BONDING AND SHORT-RANGE ORDER IN LIQUID SILICON-CARBON ALLOYS

Simulations of liquid silicon-carbon mixtures show that, at low pressures, the tendency of carbon towards low coordination dominates the overall structural characteristics. As a result silicon coordination is lower than in pure l-Si, accompanied by an enhancement of tetrahedral order and covalent bonding which persist in the liquid. The distribution of atoms is random in contrast to amorphous Si-C alloys. Under high pressures (approximately 1 Mbar) carbon coordination remains lower than four. At this pressure pure l-C is less dense than diamond.