A gallium arsenide double injection diode

Abstract

The diode consists of vacuum-deposited thin film electrodes on a single crystal substrate of semi-insulating gallium arsenide. Two types of electrical characteristics were observed at room temperature according to whether the principal dopant was copper or oxygen for type 1 or chromium for type 2. Both types displayed current-controlled negative resistance, and in the type 1 characteristic this involved a rapid switching from low to high conductivity at a voltage threshold which could be reduced by illumination. It is believed that the type 1 characteristic is produced by the mechanism of filamentary double injection breakdown, and that the type 2 characteristic is produced when self-heating effects occur before the threshold for such a breakdown. A description is given of the effect on the electrical characteristics of variations in the method of construction, and of magnetic fields, illumination and temperature changes. Rapid changes of the threshold voltage as the temperature is changed slowly are related to peaks in the thermally stimulated conductivity of the substrate material and thus are shown to be due to shallow trapping effects. These observations are consistent with the theoretical predictions of Keating for the effect of shallow trapping upon a double injection characteristic. It is deduced that the peak to valley ratio for the negative resistance may be controlled by the adjustment of the concentration of shallow minority carrier traps.