Performance enhancement in InZnO thin-film transistors with compounded ZrO2-Al2O3 nanolaminate as gate insulators

We fabricated compounded ZrO2-Al2O3 nanolaminate dielectrics by the atomic layer deposition (ALD) and used them to successfully integrate the high-performance InZnO (IZO) thin-film transistors (TFTs). It is found that nanolaminate dielectrics combine the advantages of constituent dielectrics and produce TFTs with improved performance and stability compared to single-layer gate insulators. The mobility in IZO-TFT was enhanced about 22% by using ZrO2-Al2O3 gate insulators and the stability was also improved. The transfer characteristics of IZO-TFTs at different temperatures were also investigated and temperature stability enhancement was observed for the TFT with ZrO2-Al2O3 nanolaminates as gate insulators. A larger falling rate (∼1.45 eV/V), a lower activation energy (Ea, ∼1.38 eV) and a smaller density-of-states (DOS) were obtained based on the temperature-dependent transfer curves. The results showed that temperature stability enhancement in InZnO thin-film transistors with ZrO2-Al2O3 nanolaminate as gate insulators was attributed to the smaller DOS.