm2) as shown in Table 2 In order to obtain it inSI unit areal density unit was approximated into the lengthunit using (2) [14] Since the densities of the deposited filmsare not known directly and may differ from that of bulk Zn-PbS therefore Zn due to its relatively low concentrations inthe films could as well be taken as a dopant element Basedon the foregoing a density similar to stoichiometric PbS(760 gcm3) was assumed and a factor of 0523 was obtainedfor the conversion of the atoms area density (1015 atoms cmminus2)into nanometer The corresponding length unit values aregiven in Table 2

Thickness = atoms per unit areaatoms per unit volume

(2)

In order to complement the composition results obtainedfrom backscattering experiments full scale EDX scan wasdone at beam kinetic energy of 20 keV Analysis was carriedout using INCA Point ID software for quant optimizationSince the facility is not exclusive in quantitative study itcould only be used for identification of elementsHence threesamples were selected to understand composition of all thedeposited films Spectrum shown in Figure 2(a) representingsamples ZPS2ndashZPS6 confirmed the presence of lead zincand sulphur while Figure 2(b) confirmed lead and sulphurfor sample ZPS1 with no contamination detected Figure 2(c)showed the elemental characteristics of the soda lime glassslide used as the substrate These results further justify thecomposition results obtained from the RBS analysis

32 Morphological Analysis Surface uniformity particledistribution and porosity (microstructural properties) of

the deposited Zn119909Pb1minus119909

S thin filmswere appraised fromSEMmicrographs The images shown in Figures 3(a)ndash3(f) corre-spond to each of the samples ZPS1 to ZPS6 respectively Fromthemicrographs it can be seen that all the films are composedof distinct crystallites that are well distributed across thesubstrate Considering image in Figure 3(a) (sample withoutzinc) it can be seen that the film is well crystalline and itsparticles are closely packed There is no observable crackor pinhole Images of other samples (see Figures 3(b)ndash3(f))possess similar features with a number of observations (i)particle size appears smaller than in Figure 3(a) and (ii) par-ticles are coalesced and formation of polycrystal is enhancedas percentage contribution of Zn increases Thus it can besuggested that introduction of zinc can cause slight reductionin the particle size Increasing the Zn2+ in the Zn

119909Pb1minus119909

Sfilms caused an increase in surface diffusion

33 Structural and Crystallographic Analysis The XRD spec-tra were used to determine the structure and crystallographicorientation of the samples The diffraction patterns of theZn119909Pb1minus119909

S thin film prepared by CSP are shown in Figure 4The diffraction patterns indicate that the prepared Zn

119909Pb1minus119909

Sthin films are polycrystalline in nature with the existence ofsharp and well defined peaks

As shown in Figure 4 all the prominent peaks of eachspectrum are indexed to the rock salt (NaCl) structure ofPbS according to the value of the reference standard JCPDS(card number 5-592) [15 16] The prominent peaks indicatethat the crystals have preferred orientations at the planesobserved at (111) (200) (220) (311) and (222) The relativediffraction peaks intensities of the most three prominentpeaks (119868

111119868200

) and (119868220119868200

) of the prepared Zn119909Pb1minus119909

Sthin films are shown in Table 3 Both the intensity ratios(119868111119868200

) and (119868220119868200

) for thin films grown are within therange (014ndash024) and (012ndash020) these values are lower thanthe JCPDS standard of 084 and 057 respectively showingthat the samples prepared have (200) preferred orientationwith strong intensity

In addition the diffraction angle of the peaks shiftsslightly with the addition of Zn2+ Also as the concentrationof Zn2+ increases the intensity of diffraction peaks deceasesThe slight shifts in the diffraction peaks and decease in peakintensity with increase of Zn2+ in the Zn

119909Pb1minus119909

S thin filmscan be attributed to induced structural disorder in the films[17]The slight shift of the diffraction peak angle could also beas a result of the increase in heterogeneity of the films due to


Spectrum 1

0 1 2 3 4 5 6 7

(keV)Full scale 62559 cts cursor 4731 (219 cts)

OO

K

KKCa

CaCa

CaZn

ZnMg

Na

Al

S

S

Pb

Pb

Si

(a)

Spectrum 1

O

ONa

KKCa

CaCaCa MgAl S S

Pb

PbSi

0 1 2 3 4 5 6 7


(b)

Spectrum 1

O

O

K K

KCa

CaCaCa Mg

Al

Si

Na

0 1 2 3 4 5 6 7


(c)

