Surface-field-induced tunnel junctions on InAs

Abstract
We report on tunneling between the two-dimensional electron inversion layer on a degenerate p-InAs substrate and the three-dimensional bulk valence states in Yb/oxide/InAs tunnel junctions. The current-voltage characteristics show negative differential conductance with current peak-to-valley ratio up to 2.7 (17) at T=300 K (77 K). The inversion layer is induced by the high electric surface field that arises from the low work function of the Yb electrode. Tunneling across the oxide provides a low-resistive contact of the metal to the electron layer.