U.S. patent application number 13/654617 was filed with the patent office on 2013-02-14 for photovoltaic device.
The applicant listed for this patent is Seung-Jae JUNG, Ku-Hyun KANG, Jung-Tae KIM, Byoung-Kyu LEE, Czang-Ho LEE, Mi-Hwa LIM, Yuk-Hyun NAM, Min-Seok OH, Min PARK, Joon-Young SEO, Myung-Hun SHIN. Invention is credited to Seung-Jae JUNG, Ku-Hyun KANG, Jung-Tae KIM, Byoung-Kyu LEE, Czang-Ho LEE, Mi-Hwa LIM, Yuk-Hyun NAM, Min-Seok OH, Min PARK, Joon-Young SEO, Myung-Hun SHIN.
Application Number | 20130037086 13/654617 |
Document ID | / |
Family ID | 41693010 |
Filed Date | 2013-02-14 |
United States Patent
Application |
20130037086 |
Kind Code |
A1 |
PARK; Min ; et al. |
February 14, 2013 |
PHOTOVOLTAIC DEVICE
Abstract
A photovoltaic device and a manufacturing method thereof are
provided. The photovoltaic device includes: a substrate; a first
conductive layer formed on the substrate; P layers and N layers
alternately formed along a first direction on the first conductive
layer; and I layers covering the P layers and the N layers on the
first conductive layer, wherein the P layers and the N layers are
separated from each other by a first interval, the I layers are
formed between the P layers and the N layers that are separated by
the first interval, and the P layers, the I layers, and the N
layers formed along the first direction form unit cells.
Inventors: |
PARK; Min; (Yongin-si,
KR) ; OH; Min-Seok; (Yongin-si, KR) ; KIM;
Jung-Tae; (Yongin-si, KR) ; LEE; Czang-Ho;
(Yongin-si, KR) ; SHIN; Myung-Hun; (Yongin-si,
KR) ; LEE; Byoung-Kyu; (Yongin-si, KR) ; KANG;
Ku-Hyun; (Yongin-si, KR) ; NAM; Yuk-Hyun;
(Yongin-si, KR) ; JUNG; Seung-Jae; (Yongin-si,
KR) ; LIM; Mi-Hwa; (Yongin-si, KR) ; SEO;
Joon-Young; (Yongin-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PARK; Min
OH; Min-Seok
KIM; Jung-Tae
LEE; Czang-Ho
SHIN; Myung-Hun
LEE; Byoung-Kyu
KANG; Ku-Hyun
NAM; Yuk-Hyun
JUNG; Seung-Jae
LIM; Mi-Hwa
SEO; Joon-Young |
Yongin-si
Yongin-si
Yongin-si
Yongin-si
Yongin-si
Yongin-si
Yongin-si
Yongin-si
Yongin-si
Yongin-si
Yongin-si |
|
KR
KR
KR
KR
KR
KR
KR
KR
KR
KR
KR |
|
|
Family ID: |
41693010 |
Appl. No.: |
13/654617 |
Filed: |
October 18, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12486654 |
Jun 17, 2009 |
8294021 |
|
|
13654617 |
|
|
|
|
Current U.S.
Class: |
136/249 |
Current CPC
Class: |
H01L 31/022441 20130101;
H01L 31/075 20130101; H01L 31/022425 20130101; H01L 31/046
20141201; Y02E 10/548 20130101 |
Class at
Publication: |
136/249 |
International
Class: |
H01L 31/0224 20060101
H01L031/0224 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 23, 2008 |
KR |
10-2008-0104295 |
Nov 7, 2008 |
KR |
10-2008-0110615 |
Claims
1.-19. (canceled)
20. A photovoltaic device, comprising: a first cell comprising a
lower first conductive layer, a first light absorption layer, and
an upper second conductive layer sequentially deposited on a
substrate; and a second cell neighboring the first cell, and
comprising a lower second conductive layer, a second light
absorption layer, and an upper first conductive layer sequentially
deposited on the substrate, wherein the first light absorption
layer and the second light absorption layer are formed at the same
layer and are connected to each other.
21. The photovoltaic device of claim 20, wherein the lower first
conductive layer of the first cell and the lower second conductive
layer of the second cell are separated from each other.
22. The photovoltaic device of claim 21, wherein the upper second
conductive layer of the first cell and the upper first conductive
layer of the second cell are formed with the same layer as the
first and second light absorption layer, and are electrically
disconnected from each other.
23. The photovoltaic device of claim 22, further comprising a
depletion region formed between the upper second conductive layer
of the first cell and the upper first conductive layer of the
second cell.
24. The photovoltaic device of claim 23, further comprising an
electrode portion formed between the upper second conductive layer
of the first cell and the upper first conductive layer of the
second cell.
25. The photovoltaic device of claim 24, wherein the electrode
portion comprises protrusions, depressions, and a flat portion, and
the width of the flat portion is substantially equal to or less
than the width between the lower first conductive layer of the
first cell and the lower second conductive layer of the second
cell.
26. The photovoltaic device of claim 21, wherein the upper second
conductive layer of the first cell and the upper first conductive
layer of the second cell are formed with the same layer as the
first and second light absorption layer, and are separated from
each other.
27. The photovoltaic device of claim 26, further comprising a
non-conductive member formed between the upper second conductive
layer of the first cell and the upper first conductive layer of the
second cell.
28. The photovoltaic device of claim 20, further comprising a first
electrode formed between the substrate, and the lower first
conductive layer of the first cell and the lower second conductive
layer of the second cell.
29. The photovoltaic device of claim 28, further comprising: a
second electrode formed between the upper second conductive layer
of the first cell and the upper first conductive layer of the
second cell, and on a portion therebetween.
30. The photovoltaic device of claim 29, wherein the two
neighboring cells are connected by the first electrode when the
first cell and the second cell connected by the second electrode
are a pair of cells.
31. The photovoltaic device of claim 30, further comprising a
depletion region formed with the same layer as the lower first
conductive layer and the lower second conductive layer and formed
between two neighboring pairs of cells.
32.-41. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a divisional application based on pending
application Ser. No. 12/486,654, filed Jun. 17, 2009, the entire
contents of which is hereby incorporated by reference.
[0002] This application claims priority to and the benefit of
Korean Patent Application No. 10-2008-0104295 filed in the Korean
Intellectual Property Office on Oct. 23, 2008 and Korean Patent
Application No. 10-2008-0110615 filed in the Korean Intellectual
Property Office on Nov. 7, 2008, the entire contents of which are
incorporated herein by reference.
