Silicon Carbide Materials Research Articles

Recent Advances in Reactive Ion Etching and Applications of High-Aspect-Ratio Microfabrication.

This paper reviews the recent advances in reaction-ion etching (RIE) for application in high-aspect-ratio microfabrication. High-aspect-ratio etching of materials used in micro- and nanofabrication has become a very important enabling technology particularly for bulk micromachining applications, but increasingly also for mainstream integrated circuit technology such as three-dimensional multi-functional systems integration. The characteristics of traditional RIE allow for high levels of anisotropy compared to competing technologies, which is important in microsystems device fabrication for a number of reasons, primarily because it allows the resultant device dimensions to be more accurately and precisely controlled. This directly leads to a reduction in development costs as well as improved production yields. Nevertheless, traditional RIE was limited to moderate etch depths (e.g., a few microns). More recent developments in newer RIE methods and equipment have enabled considerably deeper etches and higher aspect ratios compared to traditional RIE methods and have revolutionized bulk micromachining technologies. The most widely known of these technologies is called the inductively-coupled plasma (ICP) deep reactive ion etching (DRIE) and this has become a mainstay for development and production of silicon-based micro- and nano-machined devices. This paper will review deep high-aspect-ratio reactive ion etching technologies for silicon, fused silica (quartz), glass, silicon carbide, compound semiconductors and piezoelectric materials.

Optoelectronics of Color Centers in Diamond and Silicon Carbide: From Single‐Photon Luminescence to Electrically Controlled Spin Qubits

AbstractColor centers in diamond, silicon carbide, and related materials have recently emerged as one of the most promising platforms for quantum technology applications. These optically active point defects in the crystal lattice demonstrate outstanding optical and spin properties at room and even higher temperatures, which can hardly be achieved using other quantum systems. For a long time, the host material was considered only as a mechanical carrier of color centers, and the fact that it is a semiconductor and, therefore, can contain high densities of electrons and holes, was ignored. However, recent studies have demonstrated that color centers can exchange electrons and holes with the valence or conduction bands of the host material, which enables novel functionalities, ranging from ultrabright electrically driven single‐photon sources to protected quantum memories. This review summarizes recent advances in understanding this interaction.

Finite-element-method study of tilt mirrors without PZTs using different clamping methods under laser irradiation

Tilt mirrors play a fundamental role in correcting aberrations in adaptive optics systems. To analyze the influence of clamping methods and materials on temperature rising, deformations and high-order aberrations of tilt mirrors without PZTs during the evaluation of laser irradiation of multilayer coatings, a finite-element model of tilt mirror with a diameter of 100 mm and thicknesses of 12.5 mm was constructed. The deformation and high-order aberrations were simulated after applying a laser to the mirrors. The appearance of peak-to-valley and high-order aberrations became more significant as the tilt mirror was supported on the edge at 3 points 120° apart. Using 3 points at the back and 3 points on the side 120° apart with polytetrafluoroethylene (PTFE) protection clamping lessened the effect, and the PV was only 0.0828 µm. The corresponding 65th-order Zernike coefficients were lower, so the clamping approach is ideal for fixing the tilt mirror for evaluating the multilayer coatings. Also, the temperature rising and thermal deformation of tilt mirrors made from various materials under laser irradiation were calculated. The results show that the tilt mirror made of ultra-low expansion microcrystalline glass had the highest temperature rising and the lowest thermal deformation. The temperature rising and PV was 10.56 ℃ and 0.004 µm, respectively. Beryllium and silicon carbide materials are suitable for increasing the resonance frequency and reducing the weight of tilt mirrors. These results are also useful for designing the clamping methods of large size folding mirror, telescope fast steering mirror and small scanner mirror, etc.

Advances in Si and SiC Materials for High-Performance Supercapacitors toward Integrated Energy Storage Systems.

