Diagnostics of a Radio-Frequency Plasma Expanding Through a Nozzle (PETN) at Low Pressure

The diagnostics of the radio-frequency (induction mode) plasma expanded through a nozzle (PETN) at low pressures (100–1000 Pa) was performed by on-line optical emission spectroscopy (OES) and on line quadrupole mass spectrometry (QMS). The OES was used for evaluating the electronic, vibrational, and rotational temperatures (T_e, T_v, and T_r) along the plasma reactor before and after the nozzle. The PETN gas mixtures analyzed were Ar+N₂, Ar+CO, and Ar+O₂with an addition of 1 vol.% N₂to the last two gas mixtures. For the same conditions in the PETN the values of T_e, T_v, and T_r were found to be different for the different gas mixtures and related to the depopulation of excited N ₂ ⁺ by oxygen atoms. Moreover the Ar+O₂PETN aqueous solutions of lanthanum and manganese nitrates were nebulized for the deposition of LaMnO₃perovskite. The QMS, in real time, measuring the mass species formed before and after the nozzle, explained the reasons in the different values of T_e, T_v, and T_r for the three gas mixtures as well as for the formation of oxides in the PETN from the aqueous nitrate solutions.     

Monitoring the deposition process of metal-doped polymer films using optical emission spectroscopy

Simultaneous plasma polymerization of halocarbons (CF₄ and C₂F₃Cl) and sputtering of metals (Au and Al) or cosputtering [Au + polytetrafluoroethylene (PTFE, Teflon)] have been performed by means of an RF (20 MHz) glow discharge excited by a planar magnetron. The optical emission spectroscopy (OES) has been used for monitoring the deposition process of metal-doped polymer films. The light emission intensity ratios of the relevant species in the plasma volume are given in connection with the characteristics of the films prepared.     

A study of the deposition of polymeric material onto surfaces from fluorocarbon RF plasmas

A series of fluorocarbon gases, viz., CF₄, C₂F₆, C₃F₈, and CHF₃, have been compared for their relative tendencies to deposit polymeric material onto various surfaces, including Si and SiO₂, under RF plasma conditions. The plasmas were examined by optical emission spectroscopy. C₃F₈ and CHF₃ were found to produce the highest yields of polymers, although these exhibited significant differences in structure (as shown by XPS and IR) and differences in thermal stability, both of which could be minimized by replacing the C₃F₈ gas with a C₃F₈/H₂ mixture. The polymers produced from CHF₃ under the conditions of the present study were found to accumulate preferentially onto Si rather than SiO₂, as verified by the technique of Rutherford backscattering spectrometry.     

Cu-N Films grown by reactive MSIP: Constitution, structure and morphology

Cu-N layers were deposited on Si-100 wafers and amorphous carbon coated platinum nets at low temperatures (< 100 °C) by means of Reactive Magnetron Sputtering Ion Plating (MSIP). For this, a Cu-target was sputtered in rf-mode in a nitrogen plasma, and the influence of the parameters sputtering power and nitrogen partial pressure on composition, structure, texture and morphology of the Cu-N layers was investigated. The analysis with EPMA, XPS, HEED, XRD, TEM and SEM yielded the following results: With appropriate settings of the process parameters the nitrogen content of the films could be controlled-in this investigation between 0 to 28 at-%. The HEED analysis shows, that at the near surface region films with a nitrogen content in the range of 16–28 at-% were grown with DO₉ structure of Cu₃N. The films were textured: [100] in the case of 16–26.3 at-% nitrogen, [210] + [110] at 28 at-%. XRD analysis of the crystal structure of the bulk of a nitrogen-rich film (26.3 at-% nitrogen) confirm the result of HEED analysis. In the bulk of the nitrogen-poor film (16.4 at-%) two phases were detected, metallic copper with Al structure and Cu₃N with DO₉ structure. XPS analysis revealed that all films were oxidized at the surface to Cu₂O.Dedicated to Professor Dr. rer. nat. Dr. h. c. Hubertus Nickel on the occasion of his 65th birthday     

Deposition of Diamond-Like Carbon Film in a Closed-Space CH4 RF Plasma

Deposition of diamond-like carbon (DLC) film and mass spectrometry measurements were carried out in a closed-space CH₄ rf (13.56 MHz) plasma (without both gas injection and vacuum pumping during the process). At pressures less than 0.6 Torr, the thickness of the DLC film deposited increased with increasing elapsed deposition time, and reached a maximum value, but after this the film thickness started to decrease, which was considered to be caused predominantly by ion-induced sputter etching. The maximum film thickness appeared at larger elapsed time for higher deposition pressure. The mass concentrations of hydrocarbon ions indicated anomalous behavior at early deposition times, but those of higher hydrocarbon ions are clearly increased at the point where the film thickness started to decrease. These results suggested that the ratio of precursor CH₃al density to the total hydrocarbon ion density (_CH3/_ion in the CH₄a was an important factor for the carbon film formation, and when this ratio reduced to a certain critical value with increasing elapsed deposition time, the deposited film was then re-etched predominately by the secondary higher hydrocarbon ions. At 1.0 Torr where a polymer-like soft carbon film was deposited, such re-etching of the deposited film was not observed.     

