Proton irradiation technology was used for the improvement of power diode switching characteristics. Proton irradiation was carried out at the energies of 2.32 MeV, 2.55 MeV, 2.97 MeV so that the projection range of irradiated proton would be at the metallurgical junction, depletion region and neutral region of pn diode, respectively. Dose conditions were varied into three conditions of 1${ imes}$10$^{11}$ cm$^{-2}$ , 1${ imes}$10$^{12}$ cm$^{-2}$ , 1${ imes}$10$^{13}$ cm$^{-2}$ at each condition of energies. Characterization of the device was performed by I-V(current-voltage), C-V(capacitance-voltage) and trr(reverse recovery time) measurement. At the optimum condition of irradiation, the reverse recovery time of device has been reduced about 1/5 compared to that of original un-irradiated device.