The general method of diagnostics of the transient radiation of ribbon-shaped and axially-symmetric electron beams of small section (0.1 mm) and high-power density (1–100 kW/sm2) is described. Selective analysis of various types of transient radiation detectors of type photo-camera, video-camera and digital photo-camera is carried out at first. Advantages and disadvantages of radiation detectors are pointed out to be taken into account at analysis of the object under investigation.

One of the important parameters in understanding the mechanism of the early stage of organic thin-film growth is the critical nucleus size i*. Here, submonolayer films of para-sexiphenyl grown on amorphous silicon dioxide substrates were investigated by means of atomic-force microscopy and have been analyzed using the recently proposed capture-zone scaling. Applying the generalized Wigner surmise we determine from the capture-zone distribution i* at room temperature and 373 K. The results are compared to traditional analysis by island-size scaling and the applicability of the capture-zone scaling is critically discussed with respect to island shape.

Backside sample preparation is a well-known method to help circumvent undesired effects and artifacts in the analysis of a sample or device structure. However it remains challenging in the case of thin layers analysis since only a fraction oRelax;f the original sample must remain while removing most or all of the substrate and maintaining a smooth and flat surface suitable for analysis. Here we present a method adapted to the preparation of ultrathin layers grown on pure Si substrates. It consists in a mechanical polishing up to a few remaining microns, followed by a dedicated wet etch. This method can be operated in a routine fashion and yields an extremely flat and smooth surface, without any remaining Si from substrate. It therefore allows precise analysis of the layers of interests with various characterization techniques.

The presence of impurities in the molecular crystals of organic semiconductors is a key limiting factor for the performance of related electronic devices. For this reason, the atomic-scale details of impurity incorporation are important elements for modeling and optimization of organic electronic systems. In this article, we use first-principles density-functional theory calculations to describe the vibrational spectrum of typical impurity culprits in the prototype organic semiconductor pentacene. First, we validate the computational approach by comparing results on vibrational modes of impurity-free pentacene with available theoretical and experimental data. We then analyze the effect of oxygen, water, and hydrogen impurities on the modes of pentacene crystals. The results identify distinct impurity-related features which can help understand the evolution of impurities in pentacene samples.

The magnetohydrodynamic stability criterion of self-gravitating streaming fluid cylinder under the combined effect of capillary, inertia, pressure gradient and electromagnetic forces has been derived. The results are discussed analytically and some data are verified numerically for different parameters of the problem. The magnetic field is stabilizing, but the streaming is destabilizing while the self-gravitating and capillary forces are stabilizing or destabilizing according to restrictions. The stable and unstable domains are identified and moreover the influences of the magnetic field and capillary forces on the self-gravitating instability of the model have been examined. The including of the electromagnetic force together with both the capillary and self-gravitating forces improve the instability of the model. However, the self-gravitating instability will never be suppressed whatever are the effects of the capillary and MHD forces stabilizing effects.

Thin-film transistors (TFTs) fabricated on flexible plastic substrates are an integral part of future flexible large-area electronic devices like displays and smart textiles. Devices for such applications require stable electrical performance under electrical stress and also during applied mechanical stress induced by bending of the flexible substrate. Mechanical stress can be tensile or compressive strain depending on whether the TFT is located outside or inside of the bending plane. Especially the impact of compressive bending on TFT performance is hard to measure, because the device is covered with the substrate in this case. We present a method which allows us to continuously measure the electrical performance parameters of amorphous Indium-Gallium-Zinc Oxide (a-IGZO) based TFTs exposed to arbitrary compressive and tensile bending radii. To measure the influence of strain on a TFT it is attached and electrically connected to a flexible carrier foil, which afterwards is fastened to two plates in our bending tester. The bending radius can be adjusted by changing the distance between these plates. Thus it is possible to apply bending radii in the range between a totally flat substrate and ≈1 mm, corresponding to a strain of ≈3.5%. The tested bottom-gate TFTs are especially designed for use with our bending tester and fabricated on 50 μm thick flexible Kapton® E polyimide substrates. To show the different application areas of our bending method we characterized our TFTs while they are bent to different tensile and compressive bending radii. These measurements show that the field effect mobilities and threshold voltages of the tested a-IGZO TFTs are nearly, but not absolutely, stable under applied strain, compared to the initial values the mobilities shift by ≈3.5% in the tensile case and ≈−1.5% in the compressive one, at a bending radius of 8 mm. We also measured the influence of repeated bending (2500 cycles over ≈70 h), where a shift of the performance parameters can be observed, too. The saturation mobility of the flat device decreases by 4.5%, and the threshold voltage raises 0.1 V. These results show that it is possible to characterize the influence of different kinds of bending on flexible thin-film devices in a very reliable way with one experimental setup.

