EP3050119A1

EP3050119A1 - Method for producing a contact structure of a photovoltaic cell and photovoltaic cell

Info

Publication number: EP3050119A1
Application number: EP14776857.6A
Authority: EP
Inventors: Tim Boescke
Original assignee: Ion Beam Services SA
Current assignee: Ion Beam Services SA
Priority date: 2013-09-27
Filing date: 2014-09-26
Publication date: 2016-08-03
Also published as: WO2015044341A1; CN105765733B; CN105765733A; DE102013219599A1; US20160225921A1; KR20160064173A

Abstract

The invention relates to a method (800) for producing a contact structure (104) of a photovoltaic cell (100), wherein the method (800) comprises a step (802) of providing, a step (804) of doping, and a step (806) of contacting. In step (802) of providing, a wafer (102) for the photovoltaic cell (100) is provided. In step (804) of doping, a surface portion of at least one side of the wafer (102) is doped with a doping material in order to obtain a doped region (106), wherein the doped region (106) is formed as doped tracks (106) and the tracks (106) are separated by intermediate spaces (110). In step (806) of contacting, the doped region (106) is contacted in order to produce the contact structure (104), wherein a conductor material (108) is applied to the tracks (106) in such a way that the tracks (106) protrude beyond the conductor material (108) on both sides.

Description

Description title

Method for producing a contact structure of a photovoltaic cell and photovoltaic cell

State of the art

The present invention relates to a method for producing a contact structure of a photovoltaic cell and to a photovoltaic cell.

A semiconductor material of a photovoltaic cell is provided with at least two

doped different dopants to a P-n junction in

To create semiconductor material. At the transition, electrical

Charges are separated to produce an electric potential using incident light. The electrical potential can be tapped via conductor tracks of the semiconductor material.

DE 10 2009 034 594 A1 describes a process for producing a crystalline silicon solar cell with an all-over, alloyed surface

Backside metallization.

Disclosure of the invention

Against this background, the present invention proposes a method for producing a contact structure of a photovoltaic cell and a photovoltaic cell according to the main claims. Advantageous embodiments emerge from the respective subclaims and the following description.

When doping the semiconductor material of a photovoltaic cell and the

Contacting the doped semiconductor material may be various

Targets are sought. For example, by a high doping a low contact resistance between the semiconductor material and a contact material can be achieved. However, the high doping also results in internal losses in the semiconductor material, which can be reduced if the doping is reduced. In the case of a low doping, in return, a high contact resistance results between the semiconductor material and the contact material. High doping additionally improves electrical conductivity within the doped region.

In order to combine low internal losses with low transition losses, regions around printed conductors of the photovoltaic cell can be highly doped, while gaps between the highly doped regions are little or not doped.

As a result, a high overall efficiency of the photovoltaic cell can be achieved.

A method for producing a contact structure of a photovoltaic cell is presented, the method comprising the following steps:

Providing a wafer for the photovoltaic cell;

Doping a surface portion of at least one side of the wafer with a doping material to obtain a doped region, wherein the doped region is formed as doped sheets and the webs through

Spaces are separated; and

Contacting the doped region to produce the contact structure, wherein a conductor material is applied to the webs, that the webs project beyond the conductor material on both sides.

A photovoltaic cell can be understood as a solar cell. A wafer can be understood as a wafer made of a semiconductor material. The semiconductor material may already be predoped with foreign atoms. The semiconductor material may also be present in pure form. The doping may involve introducing atoms or ions of a species other than that

Semiconductor material in the semiconductor material. A train can be a strip. The webs may be contiguous at contact points. At the Contacting a narrow strip of metallic material can be applied to the doped tracks. The metallic material may be silver-based, for example. The conductor material can be printed on the doped tracks.

An area fraction between 20 percent and 90 percent, in particular between 40 percent and 60 percent, of the at least one side of the wafer can be doped. The higher the doped area fraction, the greater the internal losses, such as recombination losses in the

Photovoltaic cell. This can be the transmission losses within the

Reduce photovoltaic cell.

