Hopping conduction in p-type MoS_2 near the critical regime of the metal-insulator transition

摘要

We report on temperature-dependent charge and magneto transport of chemically doped MoS_2, p-type molybdenum disulfide degenerately doped with niobium (MoS_2:Nb). The temperature dependence of the electrical resistivity is characterized by a power law, ρ(T) ～ T~(-0.25), which indicates that the system resides within the critical regime of the metal-insulator (M-I) transition. By applying high magnetic field (～7 T), we observed a 20% increase in the resistivity at 2 K. The positive magnetoresistance shows that charge transport in this system is governed by the Mott-like three-dimensional variable range hopping (VRH) at low temperatures. According to relationship between magnetic-field and temperature dependencies of VRH resistivity, we extracted a characteristic localization length of 19.8 nm for MoS_2:Nb on the insulating side of the M-I transition.