This work was devoted to studying the atomic structure and electron spectrum of
a
-SiO
x
: H films created on silicon and glass substrates by means of plasma-enhanced chemical vapor deposition ...(PECVD). Depending on the conditions of oxygen supply into the reactor, the stoichiometric parameter
x
of the films was varied from 0.57 to 2. The structure of the films and the specific features of their electron structure were characterized depending on the parameter
x
with a complex of structural and optical methods and ab initio quantum-chemical simulation for the model SiO
x
structure. The studied SiO
x
: H films were established to consist predominantly of silicon suboxides SiO
y
, SiO
2
clusters, and amorphous silicon. Based on the spatial fluctuations of their chemical composition, the model of bandgap width and potential fluctuations was proposed for SiO
x
electrons and holes. The obtained data would provide the charge transport in
a
-SiO
x
: H films with more precise modeling important for the creation of nonvolatile random-access memory (RAM) elements and memristors on their basis.
The task of automation and increasing the efficiency of calculating the parameters of the rectifying column for the needs of chemical production is being solved. Rectification is one of the most ...time-consuming chemical-technological processes responsible for the separation of liquid mixtures into practically pure components, which differ in boiling points, by repeated evaporation of the liquid and vapor condensation. The possibility of separation of the liquid mixture into its constituent components by distillation is due to the fact that the composition of the vapor formed above the liquid mixture differs from the composition of the liquid mixture under the conditions of the equilibrium state of steam and liquid. To select the optimal working conditions, it is necessary to take into account the heat consumption, temperature and pressure of the heat carrier - heating steam and cooling water, as well as the necessary dimensions of the columns and connecting elements with it by heat exchangers. All these factors are interrelated and depend, in particular, on the temperature and state of aggregation of the mixture supplied for separation. When calculating the processes of rectification, the compositions of liquids are usually given in mass fractions or percent, and for practical calculation it is more convenient to use the compositions of liquids and steam, expressed in molar fractions or percent. The software being developed will automate the calculation of distillation plants, which will increase the calculation speed. In most existing installations, rectification is not clear. The resulting components of light and oil distillates do not correspond to the required fractional composition, overgrowth of fractions is observed, some of the heaviest fractions of light diesel oil products fall into the bottom of the column, into fuel oil. Therefore, much attention is paid to the study and analysis of the operation of distillation columns, improving the methods of their calculation. The software created as a result of the project will be used directly by technologists, chemists and professors.
We study the charge transport mechanism of electron via traps in thermal SiO2 on silicon. Electron transport is limited by phonon-assisted tunnelling between traps. Charge flowing leads to oxygen ...vacancies generation, and the leakage current increases. Long-time annealing at high temperatures decreased the leakage current to initial values due to oxygen vacancies recombination with interstitial oxygen. Taking into account results of ab initio simulations, we found that the oxygen vacancies act as electron traps in SiO2.
We study the charge transport mechanism in ferroelectric Hf0.5Zr0.5O2 thin films. Transport properties of Hf0.5Zr0.5O2 are described by phonon-assisted tunnelling between traps. Comparison with ...transport properties of amorphous Hf0.5Zr0.5O2 demonstrates that the transport mechanism does not depend on the structure. The thermal and optical trap energies 1.25 eV and 2.5 eV, respectively, in Hf0.5Zr0.5O2 were determined based on comparison of experimentally measured data on transport with simulations within phonon-assisted tunnelling between traps. We found that the trap density in ferroelectric Hf0.5Zr0.5O2 is slightly less than one in amorphous Hf0.5Zr0.5O2. A hypothesis that oxygen vacancies are responsible for the charge transport in Hf0.5Zr0.5O2 is confirmed by ab initio simulation of electronic structure.
The electronic structures of SiOx:H films synthesized by plasma-enhanced chemical vapor deposition on silicon and glass substrates were studied. The film stoichiometric parameter x varied in the ...range from 0.57 to 2 depending on the oxygen supply to the reactor conditions. According to XPS, Raman scattering and high-resolution electron microscopy, a core-shell model of the a-SiOx:H structure was applied. According to this model, the films consist of silicon suboxide SiOy, in which clusters of different compositions are introduced — from amorphous silicon to silicon oxide — with a characteristic size of 2–10 nm. The SiOx:H energy diagram was constructed. The nanoscale potential fluctuations model, according to which Si nanoclusters are potential wells for electrons and holes in SiOx, is proposed. The data obtained are important for the correct interpretation of the charge transport in a-SiOx:H films, and they are important for the development of nonvolatile memory elements on their basis.
•Thermal SiO2 films were treated in ECR hydrogen plasma.•The atomic ratio O/Si in the films decreases from 2.0 to 1.85 after the treatment.•The charge transport in the treated films is described by ...the trap-limited mechanism.•Oxygen vacancies (Si-Si bonds) are the traps participating in the charge transport.•High oxygen vacancy concentration is generated in the films after their treatment.
The charge transport in thin thermal silicon oxide films treated in electron cyclotron resonance hydrogen plasma at different exposure times was investigated. X-ray photoelectron studies show that such treatment leads to the oxygen deficiency of the films. It was established that the treatment of the films in plasma leads to an increase of their conductivity by a factor of about 102. The film charge transport properties were studied at different temperatures and analyzed within four theoretical dielectric conductivity models. It was found that the charge transport mechanism is described by Fowler-Nordheim model in the initial silicon oxide and by the model of phonon-assisted electron tunneling between neutral traps after the treatment in hydrogen plasma. The thermal trap ionization energy value (Wt = 1.6 eV) measured from transport experiments is in agreement with that obtained from ab initio calculations for the oxygen vacancy (Si-Si bond) in SiO2.
The chemical composition, electronic structure, structure, and physical properties a lutetium oxide Lu
2
O
3
film are studied by X-ray photoelectron spectroscopy, ellipsometry, and X-ray absorption ...spectroscopy. The short-range order in Lu
2
O
3
is found to correspond to its cubic modification. The binding energies of the 1
s
and 2
p
levels of oxygen and the 4
d
5/2
and 4
f
7/2
levels of lutetium are 529.2, 5.0 and 7.4, 195.9 eV, respectively. The energy gap determined from the electron energy loss spectrum of the film is 5.9 eV. The electron energy loss spectra have two peaks at 17.4 and 22.0 eV, which can be attributed to the excitation of bulk plasma oscillations. The dispersion of the refractive index is measured by spectral ellipsometry. The refractive index is shown to increase from 1.82 at 1.5 eV to 2.18 at 5.0 eV, and the high-frequency permittivity of Lu
2
O
3
is 3.31.
The silicon oxide thin films obtained by thermal SiO.sub.2 treatment in hydrogen electron cyclotron resonance plasma at various exposure times are investigated. Using X-ray photoelectron ...spectroscopy, we have established that such treatment leads to a significant oxygen depletion of thermal SiO.sub.2, the more so the longer the treatment time. The atomic structure of the SiO.sub.x .sub.< 2 films obtained in this way is described by the random bonding model. The presence of oxygen vacancies in the plasma-treated films is confirmed by comparing the experimental valence band photoelectron spectra and those calculated from first principles, which allows the parameter x to be estimated. We show that thermal silicon oxide films treated in hydrogen plasma can be successfully used as a storage medium for a nonvolatile resistive memory cell.
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