High Quantum Efficiency Dependence on Structure Optimizatin for Gallium Nitride Photocathode

Abstract:

We optimized the gallium nitride(GaN)photocathode’s structure in three aspects for higher quantum efficiency. AlN is used to replace GaN as the buffer layer, which can act as potential barrier to reflect electrons back to surface. The optimal thickness of emission layer is calculated as 162.5nm, and considering the graded doping profile, we optimized the thickness as 180nm. Three built-in electric fields are introduced by Mg graded doping, and the intensities of the high fields are calculated to give the quantitive results of their influence on quantum efficiency. After surface cleaning and activation, quantum efficiency of the optimized sample was greatly increased and the highest value of 56% was achieved at 5.20eV. More quantum efficiency enchancement is possible by further optimizing the photocathode structure.

• Periodical: Advanced Materials Research (Volumes 306-307)
• Pages: 309-314
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.306-307.309
• Online since: August 2011
• Authors: Xiao Qian Fu, Xiao Hui Wang, Yong Fu Yang, Ben Kang Chang
• Keywords: Gallium Nitride(GaN) Photocathode, Quantum Efficiency, Structure Optimization

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