Showing papers on "Silicon carbide published in 2016"

GaN Technology for Power Electronic Applications: A Review

Abstract: Power semiconductor devices based on silicon (Si) are quickly approaching their limits, set by fundamental material properties. In order to address these limitations, new materials for use in devices must be investigated. Wide bandgap materials, such as silicon carbide (SiC) and gallium nitride (GaN) have suitable properties for power electronic applications; however, fabrication of practical devices from these materials may be challenging. SiC technology has matured to point of commercialized devices, whereas GaN requires further research to realize full material potential. This review covers fundamental material properties of GaN as they relate to Si and SiC. This is followed by a discussion of the contemporary issues involved with bulk GaN substrates and their fabrication and a brief overview of how devices are fabricated, both on native GaN substrate material and non-native substrate material. An overview of current device structures, which are being analyzed for use in power switching applications, is then provided; both vertical and lateral device structures are considered. Finally, a brief discussion of prototypes currently employing GaN devices is given.

Temperature-Dependent Short-Circuit Capability of Silicon Carbide Power MOSFETs

Abstract: This paper presents a comprehensive short-circuit ruggedness evaluation and numerical investigation of up-to-date commercial silicon carbide (SiC) MOSFETs. The short-circuit capability of three types of commercial 1200-V SiC MOSFETs is tested under various conditions, with case temperatures from 25 to 200 °C and dc bus voltages from 400 to 750 V. It is found that the commercial SiC MOSFETs can withstand short-circuit current for only several microseconds with a dc bus voltage of 750 V and case temperature of 200 °C. The experimental short-circuit behaviors are compared, and analyzed through numerical thermal dynamic simulation. Specifically, an electrothermal model is built to estimate the device internal temperature distribution, considering the temperature-dependent thermal properties of SiC material. Based on the temperature information, a leakage current model is derived to calculate the main leakage current components (i.e., thermal, diffusion, and avalanche generation currents). Numerical results show that the short-circuit failure mechanisms of SiC MOSFETs can be thermal generation current induced thermal runaway or high-temperature-related gate oxide damage.

Hierarchical graphene/SiC nanowire networks in polymer-derived ceramics with enhanced electromagnetic wave absorbing capability

Abstract: A high-performance electromagnetic wave absorbing composite based on graphene and polysiloxane-derived SiOC ceramic is realized via the polymer pyrolysis process. Hierarchical architecture consisting of two-dimensional graphene and one-dimensional SiC nanowire in ceramic matrix is achieved owing to the heterogeneous nucleation of SiC nanowires promoted by graphene at lower temperature. The dielectric and microwave absorption properties of the composites were studied at 293–673 K. When graphene oxide loading is 3 wt%, the composite attains a minimum reflection loss value of −69.3 dB at 10.55 GHz with a thickness of 2.35 mm. With the increase of temperature, the composite exhibits better absorbing performance that the effective absorption bandwidth reaches 3.9 GHz at 673 K. The hierarchical networks with graphene/SiC nanowires achieved in SiOC matrix provide a feasible process for the realization of efficient electromagnetic wave absorption in ceramic-based composites at high temperature.

Graphene growth on silicon carbide: A review

Abstract: Graphene has been widely heralded over the last decade as one of the most promising nanomaterials for integrated, miniaturized applications spanning from nanoelectronics, interconnections, thermal management, sensing, to optoelectronics. Graphene grown on silicon carbide is currently the most likely candidate to fulfill this promise. As a matter of fact, the capability to synthesize high-quality graphene over large areas using processes and substrates compatible as much as possible with the well-established semiconductor manufacturing technologies is one crucial requirement. We review here, the enormous scientific and technological advances achieved in terms of epitaxial growth of graphene from thermal decomposition of bulk silicon carbide and the fine control of the graphene electronic properties through intercalation. Finally, we discuss perspectives on epitaxial graphene growth from silicon carbide on silicon, a particularly challenging area that could result in maximum benefit for the integration of graphene with silicon technologies.

A Comprehensive Study of Short-Circuit Ruggedness of Silicon Carbide Power MOSFETs

Abstract: The behavior of silicon carbide (SiC) power MOSFETs under stressful short-circuit (SC) conditions is investigated in this paper. Two different SC failure phenomena for SiC power MOSFETs are thoroughly reported. Experimental evidence and TCAD electrothermal simulations are exploited to describe and discriminate the failure sources. Physical causes are finally investigated and explained by means of properly calibrated numerical investigations and are reported along with their effects on devices’ SC capability.

