Top-Gate Atomic-Layer-Deposited Oxide Semiconductor Transistors With Large Memory Window and Non-Ferroelectric HfO₂ Gate Stack

In this work, we demonstrate a top-gate indium-zinc oxide (IZO) transistor with non-ferroelectric HfO2 gate stack but exhibiting a counterclockwise hysteresis loop with large memory window (MW) of 2.7 V and long retention over 10 years. The gate stack capacitor shows non-ferroelectricity in both P-V and C-V measurements. It is understood that oxygen vacancy formation at the O-poor interface is likely to be the origin of the counterclockwise hysteresis loop because the large MW disappears completely after high-temperature O2 annealing. This work suggests that the origin of the memory characteristics in oxide semiconductor ferroelectric field-effect transistors (FeFETs) need to be carefully justified due to the competing mechanism.