KR20120035509A - Semiconductor substrate for solarcell and texturing method thereof - Google Patents

Abstract

PURPOSE: A semiconductor substrate for a solar cell and a texturing method thereof is provided to improve optical efficiency by improving the internal reflectance of a TCO(Transparent Conductive Oxide) deposited on a substrate. CONSTITUTION: A photo-acryl(110) is formed on a substrate(100). The photo-acryl is coated on the substrate in a spin coating method. The photo-acryl includes a light scattering device(110a) processed in haze on an ambo pattern through a plasma etch process. A TCO(120) is formed on the photo-acryl. A light absorption layer(130) is formed on the TCO.

Description

Semiconductor Substrate for Solar Cell and Texturing Method {Semiconductor Substrate for Solarcell and Texturing Method}

TECHNICAL FIELD The present invention relates to a semiconductor substrate for a solar cell, and more particularly, to a semiconductor substrate for a solar cell and a texturing method thereof capable of improving light scattering effects.

A solar cell is a photovoltaic device that converts photons into electrical energy using a semiconductor. The principle of converting sunlight into electrical energy in a solar cell uses the p-n junction principle of a semiconductor.

In more detail, semiconductors such as Si, Ge, and As have a conduction band and a valence band, and a forbidden band, in which an electron cannot exist between the valence band and the conduction band. ) And the width of this ban is called the energy gap. When the energy corresponding to the energy gap, ie, light is irradiated to the semiconductor, photons are absorbed by the semiconductor, and the absorbed photons provide a pair of free electrons and holes in a stable state in the substrate. can be changed into a hole. Since the generated electrons and holes exist stably for a certain time of life, the electrons and positively charged holes are separated within this time and then recombined from the outside through the electrode terminals to consume current. It becomes usable.

In addition, doping a p-type impurity in one portion of the semiconductor crystal and an n-type impurity in the remaining portion forms a single crystal ane p-type semiconductor and an n-type semiconductor, and a metallic interface between the p-type semiconductor and the n-type semiconductor. Is called a pn junction. Since the p-type semiconductor is doped with a trivalent acceptor atom, a lot of curves are generated, and since the n-type semiconductor is doped with a pentavalent donor atom, many electrons are formed.

Therefore, in the pn junction, as the hole concentrations and the electron concentrations of the p-type and n-type semiconductors are different, holes diffuse toward the n-type semiconductor and p-type semiconductors. Only the acceptor ions remain, only the positively charged donor ions remain on the n-type semiconductor side, and ± space charges are generated near the junction to suppress the diffusion of holes and electrons, resulting in thermal equilibrium. do. When an energy source is externally applied to the pn junction that has reached this passion equilibrium state, the p-type semiconductor shows a positive voltage and the n-type semiconductor shows a negative voltage, so that current can be obtained as the current flows in only one direction. Can be.

On this principle, a solar cell's ability to convert sunlight into electrical energy generally measures the efficiency at which light energy is converted into electrical energy, the value of which is a ratio of the amount of incident light at the electrical output of the solar cell, usually It is expressed in%.

Therefore, many studies have been conducted to increase the efficiency of solar cells, and one method is to use a method of maximizing light absorption by texturing the wafer surface. As the texturing method, a chemical etching method, a plasma etching method, a mechanical scribing method, a photolithography method, and the like are used.

Among the above methods, the chemical etching method is getting much attention as a method of texturing a large amount of wafers at a low price in a short time. Chemical etching methods include isotropic etching and anisotropic etching, and as an example of isotropic etching, haze the TCO (Transparent Conductive Oxide) surface deposited on glass using an acidic solution. There is a way to handle it.

In this case, since the internal reflectance is weak, the average free path of the solar light is shortened, which causes a problem of deterioration of the light efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor substrate for a solar cell and a texturing method thereof capable of improving the efficiency of light by increasing the internal reflectance to increase the scattering effect of sunlight.

A semiconductor substrate for a solar cell according to an embodiment of the present invention includes a substrate, a photoacryl coated on the substrate and having an embo pattern formed on a surface thereof through an exposure process, and a light absorbing layer formed on the photoacryl. The photoacryl includes a plurality of light scattering means that have been hazed on the emboss pattern through a plasma etching process.

