Electronic synapses made of layered two-dimensional materials

Abstract

Neuromorphic computing systems, which use electronic synapses and neurons, could overcome the energy and throughput limitations of today’s computing architectures. However, electronic devices that can accurately emulate the short- and long-term plasticity learning rules of biological synapses remain limited. Here, we show that multilayer hexagonal boron nitride (h-BN) can be used as a resistive switching medium to fabricate high-performance electronic synapses. The devices can operate in a volatile or non-volatile regime, enabling the emulation of a range of synaptic-like behaviour, including both short- and long-term plasticity. The behaviour results from a resistive switching mechanism in the h-BN stack, based on the generation of boron vacancies that can be filled by metallic ions from the adjacent electrodes. The power consumption in standby and per transition can reach as low as 0.1 fW and 600 pW, respectively, and with switching times reaching less than 10 ns, demonstrating their potential for use in energy-efficient brain-like computing.

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Fig. 1: Fabrication of metal/h-BN/metal synapses.
Fig. 2: Dielectric breakdown in metal/h-BN/metal synapses.
Fig. 3: Volatile and non-volatile RS in metal/h-BN/metal synapses.
Fig. 4: In situ observation of volatile and non-volatile RS in h-BN.
Fig. 5: Dynamic response of metal/h-BN/metal synapses (type I).
Fig. 6: Dynamic response of metal/h-BN/metal synapses (type II).

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Acknowledgements

This work was supported by the member companies of the Non-Volatile Memory Technology Research Initiative (NMTRI) at Stanford University, the National Science Foundation EFRI 2-DARE EFRI: Energy-Efficient Electronics with Atomic Layers (E3AL) (award no. 1542883), the National Science Foundation of China (grants 61502326, 41550110223, 11661131002), the Jiangsu Government (grant BK20150343), and the Ministry of Finance of China (grant SX21400213). P. C. McIntyre and K. Tang (Stanford University) are acknowledged for support with ionic liquid experiments. Q. Liu and X. Zhang (IMECAS) are acknowledged for support with the STDP experiments. M. A. Villena and X. Jing are acknowledged for support with the SPICE simulation and mechanical exfoliation of h-BN, respectively.

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M.L., Y.S., E.P. and H.-S.P.W. designed the experiments. Y.S., V.C. and F.H. grew the h-BN stacks. Y.S. and X.L. fabricated the electronic synapses using photolithography, and B.Y. fabricated the electronic synapses using electron-beam lithography. Y.S., X.L., B.Y, Z.Y. and F.Y. characterized the devices. Y.S., H.L., M.L. and H.-S.P.W. wrote the manuscript. All authors discussed the data and results.

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Correspondence to H.-S. Philip Wong or Mario Lanza.

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Shi, Y., Liang, X., Yuan, B. et al. Electronic synapses made of layered two-dimensional materials. Nat Electron 1, 458–465 (2018). https://doi.org/10.1038/s41928-018-0118-9

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