Fabrication of Zinc Oxide Transparent Thin-Film Transistor with ZrO₂Insulating Layer by Sol–Gel Method

A thin-film transistor consisting of a ZnO active layer and a ZrO 2 insulating layer was fabricated on a tin-doped indium oxide sputtered glass substrate as well as on a SiO 2 /Si wafer. The ZnO and ZrO 2 layers were deposited by a sol–gel, dip-coating procedure. The resultant ZrO 2 layer was about 150 nm thick and the ZnO layer 70 nm thick. The ZnO layer consisted of a single-grain thickness while the ZrO 2 layer consisted of about 10 nm grains and was rather porous. The multilayered film consisting of ZnO/ZrO 2 /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/ZrO 2 /SiO 2 /Si wafer was also examined and the behavior of the thin-film transistor was confirmed. The ZrO 2 layer deposited on the SiO 2 /Si wafer minimized leakage through the insulating layer.