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.