A model of the formation of nanowire crystals on surfaces activated by droplets of the growth catalyst was developed. In the model, the diffusion of adatoms from the surface of the substrate to the lateral surface of the crystals was taken into account. The exact solution of the diffusion problem for the flow of adatoms from the surface to the nanowire crystals was obtained, and the particular cases of the solution for short and long diffusion lengths of adatoms, λs, were analyzed. A general expression for the length of the nanowire crystals, L, in relation to their radius R and to the conditions of growth was derived. The expression was applicable to a large variety of growth technologies. The theoretical results were compared with the experimental dependences L(R) in the range of R = 20 to 250nm for GaAs nanowire crystals grown by molecular-beam epitaxy onto a GaAs (111) surface activated by Au. It was shown that, in some range of the parameters, the dependence L(R) obeyed the function 1/R 2ln(λs/R), which was radically different from the classical diffusion dependence, 1/R.

The Role of Surface Diffusion of Adatoms in the Formation of Nanowire Crystals. V.G.Dubrovskiĭ, N.V.Sibirev, R.A.Suris, G.É.Cirlin, V.M.Ustinov, M.Tchernysheva, J.C.Harmand: Semiconductors, 2006, 40[9], 1075-82