FR3048819A1 - LASER IRRADIATION DOPING COMPENSATION FOR THE MANUFACTURE OF HETEROJUNCTION SOLAR CELLS - Google Patents

Abstract

A method of making a solar cell structure, comprising the steps of: a) providing, on a first side of a crystalline semiconductor substrate, a stack comprising a first doped semiconductor layer (5) having a first type and on the first doped semiconductor layer, a second doped semiconductor layer (9) having a second conductivity type opposite to the first conductivity type, the first doped semiconductor layer and the second doped semiconductor layer. forming a junction, b) performing heat treatment with laser radiation on at least one block formed of the stack so as to generate a rearrangement of the junction dopant species and change the conductivity type from to least one zone of said second doped semiconductor layer (5) and to confer on this zone the first conductivity type (FIG. 1B).

Description

LASER IRRADIATION DOPING COMPENSATION FOR THE MANUFACTURE OF HETEROJUNCTION SOLAR CELLS

DESCRIPTION

TECHNICAL FIELD AND PRIOR ART

The present invention relates to the field of semiconductor devices having doped semiconductor regions having different types of different conductivity formed on the same support and applies to the implementation of solar cells, in particular solar cells. with heterojunction contacted on the rear face.

Such cells are provided with doped regions having opposite conductivity types on the same face, called "back face", on which contacts are provided while the opposite face, called "front face" is preferably not provided with contact to increase the performance of the cell.

To produce a first N-doped region and a second P-doped region on the same face of a semiconductor substrate, one method consists in doping the first region, for example by ion implantation, while protecting the second region by means of first masking and then doping the second region by ion implantation while protecting the second region by a second masking.

Such a process generally requires the realization of many steps and significant manufacturing costs.

There is the problem of finding a new and improved process with respect to the aforementioned drawbacks.

STATEMENT OF THE INVENTION

One embodiment of the present invention relates to a method for producing a structure for a solar cell, in which a block formed of a stack comprising a first semi-crystalline layer is provided on a first face of a crystalline semiconductor substrate. doped conductor having a first conductivity type (N or P) and on the first doped semiconductor layer, a second doped semiconductor layer having a second conductivity type (P or N) opposite to the first conductivity type, the first doped semiconductor layer and the junction-forming doped semiconductor layer (PN or NP), and then performing a heat treatment with a laser on the block so as to reorganize dopant species of the junction and give the block the first type of conductivity (N or P).

There are two types of conductivity, one type of conductivity when the electrons are the majority carriers and the holes of the minority carriers (in particular for a zone having a resultant overall doping of type N) and a type of opposite conductivity, when the holes are majority carriers and electrons are minority carriers (especially for an area with a global P-type doping).

By virtue of the laser irradiation, a "resultant" layer is obtained from the first doped semiconductor layer and the second doped semiconductor layer, while the counter-type dopings compensate each other to obtain an N-type final effective doping. or P. It is thus possible to transform a junction or a diode into an ohmic contact, without having to carry out an additional ion implantation step.

By using a laser, such a transformation is carried out in a localized manner and without necessarily using masking.

Said block may be formed on a first region of the first face of the substrate while on a second region of the first face another block is disposed, this other block comprising a doped semiconductor layer having a second type of conductivity opposite the first type of conductivity and advantageously forming a junction with the substrate.

The laser treatment can be carried out so as to irradiate the said block with the laser without irradiating the said other block. This makes it possible to transform the junction of said block into a doped region of single conductivity, without modifying the junction formed between the other block and the substrate. It is thus possible to produce on the first face of the substrate contacts of different polarities while limiting the number of process steps necessary for this.

In particular, it is possible to implement these contacts of different polarities without having to perform several steps of successive implantations.

According to a particular implementation of the method, the doped semiconductor layer and the second type of opposite conductivity may be the second doped semiconductor layer formed in step a) by deposition opposite said first region and said second area of the first face.

According to a possibility of implementing the method, it may furthermore comprise, after step b), the formation of a contact on said zone of first conductivity type of said block and of another contact on said semi-layer. doped conductive and second conductivity type of said other block. the first doped semiconductor layer and the second doped semiconductor layer are advantageously based on α-Si: H hydrogenated amorphous silicon.

