Investigation of a transition metal dichalcogenide (TMD)-metal interface is essential for the effective functioning of monolayer TMD based field effect transistors. In this work, we employ the Density Functional Theory calculations to analyze the modulation of the electronic structure of monolayer WS2 with chlorine doping and the relative changes in the contact properties when interfaced with gold and palladium. We initially examine the atomic and electronic structures of pure and doped monolayer WS2 supercell and explore the formation of midgap states with band splitting near the conduction band edge. Further, we analyze the contact nature of the pure supercell with Au and Pd. We find that while Au is physiosorbed and forms n-type contact, Pd is chemisorped and forms p-type contact with a higher valence electron density. Next, we study the interface formed between the Cl-doped supercell and metals and observe a reduction in the Schottky barrier height (SBH) in comparison to the pure supercell. This reduction found is higher for Pd in comparison to Au, which is further validated by examining the charge transfer occurring at the interface. Our study confirms that Cl doping is an efficient mechanism to reduce the n-SBH for both Au and Pd, which form different types of contact with WS2.

1.
B.
Radisavljevic
,
A.
Radenovic
,
J.
Brivio
,
V.
Giacometti
, and
A.
Kis
, “
Single-layer MoS2 transistors
,”
Nat. Nanotechnol.
6
,
147
150
(
2011
).
2.
W.
Sik Hwang
,
M.
Remskar
,
R.
Yan
,
V.
Protasenko
,
K.
Tahy
,
S.
Doo Chae
,
P.
Zhao
,
A.
Konar
,
H.
(Grace) Xing
,
A.
Seabaugh
, and
D.
Jena
, “
Transistors with chemically synthesized layered semiconductor WS2 exhibiting 105 room temperature modulation and ambipolar behavior
,”
Appl. Phys. Lett.
101
,
013107
(
2012
).
3.
X.
Liu
,
J.
Hu
,
C.
Yue
,
N. D.
Fera
,
Y.
Ling
,
Z.
Mao
, and
J.
Wei
, “
High performance field-effect transistor based on multilayer tungsten disulfide
,”
ACS Nano
8
,
10396
10402
(
2014
).
4.
S.
Das
and
J.
Appenzeller
, “
WSe2 field effect transistors with enhanced ambipolar characteristics
,”
Appl. Phys. Lett.
103
,
103501
(
2013
).
5.
S.
Larentis
,
B.
Fallahazad
, and
E.
Tutuc
, “
Field-effect transistors and intrinsic mobility in ultra-thin MoSe2 layers
,”
Appl. Phys. Lett.
101
,
223104
(
2012
).
6.
N. R.
Pradhan
,
D.
Rhodes
,
S.
Feng
,
Y.
Xin
,
S.
Memaran
,
B.-H.
Moon
,
H.
Terrones
,
M.
Terrones
, and
L.
Balicas
, “
Field-effect transistors based on few-layered α-MoTe2
,”
ACS Nano
8
,
5911
5920
(
2014
).
7.
W. S.
Leong
,
X.
Luo
,
Y.
Li
,
K. H.
Khoo
,
S. Y.
Quek
, and
J. T.
Thong
, “
Low resistance metal contacts to MoS2 devices with nickel-etched-graphene electrodes
,”
ACS Nano
9
,
869
877
(
2014
).
8.
A.
Chanana
and
S.
Mahapatra
, “
Theoretical insights to niobium-doped monolayer MoS2 gold contact
,”
IEEE Trans. Electron Devices
62
,
2346
2351
(
2015
).
9.
S.
Das
,
H.-Y.
Chen
,
A. V.
Penumatcha
, and
J.
Appenzeller
, “
High performance multilayer MoS2 transistors with scandium contacts
,”
Nano Lett.
13
,
100
105
(
2013
).
10.
J.
Kang
,
W.
Liu
, and
K.
Banerjee
, “
High-performance MoS2 transistors with low-resistance molybdenum contacts
,”
Appl. Phys. Lett.
104
,
093106
(
2014
).
11.
M. R.
Laskar
,
D. N.
Nath
,
L.
Ma
,
E. W.
Lee
 II
,
C. H.
Lee
,
T.
Kent
,
Z.
Yang
,
R.
Mishra
,
M. A.
Roldan
,
J.-C.
Idrobo
 et al, “
P-type doping of MoS2 thin films using Nb
,”
Appl. Phys. Lett.
104
,
092104
(
2014
).
12.
J.
Suh
,
T.-E.
