A Study of Diamond-Like Carbon Thin Films Prepared by Microwave Plasma Chemical Vapour Deposition

In order to deposit good films, we need to study the uniformity of plasma density and the plasma density under different gas pressures and powers. The plasma density was diagnosed by a Langmuir probe. The optical emission spectroscopy （OES） of CH4 and H2 discharge was obtained with raster spectroscopy, with characteristic peaks of H and CH achieved. Diamond-like carbon films were achieved based on the study of plasma density and OES and characterized by atomic force microscope （AFM）, X-ray diffraction instrument （XRD）, Raman spectroscope and profiler.     

Enhanced Work Function of Al-Doped Zinc-Oxide Thin Films by Oxygen Inductively Coupled Plasma Treatment

Al-doped zinc-oxide(AZO) thin films treated by oxygen and chlorine inductively coupled plasma(ICP) were compared. Kelvin probe(KP) and X-ray photoelectron spectroscopy(XPS) were employed to characterize the e?ect of treatment. The results of KP measurement show that the surface work function of AZO thin films can increase up to 5.92 eV after oxygen ICP(O-ICP)'s treatment, which means that the work function was increased by at least 1.1 eV. However, after the treatment of chlorine ICP(Cl-ICP), the work function increased to 5.44 eV, and the increment was 0.6 eV. And 10 days later, the work function increment was still 0.4 eV after O-ICP's treatment, while the work function after Cl-ICP's treatment came back to the original value only after 48 hours. The XPS results suggested that the O-ICP treatment was more e?ective than Cl-ICP for enhancing the work function of AZO films, which is well consistent with KP results.     

Enhanced Work Function of Al-Doped Zinc-Oxide Thin Films by Oxygen Inductively Coupled PlasmaTreatment简

Al-doped zinc-oxide （AZO） thin films treated by oxygen and chlorine inductively coupled plasma （ICP） were compared. Kelvin probe （KP） and X-ray photoelectron spectroscopy （XPS） were employed to characterize the effect of treatment. The results of KP measurement show that the surface work function of AZO thin films can increase up to 5.92 eV after oxygen ICP （O-ICP）＇s treatment, which means that the work function was increased by at least 1.1 eV. However, after the treatment of chlorine ICP （CI-ICP）, the work function increased to 5.44 eV, and the increment was 0.6 eV. And 10 days later, the work function increment was still 0.4 eV after O-ICP＇s treatment, while the work function after Cl-ICP＇s treatment came back to the original value only after 48 hours. The XPS results suggested that the O-ICP treatment was more effective than CI-ICP for enhancing the work function of AZO films, which is well consistent with KP results.     

Optical Characterization of Amorphous Hydrogenated Carbon(a-C:H)Thin Films Prepared by Single RF Plasma Method

Methane(CH4) plasma was used to produce amorphous hydrogenated carbon(aC:H) films by a single capacitively coupled radio frequency(RF) powered plasma system.The system consists of two parallel electrodes:the upper electrode is connected to 13.56 MHz RF power and the lower one is connected to the ground.Thin films were deposited on glass slides with different sizes and on silicon wafers.The influence of the plasma species on film characteristics was studied by changing the plasma parameters.The changes of plasma species during the deposition were investigated by optical emission spectroscopy(OES).The structural and optical properties were analyzed via Fourier transform infrared(FTIR) spectroscopy,X-ray diffraction(XRD) and UV-visible spectroscopy,and the thicknesses of the samples were measured by a profilometer.The sp~3/sp~2 ratio and the existing H atoms play a significant role in the determination of the chemical properties of thin films in the plasma.The film quality and deposition rate were both increased by raising the power and the flow rate.     

Plasma Diagnosis for Microwave ECR Plasma Enhanced Sputtering Deposition of DLC Films

Application of the Langmuir probe in plasma circumstance for deposition of diamond-like carbon （DLC） thin films usually faces the problem of rapid failure of the probe due to surface insulative coating. In this paper, we circumvent the problem by using the floating harmonic probe technique. In the real circumstance of DLC film deposition, the floating harmonic probe worked reliably over 3 hours, correctly indicating the ion density and electron temperature. The technique was practically used to measure the ion density and electron temperature in DLC film deposition processes using the microwave ECR plasma enhanced sputtering. Combined with the Raman spectroscopic characterization of the films, the conditions for deposition of DLC films were investigated.     

