Patent Publication Number: US-2011056560-A1

Title: Solar cell module and manufacturing method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The entire disclosure of Japanese Patent Application No. 2009-205618 filed on Sep. 7, 2009, including specification, claims,drawings,andabstract,isincorporatedhereinbyreference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a solar cell module and a manufacturing method of a solar cell module. 
     2. Background Art 
     A solar cell module is formed by sequentially layering a first electrode, one or more semiconductor thin film photovoltaic units, and a second electrode over a substrate having an insulating surface. Each photovoltaic unit is formed by layering a p-type layer, an i-type layer which forms a photoelectric conversion layer, and an n-type layer from the side of incidence of light. 
     As the solar cell module, there exists a single-type solar cell module having a single photovoltaic unit of a microcrystalline silicon film, and a tandem-type solar cell module in which a photovoltaic unit of an amorphous silicon film and a photovoltaic unit of a microcrystalline silicon film are layered. 
     Normally, in order to improve a photoelectric conversion characteristic in the solar cell module, it is desirable that the crystallinity in a surface of the microcrystalline silicon film be uniform. However, in reality, because of the performances of the film forming devices for the microcrystalline silicon film and a further increase in the area of the solar cell module, it is difficult to achieve a sufficiently uniform crystallinity in the surface of the microcrystalline silicon film. As a result, in the solar cell module having the photovoltaic unit of the microcrystalline silicon, the crystallization percentage in a peripheral region becomes lower than that in the center region in the surface, an amount of generation of the carriers becomes lower in the peripheral region than the center region during power generation, and the photoelectric conversion efficiency becomes non-uniform in the surface. Because of this, there may be cases where the characteristic is reduced for the solar cell module as a whole. 
     SUMMARY 
     According to one aspect of the present invention, there is provided a solar cell module comprising a microcrystalline silicon film as a photovoltaic layer, wherein the microcrystalline silicon film of the photovoltaic layer comprises a first region and a second region having a lower crystallization percentage than the first region in a surface of the solar cell module, and a tab electrode to a terminal box of the solar cell module is placed in a manner to overlap the second region. 
     According to another aspect of the present invention, there is provided a method of manufacturing a solar cell module having a microcrystalline silicon film as a photovoltaic layer, the method comprising forming a microcrystalline silicon film comprising a first region and a second region having a lower crystallization percentage than the first region in a surface of the solar cell module, and forming a tab electrode to a terminal box of the solar cell module in a manner to overlap the second region. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the present invention will be described in detail based on the following drawings, wherein: 
         FIG. 1  is a plan view showing a structure of a tandem-type solar cell module in a preferred embodiment of the present invention; 
         FIG. 2  is a cross sectional diagram showing a structure of a tandem-type solar cell module in a preferred embodiment of the present invention; 
         FIG. 3  is a cross sectional diagram showing a structure of a tandem-type solar cell module in a preferred embodiment of the present invention; 
         FIG. 4  is a diagram showing an example of a structural distribution in a surface of an i-type layer of a μc-Si unit in a preferred embodiment of the present invention; 
         FIG. 5  is a diagram showing a crystallization percentage in a surface of an i-type layer of a μc-Si unit in a preferred embodiment of the present invention; and 
         FIG. 6  is a diagram showing a lifetime of a carrier in a surface of an i-type layer of a μc-Si unit in a preferred embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Preferred Embodiment  
       FIGS. 1-3  are diagrams showing a structure of a tandem-type solar cell module  100  in a preferred embodiment of the present invention.  FIG. 1  is a plan view viewed from a side opposite to the side of incidence of light,  FIG. 2  is a cross sectional diagram along a line a-a of  FIG. 1 , and  FIG. 3  is a cross sectional diagram along a line b-b of  FIG. 1 . In the actual tandem-type solar cell module  100 , an insulating tape covering a tab electrode, EVA which forms a protection member, and a back sheet are formed, but these structures are not shown in order to more clearly show the structure. 
     The tandem-type solar cell module  100  comprises, with a transparent insulating substrate  10  as a light incidence side, a transparent conductive film  12 , a photovoltaic unit  14 , a backside electrode  16 , an insulating tape  18 , tab electrodes  20  and  22 , and a terminal box  24 , layered from the light incidence side. 
     A structure and a manufacturing method of the tandem-type solar cell module  100  in the present embodiment will now be described. 
     For the transparent insulating substrate  10 , a material having a light transmittance at least in a visible light wavelength region may be used, such as, for example, a glass substrate and a plastic substrate. The transparent conductive film  12  is formed over the transparent insulating substrate  10 . For the transparent conductive film  12 , it is preferable to use at least one or a combination of a plurality of transparent conductive oxides (TCO) in which tin (Sn), antimony (Sb), fluorine (F), aluminum (Al), or the like is contained in tin oxide (SnO 2 ), zinc oxide (ZnO), indium tin oxide (ITO), or the like. In particular, zinc oxide (ZnO) is preferable because of its high light transmittance, low resistivity, and high plasma endurance characteristic. The transparent conductive film  12  maybe formed through, for example, sputtering. A thickness of the transparent conductive film  12  is preferably set in a range of greater than or equal to 500 nm and less than or equal to 5000 nm. In addition, unevenness having a light confinement effect is preferably formed on the surface of the transparent conductive film  12 . 
     As shown in  FIGS. 2 and 3 , when the tandem-type solar cell module  100  is formed to have a structure in which a plurality of cells are connected in series, a slit S 1  in which a surface of the transparent insulating substrate  10  is exposed is formed in the transparent conductive film  12 , and the transparent conductive film  12  is patterned to a strip shape. In addition, as shown in the plan view of  FIG. 1 , a slit S 2  in which the surface of the transparent insulating substrate  10  is exposed may be formed in a direction crossing a direction of extension of the slit S 1 , to form a structure in which a plurality of groups of photovoltaic cells connected in series are arranged in parallel to each other. 
     For example, the slits S 1  and S 2  may be formed using a YAG laser having a wavelength of 1064 nm, an energy density of 13 J/cm 2 , and a pulse frequency of 3 kHz. 
     The photovoltaic unit  14  is formed over the transparent conductive film  12 . In the tandem-type solar cell module  100  in the present embodiment, the photovoltaic unit  14  has a structure in which an amorphous silicon photovoltaic unit (a-Si unit) functioning as a top cell and having a wide band gap, an intermediate layer, and a microcrystalline silicon photovoltaic unit (μc-Si unit) functioning as a bottom cell and having a narrower band gap than the a-Si unit are sequentially layered. For example, the photovoltaic unit  14  may be formed through formation conditions as shown in TABLE 1. In TABLE 1, diborane (B 2 H 6 ) and phosphine (PH 3 ) are gases diluted to 1% based on hydrogen. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                 SUBSTRATE 
                 GAS FLOW 
                 REACTION 
                   
