CAREER: Synthesis, Processing and Characterization of Novel Electronic Oxides

这个职业项目的特点是材料发现、本科研究经历和围绕电子材料共同主题组织的课程开发相结合。电子氧化物以其独特的导电能力区别于普通陶瓷。透明导电氧化物（tco）是几乎所有显示和光伏器件的关键部件。第二类氧化物可以导电并与离子发生反应，这一过程被称为嵌入，是电致变色窗口和可充电电池的核心。随着依赖这些材料的技术不断进步，氧化物的质量已经开始限制最终设备的性能。本职业项目将针对利用等离子体增强化学气相沉积（PECVD）合成、加工和表征新型氧化物。等离子体的光学分析和薄膜的电学、光学和结构特性的基本评价将指导实验工作。并发测量将用于开发处理-结构-属性关系。扩大本科生的研究机会和继续加强我们的电子材料课程将推进教育目标。迄今为止，电子氧化物主要是通过物理气相沉积（PVD）技术合成的。与PVD相比，PECVD在开发新化合物、有效掺杂和生产功能梯度材料方面具有显著的优势。最有趣的tco要么是合金（氧化铟锡，ITO），要么是掺杂材料ZnO:AL， SnO2:F)，它们的电导率总是n型的。我们将致力于发现和表征性能更好的新型n型合金，以及p型tco的合成。p型氧化物的发展将使透明p-n二极管的形成和基于氧化物的电子学的出现成为可能。氧化物的大带隙和化学稳定性使它们成为高温/恶劣环境应用的有吸引力的候选者。低电阻率p型tco将通过使用共掺杂来追求，这是一个动力学过程，其中一个供体原子（例如Ga）和两个受体原子（例如N）同时被纳入薄膜中。这个职业项目的第二个方面将涉及使用本科研究人员来研究离子导体氧化物的合成。氧化钨（WO3）是一种主要的电致变色材料，其透明度可通过与小离子（H+, Li+）的反应而发生可逆改变。器件性能通常受到阳离子通过薄膜的传输的限制，而这又在很大程度上取决于薄膜的化学计量和微观结构。研究了PECVD氧化钨的物理性质和瞬态电致变色响应随等离子体工作条件的变化。这个职业项目的最后阶段是针对CSM电子材料课程的持续发展。在NSF-ILI的支持下，PI创建了一个新的硅加工实验课程。这个跨学科的实验室以合作学习和好奇心驱动的实验为特色，去年成功地为来自四个系的20名大四学生提供了这个实验室。PI将继续扩展这个实验室，为研究生创建一个更高级的课程。最后，计算工具将被纳入本科课程，以促进更高层次的思维能力。

CTS-0093611 Colin A. WoldenAbstractThis career project features a combination of materials discovery, undergraduate research experience, and curriculum development organized around the common theme of electronic materials. Electronic oxides are distinguished from common ceramics by their unique ability to conduct charge. Transparent conducting oxides (TCOs) are key components in nearly all display and photovoltaic devices. A second class of oxides conduct and react with ions, a process called intercalation, which is central to electrochromic windows and rechargeable batteries. As technologies reliant on these materials continue to advance, it has become clear that oxide quality is beginning to limit final device performance. This career project will be directed at the synthesis, processing, and characterization of novel oxides using plasma-enhanced chemical vapor deposition (PECVD). Optical interrogation of the plasma and fundamental evaluation of the films' electrical, optical, and structural characteristics will guide the experimental effort. Concurrent measurements will be used to develop processing-structure-property relationships. Expanded research opportunities for undergraduates and continued enhancement of our electronic materials curriculum will advance educational goals.Electronic oxides have been synthesized to date primarily by physical vapor deposition (PVD) techniques. PECVD offers significant advantages over PVD with respect to the development of new compounds, effective doping, and the production of functionally graded materials. The most interesting TCOs are either alloys (indium tin oxide, ITO) or doped materials ZnO:AL, SnO2:F), and their conductivity is invariably n-type. Our efforts will be directed at the discovery and characterization new n-type alloys with improved properties, as well as the synthesis of p-type TCOs. The development of p-type oxides will enable the formation of transparent p-n diodes and the advent of oxide-based electronics. The large bandgap and chemical stability of oxides make them attractive candidates for high temperature/harsh environment applications. Low resistivity p-type TCOs will be pursued through the use of co-doping, a kinetic process in which a donor atom (e.g. Ga) and two acceptor atoms (e.g. N) are simultaneously incorporated into the film.A second aspect of this career project will involve the use of undergraduate researchers to study the synthesis of oxides that are ion conductors. Tungsten oxide (WO3) is leading electrochromic material whose transparency is reversibly altered by reactions with small ions (H+, Li+). Device performance is often limited by cation transport through the film, which in turn depends strongly on film stoichiometry and microstructure. The physical properties and the transient electrochromic response of PECVD tungsten oxide will be investigated as a function of plasma operating conditions.The final phase of this career project is directed at the continued development of the electronic materials curriculum at CSM. The PI has created, with NSF-ILI support, a new laboratory course in silicon processing. The interdisciplinary lab, which features cooperative learning and curiosity-driven experiments, was successfully offered last year to 20 seniors from four departments. The PI will continue the expansion of this laboratory, creating a more advanced course for graduate students. Finally, computational tools will be incorporated into the undergraduate curriculum in order to promote higher order thinking skills.