Dielectric Breakdown in Cadmium Sulfide

The dielectric breakdown field strength for CdS has been measured by a technique employing blocking contacts on conducting crystals. Values obtained with different crystals are in the range 0.9×${10}^6$ to 2.5×${10}^6$ volts/cm. Experiments in which carriers are injected by intermittent illumination show that impact ionization does not occur during breakdown. A variety of evidence is presented indicating that breakdown is due to internal field emission.