​​​Oxy​gen-controlled IGZO channel deposition for enhanced memory window in ferroelectric FETs

Abstract

Ferroelectric field-effect transistors (FeFETs) incorporating hafnium-oxide-based ferroelectrics are promising candidates for next-generation nonvolatile memory technologies. Nevertheless, interface-related challenges continue to limit their device performance and reliability. In this work, we demonstrate a strategy to enhance the memory window of IGZO/HfZrO2 FeFETs through precise modulation of the oxygen partial pressure (PO2) during IGZO channel deposition. Systematic variation of PO2 from 0% to 20% revealed a substantial impact on device characteristics, with the optimized 5% PO2 condition yielding a maximum memory window of 1.85 V. X-ray photoelectron spectroscopy confirmed that PO2 tuning effectively governs the oxygen vacancy concentration in the IGZO channel and the defect density at the IGZO/HfZrO2 interface. The optimized 5% PO2 condition minimized interfacial defect states while maintaining sufficient carrier density, enabling both enhanced memory operation and accelerated switching dynamics. Nucleation-limited switching analysis further indicated that optimized oxygen control allows faster polarization switching compared to non-optimal conditions. These findings highlight the critical role of oxygen stoichiometry engineering in oxide semiconductor channels and provide a viable pathway toward improving the endurance, retention, and overall performance of ferroelectric memory devices.