Fabrication of Artificial Graphene in a GaAs Quantum Heterostructure

TL;DR

This paper reports the fabrication of high-resolution artificial graphene in a GaAs/AlGaAs quantum well, enabling potential observation of massless Dirac fermions in a tunable semiconductor system.

Contribution

It introduces a novel fabrication process for artificial graphene with the smallest lattice period reported in GaAs systems, using optimized electron-beam lithography and reactive ion etching.

Findings

Lattice period as small as 50 nm achieved

Optimized etching process developed

Potential to observe Dirac fermions in semiconductor

Abstract

The unusual electronic properties of graphene, which are a direct consequence of its two-dimensional (2D) honeycomb lattice, have attracted a great deal of attention in recent years. Creation of artificial lattices that recreate graphene's honeycomb topology, known as artificial graphene, can facilitate the investigation of graphene-like phenomena, such as the existence of massless Dirac fermions, in a tunable system. In this work, we present the fabrication of artificial graphene in an ultra-high quality GaAs/AlGaAs quantum well, with lattice period as small as 50 nm, the smallest reported so far for this type of system. Electron-beam lithography is used to define an etch mask with honeycomb geometry on the surface of the sample, and different methodologies are compared and discussed. An optimized anisotropic reactive ion etching process is developed to transfer the pattern into the AlGaAs layer and create the artificial graphene. The achievement of such high-resolution artificial graphene should allow the observation for the first time of massless Dirac fermions in an engineered semiconductor.