Hartmut Steffen

Effect of nitrogen doping on TiOxNy thin film formation at reactive high-power pulsed magnetron sputtering

The paper is focused on a study of formation of TiOxNy 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 O2 and N2. 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 the deposition process. Post-deposition thermal annealing was not employed. The chemical composition from x-ray photoelectron spectroscopy diagnostic reveals formation of TiOxNy 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 in 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.

Aluminium atom density and temperature in a dc magnetron discharge determined by means of blue diode laser absorption spectroscopy

Diode laser absorption studies of aluminium atoms produced in a direct current (dc) magnetron discharge with argon as well as argon/nitrogen and argon/oxygen mixtures as working gas are reported. The measured Al atom density increases with increasing discharge power. The observed temperature being in the range of 340–420 K rises with increasing power but shows little pressure dependence. A small admixture of oxygen gas leads to a complete disappearance of the absorption signal, a result which is not yet fully understood.