arXiv subjects

Arushi Singh

Publications and source records attributed to Arushi Singh.

2 recordsLinked to original sources

arXiv2024

Characterization of Silicon Carbide Biphenylene Network through G0W0-BSE Calculations

Two-dimensional silicon carbide stands out among 2D materials, primarily due to its notable band gap, unlike its carbon-based counterparts. However, the binary nature and non-layered structure of bulk SiC present challenges in fabricating its 2D counterpart. Recent advancements in technology have led to the successful synthesis of atomically thin, large-scale epitaxial monolayers of hexagonal-SiC and Si9C15 , marking a significant milestone in semiconductor research. Inspired by these advancements, we have computationally designed another stable phase of 2D-SiC in the popular biphenylene network, termed SiC-biphenylene. This structure is characterized by interconnected polygons of octagons, hexagons, and tetragons arranged periodically. The dynamical and thermal stability has been confirmed through ab initio phonon dispersion and molecular dynamics simulations. The structure demonstrates a high melting point of approximately 3475 K and a direct band gap of 2.16 eV using the HSE06 functional. Upon considering many-body effects, the quasiparticle band gap widens to 2.89 eV at the G0W0 level, indicating pronounced electron correlation effects within the material. The optical spectrum obtained from solving the Bethe-Salpeter equation (G0W0+BSE) identifies the first optically active exciton peak at 2.07 eV, corresponding to a strongly bound exciton with a binding energy of 0.82 eV. Furthermore, the investigation into stable bilayer structures across various stacking configurations highlights the impact of stacking patterns on excitonic binding energies. Our investigation extends to identifying the stable bulk phase of SiC-biphenylene, revealing lower self-energy corrections compared to monolayer and bilayer structures, attributed to increased electron delocalization in bulk structures.

cond-mat.mtrl-sci↗

arXiv2023

Defect-driven tunable electronic and optical properties of two-dimensional silicon carbide

Recently, an atomic-scale two-dimensional silicon carbide monolayer has been synthesized {[}Polley \emph{et al., }Phys. Rev. Lett. \textbf{130},076203 (2023){]} which opens up new possibilities for developing next-generation electronic and optoelectronic devices. Our study predicts the pristine SiC monolayer to have an ``indirect'' band gap of 3.38 eV $(K\rightarrow M)$ and a ``direct'' band gap of 3.43 eV $(K\rightarrow K)$ calculated using the HSE06 functional. We performed a detailed investigation of the various possible defects (i.e., vacancies, foreign impurities, antisites, and their various combinations) on the structural stability, electronic, and optical properties of the SiC monolayer using a first-principles based density-functional theory (DFT) and molecular dynamics (MD) simulations. A number of physical quantities such as the formation energy, electronic band gap, and the effective masses of charge carriers, have been calculated. We report that the SiC monolayer has a very low formation energy of 0.57 eV and can be stabilized on TaC \{111\} film by performing the surface slab energy and interfacial adhesion energy calculations. Nitrogen doping is predicted to be the most favorable defect in silicon carbide monolayer due to its very low formation energy, indicating high thermodynamic stability. An interesting transition from semiconducting to metallic state is observed for $N_{C}$ and $Al_{Si}$ defective systems. For the pristine SiC monolayer, we find that the conduction band is nearly flat in the $M\rightarrow K$ direction, leading to a high effective mass of $3.48m_{o}$. A significant red shift in the absorption edge, as well as the occurrence of additional absorption peaks due to the defects, have been observed in the lower energy range of the spectrum.

cond-mat.mtrl-sci↗