CN100485974C - Photoelectromotive force element and manufacturing method thereof - Google Patents

Abstract

The invention relates to a photoelectric motive force element, which comprises one crystal semi-conductive base plate with first conductive type and the semi-conductive layer with the second conductive type, wherein the crystal semi-conductive base plate has the first main surface and the second main surface opposite to the first main surface; the semi-conductive layer is arranged on the first main surface of crystal semi-conducive base plate; the base plate is clamped between the first and second main surfaces, with dividing processing side surface formed by cutting treatment; said side surface is formed by laser processing area and cutting processing area; the laser processing area is the semi-conductive layer not reaching second conductive type, that extending from the second main surface to the first main surface.

Description

The manufacture method of photovoltaic cell and this photovoltaic cell

Cross reference with related application

Japanese patent application formerly 2005-094640 number that the application on March 29th, 2005-100446 number 1 submitted to based on the Japanese patent application of submitting on March 31st, 2005 formerly and the Japanese patent application of submitting on February 14th, 2006 formerly 2006-036005 number, and require their priority, to their full content at this in conjunction with to do reference.

Technical field

The present invention relates to the manufacture method of photovoltaic cell and this photovoltaic cell, this photovoltaic cell possesses: have first interarea and second interarea first conductivity type crystal based semiconductor substrate and be arranged on the semiconductor layer of second conductivity type on first interarea of crystal based semiconductor substrate.

Background technology

In recent years, in order to adapt to consumer demand, seeking the photovoltaic cell of wide variety of sizes always.As the method for the photovoltaic cell of making various sizes, have and use standard-sized substrate to form photovoltaic cell, be divided into the method for desired size thereafter.

Dividing method as above-mentioned photovoltaic cell, for example, open the spy and to have put down in writing following method in the 2001-274441 communique: the predetermined split position irradiating laser that on glass substrate, has formed the photovoltaic cell of transparency electrode, amorphous silicon film and metal electrode from metal electrode one side direction, thus, form the groove of metal electrode, amorphous silicon film and transparency electrode having been removed, along this groove glass substrate is cut then, thereby be divided into the photovoltaic cell of desired size.

On the other hand, in recent years,, use the research and the practicability of the solar cell of crystalline silicons such as monocrystalline silicon and polysilicon actively to carry out as photovoltaic cell.Wherein, have the solar cell of the heterojunction that the combination of amorphous silicon and crystalline silicon is constituted, can form it by the low temperature process below 200 ℃ to engage, and can obtain high conversion efficiency, so gazed at.

Fig. 1 is the schematic section that is used to illustrate an example of above-mentioned solar cell with heterojunction that amorphous silicon and crystalline silicon combination are constituted.Solar cell 50 on a side's of n type crystal based semiconductor substrate 2 interarea, has the structure that forms intrinsic noncrystalline semiconductor layer 3, p type noncrystalline semiconductor layer 4, p side transparent conductive film layer 5 and p side collector electrode 6 successively.And, on the opposing party's of said n type crystal based semiconductor substrate 2 interarea, be formed with intrinsic noncrystalline semiconductor layer 7, n type noncrystalline semiconductor layer 8, n side transparent conductive film layer 9 and n side collector electrode 10 successively.

But, in manufacturing with photovoltaic cell heterojunction, desired size that the combination of amorphous silicon and crystalline silicon is constituted, as the technology of putting down in writing in the above-mentioned document, after forming the groove that collector electrode, noncrystalline semiconductor layer and the intrinsic noncrystalline semiconductor layer that will be scheduled to split position remove by irradiating laser, when this groove is cut apart photovoltaic cell, open circuit voltage V is arranged _OCWith curve factor F.F. (fill factor: fill factor, curve factor) produce situation about descending.

Summary of the invention

One of the present invention is characterised in that, have following main points: possessing crystal based semiconductor substrate with first interarea and first conductivity type of second interarea of the opposition side that is arranged on above-mentioned first interarea, in the photovoltaic cell of the semiconductor layer of second conductivity type on above-mentioned first interarea that is set at above-mentioned crystal based semiconductor substrate, above-mentioned crystal based semiconductor substrate is clamped between above-mentioned first interarea and above-mentioned second interarea, and have by the formed division processing of division processing side, above-mentioned division processing side is by constituting by laser processing formed laser processing zone with by cutting off the formed cut-out machining area of processing, and above-mentioned laser processing zone is the semiconductor layer that does not reach above-mentioned second conductivity type, from the zone of above-mentioned second interarea to above-mentioned first interarea, one side extension.

According to this feature, the laser processing zone is the semiconductor layer that do not reach second conductivity type, from second interarea to the zone that first interarea, one side is extended, thus, can prevent because the heat that laser sends and in the semiconductor layer of second conductivity type, produce microcrystal.Its result can prevent to produce leakage current by microcrystal, thereby can prevent open circuit voltage V _OCDecline with curve factor F.F..

One of the present invention is characterised in that, have following main points: in above-mentioned feature, the semiconductor layer of above-mentioned second conductivity type has from the structure of the conductive membrane of the noncrystalline semiconductor layer of above-mentioned first interarea of above-mentioned crystal based semiconductor substrate lamination second conductivity type successively and second conductivity type.

One of the present invention is characterised in that, have following main points: in above-mentioned feature, photovoltaic cell also has the semiconductor layer of first conductivity type on above-mentioned second interarea that is arranged on above-mentioned crystal based semiconductor substrate, the semiconductor layer of above-mentioned first conductivity type has from the structure of the conductive membrane of the noncrystalline semiconductor layer of above-mentioned second interarea of above-mentioned crystal based semiconductor substrate lamination first conductivity type successively and first conductivity type.

One of the present invention is characterised in that to have following main points: in above-mentioned feature, at least one side in the noncrystalline semiconductor layer of above-mentioned second conductivity type and the noncrystalline semiconductor layer of above-mentioned first conductivity type comprises the noncrystalline semiconductor layer of intrinsic.

One of the present invention is characterised in that to have following main points: in above-mentioned feature, above-mentioned cut-out processing is bending and cutting processing; On the boundary line of above-mentioned laser processing zone and above-mentioned cut-out machining area, above-mentioned laser processing zone has to the side-prominent a plurality of protuberances of above-mentioned first interarea; At above-mentioned cut-out machining area, as starting point, be formed with above-mentioned bending and cutting and add the stress that produces man-hour and concentrate vestige with the raised part in above-mentioned laser processing zone territory.

One of the present invention is characterised in that to have following main points: in above-mentioned feature, the average height of raised part is more than the 15 μ m.

One of the present invention is characterised in that to have following main points: in above-mentioned feature, the equispaced of raised part is 0.2 times～3.0 times of average height of raised part.

One of the present invention is characterised in that to have following main points: in above-mentioned feature, the average length from above-mentioned second interarea to the top of raised part is more than 50% of length from above-mentioned second interarea to above-mentioned first interarea.

One of the present invention is characterised in that, have following main points: possess manufacture method, comprise: the operation A that on above-mentioned first interarea of above-mentioned crystal based semiconductor substrate, forms the semiconductor layer of second conductivity type with first interarea and photovoltaic cell of the crystal based semiconductor substrate of first conductivity type of second interarea of the opposition side that is arranged on above-mentioned first interarea; From the above-mentioned second interarea side irradiating laser of above-mentioned crystal based semiconductor substrate, the process B of the groove that form the semiconductor layer do not reach above-mentioned second conductivity type, extends from above-mentioned second interarea to the above-mentioned first interarea side; Cut off along above-mentioned groove with semiconductor layer above-mentioned crystal based semiconductor substrate and above-mentioned second conductivity type, thus the operation C that the semiconductor layer of above-mentioned crystal based semiconductor substrate and above-mentioned second conductivity type is cut apart.

One of the present invention is characterised in that, have following main points: in above-mentioned feature, the manufacture method of photovoltaic cell also comprises, form the step D of the semiconductor layer of first conductivity type on above-mentioned second interarea of above-mentioned crystal based semiconductor substrate, above-mentioned process B is the operation of shining above-mentioned laser from semiconductor layer one side of above-mentioned first conductivity type.

One of the present invention is characterised in that, have following main points: in above-mentioned feature, the semiconductor layer of above-mentioned first conductivity type has above-mentioned second interarea from above-mentioned crystal based semiconductor substrate, the structure of the conductive membrane of the noncrystalline semiconductor layer of lamination first conductivity type and first conductivity type successively; The semiconductor layer of above-mentioned second conductivity type has above-mentioned first interarea from above-mentioned crystal based semiconductor substrate, the structure of the conductive membrane of the noncrystalline semiconductor layer of lamination second conductivity type and second conductivity type successively.

One of the present invention is characterised in that to have following main points: in above-mentioned feature, at least one side in the noncrystalline semiconductor layer of above-mentioned second conductivity type and the noncrystalline semiconductor layer of above-mentioned first conductivity type comprises the noncrystalline semiconductor layer of intrinsic.

One of the present invention is characterised in that, have following main points: in above-mentioned feature, above-mentioned process B comprises and forms the operation have to the above-mentioned groove of the side-prominent a plurality of protuberances of above-mentioned first interarea, and above-mentioned operation C comprises the semiconductor layer of above-mentioned crystal based semiconductor substrate and above-mentioned second conductivity type operation along above-mentioned groove bending.

