Tunneling Spectroscopy in GaAs

Abstract

Observations of tunneling in Schottky barriers made from $n$- and $p$-type GaAs with Au as the metallic element are presented in detail. The characteristics are expressed in terms of the dependence of incremental resistance $\frac{\mathrm{dV}}{\mathrm{dI}}$ on applied voltage $V$. These are interpreted in terms of a theory which uses the WKBJ approximations and a two-band formulation for the dispersion of states of the forbidden gap. An experimental determination of this dispersion is made which proves to be consistent with the theory. In this determination, a technique is introduced in which the characteristics are measured directly as $\frac{d\mathrm{ln}I}{\mathrm{dV}}$. Fine structure is observed superposed on the background characteristic at $\ifmmode\pm\else\textpm\fi{}\ensuremath{\hbar}{\ensuremath{\omega}}_{0}$ and is interpreted as a manybody polar (polaron) interaction. Some new aspects of the problem of zero-bias anomalies are presented.