In this study, we demonstrated experimentally that formation of chains and islands of oxygen vacancies in hafnium sub-oxides (HfOx, x<2) leads to percolation charge transport in such dielectrics. Basing on the model of Éfros-Shklovskii percolation theory, good quantitative agreement between the experimental and theoretical data of current-voltage characteristics was achieved. Based on the percolation theory suggested model shows that hafnium sub-oxides consist of mixtures of metallic Hf nanoscale clusters of 1-2nm distributed onto non-stoichiometric HfOx. It was shown that reported approach might describe low resistance state current-voltage characteristics of resistive memory elements based on HfOx.
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