Structure Of Silicon Carbide Research Articles

Fabrication of Ripple Structured Silicon Carbide (SiC) Films for Nano‐Grating and Solar Cell Applications

AbstractIn the present study, we aim to investigate the self‐organization of unexplored silicon carbide (SiC) film surfaces under 30 keV oblique Ar+ ions irradiation and hence unprecedented tailoring of optical and electrical characteristics with view of their uses in solar cells, gratings and nano‐ to micro‐scale devices. The surface morphology mainly consisted of triangular shaped nanoparticles which evolves into nanoscale ripple structures with an alignment parallel to the projection of ion beam direction. For the first time, we have demonstrated the fabrication of highly‐ordered ripple patterns with wavelength in visible region over SiC films and applicable as nano‐gratings. The underlying mechanism relies on the structural rearrangement due to transition of film microstructure from amorphous to mixed phase (crystalline, nano‐crystalline and amorphous) and lowering of C=C and C−C vibration modes by the heavier Si atoms. These nanostructured silicon carbide film shows unparalleled optical (energy gap decreases from 4.60±0.4 eV to 3.16±0.2 eV) & electrical characteristics (conductivity increases from 6.6×10−11 to 1.12×10−3 S/m with linear I−V behavior). Thus, we propose that ripple structured SiC films with wide band gap, high refractive index and high electrical conductivity with ohmic behaviour are promising candidates for application as window layer in solar cells and opto‐electronics.

Non-linear AC dielectric properties of epoxy composites filled with core–shell SiC particles

Abstract Core–shell structured silicon carbide (SiC)/epoxy (EP) composites exhibit superior non–linear DC conductivity. However, the high voltage alternative current dielectric properties of the composites are rarely reported. In this paper, the time–domain measurement was employed to obtain the basic dielectric characteristics, AC conductivity, and relative permittivity of the SiC/EP and SiC@Al2O3/EP composites under less than the breakdown strength of the SiC/EP (i.e. the amplitude of 1–5 kV mm−1). In addition, in the high AC electric field (i.e. the amplitude of 6–20 kV mm−1), the non–linear AC dielectric properties of the SiC@Al2O3/EP composite are also investigated. The experimental results suggest that the SiC@Al2O3/EP composite shows more obvious non–linear AC dielectric properties than the SiC/EP composite. In the high AC electric field, the AC conductivity of the SiC@Al2O3/EP composite presents the relaxation phenomenon, which is attributed to the excitation field and its derivative. This work lays a foundation for further research on the AC steady–state and transient dielectric properties of the field grading materials, which are widely used to homogenize the nonuniform electric field distribution in many electrical and electronic equipment.

Exploring Defect Dynamics and Twin-Layer Interactions in SiC Crystals through Molecular Simulations.

Silicon carbide (SiC), a third-generation semiconductor material, is pivotal for applications in new energy vehicles, aerospace, and high-speed electronics, owing to its superior properties. This study delves into the twin-induced growth behaviors of SiC crystals through molecular dynamics simulations at temperatures ranging from 2700 to 3200 K. It focuses on the wurtzite and zinc blende SiC structures, revealing dynamic defect behavior during growth, including an initial rise and subsequent decrease in vacancies, with particular emphasis on prevalent defects within zinc blende twin layers. A significant finding is the direct correlation between temperature and growth rates across different SiC structures, highlighting temperature control as essential for optimizing crystal quality. Furthermore, this work contributes to the analysis of the interactions of twin layers and their impact on structural stability and defect formation in SiC crystals. The insights gained here have substantial implications for the semiconductor industry, potentially enhancing device performance by better controlling growth conditions and defect management in SiC-based electronic and optoelectronic devices.

