Ikejiri Keitaro, Sato Takuya, Yoshida Hiroatsu, Hiruma Kenji, Motohisa Junichi, Hara Shinjiroh, Fukui Takashi
Research Centre for Integrated Quantum Electronics, Hokkaido University, North 13, West 8, Sapporo 060-8628, Japan.
Nanotechnology. 2008 Jul 2;19(26):265604. doi: 10.1088/0957-4484/19/26/265604. Epub 2008 May 20.
GaAs nanowires were selectively grown by metal-organic vapour-phase epitaxy within a SiO(2) mask window pattern fabricated on a GaAs(111)B substrate surface. The nanowires were 100-3000 nm in height and 50-300 nm in diameter. The height decreased as the mask window diameter was increased or the growth temperature was increased from 700 to 800 °C. The dependence of the nanowire height on the mask window diameter was compared with a calculation, which indicated that the height was inversely proportional to the mask window diameter. This suggests that the migration of growth species on the nanowire side surface plays a major role. Tetrahedral GaAs grew at an early stage of nanowire growth but became hexagonal as the growth process continued. The calculated change in Gibbs free energy for nucleation growth of the crystals indicated that tetrahedra were energetically more favourable than hexagons. Transmission and scanning electron microscopy analyses of a GaAs nanowire showed that many twins developed along the [Formula: see text] B direction, suggesting that twins had something to do with the evolution of the nanowire shape from tetrahedron to hexagon.
通过金属有机气相外延在生长于GaAs(111)B衬底表面上的SiO₂掩膜窗口图案内选择性生长砷化镓纳米线。纳米线高度为100 - 3000纳米，直径为50 - 300纳米。随着掩膜窗口直径增大或生长温度从700℃升高到800℃，纳米线高度降低。将纳米线高度对掩膜窗口直径的依赖性与计算结果进行比较，结果表明高度与掩膜窗口直径成反比。这表明生长物种在纳米线侧面的迁移起主要作用。四面体砷化镓在纳米线生长的早期阶段生长，但随着生长过程的持续变为六面体。晶体成核生长的吉布斯自由能计算变化表明，四面体在能量上比六面体更有利。对一根砷化镓纳米线的透射和扫描电子显微镜分析表明，许多孪晶沿[公式：见正文]B方向形成，这表明孪晶与纳米线形状从四面体到六面体的演变有关。
