Abstract

A picosecond thermoreflectance measurement system has been developed in theNational Metrology Institute of Japan in order to measure thermaldiffusivities of metal thin films. A laser beam from a picosecond Ti-sapphirelaser is focused onto the surface of a metal thin film with a spot size of100 µm and absorbed within the skin depth of the order of 10 nm. Then, heatdiffuses towards the opposite side of the thin film one-dimensionally, and thetemperature of the heated face decreases over the time scale from tenpicoseconds to several hundreds of picoseconds. This ultrafast temperatureresponse is observed with a thermoreflectance method using probe picosecondpulses from the same source of the Ti-sapphire laser. Thermoreflectancesignals for aluminium thin films with the thickness of 50 nm, 100 nm, and500 nm sputtered on Pyrex 7740 glass substrates were observed under the frontheating front detection (FF) configuration. We also developed a rear heatingfront detection (RF) type picosecond thermoreflectance measurement system.Thermoreflectance signals of molybdenum thin films and aluminium thin filmswith nominal thickness of 100 nm deposited on Pyrex 7740 glass substrates wereobserved at room temperature under RF configuration. Thermal energy transferinside the molybdenum and aluminium thin films is dominated by the classicalFourier law. In-plane thermal diffusivities of the thin films are close tothose of the bulk materialsalthough out-of plane electrical resistivities measured by the four-probemethod are larger than the resistivities of the bulk materials.

Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.