In this study, Ag/OD-MO/Ag surface-type diode was fabricated by drop-casting orange dye and methyl orange blend thin film from 1.0 wt.% aqueous solution, under the effect of an electric field, on a glass substrate with preliminary deposited silver electrodes. Geometrical length and width of the semiconducting channel between metallic electrodes were equal to 40 μm and 21 mm, respectively. The dark I-V characteristics exhibited strong rectification behaviour though both electrodes were from the same metal. The average value of rectification ratio (RR) was 27 and it was found that RR varies with applied voltage in the range of 1–40. The dark I-V characteristics were simulated by modified Shockley equation and space-charge limited currents (SCLC) approach. Different diode parameters were calculated from current-voltage characteristics. The diode showed non-ideal I-V behaviour with a quality factor greater than unity. Energy band diagram is proposed for the Ag/OD-MO/Ag surface-type diode.

In this work, we investigate the emission of the nano-hole array in an ultrathin silver film at infrared regime. It is shown that when the incident light illuminates the nano-hole array, the localized surface plasmons are excited and serve as electric dipoles. The emission of the nano-hole array presents a strong directivity. The maximum radiation is located at infrared regime, and it can be tuned by the period of the nano-hole array, the incidence angle and the polarization of the excitation light. These findings extend our understandings of optical property of metallic nano-structures and provide a unique way to achieve infrared antenna arrays, which may achieve potential applications in photovoltaics and telecommunication.

The temperature distribution in dentin under pulse Er:YAG laser radiation has been studied and simulated, analytically. For this reason we considered heat deposited in dentin due to laser radiation. The heat conduction equation has been solved and the temperature distribution has been obtained. The obtained results then have been used for dentin and discussed. Based on the simulation, the temperature rise to 40.5 K for 300 mJ and 21 pulses which have very good consistency with the experiment.

In this paper, we report the experimental data of photoresponse namely; voltage responsivity and speed of response at λ = 904 nm of silicon photodiode formed by pulsed laser-induced diffusion technique. Experimental results demonstrated that the photodiode parameters strongly depend on the laser energy and substrate temperature. Maximum Responsivity obtained for p-n junctions photodetectors prepared by laser fluence of 9.17 J/cm2 for Al-doped Si and 10.03 J/cm2 for Sb-doped Si at substrate temperature (T s ) of 598 K. The pulse response waveform of photodetectors illustrated that the rise time is not dominated by RC. Non-linearity deviation coefficient was improved by factors 1.6 for and 2.7 for for Al-doped Si and Sb-doped Si photodetectors respectively when T s is raised from 300 K to 598 K.

The present paper deals with the study and experimentation of a rotor current excited Vernier reluctance machine. First, the structure is introduced and the conditions on the teeth and the polarity numbers necessary for the smooth running of such a structure are presented. Then, a simple procedure is given, based on some simplifying hypotheses, to obtain the initial geometrical and electrical sizes of a designed prototype. To validate the operating principle of the structure, a prototype is designed and studied using 2D FEM. Finally, this prototype was constructed and simulation results were compared to those obtained from the prototype.

Laser Thomson scattering technique has been used to measure the electron density and the electron temperature in a pulsed single filament micro-discharge. The single filament discharge was created between a needle and a hemispherical electrode surface. The spatial and temporal profiles of the electron density and the electron temperature in the center of the discharge gap have been measured. The absolute values of the electron density and electron temperature were found to decrease with time and away from the discharge axis. These profiles have been measured for the first time.

Amorphous Se70Te30–x Cdx (x = 0, 10) are obtained by thermal evaporation under vacuum of bulk materials on pyrographite and glass substrates. The I – V characteristic curves for the two film compositions are typical for a memory switch. They exhibited a transition from an ohmic region in the lower field followed by non-ohmic region in the high field region in the preswitching region, which has been explained by the Poole-Frenkel effect. The temperature dependence of current in the ohmic region is found to be of thermally activated process. The mean value of the threshold voltage $\bar{V}_{th}$ increases linearly with increasing film thickness in the thickness range (100–491 nm), while it decreases exponentially with increasing temperature in the temperature range (293–343 K) for both compositions. The results are explained in accordance with the electrothermal model for the switching process. The effect of Cd on these parameters is also investigated.

