Development of a Novel Inorganic Dielectric Barrier Layer for Magneto-Resistive Junctions

智力优势：这项研究包括制造和研究高阻B5C碳化硼作为隧道磁阻器件中介质阻挡层材料的主要新候选材料。基于他们在各种半导体应用中制造和使用B5C的独特经验，研究人员将使用这种材料来帮助理解磁体/势垒界面的基本性质，这些界面在磁电子学中非常重要，特别是自旋电子学(自旋电子学)--未来电子学中最有前途的途径之一。研究团队将利用他们在自旋分辨光电子发射方面的能力来提供关于表面电子态的信息，由于介质膜中包含这样的轻原子，因此可以访问重要的埋入地下的磁体/碳化硼界面。高分辨率电子显微镜和光谱技术将提供关于B5C多型的结构、介电和成键信息。在外加磁场下的光电导的研究将被用来更好地理解势垒中的局域杂质状态对磁阻特性的影响。控制入射光的方向和偏振将有助于识别这些状态，并提供与光电发射相关的初始数据。在介电生长过程中，磁性杂质原子将被包括进来，以便提供对势垒状态的额外控制，从而提供磁阻。由于氧化铬结的初步结果表明，可以通过改变外加电流的极性来改变结中孤岛的磁性状态，为了测试非氧化物磁性结中自旋转移的新想法，磁夹杂也将被纳入势垒中。广泛影响：该项目将培训研究生和本科生，特别是来自未被充分代表的群体的研究生和本科生，掌握复杂的实验技术，并为他们提供在顶级期刊和主要专业和工业会议上与同行、科学家和工程师交流结果的机会。这项研究将使该团队能够提高其制造碳化硼材料和器件的能力，这些材料和器件有许多应用，包括最近团队中的两名成员所证明的中子探测。制造磁性传感器或粒子探测器对确保我们国家的安全变得越来越重要，并将继续激励团队中的学生和他们的同龄人。将寻求机会鼓励工商界人士，包括通过技术转让，以及公众、立法者和学生了解结果及其社会效益。这项研究将提供对磁铁/势垒界面物理的基本了解，并提供将这种了解应用于自旋电子学的实用技术。通过在势垒中加入金属夹杂物可以获得更多的器件性能，有望刺激新的磁存储应用。最重要的是，碳化硼介质势垒的研究有望提供一种手段，避免氧化物介质势垒引起的铁磁表面态的严重降低，从而避免自旋电子学发展的一个主要问题。因此，这项研究可能为自旋电子学的一项关键使能技术提供基础。

Intellectual Merit: This research involves making and investigating high-resistivity B5C boron carbide as a major, new candidate for the dielectric barrier material in tunnel magnetoresistive devices. Based on their unique experience of making and using B5C in a variety of semiconductor applications, with chosen bandgaps from 0.9 to 2.7 eV, the investigators will use this material to help understand the fundamental properties of magnet/barrier interfaces that are highly important in magnetoelectronics and, specifically, spin electronics (spintronics) - one of the most promising future paths in electronics.The research team will use their abilities in spin-resolved photoemission to provide information on the surface electronic states and, since the dielectric film comprises such light atoms, to gain access to the important buried magnet/boron carbide interface. High-resolution electron microscopy and spectroscopy techniques will provide structural, dielectric, and bonding information on the B5C polytypes. Investigations of photoconductivity under applied magnetic fields will be used to gain better understanding of the influence of local impurity states in the barrier on magnetoresistance properties. Control of the orientation and polarization of the incident light will help identify these states and provide initial data for correlation with photoemission. Magnetic impurity atoms will be incorporated during dielectric growth in order to provide additional control of barrier states and so of magnetoresistance. Since initial results on chromium oxide junctions showed it is possible to modify the magnetic state of an island in the junctions by changing the polarity of the applied electric current, magnetic inclusions will also be incorporated in the barrier in order to test new ideas of spin transfer in non-oxide magnetic junctions.Broad Impacts: This project will train graduate and undergraduate students, particularly from underrepresented groups, in sophisticated experimental techniques and provide them with opportunities to communicate their results to peers, scientists and engineers in top journals and at major professional and industrial meetings. The research will allow the team to improve its capabilities for making boron carbide-based materials and devices, which have many applications, including neutron detection as two of the team recently demonstrated. Making magnetic sensors, or particle detectors, has become increasingly important for ensuring the security of our nation, and will continue to motivate the students on the team, and their peers. Opportunities will be sought to encourage understanding of the results, and their societal benefits, by people in business and industry, including through technology transfer, and by the general public, legislators and school students.The research will provide access to fundamental understanding of the physics of magnet/barrier interfaces and to practical technology for applying this understanding to spintronics. The additional device properties accessible by incorporating metallic inclusions in the barrier are expected to spur new magnetic memory applications.Most importantly, the research on boron carbide dielectric barriers is expected to provide a means of avoiding the serious reduction in the ferromagnet surface states caused by oxide dielectric barriers and therefore of avoiding a major problem for the development of spintronics. The research may therefore provide the basis for a key enabling technology for spintronics.