Three-dimensional LED optoelectronic device

Abstract

Three-dimensional light-emitting diode optoelectronic device This description relates to an optoelectronic device (5) comprising a first light-emitting diode (GLED) comprising three-dimensional semiconductor elements, each corresponding to a microwire, a nanowire, or a conical or frustoconical element of micrometer or nanometer size, and an active area covering each three-dimensional semiconductor element, the first light-emitting diode being configured to emit radiation (RL) with an emission spectrum for which the light intensity is greater than 80% of the maximum light intensity of the spectrum over a first wavelength range greater than 30 nm and for which the light intensity is greater than 50% of the maximum light intensity over a second wavelength range less than the first range increased by 30 nm;and a bandpass optical filter (F_LED) covering the first light-emitting diode. Figure for the abbreviation: Fig. 3;

Description

Title of the invention: Three-dimensional LED optoelectronic device technical field

[0001] The present application relates to an optoelectronic device, in particular a display pixel for a display screen or for a backlight panel, comprising three-dimensional light-emitting diodes based on semiconductor materials, and its manufacturing process. Previous technique

[0002] A light-emitting diode (LED) based on semiconductor materials generally comprises an active region, which is the area of ​​the LED from which the majority of the electromagnetic radiation emitted by the LED is emitted. The structure and composition of the active region are adapted to obtain electromagnetic radiation with the desired properties. In particular, it is generally desirable to obtain narrow-spectrum electromagnetic radiation, ideally substantially monochromatic.

[0003] We are particularly interested here in optoelectronic devices with three-dimensional light-emitting diodes, that is to say, light-emitting diodes each comprising a three-dimensional semiconductor element of micrometer or nanometer size extending along a preferred direction, for example a microwire or a nanowire, and whose active area covers the three-dimensional semiconductor element. In particular, a three-dimensional light-emitting diode is said to be of the radial type when its active area extends at least over the lateral walls of the three-dimensional semiconductor element.

[0004] The central wavelength of the radiation emitted by a three-dimensional radial-type light-emitting diode depends in particular on the diameter of the three-dimensional semiconductor element on which the active area of ​​the light-emitting diode rests.

[0005] A method for manufacturing optoelectronic devices includes forming three-dimensional radial LEDs on a wafer and cutting the wafer to separate the optoelectronic devices. With known methods for manufacturing three-dimensional radial LEDs, including epitaxial growth steps, where the growth conditions should theoretically lead to obtaining LEDs of the same dimensions on the same wafer of three-dimensional semiconductor elements, in practice a significant overall dispersion in the diameters of the elements is observed. three-dimensional semiconductors are present across the entire plate, even if local dispersion remains low. This results in a significant overall dispersion of the central wavelengths of the radiation emitted by light-emitting diodes formed from the same plate, which can reach 20 nm.

[0006] For the fabrication of an optoelectronic device such as a pixel for a display screen or a backlight panel, a dispersion of the central wavelength of the radiation emitted by the optoelectronic device of less than 2 nm is generally required. It is then necessary to test optoelectronic devices formed from the same wafer to select those with the desired properties. These steps increase the manufacturing cost of the optoelectronic devices. Summary of the invention

[0007] An embodiment overcomes all or part of the drawbacks of known three-dimensional light-emitting diode optoelectronic devices.

[0008] An object of an embodiment is to precisely control the central wavelength of the radiation emitted by the optoelectronic device.

[0009] An object of an embodiment is to reduce, or even eliminate, the selection steps of optoelectronic devices formed from the same plate.

[0010] One embodiment provides for an optoelectronic device comprising a first light-emitting diode comprising three-dimensional semiconductor elements, each corresponding to a microwire, a nanowire, or a conical or frustoconical element of micrometric or nanometric size, and an active area covering each three-dimensional semiconductor element, the first light-emitting diode being configured to emit electromagnetic radiation (LR) with an emission spectrum for which the light intensity is greater than 80% of the maximum light intensity of the spectrum over a first wavelength range greater than 30 nm and for which the light intensity is greater than 50% of the maximum light intensity over a second wavelength range less than the first range increased by 30 nm; and an optical bandpass filter covering the first light-emitting diode.This advantageously allows the optoelectronic device to have a narrow emission spectrum while the light-emitting diode has a broad emission spectrum, thus reducing the manufacturing constraints of the light-emitting diode.

[0011] According to one embodiment, the overall dispersion of the equivalent diameters of the three-dimensional semiconductor elements of the first light-emitting diode is between 2% and 100%, preferably between 3% and 25%, more preferably between 5% and 25%, of the average equivalent diameter of the semiconductor elements. three-dimensional conductors of the first light-emitting diode. The overall dispersion can be greater than that due solely to manufacturing processes, which simplifies the constraints for manufacturing three-dimensional semiconductor elements.

[0012] According to one embodiment, the central wavelengths of the radiation emitted by the active areas of the first light-emitting diode of the optoelectronic device are between 400 nm and 480 nm. This makes it possible to produce light-emitting diodes with three-dimensional elements emitting in the blue.

[0013] According to one embodiment, each three-dimensional semiconductor element has an equivalent diameter between 0.05 pm and 2 pm.

[0014] According to one embodiment, the optical bandpass filter has a full bandwidth of less than 50 nm. According to another embodiment, the optical bandpass filter has a maximum transmission at a wavelength between 430 nm and 480 nm.

[0015] According to one embodiment, the optoelectronic device comprises a second light-emitting diode having the same structure as the first light-emitting diode, and a block of a first photoluminescent material covering the second light-emitting diode. This enables the realization of a display pixel.

[0016] According to one embodiment, the bandpass optical filter does not cover the second light-emitting diode. Therefore, the efficiency losses due to the bandpass optical filter only concern the first light-emitting diode.

[0017] According to one embodiment, the anode of the first LED is not common with the anode of the second LED and / or the cathode of the first LED is not common with the cathode of the second LED. The first and second LEDs can be controlled separately.

[0018] According to one embodiment, the optical bandpass filter has a maximum transmission at a wavelength between 430 nm and 480 nm, and the block of the first photoluminescent material is configured to absorb the radiation emitted by the second light-emitting diode and convert it into radiation at a wavelength between 510 nm and 570 nm.