Nanodots forming dense assembly on a substrate are difficult to characterize in terms of size, density, morphology and cristallinity. The present study shows how valuable information can be obtained by a combination of electron microscopy techniques. A silicon nanodots deposit has been studied by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) to estimate essentially the dot size and density, quantities emphasized because of their high interest for application. High resolution SEM indicates a density of 1.6 × 1012 dots/cm2 for a 5 nm to 10 nm dot size. TEM imaging using a phase retrieval treatment of a focus series gives a higher dot density (2 × 1012 dots/cm2) for a 5 nm dot size. High Resolution Transmission Electron Microscopy (HRTEM) indicates that the dots are crystalline which is confirmed by electron diffraction. According to HRTEM and electron diffraction, the dot size is about 3 nm which is significantly smaller than the SEM and TEM results. These differences are not contradictory but attributed to the fact that each technique is probing a different phenomenon. A core-shell structure for the dot is proposed which reconcile all the results. All along the study, Fourier transforms have been widely used under many aspects.

This paper deals with the study of very low incident energy (0–12 eV) electron beam interactions with porous silicon (PS) substrates. It mainly concerns electron stimulated desorption (ESD) of negative H− ions ejected during a resonant bond breaking process. The experiments performed with a specific experimental set-up show that initially the PS surface was repulsive with regards to the low energy electron beam so that a reference voltage v 0 = 2.44 V sets the origin of incident electron energy. Thus the resonant desorption process was centred at 7.5 eV with a threshold at 4.6 eV, close to characterisations on the hydrogenated surfaces of silicon crystals. However, the desorption yield was here very low in comparison. It was assumed that a large fraction of the incident electron beam entered the substrate depth enough without triggering significant ion desorption.Progressive shifts in the reference potentials up v 0 = 5 V and significant reductions in desorption yield were caused by repeated electron bombardments with energies never exceeding 12 eV. These variations were attributed to changes in the surface composition of the porous silicon. It is assumed that residual fluorine atoms left after PS preparation might migrate towards the porous silicon surface as F− ions to enhance the electron beam repulsion. Following a general discussion, several experiments are suggested in order better to control modification of surface composition responsible for the ageing of the PS substrates.

Composites consisting of epoxidized natural rubber (ENR) and organically modified montmorillonite (OMON) in the ratio of 70:30 by weight percent have been synthesized. X-ray diffraction (XRD) measurements were made to estimate the basal plane spacing between the layered structures of the montmorillonite (MON) before and after it was organically modified and also for the composite. The increment in basal spacing of 1.758 nm indicated that intercalation of ENR-50 chains occurred in the silicate layers with the ammonium ion being attached to the layers after the modification. TSC measurements indicated that the intercalation resulted in a suppression of the $\alpha $  peak of the ENR around -25 °C which is also referred to as the T g of the material. Two new and broader peaks around 30 °C and 73 °C appeared in the composite. The suppression of the peak may be interpreted as a result of the increasing rigidity due to the three-dimensional network of physical links formed.

Lateral conductivity effects have been investigated in self-organised InAsquantum dot (QD) structures grown in a GaAs matrix with different caplayers. Current-voltage (I-V), capacitance-voltage (C-V), DLTS, capacitanceand conductance frequency dependence, fast defect transient (FDT),and electron beam induced conductivity (EBIC) measurements were applied.The conductivity in the QD plane decays within a distance of 10 microns.The capacitance transients are dominated by the local QD-plane transversalconductivity and by the free carrier transport in the cap layer.The nonequilibrium free carrier created by electron beam excitationdevelop a potential barrier at macroscopic distances from the electricalcontacts.

The room-temperature diffusion of evaporated Fe atoms into Si and silicon-on-insulator (SOI) materials has been studied by means of the Kelvin-surface photovoltage (SPV) method. The contactless and imaging feature of this technique enabled us to visualize the evidence of the Fe diffusion by using a single sample partly deposited with Fe. The image contrast in the regions between deposited and non-deposited with Fe was clearly observed in the SPV measurements, even after the thin Fe evaporated layer was completely removed off from the SOI surface. In addition, this contrast can be observed down to about 80 nm from the top surface. This result indicates that the Fe atoms can be soluble in the Si layer at room temperature, when Fe atoms are introduced by the vacuum evaporation. Furthermore, the time variation of the depth profile of Fe contamination was also discussed. Our results suggest that the evaporated Fe atoms diffused into the Si layer and dissolved in some form as a recombination center at room temperature.

