Thermal annealing effects on the electrophysical characteristics of sputtered MoS2 thin films by Hall effect measurements

Abstract

Transition-metal dichalcogenide (MoS2) is gaining increasing attention as a promising high-performance material in practical applications because of its wide-range electrical properties. However, the effect of thermal annealing on the electrophysical characteristics of MoS2 remains unclear. In this study, the physical and electrophysical properties of MoS2 thin films were characterized by Hall effect measurements. Large-area and high-quality MoS2 thin films were obtained by RF sputtering and then subjected to ex situ thermal annealing. As the thermal annealing temperature was increased, the crystallinity of the MoS2 thin films improved and the corresponding Fermi level shifted toward the valence band. At thermal annealing temperatures above 900 °C, the conductivity type of the MoS2 thin films changed from the intrinsic n-type to p-type due to the emergence of MoO3. In addition, the orientation of the Hall coefficient was indefinite under thermal annealing, implying the electrical transport anisotropy of the MoS2 thin films, which can be attributed to the spin–orbit coupling of the exposed Mo atoms in the films with sulfur vacancies. Furthermore, the Hall mobility and carrier concentration of the annealed MoS2 thin films were up to 4.40 cm2 V−1 s−1 and 12.5 × 1016 cm−3, respectively, at a Hall testing temperature of 305 K and an external magnetic field of 0.5 T.