Interfacial Engineering of Silicon Carbide Nanowire/Cellulose Microcrystal Paper toward High Thermal Conductivity

Abstract: Polymer composites with high thermal conductivity have attracted much attention, along with the rapid development of electronic devices toward higher speed and better performance However, high interfacial thermal resistance between fillers and matrix or between fillers and fillers has been one of the primary bottlenecks for the effective thermal conduction in polymer composites Herein, we report on engineering interfacial structure of silicon carbide nanowire/cellulose microcrystal paper by generating silver nanostructures We show that silver nanoparticle-deposited silicon carbide nanowires as fillers can effectively enhance the thermal conductivity of the matrix The in-plane thermal conductivity of the resultant composite paper reaches as high as 340 W/m K, which is one order magnitude higher than that of conventional polymer composites Fitting the measured thermal conductivity with theoretical models qualitatively demonstrates that silver nanoparticles bring the lower interfacial thermal resistanc

Overview of Silicon Carbide Technology: Device, Converter, System, and Application

Abstract: This paper overviews the silicon carbide (SiC) technology. The focus is on the benefits of SiC based power electronics for converters and systems, as well as their ability in enabling new applications. The challenges and research trends on the design and application of SiC power electronics are also discussed

All-Optical dc Nanotesla Magnetometry Using Silicon Vacancy Fine Structure in Isotopically Purified Silicon Carbide

Abstract: Sensing magnetic fields is a key aspect in many areas of study such as biomedical imaging and geophysics. Researchers demonstrate all-optical solid-state magnetometry that is sensitive to magnetic fields weaker than 100 nT.

Tribological performance under dry sliding conditions of graphene/silicon carbide composites

Abstract: The role played by graphene in the friction and wear behaviour of graphene/silicon carbide (SiC) composites, tested under dry sliding conditions and using silicon nitride balls as counterbodies, is investigated as a function of the graphene nanoplatelets (GNPs) content and the graphene source. GNPs composites show an enhanced wear resistance as compared to monolithic SiC, with maximum improvements of ∼70% for the material containing up to 20 vol.% of GNPs; whereas the friction performance depends on the sliding distance and GNPs content. The analysis of the wear debris by micro-Raman spectroscopy evidenced that the tribological behaviour of the GNPs/SiC materials is linked to the formation of an adhered lubricating and protecting tribofilm. Multilayered graphene fillers participate more actively in the protecting tribofilm than other graphene sources such as reduced graphene oxide or in-situ grown graphene flakes.

A new approach for fabrications of SiC based photodetectors

Abstract: We report on a new approach to quickly synthesize high-quality single crystalline wide band gap silicon carbide (SiC) films for development of high-performance deep ultraviolet (UV) photodetectors. The fabricated SiC based UV photodetectors exhibited high response while maintaining cost-effectiveness and size miniaturization. Focus of the experiments was on studies of electrical and electronic properties, as well as responsivity, response and recovery times, and repeatability of the deep UV photodetectors. Raman scattering spectroscopy and scanning electron microscope (SEM) were used to characterize the SiC materials. Analyses of the SEM data indicated that highly flat SiC thin films have been obtained. Based on the synthesized SiC, deep UV detectors are designed, fabricated, and tested with various UV wavelength lights at different radiation intensities. Temperature effect and bias effect on the photocurrent strength and signal-to-noise ratio, humidity effect on the response time and recovery time of the fabricated detectors have been carefully characterized and discussed. The detectors appear to have a very stable baseline and repeatability. The obtained responsivity is more than 40% higher compared to commercial detectors. The good performance of the photodetectors at operating temperature up to 300 °C remains nearly unchanged.

Silicon carbide foam as a porous support platform for catalytic applications

Abstract: This review provides an overview of the use of foam-structured SiC as a porous support platform in some typical catalytic processes both for gas-phase and liquid-phase reactions, such as H2S selective oxidation, Friedel–Crafts benzoylation and Fischer–Tropsch synthesis, where traditional catalysts have shown their weaknesses. The macroscopic thermally conductive SiC material could be efficiently employed as a support for controlling the active phase, i.e. metal and zeolite, and anchoring the powder-foam nanocarbons in the field of catalysis. In light of the results, one can state that silicon carbide foam could be regarded as an ideal alternative support, which provides a great enhancement of both the catalytic performance and the catalytic stability compared to that of the traditional catalysts, in several gas- and liquid-phase catalytic processes.

