Tapering Control of Si Nanowires Grown from SiCl4 at Reduced Pressure
Tapering Control of Si Nanowires Grown from SiCl4 at Reduced Pressure
复制标题
DOI：
10.1021/nn102556s
复制
发表时间：
2011-01-01
期刊：
影响因子：
17.1
通讯作者：
Levin, Igor
中科院分区：
文献类型：
--
作者：
Krylyuk, Sergiy;Davydov, Albert V.;Levin, Igor
锥形硅纳米线（SiNW）阵列的设备应用需要可靠的技术方法来制造具有受控形状和方向的纳米线。在本研究中，我们系统地探讨了生长条件对 Si 纳米线锥度的影响，该 Si 纳米线是通过 Sicl(4) 前驱体在减压下通过化学气相沉积 (CVD) 生长的。 SiNW 的锥化由催化气-液-固 (VLS) 和非催化气-液-固 (VS) 生长机制之间的相互作用控制。我们发现了非催化气液固（VLS）和非催化气液固（VS）的生长机制。我们发现 NW 侧壁上未催化的 Si 沉积已确定。径向生长速率可以通过降低 SiCl4/H-2 摩尔比、应用更高的气体流速或降低生长压力来增强。轴向和径向生长速率对工艺条件的明显依赖性被用来生产锥度（即径向/轴向生长速率的比率）变化近2个数量级的SiNW。结果可以通过热力学和动力学效应对轴向 (VLS) 和径向 (VS) 增长率的相互作用来解释。 SiCl4/H-2 摩尔比和纳米线垂直排列之间已建立的相关性被用来开发两阶段生长程序，用于生产主要垂直方向的锥形 SiNW 阵列。
Device applications of tapered Si nanoWire (SiNW) arrays require reliable technological approaches for fabricatiing nanowires with controlled shape and orientation. In this study, we systematically explore effects of growth conditions on tapering of Si nanowires grown by chemical vapor deposition (CVD) at reduced pressure from Sicl(4) precursor. Tapering of SiNWs is governed by the interplay between the catalyzed vapor-liquid-solid (VLS) and uncatalyzed vapor-solid (VS) growth mechanisms. We found that the uncatalyzed vapor liquid solid (VLS) and uncatalyzed vapor solid (VS) growth Mechanisms. We found that the uncatalyzed Si deposition on NW sidewalls, defined. by a radial growth rate, can be enhanced by lowering SiCl4/H-2 molar ratio, applying higher gas flow rate, or reducing growth pressure. Distinct dependences of the axial and radial growth rates on the process conditions were employed to produce SiNWs with a tapering degree (i.e., a ratio of the radial/axial growth rates) varying by almost 2 orders of magnitude. The results are explained by an interplay between the thermodynamic and kinetic effects on the axial (VLS) and radial (VS) growth rates. Established correlation between the SiCl4/H-2 molar ratio and vertical alignment of nanowires was used to develop a two-stage growth procedure for producing tapered SiNW arrays with predominantly vertical orientation.