Figure 2 EDX spectrum of deposited thin films on soda lime glass substrate (a) ZPS2 (b) ZPS1 and (c) soda lime glass

Table 3 119868119868119900ratio of prominent peaks of the prepared films and that

of the JCPDS standard

Relativeintensityratio

JCPDSstandard ZPS1 ZPS2 ZPS3 ZPS4 ZPS5 ZPS6

119868111119868200

084 014 015 022 024 024 024119868220119868200

057 012 014 017 021 022 022

the occupation of Zn2+ into the host lattice Crystal size of thesamples was estimated using Debye Schererrsquos formula [18]given by

119863 =

119870120582

120573 cos 120579 (3)

where 119863 is the grain size 120582 is the wavelength (15406 Afor CuK120572 radiation) 120573 is the full width at half maximum(FWHM) and 119870 = 094 is the shape factor approximatelyequal to unity

The lattice parameters were estimated using the combina-tion of Braggrsquos law and plane spacing equation for the rock salt(NaCl) structure given by (4) [19 20] The computed crystalssize and the lattice constants (119886) are presented in Table 3

sin2120579 = 1205822

1198862(ℎ2

+ 1198962

+ 1198972

) (4)

Table 4 Computed crystals size and the lattice constants for thinfilm samples

SampleLatticeconstant

(A)

Crystal sizeusing

Schererrsquosformula (nm)

Crystal sizeusing

modifiedSchererrsquos

formula (nm)

Residualstrain

ZPS1 5942 14 15 3125 times 10minus3

ZPS2 5952 13 13 322 times 10minus3

ZPS3 5961 12 13 385 times 10minus3

ZPS4 5973 12 12 575 times 10minus3

ZPS5 5989 11 11 670 times 10minus3

ZPS6 5995 10 10 700 times 10minus3

The crystal size decreases from 1428 to 98 nm as theconcentration of Zn increases in the Zn

119909Pb1minus119909

S thin filmpreparedThe lattice constant increased from 5942 to 5995 Aas the Zn2+ in Zn

119909Pb1minus119909

S increases from ZPS1 to ZPS6(Table 4)

However during thin film deposition lattice mismatchbetween the film and the substrate with the influence of thedeposition conditions such as the temperature compositionand deposition rate can also create strain [21] Therefore the


(a) (b)

(c) (d)

(e) (f)

Figure 3 SEM micrographs of deposited thin film of Zn119909Pb1minus119909

S for (a) ZPS1 (b) ZPS2 (c) ZPS3 (d) ZPS4 (e) ZPS5 and (f) ZPS6

residual strain on the deposited filmswas calculated using themodified Schererrsquos equation [22] expressed in

120573 =

119870120582

119863 cos 120579+ 4120576 tan 120579 (5)

where 120576 is the residual strain and119863 is the grain size From thedata obtained from the diffraction patterns of the preparedZn119909Pb1minus119909

S thin film shown in Figure 4 the grain size 119863 andresidual strain (120576) are deduced from the intercept and slopeof the plot of 120573 cos 120579 versus sin 120579 Hence the increase of Zn in


ZPS1

ZPS2

ZPS3

ZPS4

ZPS5ZPS6

Cou

nts

2120579 (deg)

55000

44000

33000

22000

11000

0

20 30 40 50 60 70

(200)

(111) (220) (311) (222)

Figure 4 XRD pattern of deposited thin film of Zn119909Pb1minus119909

S

the Zn119909Pb1minus119909

S causes slight increase in residual strain in thefilm from 3125 times 10minus3 to 70 times 10minus3 This may be due to thereplacement of some larger lead ions (121 A) by smaller zincions (074 A) Similar results were reported for Mn-dopedCdS films [23]

4 Conclusion

Zinc lead sulphide thin films have been synthesized success-fully by chemical spray pyrolysis without any complexingagent otherwise using common chemical reagents Thedesired composition was built into the precursors prior todeposition Rutherford backscattering experiment revealedchanges in the thickness with stoichiometry Direct observa-tion from themicrographs showed that the films arewell crys-talline with closely packed particles Film diffraction analysisindicated direct relationship between lattice constant resid-ual stress and Zn compositionsThus by suitably controllingthe Zn composition in the layers the Zn

119909Pb1minus119909

S films mayhave minimum lattice mismatch compared to that of purePbS in forming heterojunction device

