Materials World Network: Engineering the Spintronic Properties of Semiconductor Quantum Dots

来自美国、巴西、加拿大和阿根廷的匹兹堡大学的科学家将研究专门为自旋电子和量子信息应用量身定制的工程量子点系统，该系统由材料研究部的电子材料项目和国际科学与工程办公室的美洲项目共同资助。这个与匹兹堡大学、巴西国家实验室、圭尔夫大学和阿根廷布宜诺斯艾利斯大学的科学家合作的项目将开发两种材料系统：InAs:GaAs和Ge:Si量子点。在自旋电子应用方面，每个系统都有其独特的优势和挑战，以及这些特性可以通过生长来控制的程度。InAs:GaAs量子点将使用一种方法来生长，这种方法将产生密度可以在两个数量级以上变化的高度单分散量子点。Ge:Si量子点将使用一种新的方法来生长，在这种方法中，SiC纳米模板被可控地放置在Si（100）的表面上，然后在模板表面上“定向”自组装Ge岛。这些量子点的表征将以各种互补的方式进行，包括隧道显微镜/光谱学，光致发光/吸收光谱学和电容电压测量（提取量子点的g张量并确定电子占用）。高分辨率x射线测量将提供有关量子点内部组成的关键结构信息。将开发用于在量子点中产生、操纵和测量自旋的原型自旋电子设备。这些简单的设备将用于测量自旋相干时间，单量子点中的g张量调制共振，以及测试单电子自旋读出机制（使用在微波频率下测量的自旋相关隧道）。提出的研究重点是定制半导体量子点的生长，以优化自旋电子和量子信息应用的性能。在过去的二十年里，控制量子点的特性一直是材料科学的首要目标。自旋电子学和基于自旋的量子信息科学与技术共享广泛的国际关注，拟议的合作将使美洲内部的联系正式化并加强。研究生可能会从这个国际合作项目中获得最大的好处。在出国旅行期间，学生们将分享他们的专业知识、文化、科学方法以及他们的知识和文化视野。在这个交流项目中培养的纽带旨在贯穿整个职业生涯。

With this Materials World Network award to University of Pittsburgh scientists from US, Brazil, Canada and Argentina will study engineered quantum dot systems that have been specifically tailored for spintronic and quantum information applications, and is co-funded by the Electronic Materials program in the Division of Materials Research and the Americas program in the Office of International Science and Engineering. This collaborative project with scientists from University of Pittsburgh, Laboratorio Nacional de Luz Sincrotron (Brazil), University of Guelph (Canada), and University of Buenos Aires (Argentina) will develop two material systems: InAs:GaAs and Ge:Si quantum dots. Each system has unique strengths and challenges in terms of spintronic applications, and the degree with which these properties can be manipulated through growth. InAs:GaAs quantum dots will be grown using an approach that will create highly monodisperse quantum dots with densities that can be varied over two orders of magnitude. Ge:Si quantum dots will be grown using a novel approach in which SiC nanotemplates are placed controllably on the surface of Si(100), followed by "directed" self-assembly of Ge islands on the templated surface. Characterization of these dots will be performed in a variety of complementary ways, including tunneling microscopy/spectroscopy, photoluminescence/absorption spectroscopy, and capacitance-voltage measurements (to extract the g-tensor of quantum dots as well as determine the electron occupancy). High-resolution x-ray measurements will provide crucial structural information about the internal composition of the quantum dots. Prototype spintronic devices will be developed for producing, manipulating and measuring spin in quantum dots. These simple devices will be used to measure spin coherence times, g-tensor modulation resonance in single quantum dots, and test mechanisms for single electron spin readout (using spin-dependent tunneling measured at microwave frequencies).The proposed research focuses on tailoring the growth of semiconductor quantum dots in order to optimize properties for spintronic and quantum information applications. Control over the properties of quantum dots has been a foremost goal in material science over the last two decades. Spintronics and spin-based quantum information science and technology share widespread international attention, and the proposed collaboration will formalize and strengthen the ties within the Americas. Graduate students are likely to receive the greatest benefit from this international collaborative program. During their trips abroad, students will share their expertise, cultures, approaches to science, and their intellectual and cultural horizons. The bonds fostered within this exchange program are designed to endure throughout an entire professional career.