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。这些应用要求在氧化物薄膜中掺入少量不同的化学元素，以在不改变其结构的情况下提高薄膜的导电性。例如，掺氟的氧化锡被用作光伏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，就形成了一种被称为锡酸钡的陶瓷化合物。它有一种更复杂的结构，称为钙钛矿，它的性能极大地依赖于薄膜的完好性。对锡酸钡的初步实验表明，显著的导电性可以使基于金属氧化物的新型微电子技术的发展成为可能。沉积没有缺陷的精确的元素比例的薄膜是困难的。本研究研究了控制高质量氧化锡和锡酸钡薄膜沉积的基本因素。这项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了视频，可以用来向学生和普通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，研究人员正在原子和分子细节水平上确定影响二元和三元锡氧化物晶体生长速度和质量的基本因素。从这项工作中获得的机理知识有助于设计新的分子前驱体和沉积过程。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，用于快速在计算机中筛选替代前体，目的是优先进行实验，重点关注具有很高实用可能性的分子前体。首批六种锡前驱体，包括金属烷基、酰胺和硝酸盐，正被用来在超高真空反应堆中沉积锡氧化物。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了生长速率，研究了衬底温度、前驱体和氧气压力对生长速率的影响，旨在阐明沉积动力学，为设计具有钙钛矿结构的三元锡氧化物沉积提供依据。在这些证词中，分子前体被用作锡源，渗出细胞被用作第二族元素的来源，最终目的是了解导致自我调节化学计量比控制的化学前体的基本设计原则。

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.