Non-destructive techniques are ideal for process control and process development. They do not involve any special wafer treatment and the wafers can be further processed in the manufacturing line. A relatively new technique that can be applied to materials characterizations is room temperature photoluminescence (RT-PL). Defects can be revealed because of the enhanced non-radiative recombination at the defect site. The efficiency of detecting defects in SiGe was evaluated. Defects could be detected in blanket film SiGe layers, and there was a good correlation with bright field microscopy inspection and laser scanning methods. The effect of ex-situ cleaning, pre-bake and Boron doping conditions have been investigated. The results follow the expected trends, more defects for non-standard processing. The defects detected by RT-PL were confirmed using transmission electron microscopy (TEM). Defects could also be detected in part-processed patterned wafers, giving a direct indication of the material quality in product wafers.

A possible application of nanometer-sized junction arrays is to Coulombblockade thermometry (CBT), although only highly disordered arrays can befabricated at present. In this paper, the characteristics of CBT device withdisordered arrays will be studied. Similar to what is observed for uniformarrays, there is a dip at zero bias voltage in the differential conductanceof disordered arrays. However, the half-width $V_{1/2}$ of the dip forone-dimensional disordered arrays is largely dispersed. This study suggeststhat better devices can be developed by connecting a number ofone-dimensional arrays in parallel to form an array group. The dispersion ofhalf-width is quite small with values of $V_{1/2}$ close to a constant.Further, the effects of electromagnetic environment and low temperature onthe half-width are investigated. Results are agreed with those observedexperimentally, that for the effect of the environment is negligible forlarge arrays. The half-width of a disordered array may be bigger or smallerthan the ideal value, depending on the extend of disorder.

Formation conditions, optical nonlinear properties and applications of F2 − color centers in LiF monocrystals are investigated. The efficiency of F2 − centers generation depending of irradiation conditions and content of OH− impurities of the LiF monocrystal are also presented. Thermal stability of the centers generated by electron irradiation was studied. It was measured the variation of absorption factor of the LiF: F2 − crystal in the −40 °C to 60 °C temperature range. The LiF: F2 − crystals obtained by an efficient method of irradiation with electrons generated by a linear accelerator were employed in Q-switching a Nd: YAG laser cavity with output energies of 18 mJ and fluctuations less than 5% in the −40 °C to 60 °C temperature range.

This paper deals with the solution of inverse problems in magnetostatics. The cases the authors have broached are finding the current density or positions of air coils on the basis of magnetic field measurements. These problems are ill-posed, so regularization techniques are needed. The authors discuss the main iterative regularization principles, and the stability issues of these inverse problems. This method is applied to MRI magnets. Numerical results are presented.

Gold nanoparticles have great potential toward optical investigations in biological tissues which include imaging applications as well as therapeutic applications. However, introduction of gold nanoparticles such as nanospheres into the tissue may alter the inherent physical properties of the embedding medium. Of note, the thermal diffusivity of the medium will be significantly altered imposing serious limitations to the efficacy of several imaging and therapeutic modalities. In this context, we report experimental investigations based on open photoacoustic cell configuration to evaluate the thermal diffusivity changes in polyvinyl alcohol (PVA) phantom tissue doped with gold nanospheres. The investigations performed demonstrate a non-destructive methodology for the measurement of thermal diffusivity and the experimental results show that the thermal diffusivity of the tissue will be significantly reduced when they are administered with plasmonic nanoparticles.

We propose a simple method to design multichannel electron wave filters based on graphene superlattices with one-dimensional periodic potentials, which can choose not only the peak energy of each channel but also the bandwidth independently. This method is described by two samples for the design of two-channel, three-channel filters. Additional defects are introduced symmetrically into the superlattices, then modes are generated, which overlap with the channels that need to tune. These defects make the bandwidth of a certain channel increased without location shifted, while the other channels almost keep constant. The corresponding electronic devices may benefit from this method.

The accurate simulation of power electronic systems is possible when including accurate models of the semiconductor devices, but practically not affordable. Classical ideal averaged models of the system are not suitable either. Hence, averaged models including the non-linear effects of the power semiconductor devices appear quite efficient.The proposed non-ideal PWM-switch model is a useful method for modeling pulse width modulated converters operating in the continuous conduction mode. The main advantages of the proposed averaged model are the takes into account of the non-linear effects of power devices and the possibility to estimate the dissipated power in the different circuit devices. The proposed electrical model can be applied to bi-directional converters and allows the coupling with thermal model in the power electronic system. A simple technique to evaluate the different static and dynamic parameters of the devices, from manufacturers data sheets or experimentally, is presented.

The crystallographic microstructure properties of Al-Ti alloys rapidly solidified by a vacuum melting process were investigated by XRD, SEM, optical observations and DSC analysis. It was found that the microstructures are polycrystalline fine-grained (typically 10—20 µm) of intermetallics in equilibrium with the solid solution Fcc α-Al(Ti) matrix.