                   
               
               
                   
                   
                 TEMPERATURE 
                 RATE 
                 PRESSURE 
                 RF POWER 
                 THICKNESS 
               
               
                   
                 LAYER 
                 (° C.) 
                 (sccm) 
                 (Pa) 
                 (W) 
                 (nm) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 a-Si unit 
                 p 
                 180 
                 SiH 4 : 100 
                 100 
                 30  
                 10 
               
               
                   
                 LAYER 
                   
                 CH 4 : 10 
                   
                 (11 mW/cm 2 ) 
                   
               
               
                   
                   
                   
                 H 2 : 1000 
                   
                   
                   
               
               
                   
                   
                   
                 B 2 H 6 : 50 
                   
                   
                   
               
               
                   
                 i 
                 180 
                 SiH 4 : 300 
                 100 
                 30  
                 300 
               
               
                   
                 LAYER 
                   
                 H 2 : 1000 
                   
                 (11 mW/cm 2 ) 
                   
               
               
                   
                 n 
                 180 
                 SiH 4 : 10 
                 200 
                 300 
                 20 
               
               
                   
                 LAYER 
                   
                 H 2 : 2000 
                   
                 (110 mW/cm 2 ) 
                   
               
               
                   
                   
                   
                 PH 3 : 5 
                   
                   
                   
               
               
                 μ c-Si 
                 p 
                 180 
                 SiH 4 : 10 
                 200 
                 300 
                 10 
               
               
                 unit 
                 LAYER 
                   
                 H 2 : 2000 
                   
                 (110 mW/cm 2 ) 
                   
               
               
                   
                   
                   
                 B 2 H 6 : 5 
                   
                   
                   
               
               
                   
                 i 
                 180 
                 SiH 4 : 50 
                 600 
                 600 
                 2000 
               
               
                   
                 LAYER 
                   
                 H 2 : 3000 
                   
                 (220 mW/cm 2 ) 
                   
               
               
                   
                 n 
                 180 
                 SiH 4 : 10 
                 200 
                 300 
                 20 
               
               
                   
                 LAYER 
                   
                 H 2 : 2000 
                   
                 (110 mW/cm 2 ) 
                   
