Potential Fluctuation in RRAM Based on Non-Stoichiometric Hafnium Sub-Oxides

ISSN 1121-7588

Damir R. Islamov^1,2, Vladimir N. Kruchinin¹, Vladimir Sh. Aliev¹, Timofey V. Perevalov^1,2, Vladimir A. Gritsenko^1,2, Igor P. Prosvirin³, Oleg M. Orlov⁴, Albert Chin⁵
¹Rzhanov Institute of Semiconductor Physics SB RAS, 13 Lavrentiev ave., 630090 Novosibirsk, Russian Federation
²Novosibirsk State University, 2 Pirogova str., 630090 Novosibirsk, Russian Federation
³Boreskov Institute of Catalysis SB RAS, 5 Lavrentiev ave., 630090, Novosibirsk, Russian Federation
⁴JSC Molecular Electronics Research Institute, 1st Zapadny proezd 12/1, 124460 Zelenograd, Russian Federation
⁵National Chiao Tung University, Hsinchu 300, Taiwan

Abstract

We study the structure of nonstoichiometric HfO_x films with variable composition using methods of XPS, spectroscopic ellipsometry, and ab initio calculations. According to XPS and optical absorption experiment data HfO_x consists of metal Hf and 10-15% of nonstoichiometric hafnium suboxide HfO_y (y < 2). HfO_y can be placed between HfO₂ and Hf, inside HfO₂, inside Hf. According to this model space fluctuations of chemical composition cause space fluctuations of bandgap in HfO_x. We found that transport in such electronic systems is described by percolation theory. This approach can be applied to explain LRS transport of HfO_x-based RRAM.

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