CN115863490A - Method for depositing intrinsic amorphous silicon thin film by PECVD method, cell preparation method and cell - Google Patents

Abstract

The invention discloses a method for depositing an intrinsic amorphous silicon thin film by a PECVD method, a cell preparation method and a cell, wherein the method for depositing the intrinsic amorphous silicon thin film by the PECVD method comprises the following steps: taking silane as a reaction gas, and sequentially depositing a first intrinsic amorphous silicon film layer and a second intrinsic amorphous silicon film layer on a silicon wafer substrate, wherein the deposition rate V1 of the first intrinsic amorphous silicon film layer during deposition is 0.4nm/s-1.2nm/s; the radio frequency power W2 during the deposition of the second intrinsic amorphous silicon film layer is less than the radio frequency power W1 during the deposition of the first intrinsic amorphous silicon film layer; and depositing and forming a third intrinsic amorphous silicon film layer on the second intrinsic amorphous silicon film layer by taking the mixed gas of silane and hydrogen as a reaction gas. The embodiment of the invention avoids the condition that the radio frequency source is suddenly reduced from high radio frequency power to zero, further avoids a silicon powder layer formed on the amorphous silicon film due to the sudden reduction of the radio frequency power, and improves the passivation effect of the intrinsic amorphous silicon film.

Description

Method for depositing intrinsic amorphous silicon thin film by PECVD method, cell preparation method and cell

Technical Field

The invention relates to the field of heterojunction cells, in particular to a method for depositing an intrinsic amorphous silicon thin film by a PECVD method, a cell preparation method and a cell.

Background

With the development of solar cells, the cell conversion efficiency is higher and higher. As one of the development directions of high-efficiency batteries, heterojunction batteries have been increasingly used in the industry.

The silicon-based heterojunction cell is a hybrid solar cell made of a crystalline silicon substrate and an amorphous silicon film, and is characterized in that doped amorphous silicon films are respectively deposited and molded on the front side and the back side of a monocrystalline silicon wafer, a transparent conductive layer is formed on the doped amorphous silicon films, and electrodes are formed on the transparent conductive layer. The PN junction of the silicon-based heterojunction battery has a heterogeneous interface, the composite activity of the heterogeneous interface is high, and effective passivation of the heterogeneous interface is a key core technology of the heterojunction battery.

In order to inhibit the high recombination activity of a heterogeneous interface, an intrinsic amorphous silicon film is also formed between the doped amorphous silicon film and the monocrystalline silicon wafer, the intrinsic amorphous silicon film is used as an amorphous silicon passivation layer on the surface of the monocrystalline silicon wafer, the surface of the silicon wafer can be effectively passivated, the surface recombination rate is greatly reduced, and meanwhile, a larger built-in electric field can be obtained after a PN junction is formed between the larger band gap width and the monocrystalline silicon wafer, so that the heterojunction battery has higher open-circuit voltage.

The radio frequency plasma deposition technology (RF-PECVD) is usually used for growing amorphous silicon, and the common problem in the growth process of the amorphous silicon thin film is that the epitaxial growth of the amorphous silicon thin film on a single crystal silicon wafer occurs, once the epitaxial growth occurs, the passivation effect of an intrinsic amorphous silicon thin film is greatly reduced, and the open-circuit voltage and the conversion efficiency of a heterojunction cell are influenced; in order to inhibit epitaxial growth of the amorphous silicon thin film, a high deposition rate is generally adopted when the intrinsic amorphous silicon thin film is formed, but the adoption of the high deposition rate can cause the growth of the intrinsic amorphous silicon thin film to be not compact, so that the passivation effect is influenced.

Therefore, how to control the formation of the intrinsic amorphous silicon thin film to better realize the passivation effect has important significance.

Disclosure of Invention

The invention aims to provide a method for depositing an intrinsic amorphous silicon thin film by a PECVD (plasma enhanced chemical vapor deposition) method, which can effectively avoid a silicon powder layer formed on the amorphous silicon thin film due to the sudden reduction of radio frequency power and improve the passivation effect of the intrinsic amorphous silicon thin film.

