Four-point measurements of n- and p-type two-dimensional systems fabricated with cleaved-edge overgrowth

TL;DR

This paper introduces a novel contact design enabling four-terminal magnetotransport measurements of two-dimensional electron and hole systems created by cleaved-edge overgrowth, revealing fractional quantum Hall features in both n- and p-type samples.

Contribution

It presents a new lithographic patterning and etching technique for fabricating finger-shaped leads on cleaved-edge 2D systems, allowing detailed transport measurements.

Findings

Observation of fractional quantum Hall features in both n- and p-type systems.

Detection of higher-order fractional quantum Hall fractions in n-type modulation-doped samples.

Successful demonstration of four-point measurements on cleaved-edge 2D systems.

Abstract

We demonstrate a contact design that allows four-terminal magnetotransport measurements of cleaved-edge overgrown two-dimensional electron and hole systems. By lithographically patterning and etching a bulk-doped surface layer, finger-shaped leads are fabricated, which contact the two-dimensional systems on the cleave facet. Both n- and p-type two-dimensional systems are demonstrated at the cleaved edge, using Si as either donor or acceptor, dependent on the growth conditions. Four-point measurements of both gated and modulation-doped samples yield fractional quantum Hall features for both n- and p-type, with several higher-order fractions evident in n-type modulation-doped samples.