In this case, in the step of doping, the rear side can be doped in order to produce the contact structure on the rear side of the photovoltaic cell.

Advantageously, the contact structure can be used on the back of the photovoltaic cell.

The doped region may be formed in the form of at least one main web with a plurality of side webs. The side panels may be arranged finger-shaped transversely to the main track. The main railway and the

Side lanes with conductors arranged thereon can be referred to as fingergrid. The side lanes may have a predetermined length and have no further connection to other doped areas except the main lane.

Another dopant may be introduced to provide another doped region. The further doping material may be different from the doping material. The further doped region can be formed as further doped tracks. The other tracks can be separated by gaps from the tracks. By means of the further doping material, a p-n junction can be formed between the doped region and the further doped region in order to separate electrical charges. By juxtaposed on one side, differently doped areas can a

Light incident side of the photovoltaic cell without shading structures are performed, whereby an efficiency of the photovoltaic cell can be increased. The tracks can be doped with a concentration of dopant, so that in the doped region a specific resistance, too

Sheet resistance or sheet resistance or specific sheet resistance, between 5 Ω / square (square) and 150 Ω / square,

in particular between 20 Ω / square and 60 Ω / square. Through a

Adjusting the resistivity, a balance can be found between the internal losses and the transmission losses.

A sheet resistance or sheet resistance describes the electrical resistance of a resistive layer when the resistive layer flows through an extension of the resistive layer in parallel. Accordingly, the resistance layer is traversed largely perpendicular to the layer thickness of the resistance layer. The sheet resistance has the unit Ω (ohms) and can be measured with a four-point method or four-point measurement or four-peak measurement familiar to the person skilled in the art. Alternatively or additionally, the sheet resistance can also be determined using the Van der Pauw, which is familiar to the person skilled in the art.

Measuring method are measured.

The interstices can be used with a lower concentration of

Doping material to be doped, as the webs. Due to a low concentration of the doping material in the interstices, transmission losses in the

Semiconductor material can be minimized while internal losses in the

Semiconductor material can remain at a very low level. Due to the different doping, the semiconductor material is well conductive where high current density prevails. Where there is no high current density, a low recombination rate is achieved.

The interspaces can be doped with a concentration of dopant, so that sets in the gaps, a resistivity or sheet resistance between 80 Ω / square and 500 Ω / square. By adjusting the resistivity, a balance between the

Internal losses and transmission losses are found.

The doping material may be introduced in a first pass in the region of the tracks and the spaces to the concentration of the

Doping material of the spaces to reach. In a second pass, the doping material can be introduced in the region of the webs to the To achieve concentration of the doping material in the doped region. By two successive passes, the doping can be achieved easily and quickly. For this purpose, no complicated devices for doping with different doping concentration are required.

A width of the webs and, alternatively or in addition, a width of

Spaces can be specified using a processing rule. The internal losses and the transmission losses may be deposited in the processing specification depending on the width of the webs and / or the width of the interspaces and / or the doping concentration. By the processing instruction, a minimum of the losses can be determined and the tracks are designed accordingly.

In the doping step, an ion implantation process may be used. The ion implantation can be used particularly advantageously for doping, since doping can thus be carried out in a very targeted manner.

According to one embodiment, the doped regions can be formed with phosphorus and used on the back of an n-type photovoltaic cell and boron-doped emitter. Thus, the doped region and the gaps may be formed with phosphorus and appropriately used on the back side of the n-type photovoltaic cell and boron-doped emitter.

Further, a photovoltaic cell is presented with a wafer having at least on one side a contact structure consisting of doped tracks and an applied conductor material, wherein the tracks project beyond the conductor material on both sides and the tracks are separated by gaps.

