Impact of bond rupture dynamics at polar and non-polar interfaces on time-dependent dielectric breakdown (TDDB) of GaN FinFETs

Abstract

This Letter presents a distinct crystallographic anisotropy in the time-dependent dielectric breakdown kinetics of GaN FinFETs, revealing a fundamental divergence in failure physics between polar and non-polar interfaces. By utilizing the three-dimensional Fin architecture to decouple the contributions of the c-plane (top) and m/r/a-plane (sidewall), two competing degradation mechanisms are identified: a field-assisted ionic dissociation dominated by GaGaN–NSiN bond cleavage on polar surfaces (∼1.1 eV), vs a thermally activated covalent bond rupture on non-polar sidewalls characterized by a significantly higher activation energy (∼1.9 eV). Deep-level transient spectroscopy corroborates this mechanistic transition, distinguishing shallow Ga-related electron traps (Ec−0.47 eV) on the polar face from deep vacancy-complex traps (Ec−1.032 eV and Ev+1.2 eV) specific to the non-polar interface. Consequently, GaN FinFETs exhibit an anomalous violation of the conventional area-scaling law, demonstrating superior intrinsic reliability despite their larger active gate area. These findings establish interface crystallography as a deterministic factor in the reliability physics of GaN FinFETs power electronic.