Materials World Network: Complex oxides for heterogeneous optoelectronic integration

该项目旨在通过材料研究为半导体系统带来新的功能，以确定将复杂氧化物包层集成到半导体结构（如波导）上的路径。作为美国PI，来自明尼苏达州的Stadler为合作带来了氧化物集成方面的专业知识，以及最近经过验证的控制热应变的工艺，以在半导体平台上实现高质量的氧化物。作为英国PI，来自格拉斯哥的Hutchings为合作带来了III-V族半导体制造和加工方面的专业知识，包括准相位匹配的设计，以消除结构双折射效应。该团队将共同为对电子、光子学、传感器和不可想象的未来领域感兴趣的设计师的调色板添加新材料。开始，这项合作将集中在增加磁光（MO）和电光（EO）性能，通过将掺杂的钇铁石榴石（YIG）和锂酸盐（LNO）分别集成到III-V结构上，这些性能比目前半导体的性能高出几个数量级。随着诸如源集成光子集成电路（PIC）和电子可重构光电子集成电路（OEIC）的动机，在将MO和EO材料添加到半导体平台上已经进行了热烈的工作。然而，这些领域的大多数研究人员都专注于器件设计，并且由于复杂氧化物集成的困难而感到沮丧，其中需要热结晶方法以及热膨胀失配，衬底解离和界面扩散。在这里，我们建议使用经典的材料四面体（处理，结构，属性，性能），以快速收敛到一个解决方案，涉及控制应变和界面，使用缓冲层和种子层（均为~ 10 nm），氧化物图案化和快速热退火，以最大限度地减少热处理。在较厚的膜中的后续掺杂可以用于满足最大化MO或EO活性的规格，并且同时优化处理以获得优化的膜晶体结构。光学、磁性和电子特性将被表征以分析最佳结构和成分，并且材料性能将在设计用于消除结构本身的影响的简单波导结构上进行测试。在Stadler和Hutchings的初步合作中，这个过程的基本原理已经用未掺杂的YIG得到了证明。该项目将确定他们的工艺是否可以扩展到掺杂YIG（有望使MO活性增加10- 100倍）和LNO的集成。在MO集成的情况下，非互易性最终将在没有一些研究人员目前提出的高功率选项的情况下实现。这意味着，类似于电子二极管，隔离器将成为可能，光源可以与PIC集成-这一发展将立即彻底改变光子学和设计师开始梦想的其他领域。集成铁电氧化物还将开启在近期和长期应用中从未探索过的EO功能的大门，例如有源频率调制和可重构光子学。除了将III-V平台与复杂氧化物相结合的科学效益外，这种美英合作还将在更广泛的意义上增加价值。在线小组会议将利用UMConnect和PaperShow的网络会议，使与会者能够看到彼此的面孔、文字和幻灯片，并听到彼此的声音。学生之间通过skype视频会议进行实时实验交流，将使这项研究快速发展。这一在线互动的结果将通过MRS材料教育专题讨论会传播。我们还计划进行学生/初级研究人员交流。

This project proposes to bring new functionalities to semiconductor systems by using materials research to identify paths of integration for complex oxide claddings onto semiconductor structures, such as waveguides. As the US PI, Stadler from Minnesota brings to the collaboration an expertise in oxide integration with recently proven processes for controlling thermal strain to achieve high-quality oxides on semiconductor platforms. As the UK PI, Hutchings from Glasgow brings to the collaboration an expertise in III-V semiconductor fabrication and processing, including design of quasi phase matching to enable cancellation of structure birefringence effects. Together, this team will add new materials to the palettes of designers interested in electronics, photonics, sensors, and unimagined future areas. To begin, this collaboration will focus on adding magneto-optical (MO) and electro-optical (EO) properties that are orders of magnitude greater than currently available to semiconductors by integrating both doped yttrium iron garnet (YIG) and lithium niobate (LNO), respectively, onto III-V structures.Intellectual Merit. With motivations such as source-integrated photonic integrated circuits (PICs) and electronically-reconfigurable opto-electronic integrated circuits (OEICs), there has been heated work on adding MO and EO materials to semiconductor platforms. However, most researchers in these areas have focused on device design and have been frustrated by the difficulty involved in complex oxide integration where there exists a need for thermal crystallization methods together with thermal expansion mismatch, substrate dissociation, and interfacial diffusion. Here, we propose to use the classic materials tetrahedron (processing, structure, properties, performance) to rapidly converge on a solution involving controlled strain and interfaces using buffer layers and seed layers (both~10nm), oxide patterning, and rapid thermal annealing for minimized thermal treatment. Subsequent doping in thicker films can be used to meet specifications of maximized MO or EO activity, and while the processing is optimized to obtain the optimized film crystal structures. The optical, magnetic, and electronic properties will be characterized to analyze the optimal structures and compositions, and the materials performance will be tested on simple waveguide structures designed to cancel the effects of the structures themselves. The fundamentals of this process have been proven with undoped YIG in a preliminary collaboration between Stadler and Hutchings. This project will determine if their process can be extended to the integration of doped YIG (promising 10-100x increase in MO activity) and of LNO. In the case of MO integration, non-reciprocity will finally be realized without the high-power options currently being proposed by some researchers. This means that, analogous to electronic diodes, isolators will be possible and optical sources can be integrated with PICs- a development that will revolutionize photonics immediately and other fields as designers begin to dream. Integrated ferroelectric oxides will also unlock doors to never explored EO functionality in both near and long term applications, such as active frequency modulation and reconfigurable photonics.Broader Impacts. In addition to the scientific benefits of combining III-V platforms with complex oxides, value will be added by this US-UK collaboration in a broader sense. Online group meetings will utilize web-meetings with UMConnect and PaperShow to enable attendees to see each other's faces, writings and slides and to hear each other's voices. Individual skype video-conferencing between students for real-time experimental exchange will allow rapid advances of this research. The findings of this online interaction will be disseminated via the MRS materials education symposia. We also have planned for student/junior researcher exchange.