Effect of initial crystallization temperature and surface diffusion on formation of GaAs multiple concentric nanoring structures by droplet epitaxy*

Abstract

GaAs multiple concentric nano-ring structures (CNRs) are prepared with multistep crystallization procedures by droplets epitaxy on GaAs (001) to explore the influence of different initial crystallization temperatures on CNRs morphology. Atomic force microscope (AFM) images show that GaAs nanostructures are more likely to form elliptical rings due to diffusion anisotropy. Meanwhile, with the increase of initial crystallization temperature, the inner ring height and density of CNRs are increased, and outer rings are harder to form. In addition, the mechanism of formation of CNRs is discussed by classical nucleation theory and diffusion theory. The method can be used to calculate the diffusion activation energy of gallium atoms (0.7±0.1 eV) on the GaAs (001) surface conveniently.