A Hybrid Al(0.10)Ga(0.90)As/AlAs Bilayer Electron System

TL;DR

This paper reports the fabrication and characterization of a hybrid bilayer electron system combining AlAs and AlGaAs quantum wells, demonstrating tunable electron confinement and asymmetric electronic properties.

Contribution

It introduces a novel hybrid bilayer structure with strongly asymmetric electronic properties and tunable carrier confinement using gating techniques.

Findings

Distinct cyclotron masses in AlAs and AlGaAs layers

Effective g-factors differ significantly between layers

Gate control enables selective confinement of electrons

Abstract

We have fabricated a device composed of two closely coupled two-dimensional electron systems, one of which resides within an AlAs quantum well (QW) at the X point of the Brillouin zone (BZ), while the other is contained at the $\Gamma$ point of the BZ in the alloy Al_{0.10}Ga_{0.90}As, grown directly below the AlAs QW. The electronic properties of these two systems are strongly asymmetric: the respective cyclotron masses in the AlAs and the Al_{0.10}Ga_{0.90}As layers, measured in units of the free electron mass, are 0.46 and 0.07, while the effective electron g-factors are approximately 8.5 and 0. With the help of front and back gates, we can confine mobile carriers to either or both of the two QWs, as confirmed by magnetotransport measurements.