Ballistic electron transport exceeding 160 microns in an undoped GaAs/AlGaAs FET

TL;DR

This study demonstrates ballistic electron transport over 160 microns in undoped GaAs/AlGaAs FETs with high mobility and low scattering, revealing potential for advanced electronic applications.

Contribution

First measurement of ballistic electron transport exceeding 160 microns in undoped GaAs/AlGaAs FETs with high mobility and specular edge reflections.

Findings

Electron mobility exceeds 4 million cm^2/Vs at 4.2 K.

Ballistic transport observed over 160 microns at temperatures below 2.5 K.

Edges of the 2DEG show high specularity, enabling multiple reflections.

Abstract

We report measurements of GaAs/AlGaAs undoped field-effect transistors in which two-dimensional electron gases (2DEGs) of exceptional quality and versatility are induced without modulation doping. Electron mobilities at T=4.2 K and density 3 E11 /cm^2 exceed 4 E6 cm^2/Vs. At lower temperatures, there is an unusually large drop in scattering, such that the mobility becomes too high to measure in 100 micron samples. Below T=2.5 K, clear signatures of ballistic travel over path lengths in excess of 160 microns are observed in magnetic focusing experiments. Multiple reflections at the edges of the 2DEG indicate a high degree of specularity.