Electron Confinement at the Si/MoS2 Heterosheet Interface

The electronic band line-up between a uniform 2D silicon layer and a MoS2 substrate is shown to result in a distortion of the MoS2 bands. This effect is reflected in the admittance and electrical transport responses measured from the field-effect transistor incorporating the Si/MoS2 heterosheet interface and fabricated from MoS2 multilayer flakes on SiO2/Si++ substrates. In particular, the gate modulation of the capacitance curve and the observation of a double-peak feature in the transconductance profile make evidence of the built-in of two active channels in the transistor: one at the MoS2/SiO2 interface and the other at the Si/MoS2 heterosheet interface. The emergence of a gate modulated conductive channel at the Si/MoS2 heterosheet interface is rationalized in terms of an effective electron accumulation at the Si/MoS2 interface that is consistent with the electronic band bending deduced from high-resolution synchrotron radiation photoemission spectroscopy.