CN115513338B

CN115513338B - Passivation contact structure and preparation method thereof, application of passivation contact structure in window layer, solar cell and preparation method thereof, and photovoltaic module

Info

Publication number: CN115513338B
Application number: CN202211002612.5A
Authority: CN
Inventors: 陈皓
Original assignee: Longi Green Energy Technology Co Ltd
Current assignee: Longi Green Energy Technology Co Ltd
Priority date: 2022-08-19
Filing date: 2022-08-19
Publication date: 2024-08-02
Anticipated expiration: 2042-08-19
Also published as: CN115513338A

Abstract

The invention provides a passivation contact structure, a preparation method thereof, application of the passivation contact structure in a window layer, a solar cell, a preparation method thereof and a photovoltaic module, and relates to the technical field of crystal growth. The preparation method of the carbon-doped polysilicon comprises the following steps: in the process of vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer, carbon in-situ doping is carried out to obtain the conductive doped carbon doped amorphous silicon layer; and annealing the conductive doped and carbon-doped amorphous silicon layer to obtain the conductive doped and carbon-doped polycrystalline silicon layer. The vapor deposition conductive doped amorphous silicon layer, the carbon in-situ doping and annealing are low in process temperature, low in energy consumption and good in vapor deposition process controllability. The vapor deposition conductive doped amorphous silicon layer is good in junction type formed by annealing and high in doping efficiency. The carbon doping improves the band gap of the conductive doped amorphous silicon layer, the annealing further improves the band gap of the polycrystal, and the light transmittance of the polycrystal silicon is improved, so that the light irradiated on the silicon substrate is increased.

Description

Passivation contact structure and preparation method thereof, application of passivation contact structure in window layer, solar cell and preparation method thereof, and photovoltaic module

Technical Field

The invention relates to the technical field of crystal growth, in particular to a passivation contact structure, a preparation method thereof, application of the passivation contact structure in a window layer, a solar cell, a preparation method thereof and a photovoltaic module.

Background

Passivation contact structures including a tunneling layer and a polysilicon layer can provide excellent silicon interface passivation properties, and thus, are widely used in solar cells.

However, the existing preparation method of the passivation contact structure has the defects of overhigh process temperature, overlarge energy consumption, poor process controllability, poor junction type and low doping efficiency. And the polycrystalline silicon prepared by the method has strong light absorption, resulting in reduced light irradiated onto the silicon substrate.

Disclosure of Invention

The invention provides a passivation contact structure, a preparation method thereof, an application of the passivation contact structure in a solar cell window layer, a solar cell, a preparation method thereof and a photovoltaic module, and aims to solve the problems that the existing preparation method of the passivation contact structure is high in process temperature, high in energy consumption, poor in process controllability, poor in junction type, low in doping efficiency and strong in light absorption.

In a first aspect of the present invention, there is provided a method for preparing carbon-doped polysilicon, the method comprising:

In the process of vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer, carbon in-situ doping is carried out to obtain the conductive doped carbon doped amorphous silicon layer;

and annealing the conductive doped and carbon-doped amorphous silicon layer to obtain a conductive doped and carbon-doped polycrystalline silicon layer.

In the embodiment of the invention, in the process of preparing the conductive doped and carbon doped polycrystalline silicon layer, the vapor deposition conductive doped amorphous silicon layer, the carbon in-situ doping and annealing are relatively low in process temperature, low in energy consumption and good in vapor deposition process controllability. Meanwhile, the amorphous silicon layer is doped in a vapor deposition mode, and then the formed junction is good in annealing mode and high in doping efficiency. In the process of vapor deposition of the conductive doped amorphous silicon layer, carbon in-situ doping is performed, carbon doping improves the band gap of the conductive doped amorphous silicon layer, then annealing is performed to obtain a conductive doped and carbon doped polycrystalline silicon layer, the annealing process further improves the band gap of polycrystalline silicon and improves the light transmittance of the polycrystalline silicon, so that the light absorptivity of the conductive doped and carbon doped polycrystalline silicon layer is reduced, and light irradiated onto a silicon substrate is increased. And the resistance is reduced after carbon doping, and the conductivity of the conductive doped and carbon doped polysilicon layer is improved. Meanwhile, under the conditions of reducing the resistance and improving the light transmittance to about the same degree, compared with the doped polysilicon doped with other elements, the carbon doped polysilicon is more resistant to corrosion of an acid solution, the passivation performance is better, the service life of the passivation contact structure is longer, and the stability is better.

Optionally, in-situ doping of carbon is performed on the tunneling layer during vapor deposition of the conductive doped amorphous silicon layer, to obtain a conductive doped and carbon doped amorphous silicon layer, which includes:

In the process of vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer, gradually reducing the flow of a carbon source, and carrying out carbon in-situ doping to obtain the conductive doped amorphous silicon layer with reduced carbon doping concentration along the direction away from the tunneling layer;

And annealing the conductive doped and carbon-doped amorphous silicon layer to obtain a conductive doped and carbon-doped polycrystalline silicon layer, wherein the annealing comprises the following steps:

and annealing the conductive doped and carbon doped amorphous silicon layer with reduced carbon doping concentration along the direction away from the tunneling layer to obtain the conductive doped and carbon doped polycrystalline silicon layer with reduced carbon doping concentration along the direction away from the tunneling layer.

Optionally, in the process of vapor depositing the conductive doped amorphous silicon layer on the tunneling layer, reducing the flow of the carbon source gradually, and performing carbon in-situ doping to obtain the conductive doped and carbon doped amorphous silicon layer with reduced carbon doping concentration along the direction away from the tunneling layer, before the method further includes:

Performing oxygen in-situ doping in the process of vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer to obtain a conductive doped and oxygen doped first amorphous silicon film;

In the process of vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer, gradually reducing the flow of a carbon source, and performing carbon in-situ doping to obtain a conductive doped and carbon doped amorphous silicon layer with reduced carbon doping concentration along the direction away from the tunneling layer, wherein the method comprises the following steps:

gradually reducing the carbon source flow in the process of vapor deposition of the conductive doped amorphous silicon layer on the first amorphous silicon film, and carrying out carbon in-situ doping to obtain a conductive doped carbon doped second amorphous silicon film laminated on the first amorphous silicon film; wherein, in the second amorphous silicon film: the carbon doping concentration is reduced along the direction away from the tunneling layer;

And annealing the conductive doped and carbon doped amorphous silicon layer with reduced carbon doping concentration along the direction away from the tunneling layer to obtain a conductive doped and carbon doped polycrystalline silicon layer with reduced carbon doping concentration along the direction away from the tunneling layer, wherein the conductive doped and carbon doped polycrystalline silicon layer comprises the following components:

And annealing the first amorphous silicon film and the second amorphous silicon film which are stacked to obtain a first conductive doped and oxygen doped polysilicon film and a second conductive doped and carbon doped polysilicon film which are stacked.

Optionally, in the process of vapor depositing the conductive doped amorphous silicon layer on the tunneling layer, carbon in-situ doping is performed to obtain a conductive doped and carbon doped amorphous silicon layer, which includes:

In the process of vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer, increasing and then reducing the carbon source flow, and carrying out carbon in-situ doping to obtain the conductive doped and carbon doped amorphous silicon layer with the carbon doping concentration which is increased and then reduced along the direction away from the tunneling oxide layer;

and annealing the conductive doped and carbon doped amorphous silicon layer with the carbon doping concentration increased and reduced firstly along the direction away from the tunneling layer to obtain the conductive doped and carbon doped polycrystalline silicon layer with the carbon doping concentration increased and reduced secondly along the direction away from the tunneling layer.

