Radiation Tolerant Nanowire Array Solar Cells
Pilar Espinet-Gonzalez
†
, Enrique Barrigón
‡
, Gaute Otnes
‡,#
, Giuliano Vescovi
§
, Colin
Mann
ǁ
, Ryan M. France
┴
, Alex J. Welch
†
, Matthew S. Hunt
, Don Walker
ǁ
, Michael D.
Kelzenberg
†
, Ingvar Åberg
§
, Magnus Borgström
‡
, Lars Samuelson
‡,§
and Harry A.
Atwater
,*,†
†
Department of Applied Physics and Materials Science, California Institute of
Technology, Pasadena, CA 91125, United States
‡
Division of Solid State Physics, Lund University, Lund, SE-221 00, Sweden
§
Sol Voltaics AB, Lund, SE-223 63, Sweden
ǁ
The Aerospace Corporation, El Segundo, CA 90245-4609, United States
┴
National Renewable Energy Laboratory, Golden, CO 80401, United States
The Kavli Nanoscience Institute, California Institute of Technology, Pasadena, CA
91125, United States
#
Institute for Energy Technology, Kjeller, NO-2007, Norway
*
e-mail:
haa@caltech.edu
Table S.1
Summary of the characteristics of the devices included in each irradiation test.
Particle &
Energy
Fluence
#particles/cm
2
Solar cell
V
oc0
mV
J
sc0
mA/cm
2
V
oc
mV
J
sc
mA/cm
2
Area
mm
2
NW GaAs
933±4
17.5±0.9
839±1
16.6±0.9
1.049
1·10
11
Planar InGaP
1356±5
8.07±0.1
1160±9
6.50±0.04
10
NW GaAs
884±3
16.9±0.2
712±3
14.8±0.5
1.049
5·10
11
Planar InGaP
1356±5
8.07±0.1
1060±3
5.69±0.02
10
NW GaAs
924±9
13.4±0.8
742±1
9.7±0.7
1.049
NW InP
613±7
16.7±0.1
507±9
15.9±0.3
0.86
p
+
100 keV
1·10
12
Planar InGaP
1356±5
8.07±0.1
1030±1
4.87±0.04
10
NW GaAs
949±11
16.9±0.3
947±8
18.0±0.05
1.049
NW InP
458±7
15.8±0.4
456±7
16.0±0.5
0.86
1·10
10
planar GaAs
858±37
18.3±0.08
780±7
18.0±0.2
8.41
NW GaAs
912±9
15.9±1.2
887±7
16.1±1.2
1.049
1·10
11
planar GaAs
950±14
18.4±0.15
644±1
15.3±0.3
8.41
NW GaAs
902±6
17.6±0.2
748±2
16.6±0.3
1.049
NW InP
454±7
15.6±0.6
367±7
14.6±0.5
0.86
p
+
350 keV
1·10
12
planar GaAs
1014±1
16.1±0.12
454±3
1.8±0.01
8.41
5·10
14
NW GaAs
895±5
16.8±0.4
870±4
16.6±0.3
1.049
e
-
1 MeV
5·10
15
NW GaAs
895±7
16.7±0.04
872±4
16.6±0.04
1.049
NW GaAs
930±18
17.5±0.5
838±3
16.3±0.9
1.049
5·10
15
NW InP
635±15
13.4±0.4
635±15
13.2±0.3
0.86
None of the solar cells tested have antireflecting coating.
Figure S.1
. Comparison of the degradation rate between planar and NW GaAs solar
cells under proton irradiation. A correction factor has been used in the planar
degradation curves to compare the degradation slope of planar
versus
NW solar cells.
We have applied a correction factor (c) to the planar degradation curves to extrapolate
the degradation rate expected in NW solar cells (c (E = 100 keV) = 13 and
c (E = 350 keV) = 40). The extrapolated NW degradation curves (x = Fluence
planar
*c; y =
degradation ratio
planar
) represented in figure S.1 show a very close match with the
degradation data obtained experimentally for the NW solar cells at both energies (100
keV and 350 keV).
Figure S.2
. Cross-section sketch of the NW structures simulated with the Monte Carlo
code: core-shell (left) and vacuum (right).
Figure S.3
. Electronic energy loss profiles under the irradiation with normal incident
protons. False color maps representing the integrated electronic energy loss over the
NW diameter (160 nm) under the irradiation with 100 keV protons (a) and 350 keV
protons (b).
In order to simplify the interpretation of the simulations basic NW arrays have been
modeled. The NW array consists of a GaAs NW with a radius of 80 nm and a pitch of
500 nm infilled with BCB. Periodic boundary conditions have been considered laterally.
No core-shell of Al
0.9
Ga
0.1
As or SiO
2
insulating layer has been included in the
simulations. An increment on the electronic power loss in the BCB around the NW due
to scattered ions from the GaAs NW is particularly noticeable at a depth >250 nm and
>750 nm in the irradiation with 100 keV and 350 keV respectively.
Figure S.4
. Transmission electron microscopy images of a NW solar cell irradiated with
100 keV p
+
at a fluence of 10
12
p
+
/cm
2
.