Resonant interband tunnelling in InSb electron inversion layers

The authors investigate resonant interband tunnelling in asymmetrical double-barrier devices. The electrodes consist of degenerate p-type bulk InSb and the low-work-function metal Yb. A two-dimensional electron inversion well is separated from the bulk by a bandgap barrier and from the metal by a thin oxide barrier. Current peaks at forward biases and distinct structures in the reverse current-voltage characteristic at 4.2 K are explained in terms of transverse wavevector conservation in tunneling from the electron subbands into the valence band and vice versa. Concerning the bias position of the current peaks in the forward characteristic the role of wavevector conservation is proved quantitatively by measurements under quantizing magnetic fields. In the NDC region current peak-to-valley ratios up to 7.4 at 4.2 K and 2.0 at 77 K are achieved.