Showing papers on "Silicon carbide published in 2022"

Vertically Aligned Silicon Carbide Nanowires/Boron Nitride Cellulose Aerogel Networks Enhanced Thermal Conductivity and Electromagnetic Absorbing of Epoxy Composites

Abstract: With the innovation of microelectronics technology, the heat dissipation problem inside the device will face a severe test. In this work, cellulose aerogel (CA) with highly enhanced thermal conductivity (TC) in vertical planes was successfully obtained by constructing a vertically aligned silicon carbide nanowires (SiC NWs)/boron nitride (BN) network via the ice template-assisted strategy. The unique network structure of SiC NWs connected to BN ensures that the TC of the composite in the vertical direction reaches 2.21 W m-1 K-1 at a low hybrid filler loading of 16.69 wt%, which was increased by 890% compared to pure epoxy (EP). In addition, relying on unique porous network structure of CA, EP-based composite also showed higher TC than other comparative samples in the horizontal direction. Meanwhile, the composite exhibits good electrically insulating with a volume electrical resistivity about 2.35 × 1011 Ω cm and displays excellent electromagnetic wave absorption performance with a minimum reflection loss of - 21.5 dB and a wide effective absorption bandwidth (< - 10 dB) from 8.8 to 11.6 GHz. Therefore, this work provides a new strategy for manufacturing polymer-based composites with excellent multifunctional performances in microelectronic packaging applications.

Vertically Aligned Silicon Carbide Nanowires/Boron Nitride Cellulose Aerogel Networks Enhanced Thermal Conductivity and Electromagnetic Absorbing of Epoxy Composites

Abstract: With the innovation of microelectronics technology, the heat dissipation problem inside the device will face a severe test. In this work, cellulose aerogel (CA) with highly enhanced thermal conductivity (TC) in vertical planes was successfully obtained by constructing a vertically aligned silicon carbide nanowires (SiC NWs)/boron nitride (BN) network via the ice template-assisted strategy. The unique network structure of SiC NWs connected to BN ensures that the TC of the composite in the vertical direction reaches 2.21 W m-1 K-1 at a low hybrid filler loading of 16.69 wt%, which was increased by 890% compared to pure epoxy (EP). In addition, relying on unique porous network structure of CA, EP-based composite also showed higher TC than other comparative samples in the horizontal direction. Meanwhile, the composite exhibits good electrically insulating with a volume electrical resistivity about 2.35 × 1011 Ω cm and displays excellent electromagnetic wave absorption performance with a minimum reflection loss of - 21.5 dB and a wide effective absorption bandwidth (< - 10 dB) from 8.8 to 11.6 GHz. Therefore, this work provides a new strategy for manufacturing polymer-based composites with excellent multifunctional performances in microelectronic packaging applications.

Processing of Aluminium-Silicon Alloy with Metal Carbide as Reinforcement through Powder-Based Additive Manufacturing: A Critical Study

Abstract: Powder-based additive manufacturing (PAM) is a potential fabrication approach in advancing state-of-the-art research to produce intricate components with high precision and accuracy in near-net form. In PAM, the raw materials are used in powder form, deposited on the surface layer by layer, and fused to produce the final product. PAM composite fabrication for biomedical implants, aircraft structure panels, and automotive brake rotary components is gaining popularity. In PAM composite fabrication, the aluminium cast alloy is widely preferred as a metal matrix for its unique properties, and different reinforcements are employed in the form of oxides, carbides, and nitrides. However, for enhancing the mechanical properties, the carbide form is predominantly considered. This comprehensive study focuses on contemporary research and reveals the effect of metal carbide's (MCs) addition to the aluminium matrix processed through various PAM processes, challenges involved, and potential scopes to advance the research.

