The Composite TiO2-CuOx Layers Formed by Electrophoretic Method for CO2 Gas Photoreduction.

This study demonstrates the ability to control the properties of TiO2-CuOx composite layers for photocatalytic applications by using a simple electrophoretic deposition method from isopropanol-based suspension. To obtain uniform layers with a controlled composition, the surfactant sodium lauryl sulfate was used, which influenced the electrophoretic mobility of the particles and the morphology of the deposited layers. The TiO2-CuOx composite layers with different CuOx contents (1.5, 5.5, and 11 wt.%) were obtained. It is shown that the optical band gap measured by UV-VIS-NIR diffuse reflectance spectra. When CuOx is added to TiO2, two absorption edges corresponding to TiO2 and CuOx are observed, indicating a broadening of the photosensitivity range of the material relative to pure TiO2. An open-circuit potential study shows that by changing the amount of CuOx in the composite material, one can control the ratio of free charge carriers (n and p) and, therefore, the catalytic properties of the material. As a result, the TiO2-CuOx composite layers have enhanced photocatalytic activity compared to the pure TiO2 layer: methanol yield grows with increasing CuOx content during CO2 photoreduction.

Artificial Anisotropy in Ge2Sb2Te5 Thin Films after Femtosecond Laser Irradiation.

Ge2Sb2Te5 (GST225) looks to be a promising material for rewritable memory devices due to its relatively easy processing and high optical and electrophysical contrast for the crystalline and amorphous phases. In the present work, we combined the possibilities of crystallization and anisotropic structures fabrication using femtosecond laser treatment at the 1250 nm wavelength of 200 nm thin amorphous GST225 films on silicon oxide/silicon substrates. A raster treatment mode and photoexcited surface plasmon polariton generation allowed us to produce mutually orthogonal periodic structures, such as scanline tracks (the period is 120 ± 10 µm) and laser-induced gratings (the period is 1100 ± 50 nm), respectively. Alternating crystalline and amorphous phases at the irradiated surfaces were revealed according to Raman spectroscopy and optical microscopy studies for both types of structures. Such periodic modulation leads to artificial optical and electrophysical anisotropy. Reflectance spectra in the near infrared range differ for various polarizations of probing light, and this mainly results from the presence of laser-induced periodic surface structures. On the other hand, the scanline tracks cause strong conductivity anisotropy for dc measurements in the temperature range of 200-400 K. The obtained results are promising for designing new GST225-based memory devices in which anisotropy may promote increasing the information recording density.

Antitumor Activity against A549 Cancer Cells of Three Novel Complexes Supported by Coating with Silver Nanoparticles.

A novel biologically active organic ligand L (N'-benzylidenepyrazine-2-carbohydrazonamide) and its three coordination compounds have been synthesized and structurally described. Their physicochemical and biological properties have been thoroughly studied. Cu(II), Zn(II), and Cd(II) complexes have been analyzed by F-AAS spectrometry and elemental analysis. The way of metal-ligand coordination was discussed based on FTIR spectroscopy and UV-VIS-NIR spectrophotometry. The thermal behavior of investigated compounds was studied in the temperature range 25-800 °C. All compounds are stable at room temperature. The complexes decompose in several stages. Magnetic studies revealed strong antiferromagnetic interaction. Their cytotoxic activity against A549 lung cancer cells have been studied with promising results. We have also investigated the biological effect of coating studied complexes with silver nanoparticles. The morphology of the surface was studied using SEM imaging.

Rewritable and Tunable Laser-Induced Optical Gratings in Phase-Change Material Films.

Laser-induced periodic surface structures (LIPSS) can be fabricated in virtually all types of solid materials and show great promise for efficient and scalable production of surface patterns with applications in various fields from photonics to engineering. While the majority of LIPSS manifest as modifications of the surface relief, in special cases, laser impact can also lead to periodic modulation of the material phase state. Here, we report on the fabrication of high-quality periodic structures in the films of phase-change material Ge2Sb2Te5 (GST). Due to considerable contrast of the refractive index of GST in its crystalline and amorphous states, the fabricated structures provide strong spatial modulation of the optical properties, which facilitates their applications. By changing the excitation laser wavelength, we observe the scaling of the grating period as well as transition between formation of different types of LIPSS. We optimize the laser exposure routine to achieve large-scale high-quality phase-change gratings with controllable period and demonstrate their reversible tunability through intermediate amorphization steps. Our results reveal the prospects of fast and rewritable fabrication of high-quality periodic structures for photonics and can serve as a guideline for further development of phase-change material-based optical elements.

Influence of Illumination on Porous Silicon Formed by Photo-Assisted Etching of p-Type Si with a Different Doping Level.

The influence of illumination intensity and p-type silicon doping level on the dissolution rate of Si and total current by photo-assisted etching was studied. The impact of etching duration, illumination intensity, and wafer doping level on the etching process was investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), and Ultraviolet-Visible Spectroscopy (UV-Vis-NIR). The silicon dissolution rate was found to be directly proportional to the illumination intensity and inversely proportional to the wafer resistivity. High light intensity during etching treatment led to increased total current on the Si surface. It was shown that porous silicon of different thicknesses, pore diameters, and porosities can be effectively fabricated by photo-assisted etching on a Si surface without external bias or metals.

The vacuum arc ion source for indium and tin ions implantation into phase change memory thin films.

One of the most prospective electrical and optical nonvolatile memory types is the phase change memory based on chalcogenide materials, particularly Ge2Sb2Te5. Introduction of dopants is an effective method for the purposeful change of Ge2Sb2Te5 thin film properties. In this work, we used the ion implantation method for the introduction of In and Sn into Ge2Sb2Te5 thin films by a Multipurpose Test Bench (MTB) at the National Research Center "Kurchatov Institute"-Institute for Theoretical and Experimental Physics. For Sn and In ion implantation into Ge2Sb2Te5, the following MTB elements were used: a vacuum arc ion source, an electrostatic focusing system, and a system for current and beam profile measurements. The MTB parameters for Sn and In ion implantation and its effect on the material properties are presented. Implanted Ge2Sb2Te5 thin films were irradiated by femtosecond laser pulses. It was shown that the ion implantation resulted in a decrease in the threshold laser fluence necessary for crystallization compared to the undoped Ge2Sb2Te5.