Hybrid (organic/inorganic) heterojunction device based on nano-crystallite structures of 2-(2, 3-dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-pyrazol-4-ylimino)-2-(4-nitrophenyl)acetonitrile (DOPNA) and ZnO thin films has been fabricated. The ZnO powder is prepared by the hydrolysis of zinc chloride in the presence of triethanolamine, the ZnO film is prepared by using spin coating technique, whereas the DOPNA thin film is deposited from the powder by the thermal evaporation technique. The formed nano-crystallite structures and lattice parameters of DOPNA and ZnO films have been determined. The optical absorbance of DOPNA and ZnO films are measured and the types of transitions as well as the optical band gap of the films are evaluated. The current-voltage characteristics of ITO/ZnO/DOPNA/Au heterojunction diode in dark and under illumination conditions have been investigated. The capacitance-voltage characteristic showed that the formed junction is of abrupt nature and the built-in potential is estimated. The solar cell parameters have been determined as 0.37 V for open circuit voltage, 1.04 mA for short circuit current, 0.43 for fill factor and 1.56% for power conversion efficiency.

The characterization of the BPDA/PDA polyimide (PI) at high temperature up to 400 °C, thanks to dielectric relaxation spectroscopy (DRS) in the 10-1 Hz to 106 Hz frequency range, allows the determination of the dc electrical conductivity (σdc). In such a high temperature range, the dielectric spectra are modified by the extrinsic electrode polarization phenomenon (EP) response. A model is proposed which coupled to the DRS results allows evidencing and quantifying the effect of the EP. The proposed method gives a simple way to determine the intrinsic σdc values from the effective ac dielectric response, improving the accuracy and reducing the duration of measurement. For BPDA/PDA PI, the resulting σdc values range from 4 × 10-11 to 8 × 10-6 Ω-1 m-1 for temperatures between 200 and 400 °C, with an activation energy of the conduction phenomenon of 0.55 eV.

Electrical conductivity measurements of pyronine G(Y) were performed as a function of both temperature (303–443 K) and frequency (50 Hz–550 kHz). The frequency dependence of ac conductivity is well represented by the form ωs. The values of exponent, (s) decrease from 0.98 at 303 K to 0.67 at 403 K. The temperature dependence of both ac electrical conductivity and the exponent (s) reveals that the ac conduction is due to the correlated barrier hopping (CBH). The dielectric constant, ε1(ω), and dialectic loss, ε2(ω), have been determined for bulk pyronine G(Y). Both ε1(ω) and ε2 (ω) decrease by increasing frequency and increase by increasing temperature.

We describe a new technique for the fabrication of point contacts using a focused ion beam (FIB) patterning. After sample coverage with a thin insulating layer (SiO), an FIB is used to mill a 100-nm-diameter hole through the insulator. Electrical contact to the sample is then made in-situ by filling the hole with a metal (Pt) using the ion beam assisted chemical vapor deposition capability of our FIB system. We have demonstrated the use of two such contacts (as an emitter and collector) in a transverse electron focusing (TEF) experiment. The contacts were made to a single crystal of bismuth, ballistic electrons were injected into the crystal through the emitter contact and then focused onto the collector by a magnetic field. We see the expected voltage peaks at the collector as a function of the applied magnetic field. Temperature dependent TEF measurements provided direct information about relaxation time of conduction electrons.

This paper analyses corona discharge in ambient air flow associated with laboratory-scaled wire-to-plate electrostatic precipitator (WPESP). The corona discharge is analysed by a combined iterative computational technique based on the finite element method (FEM) and charge simulation method (CSM). The phenomenon is mathematically described by Maxwell's equations in differential form. A finite element method is used to solve the Poisson's equation and the charge simulation method is used to satisfy the current continuity condition. Measurement method of the positive dc corona current density and electric field, taking into account the air flow velocity, has been introduced. The computed results are compared with experimental results to test the effectiveness of this approach.

The effect of a uniformly distributed, immobile, charged particle background on the stationary states of a plasma diode with beam electrons is studied. Whereas a positively charged particle background results in an increase of the space-charge limit of the electron current across the diode and brings in new branches of equilibria, a negatively charged background decreases the current up to zero current level due to a complete reflection of beam electrons within the diode region. This effect can be used for the design of fast switches.

