SPIN ELECTRONICS: III-V/Mn Ferromagnetic Semiconductors for Device Applications

0224206本提案是根据21世纪自旋电子学倡议，项目招标NSF 02-036收到的。本文主要研究III-V/Mn材料及其异质结构的生长、表征和器件研究。本计划的目标是发展铁磁共振带间隧道二极管（FRITD）和偏振可调红外发光二极管。为了为这些设备开发优化的材料，并演示原理操作的证明，设备结构将与材料生长并行制造和测试，以提供对材料工作的直接反馈。布法罗大学（UB）对这些器件组成材料的结构、输运/磁输运、光学和磁性的初步研究揭示了与磁性Mn++离子在高片密度下的结合有关的几个有趣的问题。更重要的是，发现这些材料的结构、光学、输运和磁性是密切相关的。这些研究表明，需要从原子水平设计材料，以便同时优化电输运、光学和磁性；这是这个项目的关键任务之一。具体而言，针对这些复杂问题，建议组建多学科研究团队，开展iii - v基铁磁材料/结构、基本性质、自旋注入/界面效应和器件的综合研究。在这项提议的工作中，布法罗大学小组将：1)制造系统的GaAs/Mn， GaSb/Mn和InAs/Mn数字合金样品集，其中Mn的亚单层插入到III-V晶格中；2)探索磁、电输运、光学性质和结构质量作为生长条件的函数；3)优化生长条件，产生最高的居里温度；4)制作和测试器件结构。该计划的制定是为了最大限度地让学生参与多学科研究，让工程和物理专业的学生共同努力，达到共同的目标。它将利用现有的基础设施，既用于合作研究，也用于学生互动，该基础设施已建立，用于正在进行的自旋电子材料开发项目，该项目由国防高级研究计划局（DARPA）支持，重点研究其他材料。本项目将资助三名全日制研究生，与相关工作协同合作，使其成为可能。该项目的成功将直接影响自旋电子学领域的关键问题，即提高居里温度，生产适合实际器件和自旋注入半导体异质结构的材料。结合目前在darpa支持的项目中研究的其他材料，UB的材料工作代表了该国最强大的材料之一。该器件的制造和表征将引领解决涉及III-V材料的自旋注入相关材料研究的瓶颈，以及电子（而不是空穴）自旋注入的可能性。

0224206LuoThis proposal was received in response to the Spin Electronics for the 21st Century Initiative, Program Solicitation NSF 02-036. The proposal focuses on growth, characterization and device studies of III-V/Mn materials and their heterostructures. The goal of this program is to develop ferromagnetic resonant interband tunneling diodes (FRITD) and polarization tunable infrared light emitting diodes. In order to develop optimized materials for these devices, and to demonstrate proof of principle operation, device structures will be fabricated and tested in parallel with the materials growth to provide direct feedback to the materials effort. Preliminary studies at the University at Buffalo (UB) of structural, transport/magneto-transport, optical and magnetic properties of the constituent materials for these devices have revealed several interesting problems associated with the incorporation of magnetic Mn++ ions at high sheet densities. More importantly, it was found that the structural, optical, transport and magnetic properties of these materials are closely connected. These studies demonstrate the need for designing materials from the atomic level so that electrical transport, optical and magnetic properties are simultaneously optimized; this is one of the key tasks of this program. Specifically, to tackle these complex problems, it is proposed to form a multidisciplinary research team to carry out comprehensive studies of III-V-based ferromagnetic materials/structures, fundamental properties, spin injection/interface effects and devices. In this proposed work, the University at Buffalo group will: 1) fabricate systematic sets of samples of GaAs/Mn, GaSb/Mn, and InAs/Mn digital alloys, in which submonolayers of Mn are inserted in the III-V lattice; 2) explore the magnetic, electrical transport, optical properties and structural quality as a function of growth conditions; 3) optimize growth conditions to produce the highest Curie temperatures; 4) fabricate and test device structures.The program is formulated to maximize student involvement in multidisciplinary research by engaging engineering and physics students working together to reach common goals. It will utilize existing infrastructure, both for collaborative research and for student interactions, which has been established for the on-going spintronic materials development project supported by the Defense Advanced Research Project Agency (DARPA) focusing on other materials. A total of three full-time graduate students will be supported in this program, a substantial effort made possible by the synergism with the related work. The success of this program will have immediate impact on the key problems in the area of spintronics, namely, improving the Curie temperature and producing materials suitable for practical devices and spin injection into semiconductor heterostructures. Combined with the other materials currently studied in the DARPA-supported project, the materials effort at UB represents one of the strongest in the country. The device fabrication and characterization will lead the way in resolving bottlenecks in materials research related to spin-injection involving III-V materials, and the possibility of electron (rather than hole) spin injection.