Optionally, before the carbon in-situ doping is performed in the process of vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer to obtain the conductive doped and carbon doped amorphous silicon layer, the method further includes:

performing oxygen in-situ doping in the process of vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer to obtain a conductive doped and oxygen doped third amorphous silicon film;

And in-situ doping carbon is performed on the tunneling layer in the process of vapor deposition of the conductive doped amorphous silicon layer to obtain the conductive doped and carbon doped amorphous silicon layer, wherein the method comprises the following steps:

in-situ doping of carbon is carried out on the third amorphous silicon film in the process of vapor deposition of the conductive doped amorphous silicon layer, so as to obtain a fourth amorphous silicon film which is stacked on the third amorphous silicon film, is conductive doped and doped with carbon;

And annealing the third amorphous silicon film and the fourth amorphous silicon film which are stacked to obtain a third polysilicon film which is stacked and doped with conductive impurities and doped with oxygen and a fourth polysilicon film which is doped with conductive impurities and doped with carbon.

And in-situ doping of carbon is carried out on the tunneling layer in the process of conducting doping of the amorphous silicon layer by adopting the vapor deposition of the plasma enhanced chemistry, so that the conducting doped carbon doped amorphous silicon layer is obtained.

Optionally, during the vapor deposition of the plasma enhanced chemistry: the deposition air pressure is 20 to 90Pa, the power density of the radio frequency power source is 10 to 70mW/cm ², and the temperature is 100 to 250 ℃.

Optionally, in the process of vapor depositing the conductive doped amorphous silicon layer on the tunneling layer, gradually reducing the carbon source flow, and performing carbon in-situ doping to obtain a conductive doped and carbon doped amorphous silicon layer with reduced carbon doping concentration along the direction away from the tunneling layer, including:

And in the process of vapor deposition of the conductive doped amorphous silicon layer, silane is used as a silicon source, methane is used as a carbon source, hydrogen diluted phosphane is used as an N-type doping source, the flow ratio of the silicon source to the methane to the hydrogen diluted phosphane is kept at 100 (100 to 300): 2, carbon in-situ doping is carried out, then the flow ratio of the silicon source to the methane to the hydrogen diluted phosphane is kept at 100 (more than 0 and less than 100): 2, and the carbon in-situ doping is continuously carried out, so that the N-type carbon doped amorphous silicon layer with reduced carbon doping concentration along the direction far away from the tunneling layer is obtained.

Optionally, in the oxygen in-situ doping process, silane is used as a silicon source, carbon dioxide is used as an oxygen source, hydrogen diluted phosphane is used as an N-type doping source, the flow ratio of the silicon source to methane to the hydrogen diluted phosphane is kept at 100 (20-100): 2, and oxygen in-situ doping is carried out to obtain the N-type oxygen doped amorphous silicon film.

Optionally, the band gap of the conductive doped and carbon doped amorphous silicon layer is 1.8 to 2.0, and the light transmittance is greater than or equal to 85%.

Optionally, the annealing temperature is: the annealing time is 20 to 40 minutes at 800 to 900 ℃.

In a second aspect of the present invention, a passivation contact structure is provided, which is prepared by any one of the aforementioned methods for preparing passivation contact structures.

In a third aspect of the present invention, there is provided an application of the passivation contact structure in a solar cell window layer.

Optionally, the band gap of the conductive doped carbon doped polysilicon layer is 2.0 to 2.2, the light transmittance is more than or equal to 87%, the conductivity Fang Zuxiao is more than 1kΩ, and the crystallization rate is more than 60%.

In a fourth aspect of the present invention, there is provided a method for manufacturing a solar cell, comprising:

By adopting any one of the preparation methods of the passivation contact structure, the passivation contact structure is formed on the light-facing surface of the silicon substrate; wherein the tunneling layer is closer to the silicon substrate than the conductively doped and carbon-doped polysilicon layer.

Optionally, after forming the passivation contact structure, the method further comprises:

Depositing a silicon nitride layer on the conductive doped carbon-doped polysilicon layer, and filling hydrogen into the conductive doped carbon-doped polysilicon layer in the process of depositing the silicon nitride layer;

and removing the silicon nitride layer by adopting acid.

Optionally, after removing the silicon nitride layer, a lifetime of minority carriers in the silicon substrate is greater than or equal to 3000 μs.

And forming a front TCO layer on the conductive doped carbon doped polysilicon layer.

Optionally, the forming a front TCO layer on the conductively doped and carbon doped polysilicon layer includes:

Depositing a first front TCO sub-layer on the conductively doped and carbon-doped polysilicon layer by atomic layer deposition;

And depositing a second front TCO sub-layer on the first front TCO sub-layer by physical vapor deposition or reactive plasma deposition.

Optionally, the thickness of the first front TCO sub-layer is 10 to 30nm;

The thickness of the second front-side TCO sub-layer is 50 to 90nm; the direction in which the thickness is located is parallel to the lamination direction of the silicon substrate and the tunneling layer.

Optionally, the first front TCO sub-layer is: AZO film of [ ZnO ] _n[Al₂O₃]_m, wherein n: m is: (100:1) to (100:5);

the sheet resistance of the first front TCO sub-layer is as follows: 500 to 1000 Ω, mobility: 5 to 10cm ²/(v·s), carrier concentration: 2X 10 ¹⁹/cm³ to 6X 10 ¹⁹/cm³.

Optionally, the method further comprises: sequentially forming a back passivation layer and a back doping layer on the backlight surface of the silicon substrate; the back doped layer and the conductively doped and carbon doped polysilicon layer have different conductive doping types; a backside TCO layer is formed on the backside doped layer.

In a fifth aspect of the present invention, a solar cell is provided, which is prepared by any one of the aforementioned methods for preparing a solar cell.

Optionally, the tunneling layer and the conductively doped and carbon-doped polysilicon layer both cover the entire light-facing surface of the silicon substrate.

Optionally, the solar cell further includes: the front electrode is contacted with the conductive doped carbon-doped polycrystalline silicon layer, and the tunneling layer and the conductive doped carbon-doped polycrystalline silicon layer partially cover the whole light facing surface of the silicon substrate; the projection of the conductively doped and carbon-doped polysilicon layer onto the light-facing surface of the silicon substrate and the projection of the front electrode onto the light-facing surface of the silicon substrate have overlapping regions.

Optionally, the front TCO layer has an opening through which the front electrode is in contact with the conductively doped and carbon doped polysilicon layer.

In a sixth aspect of the present invention, a photovoltaic module is provided, comprising a string of solar cells formed by a plurality of solar cells as described above connected in series.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments of the present invention will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a flow chart showing the steps of a method for fabricating a passivation contact structure in an embodiment of the invention;

fig. 2 is a schematic diagram showing a manufacturing process structure of a first solar cell according to an embodiment of the present invention;

FIG. 3 is a schematic diagram showing a manufacturing process of a second solar cell according to an embodiment of the present invention;

fig. 4 is a schematic diagram showing a structure of a manufacturing process of a third solar cell according to an embodiment of the present invention;

fig. 5 is a schematic diagram showing a manufacturing process structure of a fourth solar cell according to an embodiment of the present invention;

fig. 6 is a schematic diagram showing a structure of a manufacturing process of a fifth solar cell in the embodiment of the present invention;

fig. 7 is a schematic view showing a structure of a manufacturing process of a fifth solar cell in the embodiment of the present invention;

fig. 8 is a schematic view showing a manufacturing process structure of a sixth solar cell according to an embodiment of the present invention;

fig. 9 is a schematic view showing a structure of a manufacturing process of a seventh solar cell in the embodiment of the present invention;

fig. 10 shows a schematic structural diagram of a solar cell in an embodiment of the present invention.

Reference numerals illustrate:

1-silicon substrate, 2-tunneling layer, 3-conductively doped and carbon-doped amorphous silicon layer, 4-conductively doped and carbon-doped polysilicon layer, 5-silicon nitride layer, 6-back passivation layer, 7-back doped layer, 8-front TCO layer 8, 9-back TCO layer, 10-front electrode, 11-back electrode.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The inventor discovers that the existing preparation method of the passivation contact structure has the defects of overhigh process temperature, overlarge energy consumption, poor process controllability, poor junction type and low doping efficiency, and the main reasons are as follows: in the prior art, the preparation of the polysilicon layer is obtained by diffusing on the basis of intrinsic polysilicon. However, the diffusion process is usually too high in temperature, too high in energy consumption, poor in process controllability, poor in junction type and low in doping efficiency.