An advantage is also a computer program product with program code, which on a machine-readable carrier such as a semiconductor memory, a

Hard disk space or an optical storage can be stored and used to carry out the method according to one of the embodiments described above, when the program product is executed on a computer or a device. The invention will now be described by way of example with reference to the accompanying drawings. Show it:

Fig. 1 is a representation of a photovoltaic cell according to a

Embodiment of the present invention;

Fig. 2 is an illustration of a photovoltaic cell according to another

Embodiment of the present invention;

Fig. 3 shows a potential and current density distribution within a

Solar cell segment with a locally doped contact structure;

4 shows a potential and current density distribution within one

Solar cell segment with a surface-doped contact structure;

Fig. 5 is an illustration of a relationship between an internal

Series resistance of a plurality of solar cell types and a number of fingers of a contact structure of the solar cells;

Fig. 6 is an illustration of a relationship between an internal

Series resistance and a doped area fraction of a

Contact structure according to an embodiment of the present invention;

7 is an illustration of a relationship between a

Recombination rate and a doped area fraction of a

Contact structure according to an embodiment of the present invention; and

8 is a flowchart of a method for manufacturing a

Contact structure of a photovoltaic cell according to an embodiment of the present invention.

In the following description of favorable embodiments of the present invention are for the in the various figures

represented and similar elements acting the same or similar Reference numeral used, with a repeated description d

Elements is omitted.

1 shows an illustration of a photovoltaic cell 100 in accordance with a

Embodiment of the present invention. The photovoltaic cell 100 has a wafer 102 made of a semiconductor material. The photovoltaic cell 100 is contacted on both sides. For this purpose, a contact structure 104 is arranged in this exemplary embodiment on a rear side of the wafer 102. The contact structure 104 consists of doped tracks 106 and an applied conductor material 108. The conductor material 108 is formed as conductor tracks. The conductor material 108 is a metal-based material. In particular, the conductor material 108 is silver or a silver-based alloy. The webs 106 project beyond the conductor material 108 on both sides. The tracks 106 are separated by gaps 1 10. The webs 106 cover a surface portion of the back side of the wafer 102 designed for minimum losses and maximum efficiency. On the front side of the photovoltaic cell 100, the wafer 102 is doped over the whole area. There are the

Conductor tracks of the conductor material 108 opposite to the conductor tracks of the contact structure 104 aligned. Between the tracks on the front side, the wafer 102 is optically tempered to minimize reflection losses.

In an embodiment not shown, the photovoltaic cell 100 on the front side also has a contact structure according to the approach presented here. In this case, the doped tracks are doped at the front with a different doping material than the tracks 106 at the back. The differently doped tracks act as the base and emitter of the

Photovoltaic cell 100.

In an embodiment not shown, the photovoltaic cell 100 on the back of two different contact structures. In addition to the illustrated contact structure 104, the photovoltaic cell 100 has a further contact structure of further tracks and conductor material 108. The other tracks are also separated by gaps 1 10 of the tracks 106. The further tracks are doped with a different doping material than the tracks 106. As a result, the emitter and the base of the photovoltaic cell 100 are arranged side by side on the rear side of the photovoltaic cell 100. The Front of the photovoltaic cell 100 is not contacted in this embodiment, resulting in low Abschattungsverlusten.

In other words, a cross section of a solar cell 100 with partially doped BSF 106 (BSF doping = back-surface-field doping) is shown according to the approach presented here.

FIG. 2 shows a representation of a photovoltaic cell 100 according to a further exemplary embodiment of the present invention. The photovoltaic cell 100 essentially corresponds to the photovoltaic cell in FIG. 1. In addition to the photovoltaic cell shown in Fig. 1, the photovoltaic cell 100 in the

Spaces 1 10 a small doping 200 with the same

Doping material, as in the doped tracks 106 on. The low doping 200 results in an increased electrical conductivity of the back of the

Photovoltaic cell 100.

In one embodiment, to fabricate the contact structure 104, once the entire backside has been doped with the low doping 200. Then, the tracks 106 have been post-doped to achieve the high doping required for low contact resistance between the tracks 106 and the conductor material.

In one embodiment, to form the contact structure 104, the tracks 106 and the low doping 200 have been independently introduced into the wafer 102. In particular, by an ion implantation, the doping is well controlled and spatially well placed.

The approach shown in FIGS. 1 and 2 presents a double-sided contacted solar cell 100 with partially doped rear side. A structure 104 for a bilaterally contacted solar cell 100 with increased efficiency is described.

