High Power Lateral Silicon Carbide Photoconductive Semiconductor Switches and Investigation of Degradation Mechanisms

Abstract

Several generations of high power, lateral, linear mode, intrinsically triggered 4H-SiC photoconductive semiconductor switch designs and their performance are presented. These switches were fabricated from high purity semi-insulating 4H-SiC samples measuring 12.7 mm × 12.7 mm × 0.36 mm and were able to block dc electric fields up to 370 kV/cm with leakage currents less than 10 μA without failure. Switching voltages and currents up to 26 kV and 450 A were achieved with these devices and ON-state resistances of 2 were achieved with 1 mJ of 355 nm laser energy (7 ns FWHM). After fewer than 100 high power switching cycles, these devices exhibited cracks near the metal/SiC interface. Experimental and simulation results investigating the root cause of this failure mechanism are also presented. These results strongly suggest that a transient spike in the magnitude of the electric field at the metal/SiC interface during both switch closing and opening is the dominant cause of the observed cracking.

Influence of photon energy on conductivity of photoconductive semiconductor switches fabricated from semi-insulating GaP

“…They are, among others, SI GaP, SI 6H-SiC, SI 4H-SiC and SI GaN with a band gap width of 2.26, 3.0, 3.23 and 3.39 eV respectively at 300 K [6,8]. Research confirms better properties of PCSS made of SI 6H-SiC, SI 4H-SiC and SI GaN compared to switches made of SI GaAs [8,9]. PCSS switches can work in linear (conventional) and non-linear (avalanche) modes.…”

Performance Modeling of Silicon Carbide Photoconductive Switches for High-Power and High-Frequency Applications

“…Another work showed that SiC PCSS could block DC electric fields up to 705 kV/cm with leakage current < 0.1 mA, and switch voltages up to 30 kV into a 30 load [17]. DC blocking fields of 370 kV/cm with leakage currents less than 10 μA and switching currents of 450 A have been reported in 4H-SiC samples measuring 12.7 mm × 12.7 mm × 0.36 mm [19].…”

Opto-Electronics Review

“…Other mentioned SI materials have wider band gaps and, theoretically, should be able to block higher voltages and conduct higher current values than switches made of SI GaAs. Recent studies have experimentally shown that performance of PCSSs made of SI GaP, SI 6H-SiC, SI 4H-SiC, and SI GaN is much better compared to that made of SI GaAs [3,12,13].…”