Fig. 1 shows a flow chart of steps of a method for manufacturing a passivation contact structure in an embodiment of the invention. Referring to fig. 1, in order to solve the above problems, the passivation contact structure manufacturing method includes the steps of:

and step 101, performing carbon in-situ doping in the process of vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer to obtain the conductive doped and carbon doped amorphous silicon layer.

And 102, annealing the conductive doped and carbon-doped amorphous silicon layer to obtain a conductive doped and carbon-doped polycrystalline silicon layer.

Note that, the material, the preparation method, and the like of the tunneling layer are not particularly limited. For example, the tunneling layer may be a tunneling oxide layer, and the preparation method of the tunneling oxide layer may be a thermal oxidation method or the like.

Optionally, the step 101 may include: and in the process of vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer, gradually reducing the flow of a carbon source, and carrying out carbon in-situ doping to obtain the conductive doped and carbon doped amorphous silicon layer with reduced carbon doping concentration along the direction away from the tunneling layer. The step 102 may include: and annealing the conductive doped and carbon doped amorphous silicon layer with reduced carbon concentration along the direction away from the tunneling layer to obtain the conductive doped and carbon doped polycrystalline silicon layer with reduced carbon concentration along the direction away from the tunneling layer.

Specifically, after carbon doping, the acid resistance of the polysilicon layer is reduced, and the higher the carbon doping concentration is, the more the acid resistance of the polysilicon layer is reduced, but the better the conductivity and the light transmittance are. The polysilicon layer is usually located at the edge or end of the passivation contact structure, and is contacted with the outside first, and the carbon doping concentration is reduced along the direction away from the tunneling layer, that is, the carbon doping concentration of the portion of the polysilicon layer located inside the passivation contact structure is higher, so that the conductivity and light transmittance of the polysilicon layer are better, the carbon doping concentration of the end of the passivation contact structure is smaller, and the acid resistance of the end of the passivation contact structure is still better. In summary, the end part of the passivation contact structure is still better in acid resistance, better in passivation performance, longer in service life of the passivation contact structure and better in stability while the conductivity and the light transmittance of the polysilicon layer are ensured.

In the carbon in-situ doping process, the degree of reduction of the carbon source is not particularly limited, and the degree of reduction of the doping concentration in the polysilicon layer along the direction away from the tunneling layer is also not particularly limited. The carbon in-situ doping is carried out by gradually reducing the source of the carbon source, so that the conductive doped and carbon doped polycrystalline silicon layer with reduced carbon doping concentration is obtained along the direction away from the tunneling layer, and the process is simple and easy to control.

It should be noted that, in the whole process of performing carbon in-situ doping, as long as the carbon source flow is sequentially reduced at least twice, it is consistent with gradually reducing the carbon source flow. For example, throughout the carbon in-situ doping process, a first carbon source flow is used to perform carbon in-situ doping for a first preset period of time, and then a second carbon source flow smaller than the first carbon source flow is used to perform carbon in-situ doping until the carbon source doping is completed, so that the carbon source flow is gradually reduced. The flow rate of the first carbon source is greater than that of the second carbon source, and is not limited. The magnitude relationship between the first predetermined duration and the duration of the carbon in-situ doping with the second carbon source flow is also not particularly limited.

Optionally, in the process of vapor depositing the conductive doped amorphous silicon layer on the tunneling layer, the carbon source flow is gradually reduced, and carbon in-situ doping is performed to obtain a conductive doped and carbon doped amorphous silicon layer with reduced carbon doping concentration along a direction away from the tunneling layer, including: in the process of vapor deposition of the conductive doped amorphous silicon layer, silane is used as a silicon source, methane is used as a carbon source, hydrogen diluted phosphane is used as an N-type doped source, the flow ratio of the silicon source to the methane to the hydrogen diluted phosphane is kept at 100 (100 to 300): 2, carbon in-situ doping is carried out, then the flow ratio of the silicon source to the methane to the hydrogen diluted phosphane is kept at 100 (more than 0 and less than 100): 2, and the carbon in-situ doping is continuously carried out, so that the N-type carbon doped amorphous silicon layer with reduced carbon doping concentration along the direction far away from the tunneling layer is obtained. That is, in the process of vapor deposition of the conductive doped amorphous silicon layer, the flow rates of the silicon source and the N-type doped source can be kept unchanged, only the flow rate of the carbon source is reduced, and the N-type carbon doped amorphous silicon layer with reduced carbon doping concentration along the direction away from the tunneling layer is obtained. The silicon source, the carbon source and the N-type doping source are easy to obtain, the cost is low, and the performances of conductivity, light transmittance and the like of the N-type carbon-doped amorphous silicon layer obtained by doping according to the flow ratio are good.

For example, the carbon in-situ doping may be performed by maintaining the flow ratio of methane to hydrogen diluted phosphane at one of 100:300:2、100:280:2、 100:250:2、100:240:2、100:220:2、100:200:2、100:180:2、100:150:2、100:120:2、 100:100:2, and then continuing the carbon in-situ doping by maintaining the flow ratio of methane to hydrogen diluted phosphane at one of 100:99:2、100:88:2、100:83:2、100:80:2、100:75:2、100:60:2、100:55:2、 100:50:2、100:46:2、100:42:2、100:30:2、100:20:2、100:10:2、100:6:2.

Optionally, the step 101 may include: and in the process of vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer, increasing and then reducing the carbon source flow, and carrying out carbon in-situ doping to obtain the conductive doped and carbon doped amorphous silicon layer with the carbon doping concentration increased and then reduced along the direction away from the tunneling layer. The step 102 may include: and annealing the conductive doped and carbon doped amorphous silicon layer with the carbon doping concentration increased and then reduced along the direction away from the tunneling layer to obtain the conductive doped and carbon doped polycrystalline silicon layer with the carbon doping concentration increased and then reduced along the direction away from the tunneling layer.

Specifically, after carbon doping, the acid resistance of the polysilicon layer is reduced, and the higher the carbon doping concentration is, the more the acid resistance of the polysilicon layer is reduced, but the better the conductivity and the light transmittance are. The polysilicon layer is usually located at the edge or end part of the passivation contact structure, and is contacted with the outside first, and the carbon doping concentration is increased and then reduced along the direction away from the tunneling layer, that is, the carbon doping concentration of the portion of the polysilicon layer located inside the passivation contact structure is higher, so that the conductivity and the light transmittance of the polysilicon layer are better, the carbon doping concentration of the end part of the polysilicon layer located inside the passivation contact structure is smaller, and the acid resistance of the end part of the passivation contact structure is still better. In summary, the end part of the passivation contact structure is still better in acid resistance, better in passivation performance, longer in service life of the passivation contact structure and better in stability while the conductivity and the light transmittance of the polysilicon layer are ensured.

In the carbon in-situ doping process, the degree of increasing and decreasing the carbon source is not particularly limited, and the degree of increasing and decreasing the carbon doping concentration in the polysilicon layer along the direction away from the tunneling layer is also not particularly limited. The carbon in-situ doping is carried out by increasing and then reducing the carbon source flow, so that the conductive doped and carbon doped polysilicon layer with the carbon doping concentration which is increased and then reduced along the direction far away from the tunneling layer is obtained, and the process is simple and easy to control.

In the whole process of carbon in-situ doping, the carbon source flow rate is increased at least once compared with the carbon source flow rate just started, and then the carbon source flow rate is decreased at least once compared with the carbon source flow rate after the carbon source flow rate is increased. For example, throughout the carbon in-situ doping process, carbon in-situ doping with a first carbon source flow is started for a first preset period of time, then carbon in-situ doping with a second carbon source flow greater than the first carbon source flow is performed for a second preset period of time, and then in-situ doping with a third carbon source flow less than the second carbon source flow is performed until the carbon source doping is completed, so that the carbon source flow is increased and then reduced. The flow rate of the first carbon source is smaller than the flow rate of the second carbon source, the flow rate of the third carbon source is smaller than the flow rate of the second carbon source, and the relative sizes of the first carbon source and the third carbon source are not limited. The magnitude relation of the first preset duration, the second preset duration, and the duration of carbon in-situ doping with the third carbon source flow is also not particularly limited.

