Low-voltage ZnO thin-film transistors with high-K Bi_1.5Zn_1.0Nb_1.5O₇ gate insulator for transparent and flexible electronics

We report on the fabrication of field-effect transistors with transparent oxide semiconductor ZnO serving as the electron channel and high-K Bi_1.5Zn_1.0Nb_1.5O₇ (BZN) as the gate insulator. The devices exhibited very low operation voltages (≪4 V) due to high capacitance of the BZN dielectric. The field effect mobility and the current on/off ratio were 0.024 cm²/V s and 2×10⁴, respectively, at an operating voltage of 4 V. The threshold voltage and subthreshold swing were 2 V and 0.25 V/dec, respectively. The high optical transparency (≫80% for wavelength ≫400 nm), low-temperature processing, and low operation voltage of ZnO-based thin-film transistors with integrated BZN dielectric offer a promising route for the development of transparent and flexible electronics.