Picosecond Thermoreflectance Measurements of Thermal Diffusion in Film/Substrate Two-Layer Systems

摘要

We report the first systematic measurements of temperature responses of film/substrate two-layer system with a picosecond thermoreflectance technique. Aluminum thin films with the thickness of 50nm, 100nm, and 500nm sputtered on Pyrex 7740 glass substrates, measured and analyzed with a film/substrate two layer model assuming one-dimensional thermal diffusion. The validity of our approach is confirmed by simulating the thermal diffusion of the aluminum thin films on the glass substrates. We show that the thermal diffusivity of the film, the film thickness, thermal diffusion time in the thin film, and the thermal effusivity ratio of the substrate to the film can be evaluated by analyzing the thermoreflectance signal.