Ambipolar molybdenum diselenide field-effect transistors: field-effect and Hall mobilities

We report a room temperature study on the electrical response of field-effect transistors (FETs) based on few-layered MoSe2, grown by a chemical vapor transport technique, mechanically exfoliated onto SiO2. In contrast to previous reports on MoSe2 FETs electrically contacted with Ni, MoSe2 FETs electrically contacted with Ti display ambipolar behavior with current on to off ratios up to 10(6) for both hole and electron channels when applying a small excitation voltage. A rather small hysteresis is observed when sweeping the back-gate voltage between positive and negative values, indicating the near absence of charge "puddles". For both channels the Hall effect indicates Hall mobilities μH ≃ 250 cm(2)/(V s), which are comparable to the corresponding field-effect mobilities, i.e., μFE ∼ 150 to 200 cm(2)/(V s) evaluated through the conventional two-terminal field-effect configuration. Therefore, our results suggest that MoSe2 could be a good candidate for p-n junctions composed of a single atomic layer and for low-power, complementary logic applications.