Investigation of linear, extrinsic silicon carbide photo-conductive switch materials

Summary form only given. Semi-insulating, compensated silicon carbide (SiC) has been employed in the linear, extrinsic photo-conductive mode as a high power switch. The extrinsic mode is employed for the purpose of increasing the optical absorption depth and thus the area through current can flow. Thus, the dopant densities determine the maximum carrier density and thus the current density is limited to a maximum value in the absence of impact ionization. The extremely large dielectric strength of SiC (3 MV/cm) enables electrode spacing to be reduced to the point that the required optical closure energy is very reasonable. The first design of a very compact, high voltage, high current package with minimal optical closure energy has been completed and is used in this work. This paper discusses the modeling of vanadium compensated SiC switches in concert with experiment measurements as a means determining the density and recombination cross sections of the dopants in the band gap. In this work, two types of compensation structures have been identified and will be presented. The two compensation structures have markedly different recombination times in the semiconductor codes. The material used in this work is a shallow donor, deep acceptor (SDDA). This paper presents the methods used to determine the density of dopants in the semi-insulating SiC material, the simulated switch waveforms and match the experimental waveforms. Finally the future of the modeling program is discussed along with the potential for controlling maximum switch current density and the switch recombination time with doping