KR101444957B1

KR101444957B1 - Solar cell

Info

Publication number: KR101444957B1
Application number: KR1020080122924A
Authority: KR
Inventors: 장재원; 최영호; 김형석
Original assignee: 엘지전자 주식회사
Priority date: 2008-12-05
Filing date: 2008-12-05
Publication date: 2014-09-29
Also published as: KR20100064478A

Abstract

A solar cell includes a semiconductor part forming a pn junction, an electrode formed on the semiconductor part and connected to a bus bar, and an electrode for transferring a carrier formed in the semiconductor part to the bus, Wherein the electrode has a cross sectional area of a first portion located at a first distance from the bus bar and a cross sectional area of a second portion located at a second distance that is different from the first distance. Accordingly, the cross-sectional area of the electrode is changed according to the distance between the bus bars, thereby improving the collecting ability and the transporting ability of the carrier through the electrode, thereby improving the operation efficiency of the solar cell.

Solar cell, rear junction, electrode, cross-sectional area

Description

Solar cell {SOLAR CELL}

The present invention relates to a solar cell

With the recent depletion of existing energy resources such as oil and coal, interest in alternative energy to replace them is increasing. Among them, solar cells generate electric energy from solar energy, and they are environmentally friendly and have an advantage of long life as well as infinite solar energy.

Solar cells are divided into silicon solar cell, compound semiconductor solar cell and tandem solar cell according to the raw material, and silicon solar cell is mainstream.

The silicon solar cell includes a semiconductor substrate and a semiconductor emitter layer made of semiconductors having different conductive types such as p-type and n-type, a conductive transparent electrode layer formed on the semiconductor emitter layer, A front electrode formed on the conductive transparent electrode layer, and a rear electrode formed on the semiconductor substrate. Therefore, a p-n junction is formed at the interface between the semiconductor substrate and the semiconductor emitter layer.

When sunlight enters the solar cell having such a structure, electrons and holes are generated in a silicon semiconductor doped with an n-type or p-type impurity by a photovoltaic effect. For example, electrons are generated in a majority carrier in an n-type semiconductor emitter layer made of an n-type silicon semiconductor, and holes are generated in a majority carrier in a p-type semiconductor substrate made of a p-type silicon semiconductor. Electrons and holes generated by the photovoltaic effect are attracted toward the n-type semiconductor emitter layer and the p-type semiconductor substrate, respectively, and are transferred to the front electrode and the rear electrode, and current flows through the electrodes. At this time, the conductive transparent electrode layer prevents reflection of incident sunlight and improves the conductivity of the carrier so that generated electrons can easily move to the front electrode.

SUMMARY OF THE INVENTION The present invention is directed to improving the operation efficiency of a solar cell.

A solar cell according to one aspect of the present invention includes a semiconductor portion forming a pn junction and an electrode formed on the semiconductor portion and connected to the bus bar and transferring a carrier formed in the semiconductor portion to the bus, Sectional area of the first part located at the first distance from the bus bar and the sectional area of the second part located at the second distance far from the first distance are different from each other

And the cross-sectional area of the first portion is larger than the cross-sectional area of the second portion.

The cross-sectional area of the electrode may vary in magnitude in proportion to the distance from the bus bar.

It is preferable that the cross-sectional area of the electrode increases in size as it approaches the bus bar.

The cross-sectional area may vary depending on at least one of a width and a height of the electrode.

The carrier may be one of an electron and a hole.

The electrode includes a first electrode for transferring electrons and a second electrode for transferring holes. The bus bar includes a first bus connected to the first electrode, a second bus bar connected to the second electrode, Wherein the first electrode has a first cross-sectional area that varies in size along a distance from the first bus bar and the second electrode has a second cross-sectional area that varies in size along a distance from the second bus bar .

It is preferable that the first and second cross sectional areas increase in size as they approach the first and second bus bars, respectively.

The first cross-sectional area of the first electrode located at the same distance from the first bus bar and the second cross-sectional area of the second electrode may be different from each other.

The size of the cross-sectional area of the first electrode located at the first distance from the first bus bar may be smaller than the size of the cross-sectional area of the second electrode located at the first distance from the second bus bar.

At least one of the width and the height of the first and second electrodes may vary according to the distance from the first and second bus bars.