Integrated silicon carbide electro-optic modulator

Abstract: Owing to its attractive optical and electronic properties, silicon carbide is an emerging platform for integrated photonics. However an integral component of the platform is missing-an electro-optic modulator, a device which encodes electrical signals onto light. As a non-centrosymmetric crystal, silicon carbide exhibits the Pockels effect, yet a modulator has not been realized since the discovery of this effect more than three decades ago. Here we design, fabricate, and demonstrate a Pockels modulator in silicon carbide. Specifically, we realize a waveguide-integrated, small form-factor, gigahertz-bandwidth modulator that operates using complementary metal-oxide-semiconductor (CMOS)-level voltages on a thin film of silicon carbide on insulator. Our device is fabricated using a CMOS foundry compatible fabrication process and features no signal degradation, no presence of photorefractive effects, and stable operation at high optical intensities (913 kW/mm2), allowing for high optical signal-to-noise ratios for modern communications. Our work unites Pockels electro-optics with a CMOS foundry compatible platform in silicon carbide.

Anisotropic Charge Transport Enabling High‐Throughput and High‐Aspect‐Ratio Wet Etching of Silicon Carbide

Abstract: Wet etching of silicon carbide typically exhibits poor etching efficiency and low aspect ratio. In this study, an etching structure that exploits anisotropic charge carrier flow to enable high‐throughput, external‐bias‐free wet etching of high‐aspect‐ratio SiC micro/nano‐structures is demonstrated. Specifically, by applying a catalytic metal coating at the bottom surface of a SiC wafer while introducing patterned ultraviolet light illumination from its top surface, spatial charge separation across the wafer is achieved, i.e., photogenerated electrons are channeled to the bottom to participate in the reduction reaction of an oxidant in the etchant solution, while holes flow to the top to trigger oxidation of SiC and subsequent etching. Such design largely suppresses recombination‐induced charge losses, and when used in combination with a top metal catalyst mask, the structure yields a remarkable vertical etching rate of 0.737 µm min−1 and an aspect ratio of 3.2, setting new records for wet‐etching methods for SiC.

Optimizing WEDM Parameters on Nano-SiC-Gr Reinforced Aluminum Composites Using RSM

Abstract: Nanocomposites are preferred for performance enhancement over micron composites because of their better performance in enhancing the desired properties of the parent material. Nano-silicon carbide and nano-graphite are considered together for reinforcement of Al7075 in this piece of research. Here, the purpose of reinforcement of graphite considered is to improve machinability. The stir casting was employed for fabrication of nanocomposite. The composite matrix includes Al7075 matrix material, reinforcement material of nano-SiC (5 wt.%), and nano-graphite (5 wt.%). Wire cut Electrical Discharge Machining (WEDM) of the synthesized nanocomposite SiC/Gr/Al7075 is considered for investigating the machinability. The objectives of the study are to synthesize the novel nanocomposite and optimize the process parameters to minimize the kerf width during WEDM. The independent variables like choice of wire electrode including the uncoated brass wire, diffused annealed wire, and zinc coated brass wire were considered along with operating parameters like gap voltage, pulse-off time (Toff), and pulse-on time (Ton). The response surface methodology (RSM) is used for designing experiments and analyzing and optimizing independent parameters of WEDM for minimizing the kerf width. Experimental results reveal that the machinability performance of the novel nanocomposite in WEDM with zinc coated brass wire was the best and produced minimum kerf width with the optimized inputs of 117 μs pulse-on time, 60 μs pulse-off time, 160A input current, and 10 volt gap voltage.

Review of Silicon Carbide Processing for Power MOSFET

Abstract: Owing to the superior properties of silicon carbide (SiC), such as higher breakdown voltage, higher thermal conductivity, higher operating frequency, higher operating temperature, and higher saturation drift velocity, SiC has attracted much attention from researchers and the industry for decades. With the advances in material science and processing technology, many power applications such as new smart energy vehicles, power converters, inverters, and power supplies are being realized using SiC power devices. In particular, SiC MOSFETs are generally chosen to be used as a power device due to their ability to achieve lower on-resistance, reduced switching losses, and high switching speeds than the silicon counterpart and have been commercialized extensively in recent years. A general review of the critical processing steps for manufacturing SiC MOSFETs, types of SiC MOSFETs, and power applications based on SiC power devices are covered in this paper. Additionally, the reliability issues of SiC power MOSFET are also briefly summarized.

