Environmentally friendly and earth abundant Cu2ZnSnS4 (CZTS) based thin films are potential absorbers for next generation photovoltaics. Their optical properties provide the option to be used as upper cells for Si based tandem solar cells, together with a similar structure to Si, triggering interest in investigation of CZTS/Si tandem cells. However, epitaxially growing CZTS on Si can be challenging. Here, we heteroepitaxially grow tetragonal Cu2ZnSnS4 (CZTS) thin films on single crystalline cubic Si (111) wafers with a 4° miscut by simple and low-cost radio frequency magnetron sputtering from a single target. The CZTS film displays a mirror-like surface with a surface roughness of 8.46 nm. The absorption coefficients of the epitaxial CZTS are over 104 cm−1 at 1.5 eV and 1.0 × 105 cm−1 at 2.1 eV. The bandgap is 1.45 eV, and the photoluminescence lifetime is 7.04 ns. Our results demonstrate the potential of the epitaxial CZTS films fabricated by sputtering on the Si substrate for application in CZTS/Si based tandem solar cells.

1.
S.
Levcenko
,
M.
Guc
,
C.
Merschjann
,
G.
Gurieva
,
S.
Schorr
,
M.
Lux‐Steiner
, and
E.
Arushanov
, “
Photoluminescence characterization Cu2ZnGeS4 single crystals
,”
Phys. Status Solidi C.
10
(
7–8
),
1079
1081
(
2013
).
2.
M.
Guc
,
S.
Levcenko
,
L.
Dermenji
,
G.
Gurieva
,
S.
Schorr
,
N.
Syrbu
, and
E.
Arushanov
, “
Excitonic and band-band transitions of Cu2ZnSiS4 determined from reflectivity spectra
,”
Solid State Commun.
190
,
44
48
(
2014
).
3.
N.
Song
,
M.
Young
,
F.
Liu
,
P.
Erslev
,
S.
Wilson
,
S. P.
Harvey
,
G.
Teeter
,
Y.
Huang
,
X.
Hao
, and
M. A.
Green
, “
Epitaxial Cu2ZnSnS4 thin film on Si (111) 4° substrate
,”
Appl. Phys. Lett.
106
(
25
),
252102
(
2015
).
4.
N. A.
Bojarczuk
,
T. S.
Gershon
,
S.
Guha
,
B.
Shin
, and
Y.
Zhu
,
Epitaxial Growth of CZT(S,Se) on Silicon
(
International Business Machines Corporation
,
2016
).
5.
K.
Oishi
,
G.
Saito
,
K.
Ebina
,
M.
Nagahashi
,
K.
Jimbo
,
W. S.
Maw
,
H.
Katagiri
,
M.
Yamazaki
,
H.
Araki
, and
A.
Takeuchi
, “
Growth of Cu2ZnSnS4 thin films on Si (100) substrates by multisource evaporation
,”
Thin Solid Films
517
(
4
),
1449
1452
(
2008
).
6.
B.
Shin
,
Y.
Zhu
,
T.
Gershon
,
N. A.
Bojarczuk
, and
S.
Guha
, “
Epitaxial growth of kesterite Cu2ZnSnS4 on a Si(001) substrate by thermal co-evaporation
,”
Thin Solid Films
556
(
0
),
9
12
(
2014
).
7.
C.
Yan
,
J.
Huang
,
K.
Sun
,
S.
Johnston
,
Y.
Zhang
,
H.
Sun
,
A.
Pu
,
M.
He
,
F.
Liu
,
K.
Eder
 et al, “
Cu2ZnSnS4 solar cells with over 10% power conversion efficiency enabled by heterojunction heat treatment
,”
Nat. Energy
3
(
9
),
764
(
2018
).
8.
N.
Song
,
J.
Chen
,
C.
Yan
,
X.
Wen
,
X.
Hao
, and
M. A.
Green
, “
Effect of a ZnS intermediate layer on properties of Cu2ZnSnS4 films from sputtered Zn/CuSn precursors on Si (100) substrate
,” in
IEEE 43rd Photovoltaic Specialists Conference (PVSC)
(
2016
).
9.
J.
Frantz
,
R.
Bekele
,
V.
Nguyen
,
J.
Sanghera
,
A.
Bruce
,
S.
Frolov
,
M.
Cyrus
, and
I.
