Effect of post-implantation anneal on the electrical characteristics of Ni4H-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 degreesC) 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 degreesC 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 degreesC 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 degreesC. (C) 2000 Elsevier Science Ltd. All rights reserved.