Spectral response of InGaAs photocathodes with different emission layers

Three InGaAs photocathode samples with different emission layers were prepared using metal organic chemical vapor deposition and activated by Cs, O. The spectral responsivity curves of the three samples were obtained, and the quantum efficiency formula of the InGaAs photocathodes with multi-sublayers was derived. Results show that the InGaAs samples with thick emission layers have higher spectral responsivity, and the wavelength of the threshold decreases with the decrease of the In component. According to the performance parameters obtained by fitting the quantum efficiency of the experiment, it was found that a higher In component corresponds to a lower electron escape probability. Therefore, it is difficult to prepare InGaAs photocathodes with a high electron escape probability and a long threshold wavelength at the same time. By adding mini transition layers between the sublayers, the interface recombination velocity decreases, and the critical thickness of the sublayers increases. In conclusion, mini transition layers are very important for the preparation of InGaAs photocathodes capable of high performance.