               
               
                   
                   
                   
                 PH 3 : 5 
               
               
                   
               
            
           
         
       
     
     First, the a-Si unit is formed by sequentially layering silicon-based thin films of a p-type layer, an i-type layer, and an n-type layer over the transparent conductive film  12 . The a-Si unit may be formed by plasma chemical vapor deposition (plasma CVD) in which mixture gas in which silicon-containing gas such as silane (SiH 4 ), disilane (Si 2 H 6 ), and dichlorsilane (SiH 2 Cl 2 ), carbon-containing gas such as methane (CH 4 ), p-type dopant-containing gas such as diborane (B 2 H 6 ), n-type dopant-containing gas such as phosphine (PH 3 ), and dilution gas such as hydrogen (H 2 ) are mixed is made into plasma, and a film is formed. 
     For the plasma CVD, for example, an RF plasma CVD of 13.56 MHz maybepreferablyapplied. TheRFplasmaCVDmaybeofaparallel plate type. Alternatively, a structure maybe employed in which a gas shower hole for supplying the mixture gas of materials is formed on a side, of the electrodes of the parallel plate type, on which the transparent insulating substrate  10  is not placed. An input power density of the plasma is preferably set to greater than or equal to 5 mW/cm 2  and less than or equal to 100 mW/cm 2 . 
     The p-type layer of the a-Si unit has a single layer structure or a layered structure of an amorphous silicon layer, a microcrystalline silicon thin film, and a microcrystalline silicon carbide thin film, doped with a p-type dopant (such as boron) and having a thickness of greater than or equal to 5 nm and less than or equal to 50 nm. A film characteristic of the p-type layer may be changed by adjusting mixture ratios of the silicon-containing gas, p-type dopant-containing gas, and dilution gas, pressure, and plasma generating high-frequency power. The i-type layer of the a-Si unit is an amorphous silicon film formed over the p-type layer, not doped with any dopant, and having a thickness of greater than or equal to 50 nm and less than or equal to 500 nm. A film characteristic of the i-type layer may be changed by adjusting the mixture ratios of the silicon-containing gas and the dilution gas, pressure, and plasma generating high-frequency power. The i-type layer forms a photoelectric conversion layer of the a-Si unit. The n-type layer of the a-Si unit is an n-type microcrystalline silicon layer (n-type μc-Si:H) formed over the i-type layer, doped with an n-type dopant (such as phosphorus), and having a thickness of greater than or equal to 10 nm and less than or equal to 100 nm. A film characteristic of the n-type layer may be change by adjusting the mixture ratios of the silicon-containing gas, the carbon-containing gas, the n-type dopant-containing gas, and the dilution gas, pressure, and plasma generating high-frequency power. 
     The intermediate layer is formed over the a-Si unit. For the intermediate layer, a transparent conductive oxide (TCO) such as zinc oxide (ZnO), and silicon oxide (SiOx) is preferably used. In particular, it is preferable to use zinc oxide (ZnO) and silicon oxide (SiOx) to which magnesium is contained. The intermediate layer may be formed, for example, through sputtering. A thickness of the intermediate layer is preferably set in a range of greater than or equal to 10 nm and less than or equal to 200 nm. Alternatively, the intermediate layer may be omitted. 
     The μc-Si unit in which a p-type layer, an i-type layer, and an n-type layer are sequentially layered is formed over the intermediate layer. The μc-Si unit may be formed through plasma CVD in which mixture gas of silicon-containing gas such as silane (SiH 4 ), disilane (Si 2 H 6 ), and dichlorsilane (SiH 2 Cl 2 ), carbon-containing gas such as methane (CH 4 ), p-type dopant-containing gas such as diborane (B 2 H 6 ), n-type dopant containing gas such as phosphine (PH 3 ), and dilution gas such as hydrogen (H 2 ) is made into plasma and a film is formed. 
