Epitaxial Film Growth and Characterization of Stable and Metastable Gallium-Aluminum-Oxide Polymorphs

非技术描述：半导体在日常生活中无处不在，是工业制造、通信、运输、能量转换和传输以及许多其他应用的关键部件。《美国芯片与科学法案》（U.S. CHIPS and Science Act）提供了500多亿美元用于增加国内半导体研究和制造，进一步凸显了半导体研究对美国国家安全和经济的至关重要性。该研究项目为生产新型半导体合金系统创造了科学知识，并为未来可在极端环境下运行的半导体设备的开发和制造提供了平台。半导体器件在更高温度和更高功率下工作的能力转化为大量的能源节约和更高效、更强大的可再生能源技术，如远程电动汽车。作为未来劳动力的一部分，研究生和本科生在半导体行业所需的新加工方法和先进表征工具方面获得了广泛的技能。外展活动还教育初高中学生有关半导体和相关材料的知识，以激励他们考虑从事STEM领域的职业。这项研究产生的材料和生长配方促进了半导体研发活动：外部研究小组可以通过在卡内基梅隆大学洁净室用户设施的设备上进行培训，向洁净室工作人员索取收费的服务薄膜，或通过与主要研究者建立的研究合作来生产或获得半导体薄膜。技术描述：该项目是一项关于氧化镓铝（AGO）外延膜不同相或多晶的生长和表征的研究，该外延膜具有巨大的潜力，可以在极端条件下运行的高效电力电子器件。将氧化镓与Al合金形成具有独特性能和可调的超宽带隙的AGO的不同多晶型的能力，呈现出一个巨大的材料系统，具有形成现有和新型半导体器件平台的潜力。因此，该项目的最终目标是实现对AGO半导体外延膜的相含量和微观结构的前所未有的控制。然而，对于如何在这种材料体系中控制一相相对于另一相的生长的理解是非常有限的。利用化学气相沉积技术制备薄膜，本研究有助于理解热力学和动力学变量如何作为Al含量的函数来控制AGO稳定和亚稳态多晶的生长。先前的实验和理论研究作为参考点，并告知实验方法。采用先进的材料表征工具来识别薄膜中的微/纳米结构、相含量和组成，揭示薄膜内部和薄膜/衬底界面的相互扩散和相变等现象，这些现象决定了所得薄膜生长的性质。显示最佳结构特征的薄膜的电气测量揭示了与基于这些材料的未来电子设备相关的特性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical description:Ubiquitous in every-day life, semiconductors are critical components in industrial manufacturing, communications, transportation, energy conversion and transmission, and many other applications. The U.S. CHIPS and Science Act, which provides more than $50 billion to increase domestic research and manufacturing of semiconductors, further highlights the critical importance of semiconductor research to U.S. national security and the economy. This research project creates scientific knowledge to produce a novel semiconductor alloy system and forms a platform for the development and manufacturing of future semiconductor devices that can operate in extreme environments. The capability for semiconductor devices to operate at higher temperatures and higher powers translates to substantial energy savings and more efficient and robust renewable energy technologies, such as long-range electric vehicles. As part of the future workforce, graduate and undergraduate students gain a broad set of skills in new processing methods and advanced characterization tools that are needed in the semiconductor industry. Outreach activities also educate middle/high-school students about semiconductors and related materials to inspire them to consider careers in STEM. The materials and growth recipes resulting from this research advance semiconductor R&D activities: external research groups can produce or acquire semiconductor films through training on the equipment located in Carnegie Mellon University’s clean room user facility, requesting fee-for-service films from clean room staff, or through an established research collaboration with the principal investigator.Technical description:This project is a research investigation on the growth and characterization of different phases, or polymorphs, of gallium-aluminum-oxide (AGO) epitaxial films, which have enormous potential for high-efficiency power-electronic devices that can operate in extreme conditions. The ability to alloy gallium oxide with Al to form different polymorphs of AGO with unique properties and tunable, ultra-wide bandgaps that depend on Al content presents a vast materials system with potential to form a platform for both established and novel semiconductor devices. As such, an ultimate goal of this project is to achieve unprecedented control over the phase content and microstructure of AGO semiconductor epitaxial films. However, the understanding of how to control the growth of one phase versus another in this material system is very limited. Using chemical vapor deposition to produce the films, this research contributes to the understanding of how thermodynamic and kinetic variables can be used to control the growth of stable and metastable polymorphs of AGO as a function of Al content. Prior experimental and theoretical studies serve as points of reference and inform the experimental approach. Advanced materials characterization tools are employed to identify the micro-/ nano-structure, phase content and composition in the films and reveal such phenomena as interdiffusion and phase transitions within the film and at the film/substrate interface, which determine the nature of the resulting film growth. Electrical measurements of films showing optimum structural characteristics uncover properties that are relevant for future electronic devices based on these materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.