In this paper, we extend corresponding theory which can only deal with thin medium based on thin sheet approximation to a new area which can deal with thick medium with gain and loss. An analytical expression for the location and the peak intensity of the hot-image in the case of thick nonlinear medium with gain and loss are deduced by using propagation matrix method. In order to confirm our analysis as a reliable tool to forecast the hot-image damage risk, we provide some numerical results to verify its validity. The predictions of the theory are found to be in good agreement with the numerical simulations. The theoretical analysis can be used for forecasting the intensity and location of the hot-image. It can provide rules for estimating the damage risk of the hot-image and warn us of the critical areas that may be vulnerable to the hot-image.

This paper presents the modeling of an argon micro-plasma produced by microwaves (2.45 GHz) at atmospheric pressure. The study uses a one-dimensional stationary fluid-type code that solves the transport equations for electrons, positive ions Ar+ and Ar+ 2, and the electron mean energy, together with Poisson's equation for the space-charge electrostatic field, Maxwell's equations for the electromagnetic excitation field and the gas thermal energy equation. The model uses a simple kinetic scheme for Ar that includes the ground state, an excited state representing the lumped 4s levels, and two ionization states associated to the atomic and the molecular ions. The ions are assumed to be in thermal equilibrium with the neutral gas, having the same temperature profile.

Stable mono-filamentary dielectric barrier discharges (MF-DBDs) are achieved between two insulated electrodes in pure krypton, between 100 and 600Torr. Electrical characterization, spectroscopic and kinetic analyses of the MF-DBD are performed. The fast supply current pulse provides reliable triggering for spectroscopic measurements thus allowing an in situ kinetic study. Only the second continuum of krypton is observed and it is attributed to krypton excimers Kr2[ 1u(3P2)] lowv which are correlated to the Kr(3P2) metastable atomic state. Its intensity increases with pressure, due to an enhancement of 3-body collisions with ground state atoms. The kinetic analysis of the luminescence decay of this emission in the post excitation phase, leads to only two exponential components. The pressure dependence of each decay frequency allowed determination of the radiative lifetime of Kr2[ 1u(3P2)] low v excimers and the 3-body collisional rate constant of formation of Kr2[ 1u(3P2)] high v ones are determined.

Flowing microwave N2 afterglows at reduced pressure are studied as a source of N-atoms. It is presently reported results obtained by pulsing the nitrogen gas flow with an electromagnetic (EM) valve before the plasma, starting with discharge conditions of continuous flow around 1 Torr. By keeping the microwave power tuned on as in continuous flow, it is obtained two successive plasmas: the first one at a pressure of 2–3 Torr when the flow gas is on and the second one at lower pressure (0.4-0.5 Torr) when the flow gas is off. The gas pressures were measured in a 5 L post-discharge chamber. The two plasmas are here analysed by emission spectroscopy and the transmitted powers are deduced from the N2 +/N2 intensity ratio for both cases. It is obtained about the same power as for continuous flow when the flow gas is on with a negligible reflected power. The transmitted power is lower and thus the reflected power is important when the flow gas is off. The emission of the N2 1st positive system at 580 nm, signature of the N-atom recombination in the afterglow, is observed in the reactor after the gas pressure rise, with a maximum intensity obtained for a duty cycle of 0.5 at a period of 2 s, corresponding to a maximum N-atom density of about 1015 cm-3 and a pressure variation Δp in the range 2.3-0.5 Torr.

The formation of negative ions produced in a negative point-to-plane corona discharge fed by a Ar/N2/CH4 gas mixture has been studied using mass spectrometry. The measurements were carried out in flowing regime at ambient temperature and a reduced pressure of 460 mbar. The CN- anion has been found to be the most dominant negative ion in the discharge and is believed to be the precursor of heavier negative ions such as C3N- and C5N-. The most likely pathway for the formation of such molecular anions is H-loss dissociative electron attachment to HCN, H3CN and H5CN formed in the discharge. These same anions have been detected in Titan's atmosphere and the present experiments may provide some novel insights into the chemical and physical mechanisms prevalent in Titan's atmosphere and hence assist in the interpretation of results from the Cassini Huygens space mission.

Plasmas are energetic media that can give birth to dust particles due to the presence of reactive gases or plasma-surface interactions. Industrial plasmas are often concerned by these dust particles that can be either unwanted or useful for the process. For fusion plasmas, production of dust particles from wall erosion is a serious issue for performance and safety reasons. In this article, some aspects of dusty plasmas with potential implications for plasma experimenters will be discussed. Convenient ways for detecting the presence or the growth of dust particles will be presented. The spatial distribution of the dust cloud during the plasma phase determines the subsequent dust particle deposition. It will be shown that some reactor regions can attract or repeal these dust particles. Finally, the dust particle dynamics after the plasma extinction will be investigated. A special attention will be paid on the residual electric charge that can stay attached on the dust particle surface and on its implications for dust particle control or deposition.

