| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2018) | |
| Thin Films | Wednesday Sessions |
| Session TF-WeP |
| Session: | Thin Films Poster Session II |
| Presenter: | Tetsuya Miyazawa, SOKENDAI, Japan |
| Authors: | T. Miyazawa, SOKENDAI, Japan Y. Kano, Tokyo University of Science, Japan Y. Nakayama, Tokyo University of Science, Japan K. Ozawa, Tokyo Institute of Technology, Japan T. Kikuchi, KEK, Japan K. Mase, KEK, Japan |
| Correspondent: | Click to Email |
Non-evaporable getter (NEG) coatings are widely used for accelerators because they are ideal for maintain ultrahigh vacuum (UHV), and are oil free, magnetic-field free, vibration free, economical, and energy saving. Recently, we have developed a new NEG coating for pumping H2 and CO, and named it as oxygen-free Pd/Ti coating. In oxygen-free Pd/Ti coating Ti thin film is deposited and overcoated by Pd thin film under clean UHV conditions in the range of 10−7–10−8 Pa [T. Miyazawa, M. Kurihara, S. Ohno, N. Terashima, Y. Natsui, H. Kato, T. Kikuchi, and K. Mase, J. Vac. Sci. Technol. A, in press.]. When the oxygen-free Pd/Ti thin film is exposed to the atmosphere, the Pd surface is contaminated with organic compounds to some degree, resulting in a decline of the pumping speeds. In the present paper, we report removal of the carbon contamination and improvement of the pumping speeds of the oxygen-free Pd/Ti thin film using UHV or O2 annealing. Unannealed, UHV annealed, and O2 annealed (annealed under O2 pressure of 1.3 × 10−4 Pa) oxygen-free Pd/Ti thin films were analyzed with X-ray photoelectron spectroscopy using synchrotron radiation. The carbon coverage of the unannealed sample was estimated as 0.90 ML. On the other hand, the carbon coverages of UHV annealed and O2 annealed samples were estimated as 0.41 and 0.10 ML, respectively. The pumping speed of the oxygen-free Pd/Ti for H2 and CO after baking under O2 pressure of 1.3 × 10−4 Pa was improved by a factor of 3.7 and 16.3 in comparison with UHV baking, respectively [T. Miyazawa, Y. Kano, Y. Nakayama, K. Ozawa, T. Kikuchi, and K. Mase, in preparation.].