Silicon (Si), as the second most abundant element on Earth, has been a central platform of modern electronics owing to its low mass density and unique semiconductor properties. From an energy perspective, all-in-one integration of power supply systems onto Si-based functional devices is highly desirable, which inspires significant study on Si-based energy storage. Compared to the well-known Si-anode Li-ion batteries, Si-based supercapacitors possess high power density, long life, and simple working mechanisms, which enables their ease of integration onto a wide range of devices and applications. Besides Si, silicon carbide (SiC), as a physicochemically stable wide-bandgap semiconductor, also attracts research attention as an energy storage material in harsh environments. In this review, a detailed overview of latest advances in materials design, synthesis methods, and performances of Si-based and SiC-based supercapacitors will be provided. Some successful integrated devices, future perspectives, and potential research directions are also highlighted and discussed.

Failure analysis and improvement of the tribological performance of sliding bearing tribopair in integrated energy recovery-pressure boost device

Integrated rotary energy recovery-pressure boost device (IERPBD) is the essential component in seawater reverse osmosis (SWRO) desalination systems. And sliding bearing pair is the vital tribopair in the IERPBD, which guarantee the reliability of the device. However, the polyetheretherketone (PEEK) bearing in the IERPBD occurred early failure during the pre-experiment. To solve this problem, this paper firstly analyzed the reasons and mechanisms of sliding bearing early failure, which suggested that it was attributed to the low elasticity modulus and poor tribological performance of PEEK. Moreover, several improved “hard-to-hard” material combinations were proposed and screened through wear and friction experiments, and found that the WC-6Ni (YN6X)/silicon carbide (SiC) material combination has reasonable physicochemical properties and excellent tribological performance. Finally, the sliding bearing made of YN6X/SiC was equipped in IERPBD to carry out experiments under real working conditions to verify the performance of proposed material combination. The results indicated that YN6X/SiC sliding bearing pair could guarantee the continuous and stable operation of IERPBD, and effectively solve the sliding bearing failure problem.

Porous Silicon Carbide (SiC): A Chance for Improving Catalysts or Just Another Active-Phase Carrier?

There is an obvious gap between efforts dedicated to the control of chemicophysical and morphological properties of catalyst active phases and the attention paid to the search of new materials to be employed as functional carriers in the upgrading of heterogeneous catalysts. Economic constraints and common habits in preparing heterogeneous catalysts have narrowed the selection of active-phase carriers to a handful of materials: oxide-based ceramics (e.g. Al2O3, SiO2, TiO2, and aluminosilicates-zeolites) and carbon. However, these carriers occasionally face chemicophysical constraints that limit their application in catalysis. For instance, oxides are easily corroded by acids or bases, and carbon is not resistant to oxidation. Therefore, these carriers cannot be recycled. Moreover, the poor thermal conductivity of metal oxide carriers often translates into permanent alterations of the catalyst active sites (i.e. metal active-phase sintering) that compromise the catalyst performance and its lifetime on run. Therefore, the development of new carriers for the design and synthesis of advanced functional catalytic materials and processes is an urgent priority for the heterogeneous catalysis of the future. Silicon carbide (SiC) is a non-oxide semiconductor with unique chemicophysical properties that make it highly attractive in several branches of catalysis. Accordingly, the past decade has witnessed a large increase of reports dedicated to the design of SiC-based catalysts, also in light of a steadily growing portfolio of porous SiC materials covering a wide range of well-controlled pore structure and surface properties. This review article provides a comprehensive overview on the synthesis and use of macro/mesoporous SiC materials in catalysis, stressing their unique features for the design of efficient, cost-effective, and easy to scale-up heterogeneous catalysts, outlining their success where other and more classical oxide-based supports failed. All applications of SiC in catalysis will be reviewed from the perspective of a given chemical reaction, highlighting all improvements rising from the use of SiC in terms of activity, selectivity, and process sustainability. We feel that the experienced viewpoint of SiC-based catalyst producers and end users (these authors) and their critical presentation of a comprehensive overview on the applications of SiC in catalysis will help the readership to create its own opinion on the central role of SiC for the future of heterogeneous catalysis.

Behavior of Silicon Carbide Materials under Dry to Hydrothermal Conditions.

