Search results for " carbide"
showing 10 items of 101 documents
Failure Estimates for SiC Power MOSFETs in Space Electronics
2018
Silicon carbide (SiC) power metal-oxide-semiconductor field effect transistors (MOSFETs) are space-ready in terms of typical reliability measures. However, single event burnout (SEB) due to heavy-ion irradiation often occurs at voltages 50% or lower than specified breakdown. Failure rates in space are estimated for burnout of 1200 V devices based on the experimental data for burnout and the expected heavy-ion linear energy transfer (LET) spectrum in space. peerReviewed
Highly Homogeneous 2D/3D Heterojunction Diodes by Pulsed Laser Deposition of MoS2 on Ion Implantation Doped 4H-SiC
2022
In this paper, 2D/3D heterojunction diodes have been fabricated by pulsed laser deposition (PLD) of MoS2 on 4H-SiC(0001) surfaces with different doping levels, i.e., n− epitaxial doping (≈1016 cm−3) and n+ ion implantation doping (>1019 cm−3). After assessing the excellent thickness uniformity (≈3L-MoS2) and conformal coverage of the PLD-grown films by Raman mapping and transmission electron microscopy, the current injection across the heterojunctions is investigated by temperature-dependent current–voltage characterization of the diodes and by nanoscale current mapping with conductive atomic force microscopy. A wide tunability of the transport properties is shown by the SiC surface dopi…
Superior Fischer-Tropsch performance of uniform cobalt nanoparticles deposited into mesoporous SiC
2020
Electrochemically-derived well-crystalline mesoporous silicon carbide (pSiC) was used as a host for cobalt nanoparticles to demonstrate superior catalytic performance during the CO hydrogenation according to Fischer-Tropsch. Colloidal Co nanoparticles (9 ± 0.4 nm) were prepared independently using colloidal recipes before incorporating them into pSiC and, for comparison purposes, into commercially available silica (Davisil) as well as foam-like MCF-17 supports. The Co/pSiC catalyst demonstrated the highest (per unit mass) catalytic activity of 117 µmol.g(CO)-1.g-1(Co).s-1 at 220 °C which was larger by about one order of magnitude as compared to both silica supported cobalt catalysts. Furthe…
Effect of rotary cutting instruments on the resin-tooth interfacial ultra structure: An in vivo study
2013
Objectives: To evaluate the effect of cutting teeth with different types of burs at various speeds on surface topogra - phy of tooth surface and interfacial gap formation at resin-tooth interface. Material and Methods: The human molars were divided into seven groups: Diamond bur in airrotor (DA) & mi - cromotor (DM), crosscut carbide bur in airrotor (CCA) & micromotor (CCM), plain carbide bur in airrotor (CA) & micromotor (CM) and #600-grit silicon carbide paper (SiC). In five samples from each group Class II box-only cavities were restored. The occlusal surface of four teeth per group was flattened. Two out of four teeth were acid etched. Teeth were subjected for scanning electron microsco…
Monitoring of microRNA using molecular beacons approaches: Recent advances
2020
Abstract Micro ribose nucleic acid (miRNA) recognition is of remarkable significance in the investigation of its functions as well as diagnosis of various diseases. The significance of miRNA itself is owing to the complex regulatory roles in several physiological processes and its close association with important diseases such as cardiovascular problems, diabetes, Alzheimer's disease and different kinds of cancers. On the other hand, there are numerous challenges to conquer in the recognition of miRNA, consisting of low abundance, varied concentration range, small size, prolonged extraction process from cells and sequence resemblances. Traditional approaches for miRNA recognition do not mee…
3D superconducting hollow nanowires with tailored diameters grown by focused He+ beam direct writing
2020
Currently, the patterning of innovative three-dimensional (3D) nano-objects is required for the development of future advanced electronic components. Helium ion microscopy in combination with a precursor gas can be used for direct writing of three-dimensional nanostructures with a precise control of their geometry, and a significantly higher aspect ratio than other additive manufacturing technologies. We report here on the deposition of 3D hollow tungsten carbide nanowires with tailored diameters by tuning two key growth parameters, namely current and dose of the ion beam. Our results show the control of geometry in 3D hollow nanowires, with outer and inner diameters ranging from 36 to 142 …
FTIR Studies of Silicon Carbide 1D-Nanostructures
2015
Stable 1D silicon carbide nanostructures (nanowires) have been obtained via combustion synthesis route. Infrared absorption and reflection spectra for as-obtained and purified SiC nanowires were compared with the spectra of commercially available SiC nanomaterials. Principal vibrational modes have been identified. Reflectivity spectrum has been reconstructed by modeling of the dielectric function
Combustion Formation of Novel Nanomaterials: Synthesis and Cathodoluminescence of Silicon Carbide Nanowires
2009
This paper presents the combustion synthesis and characterization of one-dimensional silicon carbide nanostructures (nanowires of 3C-SiC polytype with zincblend structure) by means of cathodoluminescence technique. Cathodoluminescence spectra of nano-SiC samples and, as a reference, of a commercially available SiC micropowder are compared. It is shown that the emission band at 1.97 eV which is slightly evidenced in the spectrum of the commercial SiC under 10 keV electron beam irradiation becomes the prevailing band in CL of the purified silicon carbide nanowires.
Unifying Concepts for Ion-Induced Leakage Current Degradation in Silicon Carbide Schottky Power Diodes
2020
The onset of ion-induced reverse leakage current in SiC Schottky diodes is shown to depend on material properties, ion linear energy transfer (LET), and bias during irradiation, but not the voltage rating of the parts. This is demonstrated experimentally for devices from multiple manufacturers with voltage ratings from 600 to 1700 V. Using a device with a higher breakdown voltage than required in the application does not provide increased robustness related to leakage current degradation, compared to using a device with a lower voltage rating.
Ion-Induced Energy Pulse Mechanism for Single-Event Burnout in High-Voltage SiC Power MOSFETs and Junction Barrier Schottky Diodes
2020
Heavy-ion data suggest that a common mechanism is responsible for single-event burnout (SEB) in 1200-V power MOSFETs and junction barrier Schottky (JBS) diodes. Similarly, heavy-ion data suggest a common mechanism is also responsible for leakage current degradation in both devices. This mechanism, based on ion-induced, highly localized energy pulses, is demonstrated in simulations and shown to be capable of causing degradation and SEB for both the MOSFETs and JBS diodes.