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S近场光学显微镜远场成像的空间分辨率，设计了一种新型的共焦光学系统。新设计采用锗(Ge)弯月透镜设计作为物镜和中继镜，以减少球差。GE弯月面物镜的数值孔径为0.35，工作距离为12 mm。在物镜和接力透镜之间放置一个直径为60μm的针孔。为了检查共焦光学系统的焦斑大小，在Au和SiO_2之间的边界上测量了LWIR FF热信号。FF信号的空间分辨率估计为~70μm，优于单透镜光学获得的110μm。此外，为了减少采集时间，采用了尖端调制法来减小采样高度调制法产生的额外背景辐射。通过这两点改进，低温太赫兹S近场光学显微镜的近场探测捕获时间由10次提高到了3次S。在积分时间为3 S的NiCrSiO_2样品上，成功地探测到了近场信号。根据核磁共振衰减数据，在镍铬上观察到的核磁共振信号可以用传导电子的热随机运动产生的电磁逝去场来解释。利用电子束光刻技术制作了亚微米结构的金属和石墨烯器件。首次使用常温S近场光学显微镜检测了电流感生核磁共振。

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.