Exploration of Non-Equilibrium Interfacial Phenomena in Spin Forbidden Oxidation

自旋禁阻氧化中非平衡界面现象的探索

• 批准号: 1900109
• 负责人: Sylvia Ceyer
• 金额: $ 50万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-01 至 2023-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1900109&HistoricalAwards=false
• 关键词: Exploration; Non; Equilibrium; Interfacial; Phenomena

Modern computer chips are made from semiconductors, such as silicon, coated with an extremely thin layer of silicon-oxide. To fabricate reliable electronic components, the thickness of this oxide layer must be precisely controlled, which presents significant challenges as devices become smaller and smaller. Present methods of creating the silicon-oxide film require heating the semiconductor at high temperature. This process leads to a non-uniform oxide layer. In this project, funded by the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) program of the Chemistry Division, Professor Sylvia T. Ceyer of the Massachusetts Institute of Technology and her students are using sophisticated molecular beam techniques to study the oxide formation process. Their discoveries could lead to improved methods using lower temperatures, which would have significant societal and economic benefit. This research is also providing a broad-based education in scientific problem solving for students embarking on careers in chemical industry. Professor Ceyer leverages MIT?s Summer Research Program (MSRP) to recruit underrepresented undergraduate students for summer research engaging them in the excitement of scientific discovery. Professor Ceyer also authors and narrates compelling general chemistry lectures on YouTube as a part of educational and outreach activities designed to make science understandable and accessible for all. This work proposes a novel method using (O2)2 dimer to easily synthesize O2 in its first electronically excited singlet state with the aim of bypassing a spin-forbidden reaction that limits oxidation activity of semiconductors. This idea may lead to precise control of ever-thinner oxide layers in devices. The comparison between the experimentally-determined interaction dynamics of O2 versus (O2)2 are providing insights into the origin of the low, but non-zero probability of this spin forbidden reaction. This research program also explores a non-equilibrium phenomenon involving lattice electronic excitations due to the initial collision of the incident O2 in the quest for understanding the non-zero O2 reactivity. Finally, these experiments test a hypothesis that an alternate mechanism for dissociative chemisorption, atom abstraction, which does not require a spin forbidden transition, may be operative via a metastable, non-equilibrium precursor state or a direct atom abstraction associated with a transient potential energy maximum.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

现代计算机芯片是由半导体制成的，比如硅，表面覆盖着一层非常薄的硅氧化物。为了制造可靠的电子元件，必须精确控制氧化层的厚度，随着器件变得越来越小，这带来了巨大的挑战。目前制造氧化硅薄膜的方法需要在高温下加热半导体。这一过程导致了不均匀的氧化层。在这项由化学系化学结构、动力学和机理A(CSDM-A)计划资助的项目中，麻省理工学院的西尔维娅·T·塞耶教授和她的学生正在使用复杂的分子束技术来研究氧化物的形成过程。他们的发现可能导致使用较低温度的改进方法，这将具有显著的社会和经济效益。这项研究还为从事化学工业职业的学生提供了科学解决问题的广泛教育。塞耶教授利用麻省理工学院S暑期研究计划(MSRP)招收未被充分代表的本科生进行暑期研究，让他们参与科学发现的兴奋。Ceyer教授还在YouTube上撰写并讲述了引人注目的普通化学讲座，这是旨在使所有人都能理解和接触科学的教育和推广活动的一部分。这项工作提出了一种新的方法，利用(O2)2二聚体容易地合成处于第一电子激发单重态的O2，目的是绕过限制半导体氧化活性的自旋禁止反应。这一想法可能会导致对设备中越来越薄的氧化层的精确控制。实验确定的O2和(O2)2相互作用动力学之间的比较为这种自旋禁止反应的低但非零几率的起源提供了洞察力。这个研究项目还探索了一种非平衡现象，涉及由于入射O2的初始碰撞而引起的晶格电子激发，以寻求理解非零O2反应性。最后，这些实验测试了一种假设，即另一种解离化学吸附的替代机制-原子抽象，它不需要自旋禁忌跃迁，可以通过亚稳态、非平衡前驱状态或与瞬时势能极大相关的直接原子抽象来操作。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。