     For the plasma CVD, similar to the a-Si unit, for example, an RF plasma CVD of 13.56 MHz may be preferably applied. The RF plasma CVD may be of the parallel plate type. Alternatively, a structure may be employed in which a gas shower hole for supplying mixture gas of the materials is formed on a side, of the electrodes of the parallel plate type, on which the transparent insulating substrate 10 is not placed. An input power density of plasma is preferably greater than or equal to 5 mW/cm 2  and less than or equal to 1500 mW/cm 2 . 
     The p-type layer of the μc-Si unit is a microcrystalline silicon layer (μc-Si:H) having a thickness of greater than or equal to 5 nm and less than or equal to 50 nm, and doped with a p-type dopant (such as boron). A film characteristic of the p-type layer may be changed by adjusting the mixture ratios of the silicon-containing gas, the p-type dopant-containing gas, and the dilution gas, pressure, and plasma generating high-frequency power. 
     The i-type layer of the μc-Si unit is a microcrystalline silicon layer (μc-Si:H) formed over the p-type layer, having a thickness of greater than or equal to 500 nm and less than or equal to 5000 nm, and not doped with any dopant. A film characteristic of the i-type layer may be changed by adjusting the mixture ratios of the silicon-containing gas and the dilution gas, pressure, and plasma generating high-frequency power. 
     The i-type layer of the μc-Si unit is formed in a film formation chamber having a substrate heater, a substrate carrier, and a plasma electrode built into the chamber. The film formation chamber is vacuumed by a vacuum pump. The substrate heater is placed such that a heating surface opposes the plasma electrode. The transparent insulating substrate  10  placed on the substrate carrier is transported between the plasma electrode and the substrate heater in an orientation to face the plasma electrode. The plasma electrode is electrically connected to a plasma power supply through a matching box provided outside of the film formation chamber. In such a structure, while the material gas is supplied at a flow rate and a pressure appropriate to the film formation condition, power is input from the plasma power supply to the plasma electrode, so that plasma of the material gas is generated in the gap between the plasma electrode and the transparent insulating substrate  10  and a film is formed over the surface of the transparent insulating substrate  10 . 
     The i-type layer of the μc-Si unit has, in the surface of the incidence of light of the tandem-type solar cell module  100 , a first region  30  and a second region  32  having different crystallinity from each other. For example, in many cases, as shown in  FIG. 4 , a center region in the surface of the incidence of light of the tandem-type solar cell module  100  is the first region  30  having a high crystallinity (a region surrounded by a dot-and-chain line in  FIG. 4 ), and a peripheral region is the second region  32  having a relatively lower crystallinity than the first region  30  (a region surrounded by a solid line and a dot-and-chain line in  FIG. 4 ). 
     The crystallinity is measured using Raman spectroscopy after a microcrystalline silicon film is formed to a thickness of  600  nm over a glass substrate under the same film formation conditions as the conditions when the i-type layer (i-type layer of the μc-Si unit) of the tandem-type solar cell module  100  is formed. More specifically, light is irradiated to the respective regions in the surface of the microcrystalline silicon film formed over the glass substrate, and a crystallization percentage X (%) is calculated using the following equation (1) based on a peak intensity I 520  around 520 cm  −1  derived from crystalline silicon and a peak intensity I 480  around 480 cm −1  derived from amorphous silicon in the Raman scattering spectrum. 
       [Equation 1] 
       Crystallization Percentage×(%)= I   520 /( I   520   +I   480 )   (1)
 
