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Improvement of photoemission performance of a gradient-doping transmission-mode GaAs photocathode 下载免费PDF全文
Two types of transmission-mode GaAs photocathodes grown by molecular beam epitaxy are compared in terms of activation process and spectral response, one has a gradient-doping structure and the other has a uniform-doping structure. The experimental results show that the gradient-doping photocathode can obtain a higher photoemission capability than the uniform-doping one. As a result of the downward graded band-bending structure, the cathode performance parameters, such as the electron average diffusion length and the surface electron escape probability obtained by fitting quantum yield curves, are greater for the gradient-doping photocathode. The electron diffusion length is within a range of from 2.0 to 5.4 μm for doping concentration varying from 1019 to 1018 cm-3 and the electron average diffusion length of the gradient-doping photocathode achieves 3.2 μm. 相似文献
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利用GaN光电阴极多信息量测试评估系统,对反射式梯度掺杂和均匀掺杂GaN光电阴极样品进行了激活及衰减后的量子效率测试,并测试衰减速率。在同样的衰减时间内,和均匀掺杂样品相比,梯度掺杂样品的衰减比例较小,衰减速率较慢,其原因在于梯度掺杂结构可在其发射层内部产生系列内建电场,致使其能带连续向下弯曲,导致其表面真空能级比均匀掺杂样品下降得更低,发射层表面形成的负电子亲和势更明显,造成发射层内的光生电子更易逸出,阴极量子效率的衰减变慢,从而使其稳定性强于均匀掺杂结构。 相似文献
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