The first and second electrodes may be formed on the same side of the semiconductor portion.

A solar cell according to another aspect of the present invention includes a first doping portion of a first conductivity type formed on a semiconductor substrate of a first conductivity type, a second doping portion of another conductivity type of another of the first conductivity type, A first electrode formed on the doping portion, a second electrode formed on the second doping portion, a first bus bar receiving a carrier from the first electrode, and a second bus bar receiving a carrier from the second electrode And the cross-sectional area of the first electrode portion located on the same line and the cross-sectional area of the second electrode portion are different from each other.

According to this aspect of the present invention, the cross-sectional area of the electrode is changed according to the distance between the bus bar and the electrode, thereby improving the collecting ability and the transporting ability of the carrier through the electrode, thereby improving the operation efficiency of the solar cell.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. Like parts are designated with like reference numerals throughout the specification. When a layer, film, region, plate, or the like is referred to as being "on" another portion, it includes not only the case directly above another portion but also the case where there is another portion in between. Conversely, when a part is "directly over" another part, it means that there is no other part in the middle. Also, when a part is formed as "whole" on the other part, it means not only that it is formed on the entire surface (or the front surface) of the other part but also not on the edge part.

An example of a solar cell according to an embodiment of the present invention will now be described with reference to FIGS. 1 and 2. FIG.

FIG. 1 is a plan view of a rear surface of an example of a solar cell according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the solar cell of FIG. 1 along a line II-II.

1 and 2, a solar cell 10 according to an embodiment of the present invention includes a semiconductor substrate 110 of a first conductive type, a front protective film 120 formed on one surface of a semiconductor substrate 110, An antireflection film 130 formed on the front protective film 120 and a plurality of first doping portions 141 formed on the other surface of the semiconductor substrate 110 and highly doped with impurities of the first conductivity type, A plurality of second doping portions 142 which are formed adjacent to the first portion 141 and are highly doped with impurities of the second conductivity type of the first conductivity type and the second conductivity type, A plurality of electron-emitting electrodes (hereinafter referred to as "first electrodes") 161 formed on a part of the first doping section 141, a second doping layer 150 formed on a part of the doping section 142, (Hereinafter referred to as "second electrode") 162 formed on a part of the first electrode 142, a plurality of first electrodes 161 connected to the plurality of first electrodes 161 That includes a first bus bar 171, and the second bus bar 172 is connected is connected to a plurality of second electrodes 162. The

The upper surface of the semiconductor substrate 110 has a texturing surface having a plurality of irregularities 101 and the semiconductor substrate 110 is made of a first conductive type, for example, n-type single crystal silicon . Alternatively, the semiconductor substrate 110 may have a p-type conductivity type and may be made of polycrystalline silicon. In addition, the semiconductor substrate 110 may be formed of a semiconductor material other than silicon. When the semiconductor substrate 110 has a p-type conductivity type, the semiconductor substrate 110 may contain impurities of pentavalent elements such as phosphorus (P), arsenic (As), antimony (Sb)

As the upper surface of the semiconductor substrate 110 is textured to have a plurality of projections and depressions 101, the light reflectance of the upper surface of the semiconductor substrate 110 is reduced to about 11% And the reflecting operation is performed to trap the light inside the solar cell. As a result, the absorption rate of light is increased, so that the efficiency of the solar cell is improved.

The structure of the unevenness 101 formed may have a random pyramid structure, and the height of the unevenness 101 formed at this time may be about 1 탆 to 10 탆.

A front protective film 120 is formed on a front surface of a semiconductor substrate 110 having a plurality of protrusions and recesses 101 formed thereon.

The front protective film 120 is a film doped with an n-type impurity at a concentration higher than that of the semiconductor substrate 110 such as phosphorus (P), arsenic (As), antimony (Sb) (front surface field) similar to the back surface field of the semiconductor substrate 110, electrons and holes separated by the incident light are prevented from recombining at the upper surface of the semiconductor substrate 110 and disappearing.

An antireflection film 130 made of a silicon nitride film (SiNx) or a silicon oxide film (SiO ₂ ) is formed on the front surface of the front protective film 120.

The antireflection film 130 formed on the front protective film 120 reduces the reflectance of incident sunlight and increases the selectivity of a specific wavelength region to increase the efficiency of the solar cell. The front protective film 120 may have a thickness of approximately 70 nm to 80 nm.

