Neck formation processes of nanocrystalline silicon carbide: a tight-binding molecular dynamics study

Atomistic and electronic structures in the process of intergranular neck fo rmation of nanocrystalline silicon carbide (SiC) have been investigated by a tight-binding molecular dynamics method. An order-N parallel algorithm is employed for efficient calculations of electronic energy and forces. We fi nd that a defect-free neck is formed between SIC nanocrystals aligned along [11 (2) over bar] axis at T = 1000 K. In the case of neck formation betwee n tilted nanocrystals (with an orientation equivalent to a {122}, Sigma = 9 grain boundary), surface reconstruction before sintering, that is Si-Si bo nd formation, significantly affects the grain-boundary formation. The spati al distribution of the electronic population and the electronic density of states show that structural defects, accompanied by gap states, are formed around the reconstructed regions after the sintering.