Molybdenum disulfide is a crystalline material which attracts considerable attention due to explicit two-dimensional cha- racter of its electronic properties. To obtain MoS2 films thermally evaporated molybdenum and gaseous H2S were used as precursors in this work. As a result of chemical reaction of these precursors films consisting of flake-like of nanometer thickness assembled from parallel atomic layers with predominantly perpendicular (with respect to substrate surface) orientation were deposited on the surface of Si substrate. In this work we investigate the dependence of film morphology on deposition time, substrate temperature and concentration of precursors in gaseous phase. Presence of mono- and bi-layered structures in the film was revealed using Raman spectroscopy and electron microscopy. Dependence of photoluminescence properties on size of crystallites in produced films was also studied.

Molybdenum disulfide is a crystalline material which attracts considerable attention due to explicit two-dimensional character of its electronic properties. To obtain MoS 2 films thermally evaporated molybdenum and gaseous H 2 S were used as precursors in this work. As a result of chemical reaction of these precursors films consisting of flake-like of nanometer thickness assembled from parallel atomic layers with predominantly perpendicular (with respect to substrate surface) orientation were deposited on the surface of Si substrate. In this work we investigate the dependence of film morphology on deposition time, substrate temperature and concentration of precursors in gaseous phase. Presence of mono- and bi-layered structures in the film was revealed using Raman spectroscopy and electron microscopy. Dependence of photoluminescence properties on size of crystallites in produced films was also studied. Keywords: 2D materials, transition metal dichalcogenides, flakes, monolayers, mesoporous films.

In this work thin film coatings based on WS 2 , MoS 2 , MoO 2 and their composites were synthesized, morphological and structural properties of deposited coatings were studied. Chemical vapor deposition with heated MoO 3 , WO 3 , S powder as precursors was used. Dependence of structural and morphological properties, chemical composition of deposited films on parameters of synthesis was defined. Films of vertically aligned 10 nm thick plate crystals consisting both of pure MoO 2 and MoO 2 covered with thin MoS 2 layer were obtained. Formation of polycrystalline films of regular triangular shaped WS 2 and uniform continuous 20 nm thick WS 2 films with covering area of 2x2 mm has also been observed. In this work we also report about synthesis of films consisting of regular triangular shaped WS 2 crystals and MoS 2 irregularly shaped crystals overlapping each other. Keywords: 2D materials, transition metal dichalcogenides, heterostructures, CVD, AFM.

In this work thin film coatings based on WS2, MoS2, MoO2 and their composites were synthesized, morphological and structural properties of deposited coatings were studied. Chemical vapor deposition with heated MoO3, WO3, S powder as precursors was used. Dependence of structural and morphological properties, chemical composition of deposited films on parameters of synthesis was defined. Films of vertically aligned 10 nm thick plate crystals consisting both of pure MoO2 and MoO2 covered with thin MoS2 layer were obtained. Formation of polycrystalline films of regular triangular shaped WS2 and uniform continuous 20 nm thick WS2 films with covering area of 2x2mm has also been observed. In this work we also report about synthesis of films consisting of regular triangular shaped WS2 crystals and MoS2 irregularly shaped crystals overlapping each other.

The formation mechanisms of the zero-phonon line optical center at 580 nm (H19 center) in photoluminescence spectra of irradiated natural diamonds and those deposited from the vapor phase were studied after their high-temperature vacuum annealing. The photoluminescence band intensity of the H19 center was shown to increase exponentially as the annealing temperature increased. Temperature dependences of photoluminescence spectra and local mechanical stress effects on the position and full width at half-height of the 580-nm zero-phonon line optical peak led to the conclusion that the H19 optical center was a complex intrinsic vacancy defect.

Raman spectra of irradiated with fast neutrons or MeV ion-implanted radiation-damaged natural and CVD diamonds and chemically purified detonation nanodiamonds are investigated. The influence of radiation damage level and effects of high-temperature annealing on the intensity and spectral shape of the 1640 cm−1 band is studied. It is shown that in radiation-damaged diamonds this band consists of at least six Gaussian peaks, the intensity of which varies one to one both with the level of radiation disordering and the temperature of the subsequent annealing. The “1640” band in radiation-damaged diamonds is completely annealed at temperatures above 1000 °C, while in detonation nanodiamonds annealing up to 1200 °C does not significantly affect its shape and intensity.

The results of studying the formation of graphene layers during thermal pyrolysis of methane on the surface of polycrystalline nickel are presented. The studies have been carried out using a technique that allows controlling the change in the surface topology with high spatial resolution using a scanning tunneling microscope located directly in the reaction chamber providing no contact between the formed graphene with air. The measurements have revealed the formation of graphene layers in the form of a set of nanobubbles with characteristic sizes of about 100 nm. It has been found that the local topology of the graphene layer can change under the influence of a tunneling microscope probe depending on the applied voltage.

The results of graphene layers formation on Ni surface due to methane pyrolysis are presented in this work. The investigation was carried out using technique that allows controlling morphology of the sample surface with high spatial resolution. This technique includes the use of scanning tunnel microscope (STM) introduced inside the reaction chamber which allows to get rid of atmosphere gases impact. Bubble structure of obtained few-layer graphene film with typical diameter about 100 nm was observed. It was found that local morphology of these bubbles can be easily changed by increasing tunnel voltage applied to the STM tip.

Graphene film formation by carbon deposition from gaseous phase on nickel substrates is investigated using scanning tunnel microscope (STM) unit embedded into reactor of the chemical vapor deposition (CVD) system. The microscope was designed to provide STM measurements at the same 1 mu m x 1 mu m region on the sample surface before and just after CVD synthesis without taking the sample out of the reactor. The peculiarities of graphene deposits formation on polycrystalline nickel substrates are revealed using developed CVD-STM system. The topology features are analyzed in combination with Raman spectroscopy data. One of particular features revealed in this study is nanobubbles formation and collapse on graphene film surface. We are discussing possible mechanisms of this phenomenon.

We studied defects and stress distributions in mosaic epitaxial diamond film using a confocal Raman spectroscopy, with a special attention to the junction area between the crystals. The mosaics was grown by microwave plasma CVD on closely arranged (100)-oriented HPHT type Ib substrates. The width of stress affected and defect enriched region around the junction show a tendency of extending with the film thickness, from ≈40μm on the film-substrate interface to ≈250μm in the layer 500μm above the substrate, as found from the mosaics analysis in cross-section. The stress field around the junction demonstrates a complex pattern, with mixed domains of tensile and compressive stress, with maximum value of σ≈0.6GPa. A similar non-uniform pattern was observed for defect distribution as well. No sign of amorphous sp2 carbon in the junction zone was revealed.

In this work the Raman spectroscopy abilities for diagnostics of carbon onions synthesized from nanodiamonds have been analyzed. Several series of nanodiamonds transformed into onion-like carbon by heating at 1000-1900 K in vacuum were characterized with Raman spectroscopy. A high resolution transmission electron microscopy (HRTEM) was used to estimate the average size of nanodiamonds in the series synthesized by different methods. Each series consisted of a pristine nanodiamond powder and materials appeared after its heat treatment at different temperatures in vacuum. The changes corresponding to the nanodiamond crystal transformation into the onion-like carbon (via the stage of diamond cores enveloped by a few layer graphene) have been revealed in Raman spectra. The basic attention has been paid to behavior of D (disorder-induced), G (graphite) and 2D (two-phonon scattering)-bands in the Raman spectra.