QUALITY-CONTROL AND CHARACTERIZATION OF CU(IN,GA)SE-2-BASED THIN-FILMSOLAR-CELLS BY SURFACE PHOTOVOLTAGE SPECTROSCOPY

Surface photovoltage spectroscopy (SPS) has been used for quality cont rol of ZnO/CdS/Cu(In,Ga)Se-2 (CIGS) thin-film solar cells. The results show that SPS makes it possible to detect ''hard failures'' following CIGS deposition, and both ''hard'' and ''soft'' failures following Cd S deposition and following ZnO deposition. In addition, semi-quantitat ive screening of CdS/CIGS and ZnO/CdS/CIGS samples is possible. Hence, SPS is suggested as a useful tool for in-line monitoring of CIGS-base d solar cell production lines. Moreover, SPS is shown to yield importa nt new information regarding CIGS-based solar cells: (a) A deep gap st ate is found in samples of superior performance. (b) As opposed to the CdS/CIGS structure, a marked decrease in the open-circuit voltage upo n Na contamination in ZnO/CIGS structures is found.