Electric field control of Rashba spin splitting in 2D NIIIXVI (N = Ga, In; X = S, Se, Te) monolayer

Angle-Dependent Raman Spectra of Crystal Polymorphs of GaO: A Computational Study

Two crystal polymorphs of GaO consisting of GaO-H and GaO-T monolayers are proposed in this study. Based on the density functional theory calculations, the phonon dispersion demonstrates that both GaO-H and GaO-T monolayers could be stable. The band gaps of GaO-H and GaO-T monolayers are 1.51 and 1.43 eV, respectively. When an external electric field is applied, the band gaps of GaO monolayers are reduced dramatically, down to 0.13 eV with the field of 0.7 V/Å. Because of the decreased symmetry of C3v under an external electric field, more peaks of Raman spectra can be obtained. The angle-dependent Raman spectra ofA ' 1 1 ${{\rm{A}}{{^\prime}}_1^1 }$ andA ' 1 2 ${{\rm{A}}{{^\prime}}_1^2 }$ of GaO-H monolayer, andA 1 g 1 ${{\rm{A}}_{1{\rm{g}}}^1 }$ andA 1 g 2 ${{\rm{A}}_{1{\rm{g}}}^2 }$ of GaO-T monolayer are discussed seperately, with the incident lasers of 488 and 532 nm. Additionally, the Raman intensity distribution shows that the incident light should be parallel to the plane of the GaO monolayer to obtain more comparable Raman spectra. These investigations of the crystal polymorphs of GaO monolayers may guide the experimental investigations of GaO monolayers and potential optoelectronic applications.

Probing Strain-Induced Effects on Performance of Low-Dimensional Hybrid Perovskites for Solar Energy Harvesting

The application of strain to photovoltaics (PVs), thermoelectrics (TEs), and semiconductors often has substantial impacts on the fundamental properties governing the efficiency of these materials. In this work, we investigate two stable phases of hybrid organic-inorganic two-dimensional (2D) perovskites (2DPKs) and their response to the application of tensile and compressive strain of up to 5%. These 2D MAPbI₃ analogues are known to exhibit strongly anisotropic properties and have been put forward as excellent candidates for application in mixed PV-TE devices. Our results, stemming from ab initio density functional theory calculations and investigation of transport properties through the Boltzmann transport equations, further elucidate the key properties contributing to the success of these materials. In particular, both the M1 and M2 phases exhibit stable structures between -5 and 5% biaxial strains. The M2 phase exhibits an excellent 23.8% power conversion efficiency under the application of 5% tensile strain. Furthermore, we analyze the effects of spin-orbit coupling on the band structures of both phases, revealing great potential for spintronic applications with the M2 phase, demonstrating Rashba coefficients up to 3.67 eV Å.

Sorption studies of sulfadimethoxine and tetracycline molecules on β-antimonene nanotube - A first-principles insight

We ascertained the structural firmness of β-antimonene nanotube and studied the adsorption behaviour of sulfadimethoxine (SM) and tetracycline (TC) molecules on the base substrate using density functional theory (DFT) with B86LYP-D3 level of theory. Significantly, β-antimonene nanotube displays a semiconducting character with an energy band-gap of 0.263 eV. The three dissimilar preferential adsorption sites namely, bride-, hollow-, tube-inner site of SM and TC molecules on β-antimonene nanotube were investigated using average band gap changes, Bader charge transfer along with adsorption energy. Further, the calculated adsorption energy for preferential adsorption sites is noticed to be in the scope of -0.813 eV to -3.752 eV signifying to physisorption and chemisorption form of interaction on β-antimonene nanotube. The inclusive outcome recommends that β-antimonene nanotube can be deployed as a chemi-resistive sensor to sense and remove SM and TC molecules from the contaminated aqueous medium.

The electrical and spin properties of monolayer and bilayer Janus HfSSe under vertical electrical field

In this paper, the electrical and spin properties of mono- and bilayer HfSSe in the presence of a vertical electric field are studied. The density functional theory is used to investigate their properties. Fifteen different stacking orders of bilayer HfSSe are considered. The mono- and bilayer demonstrate an indirect bandgap, whereas the bandgap of bilayer can be effectively controlled by the electric field. While the bandgap of bilayer closes at large electric fields and a semiconductor to metal transition occurs, the effect of a normal electric field on the bandgap of the monolayer HfSSe is quite weak. Spin-orbit coupling causes band splitting in the valence band and Rashba spin splitting in the conduction band of both mono- and bilayer structures. The band splitting in the valence band of the bilayer is smaller than a monolayer, however, the vertical electric field increases the band splitting in bilayer one. The stacking configurations without mirror symmetry exhibit Rashba spin splitting which is enhanced with the electric field.