Thin silicon solar cells with SiОх /SiNx Bragg mirror rear surface reflector
. Bragg reflectors consisting of sequence of dielectric layers with a quarter wavelengths optical thickness are promising to create solar cells of third generation. SiОх /SiNx Bragg mirror (BM) at the backside of textured multicrystalline silicon solar cells was fabricated by PECVD method. BM wit...
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irk-123456789-1188452017-06-01T03:06:47Z Thin silicon solar cells with SiОх /SiNx Bragg mirror rear surface reflector Ivanov, I.I. Nychyporuk, T.V. Skryshevsky, V.A. Lemiti, M. . Bragg reflectors consisting of sequence of dielectric layers with a quarter wavelengths optical thickness are promising to create solar cells of third generation. SiОх /SiNx Bragg mirror (BM) at the backside of textured multicrystalline silicon solar cells was fabricated by PECVD method. BM with 9 bi-layers was optimized for the maximum reflectivity within the wavelength range Δλ = 820...1110 nm. The maximum measured reflectivity is approximately 82 %. Measured reflectivity values were compared with the simulated ones by using the transfer matrix. Effect of parameters for pyramids of several types on the total reflectivity of BM deposited on textured silicon surface was simulated. Enhancement of light absorption and external quantum efficiency in the longwave part of the spectrum (λ > 940 nm) was observed, and it was explained as increase of the photon absorption length. The influence of BM on passivation of SC rear surface was explored. The cell back contact was formed by Al diffusion through BM to the μc-Si wafer and promoted by a pulsed laser. For SC with BM, the efficiency 13.75 % is obtained comparatively with efficiency 13.58 % for SC without BM. 2009 Article Thin silicon solar cells with SiОх /SiNx Bragg mirror rear surface reflector / I.I. Ivanov, T.V. Nychyporuk, V.A. Skryshevsky, M. Lemiti // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2009. — Т. 12, № 4. — С. 406-411. — Бібліогр.: 9 назв. — англ. 1560-8034 PACS 42.79.Bh, 78.66.Db, 84.60.Jt http://dspace.nbuv.gov.ua/handle/123456789/118845 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
| language |
English |
| description |
. Bragg reflectors consisting of sequence of dielectric layers with a quarter
wavelengths optical thickness are promising to create solar cells of third generation.
SiОх /SiNx Bragg mirror (BM) at the backside of textured multicrystalline silicon solar
cells was fabricated by PECVD method. BM with 9 bi-layers was optimized for the
maximum reflectivity within the wavelength range Δλ = 820...1110 nm. The maximum
measured reflectivity is approximately 82 %. Measured reflectivity values were
compared with the simulated ones by using the transfer matrix. Effect of parameters for
pyramids of several types on the total reflectivity of BM deposited on textured silicon
surface was simulated. Enhancement of light absorption and external quantum efficiency
in the longwave part of the spectrum (λ > 940 nm) was observed, and it was explained as
increase of the photon absorption length. The influence of BM on passivation of SC rear
surface was explored. The cell back contact was formed by Al diffusion through BM to
the μc-Si wafer and promoted by a pulsed laser. For SC with BM, the efficiency 13.75 %
is obtained comparatively with efficiency 13.58 % for SC without BM. |
| format |
Article |
| author |
Ivanov, I.I. Nychyporuk, T.V. Skryshevsky, V.A. Lemiti, M. |
| spellingShingle |
Ivanov, I.I. Nychyporuk, T.V. Skryshevsky, V.A. Lemiti, M. Thin silicon solar cells with SiОх /SiNx Bragg mirror rear surface reflector Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Ivanov, I.I. Nychyporuk, T.V. Skryshevsky, V.A. Lemiti, M. |
| author_sort |
Ivanov, I.I. |
| title |
Thin silicon solar cells with SiОх /SiNx Bragg mirror rear surface reflector |
| title_short |
Thin silicon solar cells with SiОх /SiNx Bragg mirror rear surface reflector |
| title_full |
Thin silicon solar cells with SiОх /SiNx Bragg mirror rear surface reflector |
| title_fullStr |
Thin silicon solar cells with SiОх /SiNx Bragg mirror rear surface reflector |
