F R A U N H O F E R I N S T I T U T E F O R S O l A R E N E R g Y S Y S T E m S I S E

CRYSTALLINE SILICON THIN-FILM MATERIALS SERvICES

Fraunhofer ISE has been working on

crystalline silicon thin-film solar cells for

many years. Our speciality lies in silicon

and silicon-based deposition on a variety

of silicon and non-silicon substrates, the

recrystallization of silicon layers and in

adapting solar cell production processes.

We are experts in handling a wide range

of contamination levels, variable substrate

sizes and morphologies and temperatures

up to 1500 °C.

Besides R&D projects, we offer long-

standing expertise and state-of-the-art

technical equipment to companies and

research groups seeking support in the

fields of:

n layers and coatings

n solar cell processes

n high temperature processing

n characterization

layers and Coatings

Our laboratories can handle substrate sizes

from 20 x 20 mm2 to 156 x 500 mm2 with

thicknesses ranging from the micro to the

millimeter scale. We are used to work with

sample bowing, various surface morpho-

logies, highly porous substrates and high

contamination levels.

Our services:

n encapsulation and infiltration with

µc-Si / µc-SiC for hard coatings or

diffusion barriers

n high-quality silicon epitaxy

(n- or p-doped) for solar cell or

microelectronic applications

n porosification, reorganization, lift-off

and transfer of Si foils

n layer-stacks of amorphous SixC1-x for

application in passivation, optics and

encapsulation

1 REM image of crystalline silicon carbide

(SiC) encapsulation and infiltration of a

graphite based structure.

2 Fluorine based plasma texture on a

Si wafer.

3 Epitaxial lateral overgrowth (ELO) of

SiO2 layer on a Si wafer.

Fraunhofer Institute for

Solar Energy Systems

Heidenhofstrasse 2

79110 Freiburg

Germany

Phone +49 761 4588-0

Fax +49 761 4588-9000

www.ise.fraunhofer.de

Silicon Photovoltaics –

Crystalline Silicon Thin-Film

Solar Cells

Dr Stefan Janz

+49 761 4588-5261

stefan.janz@ise.fraunhofer.de

July 2014

1 2 3

Characterization

We provide structural and electro-optical

characterizations and related services for

thin-film and bulk material.

Our methods:

n SRP (Spreading Resistance Profiling)

n XRD (X-ray Diffraction, Grazing

Incidence (GI-XRD), rocking curve

analysis) and X-Ray Reflectometry (XRR)

n MWPCD (Microwave-Detected Photo

Conductance Decay) mapping

n conductivity measurements from

T = 70–500 K and under illumination

Our services:

n laser labeling of substrates

n laser cutting for any choice of shape

n cross-section preparation and surface

polishing

Solar Cell Processing

We offer services along the entire value

chain of solar cell processing. Our focus

is on reliability and small batch sizes. Our

expertise includes processes for defect-rich,

contaminated or very thin silicon absorber

layers.

Our services:

n wet-chemical cleaning and etching

n dopant in-diffusion and oxidation

n photolithography

n metal contact formation by sputtering,

evaporation and electroplating

n plasma texture (black silicon)

n Remote Plasma Hydrogen Passivation

(RPHP)

n surface passivation with SiO2, AlOx, SiNx

n epitaxial emitters with custom-designed

dopant profile and thickness

High-Temperature Processing

To improve the structure and electrical qua-

lity of the silicon material, high temperature

treatments in diverse atmospheres are

available for various contamination levels.

Our services:

n annealing at temperatures up to 1350°C

(H2, Ar, N2 or O2 atmosphere)

n gettering of metal impurities with

phosphorus or HCl gas

n solid phase crystallisation (SPC)

and liquid phase zone-melting

recrystallization

1 ProConCVD equipment for high-throughput

Si and SiC deposition at atmospheric pressure.

1

4 Bifacial confocal white light microscopy map-

ping the thickness of a mesa etched solar cell.

3 Spreading Resistance Profiling (SRP) of a

dopant (epitaxial Si layer).

0.4 µs 3.0 µs

depth (µm)

0 10 20 30 40 50

dopa

nt c

once

ntra

tion

(cm

-3)

1E16

1E17

1E18

1E19

1,1E17

1,4E18

3,9E17

7,9E18

width (µm)

dept

h (µ

m)

thickness (µm)

255

257

259

261

263

265200

400

600

800

1000

200 400 600 800 1000

2 Microwave-Detected Photoconductance

Decay (MWPCD) mapping of 10 µm thin Si foil.