Development of High Voltage Field Ion Microscope for the Studies of Surface, Interface, and Substrate of Materials

高压场离子显微镜（HV-FIM）是一种用于观察材料表面、界面和衬底原子结构的技术进步。众所周知，由于需要10GV/m的高电场，io <eta>场显微镜的应用仅限于精细难熔金属线。为了观察具有大曲率半径的尖端试样的原子排列，需要设计高压真空馈通。目前的HV-FIM主要由<10^(-7)> Pa的超高真空室、< n2 >的液体冷却冷指和最高电压60kV的高压装置组成。标本交换室的设备使标本的有效观察，而不泄漏整个真空系统的普通气氛。对镀硼钨进行了hv - film观察。在1200 K下加热涂层试样，鉴定出<W_2B_5>的形成，这与硼纤维核心处存在钨硼化物相吻合。利用HV-FIM成功地观察了钨的原子结构，而不是细钨丝，获得了w原子的高分辨率的氦离子图像，分辨率为0.4nm。如果不使用HV-FIM，从具有大曲率半径的尖端获得的上述结果可能是不可能的。

A high voltage field ion microscope (HV-FIM) has been developed for technological advances of observing atomic structures of surface, interface, and substrate of materials. As is well known, the applications of field io <eta> microscopy have been limited to fine refractory metal wires primarily due to the requirement of a high electric field of 10GV/m. One would require the design of a high voltage vacuum feedthrough in order to observe atomic arrangements of tip-specimen with a large radius of curvature. Main components of the present HV-FIM are ultra-high vacuum chamber of <10^(-7)> Pa, liquid <N_2> cooled cold finger, and the high voltage devices with a maximum voltage of 60kV. An equipment of the specimen exchange chamber enabled efficient observations of a specimen without leaking the whole vacuum system to an ordinary atmosphere.HV-FIM observations boron-coated tungsten were carried out. By heating the coated specimen at 1200 K, the formation of <W_2B_5> was identified, and this coincides with the existence of tungsten borides at the core of boron fibers. An observation of the atomic structure of bulk tungsten, instead of fine tungsten wire, was successfully made using the HV-FIM, and He-ion image of W-atoms was obtained with a high resolution of 0.4nm. The above results obtained from the tip having a large radius of curvature may not be possible without a use of HV-FIM.