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Abstract Relatively low and high deposition rates of BC х films were realized by pulsed laser ablation of mixed B–diamond and dual B–graphite targets, respectively. Deposition was performed at 500 °C and the rate of film deposition was determined with respect to the number of atomic monolayers (obviously less or more than one monolayer) grown for one laser pulse. In the case of BC х films formation with a low deposition rate, doping with B facilitated the growth of the nanocomposite structure, which possessed an increased fraction of sp 3 bonds, a very low electrical resistance, and an improved mechanical performance. The change of the sheet resistance of these films as the temperature was reduced from 300 to 65 K had a metallic character. For about 95-nm-thick films with bulk compositions of BC 1.7 and BC 0.6 , the resistivity at room temperature were approximately equal to 1.5 mΩ·cm, and the lowest resistivity of 0.23 mΩ·cm was detected for B-enriched film at 85 K. With an increase in the B atom concentration in such films, the charge carrier (holes) concentration decreased, and their mobility increased from 180 to 10,500 cm2·V−1·s−1 due to samples cooling. The application of a higher deposition rate from the dual B–graphite target activated surface migration of condensed atoms, which caused the development of granular morphology, the B segregation and the reduction of the sp 3 bond fraction. The hardness and electrical conductivity of such films were obviously inferior to those of the films obtained by PLD with a low deposition rate. Graphical abstract Unlabelled Image Highlights • Pulsed laser deposition of BC x films with different growth rates was made at 500 °C. • Peculiarity of diamond-containing target application for film deposition was studied. • Low deposition rate facilitated the formation of B-doped DLC with highest sp 3 content. • High deposition rate resulted in lower sp 3 content and B inclusions in the films. • BC x films with low resistivity and high mechanical performance can be obtained. [ABSTRACT FROM AUTHOR]

Pulsed laser irradiation (wavelength 1.06 μm) of a molybdenum diselenide target in vacuum caused the formation of Mo-enriched particles on the surface of the target. Nanoparticles ~ 5–50 nm in size were torn from the target and deposited on the substrate. The use of a buffer gas (argon, pressure 5 Pa) increased the thickness of the shells formed around the nanoparticles and modified the chemical composition of the films. Heating the substrate caused the crystallization of the matrix, such that the basal planes were oriented in a direction parallel to the film surface. The orientation of the planes changed in the shells. The edge sites occurred at the film surface, exhibiting the enhanced catalytic activity in hydrogen evolution reaction. The deposition of MoSe x /Mo films in a nanocrystalline state on the carbon electrode caused a decrease in the overvoltage of more than 270 mV, and the lowest Tafel slope was 86 mV/dec. [ABSTRACT FROM AUTHOR]

Abstract: WSe x thin films were obtained by pulsed laser deposition in vacuum and at various Ar gas pressures up to 10Pa. Stoichiometry and chemical state of the WSe x films were studied by means of Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy. In the case of pulsed laser deposition of WSe x films in vacuum the value of stoichiometric coefficient x was 1.3. During the deposition in argon at pressures of 2–10Pa the value of x varied from 1.5 to 2.2. To explain the influence of the buffer gas, a model was used that takes into account the following processes: (1) congruent pulsed laser evaporation of the WSe2.2 target; (2) scattering of laser-evaporated W and Se atoms in Ar; (3) sputtering of the deposited film by high-energy atoms from the laser plume. Experimentally, the velocity distributions of laser-evaporated W and Se atoms in vacuum were determined by the time-of-flight measurements. Collision Monte Carlo simulations were used to quantify the impact of the buffer gas on the energy and the incidence angle distributions of the deposited W and Se atoms. Model distributions were used to determine the chemical composition of the WSe x films, depending on the efficiency of the preferential sputtering of Se atoms. [Copyright &y& Elsevier]