Investigation on the dipole distribution at ferroelectric/dielectric interface

Abstract Ferroelectric field-effect transistors (FeFETs) have attracted considerable attention for their potential in non-volatile memory applications. Doped-HfO 2 film is a promising FE material for the application in FeFETs due to its compatibility with complementary metal-oxide-semiconductor (CMOS). However, device reliability remains a critical concern, primarily due to charge trapping behavior that shifts the flat-band voltage (V FB ) and deteriorates electrical performance. This study investigates the dipole formation at the Hf 0.5 Zr 0.5 O 2 /dielectric oxide interface and its impact on band alignment. The band offset affected by dipole at the Hf 0.5 Zr 0.5 O 2 /dielectric oxide (SiO 2 , Y 2 O 3 , SiON, and Al 2 O 3 ) interface is studied using x-ray photoelectron spectroscopy (XPS). The charge neutral level theory is applied to explain the charge transfer behavior and dipole formation at these interfaces. Our results show that negative dipoles are formed at the Hf 0.5 Zr 0.5 O 2 /SiO 2 and Hf 0.5 Zr 0.5 O 2 /Y 2 O 3 interfaces, while positive dipoles arise at the Hf 0.5 Zr 0.5 O 2 /SiON and Hf 0.5 Zr 0.5 O 2 /Al 2 O 3 interfaces. The conduction and valence band offsets between Hf 0.5 Zr 0.5 O 2 and Si change with different dipole distributions. This work will be helpful for understanding the mechanisms of dipole formation and for engineering the reliability optimization of FeFET devices.