Photoluminescence in amorphous As2S3

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Abstract
Photoluminescence in amorphous As2S3 has been investigated at temperatures down to 4 K, and excitation spectra are presented for the first time. The luminescence for evaporated films shows a substantial reduction on annealing, and this supports the model of Kilomiets (1970, 1972) in which recombination occurs via charged defects in the forbidden gap, formed by broken bonds. Luminescence is only observed with exciting photon energies corresponding to absorption coefficients of less than 104 cm-1, with the highest efficiency occurring at the lowest absorption. A model is discussed in which photons create exciton-like pairs in the vicinity of the charged defects.