1 OBJECT OF THE INVENTION

The object of the invention is to improve the manufacture of the technically useful metamaterial, free of critical electronic setbacks. Such setbacks companion almost irrevocably the amorphization obtained with a focused ion beam scanning the wafer.

The development focuses on the main step in the new metamaterial manufacture that is the crystalline material modulation by an appropriate intermediate operation of the buried amorphization. The enhancement obtained finally makes it possible to benefit from the secondary electron generation by freeing it of bad electron transport resulting from "hard" structural defects "polluting" the crystallinity of the metamaterial manufactured previously.

The efficient amorphization according to the invention, allowing the transformation of the crystalline silicon that meets the requirements imposed by the industrial conditions. A so-called "right" or "flat" amorphization allows the SEG- MATTER manufacture with the appropriate electronic properties. A very large ion spot of recent industrial equipment can be perfectly adapted, i.e., controlled, standardized, stabilized and homogeneous, thus meeting for the first time the requirements set by the electronic properties of the GPC (Giant PhotoConversion) of a new-generation of the light-to-electricity converters.

Therefore, this invention permits to take away one of the most important obstacle to the carrying out the Giant PhotConversion industrial manufacture process.

2. DEFINITIONS

SEGTON is a unit of the Secondary Electron Generation Tuned on Nanoscale, i.e., conditioned elemental unit cell of matter characterized by its specific and highly useful set of electron energy levels that is adapted for an efficient multistage light-to- electricity conversion. SEGTON allows a low-energy electron photogeneration of additional free-carriers and a carrier multiplication cycle. SEG-MATTER is a SEGTON based metamaterial, i.e., the specific crystalline material for an efficient light-to-electricity conversion that is constituted of homogeneously distributed SEGTONS that form an ordered superlattice and are immersed in a specific physical environment bordered by nanomembranes. A new crystallinity, bringing desired functionalities, becomes possible because of adequate physical forces available in nanoscale.

"Right" or "flat" amorphization is the amorphization resulting from an ion implantation with a wide homogeneous beam spot, which makes it possible to avoid or at least reduce the generation of extend persistent structural defects that appear usually after the ion implantation. The resulting insertion of a new artificial crystalline phase is done somewhere in the natural crystalline lattice with the very limited destruction and without any incurable damage that results usually from the ion implantation (Figures 1 and 2).

Remark: without this "right" or "flat" amorphization passage bringing a structural disorder due to dense point defects leading to a local amorphization, the metamaterial could not therefore be formed in a useful arrangement with energy budget available and economically acceptable on large industrial scale.

Clever transformation of the crystal lattice: creation of the desired crystal lattice variant with a reduced and cheap energy expenditure in the permissible temperature range.

The thermal budget it is the totality of thermal energy necessary to realize the specific process throughout the manufacturing process and more particularly the thermal energy for the full post-implantation treatment.

The focused ion beam for scanned amorphization is the ion beam having a focused spot of the usual diameter of 2 to 3 mm, which sweeps repeatedly, multi- directionally and sufficiently densely the surface of the wafer in order to standardize the amorphisation in space.

"Hard", residual and persistent structural defects: structural defects concern several atoms of the lattice requiring high temperature regimes of 800 to 1000°C and more to be cured or neutralized. They "pollute" the crystallinity of the metamaterial and are thus "harmful" because the cure thermal budgets and temperature regimes available during heat treatment under the conditions of the manufacturing process at allowed temperatures does not exceed 500-550°C. They represent multiple constraints and distortions characterized by a multitude of extrinsic electron levels distributed in the gap. This results in accelerated recombination of the secondary carriers neutralizing the effect of the secondary generation. These badly cured defects also cause an accelerate recombination of the primary photocarriers.

"Soft" structural defects are structural defects requiring moderate temperature regimes of 500-550°C maximum to be totally cured or neutralized.

Metamaterial refers to an artificial material, in particular silicon, having physical properties that go beyond known natural properties. The metamaterial retains its original chemical composition. More specifically, it takes the form of at least one continuous or discontinuous layer, but also a field of beads or grains or of any shape such as agglomerates or aggregates and which have in particular a very high optical absorption, a generation/conversion of low energy secondary electrons, multiplication of low energy electrons, specific electron transport, increased sensitivity to excitation intensity and strong optical nonlinearity.

SEG-MATTER nanolayers is the demarcated space inserted in the crystalline semiconductor medium, occupied by the silicon material that has been uniformly transformed into a metamaterial.

