Scalability Study on Ferroelectric-HfO2 Tunnel Junction Memory Based on Non-equilibrium Green Function Method

We have developed a numerical simulation framework for HfO2 based Ferroelectric Tunnel Junction (FTJ) memory using Non-Equilibrium Green Function (NEGF) and self-consistent potential method which is calibrated by our experimental FTJ results. Scalability and design guideline of Metal-Ferroelectric-Insulator-Semiconductor (MFIS) structure FTJ is investigated in this work. Due to the large asymmetry of dielectric screening length of MFIS structure FTJ electrodes, MFIS structure FTJ shows a higher tunneling electroresistance (TER) ratio than Metal-Ferroelectric-Insulator-Metal (MFIM) structure FTJ, while it has almost the same read current as MFIM structure FTJ. High read current and high TER ratio can be obtained by adjusting property of semiconductor bottom electrodes. A guideline of designing MFIS structure FTJ has been proposed for high read current and high TER ratio. MFIS type FTJ shows a potential for scaling down to sub-20 nm diameter.