在多物理场条件下GaN基异质结构的力-热-电耦合问题及失效行为研究

Materials performance and structural macroscopic response in GaN-based hetero-structures under complex environments with multi physical fields are suffered from the multi-field coupling effects. These coupling behaviors induce to the significant impacts on designing and application of GaN-based hetero-structural devices. In this proposal, the continuum mechanics, electromagnetic theory, transport theory and atomic methods will be utilized to explore the mechanical-thermal-electric coupling effects on the mechanical and physical properties and the macroscopicresponse as well as the failure behaviors in GaN-based hetero-structures. For the mechanical, thermal and electrical properties of GaN-based hetero-structures, e.g.the elastic modulus, yield strength, the phonon thermal conductivity, electrical conductivity and carriers mobility, the surface/interface effects and the quantum size effects are taken into account in the nanometer scale, and the multi-field coupling models will be developed to give an insight into the modification of the material properties due to the multi-field coupling effects. On the other hand, the electro-thermo-elastoplastic model is established for GaN-based hetero-structures by accounting for the multi-filed coupling effects on material properties. The thermo-mechanical behaviors such as the distributions of temperature, stress fields and current, and the failure behaviors in GaN-based hetero-structures under multi-field coupling effects are monitored in detail. The comparison between the simulations and experiments will be given. Through comprehensively studying on the issue of the multi-field coupling behaviors and structure-mechanical behaviors in GaN-based hetero-structures, the corresponding results obtained in this proposal will brighten the microscopic mechanisms of the coupling behaviors arising in material properties, and the coupling features on structural thermomechanical behaviors in GaN-based hetero-structures. And these studies will shed lights on seeking out effective approaches for the reinforcement of the functional performance of GaN-based hetero-structures and the reliability of the devices. This proposal will provide the applicable theoretical methods for the design and the applications of GaN-based hetero-structural devices.

在复杂物理场环境下,GaN基异质结构的材料性能和宏观响应均存在耦合效应，这些耦合效应会对GaN基结构器件的设计和应用产生重要影响。本项目将采用连续介质力学、电磁理论、输运理论和原子尺度方法，对GaN基异质结构的物理力学性能和宏观响应的多物理场耦合效应及失效行为进行研究。针对在不同物理场下的物理力学性能如弹性模量、屈服应力、热导率、载流子迁移率等，考虑表面/界面效应和量子效应，建立多场耦合模型来研究物理场与材料性能之间的定量关系；并建立虑及性能耦合效应的电-热-弹塑性理论，探讨性能耦合效应对GaN基异质结构宏观响应如温度、应力和电流等分布和失效行为的影响，并进行相关实验验证。通过上述问题的研究，本项目将给出在多物理场条件下GaN基异质结构的材料性能耦合行为的微观机理和宏观响应的耦合特性，指出提高GaN基异质结构性能和器件可靠性的可能途径，为GaN基结构器件的精确设计和高效应用提供理论基础。

GaN基异质结构材料因其具有优异的物理、化学性能，使其在高功率器件、高温器件和辐照器件有着广泛的应用。GaN基异质结构及其器件的材料特性和宏观物理场均存在多物理场耦合效应，这些耦合效应会对GaN基异质结构器件的设计和应用产生重要影响。本项目基于原子尺度方法和连续介质理论，建立GaN异质结构材料性能的多场耦合模型和虑及性能耦合效应的电-热-弹塑性理论，研究了GaN基纳米薄膜的热学性能和宏观物理场的多场耦合力学行为。.首先，建立GaN基异质结构的声弹理论模型，研究了异质结构和预应力对GaN基纳米薄膜结构的声子特性和热学性能的影响，计算结果表明：异质结构和预应力可以显著改变GaN基异质结构薄膜的声子色散关系、群速度和态密度，同时应力场可以改变热导率对温度的依赖性。.其次，通过考虑弹性性能表界面效应和表界面的声子散射作用，分析了表面界面特性对GaN基材料的声子特性、声子输运行为和热学性能的影响，计算结果表明: 表面电荷可以显著改变GaN纳米薄膜的声子特性进而改变声子热导率；表面散射可以显著降低GaN纳米薄膜的声子热导率，同时增强了GaN纳米薄膜声子热导率的尺寸效应；GaN异质结构薄膜的声子特性和热导率取决于表面和界面应力的共同作用。.最后，建立了脉冲热源下应力约束GaN基薄膜温度场的有限元分析模型，给出了薄膜的温度时间相应曲线和瞬态温度场的分布，发现初始压应力通增大薄膜热导率使得薄膜的温度峰值降低；同时分析了在脉冲磁场下双层导电薄板的多物理场耦合力学行为和结构失效，发现金属薄板和半导体薄板之间温度应力引起界面破坏，并在电磁脉冲作用下发生屈曲，使双层导电薄板结构的失效。.在本项目的资助下，相关研究结果已在著名国际期刊发表SCI论文8篇。本项目的研究成果，可为GaN 基异质结构器件的精确设计和高效应用提供理论基础。