Magnetism and Spin-Dependent Electronic Properties of Tailored Semiconductor Nanostructures

****技术摘要****该项目包括两个研究重点，研究定制半导体纳米结构的磁性和自旋相关电子特性。第一个是利用AlGaAs中的持续光电导率（PPC）来详细研究电子自旋输运/弛豫作为载流子浓度的函数。PPC允许半导体通道的原位光掺杂，从而能够在一个和同一样品的宽载流子浓度范围内测量自旋积累和寿命。该研究有望对自旋寿命以及与自旋弛豫相关的各种载流子散射过程产生全面而详细的认识。第二步研究采用高灵敏度半导体霍尔磁强计技术，研究了MBE生长的过渡金属掺杂InAs量子点的静态和动态磁性能。提出的研究目标是通过集成的微/纳米霍尔磁力计测量小阵列甚至单个量子点的磁化强度。该方案可能有助于将量子点的测量磁性与其结构/化学特性直接关联起来，从而有可能明确了解纳米结构稀释磁性半导体中铁磁性的起源。这项资助直接支持一名博士生的研究和教育，并间接支持其他已经参与该项目的学生。****非技术摘要****自旋电子学是一门新兴技术，它利用电子自旋来提供新的和改进的电子设备功能。二十多年来，金属器件中的自旋电子学取得了巨大的科学、技术和商业成功。然而，实用程序仅限于被动设备，如传感器和存储元件。半导体自旋电子学研究的动机是需要生产真正的三端自旋电子逻辑器件，用于潜在的变革性应用，如非易失性可编程逻辑、基于自旋的光电子学和量子计算。本研究解决了半导体自旋电子学的两个关键挑战：半导体介质中电子自旋的相干操纵、输运和检测，以及对过渡金属掺杂半导体铁磁性的理解。第一个项目利用光（光激发）来调整AlGaAs半导体通道的载流子密度，从而能够在同一样品中广泛的载流子浓度范围内详细检查电子自旋输运/弛豫。后者采用高灵敏度集成微/纳米霍尔磁力计来研究小阵列甚至单个掺杂过渡金属的InAs量子点的静态和动态磁性能。这项资助直接支持一名博士生的研究和教育，并间接支持其他已经参与该项目的学生。这为他们提供了与半导体研究所的学生和研究人员密切互动的机会，半导体研究所是中国首屈一指的材料研究机构。

****Technical Abstract****This project consists of two research thrusts on the magnetic and spin-dependent electronic properties of tailored semiconductor nanostructures. The first utilizes the persistent photoconductivity (PPC) in AlGaAs for a detailed examination of the electronic spin transport/relaxation as a function of its carrier concentration. PPC permits in situ photodoping of the semiconductor channel, thus enabling measurements of spin accumulation and lifetime over broad carrier concentration ranges in one and the same sample. The research is expected to produce comprehensive and detailed knowledge of the spin lifetime as well as various carrier scattering processes relevant to spin relaxation. The second line of research employs high-sensitivity semiconductor Hall magnetometry techniques to study the static and dynamic magnetic properties of transition metal-doped InAs quantum dots (QDs) grown by MBE. The goal of the proposed research is to measure the magnetization of a small array of, even an individual, QDs via an integrated micro/nano Hall magnetometer. The scheme may facilitate a direct correlation of the measured magnetic properties of the QDs with their structural/chemical characteristics, potentially enabling a definitive understanding of the origin of the ferromagnetism in the nano-structured diluted magnetic semiconductors. This grant supports directly the research and education of a PhD student and indirectly other students already involved with this project.****Non-Technical Abstract****Spintronics is an emerging technology which utilizes the electronic spin to provide new and improved electronic device functionality. For more than two decades spintronics in metallic devices has enjoyed great scientific, technological and commercial successes. However, the utilities have been limited to passive devices such as sensors and memory elements. The research into semiconductor spintronics is motivated by the need to produce true three-terminal spintronic logic devices for potential transformative applications such as nonvolatile reprogrammable logic, spin-based opto-electronics, and quantum computation. The research here addresses two key challenges in semiconductor spintronics: coherent manipulation, transport and detection of electron spins in a semiconducting medium and the understanding of the ferromagnetism in transitional metal-doped semiconductors. The first project utilizes light (photo-excitation) to tune the carrier density of an AlGaAs semiconductor channel, enabling a detailed examination of the electronic spin transport/relaxation over a broad carrier concentration range in one and the same sample. The latter employs a high-sensitivity integrated micro/nano Hall magnetometer to study the static and dynamic magnetic properties of a small array of, even an individual, transition metal-doped InAs quantum dots. This grant supports directly the research and education of a PhD students and indirectly other students already involved in this project. It affords them the opportunity to interact closely with the students and researchers at the Institute of Semiconductors, a premiere materials research institution in China.