Silicon heterojunction cell P-type microcrystalline film and preparation method thereof

Abstract

The invention relates to the technical field of heterojunction cells, in particular to a silicon heterojunction cell P-type microcrystalline film and a preparation method thereof, and the preparation method comprises the following steps: S1, depositing a high-density P0 intrinsic amorphous silicon layer on an intrinsic amorphous silicon passivation layer; s2, processing the P0 high hydrogen dilution ratio intrinsic layer by using the P1 seed layer; s3, growing a p-nc-SiOx: H thin film on the P1 seed layer by using the P2 first main body layer; s4, growing a p-nc-Si: Hx film on the P2 first main body layer by using the P3 second main body layer; and S5, growing a P-alpha-Si: HX film on the P3 second main body layer by using the P4 contact layer. Through the unique deposition condition in the method, the deposition rate not lower than that of a film prepared by dual power supplies can be provided, and the deposition time is basically consistent with that of the film prepared by dual power supplies. Through the unique film layer structure in the method, the crystallization rate not lower than that of a thin film prepared by dual power supplies can be provided.

Description

Technical Field

[0001] The present invention relates to the technical field of heterojunction batteries, and in particular to a silicon heterojunction battery P-type microcrystalline film and a preparation method thereof. Background Art

[0002] Currently, mainstream large-capacity PECVD equipment used to prepare P-layer microcrystalline films of heterojunction solar cells basically adopts dual power sources superimposed with ultra-high power. Ultra-high power is used to promote nucleation and increase deposition rate to ensure cell efficiency and equipment capacity.

[0003] The use of dual power supply superposition will cause interference, which has high requirements for the performance of the power supply matcher. The use of dual power supply superposition will increase the power supply cost and thus push up the overall price of the equipment, which is not conducive to the development of the industry. The use of dual power supply superposition with ultra-high power has high requirements for the insulation performance and grounding performance of the equipment, which is easy to break down and spark damage to the equipment and affect production. The use of dual power supply superposition with ultra-high power is easy to cause damage to the I layer. Summary of the invention

[0004] The purpose of the present invention is to provide a silicon heterojunction battery P-type microcrystalline thin film and a preparation method thereof, so as to solve the technical problems existing in the prior art of using dual power supply superposition.

[0005] The present invention discloses a method for preparing a P-type microcrystalline thin film of a silicon heterojunction battery, comprising the following steps:

[0006] S1. Depositing a high-density P0 intrinsic amorphous silicon layer on the intrinsic amorphous silicon passivation layer;

[0007] S2. Using the P1 seed layer to process the P0 high hydrogen dilution ratio intrinsic layer;

[0008] S3. growing a p-nc-SiOx:H film on the P1 seed layer using the P2 first bulk layer;

[0009] S4. growing a p-nc-Si:Hx film on the P2 first main layer using the P3 second main layer;

[0010] S5. Use the P4 contact layer to grow a P-α-Si:HX film on top of the P3 second bulk layer.

[0011] Furthermore, the high-density P0 intrinsic amorphous silicon layer is a high hydrogen dilution ratio intrinsic amorphous silicon layer, and the thickness of the high hydrogen dilution ratio intrinsic amorphous silicon layer should be 1-3 nm.

[0012] To increase the total hydrogen content in the compact structure (silane, hydrogen mixed intrinsic amorphous silicon passivation layer), thereby promoting c-silicon surface passivation and carrier transport, and at the same time as an intermediate layer with a more ordered structure than the conventional intrinsic amorphous silicon passivation layer to increase the microcrystal nucleation rate.

[0013] Furthermore, the high hydrogen dilution ratio intrinsic amorphous silicon layer is deposited by using hydrogen and silane.

[0014] Furthermore, the hydrogen flow rate ranges from 80 to 120 slm, and the volume ratio of hydrogen to silane is from 300 to 500.

