TW201027762A - Method for manufacturing solar cell - Google Patents

Abstract

A manufacturing method of a polycrystalline solar cell is disclosed. A polycrystalline silicon solar cell in accordance with the present invention performs crystallization-annealing amorphous silicon with a metal catalyst so as to reduce a crystallization temperature. The manufacturing method of a solar cell in accordance with the present invention includes the steps of (a) forming a first amorphous silicon layer on a substrate; (b) forming a second amorphous silicon layer on the first amorphous silicon layer; (c) forming a metal layer on the second amorphous silicon layer; (d) performing crystallization-annealing the second amorphous silicon layer; and (e) forming a third amorphous silicon layer on a resulting crystalline silicon layer of the step (d).

Description

201027762 VI. INSTRUCTION DESCRIPTION: FIELD OF THE INVENTION The present invention relates to a method for fabricating a germanium solar cell, and more particularly to a method for fabricating a polycrystalline germanium solar cell having high photovoltaic efficiency and a tandem polycrystalline solar cell. . [Prior Art 3 Background of the Invention • The solar cell is a key component of the photovoltaic technology that directly converts sunlight into electricity, and is used in a wide variety of applications from space to home. • The solar cell is basically a diode with a p-n junction. The principle of operation is as follows. When a solar light having a larger than the band gap energy of the semiconductor is incident on the p-n junction of the solar cell, a pair of holes is generated. By the electric field generated at the P-n junction 15, electrons are transferred to the η layer, and the holes are transferred to the p layer, thereby generating photovoltaic power between the p and η layers. When the two ® terminals of a solar cell are connected to a load or a system, electricity can be generated by current flow. The solar 20 battery can be classified into various types depending on the material used to form the inner layer (i.e., the light absorbing layer). In general, tantalum solar cells with an inner layer made of tantalum are the most popular. There are two types of tantalum solar cells: substrate type (single or polycrystalline) solar cells and thin film type (amorphous or polycrystalline) solar cells. In addition to these two types of solar cells, there are CdTe or CIS (CuInSe2) compound thin film solar cells, III 3V materials based on III-V materials, dye-sensitized solar cells, organic solar cells, and the like. A single crystal germanium substrate type solar cell has a relatively high conversion efficiency compared to other types of solar cells, but its monolithic germanium wafers are disadvantageous in that they are fatal. Compared with the single crystal germanium substrate type solar cell, the 5 polycrystalline solar substrate can be manufactured at a lower cost, but the polycrystalline silicon substrate type solar cell and the single type are made of a large number of solar cells of two types of solar cells. Crystalline substrate type solar cells are also not far away. The polycrystalline germanium substrate type solar cell raw material is expensive and the manufacturing process thereof is complicated, so that the manufacturing cost thereof is difficult to reduce. 10 As one of the methods for solving the defects of these substrate type solar cells, the thin film type solar solar cell mainly has a thin layer deposited on the substrate (such as glass) as an inner layer, so that the manufacturing cost thereof is relatively low. So it attracted a lot of attention. In fact, the film tantalum solar cell produced can be about 1 times thinner than the substrate type solar cell. 15 Amorphous germanium thin film solar cells were first developed from thin-film solar cells and were first used in the home. Since amorphous forms by chemical vapor deposition (CVD), amorphous steel contributes to amorphous silicon solar power; it also produces a large amount of production and low manufacturing costs. On the contrary, the photovoltaic efficiency of the amorphous-crushed solar cell appears to be lower than that of the substrate 2 〇石夕太阳 cell because many of the amorphous atoms have a dangling atom with a dangling bond. In addition, the life of the amorphous day solar cell is rather short, and the efficiency of the like is likely to decrease as the period of use increases. Therefore, in order to overcome the aforementioned shortcomings of the lion crystal solar cell, efforts have been made to develop a polycrystalline silicon solar cell 201027762 cell and a tandem thin film solar cell having at least two photovoltaic units.

