Nucleation and growth of silicon nitride nanoneedles using microwave plasma heating

We report on needlelike silicon nitride nanowires grown on silicon using ammonia microwave plasma heating. Scanning electron microscope reveals that the nanoneedles are either straight, slightly bent, or kinked with sharp tips. Transmission electron microscope shows that the sizes of the nanowire tips are less than 5 nm and the structures are well crystallized. X-ray diffraction on the surface of the as-deposited structures indicates that both alpha -silicon nitride and beta -silicon nitride exist. Catalyst particle splitting and merging explain observed structure derivation and bending. A vapor-liquid-solid model is employed to explain nucleation and growth mechanism.