The Structure, Electronic, Magnetic and Optical Properties of the Mn-X (X = B, C, N and O) Co-Doped Monolayer WS2

Abstract

To expand the potential application of monolayer WS2 systems, the structure, electronic, magnetic and optical properties of pure and Mn-X (X = B, C, N and O) co-doped monolayer WS2 systems are theoretically studied using first-principles methods based on the density function theory. The pure monolayer WS2 system is a nonmagnetic semiconductor with a direct band gap E g of 1.82 eV, and the Mn-B and Mn-N co-doped monolayer WS2 systems remain of nonmagnetic semiconducting character with smaller band gaps $$ E_{\rm{g}} $$ of 1.09 eV and 0.84 eV, respectively. While the Mn-C and Mn-O co-doped monolayer WS2 systems exhibit magnetic semiconducting characters with a total magnetic moment $$ M_{\rm{tot}} $$ of 1 $$ \mu_{\rm{B}} $$ , and spin-up gaps $$ E_{\rm{g}}^{ \uparrow } $$ (spin-down gaps $$ E_{\rm{g}}^{ \downarrow } $$ ) of 0.54 (1.17) eV and 0.61 (1.44) eV, respectively. Although the pure monolayer WS2 system has the highest transmittance in the low energy region, the Mn-B co-doped monolayer WS2 system has the highest static dielectric constants $$ \varepsilon_{1} (0) $$ and $$ \varepsilon_{2} (0) $$ , reflectivity $$ r(0) $$ , refractive indices $$ n(0) $$ and $$ k(0) $$ . Meanwhile, the Mn-X (X = B, C, N and O) co-doped monolayer WS2 systems are more suitable to make infrared photodetector due to their red-shift phenomenon. In particularly, the Mn-B co-doped monolayer WS2 system becomes of great interest to researchers since the absorption edge shifts to the mid-infrared spectral region.