U.S. patent application number 13/772596 was filed with the patent office on 2013-06-27 for solar cell and method of manufacturing the same.
This patent application is currently assigned to SANYO ELECTRIC CO., LTD.. The applicant listed for this patent is Sanyo Electric Co., Ltd.. Invention is credited to Ryo Goto, Daisuke Ide, Mitsuaki Morigami, Youhei Murakami.
Application Number | 20130160847 13/772596 |
Document ID | / |
Family ID | 45723360 |
Filed Date | 2013-06-27 |
United States Patent
Application |
20130160847 |
Kind Code |
A1 |
Murakami; Youhei ; et
al. |
June 27, 2013 |
SOLAR CELL AND METHOD OF MANUFACTURING THE SAME
Abstract
A solar cell includes a solar cell substrate including a
principal surface on which a p-type surface and an n-type surface
are exposed, a p-side electrode formed on the p-type surface and
including a first linear portion linearly extending in a first
direction, and an n-side electrode formed on the n-type surface and
including a second linear portion linearly extending in the first
direction and arranged next to the first linear portion in a second
direction orthogonal to the first direction. Corners of a tip end
of at least one of the first and second linear portions are formed
in a chamfered shape.
Inventors: |
Murakami; Youhei; (Osaka,
JP) ; Ide; Daisuke; (Osaka, JP) ; Morigami;
Mitsuaki; (Osaka, JP) ; Goto; Ryo; (Osaka,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sanyo Electric Co., Ltd.; |
Osaka |
|
JP |
|
|
Assignee: |
SANYO ELECTRIC CO., LTD.
Osaka
JP
|
Family ID: |
45723360 |
Appl. No.: |
13/772596 |
Filed: |
February 21, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/JP2011/068543 |
Aug 16, 2011 |
|
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13772596 |
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Current U.S.
Class: |
136/256 ; 438/96;
438/98 |
Current CPC
Class: |
H01L 31/0465 20141201;
H01L 31/20 20130101; H01L 31/0504 20130101; Y02E 10/547 20130101;
H01L 31/022433 20130101; H01L 31/022441 20130101; H01L 31/022458
20130101; H01L 31/02167 20130101; H01L 31/0475 20141201; H01L
31/0747 20130101; H01L 31/022425 20130101; H01L 31/0682 20130101;
H01L 31/02008 20130101; H01L 31/042 20130101; H01L 31/0516
20130101; H01L 31/046 20141201 |
Class at
Publication: |
136/256 ; 438/96;
438/98 |
International
Class: |
H01L 31/0224 20060101
H01L031/0224; H01L 31/20 20060101 H01L031/20 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 24, 2010 |
JP |
2010-187407 |
Claims
1. A solar cell comprising: a solar cell substrate including a
p-type surface and an n-type surface formed on a principal surface
side of the solar cell substrate; a p-side electrode formed on the
p-type surface and including a first linear portion linearly
extending in a first direction; and an n-side electrode formed on
the n-type surface and including a second linear portion linearly
extending in the first direction and arranged next to the first
linear portion in a second direction orthogonal to the first
direction, such that corners of a tip end of at least one of the
first and second linear portions are formed in a chamfered
shape.
2. The solar cell according to claim 1, wherein the corners of the
tip ends of the first and second linear portions are formed in a
round shape.
3. The solar cell according to claim 2, wherein the tip end of at
least one of the first and second linear portions is formed in a
semicircular shape.
4. The solar cell according to claim 1, wherein the p-side
electrode further comprises a first bus bar to which the first
linear portion is connected, the n-side electrode further comprises
a second bus bar to which the second linear portion is connected,
and corners of a connection portion between at least one of the
first and second linear portions and the corresponding one of the
first and second bus bars are formed in a round shape.
