Study on Nano-scale Measurement Technique of Thermophysical Properties Using Near-field Optics

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In order to measure nano-scale thermal properties (i.e. thermal conductivity and thermal diffusivity) of nano-materials, Near-field Optics Thermal Nanoscopy, which has a high spatial resolution beyond a diffraction limit of light, has been developed. Research results are summarized as follows;1, Adopting the PZT scanning-stage, dithering system and near-field optical system, near-field light can be stably excited in a near-field regime of sample surface.2, To check the validity of present technique, diffracted grating and 150 nm-thick Al thin film were demonstrated, and thermoreflectance signal was successfully detected by using present apparatus. The spatial resolution is estimated to be about 100 nm.3, Probe oscillation method, which can eliminate the error due to a reflection from Au coating of near-field optical fiber, was originated to detect the weak signal of reflectivity change in near-field light.4, The near-field lights that contain the information of thermal properties of 125 nm-thick Al thin film and Single-walled Carbon Nanotube were successfully detected by using probe oscillation method with 500 nm apertured near-field optical fiber. Results of phase-lag (heating laser vs. temperature change) indicate the adequacy of present study to measure thermal conductivity and thermal diffusivity of nano materials.