Low-Voltage Depletion-Mode Indium-Tin-Oxide Thin-Film Transistors Gated by Ba_0.4Sr _0.6TiO₃ Dielectric

We report on the fabrication and characterization of low-voltage indium-tin-oxide (ITO) thin-film transistors (TFTs) gated by Ba_0.4Sr_0.6TiO₃ (BST) gate dielectric deposited at room temperature. The 400-nm-thick BST film shows a low leakage current density of 6× 10^-8 A/cm² and a high specific capacitance of 83 nF/cm² (corresponding ε_r=37). The ITO TFTs gated by such BST dielectric operate in a depletion mode with an operation voltage of 5.0 V. The device exhibits a threshold voltage of -3.7 V, a subthreshold swing of 0.5 V/decade, a field effect mobility of 3.2 cm²/Vs and a current on/off ratio of 1.4× 10⁴.