[0015] Furthermore, during the deposition of the high-density P0 intrinsic amorphous silicon layer, the pressure in the deposition chamber is in the range of 300Pa to 500Pa, the temperature is in the range of 140-165°C, and the power density of the RF power source during the deposition is in the range of 0.2-0.3W / cm 2 , the ignition time is 10-30S.

[0016] Furthermore, the P1 seed layer is deposited by using hydrogen, silane and carbon dioxide.

[0017] Carbon dioxide doping provides nucleation sites for subsequent main layer deposition and accelerates crystallization.

[0018] Furthermore, the hydrogen flow rate ranges from 80 to 120 slm, the volume ratio of hydrogen to silane is from 300 to 500, and the doping concentration of carbon dioxide is from 80% to 150%.

[0019] Furthermore, during the deposition of the P1 seed layer, the pressure in the deposition chamber is in the range of 300Pa to 400Pa, the temperature is in the range of 140-165°C, and the power density of the RF power source during the deposition is in the range of 0.15-0.25W / cm 2 , the ignition time is 30-50S.

[0020] Furthermore, the P2 first main layer is deposited by using hydrogen, silane, diborane and carbon dioxide, and the thickness of the P2 first main layer is 4-6 nm.

[0021] Furthermore, the hydrogen flow rate range is 100-200 slm, the volume ratio of hydrogen to silane is 500-700, the diborane doping concentration is 0.25%-1%, and the carbon dioxide doping concentration is 10%-30%.

[0022] Furthermore, during the deposition of the P2 first main layer to form the silicon-based film, the pressure in the deposition chamber is in the range of 400Pa to 500Pa, the temperature is in the range of 140-165°C, and the power density of the RF power source during the deposition is in the range of 0.25-0.35W / cm 2 , the ignition time is 40-60S.

[0023] Furthermore, the P3 second main layer is deposited by using hydrogen, silane and diborane, and the thickness of the P3 second main layer is 20-30 nm.

[0024] Furthermore, the hydrogen flow rate ranges from 100 to 200 slm, the volume ratio of hydrogen to silane is (200 to 400), and the diborane doping concentration is 0.5% to 1%.

[0025] Furthermore, during the deposition of the second main layer of P3, the pressure in the deposition chamber is in the range of 700Pa to 1000Pa, the temperature is in the range of 140-165°C, and the power density of the RF power source during the deposition is in the range of 0.3-0.4W / cm 2 , the ignition time is 100-150S.

[0026] Furthermore, the P4 contact layer can be made of a conventional amorphous doped P layer, the purpose of which is to provide a high-doping concentration amorphous P layer to better match the work function of the TCO layer, thereby improving the contact with the TCO layer and improving battery efficiency. The thickness of the film should be 1-2nm.

[0027] A silicon heterojunction cell P-type microcrystalline film, which comprises, from bottom to top, a P0 intrinsic amorphous silicon layer, a P1 seed layer, a P2 first main layer, a P3 second main layer and a P4 contact layer.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. Through the unique high-pressure deposition conditions of the P3 second main layer in the method of the present invention, high-pressure depletion of silane can provide a deposition rate no lower than that of the film prepared by dual power supplies, and the deposition time of the two is basically the same, which can meet the mass production capacity requirements;

[0030] 2. The unique film layer design in this invention method can promote the crystallization speed and provide an overall crystallization rate no lower than that of the film prepared by dual power sources, which can meet the efficiency requirements of mass production;

[0031] 3. The method of the present invention uses a single power supply for preparation. Compared with the dual power supply preparation in existing mass production, there is no excessive ignition reflection power caused by dual power supply interference, and has better mass production stability;

[0032] 4. The method of the present invention uses a single power supply for preparation. Compared with the dual power supply preparation in existing mass production, taking the 7 deposition chambers of the P stage most used by equipment manufacturers as an example, 7 high-power power supplies can be reduced, greatly reducing the equipment investment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only represent some embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 It is a schematic diagram of the structure of the P-type microcrystalline thin film of the present invention.