| title_full_unstemmed |
Thin silicon solar cells with SiОх /SiNx Bragg mirror rear surface reflector |
| title_sort |
thin silicon solar cells with siох /sinx bragg mirror rear surface reflector |
| publisher |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| publishDate |
2009 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/118845 |
| citation_txt |
Thin silicon solar cells with SiОх /SiNx Bragg mirror
rear surface reflector / I.I. Ivanov, T.V. Nychyporuk, V.A. Skryshevsky, M. Lemiti // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2009. — Т. 12, № 4. — С. 406-411. — Бібліогр.: 9 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
| work_keys_str_mv |
AT ivanovii thinsiliconsolarcellswithsiohsinxbraggmirrorrearsurfacereflector AT nychyporuktv thinsiliconsolarcellswithsiohsinxbraggmirrorrearsurfacereflector AT skryshevskyva thinsiliconsolarcellswithsiohsinxbraggmirrorrearsurfacereflector AT lemitim thinsiliconsolarcellswithsiohsinxbraggmirrorrearsurfacereflector |
| first_indexed |
2025-07-08T14:46:20Z |
| last_indexed |
2025-07-08T14:46:20Z |
| _version_ |
1837090454625058816 |
| fulltext |
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 4. P. 406-411.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
406
PACS 42.79.Bh, 78.66.Db, 84.60.Jt
Thin silicon solar cells with SiОх /SiNx Bragg mirror
rear surface reflector
I.I. Ivanov1, T.V. Nychyporuk2, V.A. Skryshevsky1, M. Lemiti2
1Taras Shevchenko Kyiv National University, Faculty of Radiophysics,
build. 5, 2, Academician Glushkov prospect, 03022 Kyiv, Ukraine
E-mail: ivancko@gmail.com
2Institut des Nanotechnologies de Lyon, UMR CNRS 5270, Université de Lyon, INSA Lyon, Bât. Blaise Pascal, 7
avenue Jean Capelle, 69621 Villeurbanne Cedex, France
Abstract. Bragg reflectors consisting of sequence of dielectric layers with a quarter
wavelengths optical thickness are promising to create solar cells of third generation.
SiОх /SiNx Bragg mirror (BM) at the backside of textured multicrystalline silicon solar
cells was fabricated by PECVD method. BM with 9 bi-layers was optimized for the
maximum reflectivity within the wavelength range Δλ = 820...1110 nm. The maximum
measured reflectivity is approximately 82 %. Measured reflectivity values were
compared with the simulated ones by using the transfer matrix. Effect of parameters for
pyramids of several types on the total reflectivity of BM deposited on textured silicon
surface was simulated. Enhancement of light absorption and external quantum efficiency
in the longwave part of the spectrum (λ > 940 nm) was observed, and it was explained as
increase of the photon absorption length. The influence of BM on passivation of SC rear
surface was explored. The cell back contact was formed by Al diffusion through BM to
the μc-Si wafer and promoted by a pulsed laser. For SC with BM, the efficiency 13.75 %
is obtained comparatively with efficiency 13.58 % for SC without BM.
Keywords silicon solar cell, Bragg mirror, numerical simulation.
Manuscript received 11.06.09; accepted for publication 10.09.09; published online 30.10.09.
1. Introduction
Nowadays, the 1st generation of Si solar cells (SC) based
on bulk Si technology dominates the photovoltaic
market [1]. However, the important limitation of this
matured technology is the cost per Watt. In order to
reduce the costs of fabrication of Si based SC one of the
possible ways is to decrease the volume of primary
material involved into this fabrication. Another approach
is to increase the photovoltaic conversion efficiency.
Indeed, for a single junction Si SC the efficiency limit is
only 29 % mainly because of two power losses
mechanisms. The first one concerns the absorption by Si
SC the high energy photons generating the electron-hole
pairs with energy greater than the band gap of Si. The
excess of the energy is then dissipated mainly by heat
losses. Whereas the second one is inability of SC to
absorb the photons with energies less than the band gap
of Si. The latter mechanism of losses is not negligible
and in the case of standard sun illumination achieves
23.5 % of the total incident power of the sunlight [2].