Cylindrical hollow cathode magnetron sputtering (HCMS) system was used to deposit crystalline titanium dioxide thin films on p-Si (100) substrates. For a fixed pressure of 0.6 Pa total gas flow rate of 20 sccm and power of 55 W, the influence of the oxygen percentage in the Ar+O2 gas mixture on the structural and surface properties of the films was studied by profilometry, XRD and AFM. The substrates were placed inside the hollow cathode at different positions along its symmetrical axis. Numerical simulations of cathode ion collection probability (CICP) were done in order to compare calculated data with the deposition process characteristics. The results indicate that the deposition rate and the surface roughness gradually decrease with the distance from the bottom of the cathode, due to the decrease of the CICP. The increase of the oxygen percentage in the gas discharge influences directly the deposition rate and decrease the surface roughness. The XRD analyses show that all the films are crystalline with predominant anatase (101) and rutile (110) orientations.

Bactericidal activities of three different afterglows operating at reduced and atmospheric pressures and ambient temperature are established and compared through the use of a unique protocol for bacteria (E. coli, CIP 54.8 T) exposition, recovery and numeration. The influence of three important parameters is shown. An original scenario for bacterial inactivation at reduced pressure is proposed, compatible with previously published results and with the observation of conformational changes appearing on the treated bacteria.

Microplasmas are nowadays a powerful tool with multiple practical applications. The performance of a specific instrumentation for a plasma needle capable of producing non-thermal plasmas and a DBD reactor able to produce atmospheric pressure plasmas, both of them designed and already constructed, is reported. These devices operate at 13.56 MHz and are driven by a specifically built radio frequency (RF) resonant converter. The reactors, which operate at atmospheric pressure in a He-air gas mixture at a 1.5 SLPM flow, have been successfully applied to eliminate E. coli bacteria. In the needle case, bacterial samples were submitted typically to a 500 V peak voltage plasma discharge for 120 s. In the DBD treatment, the samples were processed with typical 750 V peak voltage plasma discharges for 80 s. The sample pH was used as a criterion to measure the effectiveness of the plasma treatment, in such a way that the return to the basal pH value after the treatment can be assumed as the validation of the complete bacterial elimination.

The combination of quantum cascade lasers and infra red absorption spectroscopy (QCLAS) opens up new possibilities for plasma process monitoring and control. First measurements are reported with an especially designed quantum cascade laser arrangement for application in semiconductor industrial environments to track the approach for in situ process control in silicon etch plasmas. In gas mixtures with N2 and in microwave (MW) plasmas at pressures below 30 Pa concentrations of C4F6 and of SiF4 were measured simultaneously online for the first time. It could be demonstrated, that using quantum cascade lasers (QCL) it is possible to control ex situ mass flow controllers (MFC) based on in situ measured species concentrations in the gas phase and in the MW plasma bulk.

Manufactured carbon/epoxy composite surfaces were analysed before and after CF4 plasma treatment in order to study their wettability with the aim to master adhesion properties. Roughness and XPS surface composition on raw and plasma treated surfaces have been correlated to surface free energy measurements. The analytical tools were first validated on a flat epoxy resin before being tested and compared on rough industrial carbon/epoxy composite samples. The results reveal that these analytical techniques can be reproducible and relevant on manufactured composite for new surface treatment studies.

The hydrophobic properties of polymeric surfaces may cause fogging in transparent packaging and poor adhesion to printing colours and coatings. Novel plasma processes for durable functionalization of polypropylene and polyethylene terephthalate substrates were developed and analysed using optical emission spectroscopy. A worm-like nano pattern was created on the polypropylene surface prior to the deposition of thin polar plasma polymerised layers. For both substrates, highly polar surfaces exhibiting a surface tension of up to 69 mN/m and a water contact angle of about 10° were produced – providing the anti-fogging effect. The deposition of thin plasma polymerised layers protects the increased surface areas and enables to tailoring the surface energy of the substrate in a wide range. Wetting characteristics were determined by dynamic contact angle measurements. Investigations of the chemical composition of several layers using X-ray photoelectron spectroscopy and FT-infrared spectroscopy were correlated with functional testing. The surface topography was investigated using atomic force microscopy. The weldability and peeling-off characteristics of the plasma treated polymer films could be adjusted by varying the process parameters. Global and specific migration analyses were undertaken in order to ensure the manufacturing of plasma treated polymer surfaces for direct food contact purposes.