ReaxFF molecular dynamics study on oxidation behavior of 3C-SiC: Polar face effects

The oxidation of nanoscale 3C-SiC involving four polar faces (C(¯100), Si(100), C(¯1 ¯1 ¯1), and Si(111)) is studied by means of a reactive force field molecular dynamics (ReaxFF MD) simulation. It is shown that the consistency of 3C-SiC structure is broken over 2000 K and the low-density carbon chains are formed within SiC slab. By analyzing the oxygen concentration and fitting to rate theory, activation barriers for C(¯100), Si(100), C(¯1¯1¯1), and Si(111) are found to be 30.1, 35.6, 29.9, and 33.4 kJ.mol^-1. These results reflect lower oxidative stability of C-terminated face, especially along [111] direction. Compared with hexagonal polytypes of SiC, cubic phase may be more energy-favorable to be oxidized under high temperature, indicating polytype effect on SiC oxidation behavior.