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Impedance spectroscopy study of the unipolar and bipolar resistive switching states of atomic layer deposited polycrystalline ZrO 2 thin films
Author(s) -
Kärkkänen Irina,
Shkabko Andrey,
Heikkilä Mikko,
Vehkamäki Marko,
Niinistö Jaakko,
Aslam Nabeel,
Meuffels Paul,
Ritala Mikko,
Leskelä Markku,
Waser Rainer,
HoffmannEifert Susanne
Publication year - 2015
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201431489
Subject(s) - materials science , electroforming , dielectric spectroscopy , crystallite , electrode , tin , layer (electronics) , thin film , optoelectronics , analytical chemistry (journal) , nanotechnology , metallurgy , electrochemistry , chemistry , chromatography
The polarity of the resistive switching (RS) characteristic of metal‐oxide‐metal devices from atomic layer deposited polycrystalline ZrO 2 films was studied by means of impedance spectroscopy. Pt/ZrO 2 /Ti/Pt cells made with 10 nm Ti and 30 nm Pt capping top electrodes, served as unipolar switching (US) devices. Bipolar switching (BS) devices were represented by Pt/ZrO 2 /30 nm TiN cells. Temperature measurements of the ON‐state resistances clearly show metallic and semiconducting behavior for the US and BS cells, respectively. The pristine and the ON and OFF states of the devices were analyzed by means of impedance spectroscopy. All ZrO 2 based RS devices exhibited similar impedance characteristics in the pristine states. In contrast, after electroforming clear differences in the Nyquist‐plots of the US and BS devices were observed. The effect of the device structure on the RS polarity is discussed under consideration of the pillar‐shaped grainy microstructure of the ZrO 2 thin films. An empirical model based on redox reactions between ZrO 2 and the non‐noble metal electrode is proposed emphasizing defect formation prior at the ZrO 2 grain boundaries.