The method may further comprise a step of forming on a second face of the substrate opposite to the first face: a layer of a doped semiconductor material and having a second conductivity type opposite to the first conductivity type.

According to a possibility of implementing the method, a first semiconductor interface layer of intrinsic semiconductor material is disposed between the crystalline semiconductor substrate and the first doped semiconductor layer.

According to an implementation possibility of the method, a second interface layer based on intrinsic semiconductor material is disposed between the first doped semiconductor layer and the second doped semiconductor layer.

The solar cell may be a heterojunction cell, in particular a heterojunction cell contacted only by the back face.

BRIEF DESCRIPTION OF THE DRAWINGS Other characteristics and advantages of the invention will emerge more clearly on reading the following description and with reference to the accompanying drawings, given by way of illustration only and in no way limiting.

FIGS. 1A-1C illustrate steps of a method for transforming, by means of laser irradiation, a junction into a doped region having a single type of conductivity;

FIGS. 2A-2C illustrate different test structures making it possible to compare the electrical characteristics of a semiconductor structure implemented using a method according to the invention with a standard solar cell;

FIG. 3 illustrates various current-voltage characteristics obtained by means of measurements made on the structures of FIGS. 2A-2C;

FIGS. 4A-4C illustrate an implementation of a semiconductor structure for a solar cell in which a laser doping compensation step is performed;

FIGS. 5A-5D illustrate results of characteristic measurements of a solar cell carried out on a structure as implemented by the method of FIGS. 4A-4C in comparison with a reference solar cell;

FIGS. 6A-6D illustrate an exemplary method according to the invention for producing a heterojunction solar cell and contacted on the rear face;

Figs. 7A-7C illustrate an exemplary implementation of a step of the method of Figs. 6A-6D;

Identical, similar or equivalent parts of the different figures bear the same numerical references so as to facilitate the passage from one figure to another.

The different parts shown in the figures are not necessarily in a uniform scale, to make the figures more readable.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

A method of "doping compensation" in which a junction, i.e. a region having doped regions having respective types of opposite conductivity into a doped region and having a single conductivity type, is transformed into This invention will be described in conjunction with FIGS. 1A-1C.

In this example, the doping compensation method is applied to a semiconductor structure as implemented to manufacture a solar cell.

The semiconductor structure comprises a substrate 1 based on crystalline semiconductor material such as crystalline silicon, which is doped and may have a first type of conductivity. For example, the crystalline semiconductor material is N-doped.

On a first AR face of the substrate 1 also called a rear face rests a stack in which a first doped semiconductor layer 5 and a second doped semiconductor layer 9 are formed. The doped semiconductor layers 5, 9 have respective types of opposite conductivity and thus provide a junction.

In this example, the first semiconductor layer 5 is N-doped and thus comprises the first type of conductivity. The first semiconductor layer 5 is typically based on amorphous semiconductor material such as hydrogenated amorphous Si (a-Si: H (n)) and can have a thickness for example between 10 and 60 nm, typically between 10 and 60 nm. nm and 35nm, the thickness being chosen in the upper part of this range when this semiconductor layer 5 is located on the rear face of the substrate, ie the face opposite to that by which the light is intended to penetrate. The first semiconductor layer 5 may be doped with phosphorus and have a dopant concentration of between 10 4 atoms cm -1 and 10 4 atoms cm -1, in particular of the order of 10 7 atoms cm -1. · ^.

The second semiconductor layer 9 is P-doped and thus has a second conductivity type opposite to the first conductivity type.

The second semiconductor layer 9 is typically based on amorphous semiconductor material such as doped hydrogenated amorphous Si (a-Si: H (p)).

The second semiconductor layer 9 may have a thickness of, for example, between 3 nm and 20 nm, typically between 5 nm and 15 nm, in particular between 8 nm and 10 nm. The second semiconductor layer 9 may be doped with the boron and have a dopant concentration of between 10 .mu.m atoms and 10 .mu.m atoms, in particular of the order of 10 .mu.m atoms. ^.

