Atom-Resolved Dynamical Study of the Role of Hydrogen in Low Temperature Materials Growth and Processing

本项目重点研究入射和吸附H原子在化学气相沉积（CVD）低温电子材料生长中的原子解析动力学作用。该方法是通过使用扫描隧道显微镜（STM）进行广泛的原子分辨动力学测量来解决H原子的复杂行为。最初的研究将检查由气相生长前体如二硅烷与Si（100）表面的解离反应产生的分子SiHX片段的行为。将实时跟踪这些物质的扩散和/或分解，以确定邻近空位（悬空键）位点的作用。这些研究将在模拟真实低温生长环境的大部分钝化条件下进行。空位将在受控条件下被有意地产生，在这种条件下，空位可以被诱导与分子碎片发生碰撞。将直接测量扩散和分解的速率和能量障碍，以及入射h原子对这些过程的影响。对Si（100）表面H2解吸的详细机理也将进行实时探索。这些测量将在h原子和解吸的悬垂键产物是可移动的表面物质的温度下进行。特别注意的是缺陷和表面步骤在解吸过程中的作用。使用离子束，将产生受控缺陷密度，以确定它们对表面扩散、复合和H2脱附的影响。离子诱导H2或h原子去除的作用也将被研究，并与热激活的脱附机制进行比较。利用这种方法，对h原子动力学和Si生长的基本理解有望建立起来，这有助于为先进低温材料的受控生长奠定基础。该项目涉及具有高潜在技术相关性的材料科学主题领域的基础研究问题。该研究将为电子/光子器件的新领域提供基础材料科学知识。现在有了实验工具，可以在原子水平上观察基本的表面过程，这些过程一旦得到更好的理解，就会促进基础科学和技术的进步。从研究中获得的基本知识和理解预计将有助于提高先进器件和电路的性能和稳定性，为设计和生产改进的材料和材料组合提供基本的理解和基础。该计划的一个重要特点是通过在基础和技术重要领域培养学生，将研究和教育相结合

9812416BolandThis project focuses on atom-resolved dynamical studies of the role of incident and adsorbed H atoms in the growth of low-temperature electronic materials by chemical vapor deposition (CVD). The approach is to address the complex behavior of H atoms by performing a wide range of atom-resolved dynamical measurements using scanning tunneling microscopy (STM). Initial studies will examine the behavior of molecular SiHX fragments produced by dissociative reaction of gas phase growth precursors such as disilane with a Si(100) surface. The diffusion and/or decomposition of these species in real-time will be followed to determine the role of neighboring vacancy (dangling bond) sites. The studies will be performed under largely passivated conditions that mimic real low-temperature growth environments. Vacancy sites will be deliberately generated under controlled conditions where they can be induced to collide with the molecular fragments. The rates and energy barriers to diffusion and decomposition will be directly measured, as will the influence of incident H-atoms on these processes. The detailed mechanism of H2 desorption from the Si(100) surface will also be probed in real-time. These measurements will be performed at temperatures where H-atoms, and hence the dangling-bond products of desorption, are mobile surface species. Particular attention will be paid to the role of defects and surface steps in the desorption process. Using an ion-beam, controlled defect densities will be generated to determine their impact on surface diffusion, recombination and H2 desorption. The role of ion-induced H2 or H-atom removal will also be investigated and compared with the thermally activated desorption mechanism. Using this approach a fundamental understanding of H-atom dynamics and Si growth is expected to be established helping to form the basis for controlled growth of advanced low-temperature materials.%%%The project addresses basic research issues in a topical area of materials science having high potential technological relevance. The research will contribute basic materials science knowledge at a fundamental level to new aspects of electronic/photonic devices. Experimental tools are now available to allow atomic level observation of elementary surface processes which when better understood allow advances in fundamental science and technology. The basic knowledge and understanding gained from the research is expected to contribute to improving the performance and stability of advanced devices and circuits by providing a fundamental understanding and a basis for designing and producing improved materials, and materials combinations. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area.***