Growth of nickel disilicide nanowires by CVD

A systematic study of the influence of the process parameters on the growth of nickel disilicide (NiSi2) nanowires by CVD (Chemical Vapor Deposition) has been carried out in the temperature range of 350 degrees C to 550 degrees C. Ni thin films thinner than 100 nm were dissociated using different RTP (Rapid Thermal Processing) steps in order to create Ni droplets which act as nucleation sites for the nanowire growth. Thereafter, silane (SiH4) was flown over these nucleation sites in an attempt to grown nickel silicide nanowires. The purpose of this report is to determine the optimal set of process parameters promoting the growth of nanowires. Moreover, we have studied the impact of the RTP step and the influence of the original (prior to annealing) thickness and status of the Ni layer that once dissociated acts as a catalyst. Also, the effect of the surface underneath the Ni droplets has been investigated. Scanning Electron Microscopy (SEM) as well as Energy Backscattering Electron Diffraction (EBSD) techniques were used to characterize the as-synthesized nanowires. High-resolution transmission electron microscopy (HR-TEM) results show that the nanowires are monocrystalline with a separation of the lattice planes corresponding NiSi2. HR-TEM also showed that the nickel disilicide nanowires do not all grow in a specific growth direction but that several growth directions such as < 111 > or < 110 > coexist within one and the same nanowire. (C) 2010 Elsevier B.V. All rights reserved.