Experimental study of electron-phonon coupling factor of copper thin film

Metallic thin wires are widely used as interconnectors in the ultra-miniature and highly-integrated systems and expected to exhibit high heat conductance. While in the development of novel photoelectric material, the coupling between electrons and phonons should be reduced as much as possible. The electron-phonon coupling is dominant to energy exchange in metals and the interaction time is in the order of femto to picoseconds. In this paper, the electron-phonon coupling factor of a copper nanofilm with thickness 60 nm deposited on the silicon substrate is measured using the transient thermoreflectance technique. The measured coupling factor is (11~12)×10¹⁶ W/(m³K) and very closed to the theoretical value 14×10¹⁶ W/(m³K).