Dual-Mode Operations of Self-Rectifying Ferroelectric Tunnel Junction Crosspoint Array for High-Density Integration of IoT Devices

This study proposes a self-rectifying ferroelectric tunnel junction (SR-FTJ) crosspoint array to satisfy the stringent size requirements of the Internet-of-Things devices. Each cell in the SR-FTJ crosspoint array consists of two SR-FTJs stacked vertically, resulting in ultrahigh density. The SR-FTJ crosspoint array can operate as: 1) ternary content-addressable memory (TCAM) or 2) binary content addressable memory (BCAM) or physically unclonable function (PUF) in the dual-mode operation. In the dual-mode operation, the amount of the current flowing through the SR-FTJs remains the same, resulting in a stable PUF response regardless of the BCAM data. The dual-mode operation of the SR-FTJ crosspoint array is experimentally verified by 4-in wafer-level demonstrations. HSPICE simulation results using the industrial-compatible 180-nm technology with the SR-FTJ model reflecting measured characteristics show that the SR-FTJ crosspoint array achieves the lowest search energy (2.05 fJ/search/bit) and the highest randomness (Hamming weight of 0.5000) among the previous content addressable memories (CAMs) and PUFs. In addition, the SR-FTJ crosspoint array reduces area by > 84.2% compared to the previous structures that implement individual CAM and PUF.