Charge transport in ion-gated mono-, bi-, and trilayer MoS² field effect transistors

Charge transport in MoS₂ in the low carrier density regime is dominated by trap states and band edge disorder. The intrinsic transport properties of MoS₂ emerge in the high density regime where conduction occurs via extended states. Here, we investigate the transport properties of mechanically exfoliated mono-, bi-, and trilayer MoS₂ sheets over a wide range of carrier densities realized by a combination of ion gel top gate and SiO₂ back gate, which allows us to achieve high charge carrier (>10¹³ cm²²) densities. We discuss the gating properties of the devices as a function of layer thickness and demonstrate resistivities as low as 1 kω for monolayer and 420 ω for bilayer devices at 10 K. We show that from the capacitive coupling of the two gates, quantum capacitance can be roughly estimated to be on the order of 1 mu;F/cm² for all devices studied. The temperature dependence of the carrier mobility in the high density regime indicates that short-range scatterers limit charge transport at low temperatures.