[Name Bu Ming Nei L; J 5 10 15 ❿ 20 Summary of the Invention Disclosure of the Technical Problem Due to the use of polycrystalline silicon as the inner layer, the polycrystalline tantalum thin film solar cell performs better than the amorphous tantalum thin film solar cell using the amorphous germanium as the inner layer. . However, one of the problems with such polycrystalline tantalum thin film solar cells is that it is difficult to prepare polycrystalline germanium. More specifically, polycrystalline germanium is usually obtained by solid-crystallized amorphite. Solid state crystallization of amorphous slabs involves annealing at high temperatures (e.g., 6 〇〇〇c or higher) for tens of hours, which is unsuitable for mass production of solar cells. In particular, in the high temperature of more than 600 «^ during solid state crystallization, an expensive quartz substrate must be used, and a conventional glass substrate cannot be used, but this increases the manufacturing cost of the solar cell. Moreover, solid state crystallization is known to reduce the characteristics of solar cells because polycrystalline particles tend to grow toward irregular orientations and are very irregular in size. Tandem thin film solar cells include wide-bandgap photovoltaic layers and narrow-bandgap photovoltaic layers to enhance photovoltaic efficiency and to some extent prevent the degradation of the efficiency caused by photoaging. For example, tandem amorphous by plasma enhanced chemical vapor deposition (pECVD) published by Sait Qh et al.

Si(a-Si)/microcrystalline Si(^Si)_ domain battery. Here, the initial photovoltaic efficiency is 9.4% per W, and the final photovoltaic efficiency of the obtained solar cell is 8.5%. 5 201027762 However, in order to manufacture the tandem Shihua thin film solar cell developed by Saitoh et al., microcrystalline Si (pc-Si) should be formed under conditions of low deposition pressure and two depositional powers, so the deposition time increases too much, making it It is difficult to apply to mass production of solar cells. 5 Therefore, conventional polycrystalline tantalum thin-film solar cells and tandem thin-film solar cells have some limitations in terms of achieving high photovoltaic efficiency and good mass productivity. Technical Solution An object of the present invention is to solve the above disadvantages, and therefore, the present invention provides a method of manufacturing a polycrystalline silicon solar cell having high photovoltaic efficiency. Another object of the present invention is to provide a method for manufacturing a polycrystalline silicon thin film solar cell in a case where a large amount of manufacturing time is shortened and a large amount of cost is reduced, thereby improving mass productivity. A further object of the present invention is to provide a method of fabricating a solar cell having enhanced photovoltaic efficiency by causing such polycrystalline silicon thin film solar cells to be in a tandem structure. [Advantageous Effects] The formation of a polycrystalline silicon layer which is crystallized by a metal can enhance the photovoltaic efficiency of a solar cell according to the manufacturing method of the solar cell of the present invention. Further, since the polycrystalline germanium layer is formed over a conventional glass substrate, the solar cell according to the present invention can be produced at a lower manufacturing cost. Furthermore, the leakage current can be minimized by the method of manufacturing a solar cell according to the present invention by removing residual metal from the polysilicon layer. 201027762 Moreover, the photovoltaic efficiency of the solar cell can be enhanced by the method of manufacturing a solar cell according to the present invention by manufacturing a tandem solar cell. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and features of the present invention will become more apparent from the following description of the preferred embodiments of the invention. A cross-sectional view of a solar cell manufacturing method of the first embodiment; and a second to a cross-sectional view showing a solar cell manufacturing method according to a second embodiment of the present invention.

