Breakdown-induced directional cracking in kilovolt-class β-Ga₂O₃ (001) vertical trench Schottky barrier diodes

Breakdown in kilovolt-class β-Ga₂O₃ (001) vertical Schottky barrier diodes is often observed with material cracking and local delamination along the [010] direction, which coincides with the orientation of plate-like nanopipe defects in Ga₂O₃ crystals. This study aims to determine whether these defects are the main cause of device breakdown/failure. Laser confocal and scanning electron microscopy techniques were employed to image original defects in the material and the locations of damage induced upon electrical breakdown at 3.8 kV in the devices. Our analysis shows no clear correlation between the defect locations and the breakdown sites. Failure/cracking along the [010] direction appears to be a consequence of thermo-mechanical failure along the (100) cleavage planes due to arcing-induced damage and the instantaneous heat generated during breakdown, rather than the original plate-like nanopipes, at least for the majority of cases observed.