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors acknowledge the immense contribution of Pro-fessorAM Salauwho passed away recently (may his soul restin peace (amen))The authors thank staff of Nuclear Acceler-ator Laboratory at Centre for Energy Research and Develop-ment Obafemi Awolowo University Ile-Ife Nigeria for RBSmeasurements and analyses Efforts of colleagues at Depart-ment of Physics of Obafemi Awolowo University Ile-Ife areappreciated Special appreciation goes to the management ofEngineering Materials Development Institute Akure Nige-ria for making some of their laboratory facilities availableduring this study

References

[1] R Chandramohan T Mahalingam J P Chu and P J Sebas-tian ldquoPreparation and characterization of semiconductingZn1minusxCdxSe thin filmsrdquo Solar Energy Materials and Solar Cellsvol 81 no 3 pp 371ndash378 2004

[2] S K Deshmukh A V Kokate and D J Sathe ldquoStudies on elec-trodeposited Cd

1minus119909Fe119909S thin filmsrdquoMaterials Science and Engi-

neering B vol 122 no 3 pp 206ndash210 2005[3] H Moon A Kathalingam T Mahalingam J P Chu and Y

D Kim ldquoStudies on electro-synthesized zinc mercury selenidealloysrdquo Journal ofMaterials Science Materials in Electronics vol18 no 10 pp 1013ndash1019 2007

[4] P K Nair M T S Nair A Fernandes and M OcampoldquoProspects of chemically deposited metal chalcogenide thinfilms for solar control applicationsrdquo Journal of Physics D AppliedPhysics vol 22 no 6 pp 829ndash836 1989

[5] A Pascual P Diaz-Chao I J Ferrer C Sanchez and J R AresldquoOn the growth and doping of FeTi chalcogenide thin filmsrdquoSolar Energy Materials and Solar Cells vol 87 no 1ndash4 pp 575ndash582 2005

[6] A B Kashyout A S Arico G Monforte F Crea V Antonucciand N Giordano ldquoElectrochemical deposition of ZnFeS thinfilm semiconductors on tin oxide substratesrdquo Solar EnergyMaterials and Solar Cells vol 37 no 1 pp 43ndash53 1995

[7] X J Wu D Z Shen Z Z Zhang et al ldquop-type conductivityand donor-acceptor pair emission inCd

1minus119909Fe119909S dilutemagnetic

semiconductorsrdquo Applied Physics Letters vol 89 Article ID262118 2006

[8] SThanikaikarasan T Mahalingam K Sundaram T Kim Y DKim and S Velumani ldquoElectrochemical deposition and charac-terization of Cd-Fe-Se thin filmsrdquoAdvancedMaterials Researchvol 68 pp 69ndash76 2009

[9] JH LeeWC Song J S Yi K J YangWDHan and JHwangldquoGrowth and properties of the Cd

1minus119909Zn119909S thin films for solar

cell applicationsrdquo Thin Solid Films vol 431-432 pp 349ndash3532003

[10] Y Y Xi T L Y Cheung and D H L Ng ldquoSynthesis of ternaryZnxCd1minusxS nanowires by thermal evaporation and the study oftheir photoluminescencerdquo Materials Letters vol 62 no 1 pp128ndash132 2008

[11] D S Albin and S H Rishbud ldquoSpray pyrolysis processing ofoptoelectronic materialsrdquo Advanced Ceramic Materials vol 2no 3 p 243 1987

[12] T T John C S Kartha K P Vijayakumar T Abe and YKashiwaba ldquoPreparation of indium sulfide thin films by spraypyrolysis using a new precursor indiumnitraterdquoApplied SurfaceScience vol 252 no 5 pp 1360ndash1367 2005

[13] R K Joshi and H K Sehgal ldquoStructure conductivity and HallEffect study of solution grown Pb

1minus119909Fe119909S nanoparticle filmsrdquo

Nanotechnology vol 14 no 6 pp 592ndash596 2003[14] W K Chu J W Mayer and M A Nicolet Backscattering

Spectroscopy Academic Press London UK 1978[15] K S Deane and J Ron Powder Diffraction File International

Centre for Diffraction Data Newtown Square Pa USA 2001[16] S Kumar T P Sharma M Zulfequar and M Husain ldquoCharac-

terization of vacuum evaporated PbS thin filmsrdquo Physica B vol325 pp 8ndash16 2003

