Static and dynamic characteristics of 4H-SiC p/sup +/n and 6H-SiC Schottky diodes

Abstract

Wide-bandgap (WBG) semiconductor power devices have good potential for operating at higher temperatures compared to Si-based electronics. Silicon carbide (SiC) currently represents a good WBG candidate for use in developing power MOSFETs and Schottky diodes used in power conditioning and control electronics that are required for the next generation More Electric Aircraft (MEA). To that end, SiC Schottky and p/sup +/n diodes were examined; the SiC Schottky diode is important for use in power switching applications due to its fast reverse recovery times. Faster switching times lead to lower power losses, which in turn dissipates less heat. The SiC p/sup +/n diode is the basic voltage blocking structure in the SiC MOSFET. Forward and reverse bias static and dynamic characteristics were obtained for 4H-SiC p/sup +/n diodes in vacuum at temperatures in the range of 298 K to 698 K. Static characteristics revealed a decrease in forward threshold voltage from 2 volts at /spl sim/298 K to 1.25 volts at 698 K; similar behavior was also observed for 6H-SiC Schottky diodes as a function of temperature. Dynamic measurements yielded low frequency (100 KHz) rectifier efficiencies of /spl sim/38% for the SiC Schottky diodes over the temperature range /spl sim/298 K -273 K, compared to /spl sim/34% for the SiC p/sup +/n diodes. Data was also obtained for diode power dissipation versus duty cycle and temperature. It is believed that an error exists in the authors' experimental setup for power dissipation.