Exfoliated multilayer MoTe2 field-effect transistors

Abstract

The properties of multilayer exfoliated MoTe₂ field-effect transistors (FETs) on SiO₂ were investigated for channel thicknesses from 6 to 44 monolayers (MLs). All transistors showed p-type conductivity at zero back-gate bias. For channel thicknesses of 8 ML or less, the transistors exhibited ambipolar characteristics. ON/OFF current ratio was greatest, 1 $\times$ 10⁵, for the transistor with the thinnest channel, 6 ML. Devices showed a clear photoresponse to wavelengths between 510 and 1080 nm at room temperature. Temperature-dependent current-voltage measurements were performed on a FET with 30 layers of MoTe₂. When the channel is turned-on and p-type, the temperature dependence is barrier-limited by the Au/Ti/MoTe₂ contact with a hole activation energy of 0.13 eV. A long channel transistor model with Schottky barrier contacts is shown to be consistent with the common-source characteristics.