An interface semiconductor layer 3 based on an amorphous semiconductor material may be interposed between the substrate 1 and the first doped semiconductor layer. This interface semiconductor layer 3 is typically based on intrinsic amorphous semiconductor material such as intrinsic hydrogenated amorphous Si (a-Si: H (i)) and may have a thickness of, for example, between 2 nm and 15 nm. nm, in particular between 2 and 5 nm. The semiconductor layer 3 interface may also be a layer of micro-doped material, that is to say, little doped.

By "micro-doped" we mean a doping typically in a range between 1E17 and 1E20 atoms * cm · ^.

Similarly, between the first doped semiconductor layer 5 and the second doped semiconductor layer 9 can be provided another semiconductor layer 7 interface based on amorphous semiconductor material. This other semiconductor layer 7 interface may be an intrinsic material such as intrinsic hydrogenated amorphous Si (a-Si: H (i)) or micro-doped. Typically, the interface semiconductor layer 7 has a thickness of, for example, between 2 and 15 nm, typically between 5 and 10 nm, in particular between 6 nm and 8 nm. In this example, the semiconductor layers 5, 7, 9 form an N-1-P type junction.

The amorphous semiconductor layers 3, 5, 7 and 9 can be produced for example by a plasma enhanced chemical vapor deposition (PECVD) technique on the semiconductor substrate 1.

The semiconductor substrate 1 covered with amorphous semiconductor layers 3, 5, 7 and 9 may constitute the starting structure of the doping compensation method (FIG. 1A).

The doping compensation method provides for a modification of the conductivity type of at least one determined region of the stack of semiconductor layers 5, 7, 9, and in particular of at least one region of the second doped layer 9 including a surface portion of the second doped layer 9. This modification is implemented using a localized heat treatment by means of a laser L (FIG. 1B).

A sufficiently high laser power is chosen to allow a rearrangement of the doping species in the determined region. The laser power is at the same time provided sufficiently limited to allow not to modify the structure of the intrinsic amorphous semiconductor layer 3.

The power of the laser is preferably adapted so as to preserve the first doped semiconductor layer 5. In other words, the laser is penetrated as little as possible into this layer 5 and thus the intrinsic amorphous semiconductor layer 3 is preserved, but also the interface between the substrate 1 and the amorphous semiconductor layer 3. The laser used typically emits in the ultraviolet range with a power of between 10 mW and 1.5W, preferably in a range of 17 mW-25mW. The power of the laser is adapted according to the thickness of the semiconductor layers 5, 7, 9 of the stack. The laser irradiation makes it possible to implement a reorganization or rearrangement of the doping impurities of the NIP junction and to transform the stack of layers 5, 7, 9 into a doped resultant layer in which the dopings of opposite types compensate for each other. to obtain a final effective doping of the first type, in this N-type example. An NlP diode or junction is thus transformed into a region having a single overall effective doping, here of N type, in other words in a region having a single type of conductivity. (figure IC). In the figures, the resulting layer 10 after rearrangement to a final effective doping of N type which is denoted N * in the figures.

A measurement of QSSPC type (for "Quasi-steady-state photoconductance method") carried out on a structure of the type of that illustrated in FIG. 1C but also comprising a passivation layer on the front face of the substrate 1 has been realized. The passivation layer is for example a thick layer of hydrogenated amorphous silicon (a-Si: H). Such a test shows a lifetime of carriers that may be greater than 3 ms.

To compare the electrical behavior between the starting structure of the method as illustrated in FIG. 1A and another structure obtained after the laser doping compensation step, test samples are produced from these two types of structures. (Figures 2A, 2B, 2C).

The test samples are provided with contacts 11a, 11b, 11c located on the rear face AR. These contacts 11a, 11b, 11c may be formed of a transparent conductive oxide layer 13 such as ITO on which rests a metal layer 14, for example based on Ag. Typically, a first pair of contacts 11a, 11b, spaced apart from each other by a first distance di and a second pair of contacts 11b, 11c, are separated from one another by a second distance d2, here such that d2> di.