5. The solar cell according to claim 4, wherein each of the first
and second bus bars is arranged so as to face the corresponding one
of the second and first linear portions in the first direction, and
a portion of at least one of the first and second bus bars facing a
tip end of the corresponding one of the second and first linear
portions in the first direction is formed in a shape corresponding
to the tip end.
6. The solar cell according to claim 4, wherein corners of the
first and second bus bars are formed in a round shape.
7. The solar cell according to claim 1, wherein the p-type surface
and the n-type surface have patterns corresponding to the p-side
electrode and the n-side electrode, respectively.
8. A method of manufacturing a solar cell including: a solar cell
substrate including a p-type surface and an n-type surface formed
on a principal surface side of the solar cell substrate; a p-side
electrode formed on the p-type surface and including a first linear
portion linearly extending in a first direction; and an n-side
electrode formed on the n-type surface and including a second
linear portion linearly extending in the first direction and
arranged next to the first linear portion in a second direction
orthogonal to the first direction, corners of a tip end of at least
one of the first and second linear portions being formed in a round
shape, the method comprising obtaining the at least one of the
first and second linear portions having the corners of the tip end
formed in the round shape, by forming an electroplated coating on a
seed layer provided on the p-type or n-type surface, the seed layer
having corners of its tip end formed in a round shape.
9. A method of manufacturing a solar cell comprises: forming a seed
layer on a-type or n-type surface of a solar cell substrate such
that corners of a tip end of the seed layer are formed in a round
shape; and forming an electroplated coating on the seed layer,
thereby forming an electrode on the-type or n-type surface whose
tip end has corners formed in a round shape.
10. The method of manufacturing a solar cell according to claim 9,
wherein the electroplated coating is formed by electroplating.
11. The method of manufacturing a solar cell according to claim 10,
further comprises: forming a p-type amorphous semiconductor layer
and an n-type amorphous semiconductor layer on a principal surface
side of the solar cell substrate, wherein the seed layer is formed
on the p-type amorphous semiconductor layer and the n-type
amorphous semiconductor layer.
12. The method of manufacturing a solar cell according to claim 11,
further comprises: forming an i-type amorphous semiconductor layer
on a principal surface side of the solar cell substrate, wherein at
least one of the p-type amorphous semiconductor layer and the
n-type amorphous semiconductor layer is formed on the i-type
amorphous semiconductor layer.
13. The solar cell according to claim 5, further comprising a
p-type amorphous semiconductor layer in the p-type surface; an
n-type amorphous semiconductor layer in the n-type surface; wherein
the p-side electrode is formed on the p-type amorphous
semiconductor layer and the n-side electrode is formed on the
n-type amorphous semiconductor layer.
14. The solar cell according to claim 13, further comprising i-type
amorphous semiconductor layer on a principal surface side of the
solar cell substrate; wherein at least one of the p-type amorphous
semiconductor layer and the n-type amorphous semiconductor layer is
formed on the i-type amorphous semiconductor layer.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of
International Application No. PCT/JP2011/068543, filed on Aug. 16,
2011, entitled "SOLAR CELL AND METHOD OF MANUFACTURING THE SAME",
which claims priority based on Article 8 of Patent Cooperation
Treaty from prior Japanese Patent Applications No. 2010-187407,
filed on Aug. 24, 2010, the entire contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This disclosure relates to a back contact solar cell and a
method of manufacturing the same.
[0004] 2. Description of the Related Art
[0005] Recently, solar cells have been drawing much attention as an
energy source placing only a small load on the environment. For
this reason, more and more research and development has been
undertaken on solar cells. In particular, an important issue is how
to improve conversion efficiency of solar cells. Hence, the
research and development has been made especially actively for
solar cells having improved conversion efficiency and methods of
manufacturing such solar cells.
[0006] As a solar cell with high conversion efficiency, Document 1
(Japanese Patent Application Publication No. 2009-200267), for
example, proposes a so-called back contact solar cell with a p-type
region and an n-type region formed on a back surface side of the
solar cell. In this back contact solar cell, electrodes for
collecting carriers do not necessarily need to be provided on a
light-receiving surface. Accordingly, light-reception efficiency
can be improved in a back contact solar cell, whereby improved
conversion efficiency can be achieved.
