Direct observation of infrared photoluminescence of spray-deposited CdS:In thin films

Infrared photoluminescence spectra (in the range 0.9–1.4 eV) of the as-deposited CdS:In thin films prepared by the spray pyrolysis technique were recorded at different laser powers and different film temperatures in the range 24–130 K. The spectra show an infrared band centred at 1.06 eV, which have a structure and asymmetry. The structure might be attributed to active defect states which are produced through the growth of the film and might be partially due to coupling to longitudinal phonon. Gaussian peaks were used to deconvolute the spectrum by using nonlinear square fit. The Gaussian peaks used in the fit are expected to fit the spectra taken at different laser powers and different temperatures. These results are discussed in view of the importance of CdS as a window layer for photovoltaic heterojunction solar cells.