A first doping portion 141 and a second doping portion 142 are alternately formed on the other surface of the semiconductor substrate 110.

The first doping portion 141 is doped with an n-type impurity at a higher concentration than the concentration of the semiconductor substrate 110.

The second doping portion 142 is highly doped with the p-type impurity, and the second doping portion 142 forms a p-n junction with the n-type semiconductor substrate 110.

The first doping portion 141 and the second doping portion 142 are movement paths of carriers such as electrons and holes and electrons and holes are collected in the direction of the first doping portion 141 and the second doping portion 142, . Also, the second doping portion 142 increases the efficiency of the solar cell by preventing electrons and holes from recombining on the surface of the semiconductor substrate 110 and disappearing.

Unlike the present embodiment, when the semiconductor substrate 110 has a p-type conductivity type, the conductivity types of the first and second doping portions 141 and 142 are opposite to each other.

A rear protective layer 150 is formed on the first doping portion 141 and the second doping portion 142.

The rear protective film 150 is formed of a silicon oxide film (SiO ₂ ), a silicon nitride film (SiN x) or the like. A plurality of first and second openings 181 and 182 are formed on the rear protective layer 150 to expose portions of the first doping portion 141 and the second doping portion 142, respectively.

The rear protective layer 150 prevents recombination of carriers separated into electrons and holes, and reflects the incident light to the inside of the solar cell so as to prevent the incident light from being lost to the outside, thereby reducing the amount of light lost to the outside.

The plurality of first electrodes 161 extend from the first bus bar 171 toward the second bus bar 172 in a substantially comb-shaped manner in one direction, for example, a transverse direction. The plurality of first electrodes 161 are formed on the first doped portion 141 exposed through the first openings 181 without being covered with the rear protective layer 150 and electrically connected to the first doped portions 141 have. Accordingly, the plurality of first electrodes 161 transmit carriers, for example electrons, moving from the first doping unit 141 to the first bus bar 171.

The plurality of second electrodes 162 extend from the second bus bar 172 toward the first bus bar 171 in a substantially comb-shaped manner in one direction, for example, in the transverse direction, 161 adjacent to each other. The plurality of second electrodes 162 are formed on the second doping portion 142 exposed through the second opening portion 182 without being covered with the rear shielding layer 150 and are electrically connected to the second doping portion 142. Thus, the plurality of second electrodes 162 transfer carriers, e.g., holes, moving from the second doping portion 142 to the second bus bar 172.

The first and second electrodes 161 and 162 are formed adjacent to each other, and the first electrode 161 and the second electrode 162 are alternately formed.

The shape of the first electrode 161 and the second electrode 162 varies depending on the position, and the cross-sectional area of the first and second electrodes 161 and 162 varies depending on the position.

That is, the cross-sectional area of the first electrode 161 increases as it approaches the first bus bar 171 connected to the first electrode 161, and increases as the second bus bar 172 opposed to the first electrode 161 The cross-sectional area of the second electrode 162 increases as it approaches the second bus bar 172 connected to the second electrode 162, and the cross-sectional area of the second bus bar 172, (171).

The first electrode 161 and the second electrode 162 have widths w1 and w2 and heights d1 and d2 that vary depending on the position. 3, the width w1 and the height d1 of each first electrode 161 have the greatest value at the portion connected to the first bus bar 171 and gradually decrease toward the end portion, It has the smallest value.

The width w2 and the height d2 of each second electrode 162 have the greatest value at the portion connected to the second bus bar 172 and gradually decrease toward the end portion and have the smallest value at the end portion.

The heights d1 and d2 and the widths w1 and w2 of the first and second electrodes 161 and 162 are determined according to the size of the sun electrons. D1 and d2 of the heights d1 and d2 and the amounts of variation w1 and w2 of the width w1 and w2 of the photovoltaic cells 161 and 162 are also determined according to the size of the solar cell.

For example, the heights d1 and d2 of the first and second solar cells may be several hundreds of angstroms to several hundreds of micrometers, respectively, and the variation amounts? D1 and? D2 of the heights of the first and second solar cells, May be several hundreds of micrometers.

