Capacitance Changes in Thin CdS Crystals under dc Bias

摘要

Appreciable increases in capacitance have been observed in thin single‐crystal CdS platelets when measured under conditions of dc bias. Data have been obtained in the frequency range 20 cps‐20 Mc/sec. Crystals could be roughly divided into two groups (denoted by I and II). Group I crystals, exhibiting an approximate V2 dependence of the I‐V characteristic, showed low‐frequency‐capacitance increases of up to a factor of ten under bias. These changes could be explained in terms of SCLC. Group II crystals, exhibiting I‐V characteristic with a voltage exponent much greater than two, showed low‐frequency‐capacitance increases of up to a factor of 1000. This behavior cannot be understood in terms of SCLC flow, and a two‐layer model is proposed which provides a satisfactory explanation.