Breakdown electron-hole symmetry in graphene structure with a semiconductor gate

TL;DR

This paper investigates how electron-hole symmetry in graphene structures with semiconductor gates is broken due to potential asymmetry, analyzing electrical and optical properties across various substrates and comparing with experimental data.

Contribution

It provides a detailed theoretical analysis of electron-hole symmetry violation in graphene with semiconductor gates, including potential drop effects and substrate influences.

Findings

Potential asymmetry causes electron-hole symmetry breaking.

Calculated dependencies match experimental data.

Different substrates affect optical conductivity behaviors.

Abstract

The electron-hole symmetry in the structure "graphene - insulating substrate -semiconductor gate" is violated due to an asymmetrical drop of potential in the semiconductor gate under positive or negative biases. The gate voltage dependencies of concentration and conductivity are calculated for the case of SiO_2 substrate placed over low- (moderate-) doped p-Si. Similar dependencies of the optical conductivity are analyzed for the case of high-kappa substrates (AlN, Al_2O_3, HfO_2, and ZrO_2). The comparison of our results with experimental data shows a good agreement for both cases.