Flash Spark Plasma Sintering (FSPS) of α and β SiC

Abstract: A novel processing methodology that allows combined preheating and Flash-SPS (FSPS) of silicon carbide-based materials has been developed. Beta-SiC (+10 wt% B4C) powders were densified (Ф 20 mm) up to 96% of their theoretical density in 17 s under an applied pressure of 16 MPa (5 kN). The flash event was attributed to the sharp positive temperature dependence of the electrical conductivity (thermal runaway) of SiC, and a sudden increase in electric power absorption (Joule heating) of the samples after a sufficient preheating temperature (>600°C) was reached. The microstructural evolution was analyzed by examining materials densified by FSPS in the range of 82%–96% theoretical densities. FEM modeling results suggest that the FSPS heating rate was of the order of 8800°C/min. A comparative analysis was done between FSPS and reference samples (sintered using conventional SPS in the temperature range of 1800°C–2300°C). This allowed for a better understanding of the temperatures generated during FSPS, and in turn the sintering mechanisms. We also demonstrated the scalability of the FSPS process by consolidating a large α-SiC disk (Ф 60 mm) in about 60 s inside a hybrid SPS furnace equipped with an induction heater, which allowed us to achieve sufficient preheating (1600°C) of the material to achieve FSPS.

Silicon vacancy center in 4 H -SiC: Electronic structure and spin-photon interfaces

Abstract: Defects in silicon carbide are of intense and increasing interest for quantum-based applications due to this material's properties and technological maturity. We calculate the multiparticle symmetry-adapted wave functions of the negatively charged silicon vacancy defect in hexagonal silicon carbide via use of group theory and density functional theory and find the effects of spin-orbit and spin-spin interactions on these states. Although we focused on ${\text{V}}_{\mathrm{Si}}^{\ensuremath{-}}$ in $4H$-SiC because of its unique fine structure due to the odd number of active electrons, our methods can be easily applied to other defect centers of different polytypes, especially to the $6H$-SiC. Based on these results, we identify the mechanism that polarizes the spin under optical drive, obtain the ordering of its dark doublet states, point out a path for electric field or strain sensing, and find the theoretical value of its ground-state zero-field splitting to be 68 MHz, in good agreement with experiment. Moreover, we present two distinct protocols of a spin-photon interface based on this defect. Our results pave the way toward quantum information and quantum metrology applications with silicon carbide.

Optical thermometry based on level anticrossing in silicon carbide.

Abstract: We report a giant thermal shift of 2.1 MHz/K related to the excited-state zero-field splitting in the silicon vacancy centers in 4H silicon carbide. It is obtained from the indirect observation of the optically detected magnetic resonance in the excited state using the ground state as an ancilla. Alternatively, relative variations of the zero-field splitting for small temperature differences can be detected without application of radiofrequency fields, by simply monitoring the photoluminescence intensity in the vicinity of the level anticrossing. This effect results in an all-optical thermometry technique with temperature sensitivity of 100 mK/Hz1/2 for a detection volume of approximately 10−6 mm3. In contrast, the zero-field splitting in the ground state does not reveal detectable temperature shift. Using these properties, an integrated magnetic field and temperature sensor can be implemented on the same center.

Method for analyzing passive silicon carbide thermometry with a continuous dilatometer to determine irradiation temperature

Abstract: Silicon carbide is used as a passive post-irradiation temperature monitor because the irradiation defects will anneal out above the irradiation temperature. The irradiation temperature is determined by measuring a property change after isochronal annealing, i.e., lattice spacing, dimensions, electrical resistivity, thermal diffusivity, or bulk density. However, such methods are time-consuming since the steps involved must be performed in a serial manner. This work presents the use of thermal expansion from continuous dilatometry to calculate the SiC irradiation temperature, which is an automated process requiring minimal setup time. Analysis software was written that performs the calculations to obtain the irradiation temperature and removes possible user-introduced error while standardizing the analysis. This method has been compared to an electrical resistivity and isochronal annealing investigation, and the results revealed agreement of the calculated temperatures. These results show that dilatometry is a reliable and less time-intensive process for determining irradiation temperature from passive SiC thermometry.

Mesoporous silicon carbide nanofibers with in situ embedded carbon for co-catalyst free photocatalytic hydrogen production

Abstract: Silicon carbide (SiC) has been considered a promising metal-free photocatalyst due to its unique photoelectrical properties and thermal/chemical stability. However, its performance suffers from the fast recombination of charge carriers. Herein, we report mesoporous SiC nanofibers with in situ embedded graphitic carbon (SiC NFs-Cx) synthesized via a one-step carbothermal reduction between electrospun carbon nanofibers and Si powders. In the absence of a noble metal co-catalyst, the hydrogen evolution efficiency of SiC NFs-Cx is significantly improved under both simulated solar light (180.2 μmol·g–1·h–1) and visible light irradiation (31.0 μmol·g–1·h–1) in high-pH solution. The efficient simultaneous separation of charge carriers plays a critical role in the high photocatalytic activity. The embedded carbon can swiftly transfer the photogenerated electrons and improve light absorption, whereas the additional hydroxyl anions (OH–) in highpH solution can accelerate the trapping of holes. Our results demonstrate that the production of SiC NFs-Cx, which contains exclusively earth-abundant elements, scaled up, and is environmentally friendly, has great potential for practical applications. This work may provide a new pathway for designing stable, lowcost, high efficiency, and co-catalyst-free photocatalysts.

