Strain and electric field-modulated indirect-to-direct band transition of monolayer GaInS2

Abstract

Strain and electric eld dependent electronic and optical properties have been calculated using density functional theory (DFT) and time-dependent DFT (TD-DFT) for GaInS 2 monolayer. GaInS 2 monolayer shows an indirect band gap of 1.79 eV where valance band maxima (VBM) and conduction band maxima (CBM) rest between K and Γ point and at Γ point, respectively. Under a particular tensile strain (8%), a phase change from semiconductor to semimetal has been noticed. While at 4% compressive strain, the material changes from indirect to direct band gap of 2.22 eV having VBM and CBM at Γ point. With further increase in compressive strain, CBM shifted from Γ to M point, which leads to an indirect band gap again. The electric eld also affects the band structure of monolayer GaInS 2 and shows the transition between indirect to direct band gap at positive electric eld of 4 V/nm, which acts normal to the surface. The strain-dependent optical properties are also calculated, which suggests that the absorption coe cient increases with compressive strain.

A Strategic Comparison Between Monolayers of WX2N4(X≐Si, Ge) Toward Thermoelectric Performance and Optoelectronic Properties.

“…The peaks in the absorption spectra (Figure 6c) were found at 3.34 eV and 2.12 eV with α of 4.54 × 10 5 /cm and 1.24 × 10 5 /cm for WSi 2 N 4 , and WGe 2 N 4 , respectively, and they matches with some previously reported results. [ 32,33 ] Some secondary peaks are also found near 4.5 eV for WSi 2 N 4 and 4.0 eV for WGe 2 N 4, where the absorption is much higher. The variation of η as a function of energy is shown in Figure 6d.…”

Influence of an External Electric Field on Electronic and Optical Properties of a g-C3N4/TiO2 Heterostructure: A First-Principles Perspective

“…Compared with other methods, the method of EF modification has the advantages of no chemical addition, easy operation, and no secondary pollution. Numerous studies have shown that external EF can modulate the electronic properties of many nanoscale materials. − Jia et al found that the electronic properties of GaTe/CdS heterostructures can be significantly modified by the external EF, and the material gradually shows metallicity when the EF is large enough. Saini et al investigated the effect of EF and strain upon the optical properties of monolayers of GaX (X = Sb, N, As, P) and the electronic properties.…”