title: Effects of graded band-gap structures on spectral response of AlGaAs/GaAs photocathodes.
abstract: The effects of AlGaAs/GaAs layer thickness and Al composition range on the spectral response and integral sensitivities of reflection-mode graded band-gap AlGaAs/GaAs photocathodes have been investigated and simulated. The experimental results demonstrate that the spectral response over the wavelength region of interest for graded band-gap photocathodes is greater than that for uniform band-gap cathodes, and the increase in long-wavelength response is more pronounced. These results can be attributed to the built-in electric field in the graded band-gap AlGaAs layer. We established a spectral response model of graded band-gap photocathodes based on the numerical solution of coupled Poisson and continuity equations. According to the model, we calculated the theoretical spectral response and sensitivities of graded band-gap cathodes, and found the optimum Al(x)Ga(1-x)As layer thicknesses are 6, 10, 16, and 22 μm for the reflection-mode cathodes with linearly graded Al composition x ranges of 0 to 0.1, 0.2, 0.3, and 0.4, respectively.
authors.forename: Jijun
authors.initials: J
authors.lastname: Zou
authors.forename: Yijun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Deng
authors.forename: Xincun
authors.initials: X
authors.lastname: Peng
authors.forename: Shaotao
authors.initials: S
authors.lastname: Jiang
authors.forename: Benkang
authors.initials: B
authors.lastname: Chang