t Embodiment J DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The best mode method of the invention, = the aspect of the invention, provides a method for manufacturing a solar cell comprising the steps of: (4) forming on a substrate - the first - The second layer of H and 2 layers of crystallization is a layer of crystallization. e, the third amorphous method is formed on the crystal material obtained in the step (4), and the other side provides the side of the solar cell (9) on the second t(a) on the substrate - the first amorphous a layer of amorphous stone I·/(9) formed on the second amorphous layer; (4) in the second form, a second, a third amorphous, (4) amorphous on the third non-riding layer (J into two • forming a fifth (the ice-forming layer on the fifth amorphous layer) on the fourth amorphous layer; (g) performing crystallization-annealing on the 7 201027762 fifth amorphous layer; And (h) forming a sixth amorphous germanium layer on the crystalline germanium layer obtained in the step (g). The method may further comprise the step of degassing the residual metal in the crystalline germanium layer obtained in the step (d). The method may further comprise the step of degassing the residual metal in the crystalline germanium layer obtained in the step (g). The first to third amorphous germanium layers may be formed by chemical vapor deposition. The first to sixth amorphous germanium The layer may be formed by chemical vapor deposition. The metal layer may contain Ni, A, Ti, Ag, Au, Co, Sb, Pd, 10 Cu, or the like. The metal layer may be deposited by physical vapor deposition or Vapor deposition formation. The crystallization-annealing temperature can be in the range of 400 to 700 ° C. The crystallization-annealing temperature can be lower than the solid crystallization temperature of amorphous bismuth. The degassing temperature can be in the range of 400 to 600 ° C. The metal may react with impurities in the third amorphous germanium layer to produce a compound. The metal may react with impurities in the sixth amorphous germanium layer to produce a compound. Mode 20 of the Invention In the following detailed description, The present invention may be carried out with the aid of the description of the specific embodiments, and the description of the embodiments is sufficiently detailed to enable those skilled in the art to practice the invention. The various embodiments of the present invention, although not identical to one another, are not necessarily mutually exclusive. For example, a particular feature, structure, or characteristic described herein with respect to an embodiment may be implemented in other embodiments. The spirit of escaping invented and _. Again, it should be understood that the position or arrangement of 70 individual pieces can be changed without still escaping the spirit and scope. So the following detailed description It should not be recognized as a second system and the scope of the invention is limited only by the scope of the following patent application. The following patent scope should be granted to the king of the full-time enclosure. The P-equal scope is appropriately In the drawings, the number of elements of a plurality of figures indicates similar or similar elements or functions. [Embodiment I] 10 The following is a detailed explanation of the first embodiment of the present invention with reference to the accompanying drawings. 9 is a cross-sectional view showing a method of manufacturing a solar cell according to a first embodiment of the present invention. Fig. 9 is a view showing a completed polycrystalline silicon (thin film) solar cell according to a first embodiment of the present invention. The polycrystalline germanium solar cell 1 includes an anti-reflective layer 110, a first transparent conductive layer 120, a p-type germanium layer i3〇p, an i-type germanium layer i30i, a Φ-type 11 germanium layer 130n, and a second transparent conductive layer. The layer 150 and a metal electrode layer 160' are successively stacked above the substrate 1A. Among the tantalum layers, at least the i-type tantalum layer 130i is a polycrystalline germanium layer. 