BACKGROUND
[0003] 1. Field
[0004] The present invention relates to a photovoltaic device and a
manufacturing method thereof.
[0005] 2. Description of the Related Art
[0006] A solar cell is one kind of photovoltaic device for
converting light energy into electrical energy, and is used as a
core element for developing solar light. The solar cell is a diode
consisting of a PN junction, and may be classified into various
kinds according to the material used as a light absorption
layer.
[0007] A solar cell using silicon as the light absorption layer may
be classified as a crystalline (monocrystalline and
polycrystalline) solar cell, a substrate solar cell, and a thin
film (crystalline and amorphous) solar cell. Also, a representative
solar cell may be a compound thin film solar cell using CIGS
(CuInGaSe2) or CdTe, a III-V group solar cell, a dye response solar
cell, and an organic solar cell.
[0008] The thin film solar cell is formed by coating a film onto a
substrate based on thin glass or plastic. With the common thin film
solar cell, the diffusion distance of carriers is very short due to
the characteristic of the thin film compared to that of the
crystalline silicon solar cells, and if it is fabricated only with
the PN junction structure, the collection efficiency of
electron-hole pairs generated by the sunlight is significantly
lowered. Therefore, the thin film solar cell has a PIN structure
where an intrinsic semiconductor-based light absorbing layer with
high light absorption is interposed between the P-type and N-type
semiconductors. The common thin film solar cell has a structure
where a front transparent conductive film, a PIN layer, and a rear
reflective electrode layer are sequentially deposited on a
substrate. In this structure, the light absorbing layer is depleted
due to the overlying P and underlying N layers with a high doping
concentration so that an electric field is generated therein. As a
result, among the carriers generated in the light absorbing layer
by sunlight, the electrons are collected at the N layer and the
holes at the P layer by way of drift of the internal electric
field, thereby generating an electric current.
[0009] However, when the PIN layer is formed in the vertical
direction, several laser patternings are executed to the cells when
connecting the electrodes of the P layer and the N layer of
different cells such that layer damage may be generated and a
remaining layer is generated on the side, thereby generating
pattern deterioration. Accordingly the efficiency of the solar cell
may be reduced.
[0010] The above information disclosed in this Background section
is only for enhancement of understanding of the background of the
invention and therefore it may contain information that does not
form the prior art that is already known in this country to a
person of ordinary skill in the art.
SUMMARY
[0011] Accordingly, the present invention improves an interface
characteristic of a solar cell, and increases photovoltaic
efficiency thereof.
[0012] Also, the present invention improves photo-efficiency by
connecting neighboring light absorption layers, suppresses the
generation of a lateral leakage current, and improves durability of
connection electrodes formed on the light absorption layers.
[0013] A photovoltaic device according to an embodiment of the
present invention includes: a substrate; a first conductive layer
formed on the substrate; P layers and N layers alternately formed
according to a first direction on the first conductive layer; and I
layers covering the P layers and the N layers on the first
conductive layer, wherein the P layers and the N layers are
separated from each other by a first interval, the I layers are
formed between the P layers and the N layers that are separated by
the first interval, and the P layers, the I layers, and the N
layers formed according to the first direction form unit cells.
[0014] The first direction may be the same as a direction in which
carriers are moved.
[0015] The first interval may be in the range of 0.3 um to 2
um.
[0016] The unit cells formed according to the first direction may
be electrically connected to each other through the first
conductive layer.
[0017] The unit cells formed according to the first direction may
be separated from each other by a second interval that is wider
than the first interval.
[0018] A depletion layer formed between the unit cells separated by
the second interval may be further included.
[0019] The unit cells formed on the substrate may be arranged into
a plurality of columns according to the first direction, and unit
cells arranged in neighboring columns are separated by a third
interval that is wider than the first interval.
[0020] The P layers and the N layers may include at least one of
amorphous silicon (a-Si), micro-crystalline silicon (mc-Si), and
amorphous silicon carbide (a-SiC).
[0021] The I layers may be made of amorphous silicon (a-Si) or
amorphous silicon germanium (a-SiGe).
[0022] The first conductive layer may be made of a transparent
conductive layer or a reflective layer.
[0023] A second conductive layer formed on the I layers may be
further included.
[0024] A manufacturing method of a photovoltaic device according to
another embodiment of the present invention includes: forming a
conductive layer on a substrate; alternately forming P layers and N
layers according to a first direction on the conductive layer;
patterning the P layers and the N layers to be separated by a first
interval; and forming I layers covering the P layers and the N
layers on the conductive layer and filling between the P layers and
the N layers to separate them.
[0025] The alternately forming of the P layers and the N layers may
be performed using a mask.
[0026] The patterning of the P layers and the N layers may be
performed using laser scribing or wheel scribing.
[0027] The patterning of the P layers and the N layers may be
performed using chemical etching.
[0028] The patterning of the P layers and the N layers may include
selectively etching a conductive layer along with the P layers and
the N layers for the P layers and the N layers to be separated by a
first interval of 0.3 um to 2 um.
[0029] The patterning of the P layers and the N layers may include
forming unit cells separated from each other by a second interval
that is wider than the first interval when defining the P layers
and the N layers that are separated by the first interval as unit
cells.
[0030] The patterning of the P layers and the N layers may include
arranging the unit cells in a plurality of columns according to the
first direction on the substrate, and selectively etching the P
layer, the N layer, and the conductive layer for the unit cells to
be separated by a third interval that is wider than the first
interval.
[0031] The alternately forming of the P layers and the N layers may
further include forming a depletion layer between the unit cells
that are separated from each other when defining the P layers and
the N layers that are separated by the first interval as unit
cells.
[0032] A photovoltaic device according to an embodiment of the
present invention includes: a first cell including a lower first
conductive layer, a first light absorption layer, and an upper
second conductive layer sequentially deposited on a substrate; and
a second cell neighboring the first cell and including a lower
second conductive layer, a second light absorption layer, and an
upper first conductive layer sequentially deposited on the
substrate, wherein the first light absorption layer and the second
light absorption layer are formed at the same layer and are
connected each other.
[0033] The lower first conductive layer of the first cell and the
lower second conductive layer of the second cell may be separated
from each other, and a light absorption layer may be further
included.
