The Effect of Post Annealing Combined with UV/Ozone Exposure on the Electrical Characteristics of 4H-SiC Diodes

Abstract

This work presents the effect of post annealing combined with UV/ozone exposure on electrical characteristics of SiC Schottky diodes (SBDs) and junction barrier Schottky diodes. The effective barrier height of the diodes is extracted after UV/ozone exposure for 30 min and the forward current of the JBS and SBD increase by about 21% and 75%, respectively. The effective barrier height is more pronounced in the SBD structures than in the JBS, and the reverse current for JBS and SBD also increases by similar to 30% and similar to 80%, respectively, after post annealing with UV/ozone exposure. The Schottky area of the SBD diodes is larger than that of the JBS diodes, and the Schottky interface can be influenced by the UV exposure, more than the p+n junction, and the simulated JBS structure can reduce the current at the Schottky contact portion. The decrease in the effective Schottky barrier height is considered to be due to the structural defects reaching the semiconductor surface, leading to a localized barrier that lowers and increases the leakage currents. In addition, annealing with ozone may also remove a metal surface and metal/semiconductor interface layer that contains hydrocarbon contamination.