Effect of post-implantation anneal on the electrical characteristics of Ni 4H-SiC Schottky barrier diodes terminated using self-aligned argon ion implantation

The effects of post-implantation annealing on the electrical characteristics of Ni 4H-SiC Schottky barrier diodes terminated using self-aligned Ar+ ion implantation have been investigated. Results show that the Ar+ edge termination may be modelled as a shunt linear resistive path at low to moderate reverse bias levels and at low forward bias levels. Low temperature (400–700°C) annealing is shown to increase the equivalent resistance of the edge termination by two orders of magnitude without significant effect on the breakdown voltage. Annealing temperatures above 600°C are, however, shown to degrade the on-state performance. A breakdown voltage of 1530 V was achieved on the implanted and annealed samples, representing 90% of the theoretical parallel plane breakdown voltage. Temperature dependent measurements, made over the temperature range 25–400°C show that the equivalent resistance of the edge termination is thermally activated with an exponential temperature coefficient of −0.02 K−1. Behaviour at moderate forward bias levels is typical of thermionic emission whilst operation at high forward bias is dominated by a linear series resistance which shows a quadratic temperature dependence, increasing by a factor of 6 over the range 25–400°C.