Silicon Carbide Nanostructures Research Articles

Temperature-Dependent Formation of Carbon Nanodomains in Silicon Oxycarbide Glass-A Reactive Force Field MD Study.

Novel anode materials for lithium-ion batteries (LIBs) are constantly being explored to further improve battery performance. In this work, ReaxFF molecular dynamics (MD) simulations are performed to model the early stages in the synthesis of nanostructured silicon carbide (SiC), which is one such promising material. The focus lies on its precursor, silicon oxycarbide glass of composition (Si5O8C16) x (17 mol% Si, 28 mol% O, and 54 mol% C), in the following referred to as SiOC. The structure of the amorphous material is characterized via NPT MD simulations at temperatures ranging from 300 to 1000 K. To this end, a graph theoretical approach is employed to quantify the formation of segregated carbon nanodomains in the solid. Three algorithms for detecting nearest neighbors in the amorphous solid, a crucial prerequisite for the assembly of an atomic connectivity graph, are compared. It is shown that the temperature-dependent carbon aggregation follows an exponential trend, largely independent of the neighbor detection method. Also, the effects of variations in elemental composition are explored. Furthermore, the calculated powder X-ray diffraction patterns of the equilibrated silicon oxycarbide glasses are in good agreement with experimental measurements.

(Invited) Agricultural Waste Derived Anodes for Lithium and Sodium Ion Batteries

Hard or turbostratic carbon anodes are most often derived from thermolysis of biomass in oxygen free environments and considerable data has been accrued to suggest that low specific surface area HC offers the most stable materials for lithiation and sodiation. As part of our efforts to valorize rice hull ash (RHA, 90 wt % SiO2/8 wt % C), produced in 150k ton/yr in the U.S. alone; we learned to first distillatively remove excess SiO2 to produce silica depleted RHA or SDRHA40-70 (40-70 wt.% SiO2).1 The resulting materials are nanocomposites of carbon and SiO2 intermixed at nm length scales.2 The SDRHA carbon can be used as a reductant, and because of the very small diffusion distances, SDRHAxxcan be carbothermally reduced to electronics grade silicon (SiPV, 5’9’s purity)3 or SiC (Ar) or Si2N2O (90N2/10H2) or Si3N4 (N2) at much lower temperatures (1250°-1500 °C)4 than those used to produce the same materials commercially and at higher purities. At certain ratios, HC is a coproduct also intimately mixed with the major silicon containing material.We have previously found that SiC/HC mixtures can serve as anode materials (coin cells) offering capacities of ≈ 950 mAh/g after long term cycling. This usually is with HC contents of just 10-15 wt. %. In this talk we explore increasing the ratio of HC:SiC via carbothermal reduction of lower wt. % SiO2:C ratios in SDRHA40 to assess the effects on LIB capacity and rates of change and as time permits, sodium ion battery (NIB) properties. References (1) Laine, R. M.; Furgal, J. C.; Doan, P.; Pan, D.; Popova, V.; Zhang, X. Avoiding Carbothermal Reduction: Distillation of Alkoxysilanes from Biogenic, Green, and Sustainable Sources. Angew. Chem. Int. Ed. 2016, 55 1065–1069. https://doi.org/10.1002/anie.201506838.(2) Mengjie Yu; Eleni Temeche; Richard M. Laine. M. Yu, E. Temeche, R. M. Laine, Methods of Adjusting Carbon and Silica Content in Rice Hull Ash (RHA) Byproducts to Control Carbothermal Reduction Forming Nanostructured Silicon Car-Bide, Silicon Nitride, Silicon Oxynitride Nanocomposites,” Provisional Patent Application Filed Sept. 5, 2020.(3) Marchal, J. C.; Krug III, D. J.; McDonnell, P.; Sun, K.; Laine, R. M. A Low Cost, Low Energy Route to Solar Grade Silicon from Rice Hull Ash (RHA), a Sustainable Source. Green Chem. 2015, 17 (7), 3931–3940. https://doi.org/10.1039/C5GC00622H.(4) Temeche, Eleni; Yu, Mengjie; Laine, R. M. Silica Depleted Rice Hull Ash (SDRHA), an Agricultural Waste, as a High-Performance Hybrid Lithium-Ion Capacitor. Green Chemistry 2020, 22, 4656–4668.