To improve the efficiency of industry-standard solar cells 100, the electrical and optical losses can be improved by introducing a dielectrically passivated and locally contacted backside. In this case, the locally contacting backside metallization 108 can be replaced by the use of a Screen printed Silver H-Grids 108, as it is already used on the cell front are used.

In order to reduce the contact resistance between the metallization 108 and the base 106, it is necessary to highly dope the surface at least in the area of the metallization 108 (the so-called back-surface field 106 doping). The doping can be carried out in several variants.

For example, the doping can be performed as PERT (Passivated Emitter and Rear Totally diffused) or as PERL (Passivated Emitter and Rear Locally diffused).

In the PERT concept, the entire area of the back of the solar cell is doped (100%), whereas in the PERL concept only the area under the

Metallization 108 is doped (usually 5-20% of the total area).

Both concepts have advantages and disadvantages. The electrical conductivity of the BSF doping improves the lateral conductivity in the PERT concept and thus reduces ohmic losses. On the other hand, the high doping leads to an increased backside recombination, so that the recombination losses of the cell increase. This is exactly the opposite with the PERL concept. As shown in Figures 3 and 4, the ohmic losses of an undoped back surface are always higher than those of PERT, and can be increased by itself

Compensate finger count only incompletely.

One possible approach is to lower the BSF doping of the PERT concept until an optimal compromise between recombination and transverse conductivity is found. However, this is limited by the fact that to minimize the contact resistance of the metallization 108, a certain minimum concentration of dopant must be present. In the case of metallizing pastes, this concentration is significantly above the dopant amount which is necessary to achieve the maximum efficiency.

The approach presented here is to introduce regions 106, 110 with differently high doping. This is a high

Dopant concentration below the metallization 108 arranged, which the Contacting possible. An average dopant concentration may be placed between the fingers of the metallization 108.

The approach presented here is under the fingers

highly doped region 106, which protrudes clearly above the metallized area in contrast to the PERL cell. Already with an area coverage of 50%, a conductivity is achieved that is similar to the PERT cell (100%).

Covering) is. Due to the lower coverage, the recombination at the back of the tent can be significantly reduced.

In a further embodiment, the region 110 between the highly doped regions 106 is also lightly doped. This can be z. B. to a

Improvement of long-term stability.

In the layout of the cell 100, the area coverage F may be between 20% and 90%. The area coverage fraction F is preferably 40-60%. When combined with an H-Grid, the number of fingers n can be between 40 and 150. (The width of the heavily doped regions 106 is then calculated to be ldop = r15.6 / n for a 15.6 cm solar cell.) The distances between the fingers can be variable. Likewise, the structure 104 can be combined with a full-surface metallization. Likewise, the structure 104 with a

Rear side emitter cell are combined. In this case, a partially doped FSF is used.

Electrically, the cell may have 100 p or n-type substrate 102. For example, the heavily doped region 106 may be doped with boron or phosphorus / arsenic. In the heavily doped region 106, it is possible to achieve film resistances of 5 to 150 ohms / square, that is to say resistance per area, preferably 20-60 ohms. The intermediate region 110 may be undoped or the sheet resistance may be 80-500 ohms / square.

During processing, the formation of the doping regions can occur

different types take place. For example, an ion implantation with a mask, a full area doping and a subsequent local

Re-etching, applying a local diffusion mask and a subsequent doping or application of local dopant sources such as doping glasses are performed.

Shown is an embodiment in which the remaining region 1 10 is low doped. In this case, the wafer 102 is highly doped under the fingers 108. In between, the wafer 102 is low doped. The width or interval of the doped regions 106 and spaces 110 is optimized. Usually they are the same width.

Doped areas 106 and spaces 1 10 form a fingergrid.

Fig. 3 shows a potential and current density distribution within one

Solar cell segment 300 with a locally doped contact structure 302. The contact structure 302 is here, in contrast to the approach presented here, from a doped region, which only the width of the applied

Conductor 108 has. Between the tracks 108, the wafer of the solar cell is undoped. The potential density and the current density are extremely high in the area of the contact structure 302. The potential density and the current density decrease rapidly with increasing distance from the contact structure 302. At a certain distance from the track 108, the potential density and the current density are below a display threshold. In the area of the contact structure 302, the potential density and the current density are so high that an electrical resistance of the semiconductor material of the wafer can lead to a heating of the material.

