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

Abstract

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 Ion at high VG (likely due to increased phonon scattering). Thus, the Ion/Imin 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.