[0035] Figure 2 The Raman spectrum test result of the P-type microcrystalline film of the present invention is shown in FIG.

[0036] In the above drawings, the meanings of the various marks are: 1-P0 intrinsic amorphous silicon layer, 2-P1 seed layer, 3-P2 first main layer, 4-P3 second main layer, 5-P4 contact layer. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0038] Example 1

[0039] The device used in this embodiment is a silicon heterojunction cell P-type microcrystalline thin film and a preparation method thereof, and its specific structure is as follows: Figure 1 As shown, the following steps are included:

[0040] S1. A high-density P0 intrinsic amorphous silicon layer is deposited on the intrinsic amorphous silicon passivation layer. The high-density P0 intrinsic amorphous silicon layer is a high hydrogen dilution ratio intrinsic amorphous silicon layer. The hydrogen flow rate is 100slm, and the volume ratio of hydrogen to silane is 400:1. During the deposition of the high-density P0 intrinsic amorphous silicon layer, the air pressure in the deposition chamber is 400Pa, the temperature is 155°C, and the RF power density during the deposition is 0.25W / cm 2 , the ignition time is 20S;

[0041] S2. The P0 high hydrogen dilution ratio intrinsic layer is treated with a P1 seed layer, wherein the P1 seed layer is deposited using hydrogen, silane and carbon dioxide, wherein the hydrogen flow rate is 100 slm, the volume ratio of hydrogen to silane is 400:1, and the doping concentration of carbon dioxide is 130%. During the deposition of the P1 seed layer, the air pressure in the deposition chamber is 350 Pa, the temperature is 155°C, and the power density of the RF power supply during the deposition is 0.2 W / cm 2 , the ignition time is 30S;

[0042] S3. Use the P2 first main layer to grow a p-nc-SiOx:H film on the P1 seed layer. The P2 first main layer is deposited by hydrogen, silane, diborane and carbon dioxide. The hydrogen flow rate is 150slm, the volume ratio of hydrogen to silane is 600:1, the diborane doping concentration is 0.6%, and the carbon dioxide doping concentration is 20%. During the deposition of the P2 first main layer to form the silicon-based film, the air pressure in the deposition chamber is 450Pa, the temperature is 155°C, and the RF power density during the deposition is 0.3W / cm 2 , the ignition time is 50S;

[0043] S4. Use the P3 second main layer to grow a p-nc-Si:Hx film on the P2 first main layer. The P3 second main layer is deposited by hydrogen, silane and diborane. The hydrogen flow rate is 150slm, the volume ratio of hydrogen to silane is 300:1, and the diborane doping concentration is 0.8%. During the deposition of the P3 second main layer, the air pressure in the deposition chamber is 850Pa, the temperature is 155°C, and the RF power density during the deposition is 0.35W / cm 2 , the ignition time is 150S;

[0044] S5. Use the P4 contact layer to grow a P-α-Si:HX film on top of the P3 second bulk layer.

[0045] like Figure 2 The thin film prepared in this embodiment has an ultra-high crystallinity rate of 71.3% as measured by Raman spectroscopy.

[0046] Comparative Example 1

[0047] A dual-power growth method for a silicon heterojunction cell P-type microcrystalline thin film comprises the following steps:

[0048] S1. Clean the ultra-white glass slide with an ultrasonic cleaner for 30 minutes and wipe it dry with a dust-free cloth to remove the influence of the glass slide on the film test results;

[0049] S2. Lay the ultra-white glass slide treated in S1 on 13 different points of the carrier and introduce it into the PECVD device to prepare the P-side intrinsic amorphous silicon passivation layer;

[0050] S3. The ultra-white glass slide treated in S2 and coated with a P-side intrinsic amorphous silicon passivation layer is laid flat on 13 different points on the carrier and introduced into the PECVD for coating using a dual power supply method;

