Silicon Carbide photo-conductive switch results using commercially available material

Abstract

Semi-insulating Silicon Carbide (SiC) is a promising material for bulk, linear photoconductive switches due to the extremely large dielectric strength (3MV/cm), and a large band gap that has options for extrinsic photon closure, large thermal conductivity, and robust mechanical strength. Previous work has shown that the low mobility of SiC (as compared to GaAs) can provide similar conduction resistances with similar optical energies as a GaAs switch due to the large dielectric strength. The reported work documents the recent switching results with commercially available Vanadium compensated SiC substrates and low inductance, mechanical contacts. Presently available semi-insulating SiC is manufactured to serve as a substrate for Light Emitting Diodes due to the high thermal conductivity and the high electrical resistivity. The most efficient method of producing semi-insulating SiC is to compensate the background impurities with Vanadium to produce V:SiC. However, V:SIC is not the best material for photo-conductive switches as demonstrated by this work. This document reports on recent experiments employing commercially available Vanadium compensated SiC photo-conductive switch in a 10 Ohm Blumlein system at voltages up to 10 kV. The band structure of V:SiC is described along with the experimental approach and measurements of switch resistance and the effective recombination time. The experimental results also indicate that specially grown SiC materials with lower densities of Vanadium compensation can increase the performance of this system.