Ohmic losses occur mainly in the range of high current density (since P = J ^{2 *} rho). Areas of high current density occur mainly around the metallization 108. This effect is called current crowding.

Fig. 4 shows a potential and current density distribution within one

Solar cell segment 400 with a surface-covering doped contact structure 402 In contrast to the approach presented here, the contact structure 402 consists here of a closed doped surface on which the conductor track 108 is arranged. The surface is equally heavily doped throughout. The

Potential density and current density are high in the area of the conductor track. In comparison to the contact structure in FIG. 3, the potential density and the current density decrease significantly more slowly. A potential density and a current density are shown in the area of the entire doped surface. In areas away from metallization 108 (x> 0.05), only small losses occur. The equipotential lines are at a flat angle to the BSF. Accordingly, a high doping is not mandatory here.

FIGS. 3 and 4 show a potential and current density distribution (arrows) within a PERC / PERL and a PERT solar cell segment with 30 ohm BSF. The backside metallization is at x = 0 and x = 0.0035 cm. An equipotential front has been assumed for simplicity.

5 shows an illustration of a relationship 500 between an internal series resistance of a plurality of solar cell types and a number of fingers of a contact structure of the solar cells. The relationship 500 is plotted on a graph showing the number of fingers on the abscissa and on the abscissa

Ordinate has submitted the series resistance. For all solar cell types, the series resistance decreases as the number of fingers increases. At the same time, solar cells of the PERL type show a large decline in series resistance. Solar cells of the type PERT show a smaller decrease. However, that is

Series resistance of PERT cells with a 100 ohms back-surface field already at 40 fingers as low as the series resistance of the PERL cells at 1 10 fingers. For PERT cells with a 40 ohm back-surface field, the resistance is 30 percent lower. Shown is an internal series resistor for PERL and PERT cells with different numbers of fingers. Only the transverse line resistance is shown. Ohmic losses in the metallization are not taken into account. (Rabse = 2.5 ohms ^* cm, 160pm cell thickness). Fig. 6 is an illustration of a relationship between an internal one

Series resistance and a doped area ratio of a contact structure according to an embodiment of the present invention. In this case, two different embodiments 600, 602 are plotted in a common diagram. The diagram shows on the abscissa the proportion of area between zero percent area fraction and 100 percent area fraction. On the ordinate the series resistance in ohms is plotted. The first embodiment 600 is a photovoltaic cell with undoped spaces between heavily doped bands. The first embodiment is shown for example in FIG. The series resistance is at five percent area of the heavily doped bands about six times as high as a minimum achievable series resistance, at 100 percent area of the heavily doped area. The series resistance decreases rapidly in the first embodiment 600 with increasing doped area ratio and approaches asymptotically to the minimum value, which is not undershot. Even at a 40 percent area ratio, the series resistance is only ten percent higher than the minimum value. The second embodiment 602 is a photovoltaic cell with lightly doped gaps, as shown for example in FIG. Here, the series resistance also decreases with increasing area proportion of the heavily doped area. However, even at five percent areal proportion of the series resistance is only 30 percent higher than the minimum value. At 50 percent area share of the

Series resistance already reached the minimum value.

Shown is the internal series resistance of a solar cell according to the approach presented here for different area coverage portions of the heavily doped region (40 ohms). In one case, the intermediate region is undoped (red) in the other in a middle region (blue). It's just that

Transverse line resistance shown. Ohmic losses in the metallization are not taken into account. The photovoltaic cell has an equipotential front side. The resistance in the illuminated mode (homogeneous generation) is slightly higher. The representation is based on a Rbase of 2.5 ohm ^* cm, 160pm

Cell thickness, 90 fingers. Joe by weighting by area percentage is estimated.

J_80 ohms -90 fA. J_40 ohms - 150 fA. J_none -20.

