極低温THz近接場顕微鏡を用いた微小回路エネルギー散逸の観察

为了提高低温太赫兹超近场光学显微镜（THz s-SNOM）远场图像的空间分辨率，设计了一种新的共焦光学系统。新设计的物镜和中继透镜采用锗（Ge）弯月形透镜设计，以减少球面像差。Ge弯月形物镜的数值孔径为0.35，工作距离为12 mm，物镜和中继透镜之间有一个直径为60 μm的针孔。为了检查共焦光学器件的焦斑尺寸，在Au和SiO2之间的边界处测量LWIR FF热信号。FF信号的空间分辨率估计为~70 μm，优于从单透镜光学器件获得的110 μm。此外，为了减少采集时间，应用尖端调制方法来减少由样品高度调制方法引起的额外背景辐射。通过这两项改进，低温THz s-SNOM近场探测的采集时间从10 s提高到3 s。根据NF衰减数据，我们可以用传导电子热随机运动产生的电磁倏逝场来解释NiCr上观察到的NF信号。电流诱导的NF检测的第一次尝试，通过使用室温s-SNOM。

To improve the spatial resolution of far-field (FF) images of low-temperature THz s-SNOM, I’ve designed a new confocal optics. The new design uses germanium (Ge) meniscus lens design for objective and relay lens to reduce spherical aberration. The Ge meniscus objective has a numerical aperture of 0.35 and a working distance of 12 mm. A pinhole of 60 μm diameter is placed between the objective and the relay lens. To check the focal spot size of the confocal optics, the LWIR FF thermal signals are measured at the boundary between Au and SiO2. The spatial resolution of the FF signals is estimated to be ~70 μm, better than the 110 μm obtained from the single lens optics. Further, to reduce the acquisition time, the tip-modulation method is applied to reduce the extra background radiation induced by the sample-height modulation method. With these two improvements, the acquisition time of near-field (NF) detection in the low-temperature THz s-SNOM is improved to 3 s from 10 s.An NF signal is successfully detected on the NiCr/SiO2 sample with a 3 s integration time by using. According to the NF decay data, the NF signals observed on the NiCr can be explained by the electromagnetic evanescent fields induced by the thermal random motion of the conduction electrons.The submicron-structure metallic and graphene device has been fabricated by e-beam lithography. The current-induced NF is detected for the first trial by using the room-temperature s-SNOM.