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Formation of thin TiOx films produced by pulsed planar magnetron sputtering deposition is reported in this paper. The formation process and layer growth were controlled by (i) the ratio of reactive O2 in Ar/O2 working gas mixture and (ii) the pressure in the vacuum chamber. The magnetron, operated in a high-power pulse mode with a low repetition frequency of 250 Hz, reached maxima peak current Ip ∼ 50 A and magnetron current density peaks at ip ∼ 1 A cm−2. Particular spectral lines (Ar = 420.07 nm, Ar+ = 487.98 nm, Ti = 518.96 nm) emitted by the discharge were investigated using time-resolved photon counting measurements. The phases of deposited TiOx films were determined by grazing incidence x-ray diffractometry and thickness and density were calculated from x-ray reflectometry measurements; in addition composition and chemical bounds were revealed by x-ray photoelectron spectroscopy. The film diagnostics survey the existence of different crystalline phases in the Ti–O system and their formation. Discharge properties for example, deposition rate and time evolution of discharge current are also discussed.

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Optical, photo-electrochemical, crystallographic and morphological properties of TiO2 thin films prepared by high power impulse magnetron sputtering at low substrate temperatures (<65 °C) without post-deposition thermal annealing are studied. The film composition—anatase, rutile or amorphous TiO2—is adjusted by the pressure (p ∼ 0.75–15 Pa) in the deposition chamber. The different crystallographic phases were determined with grazing incidence x-ray diffractometry. The surface morphology and size of TiO2 grains/clusters were imaged with atomic force microscopy. Basic plasma parameters were determined by means of the time-resolved Langmuir probe technique. The power density influx on the substrate was estimated from calorimetric probe measurement. The data from calorimetric probe measurements and time-resolved Langmuir probe served as input parameters for the calculation of influx contributions of particular species. The band-gap energy Eg depends on the film composition and crystallographic phase. Optical parameters (refractive index n + ik, transmittance T, reflectance R and absorbance A) are measured as functions of photon energy in the UV–Vis range by spectroscopic ellipsometry. For the rutile and anatase films agreement with the respective bulk phase is found. Incident photon-current conversion efficiency determined by photo-electrochemical measurements reached the highest values (0.312) for the anatase film.

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Experimental results for the energy distribution of electrons and plasma ions in a magnetron discharge with a titanium target and with pure argon, argon/nitrogen and argon/oxygen mixtures as working gas are reported. Typical electron temperatures measured 6.5....9.5 cm above the magnetron target range between 2-3.5 eV. Typical values for the plasma potential are in the 0.4-2 V range, as are mean ion energies measured with the help of energy-resolved mass spectrometry. Deposited titanium films show some dependencies on oxygen flow and on substrate bias.

To cite this version:Vitezslav Stranak, Marion Quaas, Robert Bogdanowicz, Hartmut Steffen, Harm Wulff, et al.. Effect of nitrogen doping on TiOxNy thin film formation at reactive high-power pulsed magnetron sputtering. Journal of Physics D: Applied Physics, IOP Publishing, 2010, 43 (28) AbstractThe paper is focused on a study of formation of TiO x N y thin films prepared by pulsed magnetron sputtering of metallic Ti target. Oxygen and nitrogen were delivered into the discharge in the form of reactive gases O 2 and N 2 . The films were deposited by high-power impulse magnetron sputtering working with discharge repetition frequency f = 250 Hz at low (p = 0.75 Pa) and high (p = 10 Pa) pressure. The substrates were on floating potential and thermally stabilized at room temperature during deposition process. Post-deposition thermal annealing was not employed. The chemical composition from XPS diagnostic reveals formation of TiO x N y structure at low flow rate of oxygen in the discharge gas mixture. This result is confirmed by XRD investigation of N elements incorporation into the Ti-O lattice. Decrease of band-gap to values Eg ∼ 1.6 eV in TiOxNy thin film is attributed to formed Ti-N bonds. The discharge properties were investigated by time-resolved optical emission spectroscopy. Time evolution of particular spectral lines (Ar + , Ti + , Ti) is presented together with peak discharge current.