Enhancement of Photoemission on P-type GaAs using Surface Acoustic Waves

TL;DR

This study shows that surface acoustic waves can significantly enhance photoemission efficiency in p-type GaAs photocathodes by increasing electron lifetime and quantum efficiency, with practical fabrication steps demonstrated.

Contribution

It introduces a novel method of using surface acoustic waves to improve GaAs photocathode performance, supported by simulations and experimental fabrication procedures.

Findings

Electron effective lifetime increased by 10-20x

Quantum efficiency improved by 2-3x

Device fabrication with ZnO layer is feasible

Abstract

We demonstrate that photoemission properties of GaAs photocathodes (PCs) can be altered by surface acoustic waves (SAWs) generated on the PC surface due to dynamical piezoelectric fields of SAWs. Simulations with COMSOL indicate that electron effective lifetime in p-doped GaAs may increase by a factor of 10x to 20x. It implies a significant, by a factor of 2x to 3x, increase of quantum efficiency (QE) for GaAs PCs. Essential steps in device fabrication are demonstrated, including deposition of an additional layer of ZnO for piezoelectric effect enhancement, measurements of I-V characteristic of the SAW device, and ability to survive high-temperature annealing.