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Excellent resistive switching properties of atomic layer-deposited Al2O3/HfO2/Al2O3 trilayer structures for non-volatile memory applications.

Wang LG, Qian X, Cao YQ, Cao ZY, Fang GY, Li AD, Wu D - Nanoscale Res Lett (2015)

Bottom Line: The memory units of Pt/Al2O3/HfO2/Al2O3/TiN/Si exhibit a typical bipolar, reliable, and reproducible resistive switching behavior, such as stable resistance ratio (>10) of OFF/ON states, sharp distribution of set and reset voltages, better switching endurance up to 10(3) cycles, and longer data retention at 85°C over 10 years.The possible switching mechanism of trilayer structure of Al2O3/HfO2/Al2O3 has been proposed.The trilayer structure device units of Al2O3/HfO2/Al2O3 on TiN-coated Si prepared by ALD may be a potential candidate for oxide-based resistive random access memory.

View Article: PubMed Central - PubMed

Affiliation: National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering, College of Engineering and Applied Sciences, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 22 Hankou Road, Nanjing, 210093 People's Republic of China ; Anhui Key Laboratory of Functional Coordination Compounds, School of Chemistry and Chemical Engineering, Anqing Normal University, 128 Linghu South Road, Anhui, 246011 People's Republic of China.

ABSTRACT
We have demonstrated a flexible resistive random access memory unit with trilayer structure by atomic layer deposition (ALD). The device unit is composed of Al2O3/HfO2/Al2O3-based functional stacks on TiN-coated Si substrate. The cross-sectional HRTEM image and XPS depth profile of Al2O3/HfO2/Al2O3 on TiN-coated Si confirm the existence of interfacial layers between trilayer structures of Al2O3/HfO2/Al2O3 after 600°C post-annealing. The memory units of Pt/Al2O3/HfO2/Al2O3/TiN/Si exhibit a typical bipolar, reliable, and reproducible resistive switching behavior, such as stable resistance ratio (>10) of OFF/ON states, sharp distribution of set and reset voltages, better switching endurance up to 10(3) cycles, and longer data retention at 85°C over 10 years. The possible switching mechanism of trilayer structure of Al2O3/HfO2/Al2O3 has been proposed. The trilayer structure device units of Al2O3/HfO2/Al2O3 on TiN-coated Si prepared by ALD may be a potential candidate for oxide-based resistive random access memory.

No MeSH data available.


Narrow-scan XPS spectra from trilayer structure of Al2O3/HfO2/Al2O3on TiN-coated Si. (a) Al 2p, (b) Hf 4f peaks of Al2O3/HfO2/Al2O3 O 1-s peaks of (c) Al2O3, and (d) HfO2 layers.
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Fig5: Narrow-scan XPS spectra from trilayer structure of Al2O3/HfO2/Al2O3on TiN-coated Si. (a) Al 2p, (b) Hf 4f peaks of Al2O3/HfO2/Al2O3 O 1-s peaks of (c) Al2O3, and (d) HfO2 layers.

Mentions: The narrow-scan XPS spectra of Al 2p, Hf 4f, and O 1-s peaks in Al2O3 and HfO2 layers are shown in Figure 5a-d. The Al 2p peak is located at 74.4 eV, which is assigned to Al-O bonding. The Hf 4f5/2 and Hf 4f7/2 peaks at 19.0 and 17.4 eV with a spin-orbit splitting of 1.6 eV are consistent with the literature data of high k HfO2/Si [34]. The O 1-s spectra from Al2O3 and HfO2 layers can be deconvoluted into two peaks in Figure 5c,d. The slightly lower binding energies of the O 1-s peak at around 531.5 and 531.0 eV, which correspond to Al-O and Hf-O bonding in Al2O3 and HfO2 layers, respectively. Whereas the slightly higher energy of 532.1 eV in the O 1-s spectra of Figure 5c, d is attributed to the oxygen vacancies in Al2O3 and HfO2 layers based on the literature reports [35,36]. The inset tables in Figure 5c, d list the area proportion of each peak. The percentage of oxygen vacancies in the Al2O3 and HfO2 layer is about 8.0% and 14.3%, respectively. Evidently, the oxygen vacancy concentration of HfO2 is higher than that of Al2O3. The TEM and XPS depth results of trilayer structure of Al2O3/HfO2/Al2O3 confirm the existence of significant interfacial diffusion between Al2O3 and HfO2 films. Defect equation of the interfacial diffusion can be expressed as:Figure 5


Excellent resistive switching properties of atomic layer-deposited Al2O3/HfO2/Al2O3 trilayer structures for non-volatile memory applications.

