Hydrogen Electrochemistry and Stress-Induced Leakage Current in Silica

Hydrogen-related defects in oxygen-deficient silica, representing the material of a thermal gate oxide, are analyzed using first-principles calculations. Energetics and charge-state levels of oxygen vacancies, hydrogen, and their complexes in the silica framework are mapped out. The neutral hydrogen bridge, called E₄^' in quartz, is identified as the trap responsible for stress-induced leakage current, a forerunner of dielectric breakdown in metal-oxide--semiconductor devices.