Effect of CdO interlayer on electrical characteristics in Se-Bi diodes

The introduction of an interlayer of CdO, of thickness up to 0.42 mu m, between a layer of crystallized selenium and one of bismuth in the form of a Se-CdO-Bi diode, was found to increase the frequency below which negative capacitance appeared in forward bias. The effect is attributed either to increased carrier transit time across the interlayer or to a reduction of internal capacitance in the presence of an existing inductive influence. An equivalent circuit model of a Se-metal diode, involving a hypothetical fixed inductor, was developed, which correctly traces out the type of observed variation of measured diode capacitance with bias and frequency. (C) 1998 Elsevier Science B.V.