In the process of vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer, the carbon source flow is increased and then reduced, carbon in-situ doping is performed, the conductive doped and carbon doped amorphous silicon layer with the carbon doping concentration increased and then reduced along the direction far away from the tunneling layer is obtained, and finally, the conductive doped and carbon doped polycrystalline silicon layer with the carbon doping concentration increased and then reduced is obtained, and in the direction far away from the tunneling layer, the carbon doping concentration of two sides of the polycrystalline silicon layer is smaller, the carbon doping concentration of the middle part is higher, and the contact recombination can be improved.

Optionally, in the process of vapor depositing the conductive doped amorphous silicon layer on the tunneling layer, gradually reducing the flow of the carbon source, and performing carbon in-situ doping to obtain the conductive doped and carbon doped amorphous silicon layer with reduced carbon doping concentration along the direction away from the tunneling layer, and before the method further comprises: and in the process of vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer, performing oxygen in-situ doping to obtain a conductive doped and oxygen doped first amorphous silicon film. In the process of vapor deposition of a conductive doped amorphous silicon layer on a tunneling layer, gradually reducing the flow of a carbon source, and carrying out carbon in-situ doping to obtain the conductive doped and carbon doped amorphous silicon layer with reduced carbon doping concentration along the direction away from the tunneling layer, wherein the method comprises the following steps: and in the process of vapor deposition of the conductive doped amorphous silicon layer on the first amorphous silicon film, gradually reducing the flow of a carbon source, and carrying out carbon in-situ doping to obtain a conductive doped and carbon doped second amorphous silicon film laminated on the first amorphous silicon film. Wherein, in the second amorphous silicon film: the doping concentration decreases in a direction away from the tunneling layer. The annealing includes: and annealing the first amorphous silicon film and the second amorphous silicon film which are stacked to obtain a conductive doped and carbon doped second polysilicon film and a conductive doped and oxygen doped first polysilicon film which are stacked.

Specifically, in the process of vapor deposition of a conductive doped amorphous silicon layer on a tunneling layer, firstly performing oxygen in-situ doping to obtain a conductive doped and oxygen doped first amorphous silicon film, then gradually reducing a carbon source flow in the process of continuing vapor deposition of the conductive doped amorphous silicon layer, and performing carbon in-situ doping on the first amorphous silicon film to obtain a conductive doped and carbon doped second amorphous silicon film and a conductive doped and oxygen doped first amorphous silicon film which are stacked; wherein, in the second amorphous silicon film which is conductive doped and doped with carbon: the doping concentration decreases in a direction away from the tunneling layer. And then annealing the first amorphous silicon film and the second amorphous silicon film which are stacked to obtain a conductive doped and carbon doped second polysilicon film and a conductive doped and oxygen doped first polysilicon film which are stacked. The conductivity and the light transmittance of the polycrystalline silicon can be improved by the oxygen doping, the conductivity and the light transmittance of the polycrystalline silicon are improved by the carbon doping and the oxygen doping, but after the oxygen doping, the acid resistance of the polycrystalline silicon layer is reduced to a degree which is larger than that of the polycrystalline silicon layer after the carbon doping, and the higher the carbon doping concentration is, the more the acid resistance of the polycrystalline silicon layer is reduced, in the passivation contact structure, the first polycrystalline silicon film which is conductive and doped with the oxygen is positioned between the tunneling layer and the second polycrystalline silicon film which is conductive and doped with the carbon doping, namely the first polycrystalline silicon film which is conductive and doped with the oxygen which is less resistant to an acidic solution is arranged in the middle of the passivation contact structure, the second polycrystalline silicon film which is conductive and doped with the carbon doping is positioned at the end part or the edge of the passivation contact structure, and the part with the low carbon doping concentration is closer to the end part or the edge of the passivation contact structure, and the end part of the passivation contact structure is still better in acid resistance, and even if the passivation contact structure is contacted with the acidic solution, the end part of the passivation contact structure is still better in acid resistance, and the passivation contact structure is still better in acid resistance and longer in service life. In summary, the end part of the passivation contact structure is still better in acid resistance, better in passivation performance, longer in service life of the passivation contact structure and better in stability while the conductivity and the light transmittance of the polysilicon layer are ensured. Through the carbon doping and oxygen doping of the polysilicon, the way for improving the conductivity and the light transmittance is more flexible and various. In the oxygen doping process, whether the oxygen source flow rate is changed is not particularly limited. For example, during oxygen doping, the oxygen source flow may remain unchanged, or the oxygen source flow may be gradually decreased, or the oxygen source flow may be gradually increased, or the oxygen source flow may be increased first and then decreased, etc.

Optionally, before the step 101, the method may further include: and (3) in-situ doping oxygen is carried out on the tunneling layer in the process of vapor deposition of the conductive doped amorphous silicon layer, so that the conductive doped and oxygen doped third amorphous silicon film is obtained. The step 101 may include: and in-situ doping carbon is carried out on the third amorphous silicon film in the process of vapor deposition of the conductive doped amorphous silicon layer, so that a fourth amorphous silicon film which is stacked on the third amorphous silicon film, conductive doped and carbon doped is obtained. The step 102 may include: and annealing the third amorphous silicon film and the fourth amorphous silicon film which are stacked to obtain a third polycrystalline silicon film which is stacked and doped with conductive impurities and doped with oxygen and a fourth polycrystalline silicon film which is conductive impurities and doped with carbon.

Specifically, in-situ doping of oxygen is performed firstly in the process of vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer to obtain a conductive doped and oxygen doped third amorphous silicon film, and then in-situ doping of carbon is performed on the third amorphous silicon film in the process of continuous vapor deposition of the conductive doped amorphous silicon layer to obtain a conductive doped and carbon doped fourth amorphous silicon film and a conductive doped and oxygen doped third amorphous silicon film which are stacked. And then annealing the third amorphous silicon film and the fourth amorphous silicon film which are stacked to obtain a fourth polysilicon film which is stacked and doped with conductive impurities and doped with carbon and a third polysilicon film which is doped with conductive impurities and doped with oxygen. The conductivity and the light transmittance of the polycrystalline silicon can be improved by the oxygen doping, the conductivity and the light transmittance of the polycrystalline silicon are improved by the carbon doping and the oxygen doping, but after the oxygen doping, the acid resistance of the polycrystalline silicon layer is reduced to a degree which is larger than that of the polycrystalline silicon layer after the carbon doping, in the passivation contact structure, the third polycrystalline silicon film which is conductive doped and oxygen doped is positioned between the tunneling layer and the fourth polycrystalline silicon film which is conductive doped and carbon doped, namely the third polycrystalline silicon film which is less resistant to an acid solution is arranged in the middle of the passivation contact structure, the fourth polycrystalline silicon film which is conductive doped and carbon doped and is resistant to an acid solution is arranged at the edge or the end of the passivation contact structure, the acid resistance of the end of the passivation contact structure is still better, and even if the passivation contact structure is contacted with the acid solution, the end of the passivation contact structure is the fourth polycrystalline silicon film which is conductive doped and carbon doped, the acid resistance of the end of the passivation contact structure is still better, the passivation contact structure is still longer in service life, and the passivation contact structure is still longer in service life. In summary, the end part of the passivation contact structure is still better in acid resistance, better in passivation performance, longer in service life of the passivation contact structure and better in stability while the conductivity and the light transmittance of the polysilicon layer are ensured. Through the carbon doping and oxygen doping of the polysilicon, the way for improving the conductivity and the light transmittance is more flexible and various.

