In this paper, a comparison of TiO₂ thin films prepared by magnetron sputtering with a continuous and pulsed gas flow was presented. Structural, surface, optical, and mechanical properties of deposited titanium dioxide coatings were analyzed with the use of a wide range of measurement techniques. It was found that thin films deposited with a gas impulse had a nanocrystalline rutile structure instead of fibrous-like anatase obtained with a continuous gas flow. TiO₂ thin films deposited with both techniques were transparent in the visible wavelength range, however, a much higher refractive index and packing density were observed for coatings deposited by the pulsed gas technique. The application of a gas impulse improved the hardness and scratch resistance of the prepared TiO₂ thin films.

The aim of this work is to determine the influence of medium frequency magnetron sputtering powers on the various properties of hafnium dioxide (HfO₂) thin films. Microstructure observations show that an increase in the sputtering power has a significant influence on HfO₂ films’ microstructure. As-deposited hafnia thin films exhibit nanocrystalline structure with a monoclinic phase, however the rise of the sputtering power results in an increase of crystallite sizes. Atomic force microscopy investigations show that the surface of the deposited films is smooth, crack-free, and composed of visible grains. The surface roughness and the value of the water contact angle increase with the increase of the sputtering power. Measurements of the optical properties show that HfO₂ coatings are transparent in the visible wavelength range. A higher sputtering power causes a decrease of an average transmittance level and a simultaneous increase of the real part of the refractive index. Nanoindentation measurements reveal that the thin film hardness and Young’s elastic modulus increase with an increase in the sputtering power. Moreover, the results of plasticity index H/E and plastic resistance parameter H³/E² are discussed. Based on the obtained results, a correlation between the sputtering power and the structural, surface, and optical properties, as well as the hardness and Young’s elastic modulus, were determined.

The magnetron sputtering has become one of the commonly used techniques for industrial deposition of thin films and coatings due to its simplicity and reliability. At standard magnetron sputtering conditions (argon pressure of ∼0.5Pa) inert gas particles (necessary to sustain discharge) are often entrapped in the deposited films. Inert gas contamination can be eliminated during the self-sustained magnetron sputtering (SSS) process, where the presence of the inert gas is not a necessary requirement. Moreover the SSS process that is possible due to the high degree of ionization of the sputtered material also gives a unique condition during the transport of sputtered particles to the substrate. So far it has been shown that the self-sustained mode of magnetron operation can be obtained using dc powering (dc-SSS) only. The main disadvantage of the dc-SSS process is its instability related to random arc formation. In such case the discharge has to be temporarily extinguished to prevent damaging both the magnetron source and power supply. The authors postulate that pulsed powering could protect the SSS process against arcs, similarly to reactive pulsed magnetron deposition processes of insulating thin films. To put this concept into practice, (i) the high enough plasma density has to be achieved and (ii) the type of pulsed powering has to be chosen taking plasma dynamics into account. In this article results of pulsed dc self-sustained magnetron sputtering (pulsed dc-SSS) are presented. The planar magnetron equipped with a 50mm diameter and 6mm thick copper target was used during the experiments. The maximum target power was about 11kW, which corresponded to the target power density of ∼560W∕cm2. The magnetron operation was investigated as a function of pulse frequency (20–100kHz) and pulse duty factor (50%–90%). The discharge (argon) extinction pressure level was determined for these conditions. The plasma emission spectra (400–410nm range) and deposition rates were observed for both dc and pulsed dc self-sustained sputtering processes. The pulse characteristics of the voltage and current of the magnetron source during pulsed dc-SSS operation are shown. The presented results illustrate that a stable pulsed dc-SSS process can be obtained at a pulsing frequency in the range of 60–90kHz and duty factor of 80%–90%.