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Download fileHigh rate deposition of thin film CdTe solar cells by pulsed dc magnetron sputtering
conference contribution
posted on 2016-01-20, 14:15 authored by Piotr Kaminski, Ali AbbasAli Abbas, Sibel Yilmaz, Jake BowersJake Bowers, Michael WallsMichael WallsA new high rate deposition method has been used to fabricate thin film CdTe photovoltaic
devices using pulsed dc magnetron sputtering. The devices have been deposited in superstrate
configuration on to a commercial fluorine doped tin oxide transparent conductor on soda lime
glass. The cadmium sulphide and cadmium telluride thin films were deposited from compound
targets. The magnetrons were mounted vertically around a cylindrical chamber and the substrate
carrier rotates so that the layers can be deposited sequentially. The substrates were held at 200ºC
during deposition, a process condition previously found to minimize the stress in the coatings.
Optimization of the process involved a number of parameters including control of pulse
frequency, power and working gas pressure. The devices deposited using the process are
exceptionally uniform enabling the CdTe absorber thickness to be reduced to ~1um. The asdeposited
material is dense and columnar. The cadmium chloride treatment increases the grain
size and removes planar defects. The microstructure of the films before and after activation has
been characterized using a number of techniques including transmission electron microscopy,
Energy Dispersive mapping and these measurements have been correlated to device
performance. The deposition rate is much higher than can be obtained with radio-frequency
sputtering and is comparable with methods currently used in thin film CdTe module
manufacturing such as Vapour Transport Deposition and Close Space Sublimation.
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