[0034] The upper second conductive layer of the first cell and the
upper first conductive layer of the second cell may be formed with
the same layer as the first and second light absorption layers, and
may be electrically disconnected each other.
[0035] A depletion region formed between the upper second
conductive layer of the first cell and the upper first conductive
layer of the second cell may be further included.
[0036] An electrode portion formed between the upper second
conductive layer of the first cell and the upper first conductive
layer of the second cell may be further included.
[0037] The electrode portion may include protrusions and
depressions, and a flat portion, and the width of the flat portion
may be substantially equal to or less than the width between the
lower first conductive layer of the first cell and the lower second
conductive layer of the second cell.
[0038] The upper second conductive layer of the first cell and the
upper first conductive layer of the second cell may be formed with
the same layer as the first and second light absorption layers, and
are separated from each other.
[0039] A non-conductive member formed between the upper second
conductive layer of the first cell and the upper first conductive
layer of the second cell may be further included.
[0040] A first electrode formed between the substrate, and the
lower first conductive layer of the first cell and the lower second
conductive layer of the second cell, may be further included.
[0041] A second electrode formed between the upper second
conductive layer of the first cell and the upper first conductive
layer of the second cell, and on a portion therebetween, may be
further included.
[0042] The two neighboring cells may be connected by the first
electrode when the first cell and the second cell connected by the
second electrode are a pair of cells.
[0043] The lower first conductive layer and the lower second
conductive layer may be maintained between two neighboring pairs of
cells.
[0044] A manufacturing method of a photovoltaic device according to
an embodiment of the present invention includes: forming a lower
first conductive layer and a lower second conductive layer on a
substrate; forming a light absorption layer on the lower first
conductive layer and the lower second conductive layer; forming an
upper first conductive layer and an upper second conductive layer
on the light absorption layer; forming an upper electrode on the
upper first conductive layer and the upper second conductive layer;
and patterning the upper electrode layer, the upper first
conductive layer, the upper second conductive layer, and the light
absorption layer to form a first cell and a second cell forming a
pair of cells connected by the upper electrode layer.
[0045] The method may further include forming a lower electrode on
the substrate before forming the lower first conductive layer and
the lower second conductive layer on the substrate.
[0046] The pair of cells including the first cell and the second
cell may be connected by the lower electrode.
[0047] The lower first conductive layer and the lower second
conductive layer may be maintained between the pair of cells
including the first cell and the second cell.
[0048] The forming of the lower first conductive layer and the
lower second conductive layer on the substrate may include forming
a first semiconductor layer on the substrate, respectively
injecting a first impurity and a second impurity having an opposite
polarity to that of the first impurity to two neighboring regions
of the first semiconductor layer by using a mask, and patterning
the first semiconductor injected with the first impurity and the
second impurity.
[0049] The forming of the lower first conductive layer and the
lower second conductive layer on the substrate may include
selectively forming a semiconductor including the first impurity at
the first region on the substrate and a semiconductor including the
second impurity at the second region on the substrate by using a
mask.
[0050] A depletion region may be formed between the upper first
conductive layer and the upper second conductive layer.
[0051] The method may further include removing a portion of the
region between the upper first conductive layer and the upper
second conductive layer, and forming a non-conductive member before
forming the upper first conductive layer and the upper second
conductive layer on the light absorption layer.
[0052] The forming of the upper first conductive layer and the
upper second conductive layer on the light absorption layer may
include forming a second semiconductor layer on the light
absorption layer, and respectively injecting a first impurity and a
second impurity having an opposite polarity to that of the first
impurity to two neighboring regions of the first semiconductor
layer by using a mask. The forming of the upper first conductive
layer and the upper second conductive layer on the light absorption
layer may include selectively forming a semiconductor including the
first impurity at the first region on the substrate and a
semiconductor including the second impurity at the second region on
the substrate by using a mask.
[0053] According to the present invention, the number of laser
scribes may be reduced, thereby reducing the manufacturing cost of
the solar cell and improving the interface characteristic of the
solar cell, and as a result the efficiency of the photovoltaic
device may be increased.
[0054] Also, light absorption layers between the neighboring cells
are connected thereby improving photo-efficiency, and the light
absorption layers are filled in the separation spaces between the
neighboring cells such that impurity adhesion or chemical
contamination that may be generated during the process is
prevented, thereby suppressing a leakage current of the side
surface thereof. Also, the connection electrode between the cells
is not floated on the light absorption layer, but contacts the
light absorption layer such that mechanical durability of the
connection electrode may be improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0055] FIG. 1 is a top plan view of a photovoltaic device according
to an embodiment of the present invention.
[0056] FIG. 2 is a cross-sectional view taken along the line II-II'
shown in FIG. 1.
[0057] FIG. 3 to FIG. 6 are cross-sectional views showing a
manufacturing method of a photovoltaic device according to an
embodiment of the present invention.
[0058] FIG. 7 is a cross-sectional view o a photovoltaic device
according to another embodiment of the present invention.
[0059] FIG. 8 and FIG. 9 are top plan views showing a structure
forming an electrode in a photovoltaic device according to an
embodiment of the present invention.
[0060] FIG. 10 is a cross-sectional view for explaining a
photovoltaic device for a solar cell according to another
embodiment of the present invention.
[0061] FIG. 11 is a cross-sectional view for explaining a
photovoltaic device for a solar cell according to another
embodiment of the present invention.
[0062] FIG. 12 to FIG. 14 are cross-sectional views showing a
manufacturing method of a photovoltaic device for a solar cell
according to another embodiment of the present invention.
[0063] FIG. 15 and FIG. 16 are cross-sectional views for explaining
a photovoltaic device for a solar cell according to another
embodiment of the present invention.
DETAILED DESCRIPTION
[0064] The present invention will be described more fully
hereinafter with reference to the accompanying drawings, in which
embodiments of the invention are shown. However, the present
invention is not limited to embodiments described herein, and may
be embodied in other forms. Rather, embodiments described herein
are provided to thoroughly and completely understand the disclosed
contents and to sufficiently transfer the ideas of the present
invention to a person of ordinary skill in the art.
[0065] In the drawings, the thicknesses of layers and regions are
exaggerated for clarity.
[0066] It is to be noted that when a layer is referred to as being
"on" another layer or substrate, it can be directly formed on the
other layer or substrate or can be formed on the other layer or
substrate with a third layer interposed therebetween. Like
constituent elements are denoted by like reference numerals
throughout the specification.