[0019] According to one embodiment, the optoelectronic device comprises a third light-emitting diode having the same structure as the first light-emitting diode, and a block of a second photoluminescent material, different from the first photoluminescent material, covering the third light-emitting diode.

[0020] According to one embodiment, the bandpass optical filter does not cover the third light-emitting diode.

[0021] According to one embodiment, the anode of the first light-emitting diode is not not common with the anode of the third LED and / or the cathode of the first LED is not common with the cathode of the third LED.

[0022] According to one embodiment, the optical bandpass filter has a maximum transmission at a wavelength between 430 nm and 480 nm, and the block of the second photoluminescent material is configured to absorb the radiation emitted by the third light-emitting diode and convert it into radiation at a wavelength between 600 nm and 720 nm.

[0023] According to one embodiment, the three-dimensional semiconductor elements of the first light-emitting diode are based on a III-V or II-VI compound.

[0024] One embodiment also provides a method for manufacturing optoelectronic devices comprising the following steps: - to form on a plate the first light-emitting diodes, each comprising three-dimensional semiconductor elements, each corresponding to a microwire, a nanowire, or a conical or truncated conical element of micrometric or nanometric size, and an active area covering each three-dimensional semiconductor element, each first light-emitting diode being configured to emit radiation with an emission spectrum for which the light intensity is greater than 80% of the maximum light intensity of the spectrum over a first wavelength range greater than 30 nm and for which the light intensity is greater than 50% of the maximum light intensity over a second wavelength range less than the first range increased by 30 nm; - to form a bandpass optical filter covering the first light-emitting diode for each optoelectronic device; and - cutting the plate to separate the first light-emitting diodes.

[0025] This advantageously allows the optoelectronic devices formed on the same plate to have the same narrow emission spectrum while the light-emitting diodes have broad, possibly shifted, emission spectra, thus reducing the manufacturing constraints of the light-emitting diodes.

[0026] The first light-emitting diodes are formed by epitaxial growth. According to one embodiment, the process includes a step of forming on the plate a mask comprising openings, and a step of growing the three-dimensional semiconductor elements in the openings, in which the overall dispersion of the equivalent diameters of the openings is between 2% and 100% of the average equivalent diameter of the three-dimensional semiconductor elements of the first light-emitting diode. Brief description of the drawings

[0027] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0028] [Fig.1] represents, for several plates, the median wavelength of the radiation emitted by the light-emitting diodes of the plate as a function of the median diameter of the light-emitting diodes of the plate;

[0029] [Fig.2] represents, for several plates, the maximum wavelength of the radiation emitted by the light-emitting diodes of the plate as a function of the median diameter of the light-emitting diodes of the plate;

[0030] [Fig.3] is a partial and schematic cross-sectional view of an embodiment of an optoelectronic device with light-emitting diodes;

[0031] [Fig.4] is a partial and schematic cross-sectional view of an embodiment of a light-emitting diode;

[0032] [Fig.5] is a partial and schematic top view of an embodiment of the arrangement of the light-emitting diodes of the optoelectronic device represented in [Fig.3];

[0033] [Fig.6] schematically represents a curve of evolution of the luminous intensity of the radiation emitted by the light-emitting diodes of the optoelectronic device of [Fig.3];

[0034] [Fig.7] schematically represents the curve of evolution of the luminous intensity of the radiation emitted by the light-emitting diodes shown in [Fig.6] on which is superimposed the response curve of the optical filter of the optoelectronic device of [Fig.3];

[0035] [Fig.8] schematically represents a curve of evolution of the luminous intensity of the radiation emitted by the optoelectronic device of [Fig.3];

[0036] [Fig. 9] is a partial, schematic cross-sectional view of another embodiment of a light-emitting diode optoelectronic device; and

[0037] [Fig.1OA], [Fig.1OB], [Fig.1OC], [Fig.1OD], and [Fig.1OE] are cross-sectional views of structures obtained at successive stages of an embodiment of a manufacturing process for the optoelectronic device of [Fig.1]. Description of the implementation methods

[0038] The same elements have been designated by the same reference numerals in the different figures. In particular, structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional, and material properties. For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed. In particular, the connections The electrical properties of the light-emitting diodes in an optoelectronic device are not described.

[0039] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements coupled together, this means that these two elements can be connected or linked through one or more other elements.

[0040] In the following description, when reference is made to absolute positional qualifiers, such as "front," "back," "top," "bottom," "left," "right," etc., or relative positional qualifiers, such as "above," "below," "superior," "inferior," etc., or to orientational qualifiers, such as "horizontal," "vertical," etc., unless otherwise specified, reference is made to the orientation of the figures or to an optoelectronic device in a normal operating position. Furthermore, unless otherwise indicated, the terms "insulator" and "conductor" are taken to mean "electrically insulating" and "electrically conductive," respectively.

[0041] Unless otherwise specified, the expressions "approximately", "roughly", and "in the order of" mean within 10%, preferably within 5%.

[0042] In the following description, the internal transmittance of a layer corresponds to the ratio between the intensity of the radiation exiting the layer and the intensity of the radiation entering the layer. The absorption of the layer is equal to the difference between 1 and the internal transmittance. In the following description, a layer is said to be transparent to radiation when the absorption of radiation through the layer is less than 60%. In the following description, a layer is said to be absorbing to radiation when the absorption of radiation in the layer is greater than 60%. When radiation has a spectrum with a general "bell-shaped" form, for example, a Gaussian shape, having a maximum, the wavelength of the radiation, or central or principal wavelength of the radiation, is the wavelength at which the maximum of the spectrum is reached.In the following description, the refractive index of a material corresponds to the refractive index of the material for the wavelength range of the radiation emitted by the optoelectronic device. Unless otherwise specified, the refractive index is considered to be substantially constant over the wavelength range of the useful radiation, for example, equal to the average of the refractive index over the wavelength range of the radiation emitted by the optoelectronic device.

[0043] The present invention relates to the manufacture of optoelectronic devices comprising at least one light-emitting diode formed from three-dimensional semiconductor elements of nanometer or micrometer size, in particular microwires, nanowires, or conical or frustoconical elements of micro- metric or nanometric, notably pyramids.

