Diffusion of photo-excited holes in viscous electron fluid

TL;DR

This paper investigates how photo-excited holes diffuse in a viscous electron fluid within a high-mobility GaAs channel, revealing hydrodynamic behavior and quantifying diffusion properties of the electron-hole mixture.

Contribution

It introduces a framework for understanding ambipolar diffusion in a viscous electron fluid with multiple hole types, providing new insights into their hydrodynamic characteristics.

Findings

Identification of a three-component hydrodynamic mixture of electrons and holes.

Measurement of diffusion lengths and ambipolar diffusion coefficient.

Determination of the effective viscosity of the electron-hole system.

Abstract

The diffusion of photo-generated holes is studied in a high-mobility mesoscopic GaAs\ channel where electrons exhibit hydrodynamic properties. It is shown that the injection of holes into such an electron system leads to the formation of a hydrodynamic three-component mixture consisted of electrons and photo-generated heavy and light holes. The obtained results are analyzed within the framework of ambipolar diffusion, which reveals characteristics of a viscous flow. Both hole types exhibit similar hydrodynamic characteristics. In such a way the diffusion lengths, ambipolar diffusion coefficient and the effective viscosity of the electron-hole system are determined.