Monocrystalline silicon pulling method, monocrystalline silicon rod, monocrystalline silicon wafer and solar cell
By establishing a correspondence model between parameters such as resistivity and oligosperm lifetime of single crystal silicon rod samples, the target parameters are determined to adjust the growth process of single crystal silicon rods, the problem of low cell conversion efficiency caused by uneven impurity distribution in the prior art is solved, and more efficient solar cell performance is achieved.
Patent Information
- Application Number
- CN202411625119.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-14
- Publication Date
- 2025-03-04
AI Technical Summary
In the existing lifting single crystal silicon technology, impurities are unevenly distributed during crystal growth due to the coagulation phenomenon, resulting in the accumulation of impurities at the tail of the single crystal silicon rod, and the nucleus life is relatively low, which in turn limits the conversion efficiency of photovoltaic cells.
By establishing a model that characterizes the correspondence between the head and tail resistivity, minor sub-life, equal diameter length and pot retention rate of the single crystal silicon rod sample, the target parameters of the single crystal silicon rod to be made, including head resistivity and pot retention rate, and then adjust the growth process of the single crystal silicon rod to be made to improve the battery conversion efficiency.
The battery conversion efficiency of single crystal silicon rods has been improved, the theoretical maximum efficiency has been approached, and the overall performance of solar cells has been improved.
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Figure CN119553352A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of pulling single crystal silicon, and in particular to a method for pulling single crystal silicon, a single crystal silicon rod, a single crystal silicon wafer and a solar cell. Background Art
[0002] Pulling single crystal silicon is a common step in the preparation of photovoltaic cells. The quality of the pulled single crystal silicon rod is related to the cell conversion efficiency of the photovoltaic cell. The conversion efficiency of mainstream mass-produced N-type cells is generally between 25% and 27%.
[0003] However, due to the existence of segregation phenomenon in the process of growing single crystal silicon by the Czochralski process, impurities will have different distributions at different stages of crystal growth, and impurities will accumulate at the tail of the single crystal silicon rod, resulting in a low minority carrier lifetime, which leads to a large gap between the existing battery conversion efficiency and the theoretical maximum battery conversion efficiency. Summary of the invention
[0004] Based on this, it is necessary to provide a method for pulling single crystal silicon, a single crystal silicon rod, a single crystal silicon wafer and a solar cell that can improve the cell conversion efficiency of the single crystal silicon rod in order to solve the above technical problems.
[0005] In a first aspect, the present application provides a method for pulling a single crystal silicon, the method comprising:
[0006] The first model is established to characterize the corresponding relationship between the head resistivity, tail resistivity, head minority carrier lifetime, tail minority carrier lifetime, equal diameter length, and crucible retention rate of single crystal silicon rod samples in the same furnace;
[0007] A second model is established to characterize the corresponding relationship between the average resistivity of a single crystal silicon wafer, the average minority carrier lifetime and the battery conversion efficiency; the single crystal silicon wafer is prepared from the single crystal silicon rod sample; the average resistivity corresponds to the head resistivity, the tail resistivity and the equal diameter length; the average minority carrier lifetime corresponds to the head minority carrier lifetime, the tail minority carrier lifetime and the equal diameter length;
[0008] Determine the parameters when the cell conversion efficiency is the target efficiency according to the first model and the second model; the parameters include at least one of the head resistivity and the crumb rate of the single crystal silicon rod to be produced;
[0009] A single crystal silicon rod is pulled according to the parameters.
[0010] In one embodiment, the first model for establishing the corresponding relationship between the head resistivity, tail resistivity, head minority carrier lifetime, tail minority carrier lifetime, equal diameter length, and crucible retention rate of single crystal silicon rod samples in the same furnace includes:
[0011] Establishing a third model for characterizing the corresponding relationship between the minority carrier lifetime and the equal diameter length at each position in the single crystal silicon rod sample of each rod batch in the same furnace;
[0012] Establishing a fourth model for characterizing the corresponding relationship between the tail resistivity of the single crystal silicon rod sample, the crucible retention rate and the equal diameter length;
[0013] The fifth model is established to characterize the corresponding relationship between the head resistivity and the head minority carrier lifetime of the single crystal silicon rod sample;
[0014] The first model is constructed according to the third model, the fourth model and the fifth model.
[0015] In one embodiment, the third model for characterizing the corresponding relationship between the minority carrier lifetime and the equal diameter length at each position in the single crystal silicon rod sample of each rod batch in the same furnace comprises:
[0016] Obtaining a first minority carrier lifetime decay rate; the first minority carrier lifetime decay rate is a decay rate of the head minority carrier lifetime of the single crystal silicon rod samples between rods in the same furnace;
[0017] Obtaining a second minority carrier lifetime decay rate; the second minority carrier lifetime decay rate is a decay rate of the minority carrier lifetime from the head to the tail of a single single crystal silicon rod sample;
[0018] The third model is established according to the first minority carrier lifetime decay rate and the second minority carrier lifetime decay rate.
[0019] In one embodiment, obtaining the second minority carrier lifetime decay rate includes:
[0020] The weighted average values of the equal diameter length, the head minority carrier lifetime, and the tail minority carrier lifetime of single crystal silicon rod samples of multiple rod batches in the same furnace are obtained; the weighted average value is used to characterize the second minority carrier lifetime attenuation rate.
[0021] In one embodiment, the formula for obtaining the weighted average values of the equal diameter length, the head minority carrier lifetime, and the tail minority carrier lifetime of single crystal silicon rod samples of multiple rod batches in the same furnace is:
[0022]
[0023] Where, S is the weighted average, X k =(T K -W K ) / L K , T K is the minority carrier lifetime at the head of the Kth single crystal silicon rod, W K is the tail minority carrier lifetime of the Kth single crystal silicon rod, L K is the equal diameter length of the Kth single crystal silicon rod.
