LED芯片层级声子热输运介观模拟

Light-emitting diodes (LEDs) are regarded as the fourth generation of light source due to its high efficiency, energy saving and environment protection. Because of light emitting with great heat generation, heat flux of the LED chip usually higher than 1 W/mm^2, therefore, chip’s junction temperature control is a main technical bottleneck for high power LED application. So far, LED thermal management is mainly focused on packaging level and system application. If more attention been paid to the chip level, to find the chip’s internal heat generation and transportation mechanism from mesoscopic, and to illuminate the chip’s internal phonon transportation mechanism, then we can control the chip’s junction temperature. It also cut the heat dissipation cost at packaging level and system application level, and enhance the reliability of chip. Based on the above conception, this proposal aims to develop and promote mesoscopic simulation methods for LED chip’s phonon heat transportation, such methods are expected to be a useful tool for the research of chip’s phonon heat transportation. The detailed research contents are divided into two aspects: 1) develop a full-dispersion Monte Carlo simulation method；2) promote the Local multiquadric RBF meshless scheme for phonon heat transfer。This proposal covers a typical fundamental problem abstracting from the thermal management of solid state lighting applications, it is expected to provide theoretical and technical instruction for LED active thermal management at chip level, and promote the LEDs indeed penetrating the general lighting market.

LED高效、节能、环保，是传统照明产业升级的第四代光源。发光伴随发热，芯片内部热流密度高达1 W/mm^2，结温控制是高功率LED应用中的技术瓶颈。现有LED热管理主要集中在封装和系统应用宏观层面上。如果关注芯片层级，从微观角度探讨芯片内部热产生及热输运机理，探明芯片内部影响声子输运的机制，就可以实现芯片结温控制，从而减小封装和系统应用层面所需要的散热成本；同时有助于提高芯片本身的可靠性。基于该思想，本项目力求发展并完善LED芯片层级声子热输运介观模拟方法，为芯片层级声子热输运研究提供有力工具。声子热输运介观模拟方法基于声子玻尔兹曼方程，具体研究内容涵括两个方面：（1）发展全色散声子蒙特卡洛模拟方法；（2）完善基于离散坐标求解声子玻尔兹曼输运方程的无网格法。本课题是一个典型的从应用中提炼出的基础科学问题，预期结果有助于为芯片层级热管理提供理论和技术指导，促进大功率LED迈向高端照明领域。

LED高效、节能、环保，是传统照明产业升级的第四代光源。发光伴随发热，芯片内部热流密度高达1 W/mm^2，结温控制是高功率LED应用中的技术瓶颈。现有LED热管理主要集中在封装和系统应用宏观层面上。如果关注芯片层级，从微观角度探讨芯片内部热产生及热输运机理，探明芯片内部影响声子输运的机制，就可以实现芯片结温控制，从而减小封装和系统应用层面所需要的散热成本；同时有助于提高芯片本身的可靠性。本项目力求发展并完善LED芯片层级声子热输运介观模拟方法，为芯片层级声子热输运研究提供有力工具。具体研究内容涵括两个方面：（1）计算了芯片材料的本征导热系数和合金材料的导热系数；（2）计算了芯片的尺寸效应；（3）发展了白光LED中荧光粉光致发光过程的辐射传递方程，并开展了实验验证。本项目为电子器件的芯片级散热提供了可行思路。