Threshold Voltage Modulation and Performance Enhancement in Indium Gallium Zinc Oxide/hafnium Zirconium Oxide Ferroelectric Field-Effect Transistors via Interface Dipole Engineering

Ferroelectric field-effect transistors (FeFETs) are receiving significant attention as representative next-generation semiconductor devices for neuromorphic computing and in-memory computing. In this study, we present threshold voltage ( V th )-tunable indium gallium zinc oxide (IGZO)/hafnium zirconium oxide (HZO) FeFETs by applying interface dipole engineering using aluminum oxide (Al 2 O 3 ) and lanthanum oxide (La 2 O 3 ) as dipole sources. Interface dipoles were formed at the IGZO/HZO interface through thermal diffusion from the source layers, and their effects were systematically investigated through sequential analysis of capacitor and transistor characteristics. The Al-dipole produced a positive V th shift and a wide memory window (MW) of 2.7 V attributed to trap amplification effects. The La-dipole simultaneously achieved a negative V th shift, MW enhancement, and device performance improvement attributed to interface oxygen vacancy passivation. The reproducibility and stability of the fabrication process were statistically verified across an ensemble of 42 devices. These results demonstrate that interface dipole engineering enables bidirectional V th modulation of more than 1.5 V, allowing the provision of various customized devices such as multilevel memory and low-power high-performance logic within a single fabrication process. This study is expected to provide high flexibility to circuit designers for neuromorphic computing and in-memory computing systems design.