This effect is even more crucial for thin SC. One of the
ways to diminish these losses is to increase the optical
path for weakly absorbed photons within the SC [3].
Bragg mirrors (BM) as rear surface reflectors could
provide the conditions for multi-passing of IR photons
within the SC. BM is a structure of an alternating
sequence of layers with different reflection indexes [4].
Each layer has the optical thickness λ0 /4, where λ0 –
wavelength of BM maximum reflection coefficient.
Reflected light components from interfaces between the
two layer interfaces interfere, which results in reflection
amplification. Schematic representation of paths for
infrared light with the intensity I inside SC with and
without BM rear reflector is shown in Fig. 1. The
reflected light intensity *
RІ for the interface Si/BM and
reflected light intensity RІ for the interface Si/air obeys
inequality *
RІ > RІ inside the Bragg peak (BP)
bandwidth. The transmitted light intensity *
TІ for SC
with BM is much less than the transmitted light intensity
TІ for SC without BM. These relationships are valid
inside the Bragg peak region. After reflection, the low
energy photons are returned towards SC bulk.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 4. P. 406-411.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
407
Fig. 1. Schematic representation of paths for infrared light with
the intensity I inside SC (a) without and (b) with BM, W is the
SC thickness.
It should be noted that the rear surface passivation
is a crucial step for SC fabrication. Hence, the BM
realized on the rear surface must satisfy two conditions:
assure the reflection of low energy photons and provide
good passivation. For this reason, the usual metallic
layers evaporated on the back surface of SC cannot be
used. On the one hand, the reflection coefficient of
metals in the IR spectral region is high enough. For
example, for Al it can reach 95 % at 1150 nm. On the
other point of view, during the firing process the metals
can easily diffuse into the silicon and thus forming a
rather considerable number of recombination centers.
Various methods of BM fabrication of the rear
surface of silicon SC have already been developed.
Duerinck et al. have recently reported on fabrication of
reorganized porous silicon Bragg reflectors for thin-film
silicon SC [5]. Indeed, refractive index of porous silicon
can be tuned within the wide range going from 2.7 to 1.3
making it a good candidate for BM fabrication. The
authors showed that the stacks of porous silicon layers
have been successfully applied to maximize internal
reflection at the interface between a silicon substrate and
epitaxially grown layer. An optical-path-length
enhancement factor of seven was calculated in the
wavelength range of 900-1200 nm. The gain of 12 % in
short-circuits current and efficiency was thus shown in
thin-film epitaxial SC.
Another interesting approach was recently
explored. Conducting BM were fabricated on the base of
TiO2 nanostructures [6]. Periodic modulation of the
refractive index was achieved by controlling the degree
of porosity for each alternate layer through the particle
size distribution of the precursor suspensions.
Photoelectrochemical measurements show that the BM
are conductive and can be a good candidate for rear
surface reflector of SC.
However, all these methods cannot be implemented
directly for industrial SC fabrication and need crucial
changes in the existing photovoltaic technological
process. In this work, we report on the SiОх /SiNx Bragg
rear reflector fabrication for industrial type thin SC. The
optical and photoelectrical characteristics of realized SC
are discussed in details.
2. Numerical simulation
BM is a structure which consists of an alternating
sequence of layers made of two different optical
materials with refractive indexes nH and nL, the optical
thickness of the layers for normal incidence corresponds
to λ0 /4. Other important characteristics of a BM are the
reflection coefficient Rmax at λ0, the reflection bandwidth
λBP at 0.99Rmax, left and right border spectral positions
λL, λR at 0.99Rmax.
Evolutions of λL and λR versus nH /nL ratio are
presented in Fig. 2 for three different Bragg wavelengths
�0 (quantity of bi-layers = 10). As can be seen from the
figure, the response bandwidth of the BM is wider for
layers having a higher refractive index contrast. Left and
right spectral borders shift to the short and longwave
spectral regions, respectively.
Fig. 3a presents the reflection coefficient of the
mirror at the Bragg wavelength versus nH /nL ratio for
different numbers of layer pairs. The increase in layer
pairs results in a higher refection coefficient Rmax at the
Bragg wavelength for a lower ratio value nH /nL, but the
value of the refection coefficient Rmax(λ0) = 99 % can be
obtained for the bi-layer number Nbi = 4 when
nH /nL > 1.8 (Fig. 3).
