CDS&E: Coupled Thermal, Piezoelectric, and Hot Carrier Effects in AlGaN/GaN HEMTs: Multiscale Modeling of Time Evolution of Device Degradation

CDS

• 批准号: 1610474
• 负责人: Shaikh Ahmed
• 金额: $ 28.28万
• 依托单位: Southern Illinois University at Carbondale
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1610474&HistoricalAwards=false
• 关键词: CDS& Coupled; Thermal; Piezoelectric; Hot

High electron mobility transistors (HEMTs) based on nitride material systems feature a unique combination of high breakdown voltage, high output power, high efficiency, wide bandwidth, low noise, and temperature and radiation hardness and have great potential in applications such as wireless communication, homeland security, radar and satellite systems, as well as emerging harsh-environment computing, sensing, cloud-networking and power conversion electronics. However, issues related to long-term reliability of these devices still remain a major concern. Reliability can be defined as the probability of operating a system for a given time under specified conditions without failure. For semiconductor devices, unrecoverable change of a device parameter (such as degradation in the output current) may be considered as a failure. As evidenced in recently reported stress or accelerated tests, high temperature gradients (thermal effect), high electric fields and built-in or induced mechanical stresses (inverse piezoelectric effect), and high current densities (hot carrier effect) may all induce damages or defects in the constituent materials and ultimately lead to device failure. Yet, the exact physical mechanisms governing the defect formation as well as the nature and distribution of these defects are still not clearly understood. This poses a significant challenge to not only interpreting the experimental results but also predicting or extrapolating the device lifetime, tasks that are critical, for example, for devices used in remote applications. It is well acknowledged that to study physical processes that are experimentally intractable, numerical modeling becomes essential. This project sets out to develop a multiscale and multiphysics simulation framework for modeling the time evolution of and the physical mechanisms responsible for AlGaN/GaN HEMT degradation. The developed simulator will enable device design for improved reliability. The simulator and the related instructional materials will be deployed and made freely available on nanoHUB.org for the broader community to use in research and classroom activities. The objective of the proposed research is to develop a multiscale, multiphysics simulation framework (HEMT 3-D) for modeling device degradation mechanisms in AlGaN/GaN HEMTs. Specific fundamental issues to be addressed include: a) correlation between metal diffusion, polarization, and induced charge density, b) origin, spatial and temporal distribution of defects, and how they affect electrostatics, band structure, gate leakage, carrier deconfinement and trapping-detrapping and contact resistances, c) correlation between lattice heating and hot-electron injection into the barrier material, d) strain and inverse-piezoelectric effects and their temperature dependence, and e) device optimization through engineering geometry, material composition, channel orientation, and enhancement of heat transfer at barrier-channel and buffer-substrate interfaces via microscopic tuning of the interface characteristics. To properly treat the atomistic symmetry in the nanostructured active region as well as the underlying physical processes that are complex, nonlinear, highly stochastic and dynamically-coupled at different length and time scales, the simulator will employ a modular approach integrating first-principles molecular dynamics, lattice kinetic Monte Carlo, and quantum-corrected electron-phonon transport kernels. Portability and run-time efficiency of the simulator will be achieved through the use of open-source scientific software, compilers and libraries, as well as incorporating optimized models, algorithms and extensions for GPGPU platforms. Verification of the computational results will be considered at every stage of the software development effort against experimental data available in literature as well as through collaboration with experimentalists in research laboratories, academia and industries.

基于氮化物材料体系的高电子迁移率晶体管（HEMT）具有高击穿电压、高输出功率、高效率、宽带宽、低噪声以及耐高温和耐辐射等独特组合，在无线通信、国土安全、雷达和卫星系统，以及新兴的恶劣环境计算、传感、云网络和功率转换电子产品。然而，与这些设备的长期可靠性相关的问题仍然是一个主要问题。可靠性可以定义为在指定条件下给定时间内操作系统无故障的概率。对于半导体器件，器件参数发生不可恢复的变化（例如输出电流的退化）可以被视为故障。正如最近报告的应力或加速测试所证明的那样，高温度梯度（热效应）、高电场和内置或感应机械应力（逆压电效应）以及高电流密度（热载流子效应）都可能引起损坏或缺陷并最终导致器件故障。然而，控制缺陷形成的确切物理机制以及这些缺陷的性质和分布仍不清楚。这不仅对解释实验结果，而且对预测或推断设备寿命、对于远程应用中使用的设备等至关重要的任务提出了重大挑战。众所周知，为了研究实验上难以处理的物理过程，数值模拟变得至关重要。该项目旨在开发一个多尺度和多物理场仿真框架，用于对 AlGaN/GaN HEMT 退化的时间演化和物理机制进行建模。开发的模拟器将使设备设计能够提高可靠性。模拟器和相关教学材料将在 nanoHUB.org 上部署并免费提供，供更广泛的社区在研究和课堂活动中使用。本研究的目标是开发一个多尺度、多物理场仿真框架 (HEMT 3-D)，用于对 AlGaN/GaN HEMT 中的器件退化机制进行建模。 要解决的具体基本问题包括：a) 金属扩散、极化和感应电荷密度之间的相关性，b) 缺陷的起源、空间和时间分布，以及它们如何影响静电、能带结构、栅极泄漏、载流子解禁和捕获。去俘获和接触电阻，c) 晶格加热和热电子注入势垒材料之间的相关性，d) 应变和逆压电效应及其温度依赖性，以及 e) 通过工程几何、材料成分、沟道取向和增强热量通过界面特性的微观调节在势垒通道和缓冲基底界面处进行传输。为了正确处理纳米结构活性区域的原子对称性以及不同长度和时间尺度下复杂、非线性、高度随机和动态耦合的底层物理过程，模拟器将采用集成第一原理分子动力学的模块化方法、晶格动力学蒙特卡罗和量子校正电子声子输运核。模拟器的可移植性和运行时效率将通过使用开源科学软件、编译器和库以及结合 GPGPU 平台的优化模型、算法和扩展来实现。在软件开发工作的每个阶段，都将根据文献中提供的实验数据以及通过与研究实验室、学术界和工业界的实验人员合作来考虑计算结果的验证。