Structural and electronic properties of effective p-type doping WS2 monolayers: A computational study

Using first-principles calculations within density functional theory, we systematically investigated the structural and electronic properties of Metal (Me = Al, Ga, In, Tl, V, Nb, Ta)-doped WS2 monolayers. The impurity states induced by Me substitutional doping are closed to the valence band, showing the p-type characteristic of Me-doped WS2 monolayers. Among Me dopants, Nb-doped WS2 monolayer has the lowest formation energy and slightly local distortion. Subsequently, the covalent character of WS bond in Nb-doped WS2 monolayer increases compared with pure WS2 monolayer. It is noteworthy that the feature of direct band gap is still presented in (V-Ta)-doped WS2 monolayers, which is very conducive to microelectronic and optoelectronic applications. Therefore, Nb is the appropriate p-type dopant for the WS2 monolayers based on the present work. These findings may prove to be instrumental in the future design of new p-type conducive WS2 monolayers.