Nanomembrane: this is the heterointerface or boundary surface acting as an interface, (vertical, horizontal, parallel to the surface, more or less spherical or not) where will be the change of electron energy bands, conduction mode and so on. This is, for example, the interface between SEG-MATTER and the surrounding silicon mass material, which will be characterized by the modification of the electron transport mode.

a/c (amorphized mass/crystalline mass) transition zone results from the layer-by- layer recrystallization of the amorphized material during the solid phase epitaxy. Thus the recrystallized amorphizatioh leaves under certain conditions an a/c transition zone that on its crystalline side (so-called <c-Si>) contain numerous divacancies (about 10 ²⁰ cm ^"3 ) , Which are confined in a nanolayer around the amorphization. The operation is as if the divacancies were injected into the <c-Si> layer through the a/c interface. Being in an environment conditioning them physically very strongly, they are transformed into SEGTONs of technical utility.

a-Si: amorphized silicon phase

<a-Si>: amorphized silicon phase under a mechanical constrain

c-Si: crystalline silicon phase

<c-Si>: crystalline silicon phase under a tensile strain Vacancy: a point structural defect forming a specific structural unit.

Divacancy: point structural defect formed by two interconnected vacancies founding a specific structural unit.

Amorphized nanoaggregates: amorphized aggregates or nanogroups of locally transformed matter that has been inserted regardless the appropriate manufacture process within the crystalline medium.

Amorphized nanoclusters are aggregates or nanogroups of the intensely locally transformed crystalline material.

GPC [Giant PhotoConversion]: the photoconversion allowing the optimal exploitation of the light energy of the entire solar spectrum by converting the light into electricity through an additional mechanism of the electron secondary low-energy generation and multiplication.

Inserted nanostructures: multilayer nanostructures (that coat amorphized nanoaggregates) containing a SEG- ATTER, i.e. a metamaterial that is able to provide numerous centers for low-energy generation and multiplication of secondary electrons resulting from collisions of hot electrons when optimally distributed inside the emitter of the converter.

3. PROBLEM SOLVED

In order to valorize the low-energy secondary electron generation, it is necessary to determine and avoid the problems related to poorly controlled electronic properties of the GPC converters. Such problems that appear even after the successful creation of the SEG-MATTER are destroying the photoconversion efficiency.

To obtain a good SEG-MATTER, it is necessary to go through a preliminary step, namely "right" or "flat" local amorphization of the crystal lattice of silicon with the aid of an adequate ion beam. The invention provides a solution to this problem thanks to the extended spot of the ion energy deposition. Its effective control causing the penetration of ions in the semiconductor by a plane thermal shock wave (figure 3). In this way, unidirectional vibrations of the crystal lattice do not produce multidirectional tugging or shear effects that can turn into "hard" structural defects (figure 4). Therefore, the so-called "right" or "flat" amorphization transforms crystal lattice adequately to meet the needs of the industrial fabrication of a good SEG- MATTER having with its surroundings required good electronic properties.

By eliminating the blockading problem of the inadequate amorphization polluting the crystallinity of the metamaterial and of its environment, the invention allows the manufacture of GPC converters having a technically useful low-energy generation of secondary electrons.

The required quality of the metamaterial called SEG-MATTER comes from a thermal treatment carried out previously within a strictly limited range from 500°C to 550°C. Since these temperatures are rather low, this above mentioned treatment has to last long enough to ensure a certain subsequent quality of the semiconductor crystallinity. These temperatures are also insufficient to cure some hard structural defects and there isn't any possibility to reduce the duration of the thermal treatment in order to meet the rapid cadence of an industrial line of manufacture.

The goal of the present invention is to solve the problems coming from the first step of manufacture of the metamaterial referred to as SEG-MATTER, i.e. to bury suitable amorphizations within the crystalline silicon wafer.

4. PRIOR STATE OF THE ART AND ITS DISADVANTAGES

The inventor has come to the conclusion that the significant improvement of the efficiency of the conversion of light into electricity by means of a crystalline silicon device with a single collecting junction is only possible thanks to a clever insertion into the converter emitter of a crystalline metamaterial with highly specific properties.

The metamaterial in question, hereinafter referred to as SEG-MATTER, is filled or even saturated with specific crystalline elementary units, hereinafter referred to as SEGTON, which are capable of releasing so-called secondary electrons by means of a low-energy collisional mechanism. The insertion of SEG-MATTER goes through a preliminary step, namely the localized buried amorphization of the crystalline silicon lattice with the aid of an ion beam.

