Open AccessTheoretical calculation of quantum yield for exponential-doping GaAs photocathodes
Author(s) -
JiJun Zou,
Benkang Chang,
Yan Zhi
Publication year - 2007
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.56.2992
Subject(s) - electric field , doping , photoelectric effect , quantum yield , photocathode , materials science , cathode , quantum efficiency , exponential function , electron , atomic physics , exponential decay , physics , optoelectronics , optics , chemistry , quantum mechanics , mathematical analysis , mathematics , fluorescence
Exponential-doping photocathodes, in which from the GaAs bulk to the surface the doping concentration is distributed exponentially from high to low, can form a stable built-in electric field in the active layer, and the electric field facilitates the excited photoelectron emission. The quantum yield formulas of both reflection-mode and transmission-mode of exponential-doped photocathodes have been solved from the 1-diemnsion continuity equations, in which the build-in electric field is considered. According to these formulas, we calculate the theoretical quantum yield of the exponential-doped photocathodes. The calculated results show that the exponential-doping structure can increase the quantum yield of photocathodes significantly. To compare with the uniformly-doped photocathodes, the integral sensitivity of the reflection-mode exponential-doped photocathodes increases by nearly 20%, and for transmission-mode photocathodes the increase is more than 30%. The performance improvements of exponential-doping photocathodes are mainly attributed to the built-in electric field, the photoelectrons driven by the field move towards the cathode surface by way of diffusion and drift, accordingly, decrease the influence of the back-interface recombination velocity on photoemission and increase the equivalent electron diffusion length of cathodes.