Differences in stability and repeatability between GaAs and GaAlAs photocathodes
Differences in stability and repeatability between GaAs and GaAlAs photocathodes
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DOI：
10.1016/j.optcom.2016.06.034
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发表时间：
2016-12
影响因子：
2.4
通讯作者：
Yuan Xu;Yijun Zhang;Cheng Feng;F. Shi;J. Zou;Xinlong Chen;Benkang Chang
中科院分区：
文献类型：
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作者：
Yuan Xu;Yijun Zhang;Cheng Feng;F. Shi;J. Zou;Xinlong Chen;Benkang Chang
对于真空光电探测器和光电注入器的应用，传统GaAs光电阴极的一个关键限制因素是有限的寿命，这取决于Cs-O激活层易受有害残余气体的影响。为了研制一种稳定性和重复性好的GaAs基光电阴极，在相同的制备条件下，对金属有机物气相外延生长的反射型指数掺杂GaAs和GaAlAs光电阴极进行了Cs/O激活和多次还原实验，测量了激活和还原后的量子效率和光电流衰减。实验结果表明，GaAs和GaAlAs光电阴极在阴极退化和重复性方面的光电发射特性不同。在不理想的真空系统中，经Cs/O激活后的GaAlAs光电阴极在高强度照明下的工作寿命比GaAs光电阴极长近一倍。GaAlAs光电阴极在多次退运后量子效率和工作寿命基本保持不变，而GaAs光电阴极随着退运次数的增加量子效率和工作寿命越来越低，这反映出GaAlAs光电阴极在稳定性和重复性方面优于GaAs光电阴极。
For the applications in vacuum photodetectors and photoinjectors, a crucial limiting factor for conventional GaAs photocathodes is the limited lifetime, depending on the Cs–O activation layer vulnerable to the harmful residual gases. In order to develop a type of GaAs-based photocathode with good stability and repeatability, Cs/O activation and multiple recesiation experiments under the same preparation condition were performed on reflection-mode exponential-doped GaAs and GaAlAs photocathodes grown by metalorganic vapor phase epitaxy, and quantum efficiency and photocurrent decay were measured after activation and recesiation. The experimental results show that the photoemission characteristics on cathode degradation and repeatability are different between GaAs and GaAlAs photocathodes. In an unsatisfactory vacuum system, the operational lifetime for GaAlAs photocathode is nearly twice longer than that for GaAs photocathode after Cs/O activation under a high intensity illumination. After multiple recesiations, the quantum efficiency and operational lifetime for GaAlAs photocathode remain nearly unchanged, while those for GaAs photocathode become lower and lower with the increase of recesiation cycles, which reflects the superiority in stability and repeatability for GaAlAs photocathode in contrast to GaAs photocathode operating in the poor vacuum environment.