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Showing papers on "Silicon carbide published in 2019"


Journal ArticleDOI
TL;DR: In this paper, the spin state of divacancy defects in silicon carbide via mechanical driving is manipulated using a stroboscopic X-ray diffraction imaging technique, which reveals the importance of shear strain for future device engineering and enhanced spin-mechanical coupling.
Abstract: Hybrid spin–mechanical systems provide a platform for integrating quantum registers and transducers. Efficient creation and control of such systems require a comprehensive understanding of the individual spin and mechanical components as well as their mutual interactions. Point defects in silicon carbide (SiC) offer long-lived, optically addressable spin registers in a wafer-scale material with low acoustic losses, making them natural candidates for integration with high-quality-factor mechanical resonators. Here, we show Gaussian focusing of a surface acoustic wave in SiC, characterized using a stroboscopic X-ray diffraction imaging technique, which delivers direct, strain amplitude information at nanoscale spatial resolution. Using ab initio calculations, we provide a more complete picture of spin–strain coupling for various defects in SiC with C3v symmetry. This reveals the importance of shear strain for future device engineering and enhanced spin–mechanical coupling. We demonstrate all-optical detection of acoustic paramagnetic resonance without microwave magnetic fields, relevant for sensing applications. Finally, we show mechanically driven Autler–Townes splittings and magnetically forbidden Rabi oscillations. These results offer a basis for full strain control of three-level spin systems. The authors use surface acoustic waves, focused in a Gaussian geometry, to manipulate the spin state of divacancy defects in silicon carbide via mechanical driving. They demonstrate that shear strain is important in controlling the spin transitions.

186 citations


Journal ArticleDOI
13 Feb 2019-ACS Nano
TL;DR: A graphene hybrid paper with characteristic structure is of great promise as an inorganic TIM for the highly efficient removal of heat from electronic devices.
Abstract: With the increasing integration of devices in electronics fabrication, there are growing demands for thermal interface materials (TIMs) with high through-plane thermal conductivity for efficiently solving thermal management issues. Graphene-based papers consisting of a layer-by-layer stacked architecture have been commercially used as lateral heat spreaders; however, they lack in-depth studies on their TIM applications due to the low through-plane thermal conductivity (<6 W m-1 K-1). In this study, a graphene hybrid paper (GHP) was fabricated by the intercalation of silicon source and the in situ growth of SiC nanorods between graphene sheets based on the carbothermal reduction reaction. Due to the formation of covalent C-Si bonding at the graphene-SiC interface, the GHP possesses a superior through-plane thermal conductivity of 10.9 W m-1 K-1 and can be up to 17.6 W m-1 K-1 under packaging conditions at 75 psi. Compared with the current graphene-based papers, our GHP has the highest through-plane thermal conductivity value. In the TIM performance test, the cooling efficiency of the GHP achieves significant improvement compared to that of state-of-the-art thermal pads. Our GHP with characteristic structure is of great promise as an inorganic TIM for the highly efficient removal of heat from electronic devices.

172 citations


Journal ArticleDOI
TL;DR: In this article, a three-dimensional silicon carbide (SiC) aerogels with a threedimensional architecture and in situ grown SiC nanowires are obtained from natural eggplants by direct graphitization and subsequent carbothermal reduction.

151 citations


01 Jan 2019
TL;DR: Experimental discovery of high thermal conductivity at room temperature in cubic boron arsenide (BAs) grown through a modified chemical vapor transport technique shows that BAs represents a class of ultrahigh–thermal conductivity materials predicted by a recent theory, and that it may constitute a useful thermal management material for high–power density electronic devices.
Abstract: The high density of heat generated in power electronics and optoelectronic devices is a critical bottleneck in their application. New materials with high thermal conductivity are needed to effectively dissipate heat and thereby enable enhanced performance of power controls, solid-state lighting, communication, and security systems. We report the experimental discovery of high thermal conductivity at room temperature in cubic boron arsenide (BAs) grown through a modified chemical vapor transport technique. The thermal conductivity of BAs, 1000 ± 90 watts per meter per kelvin meter-kelvin, is higher than that of silicon carbide by a factor of 3 and is surpassed only by diamond and the basal-plane value of graphite. This work shows that BAs represents a class of ultrahigh-thermal conductivity materials predicted by a recent theory, and that it may constitute a useful thermal management material for high-power density electronic devices.