[17] H K Yadav K Sreenivas R S Katiyar and V Gupta ldquoDefectinduced activation of Raman silentmodes in rf co-sputteredMndopedZnO thin filmsrdquo Journal of Physics D Applied Physics vol40 no 19 pp 6005ndash6009 2007


[18] S J Castillo AMendoza-Galvan R Ramırez-Bon et al ldquoStruc-tural optical and electrical characterization of InCdSglassthermally annealed systemrdquo Thin Solid Films vol 373 no 1-2pp 10ndash14 2000

[19] BD CullityElement of X-RayDiffraction Addison-Wesley 2ndedition 1977

[20] B A Taleatu and A Y Fasasi ldquoStructural characterisation ofchemical bath deposited ZnO and Ni-doped ZnO thin filmsrdquoNigerian Journal of Material Science and Engineering vol 1 pp1ndash8 2009

[21] M N Kamalasanan N D Kumar and S Chandra ldquoStructuraland microstructural evolution of barium titanate thin filmsdeposited by the sol-gel processrdquo Journal of Applied Physics vol76 no 8 pp 4603ndash4609 1994

[22] N Choudhury and B K Sarma ldquoStructural characterization oflead sulfide thin films by means of X-ray line profile analysisrdquoBulletin of Materials Science vol 32 no 1 pp 43ndash47 2009

[23] C T Tsai S H Chen D S Chuu and W C Chou ldquoFab-rication and physical properties of radio frequency sputteredCd1minus119909

Mn119909S thin filmsrdquo Physical Review B vol 54 no 16 pp

11555ndash11560 1996

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Table 1 Summary of Zn119909Pb1ndash119909S deposition precursor

Sample Precursors (concentration volume)ZPS1 Zn(CH

3COO)

22H2O (01M 0mL) + Pb(CH

3COO)


2)2(01M 20mL)

ZPS2 Zn(CH3COO)

22H2O (01M 02mL) + Pb(CH

3COO)


2)2(01M 20mL)

ZPS3 Zn(CH3COO)

22H2O (01M 04mL) + Pb(CH

3COO)


2)2(01M 20mL)

ZPS4 Zn(CH3COO)

22H2O (01M 06mL) + Pb(CH

3COO)


2)2(01M 20mL)

ZPS5 Zn(CH3COO)

22H2O (01M 08mL) + Pb(CH

3COO)


2)2(01M 20mL)

ZPS6 Zn(CH3COO)

22H2O (01M 10mL) + Pb(CH

3COO)


2)2(01M 20mL)

It has several advantages over other deposition processeswhich include scalability of the process cost effectivenessallowance of intentional doping and low ormoderate growthtemperatures (100ndash400∘C) These unique properties createdifferent possibilities such as use of variety of substrateseasy control of thickness variation of film composition andpossibility of multilayer growth [11 12]

In this study we present results on zinc lead sulphide(Zn119909Pb1minus119909

S) thin films deposited on soda lime glass substrateusing chemical spray pyrolysis Rutherford backscatteringspectroscopy (RBS) was essentially used to study thicknessprofile and stoichiometric compositions of the films EDXwas used as complementary technique for identification offilms constituents Surface microstructure and crystal ori-entation were examined by scanning electron microscopy(SEM) and X-ray diffractometer (XRD)

2 Materials and Methods

21 Film Deposition Procedure Soda lime glass substrateswere cleaned by washing with detergent and rinsed with dis-tilled water before ultrasonic cleaning in acetone methanoland isopropyl alcohol (IPA) bath each for 20minutes respec-tivelyThe substrates were dried and kept in the vacuum ovenin order to minimize extraneous contamination The precur-sors for the Zn

119909Pb1minus119909

S thin films were obtained by preparingequal molar concentration of commercially available leadacetate zinc acetate and thiourea in varying proportionsdepending on the expected concentration of each cation inthe thin filmsThemixing ratio of the precursors correspond-ing to each sample designation (ZPS1ndashZPS6) is summarizedin Table 1 The freshly prepared solutions were stirred thor-oughly for several minutes before stepwise spraying ontopreheated clean substratesmaintained at (250 plusmn 5)∘C SuitableZn119909Pb1minus119909

S thin films were obtained by maintaining depo-sition parameters such as substrate temperature carrier gasflow rate and pressure that were at (250 plusmn 5)∘C (3ndash35) dm3min and 23 bar respectively The chemical reaction mecha-nism of Zn

119909Pb1minus119909

S thin film is as shown below in

Pb1minus119909(CH3COO)

