Electrical characteristics of multilayer MoS₂ transistors at real operating temperatures with different ambient conditions

Atomically thin, two-dimensional (2D) materials with bandgaps have attracted increasing research interest due to their promising electronic properties. Here, we investigate carrier transport and the impact of the operating ambient conditions on back-gated multilayer MoS₂ field-effect transistors with a thickness of ∼50 nm at their realistic working temperatures and under different ambient conditions (in air and in a vacuum of ∼10^-5 Torr). Increases in temperature cause increases in Imin (likely due to thermionic emission at defects), and result in decreased I_on at high V_G (likely due to increased phonon scattering). Thus, the I_on/I_min ratio decreases as the temperature increases. Moreover, the ambient effects with working temperatures on field effect mobilities were investigated. The adsorbed oxygen and water created more defect sites or impurities in the MoS₂ channel, which can lead another scattering of the carriers. In air, the adsorbed molecules and phonon scattering caused a reduction of the field effect mobility, significantly. These channel mobility drop-off rates in air and in a vacuum reached 0.12 cm²/V s K and 0.07 cm²/V s K, respectively; the rate of degradation is steeper in air than in a vacuum due to enhanced phonon mode by the adsorbed oxygen and water molecules.