Multi-terminal memtransistors using polycrystalline monolayer molybdenum disulfide (MoS2) have recently emerged as novel synaptic devices. Due to the coexistence of disorder and strong Coulomb carrier-carrier interactions in MoS2, localization and delocalization of carriers can come into play successively upon the relative strength of disorder and interactions, which can be tuned by the Fermi level (EF). In this work, we show that the transition from trap-mediated to band-like transport leads to the resistive switching behavior in MoS2 memtransistors, which is driven by the EF shift arising from defect profile redistribution that is facilitated by grain boundaries. In the high resistance state, field-driven hopping conduction can be clearly observed in the high-field region (E>0.05 MV/cm), whereas the linear dependence of ln(I/E) on the square root of the electric field, E1/2, suggests Poole–Frenkel emission in the low-field region (E0.05 MV/cm). In the low resistance state, strong interactions prevailed and a substantial amount of thermally activated electrons are excited into the conduction band, leading to band-like transport.

1.
V. K.
Sangwan
,
H.-S.
Lee
,
H.
Bergeron
,
I.
Balla
,
M. E.
Beck
,
K.-S.
Chen
, and
M. C.
Hersam
, “
Multi-terminal memtransistors from polycrystalline monolayer molybdenum disulfide
,”
Nature
554
,
500
504
(
2018
).
2.
L.
Wang
,
W.
Liao
,
S. L.
Wong
,
Z. G.
Yu
,
S.
Li
,
Y.-F.
Lim
,
X.
Feng
,
W. C.
Tan
,
X.
Huang
,
L.
Chen
,
L.
Liu
,
J.
Chen
,
X.
Gong
,
C.
Zhu
,
X.
Liu
,
Y.-W.
Zhang
,
D.
Chi
, and
K.-W.
Ang
, “
Artificial synapses based on multiterminal memtransistors for neuromorphic application
,”
Adv. Funct. Mater.
29
,
1901106
(
2019
).
3.
V. K.
Sangwan
,
D.
Jariwala
,
I. S.
Kim
,
K.-S.
Chen
,
T. J.
Marks
,
L. J.
Lauhon
, and
M. C.
Hersam
, “
Gate-tunable memristive phenomena mediated by grain boundaries in single-layer MoS2
,”
Nat. Nanotechnol.
10
,
403
406
(
2015
).
4.
H.-P.
Komsa
,
S.
Kurasch
,
O.
Lehtinen
,
U.
Kaiser
, and
A. V.
Krasheninnikov
, “
From point to extended defects in two-dimensional MoS2: Evolution of atomic structure under electron irradiation
,”
Phys. Rev. B
88
,
035301
(
2013
).
5.
J.
Jadwiszczak
,
D.
Keane
,
P.
Maguire
,
C. P.
Cullen
,
Y.
Zhou
,
H.
Song
,
C.
Downing
,
D.
Fox
,
N.
McEvoy
,
R.
Zhu
,
J.
Xu
,
G. S.
Duesberg
,
Z.-M.
Liao
,
J. J.
Boland
, and
H.
Zhang
, “
MoS2 memtransistors fabricated by localized helium ion beam irradiation
,”
ACS Nano
13
,
14262
14273
(
2019
).
6.
D.
Li
,
B.
Wu
,
X.
Zhu
,
J.
Wang
,
B.
Ryu
,
W. D.
Lu
,
W.
Lu
, and
X.
Liang
, “
MoS2 memristors exhibiting variable switching characteristics toward biorealistic synaptic emulation
,”
ACS Nano
12
,
9240
9252
(
2018
).
7.
R.
Meyer
,
R.
Liedtke
, and
R.
Waser
, “
Oxygen vacancy migration and time-dependent leakage current behavior of Ba0.3sr0.7TiO3 thin films
,”
Appl. Phys. Lett.
86
,
112904
(
2005
).
8.
G.
He
,
K.
Ghosh
,
U.
Singisetti
,
H.
Ramamoorthy
,
R.
Somphonsane
,
G.
Bohra
,
M.
Matsunaga
,
A.
Higuchi
,
N.
Aoki
,
S.
Najmaei
,
Y.
Gong
,
X.
Zhang
,
R.
Vajtai
,
P. M.
Ajayan
, and
J. P.
Bird
, “
Conduction mechanisms in CVD-grown monolayer MoS2 transistors: From variable-range hopping to velocity saturation
,”
Nano Lett.
15
,
5052
5058
(
2015
).
9.
O.
Mitrofanov
and
M.
Manfra
, “
Poole–Frenkel electron emission from the traps in AlGaN/GaN transistors
,”
J. Appl. Phys.
95
,
6414
6419
(
2004
).
10.
S. D.
Ganichev
,
E.