[0007] Note that the solar cell described in Document 1has a
comb-teeth shaped electrode formed on each of the p-type region and
on the n-type region. In Document 1, as methods of forming the
electrodes, a method of applying a conductive paste and a
sputtering method are described.
SUMMARY OF THE INVENTION
[0008] As the method of forming the electrodes, a plating method
can be used as an option other than the method using the conductive
paste or the sputtering method as described above. However, when
the electrodes are formed in the plating method, there is a problem
that it is difficult to sufficiently improve conversion efficiency
of the solar cell.
[0009] An embodiment of the invention is made in view of this
point, and aims to improve conversion efficiency of a back contact
solar cell.
[0010] A first aspect of the invention is a solar cell. The solar
cell includes a solar cell substrate, a p-side electrode, and an
n-side electrode. The solar cell substrate has a principal surface
on which a p-type surface and an n-type surface are exposed. The
p-side electrode includes a first linear portion. The first linear
portion is formed on the p-type surface. The first linear portion
extends in a first direction. The n-side electrode includes a
second linear portion. The second linear portion is formed on the
n-type surface so as to extend in the first direction. The second
linear portion is arranged next to the first linear portion in a
second direction orthogonal to the first direction. Corners of a
tip end of at least one of the first and second linear portions are
formed in a round shape.
[0011] A second aspect of the invention is a method of
manufacturing a solar cell. The solar cell includes: a solar cell
substrate including a principal surface on which a p-type surface
and an n-type surface are exposed; a p-side electrode formed on the
p-type surface and including a first linear portion extending in a
first direction; and an n-side electrode formed on the n-type
surface so as to extend in the first direction and including a
second linear portion arranged next to the first linear portion in
a second direction orthogonal to the first direction, corners of a
tip end of at least one of the first and second linear portions
being formed in a round shape. The method includes: obtaining a
linear portion whose corners of tip end are formed in a round shape
from among the first and second linear portions, by forming an
electroplated coating on a seed layer which is provided on the
p-type or n-type surface and whose corners of tip end are formed in
a round shape.
[0012] According to the aspects of the invention, conversion
efficiency of a back contact solar cell can be improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a simplified plan view of a solar cell of a first
embodiment.
[0014] FIG. 2 is a simplified cross-section taken along a line
II-II of FIG. 1.
[0015] FIG. 3 is a simplified cross-section taken along a line
III-III of FIG. 1.
[0016] FIG. 4 is an enlarged simplified plan view of a portion IV
of FIG. 1.
[0017] FIG. 5 is an enlarged simplified plan view of a portion V of
FIG. 1.
[0018] FIG. 6 is a simplified plan view of a solar cell of a
comparative example. In the comparative example shown in FIG. 6,
members having functions substantially common to the first
embodiment are assigned common reference numerals.
[0019] FIG. 7 is an enlarged simplified plan view of a portion
taken along a line VII-VII of FIG. 6.
[0020] FIG. 8 is a simplified cross-section of a solar cell of a
second embodiment.
[0021] FIG. 9 is a simplified plan view of a solar cell of a third
embodiment.
DETAILED DESCRIPTION OF EMBODIMENTS
[0022] Hereinafter, preferred embodiments of the invention are
described by using solar cell 1 shown in FIG. 1 as an example.
Note, however, that solar cell 1 is only an example. The invention
is not limited to solar cell 1 in any way.
[0023] In the drawings referenced in the embodiments and the like,
members having substantially the same functions are assigned the
same reference numerals. The drawings referenced in the embodiments
and the like are schematic. Dimensional ratios and the like of
objects depicted in the drawings may differ from actual dimensional
ratios and the like of the objects. The dimensional ratios and the
like may also differ among the drawings. Concrete dimensional
ratios and the like of the objects should be determined in
consideration of the following description.
