Formation Mechanisms of Multiple Concentric Nanoring Structures upon Droplet Epitaxy

We have developed a theoretical model to elucidate the formation mechanisms of multiple concentric nanoring structures upon droplet epitaxy. On the basis of the developed model, we performed the shape evolution of GaAs nanostructures during the multistep crystallization process. Theoretical analyses indicated the rapid growth region at the periphery of the diffusion region is pushed outward by increasing growth temperature, which results in the formation of an outer ring. In addition, according to our model, we proposed that multiple concentric nanoring structures can also be obtained via reducing element flux intensity using a multistep crystallization procedure which may be more advantageous than that via increasing temperature.