Electrically tunable metal–semiconductor behavior in 2H-MoTe2

Abstract

In this study, we report tunable metallic and semiconducting behavior in molybdenum di-telluride (2H-MoTe2) by manipulating the Joule heating process through electrical control of the channel current. At low voltages, 2H-MoTe2 exhibits semiconducting behavior. As the current surpasses a critical threshold at higher voltages, the material transitions to a metallic-like state, confirmed by a positive temperature coefficient of resistance. Temperature- and voltage-dependent Raman studies confirm that this semiconducting to metal-like transition occurs without any accompanying structural phase transformation. This metallic behavior is likely due to enhanced phonon scattering caused by the increase in lattice temperature. In the metallic state, exposure to H2 gas results in a negative response, with increased resistance due to additional phonon scattering. Conversely, laser exposure at this state produces no noticeable photoresponse because the already high lattice temperature limits the impact of further heating. These effects were suppressed when 2H-MoTe2 was placed on a hexagonal boron nitride/multilayer graphene heat sink. This dynamic modulation of conductivity in 2H-MoTe2 through electrical stimuli highlights its potential for nanoelectronic device applications.