Dielectric Breakdown Mechanisms in High‑κ\nAntimony Trioxide (Sb<sub>2</sub>O<sub>3</sub>)

High-κ gate\ndielectrics compatible with two-dimensional (2D)\nmaterials are crucial for advanced electronics, and Sb<sub>2</sub>O<sub>3</sub> (antimony trioxide) shows significant potential. Here,\nwe show that the soft breakdown induces oxygen vacancies and migration\nof copper into Sb<sub>2</sub>O<sub>3</sub>. Hard breakdown, driven\nby joule heating, gives rise to a substantial temperature increase,\nleading to morphological transformations and oxygen redistribution.\nIn\nsitu transmission electron microscopy (in situ TEM) measurements correlated\nwith device performance show the formation of nanoconducting filaments\ndue to the increased concentration of oxygen vacancies and copper\nmigration in connection with the soft breakdown. The hard breakdown\nis associated with the formation of antimony-enriched nanocrystals.\nThese findings offer critical insights into the suitability of Sb<sub>2</sub>O<sub>3</sub> as a high-κ gate dielectric.