An estimation of the impurities causing n- to p-type inversion of conduction in thin InSb films on mica substrates

Abstract

The 0.1–0.9-μm-thick thin InSb films were prepared on mica substrates by evaporation of InSb to obtain highly sensitive magnetoresistance elements. It was observed that films thinner than 0.15 μm show p-type conduction while films thicker than 0.2 μm show n-type conduction in the extrinsic temperature range. It was also observed that the film, thinned from 0.3 to 0.1 μm by etching from the surface side, showed p-type conduction. The cause of these phenomena was investigated using a secondary ion mass spectroscopy in-depth analysis. It was observed that K, Al, Si and O atoms, constituents of mica substrates, diffused into InSb films from mica substrates. In these atoms, it was estimated that K, Al, and Si atoms could act as acceptors in an InSb crystal contributing to the inversion of conduction type.