One of the present invention is characterised in that, have following main points: in above-mentioned feature, above-mentioned process B comprises, and controls the pulse frequency of above-mentioned laser and the sweep speed of above-mentioned laser, thereby forms the operation that has to the above-mentioned groove of the side-prominent a plurality of protuberances of above-mentioned first interarea.

Description of drawings

Fig. 1 is the schematic section that is used to illustrate an example of the photovoltaic cell with heterojunction that the combination of amorphous silicon and crystalline silicon is constituted.

Fig. 2 is near the schematic section of the amplification the groove that forms to the photovoltaic cell irradiating laser with heterojunction that the combination of amorphous silicon and crystalline silicon is constituted.

Fig. 3 is the schematic section of structure that is used to illustrate the structure of first execution mode of the present invention.

Fig. 4 is used to illustrate by form the schematic section of the operation of groove on this structure to the structure irradiating laser of first execution mode of the present invention.

Fig. 5 is the schematic section of structure that is used to illustrate the photovoltaic cell of first execution mode of the present invention.

Fig. 6 is the schematic section of structure that is used to illustrate the structure of second execution mode of the present invention.

Fig. 7 is used to illustrate by form the schematic section of the operation of groove on this structure to the structure irradiating laser of second execution mode of the present invention.

Fig. 8 is the schematic section of structure that is used to illustrate the photovoltaic cell of second execution mode of the present invention, is used to illustrate the schematic section of the structure of structure of the present invention.

Fig. 9 is used to illustrate by form the schematic section of the operation of groove on this structure to the structure irradiating laser of comparative example 1.

Figure 10 is the schematic section of structure that is used to illustrate the photovoltaic cell of comparative example 1, is used to illustrate the schematic section of the structure of structure of the present invention.

Figure 11 is used to illustrate by form the schematic section of the operation of groove on this structure to the structure irradiating laser of comparative example 2.

Figure 12 is the schematic section of structure that is used to illustrate the photovoltaic cell of comparative example 2.

Figure 13 is the side view of the photovoltaic cell of expression the 3rd execution mode of the present invention.

Figure 14 is the stereogram of the photovoltaic cell of expression the 3rd execution mode of the present invention.

Figure 15 cuts off the side view that Fig. 1 of the state that adds man-hour sees from the arrow A direction for expression to the photovoltaic cell of the 3rd execution mode of the present invention.

The plane graph of the position that Figure 16 cuts off the periphery of the photovoltaic cell of the 3rd execution mode of the present invention for expression.

Figure 17 is for cutting off the stereogram of the state that adds man-hour in expression the 3rd execution mode of the present invention.

Figure 18 is the microphotograph of the side of the photovoltaic cell of expression the 3rd execution mode of the present invention.

Figure 19 is the microphotograph of the side of the photovoltaic cell of expression comparative example.

Figure 20 is and the corresponding side view of the microphotograph of Figure 18.

Figure 21 is and the corresponding side view of the microphotograph of Figure 19.

Pulse frequency/sweep speed when Figure 22 is the expression laser radiation is to the side view of the influence of the shape in laser processing zone.

Figure 23 is the side view of assay method of average height that is used to illustrate the protuberance in laser processing zone.

Figure 24 is the figure of the relation of the average height of the protuberance in expression laser processing zone and the standardized curve factor.

Figure 25 is the figure of the relation of the value of thickness of the average height/substrate of expression from another interarea to the protuberance top ends and the standardized curve factor.

Figure 26 is the plane graph that is used to illustrate other execution mode of the present invention.

Figure 27 is the plane graph that is used to illustrate other execution mode of the present invention.

Embodiment

Below, with reference to accompanying drawing the result that the inventor concentrates on studies is described.Inventor's discovery, during from p type noncrystalline semiconductor layer 4 one side direction solar cell 50 irradiating lasers, open circuit voltage V _OCF.F. descends with the curve factor, and during from n type noncrystalline semiconductor layer 8 one side irradiating laser, open circuit voltage V _OCF.F. does not descend with the curve factor.Below its reason is described.

Fig. 2 for the expression behind solar cell 50 irradiating lasers, will be by near the schematic diagram in the cross section of the solar cell 50 of the amplification of laser radiation.With Fig. 2 the reason of above-mentioned phenomenon is described.

Shown in arrow L, under the situation of p type noncrystalline semiconductor layer 4 one side irradiating laser, the cross section of solar cell 50 becomes the shape shown in Fig. 2 (a).In Fig. 2 (a), the solar cell of solar cell 50a after by laser radiation, groove 15 is the grooves that form on solar cell 50a by laser radiation.

With reference to Fig. 2 (a), irradiation by laser, on the end face of the solar cell 50a of the position of part of p side collector electrode 6, p side transparent conductive film layer 5, p type noncrystalline semiconductor layer 4, intrinsic noncrystalline semiconductor layer 3 and n type crystal based semiconductor substrate 2 having been removed, the end of the end of intrinsic noncrystalline semiconductor layer 3 and p type noncrystalline semiconductor layer 4, because the influence of the heat of laser radiation and micro-crystallizationization, thereby the resistance of these parts descends.In Fig. 2 (a), crystallite body 3a is the crystallite body of intrinsic noncrystalline semiconductor layer 3, and crystallite body 4a is the crystallite body of p type noncrystalline semiconductor layer 4.Shown in Fig. 2 (a), crystallite body 3a with the interface 51 of n type crystal based semiconductor substrate 2 on, join with n type crystal based semiconductor substrate 2.Crystallite body 4a with the interface 52 of p side transparent conductive film layer 5 on, join with p side transparent conductive film layer 5.Because the resistance of crystallite body 3a and crystallite body 4a is little, and p type noncrystalline semiconductor layer 4 and n type crystal based semiconductor substrate 2 have opposite conduction type, so, leakage current can pass through crystallite body 4a, crystallite body 3a and interface 51, flows between p type noncrystalline semiconductor layer 4 and n type crystal based semiconductor substrate 2.Therefore, in such solar cell 50a, open circuit voltage V _OCReduce with curve factor F.F..

Relative therewith, shown in arrow L, under the situation of n type noncrystalline semiconductor layer 8 one side irradiating laser, the cross section of solar cell 50 becomes the shape shown in Fig. 2 (b).At Fig. 2

(b) in, the solar cell of solar cell 50b after by laser radiation, groove 15 is the grooves that form on solar cell 50b by laser radiation.

The cross sectional shape of solar cell 50b in this case, except replacing p type noncrystalline semiconductor layer 4 and crystallite body 4a thereof with n type noncrystalline semiconductor layer 8 and crystallite body 8a thereof, replacing intrinsic noncrystalline semiconductor layer 3 and the crystallite body 3a thereof, identical with the situation of Fig. 2 (a) with intrinsic noncrystalline semiconductor layer 7 and crystallite body 7a thereof.Shown in Fig. 2 (b), crystallite body 7a with the interface 53 of n type crystal based semiconductor substrate 2 on, join with n type crystal based semiconductor substrate 2.Crystallite body 8a with the interface 54 of n side transparent conductive film layer 9 on, join with n side transparent conductive film layer 9.Though the resistance of crystallite body 7a and crystallite body 8a is little, but because crystallite body 8a (n type noncrystalline semiconductor layer 8) is identical with the conductivity type of n type crystal based semiconductor substrate 2, so leakage current can not pass through crystallite body 8a, crystallite body 7a and interface 53 and flow between n type noncrystalline semiconductor layer 8 and n type crystal based semiconductor substrate 2.Therefore, the open circuit voltage V of this solar cell 50b _OCF.F. can not reduce with the curve factor.

In addition, using p type crystal based semiconductor substrate to replace under the situation of n type crystal based semiconductor substrate 2, during from n type noncrystalline semiconductor layer one side irradiating laser, produce leakage current, open circuit voltage V _OCReduce with curve factor F.F..On the other hand, during from p type noncrystalline semiconductor layer one side irradiating laser, do not produce leakage current, open circuit voltage V _OCF.F. does not reduce with the curve factor.

In other words, by to the solar cell irradiating laser, make in the noncrystalline semiconductor layer that has with the different conductivity types of crystal based semiconductor substrate, not form the low crystallite body of resistance, can make and not produce leakage current, open circuit voltage V _OCThe solar cell that is suppressed with the reduction of curve factor F.F..

Promptly, in the interarea of crystal based semiconductor substrate, from with the interarea one side irradiating laser of the interarea opposition side that is formed with above-mentioned noncrystalline semiconductor layer, on solar cell, form the groove that does not reach above-mentioned noncrystalline semiconductor layer at least, can make thus and not produce leakage current, open circuit voltage V _OCThe repressed solar cell of reduction with curve factor F.F..So, from with the noncrystalline semiconductor layer one side irradiating laser of crystal based semiconductor substrate same conductivity, on solar cell, form the groove do not reach at least with the noncrystalline semiconductor layer of the different conductivity types of crystal based semiconductor substrate, can make thus and not produce leakage current, open circuit voltage V _OCThe repressed solar cell of reduction with curve factor F.F..

(first execution mode)

With reference to Fig. 3, Fig. 4 and Fig. 5, the photovoltaic cell and the manufacture method thereof of first execution mode of the present invention described.

