P‐1.11: High‐mobility ZnO thin‐film transistors with HfO2/Al2O3 bilayer dielectric

We investigate high‐performance ZnO thin‐film transistors (TFTs) with a HfO 2 /Al 2 O 3 bilayer high‐κ gate dielectric. The effects of atomic layer deposition process temperature (80, 100, 120, and 140 °C) of Al 2 O 3 dielectric layer on device performance of ZnO TFTs are examined. When the process temperature is at 100 °C, the devices show the best electrical properties, such as a field‐effect mobility of 34.12 cm 2 /Vs, a subthreshold swing of 105.70 mV/decade, and an on‐off current ratio over 10 8 . Besides, of all the devices, TFTs with 100 °C‐Al 2 O 3 show the best stability with 0.2 and –0.1 V threshold voltage shift under positive and negative gate‐bias stress, which may probably due to the high‐quality interface between the active layer and dielectric layer. This work presents great potential of the ZnO TFTs in applications of advanced displays.