Quantum spin Hall insulators in functionalized arsenene (AsX, X = F, OH and CH₃) monolayers with pronounced light absorption

Abstract

The search for new two-dimensional topological insulators (2D-TIs) with large band gaps is of great interest and importance. Our first-principles calculations predicted three candidates for 2D-TIs, arsenene functionalized with F, OH and CH3 groups (AsX, X = F, OH and CH3), which preserved large bulk band gaps from 100 to 160 meV (up to 260 meV) derived from the spin-orbit coupling (SOC) within the px,y orbitals. This picture is similar to what was reported for an AsH monolayer with a band gap of 193 meV. Ab initio molecular dynamic (AIMD) simulations demonstrated the thermal stabilities of the AsX monolayers even at 500 K. The nontrivial topological phase was confirmed by the topological invariant Z2 and topological edge state. The topological electronic bandgap of the AsF monolayer can be effectively modulated by biaxial tensile strain and vertical external electric field. In addition, pronounced light absorption in the near-infrared and visible range of the solar spectrum was expected for the AsX (X = H, F) monolayers from the adsorption peaks at 0.45-1.6 eV, which is attractive for light harvesting. The nontrivial quantum spin Hall (QSH) insulators AsX could be promising candidates for practical room-temperature applications in dissipationless transport devices and photovoltaics.

Emerging novel electronic structure in hydrogen-Arsenene-halogen nanosheets: A computational study

“…We first calculated the structural parameters of pristine arsenene, double-side hydrogenated arsenene, and double-side halogenated arsenene to ensure the following investigations, as listed in Table 1, which are in good agreement with previous works 25, 26, 28, 31 . In contrast to the pristine buckled arsenene, H-As-X sheets are nearly planar structure and the symmetry group has changed from D 3 D-3 to C 3 V-1, with the optimized geometry structures shown in Fig.…”

“…Since stronger band dispersion is found in H-As-X sheets than in pristine arsenene, we deduce that H-As-X sheets may possess a higher hole mobility than pristine arsenene. In analogy to that the states of other double-side decorated arsenenes near the Fermi level mainly are attributed to p x and p y orbitals of As atoms 25, 27, 30, 31 , the states of H-As-X sheets near the Fermi level are also primarily composed of p x and p y orbitals of As atoms, due to the fact that the p z orbital of As atoms are passivated by H and X atoms (see Fig. 4).…”

“…Interestingly, it is observed that all of the H-As-X sheets have a direct band gap, i.e., 179 meV, 85 meV, 103 meV, 95 meV, which is substantially different from other double-side decorated arsenenes 25, 26, 28, 30 , as shown in Fig. 3a.…”

“…Furthermore, the oxidation behavior of arsenene has also been explored to verify the properties in ambient air 18, 24 . More recently, some studies have revealed that the double-side decorated arsenene, such as AsCH3, AsOH, AsH, and AsX (X is halogen), exhibits Dirac character and unique 2D topological insulator property, and all of them are decorated by the same functional groups on both sides of arsenene in an alternating manner 25–31 . However, to the best of our knowledge, the different functional groups co-decorated arsenene and multilayer decorated arsenene sheets have remained almost unexplored.…”

Unconventional band inversion and intrinsic quantum spin Hall effect in functionalized group-V binary films

“…Such manipulation not only facilitates the regulation of electronic and topological properties, but also protects the desirable properties from environmental degradation. Recently, intensive efforts have implemented on functionalized group-V films 31, 33, 35–40 which can readily achieve intrinsic nontrivial topology and shows classic Kane-Mele-type QSH effect. However, the topological mechanism of these systems is still a mystery topic to be further explored and understood.…”