Optionally, in the oxygen in-situ doping process, silane is used as a silicon source, carbon dioxide is used as an oxygen source, hydrogen diluted phosphane is used as an N-type doping source, the flow ratio of the silicon source to methane to hydrogen diluted phosphane is kept at 100 (20-100): 2, oxygen in-situ doping is carried out to obtain the N-type oxygen doped amorphous silicon film, the silicon source, the oxygen source and the N-type doping source are easy to obtain and low in cost, and the flow ratio of the silicon source, the oxygen source and the N-type doping source is in the range, so that the obtained N-type oxygen doped amorphous silicon film has better performances such as conductivity, passivation performance and light transmittance.

For example, in the oxygen in-situ doping process, silane is used as a silicon source, carbon dioxide is used as an oxygen source, hydrogen diluted phosphane is used as an N-type doping source, and the flow ratio of the silicon source to methane to hydrogen diluted phosphane is kept at one of 100:20:2、100: 30:2、100:40:2、100:50:2、100:55:2、100:60:2、100:65:2、100:70:2、100: 80:2、100:90:2、100:100:2, so that oxygen in-situ doping is performed to obtain the N-type oxygen doped amorphous silicon film.

Optionally, the step 101 may include: and in the process of conducting doping of the amorphous silicon layer by adopting PECVD (PLASMA ENHANCED CHEMICAL Vapor Deposition) on the tunneling layer, conducting carbon in-situ doping is carried out to obtain the conducting doped carbon doped amorphous silicon layer, and compared with other chemical Vapor Deposition large-point reference amorphous silicon layers, the conducting doped amorphous silicon layer is deposited by adopting a PECVD mode, the winding plating is less, the yield is higher, and the process is simpler.

Optionally, in the PECVD process: the deposition air pressure is 20 to 90Pa, the power density of the radio frequency power source is 10 to 70mW/cm ², and the temperature is 100 to 250 ℃. Under the process conditions, the obtained conductive doped and carbon doped amorphous silicon layer has better junction type and higher doping efficiency.

For example, in a plasma enhanced chemical vapor deposition process: the deposition air pressure can be one of 20Pa, 30Pa, 33Pa, 40Pa, 53Pa, 61Pa, 72Pa, 84Pa, and 90Pa, the power density of the radio frequency power source is one of 10mW/cm²、13mW/cm²、20mW/cm²、29mW/cm²、33mW/cm²、44mW/cm²、 55mW/cm²、60mW/cm²、70mW/cm², and the temperature is one of 100 ℃, 120 ℃, 160 ℃, 190 ℃, 200 ℃, 210 ℃, 230 ℃, 244 ℃ and 250 ℃.

Optionally, the band gap of the conductive doped and carbon doped amorphous silicon layer is 1.8 to 2.0, the light transmittance is greater than or equal to 85%, the band gap and the light transmittance are obviously improved after the carbon doped treatment, and further, the light absorptivity of the polysilicon is reduced, so that the light irradiated onto the silicon substrate is increased. For example, the band gap of the conductively doped and carbon doped amorphous silicon layer is one of 1.8, 1.82, 1.89, 1.9, 1.93, 1.94, 2.0, and the light transmittance is one of 85%, 87%, 89%, 90%, 93%, 95%, 97%. Optionally, the annealing temperature is: 800. the annealing time is 20 to 40 minutes at the temperature of 900 ℃, and the conductive doped and carbon doped polysilicon layer obtained under the annealing condition has excellent performances such as conductivity, light transmittance and the like. For example, the annealing temperature is 850 ℃, and the annealing time period is 30 minutes. For example, the annealing temperature is: 800 ℃, 820 ℃, 830 ℃, 840 ℃, 850 ℃, 855 ℃, 860 ℃, 870 ℃, 880 ℃, 900 ℃ for one of 20 minutes, 23 minutes, 29 minutes, 30 minutes, 32 minutes, 35 minutes, 40 minutes.

It should be noted that the tunneling layer may be prepared by using a thermal oxygen method or a wet method, and the specific forming method of the tunneling layer is not limited. The thickness of the tunneling layer may be about 1.5±1nm, and the direction in which the thickness is located is parallel to the lamination direction of the tunneling layer and the conductively doped and carbon doped polysilicon layer, and the definitions of the directions of the thicknesses mentioned throughout are defined as such. The thickness of the conductively doped and carbon doped polysilicon layer may be 20±10nm. For example, the thickness of the tunneling layer may be one of 0.5nm, 0.8nm, 1nm, 1.2nm, 1.5nm, 1.8nm, 1.9nm, 2.2nm, 2.4nm, 2.5 nm. For example, the thickness of the conductively doped and carbon doped polysilicon layer may be one of 10nm, 11nm, 12nm, 15nm, 18nm, 20nm, 22nm, 24nm, 25nm, 28nm, 30 nm.

The invention also provides a passivation contact structure, which is prepared by any one of the preparation methods of the passivation contact structure. The passivation contact structure has the same or similar beneficial effects as any of the aforementioned methods for preparing passivation contact structures, and in order to avoid repetition, the description thereof is omitted.

The invention also provides an application of any of the passivation contact structures in a solar cell window layer, wherein the solar cell window layer can be a part of a silicon substrate facing the light side. This application has the same or similar beneficial effects as any of the passivation contact structures described above, and is not repeated here.

Optionally, the band gap of the conductive doped and carbon doped polysilicon layer is 2.0 to 2.2, the light transmittance is greater than or equal to 87%, the conductivity Fang Zuxiao is greater than 1kΩ, the crystallization rate is greater than 60%, the service life of minority carriers in the conductive doped and carbon doped polysilicon layer is greater than or equal to 3000 μs, the band gap, the light transmittance and the conductivity of the conductive doped and carbon doped polysilicon layer are obviously improved by carbon doping, and the band gap, the light transmittance and the conductivity of the conductive doped and carbon doped polysilicon layer are further improved by annealing. For example, the band gap of the conductively doped and carbon doped polysilicon layer is one of 2.0, 2.02, 2.09, 2.1, 2.11, 2.15, 2.2, the light transmittance is one of 87%, 88%, 89%, 90%, 93%, 95%, 97%, 98%, the conductivity sheet resistance is one of 0.3kΩ, 0.34kΩ,0.4 kΩ,0.5 kΩ, 0.6kΩ, 0.7kΩ, 0.8kΩ, 0.9kΩ, and the crystallization rate is one of 61%, 63%, 67%, 69%, 73%, 79%, 82%, 85%, 90%.

The invention also provides a preparation method of the solar cell, which comprises the following steps:

Step S1, forming a passivation contact structure on a light-facing surface of a silicon substrate by adopting any one of the preparation methods of the passivation contact structure; wherein the tunneling layer is closer to the silicon substrate than the polysilicon layer.

Fig. 2 is a schematic diagram showing a manufacturing process structure of a first solar cell in an embodiment of the present invention. Fig. 3 is a schematic diagram showing a manufacturing process structure of a second solar cell according to an embodiment of the present invention. Fig. 4 is a schematic diagram showing a manufacturing process structure of a third solar cell according to an embodiment of the present invention. Fig. 5 is a schematic diagram showing a manufacturing process structure of a fourth solar cell according to an embodiment of the present invention. A tunneling layer 2 is formed on a silicon substrate as shown with reference to fig. 3. As shown in fig. 4, on the tunneling layer 2, a conductive doped and carbon doped amorphous silicon layer is formed based on any of the above-mentioned methods for manufacturing the passivation contact structure. Referring to fig. 5, after annealing the structure shown in fig. 4, the conductively doped and carbon-doped amorphous silicon layer 3 is converted into a conductively doped and carbon-doped polysilicon layer 4, forming a passivation contact structure. Referring to fig. 5, the tunneling layer 2 is closer to the silicon substrate 1 than the conductively doped and carbon-doped polysilicon layer 4.

The light-facing surface of the silicon substrate 1 is a surface of the silicon substrate 1 that mainly receives light in a solar cell or a photovoltaic module. The conductively doped and carbon-doped polysilicon layer 4 may form a high-low junction with the silicon substrate 1.

Optionally, as shown in fig. 2, before forming the passivation contact structure, the silicon substrate 1 may be cleaned and textured to obtain a double-sided pyramid suede structure.

