Linear non-hysteretic gating of a very high density 2DEG in an undoped metal-semiconductor-metal sandwich structure

TL;DR

This paper presents a method for achieving high-density, linear, and non-hysteretic gating in undoped GaAs-AlGaAs quantum wells, enabling better understanding of mobility limits at high electron densities.

Contribution

The authors develop a fully undoped quantum well structure that maintains linear gateability at high densities, unlike doped structures.

Findings

Achieved electron densities of approximately 6×10^{11} cm^{-2} with linear gating.

Demonstrated non-hysteretic gating behavior at high densities.

Provided insights into mobility limiting mechanisms at very high densities.

Abstract

Modulation doped GaAs-AlGaAs quantum well based structures are usually used to achieve very high mobility 2-dimensional electron (or hole) gases. Usually high mobilities ($>10^{7}{\rm{cm}^{2}\rm{V}^{-1}\rm{s}^{-1}}$) are achieved at high densities. A loss of linear gateability is often associated with the highest mobilites, on account of a some residual hopping or parallel conduction in the doped regions. We have developed a method of using fully undoped GaAs-AlGaAs quantum wells, where densities $\approx{6\times10^{11}\rm{cm}^{-2}}$ can be achieved while maintaining fully linear and non-hysteretic gateability. We use these devices to understand the possible mobility limiting mechanisms at very high densities.