Modeling of metal/insulator/GaN ultraviolet photodetector by finite element method

A metal/insulator/GaN ultraviolet photodetector has been studied by computer simulations using finite element method. The equations of drift-diffusion model have been solved numerically in the illuminated structure taking into account electronic states at the insulator/GaN interface with a continuous U-shaped energy distribution in the GaN bandgap. The capacitance of the structure has been calculated versus the light excitation intensity and the gate voltage. The influence of the interface states on the photodetector characteristics has been discussed.