Influence of the elemental composition and crystal structure on the vacuum properties of Ti-Zr-V non-evaporable getter films

Non-evaporable thin film getters based on the elements of the 4th and 5th columns of the periodic table have been deposited by sputtering. Among the about 20 alloys studied to date, the lowest activation temperature (about 180 °C for a 24-hour heating) has been found for the Ti-Zr-V system in a well-defined composition range. The characterization of the activation behavior of such Ti-Zr-V films is presented. The evolution of the surface chemical composition during activation is monitored by Auger Electron Spectroscopy (AES) and the functional properties are evaluated by pumping speed measurements. The pumping speed characteristics are quite similar to those already measured for commercially available NEG materials, except for the much lower saturation coverage for CO. This inconvenience, which is due to the smooth surface structure of these films, can be counteracted by increasing the roughness of the substrate.