Search results for " Silicon"
showing 10 items of 247 documents
Positron Annihilation in Defected Monocrystalline Gold Samples
2005
Angular distribution of the positron annihilation quanta was measured for monocrystalline gold samples, oriented in (110) and (111) directions. The samples were deformed by elongation for different deformation degrees. The S and W parameters as a function of deformation degree of the sample were determined. It was found that the dynamics of the dislocations and vacancy generation during the sliding of some crystallographic planes, depends on the crystallographic direction.
Positron Annihilation in Metals Defected by Action of the Tensile Force
2006
Results of experimental investigations of uniaxially elongated mono- and polycrystalline samples of several metals (Fe, Ta, Pd, Ag, and Au), performed using the positron annihilation methods, are reviewed. The dependences of the S-parameters and positron lifetimes on the relative elongation of the samples were presented. The data obtained for polycrystalline samples indicate that in the proportionality and limited proportionality regions the changes in the physical properties are governed mainly by generation of vacancies and by kinetics of formation and transformations of vacancy clusters occurring flrst of all on the grain boundaries of monocrystallites. In the region of plastic deformati…
Morphology Study of the Porosity of the GaP Surface Layer Formed on the Surface of a Single Crystal by Electrochemical Etching
2021
The article analyzes the morphological characteristics of a porous GaP surface layer formed on the surface of monocrystalline gallium phosphide by electrochemical etching. The correlations between the etching time and the appropriate size, shape and density of pores have been established and studied in detail.
Micro‐tomographic characterization of composite recycled glass‐silicone foams for applications in civil engineering
2019
Noninvasive X‐ray micro‐computed tomography was applied for a complete quantitative and qualitative analysis of the cellular structure of composite foams constituted by a silicone matrix and a glass production waste filler. Composite foams with different glass filler weight content in the range 0–80% were synthesized and characterized. The tomographic analysis was employed in order to assess the structural heterogeneities, void fraction values, and bubble size distribution for all composite foams. The 3D micro‐CT images analysis, performed at different cross‐sections, highlighted heterogeneous cell growth or more elongated cells in the case of low and high filler content foams, respectively…
Selenium Nanoparticles Synthesized via a Facile Hydrothermal Method
2012
Crystalline selenium nanostructures were synthesized from the reaction of a GeSe3 glass with water at 85°C for 144 hours. The hydrolysis of the Ge-Se bonds releases Se fragments in the solution where they form a colloidal suspension of amorphous nanospheres. The later evolve toward a more stable hexagonal phase (trigonal) leading to the anisotropic growth of one-dimensional monocrystalline structures. Filaments, bars and tubes of monocrystalline trigonal selenium were obtained with diameters ranging from 10 nm to 1 µm and aspect ratio up to 180. This simple process in aqueous solution opens new perspectives for the synthesis of 1D nanoparticles of trigonal selenium at large scale.
Signal to Noise Ratio of Silicon Photomultipliers measured in the Continuous Wave Regime
2014
We performed a Signal to Noise Ratio characterization, in the continuous wave regime, at different bias voltages, frequencies and temperatures, on a novel class of silicon photomultipliers fabricated in planar technology on silicon p-type substrate. Signal to Noise Ratio has been measured as the ratio of the photogenerated current, filtered and averaged by a lock-in amplifier, and the Root Mean Square deviation of the overall current flowing to the device. The measured noise takes into account the shot noise, resulting from the photocurrent and the dark current. We have also performed a comparison between our SiPMs and a photomultiplier tube in terms of Signal to Noise Ratio, as a function …
The DAMPE silicon–tungsten tracker
2016
Abstract The DArk Matter Particle Explorer (DAMPE) is a spaceborne astroparticle physics experiment, launched on 17 December 2015. DAMPE will identify possible dark matter signatures by detecting electrons and photons in the 5 GeV–10 TeV energy range. It will also measure the flux of nuclei up to 100 TeV, for the study of the high energy cosmic ray origin and propagation mechanisms. DAMPE is composed of four sub-detectors: a plastic strip scintillator, a silicon–tungsten tracker–converter (STK), a BGO imaging calorimeter and a neutron detector. The STK is composed of six tracking planes of 2 orthogonal layers of single-sided micro-strip detectors, for a total detector surface of ca. 7 m2. T…
Heavy-Ion Microbeam Studies of Single-Event Leakage Current Mechanism in SiC VD-MOSFETs
2020
Heavy-ion microbeams are employed for probing the radiation-sensitive regions in commercial silicon carbide (SiC) vertical double-diffused power (VD)-MOSFETs with micrometer accuracy. By scanning the beam spot over the die, a spatial periodicity was observed in the leakage current degradation, reflecting the striped structure of the power MOSFET investigated. Two different mechanisms were observed for degradation. At low drain bias (gate and source grounded), only the gate-oxide (at the JFET or neck region) is contributing in the ion-induced leakage current. For exposures at drain–source bias voltages higher than a specific threshold, additional higher drain leakage current is observed in t…
Crystallographic analysis of extended defects in diamond-type crystals
2005
Abstract To investigate irradiation-induced Si amorphization during its initial stages, we have performed a classical molecular-dynamics (MD) calculation for the case of self-irradiation by 5 keV ions at a low temperature of 100 K. We examined the geometry of self-interstitial atom (SIA) clusters using the pixel mapping (PM) method, on the output data of MD calculations. Perfect crystalline silicon (c-Si) is amorphized by self-irradiation, and we observe that many SIA are produced. During sequential self-irradiation, the most frequently observed species were isolated SIA, i.e. I1 (monomer). The fractions of SIA clusters decreased as I2 (dimer), I3 (trimer), and I4 (tetramer) clusters, respe…
Results on radiation hardness of black silicon induced junction photodetectors from proton and electron radiation
2020
Abstract The stability of black silicon induced junction photodetectors under high-energy irradiation was tested with 11 MeV protons and 12 MeV electrons using fluence of 1 ⋅ 10 10 protons/cm2 and dose of 67 krad(Si) for protons and electrons, respectively. The energies and dose levels were selected to test radiation levels relevant for space applications. The degradation was evaluated through dark current and external quantum efficiency changes during (within 1 h after each step) and after (some days after) full irradiation sequences. Furthermore, the black silicon photodetectors were compared to planar silicon induced junction and planar silicon pn-junction photodetectors to assess the co…