Design Considerations and Performance Evaluation of 1200-V 100-A SiC MOSFET-Based Two-Level Voltage Source Converter

Abstract: Silicon carbide (SiC) MOSFET is capable of achieving better efficiency and better power density of power converters due to its low on-state resistance and lower switching losses compared to silicon (Si) Insulated Gate Bipolar Transistor. Operation of power converters at higher switching frequency using SiC devices allows reduction in filter size and hence improves the power to weight ratio of the converter. This paper presents switching characterization of 1200-V 100-A SiC MOSFET module and compares the efficiency of a two-level voltage source converter (2L-VSC) using SiC MOSFETs and Si IGBTs. Also, various design considerations of the 1200-V 100-A SiC MOSFET-based 2L-VSC including gate drive design, bus bar packaging, and thermal management have been elaborated. The designed and developed 2L-VSC is operated to supply 35 kVA load at 20-kHz switching frequency with dc bus voltage of 800 V and the corresponding experimental results are presented.

Gate and Base Drivers for Silicon Carbide Power Transistors: An Overview

Abstract: Silicon carbide (SiC) power transistors have started gaining significant importance in various application areas of power electronics. During the last decade, SiC power transistors were counted not only as a potential, but also more importantly as an alternative to silicon counterparts in applications where high efficiency, high switching frequencies, and operation at elevated temperatures are targeted. Various SiC device designs have been proposed and excessive investigations in terms of simulation and experimental studies have shown their advantageous performance compared to silicon technology. On a system-level, however, the design of gate and base drivers for SiC power transistors is very challenging. In particular, a sophisticated driver design is not only associated with properly switching the transistor and decreasing the switching power losses, but also it must incorporate protection features, as well as comply with the electromagnetic compatibility. This paper shows an overview of the gate and base drivers for SiC power transistors which have been proposed by several highly qualified scientists. In particular, the basic operating principle of each driver along with their applicability and drawbacks are presented. For this overview, the three most successful SiC power transistors are considered: junction-field-effect transistors, bipolar-junction transistors, and metal-oxide-semiconductor field-effect transistors. Last but not least, future challenges on gate and base drivers design are also presented.

Ultralight, strong, three-dimensional SiC structures

Abstract: Ultralight and strong three-dimensional (3D) silicon carbide (SiC) structures have been generated by the carbothermal reduction of SiO with a graphene foam (GF). The resulting SiC foams have an average height of 2 mm and density ranging between 9 and 17 mg cm(-3). They are the lightest reported SiC structures. They consist of hollow struts made from ultrathin SiC flakes and long 1D SiC nanowires growing from the trusses, edges, and defect sites between layers. AFM results revealed an average flake thickness of 2-3 nm and lateral size of 2 μm. In-situ compression tests in the scanning electron microscope (SEM) show that, compared with most of the existing lightweight foams, the present 3D SiC exhibited superior compression strengths and significant recovery after compression strains of about 70%.

The effect of carbide particle additives on rheology of shear thickening fluids

Abstract: In this paper, shear thickening fluids (STFs) including silicon carbide particles are presented. We fabricated a kind of STF based on nanosize fumed silica suspended in a liquid medium, polyethylene glycol, at a constant concentration of 20 wt.%. Then, different particle size silicon carbide (SiC) particles were added to the STF with various amounts. Their rheological properties under various temperatures were tested by using a rheometer. The suspension exhibits different systematic variations with respect to the varied parameters.

Bright and photostable single-photon emitter in silicon carbide

Abstract: Single-photon sources are of paramount importance in quantum communication, quantum computation, and quantum metrology. In particular, there is great interest in realizing scalable solid-state platforms that can emit triggered photons on demand to achieve scalable nanophotonic networks. We report on a visible-spectrum single-photon emitter in 4H silicon carbide (SiC). The emitter is photostable at room and low temperatures, enabling photon counts per second in excess of 2×106 from unpatterned bulk SiC. It exists in two orthogonally polarized states, which have parallel absorption and emission dipole orientations. Low-temperature measurements reveal a narrow zero phonon line (linewidth 30% of the total photoluminescence spectrum.