DESIGN AND DEVELOPMENT OF AN ULTRAHIGH-VACUUM HIGH-RESOLUTION TRANSMISSION ELECTRON-MICROSCOPE

A 200 kV ultrahigh vacuum high-resolution transmission electron microscope (UHV-HRTEM) for in-situ surface observation has been developed. With use of metal sealings, the vacuum at the specimen position was 2.6 x 10(-7) Pa without any cooling traps, and less than 1.5 x 10(-7) Pa with the built-in cooling traps cooled by LN2. A cantilever-type goniometer, a specimen holder and a high-resolution objective lens were newly developed for high-resolution transmission (HRTEM) and reflection (HRREM) to observe surfaces with a point-to-point resolution of 0.21 nm. The specimen tilt is up to +/- 20-degrees. Crucible-type and direct-heating-type specimen holders were constructed for in-situ experiments on thin films and small particles, and on bulk crystalline surfaces, respectively. The usefulness of the microscope for surface studies is shown by images of clean surfaces of Au and Si prepared in the microscope.