       FIG. 5  shows an example measurement of a distribution of the crystallization percentage in the surface of the i-type layer of the μc-Si unit of the tandem-type solar cell module  100  formed in the present embodiment. The crystallization percentage is measured by a Raman spectroscopy after a microcrystalline silicon film is formed to a thickness of 600 nm over a glass substrate under the same film formation conditions as the conditions for forming the i-type layer of the tandem-type solar cell module  100 . The measurement result of  FIG. 5  shows crystallization percentages in regions A-E of the tandem-type solar cell module  100  shown in  FIG. 4 . As shown in  FIG. 5 , when the crystallization percentage in the second region  32  at the periphery of the surface (regions A and E) is 1, a crystallization percentage of the first region  30  at the center of the surface (regions B, C, and D) is greater than or equal to 1.1, and the maximum crystallization percentage in these regions is approximately 1.2. 
     The n-type layer of the μc-Si unit is formed by layering microcrystalline silicon layers (n-type μc-Si:H) having a thickness of greater than or equal to 5 nm and less than or equal to 50 nm and doped with an n-type dopant (such as phosphorus). A film characteristic of the n-type layer may be changed by adjusting the mixture ratios of the silicon-containing gas, the carbon-containing gas, the n-type dopant-containing gas, and the dilution gas, pressure, and plasma generating high-frequency power. 
     When a plurality of photovoltaic cells are connected in series, the photovoltaic unit  14  is patterned to a strip shape. A YAG laser is irradiated at a position aside from the patterning position of the slit S 1  for separating the transparent conductive film  12  by approximately 50 μm in parallel with the slit S 1 , to form a slit S 3  and pattern the photovoltaic unit  14  in the strip shape. For the YAG laser, for example, a YAG laser having an energy density of 0.7 J/cm 2  and a pulse frequency of 3 kHz is preferably used. 
     The backside electrode  16  is formed over the μc-Si unit. The backside electrode  16  is preferably formed by layering a first backside electrode and a second backside electrode. As the first backside electrode, a transparent conductive oxide (TCO) such as tin oxide (SnO 2 ), zinc oxide (ZnO), and indium tin oxide (ITO) is used. In addition, for the second backside electrode, a metal such as silver (Ag) and aluminum (Al) may be used. The TCO may be formed, for example, through sputtering. The first backside electrode and the second backside electrode are preferably formed to a total thickness of approximately 1000 nm. In addition, it is also preferable to provide unevenness on at least one of the first backside electrode and the second backside electrode for improving the light confinement effect. 
     When a plurality of cells are connected in series, the backside electrode  16  and the photovoltaic unit  14  are patterned into a strip shape. A YAG laser is irradiated at a position aside from the patterning position of the slit S 3  for separating the photovoltaic unit  14  by approximately 50 μm in parallel to the slits S 1  and S 3 , to form a slit S 4  and pattern the backside electrode  16  and the photovoltaic unit  14  in a strip shape. For the YAG laser, a YAG laser having an energy density of 0.7 J/cm 2  and a pulse frequency of 4 kHz is preferably used. 
     In addition, as shown in  FIG. 1 , the YAG laser is irradiated in a manner to overlap the slit S 2  to form a slit S 5 , the backside electrode  16  and the photovoltaic unit  14  are removed, and the photovoltaic cell is separated in parallel. A width of the slit S 5  is preferably narrower than a width of the slit S 2 . In addition, the slit S 5  can be formed under the same conditions as the slit S 4 . 
     Alternatively, a configuration may be employed in which the transparent conductive film  12 , the photovoltaic unit  14 , and the backside electrode  16  are removed, to expose the surface of the transparent insulating substrate  10  at a peripheral portion c of the solar cell module  100 . With this configuration, when a supporting frame or the like is mounted on the solar cell module  100 , electrical insulation from the supporting frame can be more reliably achieved. 
     Because the slits S 2  and S 5  are formed, a structure is obtained in which a plurality of groups of a plurality of photovoltaic cells connected in series are arranged in parallel to each other. The tab electrode  20  is provided to electrically connect in parallel the groups of photovoltaic cells arranged in parallel to each other. The tab electrode  20  is formed in a direction parallel to the slit S 4 . The tab electrode  20  may be formed with a material including a conductive metal such as copper (Cu), silver (Ag), and aluminum (Al). For example, a structure is preferably employed in which a surface of a core line made of copper (Cu) is covered (coated) by a solder. 
     The tab electrode  20  is preferably formed over the backside electrode  16  of an end cell of the plurality of photovoltaic cells connected in series, and electrically connected to the backside electrode  16 . In the tandem-type solar cell module  100  of the present embodiment, the tab electrodes  20  are provided at the cells at both ends of the photovoltaic cells connected in series, for electrical connection of the groups of photovoltaic cells. 
     The tab electrode  22  is provided to electrically connect the tab electrode  20  to the terminal box  24 . The tab electrode  22  is formed in parallel to the slits S 2  and S 5  and from the tab electrode  20  to the terminal box  24 . The insulating tape  18  is formed below the region where the tab electrode  22  is formed so that the plurality of photovoltaic cells connected in series are not connected in parallel by the tab electrode  22 . The tab electrode  22  is provided over the insulating tape  18 . 
     In addition, the tab electrode  20  and the tab electrode  22  may be covered with an insulating tape. Moreover, the surface of the tandem-type solar cell module  100  maybe covered andprotected by EVA which forms a protection member and a back sheet. With such configurations, intrusion of moisture or the like to the photoelectric conversion layer of the tandem-type solar cell module  100  can be prevented. 
