Summary of the invention
The problem that the present invention solves is to provide a kind of monocrystaline silicon solar cell and preparation method thereof, improves the conversion efficiency of monocrystaline silicon solar cell.
For addressing the above problem, technical scheme of the present invention has proposed a kind of manufacture method of monocrystaline silicon solar cell, comprising: substrate is provided, and described substrate is first kind monocrystalline silicon piece; The Second Type doping is carried out on the surface of described substrate, formed first kind monocrystalline silicon layer and the Second Type monocrystalline silicon layer that is positioned at described first kind monocrystalline silicon layer upper surface; Surface at described Second Type monocrystalline silicon layer forms the first stressor layers; At described first stressor layers surface formation the first electrode, at lower surface formation second electrode of described first kind monocrystalline silicon layer.
Optionally, described first kind monocrystalline silicon layer is P type layer, and described Second Type monocrystalline silicon layer is the N-type layer, and described the first stressor layers has tensile stress.
Optionally, described first kind monocrystalline silicon layer is the N-type layer, and described Second Type monocrystalline silicon layer is P type layer, and described the first stressor layers has compression.
Optionally, described the first stressor layers comprises silicon nitride film or silicon oxide film.
Optionally, the formation technique of described the first stressor layers comprises thermal chemical vapor deposition or plasma enhanced chemical vapor deposition.
Optionally, form described formation method with first stressor layers of tensile stress and comprise: using plasma strengthens chemical vapor deposition method, wherein, and NH2And SiH4As reacting gas, inert gas is as carrier gas, and reaction temperature is 200 ℃ ~ 500 ℃, and reaction pressure is 100mTorr ~ 200mTorr, and a power is provided is 10W~100W, and frequency is the radio frequency power source of 10MHz ~ 15MHz.
Optionally, form described formation method with first stressor layers of compression and comprise: using plasma strengthens chemical vapor deposition method, wherein, and NH2And SiH4As reacting gas, inert gas is as carrier gas, and reaction temperature is 200 ℃ ~ 500 ℃, and reaction pressure is 100mTorr ~ 200mTorr, and a power is provided is 10W~100W, and frequency is the low frequency power source of 50KHz ~ 500kHz.
Optionally, the thickness of described the first stressor layers is 0.5nm ~ 100nm, and the number range of the stress of described the first stressor layers is 200MPa ~ 1000MPa.
Optionally, also be included in lower surface formation second stressor layers of first kind monocrystalline silicon layer.
Optionally, also comprise: after the first stressor layers surface formation anti-reflecting layer, then at described anti-reflecting layer surface formation the first electrode.
Optionally, also comprise: after the Second Type monocrystalline surface forms anti-reflecting layer, then in described anti-reflecting layer surface formation the first stressor layers.
Optionally, in first kind monocrystalline silicon layer and Second Type monocrystalline silicon layer, the scope of doping ion concentration is 1E10/cm3~ 1E20/cm3
For addressing the above problem, the invention allows for a kind of monocrystaline silicon solar cell, comprising: first kind monocrystalline silicon layer and the Second Type monocrystalline silicon layer that is positioned at described first kind monocrystalline silicon layer upper surface; Be positioned at first stressor layers on the surface of described Second Type monocrystalline silicon layer; Be positioned at first electrode on described the first stressor layers surface; Be positioned at the second electrode of first kind monocrystalline silicon layer lower surface.
Optionally, described first kind monocrystalline silicon layer is P type layer, and described Second Type monocrystalline silicon layer is the N-type layer, and described the first stressor layers has tensile stress.
Optionally, described first kind monocrystalline silicon layer is the N-type layer, and described Second Type monocrystalline silicon layer is P type layer, and described the first stressor layers has compression.
Optionally, described the first stressor layers comprises silicon nitride film or silicon oxide film.
Optionally, the thickness of described the first stressor layers is 0.5nm ~ 100nm, and the number range of the stress of described the first stressor layers is 200MPa ~ 1000MPa.
Optionally, the second stressor layers that also comprises the surface that is positioned at first kind monocrystalline silicon layer.
Optionally, also comprise: at the anti-reflecting layer between described the first electrode and the first stressor layers or the anti-reflecting layer between described Second Type monocrystalline silicon layer and the first stressor layers.
