Highly Luminescent MgZnO/ZnO Multiple Quantum Wells for Photonics Devices

Abstract

Multiple quantum wells (MQWs) have enabled a myriad of technological applications; however, their optical emission is currently severely constrained by the presence of undesirable defects, which limit their performance in advanced photonic devices. Here, we present a new route to achieve highly luminescent oxide-based MQWs by rapid remote plasma annealing (RRPA) in hydrogen. We demonstrate that the optical emission from the MgZnO/ZnO MQWs can be enhanced substantially by this plasma method, with its emission intensity increased by more than 10 times after being treated for 40 s. Concurrently, the emissions associated with both basal stacking faults and point defects are completely quenched. Based on temperature- and excitation-density-dependent luminescence results, the enhancement of the MQW emission is attributed to the passivation of competitive recombination channels. Additionally, the exciton–optical phonon coupling strength, deduced from the temperature-dependent MQW spectral line width, shows clear evidence for significantly enhanced phonon coupling as a result of exciton screening effects. This rapid plasma procedure presents a versatile method to enhance the optical quality of oxide-based MQW structures and could open the door to high-efficiency photonic devices.