Direct Vat‐Photopolymerization 3D Printing of Hierarchically Porous SiC Loaded with Co/Ni Based Catalysts by Using Pickering Emulsions

AbstractHierarchically porous silicon carbide (SiC) is an important catalyst support widely used in various gas and liquid catalytic processes. Conventional approaches to fabricate such SiC have limited design flexibility and separated catalyst‐loading step is necessitated. Herein, a one‐step, direct vat‐photopolymerization 3D printing of hierarchically porous SiC loaded with Co/Ni based catalyst is demonstrated with Pickering emulsion as feedstock for the first time. Compared with normal ceramic slurries, Pickering emulsion dramatically increases the cure depth (by 50%) and emulsion stability, which allow continuous printing of complex SiC structures with uniform pore morphology. The resultant hierarchical porous SiC offered ≈40% better mechanical strength as compared with non‐hierarchical counterpart. By dissolving metal salts into aqueous phase in Pickering emulsions, complex architected structures with Co or Ni/Co in situ loaded in SiC matrix are printed. The metal salts are then thermally converted into oxides or silicates as catalysts anchored on SiC, exhibiting excellent catalytic activity and reusability. The emulsion templating strategy holds great facility to load various highly attractive materials such as high entropy oxides or functional fillers whilst reaping the benefits of vat photopolymerization for a myriad of applications in catalysis, batteries, and structural supports.

Failure mechanisms of lightweight high strength Si/SiC non-uniform lattice structures by SLS/RMI

Silicon Carbide (SiC) ceramic lattice structures were pivotal in advancing space technology and other sectors by merging structural lightness with high strength. This study explored non-uniform lattice designs tailored for specific load-bearing applications to maximize lightness, although machining such SiC structures proved challenging due to their high hardness and wear resistance. Selective Laser Sintering (SLS) was employed to fabricate non-uniform lattice structures featuring graded volume fractions. Micro computed tomography (Miro-CT) characterized the geometric characteristics of the macroscopic non-uniform lattice structure. Extensive investigations were conducted on the impact of these gradient structures on the quasi-static compressive behavior and mechanical properties of SiC ceramics, revealing that the R-A structure achieved a maximum compressive strength of 14.989 MPa and a specific strength of 13.268 × 10³ N·m/kg, approximately double that of a uniform structure. Furthermore, a finite element model (FEM) was established to verify and predict the mechanical and fracture responses of SiC-based structures, showing effective dispersion of stress concentration along the outer rim of the R-A structure, markedly alleviating the usual stress concentration found in traditional lattices and averting catastrophic failure. The alignment between experimental and simulation outcomes substantiated these findings.

Combining dip-coating and rotate-drying to preparation of PDMS on SiC tubular support with macropore for high pervaporation performance

High-performance polydimethylsiloxane (PDMS)/ceramic tubular pervaporation membranes have potential in industrial separation applications, but realizing the preparation of PDMS layer on the ceramic supports with micrometer-scale pore size (0.8 μm or 4.3 μm) for improving performance remains a challenge. We report a strategy (combined dip-coating and rotate-drying, DCRD) to preparation of PDMS on silicon carbide (SiC) tubular support with macropore. Response surface methodology was employed to optimize the dip-coating process, and the influence of friction velocity on tubular composite membranes was investigated. The results indicate that pulling speed, casting solution viscosity, and their interaction have significant effects on the pervaporation performance of PDMS/SiC tubular composite membranes. Moreover, increasing friction velocity results in uneven PDMS layer thickness, which in turn impacts the pervaporation performance of the composite membrane. Furthermore, the rigid structure of SiC restricts the movement of PDMS polymer chains, enabling the composite membrane to maintain stable pervaporation performance at higher isobutanol feed concentrations (3 wt%) or elevated feed temperatures (60 °C). After continuous operation for 200 h, the developed PDMS/SiC tubular composite membrane consistently maintained the total flux of 650 g m−2 h−1 and the separation factor of 39 for isobutanol/water. Eventually, this novel fabrication method offers new insights into the preparation of various other organic-inorganic tubular composite membranes.

