Composition and optoelectrical properties of sputtering MoSe_x films

Influence of sputtering pressure on composition, optical and electrical properties of amorphous MoSe_x films has been systematically investigated. The highest Se concentration and nearly stoichiometric ratio Se/Mo in MoSe_x films were observed at a sputtering pressure of 0.3 Pa. When the sputtering pressure is increased, the binding energies of Mo 3d and Se 3d peaks of the MoSe_x films increase, the blue shift of optical transmission edge is observed and the optical band gap decreases from 0.92 to 0.78 eV. Additionally, Hall mobility decreases first and then increases slightly, the resistivity of the films decreases, whereas the carrier concentration of the films increases with an increase in sputtering pressure. The MoSe_x films deposited at 0.3 Pa have larger Hall mobility (6.45 cm² V^-1 s^-1) and higher optical band gap (0.92 eV) because of lower Se vacancy defect concentration.