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 proton bridge, called E'(4) in quartz, is identified as the trap responsible for stress-induced leakage current, a forerunner of dielectric breakdown in metal-oxide-semiconductor devices.