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 cm−2) 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 μF/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.
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机译:在低载流子密度状态下,MoS2中的电荷传输受陷阱态和能带边缘失调的支配。 MoS2的内在传输特性出现在高密度状态,在该状态下,导电通过扩展状态发生。在这里,我们研究了通过离子凝胶顶栅和SiO2背栅的组合实现的机械剥离的单层,双层和三层MoS2片在各种载流子密度上的传输性能,这使我们能够获得高电荷载流子( > 10 13 sup> cm −2 sup>)密度。我们讨论了器件的门控特性随层厚度的变化,并展示了在10 K下单层器件的电阻率低至1kΩ,双层器件的电阻率低至420Ω。我们表明,通过两个栅极的电容耦合,量子电容可以达到对于所研究的所有器件,其粗略估计约为1μF/ cm 2 sup>。高密度条件下载流子迁移率的温度依赖性表明,短程散射体限制了低温下的电荷传输。
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