Ultra precise 2-dimensional atomic tracking control for atom craft

随着纳米技术等超精密工程的飞速发展，需要一种亚纳米分辨率的定位方法。当晶体无应力时，晶格间距约为0.2 nm，在较长范围内是均匀稳定的。扫描隧道显微镜（STM）在获得晶体表面的原子图像方面具有很高的性能。因此，将该晶体与STM结合，可以作为亚纳米分辨率的定位参考。我们提出了一种参考晶体表面原子顶点和原子阵列的STM尖端原子跟踪控制方法。在本研究中，提出了一种针对外部扰动的原子跟踪控制稳定化方法。使用该基金获得了以下结果：(1)研制了一种直线运动精细的超精密工作台。直线度为0.2角秒，共振频率为2 kHz，振荡范围为10微米。利用该平台和STM磁头可以方便地获得原子图像。(2)分析了STM隧道电流在外部扰动作用下的噪声，并将其分为以下三个部分；(A)空气中的声音噪声，(B) STM尖端与样品之间的热漂移，(C)来自地板的振动噪声。通过提高STM仪器的刚度和使用防振台，可以去除(C)部分。(A)部分的振幅较小，频率较高。而(B)部分的幅值变化较大，频率变化较慢。(3)采用两级PI控制器实现原子跟踪控制的稳定化。对每级PI控制器分别进行调节以补偿干扰(A)或(B)，然后将它们组合起来。两级PI控制器对干扰(A)和(B)都进行了很好的补偿。少

Since ultra precision engineering, e.g. nanotechnology, has progressed rapidly, a new positioning method with sub-nanometer resolution is required. The lattice spacing of approximately 0.2 nm for some regular crystalline lattice is uniform and stable over a long range, if the crystal is stress free. The scanning tunneling microscope (STM) has high performance to obtain an atomic image of a crystalline surface. Therefore, such crystelline lattice can be used as a positioning reference with sub-nanometer resolution by combining the crystal and a STM. We have proposed an atomic tracking control of the STM tip by referring atomic apex points and arrays on crystalline surface. In this research, a stabilization method for the atomic tracking control against the outer disturbances has been developed. The following results were obtained using the fund.(1) An ultra precise stage with fine straight motion was developed. The straightness of 0.2 arc second, the resonance frequency of 2 kHz and sca … More nning range of 10 micrometer were evaluated, respectively. An atomic image was obtained easily using the stage and a STM head.(2) The noises on the tunneling current of the STM against the outer disturbances were analyzed and divided into the following three parts; (A) the sound noise in air, (B) the thermal drift between the STM tip and the sample and (C) the vibration noise from the floor. The part (C) can be removed by enhancement of the stiffness of the STM instrument and by use of the anti-vibration table. The amplitude and frequency for the part (A) were relatively small and high, respectively. However, the amplitude change and frequency for the part (B) were relatively large and slow, respectively.(3) The two-stages PI controller was implemented for the stabilization of the atomic tracking control. Each stage PI controller was adjusted for compensation of the disturbance (A) or (B), respectively, and then they were combined with. Both the disturbance (A) and (B) were compensated well with the two-stage PI controller. Less