玻璃和石英基体上沉积的TiO2薄膜的光催化性能

采用直流磁控反应溅射法,在玻璃和石英基体上制备了TiO2薄膜.在氧气流速超过阈值的条件下溅射,能够得到均匀透明的TiO2薄膜.在玻璃和石英基体上制备的薄膜都由均匀的锐钛矿型氧化钛晶粒组成,在晶粒中间分布着微小的孔隙.尽管在整个光谱区域内石英基体的透射率都比玻璃基体高,但在两种基体上制备的TiO2薄膜的光谱吸收边沿基本相同.薄膜中的Ti都以Ti4 形式存在.两种TiO2薄膜光催化降解甲基橙的能力相差不大.     

Diagnostics and decomposition mechanism in radio-frequency discharges of fluorocarbons utilized for plasma etching or polymerization

Optical emission (180–800 nm) and mass spectroscopy have been used to study the CF₄, CF₄+O₂, C₂F₆, C₂F₆+H₂, CF₃Cl, and C₂F₄ decomposition in radio-frequency discharges. The analysis of the stable and unstable discharge products has allowed the suggestion of decomposition channels for the various gases and to classify the fluorinated gases according to their predominant etching or polymerizing characteristics on the basis of the active species present in the plasma. A new broad emission continuum centered at =290 nm (FWHM=66 nm) has also been identified and it has been tentatively assigned to CF⁺ ₂.     

Numerical Modeling of an Ar–H<Subscript>2</Subscript> Radio-Frequency Plasma Reactor under Thermal and Chemical Nonequilibrium Conditions

The species densities and the thermal and chemical nonequilibrium phenomena in an Ar–H₂ radio frequency inductively coupled plasma reactor used for hydrogenation of materials have been investigated through numerical simulation. The mathematical model consists of a two-temperature fluid dynamics model and a chemical kinetics model that takes into account the effect of local chemical nonequilibrium. Computations are carried out for the rf plasma running at 11.7 kW and 27 kPa for different Ar–H₂ mixtures and for pure argon. Predicted results for the electron and heavy-species temperatures, the species densities, as well as the degree of thermal and chemical nonequilibrium, are presented in detail. It is found that the electron and hydrogen atom densities in the reactor and in the near-wall region of the torch are strongly altered by nonequilibrium effects. The hydrogen atom density remains high in the reactor zone, and peaks in a region that has been found to be attractive for material processing. Deviations from thermal and chemical equilibrium are greatly reduced by the addition of hydrogen to an argon plasma.     

Oxidation and reduction of nanodiamond particles in colloidal solutions by laser irradiation or radio-frequency plasma treatment

Functionalized nanodiamond particles (NDs) represent carbon nanomaterial with unique properties for various applications. Here we report on a new approach to surface modification of NDs by their exposure to radio frequency (RF) plasma or laser irradiation (LI) plasma directly in aqueous solution. By using grazing angle reflectance Fourier transform infrared spectroscopy and supporting analysis by X-ray photoelectron spectroscopy, zeta-potential, and Kelvin force microscopy we show that surface chemistry of NDs produced by detonation process (DNDs) or high-pressure high-temperature process (HPHT NDs) works in different way. Moieties on as-received NDs are dominated by COOH and COC groups due to wet chemical cleaning procedures. On DNDs, both RF and LA treatment lead to removal of sp² shell and additional oxidation of the surface to C OC groups. On HPHT NDs the RF treatment leads to reduction of COC groups that are transformed into COH and CH moieties. Thus at least partial hydrogenation of colloidal HPHT NDs seems feasible.     

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为探究射频离子源驱动器线圈电气参数对射频放电的影响,主要进行了射频离子源等离子体激发的物理分析,并计算了射频电源的频率选择与线圈放电电流、线圈匝间电压以及放电气压之间的关系,设计了射频离子源驱动器的主要参数。研制的射频离子源驱动器装置,成功获得氢等离子体射频放电。实验结果和理论计算结果符合很好。