Instituto de Física"GlebWataghin", Universidade Estadual de Campinas, UNICAMP, 13083-859, Campinas, SP, Brazil.
Nano Lett. 2011 May 11;11(5):1934-40. doi: 10.1021/nl200083f. Epub 2011 Apr 18.
InP nanowire polytypic growth was thoroughly studied using electron microscopy techniques as a function of the In precursor flow. The dominant InP crystal structure is wurtzite, and growth parameters determine the density of stacking faults (SF) and zinc blende segments along the nanowires (NWs). Our results show that SF formation in InP NWs cannot be univocally attributed to the droplet supersaturation, if we assume this variable to be proportional to the ex situ In atomic concentration at the catalyst particle. An imbalance between this concentration and the axial growth rate was detected for growth conditions associated with larger SF densities along the NWs, suggesting a different route of precursor incorporation at the triple phase line in that case. The formation of SFs can be further enhanced by varying the In supply during growth and is suppressed for small diameter NWs grown under the same conditions. We attribute the observed behaviors to kinetically driven roughening of the semiconductor/metal interface. The consequent deformation of the triple phase line increases the probability of a phase change at the growth interface in an effort to reach local minima of system interface and surface energy.
我们利用电子显微镜技术深入研究了 InP 纳米线的多型生长，研究重点是 In 前体流速的影响。实验结果表明，纳米线中 wurtzite 结构占主导地位，生长参数决定了纳米线中沿轴向的位错（SF）和闪锌矿段的密度。实验结果表明，如果我们假设这个变量与催化剂颗粒表面的原位 In 原子浓度成正比，那么 InP 纳米线中 SF 的形成就不能简单归因于液滴过饱和度。在与 NWs 中较大 SF 密度相关的生长条件下，检测到了这种浓度与轴向生长速率之间的不平衡，这表明在这种情况下，在三相线处的前体掺入有不同的途径。通过在生长过程中改变 In 的供应，可以进一步增强 SF 的形成，并且在相同条件下生长的小直径 NWs 中会抑制 SF 的形成。我们将观察到的行为归因于半导体/金属界面的动力学粗化。三相线的变形增加了生长界面处发生相变的可能性，以达到系统界面和表面能的局部最小值。