Unfortunately, conventional amorphization using a focused ion beam sweeping the silicon wafer inevitably leads to structures with many structural defects. The final phase separation implemented with this method is shown in figures 5, 6 and 7. As such, this operation is not usable for the industrial manufacture of converters with secondary generation. The disqualifying aspects can be summarized as follows: - the poor control of the material modulation during the impact of the ion beam and, consequently, its post implantation curative annealing;

- the exaggerated requirements concerning the thickness of the initial amorphization layer to keep a sufficient maneuver margin for healing recrystallization;

- the severe limitations regarding the design and architecture of the converter to the location of buried substructures in the crystal lattice;

- obstructions of the local electron transport around nanostructures buried in a damaged crystalline material, mainly due to a non-radiative recombination; - complications concerning the collection of both secondary and primary charge carriers.

It is well known to a person skilled in the art that post implantation thermal treatment cures some types of structural defects. This treatment must be effected within a limited range of suitable temperatures and with a reasonable thermal budget of manufacture and conditioning of the SEG-MATTER.

Unfortunately, the scanning (sweeping) ion beam amorphization, respecting the imposed limitations, produces among others residual and persistent structural defects, which remain insensitive to post-implantation heat treatment under the conditions permitted. In reality, they are remediable only with annealing at temperatures much higher, that is to say, contraindicated or inaccessible for the SEG-MATTER technology.

Residual and persistent structural defects are highly detrimental to electronic transport around the SEG-MATTER. They destroy the beneficial effects of the secondary electron generation. Thus, very promising potential improvements become not available due to the shortcomings of its technological implementation.

The proper material modulation requires appropriate solution because it lies at the basis of manufacture and functioning of improved converters. It became evident that the current method of buried amorphization by a focused ion spot sweeping the surface of the wafer should be completely revised. Its thermodynamic characteristics are too random leading to inefficient structural transformations. That explains why the devices thus obtained cannot fulfill the potential performance of the I ig ht-to-e lectri city conversion due to technical exploiting of the secondary electron generation. The previous devices thus obtained cannot fulfill the specifications of successful converters capable of the full exploitation of the solar energy. The technological application of the SEG-MATTER requires the valorization of all its potential effects. A radical solution results in good or excellent quality of amorphization process leading to a good crystalline of the SEG-MATTER as well as of the material around the buried structures.

5. SUMMARY OF THE INVENTION

The invention is related to a method of creating an efficient photovoltaic metamaterial within an all-silicon light-to-electricity converter. Its first phase concerns to form a buried amorphized region at a predetermined depth. This is realized by means of an ion implantation using a wide ion spot. A subsequent thermal treatment of recrystallization is then applied to reduce or eliminate structural defects remaining after the amorphization.

Because of the excellent quality of the initial transformation, the duration of the several consecutive sequences at 500°C-550°C can be considerably shortened. The thus created device structure has properties that qualify it for practical applications and to be manufactured on an industrial cadence line production. Figures 8 and 9 show HREM images at the atomic scale of the upper and lower abrupt c-Si/a-Si heterointerfaces of required quality.

Thanks to the excellent quality of the initial transformation of the semiconductor crystallinity the post-implantation thermal treatment carried out in a larger range of temperatures (500°C to 700°C) permits to reduce and even to eliminate more structural defects that remained after amorphization. The treatment duration at temperatures higher than those applied previously is, therefore fundamentally reduced but however, it allows further the cure of some "hard" structural defects that are unattainable at lower temperatures. Such a large reduction of the converter annealing time is also very beneficial for the industrial processing on mass production lines permitting a great cadence of the fabrication.

6. DIFFICULTIES OVERCOME BY THE INVENTION

The invention aims primarily at improving the process of burying amorphization to make it on the one hand more efficient in the manufacture and operation of the metamaterial and on the other hand industrially well applicable. In figure 10 is shown a schematic view of the comparison between multilayer structures resulting from the modulation of the crystalline material with ion spots: (a) focused leading to a deeper and thicker amorphized layers, which requires a long-term thermal treatment at admitted temperature, and (b) wide that allows to bury amorphization less deeply and substantially thinner.

