Understanding tunneling electroresistance effect through potential profile in Pt/Hf0.5Zr0.5O2/TiN ferroelectric tunnel junction memory

Abstract

Hafnia ferroelectric materials have gained prominence as promising materials for advanced memory applications due to their high scalability and full-complementary metal oxide semiconductor compatibility. In this paper, we present a comprehensive study on the electrical properties of Pt/Hf0.5Zr0.5O2/TiN asymmetric ferroelectric tunnel junction (FTJ) devices. The ferroelectric behavior of 4- and 5-nm Hf0.5Zr0.5O2 (HZO) thin films was confirmed by using piezoresponse force microscopy and conductive-atomic force microscopy. The typical current-voltage characteristics of the FTJ devices with two resistance states due to the tunneling electroresistance (TER) effect have been analyzed using a direct tunneling model based on the Wentzel-Kramers-Brillouin approximation. Further, we have proposed a method to extract the effective mass of the HZO thin film by numerical analysis using the MOS leakage current model. Finally, a dependence of the TER on the HZO thickness is analyzed to realize a high TER ratio.