Transport and drag in undoped electron-hole bilayers

TL;DR

This paper studies transport and Coulomb drag in undoped electron-hole bilayers, highlighting impurity scattering as dominant and showing drag enhancement at small layer separation due to exchange effects.

Contribution

It provides theoretical insights into the dominant scattering mechanisms and the impact of layer separation on Coulomb drag in undoped electron-hole bilayer systems.

Findings

Impurity scattering dominates resistivity in high-mobility bilayers.

Coulomb drag is significantly enhanced at small electron-hole layer separation.

Exchange effects renormalize compressibility, affecting drag.

Abstract

We investigate transport and Coulomb drag properties of semiconductor-based electron-hole bilayer systems. Our calculations are motivated by recent experiments in undoped electron-hole bilayer structures based on GaAs-AlGaAs gated double quantum well systems. Our results indicate that the background charged impurity scattering is the most dominant resistive scattering mechanism in the high-mobility bilyers. We also find that the drag transresistivity is significantly enhanced when the electron-hole layer separation is small due to the exchange induced renormalization of the single layer compressibility.