Structure-sensitive principle in silicon nanowire growth

Silicon (Si) nanowires with twining or stacking faults are challenging their applications in microelectronic devices. It is of great value to explore the assembling principle of the crystal structure of Si nanowires. In this work, Si nanowires are grown by thermal annealing of nickel (Ni) coated Si wafers underneath an amorphous carbon layer. A systematically investigation is performed on the crystal structure of Si nanowires and the connected Ni catalyst particles using field emission scanning electron microscopy, high resolution transmission electron microscopy and selected area electron diffraction pattern. The results reveal that the defect-free Si nanowire has a highly crystalline Si core surrounded by the amorphous Si-oxide shell. Twinning and stacking faults are discovered locating near the Ni catalyst particles. The origin for the structural defects is explained by a structure-sensitive principle.