Anodization-induced ZrO _x /AlO _x stacked films for low-temperature, solution-processed indium oxide thin-film transistors

Abstract

Abstract In this study, anodization is introduced to induce dehydroxylation and condensation of solution-processed ZrO x films as well as growth of AlO x films. The anodization-induced ZrO x /AlO x stacked films are systematically studied in structure, surface morphology, density, chemical composition, dielectric and electrical properties. X-ray diffraction and atomic force microscopy reveal that anodization-induced ZrO x /AlO x stacked films exhibit amorphous structure and smooth surface roughness (<1 nm). X-ray reflectivity and x-ray photoelectron spectroscopy reveal that the solution-processed ZrO x films exhibit a higher density and a lower content of hydroxyl groups after anodization, suggesting the anodization can induce dehydroxylation and condensation for the ZrO x films. The synergistic effect of collision inducing dissociation and the self-heating from anodization of Al film is proposed to explain the dehydroxylation of the ZrO x films. Dielectric and electrical measurements illustrate that the anodization-induced ZrO x /AlO x stacked films exhibit a lower leakage current, a higher breakdown voltage and a slighter capacitance dispersion on frequency comparing with that of solution-processed ZrO x films without anodization. To verify the possible applications of anodization-induced ZrO x /AlO x stacked films as the gate dielectric in metal-oxide (MO) thin-film transistors (TFTs), they were integrated in low-temperature, directly photopatternable InO x TFTs. Remarkably, with a low process temperature of 200 °C, the InO x TFTs based on the optimized ZrO x /AlO x dielectrics exhibit an average mobility of 8.94 cm 2 V −1 s −1 , an I on / I off of large than 10 5 and negligible hysteresis in transfer curves. These results demonstrate the potential application of anodization-induced solution-processed MO dielectric films for low-temperature TFTs.