PdO films were obtained by thermal deposition of palladium metal with a thickness of 30 and 90 nm, followed by its oxidation in air at different temperatures. PdO oxide films are characterized by transmission electron microscopy (TEM) and reflection high-energy electron diffraction (RHEED). Data on the semiconductor properties and gas sensitivity to different concentrations of ozone in the air are obtained. The optimal temperature conditions for the oxidation of the films are established, which ensure their uniform phase composition and the absence of electrical noise during the detection of gases. The mechanism of the electrical noise appearance in ultrathin films associated with their fragmentation during oxidative annealing is proposed and justified. The possibility of detecting ozone impurities in the air below the maximum permissible concentration (MPC) by PdO semiconductor films is shown.

Abstract. The aim of the work is to show the effect of layer thickness on the features of the morphology and optical properties of MoS2 nanostructures, including the monomolecular layers, formed during the gas transporting transfer of sulfur vapors to the reactor hot zone with a molybdenum metal and subsequent deposition on the mica (muscavite) substrates. The results of the atomic force microscopy, optical absorption spectroscopy and Raman spectroscopy of molybdenum disulfide nanostructures of different thickness, obtained in temperatures interval of gas transport synthesis 525-600°C, show that a monomolecular MoS2 layers, containing trigonal domains and having a width of the band gap 1.84 eV at a direct-gap optical transition with the formation of excitons at room temperature, can be obtained. For the first time, fractal-like substructures were obtained, in the Raman spectra of which the values of the modes of intralayer and interlayer oscillations E12g 377.5 cm-1 and A1g 403.8 differ not only from the corresponding values of the modes of the monomolecular layer, but also from the known values of bulk samples. The frequency of the intralayer mode in these samples, E12g 377.5 cm-1, is the smallest of all known values.