[0051] S4. The dual power coating method is divided into two steps. The first step is to prepare a seed layer. The seed layer is deposited by hydrogen, silane and carbon dioxide. The hydrogen flow rate is 60slm, the volume ratio of hydrogen to silane is 600:1, and the doping concentration of carbon dioxide is 70%. During the deposition of the seed layer, the air pressure in the deposition chamber is 500Pa, the temperature is 160°C, and the power density of the RF power supply during the deposition is 0.27W / cm 2 , the ignition time is 30S; the second step is to prepare the main layer, which is deposited by hydrogen, silane and diborane, with a hydrogen flow rate of 80slm, a volume ratio of hydrogen to silane of 200:1, a diborane doping concentration of 0.5%, a pressure of 600Pa in the deposition chamber, a temperature of 160°C, and a radio frequency power density of 0.55W / cm during the deposition. 2 , the ignition time is 160S.

[0052] The films prepared in Example 1 and Comparative Example 1 were tested using an ellipsometer and recorded;

[0053] As shown in Table 2, after 18 shifts of testing data, the stability of the film prepared in Example 1 is higher than that of the film grown by the dual power method in Comparative Example 1.

[0054] Comparative Example 2

[0055] This embodiment is used as a comparative example of the present invention to demonstrate the influence of different process conditions on the test parameters in the method of the present invention. The following steps are included:

[0056] S1. Clean the ultra-white glass slide with an ultrasonic cleaner for 30 minutes and wipe it dry with a dust-free cloth to remove the influence of the glass slide on the film test results;

[0057] S2. Lay the ultra-white glass slide treated in S1 on 13 different points of the carrier and introduce it into the PECVD device to prepare the P-side intrinsic amorphous silicon passivation layer;

[0058] S3. The ultra-white glass slide treated with S2 and coated with a P-side intrinsic amorphous silicon passivation layer was flattened on 13 different points of the carrier and introduced into PECVD to prepare a microcrystalline P layer. Compared with Example 1, only the air pressure in the deposition chamber of the second main layer of P3 was changed. The specific parameters were: the hydrogen flow rate was 150slm, the volume ratio of hydrogen to silane was 300:1, and the diborane doping concentration was 0.8%. During the deposition of the second main layer of P3, the air pressure in the deposition chamber was 700Pa, the temperature was 155°C, and the power density of the RF power supply during the deposition was 0.35W / cm 2 , the ignition time is 150S. Recorded as the first group;

[0059] S4. The ultra-white glass slide treated with S2 and coated with a P-side intrinsic amorphous silicon passivation layer is flattened on 13 different points of the carrier and introduced into PECVD to prepare a microcrystalline P layer. Compared with Example 1, only the air pressure in the deposition chamber of the second main layer P3 is changed. The specific parameters are: the hydrogen flow rate is 150slm, the volume ratio of hydrogen to silane is 300:1, and the diborane doping concentration is 0.8%. During the deposition of the second main layer P3, the air pressure in the deposition chamber is 1000Pa, the temperature is 155°C, and the power density of the RF power supply during the deposition is 0.35W / cm 2 , the ignition time is 150S. Recorded as the second group;

[0060] S5. The ultra-white glass slide treated with S2 and coated with a P-side intrinsic amorphous silicon passivation layer is flattened on 13 different points of the carrier and introduced into PECVD to prepare a microcrystalline P layer. Compared with Example 1, only the volume ratio of hydrogen to silane in the second main layer of P3 is changed. The specific parameters are: the hydrogen flow rate is 150slm, the volume ratio of hydrogen to silane is 200:1, and the diborane doping concentration is 0.8%. During the deposition of the second main layer of P3, the air pressure in the deposition chamber is 850Pa, the temperature is 155°C, and the power density of the RF power supply during the deposition is 0.35W / cm 2 , the ignition time is 150S. Recorded as the third group;

