RUI: Radiation selectivity of photo-induced structural transformations in covalently bonded glassy thin films

非技术描述：硫系玻璃薄膜由于其多功能和独特的性质，在红外光子学、非线性光学、全光计算、微(纳米)光刻和相变存储器件中是非常有前途的新兴应用材料。这些材料是特殊的，因为它们对光或粒子(电子、中子、离子)的暴露具有多级敏感性；这种敏感性取决于辐射源的强度和能量。光处理也可以用来加速非晶态薄膜的结构弛豫，稳定它们的性能，以供进一步应用。然而，为了控制光(或光)诱导效应和预测曝光材料的行为，需要更好地了解不同光能和强度下薄膜表面和内部的光结构转变机制。该项目的目标是利用先进的实验方法，发展对光结构转变的新的理解水平，并建立一种有效的方法来稳定不同方法制备的硫系玻璃薄膜的结构弛豫。本科生研究是该项目的重要组成部分，为学生提供接触先进实验设备的机会，并激励他们考虑进入科学或工程领域。技术细节：正在研究的技术细节：As-S(金字塔)和Ge-S(Se)(四面体)二元硫系玻璃薄膜，在广泛的成分范围内，在真空中热沉积，以及从溶液中旋转涂层。热沉积薄膜以其高光敏性和大量的同极键而闻名，即使是化学计量比的成分也是如此。同时，旋涂薄膜的光稳定性较好，其结构接近于体相。该项目的计划成果是一幅原子图，展示了用这两种不同方法获得的金字塔和四面体硫化物玻璃薄膜对光曝光的结构响应及其对光子能量和通量的依赖。用拉曼显微镜、高分辨X射线光电子能谱、扫描电子显微镜、透射电子显微镜、原子力显微镜、光学光谱、X射线吸收和中子散射等方法研究了光结构转变的机理。该项目的成果有可能推动硫系玻璃薄膜在新兴领域的应用取得重大进展，如光子学、存储设备和微/纳米光刻。此外，该项目的主要目标之一是开发全国认可的实验和计算玻璃科学本科生研究培训计划。

NON-TECHNICAL DESCRIPTION: Chalcogenide glass thin films, due to their multifunctionality and unique properties, are remarkably promising materials for emerging applications in infrared photonics, non-linear optics, all-optical computing, micro(nano)-lithography, and phase-change memory devices. These materials are exceptional because of their multilevel sensitivity to exposure by light or particles (electrons, neutrons, ions); this sensitivity depends on the intensity and energy of the radiation source. Light treatment can also be used to accelerate structural relaxation in amorphous films, stabilizing their properties for further applications. However, to control the photo-(or light-)induced effects and predict behavior of the exposed material, the mechanisms of photostructural transformation on the surface and inside of the films at different light energies and intensities needs to be better understood. The goal of this project is to develop, using advanced experimental methods, a new level of understanding of the photostructural transformations and establish an efficient way to stabilize the structural relaxation of chalcogenide glass thin films prepared by different methods. Undergraduate research is an essential part of the project, providing students access to the advanced experimental facilities and inspiring them to consider a career in science or engineering.TECHNICAL DETAILS: As-S(Se) (pyramidal) and Ge-S(Se) (tetrahedral) binary chalcogenide glass thin films, within a wide compositional domain, thermally deposited in vacuum as well as spin-coated from solution are being studied. The thermally-deposited films are known for their high photosensitivity and a large concentration of homopolar bonds, even for stoichiometric compositions. While, the spin-coated films are relatively photo-stable with structure close to the bulk analogue. The project's planned outcome is an atomistic picture of the structural response to photoexposure and its dependence on photon energy and fluence for pyramidal and tetrahedral chalcogenide glass thin films obtained with the two different methods. The mechanisms of photostructural transformations are studied with Raman microscopy, high-resolution X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, optical spectroscopy, X-ray absorption and neutron scattering methods. The project's results have the potential to stimulate major progress in application of chalcogenide glass thin films in emerging fields such as photonics, memory devices, and micro/nanolithography. As well, one of the main objectives of the project is the development of a nationally recognizable undergraduate research training program in experimental and computational glass science.