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

为了测量纳米材料的纳米级热性能（即热导率和热扩散率），开发了一种超过光衍射极限的高空间分辨率的近场光学热纳米显微镜。研究结果总结如下：1、采用PZT扫描级、抖动系统和近场光学系统，可以在样品表面近场状态下稳定地激发近场光。为了验证该技术的有效性，对衍射光栅和150nm厚的铝薄膜进行了演示，并成功地检测了热反射信号。空间分辨率估计在100 nm左右。3 .为了检测近场光反射率变化的微弱信号，提出了探测振荡法，该方法可以消除近场光纤金涂层反射带来的误差。4、利用500 nm孔径近场光纤，采用探针振荡法成功地检测了含有125 nm厚铝薄膜和单壁碳纳米管热性能信息的近场光。相位滞后（加热激光与温度变化）的结果表明，本研究对纳米材料的导热系数和热扩散系数的测量是适当的。

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.