Abstract
Monolayer group-III monochalcogenides (MX, M = Ga, In; X = S, Se, Te), an emerging category of two-dimensional (2D) semiconductors, hold great promise for electronics, optoelectronics and catalysts. By first-principles calculations, we show that the phonon dispersion and Raman spectra, as well as the electronic and topological properties of monolayer MX can be tuned by oxygen functionalization. Chemisorption of oxygen atoms on one side or both sides of the MX sheet narrows or even closes the band gap, enlarges work function, and significantly reduces the carrier effective mass. More excitingly, InS, InSe, and InTe monolayers with double-side oxygen functionalization are 2D topological insulators with sizeable bulk gap up to 0.21 eV. Their low-energy bands near the Fermi level are dominated by the px and py orbitals of atoms, allowing band engineering via in-plane strains. Our studies provide viable strategy for realizing quantum spin Hall effect in monolayer group-III monochalcogenides at room temperature, and utilizing these novel 2D materials for high-speed and dissipationless transport devices.
Highlights
We investigate the electronic and topological properties of oxygen functionalized group-III monochalcogenides monolayers including GaS, GaSe, GaTe, InS, InSe, and InTe. First-
Group-III monochalcogenides (MX, M = Ga, In; X = S, Se, Te) are layered semiconductors that have been extensively studied for decades due to their peculiar properties, such as high carrier mobility, sombrero-shape valence band edges, rare p-type electronic behaviors, etc.[1,2]
The double-side oxygen functionalized InS, InSe, and InTe sheets are topological insulators (TI) with large bulk gap up to 0.20 eV opened by spin–orbit coupling (SOC), and the low-energy bands are associated with the s, px, and py atomic orbitals
Summary
We investigate the electronic and topological properties of oxygen functionalized group-III monochalcogenides monolayers including GaS, GaSe, GaTe, InS, InSe, and InTe. First- The double-side oxygen functionalized InS, InSe, and InTe sheets are TIs with large bulk gap up to 0.20 eV opened by spin–orbit coupling (SOC), and the low-energy bands are associated with the s, px, and py atomic orbitals.
Sign-in/Register to view highlights & summary 
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call