[0024] In one embodiment, obtaining the first minority carrier lifetime decay rate includes:
[0025] Obtaining the head minority carrier lifetime of the single crystal silicon rod samples of each rod batch in the same furnace;
[0026] The average head minority carrier lifetime of multiple single crystal silicon rod samples in the same furnace is obtained according to the minority carrier lifetime of each single crystal silicon rod sample;
[0027] The first minority carrier lifetime decay rate is obtained according to the difference in average head minority carrier lifetimes of single crystal silicon rod samples between adjacent rods and the average head minority carrier lifetime of a front rod among adjacent rods.
[0028] In one embodiment, the crucible retention rate and the equal diameter length have a preset corresponding relationship; the fourth model for establishing the corresponding relationship between the tail resistivity of the single crystal silicon rod sample and the crucible retention rate and the equal diameter length includes:
[0029] Obtaining the doping concentration of the dopant according to the effective segregation coefficient of the dopant in the single crystal silicon rod sample, the initial melt concentration of the dopant in the single crystal silicon rod sample, the crucible retention rate, and the correction factor;
[0030] The fourth model is established according to the corresponding relationship between the doping concentration and the tail resistivity of the single crystal silicon rod sample and the preset corresponding relationship between the crucible retention rate and the equal diameter length.
[0031] In one embodiment, the formula for obtaining the doping concentration of the dopant according to the effective segregation coefficient of the dopant in the single crystal silicon rod sample, the initial melt concentration of the dopant in the single crystal silicon rod sample, the crucible retention rate, and the correction factor is:
[0032]
[0033] Among them, C s is the crucible retention rate f r The doping concentration of the dopant when K eff C is the effective segregation coefficient of the dopant in the single crystal silicon rod sample; 0 is the initial melt concentration of the dopant; and X is the correction factor.
[0034] In one embodiment, the formula corresponding to the second model is:
[0035] f(x,y)=a+b*x+c*y+d*x*log(e*y+f,e)+h*exp(x);
[0036] Among them, f(x, y) is the battery conversion efficiency, x is the average resistivity, and y is the average minority carrier lifetime; a, b, c, d, e, f, and h are coefficients simulated based on experimental data and correspond to the process of pulling single crystal silicon.
[0037] In a second aspect, the present application provides a single crystal silicon rod, which is prepared by the single crystal silicon pulling method as described above.
[0038] In one embodiment, the minority carrier lifetime of the single crystal silicon rod is greater than 500 us.
[0039] In one of the embodiments, the resistivity of the single crystal silicon rod is in the range of 0.3Ω to 5Ω.
[0040] In one of the embodiments, the single crystal silicon rod includes a doping element, and the doping element includes at least one of phosphorus, antimony, arsenic, and gallium.
[0041] In a third aspect, the present application provides a single crystal silicon wafer, which is prepared according to the single crystal silicon rod as described above.
[0042] In a fourth aspect, the present application provides a solar cell, wherein the solar cell is prepared according to the above-mentioned single crystal silicon wafer.
[0043] In a fifth aspect, the present application provides a photovoltaic assembly, comprising a plurality of solar cells connected in series and / or in parallel; at least one of the solar cells is the solar cell as described above.
[0044] The above-mentioned method for pulling single crystal silicon, single crystal silicon rod, single crystal silicon wafer, solar cell and photovoltaic module, the method for pulling single crystal silicon includes: establishing a first model to characterize the correspondence between the head resistivity, tail resistivity, head minority carrier lifetime, tail minority carrier lifetime, equal diameter length and crumb retention rate of single crystal silicon rod samples in the same furnace; establishing a second model to characterize the correspondence between the average resistivity, average minority carrier lifetime and battery conversion efficiency of single crystal silicon wafers; single crystal silicon wafers are prepared from single crystal silicon rod samples; the average resistivity corresponds to the head resistivity, tail resistivity and equal diameter length; the average minority carrier lifetime corresponds to the head minority carrier lifetime, tail minority carrier lifetime and equal diameter length; according to the first model and the second model, the parameters when the battery conversion efficiency is the target efficiency are determined; the parameters include at least one of the head resistivity and crumb retention rate of the single crystal silicon rod to be produced; the single crystal silicon rod is pulled according to the parameters; in this application, the correspondence between the equal diameter length\crmb retention rate and the head resistivity and tail resistivity can be obtained according to the first model. According to the second model, the corresponding average resistivity and average minority carrier lifetime can be determined when the battery conversion efficiency is the target battery conversion efficiency; the average resistivity can be calculated based on the head resistivity, tail resistivity, and equal diameter length, so the head resistivity and equal diameter length can be determined; there is a preset corresponding relationship between the equal diameter length and the crucible retention rate, so the crucible retention rate can be determined. Further, according to the first model and the second model, the parameters when the battery conversion efficiency is the target efficiency are determined, and the battery efficiency of the solar cell prepared by the single crystal silicon rod drawn based on the parameters is more ideal, thereby improving the battery conversion efficiency of the solar cell prepared by the single crystal silicon rod. BRIEF DESCRIPTION OF THE DRAWINGS
[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.
[0046] Figure 1 One of the schematic flow diagrams of a method for pulling single crystal silicon in one embodiment;
[0047] Figure 2 A visualization effect diagram of a second model in one embodiment;
[0048] Figure 3 A schematic diagram of a flow chart of establishing a first model for characterizing the corresponding relationship between the head resistivity, tail resistivity, head minority carrier lifetime, tail minority carrier lifetime, equal diameter length, and crucible retention rate of single crystal silicon rod samples in the same furnace in one embodiment;
[0049] Figure 4A schematic diagram of a process for establishing a third model for characterizing the corresponding relationship between the minority carrier lifetime and the equal diameter length at each position in a single crystal silicon rod sample of each rod batch in the same furnace in one embodiment;
[0050] Figure 5 It is a schematic diagram of a process of obtaining the first minority carrier lifetime decay rate in one embodiment;
[0051] Figure 6 A schematic diagram of a process for establishing a fourth model for characterizing the corresponding relationship between the tail resistivity, the crucible retention rate and the equal diameter length of a single crystal silicon rod sample in one embodiment;
[0052] Figure 7 The second schematic diagram of the process of pulling single crystal silicon in one embodiment;
[0053] Figure 8 FIG. 4 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION
[0054] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.