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.

Hydrogen-designed spin-states of 2D silicon carbide and graphene nanostructures.

Identifying and manipulating spin in two-dimensional materials is of great interest in advancing quantum information and sensing technologies, as well as in the development of spintronic devices. Here, we investigate the influence of hydrogen adsorption on the electronic and magnetic properties of graphene-like triangulenes. We have constructed triangulenes from SiC monolayers, which have been successfully synthesized very recently, extending our investigation to include graphene triangulenes. This advancement in the synthesis of SiC monolayers allows us to investigate deeper into the unique properties of SiC-based triangulenes and compare them with their graphene counterparts. The addition of hydrogen has been found to induce a magnetic moment in the SiC monolayer, with a more localized spin density when H is adsorbed in the C sites while spreading through the lattice when adsorbed on the Si sites. In triangular flakes, the ground spin state changes with the adsorption site: decreasing multiplicity on edge-defined sublattices and increasing it on the opposite sublattice. These findings suggest hydrogen adsorption as a tool for tuning spin-state properties in SiC and graphene nanostructures, with potential applications in spintronics and spin quantum dot devices.

Advancements in silicon carbide-based supercapacitors: materials, performance, and emerging applications.

Silicon carbide (SiC) nanomaterials have emerged as promising candidates for supercapacitor electrodes due to their unique properties, which encompass a broad electrochemical stability range, exceptional mechanical strength, and resistance to extreme conditions. This review offers a comprehensive overview of the latest advancements in SiC nanomaterials for supercapacitors. It encompasses diverse synthesis methods for SiC nanomaterials, including solid-state, gas-phase, and liquid-phase synthesis techniques, while also discussing the advantages and challenges associated with each method. Furthermore, this review places a particular emphasis on the electrochemical performance of SiC-based supercapacitors, highlighting the pivotal role of SiC nanostructures and porous architectures in enhancing specific capacitance and cycling stability. A deep dive into SiC-based composite materials, such as SiC/carbon composites and SiC/metal oxide hybrids, is also included, showcasing their potential to elevate energy density and cycling stability. Finally, the paper outlines prospective research directions aimed at surmounting existing challenges and fully harnessing SiC's potential in the development of next-generation supercapacitors.

Chemical Functionalization of Silicon Carbide Nanotube (SiCNT): First Principles DFT Study

In this study, a functionalized nano drug carrier design based on (5,5) silicon carbide nanotube and functional groups such as amine (−NH2), hydroxyl (−OH), and carboxylic acid (−COOH) were investigated using the first principles’ density functional theory. The critical need for a smart nanocarrier system aims to increase the concentration of medications to the particular tissues of interest with minimal toxicity to the patient. The simulations are carried out using Quantum ATK-Atomistic Simulation Software. The negative binding energy and the total energy difference obtained by optimization through random perturbation ensure the stability of the structures SiCNT and SiCNT-(X/2X) (X = −OH, −NH2, and −COOH). The energy bandgap obtained for the pristine structure is 1.99 eV indicating their indirect bandgap semiconducting characteristics. In comparison to SiCNT, the energy bandgap of SiCNT-(X/2X) structures decreases within a range of 0.06 eV to 1.95 eV, respectively. Partial charges and p-character were used to understand the nature of bonds between the nanotube and the functional moiety. The chemical potential analysis favors a blue shift of SiCNT-(X/2X) with respect to SiCNT. The higher values of ionic character and solvation energy predicts the solubility of nanostructures in the aqueous medium. In comparison to all analyzed systems, the findings of the ionic character, solvation, and sensing mechanism indicate SiCNT-(2NH2) system to be most favorable drug delivery nanocarrier. These findings suggest that increasing the concentration of −NH2 functional groups on the side wall of silicon carbide nanotubes helps to develop a promising and efficient targeted drug delivery system to deliver specific molecular cargo to the cells mitigating toxicity associated with nanotubes, thereby enhancing the outcomes of cancer treatment. Furthermore, surface functionalization of silicon carbide nanostructures could improve their potential solubility parameterized by higher values of dipole moment and solvation energy together with enhanced biocompatibility leading to the desired therapeutic effect.

