On the limits to mobility in InAs quantum wells with nearly lattice-matched barriers

TL;DR

This study investigates the factors limiting electron mobility in InAs quantum wells with nearly lattice-matched barriers, identifying interface roughness, alloy disorder, and charged defects as key scattering mechanisms, and achieving high mobility values.

Contribution

It provides a detailed analysis of scattering mechanisms affecting mobility in InAs quantum wells and demonstrates high mobility using dual-gated devices.

Findings

Mobility limited by interface roughness in narrow wells.

Alloy disorder and interface roughness affect wide wells at high density.

Achieved electron mobility exceeding 750,000 cm²/Vs at 2 K.

Abstract

The growth and the density dependence of the low temperature mobility of a series of two-dimensional electron systems confined to un-intentionally doped, low extended defect density InAs quantum wells with Al$_{1-x}$Ga$_{x}$Sb barriers are reported. The electron mobility limiting scattering mechanisms were determined by utilizing dual-gated devices to study the dependence of mobility on carrier density and electric field independently. Analysis of the possible scattering mechanisms indicate the mobility was limited primarily by rough interfaces in narrow quantum wells and a combination of alloy disorder and interface roughness in wide wells at high carrier density within the first occupied electronic sub-band. At low carrier density the functional dependence of the mobility on carrier density provided evidence of coulombic scattering from charged defects. A gate-tuned electron mobility exceeding 750,000 cm$^{2}$/Vs was achieved at a sample temperature of 2 K.