The invention provides a method for depositing an intrinsic amorphous silicon film by a PECVD method, which comprises the following steps:

taking silane as a reaction gas, and sequentially depositing a first intrinsic amorphous silicon film layer and a second intrinsic amorphous silicon film layer on a silicon wafer substrate, wherein the deposition rate V1 of the first intrinsic amorphous silicon film layer during deposition is 0.4nm/s-1.2nm/s; the radio frequency power W2 during the deposition of the second intrinsic amorphous silicon film layer is less than the radio frequency power W1 during the deposition of the first intrinsic amorphous silicon film layer;

and depositing and forming a third intrinsic amorphous silicon film layer on the second intrinsic amorphous silicon film layer by taking the mixed gas of silane and hydrogen as a reaction gas.

Further, the difference delta W between the radio frequency power W2 during the deposition of the second intrinsic amorphous silicon film layer and the radio frequency power W1 during the deposition of the first intrinsic amorphous silicon film layer is not more than 600W.

Furthermore, the first intrinsic amorphous silicon film layer and the second intrinsic amorphous silicon film layer are deposited and formed in the first reaction cavity, and the pressure in the first reaction cavity is reduced when the second intrinsic amorphous silicon film layer is deposited.

Further, the deposition rate V3 of the third intrinsic amorphous silicon film layer is less than V1; the deposition rate V3 of the third intrinsic amorphous silicon film layer is between 0.03nm/s and 0.3 nm/s.

Furthermore, the thickness of the third intrinsic amorphous silicon film layer is greater than the sum of the thicknesses of the first intrinsic amorphous silicon film layer and the second intrinsic amorphous silicon film layer.

Further, when the third intrinsic amorphous silicon film layer is deposited and formed, the ratio of silane/hydrogen in the mixed gas of silane and hydrogen is in the range of 5.

Furthermore, the second intrinsic amorphous silicon film layer comprises a plurality of layers deposited on the first intrinsic amorphous silicon film layer in sequence, and the radio frequency power of the deposition of the plurality of layers is sequentially reduced along with the deposition sequence and is smaller than the radio frequency power of the deposition of the first intrinsic amorphous silicon film layer.

The invention also discloses a battery preparation method, which comprises the following steps:

providing an N-type silicon wafer substrate, and texturing and cleaning the N-type silicon wafer substrate;

respectively depositing and forming an upper intrinsic amorphous silicon film and a lower intrinsic amorphous silicon film on the upper side and the lower side of an N-type silicon wafer substrate by adopting the method for depositing the intrinsic amorphous silicon films by the PECVD method;

depositing and forming an N-type doped layer on the upper side of the upper intrinsic amorphous silicon film;

depositing and molding a P-type doping layer on the lower side of the lower intrinsic amorphous silicon film;

a light-transmitting conducting layer is respectively arranged on the lower side of the P-type doping layer and the upper side of the N-type doping layer;

and forming an electrode on the light-transmitting conductive layer.

The embodiment of the invention also discloses a battery, which comprises:

an N-type silicon wafer substrate;

the upper intrinsic amorphous silicon film and the lower intrinsic amorphous silicon film layer are arranged on the upper side and the lower side of the N-type silicon wafer substrate; the upper intrinsic amorphous silicon film layer and the lower intrinsic amorphous silicon film layer are deposited and formed by adopting the PECVD deposition method for depositing the intrinsic amorphous silicon film;

the P-type doping layer is arranged on the lower side of the lower intrinsic amorphous silicon film layer;

the N-type doping layer is arranged on the upper side of the upper intrinsic amorphous silicon film;

the light-transmitting conducting layer is arranged on the upper side of the N-type doping layer and the lower side of the P-type doping layer;

and the electrode is arranged on the light-transmitting conducting layer and is electrically connected with the light-transmitting conducting layer.

Compared with the prior art, the second intrinsic amorphous silicon film layer is deposited and formed between the first intrinsic amorphous silicon film layer and the third intrinsic amorphous silicon film layer, and the radio frequency power emitted by the radio frequency source is weakened when the second intrinsic amorphous silicon film layer is deposited and formed. The situation that the radio frequency source is suddenly reduced from high radio frequency power to zero is avoided, a silicon powder layer formed on the amorphous silicon thin film due to sudden reduction of the radio frequency power is further avoided, and the passivation effect of the intrinsic amorphous silicon thin film is improved.

