Variation of spectral response curves of GaAs photocathodes in activation chamber

Jijun Zou; Benkang Chang; Zhi Yang; Hui Wang; Pin Gao

doi:10.1117/12.688725

6 October 2006 Variation of spectral response curves of GaAs photocathodes in activation chamber

Jijun Zou, Benkang Chang, Zhi Yang, Hui Wang, Pin Gao

Proceedings Volume 6352, Optoelectronic Materials and Devices; 63523H (2006) https://doi.org/10.1117/12.688725
Event: Asia-Pacific Optical Communications, 2006, Gwangju, South Korea

Abstract

The spectral response curves of reflection-mode GaAs (100) photocathodes are measured in activation chamber by multi-information measurement system at RT, and by applying quantum efficiency formula, the variation of spectral response curves have been studied. Reflection-mode GaAs photocathodes materials are grown over GaAs wafer (100) by MBE with p-type beryllium doping, doping concentration is 1×10¹⁹ cm^-3 and the active layer thickness is 1.6μm. During the high-temperature activation process, the spectral response curves varied with activation time are measured. After the low-temperature activation, the photocathode is illuminated by a white light source, and the spectral response curves varied with illumination time are measured every other hour. Experimental results of both high-temperature and low-temperature activations show that the spectral response curve shape of photocathodes is a function of time. We use traditional quantum efficiency formulas of photocathodes, in which only the Γ photoemission is considered, to fit experimental spectral response curves, and find the theoretical curves are not in agreement with the experimental curves, the reason is other valley and hot-electron yields are necessary to be included in yields of reflection-mode photocathodes. Based on the two-minima diffusion model and the fit of escape probability, we modified the quantum efficiency formula of reflection-mode photocathodes, the modified formula can be used to explain the variation of yield curves of reflection-mode photocathodes very well.

Citation Download Citation

Jijun Zou, Benkang Chang, Zhi Yang, Hui Wang, and Pin Gao "Variation of spectral response curves of GaAs photocathodes in activation chamber", Proc. SPIE 6352, Optoelectronic Materials and Devices, 63523H (6 October 2006); https://doi.org/10.1117/12.688725

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