The internal modified layer structure of silicon carbide induced by ultrafast laser and its application in stealth dicing

Silicon carbide (SiC) is widely applied in high-power electronic devices due to its excellent properties. Stealth dicing (SD) as one of the dicing methods, exhibits the advantages of few thermal surface damage and low edge-chipping. In this study, we use an ultrafast laser to induce the modified layer structure inside the SiC wafers. The effects of laser processing parameters on the modified layers are studied. The formation mechanism of the modified layer and its influence on SD are analyzed. The result shows that the number of modified layer structures is mainly determined by the moving velocity. The different modified layer structures will affect the surface roughness of the SD cross-section and critical fracture load of the 4H–SiC wafers. Finally, we achieved the high-quality SD of SiC wafers, and a cross-section with the minimum surface roughness is approximately 381 nm.

3D printing of high-purity complex SiC structures based on stereolithography

Complex Silicon carbide (SiC) structures are hardly achievable via traditional manufacturing methods, while stereolithography 3D printing technology effectively shapes sophisticated structures with high precision. However, it is a huge challenge to prepare SiC slurry for stereolithography 3D printing with excellent curing ability due to the increased light absorption of SiC powder. Therefore, a novel approach to fabricating high-purity SiC structures is proposed in this study based on the stereolithography 3D printing process, where SiO2 powder is used as an additive to increase the curing thickness from 27.8 μm to 53.0 μm. Moreover, phenolic epoxy resin (PEA) is introduced as a carbon source to transform SiO2 to SiC during sintering. As a result, there is almost no SiO2 phase or SiOC remaining in the final parts when the addition of PEA reaches 50 wt% related to the resin weight after sintering at 1600 °C for 4 h. Based on the SiC/SiO2/PEA slurry systems prepared, high-purity silicon carbide with complex structures can be successfully fabricated in one step without any pre-oxidation or precursor impregnation processes. This approach provides valuable insights into additive manufacturing of high-purity complex SiC structures.

Vat photopolymerization of large-aperture high performance SiC mirror through multiphase carbon infiltration modification

Vat photopolymerization technique (VPP) shows advantages in rapidly preparation of complex structure silicon carbide matrix composites (Si/SiC). However, compared with traditional preparation technology, the properties of Si/SiC prepared via VPP are insufficient due to the presence of residual Si and carbon. Herein, the reaction mechanism of Si and carbon were systematically studied. Multiphase carbon was introduced into porous SiC preform via carbon precursor infiltration pyrolysis (CPIP) and graphitization methods. The content of residual Si was significantly decreased after reactive melt infiltration (RMI), and the residual carbon was eliminated through partial graphitization of the carbon. The influence mechanism of the carbon content and crystallinity on the reaction process of Si and carbon was studied. It suggested that the diameter of capillary channel and crystallinity of carbon are the main factors affecting residual carbon content in the final body after RMI. The sample with multiphase carbon achieved the best performance after RMI. The residual Si content, bulk density, flexural strength and elastic modulus are 11.58%, 3.04 g/cm3, 280.09 MPa and 355.48 GPa. In addition, the lowest coefficient of linear expansion was 2.39×10−6 K−1. Finally, a large-aperture SiC mirror with a diameter of 500 mm was prepared. Therefore, this research lays a foundation for promoting the application of large-aperture Si/SiC prepared via 3D printing.

High strength and high toughness Csf/SiC composites prepared by laser powder bed fusion/ reactive melt infiltration with the impregnation of boron-and silicone-containing phenolic resin

Laser powder bed fusion (LPBF) has emerged as an effective method for preparing complex structured silicon carbide (SiC) ceramics. However, the SiC components demonstrate low strength and high brittleness, which remain major challenges limiting its application. To overcome this limitation, short carbon fiber reinforced silicon carbide (Csf/SiC) composites are prepared by combining LPBF and phenolic resin binder impregnation (PRBI)-reactive melt infiltration (RMI), in which high char yield boron-and silicone-containing phenolic resin (BSiPF) impregnation is used to adjust the carbon density of green bodies and to reduce the pore size of green bodies. By optimizing the impregnation process, the carbon density can be brought close to the theoretical optimal value of 0.84 g/cm3, and the reduction of the pore size is conducive to the improvement of the reaction rate at the early stage of the reaction, which enhance the SiC phase content of Csf/SiC composites obtained by RMI. Meanwhile, the application of BSiPF results in a protective pyrolytic carbon (PyC) coating on the surface of Csf, which can reduce the erosion of Csf by molten Si during the RMI process, thus improving the fracture toughness of Csf/SiC composites. The final Csf/SiC composites exhibit the enhanced bulk density, bending strength and fracture toughness, reaching 2.90 ± 0.01 g/cm3, 257 ± 20 MPa, 3.52 ± 0.15 MPa m1/2, respectively. This study provides a new strategy for effective impregnation technique for the additive manufacturing (AM) of high strength and high toughness SiC composites.

