Electron-Tunneling Studies of a Quantized Surface Accumulation Layer

Abstract

This paper describes an experiment on electron tunneling through $n$-type InAs-oxide-Pb junctions and discusses in detail two results which are pertinent to the quantization of an accumulation layer at the InAs surface. First, the tunneling curves $\frac{\mathrm{dI}}{\mathrm{dV}}$ vs $V$ and $\frac{d^{2}I}{d{V}^2}$ vs $V$ show structures reflecting the energy minima of two-dimensional electric subbands. The bias position of these structures gives a direct measure of the energy of the quantized levels. Second, when a quantizing magnetic field is applied perpendicular to the junction surface, oscillations are observed in the tunneling curves. These oscillations reflect the Landau-level spectra of electrons in the electric subbands. They give a direct measure of the effective mass of the surface electrons.