Theoretical research on optical properties and quantum efficiency of Ga1−xAlxN photocathodes

In order to design the optimal component structure of transmission-mode (t-mode) Ga1−xAlxN photocathode, the optical properties and quantum efficiency of Ga1−xAlxN photocathodes are simulated. Based on thin film principle, optical model of t-mode Ga1−xAlxN photocathodes is built. And the quantum efficiency formula is put forward. Results show that Ga1−xAlxN photocathodes can satisfy the need of detectors with “solar blind” property when the Al component is bigger than 0.375. There is an optimal thickness of Ga1−xAlxN layer to get highest quantum efficiency, and the optimal thickness is 0.3 μm. There is close relation between absorptivity and quantum efficiency, which is in good agreement with the “three-step” model. This work gives a reference for the experimental research on the Ga1−xAlxN photocathodes.