142 citations


Journal ArticleDOI
01 Dec 2019-Silicon
TL;DR: In this article, an attempt has been made to synthesis Al6061/SiC/WC hybrid aluminium composites using stir casting method under various mass percentage of reinforcement and the mechanical properties such as compressive strength, tensile strength, hardness and wear resistance have been characterized and investigated.
Abstract: In the present study, an attempt has been made to synthesis Al6061/SiC/WC hybrid aluminium composites using stir casting method under various mass percentage of reinforcement. The mechanical properties such as compressive strength, tensile strength, hardness and wear resistance have been characterized and investigated. From the micro structural analysis of hybrid composites, it has been observed that reinforcement particles have been uniformly distributed without clustering of particles in matrix alloy. The precipitate of Mg2Si and un-dissolved Al6 (Fe, Mn) in aluminium solid solution has been observed as interfacial reaction. The hardness of hybrid composites has been increased due to incorporation of stiffer and stronger reinforcement in the matrix material. The presence of SiC and WC reinforcement in the matrix alloy can significantly enhance the compressive, tensile strength and wear resistance of aluminum hybrid composite.

107 citations


Journal ArticleDOI
TL;DR: In this article, a 1MW 3L-ANPC topology was developed to achieve high efficiency and high power density in a hybrid-electric propulsion system, where the switching devices operating at carrier frequency were configured by the emerging silicon carbide (SiC) metaloxide-semiconductor field effect transistors, while the conventional silicon insulated-gate bipolar transistors were selected for switches operating at the fundamental output frequency.
Abstract: A hybrid-electric propulsion system is an enabling technology to make the aircraft more fuel saving, quieter, and lower carbide emission. In this article, a megawatt (MW) scale power inverter based on a three-level active neutral-point-clamped (3L-ANPC) topology will be developed. To achieve high efficiency, the switching devices operating at carrier frequency in the power converter are configured by the emerging silicon carbide (SiC) metal–oxide–semiconductor field-effect transistors, while the conventional silicon (Si) insulated-gate bipolar transistors are selected for switches operating at the fundamental output frequency. To obtain high power density, dc bus voltage is increased from the conventional 270 V to medium voltage of 2.4 kV to reduce cable weight. Also, unlike the traditional 400 Hz dominated aircraft ac systems, the rated fundamental output frequency here is boosted to 1.4 kHz to drive the high-speed motor, which helps further to reduce the motor weight. Main hardware development and control modulation strategies are presented. Experimental results are presented to verify the performance of this MW-scale medium-voltage “SiC+Si” hybrid 3L-ANPC inverter. It is shown that the 1-MW 3L-ANPC inverter can achieve a high efficiency of 99% and a high power density of 12 kVA/kg.

96 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of firing temperature, silicon carbide addition amount, and potash feldspar addition amount on the mullite porous ceramics were systematically investigated, and it was found that increasing the silicon-carbide addition or raising firing temperature was favorable for improving the cold compressive strength and thermal shock resistance of the porous poramics.

84 citations


Journal ArticleDOI
21 Aug 2019-ACS Nano
TL;DR: The experimental results demonstrate that SiC nanomembranes with thicknesses of 230 nm do not experience the hydrolysis process, which creates important opportunities for use of flexible, wide band gap materials as essential components of long-lived neurological and cardiac electrophysiological device interfaces.
Abstract: Implantable electronics are of great interest owing to their capability for real-time and continuous recording of cellular–electrical activity. Nevertheless, as such systems involve direct interfaces with surrounding biofluidic environments, maintaining their long-term sustainable operation, without leakage currents or corrosion, is a daunting challenge. Herein, we present a thin, flexible semiconducting material system that offers attractive attributes in this context. The material consists of crystalline cubic silicon carbide nanomembranes grown on silicon wafers, released and then physically transferred to a final device substrate (e.g., polyimide). The experimental results demonstrate that SiC nanomembranes with thicknesses of 230 nm do not experience the hydrolysis process (i.e., the etching rate is 0 nm/day at 96 °C in phosphate-buffered saline (PBS)). There is no observable water permeability for at least 60 days in PBS at 96 °C and non-Na+ ion diffusion detected at a thickness of 50 nm after being soaked in 1× PBS for 12 days. These properties enable Faradaic interfaces between active electronics and biological tissues, as well as multimodal sensing of temperature, strain, and other properties without the need for additional encapsulating layers. These findings create important opportunities for use of flexible, wide band gap materials as essential components of long-lived neurological and cardiac electrophysiological device interfaces.