[0061] S6. The ultra-white glass slide treated with S2 and coated with a P-side intrinsic amorphous silicon passivation layer is flattened on 13 different points of the carrier and introduced into PECVD to prepare a microcrystalline P layer. Compared with Example 1, only the volume ratio of hydrogen to silane in the second main layer of P3 is changed. The specific parameters are: the hydrogen flow rate is 150slm, the volume ratio of hydrogen to silane is 400:1, and the diborane doping concentration is 0.8%. During the deposition of the second main layer of P3, the air pressure in the deposition chamber is 850Pa, the temperature is 155°C, and the power density of the RF power supply during the deposition is 0.35W / cm 2 , the ignition time is 150S. Recorded as the fourth group;

[0062] S7. The ultra-white glass slide treated in S2 and coated with a P-surface intrinsic amorphous silicon passivation layer is laid flat on 13 different points of the carrier and introduced into PECVD to prepare a microcrystalline P layer. Compared with Example 1, only the P0 intrinsic amorphous silicon layer and the P1 seed layer are removed. This is recorded as the fifth group;

[0063] S8. The ultra-white glass slide treated in S2 and coated with a P-surface intrinsic amorphous silicon passivation layer is laid flat on 13 different points of the carrier and introduced into PECVD to prepare a microcrystalline P layer. Compared with Example 1, only the P1 seed layer is removed. This is recorded as the sixth group;

[0064] S9. The ultra-white glass slide treated with S2 and coated with a P-side intrinsic amorphous silicon passivation layer is flattened on 13 different points of the carrier and introduced into PECVD to prepare a microcrystalline P layer. Compared with Example 1, the deposition parameters of the second main layer P3 are changed. The specific parameters are: the hydrogen flow rate is 150slm, the volume ratio of hydrogen to silane is 450:1, and the diborane doping concentration is 1.5%. During the deposition of the second main layer P3, the air pressure in the deposition chamber is 600Pa, the temperature is 155°C, and the power density of the RF power supply during the deposition is 0.4W / cm 2 , the ignition time is 150S. Recorded as the seventh group;

[0065] S10. The seven groups of films prepared were tested using an ellipsometer, a Raman spectrometer, a high resistance meter, and a minority carrier lifetime tester, and the results were recorded;

[0066] As shown in Table 3, for the 7 groups of thin film test data, good results can be obtained when the pressure of the P3 second main layer deposition chamber is 700Pa and 1000Pa, and good results can be obtained when the volume ratio of hydrogen to silane is 400:1 and 200:1. Removing the P0 intrinsic amorphous silicon layer and the P1 seed layer at the same time or removing only the P1 seed layer will lead to a significant decrease in the crystallization rate.

[0067] Table 1 Comparison of test parameters of thin films grown by different methods

[0068]

[0069] Table 2 Comparison of film stability grown by different methods

[0070]

[0071] Table 3 Test data of seven groups of films

[0072]

[0073] As can be seen from Table 1, the microcrystalline P film prepared by the method of the present invention and the film prepared by the dual power supply method are applied to heterojunction solar cells, and the performances exhibited by the two are comparable, and can be applied to industrial mass production lines;

[0074] from Figure 2 It can be seen that the microcrystalline P film prepared by the method of the present invention can have an ultra-high crystallization rate of 71.3%, and this upper limit can be further developed to improve the battery terminal performance;

[0075] It can be seen from Table 2 that the microcrystalline P film prepared by the method of the present invention has higher stability than the microcrystalline P film prepared by the dual power supply method, and is more suitable for industrial mass production lines;

[0076] It can be seen from Table 3 that, taking the core P3 second main layer of the method as an example, within the parameter range of the method of the present invention, such as the chamber pressure of 700Pa and 1000Pa during deposition, and the volume ratio of hydrogen to silane of 400:1 and 200:1, good results can be obtained; while exceeding the deposition parameters of the method of the present invention, it leads to difficulty in film formation, thin film thickness, difficulty in crystallization, low crystallization rate, severe hydrogen plasma etching, reduced passivation effect and low minority carrier lifetime.

