CHARGE-STATE OF THE NATURAL EX DEFECT IN THERMAL SIO2

K-band electron spin resonance and high-frequency capacitance-voltage measurements have been combined to analyze the charge state of the int rinsic delocalized EX defect naturally generated in thermal SiO2 on (1 11) and (001) Si. The data provide strong evidence for the positive ch arge state of the defect when electron spin resonance active (paramagn etic): the EX centers account, within a factor of 2, for all detected positive charge in the Si-dioxide films. Passivation of the EX defects into a diamagnetic state through hydrogenation is found to go hand in hand with the charge neutralization of the centers.