PHOTOCONDUCTIVITY OF ZINC SULFIDE CRYSTALS EXCITED WITH LASER RADIATION NEAR THE FUNDAMENTAL ABSORPTION EDGE.

The dependence of the photoconductivity i//p//h on the intensity of nitrogen laser radiation L was determined for high-resistivity zinc sulfide crystals in a longitudinal cell. The photocurrent-voltage characteristics were also determined. The dependence was i//p//h varies directly as L**k and k decreased from 2 to 1 when the voltage across the electrodes was increased from 300 to 1400 V. The photocurrent-voltage characteristics were strongly nonlinear and the power exponent ranged from 3 to 8 when L was reduced by 1. 5 orders of magnitude from the maximum value amounting to 5 multiplied by (times) 10**2**2 photons cm** minus **2 multiplied by (times) sec** minus **1. The characteristics depended on the electrode polarity. The non-linearity of the lux-ampere characteristics suggested that carrier generation was due to two-photon absorption. The strong dependence of i//p//h on the voltage was clearly due to the important role played by recombination and possibly due to changes in the drift processes in the photoconductivity mechanism. The latter hypothesis was confirmed by the dependence of the carrier transit time on the laser radiation intensity.