Silicon ultrafast recovery diode with leakage current reduced via the combined lifetime process of gold diffusion and electron-beam irradiation

Abstract

We investigated the reduction in the reverse-biased leakage current of Si ultrafast recovery diodes via a combined lifetime process involving Au diffusion and bulk electron-beam irradiation (EI). The leakage current of the combined-processed diode was significantly reduced to less than one-third of that of the diode processed solely with Au diffusion, maintaining a similar switching time of 32 ns. This reduction was not achievable with the sole use of EI. Deep-level transient spectroscopy revealed that the reduction in the leakage current was due to the coexistence of the deep trap level of Au (E c-0.51 eV) and the shallow trap level of the defects (E c-0.39 eV) generated via EI as lifetime killers. By combining the deep and shallow trap levels, the lifetime of the carriers generated in the depletion layer of the reverse-biased p-n junction becomes long and consequently, the leakage current is reduced. By maintaining the trap density ratio of defects to diffused Au above 0.28, the leakage current was reduced to less than one-third of that in the solely Au-diffused diode, while maintaining a similar switching time.