The industrial metamaterial for the giant photoconversion can only result from a specific transformation of the crystal silicon lattice, which is an unavoidable local amorphization using an ion beam. This stage of the manufacture must imperatively respect some special requirements to avoid obstacles of the usual implantation of ions making it useless.

This includes the following indications:

- using the appropriate ion beam (energy, dose) that must be stabilized and well controlled throughout the whole implantation cycle;

- achieving the clearest possible separation of the two silicon phases, one amorphized and another crystalline already before the post-implantation thermal treatment;

- reducing the quantity or even the total absence of mutual insertions of the amorphized phase and the crystalline phase in the form of nanoparticles;

- obtaining a good homogeneity and flatness of the amorphized layer, with the thinnest possible if even inexistent transition zone between the amorphized and crystalline phases and containing trace amount of a mixed medium of amorphous and crystalline phases;

- strong limitation or a total elimination of "hard" structural defects;

- clear lowering the thermal budget that is necessary for a material modulation at a temperature range of 500-550°C due to the considerably increased quality of the just transformed structures (after implantation and before post-implantation thermal treatment).

7. ADVANTAGES OF THE INVENTION

The metamaterial obtained according the present invention by the so-called "right" or "flat" amorphization, is well-structured from the beginning, requires very little post implantation heat treatment contrary to the prior technology processing which is complicated and too expensive. The thermodynamics of such an ion implantation makes it possible to avoid or reduce undesirable residual and persistent structural defects. This complies with the manufacture specifications of the converters with secondary electron generation. In particular, the ion beam adequate in energy, dose and shape, well-stabilized and well controlled during implantation provides:

- the clearest possible separation of the two silicon structural phases, one amorphized and another crystalline even just after the amorphization, that is to say before the post-implantation thermal treatment,

- a very small amount of mutual insertions of the amorphized and crystalline structural phases in the form of nanoparticles,

- a good homogeneity, consistency and flatness of the buried amorphized layer, - a very thin transition zone lying between the amorphized and crystalline phases with its amorphized/crystalline mixed-phase medium,

- a total absence or a very small number of undesirable "hard" structural defects,

- the very low need for thermal budget for the post-implantation treatment at temperatures of the order of 500-550°C,

- the widened freedom in the design and architecture of the new converter, resulting from the reduction of the initial thickness of buried layers.

Metamaterial obtained by the so-called "right" or "flat" amorphization, is well- structured from the beginning, and requires very little post-implantation heat treatment unlike the prior technological treatment, which is complicated and too expensive.

The thermodynamics of such ion implantation avoids or reduces undesirable residual and persistent structural defects. This is in accordance with the manufacturing specifications of converters with a low-energy generation of secondary electrons.

In particular, the ion beam adequate in energy, dose and spot shape, well- stabilized and well-controlled during implantation provides:

- a suitable solution for industrial applications of SEG-MATTER in the mass manufacture of converters exploiting the low-energy generation of secondary electrons;

- an extremely reduced thermal budget (of approximately an order of magnitude) of the manufacturing of the SEG-MATTER; - the clearest possible separation of the two structural phases of silicon, one amorphized and the other crystalline even just after amorphization, that is to say before the post-implantation heat treatment;

- a very small amount of mutual insertions of the amorphized and crystalline structural phases in the form of nanoparticles;

- a good homogeneity, consistency and flatness of the buried amorphized layer;

- a very thin amorphized/crystalline transition zone between the amorphized and crystalline phases;

- total absence or a very small number of undesirable "hard" structural defects;

- the very low thermal budget required for post-implantation treatment even at higher temperatures of the order of 500-700°C;

- the widened freedom in the design and architecture of the new converters, resulting from the reduction of the initial thickness of the buried amorphized layers.

8. LIST OF THE FIGURES

FIGURE 1 is a schematic sectional view illustrating the wide ion beam used for implantation.

FIGURE 2 is a schematic view illustrating the movement of the wafer under a wide ion beam during implantation.

FIGURE 3 Example of a crystalline lattice with plane thermal shock wave at the origin of unidirectional vibrations of the crystal lattice.

FIGURE 4 Example of a crystalline lattice with multidirectional vibrations producing tugging or shear effects that can turn into "hard" structural defects FIGURE 5 is a view showing c/a heterointerfaces, c/a transition zones and an amorphized nanolayer after a 30 min heat treatment at 500°C (TEM images) in which a-Si denotes the amorphized region and c-Si the crystalline mass.

FIGURE 6 is a magnification of FIG. 5 with the detail of a crystalline inclusion designated nc-Si.