[0055] In one embodiment, see the attached Figure 1 , attached Figure 1 This is one of the flow diagrams of the method for pulling single crystal silicon in this embodiment. The method is applied to a terminal for example. It can be understood that the method can also be applied to a server, and can also be applied to a system including a terminal and a server, and is implemented through the interaction between the terminal and the server. In this embodiment, the method includes the following steps S101 to S104.
[0056] Step S101, establishing a first model for characterizing the corresponding relationship between the head resistivity, tail resistivity, head minority carrier lifetime, tail minority carrier lifetime, equal diameter length, and crucible retention rate of single crystal silicon rod samples in the same furnace.
[0057] The single crystal silicon rod sample refers to the single crystal silicon rod generated in the process of pulling single crystal silicon. Different from the single crystal silicon rod to be produced, the single crystal silicon rod sample is mainly used to test it to obtain a large number of data sets, so as to achieve the invention purpose of the technical solution of this application.
[0058] The head resistivity and tail resistivity of the above-mentioned single crystal silicon rod sample refer to the resistivity at different positions of the single crystal silicon rod sample. For example, the head resistivity can be the end surface resistivity at the cutoff point of the shoulder cap of the single crystal silicon rod, and the tail resistivity can be the end surface resistivity at the cutoff point of the tail position of the single crystal silicon rod.
[0059] The minority carrier lifetime of a single crystal silicon rod sample refers to the average existence time of non-equilibrium minority carriers in a semiconductor (unit: μs). When preparing single crystal silicon rods, it is directly related to the conversion efficiency of single crystal silicon photovoltaic cells, because the longer the minority carrier lifetime, the smaller the probability of electron-hole pair recombination, which helps to improve the output current and efficiency of photovoltaic cells. The head minority carrier lifetime and the tail minority carrier lifetime refer to the minority carrier lifetimes at different positions of the single crystal silicon rod sample. Exemplarily, the head minority carrier lifetime can be the minority carrier lifetime of the end face where the shoulder cap of the single crystal silicon rod is truncated, and the tail minority carrier lifetime can be the minority carrier lifetime of the end face where the tail position of the single crystal silicon rod is truncated.
[0060] The equal diameter length refers to the length of the portion where the crystal diameter remains constant during the growth of the single crystal silicon rod. Since the resistivity and minority carrier lifetime of the single crystal silicon rod are not uniform during the growth process and mainly decay along the growth direction, obtaining the equal diameter length of the single crystal silicon rod sample is helpful to obtain the degree of decay of the resistivity and minority carrier lifetime.
[0061] The crucible retention rate refers to the ratio of the amount of remaining raw materials in the crucible to the initial amount of raw materials during the crystal pulling process. For the same furnace and the same root, the lower the ratio, the worse the quality of the single crystal silicon rod. Therefore, in this embodiment, determining at least one of the head resistivity and the crucible retention rate of the single crystal silicon rod to be produced is helpful to adjust the average resistance and impurity level (minority carrier lifetime) of the crystal rods in the same furnace, thereby improving the battery conversion efficiency of the prepared silicon wafers.
[0062] Step S102, establishing a second model characterizing the correspondence between the average resistivity of the single crystal silicon wafer, the average minority carrier lifetime and the battery conversion efficiency; the single crystal silicon wafer is prepared from a single crystal silicon rod sample; the average resistivity corresponds to the head resistivity, the tail resistivity and the equal diameter length; the average minority carrier lifetime corresponds to the head minority carrier lifetime, the tail minority carrier lifetime and the equal diameter length.
[0063] The average resistivity of a single crystal silicon wafer is the resistance to the flow of current inside the single crystal silicon material at a specific temperature. It is an important physical property parameter that affects the conductivity of the single crystal silicon material. The magnitude of the resistivity depends on factors such as the material's properties, temperature, and lattice structure. Since the resistivity change along the growth direction of the single crystal silicon rod shows a decaying trend during the pulling of single crystal silicon, the resistivity of the head and tail of the single crystal silicon rod sample or the average resistivity of the single silicon wafer after the silicon rod is cut can be obtained in actual measurement.
[0064] Specifically, the cell conversion efficiency of photovoltaic cells made from single-crystal silicon wafers with different average resistivity and average minority carrier lifetimes is recorded to establish a second model, that is, the correspondence between the average resistivity, the average minority carrier lifetime and the cell conversion efficiency: f(x,y)=a+b*x+c*y+d*x*log(e*y+f,e)+h*exp(x), where f(x,y) is the cell conversion efficiency, x is the average resistivity, and y is the average minority carrier lifetime. a, b, c, d, e, f, and h are coefficients simulated from experimental data, and may be other values for different cell processes. By way of example, in this embodiment, a=26.1194, b=-3.3197, c=0.0000168, d=0.3137, e=3.1301, f=29.7098, and h=0.0347. See the attached Figure 2 , attached Figure 2 The figure shows the visualization effect of the second model in this embodiment.
[0065] Step S103, determining parameters when the battery conversion efficiency is the target efficiency according to the first model and the second model; the parameters include at least one of the head resistivity and the crucible retention rate of the single crystal silicon rod to be produced.
