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Posted: December 18, 2008
Thickness Monitoring of Thin-Film Solar Cell Processes
(Nanowerk News) LayTec is currently developing the product for in-line monitoring
of thin-film solar cell production processes. The upcoming
sensor systems will measure the thickness of all
functional layers and provide information on optical properties
of the layer materials as well as surface roughness and
formation of interdiffusion regions between layers.
LayTec have already approved their methods in CdTe and CIGS
based processes, both for photovoltaic cells on glass and
metallized polymer foils.
The future of chalcopyrite and II-VI thin-film solar cell production
heavily depends on reliable in-line thickness monitoring
methods. The current methods are insufficient for two
reasons: 1) accurate film thickness measurements by specular
reflectance are hindered by diffuse scattering on rough
textured CIGS or CdTe absorbers; 2) in high temperature processes,
inter-diffusion of adjacent layers takes place.
For accurate measurements of rough materials LayTec are developing
a new optical head with highly sensitive detectors
which suppresses the upper listed artefacts. For the precise
analysis of the spectra, LayTec have successfully extended the
conventional thin-film optical equation by correcting terms
for texture, light scattering and inter-diffusion effects.
LayTec has conducted numerous tests for CdTe and CIGS
absorbers, CdS buffers on absorber layers and various TCOs,
both on substrates and on top of multi-layer stacks.
The new product is designed to be integrated into virtually any
deposition processes ranging from in-line processes on glass to
roll-to-roll processes on polymer or metal foil.
Dr. Steffen Uredat of LayTec will present first results at the
18th International Photovoltaic Science and Engineering Conference
(PVSEC 18) in Kolkata, India on 19-23 January 2009.
The product release is planned for the 3rd quarter of 2009.