Role Of Plasma Parameters Research Articles

Role of plasma parameters on the characteristics properties of flexible transparent ITO films deposited by 3D facing and planar facing magnetron sources

A rectangular closed and hollow three-dimensionally confined large area magnetron source (3-DCLAMS) and a conventional moderate area facing target magnetron source (FTMS) have been used to study the plasma characteristics using different diagnostics at different working pressures. Flexible indium tin oxide (ITO) films deposited at similar operating conditions using these sources were characterized by numerous standard analyses to study their film properties. The 3-DCLAMS with high discharge current at a low-discharge voltage is capable of generating high plasma density, which assists a high ion flux and energy density on the substrate that is necessary for the high growth rate deposition of highly conductive crystalline ITO films with smooth surface morphology. Utilizing suitable plasma characteristics, highly conductive and transparent ITO films of 30 nm with the minimum resistivity ρ ∼ 4.1 × 10−4 Ω cm and ∼9.3 × 10−4 Ω cm and average transmittance T ∼ 84% and 82%, respectively, were deposited in the 3-DCLAMS and the FTMS system. The presented result shows that the 3-DCLAMS system could be useful for making high-quality, flexible ITO films at a very high deposition rate of ∼250 nm/min.

Propagation of high frequency electrostatic surface waves along the planar interface between plasma and dusty plasma

An analytical model is developed that explains the propagation of a high frequency electrostatic surface wave along the interface of a plasma system where semi-infinite electron-ion plasma is interfaced with semi-infinite dusty plasma. The model emphasizes that the source of such high frequency waves is inherent in the presence of ion acoustic and dust ion acoustic/dust acoustic volume waves in electron-ion plasma and dusty plasma region. Wave dispersion relation is obtained for two distinct cases and the role of plasma parameters on wave dispersion is analyzed in short and long wavelength limits. The normalized surface wave frequency is seen to grow linearly for lower wave number but becomes constant for higher wave numbers in both the cases. It is observed that the normalized frequency depends on ion plasma frequencies when dust oscillation frequency is neglected.

Low temperature plasma processing for cell growth inspired carbon thin films fabrication

The recent bio-applications (i.e. bio-sensing, tissue engineering and cell proliferation etc.) are driving the fundamental research in carbon based materials with functional perspectives. High stability in carbon based coatings usually demands the high density deposition. However, the standard techniques, used for the large area and high throughput deposition of crystalline carbon films, often require very high temperature processing (typically >800 °C in inert atmosphere). Here, we present a low temperature (<150 °C) pulsed-DC plasma sputtering process, which enables sufficient ion flux to deposit dense unhydrogenated carbon thin films without any need of substrate-bias or post-deposition thermal treatments. It is found that the control over plasma power density and pulsed frequency governs the density and kinetic energy of carbon ions participating during the film growth. Subsequently, it controls the contents of sp3 and sp2 hybridizations via conversion of sp2 to sp3 hybridization by ion's energy relaxation. The role of plasma parameters on the chemical and surface properties are presented and correlated to the bio-activity. Bioactivity tests, carried out in mouse fibroblast L-929 and Sarcoma osteogenic (Saos-2) bone cell lines, demonstrate promising cell-proliferation in these films.

Role of Plasma Parameters on the Growth and Field Emission Properties of 2D Graphene Sheet

The role of plasma parameters (electron density and temperature, ion density and temperature) on the growth and field emission properties of two dimensional graphene sheet has been theoretically investigated. A theoretical model of charge neutrality, including the kinetics of electrons, negatively and positively charged ions, neutral atoms and the energy balance of various species has been developed. Numerical calculations of the graphene for different plasma parameters (electron density and temperature, ion density and temperature) have been carried out for the typical glow discharge plasma parameters. It is found that the thickness of graphene sheet decreases with plasma parameters and hence the field emission of electrons from the graphene sheet increases. Some of our theoretical results are in compliance with the existing experimental observations.

Stability of Plasma Treated Non-vulcanized Polybutadiene Surfaces: Role of Plasma Parameters and Influence of Additives

Surface modification studies of non-vulcanized BR elastomers (butadiene rubber) by low-pressure air plasma treatment and the effect on ageing and adhesion performances are presented in this paper. In particular, the influence of discharge power and distance from the glow discharge, and impact of antioxidant molecules in the BR formulation were examined. To characterize the changes to the BR surface, XPS spectroscopy, contact angle measurements, AFM nanoindentation experiments and tack measurements were utilized. Oxidation and crosslinking were the main mechanisms observed on the polymer chains regardless of the plasma conditions used. Beyond a certain threshold of plasma energy (in our case, discharge power of ~60 W and exposure time of ~30 s), a steady state was reached irrespective of the distance from the glow discharge. The presence of antioxidant molecules considerably reduced crosslinking phenomena while maintaining oxidation processes on polymer chains and increasing the nitrogen content in the near surface region. The mechanisms responsible for these differences have been identified. Interestingly, the COOH/C=O ratio changed according to the balance between oxidation and crosslinking. The hydrophobic recovery rate was mainly driven by temperature-dependent dynamics and varied according to the degree of crosslinking in the surface region. It was found to be lower in air atmosphere in the presence of antioxidant molecules. Finally, the presence of antioxidant molecules in the BR formulation allowed the adhesion performances after plasma exposure to significantly increase.