Understanding how high-intensity compression waves damage human tissue is critical to developing improved therapeutic interventions for treating traumatic injuries arising from explosive devices. Assessment of the cellular and molecular basis of damage that is physiologically relevant requires the study of biomaterials using appropriate techniques which subject samples to compression waves at magnitudes relevant to traumatic injury. Here, we present the design and initial calibration of a polycarbonate chamber to be used in a split Hopkinson pressure bar system to study live cell cultures.

Computational fluid dynamics solutions of the Reynolds Averaged Navier-Stokes equations have been used to numerically predict the thrust of a thermally choked ram accelerator in subdetonative velocity regime. Studies were focused on a projectile operating in a 38-mm-diameter ram accelerator tube loaded with premixed propellant gas; methane/oxygen/nitrogen at 5.15 MPa fill pressure. Simulations were carried out for a series of incoming velocities. The shear stress transport turbulence model (SST) and the eddy dissipation combustion model (EDM) with five-step reaction mechanism were used to simulate the fully turbulent reactive flow field around the projectile. The predicted projectile thrust-velocity agreed well with the experimental measurements, in addition, the CFD predicted pressure variation and magnitude along projectile axial direction also agreed well with the test data. The present investigation reveals some key features of the shock-wave system around the projectile, which are important in determining the characteristics of the thermally choked propulsive mode. These findings are useful in understanding the characteristics of high speed turbulent combustion process in the ram accelerator.

Knowledge of endothermic and exothermic heat capacities of optoelectrics materials is important to define their energy/data storage capability. Heat capacities of Se98-xZn2Inx (0 ≤ x ≤ 10) chalcogenide glasses at glass transitions (Tg) and crystallisations temperatures (Tc) have been reported in this work. The evaluated endothermic (ΔCpg) and exothermic (ΔCpc) heat capacities of Se98-xZn2Inx system varies with alloying concentrations obtained minimum and maximum respectively at threshold composition (6 at wt.% of In). The up and down trend in ΔCpc and ΔCpg at Tg, Tc could be explained on the basis of structural units/avarage coordination number 〈r〉 of the glassy materials.

The Schottky barriers formed at the interface between gold and various rare earth doped GaN thin films (RE = Yb, Er, Gd) were investigated in situ using synchrotron photoemission spectroscopy. The resultant Schottky barrier heights were measured as 1.68 ± 0.1 eV (Yb:GaN), 1.64 ± 0.1 eV (Er:GaN), and 1.33 ± 0.1 eV (Gd:GaN). We find compelling evidence that thin layers of gold do not wet and uniformly cover the GaN surface, even with rare earth doping of the GaN. Furthermore, the trend of the Schottky barrier heights follows the trend of the rare earth metal work function.

Aggregated systems of silver (Ag) and gold (Au) nanoparticles coated with cationic polythiophene were prepared, which showed optical properties typical for strongly coupled plasmonic excitations. The procedure allowed tune up the three-dimensional arrangement of nanoparticles assembly for achieving strong SERS effect at the excitation wavelength depending on the polymer concentration. By combination with an anionic derivative of polythiophene thin multilayer films composed of alternating anionic and cationic polythiophene with mutually interacting plasmonic Au nanoparticles were successfully prepared using layer-by-layer deposition.

We developed the novel pressure-annealing method for fabricating printed low-work function metal patterns and printed metal alloy patterns. The printed diode having various rectification properties was successfully produced by using the printed metal alloy electrode pressure-annealed.

The dynamics of MinD proteins have been acknowledged as playing a central role in accurate cell division. In our study, a spot tracking technique (STT) was applied to track motion and quantitatively characterize the dynamic behavior of MinD proteins on the level of particle cluster in Escherichia coli. We focused on the time and spatial distribution of MinD proteins. With the STT technique, the main quantitative results are twofold: (i) dynamic local and global pattern formations and (ii) energy landscape. The overall MinD cluster motion is governed by two dynamical time scales, namely the (slow) trapping time (~26 s) that appears at the cell poles, and the (fast) switching time (~1–2 s) which emerges between the cell poles. MinD cluster motion at the polar zones performs subdiffusion. The energy landscape is found to be two wells and one barrier. These energy landscape results are to relate with the memory effect of GFP-MinD cluster motion, measuring the PSD exponent approximately 1.57 (α ~ 0.57) corresponding to the estimated potential depth U0 ~ 1.75kBT.

C38 carbon steel has been nitrided by radiofrequency cold plasma discharge with the aim to study the effect of gas composition on structural and mechanical properties of nitrided substrates. The plasma nitriding was carried out on unheated substrates, using two different gas mixtures (75% N2/25% H2 and 25% N2/75% H2) for 8 h of plasma treatment. Electron Probe Microanalysis (EPMA) showed that the nitrogen content and the nitride layer thickness mainly depend on the hydrogen content in the plasma. For 75% N2/25% H2 mixtures, nitrided samples showed the formation of thicker nitride layer with high content of nitrogen compared to those formed in the case of 25% N2/75% H2 or pure N2 . The thickness of the nitride layer formed is approximately 15 μm for 8 h of plasma with 75% N2/25% H2 . X-ray photoelectron spectroscopy (XPS) was employed to obtain chemical-state information of the plasma- nitrided steel surfaces. The mechanical properties of plasma-nitrided C38 steel were investigated by Vickers microhardness measurements. The micromechanical results show the formation of a new hard layer on the surface after N2/H2 treatment plasma and it reaches a maximum value of more than 2242 HV0.005 for 75% N2/25% H2 plasma-nitrided samples. However, a decrease in the hardness values with the applied load has been evidenced.