[0024] As shown in FIGS. 1 to 3, solar cell 1 includes solar cell
substrate 10. Solar cell substrate 10 has back surface 10a as a
first principal surface, and light-receiving surface 10b as a
second principal surface. Back surface 10a of solar cell substrate
10 includes a surface of p-type region 10a1 and a surface of n-type
region 10a2.
[0025] More specifically, in the first embodiment, solar cell
substrate 10 includes semiconductor substrate 15, n-type
semiconductor layer 14n, and p-type semiconductor layer 14p.
[0026] Semiconductor substrate 15 generates carriers by receiving
light on its principal surface on a light-receiving surface side.
Here, carriers refer to holes and electrons generated when light is
absorbed by semiconductor substrate 15. Semiconductor substrate 15
is formed of a crystalline semiconductor substrate of n-type or
p-type conductivity. Specific examples of the crystalline
semiconductor substrate include crystalline silicon substrates such
as a single-crystal silicon substrate and a polycrystalline silicon
substrate, for example. Hereinbelow, the first embodiment describes
an example in which semiconductor substrate 15 is formed of an
n-type single-crystal silicon substrate.
[0027] N-type semiconductor layer 14n and p-type semiconductor
layer 14p are formed on the principal surface of semiconductor
substrate 15 on a back surface side. N-type semiconductor layer 14n
forms n-type region 10a2, and p-type semiconductor layer 14p forms
p-type region 10a1.
[0028] Each of n-type semiconductor layer 14n and p-type
semiconductor layer 14p is formed in a comb-teeth shape. N-type
semiconductor layer 14n and p-type semiconductor layer 14p are
formed to interdigitate each other. Thus, p-type region 10a1 and
n-type region 10a2 are formed in comb-teeth shapes which are
inserted between each other.
[0029] N-type semiconductor layer 14n is formed of an n-type
amorphous semiconductor layer formed on the principal surface of
semiconductor substrate 15 on the back surface side. Meanwhile,
p-type semiconductor layer 14p is formed of a p-type amorphous
semiconductor layer formed on the principal surface of
semiconductor substrate 15 on the back surface side. Note that an
i-type amorphous semiconductor layer may be interposed between
semiconductor substrate 15 and n-type amorphous semiconductor layer
14n, as well as between semiconductor substrate 15 and p-type
amorphous semiconductor layer 14p. In this case, the i-type
amorphous semiconductor layer may be formed of an i-type
hydrogenated amorphous silicon layer having a thickness which
virtually does not contribute to power generation, for example.
[0030] The p-type amorphous semiconductor layer is a semiconductor
layer of p-type conductivity, to which a p-type dopant is added.
Specifically, in the first embodiment, the p-type amorphous
semiconductor layer is made of a p-type hydrogenated amorphous
silicon. Meanwhile, the n-type amorphous semiconductor layer is a
semiconductor layer of n-type conductivity, to which an n-type
dopant is added. Specifically, in the first embodiment, the n-type
amorphous semiconductor layer is made of an n-type hydrogenated
amorphous silicon. Note that although the thickness of each of the
p-type and n-type amorphous semiconductor layers is not
particularly limited, it may be about 20 angstroms to 500
angstroms, for example.
[0031] N-side electrode 11 collecting electrons and p-side
electrode 12 collecting holes are formed on back surface 10a of
solar cell substrate 10. N-side electrode 11 is formed on a surface
of n-type semiconductor layer 14n. To be specific, n-side electrode
11 is formed on an n-type surface of n-type region 10a2. N-side
electrode 11 includes fingers 11a as linear portions and bus bar
11b. Each of fingers 11a linearly extends in a first direction y.
