Defect-free ultralong InAs nanowires Au-catalyzed growth on graphene/Ge by molecular beam epitaxy

The self-catalyzed growth of InAs nanowires (NWs) on graphene is achievable but typically yields short, thick NWs with frequent stacking-fault defects. In this work, we demonstrate the successful synthesis of defect-free, ultralong InAs NWs by harnessing the synergistic effects of graphene and an Au catalyst. The distinct roles of graphene and Au in promoting the growth of high-quality NWs were systematically elucidated. Atomic resolution scanning transmission electron microscopy (STEM) imaging revealed that the Au-catalyzed InAs NWs grown on graphene predominantly exhibit defect-free wurtzite structures, whereas a small portion of nanosheets and the NWs grown atop them display defect-free zinc blende phases. Based on these observations, a growth model for Au-catalyzed InAs NWs on defective graphene/Ge surfaces was proposed.