[0044] A three-dimensional semiconductor element of nanometer or micrometer size is defined as a three-dimensional structure of elongated shape, for example cylindrical, along a preferred direction, of which at least two dimensions, called minor dimensions, are between 5 nm and 2.5 pm, preferably between 50 nm and 2.5 pm. The third dimension, called the major dimension, is greater than or equal to 1 time, preferably greater than or equal to 5 times, and even more preferably greater than or equal to 10 times, the largest of the minor dimensions. In some embodiments, the minor dimensions may be less than or equal to about 1 pm, preferably between 100 nm and 1 pm, more preferably between 100 nm and 800 nm. In some embodiments, the height of the three-dimensional semiconductor element may be greater than or equal to 500 nm, preferably between 1 pm and 50 pm.The term "microwire" or "nanofil" refers to a three-dimensional semiconductor element with a cylindrical or nearly cylindrical shape. In the following description, the term "wire" is used to mean "microwire or nanowire".

[0045] The cross-section of wires can have various shapes, for example, oval, circular, or polygonal, including triangular, rectangular, square, or hexagonal. It will be understood that the term "equivalent diameter" used in relation to a cross-section of a wire designates a quantity associated with the wire in that cross-section, corresponding, for example, to the diameter of the disk having the same area as the cross-section of the wire.

[0046] In the following description, embodiments will be described for an optoelectronic device with light-emitting diodes comprising three-dimensional semiconductor elements corresponding to wires. However, it is clear that these embodiments can also relate to an optoelectronic device with light-emitting diodes whose three-dimensional semiconductor elements are conical or frustoconical elements of micrometer or nanometer size, in particular pyramids.

[0047] Tests were carried out to characterize the dispersion of the central wavelength of the radiation emitted by light-emitting diodes (LEDs) formed on 200 mm diameter semiconductor wafers. For the tests, the LEDs were radial in type and formed by metal-organic chemical vapor deposition (MOCVD). Furthermore, the three-dimensional semiconductor elements of the LEDs were wires. The LEDs, and in particular the wires, were formed under identical growth conditions for all wafers, so that the LEDs should theoretically have the same structure and the same dimensions.

[0048] Figures 1 and 2 represent, for several plates as a function of the median diameter Dmed of the LED wires on the plate, respectively the median wavelength Xmed and the maximum wavelength Xmax of the radiation emitted by all the LEDs on the plate. In Figures 1 and 2, each point corresponds to a plate. The median diameter Dmed is determined from one hundred wires located at the center of the plate. In Figures 1 and 2, the lines D1 and D2 were obtained by linear regression. Figures 1 and 2 illustrate the wavelength dispersion resulting from the LED formation processes by epitaxial growth.

[0049] Figure 3 is a partial, schematic cross-sectional view of an embodiment of an optoelectronic device 5 with nanowires or microwires. The optoelectronic device 5 comprises, from bottom to top in Figure 3: - a substrate 10 comprising opposite faces 12 and 14, the upper face 12 being preferably flat at least at the level of the light-emitting diodes; - a germination layer 16 made of a material promoting the growth of threads and disposed on face 12, which may not be present; - an insulating layer 18 covering the germination layer 16 and comprising openings 20 exposing portions of the germination layer 16; - at least one GLED comprising elementary LEDs (a single GLED comprising six elementary LEDs is shown as an example in [Fig.3]), each elementary LED emitting R_LED radiation, each elementary LED being in contact with the nucleation layer 16 through one of the openings 20; - an insulating layer 24 extending over the lateral sides of a lower portion of each elementary LED and extending over the insulating layer 18 between the elementary LEDs; - a layer 26 transparent to the electromagnetic radiation R_LED emitted by the elementary LEDs, forming an electrode covering each elementary LED and extending further over the insulating layer 24 between the elementary LEDs; - a conductive and reflective layer 28, extending over the layer 26 between the elementary LEDs, the conductive layer 28 being able, as an alternative, to be interposed between the electrode layer 26 and the insulating layer 24 between the elementary LEDs; - a transparent encapsulation layer 34 against electromagnetic radiation R_LED emitted by the elementary LEDs, extending over the layers 26 and 28, in physical contact with layers 26 and 28, completely covering the elementary light-emitting diodes LEDs, and comprising a top face 35, preferably flat; and - an optical filter F_LED resting on face 35 and covering the elementary LED light-emitting diodes, and adapted, in operation, to perform a band-pass type wavelength filtering of the RL radiation emitted by the GLED light-emitting diode, to provide an R radiation which escapes from the optoelectronic device 5.

[0050] The GLED light-emitting diode comprises all the interconnected LEDs. In [Fig. 3], the LEDs of the GLED are connected in parallel. Generally, the LEDs of the GLED can be connected in series and / or in parallel. The RL radiation emitted by the GLED corresponds to the sum of the R_LED radiation emitted by the LEDs of the GLED.

[0051] The optoelectronic device 5 may include additional layers not shown, in particular moisture- and / or air-tight protective layers, an anti-reflective layer, etc. Alternatively, the encapsulation layer 34 may be omitted. In this case, the optical filter F_LED extends over layers 26 and 28, in physical contact with layers 26 and 28, and completely covers the light-emitting diodes LEDs.

[0052] According to one embodiment, the optoelectronic device 5 comprises a density of elementary light-emitting diodes greater than 400 / mm2, preferably greater than 20000 / mm2, even more preferably greater than 40000 / mm2.

[0053] According to another embodiment, the substrate 10 is present only at intermediate stages of the process of making the optoelectronic device 5 but is then removed and is not present on the final product.

[0054] Figure 4 represents an embodiment of elementary LEDs. Each elementary LED comprises a wire 21 in contact with the seed layer 16 through one of the openings 20 and a shell 22 comprising a stack of semiconductor layers covering the side walls and the top of the wire 21. The assembly formed by each wire 21 and the associated shell 22 constitutes an elementary LED.