A texturing method of a semiconductor substrate for a solar cell according to an embodiment of the present invention comprises the steps of preparing a substrate, coating a photoacryl excellent in light transmittance through spin coating on the substrate, and the surface of the photoacryl through an exposure process Forming an emboss pattern on the embossed pattern; forming a plurality of light scattering means on the emboss pattern through an oxygen plasma etching process; and forming the emboss pattern and a plurality of light scattering means Forming a light absorbing layer on the photoacrylic.

The semiconductor substrate for a solar cell according to the embodiment of the present invention is formed on the substrate by coating the photoacryl on the substrate and then forming an emboss pattern through an exposure process, and haze treatment on the emboss pattern using a plasma etching method. The internal reflectance of the TCO can be improved to improve the light efficiency.

1 is a cross-sectional view of a semiconductor substrate for a solar cell according to an embodiment of the present invention.
2A to 2D are diagrams sequentially showing a manufacturing process of the solar cell semiconductor substrate of FIG. 1.
FIG. 3A is a view showing an embo pattern formed on the photoacrylic of FIG. 1, and FIG. 3B is a plurality of light scattering patterns on the embo pattern of FIG. This is a view showing a state formed.
4 is a flowchart illustrating a manufacturing process procedure for manufacturing a semiconductor substrate for a solar cell according to an embodiment of the present invention.

Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings.

1 is a cross-sectional view of a semiconductor substrate for a solar cell according to an embodiment of the present invention.

As shown in FIG. 1, a semiconductor substrate for a solar cell according to an embodiment of the present invention includes a substrate 100, a photoacryl 110 formed on the substrate 100, and a photoacryl 110 formed on the photoacryl 110. Transparent Conductive Oxide (TCO) 120 and a light absorbing layer 130 formed on the TCO.

The substrate 100 may be glass, stainless steel, polyethylene terephthalate (PET), polyethylenenaphthelate (PEN), polypropylene (PP), polyamide (PI), or triacetyl cellulose (TAC). Preferably glass.

The photoacryl 110 is coated on the substrate 100 by using a spin coating method. The substrate 100 coated with the photoacryl 110 has an oval or semi-circular emboss pattern on the surface of the photoacryl 110 through an exposure process.

The light scattering means 110a is formed on the emboss pattern through a plasma etching process. The light scattering means 110a is formed on an emboss pattern of the photoacryl 110 by haze treatment through a plasma etching process.

The TCO 120 and the light absorbing layer 130 are sequentially formed on the photoacryl 110 on which the light scattering means 110a is formed.

2A to 2D are diagrams sequentially showing a manufacturing process of the solar cell semiconductor substrate of FIG. 1.

As shown in FIG. 2A, a photoacryl 110 having excellent transmittance is formed on the substrate 100 through a spin coating method. The substrate 100 coated with the photoacryl 110 is subjected to an exposure process. During the exposure process, an oval or semi-circular emboss pattern is formed on the photoacryl 110 according to the degree of exposure.

The size and height of the embo pattern vary depending on the exposure amount generated during the exposure process, and the ambo pattern having the optimal reflectance is determined according to the degree of the exposure amount. As described above, the photoacryl 110 is excellent in transmittance and has a different reflectance according to the shape of an embo pattern.

As the ambo pattern having an optimal reflectance is formed on the photoacryl 110, the internal reflectance of the substrate 100 coated with the photoacryl 110 is increased. As the internal reflectance increases, the average travel path of the solar light is increased, thereby improving the light efficiency.

Subsequently, as shown in FIG. 2C, the substrate 100 on which the photoacryl 110 having the embo pattern is formed is subjected to an oxygen plasma etching process. A plurality of light scattering means 110a that has been hazed through the oxygen plasma etching process are formed on the ambo pattern.

As the plurality of light scattering patterns 110a are formed on the semicircular emboss pattern, the light scattering effect of the photoacryl 110 is increased.

Subsequently, as shown in FIG. 2D, the TCO 120 and the light absorbing layer 130 are sequentially formed on the substrate 100 on which the plurality of light scattering patterns 110a are formed. In this case, the TCO 120 means an interface between the photoacryl 110 and the light absorbing layer 130.

