Manipulation of bilayer MoS2-based MESFET with flexoelectric polarization field

We propose a bilayer MoS2-based metal-semiconductor field-effect transistor (MESFET) with the characteristic of mechanical modulation of its performance through flexoelectricity. The MESFET sample is fabricated with the bilayer MoS2 and the Si/SiO2 substrate as well as the gate electrode of Pt and the source/drain electrode of Ag/Au. The current-voltage relationships of the fabricated MESFET under the action of different gate voltages and tip forces as well as their combinations are measured with AFM. The tip force produces a strain gradient induced flexoelectric polarization field and thus changes the effective barrier height of Schottky contact. As a result, it can serve as an equivalent gate voltage, playing a significant tuning role in the performance such as transconductance and carrier mobility of the proposed MESFET. Within the drain-source voltage (VDS) range of 0 to 2 V, the maximum carrier mobility of the fabricated MESFET under the combined action of traditional gate voltage (VGS) and tip force reach 470 cm-2/(V∙s) significantly higher than that under VGS alone. The study provides valuable insights into the application of flexoelectricity in MESFET devices based on two-dimensional materials.