Fig. 6 is a schematic diagram showing a manufacturing process structure of a fifth solar cell in the embodiment of the present invention. Fig. 7 is a schematic view showing a structure of a manufacturing process of a fifth solar cell in the embodiment of the present invention. Fig. 8 is a schematic view showing a manufacturing process structure of a sixth solar cell in the embodiment of the present invention. Fig. 9 is a schematic diagram showing a manufacturing process structure of a seventh solar cell in the embodiment of the present invention. Fig. 10 shows a schematic structural diagram of a solar cell in an embodiment of the present invention.

Optionally, referring to fig. 6, after forming the passivation contact structure, the method may further include: and depositing a silicon nitride layer 5 on the conductive doped and carbon-doped polysilicon layer 4, and filling hydrogen into the conductive doped and carbon-doped polysilicon layer 4 in the process of depositing the silicon nitride layer 5, so that the passivation performance of the conductive doped and carbon-doped polysilicon layer 4 is further improved. Referring to fig. 7, the silicon nitride layer 5 is removed using an acid. In the invention, hydrogen is filled into the conductive doped and carbon doped polysilicon layer 4 in the process of depositing the silicon nitride layer 5, so that the passivation performance of the conductive doped and carbon doped polysilicon layer 4 is further improved, but the silicon nitride layer 5 is non-conductive, if not removed, the front electrode positioned on one side of the passivation contact structure of the silicon substrate 1 at least needs to form ohmic contact with the conductive doped and carbon doped polysilicon layer 4, so that high temperature burning through the silicon nitride layer 5 is needed, on one hand, the front electrode of metal and the conductive doped and carbon doped polysilicon layer 4 are directly in ohmic contact, the passivation quality is reduced, on the other hand, the high temperature burning through the silicon nitride layer 5 brings larger thermal influence to other parts of the solar cell, and the working procedure of setting the electrode is more back, most parts of the solar cell are possibly influenced, so that more other parts of the solar cell are possibly invalid. Moreover, the portion of the conductive doped and carbon doped polysilicon layer 4 away from the tunneling layer 2 is carbon doped, further, the portion of the conductive doped and carbon doped polysilicon layer 4 away from the tunneling layer 2 has a lower carbon doping concentration than other portions, the carbon doping is more resistant to acidic solution than oxygen doping, and the lower the carbon doping concentration is, the more resistant to acidic solution, whereas the portion of the conductive doped and carbon doped polysilicon layer 4 away from the tunneling layer 2 is the portion of the conductive doped and carbon doped polysilicon layer 4 near the silicon nitride layer 5, and the acid is less corrosive to the conductive doped and carbon doped polysilicon layer 4 during removal of the silicon nitride layer 5 by using the acid, and the conductive doped and carbon doped polysilicon layer 4 or passivation contact structure is not substantially corroded by the acid herein, or has a very low degree of corrosion. For example, in the present invention, the minority carrier lifetime in the silicon substrate 1 is not substantially changed before and after the silicon nitride layer 5 is removed using an acid. Minority carriers are related according to the doping type of the silicon substrate 1, and are holes if the silicon substrate 1 is an N-type silicon substrate, and electrons if the silicon substrate 1 is a P-type silicon substrate.

For example, if the silicon nitride layer 5 is not removed, the temperature of the high-temperature burn-through silicon nitride layer 5 is generally greater than 800 ℃, and if the step of disposing the electrode is further followed by the step of disposing the amorphous silicon passivation layer, the step of disposing the electrode is positioned after disposing the amorphous silicon passivation layer, and the failure temperature of the amorphous silicon passivation layer is about 300 ℃, the burn-through temperature of the high-temperature burn-through silicon nitride layer 5 is far greater than the failure temperature of the amorphous silicon passivation layer, which may result in failure of the amorphous silicon passivation layer.

Alternatively, the thickness of the silicon nitride layer 5 is 30±10nm, the acid used for removing the silicon nitride layer 5 may be HF, specifically, the silicon substrate 1 on which the silicon nitride layer 5 is formed is immersed in HF for about 2 minutes, the silicon nitride layer 5 is removed, and the silicon dioxide layer 2 possibly on the back surface of the silicon substrate 1 is removed. For example, the thickness of the silicon nitride layer 5 may be one of 20nm, 21nm, 22nm, 25nm, 28nm, 30nm, 32nm, 34nm, 35nm, 38nm, 40 nm.

Optionally, hydrogen is filled into the conductive doped and carbon doped polysilicon layer 4 during the deposition of the silicon nitride layer 5, so that the passivation performance of the conductive doped and carbon doped polysilicon layer 4 is further improved, and then the minority carrier lifetime in the silicon substrate 1 is greater than or equal to 3000 μs (microseconds) after the removal of the silicon nitride layer 5 with acid, and the passivation performance of the passivation contact structure is excellent. For example, before depositing the silicon nitride layer 5, the lifetime of minority carriers in the silicon substrate 1 is about 1000 μs, and after removing the silicon nitride layer 5, the lifetime of minority carriers in the silicon substrate 1 is greater than or equal to 3000 μs, so that passivation performance optimization of the passivation contact structure is obvious.

Optionally, referring to fig. 9, after forming the passivation contact structure, the method may further include: a front TCO layer 8 is formed on the conductively doped and carbon doped polysilicon layer 4, the front TCO layer 8 providing suitable band adaptation and thus improved photoelectric conversion efficiency.

Optionally, the forming the front TCO layer 8 may include: a first front TCO sub-layer is deposited on the conductively doped and carbon-doped polysilicon layer 4 using ALD (Atomic layer Deposition ), and a second front TCO sub-layer is deposited on the first front TCO sub-layer using PVD (Physical Vapor Deposition ) or RPD (REACTIVE PLASMA Deposition). Specifically, the ALD method is used to deposit the first front TCO sub-layer on the conductively doped and carbon doped polysilicon layer 4, so that the ALD method has less bombardment on the conductively doped and carbon doped polysilicon layer 4, and damage or influence on the conductively doped and carbon doped polysilicon layer 4 is reduced compared with other deposition methods. And then, depositing a second front TCO sub-layer on the first front TCO sub-layer by adopting PVD or RPD, wherein the PVD or RPD bombards the first front TCO sub-layer more greatly, but the formed second front TCO sub-layer has better film quality, good electric conduction performance and smaller resistance, so that the bombarding degree of the PVD or RPD on the first front TCO sub-layer is not particularly limited, and the effect of the first front TCO sub-layer is equivalent to the bombarding effect of the PVD or RPD. In the final solar cell, the presence or absence of the first front TCO sub-layer is not limited.

For example, if the front TCO layer 8 is formed directly by PVD or RPD, the minority carrier lifetime in the silicon substrate 1 may drop from 3000 μs to below 1000 μs. However, in the present invention, the first front TCO sub-layer deposited by ALD is used to carry the bombardment effect of PVD or RPD, and the lifetime of minority carriers in the silicon substrate 1 is still around 3000 μs before and after forming the front TCO layer 8.

Optionally, the thickness of the first front TCO sub-layer is 10 to 30nm, the thickness of the second front TCO sub-layer is 50 to 90nm, and the direction in which the thickness is located is parallel to the stacking direction of the silicon substrate 1 and the tunneling layer 2. The thickness of the first front TCO sub-layer is in the range, the bombardment effect of PVD or RPD can be well born, the first front TCO sub-layer basically does not remain due to the bombardment effect of PVD or RPD, and the thickness of the second front TCO sub-layer is in the range, so that the electric conduction performance and the like are better. More specifically, if the thickness of the first front TCO sub-layer is less than 10nm, the first front TCO sub-layer cannot fully withstand the bombardment effect of PVD or RPD, and if the thickness of the first front TCO sub-layer is greater than 30nm, the first front TCO sub-layer still has more residues after the bombardment, but the film quality of the first front TCO sub-layer is different from that of the second front TCO sub-layer formed by PVD or RPD, which results in slightly reduced film quality of the final front TCO layer 8 and increases the cell string resistance.

