中国光学, 2018, 11 (4): 677, 网络出版: 2018-07-30
梯度掺杂结构GaN光电阴极的稳定性
Stability of gradient-doping GaN photocathode
摘要
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。
Abstract
The GaN photocathode multi-information measurement and evaluation system is used to test the quantum efficiency of the reflective gradient-doped and uniformly doped GaN photocathode samples after activation and attenuation, and the attenuation rate test is performed. The gradient-doped sample has a smaller attenuation ratio and a slower decay rate than the uniform-doped sample within the same decay time because the gradient-doped structure can generate a series of built-in electric fields inside the emissive layer. As a result, the energy band can be continuously bent downwards, resulting in a lower surface vacuum level than that of the uniformly doped sample, and the negative electron affinity formed on the surface of the emission layer is more pronounced, resulting in easier escape of photogenerated electrons in the emission layer. The decay of the cathode quantum efficiency becomes slower, making it more stable than uniform-doped structures.
李飙, 任艺, 常本康. 梯度掺杂结构GaN光电阴极的稳定性[J]. 中国光学, 2018, 11(4): 677. LI Biao, REN Yi, CHANG Ben-kang. Stability of gradient-doping GaN photocathode[J]. Chinese Optics, 2018, 11(4): 677.