Limits...
Evidence of Filamentary Switching in Oxide-based Memory Devices via Weak Programming and Retention Failure Analysis.

Younis A, Chu D, Li S - Sci Rep (2015)

Bottom Line: Furthermore, the metal oxide-based (CeO2:Gd) memory device was found to possess electrical and neuromorphic multifunctionalities.In addition, a short-term to long-term memory transition analogous to the forgetting process in the human brain, which is regarded as a key biological synaptic function for information processing and data storage, was realized.Based on a careful examination of the device's retention behaviour at elevated temperatures, the filamentary nature of switching in such devices can be understood from a new perspective.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, University of New South Wales, Sydney, 2052, NSW, Australia.

ABSTRACT
Further progress in high-performance microelectronic devices relies on the development of novel materials and device architectures. However, the components and designs that are currently in use have reached their physical limits. Intensive research efforts, ranging from device fabrication to performance evaluation, are required to surmount these limitations. In this paper, we demonstrate that the superior bipolar resistive switching characteristics of a CeO2:Gd-based memory device can be manipulated by means of UV radiation, serving as a new degree of freedom. Furthermore, the metal oxide-based (CeO2:Gd) memory device was found to possess electrical and neuromorphic multifunctionalities. To investigate the underlying switching mechanism of the device, its plasticity behaviour was studied by imposing weak programming conditions. In addition, a short-term to long-term memory transition analogous to the forgetting process in the human brain, which is regarded as a key biological synaptic function for information processing and data storage, was realized. Based on a careful examination of the device's retention behaviour at elevated temperatures, the filamentary nature of switching in such devices can be understood from a new perspective.

No MeSH data available.


Related in: MedlinePlus

Evidence of the filament dissolution process through measurements of the temperature-dependant retention versus time.The device exhibited excellent data retention up to 100 °C when operating under both dark and irradiated conditions. However, data retention failure was clearly observed at elevated temperatures both (a) under dark conditions and (b) under UV irradiation. A read pulse (0.1 V/10 ms) was applied every 5 s during the test.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4555098&req=5

f5: Evidence of the filament dissolution process through measurements of the temperature-dependant retention versus time.The device exhibited excellent data retention up to 100 °C when operating under both dark and irradiated conditions. However, data retention failure was clearly observed at elevated temperatures both (a) under dark conditions and (b) under UV irradiation. A read pulse (0.1 V/10 ms) was applied every 5 s during the test.

Mentions: To further confirm the aforementioned filamentary switching mechanism, the temperature dependence of the switching behaviours was studied to gain insight into the nature of filamentary failure. The device conductance in the LRS was periodically monitored every 10 s with a low read voltage pulse (0.1 V/10  ms) to avoid disturbance in the the device state at elevated temperatures (RT, 50, 100, 150, 200, 250 and 300  °C), as shown in Fig. 5. The device retained its data retention capability up to 100 °C for more than 24 hours, thereby demonstrating excellent thermal stability and sustainability. At higher temperatures, the failure of the device was more rapid than that at low temperatures [Fig. 5(a)]. In general, two different conductance behaviours were recorded at temperatures higher than 100  °C, and a gradual decline in retention was observed prior to complete failure. Our previous results are consistent with the observed high-temperature retention failure phenomena, suggesting that the entire process can be understood in terms of the oxygen ions/vacancies-based filament model. Generally, when a sufficient number of oxygen vacancies become aggregated or accumulated inside a filament, a percolation path in the form of a conducting filament is generated, resulting in the LRS. However, the oxygen vacancies inside the filament can also spontaneously diffuse away via a thermally activated process30. To understand this process, the retention failure time was recorded and analysed as a function of temperature, as shown in Figure S4, which exhibits a thermal activation effect with an activation energy of 0.6 eV, in good agreement with the thermal activation energy of bulk CeO231. The gradual reduction in the concentration of oxygen vacancies in the filament through diffusion corresponds to the gradual decline in the retention failure curve. Finally, once the local concentration of oxygen vacancies inside the filament has decreased below a certain threshold value, i.e., the electron wave functions associated with the oxygen vacancies no longer overlap and no extended state remains3233, the filament ultimately ruptures, resulting in sudden decrease in device conductance.