Fig. 7 shows a representation of a relationship between a

Recombination rate and a doped surface portion of a contact structure according to an embodiment of the present invention. As in Fig. 6, the two different embodiments 600, 602 are plotted in a common diagram. The diagram shows on the abscissa the proportion of area between zero percent area fraction and 100 percent area fraction. The recombination rate is plotted on the ordinate. The recombination rate in both embodiments 600, 602 increases linearly with increasing area fraction. With 100 percent areal proportion, both exemplary embodiments 600, 602 has a recombination rate of 150. The first embodiment 600 has a recombination rate of 25 at five percent areal proportion. The second embodiment 602 has an area ratio of five percent

Recombination rate from 95 to.

By merging the information from Figures 6 and 7, an area fraction between 20 percent and 90 percent for both

Embodiments 600, 602 are implemented economically. An increased profitability results with a surface portion between 40 per cent and 60 per cent.

8 shows a flow chart of a method 800 for producing a contact structure of a photovoltaic cell according to an exemplary embodiment of the present invention. The method 800 includes a step 802, the

Providing, a step 804 of doping and a step 806 of the

Contacting. In step 802 of providing, a wafer for the

Photovoltaic cell provided. In step 804 of doping, an area portion of at least one side of the wafer is doped with a dopant to obtain a doped area. The doped region is formed as doped tracks. The tracks are separated by gaps. In step 806 of contacting, the doped region is contacted to make the contact structure. In this case, a conductor material is applied to the webs so that the webs project beyond the conductor material on both sides.

In one embodiment, an area fraction between 20 percent and 90 percent is doped in step 804 of the doping. In this case, an area share of 10 percent to 80 percent remains undoped. In particular, in step 804 of doping, an area fraction between 40 percent and 60 percent is doped. In this case, an area share of 40 percent to 60 percent remains undoped. With these areas, an optimum of conductivity and a minimum of recombination can be achieved.

In one embodiment, in step 804 of doping, the doped region is in the form of at least one major orbit having a plurality of

Side panels formed. The side panels become finger-shaped across the main line arranged. Several main tracks with their side panels can be arranged distributed on the photovoltaic cell.

In one embodiment, the side panels are arranged alternately to the main track.

In one embodiment, the side panels are disposed opposite the main track. The main and side panels form an H-shaped pattern, with the main line representing the transverse line. There may be a plurality of side panels on a main track.

In one embodiment, in step 804 of doping, another dopant is introduced to obtain another doped region. The further doping material is different from the doping material and the further doped region is formed as further doped tracks. The others

Railways are separated from the railways by gaps. The further doped region is arranged on the same side as the doped region. A side opposite the side is here undoped or slightly doped, and executed uncontacted.

In one embodiment, in step 804 of doping, the tracks are doped with a concentration of dopant so that a resistivity of between 10 ohms / m and 150 ohms / m is established in the doped region. In particular, in step 804 of doping, the tracks are doped with a concentration of dopant, so that a specific resistance between 20 ohms / m and 60 ohms / m is established in the doped region.

In one embodiment, in the doping step 804, the

Spaces doped with a lower concentration of the doping material than the webs. Thus, the spaces are weakly doped. Due to the weak doping, an electrical resistance is reduced in the intermediate space and thus also reduces electrical losses.

In one embodiment, in the doping step 804, the

Intermediate spaces doped with a concentration of dopant, so that in the Spaces a resistivity between 80 ohms / m and 500 ohms / m.

In one embodiment, in the doping step 804, the

Doping material is introduced in a first pass in the region of the tracks and the gaps in order to achieve the concentration of the doping material of the intermediate spaces. In a second round, the

Doping material introduced in the region of the webs in order to achieve the concentration of the doping material in the doped region. Instead of a variation of the doping strength is doped once. At the higher doping is implanted twice.

In one embodiment, in the doping step 804, a width of the paths and / or a width of the spaces is determined using a processing rule.

In one embodiment, in the doping step, 804 is entered

used in the ion implantation process.

