Generation of amorphous SiO₂/SiC interface and dynamical simulation of interface oxidation process of SiC device

Silicon carbide (SiC) semiconductor devices are expected to be used in severe environments such as outer space and nuclear power plants. However, SiC devices don't present the expected performance. This is considered to be attributed to the defects at the interface between SiC and the oxide (SiO₂) layer that reduce electrical characteristics of them. For the application of computer simulation to the realistic interface structures, it is important to construct the structure of amorphous SiO₂ (a- SiO₂) on SiC. The slab model using 444 atoms for a-SiO₂ on a 4H-SiC (0001) crystal layer was constructed by using first-principles molecular dynamics (MD) simulation code optimized for the Earth-Simulator in order to obtain a more realistic structure and electronic geometry of a-SiO₂/4H-SiC interface. The heating and rapid quenching method was carried out to make an a-SiO₂/SiC interface structure. The heating temperature, the heating time or the speed of rapid quenching is 4000 K, 3.0 ps or -1000 K/ps, respectively. As the result, the interatomic distance and the bond angles of SiO₂ layers agreed well with the most probable values in bulk a-SiO₂, and there were no coordination defects in the neighborhood of the SiC substrate. The first-principle molecular dynamics calculation of the oxidation process on the SiO₂/SiC interface succeeded for the first time. The carbon cluster that seems to be one of the causes of the interface trap formation is formed in the process of the oxidation. (author)