Stability of gradient-doping GaN photocathode

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.