Silicon Carbide Photonics Bridging Quantum Technology

Abstract: In the last two decades, bulk, homoepitaxial, and heteroepitaxial growth of silicon carbide (SiC) has witnessed many advances, giving rise to electronic devices widely used in high-power and high-frequency applications. Recent research has revealed that SiC also exhibits unique optical properties that can be utilized for novel photonic devices. SiC is a transparent material from the UV to the infrared, possess nonlinear optical properties from the visible to the mid-infrared and it is a meta-material in the mid-infrared range. SiC fluorescence due to color centers can be associated with single photon emitters and can be used as spin qubits for quantum computation and communication networks and quantum sensing. This unique combination of excellent electronic, photonic and spintronic properties has prompted research to develop novel devices and sensors in the quantum technology domain. In this perspective, we highlight progress, current trends and prospects of SiC science and technology underpinning the development of classical and quantum photonic devices. Specifically, we lay out the main steps recently undertaken to achieve high quality photonic components, and outline some of the current challenges SiC faces to establish its relevance as a viable photonic technology. We will also focus on its unique potential to bridge the gap between classical and quantum photonics, and to technologically advance quantum sensing applications. We will finally provide an outlook on possible alternative applications where photonics, electronics, and spintronics could merge.

Advances in Nanostructured Silicon Carbide Photocatalysts

Abstract: : Industrialization undoubtedly boosts economic development and improves the standard of living; however, it also leads to some serious problems, including the energy crisis, environmental pollution, and global warming. These problems are associated with or caused by the high carbon dioxide (CO 2 ) and sulfur dioxide (SO 2 ) emissions from the burning of fossil fuels such as coal, oil, and gas. Photocatalysis is considered one of the most promising technologies for eliminating these problems because of the possibility of converting CO 2 into hydrocarbon fuels and other valuable chemicals using solar energy, hydrogen (H 2 ) production from water (H 2 O) electrolysis, and degradation of pollutants. Among the various photocatalysts, silicon carbide (SiC) has great potential in the fields of photocatalysis, photoelectrocatalysis, and electrocatalysis because of its good electrical properties and photoelectrochemistry. This review is divided into six sections: introduction, fundamentals of nanostructured SiC, synthesis methods for obtaining nanostructured SiC photocatalysts, strategies for improving the activity of nanostructured SiC photocatalysts, applications of nanostructured SiC photocatalysts, and conclusions and prospects. The fundamentals of nanostructured SiC include its physicochemical characteristics. It possesses a range of unique physical properties, such as extreme hardness, high mechanical stability at high temperatures, a low thermal expansion coefficient, wide bandgap, and superior thermal conductivity. It also possesses exceptional chemical characteristics, such as high oxidation and corrosion resistance. The synthesis methods for obtaining nanostructured SiC have been systematically summarized as follows: Template growth, sol-gel, organic precursor pyrolysis, solvothermal synthesis, arc discharge, carbon thermal reduction, and electrospinning. These synthesis methods require high temperatures, and the reaction mechanism involves SiC formation via the reaction between carbon and silicon oxide. In the section of the review involving the strategies for improving the activity of nanostructured SiC photocatalysts, seven strategies are discussed, viz. , element doping, construction of Z-scheme (or S-scheme) systems, supported co-catalysts, visible photosensitization, construction of semiconductor heterojunctions, supported carbon materials, and construction of nanostructures. All of these strategies, except element doping and visible photosensitization, concentrate on enhancing the separation of holes and electrons, while suppressing their recombination, thus improving the photocatalytic performance of the nanostructured SiC photocatalysts. Regarding the element doping and visible photosensitization strategies, element doping can narrow the bandgap of SiC, which generates more holes and electrons to improve photocatalytic activity. On the other hand, the principle of visible photosensitization is that photo-induced electrons move from photosensitizers to the conduction band of SiC to participate in the reaction, thus enhancing the photocatalytic performance. In the section on the applications of nanostructured SiC, photocatalytic H 2 production, pollutant degradation, CO 2 reduction, photoelectrocatalytic, and electrocatalytic applications will be discussed. The mechanism of a photocatalytic reaction requires the SiC photocatalyst to produce photo-induced electrons and holes during irradiation, which participate in the photocatalytic reaction. For example, photo-induced electrons can transform protons into H 2 , as well as CO 2 into methane, methanol, or formic acid. Furthermore, photo-induced holes can convert organic waste into H 2 O and CO 2 . For photoelectrocatalytic and electrocatalytic applications, SiC is used as a catalyst under high temperatures and highly acidic or basic environments because of its remarkable physicochemical characteristics, including low thermal expansion, superior thermal conductivity, and high oxidation and corrosion resistance. The last section of the review will reveal the major obstacles impeding the industrial application of nanostructured SiC photocatalysts, such as insufficient visible absorption, slow reaction kinetics, and hard fabrication, as well as provide some ideas on how to overcome these obstacles. photocatalysts.

