Role of defects and growth directions in the formation of periodically twinned and kinked unseeded germanium nanowires

Here we show the impact of preferred growth directions and defects in the formation of complex Ge nanowire (NW) structures grown by a simple organic medium based synthesis. Various types of NWs are examined including: straight defect free NWs; periodically bent NWs with precise angles between the NW segments; NWs with mutually exclusive lateral or longitudinal faults; and more complex "wormlike" structures. We show that choice of solvent and reaction temperature can be used to tune the morphology of the NWs formed. The various types of NWs were probed in depth using transmission electron microscopy (TEM), scanning electron microscopy (SEM), selected area electron diffraction (SAED), and dark field TEM (DFTEM).