2sdot 3H2O + Zn

119909(CH3COO)

2

sdot 2H2O +NH

2CSNH

2

997888rarr Zn119909Pb1minus119909

S + 2NH4+ 6CO

2+ 3CH

4+ 2H2

+H2O

(1)

22 Characterization Techniques Ion beam analysis (IBA) offilms was carried out at the Centre for Energy Research andDevelopment (CERD) Obafemi Awolowo University Ile-IfeNigeriaThe facility has a general purpose end station for par-ticle induced X-ray emission (PIXE) Rutherford backscat-tering spectrometry (RBS) elastic recoil detection analysis(ERDA) and particle induced gamma-ray emission (PIGE)Film composition thickness and depth profile were con-currently obtained by a 22MeV helium particle SIMNRAfitting code was used to carry out the spectra analyses of theRBS spectra Scanning electron microscope (Carl Zeiss MA-10 SEM) with attached EDX facility was used to investigatesurface morphology of the films Structural studies were car-ried out using GBC EMMA X-ray diffractometer with CuK120572radiation (120582 = 15418 A)

3 Results and Discussions

31 RBS Analyses The elemental composition stoichiome-try and thickness of the deposited Zn

119909Pb1minus119909

S thin films weredetermined using RBS techniqueThe SIMNRA Simplex codewas used to fit the simulation over experimental data and giveinformation regarding the stoichiometry and areal concen-tration Previous study [13] has shown that composition ofcompound semiconductors has a strong influence on theirpropertiesTherefore exact control of composition and accu-rate analysis of elements of these thin films are prerequisite forpreparing high quality and chemically stable thin films Boththe heavy elements (Pb Zn) and the relatively light element(S) were detected concurrently via the backscattering processThe spectra of simulated one-layer structure of Zn

119909Pb1minus119909

Sfilms with varying concentration of Zn are presented inFigures 1(a)ndash1(f) From distinct nature of the peaks shownin the spectra it can be inferred that the thin films are rel-atively uniform and adhere to the substrate well and withoutdiffusion between the layer of the films and the substrateThe results further suggested a thermal decomposition ofthe precursors to produce stable Zn-Pb-S compound withlittle or no trace of impurities such as carbon and hydrogenwhich were part of the constituents of the starting chemicalsPresence of such impurities affects film functionality In allthe spectra it is also observed that the peaks correspondingto each element are well separated This is due largely to thedifferences in the mass of the elements making up the targetnuclei namely zinc lead and sulphur Peak correspondingto Pb is more enhanced than that of S despite comparable



AlSiS K

CaFePb

S

Pb

ZPS1

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

Cou

nts

440400360320280240200160120

8040

0

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

(a)

Zn

ZPS2

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

Cou

nts

440400360320280240200160120

8040

0

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

S

Pb

SimulatedO Na

AlSiS K

CaFe

PbZn

BIIIRBSASC

(b)

ZnS

Pb

ZPS3

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

Cou

nts

440400360320280240200160120

8040

0

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

SimulatedO Na

AlSiS K

CaFe

PbZn

BIVRBSKASC

(c)

AIIRBSKASC

Cou

nts

280240200160120

8040

0

Pb

ZnS

ZPS4

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

SimulatedO Na

AlSiS K

CaFe

PbZn

(d)

Pb

ZnS

ZPS5

Cou

nts

280240200160120

8040

0

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)


AlSiS K

CaFe

PbZn

(e)

AIIIRBSASC

Cou

nts

200180160140120100

80604020

0

Pb

ZnS

ZPS6

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

SimulatedO Na

AlSiS K

CaFe

PbZn

(f)








119909Pb1minus119909



(2)





119909Pb1minus119909




119909Pb1minus119909



111119868200

) and (119868220119868200



) and (119868220119868200



119909Pb1minus119909



Spectrum 1

0 1 2 3 4 5 6 7


OO

K

KKCa

CaCa

CaZn

ZnMg

Na

Al

S

S

Pb

Pb

Si

(a)

Spectrum 1

O

ONa

KKCa

CaCaCa MgAl S S

Pb

PbSi

0 1 2 3 4 5 6 7


(b)

Spectrum 1

O

O

K K

KCa

CaCaCa Mg

Al

Si

Na

0 1 2 3 4 5 6 7


(c)






