凝聚态物理
声子
电子
材料科学
散射率
散射
放松(心理学)
声子散射
基质(水族馆)
联轴节(管道)
电子散射
界面热阻
热的
热阻
物理
超导电性
光学
地质学
量子力学
气象学
冶金
海洋学
社会心理学
心理学
作者
Ashutosh Giri,John T. Gaskins,Brian Donovan,Chester J. Szwejkowski,Ronald J. Warzoha,Mark A. Rodriguez,Jon F. Ihlefeld,Patrick E. Hopkins
摘要
We study the electron and phonon thermal coupling mechanisms at interfaces between gold films with and without Ti adhesion layers on various substrates via pump-probe time-domain thermoreflectance. The coupling between the electronic and the vibrational states is increased by more than a factor of five with the inclusion of an ∼3 nm Ti adhesion layer between the Au film and the non-metal substrate. Furthermore, we show an increase in the rate of relaxation of the electron system with increasing electron and lattice temperatures induced by the laser power and attribute this to enhanced electron-electron scattering, a transport channel that becomes more pronounced with increased electron temperatures. The inclusion of the Ti layer also results in a linear dependence of the electron-phonon relaxation rate with temperature, which we attribute to the coupling of electrons at and near the Ti/substrate interface. This enhanced electron-phonon coupling due to electron-interface scattering is shown to have negligible influence on the Kapitza conductances between the Au/Ti and the substrates at longer time scales when the electrons and phonons in the metal have equilibrated. These results suggest that only during highly nonequilibrium conditions between the electrons and phonons (Te ≫ Tp) does electron-phonon scattering at an interface contribute to thermal boundary conductance.
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