Silicon carbide optoelectronic switches

We will discuss here our efforts to fabricate and test new SiC opto-electronic high voltage switches. We report the ultrafast switching of novel silicon carbide devices using an optical trigger. The switching properties of both commercial SiC pn diodes and in-house fabricated SiC thyristors were investigated. Subnanosecond risetime was observed with both devices. A comparison of SiC pn diode and thyristor switching shows that the thyristor has the highest switching speed and efficiency, and triggers with the least optical energy. We report the first optical triggering of a silicon carbide thyristor into the latched-on state. This switching is characteristic of electrically triggered thyristors, however the optical triggering produced a significantly faster risetime, 370 picosecond, than is possible with electronic triggering. The thyristor switched 100 volts bias with 96% efficiency, corresponding to a device on-state of 4 volts at an average current density of 750 A/cm². The singular advantages of optical triggering, isolation from the trigger source, synchronized triggering of stacked devices, and switching speed, are highly desirable for high voltage, high power operation of conventional power devices. These results provide enabling technology for high-repetition rate, high-voltage impulse generators and expedite the development of high-power electrically triggered silicon carbide devices.