Vertical SiC Photoconductive Switch With Axial Optical Internal Reflection Trap

Abstract

The SiC vertical photoconductive switch with an axial optical internal reflection trap to improve the ON-state performance is presented. The extrinsic light absorption of vanadium (V)-doped SiC photoconductive switch is low. As such an axial optical reflection trap is used to increase the optical path and total optical absorption. The trap consists of a convex lens, a silver mirror electrode with a hole, and a transparent electrode to create a quasi-total internal reflection structure. Simulation and experimental evaluation reveal that both the device’s light absorption and output current have been improved significantly. Compared with regular axial illumination without the reflective trapping arrangement, the structure fabricated on a V-doped 4H-SiC device demonstrates a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.5\times $ </tex-math></inline-formula> improvement in photoelectric conversion responsivity.