Transport through a buried double-barrier single-electron transistor at low temperatures

Abstract

We report on transport and magneto-transport properties of an AlGaAs/GaAs double-barrier resonant tunneling transistor with sub-μm lateral dimensions, where lateral confinement causes quasi-zero-dimensional quantization. An MBE-grown structure was designed as a 500 nm diameter mesa on top of the two AlGaAs barriers lying 50 nm below the etched surface. A gate surrounding the mesa causes lateral confinement within the barrier region by means of its accompanying Schottky-type depletion space-charge region. It is shown that the current–voltage characteristics for such structures can be explained by using only the lateral confinement defined by the gate without assuming any defects in the mesa. Quantization effects in the emitter are found close to the first ground-state resonance in strong confinement condition. In addition, on low-doped samples no shift in the onset voltage of the first single electron step could be observed for higher magnetic fields. This effect is explained by the magnetic field dependence of the Fermi-level.