A device layout for tunneling spectroscopy of barrier-separated electron systems with tunable dimensionality

Abstract

A selective depletion scheme relying on self-aligned side gates is used to establish independent Ohmic contacts to two low-dimensional electron gases separated by a tunneling barrier. The self-aligned side gate technique is also demonstrated to be suitable for inducing an electrically tunable lateral confinement on the active region of the tunneling device via a central gate. As the central gate voltage is increased, the measured tunneling differential conductance clearly reveals a transition from tunneling between two-dimensional electron gases to tunneling between one-dimensional quantum wire states. The one-dimensional subband spacing of the collector electron channel could be continuously varied up to 6 meV.