Two-Dimensional Electron Gas in InGaAs/InAlAs Quantum Wells

TL;DR

This study investigates the electronic properties of two-dimensional electron gases in InGaAs/InAlAs quantum wells, revealing insights into scattering mechanisms and surface Fermi level positioning through low temperature transport measurements.

Contribution

The paper provides detailed characterization of electron mobility and scattering in InGaAs/InAlAs quantum wells, highlighting the dominance of short-range alloy scattering and quantifying the surface Fermi level.

Findings

Mobility remains nearly constant for setback distances >50nm.

Short-range alloy scattering is identified as the main scattering mechanism.

Fermi level at the surface is 0.36 eV above the conduction band.

Abstract

We designed and performed low temperature DC transport characterization studies on two-dimensional electron gases confined in lattice-matched In$_{0.53}$Ga$_{0.47}$As/In$_{0.52}$Al$_{0.48}$As quantum wells grown by molecular beam epitaxy on InP substrates. The nearly constant mobility for samples with the setback distance larger than 50nm and the similarity between the quantum and transport life-time suggest that the main scattering mechanism is due to short range scattering, such as alloy scattering, with a scattering rate of 2.2 ps$^{-1}$. We also obtain the Fermi level at the In$_{0.53}$Ga$_{0.47}$As/In$_{0.52}$Al$_{0.48}$As surface to be 0.36eV above the conduction band, when fitting our experimental densities with a Poisson-Schr\"odinger model.