Electric field-directed anisotropic failure of β -Ga2O3

As one of the critical materials for ultra-high-voltage power devices, β-gallium oxide (β-Ga2O3) faces significant reliability challenges. Under the coupled effects of repeated electrical stress and high-temperature thermal fields, the stability of this material directly determines the reliability of power devices under extreme service conditions. However, to date, atomic-scale real-time observations and mechanistic explanations of the failure process of this material under coupled electro-thermal fields remain lacking. In this study, using in situ transmission electron microscopy (in situ TEM) under coupled thermal-electrical field (500 °C and 1 V bias), we directly observed the anisotropic failure of β-Ga2O3 along low-index planes such as (200). Controlled decoupling experiments confirm that the electric field serves as the key driver in initiating and guiding this anisotropic melting process. Moreover, electro-thermal stress markedly accelerates the failure, increasing the melting rate from 1.145 to 4.937 nm2/s. By combining experimental observations with theoretical analysis, we establish a complete physical chain in which the synergistic effect of the electric field and the material's intrinsic anisotropy drives external field-induced defect generation and migration, ultimately leading to the anisotropic failure of β-Ga2O3. This work not only provides direct evidence for understanding the failure behavior of β-Ga2O3 under extreme operating conditions, but also offers crucial design guidance for developing highly reliable high-voltage power devices.