InGaZnO thin-film transistors with YHfZnO gate insulator by solution process

Thin-film transistors (TFTs) with the indium gallium zinc oxide (IGZO) as a channel layer and the yttrium hafnium zinc oxide (YHZO) as a gate insulator layer were fabricated and both of layers were deposited by solution process. YHZO solution was prepared by dissolving yttrium nitrate, hafnium chloride, and zinc acetate into 2-methoxyethanol with additional stabilizers. The spin coating and annealing procedures were repeated several times to obtain sufficient thickness for gate insulator in IGZO TFTs. The electrical characteristics of YHZO films were analyzed by capacitance-voltage and leakage current measurements. The dielectric constant was about 16.4 and leakage current density was about 6×10 ^-8 A/cm ². In solutionprocessed IGZO TFTs with YHZO gate insulator, the field effect mobility, the on-to-off current ratio, the threshold voltage, and the subthreshold swing were 0.29 cm ²/Vs, ̃10 ⁵, 3.47 V, and 1.26 V/decade, respectively.