Department of Physics, University of Warwick , Coventry CV4 7AL, United Kingdom.
Department of Electronic and Electrical Engineering, University College London , Torrington Place, London WC1E 7JE, United Kingdom.
Nano Lett. 2017 Apr 12;17(4):2454-2459. doi: 10.1021/acs.nanolett.7b00123. Epub 2017 Apr 3.
One of the main advantages of nanowires for functional applications is their high perfection, which results from surface image forces that act on line defects such as dislocations, rendering them unstable and driving them out of the crystal. Here we show that there is a class of step facets that are stable in nanowires, with no long-range strain field or dislocation character. In zinc-blende semiconductors, they take the form of Σ3 (112) facets with heights constrained to be a multiple of three {111} monolayers. Density functional theory calculations show that they act as nonradiative recombination centers and have deleterious effects on nanowire properties. We present experimental observations of these defects on twin boundaries and twins that terminate inside GaAsP nanowires and find that they are indeed always multiples of three monolayers in height. Strategies to use the three-monolayer rule during growth to prevent their formation are discussed.
纳米线在功能应用方面的主要优势之一是其高度的完美性，这是由于表面图像力作用于位错等线缺陷，使它们变得不稳定，并将它们逐出晶体。在这里，我们表明存在一类在纳米线中稳定的阶面，它们没有长程应变场或位错特征。在闪锌矿半导体中，它们采取Σ3(112)阶面的形式，高度受限于三个{111}单层的倍数。密度泛函理论计算表明，它们作为非辐射复合中心，对纳米线性质有有害影响。我们提出了在孪晶边界和终止于 GaAsP 纳米线内的孪晶上观察到这些缺陷的实验观察结果，并发现它们的高度确实总是三个单层的倍数。讨论了在生长过程中利用三层规则来防止它们形成的策略。