For example, the first front TCO sublayer may have a thickness of one of 10nm, 12nm, 16nm, 18nm, 20nm, 23nm, 25nm, 30 nm. For example, the second front TCO layer can have a thickness of one of 50nm, 62nm, 66nm, 68nm, 70nm, 71nm, 73nm, 80nm, 90 nm.

Optionally, in the process of depositing the first front TCO sub-layer on the conductive doped and carbon doped polysilicon layer 4 by ALD, the temperature of the cavity of the ALD furnace tube may be controlled to be 150 to 250 ℃, the pressure of the cavity is 500 to 3000mtorr (micro-meter hg), the precursor DEZ (diethyl zinc) is sequentially introduced, the duration of introduction is 0.5 to 3s, the furnace tube is vacuumized, the N ₂ O gas is introduced, the duration of introduction is 0.5 to 3s, and the furnace tube is vacuumized as one cycle of ZnO deposition. Sequentially introducing a precursor TMA (trimethylaluminum), introducing the precursor TMA for 0.5 to 3s, vacuumizing a furnace tube, introducing H ₂ gas, introducing the precursor TMA for 0.5 to 3s, vacuumizing the furnace tube, and taking the precursor TMA as one cycle of Al ₂O₃ deposition, and obtaining the doped AZO film of [ ZnO ] _n[Al₂O₃]_m through the above cycles, wherein n: m is in the range of (100:1) to (100:5), the thickness of the formed aluminum-doped zinc oxide film is controlled to be in the range of 10 to 30nm, the sheet resistance is controlled to be 500 to 1000 omega, the mobility is controlled to be 5 to 10cm ²/(V.s), and the carrier concentration is controlled to be 2X 10 ¹⁹/cm³ to 6X 10 ¹⁹/cm³. The first front TCO sub-layer obtained under the preparation condition has better bearing capacity for the bombardment effect of PVD or RPD.

For example, during the deposition of the first front-side TCO sub-layer on the conductively doped and carbon doped polysilicon layer 4 by ALD, the ALD furnace tube cavity temperature may be controlled to be one of 150 ℃, 160 ℃, 180 ℃, 190 ℃,200 ℃, 210 ℃, 220 ℃, 23 ℃, 250 ℃, the pressure being one of 500mtorr, 600mtorr, 700mtorr, 900mtorr, 1500mtorr, 1800mtorr, 2000mtorr, 2500mtorr, 3000mtorr, the precursor DEZ (diethyl zinc) is sequentially introduced, the introduction time is one of 0.5s, 0.7s, 1s, 1.3s, 1.8s, 2s, 2.2s, 2.5s, 2.3 s, the furnace tube is evacuated, and N ₂ O gas is introduced, one of 0.5s, 0.7s, 1.3s, 1.8s, 2s, 2.2.2 s, 2.5s, 3 s. n: m is 100:1. 100:1.6, 100:2. 100:2.5, 100:2.9, 100: 3. 100: 4. 100: 5. The thickness of the formed aluminum-doped zinc oxide film is as follows: one of 10nm, 12nm, 16nm, 18nm, 20nm, 23nm, 25nm and 30nm, one of 500 Ω, 600 Ω, 700 Ω, 800 Ω, 900 Ω and 1000 Ω, one of 5cm²/(V·s)、6cm²/(V·s)、 7cm²/(V·s)、8cm²/(V·s)、9cm²/(V·s)、10cm²/(V·s) mobility, and one of ：2×10¹⁹/cm³、2.3×10¹⁹/cm³、2.9×10¹⁹/cm³、3.2×10¹⁹/cm³、4×10¹⁹/cm³、 4.4×10¹⁹/cm³、5×10¹⁹/cm³、6×10¹⁹/cm³ carrier concentration.

Referring to fig. 8, optionally, after forming the passivation contact structure, the method may further include: a back passivation layer 6 and a back doped layer 7 are sequentially formed on the back surface of the silicon substrate 1, and the back doped layer 7 and the conductive doped and carbon doped polysilicon layer 4 have different conductive doping types. Referring to fig. 9, a rear TCO layer 9 is formed on the rear doped layer 7, and the light facing surface and the backlight surface of the silicon substrate 1 are relatively distributed. The back passivation layer 6 may be an intrinsic amorphous silicon passivation layer. In the backlight surface of the solar cell silicon substrate 1, the heterojunction is formed by the back passivation layer 6 and the back doped layer 7, the light-facing surface of the solar cell is of a passivation contact structure, the backlight surface is of a heterojunction structure, advantages of the back passivation layer and the back doped layer are fully utilized, and under the condition of obtaining higher open circuit voltage, shading is reduced, and short circuit current is improved.

The thickness of the back passivation layer 6 may be 10±2nm and the thickness of the back doped layer 7 may be 30±5nm. For example, the number of the cells to be processed, the thickness of the back passivation layer 6 may be one of 8nm, 9nm, 9.4nm, 10nm, 10.3nm, 11nm, 12 nm. For example, the thickness of the back surface doped layer 7 may be one of 25nm, 26nm, 28nm, 30nm, 31nm, 32nm, 34nm, 35 nm.

Optionally, referring to fig. 10, after forming the front TCO layer 8 and the back TCO layer 9, the method may further include: a back electrode 11 is formed on the back TCO layer 9 using one of screen printing low temperature silver paste, electroplating, vapor deposition. A front electrode 10 is formed on the front TCO layer 8 using one of screen printing low temperature silver paste, electroplating, vapor deposition.

The materials of the front electrode 10 and the back electrode 11 may be Ag, al, cu, au or other metals and alloys having good conductivity.

The invention also provides a solar cell prepared by any one of the preparation methods of the solar cell, and the solar cell and any one of the preparation methods of the solar cell have the same or similar beneficial effects, and in order to avoid repetition, the description is omitted.

Alternatively, referring to fig. 10, both the tunneling layer 2 and the conductively doped and carbon-doped polysilicon layer 4 cover the entire light-facing surface of the silicon substrate 1, and the passivation contact structure has a good passivation effect on the entire light-facing surface of the silicon substrate.

Optionally, the solar cell further comprises a front electrode 10 contacting the conductive doped and carbon doped polysilicon layer 4, the tunneling layer 2 and the conductive doped and carbon doped polysilicon layer 4 partially covering the entire light-facing surface of the silicon substrate 1, the projection of the conductive doped and carbon doped polysilicon layer 4 onto the light-facing surface of the silicon substrate 1, and the projection of the front electrode 10 onto the light-facing surface of the silicon substrate 1, having overlapping areas. That is to say, the passivation contact structure is a local passivation contact structure, so that contact recombination and surface recombination can be effectively inhibited, the contact resistance of a front contact area is reduced, and the open-circuit voltage, short-circuit current and photoelectric conversion efficiency of the solar cell are improved. It should be noted that the projection of the front electrode 10 may be entirely located in the projection of the locally passivated contact structure.

Alternatively, the front TCO layer 8 may have an opening through which the front electrode 10 is in contact with the conductively doped and carbon doped polysilicon layer 4, and the solar cell is relatively simple in structure, simple in process and easy to implement.

The invention also provides a photovoltaic module, which comprises a battery string formed by connecting a plurality of solar batteries in series, and has the same or similar beneficial effects as any one of the solar batteries, so that repetition is avoided, and the description is omitted here.

In the invention, the related parts of the passivation contact structure, the solar cell and the photovoltaic module can be referred to each other.

The invention is further illustrated by the following examples in conjunction with:

Example 1

Example 1 provides a method of making a passivated contact structure. And forming a tunneling layer by adopting a thermal oxidation mode, and then carrying out carbon in-situ doping in the process of vapor deposition of the conductive doped amorphous silicon layer by adopting a PECVD mode on the tunneling layer to obtain the conductive doped and carbon doped amorphous silicon layer. Specifically, siH ₄ is used as a silicon source, CH ₄ is used as a carbon source, and hydrogen diluted phosphane (PH ₃/H₂, volume ratio PH ₃:H₂ =2:98) is used as an N-type doping source. The deposition pressure of PECVD is 20 to 90Pa, the power density of a radio frequency power supply of PECVD is 50mW/cm ², and the temperature in PECVD is 180 ℃. The flow ratio of [ SiH ₄]:[CH₄]:[PH₃/H₂]:[H₂ ] is controlled to be 100:220:2:500 for the first 60s of PECVD, and the flow ratio of [ SiH ₄]:[CH₄]:[PH₃/H₂]:[H₂ ] is controlled to be 100:80:2:500 for the last 20s of PECVD.

