Diffusion-induced growth of GaAs nanowhiskers during molecular beam epitaxy: Theory and experiment

Mechanisms of nanowhisker formation during molecular beam epitaxy (MBE) are studied theoretically within the frame of a kinetic model that accounts for the adatom diffusion from the surface to the top of nanowhiskers. It is shown that the adatom diffusion flux may considerably increase the vertical growth rate of nanowhiskers. The decreasing length/diameter dependence of the MBE grown nanowhiskers is obtained that explains a number of experimentally observed facts. The results of experimental investigations of GaAs nanowhiskers grown by MBE on the GaAs(111)B surface activated by Au at different conditions are presented and analyzed. It is shown that the length of thin GaAs nanowhiskers is several times larger than the effective thickness of deposited GaAs. Theoretical and experimental length/diameter curves are compared to each other and a good correlation between them is demonstrated.