A first test sample formed from the structure of FIG. 1A is shown in FIG. 2A, while FIG. 2B shows a second test sample formed from the structure obtained after the laser doping compensation method. is illustrated. There is also provided a third reference sample formed of the substrate 1 and the semiconductor layers 3, 5. Such a sample, illustrated in FIG. 2C, makes it possible to know the intrinsic contact resistance of a superposition of layers (n). Si / (i) a-Si: H / (n) a-Si: H.

In a solar cell, in particular heterojunction, such layer superposition typically plays the role of BSF structure (for "back-surface field"). From these samples, current-voltage characteristics can be determined according to a measurement-type test configuration of the transmission line or length measurement transfer transmission also known by the acronym TLM (for "Transfer Length Method"). In such a test, electrodes are applied to the contact pairs 11a-11b and 11b-11c, and the resistance between the electrodes 11a-11b and 11a-11c is measured by applying a voltage to the contacts 11a-11b and 11a-11c. llc by measuring the resulting current.

FIG. 3 gives Cioo, C200, C300 curves of current measurement results as a function of the voltage l (V) on the three aforementioned type of samples and respectively illustrated in FIGS. 2A, 2B, 2C, for a distance between -contacts given. The characteristic Cioo curve of the first sample confirms a diode behavior of the starting structure while the curve C200 characteristic of the structure obtained after laser irradiation shows a behavior similar to that of an ohmic contact (curve C300). The TLM measurement test also shows that the measured contact resistance on the structure obtained at the end of the localized laser irradiation doping compensation process may be lower than that of a conventional ohmic contact structure.

For the resulting doped layer 10 of the transformation of the junction after laser irradiation can be used to form a BSF structure in a heterojunction solar cell, it is preferably verified that this does not generate a residual defect or that there is have no such defects at interfaces with other layers.

To experimentally test this hypothesis, a test sample is made as shown in Figures 4A-4C.

Reference is now made to FIG. 4A giving a semiconductor stack formed from the structure described above in connection with FIG.

On a second face of the substrate 1, also called the front face AV, a semiconductor 19 is formed doped in a conductivity type opposite to that of the substrate. In this example, the semiconductor layer 19 is P-doped and typically based on amorphous semiconductor material such as hydrogenated amorphous Si (a-Si: H (P)).

A semiconductor layer 17 based on a semiconductor material is typically interposed between the substrate 1 and the first doped semiconductor layer. This semiconductor layer 17 may be based on amorphous semiconductor material such as intrinsic hydrogenated amorphous Si (a-Si: H (i)) or micro-doped Si. The amorphous semiconductor layers 17 and 19 are also typically formed by PECVD.

The laser treatment L is then performed on the rear face so as to modify the overall doping of the stack of semiconductor layers 5, 7, 9 and transform the N-1-P junction into a generally N-doped layer 10 (FIG. 4B).

Then, on the front face AV and on the rear face AR, conductive transparent oxide layers 21, 23 are formed, for example based on ITO, then contacts 25a, 25b, 25c, for example silver respectively on the layers 21. , 23 transparent oxide (Figure 4C). The transparent oxide layers 21, 23 may be deposited by PVD (Physical Vapor Deposition). The contacts 25a, 25b, 25c may be formed by screen printing or by PVD deposition and etching.

The contact 25c made on the rear face may be in the form of a continuous layer as shown in FIG. 4C or in the form of distinct pads similar to the contacts 25a, 25b made on the front face.

FIGS. 5A, 5B, 5C, 5D illustrate various results of measurements of characteristics carried out on solar cells whose structure is such as that illustrated in FIG. 4C. By way of comparison, similar measurements have been made on reference cells whose structure is similar to that of FIG. 4A before laser irradiation and does not include either the intrinsic semiconductor layer 7 or the P-doped semiconductor layer 9 .

FIG. 5A is representative of results of Jsc (zero voltage) open circuit current measurements carried out on four C 1, C 2, C 3, C 4 cells of structures similar to that of FIG. 4C and which were obtained after exposure to a laser beam with powers of 17 mW, 19 mW, 21 mW and 23 mW, respectively. Complementary measurements were carried out in parallel on five reference cells Crefl, Cref2, Cref3, Cref4, Cref5.

