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Deposition of transparent oxide films at atmosphere pressure onto polymeric substrates at room temperature is a technique gaining rapid acceptance. These films can be used for numerous applications such as antiscratch and water permeation barrier coatings. In this paper, a $\sim 1.4$ - $\mu \text{m}$ SiO x layer has been deposited on polypropylene-coated paper at atmosphere pressure with a filamentary dielectric barrier discharge (DBD). The DBD linear discharge was driven by a 30-kHz power supply. Scanning electron microscope, X-ray photoelectron spectroscopy, and attenuated total reflection-Fourier transform infrared spectroscopy were used to characterize the deposited film. The deposited thin film decreased water permeation through the paper by $\sim 15$ %.

Aluminum-doped zinc oxide (AZO) is a material that can have high electrical conductivity while being highly transparent at the same time. It has been used in many applications such as displays, mobile devices and solar cells. Currently AZO films are considered as attractive alternatives to materials such as indium–tin oxide (ITO) due to its much cheaper cost and comparable high electrical conductivity. A process of depositing AZO film by dual DC magnetron and RF enhancement system has been developed. Film thicknesses were measured to be at about 200 nm by a stylus contact profilometer and transparency of greater than 90% in the visible range was measured with spectrophotometry methods. Film conductivities were on the order of 10 − 3 Ω-cm using the four-point probe method. By using a dielectric barrier discharge operating at atmospheric pressure, the conductivity of film can be further lowered. A 300 mm × 60 mm line source operating at a nitrogen flow of ~ 250 L/min was used and ~ 0.4 L/min hydrogen gas was also introduced into the discharge system to create hydrogen radicals for surface modification. A 10%–15% decrease in electrical resistance was observed with no changes in the optical properties of the AZO films.

article i nfo Available online 18 June 2013 The Center for Plasma-Material Interaction (CPMI) has developed innovative coating method of evaporative coating at atmospheric pressure (ECAP). This new idea is an atmospheric-pressure-based process. Following the similar concept as the laser-assisted plasma coating at atmospheric pressure (LAPCAP) (1), the material captured by the plasma plume is atomic in nature (the evaporated metal atom) and should therefore end up deposited molecule-by-molecule as in a PVD fashion. By using the thermal energy from the microwave plasma, solid 99.99% + purity aluminum were evaporated and then produce a PVD-like alumina coating on a work piece. The aluminum target was inserted in the center of the microwave torch feeding a melt pool and evaporated into the surrounding plasma plume. A bottle neck was made in the antenna and could reduce the heat loss by 84%, thus allowing higher temperatures to exist in the sample-holder antenna tip. Gas shielding was used to keep the work gas pure. The film was deposited as Al2O3 using oxygen from the envi- ronment. Deposition rate was around 2 μm/min. Gas flow rate around the antenna tip was about 0.9 m/s, and the temperature of the plasma was about 1400 °C at 1350 W input power from simulations. Alpha and other metastable phases of aluminum oxide were found on the deposited films.

Two types of cylindrical non-thermal dielectric barrier discharge plasma sources working at atmospheric pressure have been investigated and the electrical and optical characteristics were determined. The configurations compared are ring-and-rod and double-ring. At 30 kHz frequency and 62 W fixed input power, the electrical characteristics: V–I and V–Q Lissajous curves were measured. The capacitances, energies dissipated, and powers consumed for plasma generation have been quantified. Light emission characteristics of the two configurations were also measured at the main discharge region between the electrodes as well as at the afterglow plasma region. The propagation speed of ionization front of afterglow plasma has been estimated to be 0.5–1.3 cm/μs in this experiment.

The DBD (Dielectric Barrier Discharge) is well known for its great advantages in various kinds of industrial applications and has been widely used in manufacturing process including flat panel displays, thin films and semiconductor packaging. There has been enormous progress on DBD source development and diagnostics to suit these different purposes. At the same time, there are increasing needs for moderate and efficient remote plasma sources in order to avoid electrical damage from microarcs or high energy ion collisions. To this end, a stable remote plasma using an extended DBD source having a stable effective discharge area of 550mm × 40mm was investigated. The electron temperature was measured from a Boltzmann plot based a PLTE (Partial Local Thermodynamic Equilibrium) model and electron density measured from linewidth broadening of H β line, with hydrogen insertion for comparison of the direct discharge region in between electrodes and the remote plasma region. The capacitance of DBD electrode as well as discharge energy and discharge power has been investigated with V-Q Lissajous analysis. Surface treatment of glass and polypropylene with various applied voltage and gas flow rates were studied. Combining optical and electrical diagnostics and surface analysis results on treated samples, the atmospheric plasma source for in-line processing was characterized.

The Center for Plasma-Material Interactions (CPMI) at the University of Illinois at Urbana-Champaign has developed a greater than 10 mm diameter 2.45 GHz microwave-induced atmospheric pressure plasma torch (APPT) for use in various manufacturing applications. The APPT has the ability to generate various atmospheric pressure plasmas (helium, argon, nitrogen) with a gas temperature range from room temperature (30°C) to more than 3,000 °C at the ignition area. The diagnostics of the electron temperature T e , electron density n e , and the plasma gas temperature T g are based on the optical emission spectroscopy (OES) technique. The detailed dependence of the T e , n e and T g on the microwave power, radial distance referred to the ignition point, gas type and gas flow rate will be presented individually. The validity of the OES technique, including the local thermal equilibrium conditions and the model for H β calculation, has been verified and analyzed by the OES measured results. OES results has shown that T e is in the range of 0.5–1.5 eV, n e is in the range of 1014-1016 cm−3 and T g is in the range of 900–3000 K by varying the power from 200–3000 W, depending on the type and the mixture ratio of the plasma gases. The spatial dependence of T e , n e and T g has shown a drastic decrease in T g but relatively slower changes in T e and n e . This provides possibility on both thermal and non-thermal operation conditions for applications of selectable material processes.