Closed-Loop Experiment-Simulation Approach to Designer Materials: GaAsSbBi for Optoelectronics.

非技术性描述：国家对在红外和远红外范围内工作的高效光电器件有着强烈的需求。红外光源和探测器的应用包括夜视和监视、无线通信以及化学和生物传感。目前大多数红外应用依赖于昂贵和危险的材料。含铋的III-V族半导体是无毒的，并且可以直接集成到现有的制造线中，进一步降低成本。然而，由于Bi与这些化合物中的其他元素的复杂相互作用，生长这些材料是不平凡的。在本计画中，研究含铋化合物半导体的成长与光学性质，并将其应用于红外线侦测器。进行这项研究的模式也很重要，因为它结合了实验和计算方法，以加快发现的步伐。该项目还开发了在各种情况下使用的教学模块，从而扩大了我们的教育基础设施，扩大了代表性不足的群体对科学和工程相关专业的参与。技术说明：这项研究的新奇在于在研究未知和高度复杂的合金系统时将实验与计算相结合。一个计算验证周期是用来建立的生长参数，并获得具有所需的晶格参数和能带结构的薄膜。从头算统计力学结合了密度泛函理论、簇展开和统计蒙特-卡罗来计算平衡性质，包括GaAsSbBi合金的能带结构。在串联，基于动力学蒙特卡罗的增长建模用于了解偏离平衡行为。采用了用于生长（分子束外延）和原子尺度表征（原子探针层析、X射线衍射、卢瑟福背散射等）的稳健实验方法。使用实验与计算相结合，大大减少了参数空间，加快了这类适用于红外设备的新材料的优化路径。

Nontechnical description: There is a strong national need for efficient optoelectronic devices that operate in the infrared and far infrared regime. Applications for infrared sources and detectors include night vision and surveillance, wireless communication, and chemical and biological sensing. Most current infrared applications rely on expensive and hazardous materials. Bismuth containing III-V semiconductors are non-toxic and may be directly integrated into existing fabrication lines, further reducing cost. However, growing these materials is nontrivial due to the complex interactions of Bi with the other elements in these compounds. In this project, the growth and optical properties of Bi-containing compound semiconductors are examined with an eye on infrared detector applications. The mode in which this research is performed is also important, because it combines experimental and computational methods to speed the pace of discovery. This project also develops pedagogical modules that are used in a variety of situations, thus augmenting our infrastructure for education and broadening the participation of underrepresented groups in science and engineering related majors. Technical description: The novelty of this research is in coupling experiments with computations when studying an unknown and highly complex alloy system. A calculate-verify cycle is used to establish the growth parameters and to obtain films that have the desired lattice parameter and band structure. ab initio statistical mechanics combines Density Functional Theory, cluster expansions, and statistical Monte-Carlo to calculate the equilibrium properties, including band structure of the GaAsSbBi alloy. In tandem, growth modeling based on kinetic Monte Carlo is used to understand deviations from equilibrium behavior. Robust experimental methods for the growth (Molecular Beam Epitaxy) and atomic-scale characterization (Atom Probe Tomography, X-Ray Diffraction, Rutherford Backscattering, etc) are employed. Using experiments coupled with computation greatly reduces parameter space and speed the path to optimization of this new class of materials suitable for infrared devices.