Maliakkal Carina B, Mårtensson Erik K, Tornberg Marcus Ulf, Jacobsson Daniel, Persson Axel R, Johansson Jonas, Wallenberg Lars Reine, Dick Kimberly A
Centre for Analysis and Synthesis, Lund University, Box 124, 22100 Lund, Sweden.
Solid State Physics, Lund University, Box 118, 22100 Lund, Sweden.
ACS Nano. 2020 Apr 28;14(4):3868-3875. doi: 10.1021/acsnano.9b09816. Epub 2020 Feb 21.
Control of the crystallization process is central to developing nanomaterials with atomic precision to meet the demands of electronic and quantum technology applications. Semiconductor nanowires grown by the vapor-liquid-solid process are a promising material system in which the ability to form components with structure and composition not achievable in bulk is well-established. Here, we use TEM imaging of Au-catalyzed GaAs nanowire growth to understand the processes by which the growth dynamics are connected to the experimental parameters. We find that two sequential steps in the crystallization process-nucleation and layer growth-can occur on similar time scales and can be controlled independently using different growth parameters. Importantly, the layer growth process contributes significantly to the growth time for all conditions and will play a major role in determining material properties such as compositional uniformity, dopant density, and impurity incorporation. The results are understood through theoretical simulations correlating the growth dynamics, liquid droplet, and experimental parameters. The key insights discussed here are not restricted to Au-catalyzed GaAs nanowire growth but can be extended to most compound nanowire growths in which the different growth species has very different solubility in the catalyst particle.
控制结晶过程对于开发具有原子精度的纳米材料以满足电子和量子技术应用的需求至关重要。通过气-液-固过程生长的半导体纳米线是一种很有前景的材料体系，在该体系中，形成具有块体材料无法实现的结构和组成的组件的能力已得到充分证实。在这里，我们使用透射电子显微镜（TEM）成像来研究金催化的砷化镓纳米线生长过程，以了解生长动力学与实验参数之间的关联过程。我们发现，结晶过程中的两个连续步骤——成核和层生长——可以在相似的时间尺度上发生，并且可以通过不同的生长参数独立控制。重要的是，层生长过程在所有条件下对生长时间都有显著贡献，并且在决定材料性能（如成分均匀性、掺杂剂密度和杂质掺入）方面将发挥主要作用。通过将生长动力学、液滴和实验参数相关联的理论模拟来理解这些结果。这里讨论的关键见解不仅限于金催化的砷化镓纳米线生长，还可以扩展到大多数复合纳米线生长，其中不同的生长物种在催化剂颗粒中的溶解度差异很大。