[0067] FIG. 1 is a top plan view of a solar cell according to an
embodiment of the present invention. FIG. 2 is a cross-sectional
view taken along the line II-II' shown in FIG. 1.
[0068] Referring to FIG. 1 and FIG. 2, a transparent conductive
layer 110 is formed on a substrate 100. An upper surface of the
transparent conductive layer 110 is textured.
[0069] The texturing means that, for the purpose of increasing a
valid light amount absorbed to the inside of the solar cell by
reducing light amount reflected from the solar cell surface, the
upper surface of the first transparent conductive film 110 is
formed with periodic pyramidal structures, for example within a
size of 10 .mu.m by undergoing an etching process.
[0070] The transparent conductive layer 110 may be made of
SnO.sub.2, ZnO:Al, ZnO:B, indium tin oxide (ITO), or indium zinc
oxide (IZO) in one example.
[0071] P layers 120a including impurities of a P type and N layers
120b including impurities of an N type are alternately formed in a
first direction D on the transparent conductive layer 110. The
first direction D may be defined as a direction that the carriers
are moved, that is, the direction that the electric field generated
for the solar cell by absorbing the light is moved.
[0072] The P layers 120a may be made of one of boron-doped
amorphous silicon (a-Si), amorphous silicon carbide (a-SiC), and
microcrystalline silicon (mc-Si). The N layers 120b may be made of
one of phosphorus-doped amorphous silicon (a-Si), amorphous silicon
carbide (a-SiC), and microcrystalline silicon (mc-Si).
[0073] An I layer 130 covering the P layers 120a and the N layers
120b is formed on the transparent conductive layer 110. The I layer
130 is made of an intrinsic semiconductor, functions as a light
absorption layer, and generates an electric field to form a path
through which the carrier is moved from the P layer 120a to the N
layer 120b.
[0074] Each P layer 120a and N layer 120b are separated from each
other with a first interval W1 therebetween, and the I layer 130 is
formed in the first interval W1. Accordingly, in the solar cell
according to an embodiment of the present invention, a P layer
120a, the I layer 130, and an N layer 120b form a unit cell UC in a
lateral direction. In the unit cell UC, the upper surface and the
side surfaces of the P layer 120a and the N layer 120b are enclosed
by the I layer 130. The I layer 130 is made of amorphous silicon,
thereby protecting the surfaces of the P layer 120a and the N layer
120b, functions as an insulator thereby preventing a leakage
current, and improves the interface characteristic, thereby
improving the efficiency of the solar cell.
[0075] In one example, the first interval W1 is in the range of 0.3
um to 2 um. When the I layer 130 is formed of the amorphous
silicon, if the first interval W1 is less than 0.3 um, the light
conversion efficiency may be reduced by electron-hole
recombination. When the I layer 130 is formed of the amorphous
silicon, it is preferable that the first interval W1 is less than 2
um. However, when the degree of crystallization of the I layer 130
is improved to the degree of monocrystallinity, it is possible for
the first interval W1 to be more than 2 um.
[0076] The unit cell UC is formed along the first direction D, the
transparent conductive layer 110 is not formed between the P layer
120a and the N layer 120b in the unit cell UC, and the I layer 130
is filled therein.
[0077] The unit cells UC formed according to the first direction D
are electrically connected to each other through the transparent
conductive layer 110. In detail, the neighboring unit cells UC
according to the first direction D have a second interval W2
therebetween. In the portion connecting the neighboring unit cells
UC, the transparent conductive layer 110 formed under the P layer
120a and the N layer 120b is not disconnected. The second interval
W2 may be relatively wider than the first interval W1. In the
connection portion of the unit cells UC that are connected through
the transparent conductive layer 110, the interval W2 between the P
layer 120a and the N layer 120b is relatively wider than the
interval W1 between the P layer 120a and the N layer 120b in each
unit cell UC such that the P layer 120a and the N layer 120b form a
PIN diode through the I layer 130. In another embodiment, the P
layer 120a and the N layer 120b overlap each other and are doped on
the portion connecting the neighboring unit cells UC, thereby being
formed as a depletion layer. The depletion layer represents a
non-conductive layer.
[0078] In one example, the second interval W2 is in the range of 10
um to 100 um.
[0079] The unit cells UC formed on the substrate 100 are disposed
in a plurality of columns along the first direction D. The unit
cells UC respectively formed in neighboring columns are separated
from each other by a third interval W3. The third interval W3 is
larger than the interval W1 between the P layer 120a and the N
layer 120b in the unit cell UC so as to not generate an interaction
between the neighboring unit cells UC disposed in a direction
intersecting the first direction D.
[0080] In one example, the third interval W3 may be in the range of
10 um to 100 um.
[0081] A rear conductive layer 140 is formed on the I layer 130.
The rear conductive layer 140 may be made of indium tin oxide (ITO)
or indium zinc oxide (IZO) in one example. The surface of the rear
conductive layer 140 is textured. The rear conductive layer 140
functions to increase the light absorption rate by increasing a
path through which the light is absorbed.
[0082] A reflective layer 150 is formed on the rear conductive
layer 140. In an embodiment of the present invention, the rear
conductive layer 140 and the reflective layer 150 function as an
electrode in the solar cell of the vertical type. However, the
current flows in the sequence of the transparent conductive layer
110, the P layer 120a, the I layer 130, the N layer 120b, and the
transparent conductive layer 110 in the horizontal direction such
that the reflective layer 150 does not function as the electrode in
an embodiment of the present invention, but functions to reflect
the incident light through the substrate 100.
[0083] FIG. 3 to FIG. 6 are cross-sectional views showing a
manufacturing method of a solar cell according to an embodiment of
the present invention.
[0084] Referring to FIG. 3, a transparent conductive layer 110 is
deposited on a substrate 100. The transparent conductive layer 110
may be made of SnO.sub.2, ZnO:Al, ZnO:B, indium tin oxide (ITO), or
indium zinc oxide (IZO). The upper surface of the transparent
conductive layer 110 is etched to texture the upper surface. P
layers 120a and N layers 120b are alternately formed according to a
first direction D on the transparent conductive layer 110. Next,
various methods of alternately forming the P layer 120a and the N
layer 120b will be described in detail.