[0055] The shell 22 may comprise a stack of several layers, including in particular an active layer 23 and a bonding layer 25. The active layer 23 is the layer from which the majority of the radiation supplied by the elementary light-emitting diode LED is emitted. By way of example, the active layer 23 may It may include containment means, such as a single quantum well or multiple quantum wells. The bonding layer 25 may comprise a stack of semiconductor layers of the same material as the wire 21 but with the opposite conductivity type to wire 21. The thickness of the active layer 23 may be between 2 nm and 100 nm.

[0056] Figure 5 is a partial, schematic top view of an arrangement, referred to as a square mesh, of the wires 21 of the elementary LEDs on the substrate 10, the other elements of the optoelectronic device 5 not being shown. In the arrangement illustrated in Figure 5, an elementary LED is located at each intersection of a row and a column, the rows being perpendicular to the columns, with three rows of three elementary LEDs shown for illustrative purposes. In the embodiment illustrated in Figure 5, each wire 21 has a circular cross-section of diameter D in a plane parallel to the face 12. Alternatively, each wire 21 may have a cross-section that is not circular, for example, an oval, circular, or polygonal shape, in particular triangular, rectangular, square, or hexagonal.In this case, the equivalent diameter of the cross-section of wire 21 is considered as defined previously. The pitch along the rows and / or columns can be between 0.1 pm and 50 pm. Alternatively, the elementary LEDs can be arranged in another configuration, for example, in a hexagonal arrangement. In one embodiment, each elementary LED is adapted to emit radiation R_LED whose center wavelength is in the range of 380 nm to 480 nm, or in the range of 500 nm to 570 nm, or in the range of 590 nm to 650 nm.

[0057] According to one embodiment, at least some of the wires 21 of the elementary LEDs composing the GLED have different equivalent diameters D. The overall dispersion of a physical parameter related to the elementary LEDs is defined as the standard deviation of that parameter measured by taking into account all the elementary LEDs of the GLED; the standard deviation is taken with respect to the average of the parameter for all the elementary LEDs of the GLED. According to one embodiment, the overall dispersion of the equivalent diameters of the wires 21 of the elementary LEDs of the GLED is greater than 20 nm, preferably greater than 100 nm, and more preferably greater than 300 nm.The average equivalent diameter, which is the average of the equivalent diameters D of the wires 21, can be between 0.05 µm and 4 µm. According to one embodiment, the overall dispersion of the equivalent diameters of the wires 21 is between 2% and 100% of the diameter. equivalent average of wires, preferably between 3% and 25% of the equivalent average diameter of wires, more preferably between 5% and 25% of the equivalent average diameter of wires.

[0058] The local dispersion of a physical parameter related to elementary light-emitting diodes is defined as the standard deviation of that parameter measured at a point on the face 12, taking into account the one hundred elementary light-emitting diodes closest to that point. The standard deviation is taken relative to the mean of the parameter for these one hundred elementary light-emitting diodes. According to one embodiment, the local dispersion of the equivalent diameters of the wires 21 of the elementary LEDs of the GLED is greater than 20 nm, preferably greater than 100 nm, and more preferably greater than 300 nm, at any location on the GLED.

[0059] The local / global dispersions indicated above are strictly greater than those resulting from the process of forming elementary light-emitting diodes by growth by epitaxy.

[0060] According to one embodiment, the local and / or global dispersion of the equivalent diameters indicated above is obtained by providing apertures 20 with different equivalent diameters. According to one embodiment, the global dispersion of the apertures 20 of the GLED is greater than 20 nm. The average equivalent diameter of the apertures 20 can be between 0.01 pm and 4 pm. According to one embodiment, the local dispersion of the apertures 20 of the GLED is greater than 10 nm at any location on the GLED.

[0061] According to one embodiment, the local and / or global dispersion of the equivalent diameters indicated above is obtained by arranging the wires 21 in an irregular pattern. Indeed, the wire diameter depends in particular on the mesh pitch. According to one embodiment, the global dispersion of the wire pitch 21 of the GLED is greater than 10 nm. According to another embodiment, the local dispersion of the wire pitch of the GLED is greater than 10 nm at any point on the GLED.

[0062] Fig. 6 schematically represents, as a function of wavelength X, an evolution curve Cl of the luminous intensity I of the radiation RL emitted by the light-emitting diode GLED, which corresponds to the sum of the radiations R_LED emitted by the elementary light-emitting diodes LED of the light-emitting diode GLED of Fig. 3, i.e. before filtering by the optical filter F_LED obtained when the local dispersion of the equivalent diameters of the wires 21 of the elementary light-emitting diodes LED of the light-emitting diode GLED is greater than 80 nm.

[0063] The Cl curve has a general "plateau" shape, that is to say, over a first range of wavelengths AX greater than 30 nm, preferably greater than 40 nm, more preferably greater than 50 nm, a light intensity between 80% of the maximum intensity Imax and the maximum intensity Imax of the Cl layer and that it has over a second range AX2 of wavelengths less than the first range AX1 increased by 30 nm, preferably increased by 20 nm, more preferably increased by 15 nm, a light intensity between 50% of the maximum intensity Imax and the maximum intensity Imax of the Cl layer.The evolution curve Cia has a distinctly flatter shape than the curve representing the luminous intensity of the R_LED radiation emitted by a single LED in the GLED array, which has a "bell" shape with a maximum at the central wavelength of the LED. This is due to the fact that, since the wires 21 have different diameters, the central wavelengths of the R_LED radiation emitted by the LEDs in the GLED array are different, the RL radiation emitted by the GLED corresponding to the sum of the R_LED radiation emitted by all the LEDs in the GLED array.

[0064] According to one embodiment, the overall dispersion of the central wavelengths of the radiation emitted by the elementary light-emitting diodes of the GLED is greater than 40 nm. According to another embodiment, the local dispersion of the central wavelengths of the radiation emitted by the elementary light-emitting diodes of the GLED is greater than 40 nm.

[0065] A method for manufacturing the optoelectronic device 5 includes forming three-dimensional elementary light-emitting diodes (LEDs) on a wafer and cutting the wafer to separate the optoelectronic device from the rest of the wafer. The formation of the three-dimensional elementary LEDs on the wafer includes, in particular, epitaxial growth steps. Several copies of the optoelectronic device 5 can be produced simultaneously on the same wafer and then separated.