[0077] It can be seen from Table 3 that removing both the P0 intrinsic amorphous silicon layer and the P1 seed layer or removing only the P1 seed layer will lead to a significant decrease in the crystallization rate. The P0 intrinsic amorphous silicon layer and the P1 seed layer in the present invention do have a significant effect on improving the crystallization rate.

[0078] The above are the implementation methods listed in this embodiment, but this embodiment is not limited to the above optional implementation methods. Those skilled in the art can arbitrarily combine the above methods to obtain other various implementation methods. Anyone can derive other various forms of implementation methods under the inspiration of this embodiment. The above specific implementation methods should not be understood as limiting the scope of protection of this embodiment. The scope of protection of this embodiment shall be based on the definition in the claims, and the description can be used to interpret the claims.

Claims

1. A method for preparing a P-type microcrystalline thin film for a silicon heterojunction battery, characterized in that: The following steps are involved: S1. Depositing a high-density P0 intrinsic amorphous silicon layer on the intrinsic amorphous silicon passivation layer; S2. Using the P1 seed layer to process the P0 high hydrogen dilution ratio intrinsic layer; S3. growing a p-nc-SiOx:H film on the P1 seed layer using the P2 first bulk layer; S4. growing a p-nc-Si:Hx film on the P2 first main layer using the P3 second main layer; S5. Use the P4 contact layer to grow a P-α-Si:HX film on top of the P3 second bulk layer.

2. The method for preparing a P-type microcrystalline thin film for a silicon heterojunction battery according to claim 1, characterized in that: The high-density P0 intrinsic amorphous silicon layer is a high hydrogen dilution ratio intrinsic amorphous silicon layer.

3. The method for preparing a P-type microcrystalline thin film for a silicon heterojunction battery according to claim 2, characterized in that: The high hydrogen dilution ratio intrinsic amorphous silicon layer is deposited by using hydrogen and silane.

4. The method for preparing a P-type microcrystalline thin film for a silicon heterojunction battery according to claim 3, characterized in that: The hydrogen flow rate range is 80-120slm, and the volume ratio of hydrogen to silane is 300-500.

5. The method for preparing a P-type microcrystalline thin film for a silicon heterojunction battery according to claim 4, characterized in that: During the deposition of the high-density P0 intrinsic amorphous silicon layer, the pressure in the deposition chamber is in the range of 300Pa to 500Pa, the temperature is in the range of 140-165°C, and the power density of the RF power source during the deposition is in the range of 0.2-0.3W / cm 2 , the ignition time is 10-30S.

6. The method for preparing a P-type microcrystalline thin film for a silicon heterojunction battery according to claim 1, characterized in that: The P1 seed layer is deposited by using hydrogen, silane and carbon dioxide.

7. The method for preparing a P-type microcrystalline thin film for a silicon heterojunction battery according to claim 6, characterized in that: The flow rate of hydrogen is in the range of 80-120 slm, the volume ratio of hydrogen to silane is in the range of 300-500, and the doping concentration of carbon dioxide is in the range of 80%-150%.

8. The method for preparing a P-type microcrystalline thin film for a silicon heterojunction battery according to claim 1, characterized in that: The P2 first main layer is deposited by using hydrogen, silane, diborane and carbon dioxide, and the thickness of the P2 first main layer is 4-6 nm.

9. The method for preparing a P-type microcrystalline thin film for a silicon heterojunction battery according to claim 1, characterized in that: The P3 second main layer is deposited by using hydrogen, silane and diborane, and the thickness of the P3 second main layer is 20-30 nm.

10. A silicon heterojunction cell P-type microcrystalline thin film, characterized in that: From bottom to top, they are P0 intrinsic amorphous silicon layer, P1 seed layer, P2 first main body layer, P3 second main body layer and P4 contact layer.

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