Fabrication, electrical characterization, and annealing of aluminum, copper, and gold/4H-silicon carbide Schottky diodes

Schottky diodes were fabricated on n-type 4H-SiC with Nickel ohmic contacts and Aluminum, Copper, and Gold Schottky contacts. An improved and revised fabrication process was developed in the course of this research project. The Schottky diodes were electrically characterized using I-V and C-V measurements to extract electrical parameters which include Schottky barrier height, ideality factor, the diode series resistance, and substrate doping density. Al/4H-SiC and Au/4H-SiC were annealed at 600°C and 500°C respectively to improve the Schottky parameters. Schottky barrier height was raised and the ideality factor was reduced in both cases. Significant improvement was observed in the ideality factor of Al/4H-SiC diodes. XPS was performed on Al/4H-SiC samples to investigate the effects of annealing at the Aluminum-SiC interface. Analysis of the XPS results showed traces of Aluminum-Silicon bonding at the interface. The change in the Schottky parameters is attributed to this phenomenon. The electrical characterization of Au/4H-SiC showed that the devices had a very low ideality factor of 1.1 and represented some of the best results obtained in our research lab. The thesis establishes the effect of annealing on Schottky diodes and presents some of the very few surface analysis results performed on Al/4H-SiC.