The ambipolar evolution of a high-performance WSe₂ transistor assisted by a ferroelectric polymer

In recent years, the electrical characteristics of WSe₂ field-effect transistors (FETs) have been widely investigated with various dielectrics. Among them, being able to perfectly tune the polarity of WSe₂ is meaningful and promising work. In this work, we systematically study the electrical properties of bilayer WSe₂ FETs modulated by ferroelectric polymer poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)). Compared to traditional gate dielectric SiO₂, the P(VDF-TrFE) can not only tune both electron and hole concentrations to the same high level, but also improve the hole mobility of bilayer WSe₂ to 265.96 cm²V^-1s^-1 under SiO₂ gating. Its drain current on/off ratio is also improved to 2 ×10⁵ for p-type and 4 ×10⁵ for n-type driven by P(VDF-TrFE). More importantly, the ambipolar behaviors of bilayer WSe₂ are effectively achieved and maintained because of the remnant polarization field of P(VDF-TrFE). This work indicates that WSe₂ FETs with P(VDF-TrFE) gating have huge potential for complementary logic transistor applications, and paves an effective way to achieve in-plane p-n junctions.