Electron Spin Effects in Semiconductor Nanostructures

非技术性摘要目前正在全球范围内开展一场激烈的运动，以探索电子自旋(电子的一种量子力学磁性属性)在当代电子学中的作用，着眼于增加电子微芯片设备的功能，特别是在计算领域。该奖项支持一个旨在解决这一问题的项目，该项目采用最先进的技术来制造和表征一系列新型半导体纳米结构，其中电子自旋的作用通过加入磁性离子而得到增强。通过对研究生和本科生进行尖端半导体制造技术以及多功能材料设计方面的培训，该项目预计将产生广泛的影响，远远超出其直接的纯科学目标。美国工业界、国家实验室和学术界对这些材料科学领域的技能有着广泛的需求。此外，巴黎圣母院的团队通过提供研究样本或开展联合实验，与许多科学家(目前与其他35个以上的机构)合作。随着在本项目过程中开发新的自旋电子材料，这项传播和分享成果和专门知识的活动(使学生接触到机构间和跨学科小组合作的另一个好处)预计将进一步扩大。这笔赠款支持一个项目，该项目专注于两个新的但互补的领域，涉及低维磁性半导体系统中的自旋现象。(A)研究铁磁半导体在尺寸接近纳米尺寸时性能的变化；以及(B)对磷化物基FM半导体，如GaMnP和InMnP的生长和性能的探索性研究。区域(A)的动机是期望，当诸如GaMnAs的磁性半导体的物理尺寸接近纳米级并且变得与例如铁磁磁区壁的宽度或自由载流子耗尽长度相当时，其磁性将显著改变。当人们考虑调频半导体器件在纳米技术中的应用时，这变得尤为重要。使用分子束外延(MBE)和光刻技术，巴黎圣母院的团队建议通过磁化测量、磁传输、磁光研究和铁磁共振来探索这种尺寸减小的后果。领域(B)侧重于开展磷化物基铁磁半导体分子束外延生长的综合研究，然后对其自旋特性进行系统研究。尽管GaMnP、InMnP和GaMnAsP等合金的自旋性能被认为是非常有前途的，并提供了一系列重要的新机会，但令人惊讶的是，与GaMnAs或InMnAs合金相比，在这类材料上所做的工作很少。将拟议的研究扩展到这一新的FM半导体家族，有望极大地促进对铁磁半导体的总体理解。

NON-TECHNICAL ABSTRACTThere is currently an intense worldwide movement to explore the role of the electron spin (a quantum-mechanical magnetic property of the electron) in addition to the electron's charge in contemporary electronics, with an eye on increasing the functionality of electronic microchip devices, particularly in the realm of computation. This award supports a project aimed at addressing this issue by employing state-of-the-art techniques to fabricate and characterize a series of novel semiconductor nanometer scale structures in which the role of the electron spin is enhanced by incorporating magnetic ions. By training graduate and undergraduate students in cutting-edge semiconductor fabrication techniques as well as in designing multi-functional materials, the project is expected to have broad impact far beyond its immediate purely scientific goals. Skills in these areas of materials science are in wide demand in U.S. Industry, National Laboratories, and Academia. Additionally, the Notre Dame team collaborates with many scientists (currently with more than thirty-five other institutions) either by providing research samples or by carrying out joint experiments. This activity of dissemination and sharing of results and know-how (which has the added benefit of exposing students to inter-institutional and inter-disciplinary team collaborations) is expected to further expand as new spin-based electronic materials are developed in the course of the present project. TECHNICAL ABSTRACTThis grant supports a project that focuses on two new but complementary areas involving spin phenomena in low-dimensional magnetic semiconductor systems. (a) The study of changes in the properties of ferromagnetic (FM) semiconductors as their size approaches nanometer dimensions; and (b) exploratory research on growth and properties of phosphide-based FM semiconductors, such as GaMnP and InMnP. Area (a) is motivated by the expectation that, as the physical size of a magnetic semiconductor such as GaMnAs approaches the nanometer scale and becomes comparable to, e.g., the width of ferromagnetic domain walls or the free carrier depletion length, its magnetic properties will significantly change. This becomes especially important as one considers applications of FM semiconductor devices in nanotechnology. Using molecular beam epitaxy (MBE) followed by lithographic techniques, the Notre Dame team proposes to explore the consequences of such reduced size by magnetization measurements, magneto-transport, magneto-optical studies, and ferromagnetic resonance. Area (b) is focused on developing comprehensive research on MBE growth of phosphide-based ferromagnetic semiconductors, followed by a systematic investigation of their spin-based properties. Although the spin properties of alloys such as GaMnP, InMnP and GaMnAsP are expected to be highly promising, and offer a range of important new opportunities, surprisingly little work has been done on this family of materials as compared to the effort given to, e.g., the GaMnAs or InMnAs alloys. Extending the proposed studies to this new family of FM semiconductors is expected to significantly advance the understanding of ferromagnetic semiconductors generally.