82 citations


Journal ArticleDOI
20 Aug 2019
TL;DR: In this article, the authors obtain a high experimental Q factor of 6.3×105, which is 16 times larger than the highest Q among the previously reported values for nanocavities based on crystalline SiC.
Abstract: Photonic nanocavities with high quality (Q) factors are essential components for integrated optical circuits. The use of crystalline silicon carbide (SiC) for such nanocavities enables the realization of devices with superior properties. We fabricate ultrahigh-Q SiC photonic crystal nanocavities by etching air holes into a 4H-SiC slab that is prepared without using hydrogen ion implantation, which usually causes higher absorption losses. In addition, compared to usual designs, a relatively thin slab is utilized to avoid losses through cross-polarized mode coupling induced by the tapered air holes. We obtain a heterostructure nanocavity with a high experimental Q factor of 6.3×105, which is 16 times larger than the highest Q among the previously reported values for nanocavities based on crystalline SiC. We also show that our nanocavity exhibits a high normalized second-harmonic conversion efficiency of 1900%/W.

81 citations


Journal ArticleDOI
TL;DR: A fresh and fundamental mechanism is proposed for the rapid capacity decay of Si-based materials by taking advantage of the high strength and toughness of silicon carbide (SiC), a SiC layer is introduced between the inner silicon and outer carbon layers to inhibit the formation of Li2SiF6.
Abstract: Developing a practical silicon-based (Si-based) anode is a precondition for high-performance lithium-ion batteries. However, the chemical reactivity of the Si renders it liable to be consumed, which must be completely understood for it to be used in practical battery systems. Here, a fresh and fundamental mechanism is proposed for the rapid failure of Si-based materials. Silicon can chemically react with lithium hexafluorophosphate (LiPF6) to constantly generate lithium hexafluorosilicate (Li2SiF6) aggregates during cycling. In addition, nanocarbon coated on silicon acts as a catalyst to accelerate such detrimental reactions. By taking advantage of the high strength and toughness of silicon carbide (SiC), a SiC layer is introduced between the inner silicon and outer carbon layers to inhibit the formation of Li2SiF6. The side reaction rate decreases significantly due to the increase in the activation energy of the reaction. Si@SiC@C maintains a specific capacity of 980 mAh g-1 at a current density of 1 A g-1 after 800 cycles with an initial Coulombic efficiency over 88.5%. This study will contribute to improved design of Si-based anode for high-performance Li-ion batteries.

76 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigate charge state manipulation of individual silicon vacancies in silicon carbide, a system which has recently shown a unique combination of long spin coherence time and ultrastable spin-selective optical transitions.
Abstract: Color centers with long-lived spins are established platforms for quantum sensing and quantum information applications. Color centers exist in different charge states, each of them with distinct optical and spin properties. Application to quantum technology requires the capability to access and stabilize charge states for each specific task. Here, we investigate charge state manipulation of individual silicon vacancies in silicon carbide, a system which has recently shown a unique combination of long spin coherence time and ultrastable spin-selective optical transitions. In particular, we demonstrate charge state switching through the bias applied to the color center in an integrated silicon carbide optoelectronic device. We show that the electronic environment defined by the doping profile and the distribution of other defects in the device plays a key role for charge state control. Our experimental results and numerical modeling evidence that control of these complex interactions can, under certain conditions, enhance the photon emission rate. These findings open the way for deterministic control over the charge state of spin-active color centers for quantum technology and provide novel techniques for monitoring doping profiles and voltage sensing in microscopic devices.

