Field-effect-induced two-dimensional electron gas utilizing modulation doping for improved ohmic contacts

TL;DR

This paper presents a novel field-effect transistor design that creates a high-quality, tunable two-dimensional electron gas without remote ionized dopants, improving contact reliability and reducing charge fluctuations.

Contribution

It introduces a device architecture with modulation doping only in the contact regions, enabling better ohmic contacts and tunable electron density in the active channel.

Findings

High-quality 2DEG induced by field-effect

Wide tunability of electron density

Reliable low-resistance ohmic contacts

Abstract

Modulation-doped AlGaAs/GaAs heterostructures are utilized extensively in the study of quantum transport in nanostructures, but charge fluctuations associated with remote ionized dopants often produce deleterious effects. Electric field-induced carrier systems offer an attractive alternative if certain challenges can be overcome. We demonstrate a field-effect transistor in which the active channel is locally devoid of modulation-doping, but silicon dopant atoms are retained in the ohmic contact region to facilitate reliable low-resistance contacts. A high quality two-dimensional electron gas is induced by a field-effect and is tunable over a wide range of density. Device design, fabrication, and low temperature (T= 0.3K) transport data are reported.