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Training a Neural Network on Analog TaOx ReRAM Devices Irradiated With Heavy Ions: Effects on Classification Accuracy Demonstrated With CrossSim

IEEE Transactions on Nuclear Science

Jacobs-Gedrim, Robin B.; Hughart, David R.; Agarwal, Sapan A.; Vizkelethy, Gyorgy V.; Bielejec, E.S.; Vaandrager, Bastiaan L.; Swanson, Scot E.; Knisely, K.E.; Taggart, J.L.; Barnaby, H.J.; Marinella, M.J.

The image classification accuracy of a TaOx ReRAM-based neuromorphic computing accelerator is evaluated after intentionally inducing a displacement damage up to a fluence of 1014 2.5-MeV Si ions/cm2 on the analog devices that are used to store weights. Results are consistent with a radiation-induced oxygen vacancy production mechanism. When the device is in the high-resistance state during heavy ion radiation, the device resistance, linearity, and accuracy after training are only affected by high fluence levels. The findings in this paper are in accordance with the results of previous studies on TaOx-based digital resistive random access memory. When the device is in the low-resistance state during irradiation, no resistance change was detected, but devices with a 4-kΩ inline resistor did show a reduction in accuracy after training at 1014 2.5-MeV Si ions/cm2. This indicates that changes in resistance can only be somewhat correlated with changes to devices' analog properties. This paper demonstrates that TaOx devices are radiation tolerant not only for high radiation environment digital memory applications but also when operated in an analog mode suitable for neuromorphic computation and training on new data sets.

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TYPE Journal Article YEAR 2019
ScopusOSTIDOI

Influence of ambient on hydrogen release from p-type gallium nitride

Proposed for publication in Journal of Applied Physics.

Myers, S.M.; Myers, S.M.; Vaandrager, Bastiaan L.; Wampler, William R.; Seager, Carleton H.

Mechanisms of H release from Mg-doped, p-type GaN were investigated in vacuum, in N{sub 2} and O{sub 2} gases, and in electron-cyclotron-resonance N{sub 2} plasmas. Replacing grown-in protium with deuterium (D) and employing sensitive nuclear-reaction analysis allowed the retained concentration to be followed quantitatively over two decades during isothermal heating, illuminating the kinetics of controlling processes. Oxidation attending the O{sub 2} exposures was monitored through nuclear-reaction analysis of {sup 18}O. N{sub 2} gas at atmospheric pressure increases the rate of D release appreciably relative to vacuum. The acceleration produced by O{sub 2} gas is much greater, but is diminished in later stages of the release by oxidation. The N{sub 2} plasma employed in these studies had no resolvable effect. We argue that surface desorption is rate controlling in the D release, and that it occurs by D-D recombination and the formation of N-D and O-D species. Our results are quantitatively consistent with a theoretical model wherein the bulk solution is in equilibrium with surface states from which desorption occurs by processes that are both first and second order in surface coverage.

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TYPE Journal Article YEAR 2003
OSTI
15 Results
15 Results