Structural, electronic and optical properties of monolayer InGeX3 (X = S, Se, Te) by first-principles calculations

Abstract

Abstract Recently, two-dimensional materials have attracted enormous attentions for electronic and optoelectronic applications owing to their unique surface structures and excellent physicochemical properties. Herein, the structural, electronic and optical properties of a series of novel monolayer InGeX3 (X = S, Se, Te) materials are investigated systematically by means of comprehensive first-principles calculations. All these three materials exhibit hexagonal symmetries and dynamical stabilities with no imaginary phonon mode. For monolayer InGeX3 (X = S, Se, Te), there exist obvious In–X ionic bonds and the partially covalent interactions of Ge–Ge and Ge–X. By using the HSE06 method, the band gaps of monolayer InGeX3 are predicted to 2.61, 2.24 and 1.80 eV, respectively. Meanwhile, the p-s orbital hybridizations are happened between X and In atoms in the conduction band regions and their interactions become smaller with the increase of X atomic number. In addition, the dielectric function, absorption coefficient and reflectivity spectra of monolayer InGeS3, InGeSe3 and InGeTe3 show the strong optical peaks along the in-plane direction in the UV light region. The definite bandgaps and optical properties make monolayer InGeX3 (X = S, Se, Te) materials viable candidates for future electronic and optoelectronic applications.