2〇 More specifically, the polycrystalline hard 1% battery 10 has a p-i-n structure. Here, the pin structure represents a P-type doped germanium layer 130ρ, an n-type doped germanium layer 130n, and an i-type (ie, internal) layered layer i3〇i sandwiched therebetween, wherein The ruthenium layer is relatively insulated from the p-type ruthenium layer 130p and the n-type ruthenium layer 130n. 9 201027762 Although this embodiment indicates that the layer is completely unmixed, it is placed between the p-type layer 113p and the type 11 layer, and the present invention is not necessarily limited thereto, and may be set as compared with The P-type germanium layer 13〇p&n-type germanium layer 130η is relatively insulating (ie, having low conductivity) amorphous germanium layer. For example, it is possible to produce a highly doped ytterbium type and a type 11 yttrium layer 130p and ι30η, and to provide a low-density η-type or p-type impurity between them, and the following is the first according to the present invention. A detailed description of the various steps of the solar cell manufacturing method of the embodiment. First, referring to Fig. 1, an antireflection layer 10 is formed on a substrate 1A. Ίο is too aware of the 'battery' and the substrate 1 is preferably made of a transparent material such as glass and plastic to absorb sunlight. Here, the substrate 100 can be subjected to a textUring process to increase the efficiency of the solar cell. The completion of the texturing process can prevent the depletion of the photovoltaic cell's specific efficiency, which is caused by the optical loss caused by the reflection of the incident light on the surface of the substrate 15. Therefore, the 'texturing process mainly involves roughening the surface of the target substrate for the solar cell, i.e., forming an irregular pattern on the surface of the substrate. When the surface of the substrate becomes rough by texturing, the light that has been reflected once is again reflected, and the reflectance of the incident light on the surface of the substrate is lowered, so that a larger amount of light is captured and thus the optical loss is reduced. The anti-reflection layer 110 functions to prevent the efficiency of the solar cell 10 from being attenuated. This efficiency is attenuated because the sunlight entering through the substrate 1 is not absorbed but is directly reflected to the outside. To this end, the anti-reflective layer 110 may comprise, for example, yttrium oxide (Si〇x) or nitride. Examples of methods of forming the anti-reflection 201027762 layer 110 may include, but are not limited to, low pressure chemical vapor deposition (LPCVD), plasma enhanced chemical vapor deposition (pECVD), and the like. 5 10 15 20 Next, referring to Fig. 2, the first transparent conductive layer 12 is formed on the anti-reflection layer 110. The first transparent conductive layer 120 functions to transmit sunlight and is in electrical contact with the p-type germanium layer 130p. For example, the first transparent conductive layer 120 may contain IT〇 (indium tin oxide) or ΖηΟ doped with an impurity such as a metal. Examples of the method of forming the first transparent conductive layer 120 may include, but are not limited to, physical vapor deposition (PVD) such as sputtering. Referring to FIGS. 3 and 4, a two-layer amorphous germanium layer, that is, a p-type amorphous germanium layer 130ρ and an i-type amorphous germanium layer 13〇i, are successively formed on the first transparent conductive layer 12〇. . Examples of the method of forming the P-type amorphous germanium layer 130p and the i-type amorphous germanium layer 13〇i may include, but are not limited to, chemical vapor deposition such as LpcvD, PECVD, hot wire chemical vapor deposition (HWCVD), and the like. Preferably, during the formation of the amorphous fracture layer, the p-type amorphous layer 13 〇p is doped in situ. Typically, the butterfly (9) is used as an impurity of p-type doping. The thickness and doping concentration of each p-type amorphous iridium layer i3〇p and i-type amorphous layer are determined by the thickness and doping concentration selected for a typical over-cut solar cell. In order to produce a polycrystalline solar cell, the present invention uses so-called metal-induced crystallization (cis), and the metal-induced crystallization is based on a metal catalyst to crystallize the amorphous powder, thereby crystallizing the i-type amorphous layer. Polycrystalline stone layer. Jumping into a polycrystalline germanium film transistor corresponding to a driving circuit in a flat panel display (such as an LCD) (poly Si is not described here. FT) is well known in the art, so its fine 11 201027762 is a metal-induced crystallization, such as As shown in Fig. 5, first, before the formation of the n-type amorphous (tetra) 13Gn, the metal layer 14 () is formed on the i-type amorphous glazed layer 130. The metal layer 14A may contain a combination of see, a, 丨, 知, Co Sb Pd, Cu, or the like. Examples of the method of forming the metal layer 14 include chemical vapor deposition (such as LPCVD, PECVD, atomic layer deposition (ALD), etc.) or physical vapor deposition (such as sputtering, etc.). Next, referring to Fig. 6, crystallization-annealing 300 is carried out on the i-type amorphous germanium layer 13〇i. ! The amorphous ruthenium layer 13〇i is crystallized into a type 1 polysilicon layer l30i via crystallization