It was thoroughly investigated for the absorption of broadband incident light， photogenerated carrier generation， and the physical process of photogenerated carrier transport and compounding， and a number of semiconductor layers with different energy bandgaps were proposed to set up in the pin semiconductor junction in this paper. Through different energy bandgap semiconductor layers， the absorption region of incident light of different wavelengths could be adjusted， and the bias voltage could be used to control the transport and compounding of photogenerated carriers in different regions. Then the spectral response characteristics of the detector was improved. According to the results of the study， the Pearson correlation coefficient of the detector spectral response curve decreased from 0.99 to 0.68 at different bias voltages when four layers of intrinsic layers with bandgap gradient distributions were set up， providing effective broad-spectrum probing data for the subsequent spectral reconstruction of the detector.