FIGURE 7 is a visualization of the technically useful a-Si/c-Si interface with magnification of the amorphized insertion, in TEM and SEM images. FIGURE 8 is a HREM image at the atomic scale of the first abrupt c-Si/a-Si heterointerface.

FIGURE 9 is a HREM image at the atomic scale of the second abrupt a-Si/c-Si heterointerface.

FIGURE 10 is a schematic view of a multilayer structure resulting from the modulation of the crystalline material which appears after a buried amorphization with an ion spot: (a) focused sweeping the surface of the wafer and (b) wide according to the invention. This first step, of major importance, leads in the case (a) to deeper and thicker amorphized layers, which requires a long-term thermal treatment at admitted temperature. In contrast, the large ion spot, case (b) allows to bury amorphization less deeper and substantially thinner.

FIGURE 11 represents a graph of the recrystallization rate of an amorphization buried within the crystalline silicon with orientation [ 00] as a function of the temperature (Arrhenius curve).

FIGURE 12 is a detail of figure 10 illustrating the shifting of buried heterointerfaces due to the "right" amorphization.

9. DESCRIPTION OF THE FIGURES

The attached figures schematically show the means used and the results obtained. They are not up to scale.

Figure 1 shows an example of a schematic sectional view illustrating the wide beam of ion implantation with a wide spot bombarding the wafer surface. The spot area of this beam represents a few tens of cm ² .

Figure 2 shows a schematic view illustrating the movement of the target wafer during ion implantation under a horizontal, stabilized and fixed wide beam.

Figure 3 shows a propagation of the heat plane wave induced by a wide spot ion implantation within a crystalline lattice.

Figure 4 schematizes the spatial distribution of thermal properties in heat diffusion with generic multi-directional heat-flows inducing extended structural defects. Such propagation of the heat within a crystalline lattice results from the ion implantation with a focalized spot sweeping the wafer. Figures 5 and 6 show TE images of example buried amorphizations realized with a focused ion beam scanning the wafer surface, it is well visible that both the c/a heterointerfaces and both the c/a transition zones are not correctly planified after an allowed 30 min thermal treatment at 500°C. The enlargement of the transition c/a zone of figure 6 shows a crystalline inclusion designated nc-Si. The amorphized nanolayer contains several crystalline inserts of the size of about 5 nm. Such an amorphization is technically useless because of the poor structural quality and mostly important electronic damages.

Figure 7 shows TEM image of flattened a-Si/c-Si interfaces that are technically useful. An enlargement in SEM image at the level of the amorphized nanolayer makes it possible to distinguish three components of the buried nanoscale Si-layered system: the crystalline part (c-Si), the amorphized part (a-Si) and two transition zones, which form <c-Si> nanolayers of the SEG-MATTER.

Figures 8 and 9 show examples of the so-called "right" or "flat" amorphization. In this case, the initial a/c interfaces are sufficiently regular to become near perfectly planar during the thermal treatment available at 500°C.

Figure 10 shows schematically the improvement of « ordered » transformations of the crystalline semiconductor array coming from the thermodynamics of the "right" or "flat amorphization. When one compares the results thus obtained: a) relates to a buried amorphization according to the previous method and b) relates to the burried amorphization according to the present invention. The TEM picture visualizes the local modification of the crystallinity after the implantation and the subsequent post-implantation thermal treatment. The zones where are located extended structural defects are called c-Si-d. In heavily damaged structures, they are largely spread. The upper and lower mechanically relaxed silicon crystalline mass Si after the thermal treatment is called c-Si. The « ordered » thermodynamics of transformations within the semiconductor crystalline lattice leads to the buried "right" or "flat" amorphization, which characterizes the improvements according to the present invention related to several aspects: 1) thinning of the c-Si superficial layer, 2) thinning of the transformed upper layer after c-Si-d amorphization, 3) thinning of the transformed lower layer after c-Si-d amorphization. The c-Si mass outside and around the buried amorphized layer is practically free of residual extended and persistent defects. Figure 11 shows the recristallisation rate of a buried amorphization during the post-implantation solid state epitaxy as a function of the temperature in the case of crystalline silicon with [100] orientation (Arrhenius curve). The subsequent thermal treatment leading to a partial recrystallization of the buried amorphization is necessary to create one or more well-controlled nanolayers of the photovoltaic metamaterial. This meatmaterial is stuffed with elementary crystalline units that are conditioned to generate secondary electrons. The transition a/c zone shifts to the center of the amorphized layer progressively layer-by-layer with the curing process and orders itself on the crystalline side (called <c-Si>) thanks to the solid-state epitaxy. At the same time, the extended structural defects are healed or cured. This is all the more easy since a good quality amorphization avoids the more difficult to heal extended defects. The allowed temperature of the thermal treatment can be higher and leads to the better healing of the structure during a mostly shorter time. This is very important regarding the industrial production.