The bi-layer number increase from Nbi = 4 up to 14
leads to BM width increasing (Fig. 3b). For ratio
nH/nL = 2, BM width increases by 31 % when the bi-
layer number changes from Nbi = 4 up to 6. The
following bi-layer number increase to Nbi = 14 does not
result in a considerable growth of the BM width λBP.
The software PC1D [7, 8] was used for simulation
of SC parameters. To do that for SC with BM, the
following parameters were used: Si wafer thickness was
200 μm, emitter thickness was 500 nm, emitter doping
was Nd = 3∙1020 cm-3, base doping was Na =1016 cm-3,
both side texturing with the pyramid base angle 54.74º
and pyramid height 5 μm.
The external quantum efficiency (EQE) and I-V
dependence at various internal front and rear reflection
coefficients (R1, R2) of sunrays inside the textured Si
wafer was calculated (Fig. 4). As can be seen from
Fig. 4, using the BM as a backside reflector leads to
EQE curve shift to the longwave spectral region at
λ > 955 nm.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 4. P. 406-411.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
408
1.0 1.1 1.2 1.3 1.4 1.5
800
850
900
950
1000
1050
1100
,
n
m
n
H
/n
L
0
= 900 nm
0
= 940 nm
0
= 1000 nm
Fig. 2. Response bandwidth of the BM versus nH /nL ratio for
three different Bragg wavelengths.
1.0 1.2 1.4 1.6 1.8 2.0
40
60
80
100
4
14
0
=800 nm
R
,
%
n
H
/n
L
N
bi-layer
= 4
N
bi-layer
= 6
N
bi-layer
= 8
N
bi-layer
= 10
N
bi-layer
= 14
a)
1.0 1.2 1.4 1.6 1.8 2.0
0
100
200
300
400
N
bi-layer
= 14
0
=800 nm
R
ef
le
ct
io
n
b
a
n
d
w
id
th
o
f
th
e
B
M
at
0
.9
9R
m
a
x
, n
m
n
H
/n
L
N
bi-layer
= 4
N
bi-layer
= 6
N
bi-layer
= 8
N
bi-layer
= 10
N
bi-layer
= 14
N
bi-layer
= 4 b)
Fig. 3. Dependence of Rmax(λ0) reflection coefficient (a) and
Bragg peak width at 0.99Rmax (digits show the quantity of bi-
layers) (b) on nH/nL ratio for different bi-layer number.
950 1000 1050 1100 1150 1200
0
20
40
60
80
DBM
SC with DBM
R
1
=95%, R
2
=5%
E
Q
E
, %
, nm
reference SC
R
1
=5%, R
2
=5%
R
1
R
2
Fig. 4. EQE versus the wavelength for various front and rear
internal reflection coefficients (R1, R2).
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
-40
-35
-30
-25
-20
-15
-10
-5
0
I
oc
=34.4 mA/cm2
U
sc
=0.6115 V
Efficiency=16.3 %
I,
m
A
/c
m
2
U, V
R
1
=R
2
= 95%
R
1
=R
2
= 30%
I
oc
=32.7 mA/cm2
U
sc
=0.61 V
Efficiency=15.5 %
Fig. 5. I-V dependence for different values of internal
reflection coefficients inside Si wafer.
The simulation results show that the light beam
path increase caused by internal multiple beam bouncing
inside the wafer leads to the short-current increase (Isc).
Isc and SC efficiency increases by 5 % when internal
reflection coefficients grow from 20 up to 95 % (Fig. 5).
3. Multicomponent Bragg mirror spectral response
simulation
Multicrystalline silicon wafers used for SC production
consist of Si grains with various crystal-lattice
orientations (CLO) i and areas Si. One of the SC
production steps is wafer etching in KOH-base solution
for both-side surface texturing in the shape of pyramids.
Geometry of etched pyramids is determined by CLO,
however, the certain surface grains are badly etched and
pyramids do not form. The light beam path inside Si
wafer depends on both front and rear SC surface
pyramids type and incoming light angle into Si wafer.
