Maximum density of Pb centers at the (111) Si/SiO2 interface after vacuum anneal

Abstract

The density of interfacial [111]Pb centers, i.e., 0Si≡Si3 defects with unpaired bond along [111], has been accurately determined by K-band electron spin resonance at 4.3 K on (111)Si/SiO2 structures using various oxidation conditions. Reversible defect depassivation (dehydrogenation) has been monitored by post-oxidation vacuum annealing in the temperature range 752–835 °C. It was found that the density of both ESR active and passivated Pb defects is (11.4±0.6)×1012 cm−2 on all (111)Si/SiO2 interfaces prepared by oxidation in dry O2 at 920–1000 °C. This number appears to be a natural constant predominantly set by the oxidation temperature; variations in oxidation oxygen pressure (1.5×10−5–840 Torr) and time have little influence. The Pb’s are found to account for all the fast interface states.