Surface Nanopatterning by Ion Bombardment

技术描述：离子工艺在各种薄膜生长、表面蚀刻和表面改性工艺中发挥着至关重要的作用。深入了解离子轰击期间表面演变的一个主要障碍是难以定量研究纳米级形态演变的动力学。该项目使用国家同步加速器光源开发的用于原位X射线表面研究的独特设施来应对挑战。原位掠入射小角度X射线散射（GISAXS）研究测量依赖于波数的线性响应，控制离子轰击表面的基本稳定性/不稳定性。该项目采取综合办法，从沿着三个方向解决离子-表面相互作用的突出问题。首先，本机半导体表面的稳定性/不稳定性的离子轰击进行了系统的研究，以测试现有的理论，并提供其进一步发展的见解。应力发展及其与表面形态演变的关系是一个特别关注的问题。第二，非线性表面演化和最终的稳态表面形态的动力学检查使用传统的实时X射线散射和X射线光子相关光谱，分别。后一种技术使用小的X射线束，在其宽度上部分相干，超越了传统的动力学研究。最后，播种的影响进行了系统的研究，以解决在驱动纳米结构development.Non-technical Description：一个基本的了解离子轰击过程中的表面演变是一个“使重点”，因为超热轰击是如此无处不在的表面和薄膜生长过程中的相对重要性的应力和相分离。因此，该研究项目的结果可能会影响广泛的沉积和表面改性技术。此外，连贯的GISAXS研究的发展，调查在这个项目中设想的表面动力学将是一个强大的工具，在表面生长/改性社区的广泛的潜在应用。研究生，本科生和高中学生参加这个研究项目有机会在一个桥梁基础研究和应用领域的工作。除了体验和贡献，在当前材料研究的一个重要课题，他们学会使用各种表征工具。学生与波士顿大学不断发展的材料研究社区互动，研究生也有很好的机会参与多学科同步加速器研究环境。

Technical Description: Ion-based processes play a vital role in a wide range of thin-film growth, surface etching and surface modification processes. A major impediment to developing a robust understanding of surface evolution during ion bombardment has been the difficulty of quantitatively examining the kinetics of nanoscale morphology evolution. This project meets the challenge using a unique facility for in-situ x-ray surface studies developed at the National Synchrotron Light Source. In-situ grazing-incidence small-angle x-ray scattering (GISAXS) studies measure the wavenumber-dependent linear response governing the fundamental stability/instability of a surface to ion bombardment. The project pursues an integrated approach to resolve outstanding problems of ion-surface interaction along three directions. First, systematic studies of native semiconductor surface stability/instability to ion bombardment are carried out to test existing theory and provide insights for its further development. Stress development and its relationship to surface morphology evolution is an issue of particular focus. Second, nonlinear surface evolution and dynamics of the final steady-state surface morphology is examined using conventional real-time x-ray scattering and x-ray photon correlation spectroscopy, respectively. The latter technique uses a small x-ray beam, partially coherent across its width, to go beyond traditional kinetics studies. Finally, the effects of seeding are systematically examined to resolve the relative importance of stress and phase separation in driving nanostructure development.Non-technical Description: A fundamental understanding of surface evolution during ion bombardment is an "enabling focus" because hyperthermal bombardment is so ubiquitous in surface and thin-film growth processes. Results from this research project could thus potentially impact a wide range of deposition and surface modification techniques. Moreover, the development of coherent GISAXS studies to investigate surface dynamics envisioned in this project would be a powerful tool with a broad range of potential applications in the surface growth/modification community. Graduate, undergraduate and high-school students participating in this research project have an opportunity to work in an area that bridges basic research and application. In addition to experiencing, and contributing to, an important topic in current materials research, they learn to use a wide range of characterization tools. Students interact with a growing materials research community at Boston University and the graduate student also have an excellent opportunity to participate in the multi-disciplinary synchrotron research environment.