A fluorite-structured HfO2/ZrO2/HfO2 superlattice based self-rectifying ferroelectric tunnel junction synapse

A self-rectifying ferroelectric tunnel junction that employs a HfO2/ZrO2/HfO2 superlattice (HZH SL) combined with Al2O3 and TiO2 layers is proposed. The 6 nm-thick HZH SL effectively suppresses the formation of non-ferroelectric phases while increasing remnant polarization (Pr). This enlarged Pr mod...

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Bibliographic Details
Published in:Materials horizons 2024-10, Vol.11 (21), p.5251-5264
Main Authors: Lee, Dong Hyun, Kim, Ji Eun, Cho, Yong Hyeon, Kim, Sojin, Park, Geun Hyeong, Choi, Hyojun, Sun Young Lee, Kwon, Taegyu, Kim, Da Hyun, Jeong, Moonseek, Hyun Woo Jeong, Lee, Younghwan, Seung-Yong, Lee, Jung Ho Yoon, Park, Min Hyuk
Format: Article
Language:English
Subjects:
Aluminum oxide
Arrays
Ferroelectric materials
Ferroelectricity
Fluorite
Hafnium oxide
Structural reliability
Superlattices
Synapses
Titanium dioxide
Tunnel junctions
Zirconium dioxide
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Summary:A self-rectifying ferroelectric tunnel junction that employs a HfO2/ZrO2/HfO2 superlattice (HZH SL) combined with Al2O3 and TiO2 layers is proposed. The 6 nm-thick HZH SL effectively suppresses the formation of non-ferroelectric phases while increasing remnant polarization (Pr). This enlarged Pr modulates the energy barrier configuration, consequently achieving a large on/off ratio of 1273 by altering the conduction mechanism from off-state thermal injection to on-state Fowler–Nordheim tunneling. Moreover, the asymmetric Schottky barriers at the top TiN/TiO2 and bottom HfO2/Pt interfaces enable a self-rectifying property with a rectifying ratio of 1550. Through calculations and simulations it is found that the device demonstrates potential for achieving an integrated array size exceeding 7k while maintaining a 10% read margin, and shows potential for application in artificial synapses for neuromorphic computing with an image recognition accuracy above 92%. Finally, the self-rectifying behavior and device-to-device variation reliability are confirmed in a 9 × 9 crossbar array structure.
ISSN:2051-6347
2051-6355
2051-6355
DOI:10.1039/d4mh00519h