Drawings

Fig. 1 is a schematic flow chart of a method for manufacturing a battery according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a battery disclosed in an embodiment of the present invention.

Detailed Description

The embodiments described below with reference to the drawings are illustrative only and should not be construed as limiting the invention.

The embodiment of the invention comprises the following steps: discloses a method for depositing an intrinsic amorphous silicon film by a PECVD method, which comprises the following steps:

taking silane as a reaction gas, and sequentially depositing a first intrinsic amorphous silicon film layer and a second intrinsic amorphous silicon film layer on a silicon wafer substrate, wherein the deposition rate V1 of the first intrinsic amorphous silicon film layer during deposition is 0.4nm/s-1.2nm/s; the radio frequency power W2 during the deposition of the second intrinsic amorphous silicon film layer is less than the radio frequency power W1 during the deposition of the first intrinsic amorphous silicon film layer; the first intrinsic amorphous silicon film layer and the second intrinsic amorphous silicon film layer are deposited and formed in the first reaction cavity;

taking the mixed gas of silane and hydrogen as a reaction gas, and depositing and forming a third intrinsic amorphous silicon film layer on the second intrinsic amorphous silicon film layer, wherein the third intrinsic amorphous silicon film layer can be a single-layer film structure or a multi-layer film structure containing different SiH4/H2 ratios; and the third intrinsic amorphous silicon film layer is deposited and formed in the second reaction cavity.

The intrinsic amorphous silicon thin film disclosed by the embodiment comprises three layers, the three layers of intrinsic amorphous silicon thin films are sequentially deposited and formed on the silicon wafer substrate, the silicon wafer substrate can be an N-type monocrystalline silicon wafer, the first intrinsic amorphous silicon film layer is directly deposited and formed on the silicon wafer substrate, and the first intrinsic amorphous silicon film layer is deposited at a higher deposition rate, so that the epitaxial growth of the amorphous silicon thin film can be effectively inhibited at the higher deposition rate.

The epitaxial growth of the amorphous silicon film can be generated because the silicon wafer substrate is crystalline silicon, the surface state of the crystalline silicon has more unsaturated dangling bonds, and if the deposition rate is low, the amorphous silicon film can be preferentially combined with the dangling bonds of the crystalline silicon during deposition, so that the position of the dangling bonds forms the epitaxial growth.

A large amount of Si ions or radicals ionized during the deposition of the amorphous silicon film layer can not be selected at the same time by adopting a high deposition rate, and are deposited on the upper surface of the silicon wafer substrate, so that the epitaxial growth of the amorphous silicon film is effectively avoided. In the embodiment, the power of the first intrinsic amorphous silicon film layer during deposition is set to be 0.4nm/s-1.2nm/s, and the deposition rate in the interval can effectively inhibit the epitaxial growth of the amorphous silicon film layer.

Although the high deposition rate can effectively inhibit the epitaxial growth of the amorphous silicon thin film, the growth of the intrinsic amorphous silicon thin film is not compact, thereby affecting the passivation effect. In order to make the intrinsic amorphous silicon film layer have a better passivation effect, a third intrinsic amorphous silicon film layer is generally formed on the first intrinsic amorphous silicon film layer at a low deposition rate, and a reaction gas source is doped with hydrogen when the third intrinsic amorphous silicon film layer is deposited and formed. Namely, when the third intrinsic amorphous silicon film layer is formed by deposition, the gas in the reaction cavity is the mixed gas of silane and hydrogen, and the doped hydrogen can ionize more Si-H bonds from the reaction gas source, so that the passivation is facilitated by more Si-H bonds.

Because the mixed gas formed by hydrogen and silane is adopted during the deposition of the third intrinsic amorphous silicon film layer, and the deposition of the third intrinsic amorphous silicon film layer is different from the deposition of the first intrinsic amorphous silicon film layer only by using silane as a reflecting gas source, in order to keep the continuity of production and manufacture, the first intrinsic amorphous silicon film layer and the third intrinsic amorphous silicon film layer are generally completed in different reaction chambers.

