Interacting drift-diffusion theory for photoexcited electron-hole gratings in semiconductor quantum wells

TL;DR

This paper develops an interacting drift-diffusion theory to analyze phase-resolved transient grating spectroscopy data in semiconductor quantum wells, enabling measurement of electron-hole drag resistivity and predicting a crossover in mobility behavior.

Contribution

It introduces a novel theoretical framework linking measured mobility to Coulomb interactions, revealing a density-dependent crossover in electron-hole drag effects.

Findings

Predicted a crossover from positive to negative mobility with decreasing density.

Identified the mobility vanishing point at the crossover.

Provided a method to determine electron-hole drag resistivity from experimental data.

Abstract

Phase-resolved transient grating spectroscopy in semiconductor quantum wells has been shown to be a powerful technique for measuring the electron-hole drag resistivity $\rho_{eh}$, which depends on the Coulomb interaction between the carriers. In this paper we develop the interacting drift-diffusion theory, from which $\rho_{eh}$ can be determined, given the measured mobility of an electron-hole grating. From this theory we predict a cross-over from a high-excitation-density regime, in which the mobility has the "normal" positive value, to a low-density regime, in which Coulomb-drag dominates and the mobility becomes negative. At the crossover point, the mobility of the grating vanishes.