NER: Exploring Defect Controlled Ferromagnetism in Mn Doped ZnGeP2/GaP Heterojunction

这项纳米探索性研究(NER)计划是应“纳米科学与工程”(NSF 02-148)的征集而提交的。该项目解决了半导体中自旋注入和传输方面的主要挑战。在这项探索性研究中，我们将在GaP衬底上生长掺锰的ZnGeP2外延薄膜，并对其磁性进行研究。一个需要解决的主要材料问题是局域缺陷，如纳米团簇在诱导ZnGeP2/GaP异质结中的铁磁有序中所起的作用。材料将通过分子束外延来合成。用X射线衍射仪和电子显微镜研究了生长条件对化学计量比、缺陷和纳米团簇以及掺杂的影响。缺陷和纳米团簇的原子结构将通过横截面扫描隧道显微镜和光谱分析进行研究。输运和磁性将通过霍尔、磁阻和SQUID测量来确定。通过更好地了解外延薄膜中缺陷的结构和电子结构，可以预测II-IV-V2黄铜矿半导体中铁磁性的起源。该项目解决了材料科学中具有高度技术相关性的热门领域的基础探索性研究问题；它被认为是一项高风险/高回报的活动。该项目围绕NSE纳米结构、新现象和量子控制的研究和教育主题。该计划的一个重要特点是通过在一个具有根本意义和技术意义的领域对学生进行培训，将研究和教育结合起来。该项目预计将产生广泛的影响，提供独特的教育机会和对潜在开发具有计算和信息存储技术优势的半导体自旋电子器件至关重要的基本知识。该项目由MPS/DMR/EM和ENG/ECS/EPDT方案共同支持。

This Nanoscale Exploratory Research (NER) proposal was submitted in response to the solicitation "Nanoscale Science and Engineering" (NSF 02-148). This project addresses primary challenges in spin injection and transport in semiconductors. In this exploratory research, epitaxial thin films of Mn doped ZnGeP2 will be grown on GaP substrates and resulting magnetic properties investigated. A primary materials issue to be addressed is the role of local defects such as nano clusters in inducing ferromagnetic ordering in ZnGeP2/GaP heterojunctions. Materials will be synthesized by molecular beam epitaxy. The effects of growth conditions on stoichiometry, defects and nano clustering, and doping will be studied by x-ray diffraction and transmission electron microscopy. Atomic structures of the defects and nanoclusters will be examined by cross-sectional scanning tunneling microscopy and spectroscopy. Transport and magnetic properties will be determined by Hall, magnetoresistance, and SQUID measurements. Through a better understanding of the structure and electronic structure of the defects in the epitaxial films, the origin of ferromagnetism in II-IV-V2 chalcopyrite semiconductors is anticipated.The project addresses basic exploratory research issues in a topical area of materials science with high technological relevance; it is considered a high risk/high pay-off activity. The project encompasses the NSE research and education theme of Nanoscale Structures, Novel Phenomena, and Quantum Control. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area. The project is expected to have broad impact by providing unique educational opportunities and basic knowledge critical to potential development of semiconductor spintronic devices having advantages in computing and information storage technologies. The project is jointly supported by the MPS/DMR/EM and ENG/ECS/EPDT programs.