Influence of ion energy on titanium oxide formation by vacuum arc deposition and implantation

Abstract

Titanium oxide thin films were produced by vacuum arc deposition while pulse biasing the substrate. The stoichiometry can be influenced by varying the oxygen partial pressure and the arc current from semiconducting and transparent TiO 1.8 to metallic TiO x ( x≈1.4). Without additional bias voltage, a hyperthermal energy of 25–50 eV of the titanium and oxygen ions leads to the growth of columnar textured rutile films on silicon, with their orientation solely determined by the substrate orientation. While applying negative high voltage pulses between 1 and 5 kV with a duty cycle of 9% no loss of this texture was observed. This can be explained by the rather high displacement energy of 50 eV for rutile. Using atomic force microscopy (AFM) an increasing surface roughness, caused by a larger sputter etching of the grain boundaries, as well as an increase in the column diameter was observed. At 10 kV pulses a broadening and splitting of the rutile (1 1 0) peak in X-ray diffraction (XRD) was observed, indicating enough mobility of oxygen vacancies and titanium interstitials to start the formation of the Magnéli phases Ti n O 2 n−1 .