Electronic, Magnetic, and Optical Performances of Non-Metals Doped Silicon Carbide

Abstract: The configurations of nine different non-metals doped silicon carbide (NM-SiC) were structured by using the density functional theory (DFT). The magnetic, electronic, and optical properties of each NM-SiC are investigated at the most stable structure with the maximum binding energy. Although the O-, Si-, and S-SiC systems are still non-magnetic semiconductors, the N- and P-SiC systems have the properties of the magnetic semiconductors. The H-, F-, and Cl-SiC systems exhibit the half-metal behaviors, while the B-SiC system converts to magnetic metal. The redistribution of charges occurs between non-metals atoms and adjacent C atoms. For the same doping position, the more charges are transferred, the greater the binding energy of the NM-SiC system. The work function of the NM-SiC systems is also adjusted by the doping of NM atoms, and achieves the minimum 3.70 eV in the P-SiC, just 77.1% of the original SiC. The absorption spectrum of the NM-SiC systems occurs red-shift in the ultraviolet light region, accompanying the decrease of absorption coefficient. These adjustable magnetic, electronic, and optical performances of NM-SiC expand the application fields of two-dimensional (2D) SiC, especially in designing field emission and spintronics devices.

Promoting the thermal transport via understanding the intrinsic relation between thermal conductivity and interfacial contact probability in the polymeric composites with hybrid fillers

Abstract: Polymeric composites with thermally conductive hybrid fillers are significant in the electronics and thermal dissipation , where thermal transport along with multifunctionality is required to meet the application needs. Introduction of hybrid fillers would induce multiple interface scattering and rational design on the filler contact should be the critical criteria, while there is insufficient principle. To promote the thermal transport capability, in this paper, a contact probability model has been established to quantitatively analyze the thermal conductivity and contact probability in the silicone rubber composites with hybrid fillers (including various aluminium oxides and silicon carbide whisker). The results from experiment and simulation suggest that three critical parameters, i.e. volume fraction, filler shape and filler size, are the essential factors of hybrid fillers on impacting the thermal conductivity of composites. With understanding the contact types of hybrid filler, the optimized thermal conductivity has been obtained in the composites with aluminium oxides and silicon carbide whisker fillers. The model and analysis here have provided new contact mechanism for understanding the thermal transport in composites, which could be extended to rationally design and fabricate other types of polymeric composites with hybrid fillers.

Effect of Hybrid Reinforcements on the Mechanical Properties of Copper Nanocomposites

Abstract: Copper (Cu) composites hybridized with nano-sized reinforcing material are gathering attraction in such fields as automobile, aerospace, and power transmission due to their higher strength. Unlike conventional reinforcing materials, extraordinary mechanical properties and high electrical and thermal conductivity make nanomaterials highly useful reinforcement materials to improve the properties of pristine metals. Over the last two decades, several studies have been conducted to determine the effect of distinctive 2D nanomaterials, such as silicon carbide, aluminium oxide, copper nanotube, and graphene as reinforcement on properties of metal matrices. This study comprehensively reviews the effect of hybrid reinforcements on the mechanical properties of Cu composites having graphene as one of the reinforcements. Also, the contribution of these reinforced nanomaterials composition and their dispersion in the pure Cu matrices have also been explained in detail. In comparison with Cu composites fabricated with a single 2D reinforcement material, composites incorporating hybrid nano reinforcement, exhibit better mechanical behaviour. Additionally, the improvement in mechanical strength would enhance their capability to withstand altering thermal and surrounding environmental conditions.