Optionally, in first kind monocrystalline silicon layer and Second Type monocrystalline silicon layer, the scope of doping ion concentration is 1E10/cm3~ 1E20/cm3
Compared with prior art, the present invention has the following advantages:
Technical scheme of the present invention is in Second Type monocrystalline surface formation first stressor layers of described monocrystaline silicon solar cell.make stereo-motion in the process that charge carrier in described Second Type monocrystalline silicon layer flows to the first electrode in three-dimensional in the Second Type monocrystalline silicon layer, the first stressor layers of described Second Type monocrystalline surface can make the Second Type monocrystalline silicon layer be subject to effect of stress, improve the mobility of charge carrier in the Second Type monocrystalline silicon layer, thereby reduce light induced electron or photohole after the process PN junction, in the process of the first drift electrode by compound probability, improve to arrive the electronics at the first electrode place or the quantity in hole, improve total current density of solar cell, thereby improve the conversion efficiency of monocrystaline silicon solar cell.
Further, if described first kind monocrystalline silicon layer is P type layer, the Second Type monocrystalline silicon layer is the N-type layer, and the first stressor layers of described Second Type monocrystalline surface has tensile stress.Make stereo-motion in the process that electronics in described Second Type monocrystalline silicon layer flows to the first electrode in three-dimensional in the Second Type monocrystalline silicon layer, described the first stressor layers with tensile stress makes the N-type layer be subject to the tensile stress effect, can improve the mobility of electronics in described N-type layer, thereby reduce the light induced electron that produces in P type layer, after the process PN junction, in the N-type layer in the process of the first drift electrode, by compound probability, improve to arrive the electron amount at the first electrode place, thereby improve the conversion efficiency of monocrystalline silicon thin film solar cell.If described first kind monocrystalline silicon layer is P type layer, the Second Type monocrystalline silicon layer is the N-type layer, and the first stressor layers of described Second Type monocrystalline surface has compression.Make stereo-motion in the process that flows to the first electrode in hole in described Second Type monocrystalline silicon layer in three-dimensional in the Second Type monocrystalline silicon layer, described the first stressor layers with compression makes P type layer be subject to action of compressive stress, improve the mobility in hole in described P type layer, thereby reduce the photohole that produces in the N-type layer, after the process PN junction, in P type layer in the process of the first drift electrode, by compound probability, improve to arrive the number of cavities at the first electrode place, thereby improve the conversion efficiency of monocrystalline silicon thin film solar cell.
Further, technical scheme of the present invention can also form the second stressor layers at the lower surface of first kind monocrystalline silicon layer, improve simultaneously the carrier mobility in first kind monocrystalline silicon layer and Second Type monocrystalline silicon layer, further improve the conversion efficiency of monocrystaline silicon solar cell.
Further, the material that described the first stressor layers adopts is silica or silicon nitride, described silica or silicon nitride film have lower specific refractivity, not only can be subject to effect of stress by Second Type, also help to reduce the monocrystaline silicon solar cell surface to the reflection of sunlight, improve the absorptance of solar cell, need not form again anti-reflecting layer, thereby can save processing step.
Embodiment
As described in the background art, the conversion efficiency of monocrystaline silicon solar cell remains further to be improved at present.
Research is found, the compound direct open circuit voltage that affects solar cell of photo-generated carrier.So charge carrier is in the process of electrode movement, thereby the migration rate of raising charge carrier can effectively reduce the conversion efficiency that the recombination rate of photo-generated carrier improves solar cell.
The present invention proposes a kind of monocrystaline silicon solar cell and preparation method thereof, Second Type monocrystalline surface at described monocrystaline silicon solar cell forms the first stressor layers, carrier mobility in the Second Type monocrystalline silicon layer is improved, thereby improves the conversion efficiency of solar cell.
For above-mentioned purpose of the present invention, feature and advantage can more be become apparent, below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in detail.Described embodiment is only the part of embodiment of the present invention, rather than they are whole.When the embodiment of the present invention was described in detail in detail, for ease of explanation, schematic diagram can be disobeyed general ratio and be done local the amplification, and described schematic diagram is example, and it should not limit protection scope of the present invention at this.The three-dimensional space that should comprise in addition, length, width and the degree of depth in actual fabrication.According to described embodiment, those of ordinary skill in the art belongs to protection scope of the present invention need not obtainable all other execution modes under the prerequisite of creative work.Therefore the present invention is not subjected to the restriction of following public concrete enforcement.