FIG. 3A is a view showing an embo pattern formed on the photoacrylic of FIG. 1, and FIG. 3B is a plurality of light scattering patterns on the embo pattern of FIG. This is a view showing a state formed.

As shown in FIG. 1 and FIG. 3A, an emboss corresponding to a reflectance of 96 to 97% through an exposure process after coating a photoacryl (110 of FIG. 1) having excellent light transmittance on the substrate 100. (ambo) forms a pattern. Shapes such as the size and height of the embo pattern are determined according to the exposure amount, which can be measured through experiments.

The embo pattern may be formed in a semicircle shape or an elliptical shape. As shown in FIG. 3B, a plurality of haze-processed light scattering means are formed on the substrate 100 having the emboss pattern formed thereon through an oxygen plasma etching process.

Such a plurality of light scattering means can increase the light absorption efficiency from the light absorbing layer (130 of FIG. 1) of the solar cell.

Forming an emboss (ambo) on the photoacryl 110, by forming a plurality of haze (haze) light scattering means (110a) on the emboss (ambo) by a solar cell Internal reflectance in the interior is improved.

In addition, since the internal reflectance is improved through the emboss pattern and the plurality of light scattering means 110a, the light scattering effect is increased, thereby increasing the absorption efficiency of the light absorbing layer 130.

4 is a flowchart illustrating a manufacturing process procedure for manufacturing a semiconductor substrate for a solar cell according to an embodiment of the present invention.

As shown in FIG. 4, a photoacryl having excellent transmittance is coated on the substrate. (s10)

Subsequently, the photoacryl-coated substrate is exposed to form an embossed pattern having a semicircle or ellipse shape on the photoacryl surface. Subsequently, a plurality of light scattering means are formed on the embo pattern through an oxygen plasma etching process. (s30) Subsequently, a transparent conductive oxide (TCO) and a light absorbing layer are sequentially formed on the substrate having the embossed pattern on which the light scattering means is formed. (s40)

That is, the solar cell semiconductor substrate according to the embodiment of the present invention coats the photoacryl on the substrate, forms an optimal embo pattern to increase the internal reflectance of the photoacryl, and then hazes through a plasma etching process. By forming a plurality of treated light scattering patterns on the embossed pattern, the internal reflectance of the solar cell may be increased to increase the light scattering effect.

100: substrate 110: photoacrylic
110a: light scattering means 120: TCO
130: light absorption layer

Claims (8)

Board;
Photoacryl coated on the substrate and having an embo pattern formed on its surface through an exposure process; And
And a light absorbing layer formed on the photo acrylic.
The photoacryl is a semiconductor substrate for a solar cell, characterized in that it comprises a plurality of light scattering means haze (haze) through the plasma etching process on the embo (ambo) pattern. The method according to claim 1,
The shape of the embo pattern is determined in accordance with the exposure amount during the exposure process so that the internal reflectance of the photoacryl is 96 ~ 97%. The method according to claim 1,
The embossed pattern has a semicircle or elliptical shape. The photoacryl is a semiconductor substrate for a solar cell, characterized in that the coating on the substrate by a spin coating method. The method according to claim 1,
The substrate is characterized in that it is composed of any one of glass, stainless steel, polyethylene terephthalate (PET), polyethylenenaphthelate (PEN), polypropylene (PP), polyamide (PI), or triacetyl cellulose (TAC). Semiconductor substrate for solar cell. Preparing a substrate;
Coating a photoacryl having excellent light transmittance through spin coating on the substrate;
Forming an ambo pattern on the photoacryl surface through an exposure process;
Forming a plurality of light scattering means on the embo pattern through an oxygen plasma etching process; And
And forming a light absorbing layer on the photoacryl on which the emboss pattern and the plurality of light scattering means are formed. The method of claim 6,
The shape of the emboss (ambo) pattern is a texturing method of the semiconductor substrate for a solar cell, characterized in that determined according to the exposure amount during the exposure process so that the internal reflectance of the photoacryl is 96 ~ 97%. The method of claim 6,
The substrate is characterized in that it is composed of any one of glass, stainless steel, polyethylene terephthalate (PET), polyethylenenaphthelate (PEN), polypropylene (PP), polyamide (PI), or triacetyl cellulose (TAC). Texturing method of semiconductor substrate for solar cell.

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