Study of a Si-based light initiated multi-gate semiconductor switch for high temperatures.

Light initiated multi-gate semiconductor switch (LIMS) is a kind of power electronic device which has many differences from traditional thyristor triggered by electric pulse. LIMS is triggered by laser, the turn-on time is smaller, and the anti-electromagnetic interferences is strong. The opening mode of LIMS is obviously different to traditional thyristor. After the laser into the gate area, a large number of electrons and holes will appear in P-base region, holes gather in the area of P-base in PN junction J2, and electrons gather in N-drift region around the PN junction J2. PN junction J2 will open first, then PN junction J3 opens. The delay time of the NPN and PNP thyristors is close to zero when the laser pulse is narrow and the peak power is high, so the turn-on velocity is fast. To optimize the characteristics of the LIMS at high temperatures, we propose a new structure of the LIMS with the optimization of the n+ layer, circular light gate, and the new-style edge termination. The diameter of the LIMS is 23 mm. The experiment results show that the leakage current of the proposed LIMS has been decreased from more than 1 mA to 500 µA at 125 °C, the output current of the LIMS is 10.2 kA with a voltage of 4 kV at 85 °C, and the output current of the LIMS is 12.1 kA with a voltage of 4 kV at - 55 °C. Additionally, di/dt is larger than 30 kA/µs.

Dependence of conduction characteristics on compensation type and lattice structure of SiC photoconductive semiconductor switches.

Semi-insulating (SI) SiC photoconductive semiconductor switches were prepared using two compensation mechanisms: namely vanadium dopants compensation (4H- and 6H-SiC) and deep level defect compensation (4H-SiC). The bias voltage and current of the high-purity (HP) SI 4H-SiC photoconductive semiconductor switch (PCSS) with a channel length of 1 mm reached 24 kV and 364 A, respectively, and the minimum on-state resistance of approximately 1 Ω was triggered by laser illumination at a wavelength of 355 nm. The experimental results show that, in this case, the on-state characteristics of HP 4H-SiC PCSS are superior to those of the vanadium-doped(VD) 4H and 6H-SiC PCSS devices. HP 4H-SiC PCSS shows remarkable waveform consistency. Unlike for VD 4H and 6H-SiC PCSS, the current waveform of HP 4H-SiC PCSS exhibits a tailing phenomenon due to its longer carrier lifetime.