Development of robust power Schottky barrier diodes in silicon carbide

The recent demand for increased efficiency in transportation, manufacturing equipment, and power generation and distribution has resulted in a strong research effort towards the development of solid-state devices capable of delivering large currents and withstanding high voltages without the need for bulky and expensive cooling systems. PiN diodes, used for rectification and transient suppression, have played important roles in all power electronic systems. The efficiency of these circuits can typically be improved by increasing the operating frequency. However, power lost during the switching transient of the diode also increases. Substituting Schottky barrier diodes (SBD's) for the standard PiN diodes in such circuits can significantly reduce overall power dissipation, since SBD's exhibit almost no reverse recovery transient. Silicon SBD's are limited to applications requiring a blocking voltage less than 100 V. Due to its large bandgap and high critical field, silicon carbide (SiC) SBD's have been demonstrated with breakdown voltages as high as 5 kV. A recent announcement by Infineon Technologies of plans to produce SiC Schottky barrier diodes confirms the common speculation that SiC Schottky barrier diodes will become the first commercially available SiC power electronic device. However, several important issues have as yet not been fully addressed: (1) Optimization of SBD structures, (2) Definition of the boundary between the application spaces of PiN and Schottky barrier diodes, (3) Demonstration of the superior switching performance expected of SiC SBD's, and (4) Investigation of the impact of non-micropipe crystallographic and other electrically active defects that are known to be present in high concentrations. The work described in this thesis addresses each of these issues as well as others, and thus contributes to the ongoing effort to develop robust, manufacturable SiC Schottky barrier diodes.