Generation of light in epitaxial cadmium sulfide films

Lasing was observed in single-crystal (0001) CdS films grown on (0001) Al₂O₃ substrates and excited with N₂ laser radiation. Lasing emission occurred at 492 and 497 nm and the thresholds were 0.3 and 0.75 MW/cm², respectively. The half-width of the bands was ~1 nm and the divergence of the radiation was ~20°. It was assumed that the mechanisms responsible for lasing were the exciton-phonon interaction (492 nm) line and recombination in an electron-hole plasma (497 nm).