Nanoscale metal oxide memristors have potential in the development of brain-inspired computing systems that are scalable and efficient. In such systems, memristors represent the native electronic analogues of the biological synapses. In this work, we show cerium oxide based bilayer memristors that are forming-free, low-voltage (∼|0.8 V|), energy-efficient (full on/off switching at ∼8 pJ with 20 ns pulses, intermediate states switching at ∼fJ), and reliable. Furthermore, pulse measurements reveal the analog nature of the memristive device; that is, it can directly be programmed to intermediate resistance states. Leveraging this finding, we demonstrate spike-timing-dependent plasticity, a spike-based Hebbian learning rule. In those experiments, the memristor exhibits a marked change in the normalized synaptic strength (>30 times), when the pre- and post-synaptic neural spikes overlap. This demonstration is an important step towards the physical construction of high density and high connectivity neural networks.

1.
L. O.
Chua
, “
Memristor-the missing circuit element
,”
IEEE Trans. Circuit Theory
18
(
5
),
507
519
(
1971
).
2.
D. B.
Strukov
,
G. S.
Snider
,
D. R.
Stewart
, and
R. S.
Williams
, “
The missing memristor found
,”
Nature
453
(
7191
),
80
83
(
2008
).
3.
R.
Waser
and
M.
Aono
, “
Nanoionics-based resistive switching memories
,”
Nat. Mater.
6
(
11
),
833
840
(
2007
).
4.
H.-S. P.
Wong
and
S.
Salahuddin
, “
Memory leads the way to better computing
,”
Nat. Nanotechnol.
10
(
3
),
191
194
(
2015
).
5.
D.
Kuzum
,
S.
Yu
, and
H. P.
Wong
, “
Synaptic electronics: Materials, devices and applications
,”
Nanotechnology
24
(
38
),
382001
(
2013
).
6.
T.
Masquelier
,
R.
Guyonneau
, and
S. J.
Thorpe
, “
Competitive STDP-based spike pattern learning
,”
Neural Comput.
21
(
5
),
1259
1276
(
2009
).
7.
Y. F.
Chang
,
B.
Fowler
,
Y. C.
Chen
,
F.
Zhou
,
C. H.
Pan
,
T. C.
Chang
, and
J. C.
Lee
, “
Demonstration of synaptic behaviors and resistive switching characterizations by proton exchange reactions in silicon oxide
,”
Sci. Rep.
6
,
21268
21278
(
2016
).
8.
S. H.
Jo
,
T.
Chang
,
I.
Ebong
,
B. B.
Bhadviya
,
P.
Mazumder
, and
W.
Lu
, “
Nanoscale memristor device as synapse in neuromorphic systems
,”
Nano Lett.
10
(
4
),
1297
1301
(
2010
).
9.
M.
Prezioso
,
F.
Merrikh-Bayat
,
B.
Hoskins
,
G.
Adam
,
K. K.
Likharev
, and
D. B.
Strukov
, “
Training and operation of an integrated neuromorphic network based on metal-oxide memristors
,”
Nature
521
(
7550
),
61
64
(
2015
).
10.
J. J.
Yang
,
D. B.
Strukov
, and
D. R.
Stewart
, “
Memristive devices for computing
,”
Nat. Nanotechnol.
8
(
1
),
13
24
(
2013
).
11.
D.
Kuzum
,
R. G.
Jeyasingh
,
S.
Yu
, and
H.-S. P.
Wong
, “
Low-energy robust neuromorphic computation using synaptic devices
,”
IEEE Trans. Electron Devices
59
(
12
),
3489
3494
(
2012
).
12.
G.
Indiveri
,
R.
Legenstein
,
G.
Deligeorgis
, and
T.
Prodromakis
, “
Integration of nanoscale memristor synapses in neuromorphic computing architectures
,”
Nanotechnology
24
(
38
),
384010
(
2013
).
13.
F.
Zhou
,
Y. F.
Chang
,
B.
Fowler
,
K.
Byun
, and
J. C.
Lee
, “
Stabilization of multiple resistance levels by current-sweep in SiOx-based resistive switching memory
,”
Appl. Phys. Lett.
106
(
6
),
063508
063513
(
2015
).
14.
J. J.
Yang
,
M. D.
Pickett
,
X.
Li
,
D. A.
Ohlberg
,
D. R.
Stewart
, and
R. S.
Williams
, “
Memristive switching mechanism for metal/oxide/metal nanodevices
,”
Nat. Nanotechnol.
