Study of the effect of gas pressure and catalyst droplets number density on silicon nanowires growth, tapering, and gold coverage
Résumé
We investigated the growth of silicon nanowires from Au-rich catalyst droplets by two different methods: chemical vapor deposition (CVD) and molecular beam epitaxy (MBE). The growth rate is found to be diameter-dependent and increases with increasing precursor partial pressures. The comparison of the experimental results with models shows that the contribution of Si atoms that diffuses from the substrate and the NW sidewalls toward the catalyst droplet can be neglected in CVD for the different pressures used in this study, whereas it is the major source of Si supply for the MBE growth. In addition, by decreasing the number density of catalyst droplet prior to the NW growth in CVD, it is also found that this parameter affects the NWs morphology, increasing the tapering effect when the silane partial pressure is small enough to allow gold atom diffusion from the catalyst droplet
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