Influence of oxygen pressure on the properties and biocompatibility of titanium oxide fabricated by metal plasma ion implantation and deposition

Titanium oxide with a rutile structure has superior optical properties and blood compatibility and is thermodynamically more stable than other forms. Titanium oxide thin films are deposited on (1 0 0) silicon and SiO2 wafers by metal plasma ion implantation and deposition. The substrates are DC biased during the film deposition and the influence of the oxygen pressure on the characteristics of the coatings is investigated. X-ray diffraction indicates the existence of Ti4O7 in the film when the oxygen pressure is lower than 2.0 X 10(-2) Pa. As the oxygen pressure increases, the preferred orientation of the as-deposited titanium oxide film changes to the (2 0 0) high-index plane from the (1 0 0) low-index plane. The as-deposited titanium oxide films are subsequently annealed at 750 degreesC for 60 min in vacuum. The microstructure, resistance, composition, and blood compatibility of the films are assessed. Before annealing, the sheet resistance of the titanium oxide increases with higher oxygen pressure, and after vacuum annealing, the sheet resistance of some of the titanium oxide films increases by approximately 60 times. The results of the platelet adhesion experiments acquired from the annealed samples are similar to those from low-temperature isotropic pyrolytic carbon. (C) 2002 Elsevier Science B.V. All rights reserved.