Cross-scale static/dynamic shear damage evolution mechanism of 2D C/SiC ceramic matrix composite with transient hysteresis effect

The intricate woven structure of two-dimensional woven carbon fiber-reinforced silicon carbide (2D C/SiC) poses challenges to the investigation of damage failure mechanisms and the prediction of material performance, thereby limiting its further application in aerospace engineering. In this work, static/dynamic short beam shear tests with different densities of 2D C/SiC were carried out. It was observed that high-density specimens with fewer microporous defects exhibited better strength characteristics than those with lower density. Specifically, the shear strength of 2D C/SiC with a density of 2.07 g/cm³ increased by 18.6% compared to that of the specimen with a density of 1.94 g/cm³. The transient hysteresis strengthening effect of materials at high strain rates was discovered through cross scale research methods. It was found that deformation coordination ability of 2D C/SiC under dynamic loading was weaker than that under quasi-static conditions. Moreover, the deformation hysteresis in temporal and spatial distributions induced significant fiber plucking, further accelerating dislocation movement within the internal lattice and thereby enhancing strength of the material. The failure path of materials often follows the direction of pore defects, and stress concentration leads to cracking behavior of fiber bundles. Furthermore, microcracks within the matrix, caused by residual stress, resulted in localized regions of reduced strength. This induced the matrix cracking failure with further crack expansion within the material structure under external loads. To provide technical references for practical engineering applications and design, a realistic and effective finite element prediction model was developed for 2D C/SiC composites based on their structural characteristics.

Enhancement of the Silicon Nanocrystals’ Electronic Structure within a Silicon Carbide Matrix

Using plasma-enhanced chemical vapor deposition (PECVD), a mixed gas of silane (SiH4) and methane (CH4) was diluted with hydrogen (H2) to produce thin films of silicon nanocrystals embedded in a silicon carbide (SiC) matrix. This method prevents the co-deposition of SiH and SiC from high-temperature annealing procedures. This study experimentally explores the improvement of the electronic structure by adjusting two processing parameters according to classical nucleation theory (ratio of SiH4 to CH4 and working gas pressure). The deposited films were examined using ellipsometry spectroscopy, X-ray diffraction, scanning electron microscopy, atomic force microscopy, and photoluminescence to determine grain size, crystal volume fraction, topography, and bond configurations. The results show that increasing the working gas pressure can increase the density of SiC, while increasing the ratio of SiH4 to CH4 can only produce larger grain sizes. This is consistent with how SiC works and grows. Without using a high-temperature annealing procedure, this technique can improve the electrical structure of SiC contained in the SiC matrix formed by PECVD.

Progress of One-Dimensional SiC Nanomaterials: Design, Fabrication and Sensing Applications.

One-dimensional silicon carbide (SiC) nanomaterials hold great promise for a series of applications, such as nanoelectronic devices, sensors, supercapacitors, and catalyst carriers, attributed to their unique electrical, mechanical, and physicochemical properties. Recent progress in their design and fabrication has led to a deep understanding of the structural evolution and structure-property correlation. Several unique attributes, such as high electron mobility, offer SiC nanomaterials an opportunity in the design of SiC-based sensors with high sensitivity. In this review, a brief introduction to the structure and properties of SiC is first presented, and the latest progress in design and fabrication of one-dimensional SiC nanomaterials is summarized. Then, the sensing applications of one-dimensional SiC nanomaterials are reviewed. Finally, our perspectives on the important research direction and future opportunities of one-dimensional SiC nanomaterial for sensors are proposed.

