Characterization of InSb quantum wells with atomic layer deposited gate dielectrics

TL;DR

This study investigates InSb quantum wells with atomic layer deposited Al2O3 gate dielectrics, revealing a tunable electron density and a parallel conduction channel, supported by simulations and modeling.

Contribution

It provides detailed magnetotransport characterization of InSb QWs with high-quality ALD-grown dielectrics and insights into interface effects and conduction channels.

Findings

Parallel conduction channel present at zero Vg

Electron density tunable by gate voltage with high efficiency

Saturation of electron density at large negative Vg

Abstract

We report magnetotransport measurements of a gated InSb quantum well (QW) with high quality Al2O3 dielectrics (40 nm thick) grown by atomic layer deposition. The magnetoresistance data demonstrate a parallel conduction channel in the sample at zero gate voltage (Vg). A good interface between Al2O3 and the top InSb layer ensures that the parallel channel is depleted at negative Vg and the density of two-dimensional electrons in the QW is tuned by Vg with a large ratio of 6.5x1014 m-2V-1 but saturates at large negative Vg. These findings are closely related to layer structures of the QW as suggested by self-consistent Schrodinger-Poisson simulation and two-carrier model.