RUI: Growth and Characterization of Epitaxial Zinc Oxide Films for Device Applications

氧化锌（ZnO）是一种有吸引力的半导体材料，因为其独特的特性，例如更好的电子和光学性能、更大的辐射硬度、相对容易合成以及更好的环境友好性。因此，其可用于制造太阳能电池、光发射器（例如，发光二极管（LED）和激光二极管）、用于高功率和高温应用的电子器件、传感器和高密度数据存储系统。这些应用中的大多数都需要n型和p型氧化锌材料。虽然高质量的n型ZnO材料很容易获得，但已证明难以开发p型ZnO材料。本研究将探讨δ掺杂技术以制备高导电性p型氧化锌材料。这种技术，已被证明是成功的与其他半导体材料，涉及限制p型掺杂原子在一个狭窄的层的主机ZnO材料。随着p型ZnO材料的成功开发，该项目将对经济增长、节能和环境保护工作产生积极影响。该项目将为研究生和本科生提供半导体材料研究方面的教育和培训，使用尖端技术，为他们的高科技职业或进一步的研究生教育做好准备，并将与凝聚态物理课程相结合，吸引来自多个科学和工程部门的学生。将继续与K-12学生进行外联，并争取代表性不足的群体（妇女和少数民族）的YSU学生参与。技术说明虽然ZnO与GaN具有若干电子和光学特性，但它具有更高的激子结合能，更大的辐射硬度，可批量获得，并且需要更简单的晶体生长和加工技术。这些优点使其在制造各种电子、光学和自旋电子器件方面具有独特的吸引力。然而，高本征n型杂质浓度的存在阻碍了实现器件制造所需的高质量p型ZnO材料。本计画的目的是利用磁控溅镀技术，以delta掺杂来获得高导电率的p型氧化锌薄膜。Delta掺杂已经成功地在具有类似p型掺杂挑战的许多宽带隙半导体中产生增强的p型掺杂。p型掺杂原子将在空间上被限制在一个狭窄的层中，导致具有独特的V形势阱的二维掺杂密度分布，这超过了常用的均匀掺杂的溶解度极限。该项目可能会带来变革性的成果，因为它不仅会影响半导体器件的开发，而且还可以研究与掺杂分布微型化的基本限制相关的基础科学。

NON-TECHNICAL DESCRIPTION Zinc oxide (ZnO) is an attractive semiconductor material because of its unique characteristics such as better electronic and optical properties, greater radiation hardness, relative ease of its synthesis, and greater environmental friendliness. It is therefore useful for the fabrication of solar cells, light emitters (e.g., light emitting diodes(LEDs) and laser diodes), electronic devices for high power and high temperature applications, sensors and high-density data storage systems. Most of these applications require both n-type and p-type zinc oxide materials. While high quality n-type ZnO materials are readily available, it has proved difficult to develop p-type ZnO materials. This research will investigate the technique of delta-doping for the production of highly conductive p-type ZnO materials. This technique, which has proved successful with other semiconductor materials, involves confining p-type doping atoms in a narrow layer of the host ZnO material. With successful development of p-type ZnO materials, this project could make positive impact to the economic growth, energy savings, and environmental conservation efforts. This project will provide education and training of graduate and undergraduate students in semiconductor materials research using cutting-edge techniques that will prepare them for hi-tech careers or further graduate education, and will also be integrated with the Condensed Matter Physics course that attracts students from several science and engineering departments. Outreach to K-12 students as well as participation of YSU students from the underrepresented groups (women and minorities) will be pursued.TECHNICAL DESCRIPTIONWhile ZnO shares several electronic and optical properties with GaN, it has a higher exciton binding energy, greater radiation hardness, is available in bulk and requires simpler crystal growth and processing technology. These advantages make it uniquely attractive for fabricating various electronic, optical and spintronic devices. However, the presence of high intrinsic n-type impurity concentration has hindered achievement of good quality p-type ZnO materials necessary for device fabrication. The objective of this project is to achieve high conductivity p-type ZnO films using delta doping by magnetron sputter deposition. Delta doping has successfully yielded enhanced p-type doping in many wide band gap semiconductors with similar p-type doping challenges. The p-type doping atoms will be spatially confined in a narrow layer, resulting in a two-dimensional doping density profile with a unique V-shaped potential well, which exceeds the solubility limit of the commonly used homogeneous doping. This project could lead to transformational outcomes as it will not only impact semiconductor device development, but also permit investigation of the basic science related to the fundamental limits of doping profile miniaturization.