GOALI: An Experimental Study of Electric Field Driven Non-Fourier Thermal Transport in High Power Electronic Devices

基于氮化镓的射频功率放大器具有宽带运行和高效率的特点，是实现可靠、节能和无处不在的无线5G网络的关键部件，数十亿设备使用该网络进行数据收集和计算。然而，在5G无线网络中全面实施氮化镓微电子技术需要克服对过热的担忧。该项目将调查和确定导致理论预测和实验观察之间差异的热传输机制，以便设计有效的热管理以获得可靠的性能。此外，该项目将包括旨在弥合热科学和电子器件物理学之间差距的教育任务，并降低本科生学习纳米尺度传热原理的入门门槛。教育活动还将使代表性不足的学生接触到产业驱动的学术研究，并激励K-12学生追求stem相关领域。该项目的研究目标是通过实验确定和探测纳米尺度的非傅立叶热传输机制，该机制负责在极端电场和热流条件下同时放大氮化镓晶体管内的加热。假设观察到的放大加热是纳米尺度热源尺寸效应、电场引起的氮化镓晶体变形和能量载流子之间的热不平衡的综合结果，所有这些都是由纳米尺度电场尖峰引起的。为了验证这一假设，并研究氮化镓晶体管的基本物理特性，将开发一种深紫外热成像能力，在商用热成像系统中提供最高的空间分辨率。所开发的深紫外热成像技术将与拉曼光谱、光致发光和一种新的多尺度电热建模方案一起用于研究高压偏置氮化镓晶体管放大加热的物理根源。研究成果将促进电热协同设计，并改进氮化镓功率放大器寿命评估的行业标准方法。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。

Featuring broadband operation and high efficiency, gallium nitride-based radio frequency power amplifiers are key components to realize reliable, energy efficient, and ubiquitous wireless 5G networks that billions of devices use for data collection and computation. However, full implementation of gallium nitride microelectronics for 5G wireless networks requires overcoming concerns about overheating. This project will investigate and identify the thermal transport mechanisms leading to the discrepancies between theoretical predictions and experimental observations, to allow design of effective thermal management for reliable performance. Moreover, this project will encompass educational tasks designed to bridge the gap between thermal sciences and electronic device physics and to lower the entry barrier for undergraduate students to study nanoscale heat transfer principles. The educational activities will also expose underrepresented students to industry-driven academic research and inspire K-12 students to pursue STEM-related fields.The research goal of this project is to experimentally identify and probe nanoscopic, non-Fourier thermal transport mechanisms that are responsible for the amplified heating within gallium nitride transistors simultaneously subjected to extreme electric field and heat flux conditions. It is hypothesized that the observed amplified heating is a combined result of nanoscale heat source size effects, electric field induced deformation of the gallium nitride crystal, and thermal non-equilibrium among energy carriers, all of which are caused by a nanoscale electric field spike. A deep ultraviolet thermal imaging capability which offers the highest spatial resolution among commercial thermal imaging systems will be developed in order to test this hypothesis and to study the fundamental physics in gallium nitride transistors. The developed deep ultraviolet thermal imaging technique will be used together with Raman spectroscopy, photoluminescence, and a novel multi-scale electro-thermal modeling scheme to study the physical origins of the amplified heating in high voltage-biased gallium nitride transistors. Research outcomes will facilitate electro-thermal co-design and improve industry standard methods for lifetime assessment of gallium nitride power amplifiers.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.