Impedance spectroscopic analysis on effects of partial oxidation of TiN bottom electrode and microstructure of amorphous and crystalline HfO2 thin films on their bipolar resistive switching
- Authors
- Yoon, Ji-Wook; Yoon, Jung Ho; Lee, Jong-Heun; Hwang, Cheol Seong
- Issue Date
- 2014
- Publisher
- ROYAL SOC CHEMISTRY
- Citation
- NANOSCALE, v.6, no.12, pp.6668 - 6678
- Indexed
- SCIE
SCOPUS
- Journal Title
- NANOSCALE
- Volume
- 6
- Number
- 12
- Start Page
- 6668
- End Page
- 6678
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/101137
- DOI
- 10.1039/c4nr00507d
- ISSN
- 2040-3364
- Abstract
- The electrical resistance switching (RS) properties of amorphous HfO2 (a-HfO2) and crystalline HfO2 (c-HfO2) thin films grown on a TiN substrate via atomic layer deposition were examined using DC current-voltage (I-V) sweep and AC impedance spectroscopic (IS) analyses. The rapid thermal annealing of the a-HfO2 film at 500 degrees C under a N-2 atmosphere for 5 min crystallized the HfO2 film and induced an interfacial TiON barrier layer. The a-HfO2 sample showed fluent bipolar RS performance with a high on/off ratio (similar to 500), whereas the c-HfO2 sample showed a much lower on/off ratio (<similar to 10), but its switching uniformity was better than that of a-HfO2. Such critical differences can be mainly attributed to the absence and presence of the TiON barrier layer in the a-HfO2 and c-HfO2 samples, respectively. The AC IS especially enabled the resistance states of the HfO2/Pt interface and the HfO2/TiN interface to be separately examined during one complete switching cycle of each sample. Although the Pt/c-HfO2 interface has a Schottky barrier in the pristine state, it disappeared once the c-HfO2 was electroformed and was not recovered even after the reset step. In contrast, the Pt/a-HfO2 interface partly recovered the Schottky barrier after the reset.
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