Photoconductivity and dark-conductivity studies of CdS1-xSex(Cu) sintered layers.

Abstract

The photoconductivity and dark conductivity of ${\mathrm{CdS}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Se}}_{\mathrm{x}}$(Cu) layers sintered at 773 K have been studied in a configuration similar to that under actual use in a solid-state image intensifier. The dark current shows linear dependence on voltage at lower voltages. At higher voltages the current shows non-Ohmic behavior. The photocurrent is found to be space-charge limited at the lowest voltage studied; this behavior is explained by the nonuniform illumination of the sample. Supralinearity and subsequent sublinearity in the photocurrent dependence on light intensity indicate the presence of sensitizing centers near the valence band as well as an exponential trap distribution nearer the conduction band. The thermal quenching of the photocurrent seems to confirm this. The unusual decrease in the dark current with increase in temperature around room temperature (313 K) can be explained on the basis of these centers. The spectral studies indicate the filtering effect of selective absorption because of the particular configuration. Infrared spectral studies indicate the presence of sensitizing centers about 1 eV above the valence band.