The synergistic and reinforcement mechanism of SiC nanostructures on the ablation properties of silicone rubber composites

With improvements to the performance of ramjets, the ablation environment in afterburning chambers has become more severe, leading to an urgent demand for high-performance thermal protection materials (TPMs). In this study, the reinforcing effects of silicon carbide (SiC) nanowhiskers and nanopowders on silicone rubber composites and their synergistic effects were investigated. Both SiC nanowhiskers and nanopowders improved the thermal stability of the TPMs. SiC nanowhiskers enhanced the thermal conductivity of the TPMs by forming thermal conductivity pathways. Furthermore, SiC nanofillers can reinforce the ablation resistance of the TPM. The best performance was demonstrated by the TPM formulated with five parts SiC nanowhiskers and five parts SiC nanopowders. The ablation rate was reduced by 72.7% relative to the TPM with a basic formulation, and the back temperature increased by only 27.1%. In this study, the SiC nanofiller improved the ablation resistance of composites by densifying the pore structure and strengthening the skeleton of the char layer. Furthermore, the more compact char layer improved the thermal conductivity of the composites. The increase in the thermal conductivities of the composites and the char layer led to a decrease in the thermal insulation properties of the composites.

Experimental Study on Femtosecond Laser Processing Performance of Single-Crystal Silicon Carbide

Femtosecond laser processing technology offers a promising technique for the preparation of micro and nanostructures of single-crystal silicon carbide (SiC), thanks to its high precision and non-destructive processing. However, further research is needed to optimize processing parameters, as well as improve efficiency and quality of the process. This study conducts experiments to explore the effects of femtosecond laser ablation on single-crystal SiC. The influence and significance of parameters, such as fluence (F), repetition rate, scan speed (S), multipass scanning (c) and numerical aperture on the performance of grooves, including groove depth, groove width, heat-affected zone (HAZ) width, material removal rate (MRR) and side wall inclination angle, were studied. The results show that the influence of fluence and numerical aperture on groove depth, groove width, HAZ width, MRR and side wall inclination angle is very significant. The scan speed has a very significant effect on the groove depth, groove width, HAZ width and side wall inclination angle but has insignificant effect on the MRR. Repetition rate and multipass scanning have a very significant effect on groove depth, HAZ width, MRR and side wall inclination angle and a moderately significant effect on groove width. The experimental methods of increasing the aspect ratio and reducing the HAZ width were studied, and a significance analysis was carried out. Fluence, multipass scanning and z-layer feed have significant effects on groove depth, groove width, aspect ratio, HAZ width and MRR. The influence of polarization angle on groove depth, groove width, aspect ratio and MRR is insignificant.

Surface morphology effects on the mechanical and electronic properties of halogenated porous 3C-SiC: A DFT study

Silicon carbide nanostructures have been widely studied due to their potential technological applications. However, the theoretical characterization, especially the effect of the surface on the mechanical properties of this material is still underexplored. In this work, we report the electronic and mechanical properties of 3C-SiC nanopores with different pore surfaces and different passivation schemes using a density functional theory approach and the supercell technique. The nanopores were modeled by removing columns of atoms in the [001] direction, thus creating four types of pores, two with an Only C or Si pore and two with a C or Si-Rich pore surface. All surfaces were passivated with hydrogen, then some atoms of H were replaced with fluorine and chlorine. Results show that pores with a higher concentration of C on the surface have a larger bandgap compared with the Si cases. Moreover, only a few changes can be observed due to passivation. For the mechanical properties the Bulk and Young’s modulus were calculated and show that the Only C structures were the most brittle and, for almost all the pores, the H + Cl passivation improve the Bulk modulus.

Recent Progress in SiC Nanostructures as Anode Materials for Lithium- Ion Batteries

Abstract: Large volume variation during charge/discharge of silicon (Si) nanostructures applied as the anode electrodes for high energy lithium-ion batteries (LIBs) has been considered the most critical problem, inhibiting their commercial applications. Searching for alternative high performance anodes for LIBs has been emphasized. Silicon carbide (SiC) nanomaterials, a wide bandgap semiconductor with excellent mechanical properties, have been investigated as anode electrode materials even as active materials, protective layers, or inactive buffer stuff. In this mini review, we briefly summarize the synthesis of SiC nanostructures, the application of SiC/C anode materials, and SiC/Si composite anodes in LIBs.

Silicon Carbide Nanostructures as Potential Carbide Material for Electrochemical Supercapacitors: A Review.

