Thin-Film Femtosecond Thermoreflectance Analysis for Sensor Technology

该奖项旨在支持薄膜热表征的非接触式方法的进一步发展，并探索这些信息在传感关键微观结构特性方面的应用，如：热扩散率、电子迁移率的晶界阻抗、热边界电阻、电子声子能量耦合、声速和厚度。这将利用飞秒泵/探针热反射技术来完成。这种薄膜表征方法依赖于这样一个事实，即某些材料的反射率是温度和应变的函数，并且通过监测对超短激光脉冲辐射沉积的反射响应，可以同时推断热性能和机械性能。为了补充经验方法，在对非平衡加热和对金属和半导体光学性质的影响的强大理论理解方面取得了一些进展，并为使计算过程更有效而设定了进一步的目标。这项研究有望影响国家重要的高科技材料和设备的制造，如光电子、光电和微电子。该计划开发的理论和技术将为过程监测和控制的新型无损传感器技术的发展奠定基础。建议的工作提供了一个良好的教育环境，以基础科学为基础，对工业有强大的潜在影响，并通过培养跨学科的研究团队。实验室将继续其传统，将来自不同背景和经历的学生团结在一个支持性的小组研究环境中。

This award is to support the further development of non-contact methods for the thermal characterization of thin films and the exploration of the utility of this information in sensing critical microstructural properties such as: thermal diffusivity, grain boundary impedance of electron mobility, thermal boundary resistance, electron phonon energy coupling, acoustic velocity, and thickness. This will be done utilizing a femtosecond pump/probe thermoreflectance technique. This thin film characterization method relies on the fact that the reflectivity of certain materials is a function of both temperature and strain, and by monitoring the reflective response to the deposition of radiation by an ultrashort laser pulse, the thermal and mechanical properties can be extrapolated simultaneously. To compliment the empirical approach, several advancements have been made toward a strong theoretical understanding of nonequilibrium heating and the effects on the optical properties of metals and semiconductors and further goals have been set towards making computational processes more efficient.This research promises to impact the manufacturing of high-tech materials and devices of national importance, such as opto-electronics, photo-voltaics, and micro-electronics. The theories and techniques developed with this program will form the basis for the development of new nondestructive sensor technologies for process monitoring and control. The proposed work provides an excellent educational environment, by setting goals based in fundamental science with a strong potential impact on industry and by fostering interdisciplinary research teams. The lab will continue its tradition of uniting students from different backgrounds and experiences into a supportive group research environment.