[0066] Figure 7 schematically represents, in solid lines, the evolution curve Cl shown in Figure 6 of the intensity of the RL radiation emitted by the light-emitting diode GLED of Figure 3, overlaid in short dashed lines, is the response curve F of the optical filter F_LED of the optoelectronic device 5 of Figure 3. The curve F has a peak at a wavelength Xo. In one embodiment, the full width at half maximum (FWHM) of the curve F for the peak at wavelength Xo is less than 50 nm, preferably less than 30 nm. In another embodiment, In realization, the wavelength Xo is between 430 nm and 480 nm.

[0067] In [Fig. 7], a curve Cl' representing the evolution of the luminous intensity I of the radiation emitted by the light-emitting diode of an optoelectronic device having the same structure as the optoelectronic device 5 of [Fig. 3] and which was fabricated on the same wafer is shown in long dashed lines. The curve Cl' has the same shape as the curve Cl but may be shifted in wavelength relative to the curve Cl. This shift results from the dispersion obtained on the diameters of the wires of the elementary light-emitting diodes (LEDs) at the wafer scale, due in particular to the growth stages by epitaxy.

[0068] Figure 8 schematically represents a curve C2 of the luminous intensity I of the radiation R emitted by the optoelectronic device 5 of Figure 3, for which the radiation RL emitted by the light-emitting diode GLED has the intensity curve CL. The curve C2 has a peak at wavelength Xo. In one embodiment, the full width at half maximum (FWHM) of the curve C2 for the peak at wavelength Xo is less than 50 nm, preferably less than 30 nm. The same curve C2 is obtained for the optoelectronic device for which the radiation emitted by the light-emitting diode has the intensity curve Cl'. This therefore means that the radiation R emitted by the optoelectronic device 5 has the same spectrum regardless of the dimensional dispersion due to its manufacturing process.Since the spectrum of the R radiation emitted by the optoelectronic device 5 is obtained in a controlled manner, there is no need to carry out testing and sorting steps to select the optoelectronic device based on its emission spectrum.

[0069] The substrate 10 may be a single-piece structure or a layer covering a support made of another material. The substrate 10 is preferably a semiconductor substrate, for example, a silicon, germanium, silicon carbide, III-V compound such as GaN or GaAs, or a ZnO substrate. Preferably, the substrate 10 is a single-crystal silicon substrate. Preferably, it is a semiconductor substrate compatible with the manufacturing processes used in microelectronics. The substrate 10 may be a multilayer silicon-on-insulator (SOI) structure.

[0070] The cross-section of the openings 20 may correspond to the desired cross-section of the wires 21 or may be different from the cross-section of the wires that will be obtained. The equivalent diameter of the wires 21 may be equal to or greater than the equivalent diameter of the openings 20.

[0071] The germination layer 16 is made of a material that promotes the growth of the fibers. By way of example, the material composing the germination layer 16 may be a nitride, a carbide or a boride of a transition metal from column IV, V or VI of the periodic table of elements or a combination of these compounds. As an example, the nucleation layer 16 can be of aluminium nitride (AIN), boron (B), boron nitride (BN), titanium (Ti), titanium nitride (TiN), tantalum (Ta), tantalum nitride (TaN), hafnium (Hf), hafnium nitride (HfN), niobium (Nb), niobium nitride (NbN), zirconium (Zr), zirconium borate (ZrB2), zirconium nitride (ZrN), silicon carbide (SiC), tantalum nitride and carbide (TaCN), magnesium nitride in the form MgxNy, where x is approximately equal to 3 and y is approximately equal to 2, for example magnesium nitride in the form Mg3N2 or gallium magnesium nitride (MgGaN), tungsten (W), tungsten nitride (WN) or a combination thereof.The germination layer 16 may have a single-layer structure or correspond to a stack of at least two layers, each layer being, for example, made of one of the materials described previously.

[0072] According to another embodiment, the germination layer 16 may not be present. According to another embodiment, the germination layer 16 may be replaced by germination pads, for example formed at the bottom of the openings 20.

[0073] Each insulating layer 18, 24 may be made of a dielectric material, for example, silicon dioxide (SiO2), silicon nitride (SiXNy, where x is approximately equal to 3 and y is approximately equal to 4, for example, Si3N4), silicon oxynitride (in particular, of general formula SiOxNy, for example, Si2ON2), aluminum oxide (Al2O3), hafnium oxide (HfO2), titanium dioxide (TiO2), or diamond. The insulating layer 18, 24 may have a single-layer structure or correspond to a stack of two or more layers. When the insulating layer 18 corresponds to a stack of at least two layers, the top layer of the stack is insulating, for example, made of a dielectric material.

[0074] The wires 21 comprise predominantly, preferably more than 60% by mass, and more preferably more than 80% by mass, at least one semiconductor material. The semiconductor material may be silicon, germanium, silicon carbide, an IILV compound, an ILVI compound, or a combination of at least two of these compounds.

[0075] Examples of Group III elements include gallium (Ga), indium (In), or aluminum (Al). Examples of Group IIILN compounds are GaN, AIN, InN, InGaN, AlGaN, or AlInGaN. Other Group V elements may also be used, for example, phosphorus or arsenic. Generally, the elements in the IILV compound can be combined with different mole fractions. Examples of Group II elements include Group IIA elements, notably beryllium (Be) and magnesium (Mg), and Group IIB elements, Examples include zinc (Zn), cadmium (Cd), and mercury (Hg). Group VI elements include elements from Group VIA, such as oxygen (O) and tellurium (Te). Examples of II-VI compounds are ZnO, ZnMgO, CdZnO, CdZnMgO, CdHgTe, CdTe, and HgTe. Generally, the elements in the II-VI compound can be combined in different mole fractions. The semiconductor material of the wires may contain a dopant, for example, silicon providing N-type doping to a III-N compound, or magnesium providing P-type doping to a III-N compound.

[0076] The conductive layer 28 preferably corresponds to a metallic layer, for example of aluminium, silver, copper, gold or zinc. The thickness of the conductive layer 28 can be between 0.01 pm and 1000 pm.

