The parameters of plasma and the kinetics of generation and loss of active particles in chlorine-nitrogen mixtures

An investigation is performed of the effect of the initial composition of Cl₂/N₂ mixture on the electrophysical and kinetic parameters of plasma of a dc glow discharge. It is found that the dilution of chlorine with nitrogen causes a variation of the electron energy distribution function (EEDF), which is accompanied by an increase in the average electron energy and in the rate constants of threshold elementary processes. It is demonstrated that the principal mechanism of generation of chlorine atoms is the dissociation of Cl₂ molecules under electron impact; in so doing, the contributions by stepwise processes involving metastable molecules N ₂ ^* (A ³Σ _u ⁺ ) and vibrationally excited molecules N ₂ ^* (v > 7) are negligible. The assumption of the first kinetic order of heterogeneous recombination of chlorine atoms with a probability of (4–5) × 10^?4 provides for adequate agreement between the calculation and experimental data on reduced field intensity, rate constant of recombination, and concentration of atoms.     

Structure and mechanical characteristics of ceramic Nb2O5 and Nb2(1 − y)Ta2y O5

The structure and mechanical characteristics of ceramic Nb₂O₅ and ceramic materials produced from coprecipitated Nb_{2(1 ? y)}Ta_2y O₅ pentoxides by a conventional ceramic processing technique and exposure to high-intensity light have been studied by scanning probe microscopy and Raman spectroscopy.     

BCS-BEC Crossover and Chiral Anomaly in p-Wave Superfluids with the Symmetry of A1-Phase

We solve the Leggett equations for BCS-BEC crossover in the 3D resonance p-wave superfluid with the symmetry of A1-phase. We calculate sound velocity, normal density and specific heat for the BCS-domain (μ>0), BEC-domain (μ<0) as well as close to important point μ=0 in 100% polarized case. We find the indications of quantum phase-transition close to the point μ(T=0)=0. Deep in BCS and BEC-domains the crossover ideas of Leggett and Nozieres, Schmitt-Rink work pretty well. We discuss the spectrum of orbital waves, the paradox of intrinsic angular momentum and complicated problem of chiral anomaly in BCS A1-phase at T=0. We present two different approaches to a chiral anomaly: one based on supersymmetric hydrodynamics, another one on the formal analogy with Dirac equation in quantum electrodynamics (QED theory). We evaluate the damping of nodal fermions due to different decay processes in superclean case at T=0 and find that we are in a ballistic regime ω τ?1. We propose to use aerogel or nonmagnetic impurities to reach hydrodynamic regime ω τ?1 at T=0. We discuss the concept of spectral flow and exact cancellations between time-derivatives of anomalous and quasiparticle currents in the equation for the conservation of total linear momentum. We propose to derive and solve a kinetic equation for nodal quasiparticles both in the hydrodynamic and in the ballistic regimes to demonstrate this cancellation explicitly. We briefly discuss the role of the other residual interactions different from damping and invite experimentalists to measure the spectrum and damping of orbital waves in A-phase of ³He at low temperatures.     

Nanocrystalline silicon films formed under the impact of pulsed excimer laser radiation on polyimide substrates

Polycrystalline silicon films on polyimide substrates were obtained by a method based on the crystallization of amorphous films under the impact of nanosecond pulses of excimer laser radiation. Characteristics of the film structure were studied by methods of Raman scattering and high-resolution electron microscopy. For the laser crystallization regimes employed, nanocrystalline silicon films with an average grain size of 5 nm were obtained. The results are of interest for the development of large-scale microelectronic devices (active thin-film transistor matrices) on cheap flexible substrates.     

