Exploring negative ion behaviors and their influence on properties of DC magnetron sputtered ITO films under varied power and pressure conditions

We deposited indium-tin-oxide(ITO)films on silicon and quartz substrates by magnetron sputtering technology in pure argon.Using electrostatic quadrupole plasma diagnostic technology,we investigate the effects of discharge power and discharge pressure on the ion flux and energy distribution function of incidence on the substrate surface,with special attention to the production of high-energy negative oxygen ions,and elucidate the mechanism behind its production.At the same time,the structure and properties of ITO films are systematically characterized to understand the potential effects of high energy oxygen ions on the growth of ITO films.Combining with the kinetic property analysis of sputtering damage mechanism of transparent conductive oxide(TCO)thin films,this study provides valuable physical understanding of optimization of TCO thin film deposition process.

Enhanced antibacterial activity of cotton via silver nanocapsules deposited by atmospheric pressure plasma jet

In this work,the antibacterial activity of cotton containing silver nanocapsules prepared by atmospheric pressure plasma(APP)deposition is investigated.The nanocapsules consist of a shell and a silver nanoparticle(Ag NP)core,where the core is used to bring antibacterial activity,and the shell is utilized to suppress the potential toxicity of Ag NPs.The surface morphology and the elements of the samples are analyzed by scanning electron microscopy(SEM),energy dispersive x-ray and x-ray photoelectron spectroscopy(XPS).The SEM results show that the skin of the cotton fibers will fall off gradually after APP treatment over 3 min,and the XPS results show that the Ag content will rise to 1.6%after APP deposition for 10 min.Furthermore,the antimicrobial activity tests show that the reduction rates of Escherichia coli and Staphylococcus aureus can achieve 100%when the sample is treated for 10 min,which exhibits excellent antibacterial activity.In addition,the UV absorption properties of the cotton will also be correspondingly improved,which brings a broader application prospect for antibacterial cotton.

Speeding-up direct implicit particle-in-cell simulations in bounded plasma by obtaining future electric field through explicitly propulsion of particles

The direct implicit particle-in-cell is a powerful kinetic method for researching plasma characteristics.However,it is time-consuming to obtain the future electromagnetic field in such a method since the field equations contain time-dependent matrix coefficients.In this work,we propose to explicitly push particles and obtain the future electromagnetic field based on the information about the particles in the future.The new method retains the form of implicit particle pusher,but the future field is obtained by solving the traditional explicit equation.Several numerical experiments,including the motion of charged particle in electromagnetic field,plasma sheath,and free diffusion of plasma into vacuum,are implemented to evaluate the performance of the method.The results demonstrate that the proposed method can suppress finite-grid-instability resulting from the coarse spatial resolution in electron Debye length through the strong damping of high-frequency plasma oscillation,while accurately describe low-frequency plasma phenomena,with the price of losing the numerical stability at large time-step.We believe that this work is helpful for people to research the bounded plasma by using particle-in-cell simulations.

Development of a helicon-wave excited plasma facility with high magnetic field for plasma-wall interactions studies

The high magnetic field helicon experiment system is a helicon wave plasma（HWP）source device in a high axial magnetic field（B0）developed for plasma–wall interactions studies for fusion reactors.This HWP was realized at low pressure（5×10^-3-10 Pa）and a RF（radio frequency,13.56 MHz）power（maximum power of 2 k W）using an internal right helical antenna（5 cm in diameter by 18 cm long）with a maximum B0of 6300 G.Ar HWP with electron density～10^18–10^20m^-3 and electron temperature～4–7 e V was produced at high B0 of 5100 G,with an RF power of 1500 W.Maximum Ar^＋ion flux of 7.8×10^23m^-2s^-1 with a bright blue core plasma was obtained at a high B0 of 2700 G and an RF power of 1500 W without bias.Plasma energy and mass spectrometer studies indicate that Ar^＋ ion-beams of 40.1 eV are formed,which are supersonic（～3.1cs）.The effect of Ar HWP discharge cleaning on the wall conditioning are investigated by using the mass spectrometry.And the consequent plasma parameters will result in favorable wall conditioning with a removal rate of 1.1×10^24N2/m^2 h.

Modification of exposure conditions by the magnetic field configuration in helicon antenna-excited helium plasma

Modification of exposure conditions downstream in the diffusion chamber has been performed in helicon antenna-excited helium plasma by adjusting the magnetic field(intensity and geometry).In the inductively coupled mode(H mode),a reduction in ion and heat fluxes is found with increasing magnetic field intensity,which is further explained by the more highly magnetized ions off-axis around the last magnetic field lines(LMFL).However,in helicon wave mode(W mode),the increase in magnetic field intensity can dramatically increase the ion and heat fluxes.Moreover,the effect of LMFL geometry on exposure conditions is investigated.In H mode with contracting LMFL,off-axis peaks of both plasma density and electron temperature profiles shift radially inwards,bringing about a beam with better radial uniformity and higher ion and heat fluxes.In W mode,although higher ion and heat fluxes can be achieved with suppressed plasma cross-field diffusion under converging LMFL,the poor radial uniformity and a small beam diameter will limit the size of samples suitable for plasma irradiation experiments.