Mechanical and tribological properties of silicon carbide /carbon fiber/epoxy resin based composites

In this contribution, an epoxy resin based composites which synergistically modified by carbon fiber (MCF) and silicon carbide (SiC) particles were prepared. The chemical structure of MCF and SiC before and after surface treated using silane coupling agent were analyzed by Fourier transform infrared spectroscopy and X-ray diffraction, respectively. The mechanical properties including tensile, flexural, and compression of the composites were investigated. Moreover, the friction and wear performances were studied on a ball-on-ring wear tester. The results indicated that the best tensile, compressive, and friction and wear properties of composites were obtained when SiC particles content is 3.0 wt.%. Compared to the pure epoxy resin, when the SiC particles content is 4.0 wt.%, the best flexural strength and modulus were obtained, which increased by 8.7% and 52.97%, respectively. Both the average coefficient of friction (COF) and the wear mass losses of the composites decreased significantly with the addition of the modified SiC particles. In addition, the main wear mechanism of pure EP is adhesive and fatigue wear, while the SiC/MCF/EP composites exhibit abrasive and fatigue wear.

Comparison and Assessment of Different Interatomic Potentials for Simulation of Silicon Carbide.

Interatomic potentials play a crucial role in the molecular dynamics (MD) simulation of silicon carbide (SiC). However, the ability of interatomic potentials to accurately describe certain physical properties of SiC has yet to be confirmed, particularly for hexagonal SiC. In this study, the mechanical, thermal, and defect properties of four SiC structures (3C-, 2H-, 4H-, and 6H-SiC) have been calculated with multiple interatomic potentials using the MD method, and then compared with the results obtained from density functional theory and experiments to assess the descriptive capabilities of these interatomic potentials. The results indicate that the T05 potential is suitable for describing the elastic constant and modulus of SiC. Thermal calculations show that the Vashishta, environment-dependent interatomic potential (EDIP), and modified embedded atom method (MEAM) potentials effectively describe the vibrational properties of SiC, and the T90 potential provides a better description of the thermal conductivity of SiC. The EDIP potential has a significant advantage in describing point defect formation energy in hexagonal SiC, and the GW potential is suitable for describing vacancy migration in hexagonal SiC. Furthermore, the T90 and T94 potentials can effectively predict the surface energies of the three low-index surfaces of 3C-SiC, and the Vashishta potential exhibits excellent capabilities in describing stacking fault properties in SiC. This work will be helpful for selecting a potential for SiC simulations.

QSAR Analysis for the class of silicon carbide structures

Graph theory has many applications in chemistry and is used to analyze molecular structures. Topological descriptors are numerical numbers that contain chemical information and provide structural features of a compound associated with a chemical approach. The purpose of the topological index is to study the physicochemical properties of molecular structures. This paper investigates the molecular graph of 2D silicon carbide structures. The scope of this paper is to determine the highest thermal stability property among silicon carbide structures using topological indices.

A first-principles study of the electronic, vibrational, and optical properties of planar SiC quantum dots

With the reported synthesis of a fully planar 2D silicon carbide (SiC) allotrope, the possibilities of its technological applications are enormous. Recently, several authors have computationally studied the structures and electronic properties of a variety of novel infinite periodic SiC monolayers, in addition to the honeycomb one. In this work, we perform a systematic first-principles investigation of the geometry, electronic structure, vibrational, and optical absorption spectra of several finite, but, fully planar structures of SiC, i.e. 0D quantum dots (QDs). The sizes of the studied structures are in the 1.20–2.28 nm range, with their computed HOMO(H)-LUMO(L) gaps ranging from 0.66 eV to 4.09 eV, i.e. from the IR to the UV region of the spectrum. The H-L gaps in the SiC QDs are larger as compared to the band gaps of the corresponding monolayers, confirming the quantum confinement effects. In spite of covalent bonding in the QDs, Mulliken charge analysis reveals that Si atoms exhibit positive charges, whereas the C atoms acquire negative charges, due to the different electron affinities of the two atoms. Furthermore, a strong structure property relationship is observed with fingerprints both in the vibrational and optical spectra. The wide range of H-L gaps in different SiC QDs makes them well-suited for applications in fields such as photocatalysis, light-emitting diodes, and solar cells.

