Defect generation at SiO₂/Si interfaces by low pressure chemical vapor deposition of silicon nitride

Low pressure chemical vapor deposition of Si₃N₄ on oxidized Si (111) surfaces causes a change in the properties of the dominant interface defect, the P_b center, observed by electron paramagnetic resonance. The change in the signature of the P_b center is consistent with the formation of an oxynitride layer at the interface, which could be formed during the initial stages of nitride layer deposition. Photoconductivity decay measurements show a concomitant increase in the minority carrier recombination rate at the Si surface. The modified Si surface shows a worse thermal stability than the as-oxidized Si surface.