Effects of nitridation on the characteristics of silicon dioxide: dielectric and structural properties from ab initio calculations.
By combining ab initio calculations and classical molecular dynamics, we determine how the inclusion of nitrogen in a silica matrix changes its dielectric constant, and elucidate the underlying mechanisms. We find that there is an entire range of nitrogen concentrations (up to approximately 25%) for which the structural pattern of the oxide is preserved in bulk SiON, and the dielectric constant increases mainly because of the variation of the ionic polarizability. This behavior is not sensitive to hydrogen passivation of nitrogen. The few defects, which are associated with electron states near the gap, are mainly centered on undercoordinated nitrogen and undercoordinated silicon, and tend to be removed by hydrogen.
Fischer
Dominik
D
IBM Research, Zurich Research Laboratory, 8803 Ruschlikon, Switzerland.
Curioni
Alessandro
A
Billeter
Salomon
S
Andreoni
Wanda
W