Hot-electron magnetospectroscopy in resonant tunneling devices: A probe of conduction-band anisotropy

Abstract

We report a series of magnetotransport measurements on two double barrier resonant tunneling devices based on n-GaAs/(AlGa)As. The central GaAs wells have widths of 60 and 120 nm. Many well-defined quantum resonances are observed in the conductance even at room temperature and up to 70 resonances are observed at liquid helium temperatures. The existence of these resonances indicates that a significant fraction of the conduction electrons travel ballistically over distances >0.3 μm. When a magnetic field is applied in the plane of the well (B⊥J) tunneling takes places into two distinct types of quantum states: traversing states in which the electrons interact with both barriers and skipping states in which the electrons only interact with the emitter barrier. Rotation of the magnetic field in the (100) plane parallel to the barriers reveals the anisotropy in the Γ conduction band at high electron energies.