At first, make the structure 1 of the heterojunction that noncrystalline semiconductor and the combination of crystal based semiconductor are constituted with structure shown in Figure 3.

Fig. 3 utilizes the schematic section of the structure of the structure that the manufacture method of the photovoltaic cell of first execution mode makes for expression.Structure 1 forms following structure: form first laminated body 11 on first interarea of n type crystal based semiconductor substrate 2, form second laminated body 12 on second interarea relative with first interarea.Can use silicon substrate with monocrystal or polycrystal structure or germanium substrate etc. as crystal based semiconductor substrate.Above-mentioned first laminated body 11 has, and forms intrinsic noncrystalline semiconductor layer 3 successively on first interarea of n type crystal based semiconductor substrate 2, has the structure of p type noncrystalline semiconductor layer 4, p side transparent conductive film layer 5 and the p side collector electrode 6 of the conductivity type different with n type crystal based semiconductor substrate 2.Above-mentioned second laminated body 12 forms intrinsic noncrystalline semiconductor layer 7 successively, has n type noncrystalline semiconductor layer 8, n side transparent conductive film layer 9 and the n side collector electrode 10 of the conductivity type identical with n type crystal based semiconductor substrate 2 on second interarea of n type crystal based semiconductor substrate 2.Can use silicon or germanium etc. as the noncrystalline semiconductor substrate.

Intrinsic noncrystalline semiconductor layer 3, p type noncrystalline semiconductor layer 4, intrinsic noncrystalline semiconductor layer 7 and n type noncrystalline semiconductor layer 8 can use plasma CVD method to form respectively.Tin indium oxide) in addition, p side transparent conductive film layer 5 and n side transparent conductive film layer 9 can use ITO (IndiumTin Oxide: the conductive film of light transmission such as.P side collector electrode 6 and n side collector electrode 10 can use metals such as silver, can use silk screen print method, vacuum vapour deposition, sputtering method etc. to form pattern respectively.

Then, with reference to Fig. 4, to by to above-mentioned structure 1 irradiating laser, describe with the operation that on this structure 1, forms groove.Thereby Fig. 4 is for representing by formed the schematic section of the structure 13 of groove on structure 1 to structure shown in Figure 31 irradiating laser.As shown in Figure 4, the above-mentioned second interarea side from n type crystal based semiconductor substrate 2, under the situation of first execution mode, promptly from comprising above-mentioned second laminated body, 12 1 sides of n type noncrystalline semiconductor layer 8 with conductivity type identical with n type crystal based semiconductor substrate 2, shown in arrow L, to structure 1 irradiating laser, thus, in second laminated body 12 and n type crystal based semiconductor substrate 2, form groove 15, produce structure 13.

In the first embodiment, as shown in Figure 4, groove 15 forms on n side collector electrode 10, n side transparent conductive film layer 9, n type noncrystalline semiconductor layer 8, intrinsic noncrystalline semiconductor layer 7 and n type crystal based semiconductor substrate 2, but as long as no show has the p type noncrystalline semiconductor layer 4 of the conductivity type different with n type crystal based semiconductor substrate 2, the degree of depth of groove 15 can suitably be chosen as, the degree of depth that can easily carry out of cutting apart along groove 15 of carrying out after groove 15 forms.

At this moment, adjust the laser irradiation conditions such as irradiation time, irradiation energy of laser, make to stop at groove 15 in the n type crystal based semiconductor substrate 2 and make it not reach p type noncrystalline semiconductor layer 4 with conductivity type different with this n type crystal based semiconductor substrate 2.If reaching groove 15, irradiating laser has the p type noncrystalline semiconductor layer 4 of the conductivity type different with said n type crystal based semiconductor substrate 2, then this p type noncrystalline semiconductor layer 4 forms the low crystallite body of resistance near groove 15, because leakage current flows between this crystallite body and n type crystal based semiconductor substrate 2, so, will cause the open circuit voltage V of the photovoltaic cell that produces _OCDescend with curve factor F.F..

As the laser irradiation condition that is used to form such groove 15, for example, can use the second harmonic equiwavelength of YAG laser and Ar laser to surpass the laser of 400nm, the power of use 1～20W.In addition, as the optical path of laser, can use for example size of 20～200 μ m.By shining the laser of such condition, can form the width groove 15 identical substantially with the optical path of above-mentioned laser.

In the structure of Fig. 4, first laminated body 11 and n type crystal based semiconductor substrate 2 are the structure shown in Fig. 2 (b) near groove 15.Shown in Fig. 2 (b), the end of n type noncrystalline semiconductor layer 8 and intrinsic noncrystalline semiconductor layer 7 is because the influence of the heat that the irradiation of laser produces and micro-crystallizationization forms crystallite body 8a and crystallite body 7a respectively.Though the resistance of this crystallite body 8a and crystallite body 7a is little, because crystallite body 8a is identical conductivity types with n type crystal based semiconductor substrate 2, so, between n type noncrystalline semiconductor layer 8 and n type crystal based semiconductor substrate 2, do not produce leakage current.

Then, as shown in Figure 5, said structure body 13 is cut apart along groove 15.Fig. 5 is cut apart said structure body 13 schematic section of photovoltaic cell 14 resulting, of the present invention along groove 15 for expression.As the method for cutting apart, for example can use with the part of groove 15 as the center, clamp the periphery of structure 13 and with the bending and cutting processing method in its folding gulf, perhaps use method that washer (scrubber), cast-cutting saw (dicing saw) etc. cut off etc. with holding member.Cut apart by this, can produce the photovoltaic cell 14 of desired size.

By above making, as shown in Figure 5, can produce the photovoltaic cell 14 that at least one side of being clamped by second interarea of first interarea of n type crystal based semiconductor substrate 2 and this first interarea opposition side is formed by division processing face 18.At this, this division processing face 18 is made of laser processing zone 16 and cut-out machining area 17, laser processing zone 16 from above-mentioned first interarea of the above-mentioned second interarea side direction extend but no show have the conductivity type different with said n type crystal based semiconductor substrate 2 p type noncrystalline semiconductor layer 4, form by laser processing, cut off machining area 17 and extend, form by cutting off from the above-mentioned second interarea side of the above-mentioned first interarea side direction.

According to first execution mode, can make and have heterojunction that the combination of noncrystalline semiconductor and crystal based semiconductor is constituted, between noncrystalline semiconductor and crystal based semiconductor, do not have leakage current flow, open circuit voltage V _OCWith the decline of curve factor F.F. photovoltaic cell that be suppressed, desired size.

(second execution mode)

At first, use Fig. 6, Fig. 7 and schematic section shown in Figure 8, the structure of the photovoltaic cell of the manufacture method manufacturing of using second execution mode is described.

At first, make the structure 23 of the heterojunction that noncrystalline semiconductor and the combination of crystal based semiconductor are constituted with structure shown in Figure 6.

Fig. 6 utilizes the schematic section of the structure of the structure that the manufacture method of the photovoltaic cell of second execution mode makes for expression.Structure 23 has following structure: form first laminated body 21 on first interarea of the crystal based semiconductor substrate 20 of p type, form second laminated body 22 on second interarea relative with first interarea.Can use silicon substrate with monocrystal or polycrystal structure or germanium substrate etc. as crystal based semiconductor substrate.Above-mentioned first laminated body 21 has, and forms intrinsic noncrystalline semiconductor layer 7 successively on first interarea of p type crystal based semiconductor substrate 20, has the structure of n type noncrystalline semiconductor layer 8, n side transparent conductive film layer 9 and the n side collector electrode 10 of the conductivity type different with p type crystal based semiconductor substrate 20.Above-mentioned second laminated body 22 forms intrinsic noncrystalline semiconductor layer 3 successively, has p type noncrystalline semiconductor layer 4, p side transparent conductive film layer 5 and the p side collector electrode 6 of the conductivity type identical with p type crystal based semiconductor substrate 20 on second interarea of p type crystal based semiconductor substrate 20.Can use silicon or germanium etc. as the noncrystalline semiconductor substrate.

The manufacture method of structure 23, except n type crystal based semiconductor substrate 2 replaces with p type crystal based semiconductor substrate 20, n type noncrystalline semiconductor layer 8 replaces with p type noncrystalline semiconductor layer 4, p type noncrystalline semiconductor layer 4 replaces with n type noncrystalline semiconductor layer 8, intrinsic noncrystalline semiconductor layer 7 replaces with intrinsic noncrystalline semiconductor layer 3, intrinsic noncrystalline semiconductor layer 3 replaces with intrinsic noncrystalline semiconductor layer 7, n side transparent conductive film layer 9 replaces with p side transparent conductive film layer 5, p side transparent conductive film layer 5 replaces with n side transparent conductive film layer 9, n side collector electrode 10 replaces with p side collector electrode 6, p side collector electrode 6 replaces with outside the n side collector electrode 10, and other is identical with the manufacture method of structure 1 in first execution mode.

Then, with reference to Fig. 7, to by to above-mentioned structure 23 irradiating lasers, describe with the operation that in this structure, forms groove.Thereby Fig. 7 is for representing by formed the schematic section of the structure 24 of groove on structure 23 to structure shown in Figure 6 23 irradiating lasers.As shown in Figure 7, the above-mentioned second interarea side from p type crystal based semiconductor substrate 20, under the situation of second execution mode, promptly from comprising above-mentioned second laminated body, 22 1 sides of p type noncrystalline semiconductor layer 4 with conductivity type identical with p type crystal based semiconductor substrate 20, shown in arrow L, to structure 23 irradiating lasers, thus, in second laminated body 22 and p type crystal based semiconductor substrate 20, form groove 15, produce structure 24.