In this study, we propose new approach to study on hydrogen implantation into SiC crystalline structure and its effect on thermal oxidation. This paper has investigated on effects of hydrogen implantation into the surface structure of 6H-SiC crystal before and after thermal oxidation in oxygen ambient. H ions were implanted in SiC with dose of 1×1016 atoms/cm2 and energy of 15 keV. AFM results of implanted and non-implanted areas show that roughness in the implanted area is more than the non-implanted but, we could not observe any evidence of implanting effect in the nano scrapes which were created during polish process. Also, crystal quality, effect of H implantation and depth of maximum concentration were determined by RBS- Channeling. Moreover, it shows that the collision of H ions has affected on the SiC atoms. Distribution and dose of H ions were estimated by ERD technique. Furthermore, bonding between SiC atoms was investigated in implanted and non-implanted areas by FTIR technique. In addition, FTIR results in two areas show a significant difference between both areas before and after oxidation in oxygen ambient.

Flexibility will significantly expand the application scope of electronics, particularly large-area electronics. Over the last 10 years, printed organic electronic is believed to be one of the next major technological breakthroughs in the field of microelectronic and the use of printing technology to process organic field-effect transistors (OFETs) opens promising perspectives for low-cost, large-area circuits integrated on flexible, plastic substrates. With amorphous polymer-based thin film transistors acceptable electrical performances are now achieved with relatively good stability at ambient air. In the literature a lot of work has been devoted to study degradation of device characteristics under bias stress conditions but only few papers deal with the mechanical behavior. In this paper, we review our first reliability results obtained on flexible organic thin film transistors under mechanical stresses. The variations of electrical characteristics under bending tests, both in compression and tension, have been studied. Using specific equipment, we have also evaluated the reliability of transistors under cyclic bending tests. The stress dependency of the transfer characteristic deviates from the one observed for inorganic material like silicon.

Growth of thin layers of compound semiconductors such as GaAs and Alx Ga1−x As was obtained by Liquid Phase Epitaxy (LPE) at 838–828 ° C in thickness range of 0.1–4.3 μm which was estimated by Scanning Electron Microscopy (SEM). By Secondary Ion Mass Spectroscopy (SIMS) measurements, type of impurity atoms and their density and uniformity with respect to thickness were measured. In this way we are sure that variation of impurity atoms such as Si, Te, Sn and Ge indicates that epilayers were formed uniformly and it demonstrated that the LPE growth was a suitable way to obtain a good quality of epitaxy layers. Amount of composition parameter x in the compound semiconductor AlxGa1−xAs was measured which varies from 0.13 to 0.4. In-depth profiles of SIMS indicated that Al atom can be replaced by Ga atom in the GaAs crystalline structure.

We report a modified deep reactive ion etching method to realize high aspect ratio features and nano-grasses on silicon substrates. This etching technique uses sequential etching and passivation sub-cycles and it is based on three gases of H2, O2 and SF6 in the presence of rf-plasma. By adjusting the etching parameters such as the flows of various gases, the plasma power and duration of each cycle, the process can be controlled to obtain high aspect ratio vertical structures on silicon substrates. Features with aspect ratios of the order of 30–50 and heights of the order of 25–30 μm are obtained. On the other hand, one can program the etching parameters to achieve grass-full structures in desired places and with pre-designed patterns. The formation of nano-grass on silicon surface, improves its wetability with water and oil spills. This property has been used to entrap carbon nanotubes onto nano-structured surfaces in desired places.

The Dielectric Barrier Discharge (DBD) is composed of many Filamentary Discharges (FDs), and it can be applied to ozone generation, gaseous pollution control, etc. In our laboratory, we investigated efficient cleaning methods of diesel exhaust gas by DBD. From the results of numerical simulation of chemical reactions, a homogeneous DBD was expected to improve the efficiency of pollution control and also the ozone yield. Recently, we found that a DBD device using alumina as barrier material can generate an Atmospheric Pressure Townsend Discharge (APTD) in air. In this research, we setup two ozonizers with different discharge modes of FD and APTD, and compared the ozone yield. The experimental results showed that the ozone yield was higher by the FD mode than by the APTD mode in lower Specific Input Energy (SIE) region. However in the region that the SIE is larger than 420J/L, the APTD mode showed higher ozone yield than FD mode.