A Compact Double-Sided Cooling 650V/30A GaN Power Module With Low Parasitic Parameters

Abstract: Compared with silicon and silicon carbide devices, the unique electrical and structural characteristics of gallium nitride high electron mobility transistors (GaN HEMTs) make them have different requirements for power module integration. This article proposes a novel integration scheme for the high-voltage lateral GaN HEMT dies without bonding wires. Based on the proposed integration scheme, a compact 650 V/30 A GaN power module with low parasitic parameters and high thermal performance is designed. The GaN dies are sandwiched between two ceramic substrates to improve thermal performance and ensure consistent thermal expansion coefficients. The multiple copper layer structure is used to increase wiring flexibility to reduce parasitic parameters. The design of gate and power loop layouts is discussed, and the common-mode (CM) capacitance is optimized. A comprehensive reliability evaluation is also carried out for this integration scheme. Finally, a double-sided cooling 650 V/30 A full-bridge GaN power module with 2.4 cm×1.3 cm×0.17 cm is fabricated. The thermal resistance is reduced by 30%–48% compared with the conventional single-sided cooling module. The power loop and gate loop inductances are reduced to 0.94 nH and 2 nH, respectively, and the CM capacitance is limited to 2.5 pF. The maximum d v /d t of the drain–source voltage is high as 150 V/ns with only 10% overshoot. Based on the power module, a 3.3-kW two-phase interleaved buck converter is developed. It has 820 W/in3 power density and 98.85% peak efficiency.

Silicon Carbide Technology for Advanced Human Healthcare Applications

Abstract: Silicon carbide (SiC) is a highly robust semiconductor material that has the potential to revolutionize implantable medical devices for human healthcare, such as biosensors and neuro-implants, to enable advanced biomedical therapeutic applications for humans. SiC is both bio and hemocompatible, and is already commercially used for long-term human in vivo applications ranging from heart stent coatings and dental implants to short-term diagnostic applications involving neural implants and sensors. One challenge facing the medical community today is the lack of biocompatible materials which are inherently smart or, in other words, capable of electronic functionality. Such devices are currently implemented using silicon technology, which either has to be hermetically sealed so it does not directly interact with biological tissue or has a short lifetime due to instabilities in vivo. Long-term, permanently implanted devices such as glucose sensors, neural interfaces, smart bone and organ implants, etc., require a more robust material that does not degrade over time and is not recognized and rejected as a foreign object by the inflammatory response. SiC has displayed these exceptional material properties, which opens up a whole new host of applications and allows for the development of many advanced biomedical devices never before possible for long-term use in vivo. This paper is a review of the state-of-the art and discusses cutting-edge device applications where SiC medical devices are poised to translate to the commercial marketplace.

Effect of stacking sequence and silicon carbide nanoparticles on properties of carbon/glass/Kevlar fiber reinforced hybrid polymer composites

Abstract: Synthetic fibers as reinforcement in composites are inevitable in today's composite industry due to its exceptional mechanical properties. The objective of this paper is to investigate the effect of stacking sequence of carbon, glass and Kevlar bidirectional (0°/90°) woven mat synthetic fibers reinforced in epoxy matrix composite with silicon carbide (SiC) nanoparticles as filler material on mechanical and visco-elastic behavior of developed novel hybrid polymer matrix composites (HPMCs). Vacuum bag infusion method is adopted to manufacture the composite specimens by stacking carbon, glass and Kevlar fibers alternatively with six layers and six different stacking sequences and tested as per ASTM standards. Tensile, flexural, impact and hardness test is conducted to identify the composite specimen with maximum mechanical characteristics. The maximum tensile and flexural strength of 398.178 and 671.25 MPa respectively is seen for the composite with strong fibers such as carbon and glass stacked away from the neutral axis. Also, the scanning electron microscope (SEM) images of tensile and flexural failure specimen revealed the failure mechanisms of developed composite specimens. Moreover, the dynamic mechanical analysis (DMA) revealed the visco-elastic behavior of developed composites with glass transition temperature (Tg) at 115°C. This study emphasizes the influence of stacking sequence on thermo-mechanical properties of the developed HPMC specimens and explores its potential for diverse applications.