FIG. 5B gives, in turn, results of Voc open-circuit voltage measurements (at zero voltage) for these same cells C 1, C 2, C 3, C 4, Cre 1, Cref 2, Cref 3, Cref 4, Cref 5.

In FIG. 5C, there are results of form factor measurements (ratio between the maximum power provided by the cell on the Jsc * Voc product) of C_1, C_2, C3, C4, Crefl, Cref2, Cref3 and Cref4 cells. Cref5, which are given while Figure 5D is representative of energy efficiency measures performed on these same cells.

The measurement results presented in FIGS. 5A-5C show that the C_1, C_2, C_3, C_4 cells having undergone the laser doping compensation method as described above have comparable performances to the Crefl, Cref2, Cref3, Cref4 reference cells. , CrefS. In particular, the form factor FF of the cells having undergone the doping compensation method can be improved. The measurement results show that intrinsic defects were not added to the single conductivity type layer 10 resulting from the reorganization of dopants. The open circuit voltage Voc of the cells C_1, C_2, C_3, C_4 is comparable to those of the reference cells, which indicates that the interface between the crystalline silicon substrate 1 and the active amorphous layers is not degraded.

The doping compensation method described above in connection with FIGS. 1A-1C may, by the use of a laser beam, be applied locally to a structure in order to transform at least one junction-forming region into a doped region. single conductivity type, while retaining at least one other non-transformed region of this junction, that is to say with conductivity zones of opposite types N and P or P and N. This method applies particularly to the implementation of implementation of regions of opposite conductivity types for heterojunction solar cells and contacted by the rear face.

A HIT (Heterojunction with Intrinsic Thin Layer) heterojunction (RCC) cell of the Rear Contact Cell (RCC) type or IBC (for Interdigitated Back Contact) implements a collection of minority carriers and majority of carriers on their backs. The implementation of such a cell requires forming contacts of different types on the same side of a substrate.

An example of a method of manufacturing such a solar cell will now be given in connection with Figures 6A-6D.

Here we start from a substrate 1 based on crystalline semiconductor material, for example crystalline silicon, which can be N doped, and which is preferably cleaned and textured. Texturing of the substrate 1 (not shown in FIGS. 6A-6D) at least at its front face is typically performed in order to reduce the reflectivity of the cell surface and to increase the optical path of the light in the device . This operation makes it possible to form a relief on the surface, for example in the form of micrometric pyramidal patterns. The texturing may be carried out by mechanical action or by chemical etching, for example using a bath of an alkaline solution, for example based on KOH.

The back side can be kept flat. This makes it possible in particular to facilitate the realization of the issuer and BSF patterns. In order to protect a face of the non-textured substrate during the texturing operation, for example the rear face AR, it is possible to form at least one protective layer still called a barrier layer on this face. The barrier layer is for example SiO 2 when the texturing is carried out by etching based on KOH.

In a variant, the rear face is also textured in the same way as for the light-receiving front face.

On the front face AV of the substrate 1, an amorphous semiconductor layer 17, for example amorphous hydrogenated intrinsic Si (a-Si: H (i)) or micro-doped, is then formed by full PECVD-type deposition. a layer 19 of hydrogenated nitride (-SiN (H) -) also deposited by PECVD. The full plate stack of layers 17, 19 makes it possible both to passivate the surface of the crystalline silicon substrate 1 and to act as an antireflection coating.

On the rear face AR of the substrate 1, semiconductor stacks 21a, 21b are formed (FIG. 6A) comprising a semiconductor layer 3 based on amorphous material such as intrinsic hydrogenated amorphous Si (a-Si: H (i) ), then an N-type doped semiconductor layer 5, the semiconductor layer 5 having the same type of conductivity as the substrate 1. The semiconductor layer 5 is typically based on amorphous semiconductor material such as hydrogenated amorphous Si (a-Si: H (n)).

The stacks 21a, 21b are disjoint and may be formed by localized PECVD, using for example a mask during deposition.

