CAREER: A multi-scale and hierarchical computational framework to model III-nitride devices operating in the near-terahertz regime

宽和超宽带隙iii -氮化物半导体具有满足带宽超过100千兆赫的近太赫兹通信系统功率和频率要求的基础能力。iii -氮化物也可以很好地用于极端环境，从低温极限到高温。然而，目前iii -氮化物器件的演示性能仍低于理论预期，iii -氮化物在近太赫兹应用中的前景仍未实现。然而，孤立于理论进步的实验进展不太可能改变这种现状。为了应对这一挑战，在本研究中，我们将创建一个多尺度和分层计算框架，该框架将提供对不同长度、时间和温度尺度下iii -氮化物器件的底层物理的高保真度见解。这些基本见解对于确定材料和设备级的进步至关重要，这些进步将推动基于iii -氮化物的无线技术的发展，无论是商业无线通信还是极端环境下的科学研究。这项研究将对医疗保健、能源、交通、空间计划以及社会和教育进步等领域产生深远的影响。这里开发的模型将是完全开源的，可供世界各地的研究人员使用，从而扩大了这项研究的规模和影响。我们将为中学生开设一个以半导体为重点的课外夏令营，并与大学的包容性、多样性、公平和准入研究所合作，在本系和我们的研究实验室招募低收入和少数民族学生。将开发基于网络的半导体物理学习图书馆，鼓励学生创造性地思考下一代电子系统中半导体的可能性。这项研究、推广和教育计划的成功有望带来数十年的富有成效的基础知识，有助于转化为重要的近太赫兹技术，并激励电气工程师、材料科学家和物理学家组成的多元化社区的参与和保留。建模和仿真工具是基于物理和应用驱动的器件和电路设计的基石。由于iii -氮化物器件旨在用于高场和高频应用，目前的模型忽略了麦克斯韦的全波效应和全频带物理，无法指导实验进行技术优化，也无法充分探索材料到电路的设计空间，而这对于满足目标性能指标是非常理想的。因此，可以肯定地说，对iii -氮化物器件计算方法的根本性反思将改变无数近太赫兹应用的游戏规则，这些应用可以解决当前和未来时代的一些最大挑战。在这项研究中，我们将创建一个多尺度计算框架，通过数值传输模拟将第一性原理计算结合到紧凑的电路模型中。该框架将确定新的理论手段来询问和控制近太赫兹iii -氮化物器件的高频和非平衡物理。该计算框架的显著特征包括全电子带结构、热电子效应、自热、量子力学散射、电荷俘获、低温物理和全波电磁学。由于数值框架将与spice兼容并经过实验验证的紧凑模型相辅相成，因此提出的研究将使大规模电路模拟和系统设计成为可能。这项研究的结果将使许多利益相关者受益，从材料科学家到电路设计师，并实现跨学科的互动，这将为宽和超宽带隙半导体的多代研究奠定全球舞台。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Wide and ultrawide bandgap III-nitride semiconductors have the foundational capability to meet the power and frequency requirements of near-terahertz communication systems with bandwidths exceeding 100 gigahertz. III-nitrides are also well positioned to be used in extreme environments, from the cryogenic limit to high temperatures. However, the demonstrated performance of III-nitride devices today is still below theoretical expectations, and the promise of III-nitrides for near-terahertz applications remains unfulfilled. Still experimental advances in isolation of theoretical advances are unlikely to change this existing landscape. To tackle this challenge, in this research, we will create a multi-scale and hierarchical computational framework that will provide a high fidelity insight into the underlying physics of III-nitride devices at different length-, time-, and temperature-scales. These fundamental insights are crucial for identifying material- and device-level advances that will push the bounds of III-nitrides’ based wireless technologies, be it for commercial wireless communication or scientific investigations in extreme environments. This research will have a far reaching impact in areas like healthcare, energy, transportation, space programs, and social and educational advancements. The models developed here will be fully open-source and available to researchers world-wide, amplifying the scale and impact of this research. We will inaugurate an afterschool semiconductors-focused summer camp for middle school students and collaborate with the Inclusivity, Diversity, Equity and Access Institute at the University to recruit low-income and minority students in the department and in our research lab. Web-based learning library on semiconductor physics will be developed to encourage students to think creatively about the possibilities of semiconductors in next-generation electronic systems. The success of this research, outreach and educational plan holds promise to result in decades of productive fundamental knowledge, contribute to translation into important near-terahertz technologies, and motivate the participation and retention of a diverse community of electrical engineers, materials scientists, and physicists.Modeling and simulation tools are the cornerstones of the physics-based and application-driven device and circuit design. Because III-nitride devices are intended for use in high-field and high-frequency applications, current models that neglect Maxwell’s full-wave effects and full-band physics fail at guiding experiments for technology optimization and cannot fully explore the materials-to-circuit design space, which is highly desirable for meeting target performance metrics. Thus, it is safe to say that a fundamental rethinking of computational methodologies for III-nitride devices will be a game-changer for a myriad of near-terahertz applications that can address some of the biggest challenges of current and future times. In this research, we will create a multi-scale computational framework that combines first-principles calculations through numerical transport simulations to a compact circuit model. This framework will identify new theoretical means to interrogate and control the high-frequency and off-equilibrium physics of the near-terahertz III-nitride devices. Salient features of this computational framework include full electronic bandstructure, hot-electron effects, self-heating, quantum-mechanical scattering, charge trapping, low-temperature physics, and full-wave electromagnetics. Because the numerical framework will be complemented with a SPICE-compatible and experimentally validated compact model, the proposed research will enable large-scale circuit simulations and systems design. The outcomes of this research will benefit many stake holders, from material scientists to circuit designers, and enable cross-disciplinary interactions that will set the global stage for multi-generational research in wide and ultrawide bandgap semiconductors.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.