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

0900971/0900978协同研究：电子注入诱导效应在氧化锌材料和器件结构中的研究随着氧化锌外延生长和加工的最新进展，很有可能在不久的将来实现高效的少数载流子器件，如发光二极管、激光二极管和透明的p-n结。少数载流子扩散长度是决定p-n结性能的关键参数之一，由于在氧化锌半导体中，少数载流子扩散长度通常小于1微米，因此迫切需要找到改善它的方法。主要研究人员的最新发现表明，由于电子注入，p型氧化锌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陷阱，但延伸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氧化锌及其相关化合物中少数载流子输运和复合的影响。我们将研究广泛的外延掺锑p型氧化锌和p型锌镁氧化物(x？t0.15)薄膜。此外，还将研究掺杂磷、氮等杂质的p-氧化锌以及p型锌镉氧(x？t0.15)和锌(镁/镉)O/氧化锌超晶格中的少数载流子输运。镁(镉)掺入氧化锌晶格和势垒以及超晶格中的良好存在创造了不同于氧化锌的电子注入条件。为了充分了解电子注入对Zn(Mg/Cd)O的影响并寻找其适用条件，我们将在具有代表性的器件结构范围内进行系统的电学和光学研究：P-n结和肖特基二极管。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进行现场测试。这些测量将与现场阴极发光以及光谱光响应和瞬时光电流测量相补充。要研究的电子注入的影响可能与掺杂浓度、外延层质量和成分有关。因此，研究材料在这些性质上的变化是必要的。通过中佛罗里达大学和加州大学河滨分校的小组之间的互动合作，这些材料的生长及其设备结构的制造和表征得到了保证。这项研究的实际意义在于对光电探测器等p-n结电荷收集半导体器件的性能控制，其中少数载流子扩散长度起着关键作用。与目前最先进的约15-20%相比，预计光电探测器--S的量子效率将提高数倍。这一合作项目的更广泛影响是更好地了解氧化锌半导体中点缺陷和扩展缺陷的基本原理，在两所大学之间建立伙伴关系，并整合研究生、本科生和K-12水平的研究和教育，这体现在未被充分代表的博士生、几名本科生和当地高中生参与拟议的研究。这些学生将在参与拟议的研究时，建立长期、远程学术项目的合作技能。

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.