Wide Bandgap Extrinsic Photoconductive Switches.

摘要

Semi-insulating Silicon Carbide and Gallium Nitride are attractive materials for compact, high voltage, photoconducting semiconductor switches (PCSS) due to their large bandgap (3.0 3.4 eV), high critical electric field strength (3.0 3.5 MV/cm) and high electron saturation velocity (2.0 2.5x107 cm/s). Carriers must be optically generated throughout the volume of the photoswitch to realize the benefits of the high bulk electric field strength of the 6H-SiC (3 MV/cm) and GaN (3.5 MV/Cm) materials. This is accomplished by optically exciting deep extrinsic levels in Vanadium compensated semi- insulating 6H-SiC and Iron compensated semi-insulating GaN. Photoconducting switches with opposing electrodes were fabricated on aplane, 6H-SiC substrates and c-plane, GaN substrates. This work reports the initial fabrication and test of extrinsic GaN switches excited at a wavelength of 532 nm, and a review of the first phase of switch tests of a-plane, 6H-SiC PCSS.