CAREER: Molecular Perspectives of Gas-Surface Reactions during Growth of Thin Film Nanostructures

0846923阿加瓦尔该奖项是根据2009年美国复苏和再投资法案(公法111-5)资助的。智力价值：这项职业计划整合了气体表面动力学主题领域的研究和教育活动，这对纳米尺度的薄膜生长控制至关重要。该研究项目的目标与科罗拉多矿业学院保持一致？(CSM)专注于地球资源、能源和先进材料。特别是，这项研究将集中在原子和分子层沉积(ALD/MLD)。这些沉积技术在自限、气-固表面反应的交替循环中运行。最近，由于能够在大面积衬底上提供共形薄膜，并对薄膜的成分和厚度进行纳米级控制，激光二极管已被广泛应用。到目前为止，ALD工艺的发展在很大程度上是经验的，除了少数金属氧化物外，很少有全面的研究。虽然ALD主要局限于无机材料，但MLD是一种新兴的沉积有机薄膜的技术。有必要从分子上了解ALD/MLD过程中出现的非均相化学，以便它们可以最大限度地发挥其潜力。这两种工艺的内在兼容性可用于形成先进的无机-有机杂化薄膜。在这个研究和教育项目中，将用基础科学的方法研究ALD/MLD过程。结合了最先进的表面和气相诊断技术，包括原位表面红外光谱、X射线光电子能谱、石英晶体微天平、椭圆偏振光谱和四极杆质谱仪。这种方法的强大能力被证明是通过皮耶？S最近的研究二氧化钛使用臭氧的ALD。本项目将阐明ALD/MLD合成金属氧化物、功能聚合物和先进金属薄膜的关键分子途径。有关金属氧化物的工作将集中在臭氧和氧自由基的应用上，这两种自由基尽管成为工业过程中的首选氧化剂，但几乎没有受到关注。MLD研究将探索两种新策略，以克服有机薄膜合成面临的关键限制：(A)不产生反应副产物的过程化学；(B)智能组装，其中初始试剂产生掩蔽的功能，并使用第二种试剂选择性地激活。金属的研究将集中在成核的关键问题上，以Ru为模型化合物。PI将进一步整合这三个领域的见解，设计用于在预功能化表面上高密度成核的超薄金属薄膜的分子支架。转变方面：这项研究可能是潜在的转变，因为它将揭示在ALD/MLD过程中发生的分子转变，这最终将导致新的薄膜生长策略。此外，该程序将解决ALD中最不被理解的过程之一，即金属在不同表面上的初始形核。更广泛的影响：该项目的一个固有特点是强调教育及其与研究的结合。具体而言，将实现三个相互关联的教育目标：(A)开发和评估一门新的跨学科薄膜加工选修课；(B)通过研究提供密切的指导和职业咨询；(C)参与旨在增加本科阶段少数族裔学生招生和留住的外联方案。该项目还涉及与荷兰埃因霍温理工大学的研究生交换项目，该项目将为两所大学的学生提供智力和文化体验。该项目解决了材料科学的一个热门领域的基础研究问题，该领域在微电子、光电子学和光伏等多个领域具有高度的技术相关性。这项研究的独特之处在于，它结合了各种最先进的表面和气相诊断技术，以研究通过ALD和MLD沉积薄膜和纳米层状物过程中的气体表面动力学。通用的方法和诊断工具将帮助PI建立一个更广泛的计划，以研究其他薄膜沉积过程中的界面现象，如等离子体增强CVD。这项研究的多学科性质包括物理、化学、工程和材料科学。除了开发新的课程外，这项工作的几个方面将用于加强CSM现有的光伏、等离子体科学和微制造课程。

0846923Agarwal This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Intellectual Merit: This CAREER proposal integrates research and educational activities in the thematic area of gas-surface dynamics critical to nanoscale control of thin-film growth. The goals of the research program are aligned with the Colorado School of Mines? (CSM) focus on Earth resources, energy, and advanced materials. In particular, the study will concentrate on atomic and molecular layer deposition (ALD/MLD). These deposition techniques operate in alternating cycles of self-limiting, gas-solid surface reactions. Recently, ALD has been used in numerous applications due to its ability to deliver conformal films on large-area substrates with nanometer-scale control over the film?s composition and thickness. To date ALD process development has been largely empirical, and with the exception of a few metal oxides, there have been very few comprehensive studies. While ALD is largely limited to inorganic materials, MLD is an emerging technique to deposit organic films. There is a need to develop a molecular understanding of the heterogeneous chemistry that occurs in ALD/MLD processes, so that they may be developed to their fullest potential. The inherent compatibility of the two processes can be utilized for the formation of advanced inorganic-organic hybrid films. In this research and education project, ALD/MLD processes will be examined taking a fundamental science approach. A combination of state-of-the-art surface and gas-phase diagnostics has been assembled that include in situ surface infrared spectroscopy, x-ray photoelectron spectroscopy, quartz crystal microbalance, spectroscopic ellipsometry, and quadrupole mass spectrometry. The powerful capabilities of this approach are demonstrated through the PI?s recent studies on the ALD of TiO2 using O3. This project will illuminate the molecular pathways critical to ALD/MLD synthesis of metal oxides, functional polymers, and advanced metal films. Work on metal oxides will focus on the application of O3 and O radicals, which have received little attention despite becoming the oxidizers of choice for industrial processes. MLD studies will investigate two novel strategies to overcome key limitations facing organic thin film synthesis: (a) process chemistries that produce no reaction byproducts, and (b) ?smart assembly?, in which the initial reagent produces a masked functionality that is selectively activated using a second reagent. Investigation of metals will focus on the key issue of nucleation, with ruthenium serving as the model compound. The PI will further integrate the insights from these three topical areas to design molecular scaffolds for high density nucleation of ultrathin metal films on pre-functionalized surfaces. Transformative Aspects: This study can be potentially transformative as it will reveal the molecular transformations occurring during ALD/MLD processes, which will ultimately lead to novel strategies for film growth. Furthermore, this program will address one of the least understood processes in ALD, which is the initial nucleation of metals on different surfaces. Broader Impact: An inherent feature of the project is the emphasis on education and its integration with research. Specifically, three interrelated educational goals will be pursued: (a) development and assessment of a new interdisciplinary elective course in thin-film processing; (b) close mentorship and career counseling through research; and (c) participation in outreach programs designed to increase minority student recruitment and retention at the undergraduate level. The project also involves a graduate student exchange program with the Eindhoven University of Technology in The Netherlands, which will facilitate a intellectual and cultural experience for students at both institutions. The project addresses fundamental research issues in a topical area of materials science having high technological relevance in a variety of fields such as microelectronics, optoelectronics, and photovoltaics. The study is unique in the sense that it brings together a variety of state-of-the-art surface and gas-phase diagnostics to investigate gas-surface dynamics during deposition of thin films and nanolaminates through ALD and MLD. The general methodology and diagnostic tools will assist the PI is setting up a broader program for studying interfacial phenomena in other thin-film deposition processes, such as plasma-enhanced CVD. The multidisciplinary nature of the research encompasses physics, chemistry, engineering, and materials science. Besides development of new courses, several aspects of this work will be used to enhance existing courses in photovoltaics, plasma science, and microfabrication at CSM.