As a variant, the stacks 21a, 21b are formed by full-plate deposition on the rear face and then by localized etching of patterns, for example using photolithography of a masking or gravitating dough deposited by screen printing or else by ablation. using a laser.

A semiconductor layer 7 is then formed based on intrinsic amorphous semiconductor material such as intrinsic hydrogenated amorphous Si (a-Si: H (i)) and a doped semiconductor layer 9 having a conductivity type opposite to that of the semiconductor layer 5. In this example, the semiconductor layer 9 is P-doped. The semiconductor layer 9 is typically based on amorphous semiconductor material such as doped hydrogenated amorphous Si (a-Si). : H (p)).

The semiconductor layers 7, 9 are deposited full plate so as to cover portions of the rear face of the substrate 1 and so as to cover the stacks 21a, 21b. The stacks 21a, 21b covered with the stack of layers 7, 9 form blocks 23a, 23b provided with a junction, in this NP type example.

Next, (FIG. 6B) a laser treatment L located in blocks 23a, 23b is carried out in order to transform the junctions into doped zones 30a, 30b having a single type of conductivity. The laser is typically a UV laser of wavelength for example of the order of 355 nm, with a power in the range of 10 to 50 mW, typically 17mW-25mW. A laser writing speed of between 1000 and 4000 mm / s, typically of the order of 2000 mm / s, can be used. The frequency may, for its part, be for example between 100 and 400 kHz, typically of the order of 200 kHz. In order to expose blocks 23a, 23b with a width of several tens of micrometers to the laser, a beam of diameter, for example of the order of 20 μm, which can be displaced in steps of several micrometers, for example between 1 and 10 μm, typically of the order of 3 μm.

The laser treatment makes it possible to rearrange the doping species of the NP junctions in such a way as to transform them into doped regions with a single overall resultant doping, in this N-type example. Conducting opposite conductive semiconductor regions of the blocks 23a, 23b is transformed. in a region having a single type of conductivity (Figure 6C). The fact of having a plane back face makes it possible to perform the laser treatment step with a low power while maintaining a controlled penetration depth.

Preferably, apart from the blocks 23a, 23b, the remaining regions of the rear face of the substrate 1 are not exposed to laser radiation.

One or more other unexposed blocks 32 are thus formed formed of the stack of semiconductor layers 7, 9 with their initial doping. Laser irradiation makes it possible to simplify the production of doped regions having different types of doping on the rear face of the cell.

By virtue of this step, blocks 23a, 23b having global doping (in this N-type example) different from that (in this P-type example) of other blocks 32 made on one and the same face of the substrate are obtained. this without having to implement complex or expensive successive location steps.

It is then possible to form an anti-reflection layer, for example made of SiN, at the front face AV of the substrate 1, if this has not already been deposited previously during the manufacturing process.

Then, metal contacts 41 are formed on the laser-treated areas 30 and the unexposed areas 32, respectively, to form BSF contacts 40 and emitter contacts 42. The contacts 41, 42 may be formed of a transparent conductive oxide layer 13 such as ITO on which rests a metal layer 14, for example based on Ag.

Contacts 40, 42 may be arranged so that at least one emitter contact 42 and at least one contact 40 of BSF are in the form of interdigitated combs.

In the example of the method which has just been given in connection with FIGS. 6A-6D, contacts of different types have been formed on the rear face of a substrate. A similar method with laser irradiation doping compensation can be used to create this kind of contacts on the front face or on both sides of the same substrate.

A particular example of a method for producing the stacks 21a, 21b previously described in connection with FIG. 6A, will now be described (FIG. 7A-7C).

In this example, the front face AV, and in particular the layer 19 of hydrogenated nitride (-SiN (H) -) is textured.

The semiconductor layer 3 is deposited based on amorphous material such as intrinsic hydrogenated amorphous Si (a-Si: H (i)), and then the semiconductor layer 5 doped with N type doping.

