A molecular dynamics simulation of diamond/silicon (001) interface

The structure of diamond/silicon interface, which was formed by the contact and the subsequent relaxation of the unreconstructed (001) surfaces of dia mond film and silicon substrate, has been investigated by molecular dynamic s simulation. The interaction among atoms of the silicon/carbon binary syst em was described by Tersoff many-body empirical potential. Before relaxatio n, the ratios of silicon atoms to carbon atoms along [110] and [1 (1) over bar0] directions are both 3:2 and the ratio of the total number of interfac ial silicon atoms to that of carbon is 9:4. After relaxation, the matching of diamond and silicon lattices has been changed: along [1 (1) over bar0] d irection, a 3:2 coincidence relation is roughly remained, but along [110] d irection, a 1:1 coincidence relation is approximately adopted. Accordingly, the ratio of the total number of interfacial silicon atoms to that of carb on is near 3:2. The migration of partial silicon atoms, which were original ly in the second layer, upward to the interface is responsible for such cha nges. The silicon lattice near the interface shows the tendency of disorder ing along [001] direction. The strong bonding between interfacial silicon a nd carbon atoms was found and Si-C bonds with an average length of 0.189 nm were formed. This study has confirmed that the main feature of lattice mat ching is the meeting of silicon atoms at and near the interface to the arra ngement of interfacial carbon atoms.