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

TL;DR

This paper investigates electron flow across an etched barrier in a 2D electron gas, revealing field emission phenomena, bistability, and heating instabilities that explain recent experimental observations in similar devices.

Contribution

It demonstrates field emission from a 2DEG into a second 2DEG and identifies bistability and heating effects as key behaviors.

Findings

Rapid current increase at field emission threshold

Intrinsic bistability above the threshold

Heating instability in the second 2DEG

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.