Depositing a first intrinsic amorphous silicon film layer in a first reaction chamber, wherein a gas source supplied in the first reaction chamber is silane; and depositing a third intrinsic amorphous silicon film layer in the second reaction chamber, wherein the gas source supplied in the second reaction chamber is the mixed gas of silane and hydrogen. If the deposition forming in a reaction chamber needs longer ventilation time, the production continuity of the equipment is affected.

After the deposition of the first intrinsic amorphous silicon film layer is finished, different reaction cavities need to be replaced, and the radio frequency source needs to be closed when the reaction cavities are replaced, so that the radio frequency power emitted by the radio frequency source after the deposition of the first intrinsic amorphous silicon film layer is reduced to zero from a very high state, a large number of ionized Si ions or radicals can diffuse into the cavity of the first reaction cavity, the ions or radicals are large in amount and cannot be drawn away by the pump body in time, therefore, a silicon powder layer is easily deposited on the first intrinsic amorphous silicon, and the existence of the silicon powder layer can influence the passivation effect of the intrinsic amorphous silicon film.

In order to avoid the above technical problem, the second intrinsic amorphous silicon film layer is formed between the first intrinsic amorphous silicon film layer and the third intrinsic amorphous silicon film layer in a deposition manner in the present embodiment, the second intrinsic amorphous silicon film layer and the first intrinsic amorphous silicon film layer are both formed in a deposition manner in the first reaction chamber, and the reaction gas source supplied in the first reaction chamber is silane during the deposition forming process.

When the second intrinsic amorphous silicon film layer is deposited and formed, the radio frequency power W2 emitted by the radio frequency source is smaller than the radio frequency power W1 used when the first intrinsic amorphous silicon film layer is deposited and formed. And the second intrinsic amorphous silicon film layer and the first intrinsic amorphous silicon film layer are continuously deposited and formed in the first reaction cavity, the radio frequency source is directly reduced from high radio frequency power to low radio frequency power required by the deposition of the second intrinsic amorphous silicon film layer after the deposition and the formation of the first intrinsic amorphous silicon film layer, and then the radio frequency source is closed after the deposition and the formation of the second intrinsic amorphous silicon film layer.

The second intrinsic amorphous silicon film layer prevents the radio frequency source from suddenly reducing from high radio frequency power to zero, further prevents a silicon powder layer from being formed on the amorphous silicon film due to sudden reduction of the radio frequency power, and improves the passivation effect of the intrinsic amorphous silicon film.

Further, the difference delta W between the radio frequency power W2 during the deposition of the second intrinsic amorphous silicon film layer and the radio frequency power W1 during the deposition of the first intrinsic amorphous silicon film layer is not more than 600W. The sudden reduction of the radio frequency power of the radio frequency source during the deposition of the second intrinsic amorphous silicon film layer cannot exceed 600W, and the silicon powder layer is easily deposited after the sudden reduction exceeds 600W.

In the embodiment, the RF power for the deposition of the first intrinsic amorphous silicon film layer is generally 400-1000W, and the RF power for the deposition of the second intrinsic amorphous silicon film layer is generally 100-300W.

The third intrinsic amorphous silicon film layer has a lower deposition rate and a corresponding radio frequency power generally lower than that of the first intrinsic amorphous silicon film layer, and in a specific embodiment, the radio frequency power of the third intrinsic amorphous silicon film layer is 150W-400W.

In order to better avoid the formation of the silicon powder layer, the pressure P2 in the first reaction cavity is smaller than the pressure P1 in the first reaction cavity when the second intrinsic amorphous silicon film layer is deposited. The reduction in pressure reduces the total amount of gas in the first reaction chamber and thus the ionized gas molecules.

In a specific embodiment, the pressure in the first reaction chamber during deposition of the first intrinsic amorphous silicon film layer ranges from 0.5torr to 0.7torr, and the pressure in the first reaction chamber during deposition of the second intrinsic amorphous silicon film layer ranges from 0.2 torr to 0.5torr.