Fingers 11a are arranged in parallel at certain intervals in a
second direction x orthogonal to the first direction y. Bus bar 11b
is arranged on one end side (y1 side) of fingers 11a. Bus bar 11b
is formed to extend in the direction x. A y1-side end of each of
fingers 11a is connected to bus bar 11b.
[0032] P-side electrode 12 is formed on p-type semiconductor layer
14p. To be specific, p-side electrode 12 is formed on a p-type
surface of p-type region 10a1. P-side electrode 12 includes fingers
12a as linear portions and bus bar 12b. Each of fingers 12a
linearly extends in the direction y. Fingers 12a and the
aforementioned fingers 11a are arranged alternately at certain
intervals in the direction x. In other words, finger 12a is
arranged next to finger 11a in the direction x. Bus bar 12b is
arranged on the other end side (y2 side) of fingers 12a. Bus bar
12b is formed to linearly extend in the direction x. A y2-side end
of each of fingers 12a is connected to bus bar 12b. In addition,
bus bar 12b faces tip ends 11a1 of fingers 11a in the direction y,
whereas bus bar 11b faces tip ends 12a1 of fingers 12a in the
direction y.
[0033] In the first embodiment, corners of at least one of tip ends
11a1 of fingers 11a and tip ends 12a1 of fingers 12a are formed in
a chamfered shape, or more preferably, in a round shape.
Specifically, the corners of both tip ends 11a1, 12a1 of fingers
11a, 12a are formed in a chamfered shape, or more preferably in a
round shape. To be more precise, as shown in FIGS. 4 and 5,
radiuses of curvature r1, r2 of corners of both tip ends 11a1, 12a1
of fingers 11a, 12a are set to be 1/2 of widths W1, W2 of fingers
11a, 12a. Accordingly, both tip ends 11a1, 12a1 of fingers 11a, 12a
are formed in a semicircular shape.
[0034] Moreover, each of corners formed in connection portions
between bus bars 11b, 12b and fingers 11a, 12a is formed in a
chamfered shape, i.e., a shape in which sides are not orthogonal to
each other, or more preferably, formed in a round shape.
Specifically, portions 11b1, 12b1 of bus bar 11b, 12b facing tip
ends 12a1, 11a1 of fingers 12a, 11a are formed in shapes
corresponding to the shapes of tip ends 11a1, 12a1 of fingers 11a,
12a, i.e., in a semicircular shape.
[0035] Furthermore, other corners 11b2, 12b2, 11b3, 12b3 of bus bar
11b, 12b shown in FIG. 1 are also formed in a round shape. That is,
in the first embodiment, all corners of n-side electrode 11 and
p-side electrode 12 are formed in a round shape.
[0036] Next, a method of manufacturing solar cell 1 is
described.
[0037] First, solar cell substrate 10 is prepared. The method of
manufacturing solar cell substrate 10 is not particularly limited,
and solar cell 10 may be formed according to a known method, for
example. To be specific, solar cell substrate 10 can be
manufactured by forming n-type semiconductor layer 14n and p-type
semiconductor layer 14p on semiconductor substrate 15 according to
a CVD (Chemical Vapor Deposition) method, for example. Note that
although patterns of n-type semiconductor layer 14n and p-type
semiconductor layer 14p are not particularly limited, it is
preferable that n-type semiconductor layer 14n and p-type
semiconductor layer 14p have patterns in which corners of tip ends
are formed in a round shape in correspondence with the patterns of
n-side electrode 11 and p-side electrode 12. With this
configuration, carriers can be collected efficiently from n-type
semiconductor layer 14n and p-type semiconductor layer 14p to
n-side electrode 11 or p-side electrode 12.
[0038] Next, as shown in FIGS. 2 and 3, n-side electrode 11 and
p-side electrode 12 are formed. At first, seed layer 17 having the
same flat shape as n-side electrode 11 and p-side electrode 12 of
the aforementioned shapes is formed on n-type semiconductor layer
14n and p-type semiconductor layer 14p. In other words, formed is a
seed layer 17 whose corners including those at the tip ends are
formed in a round shape.
