Tranverse magnetotunneling in AlxGa1-xAs capacitors. I. Angular dependence

Abstract

The angular dependence of transverse magnetotunneling from an accumulation layer on n - type GaAs has been studied in four n - type GaAsAlxGa1-xAsn+-type GaAs capacitors with values of substrate doping NS between 1.2×1015 and 7×1015 cm-3. At high current densities, when tunneling is from excited subbands of the two-dimensional electron gas (2DEG) of the accumulation layer, there is a remarkably sharp angular dependence of the voltage required for a given tunnel current J when J is perpendicular to the magnetic field B. The angular width of the dependence is 2°and is independent of NS. The magnitude of the angular dependence is greatest for low NS. The angular dependence is observed when the diameter of the cyclotron orbit of electrons in the 2DEG is less than the width of the accumulation layer at the Fermi energy, resulting in a reduction of the number of electrons with a velocity component normal to the n - type GaAs/AlxGa1-xAs interface that are available for tunneling. © 1989 The American Physical Society.