Iterative correction of the thickness for transmission-mode GaAs photocathode optical performance

Transmission-mode GaAs photocathode sample was grown by molecular beam epitaxy with the structure of Glass/Si3N4/GaAlAs/GaAs. The experimental reflectivity and transmittance curves were measured by the spectrophotometer. In order to fitting the actual thicknesses, the correction method is proposed which is multiple iterations of the thicknesses for reducing the composition error. The results show that the composition error of reflectivity and transmittance curves decreased from 15.2% to 4.9% in the range of 600-1100 nm by the correction of the multiple iterations. In addition, the thickness structure approximating to the actual value can be deduced by fitting the optical performance.