Cs、O激活方式对GaAs光电阴极的影响

利用自行研制的GaAs光电阴极多信息量测试与评估系统,比较了不同Cs、O激活方式下GaAs光电阴极的激活过程、光谱响应特性以及稳定性的差异,发现与传统的Cs源、O源交替断续激活方式相比,Cs源持续,O源断续的激活方式能获得灵敏度更高和稳定性更好的阴极,且阴极的长波响应能力也得到提高.本文利用双偶极层模型对实验现象进行了解释,认为Cs在整个激活过程中处于轻微过量状态有利于获得高性能的GaAs光电阴极,Cs量控制是决定GaAs光电阴极激活工艺好坏的主要因素.

Influence of Cs,O Activation Modes on GaAs Photocathode

A novel computer-controlled multi-function system has been developed to characterize GaAs photocathode. Variations in the physical quantities of the photocathode activated in different Cs, O activation modes, such as its spectral response and stability, were studied with this lab-built apparatus. In contrast to the conventional activation mode,where Cs and O sources are turned on and off alternatively,the new activation mode only turns on and off of the O source altematively but keeps the Cs source on continuously. We found that the. photocathode activated in the new mode has higher sensitivity, better stability, and stronger long-wave response than that of the conventionally activated one. Possible mechanism was tentatively diseussed with a double dipole model. Interesting finding is that a slight excess of Cs improves performance of the photocathode. We suggest that careful control of Cs quantity plays a key role in GaAs photocathode activation.