The plasma parameters for the fast deposition of highly crystallized microcrystalline silicon (µc-Si) films with low defect density are presented using a high-density and low-temperature SiH4-H2 mixture microwave plasma. A very high deposition rate of $\sim $65 Å/s was achieved for a SiH4 concentration of 67% diluted in H2 with a high Raman crystallinity Ic/Ia > 2.5 and a low defect density of 1−2 × 1016 cm−3 by adjusting the plasma conditions. Contrary to the case of a conventional rf plasma, the defect density of the µc-Si films strongly depends on substrate temperature, Ts, and increases with increasing Ts even if Ts is below 300 °C. This indicates that the real temperature at the growing surface is higher than the monitored value. A sufficient supply of deposition precursors such as SiH3 at the growing surface under an appropriate ion bombardment is effective for the fast deposition of highly crystallized µc-Si films as well as for the suppression of the amorphous incubation and transition interface layers at the initial growth stage.

The breakdown electroluminescence spectra of individual microplasmas in a p-n-junction with microplasma breakdown, which was prepared on a 3C-SiC crystal, have been investigated. The clear periodic structure of an oscillatory nature, which was discovered first by the authors recently, with a period of about 0.16 eV was observed in the emission spectra of this microplasma. The oscillations were superimposed over the entire investigated spectral region between 1.8–4.7 eV. The amplitude of the oscillations amounted to 0.05–0.25 of the background radiation intensity. The characteristics of the oscillatory structure and of the background radiation have been separated and compared. It turned out that they depend in different ways on the temperature and on the sample-powering regime. It has been revealed that the oscillatory structure is associated apparently with the energy transition (X3c−X1c) in the conduction band.

In the present paper, we report the compensation effect for the crystallization of different binary and ternary systems of some chalcogenide glasses. We have observed Meyer-Neldel rule between the pre-exponential factor K0 of rate constant K(T) of crystallization and activation energy of crystallization Ec in the present case.

Tris(8-hydroxyquinoline) aluminium (Alq3) inserted in the structure ITO/Alq3/Al is used to show how dielectric spectroscopy and a $\log \varepsilon '' ={\rm f}(\log \omega)$ representation can separate dielectric conductivity by bound charges from $\gamma _{0 }$ conductivity due to residual pseudo free charges. Coupled with the I(V) characteristic, the $\log \varepsilon '' ={\rm f}(\log \omega)$ representation allow to study the mobility of these carriers as a function of the applied bias voltage V; then the mobility was estimated to be $\mu \approx 2 \times 10^{-6}$ cm2 V−1 s−1 (with V = 0), and we demonstrate that $\mu $ approximately follows a Poole-Frenkel like law. Consequently, these results show that mobility determined by field effects is generally overestimated by around one order of magnitude for an electric field at around 1  MV cm−1. More precisely, we demonstrate that pseudo free charges exhibit a field and weakly temperature dependent mobility, which is in contrast to carriers involved in the trap–charge limited current regime which exhibit a temperature dependent and field independent mobility.

The principle of a specific optical device which was designed to homogenize the power density distribution of a CO2 laser beam is described in the paper. The detailed formulas to express the relation between power density distribution of converted beam and optical parameters of device are given. Based on this relation, a scheme to optimize the device is presented. The power density distributions simulated by computer before and after optimization are given. A tentative criterion to estimate the uniformity of a beam spot in which there are interference fringes, is put forward.

A series of M-type hexaferrite samples with composition Sr1−xLaxFe12O19 (x = 0.00, 0.05, 0.15 and 0.25) were prepared by standard ceramic technique. AC electrical conductivity measurements were carried out at different frequencies (20 Hz–1 MHz) and at different temperatures. The dielectric constant and dielectric loss tangent were measured in the same range of frequencies. The experimental results indicate that AC electrical conductivity increases on increasing the frequency as well as the temperature, indicating magnetic semiconductor behavior of the samples. The increase in AC electrical conductivity with frequency and temperature has been explained on the basis of Koops Model whereas dielectric constant and dielectric loss tangent has been explained with the Maxwell–Wagner type interfacial polarization in agreement with the Koops phenomenological theory.

