Intrinsic Vacancy Chalcogenides for Spintronic Applications

技术：本项目旨在对本征空位硫族半导体进行基本的理解和改进，以用于硅兼容、自旋电子应用。实验计划(i)在A2 III B3 VI半导体（主要是Ga2Se3）中加入过渡金属（TM）杂质，以开发新的稀释磁性半导体；（ii）调节界面动力学和化学计量学，以控制这些新材料在硅衬底上外延生长时的能带对准。这些大部分未开发的材料的结构-性质关系将通过各种表征工具进行研究，包括原位扫描探针显微镜，光电子能谱，x射线吸收光谱和非原位传输，磁强计，x射线和光学测量，结合理论计算。该方法是探索新型稀磁半导体的物理和材料科学，其中量子现象的观察需要高材料质量，器件应用的可能性由纳米级物理控制。内生性空位硫族化合物具有灵活的键约束和可通过异质外延生长控制的磁掺杂掺杂的多个位点。由此产生的结构可调性创建了一个模型系统来测试稀磁系统中提出的磁机制。这项研究有望推动对控制本征空位化合物的能带偏移和薄膜形态的纳米级机制的认识。计划进行研究，以(i)确定自由载流子和缺陷在控制这些材料中的磁性方面的相对重要性，其中载流子、磁性物质和缺陷浓度可以独立控制；（ii）研究混合价态杂质和本征结构空位在控制纳米结构形态和掺杂位点方面的作用；（iii）探索界面化学计量在控制硅和这些极性异价材料之间的能带偏移和自旋极化输运的可能性方面的作用。预期的成果包括理解一类新型的、硅兼容的、稀磁性半导体，用于基于电子自旋的新器件技术；以及不同材料界面带偏控制方法的发展。非技术：该项目涉及材料科学主题领域的基础研究问题，具有很高的潜在技术相关性。该研究将在基础水平上为材料科学知识提供新的理解和电子器件的能力。该研究促进了硅基技术的进一步小型化和多功能化。该计划的一个重要特点是通过培养学生在一个基础和技术上重要的领域的研究和教育的整合。本科、硕士、博士和博士后水平的学生将学习如何在学科和文化之间架起桥梁，因为他们在新范式、新科学和新技术的发展中，在科学和工程的界面上工作。通过直接参与研究前沿，学生将获得必要的，可转移的技能，为他们未来参与科学和技术劳动力。该项目通过主要研究人员参与纳米技术博士项目（IGERT）、华盛顿大学/PNNL纳米科学联合研究所和本科生暑期研究经验，加强了美国国家科学基金会在华盛顿大学（UW）资助的其他教育工作。主要研究人员已经表明了促进妇女和少数民族参与科学和工程的承诺，包括开发有关这些问题的课程和系列讲座，参与西澳大学少数民族科学和工程项目和新的集中科学和工程少数民族研究生招聘，服务于西澳大学NSF-ADVANCE领导团队，并在社区科学教育项目中工作。通过这一研究项目获得的专门知识和知名度为这种外联和教育活动的成功提供了协同基础。

Technical: This project aims for fundamental understanding and modification of intrinsic-vacancy chalcogenide semiconductors for silicon compatible, spintronic applications. Experiments are planned to (i) incorporate transition metal (TM) impurities in A2 III B3 VI semiconductors, principally Ga2Se3, towards development of new dilute magnetic semiconductors and (ii) modulate interface kinetics and stoichiometries to control the band alignment when these new materials are grown epitaxially on a silicon substrate. Structure-property relationships of these largely unexplored materials will be investigated with a variety of characterization tools, including in situ scanning probe microscopy, photoelectron spectroscopy, and x-ray absorption spectroscopy and ex situ transport, magnetometry, x-ray and optical measurements, combined with theoretical calculations. The approach is to explore the physics and materials science of novel dilute magnetic semiconductors, where observation of quantum phenomena requires high materials quality and possibilities for device applications are controlled by nanoscale physics. Intrinsic vacancy chalcogenides contain flexible bonding constraints and multiple sites for magnetic dopant incorporation that may be controlled through heteroepitaxial growth. The resultant structural tunability creates a model system to test proposed magnetic mechanisms in dilute magnetic systems. This research is expected to advance knowledge regarding nanoscale mechanisms for controlling band offsets and film morphologies in intrinsic vacancy compounds. Research studies are planned to (i) determine the relative importance of free carriers and defects in controlling magnetism in these materials where carrier, magnetic species, and defect concentrations may be controlled independently; (ii) investigate the roles of mixed valence impurities and intrinsic structural vacancies in controlling nanostructure morphology and sites for dopant incorporation; and (iii) explore the role of interface stoichiometry in controlling both the band offset and the possibility of spin-polarized transport between silicon and these polar heterovalent materials. Anticipated outcomes include understanding of a new class of novel, Si-compatible, dilute magnetic semiconductors for use in new device technologies based on electron spin; and development of the means to control band-offsets at dissimilar materials interfaces. Non-Technical: The project addresses basic research issues in a topical area of materials science having high potential technological relevance. The research will contribute materials science knowledge at a fundamental level to new understanding and capabilities in electronic devices. The research promotes further miniaturization and multifunctionalization of Si-based technologies. 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. Students at the undergraduate, masters, doctoral and post-doctoral level will learn to bridge disciplines and cultures as they work at the interface between science and engineering in the development of new paradigms, new science and new technologies. Through direct participation at the research frontier, students will acquire essential, transferable skills for their future participation in the scientific and technological workforce. The project strengthens other NSF-funded education efforts at the University of Washington (UW) through the principal investigators' involvement in the Nanotechnology Ph.D. Program (IGERT), UW/PNNL Joint Institute for Nanoscience, and Summer Research Experience for Undergraduates. The principal investigators have demonstrated commitment to advancing the participation of women and minorities in the sciences and engineering, including developing a course and lecture series on these issues, participating in the UW Minority Science and Engineering Program and new centralized science and engineering minority graduate student recruiting, serving on UW's NSF-ADVANCE leadership team, and working in community science education projects. Expertise and visibility gained through this research project provides a synergistic basis for success of such outreach and educational activities.