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168 results on '"Hubička, Z."'

10. CuFeO2 prepared by electron cyclotron wave resonance-assisted reactive HiPIMS with two magnetrons and radio frequency magnetron sputtering.

Author

Písaříková, A., Olejníček, J., Venkrbcová, I., Nožka, L., Cichoň, S., Azinfar, A., Hippler, R., Helm, C. A., Mašláň, M., Machala, L., and Hubička, Z.

Subjects
RADIO frequency, MAGNETRON sputtering, IRRADIATION, PHOTOCATHODES, CYCLOTRON resonance, FUSED silica, REACTIVE sputtering, MAGNETRONS
Abstract

In this study, thin films of CuFeO2 were prepared using radio frequency reactive sputtering (RF) and reactive high-power impulse magnetron sputtering combined with electron cyclotron wave resonance plasma (HiPIMS-ECWR). The plasma was characterized using an RF ion probe. Plasma density, tail electron energy, and electron temperature were extracted from the measured data. The films were deposited on fluorine-doped tin oxide-coated glass and quartz glass, with the substrates being heated during the deposition process. The final delafossite CuFeO2 structure was formed after annealing in an argon gas flow at 550–600 °C. The ideal deposition conditions were found to be with a stoichiometric ratio of Cu:Fe = 1:1, which was the optimal condition for creating the delafossite CuFeO2 structure. The measured optical bandgap of CuFeO2 was 1.4 eV. The deposited CuFeO2 films were subjected to photoelectrochemical measurements in the cathodic region to investigate their potential application in solar photocatalytic water splitting. The films showed photocatalytic activity, with a photocurrent density of around 70 μA/cm2 (under an incident light irradiation of 62 mW/cm2, AM 1.5 G). The electrochemical properties of the layers were studied using open circuit potential, linear voltammetry, and chronoamperometry. The surface morphology and chemical composition of the layers were analyzed by atomic force microscopy and energy-dispersive x-ray spectroscopy, respectively. The crystalline structure was determined using XRD and Raman spectroscopy. The results of these methods are presented and discussed in this article. [ABSTRACT FROM AUTHOR]

Published
2023
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18. In-situ impedance spectroscopy of a plasma-semiconductor thin film system during reactive sputter deposition.

Author

Zanáška, M., Kudrna, P., Čada, M., Tichý, M., and Hubička, Z.

Subjects
SPUTTER deposition, THIN films, REACTIVE sputtering, THIN film deposition, IMPEDANCE spectroscopy, DIELECTRIC films
Abstract

We present a comparatively simple-to-apply in situ diagnostic suitable for determining the dielectric properties of nonconducting and semiconducting thin films during plasma-aided deposition. The method is based on measurement of the impedance spectrum of a system plasma-film within the kilohertz range of frequencies, i.e., without the need of special equipment. Total film capacitance, resistance, and the loss factor tan δ can be estimated in situ from the measured impedance spectra. Provided that the film thickness is known, the dielectric and electrical properties of the deposited films, such as relative permittivity ɛr and conductivity σ, can be estimated as well. The applicability of the developed method is demonstrated on Fe2O3 and TiO2 thin films during deposition in a low-pressure low-temperature plasma-jet system and on a TiO2 thin film during deposition in a planar magnetron system. The experimentally obtained dielectric properties are compared with data from the literature. [ABSTRACT FROM AUTHOR]

Published
2019
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30. Measurement and modeling of plasma parameters in reactive high-power impulse magnetron sputtering of Ti in Ar/O2 mixtures.

Author

Čada, M., Lundin, D., and Hubička, Z.

Subjects
MAGNETRON sputtering, PLASMA density, ELECTRON temperature, TITANIUM, ARGON, OXYGEN, SPUTTERING (Physics)
Abstract

A reactive high-power impulse magnetron sputtering (HiPIMS) process using a titanium target in a mixture of Ar/O2 has been investigated for different modes of operation including pure argon, metallic, transition, and compound mode. The trends and changes in the plasma density ne and the effective electron temperature Teff, have been measured by the time-resolved Langmuir probe technique. The same experimental process conditions have also been studied using a recently developed reactive ionization region model (R-IRM), making it possible to compare the acquired experimental results with the model results. It was found that trends in the plasma density and mean electron energy as measured by the Langmuir probe are in good agreement with the results obtained from the R-IRM model for different pulse discharge current densities. The effective electron temperature generally increases with an increasing oxygen flow rate. It is likely due to a reduction of sputtered Ti, due to compound formation on the target, which forces the discharge to increase the electron energy to increase the ionization rate of the process gas (Ar/O2) to maintain a high HiPIMS discharge current. Small variations in the plasma density were detected between the middle part of the plasma pulse as compared to the end of the plasma pulse, when transitioning from the metal mode to the poisoned mode. It is found that the time-evolution of the electron density is rather well correlated with the discharge current waveform. On the other hand, the mean electron energy did not change significantly between the middle and the end of the plasma pulse. For the lower pulse discharge current, both the model and experimental data have shown a slight increase in the plasma density with increasing O2 mass flow rate. [ABSTRACT FROM AUTHOR]

Published
2017
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