School of Materials Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA.
Nano Lett. 2010 Feb 10;10(2):514-9. doi: 10.1021/nl903362y.
We use real-time observations of the growth of copper-catalyzed silicon nanowires to determine the nanowire growth mechanism directly and to quantify the growth kinetics of individual wires. Nanowires were grown in a transmission electron microscope using chemical vapor deposition on a copper-coated Si substrate. We show that the initial reaction is the formation of a silicide, eta'-Cu(3)Si, and that this solid silicide remains on the wire tips during growth so that growth is by the vapor-solid-solid mechanism. Individual wire directions and growth rates are related to the details of orientation relation and catalyst shape, leading to a rich morphology compared to vapor-liquid-solid grown nanowires. Furthermore, growth occurs by ledge propagation at the silicide/silicon interface, and the ledge propagation kinetics suggest that the solubility of precursor atoms in the catalyst is small, which is relevant to the fabrication of abrupt heterojunctions in nanowires.
我们利用铜催化硅纳米线生长的实时观测结果，直接确定纳米线的生长机制，并定量描述单根纳米线的生长动力学。纳米线是在铜覆盖的硅衬底上使用化学气相沉积，在透射电子显微镜中生长的。我们表明，初始反应是形成硅化物 eta'-Cu(3)Si，并且在生长过程中，这种固态硅化物仍然留在纳米线尖端，因此生长是通过气-固-固机制进行的。个别纳米线的方向和生长速率与取向关系和催化剂形状的细节有关，导致与通过气-液-固生长的纳米线相比，具有丰富的形态。此外，生长是通过硅化物/硅界面上的平台扩展进行的，平台扩展动力学表明，前体原子在催化剂中的溶解度较小，这与纳米线中突然形成异质结有关。
