Anomalous Electrical Properties of p-Type Indium Arsenide

Abstract

Hall constants and resistivities have been measured as a function of carrier concentration for zinc-doped, single crystal p-type indium arsenide at temperatures ranging from 4.2 to 500°K. For carrier concentrations greater than 2×1017 cm−3 the electrical properties appear to be normal for a material of this type. However, for smaller carrier concentrations anomalies appear which consist of dips and double reversals in the Hall constant-temperature relationship. These results are in agreement with data reported by Folberth and Weiss for polycrystalline material. A mechanism involving inhomogeneities arising from the inclusion of microscopic n-type regions in p-type material is proposed to explain the anomalies. Such small n-type regions could arise from the aggregation of impurities about dislocations. On the basis of this model, it is predicted that the anomalies should be removed by appropriate heat treatment of the material. The prediction is confirmed by experiment. Recent work of Rupprecht suggests that the anomalous behavior of p-type InAs is due to an n-type surface layer which can be introduced by grinding or polishing, and removed by etching. This is consistent with the mechanism we propose.