Novel surface gate structure to induce sharp potential barriers in two-dimensional electron systems

A novel surface gate structure, consisting of a central gate and two side gates, is proposed to generate an effectively sharp potential barrier for two-dimensional electrons confined to a semiconductor heterojunction deep below the sample surface. The side gates are biased at a higher potential than the central gate to enhance the large-wave-vector Fourier components of the potential and therefore to compensate partially for the strong decay, due to fringing fields, of these components as a function of the distance below the surface. The reflection coefficient calculated for the proposed potential barrier exhibits strong oscillations as a function of barrier height, much stronger than a conventional single gate. The results suggest that the proposed gate structure should find use in realization of an electron interferometer which can serve as a building block for novel electron interference devices.