Current flow past an etched barrier: field emission from a two-dimensional electron gas

¹ Department of Physics, University of California and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
² Cavendish Laboratory, Madingley Road, Cambridge, CB3 OHE, UK

Received: 31 October 1997
Accepted: 8 December 1997

Abstract

We find that, under appropriate conditions, electrons can pass a barrier etched across a two-dimensional electron gas (2DEG) by field emission from the GaAs/AlGaAs heterojunction into a second, low-density 2DEG formed deep in the substrate. The current-voltage characteristics exhibit a rapid increase in the current at the field emission threshold and intrinsic bistability above this threshold, consistent with a heating instability occurring in the second 2DEG. These results may explain similar behaviour recently seen in a number of front-gated devices by several groups.