119868111119868200

084 014 015 022 024 024 024119868220119868200

057 012 014 017 021 022 022


119863 =

119870120582

120573 cos 120579 (3)



sin2120579 = 1205822

1198862(ℎ2

+ 1198962

+ 1198972

) (4)



(A)

Crystal sizeusing


Crystal sizeusing


formula (nm)

Residualstrain

ZPS1 5942 14 15 3125 times 10minus3

ZPS2 5952 13 13 322 times 10minus3

ZPS3 5961 12 13 385 times 10minus3

ZPS4 5973 12 12 575 times 10minus3

ZPS5 5989 11 11 670 times 10minus3

ZPS6 5995 10 10 700 times 10minus3


119909Pb1minus119909


119909Pb1minus119909




(a) (b)

(c) (d)

(e) (f)




120573 =

119870120582

119863 cos 120579+ 4120576 tan 120579 (5)




ZPS1

ZPS2

ZPS3

ZPS4

ZPS5ZPS6

Cou

nts

2120579 (deg)

55000

44000

33000

22000

11000

0

20 30 40 50 60 70

(200)

(111) (220) (311) (222)


S



4 Conclusion


119909Pb1minus119909




Acknowledgments


References


































11555ndash11560 1996








CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





AlSiS K

CaFePb

S

Pb

ZPS1

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

Cou

nts

440400360320280240200160120

8040

0

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

(a)

Zn

ZPS2

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

Cou

nts

440400360320280240200160120

8040

0

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

S

Pb

SimulatedO Na

AlSiS K

CaFe

PbZn

BIIIRBSASC

(b)

ZnS

Pb

ZPS3

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

Cou

nts

440400360320280240200160120

8040

0

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

SimulatedO Na

AlSiS K

CaFe

PbZn

BIVRBSKASC

(c)

AIIRBSKASC

Cou

nts

280240200160120

8040

0

Pb

ZnS

ZPS4

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

SimulatedO Na

AlSiS K

CaFe

PbZn

(d)

Pb

ZnS

ZPS5

Cou

nts

280240200160120

8040

0

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)


AlSiS K

CaFe

PbZn

(e)

AIIIRBSASC

Cou

nts

200180160140120100

80604020

0

Pb

ZnS

ZPS6

Channel

600

560

520

480

440

400

360

320

280

240

200

160

12080400

0 200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

Energy (keV)

SimulatedO Na

AlSiS K

CaFe

PbZn

(f)








119909Pb1minus119909



(2)





119909Pb1minus119909




119909Pb1minus119909



111119868200

) and (119868220119868200



) and (119868220119868200



119909Pb1minus119909



Spectrum 1

0 1 2 3 4 5 6 7


OO

K

KKCa

CaCa

CaZn

ZnMg

Na

Al

S

S

Pb

Pb

Si

(a)

Spectrum 1

O

ONa

KKCa

CaCaCa MgAl S S

Pb

PbSi

0 1 2 3 4 5 6 7


(b)

Spectrum 1

O

O

K K

KCa

CaCaCa Mg

Al

Si

Na

0 1 2 3 4 5 6 7


(c)






119868111119868200

084 014 015 022 024 024 024119868220119868200

057 012 014 017 021 022 022


119863 =

119870120582

120573 cos 120579 (3)



sin2120579 = 1205822

1198862(ℎ2

+ 1198962

+ 1198972

) (4)



(A)

Crystal sizeusing


Crystal sizeusing


formula (nm)

Residualstrain

ZPS1 5942 14 15 3125 times 10minus3

ZPS2 5952 13 13 322 times 10minus3

ZPS3 5961 12 13 385 times 10minus3

ZPS4 5973 12 12 575 times 10minus3

ZPS5 5989 11 11 670 times 10minus3

ZPS6 5995 10 10 700 times 10minus3


119909Pb1minus119909


119909Pb1minus119909




(a) (b)

(c) (d)

(e) (f)




120573 =

119870120582

119863 cos 120579+ 4120576 tan 120579 (5)




ZPS1

ZPS2

ZPS3

ZPS4

ZPS5ZPS6

Cou

nts

2120579 (deg)

55000

44000

33000

22000

11000

0

20 30 40 50 60 70

(200)

(111) (220) (311) (222)


S



4 Conclusion


119909Pb1minus119909




Acknowledgments


References


































11555ndash11560 1996








CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials








119909Pb1minus119909



(2)





