为了提高GaN阴极的紫外探测效率，提出了一种由体内到表面、掺杂浓度由高到低的变掺杂GaN阴极材料结构，采用超高真空（Cs,O）激活工艺进行了阴极制备，对均匀掺杂和变掺杂GaN光电阴极的光谱响应特性进行了测试与比较。与传统具有均匀掺杂结构的GaN阴极相比，这种变掺杂结构的阴极在反射工作模式下具有更高的量子效率(量子效率平均提高了30％)和更好的长波紫外响应特性（长波响应提高了43％）。通过比较变掺杂与均匀掺杂阴极在能带结构、光电子体内输运效率、光电子表面发射效率等特性上的差异，对变掺杂GaN光电阴极获得更高量子效率的机理进行了分析。

A varied-doping structure, in which the doping concentrations from bulk to surface of GaN emission layer are distributed from high to low, is proposed to improve the ultraviolet detection efficiency of GaN photocathode. The new material is prepared into negative electron affinity (NEA) photocathode using (Cs,O) activation technique in ultra-high vacuum system. The spectral response properties of uniform-doping photocathode and varied-doping photocathode are measured and compared, respectively. It is shown that the quantum efficiency varied-doping GaN photocathode has higher the average (increase by 30%) and better long-wave ultraviolet responsibility (increase by 43%) compared to the traditional uniform-doping photocathode in reflection operation mode. The differences in energy band structure, photoelectrons bulk transportation efficiency and photoelectrons surface escape efficiency between varied-doping and uniform-doping GaN photocathode are compared and the internal mechanism to explain why varied-doping GaN photocathode can obtain higher quantum efficiency is discussed.