Silicon carbide materials are excellent candidates for high-performance applications due to their outstanding thermomechanical properties and their strong corrosion resistance. SiC materials can be processed in various forms, from nanomaterials to continuous fibers. Common applications of SiC materials include the aerospace and nuclear fields, where the material is used in severely oxidative environments. Therefore, it is important to understand the kinetics of SiC oxidation and the parameters influencing them. The first part of this review focuses on the oxidation of SiC in dry air according to the Deal and Grove model showing that the oxidation behavior of SiC depends on the temperature and the time of oxidation. The oxidation rate can also be accelerated with the presence of H2O in the system due to its diffusion through the oxide scales. Therefore, wet oxidation is studied in the second part. The third part details the effect of hydrothermal media on the SiC materials that has been explained by different models, namely Yoshimura (1986), Hirayama (1989) and Allongue (1992). The last part of this review focuses on the hydrothermal corrosion of SiC materials from an application point of view and determine whether it is beneficial (manufacturing of materials) or detrimental (use of SiC in latest nuclear reactors).

Free‐enzymatic Indirect Detection of Malathion by SiC@CuO‐NPs Composite Nanomaterial Modified Glassy Carbon Electrode

AbstractWe prepared a highly sensitive electrochemical sensor for the free‐enzymatic indirect detection of malathion. The electrochemical sensor was based silicon carbide and copper oxide nanocomposite material. The structural and morphological properties of the SiC@CuO‐NPs nanocomposite was characterized by scanning electron microscopy (SEM) and X‐ray diffraction (XRD). SiC‐NPs has the function of malathion pre‐concentration and SiC@CuO‐NPs nanocomposite was noted to possess high affinity towards malathion, thus the redox reaction of CuO could be hindered. This feature was utilized to design as a simple strategy for electrochemical detection of malathion. Electrochemical detection of malathion was investigated via cyclic voltammetry (CV), differential pulse voltammetry (DPV), respectively. Under the optimized experimental conditions, the inhibition rate displays a good linear relationship with the concentration of malathion, the linear range is 0.03 nM∼3.0 nM, and the detection limit is 0.01 nM (S/N=3). In addition, the sensor exhibits good selectivity, stability and reproducibility, and has been successfully used in the detection of malathion in actual water samples with recoveries between 99.33 % and 106.6 %, which is satisfactory experimental results.

Water-induced effect on femtosecond laser layered ring trepanning in silicon carbide ceramic sheets using low-to-high pulse repetition rate

An underwater femtosecond laser layered ring trepanning (FLLRT) technology is reported in this paper. The FLLRT experiments are performed in silicon carbide (SiC) ceramic sheets in air and water. The effects of water immersion and laser pulse repetition rate on laser trepanning quality and hole generation characteristics are demonstrated by altering the laser pulse repetition rate. The underwater FLLRT technology notably improves the laser hole-trepanning quality for the SiC material because of the water cooling–insulating effect, underwater bubble-cavitation effect, and water microstreaming effect. Performing FLLRT in water, the hole diameter, particularly the hole exit diameter, increased whereas the hole taper decreased when using a relatively low pulse repetition rate. Furthermore, the hole-wall formation quality and surface uniformity improved while notably reducing the hole-wall oxidation. Significantly, the redeposition of the vapourised material and the resolidification of the molten material are greatly reduced, thereby reducing the formation of the recast layer and micro cracks. When the pulse repetition rate was relatively high, the local thermal accumulation effect induced by significantly more successive laser pulses was notably enhanced for melting the SiC material despite the laser ablation-induced vapourisation.

Study of high efficiency, low noise sputtered magnetron's cathode using GaN and SiC semiconductors for modulated microwave power transmission

AbstractSemiconductor deposition on magnetron's cathode surface using different materials such as gallium nitride (GaN) and silicon carbide (SiC) semiconductors is conducted to grow approximately 80, 100 and 120 nm plasma layers. The cathode is then used to generate high frequency and low-power microwave for further comparison and analysis with the conventional magnetron operation. Parameter of analysis to identify the efficiency includes electron drift velocity, harmonic order, total harmonic distortion, low harmonic distortion, and spectrum observation. The sputtered cathode of the magnetron is used to generate a low-power microwave observing a generator efficiency up to 93 and 88% for GaN and SiC materials, respectively, compared to the conventional material, which observes 37% of efficiency at 2450 MHz, 5 W. Also reported is the quality of semiconductor sputtering on the magnetron cathode, which was manipulated by the deposition period, temperature, and plasma layer growth thickness.

