First-principles calculations of the band gap and optical properties of germanium sulfide

Phosphorene analogues: Isoelectronic two-dimensional group-IV monochalcogenides with orthorhombic structure

“…1, the Pcmn structure can be regarded as a distorted cubic NaCl structure, and the dispersion of the bands near the gap, mostly with s character, is little affected by the symmetry breaking, specially in plane. The nearly isotropic behavior of ǫ is in agreement with previous calculations, [48,51] but at variance with experimental data for GeS [47]. This may be due to the difficulty in performing measurements with the electric field polarization perpendicular to the layers.…”

Self-consistent calculations of deep Sn and Se vacancy levels in SnSe by the Green’s function method

“…The wave functions of the states localized in the gap consist mainly of p-type orbitals localized on the nearest neighbors, whereas the states localized around V E -12.5 eV in the valence band gap consist mainly of the s-type orbitals localized on the nearest neighbors. This is in agreement with the fact that the upper part of the SnSe valence band consists mainly of the p-type cation and anion states, and its lower part consists mainly of the anion s-states [9,14]. The wave functions of all localized states decay exponentially with increasing distance from the defect.…”

“…The А 4 В 6 type semiconductor compounds draw attention of researchers [8,9] as crystals with strong anisotropy of their chemical bonds and physical properties. GeSe, GeS, SnSe, and SnS layered semiconductors crystallizing in the orthorhombic structure with 16 2h D space symmetry group are considered as intermediate between quasi-twodimensional and three-dimensional crystals.…”

Ab initiocalculations of pressure-induced structural phase transitions of GeTe

“…This transition path is frequently observed for IV-VI compounds such as GeS, SnS, and GeSe. 13,[25][26][27] First, the structural and electronic properties are investigated for the rhombohedral, NaCl, and CsCl structures, where the first two are the structures at ambient conditions and the last is the high-pressure phase. The rhombohedral structure, which is the distorted NaCl structure and the equilibrium phase at low temperatures, has two internal parameters, the angle and the displacement, that characterize the distortion from the NaCl phase.…”