Electrical Properties of Solution-Processed Nanolaminates of ZrO2 and Al2O3 as Gate Insulator Materials for Thin-Film Transistors

We investigated the electrical properties of solution-processed nanolaminates composed of zirconium oxide (ZrO2) and aluminum oxide (Al2O3) as gate insulator materials for thin-film transistors (TFTs). We fabricated MOS capacitors using Al2O3/ZrO2/Al2O3 and ZrO2/Al2O3/ZrO2 nanolaminate stacks through solution processing. The fabricated nanolaminates showed low leakage current densities and high dielectric constants. Also, solution-processed InSnZnO (ITZO) TFTs were fabricated on nanolaminates. Among these devices, the Al2O3/ZrO2/Al2O3 stack showed the best performance in terms of its switching operation, with a high on/off current ratio (>10(6)), high mu(sat) (0.28 cm(2)/Vs), and low subthreshold swing (0.25 V/dec). The superior characteristics of these nanolaminates originated from the high dielectric constant of ZrO2 (>20) and the high band gap energy of Al2O3 (8.9 eV), which generates a large band offset between the gate insulator and active layer to effectively block the leakage current.