Polymer Surface Treatment by Atmospheric Pressure Low Temperature Surface Discharge Plasma： Its Characteristics and Comparison with Low Pressure Oxygen Plasma Treatment

The polymer treatment with a low-temperature plasma jet generated on the atmospheric pressure surface discharge （SD） plasma is performed. The change of the surface property over time, in comparison with low pressure oxygen （O2） plasma treatment, is examined. As one compares the treatment by atmospheric pressure plasma to that by the low pressure O2 plasma of PS （polystyrene） the treatment effects were almost in complete agreement. However, when the atmospheric pressure plasma was used for PP（polypropylene）, it produced remarkable hydrophilic effects.     

Helium Plasma Damage of Low-k Carbon Doped Silica Film: the Effect of Si Dangling Bonds on the Dielectric Constant

The low-k carbon doped silica film has been modified by radio frequency helium plasma at 5 Pa pressure and 80 W power with subsequent XPS, FTIR and optical emission spec- troscopy analysis. XPS data indicate that helium ions have broken Si-C bonds, leading to Si-C scission with C（1s） lost seriously. The Si（2p）, O（ls）, peak obviously shifted to higher binding en- ergies, indicating an increasingly oxidized Si（2p）. FTIR data also show that the silanol formation increased with longer exposure time up to a week. Contrarily, the CHa stretch, Si-C stretching bond and the ratio of the Si-O-Si cage and Si-O-Si network peak sharply decreased upon exposure to helium plasma. The OES result indicates that monovalent helium ions in plasma play a key role in damaging carbon doped silica film. So it can be concluded that the monovalent helium ions besides VUV photons can break the weak Si-C bonds to create Si dangling bonds and free methyl radicals, and the latter easily reacts with O_2 from the atmosphere to generate CO_2 and H_2O. The bonds change is due to the Si dangling bonds combining with H_2O, thereby, increasing the dielectric constant k value.     

Characterization of Thin Films Deposited with Precursor Ferrocene by Plasma Enhanced Chemical Vapour Deposition

In this paper, the characterization of thin films, deposited with the precursor ferrocene （FcH） by the plasma enhanced chemical vapour deposition （PECVD） technique, was investigated. The films were measured by Scanning Electronic Microscopy （SEM）, Atomic Force Microscopy （AFM）, Electron Spectroscopy for Chemical Analysis （ESCA）, and Superconducting Quantum Interference Device （SQUID）. It was observed that the film＇s layer is homogeneous in thickness and has a dense morphology without cracks. The surface roughness is about 36 nm. From the results of ESCA, it can be inferred that the film mainly contains the compound FeOOH, and carbon is combined with oxygen in different forms under different supply-powers. The hysteresis loops indicate that the film is of soft magnetism.     

Tuning Effect of N2 on Atmospheric-Pressure Cold Plasma CVD of TiO2 Photocatalytic Films

To deposit TiO2 films through plasma CVD, the partial pressure ratio of O2 to TiCl4 should be greater than the stoichiometric ratio (pO2 /pTiCl4>1). However, this may lead to the formation of powder instead of film on the substrate when using volume dielectric barrier discharge (volume-DBD) at atmospheric pressure. In this study, by adding N2 into the working gas Ar, TiO2 photocatalytic films were successfully fabricated in the presence of excess O2 (pO2 /pTiCl4=2.6) by using a wire-to-plate atmospheric-pressure volume-DBD. The tuning effect of N2 on the deposition of TiO2 film was studied in detail. The results showed that by increasing the N2 content, the deposition rate and particle size of the TiO2 film were reduced, and its photocatalytic activity was enhanced. The tuning mechanism of N2 is further discussed.     

Study of the Deburring Process for Low Carbon Steel by Plasma Electrolytic Oxidation

In an appropriate electrochemical environment, the discrete thermal electron emission could be induced in the micro area due to the uneven distribution of electron flux on the anode surface. Thus an oxygen molecule could be ionized at the liquid-solid interface after collision, and then oxygen plasma with distribution characteristics would be formed. The plasma electrolytic oxidation(PEO) could happen at the liquid-solid interface. In this work, the low carbon steel was used to study the deburring process by PEO at a high frequency(70000 Hz)pulse DC mode. Its burr height H from 3.23 mm to 0.04 mm was removed to form a smooth surface within 6 min. The values of corrosion potential and current density for the untreated sample were -0.667 V and 6.735×10~(-5)A/cm~2, respectively. But for the treated sample, the corrosion potential and current density were relatively lower,-0.354 V and 1.19×10~(-7)A/cm~2.Therefore, PEO was expected to be a new deburring method of carbon steel for the material processing field.     

