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首页> 外文期刊>Physical review >Atomistic modeling of the Au droplet-GaAs interface for size-selective nanowire growth
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Atomistic modeling of the Au droplet-GaAs interface for size-selective nanowire growth

机译：用于尺寸选择纳米线生长的Au液滴-GaAs界面的原子建模

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摘要

Density functional theory calculations within both the local density approximation and the generalized gradient approximation are used to study Au-catalyzed growth under near-equilibrium conditions. We discuss both the chemical equilibrium of a GaAs nanowire with an A_(s2) gas atmosphere and the mechanical equilibrium between the capillary forces at the nanowire tip. For the latter goal, the interface between the gold nanoparticle and the nanowire is modeled atomically within a slab approach, and the interface energies are evaluated from the total energies of the model systems. We discuss three growth regimes, one catalyzed by an (almost) pure Au particle, an intermediate alloy-catalyzed growth regime, and a Ga-catalyzed growth regime. Using the interface energies calculated from the atomic models, as well as the surface energies of the nanoparticle and the nanowire sidewalls, we determine the optimized geometry of the nanoparticle-capped nanowire by minimizing the free energy of a continuum model. Under typical experimental conditions of 10~(-4) Pa As_2 and 700 K, our results in the local density approximation are insensitive to the Ga concentration in the nanoparticle. In these growth conditions, the energetically most favored interface has an interface energy of around 45 meV/A~2, and the correspondingly optimized droplet on top of a GaAs nanowire is somewhat larger than a hemisphere and forms a contact angle around 130° for both pure Au and Au-Ga alloy nanoparticles.
机译：局部密度近似和广义梯度近似中的密度泛函理论计算被用于研究金在近似平衡条件下的生长。我们既讨论了具有A_（s2）气氛的GaAs纳米线的化学平衡，也讨论了纳米线尖端的毛细管力之间的机械平衡。对于后一个目标，在平板方法中以原子方式对金纳米粒子和纳米线之间的界面进行建模，然后从模型系统的总能量中评估界面能量。我们讨论了三种生长方式，一种由（几乎）纯Au颗粒催化，一种中间合金催化的生长方式，以及Ga催化的生长方式。使用从原子模型计算的界面能，以及纳米粒子和纳米线侧壁的表面能，我们通过最小化连续体模型的自由能来确定纳米粒子封端的纳米线的优化几何形状。在10〜（-4）Pa As_2和700 K的典型实验条件下，我们的局部密度近似结果对纳米粒子中的Ga浓度不敏感。在这些生长条件下，能量最受青睐的界面具有约45 meV / A〜2的界面能，并且在GaAs纳米线顶部相应优化的液滴略大于半球，并且两者形成约130°的接触角纯Au和Au-Ga合金纳米粒子。

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  • 来源
    《Physical review》 |2013年第15期|155309.1-155309.9|共9页
  • 作者

    Sung Sakong; Yaojun A. Du; Peter Kratzer;

  • 作者单位

    Fakultaet fuer Physik and Center for Nanointegration (CENIDE), Universitaet Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany;

    Institut fuer Theoretische Chemie, Universitaet Ulm, Albert-Einstein-Allee 11, D-89069 Ulm, Germany;

    Fakultaet fuer Physik and Center for Nanointegration (CENIDE), Universitaet Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany;

    Fakultaet fuer Physik and Center for Nanointegration (CENIDE), Universitaet Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany;

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  • 正文语种 eng
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  • 关键词

    solid surfaces and solidsolid interfaces: structure and energetics; ⅢⅤ semiconductors;

    机译：固体表面和固体界面：结构和能量学;ⅢⅤ半导体;

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