Exploration of Physicochemical Mechanism for Negative Bias Temperature Instability in GaN‐HEMTs by Extracting Activation Energy of Dislocations

The reliability issues caused by negative bias temperature instability (NBTI) impede the rapid expansion of gallium nitride (GaN)-based high electron mobility transistors (HEMT). Clarifying the physicochemical reactions during the degradation process induced by NBTI is of paramount importance for tracing the origin of NBTI, so as to circumvent the intrinsic reliability problem. However, the investigation of deep-seated reasons behind NBTI-related issue still lacks a feasible approach and has not been explored in depth. This paper proposes a conjoint approach that combines electrical measurements, material analysis, and theoretical calculations to comprehensively investigate the molecular basis of degradation presented by NBTI. Extracting the activation energy of dislocations during stress effectively identifies the deep sources of device deterioration. The breaking of N-H bonds and migration of hydrogen ions along the dislocations in GaN lattice are primarily responsible for the electrical instabilities according to the theoretical calculation of activation energy, which is also evidenced by material characterizations including transmission electron microscopy, X-ray photoelectron spectroscopy and Raman analysis. Also, a molecular-level model that demonstrates the reaction kinetics is well established for the fundamental understanding of the pivotal physicochemical mechanism behind NBTI, thus providing the direction for further optimization of GaN electronics.