Theoretical analysis of the HfS2 monolayer electronic structure and optical properties under vertical strain effects

In this paper, the HfS2 monolayer electronic structure and optical properties under vertical strains are theoretically explored using density functional theory (DFT) calculations. The HfS2 single layer dynamical stability is examined by calculating the phonon dispersion curves. Based on our simulation, the studied two-dimensional (2D) material is an indirect gap semiconductor with band gap value of 1.545 eV. The band gap engineering can be effectively realized by applying the vertical strains. In this regard, the indirect-direct gap transition in the monolayer at hand may be induced by compressive strains with strength from 9%. Consequently, significant changes of the optical properties may be obtained, in particular when visible to middle ultraviolet regime radiation is incident on the sample. The HfS2 monolayer displays promising optoelectronic applicability with a high absorption coefficient reaching to 49.600 (10(4)/cm) and 88.122 (104/cm) in the visible and ultraviolet regime, respectively. Results may suggest an effective approach to modify the optoelectronic properties of the HfS2 single layer at the time of designing its practical applications.