Idrobo Juan Carlos, Lupini Andrew R, Feng Tianli, Unocic Raymond R, Walden Franklin S, Gardiner Daniel S, Lovejoy Tracy C, Dellby Niklas, Pantelides Sokrates T, Krivanek Ondrej L
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Phys Rev Lett. 2018 Mar 2;120(9):095901. doi: 10.1103/PhysRevLett.120.095901.
Heat dissipation in integrated nanoscale devices is a major issue that requires the development of nanoscale temperature probes. Here, we report the implementation of a method that combines electron energy gain and loss spectroscopy to provide a direct measurement of the local temperature in the nanoenvironment. Loss and gain peaks corresponding to an optical-phonon mode in boron nitride were measured from room temperature to ∼1600 K. Both loss and gain peaks exhibit a shift towards lower energies as the sample is heated up. First-principles calculations of the temperature-induced phonon frequency shifts provide insights into the origin of this effect and confirm the experimental data. The experiments and theory presented here open the doors to the study of anharmonic effects in materials by directly probing phonons in the electron microscope.
集成纳米级器件中的热耗散是一个重大问题，需要开发纳米级温度探测器。在此，我们报告了一种结合电子能量得失光谱法的方法的实施情况，以直接测量纳米环境中的局部温度。从室温到约1600 K测量了与氮化硼中的光学声子模式相对应的损失峰和增益峰。随着样品被加热，损失峰和增益峰都表现出向较低能量的偏移。温度诱导的声子频移的第一性原理计算为这种效应的起源提供了见解，并证实了实验数据。本文介绍的实验和理论为通过在电子显微镜中直接探测声子来研究材料中的非谐效应打开了大门。
