Electronic band structures and optical properties of atomically thin AuSe: first-principle calculations

Abstract

As a large family of 2D materials, transition metal dichalcogenides (TMDs) have stimulated numerous works owing to their attractive properties. The replacement of constituent elements could promote the discovery and fabrication of new nano-film in this family. Using precious metals, such as platinum and palladium, to serve as transition metals combined with chalcogen is a new approach to explore novel TMDs. Also, the proportion between transition metal and chalcogen atoms is found not only to exist in conventional form of 1 : 2. Herein, we reported a comprehensive study of a new 2D precious metal selenide, namely AuSe monolayer. Based on density functional theory, our result indicated that AuSe monolayer is a semiconductor with indirect band-gap of 2.0 eV, which possesses superior dynamic stability and thermodynamic stability with cohesive energy up to –7.87 eV/atom. Moreover, it has been confirmed that ionic bonding predominates in Au–Se bonds and absorption peaks in all directions distribute in the deep ultraviolet region. In addition, both vibration modes dominating marked Raman peaks are parallel to the 2D plane.

Single-Layer Zirconium Dihalides ZrX2 (X = Cl, Br, and I) with Abnormal Ferroelastic Behavior and Strong Anisotropic Light Absorption Ability

“…Upon increasing interlayer distance, the E cl would increase up to a saturated value of ∼0.295 J/m 2 (Figure S1). This value is smaller than many other well-known 2D materials, such as graphene (0.37 J/m 2 ), SL black phosphorus (∼0.4 J/m 2 ), and BiI 3 (0.43 J/m 2 ), suggestive of the feasibility of mechanical exfoliation for ZrX 2 monolayers. The phonon spectra of the ZrX 2 monolayer show that there are no imaginary frequencies in the phonon spectra, indicating the dynamical stability of ZrX 2 monolayers (Figure S2).…”

Two-Dimensional Gold Halides: Novel Semiconductors with Giant Spin–Orbit Splitting and Tunable Optoelectronic Properties

“…Considering the SOC effect, a very large splitting of ∼1.1 eV is observed in CBM. For comparison, SOC induces a CBM shift by only ∼0.3 eV in AuSe monolayers. ,, This is probably the largest SOC-induced effect ever reported for 2D materials. Meanwhile, the band gaps are drastically decreased by ∼60% compared to that without SOC.…”

“…Many 2D noble metal dichalcogenides have been exfoliated experimentally, and their electronic structures have been widely studied, revealing tunable thickness-dependent band gaps and optical properties. − Special attention in the recent two years paid to Au mono- and dichalcogenides has revealed their stability, giant magnetoresistance, high carrier mobility, and promising optical properties. − However, 2D noble metal halides (such as AuBr and AuI) are surprisingly still only little studied, with much more theoretical and experimental possibilities unrevealed. In addition, little is known about their bulk phases.…”

Tuning the Electronic and Optical Properties of the Novel Monolayer Noble-Transition-Metal Dichalcogenides Semiconductor β-AuSe via Strain: A Computational Investigation

“…In order to verify the accuracy of the calculated results, the HSE06 hybrid functional method [38,39] with high precision was employed to calculate the electronic and optical properties. Based on previous studies, we know that the spin-orbit coupling (SOC) effect only shrinks the calculated band gap slightly [26,[31][32][33]. Therefore, in our study, the electronic and optical properties of monolayer β-AuSe were calculated without the SOC effect.…”

“…In the same year, Bai et al used the DFT method to study the structural properties and band structure of β-AuSe. The β-AuSe showed excellent dynamic and thermodynamic stability, and its formation energy reached −7.87 eV/atom [31]. In 2020, Tang et al calculated the in-plane anisotropy of ultra-high carrier mobility for β-AuSe using ab initio calculation.…”