Silicon carbide (SiC) is a very promising carbide material with various applications such as electrochemical supercapacitors, photocatalysis, microwave absorption, field-effect transistors, and sensors. Due to its enticing advantages of high thermal stability, outstanding chemical stability, high thermal conductivity, and excellent mechanical behavior, it is used as a potential candidate in various fields such as supercapacitors, water-splitting, photocatalysis, biomedical, sensors, and so on. This review mainly describes the various synthesis techniques of nanostructured SiC (0D, 1D, 2D, and 3D) and its properties. Thereafter, the ongoing research trends in electrochemical supercapacitor electrodes are fully excavated. Finally, the outlook of future research directions, key obstacles, and possible solutions are emphasized.

Production of graphitic carbons from plant-based SiC/C nanocomposites for Li-ion batteries

Barley husks are a byproduct of grain processing produced in large volumes globally. They contain a large amount of nanostructured silica (nSiO2) which can be converted via magnesiothermic reduction into carbon-rich nanostructured silicon carbide composite (nSiC/C). The nSiC/C can be further utilized as a precursor for the production of graphitic carbons (GCs) under atmospheric pressure at 2400 °C, typically utilized as active material in Li-ion battery (LIB) anodes. However, the current synthesis of graphite utilizes fossil-based precursors and requires temperatures up to 3000 °C. Therefore, we propose the sustainable and renewable plant-based GCs as an alternative anode material for LIBs. The synthesized GCs demonstrated a fully crystalline 3D carbon structure with stacking faults between graphene layers. Particle morphology, carbon structure, and elemental composition of the GCs were not influenced by the amount of free carbon in the precursors but the yield (11–41 wt%) of the GCs increased with increasing content of free carbon (1–26 wt%) in the SiC/C composite. The GC material had a specific capacity of 294 mAh g−1 as an active anode material in LIBs, demonstrated significantly better capacity retention at high current rates (1 and 2 C) compared with commercial graphite, and withheld 80% of the specific capacity over 175 cycles at 1 C. Synthesis of GCs from barley husks may provide an advantageous route of valorization of this underutilized sidestream.

SO2 sensing mechanism of nanostructured SiC-SiOxC core shell: An operando DRIFT investigation

The possible use of nanostructured silicon carbide for the manufacturing of chemiresistive gas sensors with high selectivity towards sulfur dioxide has been recently explored. In this work, we take this topic a step further with an in-depth investigation on the role played by the oxidation process occurring on the surface of silicon carbide nanoparticles during the detection of SO2. This study starts by understanding the oxidation process at different temperatures and subsequently investigates the reaction mechanism of SO2, in both dry and wet atmosphere, at the optimal working temperature for the sensor operation. The device was characterized using a diffuse reflectance infrared Fourier transform spectroscopy setup capable of working in operando conditions with a dedicated electronics for the simultaneous monitoring of surface chemical reactions on the sensing film together with its electrical activity. This work demonstrates that the oxidation of silicon carbide nanoparticles is at the core of the modification of the overall electrical characteristics of the device. It was also proved that the exposure to SO2 increases the oxidation rate of the silicon carbide film in working conditions. Moreover, it was observed that this behavior is magnified by the presence of humidity.Finally, a proposed sensing mechanism is suggested highlighting a mainly ionic electrical conduction, in which working conditions play a fundamental role in affecting the concentration and mobility of charge carriers.

Magnetically-supported electrically-induced formation of silicon carbide nanostructures on silicon substrate for optoelectronics applications

Magnetically-supported electrically-induced formation of silicon carbide nanostructures on silicon substrate for optoelectronics applications

Structures, Electronic Properties, and Gas Permeability of 3D Pillared Silicon Carbide Nanostructures.

Silicon carbide (SiC) is recognized as excellent material for high power/temperature applications with a wide-band gap semiconductor. With different structures at the nanosize scale, SiC nanomaterials offer outstanding mechanical, physical, and chemical properties leading to a variety of applications. In this work, new 3D pillared SiC nanostructures have been designed and investigated based on self-consistent charge density functional tight-binding (SCC-DFTB) including Van der Waals dispersion corrections. The structural and electronic properties of 3D pillared SiC nanostructures with effects of diameters and pillar lengths have been studied and compared with 3D pillared graphene nanostructures. The permeability of small gas molecules including H2O, CO2, N2, NO, O2, and NO2 have been demonstrated with different orientations into the 3D pillared SiC nanostructures. The promising candidate of 3D pillared SiC nanostructures for gas molecule separation application at room temperature is highlighted.