Electrophysical parameters and plasma composition of HCl-Cl2 mixtures

The influence of the initial HCl-Cl₂ mixture composition on stationary parameters and the composition of the DC glow discharge plasma (p = 40?C200 Pa, i _p = 15?C35 mA) is investigated. Calculated data on the energy distributions of electrons, the integral characteristics of the electron gas, and the plasma composition are obtained. The character of the influence of the initial mixture composition on the charged particle concentrations is shown to be governed by the dominant mechanism of their destruction at the given gas pressure. The composition of the neutral particles of the HCl-Cl₂ plasma, at a 0?C20% Cl content, is shown to be formed mainly by atomic-molecular processes.     

Radiation hardness of lithium niobate nonlinear optical crystals doped with Y, Gd, and Mg

We have studied the effect of gamma irradiation to various doses on optical characteristics (optical transmission spectra) of nominally undoped, rare earth-doped, and alkaline earth-doped lithium niobate crystals: LiNbO₃, LiNbO₃:Y (0.46 wt %), LiNbO₃:Y,Mg (0.32, 0.24 wt %), LiNbO₃:Mg (0.27 wt %), and LiNbO₃:Gd (0.004, 0.04, 0.26, 0.43 wt %). We have examined the influence of the ionizing radiation dose, the nature of dopants, and their concentration on the optical transmission of the gamma-irradiated doped lithium niobate crystals. The results suggest that gamma-induced changes in the optical transmission of LiNbO₃:Gd (?0.004 and 0.04 wt %) crystals can be used for gamma dosimetry in the dose range ?10¹ to 1.5 × 10⁴ rad.     

Effects of high oxygen concentrations on microbial biosensor signals. Hyperoxygenation by means of perfluorodecalin

Amperometric biosensors register oxygen depletion in response to analyte catabolism, and thus are limited by the availability of dissolved oxygen. Microbial sensors containing immobilized cells of Gluconobacter oxydans were hyperoxygenated to 400% of control levels and the effects on sensor responses to glucose were determined. Oxygenated perfluorodecalin (a completely fluorinated organic substance) was as effective in hyperoxygenation as direct sparging with O2, increasing sensor base medium oxygen concentrations from 9.3 to 37 mg/l. Hyperoxygenation enhanced maximal biosensor response amplitudes, particularly at high cell loading densities. Maximal response rates were also improved, although less dramatically. Results suggest that hyperoxygenation may be a new general approach for modulating biosensor responses.     

HfO2 etching mechanism in inductively-coupled Cl2/Ar plasma

Etching characteristics and the mechanism of HfO₂ thin films in Cl₂/Ar inductively-coupled plasma were investigated. The etch rate of HfO₂ was measured as a function of the Cl₂/Ar mixing ratio in the range of 0 to 100% Ar at a fixed gas pressure (6 mTorr), input power (700 W), and bias power (300 W). We found that an increase in the Ar mixing ratio resulted in a monotonic decrease in the HfO₂ etch rate in the range of 10.3 to 0.7 nm/min while the etch rate of the photoresist increased from 152.1 to 375.0 nm/min for 0 to 100% Ar. To examine the etching mechanism of HfO₂ films, we combined plasma diagnostics using Langmuir probes and quadrupole mass spectrometry with global (zero-dimensional) plasma modeling. We found that the HfO₂ etching process was not controlled by ion-surface interaction kinetics and formally corresponds to the reaction rate-limited etch regime.     

Etching characteristics and mechanism of Pb(Zr,Ti)O3 thin films in CF4/Ar inductively coupled plasma

The effect of the CF₄/Ar mixing ratio on the etching behaviour and mechanisms for Pb(Zr,Ti)O₃ (PZT) thin films in an inductively coupled plasma was carried out. It was found that an increase of Ar mixing ratio causes non-monotonic behaviour of the PZT etch rate, which reaches a maximum of 2.38 nm/s at 80% Ar. Investigating the plasma parameters, we found a weak sensitivity of both electron temperature and electron density to the change of CF₄/Ar mixing ratio. A combination of zero-dimensional plasma model with the model of surface kinetics shows the possibility of a non-monotonic etch rate behaviour due to the concurrence of physical and chemical pathways in the ion-assisted chemical reaction.