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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.


The durability of the device unit of Pt/Al2O3/HfO2/Al2O3/TiN/Si. (a) The continuous program and erase test. (b) Read disturbance test for device after 104-s retention time at room temperature and 85°C.
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Fig4: The durability of the device unit of Pt/Al2O3/HfO2/Al2O3/TiN/Si. (a) The continuous program and erase test. (b) Read disturbance test for device after 104-s retention time at room temperature and 85°C.

Mentions: The switching endurance and data retention characteristics of the device unit of Pt/Al2O3/HfO2/Al2O3/TiN/Si have been examined. The stable and reproducible switching properties have been achieved in Figure 4a,b. The sweeping voltage was applied from 0 to −2 V for set and 0 to 1.5 V for reset with a reading voltage of 0.1 V at room temperature. The endurance test shows a consistent 103 switching cycle with a stable resistance ratio of OFF/ON states above 10 (Figure 4a). Retention characteristics of the device unit were measured at room temperature and 85°C, as seen in Figure 4b. Both HRS and LRS were read at 0.1 V for cumulative waiting time of 104 s. At room temperature, no obvious degradation of the memory window is observed with slightly increasing LRS and HRS. At 85°C, the memory window exhibits better thermal stability with the resistance ratio of LRS/HRS >10, indicating a better retention endurance of the memory unit over a 10-year lifetime based on the extrapolation method. It is interesting that in the retention test, both HRS and LRS increase with time at room temperature but decrease at 85°C on the contrary. This phenomenon can be explained by the change of oxygen vacancy concentration with time at room temperature and 85°C. As known, the oxygen vacancy concentration of some oxide thin film samples stored in air ambient is not constant [33]. The air oxygen may slowly diffuse into the Al2O3/HfO2/Al2O3-based samples at room temperature, leading to the gradual decrease of oxygen vacancy concentration, i.e. the increase of HRS and LRS in oxide thin films with retention time. When raising the measuring temperature to 85°C, on one hand, the oxygen diffusion into the device unit reduces the oxygen vacancy concentration; on the other hand, the enhanced temperature may produce more oxygen vacancies in Al2O3/HfO2/Al2O3 trilayer structures. Evidently the increased carriers of oxygen vacancies predominate, so both HRS and LRS of the device unit decrease with time at 85°C.Figure 4


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)

The durability of the device unit of Pt/Al2O3/HfO2/Al2O3/TiN/Si. (a) The continuous program and erase test. (b) Read disturbance test for device after 104-s retention time at room temperature and 85°C.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385330&req=5

Fig4: The durability of the device unit of Pt/Al2O3/HfO2/Al2O3/TiN/Si. (a) The continuous program and erase test. (b) Read disturbance test for device after 104-s retention time at room temperature and 85°C.
Mentions: The switching endurance and data retention characteristics of the device unit of Pt/Al2O3/HfO2/Al2O3/TiN/Si have been examined. The stable and reproducible switching properties have been achieved in Figure 4a,b. The sweeping voltage was applied from 0 to −2 V for set and 0 to 1.5 V for reset with a reading voltage of 0.1 V at room temperature. The endurance test shows a consistent 103 switching cycle with a stable resistance ratio of OFF/ON states above 10 (Figure 4a). Retention characteristics of the device unit were measured at room temperature and 85°C, as seen in Figure 4b. Both HRS and LRS were read at 0.1 V for cumulative waiting time of 104 s. At room temperature, no obvious degradation of the memory window is observed with slightly increasing LRS and HRS. At 85°C, the memory window exhibits better thermal stability with the resistance ratio of LRS/HRS >10, indicating a better retention endurance of the memory unit over a 10-year lifetime based on the extrapolation method. It is interesting that in the retention test, both HRS and LRS increase with time at room temperature but decrease at 85°C on the contrary. This phenomenon can be explained by the change of oxygen vacancy concentration with time at room temperature and 85°C. As known, the oxygen vacancy concentration of some oxide thin film samples stored in air ambient is not constant [33]. The air oxygen may slowly diffuse into the Al2O3/HfO2/Al2O3-based samples at room temperature, leading to the gradual decrease of oxygen vacancy concentration, i.e. the increase of HRS and LRS in oxide thin films with retention time. When raising the measuring temperature to 85°C, on one hand, the oxygen diffusion into the device unit reduces the oxygen vacancy concentration; on the other hand, the enhanced temperature may produce more oxygen vacancies in Al2O3/HfO2/Al2O3 trilayer structures. Evidently the increased carriers of oxygen vacancies predominate, so both HRS and LRS of the device unit decrease with time at 85°C.Figure 4

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.