The widths w1 and w2 of the first and second solar cells may be in the range of about 1 m to about 10 cm Lt; / RTI >

In this embodiment, the cross-sectional areas of the first and second electrodes 161 and 162 located at the same distance from the first and second bus bars 171 and 172 connected to each other are different from each other, Is larger than the cross-sectional area of the second electrode (162). At least one of the heights d1 and d2 and the widths w1 and w2 of the first and second electrodes 161 and 162 and the variation widths? D1,? D2,? W1 and? The sizes of the cross-sectional areas of the first and second electrodes 161 and 162 located at the same distance from the first and second bus bars 171 and 172 connected to each other can be made different. Accordingly, the total area of the second electrode 162, which transfers holes to the second bus bar 172 and serves as an emitter, of the first electrode 161 that transfers electrons to the first bus bar 171 Area, the operation efficiency of the solar cell is increased.

Alternatively, however, the cross-sectional area of the first and second electrodes 161, 162 located at the same distance from each of the connected first and second bus bars 171, 172 may be the same. At this time, the sizes (d1, d2,? W1,? W2) of the heights (d1, d2) and the widths (w1, w2) of the first and second electrodes 1 and the second electrodes 161 and 162 can be equalized.

The first bus bar 171 is connected to the plurality of first electrodes 161 and is connected to a carrier (for example, electrons) collected through the first electrode 161, .

The second bus bar 172 is connected to the plurality of second electrodes 162 to transfer the carriers collected through the second electrode 162, for example holes, to a load connected to the outside.

In this way, when the first and second electrodes 161 and 162 are formed with different cross-sectional areas according to their positions, that is, in order to increase the cross-sectional area of the bus bars 171 and 172 adjacent to the bus bars 171 and 172, 1 and the second electrodes 161 and 162 are formed, the carrier transport capability of the first and second electrodes 161 and 162 changes according to the variable load amount depending on the position.

Carriers such as electrons and holes collected in the first and second doping units 141 and 142 move to adjacent portions of the first electrode 161 and the second electrode 162 which are in contact with each other, 171, and 172, respectively. As the bus bars 171 and 172 approach the bus bars 171 and 172, the carriers that have already flown in from the first and second electrodes 161 and 162 and flow toward the bus bars 171 and 172 are combined , The amount of the carrier moving toward the bus bars 171 and 172 increases, and the resistance component due to the carrier increases greatly.

At this time, if the widths and heights of the first and second electrodes connected to the respective bus bars are constant and the cross-sectional area of the first and second electrodes is constant regardless of the positional change, regardless of the increasing amount of carriers, I have the ability. Therefore, when the amount of carriers to be transported is larger than the transporting capability of the first and second electrodes, the load increases and heat generation occurs, and the carrier transport ability of the first and second electrodes also deteriorates, .

However, as the cross-sectional area of the first and second electrodes 161 and 162 increases as the first and second bus bars 171 and 172 approach the first and second bus bars 171 and 172 as in the present embodiment, . Accordingly, since the cross-sectional area of the first and second electrodes 161 and 162 increases in proportion to the amount of the increased carrier, the collecting ability and the transporting ability of the carrier are improved to improve the heat generation due to the increase of the load, And the operation efficiency of the solar cell is improved.

The first and second electrodes 161 and 162 and the first and second bus bars 171 and 172 are made of at least one conductive metal material. Examples of these conductive metal materials include nickel (Ni), copper ), Silver (Ag), aluminum (Al), tin (Sn), zinc (Zn), indium (In), titanium (Ti), gold (Au) , Or other conductive metal materials.

In FIG. 1, for convenience, the number of the first and second electrodes 161 and 162 connected to the first and second bus bars 171 and 172 is three, respectively. However, the number of the first and second electrodes 161 and 162 is not limited to three, The number and size of the electrodes 161 and 162 can be changed according to the size of the solar cell.

In the solar cell 10 according to this embodiment having the above-described structure, since the two electrodes 162 of the first electrode 161 are all formed on the rear surface of the semiconductor substrate 110 to which no light is incident, The operation of the solar cell is as follows.

