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，如光化学、气体传感器和建筑玻璃涂层。这些应用要求薄氧化物膜掺杂少量不同的化学元素，以提高膜的导电性而不改变其结构。例如，氟掺杂的氧化锡被用作光伏电池和气体传感器中玻璃上的导电涂层。当氧化锡与等量的氧化钡结合时，形成一种称为锡酸钡的陶瓷化合物。它具有更复杂的结构，称为钙钛矿，其性能非常依赖于薄膜的完美性。对锡酸钡的初步实验显示出显著的导电性，这可以使基于金属氧化物的新型微电子学的发展成为可能。沉积没有缺陷的具有精确元素比率的膜是困难的。本研究探讨了高品质氧化锡及锡酸钡薄膜沉积的基本控制因素。这种实验和计算相结合的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所涉及的事件。技术描述：通过实验和理论/计算技术的结合，研究人员正在确定原子和分子水平上影响晶体生长速率和质量的基本因素，二元和三元氧化锡。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，一个单独的化学计量学方法提供了一个潜在的强大的工具，用于快速的替代前体的计算机模拟筛选，其目标是优先考虑实验，以专注于具有高实用性的可能性的分子前体。最初的一组六种锡前体，包括金属烷基化物、氨化物和硝酸盐，被用于在真空反应器中沉积存款氧化锡。生长速率，原位测量通过使用随时间变化的强度振荡的反射高能电子衍射峰，研究作为衬底温度，前体和氧气压力的函数，旨在阐明沉积动力学被用作设计沉积的基础上具有钙钛矿结构的三元锡氧化物。在这些沉积中，分子前体被用作锡源，并且泻流单元被用作第二族元素的源，其最终目标是理解导致自调节化学计量控制的化学前体的基本设计原理。

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.