Landau-level spectra of conduction electrons at an InAs surface

Abstract

I report magneto-oscillatory effects in tunneling through in As-oxide-Pb junctions, which reflect the Landau levels of conduction electrons near the InAs- oxide interface. These oscillatory effects, which have been observed in transverse as well as longitudinal magnetic fields, are understood in terms of a qualitative theoretical picture. From the longitudinal magneto-oscillations, we have obtained that the effective cyclotron mass m$sub 0$*/m = 0.0215 plus-or- minus 0.0005 at the conduction-band edge and that, at energies within 400 meV above the band edge, it increases linearly with increasing energy at a rate of 1.2times10$sup -4$/meV. This value of m$sub 0$* is approx. 7% smaller than that obtained from cyclotron resonance and magneto-phonon experiments on bulk InAs. The transverse magneto-oscillations are identified with Landau levels of electrons whose cyclotron orbits graze the oxide potential barrier. The level broadening GAMMA, as deduced from the magnetic field dependence of the oscillation amplitude, corresponds to a relaxation time approx. 10$sup -14$ sec. Within our experimental uncertainties, GAMMA increases linearly with increasing excitation energy. (AIP)