Conversion of Chloride Waste into Oxide by Microwave Heated Oxygen Plasma

In this paper we show the feature of the microwave heated oxygen plasma torch which we designed and apply it to the conversion method of metal chloride wastes in a pyrochemical reprocessing into oxides. For this purpose oxygenation experiments of several typical metal chlorides were carried out by using this plasma device and thermodynamic equilibrium diagrams of each metal chloride and oxygen system were calculated. Consequently, it was found that our oxygen plasma has a possibility to realize such a oxygenation reaction, the equilibrium diagrams can predict the oxygenation characteristics of metal chlorides by oxygen plasma and the chlorides have conversion characteristics according to their oxygenation difficulties. Finally, we classified chlorides into three categories by predictions from the calculated thermodynamic equilibrium diagrams.     

High Growth Rate of Microcrystalline Silicon Films Prepared by ICP-CVD with Internal Low Inductance Antennas

The plasma parameters in ICP-CVD system with internal low inductance antennas(LIA) were diagnosed by Langmuir probe.The ions density(Ni) reached 10~(11)-10~(12) cm~(-3),and the electron temperature(T_e) was below ca.2 eV,which was slightly decreased with applied power.A p-type hydrogenated microcrystalline silicon(μc-Si:H) film was prepared on glass substrate.After optimization of the processing parameters in flow ratio of SiH_4:B_2H_6:H_2,a high quality μc-Si:H film with deposition rate above 1.0 nm/s was achieved in this work.     

The Effect of Air Plasma on Sterilization of Escherichia coli in Dielectric Barrier Discharge

In this work, a Dielectric Barrier Discharge （DBD） air plasma was used to sterilize Escherichia eoli （E. coli） on the surface of medical Polyethylene Terephthalate （PET） film. The leakage of cellular DNA and protein by optical absorbance measurement at 260 nm and 280 nm, together with transmission electron microscopy （TEM） about cell morphology were performed after sterilization to analyse inactivation mechanisms. The results indicated that the DBD air plasma was very effective in E. coli sterilization. The plasma germicidal efficiency depended on the plasma treatment time, the air-gap distance, and the applied voltage. Within 5 min of plasma treatment, the germicidal efficiency against E. coli could reach 99.99%. An etching action on cell membranes by electrons, ions and radicals is the primary mechanism for DBD air plasma sterilization, which leads to the effusion of cellular contents （DNA and protein） and bacterial death.     

Surface Modification of Polyethylene （PE） Films Using Dielectric Barrier Discharge Plasma at Atmospheric Pressure

Modification of the surface properties of polyethylene （PE） films is studied using air dielectric barrier discharge at atmospheric pressure. The treated samples are examined by Water contact angle measurements, Fourier transform infrared attenuated total reflection spectroscopy （FTIR-ATR）, X-ray photoelectron spectroscopy （XPS） and scanning electron microscopy （SEM）. With the increase in treating time, the water contact angle changes from 93.2° before treatment to a minimum of 53.3° after a treatment for 50 s. Both ATR and XPS results show some oxidized species are introduced into the sample surface by the plasma treatment and the tendency of the water contact angle with the treating time is the same as that of oxygen concentration on the treated sample surface. SEM result shows the surface roughness of PE samples increases with the treatment time increasing.     

Growth of Fluorocarbon Films by Low-Pressure Dielectric Barrier Discharge

Plasma polymerized fluorocarbon （FC） films have been deposited on silicon substrates from dielectric barrier discharge （DBD） plasma of C4Fs at room temperature under a pressure of 25～125 Pa. The effects of the discharge pressure and frequency of power supply on the films have been systematically investigated. FC films with a less cross linked structure may be formed at a relatively high pressure. Increase in the frequency of power supply leads to a significant increase in the deposition rate. Static contact angle measurements show that deposited FC films have a stable, hydrophobic surface property. All deposited films show smooth surfaces with an atomic surface roughness. The relationship between plasma parameters and the properties of the deposited FC films are discussed.     