That is, when light is irradiated into the p-n junction of the solar cell 10, electrons and holes, which are carriers, are generated in the semiconductor portions 110, 141 and 142 inside the semiconductor by light energy. Generally, when light below a bandgap energy enters a semiconductor, it weakly interacts with electrons in the semiconductor, and when light having a bandgap or more enters, electrons in the covalent bond are excited to generate electrons or holes. The electrons generated by the light energy move toward the first doping unit 141 and are collected on the first electrode 161 and transferred to the first bus bar 171. The generated holes are transferred to the second electrode The electrons move toward the doping portion 142 and are collected on the second electrode 162 and transferred to the second bus bar 172.

Therefore, the electrons and holes transferred through the first bus bar 171 and the second bus bar 172 move to the connected load and the current flows, so that they are used as electric power from the outside.

The cross sectional area of the first and second electrodes 161 and 162 connected to the first and second bus bars 171 and 172 increases as the first and second bus bars 171 and 172 are adjacent to each other Since the carrier transport ability is improved, the heat generation due to the carrier increasing as the substrate moves toward the first and second bus bars 171 and 172 is reduced, and the carrier transport ability of the first and second electrodes 161 and 162 .

1 and 3, both the width and the height of the first and second electrodes 161 and 162 are changed in order to change the cross-sectional area of the first and second electrodes 161 and 162, The cross-sectional area of the first and second electrodes 161 and 162 can be changed by changing one of the width and the height of the second electrodes 161 and 162.

Another example of the solar cell according to the embodiment will be described with reference to FIGS. 4 to 8. FIG.

4 is a cross-sectional view of the solar cell of FIG. 4 along the line VV, and FIG. 6 is a cross-sectional view of a solar cell according to an embodiment of the present invention FIG. 7 is a cross-sectional view of the solar cell of FIG. 6 taken along line VII-VII. 8 is a plan view of a back surface of another example of a solar cell according to an embodiment of the present invention.

4 and 5, the solar cell changes only the width of each of the first and second electrodes 161 and 162 according to the distance from the first and second bus bars 171 and 172, 1 and the second electrodes 161 and 162 are changed. That is, the height of the first electrode 161 connected to the first bus bar 171 is the same, but as the distance from the first bus bar 171, for example, the distance from the first bus bar 171, The width of the first electrode 171 becomes narrow. The height of the second electrode 162 connected to the second bus bar 172 is the same as the height of the first electrode 161 but the height of the second electrode 162 connected to the second bus bar 172 is, As the distance from the bus bar 172 increases, the width of the second electrode 162 becomes narrower.

6 and 7, the solar cell is connected to the first and second electrodes 161 and 162 in accordance with distances from the first and second bus bars 171 and 172, respectively, unlike FIGS. 4 and 5, 162 are changed to change the cross-sectional area of the first and second electrodes 161, 162. That is, the width of the first electrode 161 connected to the first bus bar 171 is the same, but the distance from the first bus bar 171 to the first bus bar 171 The height of the first electrode 171 decreases. The width of the second electrode 162 connected to the second bus bar 172 is the same but the distance from the second bus bar 172 to the second bus bar 172 The height of the second electrode 162 is reduced.

In yet another example, the solar cell may have different cross-sectional areas in at least two portions of each electrode 161, 162. That is, as shown in FIG. 8, each of the electrodes 161 and 162 has two portions having different cross-sectional areas, and the cross-sectional area of each portion is changed by using the height and width of the electrodes 161 and 162. In this case, the cross-sectional area of the portion closer to each of the bus bars 171 and 172 is larger than the cross-sectional area thereof. In FIG. 8, the cross-sectional area of the two portions was changed by changing only the width of each of the electrodes 161 and 162. However, unlike the above, it is possible to change only the height, or to change the width and height both to make the cross-sectional area of the different part different.

In Figs. 4-8, the electrodes connected to the same bus bar have the same shape and the same cross-sectional area on the same line. However, at least one of the width, the height, and the variation amount between the electrodes connected to the different bus bars is different, and the sectional areas of the first electrode 161 and the second electrode 162 located on the same line are different from each other, 162 are larger than the cross-sectional area of the first electrode 161.

However, the first electrode 161 and the second electrode 162, which are located on the same line by using at least one of the width, the height, and the variation amount between the electrodes connected to the different bus bars, are equal to each other, The electrodes connected to the bars may have the same shape.

