Formation of Higher Polytypes in III-V - Nanowires
Physical Chemistry of Solids and Surfaces, Material Characterisation
Final Report Abstract
In conclusion, the nucleation as a random process can not be the root cause for the strong broadening which is observed in growth experiments. Especially for thin wires where the depletion of the droplet regulates the growth of the next layer, no broadening can be expected when only nucleation is considered. For the limit of large radii, a Poissonian broadening could be demonstrated in the simulations, but no super-Poissonian broadening could be shown. Rather than nucleation, diffusion effects must be the origin for the experimentally observed length distribution. Due to surface diffusion effects along the substrate and along the NW sidewalls the material transport towards the droplet becomes inhomogeneous depending on the density and the areal distribution of NWs in an array, i.e. number and distance of next nearest NWs. The broadening effect of growing NWs driven by surface diffusion was elucidated in collaboration with the group of Vladimir Dubroskii (St. Petersburg Academic University) and was published in a joint paper. It turns out that with the help of models which take surface diffusion into account, the experimental length distributions can be fitted well with for different radii as well as the correct evolution of the length distribution with time can be shown.
Publications
- “Length distributions of nanowires growing by surface diffusion”, Crystal Growth & Design 2016, vol 16, p 2167-2172
V Dubroskii, Y Berdnikov, J Schmidtbauer, M Borg, K Storm, K Deppert, J Johansson
(See online at https://doi.org/10.1021/acs.cgd.5b01832)