3
(
7
),
429
433
(
2008
).
15.
K.
Kamiya
,
M. Y.
Yang
,
S.-G.
Park
,
B.
Magyari-Köpe
,
Y.
Nishi
,
M.
Niwa
, and
K.
Shiraishi
, “
ON-OFF switching mechanism of resistive–random–access–memories based on the formation and disruption of oxygen vacancy conducting channels
,”
Appl. Phys. Lett.
100
(
7
),
073502
(
2012
).
16.
C.-C.
Hsieh
,
A.
Roy
,
A.
Rai
,
Y.-F.
Chang
, and
S. K.
Banerjee
, “
Characteristics and mechanism study of cerium oxide based random access memories
,”
Appl. Phys. Lett.
106
(
17
),
173108
(
2015
).
17.
Y. F.
Chang
,
B.
Fowler
,
Y. C.
Chen
, and
J. C.
Lee
, “
Proton exchange reactions in SiO x-based resistive switching memory: Review and insights from impedance spectroscopy
,”
Prog. Solid State Chem. Prog. Solid State Chem.
44
(
3
),
75
85
(
2016
).
18.
D. S.
Jeong
,
R.
Thomas
,
R.
Katiyar
,
J.
Scott
,
H.
Kohlstedt
,
A.
Petraru
, and
C. S.
Hwang
, “
Emerging memories: Resistive switching mechanisms and current status
,”
Rep. Prog. Phys.
75
(
7
),
076502
(
2012
).
19.
Y. F.
Chang
,
B.
Fowler
,
F.
Zhou
,
Y. C.
Chen
, and
J. C.
Lee
, “
Study of self-compliance behaviors and internal filament characteristics in intrinsic SiOx-based resistive switching memory
,”
Appl. Phys. Lett.
108
(
3
),
033504
033508
(
2016
).
20.
C.
Hu
,
M. D.
McDaniel
,
A.
Posadas
,
A. A.
Demkov
,
J. G.
Ekerdt
, and
E. T.
Yu
, “
Highly controllable and stable quantized conductance and resistive switching mechanism in single-crystal TiO2 resistive memory on silicon
,”
Nano Lett.
14
(
8
),
4360
4367
(
2014
).
21.
S.
Yu
,
H.-Y.
Chen
,
B.
Gao
,
J.
Kang
, and
H.-S. P.
Wong
, “
HfOx-based vertical resistive switching random access memory suitable for bit-cost-effective three-dimensional cross-point architecture
,”
ACS Nano
7
(
3
),
2320
2325
(
2013
).
22.
L.
Goux
,
A.
Fantini
,
G.
Kar
,
Y.-Y.
Chen
,
N.
Jossart
,
R.
Degraeve
,
S.
Clima
,
B.
Govoreanuet
,
G.
Lorenzo
,
G.
Pourtois
 et al, “
Ultralow sub-500 nA operating current high-performance TiNAl2O3 HfO2 HfTiN bipolar RRAM achieved through understanding-based stack-engineering
,” in
2012 Symposium on VLSI Technology (VLSIT)
(
IEEE
,
2012
).
23.
Y. Y.
Chen
,
L.
Goux
,
S.
Clima
,
B.
Govoreanu
,
R.
Degraeve
,
G. S.
Kar
,
A.
Fantini
,
G.
Groeseneken
,
D. J.
Wouters
, and
M.
Jurczak
, “
Endurance/retention trade-off on cap 1T1R bipolar RRAM
,”
IEEE Trans. Electron Devices.
60
(
3
),
1114
1121
(
2013
).
24.
Y. C.
Chen
,
Y. F.
Chang
,
X.
Wu
,
M.
Guo
,
B.
Fowler
,
F.
Zhou
,
C. H.
Pan
,
T. C.
Chang
, and
J. C.
Lee
, “
Characterization of SiOx/HfOx bilayer resistive-switching memory devices
,”
ECS Trans.
72
(
2
),
25
33
(
2016
).
25.
Y.
Dan
and
M.-m.
Poo
, “
Spike timing-dependent plasticity of neural circuits
,”
Neuron
44
(
1
),
23
30
(
2004
).
26.
S.
Ban
and
O.
Kim
, “
Improvement of switching uniformity in HfOx-based resistive random access memory with a titanium film and effects of titanium on resistive switching behaviors
,”
Jpn. J. Appl. Phys., Part 1
53
(
6S
),
06JE15
(
2014
).