[0066] Specifically, when the battery conversion efficiency is determined to be the target efficiency, the approximate range of the corresponding average resistivity and average minority carrier lifetime can be determined according to the second model. The corresponding equal diameter length and crucible retention rate can be further inferred according to the first model. Based on the tail resistivity, head minority carrier lifetime, tail minority carrier lifetime, and equal diameter length in the first model, the attenuation rate of the resistivity of each single crystal silicon rod in the same furnace can also be determined, so the head resistivity of each single crystal silicon rod of each rod in the same furnace can be further determined.
[0067] Step S104, pulling a single crystal silicon rod according to the parameters.
[0068] In this embodiment, the correspondence between the equal-diameter length\residue rate and the head resistivity and the tail resistivity can be obtained according to the first model. According to the second model, when the battery conversion efficiency is the target battery conversion efficiency, the corresponding average resistivity and average minority carrier lifetime can be determined; the average resistivity can be calculated according to the head resistivity, the tail resistivity and the equal-diameter length, so the head resistivity and the equal-diameter length can be determined; there is a preset correspondence between the equal-diameter length and the retention rate, so the retention rate can be determined. Further, according to the first model and the second model, the parameters when the battery conversion efficiency is the target efficiency are determined, and the battery efficiency of the solar cell prepared from the single crystal silicon rod drawn based on the parameters is more ideal, thereby improving the battery conversion efficiency of the solar cell prepared from the single crystal silicon rod.
[0069] In one embodiment, see the attached Figure 3 , attached Figure 3A flow chart of establishing a first model for characterizing the corresponding relationship among the head resistivity, tail resistivity, head minority carrier lifetime, tail minority carrier lifetime, equal diameter length, and crucible retention rate of single crystal silicon rod samples from the same furnace is shown. In this embodiment, establishing a first model for characterizing the corresponding relationship among the head resistivity, tail resistivity, head minority carrier lifetime, tail minority carrier lifetime, equal diameter length, and crucible retention rate of single crystal silicon rod samples from the same furnace includes the following steps S301 to S304.
[0070] Step S301, establishing a third model for characterizing the corresponding relationship between the minority carrier lifetime and the equal diameter length at each position in the single crystal silicon rod samples of each batch of rods in the same furnace.
[0071] Specifically, it can be established by obtaining the minority carrier lifetime of the head silicon wafer, the minority carrier lifetime of the tail silicon wafer, and the equal diameter length of each single crystal silicon rod sample in the same furnace. Obtaining the corresponding relationship between the minority carrier lifetime and the equal diameter length refers to obtaining the attenuation degree of the minority carrier lifetime of each single crystal silicon rod sample of different rod orders during the generation process, based on which the minority carrier lifetime at any position of each single crystal silicon rod in the same furnace can be obtained.
[0072] Step S302, establishing a fourth model for characterizing the corresponding relationship between the tail resistivity of the single crystal silicon rod sample, the crucible retention rate and the equal diameter length.
[0073] The establishment of the fourth model can directly test the equal diameter length, tail resistivity and crucible retention rate of the single crystal silicon rod sample to obtain the corresponding relationship between the two through data analysis. The corresponding relationship between the tail resistivity and other parameters, the corresponding relationship between the crucible retention rate and the same other parameters, and the corresponding relationship between the equal diameter length and the same other parameters can also be obtained respectively to indirectly obtain the corresponding relationship between the tail resistivity and the crucible retention rate.
[0074] Exemplarily, the fourth model can be indirectly established by respectively obtaining the relationship between the equal diameter length and the tail resistivity of the single crystal silicon rod sample and the corresponding relationship between the equal diameter length and the crucible retention rate of the single crystal silicon rod sample; but it is not limited to this.
[0075] Step S303, establishing a fifth model for characterizing the corresponding relationship between the head resistivity and the head minority carrier lifetime of the single crystal silicon rod sample.
[0076] Specifically, the fifth model can be constructed by directly testing the head resistivity and head minority carrier lifetime of single crystal silicon rod samples from different furnaces but with the same charging order, and then using linear regression analysis. For example, the fifth model in this embodiment can be expressed as: Y = -i + jX - kX 2, where Y is the head minority carrier lifetime, X is the head resistivity, i, j, k are coefficients, which can be obtained specifically according to linear regression analysis. The values may also be different according to the different head resistivity and head minority carrier lifetime of the single crystal silicon rod samples obtained from different furnaces but with the same charging order. For example, i=-10213, j=27267, k=-9902 in this embodiment.
[0077] In addition, when testing the head resistivity and head minority carrier lifetime of single crystal silicon rod samples from different furnaces but with the same charging order, the head resistivity and head minority carrier lifetime of silicon wafers of single crystal silicon rod samples from different furnaces but with the same charging order, or the resistivity and head minority carrier lifetime of tail silicon wafers, or the average resistance of the entire single crystal silicon rod sample can be tested.
[0078] Step S304, constructing the first model according to the third model, the fourth model and the fifth model.
[0079] In this embodiment, the corresponding relationships among the head resistivity, tail resistivity, head minority carrier lifetime, tail minority carrier lifetime, equal diameter length and crucible retention rate are obtained according to the third model, the fourth model and the fifth model, so that the resistivity, minority carrier lifetime and corresponding crucible retention rate at any position in the single crystal silicon rod samples of each rod in the whole furnace of single crystal silicon rod samples can be obtained, thereby obtaining an accurate data set to balance the relationship between the various parameters and improve the overall quality and cost-effectiveness of the pulled single crystal silicon rods.
[0080] In one embodiment, see the attached Figure 4 , attached Figure 4 A flow chart of establishing a third model for characterizing the correspondence between the minority carrier lifetime and the equal diameter length at each position of the single crystal silicon rod samples of each batch from the same furnace is shown. In this embodiment, establishing the third model for characterizing the correspondence between the minority carrier lifetime and the equal diameter length at each position of the single crystal silicon rod samples of each batch from the same furnace includes the following steps S401 to S403.
