Influence of material performance parameters of GaAs/AlGaAs photoemission
摘要
Photocathode based on GaAs/AlGaAs heterojunction has been applied broadly for its broad spectral response wavelength, high quantum efficiency and low dark current. To obtain more effective photoemission, reasonable selection of material parameters of GaAs/AlGaAs heterojunction is required. In this paper on basis of three step photoemission model, the dependence of adsorption coefficient of GaAs, electron diffusion length and surface escape probability on p-type doping concentration are made analysis, and theoretic quantum efficiency of GaAs/AlGaAs heterojunction photocathodes for different doping concentrations are deduced. From the calculated results the optimum doping concentration for p-type GaAs is between 3.0×10<sup>18</sup>cm<sup>-3 </sup>and 6.0×10<sup>18</sup>cm<sup>-3 </sup>and response threshold wavelength moves towards long-wave with doping concentration increases.