We report the synthesis of tungsten diselenide (WSe₂) flakes and continuous layers using an atmospheric pressure thermally assisted conversion (TAC) method, where the tungsten (W) layers were pre-deposited by a magnetron sputtering system onto fused silica substrates. Optical microscopy (OM) and atomic force microscopy (AFM) mapping predominantly revealed the formation of isolated flakes with different shapes, mainly concentrated near the substrate’s edges, which tended to form clusters and to further overlap to continuous layers, moving to the central part of the fused silica substrates. Raman spectroscopy and photoluminescence measurements confirmed the existence of atomically thin flakes and 2H-WSe₂ continuous layers. The measured current–voltage characteristics indicated Ohmic behavior under dark conditions and photo illumination. Finally, the demonstrated resistor-like behavior suggested unlimited prospects for WSe₂ integration into a variety of heterostructures.

Platinum diselenide (PtSe₂), which belongs to the transition metals dichalcogenide (TMDCs) class of 2D materials, is characterized with a transition from semimetal to semiconductor with a thickness variation from bulk to monolayer and found in versatile applications especially in sensors and mid-infrared detectors. In this study we report the large-scale synthesis of PtSe₂ layers by thermally assisted selenization of pre-deposited platinum films in a horizontal quartz-tube Chemical Vapor Deposition (CVD) reactor. Raman spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) are used for characterization of the obtained 2D PtSe₂. It is observed that the Raman spectra of PtSe₂ show strong dependence on the thickness (Pt deposition time). XPS analysis was applied to examine the chemical compositions in order to assess the quality of the synthesized PtSe₂ films. All the studied properties reveal great potential to obtain continuous layers with a controlled thickness and composition and further potential for integration in functional heterostructures for future nanoelectronic and optoelectronic devices.

Recently, low-dimensional structures in the form of bulk crystals and nanoflakes have received considerable interest due to their 2D unique functionality and promising applications in electronics, photonics, sensing devices and photovoltaic solar cells. As a result, remarkable efforts and modifications have been made for the synthesis process of crystalline material by the vapor transport technique. Here, an alternative concept of NbSe₂ crystal growth by the chemical vapor transport (CVT) technique using bromine as a vapor transport agent is presented and subsequently analyzed by X-ray diffraction (XRD), Raman and X-ray photoelectron spectroscopy (XPS) spectroscopy. X-ray powder diffraction analysis revealed hexagonal 2H-NbSe₂ and 4H-NbSe₂ phases, and characteristic Raman and XPS spectra typical for crystalline NbSe₂ were obtained. The environmental sensitivity of the grown crystals is manifested by luminescence attributed to oxidized Nb at the samples’ surface.

Two-dimensional transition metal dichalcogenides (TMDCs) require highly controllable and scalable synthesis methods for successful integration into next-generation optoelectronic technologies. This study presents a modified two-step thermally assisted conversion approach for synthesizing 2D tungsten diselenide (WSe₂) by introducing an intermediate UV–ozone treatment. Magnetron-sputtered tungsten films are exposed to UV–ozone, converting the precursor into a uniform, dense layer of amorphous tungsten trioxide (WO₃) prior to the selenization process via chemical vapor deposition. X-ray photoelectron spectroscopy and Raman spectroscopy confirm the complete phase transition from the oxidized precursor to the 2H-WSe₂ crystal lattice. Morphological evaluations utilizing transmission electron microscopy and atomic force microscopy demonstrate that the ozonated precursors yield highly uniform, triangular flakes exceeding 5 µm in lateral size, effectively eliminating the unreacted WO₃ phases observed in untreated samples. Furthermore, the intermediate oxidation step finetunes the electronic band structure; the resulting WSe₂ exhibits an enhanced p-type character with a valence band maximum shift to 0.35 eV, a tuning attributed to residual oxygen doping. Optical characterizations reveal significantly improved transmittance in the visible spectrum, accompanied by excitonic absorption shifts indicative of reduced layer dimensionality. This intermediate ozonation strategy provides a highly effective pathway for producing high-quality WSe₂ nanosheets with tailored structural and optoelectronic properties.