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Effect of different epitaxial structures on GaAs photoemission.

Authors
  • Zou, Jijun
  • Zhang, Yijun
  • Deng, Wenjuan
  • Jin, Jieyun
  • Chang, Benkang
Type
Published Article
Journal
Applied Optics
Publisher
The Optical Society
Publication Date
Sep 20, 2011
Volume
50
Issue
27
Pages
5228–5234
Identifiers
DOI: 10.1364/AO.50.005228
PMID: 21947040
Source
Medline
License
Unknown

Abstract

The quantum efficiency equations of two different structure reflection-mode GaAs photocathodes with back interface recombination velocity have been solved from the diffusion equations. One structure consists of GaAs substrate and an epitaxial GaAs active layer (GaAs-GaAs) and another structure consists of GaAs substrate, an epitaxial AlGaAs buffer layer, and a GaAs active layer (AlGaAs-GaAs). The experimental results show that the quantum efficiency of long-wavelength photons and the integral sensitivities for GaAs-GaAs cathodes both increase with the increase in the active layer thickness, which is due to the increase of electron diffusion length. The quantum efficiency of long-wavelength photons and the integral sensitivity of AlGaAs-GaAs cathodes are greater than those of GaAs-GaAs cathodes with an identical active layer thickness, which is attributed to the AlGaAs buffer layer. The buffer layer can reflect electrons and improve the quality of the GaAs active layer. Through the theoretical simulation, we found the active layer thickness for AlGaAs-GaAs cathodes has an optimum value at which the cathodes achieve the maximum sensitivity.

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