Formation of cesium peroxide and cesium superoxide on InP photocathode activated by cesium and oxygen
Formation of cesium peroxide and cesium superoxide on InP photocathode activated by cesium and oxygen
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DOI：
10.1063/1.2786882
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发表时间：
2007-10
影响因子：
3.2
通讯作者：
Yun Sun;Zhi Liu;P. Pianetta;D. Lee
中科院分区：
文献类型：
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作者：
Yun Sun;Zhi Liu;P. Pianetta;D. Lee
用铯和氧活化p型III-V族半导体已被广泛用于制备负电子亲和势（NEA）光电阴极。然而，活化后表面上的化学物质的性质还没有很好地理解。在这项研究中，InP NEA光电阴极激活铯和氧使用同步辐射光电子能谱，也称为光电发射研究。基于O 1 s芯能级以及价带谱，确定了InP表面的Cs过氧化物和Cs超氧化物。活化后观察到Cs过氧化物向Cs超氧化物的转化，这可能是光阴极量子产额衰减的主要原因。随着时间的推移，还观察到InP衬底的氧化，增加了量子产率的衰减。
Activation of p-type III-V semiconductors with cesium and oxygen has been widely used to prepare negative electron affinity (NEA) photocathodes. However, the nature of the chemical species on the surface after the activation is not well understood. In this study, InP NEA photocathodes activated with cesium and oxygen are studied using synchrotron radiation photoelectron spectroscopy, also called photoemission. Based on the O 1s core level as well as the valence band spectra, Cs peroxide and Cs superoxide are identified on the InP surface. Transformation from Cs peroxide to Cs superoxide is observed after the activation, and is probably the major reason for the decay of the quantum yield of the photocathode. The oxidation of the InP substrate is also observed with elapse of time, adding to the decay of the quantum yield.