Spatial distributions of the intensity of optical emission lines studied during bismuth ferrite film deposition in high-frequency discharge plasma

We have studied spatial distributions of the intensity of optical emission lines in plasma of the RF discharge in oxygen during the deposition of bismuth ferrite (BiFeO₃) films. The intensities of characteristic emission lines in the visible, near-UV and near-IR spectral ranges have been measured as functions of the distance from the probed plasma layer to the target. The intensity profiles of the emission lines of oxygen ions, oxygen atoms, and iron atoms exhibit different behavior. Differences in the spatial distributions of intensity have been also observed for the two characteristic emission lines (at 613.7 and 688.6 nm) of iron.     

Properties of dust particles formed upon sputtering of a barium strontium titanate ceramic target in plasma of high-frequency discharge in oxygen

We have studied the behavior and properties of dust particles formed upon sputtering of a barium strontium titanate Ba(0.8)Sr(0.2)TiO₃ ceramic target in plasma of capacitive high-frequency discharge in oxygen. The particles were accumulated in potential traps situated near the target at a remote position of the substrate. Dependences of the density of accumulated dust on the pressure, discharge power, substrate position, and substrate voltage were determined using laser-radiation scattering. The dimensions and composition of collected dust particles were determined.     

Magnetic and optical properties of multiferroic bismuth ferrite nanoparticles by tartaric acid-assisted sol-gel strategy

Pure BiFeO₃ nanoparticles have been successfully synthesized through the tartaric acid-assisted sol-gel method at relatively low temperature. The as-prepared nanoparticles were characterized by a variety of techniques. The success in preparing pure BiFeO₃ may be attributed to the formation of heterometallic polynuclear complexes in the tartaric acid system. The ferroelectric phase transition (T_C = 851 °C) was determined, revealing the ferroelectric nature of the as-prepared BiFeO₃ nanoparticles. The result of magnetic measurement indicates the weak ferromagnetic order of BiFeO₃ nanoparticles at room temperature, which may be ascribed to the size confinement effect. The observed strong absorption in the UV region will enable BiFeO₃ nanoparticles to be potentially used as promising photocatalytic decomposition material.     

On the high-frequency instability of plasma in the octupole galathea electric discharge trap

Spectra of microwave plasma oscillations in an electric discharge trap are considered, and specific features of these spectra related to the instability of transverse current near the magnetic barrier confining the plasma are revealed. A relation between oscillations of the discharge current and the modulation of intensity of the microwave oscillations is established which indicates that the barrier region of discharge possesses an anomalous resistivity.     

The optical emission spectroscopy study of an rf-plasma-enhanced magnetron sputtering system

Optical emission spectroscopy has been performed for unbalanced DC magnetron sputtering of Cu in Ar atmosphere with the enhanced ionization of inductively coupled plasma. The intensities of Cu, Cu⁺, Ar and Ar⁺ lines were measured at various discharge parameters such as pressure and rf power. Both Cu and Cu⁺ lines intensities initially increase and then decrease with increasing pressure. At the same time, Ar line intensity increases and the Ar⁺ line intensity decreases with increasing pressure. With increasing rf power, all the lines intensities increase at different rates and become saturated when the rf power is greater than 700 W. The rf discharge exhibits mode jumping (E-mode to H-mode) and hysteresis phenomena. When the rf power increases to 400 W, the rf discharge mode jumps from E-mode to H-mode. When the rf power input decreases from 800 to 300 W, the rf discharge mode jumps back from H-mode to E-mode. However, during the mode change, the intensities of all lines are higher when switching from H-mode to E-mode than those when switching from E-mode to H-mode at the same rf power. In the rf power region, the ionization of Cu is significantly enhanced. The reasons of these phenomena are discussed.     

Time-resolved optical emission spectroscopy of pulsed RF plasmas with copper magnetron sputtering

Time-resolved optical emission spectroscopy is used to investigate the discharge of the RF pulse sputtering of copper. The time integrated emission of a neutral copper atom in RF pulse sputtering was found to be superior to emission in continuous mode. The increase stemmed from the concentration of the power in the sharp pulse at the breakdown of the discharge. The integrated emission reached its maximum at 50% duty ratio. A sudden drop in the copper emission in continuous mode from that of a 98% duty ratio was correlated with an absence of the power peak of the pulse mode.     

On the efficiency of emission from a plasma column in high-pressure pulse-periodic discharge in cesium

Spectral energy fluxes emerging from the surface of an axially symmetric column of inhomogeneous cesium high-pressure plasma have been calculated by direct integration of the radiation-transport equation. It is shown that, at a specified plasma temperature on the axis, irrespective of the radiation -formation mechanism and the radial distribution of the plasma parameters, the maximum energy fluxes arise when the radial optical thickness τ _R of the plasma column is close to unity. The asymptotic τ _R value, at which the discharge column radiation is the largest part of the Planck radiation, has been found.     

