Morphology characterization and growth of GaAs nanowires on Selective-area substrates

Gold (Au)-catalyzed and catalyst-free gallium arsenide (GaAs) nanowires (NWs) were grown on GaAs substrates with mask patterns by metal-organic chemical vapor deposition (MOCVD). Catalyst-free GaAs NWs with hexagonal prism morphology were observed by scanning electron microscopy (SEM). The growth rate of catalystfree GaAs NWs was reduced to nearly 5.5% of that of NWs grown using a vapor-liquid-solid (VLS) mechanism. By coating Au as a catalyst on selective-area substrates with the same thickness of Au film, an increased growth was observed. The diameter of the Au-catalyzed NWs grown on selective-area substrates was roughly reduced to 40%, resulting in multiple NWs being squeezed into the same hole. GaAs NWs with cylindrical geometry on selective-area substrates were produced by adjusting the thickness of the Au film, and thus, a single NW could be contained in one hole as the Au film thickness increased.

Automated summary

Gold-catalyzed and catalyst-free gallium arsenide nanowires were grown on GaAs substrates with mask patterns using MOCVD. The morphology of GaAs nanowires changed with catalyst type, and the growth rate of catalyst-free NWs was much lower. By adjusting the thickness of the Au film on selective-area substrates, the growth morphology of nanowires could be controlled effectively.