Please refer to Fig. 1, the schematic flow sheet for the manufacture method of monocrystaline silicon solar cell in the present embodiment comprises:
Step S1: substrate is provided, and described substrate is first kind monocrystalline silicon piece;
Step S2: the Second Type doping is carried out on the surface of described substrate, formed first kind monocrystalline silicon layer and the Second Type monocrystalline silicon layer that is positioned at described first kind monocrystalline silicon layer upper surface;
Step S3: the surface at described Second Type monocrystalline silicon layer forms the first stressor layers;
Step S4: at described the first stressor layers surface formation anti-reflecting layer;
Step S5: at described anti-reflecting layer surface formation the first electrode, at lower surface formation second electrode of first kind monocrystalline silicon layer.
Please refer to Fig. 2,substrate 100 is provided, describedsubstrate 100 is first kind monocrystalline silicon piece.
Concrete, describedsubstrate 100 is p type single crystal silicon sheet or n type single crystal silicon sheet, the substrate that adopts in the present embodiment is the p type single crystal silicon sheet, follow-up N doping, the formation N-type layer of carrying out on described p type single crystal silicon sheet.In other embodiments of the invention, described substrate also can be selected the n type single crystal silicon sheet, follow-up P doping, the formation P type layer of carrying out on described n type single crystal silicon sheet.
Described P type single-chip is when forming silicon chip, described silicon chip to be carried out the boron ion doping, can also be described silicon chip to be carried out the doping of one or more ions in boron, gallium or indium.The concentration range of the doping ion of described substrate is 1E10/cm3~ 1E20/cm3
Please refer to Fig. 3, described substrate 100(be please refer to Fig. 1) the surface carry out Second Type doping, form first kindmonocrystalline silicon layer 101 and be positioned at the Second Typemonocrystalline silicon layer 102 of described first kindmonocrystalline silicon layer 101 upper surfaces.
Concrete, if describedsubstrate 100 is the p type single crystal silicon sheet, described substrate being carried out the N-type doping, the first kindmonocrystalline silicon layer 101 of formation is P type layer, the Second Typemonocrystalline silicon layer 102 that is positioned at described first kindmonocrystalline silicon layer 101 upper surfaces is the N-type layer; If described substrate is the n type single crystal silicon sheet, described substrate is carried out the doping of P type, the first kindmonocrystalline silicon layer 101 of formation is the N-type layer, the Second Typemonocrystalline silicon layer 102 that is positioned at described first kindmonocrystalline silicon layer 101 upper surfaces is P type layer.
In the present embodiment, describedsubstrate 100 is the p type single crystal silicon sheet, so described substrate is carried out the N-type doping, the first kindmonocrystalline silicon layer 101 of formation is P type layer, and Second Typemonocrystalline silicon layer 102 is the N-type layer, and described P type layer and N-type layer are in contact with one another, and form PN junction.In the present embodiment, the ion of described N-type doping is phosphorus.Concrete grammar is: substrate is placed in the tubular diffusion furnace quartz container, uses nitrogen to bring phosphorus oxychloride into quartz container under 850 ℃ ~ 900 ℃ high temperature, by phosphorus oxychloride and silicon chip reaction, obtain phosphorus atoms.Through after a while, phosphorus atoms enters the superficial layer of substrate from surrounding, and spreads to the substrate internal penetration by the space between silicon atom, forms the interface of N-type layer and P type layer, namely PN junction.In other embodiments of the invention, described N-type doping ion can also be one or more in phosphorus, arsenic or antimony.The concentration range of the doping ion of described Second Typemonocrystalline silicon layer 102 is 1E10/cm3~ 1E20/cm3, the PN junction junction depth of formation is 0.3 μ m ~ 0.5 μ m.The degree of depth of described N-type diffusion can not be too thick, because diffusion needs concentration gradient just can make impurity spread in substrate.If the described PN junction that diffuses to form is too dark, can cause the serious degeneracy of energy level in surface, make the drops of opening of solar cell, battery efficiency descends.
In other embodiments of the invention, also can carry out P type ion doping to described n type single crystal silicon sheet with the n type single crystal silicon sheet as substrate, form P type layer.Described P type doping ion comprises one or more ions in boron, gallium or indium.In the P type layer that P type ion diffuses to form, the doping content scope is 1E10/cm3~ 1E20/cm3, the PN junction junction depth of formation is 0.3 μ m ~ 0.5 μ m.
