One Nanometer HfO₂‐Based Ferroelectric Tunnel Junctions on Silicon

In ferroelectric materials, spontaneous symmetry breaking leads to a switchable electric polarization, which offers significant promise for nonvolatile memories. In particular, ferroelectric tunnel junctions (FTJs) have emerged as a new resistive switching memory which exploits polarization‐dependent tunnel current across a thin ferroelectric barrier. This work integrates FTJs with complementary metal‐oxide‐semiconductor‐compatible Zr‐doped HfO 2 (Zr:HfO 2 ) ferroelectric barriers of just 1 nm thickness, grown by atomic layer deposition on silicon. These 1 nm Zr:HfO 2 tunnel junctions exhibit large polarization‐driven electroresistance (>20 000%), the largest value reported for HfO 2 ‐based FTJs. In addition, due to just a 1 nm ferroelectric barrier, these junctions provide large tunneling current (>1 A cm −2 ) at low read voltage, orders of magnitude larger than reported thicker HfO 2 ‐based FTJs. Therefore, this proof‐of‐principle demonstration provides an approach to simultaneously overcome three major drawbacks of prototypical FTJs: a Si‐compatible ultrathin ferroelectric, large electroresistance, and large read current for high‐speed operation.