Hf0.4Zr0.6O2 Thickness-Dependent Transfer Characteristics of In x Zn1-x O y Channel Ferroelectric FETs

초록

We investigate how the threshold voltage (V-T) is adjusted to create a memory window (MW) in ferroelectric field-effect transistors (FeFETs) composed of ferroelectric Hf0.4Zr0.6O2 and InZnO (In2O3:ZnO = 9:1 wt %). Temperature-dependent polarization measurements reveal a dipole switching in Hf0.4Zr0.6O2. The properties of the n-type InZnO channel are examined by fabricating an oxide transistor with an HfO2 gate dielectric. Upon replacement of HfO2 with Hf0.4Zr0.6O2 in the oxide transistor, a counterclockwise MW is observed. Specifically, as the Hf0.4Zr0.6O2 thickness increases from 16 to 24 nm, the V-T of the FeFET after a + gate voltage (V-G) sweep remains nearly constant, while the V-T after a -V-G sweep shifts significantly from -0.9 to 0.5 V. The enlarged MW of approximately 2 V, which is proportional to the Hf0.4Zr0.6O2 thickness in the FeFET, can be explained by considering the balance between V-G controllability across the gate stack and the ferroelectric switching of Hf0.4Zr0.6O2.

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