LETTER TO THE EDITOR: Blocking of thermally induced interface degradation in (111) ? by He

The interface degradation induced in (111) by postoxidation annealing in vacuum, previously identified by electron spin resonance as intense creation of interfacial Si dangling bond defects from on, is found to be remarkably suppressed when annealing in He ambient. On the time scale of , He firmly blocks the degradation up to , from which temperature on creation gradually rises, though much suppressed as compared to the vacuum case. At , the density drops abruptly to a value ( about one-third that of the as-oxidized state density, indicating an electrically much improved interface. The transition results from the known thermal cooperative restructuring of the layer, completed at . The data support the degradation model based on interfacial SiO(g) release, where He is seen as rapidly occupying the SiO accessible sites in the oxide thus inhibiting the degradation mechanism through impeding SiO removal - a prerequisite for the degradation to occur.

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