Failure mechanisms of vertical β -Ga2O3 photoconductive switch with different crystal orientations under 355 nm irradiation

As a promising material for fabricating high-performance photoconductive semiconductor switches (PCSSs), β-Ga2O3 suffers from restricted performance improvement due to premature breakdown failure. In this study, we systematically investigated the output characteristics and failure mechanisms of vertical structure β-Ga2O3 PCSSs fabricated on the (100), (010), and (001) crystal planes under 355 nm laser irradiation. The results show that the maximum voltage-withstanding capabilities of the devices on the three crystal planes reach 5, 6, and 7 kV, corresponding to output powers of 250, 192, and 203 kW, respectively. Characterizations via x-ray diffraction and focused ion beam-transmission electron microscopy confirm that the device failure does not originate from typical electrical breakdown but is dominated by cleavage fracture along the inherent cleavage planes of the crystal: the (100)-plane device cleaves along the (001) plane, while the (010)- and (001)-plane devices cleave along the (100) plane. Furthermore, the stress accumulation inside the device under high power is the core inducement triggering cleavage failure. This study provides an important theoretical basis for the performance optimization of vertical β-Ga2O3 PCSSs.