Stopping and Resuming at Will the Growth of GaAs Nanowires

We report on the possibility of interrupting and resuming at will the self-assisted growth of GaAs nanowires by molecular beam epitaxy. The Ga nanoparticles assisting nanowire growth on Si-treated GaAs(111)B wafers were consumed by exposure to an As flux. Condensation of a new Ga nanopartide on the top (111)B facets of the existing GaAs nanowires was achieved by either resuming GaAs growth under Ga-rich conditions or exposing the nanowires to a Ga flux. The new Ga nanoparticles were found to assist the growth of new GaAs nanowires in epitaxial relation with the previous nanowires. The growth and regrowth processes of the nanowires are jointly described by an analytical model that can reproduce the observed experimental time dependence of nanowire length and diameter.