标题： 表面反应的量子化学模型和金刚石生长的动力学模型：低温度CVD中CH3自由基和C2H2分子的影响 显示英文标题

标题： Quantum Chemistry Model of Surface Reactions and Kinetic Model of Diamond Growth: Effects of CH3 Radicals and C2H2 Molecules at Low-Temperatures CVD

摘要： 本研究的目的是探讨在金刚石生长过程中促进基底温度显著降低的条件。 这一过程的典型温度约为1200K；我们的目标是将其降低到一个更低的水平。 为了实现这一点，我们需要了解在低温下限制金刚石生长的过程。 因此，我们开发了一个详细的化学动力学模型来分析(100)表面上的金刚石生长。 该模型考虑了基底温度和气体组成的差异。 使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，总计91种基本表面反应。 与之前的研究一致，该模型确认 CH3是金刚石生长的主要前体，而C2H2对生长的贡献要小得多。 然而，C2H2也可以参与形成sp2相而不是sp3相，且这一过程在临界温度以下占主导地位。 因此，C2H2通量在低温下会抑制金刚石的生长。 为了量化这一有害过程，我们开发了一种新的sp2相在(100)表面上成核的机制。 类似于所谓的烟尘形成HACA机制，它涉及氢原子的抽取和C2H2的添加。 因此，可以通过设计一个最大化CH3自由基生成同时最小化C2H2和其他sp和sp2烃类生成的反应器，实现最优的低温CVD生长。 显示英文摘要

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.