Carrier dynamics in a vanadium-doped 4H-SiC photoconductive semiconductor switch at different photon injection rates

The transient photoconductivity process of silicon carbide photoconductive semiconductor (SiC PCSS) mainly depends on the optical excitation to generate electron-hole plasma in the semiconductor substrate. Among them, photon injection rate has a significant impact on the generation and transport of photo-generated carriers within PCSS as an important parameter of the laser pulse. The effect of photon injection rate on the output characteristics of vanadium-doped (V-doped) 4H-SiC PCSS under 532 nm non-intrinsic laser triggering is experimentally studied in this article. Experiments show that the turn-on time and output amplitude of PCSS can be effectively regulated by changing the photon injection rate at the same energy. A physical model of SiC PCSS is constructed based on the finite element method, and the effects of different photon injection rates on the distribution of transient electric field and current density are investigated. Simulation shows that a high-current density plasma channel within PCSS is rapidly formed based on two-photon absorption and electric field enhancement at a higher photon injection rate.