[0077] The electrode layer 26 may be a layer of a transparent and conductive material such as indium tin oxide (ITO), aluminum- or gallium-doped zinc oxide, or graphene. The electrode layer 26 may be a metallic layer, in particular silver, aluminum, or titanium, sufficiently thin to be transparent to the radiation emitted by elementary light-emitting diodes (LEDs). The thickness of the electrode layer 26 may be between 0.01 µm and 10 µm.

[0078] The encapsulation layer 34 may be made of an inorganic material that is at least partially transparent to the radiation emitted by photoluminescent particles and / or elementary light-emitting diodes (LEDs). By way of example, the inorganic material may be chosen from the group comprising silicon oxides, of the type SiOx where x is a real number ranging from 1 to 2, silicon nitrides (SixNy, where x is approximately equal to 3 and y is approximately equal to 4, for example Si3N4), silicon oxynitrides (in particular of the general formula SiOxNy, for example Si2ON2), titanium dioxide, aluminum oxides, for example Al2O3, and mixtures of these compounds. The encapsulation layer 34 may be made of an organic material that is at least partially transparent. As an example, encapsulation layer 34 is a silicone polymer, an epoxy polymer, an acrylic polymer or a polycarbonate.The encapsulation layer 34 can have a single-layer or multi-layer structure, and include, for example, a stack of organic and / or inorganic layers.

[0079] The filtering of the radiation emitted by the elementary LEDs of the GLED can be achieved by any means. In one embodiment, the filtering is achieved by coating the elementary LEDs of the GLED with a layer of colored material. In another embodiment, the filtering is achieved by coating the elementary LEDs of the GLED with an interference filter. Preferably, the optical filter F_LED It includes a layer of colored resin. The F_LED optical filter can have a thickness between 10 nm and 200 pm.

[0080] Figure 9 is a partial, schematic cross-sectional view of an embodiment of an optoelectronic device 50 with nanowires or microwires. The optoelectronic device 50 comprises all the elements of the optoelectronic device 5 shown in [Fig. 3], three GLED light-emitting diodes being shown as an example in [Fig. 9], and further comprises, from bottom to top in [Fig. 9]: - a dielectric protection layer 30 extending over layers 26 and 28; - photoluminescent blocks 32, 33 covering the elementary LEDs of some of the GLEDs (for example the two GLEDs on the left in [Fig.9]), the encapsulation layer 34 corresponding to encapsulation blocks 34 covering the elementary LEDs of other GLEDs (for example the GLED on the right in [Fig.9]); - an insulating layer 36 covering the upper face of each block 32, 33, 34, or only of some of the blocks 32, 33, 34, the insulating layer 36 may not be present; - a protective layer 37 covering the insulating layers 36, the lateral faces of the blocks 32, 33, 34 and the electrode layer 26 between the blocks 32, 34; - walls 38 between blocks 32, 34, each wall 38 comprising a core 40 surrounded by a reflective coating 42; - the optical filter F_LED covering the blocks 34, and possibly other optical filters 43, 44 covering the photoluminescent blocks 32 and 33, for example two filters 43, 44, the first being a green filter and the second being a red filter; and - a protective layer 46 covering the entire structure, the protective layer 46 may not be present.

[0081] In the present embodiment, the electrode layer 26 is common to the GLEDs. The GLEDs can be controlled separately by specific connections, not shown, provided in the substrate 10. Generally, the anodes and / or cathodes of the LEDs are not common in order to allow the GLEDs to be controlled separately.

[0082] According to one embodiment, the radiation emitted by one of the photoluminescent blocks 33, 34, after passing through the optical filter 43, 44 covering the photoluminescent block when this optical filter is present, corresponds to green light, that is to say, radiation whose wavelength is in the range of 510 nm to 570 nm. According to another embodiment, the radiation emitted by another of the photoluminescent blocks 33, 34, after passing through the optical filter 43, 44 covering the photoluminescent block when this optical filter is present, corresponds to red light, that is to say radiation whose wavelength is in the range of 600 nm to 720 nm.

[0083] According to one embodiment, the diameters of the wires 21 of all the LEDs of the GLEDs of the optoelectronic device 50 are different, as described for the optoelectronic device 5. As shown in [Fig. 9], for the LEDs covered with the photoluminescent blocks 32, 33, the optical filter F_LED may not be present between the LEDs and the photoluminescent blocks 32, 33. The dispersion of the central wavelengths of the radiation emitted by the LEDs covered with the photoluminescent blocks 32, 33 has no appreciable effect on the spectrum of the radiation emitted by the photoluminescent blocks 32, 33.Indeed, the photoluminescent blocks 32, 33 are adapted to absorb the radiation emitted by the elementary LEDs over a sufficiently wide range of wavelengths to contain the central wavelengths of the radiation emitted by the elementary LEDs despite the dispersion of the central wavelengths of the radiation emitted by the elementary LEDs.

[0084] According to one embodiment, the optoelectronic device 50 corresponds to a display pixel in which each GLED emits blue RL radiation. The F_LED filter covering one of the GLEDs is a bandpass filter centered on a wavelength in the blue region, and the photoluminescent blocks 32, 33 covering the other GLEDs allow, for example, the production of green and red colors. Advantageously, for each GLED covered by a photoluminescent block 32, 33, there is no loss of emission efficiency because all the broadband radiation from the GLEDs is converted by the photoluminescent blocks 32, 33.As with obtaining white light, the proportion of blue light is only about 5%, the loss of emission efficiency due to the F_LED filter is reduced compared to the entire display pixel.

[0085] Each insulating layer 30, 36, 37, 46 can have the same composition as that described previously for the insulating layers 18, 24. The coating 42 can have the same composition as that described previously for the conductive layer 28.

[0086] According to one embodiment, each photoluminescent block 32, 33 is located opposite an array of elementary light-emitting diodes (LEDs). Each photoluminescent block 32, 33 comprises suitable phosphors, which, when excited by the light emitted by the associated LEDs, to emit light at a wavelength different from the wavelength of the light emitted by the associated LEDs. In one embodiment, the optoelectronic device 5 comprises at least two types of photoluminescent blocks 32, 33. Each photoluminescent block 32 of the first type is adapted to convert the radiation provided by the LEDs it covers into a first radiation at a first wavelength, and each photoluminescent block 33 of the second type is adapted to convert the radiation provided by the LEDs it covers into a second radiation at a second wavelength. The aspect ratio of the blocks 32, 33, that is, the ratio between the height and the maximum width of the block, can be between 0.01 and 10, preferably between 0.05 and 2.

