Band structure and magnetism engineering of InSe monolayers through doping with IVA- and VA-group atoms: role of impurities

In this work, we investigate the electronic and magnetic properties of the InSe monolayer enriched by doping with IVA-group (Si and Ge) and VA-group (P and As) atoms. Both In and Se sublattices are considered as doping sites to realize n- and p-type doping (X_In@InSe and X_Se@InSe systems, X = Si, Ge, P, and As), respectively. The pristine InSe monolayer is an indirect gap semiconductor with a band gap of 1.41 eV. n-Doping processes preserve the monolayer's nonmagnetic nature. IVA-group impurities lead to monolayer metallization, while a considerable band gap reduction is induced by doping with VA-group atoms. The band gap also decreases considerably when realizing p-type doping with IVA-group atoms. In contrast, monolayer magnetization is achieved by p-type doping when replacing Se atoms with P and As atoms, leading to the formation of new 2D magnetic semiconductors. In these cases, VA-group impurities mainly produce the system's magnetism. Furthermore, our calculations also provide evidence for the emergence of magnetism in the InSe monolayer through doping with pair impurities (pX@InSe systems), where Si2/Ge2 (incorporated at the Se sublattice) and P1/As1 (incorporated at the In sublattice) dopant atoms play a key role in determining the electronic and magnetic properties of respective pair-atom-doped systems. Herein, the magnetic semiconductor nature of pSi@InSe and pGe@InSe systems is confirmed, while pAs@InSe is found to be a half-metallic system. Our results suggest the usefulness of doping with IVA- and VA-group atoms that can serve as an effective strategy to functionalize the InSe monolayer, providing insights into the role of impurities.