Machine-Learning-Based Atomistic Model Analysis on High-Temperature Compressive Creep Properties of Amorphous Silicon Carbide.

Ceramic matrix composites (CMCs) based on silicon carbide (SiC) are used for high-temperature applications such as the hot section in turbines. For such applications, the mechanical properties at a high temperature are essential for lifetime prediction and reliability design of SiC-based CMC components. We developed an interatomic potential function based on the artificial neural network (ANN) model for silicon-carbon systems aiming at investigation of high-temperature mechanical properties of SiC materials. We confirmed that the developed ANN potential function reproduces typical material properties of the single crystals of SiC, Si, and C consistent with first-principles calculations. We also validated applicability of the developed ANN potential to a simulation of an amorphous SiC through the analysis of the radial distribution function. The developed ANN potential was applied to a series of creep test for an amorphous SiC model, focusing on the amorphous phase, which is expected to be formed in the SiC-based composites. As a result, we observed two types of creep behavior due to different atomistic mechanisms depending on the strain rate. The evaluated activation energies are lower than the experimental values in literature. This result indicates that an amorphous region can play an important role in the creep process in SiC composites.

Improvement in chemical mechanical polishing of 4H-SiC wafer by activating persulfate through the synergistic effect of UV and TiO2

Chemical mechanical polishing (CMP) has revolutionized the processing of semiconductor material such as silicon carbide (SiC). However, the strong chemical bond between silicon atoms and carbon atoms gives SiC materials a very high mechanical hardness and chemical stability. Therefore, SiC wafers may suffer from a low material removal rate (MRR) and serious subsurface damage when traditional CMP methods are used. In this study, to improve the CMP properties of Si-face of the 4H-SiC wafers, the synergistic effect of UV and TiO 2 on the activation of persulfate (PS) was investigated for the first time. The response surface method was employed to study the effect of pH, PS concentration, and TiO 2 dosage on CMP in-depth, and to ultimately optimize the polishing process. The analysis demonstrated that an MRR of 608 nm/h can be obtained with the average surface roughness ( Sq ) of 0.521 nm when the pH is 6, in which the TiO 2 dosage is 0.015 wt% and the PS concentration is 3 wt%. Polarization curves, AC impedance spectra and X-ray photoelectron spectroscopy tests were performed to further analyze the chemical action of the slurry, which showed that the introduction of UV-TiO 2 strongly enhances the chemical action of slurry and results in the formation of a passivated layer on the SiC surface. Finally, based on the radical quenching experiments and the results mentioned above, a model that relates to the removal of 4H-SiC by UV-TiO 2 synergistic activation of PS is proposed.

Determination of the Temperature Coefficient of Linear Expansion of Materials Based on Silicon Carbide

Information on the temperature coefficient of linear expansion (TCLE) of materials based on silicon carbide is presented. It is shown that the different polytypes 3C (cubic modification) and 4H and 6H (hexagonal modifications) are characterized by different thermal expansions, the difference between the values of which increases with increasing temperature. The TCLEs of reaction-sintered, liquid-phase-sintered, and hot-pressed silicon carbide materials are determined in the range 20 – 1800°C.

Antimicrobial and immunomodulatory potential of nanoscale hierarchical one-dimensional zinc oxide and silicon carbide materials