Alternatively, the cross-sectional area of the first and second electrodes 161 and 162 may be changed by using other than the width and the height of the first and second electrodes 161 and 162.

In addition, the present embodiment is described based on a solar cell having a rear junction type electrode structure in which both first and second electrodes 161 and 162 for transferring electrons and holes are formed on the rear surface of the semiconductor substrate 110 However, the present invention is not limited thereto, and can be applied to various types of solar cells.

For example, the present invention can be applied to a solar cell in which a plurality of first electrodes for transferring electrons are formed on the front surface of a semiconductor substrate, and a second electrode for transferring holes is formed on the entire rear surface of the semiconductor substrate. In this case, the cross-sectional area of the first electrode increases as the shape of the first electrode according to the present embodiment becomes closer to the connected bus bar. Therefore, this embodiment is applicable to a solar cell having an electrode for transferring a carrier.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

1 is a plan view of a rear surface of an example of a solar cell according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the solar cell of FIG. 1 taken along line II-II.

3 is an enlarged view of a part of the first and second electrodes shown in Fig.

4 is a plan view of a back surface of another example of a solar cell according to an embodiment of the present invention.

5 is a cross-sectional view of the solar cell of FIG. 4 taken along line V-V.

6 is a plan view of a back surface of another example of a solar cell according to an embodiment of the present invention.

FIG. 7 is a cross-sectional view of the solar cell of FIG. 6 taken along line VII-VII.

8 is a plan view of a back surface of another example of a solar cell according to an embodiment of the present invention.

[Description of Drawings]

110: semiconductor device 120: front shield

130: antireflection film 141: first doping portion

142: second doping unit 150: rear shield

161: first electrode 162: second electrode

171, 172; Bus bars 181, 182; Opening

Claims

a semiconductor portion forming a p-n junction, and

And an electrode formed on the semiconductor portion and connected to the bus bar, for transferring a carrier formed in the semiconductor portion to the bus,

Wherein the electrode has a cross-sectional area of a first portion located at a first distance from the bus bar and a cross-sectional area of a second portion located at a second distance more distant from the first distance

Solar cells.

The method of claim 1,

Wherein a cross-sectional area of the first portion is larger than a cross-sectional area of the second portion.

The method of claim 1,

Wherein a cross-sectional area of the electrode varies in proportion to a distance from the bus bar.

4. The method of claim 3,

Wherein a cross-sectional area of the electrode increases in size as it approaches the bus bar.

5. The method according to any one of claims 1 to 4,

Wherein the cross-sectional area varies depending on at least one of a width and a height of the electrode.

The method of claim 1,

Wherein the carrier is one of an electron and a hole.

The method of claim 1,

Wherein the electrode includes a first electrode for transferring electrons and a second electrode for transferring holes,

Wherein the bus bar includes a first bus bar connected to the first electrode and a second bus bar connected to the second electrode,

Wherein the first electrode has a first cross-sectional area that varies in size according to a distance from the first bus bar,

Wherein the second electrode has a second cross-sectional area that varies in size according to a distance from the second bus bar.

8. The method of claim 7,

Wherein the first and second cross-sectional areas increase in size as they approach the first and second bus bars, respectively.

8. The method of claim 7,

Wherein a first cross-sectional area of the first electrode located at the same distance from the first bus bar and a second cross-sectional area of the second electrode are different from each other.

The method of claim 9,

Wherein a size of a cross-sectional area of the first electrode located at a first distance from the first bus bar is smaller than a size of a cross-sectional area of the second electrode located at the first distance from the second bus bar.

11. The method according to any one of claims 7 to 10,

Wherein at least one of a width and a height of the first and second electrodes is varied according to a distance from the first bus bar and the second bus bar.

8. The method of claim 7,

Wherein the first and second electrodes are formed on the same side of the semiconductor portion.

A first doping of a first conductivity type formed over a semiconductor substrate of a first conductivity type,

A second doping portion of another of the second conductivity type of the first conductivity type,

A first electrode formed on the first doping region,

A second electrode formed on the second doping region,

A first bus bar for receiving a carrier from the first electrode,

And a second bus bar for receiving a carrier from the second electrode,

Wherein a cross-sectional area of the first electrode portion located on the same line and a cross-sectional area of the second electrode portion are different from each other.

The method of claim 13,