[0081] Step S401, obtaining a first minority carrier lifetime decay rate; the first minority carrier lifetime decay rate is the decay rate of the minority carrier lifetime at the head of the single crystal silicon rod sample between rods in the same furnace.
[0082] Specifically, the head minority carrier lifetime of the single crystal silicon rod samples of each rod batch in the same furnace can be directly obtained through testing, and the first minority carrier lifetime decay rate can be further obtained based on the difference in minority carrier lifetimes of the single crystal silicon rod samples between adjacent rod batches and the minority carrier lifetime of the front rod batch among adjacent rod batches.
[0083] It is understandable that for P-type single crystal silicon rods and N-type single crystal silicon rods, the first minority carrier lifetime decay rates of the two may be different. For example, the first minority carrier lifetime decay rate of the N-type single crystal silicon rod is 5%, and the first minority carrier lifetime decay rate of the P-type single crystal silicon rod is 11%.
[0084] Step S402, obtaining a second minority carrier lifetime decay rate; the second minority carrier lifetime decay rate is the decay rate of the minority carrier lifetime from the head to the tail of a single single crystal silicon rod sample.
[0085] The second minority carrier lifetime decay rate can be understood as the decay of the minority carrier lifetime from the head of a single single crystal silicon rod sample to the minority carrier lifetime of the tail silicon wafer.
[0086] Due to the segregation phenomenon in the process of pulling single crystal silicon, impurities will have different distributions at different stages of crystal formation, so the minority carrier lifetime will decay along the length direction of the single crystal silicon rod during its growth. Obtaining the second minority carrier lifetime decay rate in step S402 is conducive to obtaining the second minority carrier lifetime decay rate of the minority carrier lifetime at each position of the single crystal silicon rod.
[0087] Step S403: establishing a third model according to the first minority carrier lifetime decay rate and the second minority carrier lifetime decay rate.
[0088] In this embodiment, according to the decay rate of the minority carrier lifetime of the single crystal silicon rod samples between the rods of the same furnace and the decay of the minority carrier lifetime from the head of the single crystal silicon rod sample to the tail silicon wafer, the minority carrier lifetime at any position of the single crystal silicon rods of each rod in the same furnace can be obtained. The first model constructed by the third model, the fourth model and the fifth model combined with the second model can obtain the data set determined by the parameter determination method in this application shown in Table 1. Compared with the parameters determined by the traditional work shown in Table 2, the parameters determined according to this embodiment can prepare single crystal silicon rods with higher battery conversion efficiency.
[0089] Table 1:
[0090] RCZ Head resistance Head life Tail life Leave the crucible Tail resistor Full Pot Standard rod length Average resistance Life expectancy efficiency Adding materials 1 1.35 8779 2494 25％ 0.600 930 4147 0.98 5636.67 26.061 930 2 1.35 8281 2327 25％ 0.600 930 4147 0.98 5304.07 26.036 695 3 1.35 8040 2256 25％ 0.600 930 4147 0.98 5148.09 26.025 695 4 1.35 7966 2255 25％ 0.600 930 4147 0.98 5110.52 26.009 695 5 1.35 6500 1237 30％ 0.660 930 3887 1.01 3868.66 26.008 652 6 1.35 6000 867 30％ 0.660 930 3887 1.01 3433.54 25.985 652 7 1.35 5500 400 4％ 0.200 750 4554 0.78 2950.00 25.954 472 Summary 26.03 4792
[0091] Table 2:
[0092] RCZ Head resistance Head life Tail life Leave the crucible Tail resistor Full Pot Standard rod length Average resistance Life expectancy efficiency Adding materials 1 1.25 8079 2643 35％ 0.675 930 3587 0.96 5360.99 26.043 930 2 1.25 7581 2431 35％ 0.675 930 3587 0.96 5006.05 26.016 602 3 1.25 7340 2337 35％ 0.675 930 3587 0.96 4838.59 26.003 602 4 1.25 7266 2326 35％ 0.675 930 3587 0.96 4796.11 26.000 602 5 1.25 6941 2084 35％ 0.675 930 3587 0.96 4512.74 25.977 602 6 1.25 6586 1849 35％ 0.675 930 3587 0.96 4217.61 25.951 602 7 1.25 5758 400 5％ 0.200 750 4554 0.73 3079.00 25.923 422 Summary 25.98 4367
[0093] Among them, RCZ in Table 1 and Table 2 refers to the feeding order in the process of pulling single crystal silicon rods by multiple feeding and compound pulling, head resistance refers to the end surface resistivity at the head cutoff, head life refers to the minority carrier lifetime at the head cutoff, tail life refers to the minority carrier lifetime at the end surface at the tail cutoff, crucible retention is the crucible retention rate, tail resistance refers to the end surface resistivity at the tail cutoff of the silicon rod, standard rod length refers to the theoretical equal diameter length under a certain diameter (here the diameter is 300mm), average resistance refers to the average resistivity of the head and tail of the pulled single crystal silicon rod, average life refers to the average minority carrier lifetime of the head and tail of the pulled single crystal silicon rod, and efficiency refers to the battery conversion efficiency of solar cells made of the corresponding single crystal silicon rod.
[0094] In one embodiment, obtaining the second minority carrier lifetime decay rate includes: obtaining a weighted average value of the equal diameter length, the head minority carrier lifetime, and the tail minority carrier lifetime of multiple rod batches of single crystal silicon rod samples from the same furnace; the weighted average value is used to characterize the second minority carrier lifetime decay rate.