Dielectric barrier discharges (DBDs) have been investigated under a wide range of experimental conditions (pulsed and sinusoidal excitation, input energy, frequency, and residence time) to remediate NOx from atmospheric O2 rich gas streams. In a given reactor under identical gas composition and equivalent energy density deposition, results show that the main parameter which controls the efficiency of the plasma process is the energy deposition mode. For example, in a pulsed DBD processing at energy density deposition of 30 J/L, 25% of NOx and 40% of C3H6 were converted at 35 mJ/pulse whereas, at 195 mJ/pulse these values were 0% and 15%, respectively. Furthermore, significantly different end products were observed when changing the nature of electrical excitation.

The conditions for formation of ion acoustic weak double layer in a dusty plasma are investigated. In case of much lower value of ion-electron temperature ratio, the weak double layer is observed when the fraction of the negative charge in the plasma on the dust grain is ${\geq}0.45$, whereas for equal ion-electron temperature it is observed only when the fraction is ${\geq}0.6$. The parameter regimes of transition from compressive to rarefactive double layer are also specified.

SiClx radicals, the silicon etching by-products, are playing a major role in silicon gate etching processes because their redeposition on the wafer leads to the formation of a SiOClx passivation layer on the feature sidewalls, which controls the final shape of the etching profile. These radicals are also the precursors to the formation of a similar layer on the reactor walls, leading to process drifts. As a result, the understanding and modelling of these processes rely on the knowledge of their densities in the plasma. Actinometry technique, based on optical emission, is often used to measure relative variations of the density of the above mentioned radicals, even if it is well known that the results obtained with this technique might not always be reliable. To determine the validity domain of actinometry in industrial silicon-etching high density plasmas, we measure the RF source power and pressure dependences of the absolute densities of SiClx (x = 0−2), SiF and SiBr radicals, deduced from UV broad band absorption spectroscopy. These results are compared to the evolution of the corresponding actinometry signals from these radicals. It is shown that actinometry predicts the global trends of the species density variations when the RF power is changed at constant pressure (that is to say when only the electron density changes) but it completely fails if the gas pressure, hence the electron temperature, changes.

A spectroscopic investigation of corona discharges in SF6/N2 gas mixtures has been undertaken using an optical multichannel analyser (OMA). A point-to-plane geometry has been used with point radii varying from 3 to 10 μm. Spectra are measured for high pressures ranging from 0.2 MPa up to 1.4 MPa and for different concentrations of SF6 in the gas mixture. The spectra in the 200–850 nm spectral range are mainly made of molecular bands, which is indicative of a low temperature discharge. It has been noted that SF6 emits in the region of 420 nm to 510 nm in positive and negative polarities, although in negative polarity the emission is weaker. For SF6/N2 mixtures, the main source of light emission is from N2. The resultant spectra are used to evaluate the rotational Tr and vibrational Tv temperatures of excited N2, Tr being considered, due to the high pressure, to be equal to the kinetic temperature Tkin in the corona discharge. Tr and Tv are determined by comparing the experimental spectrum of the second positive system ($C^{3}\Pi_{u}\to B^{3}\Pi_{g})$ of N2 and the simulated one, which is obtained using a convolution method. As expected, the results show that the measured rotational temperature Tr increases steadily with the mean discharge current, while its increase with gas pressure is less pronounced. The values of Tr are higher for the positive corona discharge than the negative and also for mixtures having higher amounts of SF6. In all conditions, we found $T_{v}>T_{r}$ and Tv is less sensitive to the variation of the current.

For physical processes which express themselves as a frequency, for example magnetic field measurements using optically-pumped alkali-vapor magnetometers, the precise extraction of the frequency from the noisy signal is a classical problem. We describe herein a frequency measurement system based on an inexpensive commercially available computer sound card coupled with a software single-tone estimator which reaches Cramér–Rao limited performance, a feature which commercial frequency counters often lack. Characterization of the system and examples of its successful application to magnetometry are presented.

A simple and straightforward method to assess the relative temporal fluctuation of the individual pixels in a CCD array with respect to the fluctuation of the spatial average is proposed. This procedure is based on the comparison of the low-frequency temporal noise of the individual pixels and the value of this magnitude averaged over the entire CCD. Moreover, this method is able to detect the presence of bad pixels within the array (drifting and flicking). The importance of this study resides in the need to know whether or not the behavior of the individual pixels can be approximated by that of the spatial average and to assess the stability of Nonuniformity Correction algorithms (NUC). Once the mathematical formulation was developed, it was applied to the analysis of a specific CCD array, the Sony ICX414AL. The results show three different trends in the behavior of its pixels.