As implemented in commercialized device modeling software, the four-state nonradiative multiphonon model has attracted intensive attention in the past decade for describing the physics in negative bias temperature instability (NBTI) and other reliability issues of ${\mathrm{Si}/\mathrm{Si}\mathrm{O}}_2$ metal-oxide-semiconductor field effect transistor (MOSFET) devices. It was proposed initially based on the assumption that the oxygen vacancy defects (${\mathrm{V}}_{\mathrm{O}}$) in ${\mathrm{Si}\mathrm{O}}_2$ dielectric layer are bistable in the Si-dimer and back-projected structures during carrier capture and emission. Through high-throughput first-principles structural search, we found ${\mathrm{V}}_{\mathrm{O}}$ on nonequivalent O sites in amorphous ${\mathrm{Si}\mathrm{O}}_2$ can take four types of structural configurations in neutral state and seven types of configurations in +1 charged state after capturing holes, which produce a wide range of charge-state transition levels for trapping holes. The finding contrasts the structural-bistability assumption and makes the four-state model invalid for most O sites. To describe the reliability physics accurately, we propose an all-state model to consider all these structural configurations as well as all the carrier capture/emission transitions and thermal transitions between them. With the all-state model, we show that the ${\mathrm{V}}_{\mathrm{O}}$ defects play important roles in causing NBTI, which challenges the recent studies that discarded ${\mathrm{V}}_{\mathrm{O}}$ as a possible hole trap in NBTI. Our systematical calculations on the diversified ${\mathrm{V}}_{\mathrm{O}}$ properties and the all-state model provide the microscopic foundation for describing the reliability physics of MOSFETs and other transistors accurately.

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• Carrier dynamics
• Defects
• Electronic transitions
• Phonons
• Thermal properties
• Field-effect transistors
• First-principles calculations
• Materials modeling