Thermal diffusivity measurement on sub-mm specimen using heat diffusion image by spot heating thermoreflectance

T. Yagi1, S. Firoz2, N. Taketoshi1 and T. Baba1

1National Institute of Advanced Industrial Science and Technology, Japan
2Ahsanullah University of Science and Technology, Japan

Keywords: thermoreflectance
property: thermal diffusivity
material: solid

Thermal diffusivity measurements for specimens smaller than a cubic mm has been carried out using spot laser heating and thermoreflectance technique. A specimen was cut to obtain flat surface and then coated by Mo thin film with 100 nm in thickness. A modulated laser beam with 808 nm in a wavelength, 20 mW in an averaged power and 15 μm in a spot diameter was irradiated on the flat surface. To observe temperature oscillation from the heated point, a cw laser beam with 782 nm in a wavelength, 1 mW in a power and 10 μm in a diameter was scanned with 5 μm step. A 2D image of phase delay of the temperature oscillation from the heated point was finally obtained. The 2D images for the pure quartz, Ge and Si was converted to the relation between the phase delay and the distance from the heat spot. The phase delay data for those materials were proportional to the distance and the thermal diffusivities were analyzed based upon the principle of Angstrom method.

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