Optical parameters of chalcogenide glass multi-layers with 12–15nm modulation lengths prepared by thermal evaporation could be changed by laser irradiation. Photoluminescence studies were carried out on such non-irradiated and irradiated multi-layered samples of a-Se/As2S3 (sub-layer thickness of a-Se was 4–5nm for one set of samples and 1–2nm for the other set. However As2S3 sub-layer thickness was 11–12nm for both sets of samples.) photoluminescence intensity could be increased by several orders of magnitude by reducing the Se well layer (lower band gap) thickness and could be further increased by irradiating the samples with appropriate wavelengths in the range of the absorption edge. The broadening of luminescence bands takes place either with a decrease in Se layer thickness or with irradiation. The former was due to the change in interface roughness and defects because of the enhanced structural disorder while the latter was due to photo-induced interdiffusion. The photo-induced interdiffusion creates defects at the interface between Se and As2S3 by forming an As–Se–S solid solution. From the deconvoluted photoluminescence spectrum, it was shown that the peak photoluminescence intensity, full width half maximum, and the photoluminescence quantum efficiency of particular defects giving rise to photoluminescence, could be tuned by changing the sub-layer thickness or by interdiffusion.

Enhancement of Photoluminescence Intensity by Photo-Induced Interdiffusion in Nanolayered a-Se/As2S3 Films. K.V.Adarsh, K.S.Sangunni, S.Kokenyesi, I.Ivan, M.Shipljak: Journal of Applied Physics, 2005, 97[4], 044314 (5pp)