[0095] Specifically, the weighted average values of the equal diameter length, the head minority carrier lifetime, and the tail minority carrier lifetime of the single crystal silicon rod samples of multiple rods in the same furnace can be obtained by taking the head minority carrier lifetime, tail minority carrier lifetime, and equal diameter length of K single crystal silicon rod samples of different rods in the same furnace, and performing weighted average of the head minority carrier lifetime, tail minority carrier lifetime, and equal diameter length of the K single crystal silicon rod samples:
[0096]
[0097] Among them, S is the weighted average, X k =(T K -W K ) / L K , T K is the minority carrier lifetime at the head of the Kth single crystal silicon rod, W K is the tail minority carrier lifetime of the Kth single crystal silicon rod, L K is the equal diameter length of the Kth single crystal silicon rod. For any equal diameter length position L of the Kth single crystal silicon rod l The minority carrier lifetime can be obtained by S*L i Get.
[0098] In this embodiment, based on the weighted average of the equal-diameter length, the head minority carrier lifetime, and the tail minority carrier lifetime of multiple batches of single crystal silicon rod samples from the same furnace, the weighted average is used to characterize the second minority carrier lifetime decay rate and the equal-diameter length of the single crystal silicon rod, so as to obtain the minority carrier lifetime at any equal-diameter length position of any batch of single crystal silicon rods.
[0099] In one embodiment, the formula for obtaining the weighted average values of the equal diameter length, the head minority carrier lifetime, and the tail minority carrier lifetime of the single crystal silicon rod samples of multiple rod batches in the same furnace is:
[0100]
[0101] Among them, S is the weighted average, X k =(T K -W K ) / L K , T K is the minority carrier lifetime at the head of the Kth single crystal silicon rod, W K is the tail minority carrier lifetime of the Kth single crystal silicon rod, L K is the equal diameter length of the Kth single crystal silicon rod.
[0102] In one embodiment, see the attached Figure 5 , attached Figure 5 A schematic diagram of the process of obtaining the first minority carrier lifetime decay rate is shown. In this embodiment, obtaining the first minority carrier lifetime decay rate includes the following steps S501 to S503.
[0103] Step S501, obtaining the minority carrier lifetime at the head of the single crystal silicon rod samples of each batch in the same furnace.
[0104] For example, the minority carrier lifetime at the head of the single crystal silicon rod samples of each rod batch in the same furnace can be obtained by direct measurement.
[0105] Step S502, obtaining the average head minority carrier lifetime of multiple single crystal silicon rod samples in the same furnace according to the minority carrier lifetime of the single crystal silicon rod samples of each rod batch.
[0106] By averaging the minority carrier lifetimes of the single crystal silicon rod samples of each batch, the average head minority carrier lifetime of multiple single crystal silicon rod samples from the same furnace can be obtained.
[0107] Step S503, obtaining a first minority carrier lifetime decay rate according to the difference in average head minority carrier lifetimes of single crystal silicon rod samples between adjacent rods and the average head minority carrier lifetime of a front rod among adjacent rods.
[0108] In this embodiment, an accurate first minority carrier lifetime attenuation rate can be obtained based on the difference in average head minority carrier lifetimes of single crystal silicon rod samples between adjacent rods and the average head minority carrier lifetime of the front rod among adjacent rods.
[0109] In one embodiment, the crucible retention rate and the equal diameter length have a preset corresponding relationship; see the attached Figure 6 , attached Figure 6 A schematic flow chart of establishing a fourth model for characterizing the correspondence between the tail resistivity, crucible retention rate and equal diameter length of a single crystal silicon rod sample is shown. In this embodiment, establishing a fourth model for characterizing the correspondence between the tail resistivity, crucible retention rate and equal diameter length of a single crystal silicon rod sample includes the following steps S601 to S602.
[0110] Step S601, obtaining the doping concentration of the dopant according to the effective segregation coefficient of the dopant in the single crystal silicon rod sample, the initial melt concentration of the dopant in the single crystal silicon rod sample, the crucible retention rate, and the correction factor.
[0111] Step S602, establishing a fourth model according to the corresponding relationship between the doping concentration and the tail resistivity of the single crystal silicon rod sample, and the preset corresponding relationship between the crucible retention rate and the equal diameter length.
[0112] In the process of pulling single crystal silicon rods, based on the segregation effect, the doping elements are gradually enriched in the crucible. There is a corresponding relationship between the tail doping concentration of the single crystal silicon rod sample and the crucible retention rate, and the formula satisfies: C s =K eff C 0f r Keff-1+X According to the national standard "Conversion Procedure for Resistivity and Dopant Concentration of Boron-doped, Phosphorus-doped and Arsenic-doped Silicon Single Crystal", the doping concentration C s Convert to resistivity, C s is the CZ silicon single crystal with a crucible retention rate of f r The doping concentration of n-type dopant when K eff is the effective segregation coefficient of n-type dopant in silicon single crystal; C 0 is the initial melt concentration of n-type dopant in the CZ silicon single crystal; correction factor X = m / v, m is the total mass transfer coefficient of n-type dopant in silicon, and v is the crystal pulling rate. According to the above method, the relationship between resistivity and crucible retention rate can be indirectly obtained.
[0113] In one embodiment, the formula for obtaining the doping concentration of the dopant according to the effective segregation coefficient of the dopant in the single crystal silicon rod sample, the initial melt concentration of the dopant in the single crystal silicon rod sample, the crucible retention rate, and the correction factor is:
[0114]
[0115] Among them, C s is the crucible retention rate f r The doping concentration of the dopant when K eff is the effective segregation coefficient of the dopant in the single crystal silicon rod sample; C 0 is the initial melt concentration of the dopant; X is the correction factor.
[0116] In one embodiment, the formula corresponding to the second model is:
[0117] f(x,y)=a+b*x+c*y+d*x*log(e*y+f,e)+h*exp(x);
[0118] Among them, f(x,y) is the battery conversion efficiency, x is the average resistivity, and y is the average minority carrier lifetime; a, b, c, d, e, f, and h are coefficients simulated based on experimental data and correspond to the process of pulling single crystal silicon.