Journal ArticleDOI
TL;DR: In this paper, continuous polypyrrole (PPy) shells were coated on silicon carbide (SiC) nanowires to form core-shell nanostructures, and the thickness of the shells were efficiently tuned through controlling the rate of polymerization.
Abstract: Continuous polypyrrole (PPy) shells were coated on silicon carbide (SiC) nanowires to form core–shell nanostructures, and the thicknesses of the shells were efficiently tuned through controlling the rate of polymerization. Compared with the composites loaded with pure SiC nanowires, the values of e′ and e″ for the composites loaded with PPy@SiC nanowires were strengthened remarkably along with the increased thickness of the shells. The electromagnetic absorption (EA) bandwidths lower than −10 and −20 dB can be monitored in the area of 3.67–18.00 and 4.13–18.00 GHz, when 5 wt % of PPy@SiC nanowires were loaded in the composite. Meanwhile, the effective EA bandwidth can reach 6.88 GHz, and the strongest reflection loss is −58.6 dB.

Journal ArticleDOI
01 Sep 2019
TL;DR: In this paper, the authors show that nanoscale vacuum channel transistors can be fabricated on 150mm silicon carbide wafers using conventional integrated circuit processing technology and show that their drive current scales linearly with the number of emitters on the source pad.
Abstract: Vacuum tubes were central to the early development of electronics, but were replaced, decades ago, by semiconductor transistors. Vacuum channel devices, however, offer inherently faster operation and better noise immunity due to the nature of their channel. They are also stable in harsh environments such as radiation and high temperature. However, to be a plausible alternative to solid-state electronics, nanoscale vacuum channel devices need to be fabricated on the wafer scale using established integrated circuit manufacturing techniques. Here, we show that nanoscale vacuum channel transistors can be fabricated on 150 mm silicon carbide wafers. Our devices have a vertical surround-gate configuration and we show that their drive current scales linearly with the number of emitters on the source pad. The silicon carbide vacuum devices are also compared to identically sized silicon vacuum channel transistors, which reveals that the silicon carbide devices offer superior long-term stability. Nanoscale vacuum channel transistors, which have a vertical surround-gate configuration, can be fabricated on 150 mm silicon carbide wafers using conventional integrated circuit processing technology.

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate the hydrogen gas sensing characteristics of palladium-platinum (Pd-Pt) functionalized silicon carbide (SiC) thin film grown on porous silicon (PSi) substrate for high temperature applications.
Abstract: Present work demonstrates the hydrogen gas (H2) sensing characteristics of palladium-platinum (Pd-Pt) functionalized silicon carbide (SiC) thin film grown on porous silicon (PSi) substrate for high temperature applications. Nano-crystalline SiC thin film was deposited by RF magnetron sputtering on anodized PSi substrate. The loading of discrete ultra-thin Pd-Pt bimetallic catalytic layer was carefully controlled by varying the sputtering parameters. The proposed device architecture (Pd-Pt/SiC/PSi) revealed significant advantages, such as stable high sensing response, large tunable detection range (5–500 ppm), fast response/recovery time, excellent reproducibility, high selectivity, wide operating temperature regime (25–500 °C) and good durability. The observed high response may be ascribed to the combined effect of enhanced catalytic activity of bimetallic Pd-Pt layer and increased surface area of the proposed sensor.

Journal ArticleDOI
TL;DR: The results verify the features of SiC 3L-NPC inverter, the corresponding modulation technique used and their effects on reducing and improving power loss in solar SiC photovoltaic inverters.
Abstract: This paper presents the power loss model analysis and efficiency of three-level neutral-point-clamped (3L-NPC) inverter that is widely employed in solar photovoltaic energy conversion system. A silicon carbide (SiC) 3L-NPC inverter is developed in this paper by employing wide bandgap semiconductor power devices, such as SiC MOSFET and SiC diode (SiC D). These devices are used due to their superior characteristics over silicon (Si) semiconductor devices for the reduction of inverter power losses, and as a result, an improving efficiency at the high switching frequency. Accurate and detailed power loss calculation formula and power loss distribution over switching devices of the SiC 3L-NPC inverter are derived according to the modulation technique and inverter operation. The switching energy loss of SiC MOSFET is then measured and determined experimentally via inductive clamp double pulse test (DPT) at the real working condition of the circuit. Afterward, this experimental data is used in the thermal description file of the device’s library of PLECS simulation software to determine the total power loss of SiC 3L-NPC inverter. The developed simulation model replicates the real operating conditions of the 3L-NPC inverter. This method gives results close to the practical test. Finally, the power loss of SiC 3L-NPC inverter is measured and compared with the theoretical results. Furthermore, SiC MOSFET and SiC D are employed to achieve high system efficiency at the high switching frequency. The results verify the features of SiC 3L-NPC inverter, the corresponding modulation technique used and their effects on reducing and improving power loss in solar SiC photovoltaic inverters.

