GaN/AlGaN 2DEGs in the quantum regime: Magneto-transport and photoluminescence to 60 tesla

TL;DR

This study investigates GaN/AlGaN 2DEGs under magnetic fields up to 60 T, revealing quantum Hall effects, fractional states, and Landau level properties through combined magneto-transport and photoluminescence measurements.

Contribution

It provides new insights into high-field quantum phenomena in GaN/AlGaN 2DEGs, including direct observation of Landau level dispersion and fractional quantum Hall states.

Findings

Quantum limit exceeded with Landau level filling factor < 1

Evidence for the $ u=2/3$ fractional quantum Hall state

Synchronous quantum oscillations in PL intensity and resistivity

Abstract

Using high magnetic fields up to 60 T, we report magneto-transport and photoluminescence (PL) studies of a two-dimensional electron gas (2DEG) in a GaN/AlGaN heterojunction grown by molecular-beam epitaxy. Transport measurements demonstrate that the quantum limit can be exceeded (Landau level filling factor $\nu < 1$), and show evidence for the $\nu =2/3$ fractional quantum Hall state. Simultaneous optical and transport measurements reveal synchronous quantum oscillations of both the PL intensity and longitudinal resistivity in the integer quantum Hall regime. PL spectra directly reveal the dispersion of occupied Landau levels in the 2DEG and therefore the electron mass. These results demonstrate the utility of high (pulsed) magnetic fields for detailed measurements of quantum phenomena in high-density 2DEGs.