Role of Plasma Parameters on the Conjugated Structure Retention in Polyaniline Thin Film

The role of plasma parameters on the film characteristics is investigated on polyaniline thin film deposited by radio frequency (RF) plasma polymerization. A series of un-doped and iodine doped polyaniline thin films are prepared by RF discharge operating at 13.56 MHz with different discharge powers and pressure variation from 0.1 to 0.05 mbar and variation in deposition time from 20 to 40 min. A good thin film is found with a power ranging from 9 W (−28 V self bias) to 20 W (−65 V self bias) at 0.1 mbar pressure which is confirmed by fourier transform infra-red spectroscopy showing the retention of aromatic rings. In addition, iodine doping is carried out with 9 W power and 0.1 mbar pressure. The characterization of process plasma is done using Langmuir probe diagnostics and optical emission spectroscopy. A correlation has been established between film characteristics and plasma properties investigated using optical emission spectroscopy and Langmuir probe analysis. Emphasis has been given on the study of the influence of plasma parameters, particularly of the electron energy distribution function on the quality of conjugated plasma polymerized aniline film.

Effects of hydrogen plasma on passivation and generation of defects in multicrystalline silicon

Hydrogenation by plasma is a low cost and efficient method to improve the photovoltaic properties of multicrystalline silicon. The role of plasma parameters on the efficiency of hydrogenation was studied using secondary ion mass spectrometry (SIMS), hydrogen effusion, electrochemical impedance spectroscopy and electron beam induced current (EBIC). The experimental results showed a deuterium concentration of 10 20 atoms cm −3 could be reached in the sample after a 15-min treatment. Optimal treatment time depends on temperature and leads to maximum electrical conductivity and minority carrier diffusion length. The results confirm the reduction of defects densities and potential barriers associated with grain boundaries.

Development of Cathode Materials by Plasma Process at Room Temperature

Deposits of La 1-x Sr x MnO 3±δ used as cathode materials in solid oxide fuel cells are obtained by oxidation of nitrate precursors in a cold temperature plasma reactor equipped with a convergent nozzle. Infrared analysis of deposits permitted us to measure the role of plasma parameters on the conversion rate of nitrate precursors. Oxygen and hydroxyl radicals produced by plasma are found to be the major reactive species that lead to the transformation of nitrate precursors into perovskites in this process. Impedance measurements showed the role of plasma parameters on the electrical conductivity of deposits.

Effect of the neutral beam fuelling profile on fusion power, confinement and stability in TFTR

The stored energy and neutron yields of TFTR plasmas have been modelled, with small dispersion, by considering a parameter associated with the peakedness of the beam fuelling profile as an independent variable. Scalings with fixed multiplicative constants and exponential powers determined from the experimental data are applied to deuterium discharges at different major radii in TFTR, and also to deuterium-tritium (DT) plasmas. The domain of the data considered includes the supershot, high poloidal beta, L mode and limiter H mode operational regimes, as well as discharges with a reversed shear (RS) magnetic configuration. The role of plasma parameters, such as plasma current Ip, edge safety factor qa and toroidal field Bt, are considered in this study. Improved energy confinement and neutron production are relatively insensitive to these parameters compared with the beam fuelling peakedness parameter when considering plasmas that are stable to magnetohydrodynamic modes. In contrast, plasma stability is dependent on these quantities and also on parameters describing the peakedness of the equilibrium profiles. On the basis of externally controllable plasma parameters, the limitation and optimization of fusion power production of the present TFTR is investigated and a path towards a discharge condition with fusion power gain Q>1 is suggested

Plasma-assisted deposition techniques for hard coatings

This paper reviews the most commonly used deposition techniques for hard coatings, namely Plasma-Assisted Chemical Vapor Deposition (PACVD), Reactive Sputtering (RS) and Activated Reactive Sputtering (ARE). The role of plasma parameters and process parameters as well as their interdependency is discussed in terms of the three steps in deposition of films, i.e. generation of the depositing species, transport from source to substrate and film growth on the substrate.