The reflection coefficient of every grain in Si wafer with
BM depends on pyramid parameters because the BM
reflection coefficient depends on the light incidence
angle. The spectral response of multicrystalline silicon
wafer with rear side BM is equal to the sum of BM
spectral responses of grain components:
M
j
i
j
N
i
im SRR
10
Si = , (1a)
M
j
i
ji SS
1
= ,
N
i
iSS
1
= , (1b)
where Ri is the reflection coefficient of an elementary Si
grain with i CLO, S is the total Si wafer area, Si is the
grain area with i CLO. The total reflection response of
multicrystalline silicon wafer is determined by weighted
summation of separate grain reflection coefficients Ri.
Weighted coefficients are determined by a cluster with
area Si and reflection coefficients Ri.
Fig. 6 shows the light paths inside the both-side
textured wafer 100 with pyramid base angle 54.74º of
light beam incidence. The angles on the BM rear side are
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 4. P. 406-411.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
409
Fig. 6. The light paths inside Si both-side textured wafer
100 at normal beam incidence on SC front.
4.45º, 13.49º, 25.45º. The values of internal angles
depend on the number of beam reflections from the front
side. The total BM spectral response dependence on the
incidence angle is shown in Fig. 7. The increase in this
angle causes BM position shift to the shortwave spectral
region and BM width growth from 0
w up to w . The
central region on the spectral dependence with a high
reflection coefficient ( w ) remains nonshifted, when the
angle of incidence increases from 0º up to 90º.
Fig. 8 shows the simulated spectral dependence of
reflection from BM that consists of two grains (BM
position at λBM1 = 800 nm and λBM2 = 940 nm). Fig. 8
depicts the reflection coefficient is high at the w
region, if the spectral responses of Bragg peaks are
overlapped in this region. The resulting spectral response
of many-component BM is determined by the position
and amplitude of non-main side peaks for BM
component. The spectral response of many-component
BM is more complicated comparatively with that of the
two-component BM.
Fig. 7. BM reflection coefficient dependence on the
wavelength and incident angle (0 = 940 nm, bi-layer number
Nbi = 9).
Fig. 8. Total reflection coefficient and separate mirror
contributions to total response of two-component BM versus
the wavelength (λBM1 = 800 nm and λBM2 = 940 nm, number of
bi-layers is 10).
4. Effect of SiОх /SiNx Bragg mirror on solar cell
parameters
A square p-type multicrystalline silicon wafer was used
as a base for SC with dielectric Bragg mirror (DBM)
manufacturing (Na = 1016 cm-3, wafer size is
125×125 mm, wafer thickness is 200 m). The emitter
thickness and doping were 500 nm and Nd = 3∙1020 cm-3,
respectively. The wafer was both-side textured by KOH
etching (texturing depth is 5 m). p-n junction was
formed after texturing. Back surface field p+ region was
doped up to Na = 5∙1018 cm-3. Antireflection SiNx coating
was deposited on the front SC surface to decrease front
surface reflection. Antireflection coating parameters
were chosen to obtain the minimum reflectivity at λ =
600 nm. DBM was formed on rear side of Si wafer by
using successive deposition of SiОх (nL = 1.46, LL =
161 nm) and SiNx (nH = 2.2, LH = 107 nm) layers with
PECVD method. DBD scheme is depicted in Fig. 9. The
total DBM thickness was 2.4 m. To improve Al
diffusion through DBM to Si wafer, DBM was
perforated with laser beam (λlaser = 470 nm, P =
1200 mW). The distance between holes was 1.5 mm,
hole diameters were 80 m. Fig. 10 shows SEM image
of SC with DBM. DBM layers with different reflection
indexes are represented with different intensity bars at
the SEM image.
Reflection and transmission coefficients of tested
SC with DBM were measured using the integration
sphere. The absolute values of reflection and
transmission were obtained with calibrated reflection
standards.
Spectral dependences of the reflection coefficient
of five BMs that were measured from rear SC side are
shown in Fig. 11. The reflection coefficients at BM
maxima are varied within the range from 63 up to 82 %.
