Magneto-photoluminescence of charged excitons from MgZnO/ZnO heterojunctions

TL;DR

This study investigates how high magnetic fields affect photoluminescence in MgZnO/ZnO heterojunctions, revealing features consistent with charged excitons and quantum Hall states, advancing understanding of 2DEG optical properties.

Contribution

It provides experimental evidence supporting the charged exciton model over the conventional 2DEG-hole transition model in high magnetic fields.

Findings

PL redshift observed up to 20 T

Spectral lineshape changes at high fields correlate with quantum Hall states

Charged exciton model better explains the PL features

Abstract

We report on the photoluminescence (PL) properties of MgZnO/ZnO heterojunctions grown by plasma-assisted molecular-beam epitaxy. Influence of the applied magnetic field (B) on the radiative recombination of the two-dimensional electron gas (2DEG) is investigated up to 54 T. An increase in magnetic field in the range of B <= 20 T results in a redshift in the PL. Abrupt lineshape changes in the PL spectra are observed at higher magnetic fields, in correlation with the integer quantum Hall states. We attempt to interpret these features using the conventional model for the 2DEG-related PL based on the transition between the 2DEG and a hole as well as a model taking a bound state effect into account, i.e., a charged exciton. The comparison about the adequateness of these models was made, being in favor of the charged exciton model.