Investigation and Improvement of Verify-Program in Carbon Nanotube-Based Nonvolatile Memory

Carbon nanotube (CNT)-based random access memory (NRAM) cells are measured to investigate cell program at different set current compliances and temperatures. Then, a physical model is proposed to explain the mechanism of cell resistance switching. Specifically, the changes in the NRAM cell tunneling...

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Bibliographic Details
Published in:IEEE transactions on electron devices 2015-09, Vol.62 (9), p.2837-2844
Main Authors: Sheyang Ning, Iwasaki, Tomoko Ogura, Shimomura, Kazuya, Johguchi, Koh, Yanagizawa, Eisuke, Rosendale, Glen, Manning, Monte, Viviani, Darlene, Rueckes, Thomas, Takeuchi, Ken
Format: Article
Language:English
Subjects:
Carbon nanotube (CNT)
Current measurement
Electrical resistance measurement
nonvolatile memory
Proposals
Resistance
resistance switching
Switches
Temperature measurement
verify-program
Voltage measurement
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Summary:Carbon nanotube (CNT)-based random access memory (NRAM) cells are measured to investigate cell program at different set current compliances and temperatures. Then, a physical model is proposed to explain the mechanism of cell resistance switching. Specifically, the changes in the NRAM cell tunneling current and resistance can be attributed to the variation of the distance between CNTs. An attraction force (F attraction ), generated by electrical induction, reduces the distance, whereas a repulsion force (F repulsion ), generated by phonon-induced temperature, increases the distance. It is proposed that the dominance of these two forces is reversed during set and reset programs, possibly due to the reduction of F repulsion in set program. Finally, two verify-reset schemes are proposed to improve the NRAM cell verify-program performance. The first proposal, multiple-pulse reset demonstrates 23% program time reduction by skipping a cell resistance read between two successive reset pulses. The second proposal, gate-pulse reset is calculated to decrease more than 40% program energy by reducing bitline charge energy in array program.
ISSN:0018-9383
1557-9646
DOI:10.1109/TED.2015.2450219