Example 2

Example 2 also provides a method of making a passivated contact structure. And forming a tunneling layer by adopting a thermal oxidation mode, and then carrying out carbon in-situ doping in the process of vapor deposition of the conductive doped amorphous silicon layer by adopting a PECVD mode on the tunneling layer to obtain the conductive doped and carbon doped amorphous silicon layer. Specifically, siH ₄ is used as a silicon source, CH ₄ is used as a carbon source, hydrogen diluted phosphane (PH ₃/H₂, volume ratio PH ₃:H₂ =2:98) is used as an N-type doping source, and CO ₂ is used as an oxygen source. The deposition pressure of PECVD is 20 to 90Pa, the power density of a radio frequency power supply of PECVD is 50mW/cm ², and the temperature in PECVD is 180 ℃. The flow ratio of [ SiH ₄]:[CO₂]:[PH₃/H₂]:[H₂ ] is controlled to be 100:80:2:500 for the first 8s of PECVD, 50s in the middle of PECVD deposition, the flow ratio of [ SiH ₄]:[CH₄]:[PH₃/H₂]:[H₂ ] is controlled to be 100:220:2:500, and the flow ratio of [ SiH ₄]:[CH₄]:[PH₃/H₂]:[H₂ ] is controlled to be 100:80:2:500 for the second 22s of PECVD deposition.

It should be noted that, for simplicity of description, the method embodiments are shown as a series of acts, but it should be understood by those skilled in the art that the embodiments are not limited by the order of acts, as some steps may occur in other orders or concurrently in accordance with the embodiments. Further, those skilled in the art will appreciate that the embodiments described in the specification are presently preferred, and that the acts are not necessarily all required in accordance with the embodiments of the application.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those having ordinary skill in the art without departing from the spirit of the present invention and the scope of the claims, which are to be protected by the present invention.

Claims

1. A method of fabricating a passivated contact structure, the method comprising:

2. The method for preparing a passivation contact structure according to claim 1, wherein in-situ doping of carbon is performed during vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer, to obtain a conductive doped and carbon doped amorphous silicon layer, comprising:

3. The method for preparing a passivation contact structure according to claim 2, wherein during the vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer, the carbon source flow is gradually reduced, and the carbon in-situ doping is performed, so that, before the conductive doped and carbon doped amorphous silicon layer with reduced carbon concentration is obtained along the direction away from the tunneling layer, the method further comprises:

4. The method for preparing a passivation contact structure according to claim 1, wherein in-situ doping of carbon is performed during vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer, to obtain a conductive doped and carbon doped amorphous silicon layer, comprising:

In the process of vapor deposition of the conductive doped amorphous silicon layer on the tunneling layer, increasing and then reducing the carbon source flow, and carrying out carbon in-situ doping to obtain the conductive doped and carbon doped amorphous silicon layer with the carbon doping concentration which is increased and then reduced along the direction away from the tunneling layer;

5. The method for preparing a passivation contact structure according to claim 1, wherein, before the carbon in-situ doping is performed in the process of vapor depositing the conductive doped amorphous silicon layer on the tunneling layer to obtain the conductive doped and carbon doped amorphous silicon layer, the method further comprises:

6. The method for preparing a passivation contact structure according to any one of claims 1 to 5, wherein in-situ doping of carbon is performed during vapor deposition of the conductively doped amorphous silicon layer on the tunneling layer, to obtain a conductively doped and carbon doped amorphous silicon layer, comprising:

7. The method of claim 6, wherein during the vapor deposition of the plasma enhanced chemical: the deposition air pressure is 20 to 90Pa, the power density of the radio frequency power source is 10 to 70mW/cm ², and the temperature is 100 to 250 ℃.

8. The method for preparing a passivation contact structure according to claim 2, wherein in the process of vapor depositing the conductive doped amorphous silicon layer on the tunneling layer, the carbon source flow is gradually reduced, and carbon in-situ doping is performed to obtain a conductive doped and carbon doped amorphous silicon layer with reduced carbon doping concentration along a direction away from the tunneling layer, comprising:

9. The method of claim 3 or 5, wherein in the oxygen in-situ doping process, silane is used as a silicon source, carbon dioxide is used as an oxygen source, hydrogen diluted phosphane is used as an N-type doping source, and the flow ratio of the silicon source to methane to hydrogen diluted phosphane is kept at 100 (20 to 100): 2, and oxygen in-situ doping is performed to obtain the N-type oxygen doped amorphous silicon film.

10. The method of any one of claims 1-5, wherein the conductively doped and carbon-doped amorphous silicon layer has a bandgap of 1.8 to 2.0 and a light transmittance of 85% or greater.

11. The method of any one of claims 1-5, wherein the annealing temperature is: the annealing time is 20 to 40 minutes at 800 to 900 ℃.

12. A passivated contact structure, characterized in that it is produced by a method for producing a passivated contact structure according to any of claims 1-11.

13. Use of the passivated contact structure of claim 12 in a solar cell window layer.

14. The use of claim 13, wherein the conductively-doped and carbon-doped polysilicon layer has a bandgap of 2.0 to 2.2, a light transmittance of 87% or more, a conductivity Fang Zuxiao of 1kΩ, and a crystallization rate of greater than 60%.

15. A method of manufacturing a solar cell, comprising:

Forming a passivation contact structure on a light-facing surface of a silicon substrate by using the method for preparing the passivation contact structure according to any one of claims 1 to 11; wherein the tunneling layer is closer to the silicon substrate than the conductively doped and carbon-doped polysilicon layer.

16. The method of claim 15, wherein after forming the passivation contact structure, the method further comprises:

and removing the silicon nitride layer by adopting acid.

17. The method of claim 16, wherein minority carriers in the silicon substrate have a lifetime of 3000 μs or more after removing the silicon nitride layer.

18. The method of claim 15, wherein after forming the passivation contact structure, the method further comprises:

19. The method of claim 18, wherein forming a front TCO layer on the conductively doped and carbon doped polysilicon layer comprises:

20. The method of manufacturing a solar cell according to claim 19, wherein the thickness of the first front-side TCO sub-layer is 10 to 30nm;

21. The method of claim 19 or 20, wherein the first front-side TCO sub-layer is: AZO film of [ ZnO ] _n [Al₂O₃]_m, wherein n: m is: (100:1) to (100:5);

22. The method of any one of claims 15-20, wherein the method further comprises: sequentially forming a back passivation layer and a back doping layer on the backlight surface of the silicon substrate; the back doped layer and the conductively doped and carbon doped polysilicon layer have different conductive doping types; a backside TCO layer is formed on the backside doped layer.

23. A solar cell prepared by the method of any one of claims 15-22.

24. The solar cell of claim 23, wherein the tunneling layer and the conductively doped and carbon-doped polysilicon layer each cover an entire light-facing surface of the silicon substrate.

25. The solar cell of claim 23, wherein the solar cell further comprises: the front electrode is contacted with the conductive doped carbon-doped polycrystalline silicon layer, and the tunneling layer and the conductive doped carbon-doped polycrystalline silicon layer partially cover the whole light facing surface of the silicon substrate; the projection of the conductively doped and carbon-doped polysilicon layer onto the light-facing surface of the silicon substrate and the projection of the front electrode onto the light-facing surface of the silicon substrate have overlapping regions.

26. The solar cell of claim 25, wherein the front-side TCO layer has an opening through which the front-side electrode is in contact with the conductively doped and carbon-doped polysilicon layer.

27. A photovoltaic module comprising a string of cells formed by the series connection of a plurality of solar cells of any one of claims 23-26.