Correspondingly, the amount of the gas entering the reaction cavity can be reduced by controlling the flow of the gas source, so that ionized gas molecules are reduced. In the present embodiment, the amount of gas in the reaction chamber is changed only by changing the gas pressure. When the first intrinsic amorphous silicon film layer is deposited, the flow rate of the silane in the first reaction cavity ranges from 500 sccm to 2000sccm, and when the second intrinsic amorphous silicon film layer is deposited, the flow rate of the silane in the second reaction cavity ranges from 500 sccm to 2000sccm.

The above embodiment shows that a second intrinsic amorphous silicon film layer is deposited between the first intrinsic amorphous silicon film layer and the third intrinsic amorphous silicon film layer. In another embodiment, the second intrinsic amorphous silicon film layer comprises a plurality of layers, and the radio frequency power of the deposition of the plurality of layers is sequentially decreased along with the deposition sequence and is less than the radio frequency power of the deposition of the first intrinsic amorphous silicon film layer. The RF power of the first layer deposited on the first intrinsic amorphous silicon film layer among the plurality of layers is the maximum during deposition, and the RF power is continuously reduced along with the upward deposition.

It can be understood that when the layers are sequentially and continuously deposited upwards, the pressure in the first reaction chamber is gradually reduced, and the reduction of the pressure can reduce the content of silane in the reaction chamber, so that the ionized gas molecules are reduced.

The third intrinsic amorphous silicon film layer is used as the uppermost film layer and mainly plays a role in passivation, so that in order to ensure a good passivation effect, the deposition rate V3 of the third intrinsic amorphous silicon film layer during deposition forming is smaller than V1; the deposition rate V3 of the third intrinsic amorphous silicon film layer is in the range of 0.03nm/s to 0.3nm/s as a preferred scheme. The deposition rate V2 of the second intrinsic amorphous silicon film layer ranges from 0.1nm/s to 0.3 nm/s.

The second intrinsic amorphous silicon film layer is actually a transition layer between the first intrinsic amorphous silicon film layer and the second intrinsic amorphous silicon film layer, and the second intrinsic amorphous silicon film layer is actually a product on the first intrinsic amorphous silicon film layer in the process of stepping off the radio frequency source. The first intrinsic amorphous silicon film layer mainly plays a role in inhibiting epitaxial growth of the amorphous silicon film layer, the third intrinsic amorphous silicon film layer mainly plays a role in passivation, the second intrinsic amorphous silicon film layer mainly prevents a silicon powder layer from appearing after sudden reduction of the radio frequency source, the passivation effect is weak, and therefore the thickness of the second intrinsic amorphous silicon film layer is set to be not higher than that of the first intrinsic amorphous silicon film layer. Meanwhile, the thickness of the third intrinsic amorphous silicon film layer is larger than the sum of the thicknesses of the first intrinsic amorphous silicon film layer and the second intrinsic amorphous silicon film layer. The third intrinsic amorphous silicon film layer mainly plays a role of passivation, and thus the thickness is set to be greater than the first two.

In a specific embodiment, the thickness of the first intrinsic amorphous silicon film layer ranges from 1nm to 3nm, the thickness of the second intrinsic amorphous silicon film layer ranges from 0.5 nm to 2nm, and the thickness of the third intrinsic amorphous silicon film layer ranges from 2nm to 10 nm.

In order to better enable the third intrinsic amorphous silicon film layer to play a passivation effect, when the third intrinsic amorphous silicon film layer is deposited and formed, the ratio range of silane/hydrogen in the mixed gas of silane and hydrogen is 5.

The present invention also provides a specific example 1, and two sets of comparative experiments are provided to verify that example 1 using the scheme of the present invention has significant improvement and comparison, and in comparative experiment 1, two deposition rate controls are used when forming an intrinsic amorphous silicon thin film and two layers are deposited. In comparative experiment 1, a first film layer for inhibiting the epitaxial growth of the amorphous silicon film layer is deposited at a high deposition rate, and then a second film layer for passivation is deposited at a low deposition rate. In comparative experiment 2, the intrinsic amorphous silicon thin film was directly deposited at a single deposition rate.

