σ–π-Band Inversion in a Novel Two-Dimensional Material

Abstract

We present a theoretical study of a new type of two-dimensional material exhibiting a pentagonal arrangement of C and Si atoms. Pentagonal SiC 2 is investigated with density functional theory-based calculations to show that the buckled nano-structure is dynamically stable, exhibits an indirect energy band gap, and an enhanced electronic dispersion with respect to the all-carbon counterpart. Computed Born effective charges exhibit a significant anisotropy for C and Si atoms that deviates substantially from their static effective charges. We establish an accurate tunability of the vertical location of the p-p-σ and p-p-π bands and show that under compressive bi-axial strain the density of states decreases, and conversely for tensile biaxial strain. This study establishes that the coupling between the tunability of strain-mediated density of states and semiconducting properties in a monolayered structure may allow for the development of applications in semiconducting stretchable electronics.

Ultrahigh Sensitivity and Selectivity of Pentagonal SiC2 Monolayer Gas Sensors: The Synergistic Effect of Composition and Structural Topology

“…To investigate the synergistic effect of composition and structural topology, P‐SiC 2 monolayer, graphene, and PG (Figure ) are chosen to compare their adsorption behaviors of various gas molecules. Before studying the structural characteristics and energetics of the adsorption system, we first optimize the lattice constant of the P‐SiC 2 monolayer and obtain a = b = 4.41 Å, which is consistent with the results of previous studies . To find the most advantageous configuration, we have examined different adsorption sites and orientations to adsorb gas molecules, each of which is placed on a 3 × 3 P‐SiC 2 supercell.…”

“…Figure shows the total density of states (DOS) of gas molecules adsorbing P‐SiC 2 monolayer, as well as the partial DOS from the individual gas molecule. The calculated band gap of P‐SiC 2 monolayer is about 1.39 eV, which is consistent with the DFT results of previous studies . However, the band gap obtained from HSE06 calculation is 2.85 eV, because Perdew–Burke–Ernzerhof (PBE) always underestimates the value of the semiconductor band gap.…”

“…Before studying the structural characteristics and energetics of the adsorption system, we first optimize the lattice constant of the P-SiC 2 monolayer and obtain a ¼ b ¼ 4.41 Å, which is consistent with the results of previous studies. [22] To find the most advantageous configuration, we have examined different adsorption sites and orientations to adsorb gas molecules, each of which is placed on a 3 Â 3 P-SiC 2 supercell. Figure 2 shows the most stable configurations of various gas molecules adsorbed on the P-SiC 2 monolayer.…”

“…The composition variation would result into unusual properties of these carbon‐based pentagon structures compared with parent PG. For example, a partial inversion of the vertical ordering of the p–p–σ and p–p–π electronic bands can be found in P‐SiC 2 . Furthermore, P‐SiC 2 has a peculiar distribution of the electronic states, corresponding to in‐plane σ orbitals, in the vicinity of the Fermi level, indicating that it is a sensitive material to a change induced by interactions, such as strain .…”

“…[13] Inspired by these investigations on PG and 2D PdSe 2 , 2D pentagonal materials have attracted increasing attention because of their novel electronic properties and great potential in fundamental studies and applications in nanodevices and functional materials. [14][15][16][17][18][19] In particular, carbon-based pentagon structures have become a new family of carbon-based nanomaterials, wherein the main members include PG, [13,20,21] pentagonal-SiC 2 (P-SiC 2 ), [22] penta-CN 2 , [17] and penta-B 2 C. [23] These thermally and dynamically stable materials have the same structural topology. Isostructural to PG, these 2D carbon-based pentagonal nanosheets can be considered as the derivatives of PG by replacing some carbon atoms with silicon, nitrogen, or boron atoms ( Figure 1).…”