annealing, and the presence of a metal catalyst allows the 10 people to perform at a temperature lower than the amorphous crystallization solid state crystallization temperature. Crystallization. The crystallization-annealing 300 can be carried out in a typical annealing furnace, preferably at a temperature of 400-700 °C! It takes 1 hour. Further, the p-type amorphous germanium layer 130p may be crystallized by crystallization-annealing to form a p-type polycrystalline fine layer 130p. 15 Next, referring to Fig. 7, an 11-type amorphous germanium layer i3〇n is formed on the i-type polysilicon layer 130i. In addition to phosphorus (P) or arsenic (AS) as an n-type doping impurity, the formation and doping method of the n-type amorphous germanium layer 130n and the above-described i-type amorphous germanium layer 130i and p-type amorphous germanium The formation and doping methods of layer i3〇p are the same. The thickness and doping concentration of the n-type amorphous germanium layer 130n are determined in accordance with the thickness and the dopant concentration which are typically selected for the solar cell of 矽20. Next, referring to Fig. 18, a gettering 400 is performed to remove the metal element, that is, the metal catalyst which has been introduced into the MIC of Fig. 6 and remains in the i-type polysilicon layer 130i. The residual metal remaining in the earthy polysilicon layer 130i, such as Ni, is diffused into the non-b曰曰12 201027762 layer by the degassing, and reacts with the n-type impurity p to form nickel phosphide (Ni2P). Compound. In this manner, the residual metal in the i-type polysilicon layer 130i can be removed. Degassing 400 is preferably carried out at 400-600 ° C for 1 to 5 hours. 5 10 15 ❹ 20 So even if Ni is introduced into the solar cell, more specifically, the introduction of the i-type polycrystalline layer 130i may be unavoidable for the MIC, but it can still prevent the sun caused by metal contamination. Attenuation of the overall properties of the battery, such as an increase in leakage current. At this time, the amount of metal catalyst introduced must be controlled to minimize metal contamination in the solar cell. One of the ways is to control the thickness of the metal layer 140', but the invention is not always limited thereto. In some instances, the metal layer needs to be made even thinner than the atomic layer to keep the amount of residual metal in the polycrystalline layer at a minimum. Here, making the metal layer thinner than the one atomic layer means that the entire area of the amorphous germanium layer is not completely covered by the deposited metal layer, that is, the metal layer is not completely deposited on the amorphous layer. The rate <1), instead of the metal layer, is continuously deposited on the amorphous layer. In other words, since the coverage is less than 1, more metal atoms can be placed between the metal atoms that have been deposited on the amorphous germanium layer. Further, although the embodiment proposes that the crystallization-annealing 3 〇〇 should be performed after the metal layer 140 is first formed on the i-type amorphous germanium layer I30i, the present invention is not always limited thereto. That is, the crystallization-annealing 3 〇〇 can be carried out after the metal layer 140 is formed on the n-type amorphous germanium layer 130n or the p-type amorphous germanium layer 13〇p. Finally, referring to Fig. 9, the second transparent conductive layer 15 and the metal electrode 13 201027762 layer 16 are successively formed over the n-type amorphous layer i3〇n to obtain the completed layer 10. The material and formation method of the second transparent conductive layer 15A are completely the same as those of the first transparent conductive layer 12A. Further, the metal electrode layer 160 may be made of any conductive material such as aluminum, and may be formed by physical vapor deposition such as 5 thermal evaporation, sputtering, or the like. In the configuration of the solar cell 1A shown in Fig. II, the anti-reflection layer U0 and the first and second transparent conductive layers 120 and 150 can be excluded when possible. Furthermore, in terms of the overall properties of the solar cell, it is preferable to use only the anti-reflection layer U or the first transparent conductive layer 120. As previously explained, the method for fabricating a polycrystalline silicon solar cell according to the first embodiment of the present invention uses MIC technology to crystallize amorphous germanium into a poly-crystalline germanium, which can be implemented on a conventional glass substrate. Low temperature process. Therefore, the manufacturing cost of the solar cell can be reduced, and the leakage current caused by the metal contamination can be minimized by degassing. [Embodiment