Journal ArticleDOI
TL;DR: In this paper, defects in silicon carbide have been explored as promising spin systems in quantum technologies, and for practical quantum metrology and quantum communication, it is critical to achieve on-dem...
Abstract: Defects in silicon carbide have been explored as promising spin systems in quantum technologies. However, for practical quantum metrology and quantum communication, it is critical to achieve on-dem...

Journal ArticleDOI
TL;DR: It is reported that the piezoresistance coefficient of SiC NW is 17 times that of its bulk counterparts, which provides new insights to develop high performance SiC devices, to help avoid catastrophic failure when working in harsh environments.
Abstract: Reports reveal that the piezoresistance coefficients of silicon carbide (SiC) nanowires (NWs) are 2 to 4 times smaller than those of their corresponding bulk counterparts. It is a challenge to eliminate contamination in adhering NWs onto substrates. In this study, a new setup was developed, in which NWs were manipulated and fixed by a goat hair and conductive silver epoxy in air, respectively, in the absence of any depositions. The goat hair was not consumed during manipulation of the NWs. The process took advantage of the stiffness and tapered tip of the goat hair, which is unlike the loss issue of beam sources in depositions. With the new fixing method, in situ transmission electron microscopy (TEM) electromechanical coupling measurements were performed on pristine SiC NWs. The piezoresistance coefficient and carrier mobility of SiC NW are -94.78 × 10-11 Pa-1 and 30.05 cm2 V-1 s-1, respectively, which are 82 and 527 times respectively greater than those of SiC NWs reported previously. We, for the first time, report that the piezoresistance coefficient of SiC NW is 17 times those of its bulk counterparts. These findings provide new insights to develop high performance SiC devices and to help avoid catastrophic failure when working in harsh environments.

Journal ArticleDOI
TL;DR: In this article, the effects of FexSiy phases on SiC porous ceramics were investigated, and the possibility of the FExSiy as a reinforcement for SiC porosity was confirmed, while the results showed that when a small amount of Fe2O3 was added, the cold compressive strength reached 8.8 MPa.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated ultrasonic elliptical vibration-assisted diamond cutting of reaction-bonded silicon carbide (RB-SiC) by using finite element simulations and corresponding experimental validations.

Journal ArticleDOI
TL;DR: In this article, a net-like amorphous carbon-coated silicon carbide coaxial nanocables (SiC@C NCs), which had low density and excellent physicochemical stability, was successfully fabricated according to the hydrothermal-carbonization strategy.
Abstract: In this study, a practical lightweight and broadband microwave absorber, namely, the net-like amorphous carbon-coated silicon carbide coaxial nanocables (SiC@C NCs), which had low density and excellent physicochemical stability, was successfully fabricated according to the hydrothermal-carbonization strategy. Typically, the microwave absorption performance exhibited broad effective absorption bandwidth (EAB) of up to 7.2 GHz (9.12–16.32 GHz) at a small matching thickness of 2.58 mm. Meanwhile, the minimal reflection loss (RL) value of −51.53 dB with the corresponding EAB across the whole Ku-band (11.68–18 GHz) appeared at 2.08 mm, which suggested that, the as-prepared SiC@C NCs displayed extensive application prospects as a superior lightweight and broadband microwave absorber. Moreover, the systematic characterization results indicated that, the superior microwave absorption performance was ascribed to the interfacial polarization and multiple reflections on the heterogeneous interface between the SiC nanowires (SiC NWs) core and the amorphous carbon shell, together with the electron polarization and Debye dipolar relaxation resulted from the stacking faults of SiC NWs core, and the abundant defect and disorder within the amorphous carbon shell.

