Multiscale Simulation of Ferroelectric Tunnel Junction Memory Enabled by van der Waals Heterojunction: Comparison to Experiment and Performance Projection

Atomically thin van der Waals (vdW) heterojunctions are investigated for ferroelectric tunnel junction (FTJ) device application by combining multiscale simulations from atomistic ab initio to quantum transport device simulations with experimental studies. The simulation reveals that low quantum capacitance of graphene, weak electronic hybridization of vdW bonds, and high interface quality free of dangling bonds can lead to extremely large vdW interface barrier height modulation at the graphene-CuInP2S6 ferroelectric (FE) interface. As a result, the simulated and experimental I-V characteristics show an unprecedented large tunneling electroresistance ratio. The vdW ferroelectric CIPS material further permits the tunneling barrier to be scaled down to atomic thickness. Quantum transport device simulations indicate that scaling of the FE layer thickness exponentially increases the ferroelectric tunneling ON current and reduces the read latency, leading to nanosecond read speed for the FTJs with CIPS bilayer or trilayer. The FTJ device also shows excellent endurance and retention characteristics.