Synergistic experimental and theoretical studies of the growth and characterization of near-single crystal semiconductors on glass

摘要技术：本项目旨在对在玻璃等非晶质衬底上生长近单晶Ge进行基础性研究。玻璃衬底没有有序的原子晶格，因此不能诱导外延半导体的生长。一个关键的挑战是，是否有可能在玻璃上生长出单晶膜。在这个项目中，我们建议在玻璃上使用一个双轴CaF2缓冲层来诱导近单晶Ge薄膜的外延生长。双轴CaF2层具有很强的面外和面内织构取向，将采用斜角沉积技术生长。本研究的目的是：(A)了解在双轴CaF2缓冲层上异质外延生长近单晶Ge薄膜的基本机制，(B)表征外延Ge薄膜的结构缺陷和电子性质，以及(C)利用经典和量子力学原子方法了解Ge薄膜中缺陷的基本性质，特别是小角度晶界。人们期望这些近单晶的Ge薄膜可能具有比传统方法在玻璃上制备的颗粒随机取向的多晶薄膜更好的器件质量特性。这项研究提出的策略是稳健的，可能会刺激更多关于在非晶质衬底上生长其他半导体的研究。非技术性：到目前为止，高性能半导体器件是由在单晶衬底上生长的单晶半导体薄膜制成的。然而，对于显示器和太阳能电池等大面积应用来说，单晶基板太贵了。大多数低成本的商用大面积器件要么是由玻璃或金属基板上的多晶或非晶态半导体制成的，要么效率不理想，而且存在长期稳定性问题。在这个项目中，PI的目标是创造一种近乎单晶的半导体薄膜，例如生长在玻璃上的Ge。通过这项研究获得的知识可以帮助研究人员设计和功能化织构，以获得理想的薄膜物理性能。预计这些近单晶半导体薄膜将具有比传统方法在玻璃上沉积的薄膜更好的性能，以用于大面积电子应用。这项跨学科工作、研究将与教育和外联活动相结合。除了培训研究生，通过NSF-REU和伦斯勒赞助的URP(本科生研究参与)计划支持的学生也将参与研究。外展活动将包括开放参观和在校园内为高三/高年级学生提供暑期计划。这些努力将提高和激发学生追求科学或工程职业的兴趣。

AbstractTechnical: This project aims at the fundamental study of the growth of near-single crystal Ge on non-crystalline substrates such as glass. A glass substrate does not have a well ordered atomic lattice and therefore cannot induce the growth of epitaxial semiconductors. A key challenge is whether it is possible to grow a single crystal film on glass at all. In this project it is proposed to use a biaxial CaF2 buffer layer on glass to induce an epitaxial growth of near-single crystal Ge films. The biaxial CaF2 layer, which possesses strong out-of-plane and in-plane texture orientations, will be grown using an oblique angle deposition technique. The aims of the proposed research are to (a) understand the fundamental mechanism of the heteroepitaxial growth of near-single crystal Ge films on biaxial CaF2 buffer layer, and (b) to characterize the structural defects and electronic properties of the epitaxial Ge films, and (c) to understand the fundamental nature of the defects in the Ge films, in particular, the small angle grain boundaries, using classical and quantum mechanical atomistic methods. The expectation is that these near-single crystal Ge films may possess superior device quality properties compared to those polycrystalline films fabricated by conventional means on glass where the grains are randomly oriented. The strategy proposed in this research is robust and may stimulate more study on the growth of other semiconductors on amorphous substrates.Nontechnical: To date, high performance semiconductor devices are made out of single crystal semiconductor films grown on single crystal substrates. However, single crystal substrates are too expensive for large area applications such as display and solar cells. Most low-cost commercial large area devices are made of either polycrystalline or amorphous semiconductors on glass or metal substrates with less than ideal efficiency and long term stability problems. In this project the PIs are aiming to create a near-single crystal semiconductor films such as Ge grown on glass. The knowledge gained from this study can aid researchers to design and functionalize textures to obtain the desirable physical properties of thin films. It is projected that these near-single crystal semiconductor films should possess substantially better performance than that of the films deposited by conventional means on glass for large area electronics applications. This interdisciplinary work, research will be integrated with education and outreach activities. In addition to training graduate students, students supported through the NSF-REU and Rensselaer-sponsored URP (Undergraduate Research Participation) programs will also participate in the research. Outreach activities will include open houses and summer programs on campus for high school juniors/seniors. These efforts will enhance and stimulate students' interest in pursuing science or engineering careers.