Collaborative Research: Studies of Electron Injection-Induced Effects in ZnO-based Materials and Device Structures

合作研究：ZnO基材料和器件结构中电子注入诱导效应的研究

• 批准号: 0900978
• 负责人: Jianlin Liu
• 金额: $ 24.49万
• 依托单位: University of California-Riverside
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0900978&HistoricalAwards=false
• 关键词: Collaborative; Research; Studies; Electron; Injection

ECCS 0900971/0900978Collaborative Research: Studies of Electron Injection-Induced Effects in ZnO-based Materials and Device Structures With recent advances in ZnO epitaxial growth and processing, it is very likely that efficient minority carrier devices, such as light emitting diodes, laser diodes and transparent p-n junctions, can be achieved in the near future. Because the minority carrier diffusion length - one of the critical parameters in defining p-n junction performance - is usually less than 1 micron in ZnO-based semiconductors, it is imperative to find ways of its improvement. The principal investigators¡¦ recent findings indicate that the minority carrier diffusion length can be elongated in p-type ZnO due to electron injection. While the observed novel effect was attributed to electron trapping on impurity-related levels, the role of extended and point defects as well as of surface states was not completely excluded. The intellectual merit of this research is in exploration of electron injection¡¦s impact on minority carrier transport and recombination in ZnO and related compounds. A wide range of epitaxial antimony-doped p-type ZnO and p-type Zn1-xMgxO (x ?T 0.15) layers will be studied. In addition, the minority carrier transport in p-ZnO doped with other impurities such as phosphorus, or nitrogen, as well as in p-type Zn1-xCdxO (x ?T 0.15) and Zn(Mg/Cd)O/ZnO superlattices, will be investigated. Magnesium (Cadmium) incorporation into the ZnO lattice and barrier and well presence in the superlattices create electron injection conditions different from that in ZnO. To fully understand the effects of electron injection in Zn(Mg/Cd)O and to find conditions under which they can be employed, systematic electrical and optical studies will be carried out in the representative range of device structures: p-n junction and Schottky diodes. Electrical testing, combined with Electron Beam-Induced Current measurements, will be performed in-situ in a Scanning Electron Microscope. These measurements will be complemented with in-situ cathodoluminescence as well as spectral photoresponse and transient photocurrent measurements.The effects of electron injection to be investigated are likely related to concentration of dopants, epitaxial layer quality and composition. Therefore, the study of materials with variations in these properties is necessary. The growth of these materials and the fabrication and characterization of their device structures are assured through the interactive collaboration between the groups at the University of Central Florida and the University of California, Riverside. The practical significance of the proposed research is in performance control of p-n junction charge collection semiconductor devices, such as photodetectors, in which the minority carrier diffusion length plays a critical role. A several-fold increase in the photodetector¡¦s quantum efficiency is anticipated relative to the current state-of-the-art of ~ 15-20%. The broader impact of this collaborative project is in better understanding the fundamentals of point and extended defects in ZnO-based semiconductors, creating a partnership between two universities, and integrating research and education at the graduate, undergraduate and K-12 levels, as expressed in participation of underrepresented Ph.D. students, several undergraduates and local high school students in the proposed research. These students will build skills in collaborating on a long-term, long-distance academic project, as they participate in the proposed research.

ECCS 0900971/0900978合作研究：ZnO基材料和器件结构中电子注入诱导效应的研究随着ZnO外延生长和加工的最新进展，很可能在不久的将来实现高效的少数载流子器件，例如发光二极管、激光二极管和透明p-n结。 由于少数载流子扩散长度（定义 p-n 结性能的关键参数之一）在 ZnO 基半导体中通常小于 1 微米，因此必须找到改进的方法。主要研究人员最近的研究结果表明，由于电子注入，p型ZnO中的少数载流子扩散长度可以延长。虽然观察到的新效应归因于杂质相关能级上的电子俘获，但扩展缺陷和点缺陷以及表面态的作用并未完全排除。 本研究的智力价值在于探索电子注入对ZnO及相关化合物中少数载流子输运和复合的影响。将研究各种外延锑掺杂的 p 型 ZnO 和 p 型 Zn1-xMgxO (x ≤T 0.15) 层。此外，还将研究掺杂其他杂质（例如磷或氮）的 p-ZnO 以及 p 型 Zn1-xCdxO (x ≤T 0.15) 和 Zn(Mg/Cd)O/ZnO 超晶格中的少数载流子输运。镁（镉）掺入 ZnO 晶格和势垒以及超晶格中的良好存在创造了与 ZnO 不同的电子注入条件。为了充分了解 Zn(Mg/Cd)O 中电子注入的影响并找到其使用条件，将对代表性器件结构范围：p-n 结和肖特基二极管进行系统的电学和光学研究。电气测试与电子束感应电流测量相结合，将在扫描电子显微镜中现场进行。这些测量将与原位阴极发光以及光谱光响应和瞬态光电流测量相补充。要研究的电子注入的影响可能与掺杂剂浓度、外延层质量和成分有关。因此，研究具有这些特性变化的材料是必要的。通过中佛罗里达大学和加州大学河滨分校之间的互动合作，可以确保这些材料的生长及其器件结构的制造和表征。 该研究的实际意义在于p-n结电荷收集半导体器件（例如光电探测器）的性能控制，其中少数载流子扩散长度起着至关重要的作用。相对于目前最先进的约 15-20%，预计光电探测器的量子效率将增加数倍。该合作项目的更广泛影响在于更好地了解 ZnO 基半导体的点缺陷和扩展缺陷的基本原理，在两所大学之间建立合作伙伴关系，并整合研究生、本科生和 K-12 级别的研究和教育，正如代表性不足的博士生的参与所体现的那样。学生、几名本科生和当地高中生参与了拟议的研究。这些学生在参与拟议研究时将培养长期、远程学术项目合作的技能。