Improved integrability and boundedness of solutions to some high-order variational problems

We give a series of results on the improved integrability and boundedness of solutions to several high-order variational problems with strengthened coercivity. In particular, we consider the homogeneous Dirichlet problem on the minimum of integral functionals and study variational inequalities with unilateral and bilateral obstacles and with integral and gradient constraints

Structural properties of nanocomposite SiO₂(Si) films obtained by ion-plasma sputtering and thermal annealing

The nanocomposite SiO₂(Si) films containing Si nanoclusters inside insulating SiO₂matrix are promising for many nanoelectronics applications. The ion-plasma sputtering of Si in O₂ containing gas mixture and following thermal annealing have been used to form nanocomposite SiO₂(Si) films. The structural properties of the obtained films have been studied using several methods. Among them, there were ellipsometry, IR spectroscopy, Raman spectroscopy, and AFM. Transition of SiOx matrix into insulating SiO₂ matrix has been revealed by IR spectroscopy. The shift of the transmittance spectra toward high frequency region and the increase in their intensity have been observed. The existence of amorphous and nanocrystalline phases into SiO₂(Si) films have been confirmed using Raman spectroscopy. Two material phases on the film surface, namely SiO₂ and Si, and surface density of silicon nanoclusters have been determined using AFM. It was shown that the size of silicon nanoclusters and their surface density depend on the level of enrichment with silicon of the initial SiOx film after ion-plasma sputtering and the temperature of subsequent annealing

Effect of low-temperature annealing on light-emitting properties of na-Si/SiOx porous nanocomposite films

The effect of low-temperature annealing on light emitting properties of naSi/SiOx porous column-like nanocomposite films has been studied. Influence of type of chemically active gas or inert ambient on PL characteristics is shown. Existence of metastable defects in such structures is shown. A temperature interval for healing the metastable defects is defined. Mechanisms to reduce a non-radiative recombination channel depending on the gas ambient are proposed

Transformation of SiOx films into nanocomposite SiO₂(Si) films under thermal and laser annealing

Oxide-assisted growth of Si nanocrystals includes deposition of a siliconenriched SiOx film at the first stage and annealing at the second one. The ion-plasma sputtering method has been used for deposition of the SiOx film. The influence of thermal and laser annealing on SiOx film properties has been investigated. Formation of silicon nanoislands on oxide film surface has been observed by AFM both after thermal and laser annealing. The height and surface density of the nanoislands depends both on the silicon content in the initial SiOx film and temperature of thermal annealing. The higher annealing temperature causes formation of large nanoislands, but their surface density decreases. Comparison of nanoislands created at thermal and laser annealing shows that in case of laser annealing the nanoislands are higher and their surface density is lower. The intensity of laser irradiation influences on nanoisland parameters significantly. The growth of electrical conductivity with thermal annealing temperature has been observed. The influence of gas atmosphere during annealing is also significant in case of higher temperatures. In case of laser annealing at the beginning at low laser irradiation intensities, the SiOx film conductivity increases, but the following growth of intensity causes the decrease in electrical conductivity

Influence of deposition rate and substrate temperature on structure and optical features of NiO thin film

Nickel oxide thin films were prepared by direct-current magnetron sputtering method at different deposition rates on unheated and heated substrates. It was shown that the deposited films are the dense arrays of nanowhiskers with the rhombohedral crystalline structure for the unheated substrate and with the face centered cubic structure for the heated substrate. Surface morphology of films consists of nanocrystalline randomly oriented grains. Increasing of the deposition rate and/or the substrate temperature lead to decrease of the film porosity and enlarge of nanocrystals. The maximum oxidation state of the deposited films is observed near the surface