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Dynamic-load-enabled ultra-low power multiple-state RRAM devices.

Yang X, Chen IW - Sci Rep (2012)

Bottom Line: Bipolar resistance-switching materials allowing intermediate states of wide-varying resistance values hold the potential of drastically reduced power for non-volatile memory.This approach is entirely scalable and applicable to other bipolar RRAM with intermediate states.The projected power is 12 nW for a 100 × 100 nm(2) device and 500 pW for a 10 × 10 nm(2) device.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104-6272, USA.

ABSTRACT
Bipolar resistance-switching materials allowing intermediate states of wide-varying resistance values hold the potential of drastically reduced power for non-volatile memory. To exploit this potential, we have introduced into a nanometallic resistance-random-access-memory (RRAM) device an asymmetric dynamic load, which can reliably lower switching power by orders of magnitude. The dynamic load is highly resistive during on-switching allowing access to the highly resistive intermediate states; during off-switching the load vanishes to enable switching at low voltage. This approach is entirely scalable and applicable to other bipolar RRAM with intermediate states. The projected power is 12 nW for a 100 × 100 nm(2) device and 500 pW for a 10 × 10 nm(2) device. The dynamic range of the load can be increased to allow power to be further decreased by taking advantage of the exponential decay of wave-function in a newly discovered nanometallic random material, reaching possibly 1 pW for a 10×10 nm(2) nanometallic RRAM device.

No MeSH data available.


Related in: MedlinePlus

(a) R–V curves of 100×100 μm2 cells of 10 nm and 17 nm thickness.(b) On-resistance Ron and off-switching voltage Voff* for the 17 nm film cells of various areas at their minimum Poff configuration (optimal Rex).
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f6: (a) R–V curves of 100×100 μm2 cells of 10 nm and 17 nm thickness.(b) On-resistance Ron and off-switching voltage Voff* for the 17 nm film cells of various areas at their minimum Poff configuration (optimal Rex).

Mentions: Although the approach of employing an asymmetric dynamic load to reduce P was demonstrated above using a nanometallic RRAM, it is applicable to other bipolar RRAM that satisfies two requirements: (i) intermediate states are accessible using compliance control, and (ii) switching is triggered by a critical cell voltage independent of cell area. Nevertheless, nanometallic RRAM does have two important advantages. First, since it switches by a purely electronic mechanism, fast switching speed should be possible (<50 ns as already measured in our laboratory, much faster also likely), assuring a very small energy for switching per bit. Second, reflecting the elastic tunneling nature of itinerant electrons in random materials, the HRS of nanometallic thin films follows a unique exponential dependence on thickness, Rc~exp(δ/ζHR), where δ is the thickness and ζHR (of the order of a few nm) is the localization length in the HRS8. (ζHR essentially defines the spatial extent of electron's wave-function, which decays exponentially in a random material.) Meanwhile, Vc* is thickness independent in the nanometallic regime.824 These unique attributes allow additional freedom to increase Rc and decrease P by many orders of magnitude by using thicker films to take advantage of their higher HRS (see Figure 6a). This is demonstrated by the data (red) in Figure 1, which were collected for a set of thicker (17 nm) film devices following the same procedure described above. The on-resistance for each of the 17 nm device in Figure 1 is shown in Figure 6b along with the Rex it contains and the Voff* it exhibits. Comparing these data with those of similar cell areas in Figure 4d, it is clear that Voff* is maintained at the same value but the on-resistance is raised in the 17 nm film devices.


Dynamic-load-enabled ultra-low power multiple-state RRAM devices.

Yang X, Chen IW - Sci Rep (2012)

(a) R–V curves of 100×100 μm2 cells of 10 nm and 17 nm thickness.(b) On-resistance Ron and off-switching voltage Voff* for the 17 nm film cells of various areas at their minimum Poff configuration (optimal Rex).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3473363&req=5

f6: (a) R–V curves of 100×100 μm2 cells of 10 nm and 17 nm thickness.(b) On-resistance Ron and off-switching voltage Voff* for the 17 nm film cells of various areas at their minimum Poff configuration (optimal Rex).
Mentions: Although the approach of employing an asymmetric dynamic load to reduce P was demonstrated above using a nanometallic RRAM, it is applicable to other bipolar RRAM that satisfies two requirements: (i) intermediate states are accessible using compliance control, and (ii) switching is triggered by a critical cell voltage independent of cell area. Nevertheless, nanometallic RRAM does have two important advantages. First, since it switches by a purely electronic mechanism, fast switching speed should be possible (<50 ns as already measured in our laboratory, much faster also likely), assuring a very small energy for switching per bit. Second, reflecting the elastic tunneling nature of itinerant electrons in random materials, the HRS of nanometallic thin films follows a unique exponential dependence on thickness, Rc~exp(δ/ζHR), where δ is the thickness and ζHR (of the order of a few nm) is the localization length in the HRS8. (ζHR essentially defines the spatial extent of electron's wave-function, which decays exponentially in a random material.) Meanwhile, Vc* is thickness independent in the nanometallic regime.824 These unique attributes allow additional freedom to increase Rc and decrease P by many orders of magnitude by using thicker films to take advantage of their higher HRS (see Figure 6a). This is demonstrated by the data (red) in Figure 1, which were collected for a set of thicker (17 nm) film devices following the same procedure described above. The on-resistance for each of the 17 nm device in Figure 1 is shown in Figure 6b along with the Rex it contains and the Voff* it exhibits. Comparing these data with those of similar cell areas in Figure 4d, it is clear that Voff* is maintained at the same value but the on-resistance is raised in the 17 nm film devices.

Bottom Line: Bipolar resistance-switching materials allowing intermediate states of wide-varying resistance values hold the potential of drastically reduced power for non-volatile memory.This approach is entirely scalable and applicable to other bipolar RRAM with intermediate states.The projected power is 12 nW for a 100 × 100 nm(2) device and 500 pW for a 10 × 10 nm(2) device.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104-6272, USA.

ABSTRACT
Bipolar resistance-switching materials allowing intermediate states of wide-varying resistance values hold the potential of drastically reduced power for non-volatile memory. To exploit this potential, we have introduced into a nanometallic resistance-random-access-memory (RRAM) device an asymmetric dynamic load, which can reliably lower switching power by orders of magnitude. The dynamic load is highly resistive during on-switching allowing access to the highly resistive intermediate states; during off-switching the load vanishes to enable switching at low voltage. This approach is entirely scalable and applicable to other bipolar RRAM with intermediate states. The projected power is 12 nW for a 100 × 100 nm(2) device and 500 pW for a 10 × 10 nm(2) device. The dynamic range of the load can be increased to allow power to be further decreased by taking advantage of the exponential decay of wave-function in a newly discovered nanometallic random material, reaching possibly 1 pW for a 10×10 nm(2) nanometallic RRAM device.

No MeSH data available.


Related in: MedlinePlus