The effect of nitrogen concentration on the properties of N-DLC prepared by helicon wave plasma chemical vapor deposition

Nitrogen-doped diamond-like carbon(N-DLC)films were synthesized by helicon wave plasma chemical vapor deposition(HWP-CVD).The mechanism of the plasma influence on the N-DLC structure and properties was revealed by the diagnosis of plasma.The effects of nitrogen doping on the mechanical and hydrophobicity properties of DLC films were studied.The change in the ratio of precursor gas flow reduces the concentration of film-forming groups,resulting in a decrease of growth rate with increasing nitrogen flow rate.The morphology and structure of N-DLC films were characterized by scanning probe microscopy,Raman spectroscopy,and X-ray photoemission spectroscopy.The mechanical properties and wettability of N-DLC were analyzed by an ultra-micro hardness tester and JC2000DM system.The results show that the content ratio of N^(+)and N_(2)^(+)is positively correlated with the mechanical properties and wettability of N-DLC films.The enhancement hardness and elastic modulus of N-DLC are attributed to the increase in sp3 carbon–nitrogen bond content in the film,reaching 26.5 GPa and 160 GPa respectively.Water contact measurement shows that the increase in the nitrogen-bond structure in N-DLC gives the film excellent hydrophobic properties,and the optimal water contact angle reaches 111.2°.It is shown that HWP technology has unique advantages in the modulation of functional nanomaterials.

Simulation study on electron heating characteristics in magnetic enhancement capacitively coupled plasmas with a longitudinal magnetic field

The electron heating characteristics of magnetic enhancement capacitively coupled argon plasmas in presence of both longitudinal and transverse uniform magnetic field have been explored through both theoretical and numerical calculations.It is found that the longitudinal magnetic field can affect the heating by changing the level of the pressure heating along the longitudinal direction and that of the Ohmic heating along the direction which is perpendicular to both driving electric field and the applied transverse magnetic field,and a continuously increased longitudinal magnetic field can induce pressure heating to become dominant.Moreover,the electron temperature as well as proportion of some low energy electrons will increase if a small longitudinal magnetic field is introduced,which is attributed to the increased average electron energy.We believe that the research will provide guidance for optimizing the magnetic field configuration of some discharge systems having both transverse and longitudinal magnetic field.

The application of a helicon plasma source in reactive sputter deposition of tungsten nitride thin films

A reactive helicon wave plasma(HWP)sputtering method is used for the deposition of tungsten nitride(WNx)thin films.N_(2)is introduced downstream in the diffusion chamber.The impacts of N_(2)on the Ar-HWP parameters,such as ion energy distribution functions(IEDFs),electron energy probability functions(EEPFs),electron temperature(Te)and density(ne),are investigated.With the addition of N_(2),a decrease in electron density is observed due to the dissociative recombination of electrons with N_(2)^(+).The similar IEDF curves of Ar+and N_(2)^(+) indicate that the majority ofN_(2)^(+) stems from the charge transfer in the collision between Ar+and N_(2).Moreover,due to the collisions between electrons and N_(2)ions,EEPFs show a relatively lower Tewith a depletion in the high-energy tail.With increasing negative bias from 50 to 200 V,a phase transition from hexagonal WN to fcc-WN0.5is observed,together with an increase in the deposition rate and roughness.

Synthesis of Ag-decorated vertical graphene nanosheets and their electrocatalytic efficiencies

Herein we report the successful preparation of silver(Ag)-decorated vertically oriented graphene sheets(Ag/VGs)via helicon wave plasma chemical vapor deposition(HWP-CVD)and radiofrequency plasma magnetron sputtering(RF-PMS).VGs were synthesized in a mixture of argon and methane(Ar/CH_(4))by HWP-CVD and then the Ag nanoparticles on the prepared VGs were modified using the RF-PMS system for different sputtering times and RF power levels.The morphology and structure of the Ag nanoparticles were characterized by scanning electron microscopy and the results revealed that Ag nanoparticles were evenly dispersed on the mesoporous wall of the VGs.X-ray diffraction results showed that the diameter of the Ag particles increased with the increase in Ag loading,and the average size was between 10.49 nm and 25.9 nm,consistent with the transmission electron microscopy results.Ag/VGs were investigated as effective electrocatalysts for use in an alkaline aqueous system.Due to the uniquely ordered and interconnected wall structure of VGs,the area of active sites increased with the Ag loading,giving the Ag/VGs a good performance in the oxygen evolution reaction.The double-layer capacitance(C_(dl))of the Ag/VGs under different Ag loadings were studied,and the results showed that the highest Ag content gave the best C_(dl)(1.04 mF cm^(-2)).Our results show that Ag/VGs are likely to be credible electrocatalytic materials.

jdisHow does the Research Capacity Gap among Institutions Change over Time?

Recent investigation has reported that the richest 10%of the world population now owns 76%of all wealth due to COVID-19,indicating a wide gap between the rich and the poor across the globe(World Economic Forum,2022).This disparity also prevails in science,where a few prominent institutions publish most impactful papers,while the rest majority are inconspicuous.

Rapidly Synthesis of Nanocrystalline Diamond Films by Helicon Wave Plasma

A new technique of the synthesis of Nanocrystalline Diamond(NCD)Films by helicon wave plasma(HWP)chemical vapor deposition at room temperature was reported.The growth morphology and the roughness of NCD samples was characterized using filed emission scanning electron microscopy(SEM-SU8010)and atom force microscopy(AFM),respectively.The results show the growth rate of the film was very fast,about 833nm/min.Typical G,D

High magnetic field helicon plasma discharge for plasma-wall interaction studies

Dear Editors,Plasma-Wall Interactions(PWIs)are important for the development of magnetic confinement fusion devices such as International Thermonuclear Experimental Reactor(ITER),as they can release impurities into the plasma,erode the surfaces,or produce retention of fuel in the wall。