Ziemann
,
W.
Prettl
,
I. N.
Yassievich
,
A. A.
Istratov
, and
E. R.
Weber
, “
Distinction between the Poole–Frenkel and tunneling models of electric-field-stimulated carrier emission from deep levels in semiconductors
,”
Phys. Rev. B
61
,
10361
10365
(
2000
).
11.
H.
Schroeder
, “
Poole–Frenkel-effect as dominating current mechanism in thin oxide films—An illusion?!
,”
J. Appl. Phys.
117
,
215103
(
2015
).
12.
T.
Cheiwchanchamnangij
and
W. R. L.
Lambrecht
, “
Quasiparticle band structure calculation of monolayer, bilayer, and bulk MoS2
,”
Phys. Rev. B
85
,
205302
(
2012
).
13.
W.
Zhu
,
T.
Low
,
Y.-H.
Lee
,
H.
Wang
,
D. B.
Farmer
,
J.
Kong
,
F.
Xia
, and
P.
Avouris
, “
Electronic transport and device prospects of monolayer molybdenum disulphide grown by chemical vapour deposition
,”
Nat. Commun.
5
,
3087
(
2014
).
14.
E. J. G.
Santos
and
E.
Kaxiras
, “
Electrically driven tuning of the dielectric constant in MoS2 layers
,”
ACS Nano
7
,
10741
10746
(
2013
).
15.
H.
Qiu
,
T.
Xu
,
Z.
Wang
,
W.
Ren
,
H.
Nan
,
Z.
Ni
,
Q.
Chen
,
S.
Yuan
,
F.
Miao
,
F.
Song
,
G.
Long
,
Y.
Shi
,
L.
Sun
,
J.
Wang
, and
X.
Wang
, “
Hopping transport through defect-induced localized states in molybdenum disulphide
,”
Nat. Commun.
4
,
2642
(
2013
).
16.
Z.
Yu
,
Y.
Pan
,
Y.
Shen
,
Z.
Wang
,
Z.-Y.
Ong
,
T.
Xu
,
R.
Xin
,
L.
Pan
,
B.
Wang
,
L.
Sun
,
J.
Wang
,
G.
Zhang
,
Y. W.
Zhang
,
Y.
Shi
, and
X.
Wang
, “
Towards intrinsic charge transport in monolayer molybdenum disulfide by defect and interface engineering
,”
Nat. Commun.
5
,
5290
(
2014
).
17.
N.
Papadopoulos
,
G. A.
Steele
, and
H. S. J.
van der Zant
, “
Efros-shklovskii variable range hopping and nonlinear transport in 1t/1t'-MoS2
,”
Phys. Rev. B
96
,
235436
(
2017
).
18.
M. D. H.
Chowdhury
,
P.
Migliorato
, and
J.
Jang
, “
Low temperature characteristics in amorphous indium-gallium-zinc-oxide thin-film transistors down to 10k
,”
Appl. Phys. Lett.
103
,
152103
(
2013
).
19.
S.
Peng
,
Z.
Jin
,
Y.
Yao
,
L.
Li
,
D.
Zhang
,
J.
Shi
,
X.
Huang
,
J.
Niu
,
Y.
Zhang
, and
G.
Yu
, “
Metal-contact-induced transition of electrical transport in monolayer MoS2: From thermally activated to variable-range hopping
,”
Adv. Electron. Mater.
5
,
1900042
(
2019
).
20.
D.
Yu
,
C.
Wang
,
B. L.
Wehrenberg
, and
P.
Guyot-Sionnest
, “
Variable range hopping conduction in semiconductor nanocrystal solids
,”
Phys. Rev. Lett.
92
,
216802
(
2004
).
21.
I.
Vladimirov
,
M.
Kühn
,
T.
Geßner
,
F.
May
, and
R. T.
Weitz
, “
Energy barriers at grain boundaries dominate charge carrier transport in an electron-conductive organic semiconductor
,”
Sci. Rep.
8
,
14868
(
2018
).
22.
L.
Wang
,
L.
Chen
,
S. L.
Wong
,
X.
Huang
,
W.
Liao
,
C.
Zhu
,
Y.-F.
Lim
,
D.
Li
,
X.
Liu
,
D.
Chi
, and
K.-W.
Ang
, “
Electronic devices and circuits based on wafer-scale polycrystalline monolayer MoS2 by chemical vapor deposition
,”
Adv. Electron. Mater.
5
,
1900393
(
2019
).
23.
K. K. H.
Smithe
,
C. D.
English
,
S. V.
Suryavanshi
, and
E.
Pop
, “
High-field transport and velocity saturation in synthetic monolayer MoS2
,”
Nano Lett.
18
,
4516
4522
(
2018
).
You do not currently have access to this content.