[0085] First, to alternately form the P layer 120a and the N layer
120b, first regions and second regions that are alternately
disposed according to the first direction D are defined on the
transparent conductive layer 110. Next, the P layers 120a are
deposited in the first regions after covering the second regions by
using a mask. In one example, the P layers 120a may be deposited
through plasma enhanced chemical vapor deposition (PECVD). Next,
the N layers 120b are deposited in the second regions after
covering the first regions by using a mask. The N layers 120b may
also be deposited through plasma enhanced chemical vapor deposition
(PECVD).
[0086] In another method, an amorphous silicon layer is firstly
formed on the transparent conductive layer 110, and P-type ions are
injected on the whole surface of the amorphous silicon layer. Next,
a portion where the P layers 120a will be formed is covered and a
portion where the N layers 120b will be formed is exposed by using
a mask, and an N-type impurity is injected with a high
concentration and thereby the P layers 120a and the N layers 120b
are alternately formed.
[0087] In another method, an amorphous silicon layer is first
formed on the transparent conductive layer 110, a portion where the
N layers 120b will be formed is covered and a portion where the P
layers 120a will be formed is exposed by using a mask, and the
P-type impurity is injected to form the P layers 120a. Next, the
portion where the P layers 120a will be formed is covered and the
portion where the N layers 120b will be formed is exposed by using
a mask, and the N-type impurity is injected to form the N layers
120b.
[0088] In another method, an amorphous silicon layer doped with the
P-type impurity is deposited on the transparent conductive layer
110 through plasma enhanced chemical vapor deposition (PECVD).
Next, a mask is disposed on the amorphous silicon layer doped with
the P-type impurity to cover the portion where the P layers 120a
will be formed, and N-type ions are injected to form the N layers
120b. The layer of the P type is changed to the I layer according
to the injection of the N-type ions, and is then changed to the
N-type layer. Accordingly, the P layers 120a and the N layers 120b
may be alternately formed according to the first direction D.
[0089] FIG. 4 is a cross-sectional view explaining a method for
alternately forming the P layers 120a and the N layers 120b
according to another embodiment.
[0090] Referring to FIG. 1 and FIG. 4, depletion layers d between
the unit cells UC are formed with the second interval W2. When
forming the P layers 120a and the N layers 120b by using the plasma
enhanced chemical vapor deposition (PECVD) or the ion injection
method, the P layers 120a and the N layers 120b may be formed to
overlap each other in the portion where the unit cells UC1 and the
unit cells UC2 are connected to each other. If the portion where
the unit cells UC are connected is formed as an electrically
non-conductive depletion layer, it is not necessary for the portion
connecting the unit cells UC to be subsequently removed by using
laser scribing.
[0091] Next, as shown in FIG. 5, the P layers 120a and the N layers
120b are patterned to separate the P layers 120a and N layers 120b
neighboring each other by a predetermined interval. Patterning the
P layers 120a and the N layers 120b is a process of connecting the
electrodes while forming the unit cells UC. In one example, the
region where the P layer 120a and the N layer 120b neighbor each
other may be patterned by laser scribing, wheel scribing, or
chemical etching.
[0092] In the unit cell UC, the P layer 120a and the N layer 120b
are patterned to have the interval W1. The first interval W1 is
formed to be in the range of 0.3 um to 2 um. The unit cells UC
formed according to the first direction D are patterned for the
interval therebetween to be the second interval W2. The second
interval W2 may be wider than the first interval W1. The second
interval W2 may be in the range of 10 um to 100 um.
[0093] The transparent conductive layer 110 may be selectively
patterned at the same time as the P layer 120a and the N layer
120b. In detail, as shown in FIG. 5, in the case of the portion
where the unit cell UC1 and the unit cell UC2 are connected, the
transparent conductive layer 110 is left as it is, and the regions
neighboring the P layer 120a and the N layer 120b in each unit cell
UC are selectively patterned. Accordingly, the unit cells UC1 and
UC2 are electrically connected to each other through the
transparent conductive layer 110. In the regions consisting of the
unit cells UC1 and UC2, the transparent conductive layer 110 is
simultaneously patterned along with the P layer 120a and the N
layer 120b. When using laser scribing, the wavelength and the
output of the laser are controlled for etching, and an appropriate
etchant is selected when using the chemical etching process, so it
is thereby possible to execute the above-explained patterning.
[0094] The unit cells UC formed on the substrate 100 are disposed
along the first direction D with the plurality of columns. The unit
cells UC are patterned to have the third interval W3 between the
unit cells UC formed in neighboring columns. The third interval W3
is relatively wider than the first interval W1 so as to not
generate an interaction between neighboring unit cells UC. The
third interval W3 may be in the range of 10 um to 100 um.
[0095] Referring to FIG. 6, an I layer 130 covering the P layer
120a and the N layer 120b is deposited on the transparent
conductive layer 110. The I layer 130 may be made of amorphous
silicon. The I layer 130 may be formed through plasma enhanced
chemical vapor deposition (PECVD).
[0096] The deposited I layer 130 functions as a light absorption
layer, and the P layer 120a, the I layer 130, and the N layer 120b
are connected to form a diode according to the side direction.
[0097] A rear conductive layer 140 is formed on the I layer 130.
The upper surface of the rear conductive layer 140 may be etched,
thereby forming a texture. The rear conductive layer 140 increases
a path through which the light is absorbed, thereby increasing the
light absorption rate.
[0098] A reflective layer 150 is deposited on the rear conductive
layer 140 as shown in FIG. 2, thereby forming the solar cell shown
in FIG. 1.
[0099] FIG. 7 is a cross-sectional view showing a solar cell
according to another embodiment of the present invention.
[0100] A solar cell of a substrate structure will now be explained.
Light is incident through the substrate in the solar cell of the
superstrate structure, however the light is incident on the side
opposite to the substrate in the solar cell of the substrate
structure. Hereafter, referring to FIG. 7, the solar cell of the
substrate structure according to the current embodiment of the
present invention will be described.
[0101] The solar cell of the substrate structure according to an
embodiment of the present invention has the same planar shape as
the solar cell of the superstrate according to an embodiment of the
present invention, and FIG. 1 is again referred to. However, the
reference numerals 100 of the substrate and 130 of the I layer of
FIG. 1 are replaced with the reference numerals 200 for the
substrate and the 230 for the I layer in the solar cell of the
superstrate structure according to the current embodiment of the
present invention.
