Volmer–Weber生长机理形成的外延量子点的演化,Crystal Growth & Design

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Volmer–Weber生长机理形成的外延量子点的演化
Crystal Growth & Design ( IF 3.2 ) Pub Date : 2019-11-21 , DOI: 10.1021/acs.cgd.9b00820
Kirill A. Lozovoy ₁ , Andrey P. Kokhanenko ₁ , Vladimir V. Dirko ₁ , Nataliya Yu. Akimenko ₂ , Alexander V. Voitsekhovskii ₁

Affiliation

锗/硅系统是当前半导体电子和光子学发展最有前途的材料之一。从创建快速晶体管，光电探测器和太阳能电池的角度来看，在硅上具有锗量子点的结构非常有趣。合成纳米岛的基本方法是它们在分子束外延过程中的自组织。实验表明，超高表面密度（高达10 ¹² –10 ¹³ cm ^–2可以通过在氧化的而不是裸露的硅表面上沉积锗来实现纳米级的团簇。然而，对具有氧化硅薄层的系统的研究很少。在这项工作中，考虑了通过Volmer-Weber生长机制进行外延形成和量子点生长的基本特性。首次提出了基于一般成核理论的Volmer–Weber机理对三维岛形核和生长的动力学模型。开发的模型不仅可以评估具有量子点的系统的平衡值（其平均大小和表面密度），而且还可以评估主要的非平衡参数，例如岛形核率，尺寸分布函数及其时间演化。获得了Volmer–Weber量子点的平均横向尺寸和表面密度与其合成条件（生长温度和沉积速率）的相关性。Ge / SiO的Volmer–Weber生长的数值模拟结果₂ / Si系统与实验数据显示出很好的一致性。所提出的理论模型可能很容易应用于通过Volmer–Weber机理实现了小岛增长的其他材料系统。

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Evolution of Epitaxial Quantum Dots Formed by Volmer–Weber Growth Mechanism

Germanium/silicon systems are among the most promising materials for development of current semiconductor electronics and photonics. Structures with germanium quantum dots on silicon are very interesting from the point of view of the creation of fast-speed transistors, photodetectors, and solar cells. The basic method of the synthesis of nanoislands is their self-organization in the process of molecular beam epitaxy. It was experimentally shown that ultrahigh surface densities (up to 10¹²–10¹³ cm^–2) of nanometer-sized clusters may be achieved by deposition of germanium on oxidized rather than bare silicon surfaces. Nevertheless, this system with a thin layer of silicon oxide is poorly investigated. In this work, fundamental peculiarities of epitaxial formation and growth of quantum dots by the Volmer–Weber growth mechanism are considered. A kinetic model of nucleation and growth of three-dimensional islands by the Volmer–Weber mechanism based on the general nucleation theory is proposed for the first time. The developed model allows one to evaluate not only equilibrium values of a system with quantum dots (their average size and surface density), but also principally nonequilibrium parameters such as islands nucleation rate, size distribution function, and its time evolution. Dependencies of mean lateral size and surface density of Volmer–Weber quantum dots on the conditions of their synthesis (growth temperature and deposition rate) are obtained. The results of numerical simulations of Volmer–Weber growth for the Ge/SiO₂/Si system show very good agreement with experimental data. The proposed theoretical model may be easily applied for other material systems where growth of islands by the Volmer–Weber mechanism is realized.

更新日期：2019-11-22

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