Time-scale analysis for the synthesis of thin-film deposition reaction kinetics models

一些电子材料，如太阳能电池的光伏材料，是在专门的化学反应器中制造的，其中气相反应物分子沉积在表面上，形成产品材料的薄膜。分子从气相到薄膜的过程包含了一系列复杂的化学反应，为了生产出具有理想性能的材料，必须充分了解这些化学反应。为了从数学上描述薄膜生长的整个过程，可以推导出一个方程组来跟踪反应器内和生长薄膜表面的各种化学物质。该项目涉及开发分析方程组的新方法，并将分析结果与沉积过程（如原子层沉积（ALD）和化学气相沉积（CVD））的实验数据进行比较。该项目的结果将为科学家和工程师提供预测ALD和CVD反应器性能的新工具。该项目将为反应工程重要领域的研究生提供训练基地，并为感兴趣的本科生提供研究机会。在项目期间开发的软件将提供给研究和工业界。本项目将研究描述ALD和CVED薄膜沉积过程中表面反应种类的微分代数（DAE）方程组的数学结构。将开发一个反应网络分解程序，将表面反应和沉积物种动态平衡划分为相对缓慢（沉积），快速（平衡）和瞬时（守恒）模式。该项目将确定分解工作的条件，方程不动点的重要性以及化学物质的反应通量。将分析不同复杂程度的沉积过程示例，包括一些具有空间分布的沉积过程。将薄膜生长速率与反应器条件相关联的结果与实验数据进行比较。

1438375PI: Raymond AdomaitisInstitution: University of Maryland College ParkSome electronic materials, such as photovoltaic materials for solar cells, are manufactured in specialized chemical reactors in which gas-phase reactant molecules deposit on a surface to form a thin film of the product material. The routes that molecules take from the gas phase to the thin film involve a complex set of chemical reactions that must be well understood in order to produce materials with the desired properties. To describe mathematically the overall process of film growth, a system of equations can be derived to track the various chemical species inside the reactor and on the surface of the growing film. This project involves developing new methods for analyzing the system of equations, and comparing the results of the analysis with experimental data for deposition processes such as atomic layer deposition (ALD) and chemical vapor deposition (CVD). The results of the project will provide scientists and engineers with a new tool for predicting the performance of ALD and CVD reactors. The project will provide a training ground for graduate students in an important area of reaction engineering and will provide research opportunities for interested undergraduate students as well. Software that is developed during the project will be made available to the research and industrial communities.This project will investigate the mathematical structure of differential-algebraic (DAE) systems of equations describing surface reaction species during ALD and CVED thin film deposition processes. A reaction network factorization procedure will be developed that partitions surface reaction and deposition species dynamic balances into sets of relatively slow (deposition), fast (equilibrium), and instantaneous (conserved) modes. The project will determine conditions under which the factorization works, the importance of fixed points of the equations, and reaction fluxes of chemical species. Example deposition processes of varying complexity will be analyzed, including some with spatially distributed deposition. Results that correlate rates of film growth with reactor conditions will be compared with experimental data.