Evidence of localization effect on photoelectron transport induced by alloy disorder in nitride semiconductor compounds

TL;DR

This study investigates how alloy disorder in InGaN affects photoelectron transport, revealing electron localization at low temperatures through photoemission spectroscopy, which impacts the material's photoemission efficiency.

Contribution

The paper provides experimental evidence of electron localization due to alloy disorder in InGaN, affecting photoelectron transport at low temperatures.

Findings

Photoemission quantum yield drops significantly in InGaN at low temperatures.

Electron localization caused by alloy disorder is confirmed by spectral changes.

Transport freezing occurs in InGaN but not in GaN, indicating material-specific effects.

Abstract

Near-bandgap photoemission spectroscopy experiments were performed on p-GaN and p-InGaN/GaN photocathodes activated to negative electron affinity. The photoemission quantum yield of the InGaN samples drops by more than one order of magnitude when the temperature is decreased while it remains constant on the GaN sample. This indicates a freezing of photoelectron transport in p-InGaN that we attribute to electron localization in the fluctuating potential induced by the alloy disorder. This interpretation is confirmed by the disappearence at low temperature of the peak in the photoemission spectrum that corresponds to the contribution of the photoelectrons relaxed at the bottom of the InGaN conduction band.