10nm尺度氮化镓局域热点的传热测量  

Ballistic Thermal Transport at Sub-10 nm Laser-Induced Hot Spots in GaN Crystal

作　　者：黄德钊 孙强胜 张宏凯 黄小娜 徐屾 岳亚楠[1,2] HUANG Dezhao;SUN Qiangsheng;ZHANG Hongkai;HUANG Xiaona;XU Shen;YUE Yanan(Key Laboratory of Hydraulic Machinery Transients,School of Power and Mechanical Engineering,Wuhan University,Wuhan 430072,China;School of Mechanical and Automotive Engineering,Shanghai University of Engineering Science,Shanghai 201620,China)

机构地区：[1]水力机械过渡过程教育部重点实验室,武汉大学动力与机械学院,武汉430072 [2]上海工程技术大学机械与汽车工程学院,上海201620

出　　处：《工程热物理学报》2025年第1期261-268,共8页Journal of Engineering Thermophysics

基　　金：国家重点研发计划(No.2023YFE0120200);国家自然科学基金资助项目(No.52206107,No.52076156)。

摘　　要：以氮化镓(GaN)为代表的第三代宽禁带半导体材料在功率半导体、微纳电力电子器件等领域具有重要的应用,而电子器件中广泛存在的纳米尺度热点(小于100 nm)极大地降低器件热安全阈值,是热安全隐患的重要来源,研究纳米尺度热点、充分理解纳米尺度热源的声子导热行为具有重要意义。纳米热点的可控生成及温度测量一直是工程热物理领域研究的热点和难点,本文针对该难题发展的针尖增强拉曼测热技术,同时解决了纳米热点的生成及测温难题,实现了10 nm尺度热点的传热研究。研究发现由于声子输运的影响,纳米尺度下热点的局部热导率远低于宏观热导率值。进一步结合光热耦合模拟和分子动力学研究,分析了声子在纳米尺度热点处的弹道输运行为,并测算出声子平均自由程,研究发现氮化镓声子平均自由程随温度降低的现象。该研究发展的方法将针尖近场增强效应和拉曼测热技术相结合,实现了10 nm尺度非接触温度测量和激光定点加热,本文关于声子弹道输运的理论成果还可以用于研究其他器件热安全问题。Gallium nitride(GaN)is a typical wide-bandgap semiconductor with a critical role in a wide range of electronic applications.Ballistic thermal transport at nanoscale hotspots will greatly reduce the performance of a device when its characteristic length reaches the nanometer scale,due to heat dissipation.In this work,we developed a tip-enhanced Raman thermometry approach to study ballistic thermal transport within the range of 10 nm in GaN,simultaneously achieving laser heating and measuring the local temperature.The Raman results showed that the temperature increase from an Au-coated tip-focused hotspot was up to two times higher(40 K)than that in a bare tip-focused region(20 K).To further investigate the possible mechanisms behind this temperature difference,we performed electromagnetic simulations to generate a highly focused heating field,and observed a highly localized optical penetration,within a range of 10 nm.The phonon mean free path(MFP)of the GaN substrate could thus be determined by comparing the numerical simulation results with the experimentally measured temperature increase which was in good agreement with the average MFP weighted by the mode-specific thermal conductivity,as calculated from first-principles simulations.Our results demonstrate that the phonon MFP of a material can be rapidly predicted through a combination of experiments and simulations,which can find wide application in the thermal management of GaN-based electronics.

关 键 词：拉曼热测量 纳米针尖 弹道热输运 

分 类 号：TK121[动力工程及工程热物理—工程热物理]