Some differences between the experimental curves (SC
without DBM No.1 - 2 and SC with DBM No.1 - 5) and
the simulated one can be caused by dispersion of
reflection indexes in DBM layers, because Si wafers
were located at different heights inside the chemical
reactor.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 4. P. 406-411.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
410
0 500 1000 1500 2000 2500
1.0
1.5
2.0
2.5
3.0
3.5
L
H
n
x, nm
Bragg mirror
9 bi-layers
L
L
Si
a)
Fig. 9. a) Scheme of SC with DBM on the base of SiNx /SiOx;
b) scheme of SC rear side with laser assisted perforation
through BM.
Fig. 10. SEM image of DBM at textured SC rear surface (9 bi-
layers).
800 900 1000 1100 1200 1300 1400
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
R
, %
, nm
SC without DBM №1
SC without DBM №2
SC with DBM №1
SC with DBM №2
SC with DBM №3
SC with DBM №4
SC with DBM №5
Simulation
0
=940 nm Rear side of SCSimulation
Fig. 11. Simulated and measured reflection dependences of SC
with DBM.
400 600 800 1000 1200
0.0
0.1
0.2
0.3
0.4
0.5
0.6
SC with DBM
R
av
g
, nm
a)
Si
200 400 600 800 1000 1200
0.00
0.05
0.10
0.15
0.20
0.25
0.30
Si
T
a
vg
, nm
b)
SC with DBM
400 600 800 1000 1200
0.2
0.3
0.4
0.5
0.6
0.7
0.8
SC with DBM
av
g
,
m
-1
, nm
c)
Si
400 600 800 1000 1200
0.0
0.2
0.4
0.6
0.8
1.0
SC with DBM
E
Q
E
a
vg
, nm
d)
Reference SC
Fig. 12. Comparison of SC with and without DBM: a) spectral
dependence of the reflection coefficient; b) spectral
dependence of the transmission coefficient; c) spectral
dependence of the absorption coefficient; d) spectral
dependence of the external quantum efficiency.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 4. P. 406-411.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
411
Fig. 13. Lifetime dependence on the surface of SC for
passivated and non-passivated parts.
Fig. 12 shows the averaged spectral dependences of
the front surface reflection coefficient (Fig. 12a),
transmission coefficient (12b), absorption coefficient
(12c), EQE for SC with DBM comparatively with those
of the sample without DBM. Results of five SC with
DBM were used for averaging. The presence of DBM
results in increase of the reflection coefficient for DBM,
absorption coefficient in SC and EQE within the
longwave range. Curves for SC with DBM and without
DBM do not differ for the spectral range λ < 1000 nm.
To verify the passivation effect of DBM presence
on the lifetime of minority charge carriers, SC with
DBM were annealed for 15 s at 720 ºC in oxygen
atmosphere. Fig. 13 shows the mapping of the electron
lifetime for SC with DBM. For the same wafer, one
part was passivated and another was not. The electron
lifetime increases after passivation. The presence of
DBM does not cause the decrease for SC with DBM.
The maximal life time of electrons increases from 5.7 up
to 11 s, while the average electron lifetime increases
from 5.53 up to 11.14 s.
Using the SunUoc method [9], the serial resistance
value Rs = 2 Ohm and pseudo fill factor PFF = 74.7 %
(fill factor without Rs effect) were determined. Results of
I-V dependence analysis are summarized in Table.
Table. Cell parameters.
Isc,
mA/cm2 Uoc, V
FF,
%
Efficiency,
%
Solar cell
with DBM
33 0.587 71 13.75
Solar cell
without
DBM
32.3 0.584 72 13.58
5. Conclusions
Using the BM allows to improve the absorption in the
longwave spectral range due to the photon path increase
inside Si wafer. EQE improvement is observed within
the spectral range from 940 to 1200 nm. The standard
PECVD method can be used to produce BM as a set of
SiОх /SiNx layers with an optimized BM position and
width. The total reflection coefficient of both-side
textured SC with DBM depends on geometry of
pyramids and their type as well as ratio between
different types of pyramids. DBM as a dielectric stack
displays also the good passivation properties – the
maximum lifetime of minority charge carriers increases
from 5.7 up to 11 s. For SC with DBM, the efficiency
was 13.75 % as compared with that 13.58 % for SC
without DBM.
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