Investigation of resonant tunnelling from miniband emitter states in double barrier structures based on (AlGa)As/GaAs using high magnetic fields

Abstract

The authors present an investigation into the electrical and magnetic properties of a symmetric (AlGa)As/GaAs resonant tunnelling double barrier structure in which a superlattice (SL) is included between one of the heavily doped contacts and the adjacent barrier. With the emitter electrons confined to the miniband states of the SL (forward bias), the threshold voltage is found to decrease and the peak current density to increase. Moreover, a significant increase in phonon-assisted tunnelling is apparent with three LO-phonon satellite peaks observed in I(V). With a magnetic field applied parallel to the tunnel current direction, magneto-quantum oscillations in I(B) are observed. In forward bias only, two series of oscillations are detected in and past the valley current region with high values of the fundamental magnetic field, Bf. These two series are attributed to kperpendicular to non-conserving scattering events with and without the involvement of an LO phonon. These observations suggest that an increase in penetration of the emitter wavefunction into the emitter barrier produces an increase in LO-phonon-mediated tunnelling and novel structure in I(B).