Linearization of BTI Degradation Across Si, SiC, and GaN

Bias temperature instability (BTI) degradation is commonly described using empirical power-law kinetics; however, extraction of the time exponent and projection of lifetime remain highly sensitive to baseline definition and data representation. In conventional approaches, the threshold voltage shift is referenced to an initial value that cannot be measured simultaneously with stress, introducing uncertainty that can produce apparent curvature and variability in the extracted exponent. In this work, a baseline-independent linearization method is applied to representative published datasets spanning advanced silicon, SiC MOSFETs, and GaN power devices. By analyzing the measured degradation trajectories directly in a transformed time coordinate, the method removes curvature associated with baseline ambiguity and enables consistent extraction of the effective power-law exponent. Across all material systems examined, the extracted exponent exhibits systematic dependence on applied stress once baseline effects are reduced. This behavior challenges the commonly assumed constant-exponent formulation used in conventional lifetime projections and shows that even modest variations in the exponent can produce large differences in projected time-to-failure. A transformed lifetime representation based on is introduced, in which the influence of exponent variation is separated from the intrinsic voltage and temperature acceleration of the degradation rate. In this representation, the extracted acceleration parameters become more stable and physically interpretable. This formulation is consistent with standard reliability frameworks, including JEDEC JEP122G, in which the time exponent enters directly into the lifetime expression. These results demonstrate that baseline-independent analysis provides a unified framework for interpreting BTI degradation across disparate semiconductor technologies and suggest that explicit treatment of stress-dependent exponents is required for physically consistent lifetime modeling.