Ferroelectric polarization-switching acceleration of sputtered Hf0.5Zr0.5O2 with defect-induced polarization of interlayer

Abstract

Herein, ferroelectric properties of Hf0.5Zr0.5O2 (HZO) are analyzed by inserting various interlayers (ILs) underneath HZO in capacitors and ferroelectric thin-film-transistors (FeTFTs) with all-sputter-deposited metal/HZO/IL/Si (MFIS) stacks. Although all the HZO films have similar phase ratios regardless of the IL, only the MFIS stack with a TiOx IL exhibit polarization switching. To investigate the polarization due to the introduction of TiOx, the polarization of TiOx is checked. It is confirmed that the TiOx can be polarized by the movement of oxygen vacancies (OVs) depending on the electric-field direction, which accelerates the polarization switching of HZO. Therefore, the insertion of the TiOx IL results in a wide (3.4-V) memory window in the FeTFTs, since the IL suppress the leakage current by increasing the IL thickness and simultaneously accelerates the polarization switching of the HZO.