The current-voltage (I-V) characteristic of the Au/n-GaAs/Au-Ge Schottky diode with native oxide interfacial layer has been studied as a function of hydrostatic pressure. The ideality factor and barrier height of the diode have shown hydrostatic pressure dependence. The pressure coefficient of the flat-band barrier height was found to be 10.3 meV/kbar and the flat-band barrier height at zero pressure was calculated as 0.854 eV. Additionally, the energy distribution of interface state density was determined from I-V characteristics for each hydrostatic pressure value.

In situ powder X-ray diffraction (XRD) studies on 3D micro-crystalline tin (II) sulfide (SnS) were carried out at different temperatures. While increasing temperature, the crystal structure of SnS remains stable as orthorhombic, whereas its lattice parameters and unit-cell volume are considerably varied. Further, these 3D micro-crystalline structures have showed a negative thermal expansion along the a-axis and positive expansion along the b- and c-axes. However, the overall drop along the a-axis of SnS crystals is nearly equal to their expansion along the c-axis. The observed changes in the structural properties of SnS micro-crystallites with temperature are discussed and reported.

In device technology, the multilayer contacts provide improved performance. The comparative study of different high work function bilayer Schottky metal (Pt/Pd, Pt/Ni and Pt/Ti) contact has been taken to study the DC and RF performance of n-GaN Schottky diode. The fabricated Schottky metal contact Pt/Pd, Pt/Ni and Pt/Ti annealed from room temperature to 800 °C studied shows that Pt/Pd Schottky metal contact on n-GaN shows high thermal stability and maximum barrier height 1.10 eV, ideality factor 1.001, lower series resistance and lower insertion loss (S21 dB) at high frequency compared to Pt/Ni and Pt/Ti bilayer Schottky metal contact.

The reverse I-V characteristics of In-pWSe2 and Al-pWSe2 Schottky barrier diodes were investigated at room temperature with two different metal thicknesses. A model is presented on the basis of thermionic emission and tunneling to explain the unusually high leakage current observed in these diodes. It has been identified that the major contribution to leakage current is by tunneling mechanism, which significantly affects the reverse I-V characteristics of the Schottky contacts, along with a very small amount of thermionic emission current. We have also extracted various Schottky diode parameters of the two types of diodes fabricated and compared the data. It is found that the diode with 1000 Å metal thickness possesses more tunneling current compared to 500 Å diode.

This work presents additional arguments about the enhancement of optical and electrical properties of SiNWs obtained by chemical etching and the beneficial effect of the formation of ultrathin film of SiO2 by a heat treatment at 900 and 1000 °C reported recently by Karyaoui et al. in [Eur. Phys. J. Appl. Phys. 58, 20103 (2012)]. In the actual study, we report the effect of this thermal oxidation treatment on the morphological and optoelectronic properties of silicon nanowires (SiNWs). The SEM and AFM observations exhibit indeed a remarkable change of the surface shape after this oxidation. On the other hand, the LBIC measurements of the SiNWs reveal that the thermal treatment improves the optoelectronic response at 900 °C and the effective diffusion length increases from 150 μm for untreated SiNWS to 235 μm after thermal treatment.

The electrical behavior of organic memory devices based on pentacene thin film transistor using polymethylmethacrylate (PMMA) as the gate dielectric is reported. Memory behaviors based on incorporating a layer of thermally evaporated metallic floating gate are demonstrated. The gate electrode was made from 50 nm evaporated aluminum on glass substrate, and the drain and source electrodes were fabricated by evaporating 50 nm gold. The effects of the insulator thickness on the stability of pentacene layer are also investigated. The memory transistors containing the floating gate exhibited clear hysteresis in their electrical characteristics (output and transfer characteristics). Under an appropriate gate bias (2 s pulses), the floating gate is charged and discharged, resulting in significant threshold voltage shifts. Pulses of 1 V resulted in clear write and erase states. The shifts in the threshold voltage of the transfer characteristics were attributed to the charging and discharging of the floating gate. The detailed programming and erasing procedures are reported.

To study the gas sensing properties for CO2 and NH3 gas, powdered gold nanocomposite polyaniline was chemically synthesized and ultrathin films were fabricated. XRD spectra of these samples indicate the polycrystalline nature of the film. UV-vis spectra showed peak at 3.8 eV corresponding to π-π* transition. The relative sensitivities of the gas to air were around 70 and 530 for CO2 and NH3 gas respectively. Temperature variation of gas conductivity showed the increase of conductivity of the films up to about 42 °C and then decreased for small change of temperature. Recovery time for the sample was 54 s.

It is well known that space charge accumulation in insulating materials constitutes the principal cause of dielectric breakdown. Though space charge measurements in polymeric materials have been extensively developed over the last two decades, modeling and simulation works have progressed slowly in this respect. In the present study, a model for bipolar charge transport, as a basis for studying breakdown phenomenon in low density polyethylene (LDPE), is presented. Indeed, we are especially interested in external current dynamic which is the witness of the sample post breakdown. Our results show the effect of the high dc applied voltage and the generation of the space charge packets on the apparition of the post breakdown of the insulator. In order for this effect to be revealed, the external current evolutions under low and high dc applied voltages before and at the breakdown are determined. Indeed, these evolutions show an abrupt increase that is observed when the charge packet aspect occurred in the sample under high dc applied voltage. This observed abrupt increase of the external current is attributed to post breakdown phenomenon. These results are obtained for the first time in modeling and show some aspects similar to those observed in some experimental works.

The Monte Carlo (MC) simulation of electron and hole impact ionization rates for 4H- and 6H-SiC in high electric field is presented. This work focuses on the study of impact ionization rates and impact ionization coefficients since these parameters play a very important role in determining the device performance. In our simulation, the impact ionization rates are obtained by using modified Keldysh equation with a softness factor fitted to the experimental data described by other researchers. The electron and hole impact ionization coefficients in 4H- and 6H-SiC are parameterized at high electric field. The electron and hole impact ionization coefficients for a wide range of electric fields have been successfully derived in our model.

This contribution deals with the state of the art of studies concerning the fabrication of electric double-layer capacitors (EDLCs) also called super- or ultracapacitors and obtained using carbon nanotubes (CNTs) without exploiting Faradic reactions. From the first work published in 1997, EDLCs fabricated using carbon nanotubes as constitutive material for electrodes showed very interesting characteristics. It appeared that they could potentially outperform traditional technologies based on activated carbon. Different methods to fabricate the CNT-based electrodes have been proposed in order to improve the performances (mainly energy densities and power densities), for example filtration, direct growth on metal collector or deposition using an air-brush technique. In this contribution we will introduce the main works in the field. Finally, we will point out an emerging interest for supercapacitors fabricated on flexible substrates, exploiting the outstanding mechanical performances of CNTs, for new kinds of applications such as portable electronics.

Thanks to atomic force microscope observation of swift heavy ion-induced structural modifications of SiO2-Si layer, we show that for a given linear energy transfer value the radial atomic modification along the ion track depends on the ion velocity regime.

This paper presents a preliminary experimental investigation of the damping effect of bubble levels on the rotation of pendulous systems. The damping efficiency of such a level is directly correlated to the energy dissipated by the bubble motion. This energy depends on the physical characteristics of the bubble level such as the radius of curvature of the tube, the liquid properties and the bubble length. This study demonstrates that a bubble level can be used to damp the oscillations of dynamic mechanical systems. In particular, commercially available bubble levels might prove suitable for applications where one needs to damp efficiently oscillating systems for which the initial potential energy is less than a hundred times the energy dissipated by the bubble displacement for the first oscillation.