Impact of emission layer of GaAs photocathode on certain wavelength absorptivity

In order to analyze the requirements of different wavelength response to the GaAs photocathode structure, the relationship was simulated and verified by experiments between the absorptivity at the single-wavelength response of 400~1000 nm and the GaAs emission layer. The results show that the GaAs layer thickness is required greater than 0.5 μm under 600 nm wavelength response in order to get the absorptivity of 90% above, the thickness is required greater than 0.8 μm for 700 nm wavelength response, and it is required greater than 1.5 μm under 800 nm wavelength response. The value of GaAs photocathode absorptivity has little influence with the thickness of GaAs layer in the wavelength section of 400~500 nm, which is only related to the wavelength. The longer the wavelength, the higher the absorptivity. The absorptivity in the range of 550~900 nm decreases with the increase of wavelength, and the absorptivity increases with the increase of GaAs layer thickness. The experimental results confirm the simulation results.