Evolution between self-assembled single and double ring-like nanostructures

The evolution between lattice-matched GaAs/Al0.3Ga0.7As single and double ring-like nanostructures is studied, with an emphasis on the construction and destruction of the observed outer ring. Using droplet epitaxy, this was achieved by directly controlling the Ga surface diffusion on GaAs( 100). Double ring-like nanostructures were observed at relatively low temperatures under a fixed As-4 flux (beam equivalent pressure (BEP) of 6.4 mu Torr) and at a fixed temperature under a high As-4 flux. The construction of the outer ring can be controlled through surface diffusion by varying the substrate temperature or the As-4 flux. Single ring-like nanostructures were realized both at relatively high temperatures under a fixed As-4 flux, and at low temperatures under a relatively low As-4