Analysis of trap-assisted tunneling current at non-alloyed contacts formed on heavily ion-implanted n-type SiC

Numerical calculation of trap-assisted tunneling (TAT) current was performed and trap levels that dominantly contribute to the TAT current at non-alloyed contacts formed on phosphorus ion-implanted n-type SiC were speculated. Based on a careful discussion focusing on the impact of the energy level of traps on the tunneling probability and tunneling current, it was found that the energy level contributing to the TAT current was sensitively varied depending on the applied voltage. It turned out that a trap located at the half energy of the Schottky barrier height from the conduction band edge mainly contributed to the enhanced TAT current under a reverse bias, while shallower traps were responsible for the forward TAT current.