The approach presented here results in an improvement of the

Cell efficiency through a reduction in effective backside recombination. It is only necessary to control a doping level. This simplifies the process over a "classical" selective doping as it is applied to selective emitters. The presented method 800 can with

Methods for avoiding edge shunts, such as an edge mask, are combined. The requirements for the alignment of the metallization are greatly relaxed because the metallization no longer has to be precisely aligned with highly doped areas. This results in a simplified implementation in the ion implanter compared to a two-stage doping. There are no moving masks necessary.

The embodiments described and shown in the figures are chosen only by way of example. Different embodiments may be combined together or in relation to individual features. Also, an embodiment can be supplemented by features of another embodiment. Furthermore, method steps according to the invention can be repeated as well as carried out in a sequence other than that described. If an exemplary embodiment comprises a "and / or" link between a first feature and a second feature, then this is to be read so that the embodiment according to one embodiment, both the first feature and the second feature and according to another embodiment either only first feature or only the second feature.

Claims

claims

1 . Method (800) for producing a contact structure (104) of a

A photovoltaic cell (100), the method (800) comprising the steps of:

Providing (802) a wafer (102) for the photovoltaic cell (100);

Doping (804) a surface portion of at least one side of the wafer (102) with a dopant to obtain a doped region (106), wherein the doped region (106) is formed as doped lines (106) and passing through the traces (106) Interspaces (1 10) are separated; and

Contacting (806) the doped region (106) to form the contact structure (104), wherein a conductor material (108) is applied to the traces (106) such that the traces (106) overhang the conductive material (108) on both sides.

2. Method (800) according to claim 1, wherein in step (804) of the doping, an area fraction between 20 percent and 90 percent, in particular between 40 percent and 60 percent, of the at least one side of the wafer (102) is doped.

The method (800) according to one of the preceding claims, wherein in the step of doping (804) the rear side is doped to produce the contact structure (104) on the back side of the photovoltaic cell (100).

A method (800) according to any one of the preceding claims, wherein in step (804) of doping, the doped region (106) is formed in the form of at least one major web having a plurality of side webs, the side webs being finger-shaped across the main web are. Method (800) according to one of the preceding claims, wherein in the step (804) of the doping, a further doping material is introduced to obtain a further doped region, wherein the further

Doping material is different from the doping material and the further doped region is formed as further doped webs and the other webs are separated by gaps (1 10) from the webs (106).

Method (800) according to one of the preceding claims, wherein in the step (804) of doping the tracks (106) are doped with a concentration of dopant such that in the doped area (106) a sheet resistance between 5 Ω / square and 150 Ω / square, in particular between 20 Ω / square and 60 Ω / square adjusts.

Method (800) according to one of the preceding claims, wherein in the step (804) of doping, the intermediate spaces (110) are doped with a lower concentration of the doping material than the tracks

(106) The method (800) according to claim 7, wherein in the step (804) of doping, the gaps (110) are doped with a concentration of dopant, so that in the gaps a sheet resistance between 80 Ω / square and 500 Ω / square.

Method (800) according to one of Claims 7 to 8, in which, in the step (804) of doping, the doping material is introduced in a first pass in the region of the tracks (106) and the gaps (110) to reduce the concentration of the doping material of the To reach spaces (1 10) and in a second pass the doping material in the region of the tracks (106) is introduced to the concentration of

Doping material in the doped region (106) to achieve.

A method (800) according to any one of the preceding claims, wherein in step (804) of doping, a width of the tracks (106) and / or a width of the spaces (110) are determined using a

Processing rule is set.

A method (800) according to any one of the preceding claims, wherein an ion implantation process is used in step (804) of doping.

1 1. Method (800) according to one of the preceding claims, in which the doped region (106) and the interstices (110) are formed with phosphorus and are used on the back side of the n-type base photovoltaic cell (100) and boron-doped emitter ,

12. A photovoltaic cell (100) with a wafer (102) having at least on one side a contact structure (104) consisting of doped tracks (106) and an applied conductor material (108), wherein the tracks (106) the conductor material ( 108) protrude on both sides and the webs (106) by gaps (1 10) are separated.