Effect of surface preparation and thermal anneal on electrical characteristics of 4H-SiC Schottky barrier diodes

The effect of surface preparation and thermal anneal on electrical characteristics of 4H-SiC Schottky barrier diodes was investigated with the aim of finding a suitable fabrication process that would produce low reverse leakage current and low forward voltage drop. Schottky barrier diodes were fabricated on 4H-SiC surfaces using different surface preparation techniques. After fabrication, the diodes were subjected to anneal temperatures of up to 500 degrees C. It was found that surface preparation plays a crucial role in determining the electrical characteristics of as-deposited Schottky barrier diodes. The effect of thermal anneal was (a) a reduction in leakage current by several orders-of-magnitude, (b) an increase in barrier height, (c) an improvement in ideality factor. This study suggests that the choice of surface preparation technique and anneal temperature has significant effect on the performance of 4H-SiC Schottky barrier diodes.