Park
,
D.-Y.
Lin
,
D.
Fu
,
J.
Park
,
H. J.
Jung
,
Y.
Chen
,
C.
Ko
,
C.
Jang
,
Y.
Sun
,
R.
Sinclair
,
J.
Chang
,
S.
Tongay
, and
J.
Wu
, “
Doping against the native propensity of MoS2: Degenerate hole doping by cation substitution
,”
Nano Lett.
14
,
6976
6982
(
2014
).
13.
L.
Liu
,
S.
Bala Kumar
,
Y.
Ouyang
, and
J.
Guo
, “
Performance limits of monolayer transition metal dichalcogenide transistors
,”
IEEE Trans. Electron Devices
58
,
3042
3047
(
2011
).
14.
L.
Yang
,
K.
Majumdar
,
H.
Liu
,
Y.
Du
,
H.
Wu
,
M.
Hatzistergos
,
P. Y.
Hung
,
R.
Tieckelmann
,
W.
Tsai
,
C.
Hobbs
, and
P. D.
Ye
, “
Chloride molecular doping technique on 2D materials: WS2 and MoS2
,”
Nano Lett.
14
,
6275
6280
(
2014
).
15.
P. A.
Khomyakov
,
G.
Giovannetti
,
P. C.
Rusu
,
G.
Brocks
,
J.
van den Brink
, and
P. J.
Kelly
, “
First-principles study of the interaction and charge transfer between graphene and metals
,”
Phys. Rev. B
79
,
195425
(
2009
).
16.
C.
Gong
,
G.
Lee
,
B.
Shan
,
E. M.
Vogel
,
R. M.
Wallace
, and
K.
Cho
, “
First-principles study of metal-graphene interfaces
,”
J. Appl. Phys.
108
,
123711
(
2010
).
17.
I.
Popov
,
G.
Seifert
, and
D.
Tománek
, “
Designing electrical contacts to MoS2 monolayers: A computational study
,”
Phys. Rev. Lett.
108
,
156802
(
2012
).
18.
J.
Kang
,
W.
Liu
,
D.
Sarkar
,
D.
Jena
, and
K.
Banerjee
, “
Computational study of metal contacts to monolayer transition-metal dichalcogenide semiconductors
,”
Phys. Rev. X
4
,
031005
(
2014
).
19.
See http://quantumwise.com/ for Atomistix ToolKit v.15.beta Quantumwise.
20.
J. P.
Perdew
and
A.
Zunger
, “
Self-interaction correction to density-functional approximations for many-electron systems
,”
Phys. Rev. B
23
,
5048
5079
(
1981
).
21.
C.
Hartwigsen
,
S.
Goedecker
, and
J.
Hutter
, “
Relativistic separable dual-space Gaussian pseudopotentials from H to Rn
,”
Phys. Rev. B
58
,
3641
3662
(
1998
).
22.
H. J.
Monkhorst
and
J. D.
Pack
, “
Special points for Brillouin-zone integrations
,”
Phys. Rev. B
13
,
5188
(
1976
).
23.
H.
Jiang
, “
Electronic band structures of molybdenum and tungsten dichalcogenides by the gw approach
,”
J. Phys. Chem. C
116
,
7664
7671
(
2012
).
24.
A.
Kumar
and
P.
Ahluwalia
, “
Electronic structure of transition metal dichalcogenides monolayers 1H-MX2 (M = Mo, W; X = S, Se, Te) from ab-initio theory: new direct band gap semiconductors
,”
Eur. Phys. J. B
85
,
186
(
2012
).
25.
K.
Dolui
,
I.
Rungger
,
C.
Das Pemmaraju
, and
S.
Sanvito
, “
Possible doping strategies for MoS2 monolayers: An ab initio study
,”
Phys. Rev. B
88
,
075420
(
2013
).
26.
C. G.
Van de Walle
and
J.
Neugebauer
, “
First-principles calculations for defects and impurities: Applications to III-nitrides
,”
J. Appl. Phys.
95
,
3851
3879
(
2004
).
27.
C.
Gong
,
L.
Colombo
,
R. M.
Wallace
, and
K.
Cho
, “
The unusual mechanism of partial Fermi level pinning at metal–MoS2 interfaces
,”
Nano Lett.
14
,
1714
1720
(
2014
).
28.
A. D.
Becke
and
K. E.
Edgecombe
, “
A simple measure of electron localization in atomic and molecular systems
,”
J. Chem. Phys.
92
,
5397
(
1990
).
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