As the laser irradiation condition that is used to form such groove 15, identical with the situation of first execution mode.

At this moment, adjust the laser irradiation conditions such as irradiation time, irradiation energy of laser, make to stop at groove 15 in the p type crystal based semiconductor substrate 20 and make it not reach n type noncrystalline semiconductor layer 8 with conductivity type different with this p type crystal based semiconductor substrate 20.If reaching groove 15, irradiating laser has the n type noncrystalline semiconductor layer 8 of the conductivity type different with above-mentioned p type crystal based semiconductor substrate 20, then this n type noncrystalline semiconductor layer 8 forms the low crystallite body of resistance near groove 15, because leakage current flows between this crystallite body and p type crystal based semiconductor substrate 20, so, will cause the open circuit voltage V of the photovoltaic cell that produces _OCDescend with curve factor F.F..

In second execution mode, as shown in Figure 7, groove 15 forms on p side collector electrode 6, p side transparent conductive film layer 5, p type noncrystalline semiconductor layer 4, intrinsic noncrystalline semiconductor layer 3 and p type crystal based semiconductor substrate 20, but as long as no show has the n type noncrystalline semiconductor layer 8 of the conductivity type different with p type crystal based semiconductor substrate 20, the degree of depth of groove 15 can suitably be chosen as, the degree of depth that can easily carry out of cutting apart along groove 15 of carrying out after groove 15 forms.

In the structure of Fig. 7, near the groove 15 of second laminated body 22 and p type crystal based semiconductor substrate 20, be the structure that the n type crystal based semiconductor substrate 2 among Fig. 2 (a) is replaced with p type crystal based semiconductor substrate 20.In this case, the end of p type noncrystalline semiconductor layer 4 and intrinsic noncrystalline semiconductor layer 3 is because the influence of the heat that laser radiation produces and micro-crystallizationization forms crystallite body 4a and crystallite body 3a respectively.Though the resistance of this crystallite body 4a and crystallite body 3a is little, because crystallite body 4a is identical with the conductivity type of p type crystal based semiconductor substrate 20, so between p type noncrystalline semiconductor layer 4 and p type crystal based semiconductor substrate 20, can not produce leakage current.

Then, as shown in Figure 8, cut apart said structure body 24 along groove 15.The method of cutting apart is identical with the situation of first execution mode.Cut apart by this, can produce the photovoltaic cell 25 of desired size.

According to second execution mode, can make and have heterojunction that the combination of noncrystalline semiconductor and crystal based semiconductor is constituted, between noncrystalline semiconductor and crystal based semiconductor, do not have leakage current flow, open circuit voltage V _OCWith the decline of curve factor F.F. photovoltaic cell that be suppressed, desired size.

[embodiment]

(embodiment 1)

Below, with reference to Fig. 3, Fig. 4 and Fig. 5, an example of the manufacture method of the photovoltaic cell of above-mentioned first execution mode is described.

At first, resistivity is about 1 Ω cm, size for after 10.4cm is square, thickness is about 200 μ m n type crystal based semiconductor substrate 2 cleans, is arranged in the vacuum chamber, be heated to 170 ℃.Then, in above-mentioned chamber, import hydrogen, make it carry out plasma discharge, carried out the interface processing of second interarea of n type crystal based semiconductor substrate 2 thus.

To chamber in import SiH thereafter, ₄Gas and hydrogen utilize plasma CVD method, and forming thickness on second interarea of above-mentioned n type crystal based semiconductor substrate 2 is the intrinsic noncrystalline semiconductor layer 7 of 10nm.Then, in chamber, import SiH ₄Gas, PH ₃Gas and hydrogen utilize plasma CVD method, and forming thickness on intrinsic noncrystalline semiconductor layer 7 is the n type noncrystalline semiconductor layer 8 of 5nm.

Next, the n type crystal based semiconductor substrate 2 that will be formed with above-mentioned intrinsic noncrystalline semiconductor layer 7 and n type noncrystalline semiconductor layer 8 takes out from chamber, after being arranged in the chamber once more, be heated to 170 ℃, to carrying out the identical processing of interface processing with the second above-mentioned interarea with right first interarea of second principal phase.

To chamber in import SiH thereafter, ₄Gas and hydrogen utilize plasma CVD method, and forming thickness on first interarea of above-mentioned n type crystal based semiconductor substrate 2 is the intrinsic noncrystalline semiconductor layer 3 of 10nm.Then, in chamber, import SiH ₄Gas, B ₂H ₆Gas and hydrogen utilize plasma CVD method, and forming thickness on this intrinsic noncrystalline semiconductor layer 3 is the p type noncrystalline semiconductor layer 4 of 5nm.

The membrance casting condition of above noncrystalline semiconductor layer is shown in table 1.In the table 1, " i type " expression intrinsic noncrystalline semiconductor layer 3 and intrinsic noncrystalline semiconductor layer 7, " p type " expression p type noncrystalline semiconductor layer 4, " n type " expression n type noncrystalline semiconductor layer 8.In addition, B ₂H ₆And PH ₃By H ₂Gas is diluted to 2%, 1% respectively.

Table 1

Then, on the n type noncrystalline semiconductor layer 8 and p type noncrystalline semiconductor layer 4 that form on two interareas of n type crystal based semiconductor substrate 2, utilize sputtering method to form the n side transparent conductive film layer 9 and the p side transparent conductive film layer 5 that by ITO constitute of thickness for 100nm.

Then, on the n side transparent conductive film layer 9 that the second interarea side of n type crystal based semiconductor substrate 2 forms and on the p side transparent conductive film layer 5 that the first interarea side forms, the n side collector electrode 10 and the p side collector electrode 6 that utilize the silk screen print method coating to constitute by silver paste (paste), under about 180 ℃, fired about 1 hour afterwards, make the silver paste sclerosis.Thus, finish second laminated body 12 and first laminated body 11.Like this, just produced structure 1.

Then,, structure is removed by the part of laser radiation, thus, on structure 1, formed groove to above-mentioned structure 1 irradiating laser.

At this moment, using the laser optical path is 50 μ m, the wavelength YAG laser as 1064nm, uses the power of 3～5W, as shown in Figure 4, along the direction of arrow L, from second laminated body, 12 1 sides, promptly from the second interarea side of n type crystal based semiconductor substrate 2, to structure 1 irradiating laser.By carrying out such laser radiation, as shown in Figure 4, first laminated body 11 and n type crystal based semiconductor substrate 2 are removed, on structure 1, form groove 15 thus, produce structure 13.By adjusting the illuminate condition of laser, formed the groove 15 that the degree of depth does not reach the p type noncrystalline semiconductor layer 4 with conductivity type different with n type crystal based semiconductor substrate 2.The degree of depth of this groove 15 is about 60 μ m, and the width of groove 15 and the optical path of above-mentioned laser are roughly the same.

At last, by to structure 13 stress applications, structure 13 is mechanically cut apart along above-mentioned groove 15.Cut apart by this, produced the photovoltaic cell 14 (Fig. 5) of desired size.

By above making, as shown in Figure 5, can produce the photovoltaic cell 14 that at least one side of being clamped by second interarea of first interarea of n type crystal based semiconductor substrate 2 and this first interarea opposition side is formed by division processing face 18.At this, this division processing face 18 is made of laser processing zone 16 and cut-out machining area 17, laser processing zone 16 from above-mentioned first interarea of the above-mentioned second interarea side direction extend but no show have the conductivity type different with said n type crystal based semiconductor substrate 2 p type noncrystalline semiconductor layer 4, form by laser processing, cut off machining area 17 and extend, form by cutting off from the above-mentioned second interarea side of the above-mentioned first interarea side direction.

(embodiment 2)

Below, with reference to Fig. 6, Fig. 7 and Fig. 8, an example of the manufacture method of the photovoltaic cell of the second above-mentioned execution mode is described.

At first, resistivity is about 1 Ω cm, size for after 10.4cm is square, thickness is about 200 μ m p type crystal based semiconductor substrate 20 cleans, is arranged in the vacuum chamber, be heated to 170 ℃.

Then, in above-mentioned chamber, import hydrogen, make it carry out plasma discharge, carried out the interface processing of second interarea of p type crystal based semiconductor substrate 20 thus.

To chamber in import SiH thereafter, ₄Gas and hydrogen utilize plasma CVD method, and forming thickness on second interarea of above-mentioned p type crystal based semiconductor substrate 20 is the intrinsic noncrystalline semiconductor layer 3 of 10nm.Then, in chamber, import SiH ₄Gas, B ₂H ₆Gas and hydrogen utilize plasma CVD method, and forming thickness on this intrinsic noncrystalline semiconductor layer 3 is the p type noncrystalline semiconductor layer 4 of 5nm.

Next, the p type crystal based semiconductor substrate 20 that will be formed with above-mentioned intrinsic noncrystalline semiconductor layer 3 and p type noncrystalline semiconductor layer 4 takes out from chamber, after being arranged in the chamber once more, be heated to 170 ℃, to carrying out the identical processing of interface processing with the second above-mentioned interarea with right first interarea of second principal phase.