Specifically, the specific method for forming the intrinsic amorphous silicon thin film in the scheme of example 1 is as follows:

firstly, depositing to form a first intrinsic amorphous silicon film layer in a first reaction cavity by taking silane as a reaction gas source, wherein the temperature in the first reaction cavity is controlled at 200 ℃, the pressure in the first reaction cavity is controlled at 0.6torr, the flow of supply of SiH4 silane in the first reaction cavity is controlled at 1000sccm, the radio frequency power W1 is 500W when a radio frequency chemical vapor deposition method is adopted, the deposition rate is controlled at 0.7nm/s, and the deposition thickness is controlled at 2.2nm;

secondly, depositing to form a second intrinsic amorphous silicon film layer in a first reaction cavity by taking silane as a reaction gas source, wherein in the deposition process of the second intrinsic amorphous silicon film layer, the temperature in the first reaction cavity is controlled at 200 ℃, the pressure in the first reaction cavity is controlled at 0.5torr, the flow of supply of SiH4 in the first reaction cavity is controlled at 1000sccm, the radio frequency power W2 is 250W when a radio frequency chemical vapor deposition method is adopted, the deposition rate is controlled at 0.2nm/s, and the deposition thickness is controlled at 1.2nm; after the deposition of the second intrinsic amorphous silicon film layer is finished, the radio frequency source in the first reaction cavity needs to be closed, and then the silicon wafer substrate is transferred into the second reaction cavity to continue deposition molding;

and finally, depositing and forming a third intrinsic amorphous silicon film layer in the second reaction cavity, wherein the temperature in the second reaction cavity is controlled to be 200 ℃ and the pressure in the second reaction cavity is controlled to be 0.6torr during deposition of the third intrinsic amorphous silicon film layer, and a reaction gas source in the second reaction cavity is a mixed gas of silane and hydrogen, wherein the mixing ratio of silane to hydrogen is SiH4/H2=500:1000, when the third intrinsic amorphous silicon film layer is deposited, the radio frequency power W3 is 150W when the radio frequency chemical vapor deposition method is adopted, the deposition rate is controlled to be 0.1nm/s, and the deposition thickness is controlled to be 4.2nm.

The specific protocol for comparative experiment 1 is as follows:

firstly, depositing a first film layer in a first reaction cavity by taking silane as a reaction gas source, wherein the temperature in the first reaction cavity is controlled at 200 ℃, the pressure in the first reaction cavity is controlled at 0.6torr, the flow rate of SiH4 supplied in the first reaction cavity is controlled at 1000sccm, the radio frequency power is controlled at 500W by adopting a radio frequency chemical vapor deposition method, the deposition rate is controlled at 0.7nm/s, and the deposition thickness is controlled at 2.2nm;

then, depositing a second film layer in a second reaction chamber by using a mixed gas of silane and hydrogen as a reaction gas source, wherein in the deposition process of the second film layer, the temperature in the second reaction chamber is controlled at 200 ℃, the pressure in the second reaction chamber is controlled at 0.6torr, and the mixing ratio of silane and hydrogen in the reaction gas source in the second reaction chamber is SiH4/H2=500:1000, when the radio frequency chemical vapor deposition method is adopted, the radio frequency power is 150W, the deposition rate is controlled to be 0.1nm/s, and the deposition thickness is controlled to be 5.4nm.

The specific protocol for comparative experiment 2 is as follows:

depositing and forming an intrinsic amorphous silicon film in a second reaction cavity, wherein the temperature of the intrinsic amorphous silicon film during deposition and forming is controlled at 200 ℃, the pressure of the intrinsic amorphous silicon film during deposition and forming is controlled at 0.6torr, and the reaction gas supplied in the second reaction cavity during deposition of the intrinsic amorphous silicon film is a mixed gas of silane and hydrogen, wherein the mixing ratio of the silane to the hydrogen is SiH4/H2=500:500, the radio frequency power of the radio frequency source is controlled at 200W when the intrinsic amorphous silicon film is deposited, the deposition rate is controlled at 0.15nm/s, and the thickness is controlled at 5.4nm.

