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研究了透射式GaN光电阴极在正面光照和背面光照两种工作模式下的光电发射特性差异及影响因素,并推导了这两种工作模式下的量子效率理论公式,利用所推导的公式对实验获得的GaN光电阴极量子效率曲线进行了分析。研究结果表明,两种工作模式下光电子的表面逸出几率与光子能量具有不同的依赖关系,背面光照下,光电子将以一个一致的表面逸出几率从表面发射出去,并且短波响应会受到缓冲层及界面特性的影响,总体光电发射效率依赖于阴极表面势垒所决定的平均电子逸出几率。利用所推导的量子效率公式对实验曲线进行拟合,可实现多个阴极参量的评估,这为透射式GaN阴极材料与制备工艺水平的分析提供了重要依据。
The differences and influencing factors of photoelectric emission characteristics of transmissive GaN photocathode in frontal illumination mode and backside illumination mode were studied. The theoretical formulas of quantum efficiency in these two modes of operation were deduced. The experimental results were obtained by using the derived formulas GaN quantum cathode quantum efficiency curve was analyzed. The results show that there are different dependences of photoemission rate on photon energy under the two operating modes. Under the backside illumination, the photoelectrons will emit from the surface with a consistent probability of surface escaping, and the shortwave response will be affected by the buffer layer And interface characteristics, the overall optoelectronic emission efficiency depends on the average electron escape probability determined by the cathodic surface barrier. Using the derived quantum efficiency formula to fit the experiment curve, it is possible to evaluate several cathode parameters, which provides an important basis for the analysis of transmissive GaN cathode material and preparation technology.