Ab initio calculation on atomic structure and charge transfer of silicon oxycarbide (SIOxCy) at the SiC/SiO2 interface

The atomic structure and structural stabilities of silicon oxycarbide SiOxC y phase formed at the SiC/SiO2 interface were studied using ab initio pseud opotential method. The total energies and the cohesive energies of the SiOx Cy at different composition: SiC, SiO1/4C3/4, SiO1/2Cl1/2, SiO3/4C1/4, SiO2 , SiO5/3C1/3, SiO4/3C2/3, SiOC, SiO2/3C4/3 and SiO1/3C5/3 were calculated a t zero temperature by relaxing the local atomic positions. The SiOxCy phase showed a structural preference to the SiC-like structure when carbon/oxyge n (C/O) composition ratio was greater than unity (i.e.: y > x), and to the SiO2-like structure when the ratio was less than unity (i.e., y < x). The c harge distribution on atoms (Si, C and O) were calculated and it was found that electrons were transferred from Si to C with less amount than to O.