Wang LG, Qian X, Cao YQ, Cao ZY, Fang GY, Li AD, Wu D - Nanoscale Res Lett (2015)

Narrow-scan XPS spectra from trilayer structure of Al2O3/HfO2/Al2O3on TiN-coated Si. (a) Al 2p, (b) Hf 4f peaks of Al2O3/HfO2/Al2O3 O 1-s peaks of (c) Al2O3, and (d) HfO2 layers.
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Fig5: Narrow-scan XPS spectra from trilayer structure of Al2O3/HfO2/Al2O3on TiN-coated Si. (a) Al 2p, (b) Hf 4f peaks of Al2O3/HfO2/Al2O3 O 1-s peaks of (c) Al2O3, and (d) HfO2 layers.
Mentions: The narrow-scan XPS spectra of Al 2p, Hf 4f, and O 1-s peaks in Al2O3 and HfO2 layers are shown in Figure 5a-d. The Al 2p peak is located at 74.4 eV, which is assigned to Al-O bonding. The Hf 4f5/2 and Hf 4f7/2 peaks at 19.0 and 17.4 eV with a spin-orbit splitting of 1.6 eV are consistent with the literature data of high k HfO2/Si [34]. The O 1-s spectra from Al2O3 and HfO2 layers can be deconvoluted into two peaks in Figure 5c,d. The slightly lower binding energies of the O 1-s peak at around 531.5 and 531.0 eV, which correspond to Al-O and Hf-O bonding in Al2O3 and HfO2 layers, respectively. Whereas the slightly higher energy of 532.1 eV in the O 1-s spectra of Figure 5c, d is attributed to the oxygen vacancies in Al2O3 and HfO2 layers based on the literature reports [35,36]. The inset tables in Figure 5c, d list the area proportion of each peak. The percentage of oxygen vacancies in the Al2O3 and HfO2 layer is about 8.0% and 14.3%, respectively. Evidently, the oxygen vacancy concentration of HfO2 is higher than that of Al2O3. The TEM and XPS depth results of trilayer structure of Al2O3/HfO2/Al2O3 confirm the existence of significant interfacial diffusion between Al2O3 and HfO2 films. Defect equation of the interfacial diffusion can be expressed as:Figure 5

Bottom Line: The memory units of Pt/Al2O3/HfO2/Al2O3/TiN/Si exhibit a typical bipolar, reliable, and reproducible resistive switching behavior, such as stable resistance ratio (>10) of OFF/ON states, sharp distribution of set and reset voltages, better switching endurance up to 10(3) cycles, and longer data retention at 85°C over 10 years.The possible switching mechanism of trilayer structure of Al2O3/HfO2/Al2O3 has been proposed.The trilayer structure device units of Al2O3/HfO2/Al2O3 on TiN-coated Si prepared by ALD may be a potential candidate for oxide-based resistive random access memory.

View Article: PubMed Central - PubMed

Affiliation: National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering, College of Engineering and Applied Sciences, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 22 Hankou Road, Nanjing, 210093 People's Republic of China ; Anhui Key Laboratory of Functional Coordination Compounds, School of Chemistry and Chemical Engineering, Anqing Normal University, 128 Linghu South Road, Anhui, 246011 People's Republic of China.

ABSTRACT
We have demonstrated a flexible resistive random access memory unit with trilayer structure by atomic layer deposition (ALD). The device unit is composed of Al2O3/HfO2/Al2O3-based functional stacks on TiN-coated Si substrate. The cross-sectional HRTEM image and XPS depth profile of Al2O3/HfO2/Al2O3 on TiN-coated Si confirm the existence of interfacial layers between trilayer structures of Al2O3/HfO2/Al2O3 after 600°C post-annealing. The memory units of Pt/Al2O3/HfO2/Al2O3/TiN/Si exhibit a typical bipolar, reliable, and reproducible resistive switching behavior, such as stable resistance ratio (>10) of OFF/ON states, sharp distribution of set and reset voltages, better switching endurance up to 10(3) cycles, and longer data retention at 85°C over 10 years. The possible switching mechanism of trilayer structure of Al2O3/HfO2/Al2O3 has been proposed. The trilayer structure device units of Al2O3/HfO2/Al2O3 on TiN-coated Si prepared by ALD may be a potential candidate for oxide-based resistive random access memory.

No MeSH data available.