Journal ArticleDOI
TL;DR: A photo-electrical detection technique for electron spins of silicon vacancy ensembles in the 4H polytype of silicon carbide (SiC) is demonstrated, proving that this electrical readout technique enables detection of coherent spin motion.
Abstract: Quantum technology relies on proper hardware, enabling coherent quantum state control as well as efficient quantum state readout. In this regard, wide-bandgap semiconductors are an emerging material platform with scalable wafer fabrication methods, hosting several promising spin-active point defects. Conventional readout protocols for defect spins rely on fluorescence detection and are limited by a low photon collection efficiency. Here, we demonstrate a photo-electrical detection technique for electron spins of silicon vacancy ensembles in the 4H polytype of silicon carbide (SiC). Further, we show coherent spin state control, proving that this electrical readout technique enables detection of coherent spin motion. Our readout works at ambient conditions, while other electrical readout approaches are often limited to low temperatures or high magnetic fields. Considering the excellent maturity of SiC electronics with the outstanding coherence properties of SiC defects, the approach presented here holds promises for scalability of future SiC quantum devices. The efficiency of quantum state readout is one of the factors that determine the performance of point defects in semiconductors in practical applications. Here the authors demonstrate photo-electrical readout for silicon vacancies in silicon carbide, providing an alternative to optical detection.

Journal ArticleDOI
04 Jun 2019-ACS Nano
TL;DR: In this study, NWs were manipulated using a weasel hair and fixed by conductive silver epoxy, eliminating the contaminations and damages induced by conventional beam depositions, and self-healing of mismatched fractured amorphous surfaces of brittle NWs was discovered.
Abstract: Nanowires (NWs) have been envisioned as building blocks of nanotechnology and nanodevices. In this study, NWs were manipulated using a weasel hair and fixed by conductive silver epoxy, eliminating ...

Journal ArticleDOI
TL;DR: In this article, single-abrasive scratch tests were designed and conducted in two typical cutting directions, and the results showed that the grinding parameters (feed rate, spindle speed, depth of cut, and cutting direction) have significant influences on the grinding forces, surface integrity, and affected subsurface region.

Journal ArticleDOI
TL;DR: The thermal properties of two-dimensional silicon carbide are explored using reverse non-equilibrium molecular dynamics simulation to provide a means for better understating as well as designing the efficient thermal management of 2D-SiC based electronics and optoelectronics in near future.
Abstract: Recently, two-dimensional silicon carbide (2D-SiC) has attracted considerable interest due to its exotic electronic and optical properties. Here, we explore the thermal properties of 2D-SiC using reverse non-equilibrium molecular dynamics simulation. At room temperature, a thermal conductivity of ∼313 W mK-1 is obtained for 2D-SiC which is one order higher than that of silicene. Above room temperature, the thermal conductivity deviates the normal 1/T law and shows an anomalous slowly decreasing behavior. To elucidate the variation of thermal conductivity, the phonon modes at different length and temperature are quantified using Fourier transform of the velocity auto-correlation of atoms. The calculated phonon density of states at high temperature shows a shrinking and softening of the peaks, which induces the anomaly in the thermal conductivity. On the other hand, quantum corrections are applied to avoid the freezing effects of phonon modes on the thermal conductivity at low temperature. In addition, the effect of potential on the thermal conductivity calculation is also studied by employing original and optimized Tersoff potentials. These findings provide a means for better understating as well as designing the efficient thermal management of 2D-SiC based electronics and optoelectronics in near future.

Journal ArticleDOI
TL;DR: In this paper, a combined theoretical, numerical and experimental investigation of the integrated thermal protection system based on C/SiC composite corrugated core sandwich plane structure was conducted, which was made from carbon fiber reinforced silicon carbide composite by a hot compression molding combined with precursor infiltration and pyrolysis method.

Journal ArticleDOI
TL;DR: In this article, the effect of Si addition on the microstructures of the laser-sintered green part, carbon preform and derived carbon fiber reinforced silicon carbide (Cf/SiC) composite was investigated.

