HfZrO Thickness-Dependent Transfer Characteristics of InZnO Channel Ferroelectric FETs.

We investigate how the threshold voltage () is adjusted to create a memory window (MW) in ferroelectric field-effect transistors (FeFETs) composed of ferroelectric HfZrO and InZnO (InO:ZnO = 9:1 wt %). Temperature-dependent polarization measurements reveal a dipole switching in HfZrO. The properties of the n-type InZnO channel are examined by fabricating an oxide transistor with an HfO gate dielectric. Upon replacement of HfO with HfZrO in the oxide transistor, a counterclockwise MW is observed. Specifically, as the HfZrO thickness increases from 16 to 24 nm, the of the FeFET after a + gate voltage () sweep remains nearly constant, while the after a - sweep shifts significantly from -0.9 to 0.5 V. The enlarged MW of approximately 2 V, which is proportional to the HfZrO thickness in the FeFET, can be explained by considering the balance between controllability across the gate stack and the ferroelectric switching of HfZrO.