Materials World Network: Science of Polar Homo- and Heterointerfaces

一个有重点的国际研究合作，连接北卡罗来纳州州立大学，技术大学柏林（TUB）和莱布尼茨研究所für Kristallzüchtung（IKZ）在柏林，德国，探索外延界面的基础科学，定义了在氮化物-氮化物和氮化物-氧化物系统的电极化的不连续性。其目的是了解调节界面电子性质的结构，化学和电子特征。这项工作是基于一个假设，即垂直和横向异极接口，接近“超导级”的质量可以准备，他们的研究将导致令人兴奋的机会，在界面物理学和光学/电子功能的根本进步。国际团队的每个成员都带来了独特和领先的技术能力，共同实现了这项研究。西塔乐队（NC State）带来了一种金属有机化学气相沉积技术，可以在横向和纵向上控制氮化物半导体薄膜的极性; Maria集团（NC State）开发了一种表面辅助分子束外延技术，该技术首次可以在GaN表面上制备具有二维生长模式的立方氧化物，并显著降低了缺陷浓度;霍夫曼小组（TUB）带来了极性材料和异质结构的光学表征;阿尔布雷希特小组（IKZ）带来了具有亚Å空间分辨率和亚eV能量分辨率的像差校正透射电子显微镜表征。这项研究改进了合成技术，使混合薄膜结构能够无缝地将氧化物和氮化物与迄今为止无法实现的材料质量结合起来。通过结合合成和表征，研究人员能够识别和理解的结构和化学特征，使，干扰，或增强异极界面耦合。实现异极界面性质的关系的理解将推动研究在混合系统，导致新的物理，新的功能，一套扩展的低维光电器件，以及以新的方式利用铁电体的非线性介电响应的智能结构的途径。通过这种合作，来自NCSU，TUB和IKZ的学生和教师可以获得技术领域的指导专业知识和世界一流的实验室设施。美国和德国的学生在第三年参加为期6个月的研究生休假，以确保实质性的国际经验。在他们的头两年，鼓励美国学生参加两个学期的德语学习，以获得基本的沟通技巧。德国参与者的工作得到了德国研究基金会（DFG）的支持。

A focused international research collaboration linking North Carolina State University, the Technical University Berlin (TUB) and the Leibniz-Institut für Kristallzüchtung (IKZ) in Berlin, Germany, explores the fundamental science of epitaxial interfaces that define a discontinuity in electrical polarization in nitride-nitride and nitride-oxide systems. The aim is to understand the structural, chemical, and electronic features that regulate the interfacial electronic properties. The effort is based on a hypothesis that vertical and lateral heteropolar interfaces that approach 'semiconductor-grade' quality can be prepared, and that their study will lead to exciting opportunities for fundamental advances in interface physics and optic/electronic functionality. Each member of the international team brings a unique and leading edge technical capability that collectively enables this research. The Sitar group (NC State) brings a metalorganic chemical vapor deposition technology that can control polarity in thin films of nitride semiconductors both laterally and vertically; the Maria group (NC State) developed a surfactant-assisted molecular beam epitaxy technique that can for the first time prepare cubic oxides on GaN surfaces with a 2-D growth mode and dramatically reduced defect concentrations; the Hoffmann group (TUB) brings in optical characterization of polar materials and heterostructures; and the Albrecht group (IKZ) brings aberration-corrected transmission electron microscopy characterization with sub-Å spatial resolution and sub-eV energy resolution. The research refines synthesis techniques that enable hybrid thin film structures that seamlessly merge oxides and nitrides with heretofore unachievable material quality. By combining synthesis and characterization the investigators are able to identify and understand the structural and chemical features that enable, interfere, or enhance heteropolar interface coupling.Achieving an understanding of heteropolar interface-property relationships will propel research in hybrid systems that lead to new physics, new functionality, an expanded set of low dimension optoelectronic devices, and a pathway to smart structures that utilize in a new way the non-linear dielectric response of ferroelectrics. Through this collaboration, students and faculty from NCSU, TUB, and IKZ have access to mentoring expertise and world-class laboratory facilities in technical areas that are absent from the home institutions. U.S. and German students participate in a 6-month graduate sabbatical in program year three to ensure substantive international experience. During their first two years, U.S. students are encouraged take two semesters of German to acquire basic communication skills. The work of the German participants is supported by the German Research Foundation (DFG).