Design Principles for the Growth of High-quality Binary and Ternary Tin Oxides

非技术描述：金属氧化物在许多关键应用中发挥着重要作用，如光伏、气体传感器和建筑玻璃涂层。这些应用需要在氧化薄膜中掺杂少量不同的化学元素，以提高薄膜的导电性而不改变其结构。例如，氟掺杂氧化锡被用作光电电池和气体传感器玻璃上的导电涂层。当氧化锡与等量的氧化钡结合时，就会形成一种称为锡酸钡的陶瓷化合物。它有一个更复杂的结构，被称为钙钛矿，它的性能非常依赖于薄膜的完美性。锡酸钡的初步实验表明，它具有卓越的导电性，可以开发一种基于金属氧化物的新型微电子器件。沉积具有精确元素比且无缺陷的薄膜是困难的。本文研究了控制高质量氧化锡和锡酸钡薄膜沉积的基本因素。这种结合实验和计算研究的一个重要的更广泛的影响是制作视频，可以用来向学生和公众解释沉积过程中涉及的事件。技术描述：通过实验和理论/计算技术的结合，研究人员正在确定影响二元和三元锡氧化物晶体生长速率和质量的原子和分子水平的基本因素。从这项工作中获得的机械知识有助于设计新的分子前体和沉积过程。此外，一种单独的化学计量学方法提供了一种潜在的强大工具，用于快速筛选替代前体，其目标是优先考虑实验，专注于具有高效用可能性的分子前体。一组最初的六种锡前体，包括金属烷基、酰胺和硝酸盐，正被用于在超高真空反应器中沉积锡氧化物。利用反射高能电子衍射峰中随时间变化的强度振荡原位测量生长速率，研究了生长速率与衬底温度、前驱体和氧压的关系，旨在阐明沉积动力学，为设计具有钙钛矿结构的三元氧化锡沉积奠定基础。在这些沉积中，分子前体被用作锡源，积液细胞被用作两族元素的来源，最终目的是了解导致自我调节化学计量控制的化学前体的潜在设计原则。

Non-technical Description: Metal oxides play important roles in many critical applications such as photovoltaics, gas sensors and coatings for architectural glass. These applications require that thin oxide films be doped with small amounts of a different chemical element that improves the electrical conductivity of the film without changing its structure. For example, fluorine-doped tin oxide is used as an electrically conductive coating on glass in photovoltaic cells and in gas sensors. When tin oxide combines with an equal amount of barium oxide, a ceramic compound known as barium stannate forms. It has a more complex structure known as a perovskite, and its properties are extremely dependent on the perfection of the film. Initial experiments on barium stannate demonstrate remarkable electrical conductivities that can enable the development of a new class of microelectronics based on metal oxides. Depositing films with exact elemental ratios that are free of defects is difficult. This research studies the fundamental factors controlling the deposition of high quality tin oxide and barium stannate films. An important broader impact of this combined experimental and computational research is the production of videos that can be used to explain to students and the general public the events involved in the deposition processes.Technical Description: Through a combination of experimental and theoretical/computational techniques, the researchers are identifying fundamental factors at the atomic and molecular level of detail that influence the rates and quality of crystal growth in binary and ternary tin oxides. Mechanistic knowledge gained from this work is aiding in the design of new molecular precursors and deposition processes. In addition, a separate chemometric approach offers a potentially powerful tool for rapid in-silico screening of alternative precursors with the goal of prioritizing experiments to focus on molecular precursors having a high likelihood of utility. An initial group of six tin precursors, including metal alkyls, amides and nitrates, is being used to deposit tin oxides in an ultrahigh vacuum reactor. Growth rates, measured in situ by using time-dependent intensity oscillations in the reflection high energy electron diffraction peaks, are studied as a function of substrate temperature, precursor and oxygen pressure, aiming to elucidate the deposition kinetics to be used as the basis for designing depositions of ternary tin oxides having the perovskite structure. In these depositions, molecular precursors are used as the tin source and effusion cells are used as sources for the group-two elements with the ultimate goal to understand the underlying design principles for chemical precursors that lead to self-regulating stoichiometry control.