[0102] Referring to FIG. 1 and FIG. 7, a reflecting electrode layer
210 is formed on a substrate 200. P layers 220a including
impurities of a P type and N layers 220b including impurities of an
N type are alternately formed along a first direction D on the
reflecting electrode layer 210. The first direction D may be
defined as a direction in which the carriers are moved, that is,
the direction that the electric field generated for the solar cell
by absorbing the light is moved.
[0103] An I layer 230 covering the P layers 220a and the N layers
220b are formed on the reflecting electrode layer 210. The I layer
230 is made of an intrinsic semiconductor, and is a path through
which the carriers are moved from the P layer 220a to the N layer
220b by generating the electric field to the light absorption
layer.
[0104] In the solar cell according to an embodiment of the present
invention, the reflecting electrode layer 210 is used as the
electrode of the N layer 220b in the P layer 220a, and
simultaneously functions as the reflective layer. The reflecting
electrode layer 210 may be made of a metal material.
[0105] The P layers 220a including impurities of a P type and the N
layers 220b including impurities of an N type are alternately
formed along the first direction D on the reflecting electrode
layer 210. The first direction D may be defined as a direction that
the carriers are moved, that is, the direction that the electric
field generated for the solar cell by absorbing the light is
moved.
[0106] An I layer 230, covering the P layers 220a and the N layers
220b, is formed on the reflecting electrode layer 210. The I layer
230 is made of an intrinsic semiconductor, and is a path through
which the carriers are moved from the P layer 220a to the N layer
220b by generating the electric field to the light absorption
layer.
[0107] Each P layer 220a and N layer 220b are separated by the
first interval W1 therebetween, and the I layer 230 is formed in
the first interval W1. Accordingly, in the solar cell of the
substrate structure according to an embodiment of the present
invention, the P layer 220a, the I layer 230, and the N layer 220b
form unit cells UC along the side, like the solar cell of the
superstrate structure.
[0108] In the unit cells UC, the upper surface and the side
surfaces of the P layer 220a and the N layer 220b are enclosed by
the I layer 230. The I layer 230 is made of an amorphous layer such
that it functions as a surface passivation layer of the P layer
220a and the N layer 220b, prevents a leakage current, and improves
the interface characteristic, thereby improving the efficiency of
the solar cell.
[0109] The unit cells UC are formed along the first direction D,
the reflecting electrode layer 210 is not formed between the P
layer 220a and the N layer 220b in the unit cell UC, and the I
layer 230 is filled therein.
[0110] The unit cells UC formed according to the first direction D
are electrically connected to each other through the reflecting
electrode layer 210. In detail, the unit cells UC neighboring each
other along the first direction D are separated by the second
interval W2. In the portion connecting the neighboring unit cells
UC, the reflecting electrode layer 210 formed under the P layer
220a and the N layer 220b is not disconnected. The second interval
W2 may be wider than the first interval W1. Accordingly, in the
connection portion of the unit cells UC that are connected by the
reflecting electrode layer 210, the interval W2 between the P layer
220a and the N layer 220b is wider than the interval W1 between the
P layer 220a and the N layer 220b in each unit cell UC such that
the P layer 220a and the N layer 220b form a PIN diode through the
I layer 230.
[0111] The unit cells UC formed on the substrate 200 are disposed
in a plurality of columns according to the first direction D. The
unit cells UC respectively formed in neighboring columns are
separated from each other by a third interval W3. The third
interval W3 is larger than the interval W1 between the P layer 220a
and the N layer 220b in the unit cell UC so as to not generate an
interaction between the neighboring unit cells UC along the
direction intersecting the first direction D.
[0112] A reflection prevention layer 250 is formed on the I layer
230. In the solar cell of the superstrate structure, the light is
incident on the opposite side of the substrate 200, and the
reflection prevention layer 250 protects the I layer 230 and does
not reflect the incident light toward the I layer 230, and thus the
reflection prevention layer 250 has the function of increasing the
light absorption rate. In the solar cell of the superstrate
structure according to an embodiment of the present invention, it
is not necessary to additionally form the connection electrode on
the reflection prevention layer 250 such that the problem that the
area receiving the light is decreased by the connection electrode
is solved, thereby increasing the light absorption rate.
[0113] FIG. 8 and FIG. 9 are top plan views showing a structure
forming an electrode in a photovoltaic device according to an
embodiment of the present invention.
[0114] Referring to FIG. 8 and FIG. 9, the unit cells UC are
basically connected in series with a zigzag shape. If all cells are
connected in series under a module formation, an efficiency
deterioration may occur when generating dead cells or deteriorated
cells, and the solar cell may not operate in a serious case.
[0115] Accordingly, in the solar cell according to an embodiment of
the present invention, connectors 300 and 400 connected to the edge
of the transparent conductive layer are connected in parallel to
several regions under the modulation process such that a short
caused by dead cells and deteriorated cells, and consequent
efficiency deterioration, may be prevented.
[0116] Also, the output voltage/current may be controlled according
to the method of forming the connectors 300 and 400.
[0117] According to embodiments of the present invention, it is
possible for the electrode and the unit cell to be formed through
one patterning process such that interface defects and pattern
deteriorations generated through the patterning process may be
solved.
[0118] FIG. 10 is a cross-sectional view for explaining a
photovoltaic device for a solar cell according to another
embodiment of the present invention.
[0119] Referring to FIG. 10, a front electrode 520 is formed on a
substrate 510. The substrate 510 is a hard substrate or a flexible
substrate. For example, when the substrate is a hard substrate, it
may include a glass plate, a quartz plate, a silicon plate, a
plastic plate, or a metal plate. In another embodiment, when the
substrate is a flexible substrate, it may include a metal sheet or
a plastic sheet. As an example, the metal sheet may be a stainless
sheet or aluminum foil.
[0120] The incident solar light is transmitted through the front
electrode 520, which is made of a transparent conductive material
having conductivity. Generally, the front electrode is made of a
material that minimizes the deterioration of light transmittance
and that has low resistivity and good surface roughness, such as a
transparent conductive oxide (TCO) like ZnO:Al, ZnO:B, SnO2, and
ITO. To increase the efficiency of the incident light, texture of a
predetermined height and size may be formed on the surface of the
front electrode 520, for example by etching.
[0121] A lower first conductive layer 531 and a lower second
conductive layer 532 having an opposite polarity to that of the
lower first conductive layer 531 and that neighbor each other are
formed on the front electrode 520. The lower first conductive layer
531 and the lower second conductive layer 532 are separated from
each other through a patterning process. A contact hole 534
exposing the substrate 510 by passing through the front electrode
520 is formed between the lower first conductive layer 531 and the
lower second conductive layer 532.