In order to verify the benefit of example 1, the cell sheets having the intrinsic amorphous silicon thin films of example 1, comparative experiment 1 and comparative experiment 2 were subjected to the test of relevant parameters, and the test results are as follows:

	Voc(mV)	Isc(A)	FF(％)	Rs(mΩ)	Rsh(Ω)	EFF
							example 1	745.4	6.360	84.94	1.70	2433.2	24.31％
Comparative experiment 1	743.9	6.363	84.74	1.81	2433.8	24.22％
							Comparative experiment 2	743.7	6.356	84.44	1.68	2368.8	24.10％

The test result shows that:

for the open circuit voltage (Voc) of the cell, the cell using the intrinsic amorphous silicon thin film of example 1 was raised by 1.5mV compared to the cell using the intrinsic amorphous silicon thin film of comparative experiment 1, and by 1.7mV compared to the cell using the intrinsic amorphous silicon thin film of comparative experiment 2;

for the Fill Factor (FF), the cell using the intrinsic amorphous silicon thin film of example 1 was improved by 0.2% compared to the cell using the intrinsic amorphous silicon thin film of comparative experiment 1, and the cell using the intrinsic amorphous silicon thin film of example 1 was improved by 0.5% compared to the cell using the intrinsic amorphous silicon thin film of comparative experiment 2;

for the conversion Efficiency (EFF), the cell sheet using the intrinsic amorphous silicon thin film of example 1 was improved by 0.09% compared to the cell sheet using the intrinsic amorphous silicon thin film of comparative experiment 1, and the cell sheet using the intrinsic amorphous silicon thin film of example 1 was improved by 0.21% compared to the cell sheet using the intrinsic amorphous silicon thin film of comparative experiment 2.

Therefore, the amorphous silicon thin film formed by deposition by the method disclosed by the embodiment of the application has a good passivation effect, the open-circuit voltage of the cell with the intrinsic amorphous silicon thin film is greatly improved, the Filling Factor (FF) and the conversion Efficiency (EFF) of the cell are greatly improved, and the service efficiency of the cell is improved.

As shown in fig. 2, the invention also discloses a battery preparation method, which comprises the following steps:

providing an N-type silicon wafer substrate, and texturing and cleaning the N-type silicon wafer substrate;

respectively depositing and forming an upper intrinsic amorphous silicon film and a lower intrinsic amorphous silicon film on the upper side and the lower side of the N-type silicon wafer substrate by adopting the method for depositing the intrinsic amorphous silicon film by the PECVD method;

depositing and forming an N-type doped layer on the upper side of the upper intrinsic amorphous silicon film;

depositing and molding a P-type doping layer on the lower side of the lower intrinsic amorphous silicon film;

a light-transmitting conducting layer is respectively arranged on the lower side of the P-type doping layer and the upper side of the N-type doping layer;

and forming an electrode on the light-transmitting conductive layer.

As shown in fig. 1, another embodiment of the present invention also discloses a heterojunction battery comprising:

an N-type silicon wafer substrate;

the upper intrinsic amorphous silicon film and the lower intrinsic amorphous silicon film are arranged on the upper side and the lower side of the N-type silicon wafer substrate;

the P-type doping layer is arranged on the lower side of the lower intrinsic amorphous silicon film;

the N-type doping layer is arranged on the upper side of the upper intrinsic amorphous silicon film layer;

the light-transmitting conducting layer is arranged on the upper side of the N-type doping layer and the lower side of the P-type doping layer;

and the electrode is arranged on the light-transmitting conductive layer and is electrically connected with the light-transmitting conductive layer.

The construction, features and functions of the present invention are described in detail in the embodiments illustrated in the drawings, which are only preferred embodiments of the present invention, but the present invention is not limited by the drawings, and all equivalent embodiments modified or changed according to the idea of the present invention should fall within the protection scope of the present invention without departing from the spirit of the present invention covered by the description and the drawings.