II] Hereinafter, a second embodiment of the present invention will be explained in detail with reference to the accompanying drawings. In addition to the first pin layer 130p, 130i and 130n and the second pin layer 170p, 170i and 170n, the 20-cell battery according to the second embodiment of the present invention has the same meaning as explained with reference to Figures 1 to 9. The solar cell 10 of one embodiment has the same configuration. Therefore, in the following description of the second embodiment, the substrate 100, the antireflection layer 11, the first transparent conductive layer 12, the metal layer 140, the second transparent conductive layer 150 and the metal electrode layer 16 will not be detailed. Explain to avoid unnecessary repetitive statements of the same components. 14 201027762 Figures 10 through 18 show cross-sectional views of a method of fabricating a solar cell 20 in accordance with a second embodiment of the present invention. The 18th ® shows the completed polycrystalline (thin film) solar cell 20 in accordance with the third embodiment of the present invention. 5 10 15 ❹ 20 Refer to Fig. 18 'Polycrystalline ♦ solar cell with tandem structure 2 〇 including anti-reflective layer 11G, first transparent conductive layer 12 (), p-in broken layer (p-type germanium layer 130p, i Type 矽 layer 13〇i type 矽 layer 13〇n), second p small n 矽 layer (P type 矽 layer 170p, i type 矽 layer 17〇i and n type 矽 layer 17〇n), second transparent conductive layer 15G is stacked with the metal electrode layer (10), which is successively stacked over the substrate 100. Here, the first p_i_ni layer is an amorphous layer and at least the i-type layer 17〇i in the second p-i-n layer is a polysilicon layer. More specifically, the polycrystalline solar cell 20 is configured to have a wonderful laminate of two p_i_n snaps. Here, the pin structure represents a p-type doped dream layer 130p and ΠΟρ, an n-type doped germanium layer 13〇n and 17〇n, and a type 1 (ie, internal) germanium layer 13 sandwiched therebetween. The structure of 〇i and 17〇i, in which the 矽-type 矽 layer is relatively insulated from the p-type shi-ding layer 13〇p and ι7〇ρ and the η-type shi-ding layer 13〇n and 17〇n. Although the embodiment is such that the completely undoped i-type germanium layers 13 and 17〇i are placed between the p-type germanium layers 130P and 17〇P and the n-type lithospheres 130n and 170η, the present invention is not necessarily Limited thereto, and an amorphous germanium layer in which the n-type germanium layers 13〇11 and 17〇η are relatively insulated (i.e., have low conductivity) can be placed as compared with the p-type layer and the Π0ρ. For example, we can also produce highly doped p-type fracture layers 13〇ρ and 17〇ρ with highly doped n-type 矽-layer π〇η and 17〇Π, and doped with low-density η-type or ρ The ruthenium layer 13〇i 15 201027762 and 170i of the type impurity are placed between them. The present invention is a detailed description of the respective steps of the manufacturing method of the solar cell 2 according to the second embodiment of the present invention. First, referring to Fig. 10, the antireflection layer 11 is formed on the substrate 1A, and the first conductive layer 12 is formed on the antireflection layer 11A as shown in the first embodiment. Next, referring to FIG. 11, the amorphous layer of the three-layer structure, that is, the p-type amorphous layer I30p"-type amorphous slab layer 13〇i and the n-type amorphous slab layer 13〇n are successively opened. A first pin layer for the tandem solar cell 20 is obtained over the first transparent conductive layer 12A. The first pin-day layers 130p, 130i, and 130n are in an amorphous state. Examples of the method of forming the same may include, but are not limited to, chemical vapor deposition (such as LPCVD, PECVD, HWCVD, etc.). Preferably, the η type or ρ on each of the first pin layers 130p, 130i, and 130n The type is doped in situ during the formation of the amorphous germanium layer. In general, boron (germanium) is used as the impurity of the germanium type doping, and phosphorus (germanium) or arsenic (As) is used as the n-type doping. The thickness of each of the first pin fragments 130p, 130i, and 130n and the change in the doping/agronomy are determined by the thickness and doping concentration typically selected for the tandem solar cell. 20 Referring to Figures 12 and 13, a Ρ-type amorphous germanium layer 170ρ and an i-type amorphous germanium layer 17〇i are successively formed on the n-type amorphous germanium layer 130n. p-type amorphous germanium The method of forming and doping the 17〇ρ and i-type amorphous germanium layer 170i is exactly the same as the formation and doping method of the p-type amorphous germanium layer 130p and the i-type amorphous germanium layer 13〇i described in the first embodiment. 