Aggarwal
, “
Cu (In, Ga) Se2 thin films and devices sputtered from a single target without additional selenization
,”
Thin Solid Films
519
(
22
),
7763
7765
(
2011
).
10.
N.
Song
,
M. A.
Green
,
J.
Huang
,
Y.
Hu
, and
X.
Hao
, “
Study of sputtered Cu2ZnSnS4 thin films on Si
,”
Appl. Surf. Sci.
459
,
700
706
(
2018
).
11.
G. K.
Dalapati
,
S. K.
Batabyal
,
S.
Masudy-Panah
,
Z.
Su
,
A.
Kushwaha
,
T. I.
Wong
,
H. F.
Liu
,
T.
Bhat
,
A.
Iskander
,
Y.-F.
Lim
 et al, “
Sputter grown sub-micrometer thick Cu2ZnSnS4 thin film for photovoltaic device application
,”
Mater. Lett.
160
,
45
50
(
2015
).
12.
A.
Fairbrother
,
E.
García-Hemme
,
V.
Izquierdo-Roca
,
X.
Fontaneé
,
F. A.
Pulgarín-Agudelo
,
O.
Vigil-Galaán
,
A.
Pérez-Rodríguez
, and
E.
Saucedo
, “
Development of a selective chemical etch to improve the conversion efficiency of Zn-rich Cu2ZnSnS4 solar cells
,”
J. Am. Chem. Soc.
134
(
19
),
8018
8021
(
2012
).
13.
N.
Song
,
Y.
Wang
,
Y.
Hu
,
Y.
Huang
,
W.
Li
,
S.
Huang
, and
X.
Hao
, “
Heteroepitaxial growth of Cu2ZnSnS4 thin film on sapphire substrate by radio frequency magnetron sputtering
,”
Appl. Phys. Lett.
104
(
9
),
092103
(
2014
).
14.
N.
Song
,
W.
Li
,
X.
Hao
,
Y.
Huang
, and
M. A.
Green
, “
Radio frequency magnetron sputtered epitaxial Cu2ZnSnS4 thin film on ZnS (100)
,”
Phys. Status Solidi RRL
8
(
5
),
404
407
(
2014
).
15.
X.
Fontané
,
L.
Calvo-Barrio
,
V.
Izquierdo-Roca
,
E.
Saucedo
,
A.
Pérez-Rodriguez
,
J. R.
Morante
,
D. M.
Berg
,
P. J.
Dale
, and
S.
Siebentritt
, “
In-depth resolved Raman scattering analysis for the identification of secondary phases: Characterization of Cu2ZnSnS4 layers for solar cell applications
,”
Appl. Phys. Lett.
98
(
18
),
181905
(
2011
).
16.
N.
Song
,
X.
Wen
, and
X.
Hao
, “
Radio frequency magnetron sputtered highly textured Cu2ZnSnS4 thin films on sapphire (0001) substrates
,”
J. Alloys Compd.
632
,
53
58
(
2015
).
17.
M.
Dimitrievska
,
A.
Fairbrother
,
X.
Fontané
,
T.
Jawhari
,
V.
Izquierdo-Roca
,
E.
Saucedo
, and
A.
Pérez-Rodríguez
, “
Multiwavelength excitation Raman scattering study of polycrystalline kesterite Cu2ZnSnS4 thin films
,”
Appl. Phys. Lett.
104
(
2
),
021901
(
2014
).
18.
R.
Hunger
,
D.
Su
,
A.
Krost
,
D.
Ellmer
,
H. J.
Lewerenz
, and
R.
Scheer
, “
Structure of extended defects in epitaxial CuInS2/Si(111)
,”
Thin Solid Films
361-362
(
0
),
437
442
(
2000
).
19.
M.
Bar
,
B.-A.
Schubert
,
B.
Marsen
,
S.
Krause
,
S.
Pookpanratana
,
T.
Unold
,
L.
Weinhardt
,
C.
Heske
, and
H.-W.
Schock
, “
Native oxidation and Cu-poor surface structure of thin film Cu2ZnSnS4 solar cell absorbers
,”
Appl. Phys. Lett.
99
(
11
),
112103
(
2011
).
20.
C.
Kiely
,
R.
Pond
,
G.
Kenshole
, and
A.