Evidence of Filamentary Switching in Oxide-based Memory Devices via Weak Programming and Retention Failure Analysis.

Younis A, Chu D, Li S - Sci Rep (2015)

Evidence of the filament dissolution process through measurements of the temperature-dependant retention versus time.The device exhibited excellent data retention up to 100 °C when operating under both dark and irradiated conditions. However, data retention failure was clearly observed at elevated temperatures both (a) under dark conditions and (b) under UV irradiation. A read pulse (0.1 V/10 ms) was applied every 5 s during the test.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4555098&req=5

f5: Evidence of the filament dissolution process through measurements of the temperature-dependant retention versus time.The device exhibited excellent data retention up to 100 °C when operating under both dark and irradiated conditions. However, data retention failure was clearly observed at elevated temperatures both (a) under dark conditions and (b) under UV irradiation. A read pulse (0.1 V/10 ms) was applied every 5 s during the test.
Mentions: To further confirm the aforementioned filamentary switching mechanism, the temperature dependence of the switching behaviours was studied to gain insight into the nature of filamentary failure. The device conductance in the LRS was periodically monitored every 10 s with a low read voltage pulse (0.1 V/10  ms) to avoid disturbance in the the device state at elevated temperatures (RT, 50, 100, 150, 200, 250 and 300  °C), as shown in Fig. 5. The device retained its data retention capability up to 100 °C for more than 24 hours, thereby demonstrating excellent thermal stability and sustainability. At higher temperatures, the failure of the device was more rapid than that at low temperatures [Fig. 5(a)]. In general, two different conductance behaviours were recorded at temperatures higher than 100  °C, and a gradual decline in retention was observed prior to complete failure. Our previous results are consistent with the observed high-temperature retention failure phenomena, suggesting that the entire process can be understood in terms of the oxygen ions/vacancies-based filament model. Generally, when a sufficient number of oxygen vacancies become aggregated or accumulated inside a filament, a percolation path in the form of a conducting filament is generated, resulting in the LRS. However, the oxygen vacancies inside the filament can also spontaneously diffuse away via a thermally activated process30. To understand this process, the retention failure time was recorded and analysed as a function of temperature, as shown in Figure S4, which exhibits a thermal activation effect with an activation energy of 0.6 eV, in good agreement with the thermal activation energy of bulk CeO231. The gradual reduction in the concentration of oxygen vacancies in the filament through diffusion corresponds to the gradual decline in the retention failure curve. Finally, once the local concentration of oxygen vacancies inside the filament has decreased below a certain threshold value, i.e., the electron wave functions associated with the oxygen vacancies no longer overlap and no extended state remains3233, the filament ultimately ruptures, resulting in sudden decrease in device conductance.

Bottom Line: Furthermore, the metal oxide-based (CeO2:Gd) memory device was found to possess electrical and neuromorphic multifunctionalities.In addition, a short-term to long-term memory transition analogous to the forgetting process in the human brain, which is regarded as a key biological synaptic function for information processing and data storage, was realized.Based on a careful examination of the device's retention behaviour at elevated temperatures, the filamentary nature of switching in such devices can be understood from a new perspective.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, University of New South Wales, Sydney, 2052, NSW, Australia.

ABSTRACT
Further progress in high-performance microelectronic devices relies on the development of novel materials and device architectures. However, the components and designs that are currently in use have reached their physical limits. Intensive research efforts, ranging from device fabrication to performance evaluation, are required to surmount these limitations. In this paper, we demonstrate that the superior bipolar resistive switching characteristics of a CeO2:Gd-based memory device can be manipulated by means of UV radiation, serving as a new degree of freedom. Furthermore, the metal oxide-based (CeO2:Gd) memory device was found to possess electrical and neuromorphic multifunctionalities. To investigate the underlying switching mechanism of the device, its plasticity behaviour was studied by imposing weak programming conditions. In addition, a short-term to long-term memory transition analogous to the forgetting process in the human brain, which is regarded as a key biological synaptic function for information processing and data storage, was realized. Based on a careful examination of the device's retention behaviour at elevated temperatures, the filamentary nature of switching in such devices can be understood from a new perspective.

No MeSH data available.


Related in: MedlinePlus