Structural and electronic properties of monolayer group III monochalcogenides

Abstract

We investigate the structural, mechanical, and electronic properties of the two-dimensional hexagonal structure of group III-VI binary monolayers, MX (M = B, Al, Ga, In and X = O, S, Se, Te) using first-principles calculations based on the density functional theory. The structural optimization calculations and phonon spectrum analysis indicate that all of the 16 possible binary compounds are thermally stable. In-plane stiffness values cover a range depending on the element types and can be as high as that of graphene, while the calculated bending rigidity is found to be an order of magnitude higher than that of graphene. The obtained electronic band structures show that MX monolayers are indirect band-gap semiconductors. The calculated band gaps span a wide optical spectrum from deep ultraviolet to near infrared. The electronic structure of oxides (MO) is different from the rest because of the high electronegativity of oxygen atoms. The dispersions of the electronic band edges and the nature of bonding between atoms can also be correlated with electronegativities of constituent elements. The unique characteristics of group III-VI binary monolayers can be suitable for high-performance device applications in nanoelectronics and optics.

Spin-orbit coupling, optical transitions, and spin pumping in monolayer and few-layer InSe

“…These experiments have identified two main photoluminescence lines, interpreted 30 as a lower energy transition between bands dominated by s and p z orbitals (A-line) and hot luminescence, involving holes in a deeper valence band based on p x and p y orbitals (B-line). The band structure analysis of mono-and few-layer InSe [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] has revealed that the conduction and valence band edges near the Γ-point are non-degenerate, being dominated by s and p z orbitals of both metal and chalcogen atoms. Combined with the opposite z → −z (mirror reflection) symmetry of conduction and valence bands, this determines that the transition across the principal band gap has a dominantly electric dipole-like character, coupled to out-of-plane polarized photons.…”

Single layers and multilayers of GaN and AlN in square-octagon structure: Stability, electronic properties, and functionalization

“…In the infrared active modes, two N atoms in the same square move in the same direction while in the Raman active modes, the opposite is true. The E u branches with the highest frequencies have striking similarity to the Mexican hat dispersion of the valence band edge of so-structures [45]. Hence, the Mexican hat dispersion that appears both in the electronic and phononic band structures can be interpreted as a fundamental property of interactions in the so geometry.…”

High stability and visible-light photocatalysis in novel two-dimensional monolayer silicon and germanium mononitride semiconductors: first-principles study

“…This defect motivated the search for novel 2D materials. In recent years, some 2D materials, including, but not limited to, black phosphorene (BP), 7 transition-metal dichalogenides (TMDs), [8][9][10] monolayer group IV, 11 monolayer group V, 12,13 and monolayer group III monochalcogenides, 14,15 have been explored. Due to the high carrier mobility and direct band gap, BP is emerging as a contender in the eld of 2D materials.…”