Journal ArticleDOI
TL;DR: In this article, the authors used the MSD (Mean Square Displacement) method to describe the diffusion process between the workpiece atoms in the silicon carbide more accurately.

Journal ArticleDOI
TL;DR: A SiC-on-insulator platform based on crystalline 4H-SiC is reported on and engineerable dispersion from normal to anomalous dispersion is shown by controlling the waveguide cross-sectional dimension, which paves the way toward nonlinear applications in SiC microring resonators.
Abstract: Silicon carbide (SiC) exhibits promising material properties for nonlinear integrated optics. We report on a SiC-on-insulator platform based on crystalline 4H-SiC and demonstrate high-confinement SiC microring resonators with sub-micron waveguide cross-sectional dimensions. The Q factor of SiC microring resonators in such a sub-micron waveguide dimension is improved by a factor of six after surface roughness reduction by applying a wet oxidation process. We achieve a high Q factor (73,000) for such devices and show engineerable dispersion from normal to anomalous dispersion by controlling the waveguide cross-sectional dimension, which paves the way toward nonlinear applications in SiC microring resonators.

Journal ArticleDOI
TL;DR: In this paper, the structural, electrical and electronic properties of (PVA-TiO2-SiC) nanocomposites for antibacterial application have been investigated with low cost, low weight and high activity.
Abstract: The structural, electrical and electronic properties of (PVA–TiO2-SiC) nanocomposites for antibacterial application have been investigated with low cost, low weight and high activity for antibacterial. The (PVA–TiO2-SiC) nanocomposites were prepared with different concentrations of (PVA–TiO2) nanocomposites and silicon carbide (SiC) nanoparticles. The casting method was used to prepare the (PVA–TiO2-SiC) nanocomposites. The silicon carbide nanoparticles were added to the (PVA–TiO2) nanocomposites with concentrations (x) are (1.5, 3,4.5 and 6) wt.%. The electrical properties of (PVA–TiO2-SiC) nanocomposites were studied at different temperatures. The results showed that the SiC nanoparticles form a paths network inside the (PVA–TiO2) nanocomposites at concentrations (4.5 and 6) wt.%. The conductivity (PVA–TiO2-SiC) nanocomposites is increased with increase of silicon carbide (SiC) nanoparticles concentrations from 4×10-11 (Ω. cm)-1 to 7.4×10-11 (Ω. cm)-1. The activation energy of (PVA-TiO2-SiC) nanocomposites decreases with the increase of silicon carbide nanoparticles concentrations from (0.76 eV) to (0.703 eV) when the silicon carbide nanoparticles concentrations increase from (0-6) wt.%.. The total energies of the (PVA–TiO2-SiC) nanocomposites were studied by using Gaussian 09(G09) program and density functional theory (DFT) with B3LYP/6-31G) basis set. The total energies decrease with increase the number of atoms. The (PVA–TiO2-SiC) nanocomposites tested for antibacterial applications against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) by using a disc diffusion method. The results showed that the prepared nanocomposites have good antibacterial activity.

Journal ArticleDOI
TL;DR: In this article, the structural, electronic and D.C electrical properties of PVA-MgO-SiC nanocomposites for antibacterial application have been investigated.
Abstract: The structural, electronic and D.C electrical properties of,(PVA-MgO-SiC) nanocomposites for antibacterial application have been investigated. The prepared nanocomposites have low cost, flexible and high antibacterial activity. The (PVA-MgO-SiC),nanocomposites were prepared with different weight percentages of Silicon Carbide (SiC),nanoparticles., Electrical properties of ,(PVA-MgO-SiC) nanocomposites were studied with different temperature. The experimental results showed that the conductivity of (PVA-MgO-SiC),nanocomposites is increased with increase the concentration of Silicon Carbide (SiC) nanoparticles. The activation energy of,(PVA-MgO-SiC) nanocomposites decreases with increase the weight percentages of Silicon Carbide nanoparticles. The total energies of the (PVA–MgO-SiC) nanocomposites were studied by using Gaussian 09(G09) program and density functional theory (DFT) with B3LYP/6-31G) basis set. The total energies decreases with the increase the number of atoms forming the nanocomposites,.