To chamber in import SiH thereafter, ₄Gas and hydrogen utilize plasma CVD method, and forming thickness on first interarea of above-mentioned p type crystal based semiconductor substrate 20 is the intrinsic noncrystalline semiconductor layer 7 of 10nm.Then, in chamber, import SiH ₄Gas, PH ₃Gas and hydrogen utilize plasma CVD method, and forming thickness on intrinsic noncrystalline semiconductor layer 7 is the n type noncrystalline semiconductor layer 8 of 5nm.

The membrance casting condition of above noncrystalline semiconductor layer, identical with embodiment 1, as shown in table 1 is the same.

Then, on the p type noncrystalline semiconductor layer 4 and n type noncrystalline semiconductor layer 8 that form on two interareas of p type crystal based semiconductor substrate 20, utilize sputtering method to form the p side transparent conductive film layer 5 and the n side transparent conductive film layer 9 that by ITO constitute of thickness for 100nm.

Then, on the p side transparent conductive film layer 5 that the second interarea side of p type crystal based semiconductor substrate 20 forms and on the n side transparent conductive film layer 9 that the first interarea side forms, the p side collector electrode 6 and the n side collector electrode 10 that utilize the silk screen print method coating to constitute by silver paste, under about 180 ℃, fired about 1 hour afterwards, make the silver paste sclerosis.Thus, finish second laminated body 22 and first laminated body 21.Like this, just produced structure 23.

Then,, structure is removed by the part of laser radiation, thus, on structure 23, formed groove to above-mentioned structure 23 irradiating lasers.

At this moment, similarly to Example 1, using the laser optical path is 50 μ m, the wavelength YAG laser as 1064nm, use the power of 3～5W, as shown in Figure 7, along the direction of arrow L, from second laminated body, 22 1 sides, promptly from the second interarea side of p type crystal based semiconductor substrate 20, to structure 23 irradiating lasers.By carrying out such laser radiation, as shown in Figure 7, second laminated body 22 and p type crystal based semiconductor substrate 20 are removed, on structure 23, form groove 15 thus, produce structure 24.Similarly to Example 1, by adjusting the illuminate condition of laser, formed the groove 15 that the degree of depth does not reach the n type noncrystalline semiconductor layer 8 with conductivity type different with p type crystal based semiconductor substrate 20.The degree of depth of this groove 15 is about 60 μ m, and the width of groove 15 and the optical path of above-mentioned laser are roughly the same.

At last, by to structure 23 stress applications, structure 24 is mechanically cut apart along above-mentioned groove 15.Cut apart by this, produced the photovoltaic cell 25 (Fig. 8) of desired size.

By above making, as shown in Figure 8, can produce the photovoltaic cell 25 that at least one side of being clamped by second interarea of first interarea of p type crystal based semiconductor substrate 20 and this first interarea opposition side is formed by division processing face 28.At this, this division processing face 28 is made of laser processing zone 26 and cut-out machining area 27, laser processing zone 26 from above-mentioned first interarea of the above-mentioned second interarea side direction extend but no show have the conductivity type different with above-mentioned p type crystal based semiconductor substrate 20 n type noncrystalline semiconductor layer 8, form by laser processing, cut off machining area 27 and extend, form by cutting off from the above-mentioned second interarea side of the above-mentioned first interarea side direction.

(comparative example 1)

Below, with reference to Fig. 3, Fig. 9 and Figure 10, comparative example 1 is described.

In comparative example 1, made the structure 1 identical similarly to Example 1 with the situation of embodiment shown in Figure 31.

Then, as shown in Figure 9, from the opposition side of the situation of embodiment 1, promptly from first laminated body, 11 1 sides,, structure is removed by the part of laser radiation to above-mentioned structure 1 irradiating laser, on structure 1, form groove 15 thus, produced structure 31.

At this moment, similarly to Example 1, using the laser optical path is 50 μ m, the wavelength YAG laser as 1064nm, uses the power of 3～5W, as shown in Figure 9, and along the direction of arrow L, from first laminated body, 11 1 sides, to structure 1 irradiating laser.By carrying out such laser radiation, as shown in Figure 9, first laminated body 11 and n type crystal based semiconductor substrate 2 are removed, on structure 1, form groove 15 thus, produce structure 31.Similarly to Example 1, by adjusting the illuminate condition of laser, formed the groove 15 that the degree of depth does not reach the n type noncrystalline semiconductor layer 8 with conductivity type identical with n type crystal based semiconductor substrate 2.The degree of depth of this groove 15 is about 60 μ m, and the width of groove 15 and the optical path of above-mentioned laser are roughly the same.

At last, by to structure 31 stress applications, structure 31 is mechanically cut apart along above-mentioned groove 15.Cut apart by this, produced the photovoltaic cell 32 of desired size.

By above making, as shown in figure 10, can produce the photovoltaic cell 32 that at least one side of being clamped by second interarea of first interarea of n type crystal based semiconductor substrate 2 and this first interarea opposition side is formed by division processing face 38.At this, this division processing face 38 is made of laser processing zone 36 and cut-out machining area 37, laser processing zone 36 from above-mentioned second interarea of the above-mentioned first interarea side direction extend but no show have the conductivity type identical with said n type crystal based semiconductor substrate 2 n type noncrystalline semiconductor layer 8, form by laser processing, cut off machining area 37 and extend, form by cutting off from the above-mentioned first interarea side of the above-mentioned second interarea side direction.

(comparative example 2)

Below, with reference to Fig. 6, Figure 11 and Figure 12, comparative example 2 is described.

In comparative example 2, made the structure 23 identical similarly to Example 2 with the situation of embodiment shown in Figure 62.

Then, as shown in figure 11, from the opposition side of the situation of embodiment 2, promptly from first laminated body, 21 1 sides,, structure is removed by the part of laser radiation to above-mentioned structure 23 irradiating lasers, on structure 23, form groove 15 thus, produced structure 41.

At this moment, similarly to Example 2, using the laser optical path is 50 μ m, the wavelength YAG laser as 1064nm, uses the power of 3～5W, as shown in figure 11, and along the direction of arrow L, from first laminated body, 21 1 sides, to structure 23 irradiating lasers.By carrying out such laser radiation, as shown in figure 11, first laminated body 21 and p type crystal based semiconductor substrate 20 are removed, on structure 23, form groove 15 thus, produce structure 41.Similarly to Example 2, by adjusting the illuminate condition of laser, formed the groove 15 that the degree of depth does not reach the p type noncrystalline semiconductor layer 4 with conductivity type identical with p type crystal based semiconductor substrate 20.The degree of depth of this groove 15 is about 60 μ m, and the width of groove 15 and the optical path of above-mentioned laser are roughly the same.

At last, by to structure 41 stress applications, structure 41 is mechanically cut apart along above-mentioned groove 15.Cut apart by this, produced the photovoltaic cell 42 of desired size.

By above making, as shown in figure 12, can produce the photovoltaic cell 42 that at least one side of being clamped by second interarea of first interarea of p type crystal based semiconductor substrate 20 and this first interarea opposition side is formed by division processing face 48.At this, this division processing face 48 is made of laser processing zone 46 and cut-out machining area 47, laser processing zone 46 from above-mentioned second interarea of the above-mentioned first interarea side direction extend but no show have the conductivity type identical with above-mentioned p type crystal based semiconductor substrate 20 p type noncrystalline semiconductor layer 4, form by laser processing, cut off machining area 47 and extend, form by cutting off from the above-mentioned first interarea side of the above-mentioned second interarea side direction.

(evaluation result)

To the photovoltaic cell of embodiment 1, embodiment 2, comparative example 1 and the comparative example 2 of above-mentioned manufacturing, measured output characteristic.To be shown in table 2 to the measurement result of the output characteristic of the photovoltaic cell of embodiment 1 and comparative example 1, will be shown in table 3 measurement result of the output characteristic of the photovoltaic cell of embodiment 2 and comparative example 2.

Table 2

	V oc(V)	I sc(A)	F.F.	P max(W)
					Embodiment 1	0.702	3.725	0.775	2.026
Comparative example 1	0.695	3.722	0.758	1.960

Table 3

	V oc(V)	I sc(A)	F.F.	P max(W)
					Embodiment 2	0.676	3.686	0.745	1.858
Comparative example 2	0.674	3.680	0.700	1.736

As shown in Table 2, embodiment 1 compares with comparative example 1, open circuit voltage V _OC, short circuit current I _SC, curve factor F.F. and peak power output P _MaxAll higher, have excellent characteristic.The difference of embodiment 1 and comparative example 1 is: in embodiment 1, from the second interarea side of n type crystal based semiconductor substrate 2, promptly from interarea one side of the interarea opposition side that has formed p type noncrystalline semiconductor layer 4 with conductivity type different with n type crystal based semiconductor substrate 2, to structure 1 irradiating laser, and in comparative example 1, from the first interarea side of n type crystal based semiconductor substrate 2, promptly from comprising first laminated body, 11 1 sides of p type noncrystalline semiconductor layer 4, to structure 31 irradiating lasers with conductivity type different with n type crystal based semiconductor substrate 2.