This work reports the comparison of antimicrobial and immunomodulatory activities between nanoscale hierarchical ZnO nanorods (NRs) and SiC nanowires (NWs). The fabricated one-dimensional (1D) materials possess various nanoscale sizes, morphologies, geometries, and crystal directions. A developed hexamethylenetetramine-assisted hydrothermal regime was followed for preparing wurtzite–ZnO NRs with 40 nm average width, 1 μm length, and [0001] growth orientation. The antibacterial activity of NRs was compared with that of SiC NWs, which had 50–80 nm width and [111] direction. The antibacterial activity of the hierarchical NRs and NWs was tested using different microorganisms including Gram-positive and Gram-negative bacteria and fungi strains. The microbial inactivation of the hierarchical 1D nanomaterials was evaluated by inhibition zone, minimal inhibition concentration (MIC), cell viability assays, and nitroblue tetrazolium reduction test. Cell apoptosis was elucidated by confocal laser scanning microscopy. The scanning electron microscope results showed that [0001]-ZnO NRs led to higher loss in bacterial viability than [111]-SiC NWs. Also, ZnO NRs exhibited lower MIC values than SiC NWs with 3.9, 7.9, 31.25, and 7.91 μg/mL for P. aeruginosa, A. baumannii, S. aureus ATCC 29213, S. typhi ATCC 6539, respectively. This is caused by the higher surface area, smaller width and length, hexagonal wurtzite structure, and highly exposed [0001] polar surface grown along the c-axis of ZnO NRs.

Neutronic analysis for the Edge Charge Exchange Recombination Spectroscopy in Equatorial Port of ITER

• Neutronics for Edge Charge Exchange Recombination Spectroscopy (CXRS-Edge). • CXRS-Edge Diagnostics installed in Equatorial Port #3 (EP3) of ITER. • New MCNP model of CXRS-Edge Diagnostic system in EP3 was created. • Personnel access to the Inter-Space Structure (ISS) the EP3 is evaluated. • Maps of local shutdown dose rate (SDDR) are shown in EP3 ISS with CXRS-Edge. The neutronic analysis results presented in this paper support the design development of the Edge Charge Exchange Recombination Spectroscopy (CXRS-Edge) system to be installed in Equatorial Port #3 (EP3) of ITER. That is an active optical diagnostic system with a dogleg labyrinth design of two optical pathways and a system of mirrors arranged in Diagnostic Shield Modules #1 and #2 (DSM #1 and #2) of EP3. The shielding performance of the CXRS-Edge system and the radiation effects of its mirror materials have been evaluated. To this end, a neutronic 3D model of the CXRS-Edge system has been created in the format of the MCNP code. The MCNP model of CXRS has been converted from the underlying CAD engineering model using the SuperMC code. Then the model has been integrated with the actual standard MCNP model of the ITER tokamak called “C-Model R181031 (Revision 190110)”. With this C-Model, neutron and photon fluxes, nuclear heating distributions and neutron damage in molybdenum, steel, and silicon carbide (SiC) materials have been calculated. Assessing the possibility of personnel access to the Inter-Space Structure (ISS) of EP3 with CXRS-Edge installed, a map of shutdown dose rate (SDDR) has been calculated using the local approach, without any other diagnostics systems shared by EP3. In conclusion, the suitability of CXRS Edge doglegs for necessary attenuations of neutron and photon fluxes, nuclear heating, and SDDR is demonstrated. As design work is progressing, this paper presents an initial contribution to the complete neutronic analysis.

Numerical analysis and thermal fatigue life prediction of solder layer in a SiC-IGBT power module

Limited by the mechanical properties of materials, silicon (Si) carbide insulated gate bipolar transistor (IGBT) can no longer meet the requirements of high power and high frequency electronic devices. Silicon carbide (SiC) IGBT, represented by SiC MOSFET, combines the excellent performance of SiC materials and IGBT devices, and becomes an ideal device for high-frequency and high-temperature electronic devices. Even so, the thermal fatigue failure of SiC IGBT, which directly determines its application and promotion, is a problem worthy of attention. In this study, the thermal fatigue behavior of SiC-IGBT under cyclic temperature cycles was investigated by finite element method. The finite element thermomechanical model was established, and stress-strain distribution and creep characteristics of the SnAgCu solder layer were obtained. The thermal fatigue life of the solder was predicted by the creep, shear strain and energy model respectively, and the failure position and factor of failure were discussed.

