Theoretical and experimental investigation on structural and electronic properties of Al/O/Al, O-doped WS₂

Effects of the doping atom (O, Al, and (Al, O)) on structural and electronic properties of the monolayer WS₂ have been studied by using first-principles calculations. Results show that the covalent character of W-S bonding has been enhanced after doping. Meanwhile, W-O, Al-S and W-S bonds of (Al, O) co-doped WS₂ monolayer have higher covalent character compared with O-doped and Al-doped WS₂ monolayer of this work. After doping with Al (or Al, O) atoms, Fermi level moves close to the valence band and the dopant atoms produce the defect energy levels, indicating that Al doped and (Al, O) co-doped WS₂ monolayer both have p-type conductivity. O-doped and (Al, O) co-doped WS₂ ultrathin films was prepared on Si substrates. Results of Raman spectra show the formation of the O-doped and (Al, O) co-doped WS₂ films. Moreover, compared with the pure WS₂, the approximate reduction of 0.43 eV and 0.46 eV for W 4f and S 2p in binding energy after (Al, O) co-doped shows that p-type doping of (Al, O) co-doped WS₂ has been verified.