Surface-Assisted Luminescence: the PL Yellow Band and the EL of n-GaN Devices

TL;DR

This paper demonstrates that the yellow band in GaN photoluminescence and electroluminescence originates from surface-assisted luminescence effects, emphasizing the importance of device-level analysis over bulk assumptions.

Contribution

It introduces a model for GaN surface devices showing that surface effects significantly influence luminescence measurements, challenging the traditional bulk emission perspective.

Findings

Yellow band PL is surface-assisted luminescence.

Electroluminescence in n-GaN devices is predicted by the model.

Device effects are crucial in interpreting luminescence data.

Abstract

Although everybody should know that measurements are never performed directly on materials but on devices, this is not generally true. Devices are physical systems able to exchange energy and thus subject to the laws of physics, which determine the information they provide. Hence, we should not overlook device effects in measurements as we do by assuming naively that photoluminescence (PL) is bulk emission free from surface effects. By replacing this unjustified assumption with a proper model for GaN surface devices, their yellow band PL becomes surface-assisted luminescence that allows for the prediction of the weak electroluminescence recently observed in n-GaN devices when holes are brought to their surfaces.