Injection modulation of p⁺–n emitter junction in 4H–SiC light triggered thyristor by double-deck thin n-base

To overcome hole-injection limitation of p⁺-n emitter junction in 4H-SiC light triggered thyristor, a novel high-voltage 4H-SiC light triggered thyristor with double-deck thin n-base structure is proposed and demonstrated by two-dimensional numerical simulations. In this new structure, the conventional thin n-base is split to double-deck. The hole-injection of p⁺-n emitter junction is modulated by modulating the doping concentration and thickness of upper-deck thin n-base. With double-deck thin n-base, the current gain coefficient of the top pnp transistor in 4H-SiC light triggered thyristor is enhanced. As a result, the triggering light intensity and the turn-on delay time of 4H-SiC light triggered thyristor are both reduced. The simulation results show that the proposed 10-kV 4H-SiC light triggered thyristor is able to be triggered on by 500-mW/cm² ultraviolet light pulse. Meanwhile, the turn-on delay time of the proposed thyristor is reduced to 337 ns.