Growth and characterization of large area Cu(In,Ga)Se-2 films

Large area thin films of Cu(In,Ga)Se, (CIGS) were grown by sequential sputt ering. Photovoltaic cells have been fabricated using these films and the pe rformance has been characterized. The effect of annealing conditions (tempe rature and duration) of the CIGS film on the device performance has been in vestigated. SEM studies of the films correlate the microstructure of the CI GS films with the solar cell efficiency. Cell efficiencies in excess of 10% have been achieved by using optimized annealing conditions. The optical pr operties of the CIGS films were characterized using Variable Angle Spectros copic Ellipsometry (VASE). The Gaussian broadened polynomial superposition (GBPS) parametric relationship is used to describe the optical properties o f CIGS films below, above and through the bandgap energy. The present resul ts show that spectroscopic ellipsometry may be used in situ to monitor and optimize him growth conditions and achieve high efficiencies. (C) 2001 Else vier Science B,V, All rights reserved.