Photo-generated parasitical capacitance model of GaN-based pin ultraviolet detector

This paper investigates the variation of depletion region width in the p and n layers and the total depletion region width of GaN-based pin ultraviolet (UV) detector with applied voltage. The variation of barrier capacitance with applied voltage is presented. The carrier number in the depletion region of detector generated by the light irradiation has relationships with width of the depletion region. Based on the definition of differential capacitance, the model including the photo-generated parasitical capacitance is presented. Finally, this paper systematically analyzes the influence of doping concentration on the photo-generated parasitical capacitance, response time and the cutoff frequency of GaN-based pin ultraviolet detector. By compared with the experiment results, the validity of the model is verified.