The stabilization of the threshold switching characteristics of memristive NbOx is examined as a function of sample growth and device characteristics. Sub-stoichiometric Nb2O5 was deposited via magnetron sputtering and patterned in nanoscale (50×50170×170nm2) W/Ir/NbOx/TiN devices and microscale (2×215×15μm2) crossbar Au/Ru/NbOx/Pt devices. Annealing the nanoscale devices at 700 °C removed the need for electroforming the devices. The smallest nanoscale devices showed a large asymmetry in the IV curves for positive and negative bias that switched to symmetric behavior for the larger and microscale devices. Electroforming the microscale crossbar devices created conducting NbO2 filaments with symmetric IV curves whose behavior did not change as the device area increased. The smallest devices showed the largest threshold voltages and most stable threshold switching. As the nanoscale device area increased, the resistance of the devices scaled with the area as RA1, indicating a crystallized bulk NbO2 device. When the nanoscale device size was comparable to the size of the filaments, the annealed nanoscale devices showed similar electrical responses as the electroformed microscale crossbar devices, indicating filament-like behavior in even annealed devices without electroforming. Finally, the addition of up to 1.8% Ti dopant into the films did not improve or stabilize the threshold switching in the microscale crossbar devices.

1.
C. D.
Wright
,
P.
Hosseini
, and
J. A. V.
Diosdado
,
Adv. Funct. Mater.
23
,
2248
(
2013
).
2.
J.
Hasler
and
B.
Marr
,
Front. Neurosci.
7
,
118
(
2013
).
3.
M. D.
Pickett
,
G.
Medeiros-Ribeiro
, and
R. S.
Williams
,
Nat. Mater.
12
,
114
(
2013
).
4.
K.
Sakata
,
J. Phys. Soc. Jpn.
26
,
582
(
1969
).
5.
R.
Janninck
and
D.
Whitmore
,
J. Phys. Chem. Solids
27
,
1183
(
1966
).
6.
M. J.
Wahila
et al.,
Phys. Rev. Mater.
3
,
074602
(
2019
).
7.
J.
Park
,
E.
Cha
,
I.
Karpov
, and
H.
Hwang
,
Appl. Phys. Lett.
108
,
232101
(
2016
).
8.
J.
Park
,
T.
Hadamek
,
A. B.
Posadas
,
E.
Cha
,
A. A.
Demkov
, and
H.
Hwang
,
Sci. Rep.
7
,
4068
(
2017
).
9.
10.
G. A.
Gibson
et al.,
Appl. Phys. Lett.
108
,
023505
(
2016
).
11.
T.
Mikolajick
,
H.
Wylezich
,
H.
Maehne
,
S.
Slesazeck
, and
T.
Mikolajick
, “Versatile resistive switching in niobium oxide,” in 2016 IEEE International Symposium on Circuits and Systems (ISCAS) (IEEE Press, New York, 2016), pp. 381–384.
12.
S. K.
Nandi
,
S. K.
Nath
,
A. E.
El-Helou
,
S.
Li
,
T.
Ratcliff
,
M.
Uenuma
,
P. E.
Raad
, and
R. G.
Elliman
,
ACS Appl. Mater. Interfaces
12
,
8422
(
2020
).
13.
S. K.
Nath
,
S. K.
Nandi
,
S.
Li
, and
R. G.
Elliman
,
Nanotechnology
31
,
235701
(
2020
).
14.
S.
Li
,
X.
Liu
,
S. K.
Nandi
, and
R. G.
Elliman
,
Nanotechnology
29
,
375705
(
2018
).
15.
D.
Chen
et al.,
Ceram. Int.
47
,
22677
(
2021
).
16.
T.
Joshi
,
P.
Borisov
, and
D.
Lederman
,
J. Appl. Phys.
124
,
114502
(
2018
).
17.
S. K.
Nath
,
S. K.
Nandi
,
T.
Ratcliff
, and
R. G.
Elliman
,
ACS Appl. Mater. Interfaces
13
,
2845
(
2021
).
18.
A. C.
Kozen
,
Z. R.
Robinson
,
E. R.
Glaser
,
M.
Twigg
,
T. J.
Larrabee
,
H.
Cho
,
S. M.
Prokes
, and
L. B.
Ruppalt
,
ACS Appl. Mater. Interfaces
12
,
16639
(
2020
).
19.
J.
Lee
,
J.
Kim
,
J.
Jeong
, and
H.
Sohn
,
J. Vac. Sci. Technol. B
39
,
053206
(
2021
).
20.
K.
Park
,
J.
Ryu
,
D. P.
Sahu
,
H.-M.
Kim
, and
T.-S.
Yoon
,
RSC Adv.
12
,
18547
(
2022
).
21.
G. J.
Pãez Fajardo
et al.,
Chem. Mater.
33
,
1416
(
2021
).
22.
M.
Twigg
,
A.
Kozen
,
L.
Ruppalt
,
S.
Prokes
, and
H.
Cho
,
J. Appl. Phys.
129
,
025304
(
2021
).
23.
A.
Kozen
et al., Crystallization behavior of zinc doped Nb2O5 thin films synthesized by atomic layer deposition,”
ACS Appl. Electron. Mater.
4
(9), 4280 (2022).
24.
S. K.
Nandi
,
X.
Liu
,
D. K.
Venkatachalam
, and
R. G.
Elliman
,
Appl. Phys. Lett.
107
,
132901
(
2015
).
25.
S. K.
Nandi
,
X.
Liu
,
D. K.
Venkatachalam
, and
R. G.
Elliman
,
J. Phys. D: Appl. Phys.
48
,
195105
(
2015
).
26.
The exact values for the hold voltages are 1.09±0.03 V, 0.91±0.02 V, 1.15±0.03 V, and 0.77±0.03 V, for 50×50, 80×80, 120×120, and 170×170nm2, respectively.
27.
The exact values for the hold voltages are 0.694±0.004 V, 0.698±0.005 V, and 0.664±0.005 V, for 2×2, 4×4, and 15×15μm2, respectively.
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