Then, this stack is then coated with a protective layer 54 of silicon oxide (SiO 2), for example by PECVD ("Plasma Enhanced Chemical Vapor Deposition") 54 of thickness which can be for example between 50 and 500 nm, typically 200 nm. Then comes to locally expose to a laser one or more areas of the stack of layers 3, 5, 54 that it is desired to remove (Figure 7A). By way of example, the following laser etching conditions can be provided: scanning speed, for example of the order of 2000 mm / s, frequency for example of the order of 200 kHz, power below IW, - spacing of 3 pm between each successive laser firing.

It is preferable that the ablation of the semiconductor layer 5 is partial in order to preserve at certain points an interface between the semi-conducting layer 3 based on amorphous material and the substrate 1. In the case of a partial removal of the layer semiconductor 5, a chemical etching step is then performed to finalize the etching of the layer 5 and the semiconductor layer 3 and thus obtain at least one stack 21a. Chemical etching using KOH is typically carried out (Figure 7B). The oxide layer 54 is then removed for example using HF.

Then, the semiconductor layers 7, 9 are deposited so as to cover an exposed portion of the rear face of the substrate 1 and so as to cover the stack 21a (FIG. 7C).

A method as described above is not limited to an implementation of a structure from an N-doped starting crystalline substrate and can be applied starting from a P-doped crystalline semiconductor material substrate.

In one or other of the examples of the method which have just been given, the crystalline substrate 1 and the amorphous layers formed on this substrate 1 are based on silicon. A laser doping compensation method as described above can be applied to other semiconductor materials, for example to stacks comprising one or more III-V semiconductor materials.

Furthermore, a laser doping compensation method is not limited to transforming a NIP or NP junction into a region having a single conductivity type and having an effective N-type doping. The doping compensation method laser also applies to the transformation of a PIN or PN junction into a region of a single conductivity type and has effective P-type doping.

Claims (9)

A method for producing a heterojunction solar cell structure, comprising the steps of: a) providing, on a first face of a crystalline semiconductor substrate (1): a block formed of a stack comprising a first doped semiconductor layer (5) having a first N or P conductivity type and on the first doped semiconductor layer (5), a second doped semiconductor layer (9) having a second conductivity type, P or N, opposite the first type of conductivity, the first doped semiconductor layer (5) and the second semiconductor layer (9) doped forming a junction, b) performing a heat treatment using laser radiation on the block (23a, 23b) so as to modify the conductivity type of at least one zone of said second doped semiconductor layer (5) and to give the block the first conductivity type. 2. Method according to claim 1, wherein the block (23a, 23b) is formed on a first region of the first face (AR) and in which on a second region of the first face (AR) another block (32) is disposed, said other block comprising a doped semiconductor layer (9) having a second conductivity type opposite to the first conductivity type, the laser treatment being carried out so as to irradiate said block with the laser without irradiating said other block. The method according to claim 2, wherein the doped semiconductor layer (9) and the second opposite conductivity type is said second doped semiconductor layer (9) formed in step a) by deposition with respect to said first region and on said second region of the first face (AR). The method according to one of claims 2 or 3, further comprising after step b), forming a contact (40) on said first conductivity type zone of said block and another contact (42). ) on said doped semiconductor layer (9) and the second conductivity type of said other block. 5. Method according to one of claims 2 to 4, wherein the first doped semiconductor layer (5) and the second doped semiconductor layer (9) are based on hydrogenated amorphous silicon a-Si: H. 6. Method according to one of claims 1 to 5, the method further comprising a step of forming on a second face (AV) of the substrate (1) opposite to the first face (AR): a layer made of a semi- doped conductor (19) having a second conductivity type opposite to the first conductivity type. 7. Method according to one of claims 1 to 6, wherein a first semiconductor interface layer (3) of intrinsic semiconductor material is disposed between the crystalline semiconductor substrate (1) and the first semiconductor layer. -conductive (5) doped. 8. Method according to one of claims 1 to 7, wherein a second interface layer (7) based on intrinsic semiconductor material is disposed between the first doped semiconductor layer (5) and the second semi layer. -conductor (9) doped. 9. Method according to one of claims 1 to 8, wherein the solar cell is a heterojunction cell.