Anomalous behaviour in the capacitance of selenium Schottky diodes

Abstract

Measurements on Se–Tl, Se–Bi, and Se–Au Schottky diodes, fabricated by evaporation of thallium, bismuth, or gold respectively, on a layer of crystallized selenium have shown an anomalous minimum of incremental capacitance with variation of applied voltage at a frequency below about 1 kHz. The voltage of the minimum varies consistently with the estimated barrier height of the junctions and suggests that it arises from a deep level located some 0.4 eV above the valence band of trigonal selenium. The disappearance of the effect with increasing frequency, while qualitatively consistent with this interpretation, indicates the level to be at 0.6 eV.