Tiffany Callahan, Kevin Cheng, et al.
ACS Spring 2025
Ferroelectric Tunnel Junctions (FTJs) are a candidate for the hardware realization of synapses in artificial neural networks. The fabrication process for a 784 × 100 crossbar array of 500 nm large FTJs, exhibiting effective On/Off currents ratio in the range 50–100, is presented. First, the epitaxial 4 nm-BiFeO3/Ca0.96Ce0.04MnO3//YAlO3 is combined with Ni electrodes. The oxidation of Ni during the processing affects the polarity of the FTJ and the On/Off ratio, which becomes comparable to that of CMOS-compatible HfZrO4 junctions. The latter have a wider coercive field distribution: consequently, in test crossbar arrays, BiFeO3 exhibits a smaller cross-talk than HfZrO4. Furthermore, the relatively larger threshold for ferroelectric switching in BiFeO3 allows the use application of half-programming schemes for supervised and unsupervised learning. Second, the heterostructure is combined with W and Pt electrodes. The design is optimized for the controlled collapse chip connection to neuromorphic circuits. Graphical abstract: [Figure not available: see fulltext.]
Tiffany Callahan, Kevin Cheng, et al.
ACS Spring 2025
Florian Albrecht, Igor Rončević, et al.
Science
Nayara Fonseca, Veronica Guidetti, et al.
ICLR 2023
Vadim Elisseev, Max Esposito, et al.
NeurIPS 2024