Rockett
, “
A TEM study of the crystallography and defect structures of single crystal and polycrystalline copper indium diselenide
,”
Philos. Mag. A
63
(
6
),
1249
1273
(
1991
).
21.
M.
Krejci
,
A.
Tiwari
,
H.
Zogg
,
P.
Schwander
,
H.
Heinrich
, and
G.
Kostorz
, “
Rotational twins in heteroepitaxial CuInSe2 layers on Si (111)
,”
J. Appl. Phys.
81
(
9
),
6100
6106
(
1997
).
22.
Y.
Takagaki
,
U.
Jahn
,
B.
Jenichen
,
K.
Berlin
,
X.
Kong
, and
K.
Biermann
, “
Element substitution from substrates in Bi2Se3, Bi2Te3 and Sb2Te3 overlayers deposited by hot wall epitaxy
,”
Semicond. Sci. Technol.
29
(
9
),
095021
(
2014
).
23.
H.
Ahari
,
R. L.
Bedard
,
C. L.
Bowes
,
N.
Coombs
,
O.
Dag
,
T.
Jiang
,
G. A.
Ozin
,
S.
Petrov
,
I.
Sokolov
,
A.
Verma
 et al, “
Effect of microgravity on the crystallization of a self-assembling layered material
,”
Nature
388
(
6645
),
857
860
(
1997
).
24.
A.
Boulineau
,
C.
Sirisopanaporn
,
R.
Dominko
,
A. R.
Armstrong
,
P. G.
Bruce
, and
C.
Masquelier
, “
Polymorphism and structural defects in Li2 FeSiO4
,”
Dalton Trans.
39
(
27
),
6310
6316
(
2010
).
25.
D. B.
Williams
and
C. B.
Carter
,
The Transmission Electron Microscope
(
Springer
,
1996
).
26.
Y.
Yan
,
M. M.
Al-Jassim
, and
T.
Demuth
, “
Energetics and effects of planar defects in CdTe
,”
J. Appl. Phys.
90
(
8
),
3952
3955
(
2001
).
27.
S.-Y.
Li
,
C.
Hägglund
,
Y.
Ren
,
J. J. S.
Scragg
,
J. K.
Larsen
,
C.
Frisk
,
K.
Rudisch
,
S.
Englund
, and
C.
Platzer-Björkman
, “
Optical properties of reactively sputtered Cu2ZnSnS4 solar absorbers determined by spectroscopic ellipsometry and spectrophotometry
,”
Sol. Energy Mater. Sol. Cells
149
,
170
178
(
2016
).
28.
T.
Gershon
,
B.
Shin
,
N.
Bojarczuk
,
T.
Gokmen
,
S.
Lu
, and
S.
Guha
, “
Photoluminescence characterization of a high-efficiency Cu2ZnSnS4 device
,”
J. Appl. Phys.
114
(
15
),
154905
(
2013
).
29.
X.
Wen
,
P.
Yu
,
Y.-R.
Toh
,
Y.-C.
Lee
,
K.-Y.
Huang
,
S.
Huang
,
S.
Shrestha
,
G.
Conibeer
, and
J.
Tang
, “
Ultrafast electron transfer in the nanocomposite of the graphene oxide-Au nanocluster with graphene oxide as a donor
,”
J. Mater. Chem. C
2
(
19
),
3826
3834
(
2014
).
30.
S.
Chen
,
A.
Walsh
,
X. G.
Gong
, and
S. H.
Wei
, “
Classification of lattice defects in the kesterite Cu2ZnSnS4 and Cu2ZnSnSe4 earth-abundant solar cell absorbers
,”
Adv. Mater.
25
(
11
),
1522
1539
(
2013
).
31.
S.
Schorr
,
G.
Gurieva
,
M.
Guc
,
M.
Dimitrievska
,
A.
Pérez-Rodríguez
,
V.
Izquierdo-Roca
,
C. S.
Schnohr
,
J.
Kim
,
W.
Jo
, and
J. M.
Merino
, “
Point defects, compositional fluctuations, and secondary phases in non-stoichiometric kesterites
,”
J. Phys.: Energy
2
(
1
),
012002
(
2019
).
32.
S.
Kim
,
J.-S.
Park
, and
A.
Walsh
, “
Identification of killer defects in kesterite thin-film solar cells
,”
ACS Energy Lett.
3
(
2
),
496
500
(
2018
).
You do not currently have access to this content.