[0119] In one embodiment, see the attached Figure 7 , attached Figure 7 A second schematic flow chart of a method for pulling single crystal silicon is shown. The parameter determination method in this embodiment includes the following steps S701 to S709.
[0120] Step S701, respectively obtaining the average minority carrier lifetime and the first minority carrier lifetime decay rate of multiple single crystal silicon rod samples in the same furnace; the first minority carrier lifetime decay rate is the decay rate of the minority carrier lifetime of the single crystal silicon rod samples between different rods in the same furnace.
[0121] Step S702, obtaining the weighted average of the equal diameter length, the head minority carrier lifetime, and the tail minority carrier lifetime of multiple batches of single crystal silicon rod samples from the same furnace; the weighted average represents the second minority carrier lifetime decay rate; the second minority carrier lifetime decay rate is the decay rate of the minority carrier lifetime in a single single crystal silicon rod sample.
[0122] Step S703: establishing a third model according to the first minority carrier lifetime decay rate and the second minority carrier lifetime decay rate.
[0123] Step S704, obtaining the doping concentration of the dopant according to the effective segregation coefficient of the dopant in the single crystal silicon rod sample, the initial melt concentration of the dopant in the single crystal silicon rod sample, the crucible retention rate, and the correction factor.
[0124] Step S705, establishing a fourth model according to the corresponding relationship between the tail resistivity, the crucible retention rate and the equal diameter length of the single crystal silicon rod sample.
[0125] Step S706, establishing a fifth model for characterizing the corresponding relationship between the head resistivity and the head minority carrier lifetime of the single crystal silicon rod sample.
[0126] Step S707, constructing the first model according to the third model, the fourth model and the fifth model.
[0127] Step S708, establishing a second model that characterizes the corresponding relationship between the average resistivity of the single crystal silicon wafer, the average minority carrier lifetime and the battery conversion efficiency; the single crystal silicon wafer is prepared from the single crystal silicon rod samples in the same furnace.
[0128] Step S709, determining parameters when the battery conversion efficiency is the target efficiency according to the first model and the second model.
[0129] In this embodiment, the attenuation degree of minority carrier lifetime during the growth of single crystal silicon rods can be accurately reflected, and the relationship between the minority carrier lifetime and the crucible retention rate can be established. The crucible retention rate refers to the proportion of residual material in the crucible after the single crystal silicon rod is taken out. For the same furnace and the same root, the lower the crucible retention rate, the lower the conversion efficiency of the single crystal silicon rod battery. Therefore, further controlling the head resistivity and crucible retention rate according to the second model can adjust the average resistivity and impurity level (minority carrier lifetime) of the crystal rods in the same furnace, so that the resistivity and minority carrier lifetime of each position of the single crystal silicon rod are evenly distributed, thereby improving the battery conversion efficiency of the photovoltaic cell prepared according to the single crystal silicon rod.
[0130] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.
[0131] In one embodiment, the present application also provides a single crystal silicon rod, which is prepared by the single crystal silicon pulling method in any of the above embodiments.
[0132] In one embodiment, the minority carrier lifetime of the single crystal silicon rod is greater than 500 us.
[0133] In one embodiment, the resistivity of the single crystal silicon rod is in the range of 0.3Ω to 5Ω.
[0134] In one embodiment, the single crystal silicon rod includes a doping element, wherein the doping element includes at least one of phosphorus, antimony, arsenic, and gallium.
[0135] In one embodiment, the single crystal silicon wafer is prepared according to the single crystal silicon rod in any of the above embodiments.
[0136] In one embodiment, the present application further provides a solar cell, which is prepared according to the single crystal silicon wafer in the above embodiment.
[0137] In one embodiment, the present application further provides a photovoltaic assembly, which includes a plurality of solar cells connected in series and / or in parallel; at least one solar cell is a solar cell as in the above embodiment.
[0138] In an exemplary embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure diagram may be as shown in FIG. Figure 8As shown. The computer device includes a processor, a memory, an input / output interface, a communication interface, a display unit and an input device. Among them, the processor, the memory and the input / output interface are connected through a system bus, and the communication interface, the display unit and the input device are connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be implemented through WIFI, a mobile cellular network, near field communication (Near Field Communication, NFC) or other technologies. When the computer program is executed by the processor, a method for pulling single crystal silicon is implemented. The display unit of the computer device is used to form a visually visible picture, which can be a display screen, a projection device or a virtual reality imaging device. The display screen can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or a button, trackball or touchpad set on the computer device shell, or an external keyboard, touchpad or mouse.
[0139] Those skilled in the art will understand that Figure 8 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.
[0140] In an exemplary embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above-mentioned method embodiments when executing the computer program.
[0141] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.
[0142] In one embodiment, a computer program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.
[0143] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, an artificial intelligence (AI) processor, etc., but are not limited to this.
[0144] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.
[0145] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.
Claims
1. A method for pulling single crystal silicon, characterized in that: The method comprises: The first model is established to characterize the corresponding relationship between the head resistivity, tail resistivity, head minority carrier lifetime, tail minority carrier lifetime, equal diameter length, and crucible retention rate of single crystal silicon rod samples in the same furnace; A second model is established to characterize the corresponding relationship between the average resistivity of a single crystal silicon wafer, the average minority carrier lifetime and the battery conversion efficiency; the single crystal silicon wafer is prepared from the single crystal silicon rod sample; the average resistivity corresponds to the head resistivity, the tail resistivity and the equal diameter length; the average minority carrier lifetime corresponds to the head minority carrier lifetime, the tail minority carrier lifetime and the equal diameter length; Determine the parameters when the cell conversion efficiency is the target efficiency according to the first model and the second model; the parameters include at least one of the head resistivity and the crumb rate of the single crystal silicon rod to be produced; A single crystal silicon rod is pulled according to the parameters.