Figure 12 shows a detail of figure 10 of relative movements of buried interfaces according to a wide ions beam amorphization referred to as a "right" or "flat" compared to the previous buried amorphization that is obtained with a focalized beam sweeping the wafer surface.

10. DETAILED DESCRIPTION

The invention will be fully understood after the reading of the following description.

Amorphisation

After a phase of preparation of the silicon wafer called hereinafter target wafer according or similar to the initial phase as described in the previous patents, including the PN junction formation, a "right" or « flat » amorphisation process is carried out by means of an implanter working with a large stabilzed and controlled ion beam and spot, the kind of which is shown in the first appended figures.

It is proceeded to the creation of an amorphized region by means of the ion implantation method referred to as "right" or "flat" amorphisation at a predetermined depth and with a predetermined thickness in the crystalline silicon mass of the emitter. This amorphization is carried out by using a wide-beam and wide-spot ion implanter, stabilized and controlled throughout the implantation cycle, which induces planar heat waves moving in the target crystalline mass in the direction of propagation of the incident ions, avoiding effects of multidirectional tightness or shearing.

The implantation of ions is implemented with silicon ions or phosphorus ions.

The area of the wide-spot projected on the target wafer is at least a few tens of cm ² .

The implantation of ions is carried out in the crystalline mass of the emitter in the vicinity of the front face of the wafer.

The ion beam is fixed and the semiconductor target wafer is translated by being scanned by the ion spot on its front face.

The ion beam bombarding the semiconductor target wafer has a substantially planar wave through which, despite the low energy expenditure, the thermodynamics of the semiconductor crystal material transformations leads to a structure practically free of extended and persistent residual structural defects.

It results in the creation in the emitter of a buried nano scale silicon layered system containing at least one active metamaterial nano layer, embedded with numerous low-energy secondary generation centers.

The ion beam bombarding the semiconductor target wafer induces thermal shock waves propagating in the semiconductor crystal lattice and generating thermal agitations that are homogeneous and appear along the axis of implant propagation with a minimal probability of lateral vibrations.

This « right » or « flat » amorphization as described above brings a lot of important advantages.

It requires however a most efficient control of the ion penetration in the semiconductor wafer. This control provides the very plane thermic shock waveform. In this way, the unidirectional vibrations of the crystalline lattice along the propagation axis are not likely to provoke dislocations effects or multidirectional shearing effects which lead to « hard » structural defects. Consequently this kind of amorphization allows a suitable modulation of the crystalline lattice which provides the opportunity to create a good quality metamaterial while maintaining good electronic properties of the transformed converter. Post-implantation thermal treatment

A post-implantation thermal treatment takes place thereafter which consists in several phases of exposure to heat with a control of recrystallisation. The first phase is rather short at about 500-550°C and is followed by phases at higher temperature up to 700 °C.

Globally, this post-implantation thermal treatment of the "right" or "flat" amorphization is done at relatively high temperatures up to 700°C.

Excellent amorphization quality not only allows the use of higher temperatures, but also shortens the total time of heating, which leads to a significant reduction of the thermal budget.

The duration of the first phase of this post-implantation thermal treatment that is performed at a temperature around 500-550°C is therefore reduced to a few minute time duration.

Furthermore this amorphization reduces the total duration of the thermal treatment to about 30 minutes.

This reduction is possible thanks to the « right » or « flat » amorphization as mentioned hereabove.

The results as to quality of the metamaterial and the very few defects created are outstanding. The energy savings are also a high advantage as to the industrial production capability.

The expanded range of the process temperatures (500°C-700°C) as well as the thermal treatment duration are very much appreciated for an industrial production.

The higher temperatures possible for the thermal treatment ease mostly the healing of residual defects of the crystalline lattice.

The solution according to the present invention helps maintaining the good crystallinity of the semiconductor lattice outside the amorphized layer.

This invention relates also to the product resulting from the carrying out of the above method as a photovoltaic all-silicon converter.