First-principles investigation of the effect of charged unit cell on the electronic structure of two-dimensional MoS2

Abstract

Abstract Density-functional theory has been applied to investigate the effect of charged unit cell on the structural and electronic properties of two-dimensional MoS2 within PBE-GGA. The charge of the unit cell of the monolayer changes from zero to n = ± 4 e with e the absolute value of the elementary electric charge. Variations of the lattice constant, Mo–S bond length, S–Mo–S bond angle, total energy, exchange and correlation contributions, and the Fermi level versus n have been calculated quantitatively, indicating decrease in the stability of the atomic structure of the monolayer with increase in the absolute value of n. It is found that the Fermi level for two-dimensional MoS2 is a function of both the number of electrons in allowed states and the inverse of the volume of the unit cell. The electronic properties of each monolayer have been also calculated via examining the related electronic band structure and density of states. Results broadly support the view that the effect of charged unit cell ( n =+ e to − 4 e ) on the electronic properties of MoS2 monolayer is manifested in the form of semiconductor-to-metal transition in addition to the Fermi level shift. It is also verified that as the negative charge of the unit cell increases from n = − e to − 4 e , there is an ever-increasing trend in the total number of allowed electronic states at the Fermi level, implying a direct correlation between electrical conductivity and the value of n in a way that the more negative the charge of the unit cell, the higher the electrical conductivity of the monolayer.