Defect engineering of two-dimensional (2D) materials offers an unprecedented route to increase their functionality and broaden their applicability. In light of the recent synthesis of the 2D Silicon Carbide (SiC), a deep understanding of the effect of defects on the physical and chemical properties of this new SiC allotrope becomes highly desirable. This study investigates 585 extended line defects (ELDs) in hexagonal SiC considering three types of interstitial atom pairs (SiSi-, SiC-, and CC-ELD) and using computational methods like Density Functional Theory, Born-Oppenheimer Molecular Dynamics, and Kinetic Monte-Carlo (KMC). Results show that the formation of all ELD systems is endothermic, with the CC-ELD structure showing the highest stability at 300 K. To further characterize the ELDs, simulated scanning tunneling microscopy (STM) is employed, and successfully allow identify and distinguish the three types of ELDs. Although pristine SiC has a direct band gap of 2.48 eV, the presence of ELDs introduces mid-gap states derived from the p orbitals at the defect sites. Furthermore, our findings reveal that the ELD region displays enhanced reactivity towards hydrogen adsorption, which was confirmed by KMC simulations. Overall, this research provides valuable insights into the structural, electronic, and reactivity properties of ELDs in hexagonal SiC monolayers and paves the way for potential applications in areas such as catalysis, optoelectronics, and surface science.
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http://dx.doi.org/10.1039/d3cp04267g | DOI Listing |
Materials (Basel)
November 2024
Condensed Matter Physics Section, Physics Department, National and Kapodistrian University of Athens, Panepistimiopolis, 15784 Athens, Greece.
We theoretically investigated the electron-surface optical phonon interaction across the long-range Fröhlich coupling in monolayer transition metal dichalcogenides, such as WS, WSe, MoS, and MoSe monolayers, on SiC and hexagonal BN dielectric substrates. We employed the effective Hamiltonian in the K+(K-) valley of the hexagonal Brillouin zone to assess the electronic energy shifts induced by the interaction between electronic states and surface polar optical phonons. Our results indicate that the interaction between electrons and surface optical phonons depends upon the polar nature of the substrate.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
November 2024
Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, 100190, Beijing, P. R. China.
The transfer-free character of graphene growth on Silicon Carbide (SiC) makes it compatible with state-of-the-art Si semiconductor technologies for directly fabricating high-end electronics. Although significant progress has been achieved in epitaxial growth of graphene on SiC recently, the underlying nucleation mechanism remains elusive. Here, we present a theoretical study to elucidate graphene near-equilibrium nucleation on Si-terminated hexagonal-SiC(0001) surface.
View Article and Find Full Text PDFUltramicroscopy
December 2024
National Research University of Electron Technology (MIET), Zelenograd 124498, Moscow, Russia.
The structural studies of two-dimensional (2D) van der Waals heterostructures and understanding of their relationship with the orientation of crystalline substrates using transmission electron microscopy (TEM) presents a challenge in developing an easy-to-use plan-view specimen preparation technique. In this report, we introduce a simple approach for high-quality plan-view specimen preparation utilizing a dual beam system comprising focused ion beam and scanning electron microscopy. To protect the atomically thin 2D heterostructure during the preparation process, we employ an epoxy layer.
View Article and Find Full Text PDFACS Appl Mater Interfaces
October 2024
Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States.
Ceramic matrix composites (CMCs) have played a significant role in increasing the efficiency of gas turbine engines. CMCs combine the high temperature resistance of ceramics with the high mechanical strength of ceramic fibers into a single unit. Interphase layers are a crucial component in CMCs, as they prevent ceramic fibers from oxidation and introduce strengthening mechanisms into the composite.
View Article and Find Full Text PDFRSC Adv
August 2024
School of Nuclear Science and Technology, University of South China Hengyang Hunan China
Four-layer hexagonal silicon carbide (4H-SiC) is a promising material for high-temperature and radiation-rich environments due to its excellent thermal conductivity and radiation resistance. However, real 4H-SiC crystals often contain Shockley-type stacking faults (SSF), which can affect their radiation resistance. This study employed molecular dynamics (MD) simulation method to explore the effects of SSF on radiation displacement cascades in 4H-SiC.
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