[0122] A light absorption layer 540 made of an intrinsic
semiconductor material is formed on the lower first conductive
layer 531 and the lower second conductive layer 532. Here, the
light absorption layer 540 is connected with the substrate 510
through the contact hole 534, and separates the lower first
conductive layer 531 and the lower second conductive layer 532 from
each other.
[0123] An upper second conductive layer 536 and an upper first
conductive layer 537 respectively corresponding to the lower first
conductive layer 531 and the lower second conductive layer 532 are
formed at the same layer on the light absorption layer 540 to
neighbor each other. A region where the upper second conductive
layer 536 and the upper first conductive layer 537 neighbor each
other becomes a depletion region 535 by combining the electrons and
holes of the impurities that have the different polarities and are
injected to the upper second conductive layer 536 and the upper
first conductive layer 537, and is non-conductive. It is possible
for the depletion region 535 to be replaced with an insulating
member made of an organic material.
[0124] A rear electrode 550 is formed on the upper second
conductive layer 536, the depletion region 535, and the upper first
conductive layer 537. The rear electrode 550 includes protrusions
and depressions 552 and a flat portion 551, and the width of the
flat portion 551 corresponds to the width of the contact holes 534
such that it is substantially equal to or less than the width of
the contact holes 534. The rear electrode 550 is generally made of
a material such as silver (Ag), and a reflective layer (not shown)
may be included between the upper second conductive layer 536, the
depletion region 535, and the upper first conductive layer 537, and
the rear electrode 550.
[0125] When a first cell 571 and a second cell 572 connected
through the rear electrode 550 are referred to as a pair of cells,
two neighboring pairs of cells are connected by the front electrode
520.
[0126] In this way, the first cell 571 made of the lower first
conductive layer 531, the light absorption layer 540, and the upper
second conductive layer 536, and the second cell 572 made of the
lower second conductive layer 532, the light absorption layer 540,
and the upper first conductive layer 537, are formed with the same
layer such that a cell having the same effect as the vertical
deposition structure such as in tandem or triplet may be formed by
being horizontally deposited. Particularly, the light absorption
layer 540 is formed in the contact hole 534 between the lower first
conductive layer 531 and the lower second conductive layer 532, and
is connected on the boundary of the first cell 571 and the second
cell 572 such that leakage current of the cell side generated by
the adhesion of an impurity or chemical contamination may be
reduced. Also, the light absorption layer formed on the boundary
between two neighboring cells functions as a supplying source of
the carriers such that the lifetime of the minority carrier of the
cell increases, thereby improving the light efficiency.
[0127] Also, the connection electrode between the neighboring cells
is disposed on the depletion region 535 formed between the upper
second conductive layer 536 of the first cell 571, and the upper
first conductive layer 537 of the second cell 572 is not floated
but is contacted with the lower layer, such that the mechanical
durability may be improved.
[0128] FIG. 11 is a cross-sectional view for explaining a
photovoltaic device for a solar cell according to another
embodiment of the present invention.
[0129] Referring to FIG. 11, a rear electrode 620 is formed on a
substrate 610.
[0130] The surface of the substrate 610 may include protrusions and
depressions to increase the reflection efficiency of solar
light.
[0131] The rear electrode 620 is made of a metal having high
reflectance, such as Mo.
[0132] A lower first conductive layer 631 and a lower second
conductive layer 632 having an opposite polarity to that of the
lower first conductive layer 631 and that neighbor each other are
formed on the rear electrode 620. The lower first conductive layer
631 and the lower second conductive layer 632 are separated from
each other through a patterning process. A contact hole 634
exposing the substrate 610 by passing through the rear electrode
620 is formed between the lower first conductive layer 631 and the
lower second conductive layer 632.
[0133] A light absorption layer 640 made of an intrinsic
semiconductor material is formed on the lower first conductive
layer 631 and the lower second conductive layer 632. Here, the
light absorption layer 640 is connected with the substrate 610
through the contact hole 634, and separates the lower first
conductive layer 631 and the lower second conductive layer 632 from
each other.
[0134] An upper second conductive layer 636 and an upper first
conductive layer 637 respectively corresponding to the lower first
conductive layer 631 and the lower second conductive layer 632 are
formed with the same layer on the light absorption layer 640 to
neighbor each other. The region where the upper second conductive
layer 636 and the upper first conductive layer 637 neighbor each
other becomes a depletion region 635 by combining the electrons and
holes of impurities that have different polarities and are injected
into the upper second conductive layer 636 and the upper first
conductive layer 637, and is non-conductive. It is possible for the
depletion region 635 to be replaced by an insulating member made of
an organic material.
[0135] A front electrode 650 is formed on the upper second
conductive layer 636, the depletion region 635, and the upper first
conductive layer 637. A reflection prevention layer (not shown) may
be included between the upper second conductive layer 636, the
depletion region 635, and the upper first conductive layer 637, and
the front electrode 650. The reflection prevention layer may be
made of at least one material of silicon nitride, titanium oxide,
and MgF2.
[0136] When a first cell 671 and a second cell 672 connected
through the rear electrode 650 are referred to as a pair of cells,
two neighboring pairs of cells are connected by the rear electrode
620.
[0137] FIGS. 12 to 14 are cross-sectional views showing a
manufacturing method of a photovoltaic device for a solar cell
according to another embodiment of the present invention.
[0138] FIG. 12 is a cross-sectional view showing a step of forming
a front electrode 720 on a substrate 710.
[0139] Referring to FIG. 12, a front electrode layer 721 is formed
on the substrate 710. As an example, the front electrode layer 721
is formed through physical vapor deposition. The front electrode
layer 721 is made of a material that is transparent and has
conductivity, such as ZnO:Al, ZnO:B, SnO2, and indium tin oxide
(ITO). To increase the efficiency of incident light, it is
preferable that the surface thereof is textured to a predetermined
height and size. For example, the texture may include an embossing
pattern, protrusions and depressions, protrusions, recesses,
grooves, or a prism pattern.
[0140] The front electrode layer 721 is patterned to form the front
electrode 720. The patterning method may use laser scribing.
[0141] FIG. 13 is a cross-sectional view showing a step of forming
a lower first conductive layer 731 and a lower second conductive
layer 732 on the front electrode 720 formed by patterning the front
electrode layer 721 shown in FIG. 12.