Under the situation of comparative example 1, near the structure the laser radiation position of the structure 31 after the laser radiation is identical with the solar cell 50a of Fig. 2 (a).In near the end face of the structure 31 the laser radiation position, the end of the end of intrinsic noncrystalline semiconductor layer 3 and p type noncrystalline semiconductor layer 4, because the influence of the heat during laser radiation and micro-crystallizationization, the resistance of these parts reduces.So, between p type noncrystalline semiconductor layer 4 with opposite conductivity type and n type crystal based semiconductor substrate 2, leakage current flow is arranged.Therefore, the open circuit voltage V of the photovoltaic cell 32 of the comparative example of making like this 1 _OCReduce with curve factor F.F..

Relative therewith, in embodiment 1, since from interarea one side direction structure 1 irradiating laser of the interarea opposition side that has formed p type noncrystalline semiconductor layer 4 with conductivity type different with n type crystal based semiconductor substrate 2, so, can between p type noncrystalline semiconductor layer 4 with opposite conductivity type and n type crystal based semiconductor substrate 2, can not produce leakage current flow as comparative example 1.

Therefore, as mentioned above, can think and compare to have excellent characteristic with comparative example 1.

As shown in Table 3, embodiment 2 compares with comparative example 2, open circuit voltage V _OC, short circuit current I _SC, curve factor F.F. and peak power output P _MaxAll higher, have excellent characteristic.

The difference of embodiment 2 and comparative example 2 is: in embodiment 2, the second interarea side from p type crystal based semiconductor substrate 20, promptly from the interarea side of the interarea opposition side that is formed with n type noncrystalline semiconductor layer 8 with conductivity type different with p type crystal based semiconductor substrate 20, to structure 23 irradiating lasers, and in comparative example 2, the first interarea side from p type crystal based semiconductor substrate 20, promptly from comprising first laminated body, 21 1 sides of n type noncrystalline semiconductor layer 8, to structure 41 irradiating lasers with conductivity type different with p type crystal based semiconductor substrate 20.

Under the situation of comparative example 2, near the structure the laser radiation position of the structure 41 after the laser radiation is identical with the structure that replaces with behind the p type crystal based semiconductor substrate 20 in the solar cell 50b of Fig. 2 (b), with n type crystal based semiconductor substrate 2.In near the end face of the structure 41 the laser radiation position, the end of the end of intrinsic noncrystalline semiconductor layer 7 and n type noncrystalline semiconductor layer 8, because the influence of the heat during laser radiation and micro-crystallizationization, the resistance of these parts reduces.So, between n type noncrystalline semiconductor layer 8 with opposite conductivity type and p type crystal based semiconductor substrate 20, leakage current flow is arranged.Therefore, the open circuit voltage V of the photovoltaic cell 42 of the comparative example of making like this 2 _OCReduce with curve factor F.F..

Relative therewith, in embodiment 2, since from interarea one side direction structure 23 irradiating lasers of the interarea opposition side that is formed with n type noncrystalline semiconductor layer 8 with conductivity type different with p type crystal based semiconductor substrate 20, so, can between n type noncrystalline semiconductor layer 8 with opposite conductivity type and p type crystal based semiconductor substrate 20, can not produce leakage current flow as comparative example.

Therefore, as mentioned above, can think and compare to have excellent characteristic with comparative example 2.

So, no matter crystal based semiconductor substrate is n type or p type, from being formed with a side of noncrystalline semiconductor layer with conductivity type identical with crystal based semiconductor substrate, promptly from the interarea one side irradiating laser of the opposition side of the interarea that is formed with noncrystalline semiconductor layer with conductivity type different with crystal based semiconductor substrate, on structure, form groove in the mode that does not reach noncrystalline semiconductor layer at least, can make the photovoltaic cell of output characteristic excellence thus with conductivity type different with crystal based semiconductor substrate.

In addition, crystal based semiconductor substrate can be a monocrystalline silicon substrate, also can be polycrystalline silicon substrate.In addition, being not limited to silicon substrate, also can be semiconductor substrates such as germanium substrate.In above embodiment, the noncrystalline semiconductor layer can be an amorphous silicon layer, also can be the amorphous germanium layer.

Like this, according to the present invention, can provide and to make open circuit voltage V _OCRepressed with the reduction of curve factor F.F., have a technology of photovoltaic cell heterojunction, desired size that the combination of noncrystalline semiconductor and crystal based semiconductor is constituted.

(the 3rd execution mode)

Below, with reference to accompanying drawing the 3rd execution mode of the present invention is described.

Figure 13 is the side view of the photovoltaic cell of expression the 3rd execution mode of the present invention.Figure 14 is the stereogram of expression photovoltaic cell shown in Figure 13.As shown in figure 16, Figure 13 and photovoltaic cell shown in Figure 14 are cut off and are made by the periphery of cut-off parts 114 with the substrate of photovoltaic cell.As shown in figure 13, in the photovoltaic cell of the 3rd execution mode, on an interarea 101a who has as the n type crystal based semiconductor substrate 101 of the interarea 101a of (100) face of crystal based semiconductor substrate, formation has the intrinsic noncrystalline semiconductor layer 102 thickness, that be essentially the intrinsic uncrystalline layer of about 5nm, form p type noncrystalline semiconductor layer 103 thereon, form p side transparent conductive film layer 104 thereon with about 80nm～about 100nm thickness with about 5nm thickness.On p side transparent conductive film layer 104, be formed with by the SnO that contains the 5 quality % that have an appointment ₂InO ₂ITO (indium tin oxide) film that constitutes.On p side transparent conductive film layer 104, be formed with p side collector electrode 105.As shown in figure 14, p side collector electrode 105 is by the interval that separates regulation, extend in parallel to each other and a plurality of finger electrode 105a that form and the bus electrode 105b that further collects by the collected electric current of finger electrode 105a constitute.

In addition, on another interarea (back side) 101b of n type crystal based semiconductor substrate 101, formation has intrinsic noncrystalline semiconductor layer 106 about 5nm thickness, that be essentially the intrinsic uncrystalline layer, formation has the n type noncrystalline semiconductor layer 107 of about 5nm thickness, is formed with the p side transparent conductive film layer 108 with about 80～about 100nm thickness thereon.On p side transparent conductive film layer 108, similarly be formed with the n side collector electrode 109 that constitutes by finger electrode and bus electrode with p side collector electrode 105.

As mentioned above, photovoltaic cell 120 shown in Figure 13 forms by the cut-off parts 114 on 4 limits around shown in Figure 16 is cut off, and by being cut off by cut-off parts 114, as shown in figure 16, forms 4 division processing sides 110.

As shown in figure 13, be formed with on the division processing side 110 from laser processing zone 111 that interarea 101a one side of another interarea 101b one side direction is extended and the cut-out machining area 112 that extends from another interarea of interarea 101a one side direction 101b one side.Wherein, the laser processing of division processing side 110 shown in Figure 13 zone 111 and cut-out machining area 112 are the diagrams of amplifying.

As shown in figure 13, in laser processing zone 111 with cut off on the boundary line of machining area 112, be formed with side-prominent a plurality of protuberance 111a to an interarea 101a one, 111a forms concavo-convex on the boundary line by this protuberance.This protuberance 111a is in that to form laser processing zone 111 o'clock formed.

Figure 15 is the side view that is used to illustrate the formation operation in laser processing zone, is the side view of seeing from arrow A direction shown in Figure 13.In Figure 15, to be expression process and the peripheral part of the photovoltaic cell 120 removed through laser processing and bending and cutting thereafter the part of representing with chain-dotted line.As shown in figure 15, from another interarea 101b one side irradiating laser of n type crystal based semiconductor substrate 101, form groove 113.When forming this groove 113, the part of the division processing side 110 in groove 113 forms laser processing zone 111.Forming groove 113 like this, for example, as shown in figure 17, is the center with the part of groove 113, processes by the bending and cutting of clamping the periphery of photovoltaic cell 120 with holding member 115 and carrying out bending, cuts apart photovoltaic cell 120.Like this, formed cross section when being cut off by bending and cutting processing becomes cut-out machining area 112 shown in Figure 15.

Stress around the protuberance 111a that forms in cut-out machining area 112 shown in Figure 13 is concentrated vestige 112a, is owing to add concentrated formation of stress in man-hour at above-mentioned bending and cutting.

In the present invention, add man-hour at bending and cutting, as mentioned above, because stress concentrates on the head portion and on every side of the protuberance 111a in laser processing zone 111, so forming with protuberance 111a is that the radial stress of starting point is concentrated trace 112a.In laser processing zone 111, be formed with a plurality of protuberance 111a, bending and cutting adds man-hour, because stress concentrates on the head portion of these protuberances 111a and on every side, therefore, can easily carry out bending and cutting processing.That is, can carry out bending and cutting processing by enough littler stress.Owing to add man-hour at bending and cutting, can cut off by less stress, so the strain that produces also can reduce, its result can improve the curve factor, thereby can access high photoelectric conversion efficiency.

Figure 18 is the microphotograph of the side of the photovoltaic cell of expression the 3rd execution mode of the present invention.Figure 19 is the microphotograph of the side of the photovoltaic cell of expression comparative example.In addition, Figure 20 is and the corresponding figure of Figure 18 to represent the side of the photovoltaic cell of the 3rd execution mode of the present invention.Figure 21 is and the corresponding figure of Figure 19 the side of the photovoltaic cell of expression comparative example.

