Role of the bond defect for structural transformations between crystallineand amorphous silicon: A molecular-dynamics study

The relation between the bond defect, which is a topological defect, and st ructural transformations between crystalline and amorphous silicon, is stud ied by molecular-dynamics simulations. The investigation of 1-keV boron imp lantation into crystalline silicon proves that the bond defect can also be generated directly by collisional-induced bond switching in addition to its formation by incomplete recombination of primary defects. This supports th e assumption that the bond defect may play an important role in the amorphi zation process of silicon by light ions. The analysis of the interface betw een (001) silicon and amorphous silicon shows that there are two typical de fect configurations at the interface which result from two different orient ations of the bond defect with respect to the interface. Thus the bond defe ct appears to be a characteristic structural feature of the interface. More over, annealing results indicate that the bond defect acts as a growth site for interface-mediated crystallization.