Hybrid FeFET-ECRAM Device for Enhanced Memory Window and Retention via Ion-Ferroelectric Synergy

We introduce a hybrid ferroelectric field-effect transistor (FeFET) memory device that integrates an ion-based electrochemical random-access memory (ECRAM) stack with a conventional FeFET structure, significantly enhancing both memory window and retention properties. This synergistic improvement arises from ion injections facilitated by the ECRAM layer, allowing analog modulation of the threshold voltage (Vth), while the ferroelectric layer effectively suppresses ion back-diffusion, thus improving retention. Experimental data combined with ionic charge (Q<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ion</sub>)-based modeling confirms that the device achieves a memory window greater than 10 V. By tuning the ion conduction barrier energy (E<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a,ion</sub>) of the ECRAM electrolyte to 0.3 eV, uniform ion injections across various programming voltages were achieved, crucial for stable multi-level operation. This optimization resulted in highly linear incremental step pulse programming (ISPP) behavior. Comparative simulations validated the respective contributions of ferroelectric polarization (ΔP) and ionic charge (Q<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ion</sub>), demonstrating excellent agreement between modeled and experimental results. Furthermore, failure-time analysis indicated that the ferroelectric layer elevates the energy barrier for ion back-diffusion by 0.29 eV, significantly enhancing retention performance. Consequently, the hybrid device demonstrated reliable 3-bit storage capability, minimal cycle-to-cycle variation, and robust retention characteristics, clearly demonstrating the advantageous synergy between ionic and ferroelectric switching mechanisms for high-density, analog-programmable non-volatile memory applications.