As Figure 18 and shown in Figure 20, side at photovoltaic cell of the present invention, top ends in laser processing zone 111 is formed with protuberance 111a, and in the cut-out machining area 112 around the protuberance 111a, being formed with protuberance 111a is the concentrated trace 112a of radial stress of starting point.Can think, owing to stress concentrates on the protuberance 111a, so, add man-hour at bending and cutting, forming with this part is the concentrated trace 112a of radial stress of starting point.

Relative therewith, as Figure 19 and shown in Figure 21, in the photovoltaic cell of comparative example 1, in laser processing zone 111, do not form protuberance, under such state, carry out bending and cutting and add man-hour, cut off machining area 112 and be subjected to bigger stress, be cut off in the mode of twisting, so observed at the upwardly extending lines 112b of certain party.

Figure 22 is the side view of relation of shape of the top ends in laser irradiation condition when being used to laser processing is described and laser processing zone.As the laser irradiation condition of the shape that influences the laser processing zone, can list scanning times of the pulse frequency of output power of laser, laser and sweep speed, laser radiation etc.

The degree of depth in laser processing zone, promptly, roughly proportional with power output by the degree of depth of the formed groove of laser processing.So,, can add the degree of depth of deep trouth by increasing power output.

What the shape in laser processing zone was had the greatest impact is pulse frequency and sweep speed.Pulse frequency is big more divided by the value (pulse frequency/sweep speed) of sweep speed gained, and the interval of protuberance is narrow more, when the interval of protuberance is too narrow to when to a certain degree above, can't observe at microscope (100 times), and the top ends of machining area becomes smooth shape.The shape that Figure 22 (a) expression is such.

In addition, the value of pulse frequency/sweep speed is more little, and the interval of protuberance is big more, and the height of protuberance has the trend that reduces.The shape that Figure 22 (c) expression is such.

So, in order to form the protuberance 111a of the present invention shown in Figure 22 (b), value that must paired pulses frequency/sweep speed is controlled, and the value of the pulse frequency/sweep speed when making it than the shape of expression Figure 22 (a) is little and the value pulse frequency/sweep speed during than the shape of expression Figure 22 (c) is big.

In addition, the scanning times of laser radiation also has bigger influence to the degree of depth of groove.Though working depth increases when increasing scanning times at every turn, its recruitment can reduce gradually.

Figure 23 is the side view of method that is used for illustrating the average height of the protuberance of measuring the present invention.The height of protuberance 111a in the laser processing zone 111 uses to have the microscope of surveying long function, for example is amplified to 100 times, measures the poor of the apex portion of protuberance and the lowest point part.Because the shape of protuberance is uneven, survey long line 16 so draw in the center of the apex portion of protuberance 111a to survey long line 15 and to draw, with the difference of surveying long line 15 and the long line 16 of survey average height as protuberance 111a in the center of the lowest point part.

In addition, for the interval of protuberance 111a, with similarly above-mentioned, use has the microscope of surveying long function, for example is amplified to 200 times, can observed 6 protuberances for naked eyes, distance between each protuberance is measured, with its mean value as the equispaced between protuberance.

According to the 3rd execution mode of the present invention, in laser processing zone 111, form side-prominent a plurality of protuberance 111a to the interarea 101a one of n type crystal based semiconductor substrate 101.So bending and cutting adds the stress that produces man-hour and concentrates on the protuberance 111a, strain is disperseed, so the strain of division processing side 110 reduces.Its result, the photoelectric conversion efficiency of photovoltaic cell 120 improves.

[embodiment]

(embodiment 3)

Below, the embodiment of the photovoltaic cell of making embodiments of the invention is described.

[experiment 1]

The making of the photovoltaic cell the before＜cut-out processing 〉

With reference to Figure 13, by the n type crystal based semiconductor substrate 101 clean impurity of removing that will have (100) face.This n type crystal based semiconductor substrate 101 has the resistivity of about 1 Ω cm, the thickness of about 300 μ m.

Then, using the RF plasma CVD method, is that about 13.56MHz, formation temperature are that about 100 ℃～about 300 ℃, reaction pressure are that about 5Pa～about 100Pa, RF power are about 1mW/cm in frequency ²～about 500mW/cm ²Condition under, on an interarea 101a of n type crystal based semiconductor substrate 101, form the p type noncrystalline semiconductor layer 103 have the intrinsic noncrystalline semiconductor layer 102 of about 5nm thickness and to have about 5nm thickness successively.In addition, the p type doping agent during as formation p type noncrystalline semiconductor layer 103 can list B, Al, Ga, In etc. as the 3rd family's element.In addition, when forming p type noncrystalline semiconductor layer 103, by containing at least a chemical compound gas and the SiH in the above-mentioned p type doping agent ₄Unstrpped gases such as (silane) gas are mixed, and can form p type noncrystalline semiconductor layer 103.

Then, with similarly above-mentioned, on 101b on another interarea of n type crystal based semiconductor substrate 101, form the n type noncrystalline semiconductor layer 107 that has the intrinsic noncrystalline semiconductor layer 106 of about 5nm thickness and have about 5nm thickness successively.In addition, the n type doping agent during as formation n type noncrystalline semiconductor layer 107 can list P, N, As, Sb etc. as the 5th family's element.When forming n type noncrystalline semiconductor layer 107, mix with unstrpped gas by at least a chemical compound gas that will contain in the said n type doping agent, can form n type noncrystalline semiconductor layer 107.

Then, use sputtering method, on p type noncrystalline semiconductor layer 103 and n type noncrystalline semiconductor layer 107, form the p side transparent conductive film layer 104 and the n side transparent conductive film layer 108 that constitute by the ITO film respectively.This p side transparent conductive film layer 104 and n side transparent conductive film layer 108 can use by the SnO that contains the 5 weight % that have an appointment ₂In ₂O ₃The target that sintered body constituted (target) of powder forms by sputtering method.By changing SnO ₂The amount of powder can change the amount of Sn in the ITO film.Sn is preferably about 1 quality %～about 10 quality % with respect to the amount of In.P side transparent conductive film layer 104 and n side transparent conductive film layer 108 form the thickness of about 80nm～about 100nm.

Then, after using silk screen print method, the conductive paste (silver (Ag) cream) of the thermohardening type of epoxies being transferred on the regulation zone of p side transparency electrode rete 104 of an interarea 101a side, in heating furnace, heat, conductive paste is solidified, formed p side collector electrode 105.Similarly formed n side collector electrode 109.

＜utilize laser processing to form groove 〉

Utilize laser processing to form groove at the periphery of the photovoltaic cell of producing as described above.As shown in figure 16, form groove in 4 positions with chain-dotted line (cut-off parts 114) expression of periphery.Use YAG laser as laser, from another interarea 101b one side irradiating laser of n type crystal based semiconductor substrate 101.Output power of laser is that 3～10W, wavelength are the scope that 1064nm, pulse frequency are controlled at 1kHz～30kHz, and the sweep speed of laser scans with the certain speed in 1～30mm/ scope of second.Scanning times is selected in 1～6 time scope.

Irradiating laser under above-mentioned laser irradiation condition makes that the average height of protuberance is 7 μ m, 15 μ m, 25 μ m, 50 μ m and 75 μ m.In addition, make, make that equispaced between the protuberance of this moment is in 0.2 times～3.0 times the scope of average height of protuberance.In addition, make, make average height in the scope of 150 μ m～200 μ m from another interarea of wafer to the top ends of protuberance.

The bending and cutting processing of＜photovoltaic cell 〉

Part with the groove that forms is the center, and bending and cutting processing is carried out in the periphery bending of 5 kinds of photovoltaic cells that will obtain as mentioned above respectively thus, produces each photovoltaic cell.

[evaluating characteristics of photovoltaic cell]

To 5 kinds of photovoltaic cells of above making, irradiation solar simulator (solar simulator) AM1.5,1kW/m ²Light, measured the I-V characteristic.With the average height of protuberance as transverse axis, with the curve factor (F.F.) as the longitudinal axis, measurement result is shown in Figure 24.Wherein, the value representation of the curve factor carries out the value of the curve factor after the standardization with the curve factor of the photovoltaic cell of comparative example.Use the photovoltaic cell photovoltaic cell as a comparative example that periphery is not cut off processing.

As shown in Figure 24, the average height of protuberance is the above photovoltaic cells of 15 μ m, and standardized F.F. is more than 1.In addition, the value of standardization F.F. increases, and is more than the 25 μ m until the average height of protuberance, maintains roughly the same value thereafter.So the average height of protuberance is preferably more than the 15 μ m.

[experiment 2]

Except utilize in 1 laser processing to form groove carries out in accordance with the following methods in experiment, all the other similarly carry out with experiment 1, produce photovoltaic cell.

Produce 8 kinds of photovoltaic cells, make that the average height of protuberance is 25～30 μ m, make the average height of top ends be changed to 60 μ m, 90 μ m, 120 μ m, 150 μ m, 200 μ m, 250 μ m, 270 μ m and 300 μ m from another interarea to protuberance.So that being 0.2 times～3.0 times mode of the average height of protuberance, the equispaced of protuberance makes.

