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Energy-efficient Mott activation neuron for full-hardware implementation of neural networks


To circumvent the von Neumann bottleneck, substantial progress has been made towards in-memory computing with synaptic devices. However, compact nanodevices implementing non-linear activation functions are required for efficient full-hardware implementation of deep neural networks. Here, we present an energy-efficient and compact Mott activation neuron based on vanadium dioxide and its successful integration with a conductive bridge random access memory (CBRAM) crossbar array in hardware. The Mott activation neuron implements the rectified linear unit function in the analogue domain. The neuron devices consume substantially less energy and occupy two orders of magnitude smaller area than those of analogue complementary metal–oxide semiconductor implementations. The LeNet-5 network with Mott activation neurons achieves 98.38% accuracy on the MNIST dataset, close to the ideal software accuracy. We perform large-scale image edge detection using the Mott activation neurons integrated with a CBRAM crossbar array. Our findings provide a solution towards large-scale, highly parallel and energy-efficient in-memory computing systems for neural networks.

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Fig. 1: The Mott ReLU device for the hardware implementation of a neural network.
Fig. 2: Switching mechanisms of VO2 gap.
Fig. 3: Electrical characteristics of the Mott ReLU device.
Fig. 4: Network-level implementations.
Fig. 5: System-level benchmarking results.
Fig. 6: Hardware demonstration of the integration of Mott ReLU devices and a synaptic array.

Data availability

The data that support the plots and other results of this paper are available from the corresponding author upon request.

Code availability

The software codes used for this study are available from the corresponding author upon request.


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This work was supported by Office of Naval Research (N000142012405 and N00014162531), Samsung Electronics, the National Science Foundation (ECCS-1752241, ECCS-2024776 and ECCS-1734940), the National Institutes of Health (R21 EY029466, R21 EB026180 and DP2 EB030992) and Qualcomm Fellowship. The experimental aspects of this work were supported as part of the Quantum Materials for Energy Efficient Neuromorphic Computing (Q-MEEN-C) Energy Frontier Research Center (EFRC), funded by the US Department of Energy, Office of Science, Basic Energy Sciences under award #DE-SC0019273. The fabrication of the devices was performed at the San Diego Nanotechnology Infrastructure (SDNI) of the University of California San Diego, supported by the National Science Foundation (ECCS-1542148).

Author information




S.O., Y.S., I.K.S. and D.K. conceived the idea. S.O. developed the SPICE model and performed SPICE and network simulations. S.O., Y.S. and Z.H. performed the system-level benchmarking simulations. P.S., J.d.V. and Y.K. fabricated and measured the electrical characteristics of the Mott ReLU devices under the supervision of I.K.S.; S.O. and Y.L. fabricated the CBRAM array. Y.S. designed the PCB. S.O. and Y.S. performed the measurements for the CBRAM array and Mott ReLU device integration. All the authors discussed the results and contributed to the writing of the manuscript. I.K.S. and D.K. supervised the work.

Corresponding author

Correspondence to Duygu Kuzum.

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The authors declare no competing interests.

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Peer review information Nature Nanotechnology thanks Jinfeng Kang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–6, Table 1 and Notes 1–7.

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Oh, S., Shi, Y., del Valle, J. et al. Energy-efficient Mott activation neuron for full-hardware implementation of neural networks. Nat. Nanotechnol. (2021).

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