[0142] Referring to FIG. 13, the lower first conductive layer 731
and the lower second conductive layer 732 are formed to neighbor
each other on the front electrode 720. Here, chemical vapor
deposition may be used. A predetermined region is exposed by using
a hard mask (not shown), and a thin film is deposited by using a
deposition gas including a first impurity to thereby selectively
form the lower first conductive layer 731 on the predetermined
region. Next, a region adjacent to the lower first conductive layer
731 is exposed by using a hard mask, and a thin film is deposited
by using a deposition gas including a second impurity having the
opposite polarity to that of the first impurity, thereby
selectively forming the lower second conductive layer 732 on the
region adjacent to the lower first conductive layer 731. A region
733 that is not doped with an impurity may be present between the
lower first conductive layer 731 and the lower second conductive
layer 732.
[0143] As another method of forming the lower first conductive
layer 731 and the lower second conductive layer 732, an intrinsic
semiconductor layer that does not include an impurity is formed on
the front electrode 720, and impurities having different polarities
are injected to the neighboring regions by using a hard mask.
[0144] As another method of forming the intrinsic semiconductor
layer that does not include the impurity on the front electrode
720, a laser is irradiated to the semiconductor layer under a gas
atmosphere including an impurity such as PH3 or B2H6 such that the
impurity in the gas atmosphere is reacted, thereby forming the
lower first conductive layer 731 and the lower second conductive
layer 732.
[0145] After forming the lower first conductive layer 731 and the
lower second conductive layer 732, the boundary portion of the
lower first conductive layer 731 and the lower second conductive
layer 732, and the lower front electrode 720, are removed by using
laser scribing such that a plurality of contact holes 734 exposing
a portion of the substrate 710 are formed. The contact holes 734
may be formed in a ditch shape extending in one direction under the
plane surface. Here, the boundary portions of the lower first
conductive layer 731 and the lower second conductive layer 732 are
removed while skipping one to form the conductive layer with the
same polarity on the right side and the left side with respect to
the contact holes 734.
[0146] FIG. 14 is a cross-sectional view showing formation of a
light absorption layer 740, an upper second conductive layer 736,
and an upper first conductive layer 737, as well as a rear
electrode 750.
[0147] Referring to FIG. 14, the light absorption layer 740 is
formed on the substrate 710 formed with the front electrode 720,
the lower first conductive layer 731, and the lower second
conductive layer 732, and in the contact holes 734, through
chemical vapor deposition. Next, the upper second conductive layer
736 and the upper first conductive layer 737 are formed on the
light absorption layer 740. Here, the upper second conductive layer
736 and the upper first conductive layer 737 having opposite
polarities are disposed at positions corresponding in the vertical
direction to the lower first conductive layer 731 and the lower
second conductive layer 732, respectively. The method of forming
the upper conductive layers may be the same as the method of
forming the lower conductive layers thereunder. Here, a depletion
region 735 may be formed between the upper second conductive layer
736 and the upper first conductive layer 737. In the depletion
region 735, impurities having the different polarities are injected
such that combinations of electron-hole pairs are formed, and the
charge carriers are depleted in this region such that this region
become a region that is electrically disconnected. When the upper
second conductive layer 736 and the upper first conductive layer
737 are formed through the impurity injection using a hard mask,
the upper second conductive layer 736 and the upper first
conductive layer 737 are formed to be separated from each other
such that the intrinsic semiconductor region may be formed between
the upper second conductive layer 736 and the upper first
conductive layer 737 to thereby obtain the same effects. Also, the
depletion region 735 may be eliminated, or may be replaced by an
insulating member of an inorganic layer or organic layer.
[0148] A rear electrode 750 is formed on the substrate formed with
the light absorption layer 740, the upper second conductive layer
736, the upper first conductive layer 737, and the depletion region
735. The material for the rear electrode 750 may be one of Ag, Mo,
and Al.
[0149] Next, the rear electrode 750, the upper second conductive
layer 736, the upper first conductive layer 737, the light
absorption layer 740, the lower first conductive layer 731, and the
lower second conductive layer 732 are patterned through laser
scribing or photolithography such that a first cell 771 and a
second cell 772 are connected by the rear electrode 750 thereby
forming a pair, and a structure in which pairs of a first cell 771
and a second cell 772 are only connected by the front electrode 720
is formed.
[0150] Accordingly, the first cell including the lower first
conductive layer, the light absorption layer, and the upper second
conductive layer, and the second cell including the lower second
conductive layer, the light absorption layer, and the upper first
conductive layer are formed with the same layer to neighbor each
other such that a cell having the same effect as the vertical
deposition structure such as tandem or triplet may be formed by
being horizontally deposited. Particularly, the light absorption
layer is formed in the contact hole between the lower first
conductive layer and the lower second conductive layer, and is
connected on the boundary of the first cell and the second cell
such that leakage current of the cell side generated by adhesion of
an impurity or chemical contamination may be reduced. Also, the
light absorption layer formed on the boundary between two
neighboring cells functions as a supplying source of the carrier
such that the lifetime of the minority carrier of the cell
increases, thereby improving the light efficiency.
[0151] FIG. 15 and FIG. 16 are cross-sectional views for explaining
a photovoltaic device for a solar cell according to another
embodiment of the present invention.
[0152] In an embodiment of FIG. 15, compared with the embodiment of
FIG. 10, a depletion region formed between the lower first
conductive layer 531 and the lower second conductive layer 532 is
not removed, but is maintained, as well as the front electrode 520
between the cells in which the first cell 571 and the second cell
572 are connected to each other by the rear electrode 550. Thus,
the portion that will be removed through the laser scribing is
decreased such that thermal damage due to the laser irradiation may
be reduced.
[0153] In an embodiment of FIG. 16, compared with the embodiment of
FIG. 11, a depletion region formed between the lower first
conductive layer 631 and the lower second conductive layer 632 is
not removed, but is maintained, as well as the rear electrode 620
between the cells in which the first cell 671 and the second cell
672 are connected to each other by the front electrode 650. Thus,
the portion that will be removed through the laser scribing is
decreased such that thermal damage due to the laser irradiation may
be reduced.
[0154] While this invention has been described in connection with
what is presently considered to be practical embodiments, it is to
be understood that the invention is not limited to the disclosed
embodiments, but, on the contrary, is intended to cover various
modifications and equivalent arrangements included within the
spirit and scope of the appended claims.
* * * * *