Claims (9)

1. A method for depositing an intrinsic amorphous silicon film by a PECVD method is characterized by comprising the following steps:

taking silane as a reaction gas, and sequentially depositing a first intrinsic amorphous silicon film layer and a second intrinsic amorphous silicon film layer on a silicon wafer substrate, wherein the deposition rate V1 of the first intrinsic amorphous silicon film layer during deposition is 0.4nm/s-1.2nm/s; the radio frequency power W2 when the second intrinsic amorphous silicon film layer is deposited is smaller than the radio frequency power W1 when the first intrinsic amorphous silicon film layer is deposited;

and depositing and forming a third intrinsic amorphous silicon film layer on the second intrinsic amorphous silicon film layer by taking the mixed gas of silane and hydrogen as a reaction gas.

2. The method of depositing intrinsic amorphous silicon thin film according to the PECVD method of claim 1, wherein: the difference delta W between the radio frequency power W2 when the second intrinsic amorphous silicon film layer is deposited and the radio frequency power W1 when the first intrinsic amorphous silicon film layer is deposited is not more than 600W.

3. The method of claim 1 for depositing an intrinsic amorphous silicon thin film by the PECVD method, wherein: the first intrinsic amorphous silicon film layer and the second intrinsic amorphous silicon film layer are deposited and formed in the first reaction cavity, and the pressure in the first reaction cavity is reduced when the second intrinsic amorphous silicon film layer is deposited.

4. The method of depositing intrinsic amorphous silicon thin film according to the PECVD method of claim 1, wherein: the deposition rate V3 of the third intrinsic amorphous silicon film layer is less than V1; the deposition rate V3 of the third intrinsic amorphous silicon film layer is between 0.03nm/s and 0.3 nm/s.

5. The method of depositing intrinsic amorphous silicon thin film according to the PECVD method of claim 1, wherein: the thickness of the third intrinsic amorphous silicon film layer is larger than the sum of the thicknesses of the first intrinsic amorphous silicon film layer and the second intrinsic amorphous silicon film layer.

6. The method of claim 1 for depositing an intrinsic amorphous silicon thin film by the PECVD method, wherein: when the third intrinsic amorphous silicon film layer is deposited and formed, the ratio of silane/hydrogen in the mixed gas of silane and hydrogen is in the range of 5.

7. The method for depositing an intrinsic amorphous silicon thin film according to the PECVD method of claim 1,

the second intrinsic amorphous silicon film layer comprises a plurality of layers deposited on the first intrinsic amorphous silicon film layer in sequence, and the radio frequency power of the deposition of the plurality of layers is gradually reduced along with the deposition sequence and is smaller than that of the deposition of the first intrinsic amorphous silicon film layer.

8. A battery preparation method is characterized by comprising the following steps:

providing an N-type silicon wafer substrate, and texturing and cleaning the N-type silicon wafer substrate;

depositing an upper intrinsic amorphous silicon film and a lower intrinsic amorphous silicon film on the upper side and the lower side of an N-type silicon wafer substrate respectively by adopting the method for depositing the intrinsic amorphous silicon film by adopting the PECVD method as defined in any one of claims 1 to 7;

depositing and forming an N-type doped layer on the upper side of the upper intrinsic amorphous silicon film;

depositing and forming a P-type doped layer on the lower side of the lower intrinsic amorphous silicon film;

a light-transmitting conducting layer is respectively arranged on the lower side of the P-type doping layer and the upper side of the N-type doping layer;

and forming an electrode on the light-transmitting conductive layer.

9. A battery, comprising:

an N-type silicon wafer substrate;

the upper intrinsic amorphous silicon film and the lower intrinsic amorphous silicon film are arranged on the upper side and the lower side of the N-type silicon wafer substrate; the upper intrinsic amorphous silicon film layer and the lower intrinsic amorphous silicon film layer are deposited and formed by adopting the method for depositing the intrinsic amorphous silicon film by the PECVD method as claimed in any one of claims 1 to 7;

the P-type doping layer is arranged on the lower side of the lower intrinsic amorphous silicon film;

the N-type doping layer is arranged on the upper side of the upper intrinsic amorphous silicon film layer;

the light-transmitting conducting layer is arranged on the upper side of the N-type doping layer and the lower side of the P-type doping layer;

and the electrode is arranged on the light-transmitting conducting layer and is electrically connected with the light-transmitting conducting layer.

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