In the present embodiment, because light induced electron is done drift motion by first kindmonocrystalline silicon layer 101 to Second Typemonocrystalline silicon layer 102, photohole is taken exercises to first kindmonocrystalline silicon layer 101 by Second Type monocrystalline silicon layer 102.Because electron mass is more much smaller than hole mass, so the same time electronics is longer than the distance of movement of hole, if first kindmonocrystalline silicon layer 101 thickness are less than the thickness of Second-Typemonocrystalline silicon layer 102, the hole does not also move to first kind monocrystalline silicon layer will be fallen by compound, so the thickness of first kindmonocrystalline silicon layer 101 is greater than the thickness of Second Typemonocrystalline silicon layer 102.
Before described substrate being carried out the Second Type doping, at first described substrate is cleaned, remove the impurity of substrate surface, thereby avoid the performance of impurity effect monocrystaline silicon solar cell.
After cleaning, can also prepare matte to described substrate surface, with aqueous slkali, substrate surface is carried out anisotropic etch, form matte at described substrate surface, described matte can improve the contact area of substrate surface and sunlight and reduce sun reflection of light.After the preparation matte, then carry out the Second Type doping.
Please refer to Fig. 4, in described Second Typemonocrystalline silicon layer 102 surface formation thefirst stressor layers 103.
On described Second Typemonocrystalline silicon layer 102 surfaces, form thefirst stressor layers 103, described thefirst stressor layers 103 comprises transparent nonconducting films such as silicon nitride film, silicon oxide film.The formation technique of described thefirst stressor layers 103 can be plasma enhanced chemical vapor deposition (PECVD) or thermal chemical vapor deposition.
In the present embodiment, described Second Typemonocrystalline silicon layer 102 is the N-type layer, has thefirst stressor layers 103 of tensile stress in the surface formation of described N-type layer.In the present embodiment, described thefirst stressor layers 103 is silicon nitride film, and the formation technique of employing is plasma enhanced chemical vapor deposition, and wherein, reacting gas is NH2And SiH4, utilize the inert gases such as Ar as carrier gas, SiH4And NH2Gas flow ratio be 0.1 ~ 4, reaction temperature is 200 ℃ ~ 500 ℃, reaction pressure is 100mTorr ~ 200mTorr, and a power is provided is the radio frequency power source of 10W~100W, frequency is 13.56MHz.The thickness of described thefirst stressor layers 103 is 0.5nm ~ 100nm, has tensile stress, and the tensile stress number range is 200MPa ~ 1000MPa.
Electronics in described Second Type monocrystallinesilicon layer interior 102 is made stereo-motion in three-dimensional in the process that flows to the first electrode.Described thefirst stressor layers 103 with tensile stress makes the N-type layer be subject to the effect of the tensile stress in horizontal plane, the mobility of electronics in the N-type layer is improved, thereby reduce light induced electron through after PN junction in the N-type layer in Drift Process by compound probability, improve to arrive the electron amount at the first electrode place, improve total current density of solar cell, thereby improve the conversion efficiency of solar cell.
In other embodiments of the invention, described Second Typemonocrystalline silicon layer 102 can be also P type layer, has thefirst stressor layers 103 of compression in the surface formation of described P type layer.Described the first stressor layers with compression comprises silicon nitride film or silicon oxide film, and described formation technique with first stressor layers of compression comprises plasma enhanced chemical vapor deposition or thermal chemical vapor deposition.In one embodiment of the invention, described the first stressor layers with compression is silicon nitride film, and the formation technique of employing is plasma enhanced chemical vapor deposition, and wherein, reacting gas is NH2And SiH4, utilize the inert gases such as Ar as carrier gas, SiH4And NH2Gas flow ratio be 0.1 ~ 4, reaction temperature is 200 ℃ ~ 500 ℃, reaction pressure is 100mTorr ~ 200mTorr, the low frequency power source that a power is provided is 10W~100W, frequency is 100KHz.The thickness of described the first stressor layers is 0.5nm ~ 100nm, has compression, and the number range of compression is 200MPa ~ 1000MPa.In the process that flows to the first electrode in the Second Type monocrystalline silicon layer in hole in described Second Type monocrystalline silicon layer, make stereo-motion in three-dimensional, described the first stressor layers with compression, make P type layer be subject to the effect of the compression in horizontal plane, the mobility of photohole in P type layer is improved, thereby reduce photohole after the process PN junction, in P type layer in Drift Process by compound probability, improve to arrive the number of cavities at the first electrode place, thereby improve the conversion efficiency of solar cell.
In other embodiments of the invention, can also form the first stressor layers in first kind monocrystalline surface, lower surface at the Second Type monocrystalline silicon layer forms the second stressor layers, make first kind monocrystalline silicon layer and Second Type monocrystalline silicon layer all be subject to effect of stress, improve simultaneously the mobility of charge carrier in first kind monocrystalline silicon layer and Second Type monocrystalline silicon layer, further improve the conversion efficiency of solar cell.