Output Characteristics of Graphene Field Effect Transistors

The use of graphene, which has high mobility of charge carriers, high thermal conductivity and a number of other positive properties, is promising for the creation of new semiconductor devices with good output characteristics. The aim was to simulate the output characteristics of field effect transistors containing graphene using the Monte-Carlo method and the Poisson equation.Two semiconductor structures in which a single layer (or monolayer) of graphene is placed on a substrate formed from 6H-SiC silicon carbide material are considered. The peculiarity of the first of them is that the contact areas of drain and source were completely located on the graphene layer, the length of which along the longitudinal coordinate was equal to the length of the substrate. The second structure differed in that the length of the graphene layer was shortened and the drain and source areas were partly located on the graphene layer and partly on the substrate.The main output characteristics of field-effect transistors based on the two semiconductor structures considered were obtained by modeling. The modeling was performed using the statistical Monte Carlo method. To perform the simulation, a computational algorithm was developed and a program of numerical simulation using the Monte-Carlo method in three-dimensional space using the Poisson equation was compiled and debugged.The results of the studies show that the development of field-effect transistors using graphene layers can improve the output characteristics – to increase the output current and transconductance, as well as the limit frequency of semiconductor structures in high frequency ranges.

Equivalent thin-plate method for stressed mirror polishing of an off-axis aspheric silicon carbide lightweight mirror.

No physical model of stressed mirror polishing, based on the small deflection and deformation of elastic thin plates, has been applied in processing lightweight mirrors. We propose an equivalent thin-plate method for the stressed loading of lightweight mirrors for the first time. Stressed loading and polishing of an aspheric lightweight mirror are simulated using the small-deflection deformation theory of an elastic thin plate. We simulate off-axis aspheric silicon carbide (SiC) lightweight mirrors with three different structures, determining the corresponding equivalent thickness plate in a lightweight structure with a nearly uniform surface density distribution and isotropic bending properties. We then establish a residual removal model of a stressed polishing surface, design the stressed loading equipment, and propose an iterative method for stressed polishing of an off-axis aspheric SiC lightweight mirror. The results demonstrate that it is feasible to choose a lightweight structure that performs full-aperture stressed polishing on off-axis aspheric lightweight mirrors consisting of SiC or other materials.

Two-Dimensional Silicon Carbide: Emerging Direct Band Gap Semiconductor.

As a direct wide bandgap semiconducting material, two-dimensional, 2D, silicon carbide has the potential to bring revolutionary advances into optoelectronic and electronic devices. It can overcome current limitations with silicon, bulk SiC, and gapless graphene. In addition to SiC, which is the most stable form of monolayer silicon carbide, other compositions, i.e., are also predicted to be energetically favorable. Depending on the stoichiometry and bonding, monolayer may behave as a semiconductor, semimetal or topological insulator. With different Si/C ratios, the emerging 2D silicon carbide materials could attain novel electronic, optical, magnetic, mechanical, and chemical properties that go beyond those of graphene, silicene, and already discovered 2D semiconducting materials. This paper summarizes key findings in 2D SiC and provides insight into how changing the arrangement of silicon and carbon atoms in SiC will unlock incredible electronic, magnetic, and optical properties. It also highlights the significance of these properties for electronics, optoelectronics, magnetic, and energy devices. Finally, it will discuss potential synthesis approaches that can be used to grow 2D silicon carbide.

Additive manufacturing of silicon carbide for nuclear applications

Additive manufacturing (AM) is a rapidly evolving technology being considered for nuclear applications. A special focus on AM to fabricate nuclear-grade silicon carbide (SiC) is explored in this paper. First, we present currently available AM processing options for SiC. AM methods commonly used for other ceramics, in which the feedstocks are forms of polymers, powders, and/or reactive chemical vapors, are also applicable to SiC. SiC phases are formed by pyrolysis of pre-ceramic polymer, direct reaction of powder precursors, sintering of SiC powders, or chemical vapor deposition/infiltration. Second, we discuss how the different microstructures of SiC materials fabricated by various processing methods affect their behavior in nuclear environments. Third, we discuss state-of-the-art AM technologies for the fabrication of relatively pure SiC, which show great potential to retain its strength under neutron irradiation: (1) binder jet printing followed by chemical vapor infiltration, (2) laser chemical vapor deposition, and (3) selective laser sintering of SiC powders.