Electrically stable low voltage operating ZnO thin film transistors with low leakage current Ni-doped Ba0.6Sr0.4TiO3 gate insulator

We report on the fabrication of low-voltage ZnO thin-film transistors using 1% Ni-doped Ba0.6Sr0.4TiO3 as the gate insulator. The Ni-doped BST, deposited by RF magnetron sputtering at room temperature, significantly reduced leakage current density to less than 6 x 10(-9) A/cm, as compared to a current density of 5 x 10(-4) A/cm for undoped BST films at 0.5 MV/cm. The ZnO thin-film transistor with the Ni-doped BST gate insulator exhibited a very low operating voltage of 4 V. The field-effect mobility, the current on/off ratio and subthreshold swing were 2.2 cm(2) V/s, 1.2 x 10(6), and 0.21 V/dec respectively.