One Nanometer HfO2‐Based Ferroelectric Tunnel Junctions on Silicon

• Published in: Advanced electronic materials Vol. 8; no. 6
• Main Authors: Cheema, Suraj S., Shanker, Nirmaan, Hsu, Cheng‐Hsiang, Datar, Adhiraj, Bae, Jongho, Kwon, Daewoong, Salahuddin, Sayeef
• Format: Journal Article
• Language: English
• Published: 01.06.2022
• Subjects: ferroelectric tunnel junction; hafnium oxide; resistive switching memory; ultrathin ferroelectricity
• ISSN: 2199-160X; 2199-160X
• DOI: 10.1002/aelm.202100499

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 HfO2 (Zr:HfO2) ferroelectric barriers of just 1 nm thickness, grown by atomic layer deposition on silicon. These 1 nm Zr:HfO2 tunnel junctions exhibit large polarization‐driven electroresistance (>20 000%), the largest value reported for HfO2‐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 HfO2‐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. This work integrates ferroelectric tunnel junctions (FTJs) with complementary metal‐oxide‐semiconductor‐compatible atomic layer deposition grown Zr‐doped HfO2 ferroelectric barriers just 1 nm thick. These 1 nm FTJs on Si exhibit the largest polarization‐driven electroresistance (>20 000%) and tunneling current (>1 A cm−2) reported for HfO2‐based FTJs. Therefore, this proof‐of‐principle demonstration simultaneously overcomes three prototypical FTJ roadblocks—a Si‐compatible ultrathin ferroelectric, large electroresistance, large read current—promising for ultra‐scaled memory technologies.