The energies of reactions occurring at the SiC/SiO2 interface upon nitridation were

reported. The computational approach was to calculate the energy of incoming and

outgoing molecules in a bulk super-cell of SiO2, and that of interface defects before

or after the reaction in a slab model of the 4H-SiC/SiO2 interface. Incoming

molecules in bulk SiO2 were assumed to be neutral, but the interface was coupled

to a reservoir of electrons with an energy corresponding to the Fermi level of the

semiconductor. The latter was determined by the temperature of nitridation

(~1100C) and the usual doping of the channel region (1015 to 1016/cm3) of a MOS

(metal-oxide-semiconductor) transistor with an n-type channel, to be 1.9 to 2.2eV,

with respect to the valence band edge of SiC. Using the calculated total energies, energies of exchange reactions between the models were calculated; adding a band

off-set correction for each electron transfer between the models (to account for the

error introduced by using the pseudopotential approximation in two different

models).

The Mechanism of Defect Creation and Passivation at the SiC/SiO2 Interface.

P.Deák, J.Knaup, C.Thill, T.Frauenheim, T.Hornos, A.Gali: Journal of Physics D,

2008, 41[4], 049801