Based upon first-principles density-functional calculations, N-associated defects at Si/SiO2 interfaces were proposed which behaved as predominant interface states in Si oxynitrides instead of conventional Pb centers in pure SiO2. These defects involved an N interstitial, and their energy levels lay in the broad range from the mid-gap to the conduction-band edge of Si, depending upon the local oxidation status near N, while electrical states from Pb-type centers were removed by substitutional N atoms. The results provided a mechanism for degradations related to the interface defects in Si oxynitrides which were used in state-of-the-art metal-oxide-semiconductor devices.

Nitrogen-Induced Interface Defects in Si Oxynitride. E.C.Lee: Physical Review B, 2008, 77[10], 104108 (4pp)