Albani Marco, Bergamaschini Roberto, Barzaghi Andrea, Salvalaglio Marco, Valente Joao, Paul Douglas J, Voigt Axel, Isella Giovanni, Montalenti Francesco
L-NESS and Department of Materials Science, University of Milano - Bicocca, 20125, Milan, Italy.
L-NESS and Dipartimento di Fisica, Politecnico di Milano, 22100, Como, Italy.
Sci Rep. 2021 Sep 22;11(1):18825. doi: 10.1038/s41598-021-98285-1.
The development of three-dimensional architectures in semiconductor technology is paving the way to new device concepts for various applications, from quantum computing to single photon avalanche detectors. In most cases, such structures are achievable only under far-from-equilibrium growth conditions. Controlling the shape and morphology of the growing structures, to meet the strict requirements for an application, is far more complex than in close-to-equilibrium cases. The development of predictive simulation tools can be essential to guide the experiments. A versatile phase-field model for kinetic crystal growth is presented and applied to the prototypical case of Ge/Si vertical microcrystals grown on deeply patterned Si substrates. These structures, under development for innovative optoelectronic applications, are characterized by a complex three-dimensional set of facets essentially driven by facet competition. First, the parameters describing the kinetics on the surface of Si and Ge are fitted on a small set of experimental results. To this goal, Si vertical microcrystals have been grown, while for Ge the fitting parameters have been obtained from data from the literature. Once calibrated, the predictive capabilities of the model are demonstrated and exploited for investigating new pattern geometries and crystal morphologies, offering a guideline for the design of new 3D heterostructures. The reported methodology is intended to be a general approach for investigating faceted growth under far-from-equilibrium conditions.
半导体技术中三维架构的发展正在为从量子计算到单光子雪崩探测器等各种应用的新器件概念铺平道路。在大多数情况下，此类结构只有在远离平衡的生长条件下才能实现。要控制生长结构的形状和形态以满足应用的严格要求，远比在接近平衡的情况下复杂得多。开发预测性模拟工具对于指导实验可能至关重要。本文提出了一种用于动力学晶体生长的通用相场模型，并将其应用于在深度图案化的硅衬底上生长的锗/硅垂直微晶的典型案例。这些正在开发用于创新光电子应用的结构，其特征在于一组复杂的三维小面，主要由小面竞争驱动。首先，根据一小部分实验结果拟合描述硅和锗表面动力学的参数。为此，生长了硅垂直微晶，而对于锗，拟合参数则从文献数据中获得。一旦校准，就展示并利用该模型的预测能力来研究新的图案几何形状和晶体形态，为新型三维异质结构的设计提供指导。所报道的方法旨在成为研究远离平衡条件下小面生长的通用方法。
