Figure 6. Ambipolar dual-gated BP-FETs.

(a) Optical image of 7-nm thick dual-gated (top and bottom) device. (b) Fully symmetric dual-gated FET operation. The applied displacement field has no influence on device polarity. Scale bar, 5 μm. (c) 2-Terminal mobilities measured via the V_tg sweep. Mobility saturation is observed and electron–hole transport symmetry is retained, although peak values increased by 45 cm² V⁻¹ s⁻¹ compared with pre-Al₂O₃ measurement in Fig. 4c. Inset shows the device schematic from a. Al₂O₃ dielectric thickness is 50 nm and SiO₂ thickness is 300 nm. (d) Peak mobility for electrons (squares) and hole (circles) branches of the curves in c, plotted as a function of D, normalized to a thickness of 7 nm. (e) No clear directional dependences are observed for I_ds at both 300 K (solid) and 80 K (dotted).