Heating of polymer substrate by discharge plasma in radiofrequency magnetron sputtering deposition

The substrate used for the thin film deposition in a radiofrequency magnetron sputtering deposition system is heated by the deposition plasma. This may change drastically the surface properties of the polymer substrates. Deposition of titanium dioxide thin films on polymethyl methacrylate and polycarbonate substrates resulted in buckling of the substrate surfaces. This effect was evaluated by analysis of atomic force microscopy topography images of the deposited films. The amount of energy received by the substrate surface during the film deposition was determined by a thermal probe. Then, the results of the thermal probe measurements were used to compute the surface temperature of the polymer substrate. The computation revealed that the substrate surface temperature depends on the substrate thickness, discharge power and substrate holder temperature. For the case of the TiO₂ film depositions in the radiofrequency magnetron plasma, the computation indicated substrate surface temperature values under the polymer melting temperature. Therefore, the buckling of polymer substrate surface in the deposition plasma may not be regarded as a temperature driven surface instability, but more as an effect of argon ion bombardment.     

Determination of trace bismuth in human serum by cloud point extraction coupled flow injection inductively coupled plasma optical emission spectrometry

A cloud point extraction method for the preconcentration of ultra-trace bismuth in human serum prior to its determination by inductively coupled plasma optical emission spectrometry had been developed in this paper. The cloud point extraction method was based on the complex of Bi(III) with 8-hydroxyquinoline and Triton X-114 was used as non-ionic surfactant. The main factors affecting cloud point extraction efficiency, such as pH of solution, concentration of complexing agent, concentration of non-ionic surfactant, equilibration temperature and time were investigated in detail. An enrichment factor of 81 was obtained for the preconcentration of Bi(III) with 25 mL solution. Under the optimal conditions, the detection limit of Bi(III) is 0.12 μg L⁻¹. The relative standard deviation (n = 7) of determination was 2.3%, values of recovery of bismuth were from 92.3% to 94.7% for three samples. This method is simple, accurate, sensitive and can be applied to the determination trace bismuth in human serum.     

Direct atomic emission analysis of bismuth and germanium oxides and bismuth orthogermanate crystals using two-jet arc plasma

Simple, high-speed procedures have been proposed for direct analysis of Bi₂O₃, GeO₂, and crystals of bismuth orthogermanate (BGO) by atomic emission spectroscopy with a high-power two-jet arc plasma as an excitation source. The detection limits for 36 impurities have been shown to lie in the ranges of 0.008–2 (Bi₂O₃), 0.006–4 (GeO₂), and 0.008–3.5 μg/g (BGO).     

Growth process observation of homoepitaxial ZnO thin films using optical emission spectra during pulsed laser deposition

Homoepitaxial ZnO thin films were prepared on the Zn-polar or O-polar ZnO substrates by pulsed laser deposition method. Optical emission spectroscopy of the plume was carried out to estimate O/Zn flux ratio under the various deposition conditions such as oxygen pressure, laser fluence, and the distance between target and substrate. It is revealed that the O/Zn flux ratio could be controlled by laser fluence, oxygen pressure, and target-substrate distance. Zn-rich O/Zn flux promotes pit formation and O-rich flux yields the three-dimensional growth. The difference of the growth process on Zn-polar or O-polar substrates is also discussed.     

The energy spectra of clusters formed during ion sputtering of metals

We propose a method for calculating the energy spectra of neutral and charged clusters with the number of atoms N≤5 sputtered from a metal surface during ion bombardment. The calculated energy distributions of clusters emitted from tantalum and niobium bombarded with atomic gold ions are compared to the published experimental data.     

The effect of ion energy on the surface morphology of platinum film under high-frequency ion plasma sputtering

The effect of ion energy (E _i = 45–220 eV) on the sputter deposition rate and surface morphology of polycrystalline platinum films processed in high-density argon plasma of low-pressure (P = 0.08 Pa) RF induction discharge has been studied. The sputtering yield of Pt has been determined as a function of the ion energy. Analysis of the data of scanning tunneling microscopy showed a large difference between the surface profiles of samples treated at minimum and maximum ion energies in the range studied. The mechanism of Pt surface morphology modification by ion plasma sputtering is discussed.     

潘宁放电溅射沉积纳米级AlN薄膜的性质

设计并制造了新的潘宁型等离子体源实验装置，分析了等离子体的发射光谱和产生AIN的动力学机理。在室温条件下，纯氮气的工作环境中用潘宁放电离子源溅射的方法，在Si（100）衬底上制备了纳米级的光滑平整AIN薄膜。本文用扫描电镜（SEM），原子力显微镜（ATM），红外吸收光谱（FTIR）和拉曼光谱（Raman shift）等测试分析技术用来研究了薄膜的微结构特征。     

Effect of aging the hollow cathode by sputtering on the analytical precision of the hollow cathode discharge emission source.

Sputtering changes the analytical performance of the hollow cathode as an emission source. Proper conditioning (aging) of the hollow with sputtering greatly improves precision. Conditioning decreases the blank emission signal and changes the shape of the hollow. Micrographs which show the evolution of the bottom of the hollow into a stable bulb shape are presented. The blank emission signal decreases with aging of the hollow and approaches a constant value when the hollow is properly conditioned. A short-term stability (n = 5) of approximately 1.8% RSD has been observed frequently. An average long-term stability over several days (n = 45) of 4.5% for Li and 3.5% for Na in the emission signal from microsamples (less than 50 nL) deposited in the hollow cathode discharge source is reported here. Instrumentation, operation, and sample preparation procedures are described.