The effects of helium, strontium, and silver triple ions implanted into SiC

The effects of helium (He), silver (Ag) and strontium (Sr) ions triple implanted into polycrystalline silicon carbide (SiC) were investigated. Ag ions of 360 keV were first implanted into polycrystalline SiC to a fluence of 2 × 1016 cm−2 at 600 °C, followed by implantation of Sr ions of 280 keV to a fluence of 2 × 1016 cm−2 also at 600 °C (Ag + Sr–SiC). Some of Ag + Sr–SiC samples were then implanted with 17 keV He ions to a fluence of 1 × 10 17 cm−2 at 350 °C (Ag + Sr + He–SiC). Some of the dual (Ag + Sr–SiC) and triple (Ag + Sr + He–SiC) implanted samples were annealed at 1000 °C for 5 h. Both dual and triple implantation resulted in the accumulation of defects without amorphization of SiC structure. Moreover, triple implantation also resulted in formation of elongated He nano-bubbles and cavities in the damaged SiC accompanied by the appearance of blisters and craters on the surface. Healing of some structural defects was observed after annealing at 1000 °C in both dual and triple implanted samples. Implantation of Sr caused pre-implanted Ag to form precipitates indicating some limited migration while implantation of He caused some migration of both Ag and Sr. The migration of Ag was accompanied by formation of bigger precipitates trapped in He-cavities. Annealing the triple implanted caused the migration of both Ag and Sr governed by trapping of both implanted species by cavities due to some exo-diffusion of He. No migration was observed in the dual implanted samples annealed at 1000 °C. Hence, He bubbles assisted migration of implants and He cavities trap the implanted species.

Hydrogen production by steam reforming of fusel oil over nickel deposited on pyrolyzed rice husk supports

Fusel oil is mixed alcohol as a by-product of ethanol production, and it can be used as a cheap and renewable source to produce Hydrogen (H2) via steam reforming. Silicon carbide (SiC) was successfully synthesized by pyrolysis of rice husk at different temperatures (1300, 1500, and 1700 °C) and was used as a support for a nickel (Ni) catalyst in steam reforming of fusel oil. The results exhibited pyrolysis temperature had a significant effect on the structure and crystalline phase of SiC, where pyrolysis of rice husk over 1500 °C resulted in the formation of a rod structure and β-SiC phase. The surface area of pyrolyzed rice husk was obtained for 19, 64, and 25 m2/g at pyrolysis temperatures of 1300, 1500, and 1700 °C, respectively. The performance of the Ni on the pyrolyzed rice husk support on steam reforming of fusel oil (SRF) was investigated at 700 °C and compared with Ni on commercial SiC. The Ni/SiC1500 exhibited the highest catalytic performance, and its activity remained almost constant during a 300 min stability test. The H2 yield produced from the Ni/SiC1500 was 29% after 180 min and remained stable because the unique rod structure and β-SiC phase reduced carbon formation, thus giving an excellent performance.

Changes in the Structure and Properties of Silicon Carbide under Gamma Irradiation

The paper presents the results of comprehensive study of SiC samples, which is one of the most promising materials in the field of semiconductor nanotechnology. The identification and qualitative analysis of a SiC sample was carried out by Raman spectroscopy using an In Via Raman spectrometer. Based on the spectrogram of X-ray phase analysis, the amorphous and crystalline phases of this substance were determined. At the same time, according to the peaks of the spectrogram, based on the Miller indices and inter planar distances dhkl, complex compounds are shown that are newly formed on the basis of silicon carbide. Using the method of IR spectroscopy, the IR spectra of SiC were obtained in the optical range ν = 400-4000 cm−1.