[0039] Seed layer 17 is not particularly limited as long as plating
can be performed thereon. Seed layer 17 preferably has a surface
layer made of Cu, Sn and the like. To be specific, it is preferable
that seed layer 17 is formed of a multilayer including a TCO
(Transparent Conductive Oxide) layer formed of a conductive oxide
such as indium oxide, and a metal layer made of metal such as Cu,
Sn and the like or an alloy containing one or more of these types
of metal. The method of forming seed layer 17 is not particularly
limited. Seed layer 17 may be formed by a CVD method, a sputtering
method, or a deposition method, for example. The thickness of seed
layer 17 is not particularly limited. The thickness of seed layer
17 may be about 100 nm to 500 nm, for example.
[0040] Next, electroplated coating 18 made of Cu, Sn and the like
is formed by an electroplating method, for example, on seed layer
17. Thus, n-side electrode 11 and p-side electrode 12 formed of a
multilayer including seed layer 17 and electroplated coating 18 can
be formed.
[0041] The thickness of the electroplated coating formed by the
electroplating method is correlated to the field intensity applied
at the time of performing the electroplating. The higher the field
intensity applied to the part to be electroplated, the thicker
electroplated coating 18 becomes. For this reason, if the applied
field intensity differs among portions within the part to be
electroplated, the thickness varies within the electroplated
coating. Specifically, the electroplated coating at a portion to
which high field intensity is applied becomes thicker than the
electroplated coating at a portion to which low field intensity is
applied.
[0042] Here, assume a case as in solar cell 100 of a comparative
example shown in FIG. 6 where corners of n-side electrode 11 and
p-side electrode 12 are not formed in a round shape but are sharp,
for example. In this case, lines of electric force concentrate in
the corners of n-side electrode 11 and the corners of p-side
electrode 12, and an electric field of high field intensity is
applied thereto. As a result, as shown in FIG. 7, a ratio
(t.sub.4/t.sub.3) of thickness t.sub.4 at peripheral portions of
n-side electrode 11 and p-side electrode 12 to thickness t.sub.3 at
center portions thereof becomes extremely large. Accordingly, the
peripheral portions of n-side electrode 11 and p-side electrode 12
are formed to project sharply, and their strengths are lowered.
Hence, at least one of tip end 11a1 of finger 11a and tip end 12a1
of finger 12a is deformed, so that finger 11a and finger 12a may
come into contact with each other and cause a short circuit.
Occurrence of a short circuit between finger 11a and finger 12a
lowers conversion efficiency of solar cell 100.
[0043] By enlarging the distance between n-side electrode 11 and
p-side electrode 12, it is possible to avoid the short circuit
between finger 11a and finger 12a. However, in this case, holes
being minority carriers are likely to recombine and disappear
before reaching p-side electrode 12. Thus, conversion efficiency of
the solar cell is lowered.
[0044] On the other hand, in the first embodiment, tip ends 11a1,
12a1 of fingers 11a, 12a are formed in a round shape. With this, it
is possible to avoid concentration of lines of electric force to
peripheral portions of tip ends 11a1, 12a1. Consequently, as shown
in FIG. 3, the difference in thicknesses of center portions of tip
ends 11a1, 12a1 and the peripheral portions thereof can be reduced.