2. The method for pulling single crystal silicon according to claim 1, characterized in that: The first model for establishing the corresponding relationship between the head resistivity, tail resistivity, head minority carrier lifetime, tail minority carrier lifetime, equal diameter length, and crucible retention rate of single crystal silicon rod samples in the same furnace includes: Establishing a third model for characterizing the corresponding relationship between the minority carrier lifetime and the equal diameter length at each position in the single crystal silicon rod sample of each rod batch in the same furnace; Establishing a fourth model for characterizing the corresponding relationship between the tail resistivity of the single crystal silicon rod sample, the crucible retention rate and the equal diameter length; The fifth model is established to characterize the corresponding relationship between the head resistivity and the head minority carrier lifetime of the single crystal silicon rod sample; The first model is constructed according to the third model, the fourth model and the fifth model.
3. The method for pulling single crystal silicon according to claim 2, characterized in that: The third model for characterizing the corresponding relationship between the minority carrier lifetime and the equal diameter length at each position in the single crystal silicon rod samples of each batch of rods in the same furnace comprises: Obtaining a first minority carrier lifetime decay rate; the first minority carrier lifetime decay rate is a decay rate of the head minority carrier lifetime of the single crystal silicon rod samples between rods in the same furnace; Obtaining a second minority carrier lifetime decay rate; the second minority carrier lifetime decay rate is a decay rate of the minority carrier lifetime from the head to the tail of a single single crystal silicon rod sample; The third model is established according to the first minority carrier lifetime decay rate and the second minority carrier lifetime decay rate.
4. The method for pulling single crystal silicon according to claim 3, characterized in that: The obtaining of the second minority carrier lifetime decay rate comprises: The weighted average values of the equal diameter length, the head minority carrier lifetime, and the tail minority carrier lifetime of single crystal silicon rod samples of multiple rod batches in the same furnace are obtained; the weighted average value is used to characterize the second minority carrier lifetime attenuation rate.
5. The method for pulling single crystal silicon according to claim 4, characterized in that: The formula for obtaining the weighted average values of the equal diameter length, the head minority carrier lifetime, and the tail minority carrier lifetime of the single crystal silicon rod samples of multiple rod batches in the same furnace is: Where, S is the weighted average, X k =(T K -W K ) / L K , T K is the minority carrier lifetime at the head of the Kth single crystal silicon rod, W K is the tail minority carrier lifetime of the Kth single crystal silicon rod, L K is the equal diameter length of the Kth single crystal silicon rod.
6. The method for pulling single crystal silicon according to claim 3, characterized in that: The obtaining of the first minority carrier lifetime decay rate comprises: Obtaining the head minority carrier lifetime of the single crystal silicon rod samples of each rod batch in the same furnace; The average head minority carrier lifetime of multiple single crystal silicon rod samples in the same furnace is obtained according to the minority carrier lifetime of each single crystal silicon rod sample; The first minority carrier lifetime decay rate is obtained according to the difference in average head minority carrier lifetimes of single crystal silicon rod samples between adjacent rods and the average head minority carrier lifetime of a front rod among adjacent rods.
7. The method for pulling single crystal silicon according to claim 2, characterized in that: The crucible retention rate and the equal diameter length have a preset corresponding relationship; The fourth model for characterizing the corresponding relationship between the tail resistivity of the single crystal silicon rod sample, the crucible retention rate and the equal diameter length comprises: Obtaining the doping concentration of the dopant according to the effective segregation coefficient of the dopant in the single crystal silicon rod sample, the initial melt concentration of the dopant in the single crystal silicon rod sample, the crucible retention rate, and the correction factor; The fourth model is established according to the corresponding relationship between the doping concentration and the tail resistivity of the single crystal silicon rod sample and the preset corresponding relationship between the crucible retention rate and the equal diameter length.
8. The method for pulling single crystal silicon according to claim 7, characterized in that: The formula for obtaining the doping concentration of the dopant according to the effective segregation coefficient of the dopant in the single crystal silicon rod sample, the initial melt concentration of the dopant in the single crystal silicon rod sample, the crucible retention rate, and the correction factor is: Among them, C s is the crucible retention rate f r The doping concentration of the dopant when K eff is the effective segregation coefficient of the dopant in the single crystal silicon rod sample; C0 is the initial melt concentration of the dopant; and X is the correction factor.
9. The method for pulling single crystal silicon according to claim 1, characterized in that: The formula corresponding to the second model is: f(x,y)=a+b*x+c*y+d*x*log(e*y+f,e)+h*exp(x); Among them, f(x, y) is the battery conversion efficiency, x is the average resistivity, and y is the average minority carrier lifetime; a, b, c, d, e, f, and h are coefficients simulated based on experimental data and correspond to the process of pulling single crystal silicon.
10. A single crystal silicon rod, characterized in that: The single crystal silicon rod is prepared by the single crystal silicon pulling method according to any one of claims 1 to 9.
11. The single crystal silicon rod according to claim 10, characterized in that: The minority carrier lifetime of the single crystal silicon rod is greater than 500 us.
12. The single crystal silicon rod according to claim 10, characterized in that: The resistivity of the single crystal silicon rod is in the range of 0.3Ω to 5Ω.
13. The single crystal silicon rod according to claim 10, characterized in that: The single crystal silicon rod includes a doping element, and the doping element includes at least one of phosphorus, antimony, arsenic, and gallium.
14. A single crystal silicon wafer, characterized in that: The single crystal silicon wafer is prepared according to the single crystal silicon rod according to any one of claims 10 to 13.
15. A solar cell, characterized in that: The solar cell is prepared according to the single crystal silicon wafer as claimed in claim 14.
16. A photovoltaic module, characterized in that: The photovoltaic assembly comprises a plurality of solar cells connected in series and / or in parallel; at least one of the solar cells is the solar cell according to claim 15.