Effect of nano-scale surface roughness on transverse energy spread from GaAs photocathodes

TL;DR

This paper investigates how nanoscale surface roughness influences the transverse energy spread of electrons emitted from GaAs photocathodes, providing insights into experimental discrepancies and emission mechanisms.

Contribution

It introduces a model linking nanoscale surface roughness to electron emission characteristics, clarifying previous experimental controversies.

Findings

Nanoscale roughness can alter transverse energy spread by nearly tenfold.

The model explains the dependence of energy spread on incident light wavelength.

Results reconcile conflicting experimental observations.

Abstract

High quantum yield, low transverse energy spread and prompt response time make GaAs activated to negative electron affnity, an ideal candidate for a photocathode in high brightness photoinjectors. Even after decades of investigation, the exact mechanism of electron emission from GaAs is not well understood. We show that a nanoscale surface roughness can affect the transverse electron spread from GaAs by nearly an order of magnitude and explain the seemingly controversial experimental results obtained so far. This model can also explain the measured dependence of transverse energy spread on the wavelength of incident light.