GOALI: Growth-Dependent Identification and Control of Bulk and Interface Defects in ZnO

技术。由于最近引入了基于GaN的蓝光发射器和高功率场效应晶体管，ZnO是下一代电子产品的主要候选者，并且ZnO是这些应用的基本更好的材料。也就是说，氧化锌更便宜，毒性更小，更容易生长，作为发射极效率更高，作为晶体管速度更快。也许最近期的商业应用将是固态照明，预计到2025年，固态照明将主导人工照明行业，每年可节省1250亿美元的成本。然而，ZnO作为一种材料还没有准备好用于这种应用。它不容易制成“p型”，这是制造发光p-n同质结的必要步骤。其次，很难形成场效应晶体管所需要的肖特基势垒。第三，它的表面和界面性能难以控制，很大程度上是因为表面的极性性质。在ZnO成为一种商业上可行的材料之前，这些问题必须得到解决。鉴于此，该GOALI（与工业界学术联络的资助机会）项目解决了决定ZnO材料科学和电子学进步的关键问题。该方法包括：(a)由工业合作伙伴提供的最先进的ZnO的受控生长，(b)由学术合作伙伴使用电子，光学和表面科学技术的补充来表征体积和界面特性，(c)分析系统生长变化以分离关键缺陷和掺杂机制，以及(d)对这些结果进行协同反馈以进一步完善生长过程。该项目的目标和智力价值是：(1)了解生长，加工，本体和界面上的内在缺陷和外在掺杂之间的复杂关系；(2)利用这些发现创建ZnO单晶薄膜和本体晶圆，通过完全控制掺杂，界面状态和势垒形成，扩大光电应用范围。GOALI项目旨在通过将关键物理特性与生长的系统性变化联系起来，以最直接的方式解决这些问题。跨学科的GOALI团队由研究人员组成，他们将单晶生长，表征和建模方面的互补和独特专业知识与共同的兴趣结合起来，探索和利用生长，电子和结构特性以及宽带隙半导体的界面特性之间的关系。核心活动包括：(1)开发识别和控制电活性缺陷的晶体生长技术；(2)建立有利于p型掺杂剂掺入和活化的生长原理；(3)创建界面表征技术，提供在不同受控生长条件下形成的ZnO的关键电子、化学和结构信息；(4)探索生长前表面化学在ZnO同外延结缺陷和界面态形成中的作用。非技术。此次GOALI合作的更广泛影响包括每年的人员交流，使研究生、本科生和大学人员在密切协调的活动中与ZN科技的工业科学家直接接触。这些交流将提供机会，通过提供接触到学术界和高科技产业环境中的工业研究人员，以及获得先进的晶体生长和表征设备，扩大学生的教育。该合作还为哥伦布和代顿当地有前途的高中学生，特别是哥伦布女子学校的女性，以及通过附属空军研究实验室暑期项目的学生提供与工业相关的暑期研究经验。

Technical. ZnO is a leading candidate for the next generation of electronics, stemming from the recent introduction of blue light emitters and high power field-effect transistors based on GaN, and the realization that ZnO is a fundamentally better material for these applications. That is, ZnO is cheaper, less toxic, easier to grow, more efficient as an emitter, and faster as a transistor. Perhaps the most near-term commercial application will be solid-state lighting, which is forecast to dominate the artificial lighting industry by 2025, and at an annual cost savings of $125 Billion. However, ZnO as a material is not ready for such applications. It cannot be easily made "p-type," which is a necessary step in the fabrication of a light emitting p-n homojunction. Secondly, it is difficult to form Schottky barriers, which are required for field-effect transistors. Thirdly, its surface and interface properties are difficult to control, largely because of the polar nature of the surface. These problems must be addressed and solved before ZnO will be a commercially viable material. In view of this, this GOALI (Grant Opportunity for Academic Liaison with Industry) project addresses the key issues determining advances in ZnO materials science and electronics. The approach encompasses: (a) controlled growth of state-of-the-art ZnO provided by the industrial partner, (b) characterization of bulk and interface properties by the academic partners using a complement of electronic, optical, and surface science techniques, (c) analysis of systematic growth variations to isolate pivotal defect and doping mechanisms, and (d) synergistic feedback of these results to further refine the growth process. The objectives and intellectual merit for the project are to: (1) understand the complex relationships between growth, processing, intrinsic defects and extrinsic doping in both the bulk and at the interface and (2) use these findings to create ZnO single crystal films and bulk wafers that expand the range of optoelectronic applications by enabling full control of doping, interface states and barrier formation. This GOALI project aims to address these issues in the most direct approach possible, by linking key physical properties with systematic variations in growth. The interdisciplinary GOALI team consists of researchers who combine complementary and unique expertise in single crystal growth, characterization, and modeling with a shared interest to explore and exploit the relationships between growth, electronic and structural properties, and interface properties of wide band gap semiconductors. Core activities include: (1) developing crystal growth techniques that identify and control electrically-active defects; (2) establishing growth principles that facilitate the incorporation and activation of p-type dopants; (3) creating interface characterization techniques that provide key electronic, chemical, and structural information on ZnO formed under different controlled growth conditions; and (4) exploring the role of pre-growth surface chemistry in defect and interface state formation at ZnO homoepitaxial junctions. Non-Technical. The broader impacts of this GOALI collaboration include yearly personnel exchanges that place graduate research students, undergraduates, and university personnel in direct contact with industrial scientists at ZN Technology in closely coordinated activities. These exchanges will provide opportunities to broaden students' education by providing exposure to industrial researchers both within academia and a high technology industry environment, as well as access to advanced crystal growth and characterization equipment. The collaboration also provides summer research experiences relevant to industry for promising local high school students in Columbus and Dayton, especially women at the Columbus School for Girls, as well as students via a strongly affiliated Air Force Research Laboratory summer program. .