Effects of Coulomb screening and disorder on an artificial graphene based on nanopatterned semiconductor

Abstract

A residual disorder in the gate system is the main problem on the way to create artificial graphene based on two-dimensional electron gas. The disorder can be significantly screened/reduced due to the many-body effects. To analyse the screening/disorder problem we consider AlGaAs/GaAs/AlGaAs heterostructure with two metallic gates. We demonstrate that the design least susceptible to the disorder corresponds to the weak coupling regime (opposite to tight binding) which is realised via a system of quantum anti-dots. The most relevant type of disorder is the area disorder which is a random variation of areas of quantum anti-dots. The area disorder results in the formation of puddles. Other types of disorder, the position disorder and the shape disorder, are practically irrelevant. The formation/importance of puddles dramatically depends on the parameters of the nanopatterned heterostructure. A variation of the parameters by 20–30% can change the relative amplitude of puddles by orders of magnitude. Based on this analysis we formulate criteria for the acceptable design of the heterostructure aimed at the creation of the artificial graphene.