Please refer to Fig. 5, at described the first stressor layers 103 surface formation anti-reflecting layers 104.
Described
anti-reflecting layer 104 is the transparent material of low-refraction coefficient, for example TiO
2, SiN, SiO, Al
2O
3, SiO
2Or CeO
2Deng.Concrete, can adopt the methods such as PECVD, magnetron sputtering or electron beam evaporation to form described
anti-reflecting layer 104, the thickness range of described
anti-reflecting layer 104 is
In other embodiments of the invention, the silicon nitride film or the silicon oxide film that adopt due to described the first stressor layers 103 have lower specific refractivity, can reduce the reflection to sunlight, can be used as the anti-reflecting layer of Second Type monocrystalline surface, improve solar cell to the absorptivity of sunlight.So can additionally form again describedanti-reflecting layer 104, thereby can reduce processing step.
In other embodiments of the invention, also can first form anti-reflecting layer on Second Typemonocrystalline silicon layer 102 surfaces, and then in described anti-reflecting layer surface formation the first stressor layers, describedanti-reflecting layer 104 is except antireflecting effect, can also play to the Second Type monocrystalline surface effect of passivated surface, reduce the recombination rate of charge carrier.Because the thickness of described anti-reflecting layer is lower, so the Second Type monocrystalline silicon layer can be subject to the effect of stress of the first stressor layers equally, improve the mobility of charge carrier.
Please refer to Fig. 6, at describedanti-reflecting layer 104 surface formation thefirst electrodes 105, at lower surface formationsecond electrode 106 of first kindmonocrystalline silicon layer 101.
The concrete technology that forms described thefirst electrode 105 and thesecond electrode 106 is known for those skilled in the art, does not repeat them here.
According to above-mentioned manufacture method, embodiments of the invention also provide a kind of monocrystaline silicon solar cell that adopts above-mentioned manufacture method to form.
Please refer to Fig. 6, the generalized section of the monocrystaline silicon solar cell that provides for the embodiment of the present invention.
Concrete, comprising: first kindmonocrystalline silicon layer 101 and the Second Typemonocrystalline silicon layer 102 that is positioned at described first kindmonocrystalline silicon layer 101 upper surfaces; Be positioned at first stressor layers 103 on described Second Typemonocrystalline silicon layer 102 surfaces; Be positioned at describedanti-reflecting layer 104 with first stressor layers 103 surfaces of tensile stress; Be positioned atfirst electrode 105 and thesecond electrode 106 that is positioned at described first kindmonocrystalline silicon layer 101 lower surfaces on describedanti-reflecting layer 104 surfaces.
Described first kindmonocrystalline silicon layer 101 is P type layer, and ion doping concentration is 1E10/cm3~ 1E20/cm3, the doping ion comprises one or more in boron, gallium or indium; Described Second Typemonocrystalline silicon layer 102 is the N-type layer, and ion doping concentration is 1E10/cm3~ 1E20/cm3, the doping ion comprises one or more in phosphorus, arsenic or antimony.Described the first stressor layers 103 comprises silicon nitride film or silicon oxide film, and thickness is 0.5nm ~ 100nm, and the number range of stress is 200MPa ~ 1000MPa.The material of described anti-reflecting layer is TiO2, SiN, SiO, Al2O3, SiO2Or CeO2In other embodiments of the invention, described anti-reflecting layer can be between the first stressor layers 103 Second Type monocrystalline silicon layers 102.
In other embodiments of the invention, has the second stressor layers between the lower surface of described first kindmonocrystalline silicon layer 101 and thesecond electrode 106, make first kind monocrystalline silicon layer and Second Type monocrystalline silicon layer all be subject to effect of stress, improve simultaneously the mobility of charge carrier in first kind monocrystalline silicon layer and Second Type monocrystalline silicon layer, improve total current density of solar cell, further improve the conversion efficiency of solar cell.
By the explanation of above-described embodiment, should be able to make this area professional and technical personnel understand better the present invention, and can reproduce and use the present invention.Those skilled in the art can be in the situation that do not break away from that the spirit and scope of the invention are done various changes to above-described embodiment and modification is apparent according to described principle herein.Therefore, the present invention should not be understood to be limited to above-described embodiment shown in this article, and its protection range should be defined by appending claims.