On the electrical properties of compound semiconductor interfaces in metal/insulator/ semiconductor structures and the possible origin of interface states

Electrical properties of GaAs and InP metal/insulator/semiconductor (MIS) systems are discussed from various points of view in an attempt to clarify the origin of the high density of interface states that characterizes the compound semiconductor-insulator interfaces. The density distributions of interface states in GaAs and InP MIS systems containing various insulators are reviewed, and a summary of detailed measurements of the thermal activation and photoionization of interface states in anodic native oxide/GaAs metal/oxide/semiconductor samples and anodic Al2O3/InP MIS samples is given. Various anomalies in the dynamic behaviour of these systems are pointed out. On the basis of these data, three existing models for the origin of interface states are compared in terms of their ability to explain the experimental facts. The “surface disorder model” proposed by the present researchers is shown to be capable of explaining all the dynamic anomalies in a consistent way. Finally, a promising result for the reduction of the density of interface states in InP MIS interfaces is presented and is explained in terms of the surface disorder model.