A novel device layout for tunneling spectroscopy of low-dimensional electron systems

We report tunneling spectroscopic investigations on a barrier separated double-electron-layer system using a novel selective depletion scheme based on self-aligned side gates. We show that the side gate technique is also suitable to impose a tunable lateral confinement on a narrow channel. From the study of tunneling processes on a single-wire device we conclude that the energetic spacing of the one-dimensional subbands can be varied from effectively zero to up to 6 meV. A simple electrostatic model confirms the order of magnitude of the measured one-dimensional level spacing.