Coherent X-ray Studies of Surface Growth and Patterning Processes

Trustees Of Boston University, Boston

Investigators

Abstract

Nontechnical description: Controlling the growth and nanometer-scale patterning of materials surfaces is critical to many applications in energy, communication and information technologies. However, a major impediment to developing more useful materials is the difficulty of measuring the evolution of surface structure during such processes. This research meets that challenge by using very intense x-rays to measure the nanometer-scale dynamics on surfaces during growth and patterning. These experiments are made possible by the use of the latest x-ray sources, which have been rapidly developing increasing brightness. The experimental measurements are compared with predictions of theory and computer simulations, leading to increased understanding and predictive power. Such knowledge can help scientists and engineers better control surface processes on materials, enhancing their technological capabilities. In addition, the project trains graduate, undergraduate and high school students in this very important and rapidly developing part of materials research, leading to future careers in materials innovation. Technical description: This research is developing x-ray photon correlation spectroscopy as a powerful new approach to investigating the nanoscale dynamics of surfaces during growth and ion beam patterning. Given the technique?s early stage of application to such challenging problems, it is important to examine the range of its capabilities. This project is therefore investigating a carefully chosen set of systems and behaviors. First, it is being used to carefully probe the fundamental processes in kinetic roughening during amorphous film growth, an issue of long-standing interest and controversy. Second, the applicability of the technique to investigating epitaxial growth processes is being examined within the context of vapor deposition of organic semiconductor films and plasma-assisted atomic layer epitaxial growth of III-V nitride epitaxial films. Finally, the dynamics of semiconductor ion beam nanopatterning, an issue generating unusually close interaction between experiment and theory, is being studied. In all cases, simulations of continuum and atomistic models are being performed to relate observations to underlying mechanisms. Graduate, undergraduate and high school students involved have an outstanding opportunity to work in an area that bridges basic research and application. Participating students learn a wide range of characterization and computational tools that can translate well to future careers in industry or academia.