16 201027762 • At this time, in order to manufacture a tantalum solar cell having an amorphous tantalum layer/polycrystalline tantalum layer tandem structure, the present invention uses MIC technology to crystallize the i-type amorphous Shishi layer 17〇i into a polycrystalline layer. For this reason, as shown in Fig. 14, first, the 'metal layer 140 is formed on the i-type amorphous germanium layer 17〇i before the formation of the n-type amorphous stone layer 5 170n. Next, referring to Fig. 15, Crystallization-annealing 300 is performed on the i-type amorphous germanium layer i7〇i. Through the crystallization-annealing process, the germanium-type amorphous germanium layer 17〇i is crystallized into the i-type polycrystalline germanium layer 170i, and in the presence of a metal catalyst The crystallization can be carried out at a temperature lower than the solid state crystallization temperature of the amorphous stone. The crystallization-annealing process is carried out in a typical annealing furnace, preferably at 400-700 ° C for 1 to 1 Further, the p-type amorphous germanium layer 17〇p may be crystallized via crystallization-annealing 300 to form a p-type polysilicon layer 17 0p. Here, in order to manufacture a solar cell having an amorphous germanium/polysilicon layer 15 tandem structure according to the present invention, preferably, the crystallization-annealing temperature is selected from the temperature of the first pin layer solid crystallizing. The range, more specifically, does not produce the β i-type amorphous germanium layer 130i. In other words, preferably, the i-type amorphous litmus layer 130i does not undergo solid state crystallization during the crystallization-annealing 3〇〇 process. The polycrystalline germanium layer is formed. 20 Next, referring to Fig. 16, an n-type amorphous slab layer 170n is formed on the i-type polysilicon layer 170i. The formation and doping method of the n-type amorphous germanium layer i7〇n is completely the same as the formation and doping method of the n-type amorphous germanium layer non in the first embodiment. The thickness and doping concentration of the n-type amorphous germanium layer 170n are determined in accordance with the thickness and doping concentration which are typically selected for the tandem solar cell. 17 201027762 In this manner, the second p-i_n layers 170p, 170i, and 170n for the tandem solar cell 20 are completed. As shown, the second p-i-n ♦ layer has exactly the same structure as the first p-i-n 矽 layer. Therefore, if the first layer has an n-i-p structure, the second layer should also have an n-i-p structure. 5 Next, referring to the figure, degassing 400 is carried out to remove the metal element, that is, the metal catalyst which has been introduced into the MIC of Fig. 15 and remains in the i-type polycrystalline layer 170i. Via degassing 400, a metal remaining in the i-type polycrystalline layer 170i, such as]Sii, diffuses into the n-type amorphous slab layer l7〇n to react with the n-type impurity Ρ to form a nickel phosphide (Ni 2 P) compound. . In this way, the residual metal in the i-type polycrystalline layer 170i can be removed. Preferably, degassing 400 is carried out at 400-600 ° C for 1 to 5 hours. Therefore, even if Ni is introduced into the solar cell, more specifically, it is introduced into the i-type polysilicon layer 170i, it may be unavoidable in terms of the MIC, but we can still prevent the 15 attenuation of the overall properties of the solar cell caused by metal contamination ( For example, an increase in leakage current). Further, although the embodiment is performed after the metal layer 14 is first formed on the i-type amorphous layer 170i, the crystallization is performed. The annealing is not described herein. That is, 'crystallization-annealing 3 〇〇 can be performed 20 times after the metal layer 140 is formed on the n-type amorphous fracture layer 17〇n or the P-type amorphous lithium layer 17〇P. Finally, referring to FIG. 18, the second transparent conductive layer 15A and the metal electrode layer 160 are successively formed over the n-type amorphous slab 170n' as shown in the method of the first embodiment to obtain the completed tandem stone. At the same time, although the present invention interprets the second embodiment with a P_i_n layer of 201027762, which has a two-layer structure, the present invention is not always limited thereto, but For example, a p-small layer solar cell having a three-layer structure can also be an embodiment of the present invention. That is, if at least one layer of the solar cell constituting the solar cell contains a phosphating metal compound, such a solar cell and its manufacturing method are considered to fall within the scope of the present invention.

