Abstract:

Photocurrent noise, a.c. photoexcitation frequency spectra of photoconductivity and luminescence have been studied on ZnS crystals. ZnS exhibits noise spectra similar to those observed on CdS by Brophy and by Van Vliet. Comparing photocurrent noise with theoritical photon induced noise, deduced by a.c. frequency response, excess noise was determined. The excess noise varied within a factor 3-103 for various crystals. Attempts have been made to detect noise in luminescence emission (a contactless method). A highly sensitive noise detector system was developed, able to detect 100% deviations from the photon noise level of a blackbody radiation. No noise was observed in luminescence as could be hope for, if high excess noise is associated with free electron density fluctuations in the bulk. © 1957.