     As shown in  FIG. 1 , the tab electrode  22  is placed to overlap the second region  32  of the tandem-type solar cell module  100 . In other words, the tab electrode  22  is formed to overlap not the first region  30  at the center region in the surface of the tandem-type solar cell module  100  and having a high crystallinity, but the second region  32  having a lower crystallinity than the first region  30 . 
     Light entering from the transparent insulating substrate  10  passes through the slit S 4  for separating the backside electrode  16  to the backside, but in the region where the tab electrode  22  is formed, the light transmitting through the slit S 4  is reflected by the tab electrode  22  to the side of the photovoltaic unit  14 . In the present embodiment, because the tab electrode  22  is formed in the second region  32  which is at a module peripheral region in which the microcrystalline silicon film of the i-type layer having a low crystallinity is formed, the light transmitting through the slit S 4  is reused, an amount of generation of current near the region where the tab electrode  22  is formed is increased, and the balance with the amount of generation of the current in the first region  30  which is the center region of the module is improved. With this configuration, more uniform photoelectric conversion efficiency of the photoelectric conversion layer of the tandem-type solar cell module  100  as a whole can be achieved. 
     Second Preferred Embodiment  
     In the tandem-type cell module  100  described above in the first preferred embodiment, it is preferable that, in the i-type layer of the microcrystalline silicon of the photovoltaic unit  14  (i-type layer of the μc-Si unit), a lifetime of a carrier in the first region  30  is lower than a lifetime of a carrier in the second region  32 . 
     When the lifetime of the carrier in the first region  30  is assumed to be 1, the lifetime of the carrier in the second region  32  is preferably greater than or equal to 1.05. The lifetime of the carrier is measured using Microwave Photo Conductivity Decay (p-PCD) after a microcrystalline silicon film is formed to a thickness of 600 nm over a glass substrate under the same film formation conditions as the conditions for forming the i-type layer of the tandem-type solar cell module  100 . More specifically, a method described in “Detection of Heavy Metal Contamination in Semiconductor Processes using a Carrier Lifetime Measurement System” (Kobe Steel Engineering Reports, Vol. 52, No. 2, September, 2002, pp. 87 - 93) is applied. In the μ-PCD, light is instantaneously irradiated in the regions in the surface of the microcrystalline silicon film formed over the glass substrate, and decay of the carrier due to the recombination occurring in the film by the light is measured as a change of reflection intensity of a microwave light which is separately irradiated on the microcrystalline silicon film. 
     The i-type layer of the μc-Si unit can be formed by employing different states of the plasma of the material gas for the first region  30  and the second region  32  during the film formation. In a first method, film is formed in a state where the potentials of the regions of the transparent conductive film  12  patterned in the strip shape by the slit S 1  are set different from each other. For example, plasma CVD is applied while the transparent conductive film  12  corresponding to the first region  30  is set in a floating state and the transparent conductive film  12  corresponding to the second region  32  is grounded, to obtain the in-surface distribution of the i-type layer. 
     In a second method, different shapes may be employed for the plasma electrode corresponding to the first region  30  and the second region  32 , to adjust the state of the generated plasma of the material gas within the surface. In a third method, different shapes, sizes, numbers, etc. may be employed for the gas shower holes formed in the plasma electrode corresponding to the first region  30  and the second region  32 , to adjust the state of the generated plasma of the material gas. 
       FIG. 6  shows an example measurement of the distribution of the lifetime of the carrier in the surface of the i-type layer of the μc-Si unit of the tandem-type solar cell module  100  formed in the present embodiment. The lifetime of the carrier is measured by applying the μ-PCD after a microcrystalline silicon film is formed to a thickness of 600 nm over a glass substrate under the same film formation conditions as the conditions for forming the i-type layer of the tandem-type solar cell module  100 . The measurement result of  FIG. 6  shows the lifetimes in regions A-E of the tandem-type solar cell module  100  shown in  FIG. 4 . As shown in  FIG. 6 , when the lifetime of the first region  30  at the center of the surface (region C) is 1, the lifetime of the second region  32  at the periphery of the surface (regions A and E) is increased to approximately 1.14. 
     As described, in the present embodiment, in a surface of the tandem-type solar cell module  100 , the first region  30  having a high crystallization percentage and a low lifetime of carrier, and the second region  32  having a lower crystallization percentage than the first region  30  and a high lifetime of carrier, are placed in the i-type layer of the μc-Si unit. 
     With this configuration, in a region where the crystallinity of the i-type layer is reduced due to the film formation conditions, such as the periphery of the substrate, the lifetime of the carrier can be increased, and in a region where the crystallinity is higher than such a region, the lifetime of the carrier can be shortened. As a result, more uniform photoelectric conversion efficiency can be achieved in the surface of the tandem-type solar cell module  100 . Such a characteristic is advantageous when the tandem-type solar cell module  100  is to be made into a module. 
     When a panel of the tandem-type solar cell module  100  is formed, even when moisture enters from the outside at the peripheral portion of the substrate, because the crystallinity of the i-type layer at the peripheral portion is low, possibility of detachment can be further reduced.