Fabrication of Zinc Oxide Transparent Thin-Film Transistor with ZrO₂ Insulating Layer by Sol–Gel Method

A thin-film transistor consisting of a ZnO active layer and a ZrO₂ insulating layer was fabricated on a tin-doped indium oxide sputtered glass substrate as well as on a SiO₂/Si wafer. The ZnO and ZrO₂ layers were deposited by a sol–gel, dip-coating procedure. The resultant ZrO₂ layer was about 150 nm thick and the ZnO layer 70 nm thick. The ZnO layer consisted of a single-grain thickness while the ZrO₂ layer consisted of about 10 nm grains and was rather porous. The multilayered film consisting of ZnO/ZrO₂/ITO/glass was transparent with 60–85% transmittance in the visible region and exhibited characteristics of a field-effect transistor. The multilayered film of the ZnO/ZrO₂/SiO₂/Si wafer was also examined and the behavior of the thin-film transistor was confirmed. The ZrO₂ layer deposited on the SiO₂/Si wafer minimized leakage through the insulating layer.