Moreover, the tandem solar cell of the present invention can be greatly reduced by using MIC technology to crystallize amorphous austenite as polycrystalline shreds compared to the conventional tandem Shixia% battery using PECVD to prepare microcrystalline stone itself. Manufactured with time and reduced costs. Although the first and second embodiments of the present invention have employed the p_i_n structure as a basic structure for constructing a solar cell, the present invention is not always limited thereto, and conversely, it may adopt a nip structure, that is, an n-type 矽 layer/丨 type The laminated structure of the stone layer/p layer. However, in the case of the nip structure, considering that sunlight enters from the P side (that is, sunlight enters from the opposite side of the substrate), the substrate does not absolutely have to be made of a glass-like transparent material, but It can be made from other materials like tantalum, metal and metal alloys. In this case, in terms of enhancing the efficiency of the solar cell, it is generally preferred that the sunlight pass through the P-type germanium layer into the i-type germanium layer. This is because of the change in the drift rate in the pair of holes created by the sunlight. Usually the upper hole has a drifting rate that is much lower than the electron. Therefore, in order to maximize the collection efficiency of all the solar light carriers, most of the carriers must be generated at the interface between the p-type germanium layer and the i-type germanium layer to keep the moving distance of the holes to a minimum. Although the present invention has been described in terms of certain preferred embodiments, it will be apparent that various changes and modifications may be made to the present invention without departing from the scope of the invention as defined in the following claims. category. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 9 are cross-sectional views showing a solar cell manufacturing method according to a first embodiment of the present invention; and FIGS. 10 to 18 are views showing a solar cell according to a second embodiment of the present invention. A cross-sectional view of the manufacturing method. [Description of main components] 10...Solar battery 20...Solar battery 100...Substrate 110...Anti-reflection layer 120·.·First transparent conductive layer BOp...p-type germanium layer 130i...I-type germanium layer 130η...η type Broken layer 140...metal layer 150.··second transparent conductive layer 160·.·metal electrode layer 170ρ...p type 矽 layer 170i... i type shi layer 170η... η type shi layer 300... crystallization _ Annealing 400... Degassing

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Claims (1)

201027762 VII. Patent application scope: 1. A method for manufacturing a solar cell, comprising the steps of: (a) forming a first amorphous germanium layer on a substrate; (b) forming a first amorphous germanium layer on the substrate; Forming a second amorphous germanium layer; (c) forming a metal layer on the second amorphous germanium layer; (d) performing crystallization-annealing on the second amorphous germanium layer; and (e) performing the step ( d) A third amorphous germanium layer is formed on the obtained crystalline germanium layer. 2. A method of fabricating a solar cell comprising the steps of: (a) forming a first amorphous germanium layer on a substrate; (b) forming a second non-deposit on the first amorphous germanium layer a crystalline germanium layer; (c) forming a third amorphous germanium layer on the second amorphous germanium layer; (d) forming a fourth amorphous germanium layer on the third amorphous germanium layer; (e) Forming a fifth amorphous germanium layer on the fourth amorphous germanium layer; (f) forming a metal layer on the fifth amorphous germanium layer; (g) performing crystallization on the fifth amorphous germanium layer - Annealing; and (h) forming a sixth amorphous germanium layer on the crystalline germanium layer obtained in the step (g). ® 3. The method of claim 1, further comprising the step of: performing a gettering of the residual metal in the crystalline germanium layer obtained in step (d). 4. The method of claim 2, further comprising the step of: degassing the residual metal in the crystalline layer obtained in step (g). 5. The method of claim 1, wherein the first to third amorphous germanium layers are formed by chemical vapor deposition. 6. The method of claim 2, wherein the first to sixth amorphous 21 201027762 layers are formed by chemical vapor deposition. 7. The method of claim i or 2, wherein the metal layer comprises a combination of Ni, A, Ti, Ag, Au, Co, Sb, Pd, Cu, or the like. 8. If the application is general (4) or 2, the metal layer of the towel is formed by physical vapor deposition or chemical vapor deposition. 9. The method of claim 2, wherein the crystallization-annealing temperature is in the range of 400 to 700 °C. The method of claim 2, wherein the temperature of the crystallization annealing is lower than the solid crystallization temperature of the amorphous ruthenium. η. The method of claim 3, wherein the degassing temperature is in the range of 400 to 600 〇C. It is not necessary to remedy the three-time method, and the towel (4) reacts with the impurities in the non-deuterium layer to produce a compound. 13. The method of claim 4, wherein the metal reacts with impurities in the (b) layer to produce a compound. twenty two