SELF-INDUCED TRANSMISSION AND LUMINESCENCE OSCILLATIONS IN THIN CDS FILMS

The transmission and luminescence of spray-deposited thin (6 mum) CdS films were studied below the gap (2.44 eV = 508 nm at 300 K) by the us e of the 514.5 nm and 632.8 nm lines of an argon- and He-Ne laser, res pectively. Oscillations with a frequency of about 0.03-0.05 Hz were ob served in both effects at 300 K. The oscillations occur without any ex ternal feedback and are driven exclusively by particlar properties of the thin CdS films. An impurity band between 1.7 and 1.8 eV, which cau ses a nonequilibrium state between the generation and recombination ra te, is found to be the origin of the selfinduced oscillation effect.