Amorphous In2O3 FeFET-like devices by interface dipoles

Abstract

Counterclockwise (CCW) hysteresis with a memory window (MW) of 2.4 V is observed in amorphous indium oxide (a-In2O3) thin-film transistors with silicon oxide (SiOX) gate insulator (40 nm). This CCW phenomenon is due to the dipole formation between the a-In2O3 channel and the SiOX gate insulator by relocating oxygen atoms under the influence of the applied electric field. Hence, bipolar switching of gate bias (VGS) alters the dipole direction and leads to low (VTL) and high (VTH) threshold voltages. The dipole formation increases with the electric field, which can be tailored by gate oxide (SiOX) thickness or gate bias (VGS). Therefore, the devices with a gate oxide thickness of 200 nm initially showed the clockwise hysteresis at VGS of 2 V, transformed to the CCW (MW of 4.2 V) with an increase in gate bias to 14 V. Therefore, a difference in oxygen density at the interface can form a dipole to exhibit the CCW phenomenon and behave FeFET-like.