Nanopillar growth mode by vapor-liquid-solid epitaxy

We report epitaxial growth of Ge nanopillars (NPs) on Si(100) by vapor-liquid-solid (VLS) growth from digermane. This growth morphology is characterized by short, low-aspect-ratio pillars and is markedly different from the long, narrow nanowires (NWs) previously reported for VLS growth. The NP growth mode occurs at low digermane pressures. It is attributed to surface-diffusion-induced lateral growth in combination with an insufficient Ge concentration gradient in the AuGe eutectic to catalyze NW growth. High resolution electron microscopy confirms that the NPs are epitaxial with the Si (100) substrate and are fully relaxed and strain free.