4H-SiC photoconductive switching devices for use in high-power applications

Abstract

Silicon carbide is a wide-band-gap semiconductor suitable for high-power high-voltage devices and it has excellent properties for use in photoconductive semiconductor switches (PCSSs). PCSS were fabricated as planar structures on high-resistivity 4H-SiC and tested at dc bias voltages up to 1000 V. The typical maximum photocurrent of the device at 1000 V was about 49.4 A. The average on-state resistance and the ratio of on-state to off-state currents were about 20 Omega and 3x10(11), respectively. Photoconductivity pulse widths for all applied voltages were 8-10 ns. These excellent results are due in part to the removal of the surface damage by high-temperature H-2 etching and surface preparation. Atomic force microscopy images revealed that very good surface morphology, atomic layer flatness, and large step width were achieved.