27.
W.
Scopel
,
A. J.
da Silva
,
W.
Orellana
, and
A.
Fazzio
, “
Comparative study of defect energetics in HfO2 and SiO2
,”
Appl. Phys. Lett.
84
,
1492
(
2004
).
28.
C.
Hardacre
,
G. M.
Roe
, and
R. M.
Lambert
, “
Structure, composition and thermal properties of cerium oxide films on platinum {111}
,”
Surf. Sci.
326
(
1
),
1
10
(
1995
).
29.
T.
Hasegawa
,
S. M. F.
Shahed
,
Y.
Sainoo
,
A.
Beniya
,
N.
Isomura
,
Y.
Watanabe
, and
T.
Komeda
, “
Epitaxial growth of CeO2 (111) film on Ru (0001): Scanning tunneling microscopy (STM) and x-ray photoemission spectroscopy (XPS) study
,”
J. Chem. Phys.
140
(
4
),
044711
(
2014
).
30.
F. ç.
Larachi
,
J.
Pierre
,
A.
Adnot
, and
A.
Bernis
, “
Ce 3d XPS study of composite CexMn1−xO2−y wet oxidation catalysts
,”
Appl. Surf. Sci.
195
(
1
),
236
250
(
2002
).
31.
A. A.
Bhatti
,
C.-C.
Hsieh
,
A.
Roy
,
L. F.
Register
, and
S. K.
Banerjee
, “
First-principles simulation of oxygen vacancy migration in HfOx, CeOx, and at their interfaces for applications in resistive random-access memories
,”
J. Comput. Electron.
15
,
741
748
(
2016
).
32.
J.
Guy
,
G.
Molas
,
P.
Blaise
,
C.
Carabasse
,
M.
Bernard
,
A.
Roule
,
G.
La Carval
,
V.
Sousa
,
H.
Grampeix
,
V.
Delaye
 et al, “
Experimental and theoretical understanding of forming, SET and RESET operations in conductive bridge RAM (CBRAM) for memory stack optimization
,” in
2014 IEEE International Electron Devices Meeting (IEDM)
(
IEEE
,
2014
).
33.
M.
Khafizov
,
I. W.
Park
,
A.
Chernatynskiy
,
L.
He
,
J.
Lin
,
J. J.
Moore
,
D.
Swank
,
T.
Lillo
,
S. R.
Philpot
,
A.
El-Azab
 et al, “
Thermal conductivity in nanocrystalline ceria thin films
,”
J. Am. Ceram. Soc.
97
(
2
),
562
569
(
2014
).
34.
S.
Menzel
, Modeling and simulation of resistive switching devices: Lehrstuhl für Werkstoffe der Elektrotechnik II und Institut für Werkstoffe der Elektrotechnik,
2013
.
35.
Y. A.
Volkov
,
L.
Palatnik
, and
A.
Pugachev
, “
Investigation of the thermal properties of thin aluminum films
,”
Zh. Eksp. Teor. Fiz.
70
,
2244
2250
(
1976
).
36.
M. A.
Panzer
,
M.
Shandalov
,
J.
Rowlette
,
Y.
Oshima
,
Y. W.
Chen
,
P. C.
McIntyre
, and
K. E.
Goodson
, “
Thermal properties of ultrathin hafnium oxide gate dielectric films
,”
IEEE Electron Device Lett.
30
(
12
),
1269
1271
(
2009
).
37.
Y. F.
Chang
,
B.
Fowler
,
Y. C.
Chen
,
Y. T.
Chen
,
Y.
Wang
,
F.
Xue
,
F.
Zhou
, and
J. C.
Lee
, “
Intrinsic SiOx-based unipolar resistive switching memory. I. Oxide stoichiometry effects on reversible switching and program window optimization
,”
J. Appl. Phys.
116
(
4
),
043708
043718
(
2014
).
38.
B.
Rajendran
,
Y.
Liu
,
J.-S.
Seo
,
K.
Gopalakrishnan
,
L.
Chang
,
D. J.
Friedman
, and
M. B.
Ritter
, “
Specifications of nanoscale devices and circuits for neuromorphic computational systems
,”
IEEE Trans. Electron Devices.
60
(
1
),
246
253
(
2013
).

Supplementary Material

You do not currently have access to this content.