[0087] According to one embodiment, each photoluminescent block 32, 33 comprises particles of at least one photoluminescent material, for example in a transparent matrix. An example of a photoluminescent material is trivalent cerium ion-activated yttrium aluminum garnet (YAG), also called YAG:Ce or YAG:Ce3+. The average particle size of conventional photoluminescent materials is generally greater than 5 pm.

[0088] According to one embodiment, each photoluminescent block 32, 33 comprises a matrix in which nanometer-sized single-crystal particles of a semiconductor material are dispersed, also referred to as semiconductor nanocrystals or nanoluminophore particles hereafter. The internal quantum efficiency QYint of a photoluminescent material is equal to the ratio of the number of photons emitted to the number of photons absorbed by the photoluminescent substance. The internal quantum efficiency QYint of semiconductor nanocrystals is greater than 5%, preferably greater than 10%, and more preferably greater than 20%.

[0089] According to one embodiment, the average size of the nanocrystals is in the range of 0.5 nm to 1000 nm, preferably from 0.5 nm to 500 nm, and even more preferably from 1 nm to 100 nm, particularly from 2 nm to 30 nm. For dimensions smaller than 50 nm, the photoconversion properties of the semiconductor nanocrystals depend essentially on quantum confinement phenomena. The semiconductor nanocrystals then correspond to quantum dots.

[0090] According to one embodiment, the semiconductor material of the semiconductor nanocrystals is chosen from the group comprising cadmium selenide (CdSe), indium phosphide (InP), cadmium sulfide (CdS), zinc sulfide (ZnS), zinc selenide (ZnSe), cadmium telluride (CdTe), zinc telluride (ZnTe), cadmium oxide (CdO), zinc cadmium oxide (ZnCdO), zinc cadmium sulfide (CdZnS), zinc cadmium selenide (CdZnSe), sulfide silver and indium (AgInS2), PbScX3 type perovskites, where X is a halogen atom, in particular iodine (I), bromine (Br) or chlorine (Cl), and a mixture of at least two of these compounds. According to one embodiment, the semiconductor material of the semiconductor nanocrystals is chosen from the materials cited in the publication by Le Blevenec et al. in Physica Status Solidi (RRL) - Rapid Research Letters Volume 8, No. 4, pages 349-352, April 2014.

[0091] In one embodiment, the dimensions of the semiconductor nanocrystals are chosen according to the desired wavelength of the radiation emitted by the semiconductor nanocrystals. For example, CdSe nanocrystals with an average size of approximately 3.6 nm are suitable for converting blue light into red light, and CdSe nanocrystals with an average size of approximately 1.3 nm are suitable for converting blue light into green light. In another embodiment, the composition of the semiconductor nanocrystals is chosen according to the desired wavelength of the radiation emitted by the semiconductor nanocrystals.

[0092] The matrix is ​​at least partially transparent to the radiation emitted by photoluminescent particles and / or elementary light-emitting diodes (LEDs), preferably more than 80%. The matrix is, for example, made of silica. The matrix is, for example, made of any polymer that is at least partially transparent, in particular silicone, epoxy, poly(methyl methacrylate) (PMMA) acrylic resin, or polyacetic acid (PLA). The matrix may, in particular, be made of a polymer that is at least partially transparent and used with 3D printers. The matrix may be a spin-on glass (SOG), photosensitive or non-photosensitive. In one embodiment, the matrix contains from 2% to 90%, preferably from 10% to 60%, by weight, of nanocrystals, for example, approximately 30% by weight of nanocrystals.

[0093] The thickness of the photoluminescent blocks 32, 33 depends on the concentration of nanocrystals and the type of nanocrystals used. The height of the photoluminescent blocks 32, 33 is preferably greater than the height of the wires 21 and less than or equal to the height of the walls 38. In top view, each photoluminescent block 32, 33 can correspond to a square, a rectangle, an "L"-shaped polygon, etc., the dimensions of which can be equal to those of a square having a side measuring from 1 pm to 100 pm, preferably from 3 pm to 15 pm.

[0094] The walls 38 are at least partially made of a reflective material. The reflective material may be a metallic material, in particular iron, copper, aluminum, tungsten, silver, titanium, hafnium, zirconium, or a combination of at least two of these compounds. Preferably, the walls 38 are made of a material compatible with the manufacturing processes used in microelectronics. Preferably, the walls 38 are made of aluminum or silver.

[0095] The height of the walls 38, measured in a direction perpendicular to the face 12, is in the range of 300 nm to 200 pm, preferably from 3 pm to 15 pm. The thickness of the walls 38, measured in a direction parallel to the face 12, is in the range of 100 nm to 50 pm, preferably from 0.5 pm to 10 pm.

[0096] According to one embodiment, the walls 38 can be formed of a reflective material or covered with a coating that reflects the wavelength of the radiation emitted by the photoluminescent blocks 32, 33 and / or the elementary light-emitting diodes.

[0097] Preferably, the walls 38 surround the photoluminescent blocks 32, 33. The walls 38 then reduce crosstalk between adjacent photoluminescent blocks 32, 33.

[0098] The protective layer 46 is at least partially transparent to the radiation emitted by photoluminescent particles and / or elementary light-emitting diodes (LEDs). The encapsulation layer may be made of an inorganic material that is at least partially transparent to the radiation emitted by photoluminescent particles and / or elementary light-emitting diodes (LEDs). By way of example, the inorganic material may be chosen from the group comprising silicon oxides, of the type SiOx where x is a real number between 1 and 2 or SiOyNz where y and z are real numbers between 0 and 1, titanium dioxide, aluminum oxides, for example Al₂O₃, and mixtures of these compounds. The encapsulation layer may be made of an organic material that is at least partially transparent. By way of example, the encapsulation layer may be a silicone polymer, an epoxy polymer, an acrylic polymer, or a polycarbonate.The encapsulation layer 46 can have a single-layer or multi-layer structure, and include, for example, a stack of organic and / or inorganic layers.

