AFM local oxidation nanopatterning of a high mobility shallow 2D hole gas

TL;DR

This paper presents a novel shallow quantum well design enabling high mobility 2D hole gases close to the surface, facilitating AFM local oxidation nanopatterning for nanodevice fabrication with demonstrated quantum point contact functionality.

Contribution

A new quantum well structure allowing independent control of depth and density, enabling high mobility 2D hole gases suitable for AFM nanopatterning.

Findings

High mobility 2D hole gas at 350A depth with 0.5 million cm^2/Vs at 4.2 K

Successful fabrication of a quantum point contact with 9 quantum steps at 50 mK

Demonstration of AFM LAO nanopatterning on the new quantum well structure

Abstract

Recently developed AFM local anodic oxidation (LAO) technique offers a convenient way of patterning nanodevices, but imposes even more stringent requirements on the underlying quantum well structure. We developed a new very shallow quantum well design which allows the depth and density of the 2D gas to be independently controlled during the growth. A high mobility (0.5 10^6 cm^2/Vs at 4.2 K) 2D hole gas just 350A below the surface is demonstrated. A quantum point contact, fabricated by AFM LAO nanopatterning from this wafer, shows 9 quantum steps at 50 mK.