Nanoscale limit of the thermal conductivity in crystalline silicon carbide membranes, nanowires, and phononic crystals

Silicon carbide (SiC) aims to be the number one material for power microelectronics due to its remarkable thermal properties. Recent progress in SiC technology finally enabled the fabrication of crystalline SiC nanostructures. Yet, the thermal properties of SiC at the nanoscale remain overlooked. Here, we systematically study heat conduction in SiC nanostructures, including nanomembranes, nanowires, and phononic crystals. Our measurements show that the thermal conductivity of nanostructures is several times lower than that in bulk and that the values scale proportionally to the narrowest dimension of the structures. In the smallest nanostructures, the thermal conductivity reached 10% of that in bulk. To better understand nanoscale thermal transport in SiC, we also probed phonon mean free path and coherent heat conduction in the nanostructures. Our theoretical model links the observed suppression of heat conduction with the surface phonon scattering, which limits the phonon mean free path and thus reduces the thermal conductivity. This work uncovers thermal characteristics of SiC nanostructures and explains their origin, thus enabling realistic thermal engineering in SiC microelectronics.

Terahertz emission from silicon carbide nanostructures

For the first time, electroluminescence detected in the middle and far infrared ranges from silicon carbide nanostructures on silicon, obtained in the framework of the Hall geometry. Silicon carbide on silicon was grown by the method of substitution of atoms on silicon. The electroluminescence from the edge channels of nanostructures is induced due to the longitudinal drain- source current. The electroluminescence spectra obtained in the terahertz frequency range, 3.4, 0.12 THz, arise due to the quantum Faraday effect. Within the framework of the proposed model, the longitudinal current induces a change in the number of magnetic flux quanta in the edge channels, which leads to the appearance of a generation current in the edge channel and, accordingly, to terahertz radiation. Keywords: silicon carbide on silicon, terahertz emission, electroluminescence, nanostructure, quantum Faraday effect.

Registration of terahertz irradiation with silicon carbide nanostructures

The response to external terahertz (THz) irradiation from the silicon carbide nanostructures prepared by the method of substitution of atoms on silicon is investigated. The kinetic dependence of the longitudinal voltage is recorded at room temperature by varying the drain-source current in the device structure performed in a Hall geometry. In the frameworks of proposed model based on the quantum Faraday effect the incident radiation results in the appearance of a generated current in the edge channels with a change in the number of magnetic flux quanta and in the appearance of features in the kinetic dependence of the longitudinal voltage. The generation of intrinsic terahertz irradiation inside the silicon carbide nanostructures is also revealed by the electrically-detected electron paramagnetic resonance (EDEPR) measured the longitudinal voltage as a function of the magnetic field value. Keywords: silicon carbide on silicon, terahertz irradiation, nanostructure, electrically-detected EPR, quantum Faraday effect.

Advances in Nanostructured Silicon Carbide Photocatalysts

Advances in Nanostructured Silicon Carbide Photocatalysts

The Study of Optical and Electrical Properties of Nanostructured Silicon Carbide Thin Films Grown by Pulsed-Laser Deposition

In this paper, nanostructured silicon carbide (SiC) thin films are deposited onto glass substrate using pulsed laser deposition technique. Electrical and optical characterizations such as conductivity, resistivity, transmission, Seeback effect, absorption, absorption coefficient, energy band gap, and extinction coefficient as a function of photon energy, and the effect of thin films thickness on transmission are carried out to characterize the prepared samples. Results showed that the prepared SiC thin film is an n-type semiconductor with an indirect bandgap of ~3 eV, 448 nm cutoff wavelength, 3.4395 × 104 cm−1 absorption coefficient and 0.154 extinction coefficient. The surface morphology of the SiC thin films is studied using scanning electron microscope at a substrate temperature of 400 °C and it is found that the grain size of the prepared SiC thin film is about 30 nm. As such, the nano thin films optical and structural characteristics enable the films to be used as gases sensors in many optoelectronic devices such as the environment and ultraviolet photodiode.