表面反应的量子化学模型与金刚石生长的动力学模型：低温CVD中CH3自由基和C2H2分子的影响
Quantum Chemistry Model of Surface Reactions and Kinetic Model of Diamond Growth: Effects of CH3 Radicals and C2H2 Molecules at Low-Temperatures CVD
AI总结：
本文通过量子化学计算和详细动力学模型研究低温CVD金刚石生长，揭示CH3是主要生长前驱体而C2H2在低温下通过促进sp2相成核抑制生长，并提出优化反应器设计以最大化CH3、最小化C2H2的策略。
摘要：
本研究的目标是探索能够在金刚石生长过程中显著降低衬底温度的条件。该过程的典型温度约为1200K；我们旨在将其降低到远低于此的水平。为了实现这一目标，我们需要理解在低温下限制金刚石生长的过程。因此，我们建立了一个详细的化学动力学模型，用于分析(100)表面上的金刚石生长。该模型考虑了衬底温度和气体组成的变化。利用从头算量子化学方法，我们计算了所有主要气相反应物与金刚石表面的反应速率，共计91个基元表面反应。与先前研究一致，该模型确定CH3是金刚石生长的主要前驱体，而C2H2对生长的贡献显著较小。然而，C2H2也可能促成sp2相而非sp3相的形成，并且该过程在低于某一临界温度时占据主导地位。因此，C2H2通量在低温下抑制金刚石生长。为了定量描述这一有害过程，我们为(100)表面上的sp2相成核建立了一种新机制。与用于碳烟形成的所谓HACA机制类似，该机制涉及氢抽取和C2H2加成。因此，最优的低温CVD生长可以在一种反应器中实现，该反应器旨在最大化CH3自由基的生成，同时最小化C2H2以及其他sp和sp2烃类的产生。
英文摘要：
The objective of this study is to explore conditions that facilitate a significant reduction in substrate temperature during diamond growth. The typical temperature for this process is around 1200K; we aim to reduce it to a much lower level. To achieve this, we need to understand processes that limit the diamond growth at low temperatures. Therefore, we developed a detailed chemical kinetic model to analyze diamond growth on the (100) surface. This model accounts for variations in substrate temperature and gas composition. Using an ab initio quantum chemistry, we calculated the reaction rates of all major gas phase reactants with the diamond surface, totaling 91 elemental surface reactions. Consistent with previous studies, the model identifies that CH3 is a major precursor of diamond growth, and the contribution from C2H2 to the growth is significantly smaller. However, C2H2 can also contribute to forming a sp2-phase instead of a sp3-phase, and this process becomes dominant below a critical temperature. As a result, C2H2 flux inhibits diamond growth at low temperatures. To quantify this deleterious process, we developed a new mechanism for sp2-phase nucleation on the (100) surface. Similar to the so-called HACA mechanism for soot formation it involves hydrogen abstraction and C2H2 addition. Consequently, optimal low-temperature CVD growth could be realized in a reactor designed to maximize the CH3 radical production, while minimizing the generation of C2H2 and other sp and sp2 hydrocarbons.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
