Morphological control of GaAs/InAs radial heterostructure nanowires: From cylindrical to coherent quantum dot structure

Abstract

Various surface morphologies of hierarchical GaAs/InAs core/shell heterostructure were obtained by carefully tuning the growth parameters. The growth of the InAs shell around the surface of the GaAs core could be evolved from 2D mode to 3D mode as the variation of the growth parameters. As a consequence, the morphology of the InAs shell can systematically change from the uniformly coated cylindrical to isolated islands and eventually nanorings. The isolated nanoring structure can be formed innovatively by coalescence of the islands without the assistance of twin-induced concave sites. Different types of dislocations in the shell structure, which could result from the different behaviors of misfit-stress relaxation processes, were observed during these two growth modes. The mechanisms of the morphological evolution are also discussed in detail.