In-situ multi-information measurement system for preparing gallium nitride photocathode
In-situ multi-information measurement system for preparing gallium nitride photocathode
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DOI：
10.1088/1674-1056/21/3/030601
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发表时间：
2012-03
影响因子：
1.7
通讯作者：
Xiao-qian Fu;Benkang Chang;Y. Qian;Junju Zhang
中科院分区：
文献类型：
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作者：
Xiao-qian Fu;Benkang Chang;Y. Qian;Junju Zhang
介绍了国内第一套氮化镓光电阴极多信息原位测量系统。该系统可以在高真空环境下成功地实现GaN的热清洗和活化，并制备出负电子亲和势（NEA）的GaN光电阴极。在制备过程中可以获得包括热清洗温度、真空度、光电流、铯源电流、氧源电流的信息，以及关于光谱响应的最重要的信息，或者等效地，量子效率（QE）。用该系统制备的GaN光电阴极表明，在真空中的最佳加热温度为700 ℃左右。C.我们还开发了一种方法，快速评估原子级清洁表面的真空度-波长曲线，以防止可能的二次污染时，原子级清洁表面的X射线光电子能谱测试。当铯源与氧源的电流比为1.025时，光电流迅速增强。GaN光电阴极的光谱响应在240 ~ 365 nm波长范围内比较平坦，在365 nm处出现了一个突变，说明利用多信息测量系统可以成功制备NEA GaN光电阴极。
We introduce the first domestic in-situ multi-information measurement system for a gallium nitride (GaN) photocathode. This system can successfully fulfill heat cleaning and activation for GaN in an ultrahigh vacuum environment and produce a GaN photocathode with a negative electron affinity (NEA) status. Information including the heat cleaning temperature, vacuum degree, photocurrent, electric current of cesium source, oxygen source, and the most important information about the spectral response, or equivalently, the quantum efficiency (QE) can be obtained during preparation. The preparation of a GaN photocathode with this system indicates that the optimal heating temperature in a vacuum is about 700 ?C. We also develop a method of quickly evaluating the atomically clean surface with the vacuum degree versus wavelength curve to prevent possible secondary contamination when the atomic level cleaning surface is tested with X-ray photoelectron spectroscopy. The photocurrent shows a quick enhancement when the current ratio between the cesium source and oxygen source is 1.025. The spectral response of the GaN photocathode is flat in a wavelength range from 240 nm to 365 nm, and an abrupt decline is observed at 365 nm, which demonstrates that with the in-situ multi-information measurement system the NEA GaN photocathode can be successfully prepared.