Study of Humidity Effect on Benzene Decomposition by the Dielectric Barrier Discharge Nonthermal Plasma Reactor

The humidity effects on the benzene decomposition process were investigated by the dielectric barrier discharge(DBD) plasma reactor.The results showed that the water vapor played an important role in the benzene oxidation process.It was found that there was an optimum humidity value for the benzene removal efficiency,and at around 60% relative humidity(RH),the optimum benzene removal efficiency was achieved.At a SIE of 378 J/L,the removal efficiency was 66% at 0% RH,while the removal efficiency reached 75.3% at 60% RH and dropped to 69% at 80% RH.Furthermore,the addition of water inhibited the formation of ozone and NO_2 remarkably.Both of the concentrations of ozone and NO_2 decreased with increasing of the RH at the same specific input energy.At a SIE of 256 J/L,the concentrations of ozone and NO_2 were 5.4 mg/L and 1791 ppm under dry conditions,whereas they were only 3.4 mg/L and 1119 ppm at 63.5%RH,respectively.Finally,the outlet gas after benzene degradation was qualitatively analyzed by FT-IR and GC-MS to determine possible intermediate byproducts.The results suggested that the byproducts in decomposition of benzene primarily consisted of phenol and substitutions of phenol.Based on these byproducts a benzene degradation mechanism was proposed.     

储氢薄膜的吸氢动力学研究

研究了储氢薄膜材料在两相区范围内的吸氢动力学,它包括４个力学过程：氢在气／固表面的化学吸附,氢原子的表面渗透,氢原子在氢化物层的扩散和金属／氢化物界面上的氢化物生成。     

Effect of Oxygen Partial Pressure on Oxidation of Iron at 573 K

The oxidation of iron was investigated by Rutherford backscattering spectroscopy at 573 K under the oxygen partial pressure from 10^?1 to 10⁵ Pa for 3~24 h. In the first stage of oxidation, thickness of the oxide film reached the maximum around 1 Pa. In the second stage the oxidation obeyed the parabolic rate law. From 10^?1 to 10^?0.5 Pa the parabolic rate constant increased with increasing oxygen partial pressure due to the growth of magnetite, whereas from 1 to 10^0.5 Pa hematite covered magnetite but the parabolic rate constants were kept still high values possibly due to the presence of grain boundaries. Between 10 and 10^4.3 Pa the protective hematite coverage over magnetite kept the parabolic rate constants low regardless of oxygen partial pressure. At 10⁵ Pa a sharp increase of the parabolic rate constant was observed due to the simultaneous growth of hematite and magnetite. The oxygen concentration in water for the inhibition of the corrosion may correspond to the oxygen partial pressure for the formation of protective film in gas phase around 573 K.     

Effects of Low Energy and High Flux Helium／Hydrogen Plasma Irradiation on Tungsten as Plasma Facing Material

The High-Z material tungsten (W) has been considered as a plasma facing material in the divertor region of ITER (International Thermonuclear Experimental Reactor). In ITER, the divertor is expected to operate under high particle fluxes (> 1023 m-2s-1) from the plasma as well as from intrinsic impurities with a very low energy (< 200 eV). During the past dacade, the effects of plasma irradiation on tungsten have been studied extensively as functions of the ion energy, fluence and surface temperature in the burning plasma conditions. In this paper, recent results concerning blister and bubble formations on the tungsten surface under low energy (< 100 eV) and high flux (> 1021 m-2s-1) He/H plasma irradiation are reviewed to gain a better understanding of the performance of tungsten as a plasma facing material under the burning plasma conditions.     

Surface Modification of Biodegradable Poly(D,L-lactic acid)by Nitrogen and Nitrogen/Hydrogen Plasma for Improving Surface Hydrophilicity

Enhancement of the surface hydrophilicity of biodegradable poly (D,L-lactic acid) (PLA) films is studied. The PLA films were treated by nitrogen plasma (PLA-N2) and nitrogen/hydrogen plasma (PLA-N2/H2), respectively. The surface properties and microstructure of PLA-N2 and PLA-N2/H2 were studied by static contact angle measurement, surface free energy calculation, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). It is confirmed that the surface hydrophilicity of PLA-N2 and PLA-N2/H2 was higher than that of pristine PLA, and the surface hydrophilicity of PLA-N2 films was better than that of PLA-N2/H2.