What is it about?

Measuring the diffusion of ions across nanoscale thin films is incredibly important for nano electronics but incredibly difficult. We have developed a method that allows the use of Secondary Ion Mass Spectrometry, the most sensitive surface analysis technique, to track changes in the concentration of oxygen across a stack of thin films.

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Why is it important?

The detail revealed on the scale and magnitude of the oxygen diffusion is unprecedented. We show how efficiently the electrode stores and releases oxygen during operation, acting as a reservoir. We find that the degree of oxygen storage changes with the electrode material, giving the means to systematically improve and tune devices through optimising the reservoir. The sensitivity of this technique means it could be extended to look, for the first time, at the movement of every element in the system. This includes trace impurities that are important to performance, but too low in concentration to be measured using other techniques.


Although SIMS analysis produces a wealth of information about the system it is measuring it can be very difficult to deconvolute and so is perhaps sometimes overlooked. I have been continually surprised by the scale and complexity of the movement of ions revealed in these ReRAM devices. I hope this work gives an insight into how incredibly powerful SIMS analysis can be.

Horatio Cox
University College London

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This page is a summary of: A nanoscale analysis method to reveal oxygen exchange between environment, oxide, and electrodes in ReRAM devices, APL Materials, November 2021, American Institute of Physics, DOI: 10.1063/5.0070046.
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