More specifically, a ratio (t.sub.2/t.sub.1) of thickness t.sub.1
at the center portions of tip ends 11a1, 12a1 to thickness t.sub.2
at the peripheral portions thereof can be reduced. Moreover, in the
first embodiment, corners at the connection portions between
fingers 11a, 12a and bus bars 11b, 12b are also formed in a round
shape. Hence, the thicknesses at peripheral portions of the corners
at the connection portions between fingers 11a, 12a and bus bars
11b, 12b can also be reduced. Particularly in the first embodiment,
tip ends 11a1, 12a1 of fingers 11a, 12a are formed in a
semicircular shape and portions 11b1, 12b1 of bus bars 11b, 12b
facing tip ends 12a1, 11a1 of fingers 12a, 11a are formed in a
semicircular shape. With this, the thicknesses at peripheral
portions of tip ends 11a1, 12a1 and portions 11b1, 12b1 can be
reduced. As a result, conversion efficiency of solar cell 1 is less
likely to be lowered due to occurrence of a short circuit between
n-side electrode 11 and p-side electrode 12 attributable to
deformation of the peripheral portions of n-side electrode 11 and
p-side electrode 12. Accordingly, the space between fingers 11a and
fingers 12a can also be reduced. Hence, it is possible to avoid
recombination and disappearance of holes being minority carriers,
whereby high conversion efficiency can be achieved.
[0045] In addition, since it is possible to reduce the thicknesses
of the peripheral portions of n-side electrode 11 and p-side
electrode 12, it is possible to avoid a poor appearance where a
color tone at the peripheral portions differ from that at the
center portions.
[0046] Moreover, variation in electrical resistivity of n-side
electrode 11 and p-side electrode 12 can be reduced. Hence, it is
possible to avoid concentration of electric fields of n-side
electrode 11 and p-side electrode 12 in a specific part at the time
of power generation.
[0047] Note that the effects described above are those achievable
when the corners of tip ends 11a1, 12a1 and of portions 11b1, 12b1
are formed in a round shape. Note that in order to obtain a more
preferable effect, radiuses of curvature of the corners of tip ends
11a1, 12a1 and of portions 11b1, 12b1 are preferably within a range
of 1 to 1/2 of widths of fingers 11a, 12a, or more preferably
within a range of 3/4 to 1/2 thereof. Additionally, radiuses of
curvature of the corners of tip ends 11a1, 12a1 and of portions
11b1, 12b1 are preferably set such that a ratio of the thickness of
electroplated coating 18 at the center portion to the thickness of
the electroplated coating at the peripheral portion is 1.2 or
smaller, or more preferably set such that the ratio is 1 or
smaller.
[0048] Hereinafter, a description is given of other examples of
preferred embodiments of the invention. Note that in the following
description of the embodiments, members having functions
substantially common to the first embodiment are referred to as
having the common function, and descriptions thereof are
omitted.
Second Embodiment
[0049] FIG. 8 is a simplified cross-section of a solar cell of a
second embodiment.
[0050] The first embodiment describes an example in which solar
cell substrate 10 is formed of semiconductor substrate 15, n-type
semiconductor layer 14n, and p-type semiconductor layer 14p.
However, the invention is not limited to this configuration. For
example, as shown in FIG. 8, solar cell substrate 10 maybe formed
of an n-type crystalline semiconductor substrate 15 including a
first principal surface in which n.sup.+ type thermal diffusion
area 15n and p-type thermal diffusion area 15p are formed. An
n-type dopant is thermally diffused in n+ type thermal diffusion
area 15n, and a p-type dopant is thermally diffused in p-type
thermal diffusion area 15p.
Third Embodiment
[0051] FIG. 9 is a simplified plan view of a solar cell of a third
embodiment.
[0052] The first embodiment describes an example in which n-side
electrode 11 and p-side electrode 12 are respectively formed of
fingers 11a, 12a and bus bars 11b, 12b. However, the invention is
not limited to this configuration. For example, as shown in FIG. 9,
n-side electrode 11 and p-side electrode 12 may respectively be
formed of fingers 11a. 12a with no bus bar provided thereto.
Other Modified Example
[0053] The first embodiment describes a case where all corners of
n-side electrode 11 and p-side electrode 12 are formed in a round
shape. However, the invention is not limited to this configuration.
For example, a configuration may be employed in which only corners
of tip ends 11a1, 12a1 of fingers 11a, 12a are formed in a
chamfered shape.
* * * * *