119909Pb1minus119909




119909Pb1minus119909



111119868200

) and (119868220119868200



) and (119868220119868200



119909Pb1minus119909



Spectrum 1

0 1 2 3 4 5 6 7


OO

K

KKCa

CaCa

CaZn

ZnMg

Na

Al

S

S

Pb

Pb

Si

(a)

Spectrum 1

O

ONa

KKCa

CaCaCa MgAl S S

Pb

PbSi

0 1 2 3 4 5 6 7


(b)

Spectrum 1

O

O

K K

KCa

CaCaCa Mg

Al

Si

Na

0 1 2 3 4 5 6 7


(c)






119868111119868200

084 014 015 022 024 024 024119868220119868200

057 012 014 017 021 022 022


119863 =

119870120582

120573 cos 120579 (3)



sin2120579 = 1205822

1198862(ℎ2

+ 1198962

+ 1198972

) (4)



(A)

Crystal sizeusing


Crystal sizeusing


formula (nm)

Residualstrain

ZPS1 5942 14 15 3125 times 10minus3

ZPS2 5952 13 13 322 times 10minus3

ZPS3 5961 12 13 385 times 10minus3

ZPS4 5973 12 12 575 times 10minus3

ZPS5 5989 11 11 670 times 10minus3

ZPS6 5995 10 10 700 times 10minus3


119909Pb1minus119909


119909Pb1minus119909




(a) (b)

(c) (d)

(e) (f)




120573 =

119870120582

119863 cos 120579+ 4120576 tan 120579 (5)




ZPS1

ZPS2

ZPS3

ZPS4

ZPS5ZPS6

Cou

nts

2120579 (deg)

55000

44000

33000

22000

11000

0

20 30 40 50 60 70

(200)

(111) (220) (311) (222)


S



4 Conclusion


119909Pb1minus119909




Acknowledgments


References


































11555ndash11560 1996








CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Spectrum 1

0 1 2 3 4 5 6 7


OO

K

KKCa

CaCa

CaZn

ZnMg

Na

Al

S

S

Pb

Pb

Si

(a)

Spectrum 1

O

ONa

KKCa

CaCaCa MgAl S S

Pb

PbSi

0 1 2 3 4 5 6 7


(b)

Spectrum 1

O

O

K K

KCa

CaCaCa Mg

Al

Si

Na

0 1 2 3 4 5 6 7


(c)






119868111119868200

084 014 015 022 024 024 024119868220119868200

057 012 014 017 021 022 022


119863 =

119870120582

120573 cos 120579 (3)



sin2120579 = 1205822

1198862(ℎ2

+ 1198962

+ 1198972

) (4)



(A)

Crystal sizeusing


Crystal sizeusing


formula (nm)

Residualstrain

ZPS1 5942 14 15 3125 times 10minus3

ZPS2 5952 13 13 322 times 10minus3

ZPS3 5961 12 13 385 times 10minus3

ZPS4 5973 12 12 575 times 10minus3

ZPS5 5989 11 11 670 times 10minus3

ZPS6 5995 10 10 700 times 10minus3


119909Pb1minus119909


119909Pb1minus119909




(a) (b)

(c) (d)

(e) (f)




120573 =

119870120582

119863 cos 120579+ 4120576 tan 120579 (5)




ZPS1

ZPS2

ZPS3

ZPS4

ZPS5ZPS6

Cou

nts

2120579 (deg)

55000

44000

33000

22000

11000

0

20 30 40 50 60 70

(200)

(111) (220) (311) (222)


S



4 Conclusion


119909Pb1minus119909




Acknowledgments


References


































11555ndash11560 1996








CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a) (b)

(c) (d)

(e) (f)




120573 =

119870120582

119863 cos 120579+ 4120576 tan 120579 (5)




ZPS1

ZPS2

ZPS3

ZPS4

ZPS5ZPS6

Cou

nts

2120579 (deg)

55000

44000

33000

22000

11000

0

20 30 40 50 60 70

(200)

(111) (220) (311) (222)


S



4 Conclusion


119909Pb1minus119909




Acknowledgments


References


































11555ndash11560 1996








CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




ZPS1

ZPS2

ZPS3

ZPS4

ZPS5ZPS6

Cou

nts

2120579 (deg)

55000

44000

33000

22000

11000

0

20 30 40 50 60 70

(200)

(111) (220) (311) (222)


S



4 Conclusion


119909Pb1minus119909




Acknowledgments


References


































11555ndash11560 1996








CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials











11555ndash11560 1996








CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



research article rutherford backscattering spectrometry...

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