Concurrent Characterization of Surface Diffusion and Intermixing of Ge on Si: A Classical Molecular Dynamics Study,Advanced Theory and Simulations

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Concurrent Characterization of Surface Diffusion and Intermixing of Ge on Si: A Classical Molecular Dynamics Study
Advanced Theory and Simulations ( IF 2.9 ) Pub Date : 2023-03-16 , DOI: 10.1002/adts.202200848
Luis Martín‐Encinar ₁ , Luis Alberto Marqués ₁ , Iván Santos ₁ , Pedro López ₁ , Lourdes Pelaz ₁

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The surface diffusion and intermixing of Ge ad-atoms over Si (001) 2 × 1 substrates using classical molecular dynamics (CMD) simulations are characterized here. Several interatomic potentials, parametrizations, and parameter mixing rules are contemplated. A novel simulation scheme is devised to characterize the effective frequency of surface diffusion and intermixing events overcoming the inherent difficulties related to their interdependency in heteroepitaxial systems. The effective energy barriers of these events encompass different atomistic mechanisms weighted by their occurrence probabilities. The overall description of surface diffusion and intermixing based on Stillinger–Weber (SW) potential is in agreement with ab initio calculations and experimental observations, though some atomistic details differ. This study is extended to Si(001) substrates with stressed Ge monolayers grown on top. It is found that Ge ad-atom dynamics is accelerated with respect to the case of the pure Si substrate and that diffusion across dimer rows is mainly mediated by the atomic exchange of the Ge ad-atom with a Ge atom on the surface.

中文翻译：

Ge 在 Si 上的表面扩散和混合的同时表征：经典分子动力学研究

使用经典分子动力学 (CMD) 模拟，Ge 吸附原子在 Si (001) 2 × 1 基板上的表面扩散和混合在此进行了表征。设想了几种原子间势、参数化和参数混合规则。设计了一种新颖的模拟方案来表征表面扩散和混合事件的有效频率，克服了与其在异质外延系统中的相互依赖性相关的固有困难。这些事件的有效能垒包括由其发生概率加权的不同原子机制。基于 Stillinger-Weber (SW) 势的表面扩散和混合的总体描述与从头计算和实验观察一致，尽管一些原子细节不同。这项研究扩展到 Si(001) 衬底，上面生长有应力 Ge 单层。发现相对于纯 Si 衬底的情况，Ge ad 原子动力学加速，并且二聚体行的扩散主要由 Ge ad 原子与表面上的 Ge 原子的原子交换介导。

更新日期：2023-03-16

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