Differentiating contributions of electrons and phonons to the thermoreflectance spectra of gold
Differentiating contributions of electrons and phonons to the thermoreflectance spectra of gold
复制标题
DOI：
10.1103/physrevmaterials.5.106001
复制
发表时间：
2021-03
影响因子：
3.4
通讯作者：
Kexin Liu;Xinping Shi;Frank Angeles;R. Mohan;J. Gorchon;Sinisa Coh;Richard B. Wilson
中科院分区：
文献类型：
--
作者：
Kexin Liu;Xinping Shi;Frank Angeles;R. Mohan;J. Gorchon;Sinisa Coh;Richard B. Wilson
为了更好地了解温度对金属光学性质的多种影响，我们从实验和理论上量化了电子与声子对金的反射谱的贡献。我们进行了一系列的泵浦/探测测量纳米Pt/Au双层膜在400和1000 nm之间的波长。在所有波长下，我们发现声子温度的变化，而不是电子温度的变化，是Au的介电常数的主要贡献者。由于d态和费米能级之间的带间跃迁，在波长λ 480 nm处的电子温度对电导率最敏感。在480 nm处，电子温度占总发射率的约20%。在近红外区，电子温度占总辐射率的2%。我们还从第一性原理计算了Au的电子发射谱。我们的计算进一步证实了声子温度对Au的电导率起主导作用。Au的大部分电子发射率是由于声子布居数对电子寿命的影响。
To better understand the many effects of temperature on the optical properties of metals, we experimentally and theoretically quantify the electron vs phonon contributions to the thermoreflectance spectra of gold. We perform a series of pump/probe measurements on nanoscale Pt/Au bilayers at wavelengths between 400 and 1000 nm. At all wavelengths, we find that changes in phonon temperature, not electron temperature, are the primary contributor to the thermoreflectance of Au. The thermoreflectance is most sensitive to the electron temperature at a wavelength of ∼ 480 nm due to interband transitions between d states and the Fermi level. At 480 nm, the electron temperature is responsible for ∼ 20% of the total thermoreflectance. In the near infrared, the electron temperature is responsible for < 2% of the total thermoreflectance. We also compute the thermoreflectance spectra of Au from first principles. Our calculations further confirm that phonon temperature dominates thermoreflectance of Au. Most of the thermoreflectance of Au is due to the effect of the phonon population on electron lifetime.