[evaluating characteristics of photovoltaic cell]

With experiment 1 similarly, to 8 kinds of photovoltaic cells of above making, measure the I-V characteristic, measurement result is shown in Figure 25.Wherein, in Figure 25, with the thickness of average height/substrate from another interarea to the protuberance top ends as transverse axis.Because substrate thickness is 300 μ m, so when the average height from another interarea to the protuberance top ends was 300 μ m, above-mentioned value was 100%.In addition, the point that has " zero " among Figure 24 and Figure 25 is the measurement result of same device.

As shown in figure 25, the average height from another interarea to the protuberance top ends reaches 30% when above of substrate thickness, and standardization F.F. is greater than 1.Up to 50%, along with the increase of distance, the standardized curve factor increases thus; Reach 50% when above, the value of the standardized curve factor maintains roughly certain value.Therefore as can be known, the average height from another interarea to the protuberance top ends is preferably more than 50% of substrate thickness.In addition, reach 90% when above, the standardized curve factor becomes less than 1.Therefore as can be known, if the average height of top ends from another interarea to protuberance in 30%～90% scope of substrate thickness, then the standardization curve factor is more than 1, more preferably in 50%～90% scope.

In addition, in Figure 25,100% situation is the situation that the top ends of protuberance has arrived an interarea of substrate, and as can be known, when having arrived interarea of substrate, the standardized curve factor descends significantly.So the average height of the top ends from another interarea to protuberance is preferably less than 100% of substrate thickness.

In addition, in the above-described embodiments, the example that 4 limits around the photovoltaic cell are cut off is illustrated, but the present invention is not limited to this, also goes for only cutting off the situation on 1 limit, 2 limits or 3 limits.

In addition, as shown in figure 26, with chain-dotted line (cut-off parts 114) with 1 photovoltaic cell array 130 be divided into multi-disc, with the situation of the photovoltaic cell 120 of making small size, also can be suitable for the present invention.And, cut off the cut-out that also is not limited to linearity, be cut to curvilinear situation and also can be suitable for the present invention.

In addition, in the above-described embodiments, be that example is illustrated with the photovoltaic cell of HIT structure, but the present invention also go for using the photovoltaic cell of crystal based semiconductor substrate, also goes for other photovoltaic cell.For example, go for thin-film solar cells of on monocrystalline silicon, polysilicon, compound semiconductor, crystal class substrate, forming etc.

In the above-described embodiments, use the material of the thermohardening type conductive paste of epoxies as collector electrode, but the present invention is not limited to this, as the material of adhesive layer, bus electrode and backplate, also can use the conductive material that contains epoxies resin material in addition.In addition, also can use the conductive paste of the resin material that contains polyesters, acrylic compounds, polyethylene kind and phenols etc.

In the above-described embodiments, make the conductive paste sclerosis by heating, thereby form collector electrode, but the present invention is not limited to this, also can utilize said method method in addition to form collector electrode.For example, thereby also can form collector electrode, thereby or metal wire be carried out bonding formation collector electrode with adhesive layer by evaporating Al etc.

In the above-described embodiments, on the conducting film of another interarea side, form the backplate that constitutes by bus electrode and finger electrode, but the present invention is not limited to this, also can forms the backplate of the nesa coating integral body that covers another interarea side.

In the above-described embodiments, use silicon (Si) as semi-conducting material, but the present invention is not limited to this, also can use any semiconductor among SiGe, SiGeC, SiC, SiN, SiGeN, SiSn, SiSnN, SiSnO, SiO, Ge, GeC, the GeN.In this case, these semiconductors can be crystal, or contain any one the noncrystal or microcrystal in hydrogen and the fluorine.

In the above-described embodiments, use and mix up the material that indium oxide (ITO) conduct that Sn is arranged forms nesa coating, but the present invention is not limited to this, also can use the nesa coating that is made of the material beyond the ITO film.For example, can form by being mixed with the nesa coating that indium oxide at least a among Zn, As, Ca, Cu, F, Ge, Mg, S, Si and the Te constitutes.

In the above-described embodiments, use the RF plasma CVD method to form the noncrystalline semiconductor layer, but the present invention is not limited to this, also can form the noncrystalline semiconductor layer by other methods such as vapour deposition method, sputtering method, microwave plasma CVD technique, ECR method, hot CVD method, LPCVD (decompression CVD) methods.

More than, describe the present invention according to execution mode.These execution modes only are illustrations, with these each inscapes and the combination of each treatment process, can access various variation, and these variation also belong to scope of the present invention, and this point those skilled in the art should understand that.

Claims (14)

1. photovoltaic cell, possess the crystal based semiconductor substrate of first conductivity type and the semiconductor layer of second conductivity type, the crystal based semiconductor substrate of described first conductivity type has first interarea and is arranged on second interarea of the opposition side of described first interarea, the semiconductor layer of described second conductivity type is set on first interarea of described crystal based semiconductor substrate, it is characterized in that:

Described crystal based semiconductor substrate is clamped between described first interarea and described second interarea and has by the formed division processing of division processing side,

Described division processing side constitutes by crossing laser processing formed laser processing zone from described second interarea, one square tube and processing formed cut-out machining area by cut-out,

Described laser processing zone is the semiconductor layer of described second conductivity type of no show, from described second interarea to zone that the described first interarea side is extended.

2. photovoltaic cell as claimed in claim 1 is characterized in that:

The semiconductor layer of described second conductivity type has from the structure of the conductive membrane of the noncrystalline semiconductor layer of described first interarea of described crystal based semiconductor substrate lamination second conductivity type successively and second conductivity type.

3. photovoltaic cell as claimed in claim 2 is characterized in that:

The semiconductor layer that also has first conductivity type on described second interarea that is arranged on described crystal based semiconductor substrate,

The semiconductor layer of described first conductivity type has from the structure of the conductive membrane of the noncrystalline semiconductor layer of described second interarea of described crystal based semiconductor substrate lamination first conductivity type successively and first conductivity type.

4. photovoltaic cell as claimed in claim 3 is characterized in that:

At least one side in the noncrystalline semiconductor layer of described second conductivity type and the noncrystalline semiconductor layer of described first conductivity type comprises the noncrystalline semiconductor layer of intrinsic.

5. photovoltaic cell as claimed in claim 1 is characterized in that:

Described cut-out processing is bending and cutting processing,

On the boundary line of described laser processing zone and described cut-out machining area, described laser processing zone has to the side-prominent a plurality of protuberances of described first interarea,

At described cut-out machining area, as starting point, be formed with described bending and cutting and add the stress that produces man-hour and concentrate vestige with the described protuberance in described laser processing zone.

6. photovoltaic cell as claimed in claim 5 is characterized in that:

The average height of described protuberance is more than the 15 μ m.

7. photovoltaic cell as claimed in claim 5 is characterized in that:

The equispaced of described protuberance is 0.2 times～3.0 times of average height of described protuberance.

8. photovoltaic cell as claimed in claim 5 is characterized in that:

Average length from described second interarea to the top of described protuberance is more than 50% of length from described second interarea to described first interarea.

9. the manufacture method of a photovoltaic cell, make possess have first main and and be arranged on the photovoltaic cell of crystal based semiconductor substrate of first conductivity type of second interarea of the opposition side of described first interarea, it is characterized in that, comprise:

On described first interarea of described crystal based semiconductor substrate, form the operation A of the semiconductor layer of second conductivity type;

From the described second interarea side irradiating laser of described crystal based semiconductor substrate, the process B of the groove that form the semiconductor layer do not reach described second conductivity type, extends from described second interarea to the described first interarea side; With

The semiconductor layer of described crystal based semiconductor substrate and described second conductivity type is cut off along described groove, thus the operation C that the semiconductor layer of described crystal based semiconductor substrate and described second conductivity type is cut apart.

10. the manufacture method of photovoltaic cell as claimed in claim 9 is characterized in that:

Also be included in the step D that forms the semiconductor layer of first conductivity type on described second interarea of described crystal based semiconductor substrate,

Described process B is the operation of shining described laser from semiconductor layer one side of described first conductivity type.

11. the manufacture method of photovoltaic cell as claimed in claim 10 is characterized in that:

The semiconductor layer of described first conductivity type has described second interarea from described crystal based semiconductor substrate, the structure of the conductive membrane of the noncrystalline semiconductor layer of lamination first conductivity type and first conductivity type successively;

The semiconductor layer of described second conductivity type has described first interarea from described crystal based semiconductor substrate, the structure of the conductive membrane of the noncrystalline semiconductor layer of lamination second conductivity type and second conductivity type successively.

12. the manufacture method of photovoltaic cell as claimed in claim 11 is characterized in that:

At least one side in the noncrystalline semiconductor layer of described second conductivity type and the noncrystalline semiconductor layer of described first conductivity type comprises the noncrystalline semiconductor layer of intrinsic.

13. the manufacture method of photovoltaic cell as claimed in claim 9 is characterized in that:

Described process B comprises and forms the operation have to the described groove of the side-prominent a plurality of protuberances of described first interarea,

Described operation C comprises the semiconductor layer of described crystal based semiconductor substrate and described second conductivity type operation along described groove bending.

14. the manufacture method of photovoltaic cell as claimed in claim 13 is characterized in that:

Described process B comprises, and controls the pulse frequency of described laser and the sweep speed of described laser, thereby forms the operation that has to the described groove of the side-prominent a plurality of protuberances of described first interarea.

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