PHOTOLUMINESCENCE OF THE INTERFACE OF SnO_2:F/CdS:In/CdTe THIN FILM SOLAR CELLS PREPARED PARTIALLY BY THE SPRAY PYROLYSIS TECHNIQUE

摘要

CdS/CdTe solar cells were built by depositing a 200 nm layer of SnO_2:F on glass substrates by the spray pyrolysis (SP) technique, a 500 nm CdS:In layer by the same technique and a 1-1.5 μm CdTe layer by vacuum evaporation. The cells were CdCl_2 heat-treated in nitrogen atmosphere for 30 minutes at 350 C. The photoluminescence (PL) spectra were measured at the CdS/CdTe interface for two cells with different values of the CdTe layer's thickness at temperature T = 60 K. A deconvolution peak fit was performed from which it is found that the peaks are characteristic of the solid solution CdS_xTe_(1-x). The parabolic relation that relates the bandgap energy with the composition was used to estimate x, where x is [S]/([Te]+[S]) and [Te], [S] are the concentrations of Te and S atoms respectively. The results show that the interface is smooth and the change of the bandgap occurs gradually.