High-quality quantum point contact in two-dimensional GaAs (311)A hole system

TL;DR

This paper demonstrates high-quality ballistic transport in a GaAs (311)A 2D hole system with quantized conductance plateaus, modeled by considering hole density and channel width variations.

Contribution

It reports the fabrication and analysis of a GaAs (311)A QPC showing up to 11 quantized conductance plateaus, with a simple model explaining the data.

Findings

Observation of up to 11 quantized conductance plateaus.

Conductance features explained by a model considering hole density and channel width.

Ballistic transport confirmed in high-quality GaAs (311)A 2D hole system.

Abstract

We studied ballistic transport across a quantum point contact (QPC) defined in a high-quality, GaAs (311)A two-dimensional (2D) hole system using shallow etching and top-gating. The QPC conductance exhibits up to 11 quantized plateaus. The ballistic one-dimensional subbands are tuned by changing the lateral confinement and the Fermi energy of the holes in the QPC. We demonstrate that the positions of the plateaus (in gate-voltage), the source-drain data, and the negative magneto-resistance data can be understood in a simple model that takes into account the variation, with gate bias, of the hole density and the width of the QPC conducting channel.