[0099] Fig.1OA, Fig.1OB, Fig.1OC, Fig.1OD, and Fig.1OE are cross-sectional views of structures obtained at successive stages of an embodiment of a manufacturing process for the optoelectronic device 5 of Fig.3.

[0100] Fig. 1OA represents the structure obtained after the formation of the germination layer 16 on a substrate 10, which corresponds, at this stage of the process, to a plate having a diameter, for example, greater than 100 mm.

[0101] Figure [1OB] shows the structure obtained after the insulating layer 18 is deposited onto the germination layer 16 and openings 20 are formed in the insulating layer, for example by anisotropic etching, to expose portions of the germination layer. According to one embodiment, the equivalent diameters of the openings 20 are different to obtain wires 21 with different equivalent diameters in the next step of the process.

[0102] Fig. 1OC represents the structure obtained after the growth of the wires 21. The wire growth process of the wires 21 is from the other layers of the light-emitting diodes. Elemental LED necescents can be a process of the type or a combination of processes of the type of chemical vapor deposition (CVD) or metal-organic chemical vapor deposition (MOCVD), also known as metal-organic vapor phase epitaxy (or MOVPE). However, processes such as molecular-beam epitaxy (MBE), gas-source MBE (GSMBE), metal-organic MBE (MOMBE), plasma-assisted MBE (PAMBE), atomic layer epitaxy (ALE), or hydride vapor phase epitaxy (HVPE) can be used.However, electrochemical processes can be used, for example, chemical bath deposition (CBD), hydrothermal processes, liquid aerosol pyrolysis or electrodeposition.

[0103] Fig. 100D represents, at a reduced scale compared to Figures 10A to 10C, the structure obtained after the formation of the remaining elementary LEDs, the formation of the encapsulation layer 34 and the formation of the optical filter F_LED.

[0104] [Fig. 1OE] represents the structure obtained after cutting the structure shown in [Fig. 1OD] to obtain several copies of the optoelectronic device 5. By way of example, two cutting paths 52 are schematically represented in [Fig. 1OE]. The cutting step may include a sawing step of the structure shown in [Fig. 1OD].

[0105] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to those skilled in the art. In particular, although in the embodiments described above the elementary LEDs are radial, it is clear that the present embodiments can be implemented with axial LEDs in which the active area of ​​the LED is present only at the top of the wire.

[0106] Finally, the practical implementation of the embodiments and variants described is within the reach of a person skilled in the art, based on the functional indications given above.

Claims

Claims

1. Optoelectronic device (5; 50) comprising: - a first light-emitting diode (GLED) comprising three-dimensional semiconductor elements (21), each corresponding to a microwire, a nanowire, or a conical or truncated element of micrometric or nanometric size, and an active zone (23) covering each three-dimensional semiconductor element,the first light-emitting diode being configured to emit radiation (RL) with an emission spectrum comprising a first wavelength range corresponding to the wavelength range for which the light intensity is greater than 80% of the maximum light intensity of the spectrum and a second wavelength range corresponding to the wavelength range for which the light intensity is greater than 50% of the maximum light intensity and for which the first wavelength range is greater than 30 nm and the second wavelength range is less than the first wavelength range increased by 30 nm; and - a bandpass optical filter (F_LED) covering the first light-emitting diode.,

2. An optoelectronic device according to claim 1, wherein the overall dispersion of the equivalent diameters of the three-dimensional semiconductor elements (21) of the first light-emitting diode (GLED) is between 2% and 100% of the average equivalent diameter of the three-dimensional semiconductor elements (21) of the first light-emitting diode (GLED).

3. An optoelectronic device according to claim 2, wherein the overall dispersion of the equivalent diameters of the three-dimensional semiconductor elements (21) of the first light-emitting diode (GLED) is between 3% and 25% of the average equivalent diameter of the three-dimensional semiconductor elements (21) of the first light-emitting diode (GLED).

4. Optoelectronic device according to any one of claims 1 to 3, in which the central wavelengths of the radiation emitted by the active zones (23) of the first light-emitting diode (GLED) are between 400 nm and 480 nm.

5. An optoelectronic device according to any one of claims 1 to 4, wherein each three-dimensional semiconductor element (21) has an equivalent diameter between 0.05 pm and 2 pm.

6. An optoelectronic device according to any one of claims 1 to 5, wherein the optical bandpass filter (F_LED) has a half-height bandwidth of less than 50 nm.

7. Optoelectronic device according to any one of claims 1 to 6, wherein the optical bandpass filter (F_LED) has a transmission maximum at a wavelength between 430 nm and 480 nm.

8. An optoelectronic device according to any one of claims 1 to 7, comprising a second light-emitting diode (GLED) having the same structure as the first light-emitting diode, and a block (32) of a first photoluminescent material covering the second light-emitting diode.

9. Optoelectronic device according to claim 8, wherein the optical bandpass filter (F_LED) does not cover the second light-emitting diode (GLED).

10. An optoelectronic device according to claim 8 or 9, wherein the anode of the first light-emitting diode is not common with the anode of the second light-emitting diode and / or the cathode of the first light-emitting diode is not common with the cathode of the second light-emitting diode.

11. Optoelectronic device according to any one of claims 8 to 10, wherein the optical bandpass filter (F_LED) has a transmission maximum at a wavelength between 430 nm and 480 nm, and wherein the block (32) of the first photoluminescent material is configured to absorb the radiation emitted by the second light-emitting diode and convert it into radiation at a wavelength between 510 nm and 570 nm.

12. An optoelectronic device according to any one of claims 8 to 11, comprising a third light-emitting diode (GLED) having the same structure as the first light-emitting diode, and a block (33) of a second photoluminescent material, different from the first photoluminescent material, covering the third light-emitting diode.

13. Optoelectronic device according to claim 12, wherein the optical bandpass filter (F_LED) does not cover the third light-emitting diode (GLED).

14. An optoelectronic device according to claim 12 or 13, wherein the anode of the first light-emitting diode is not common with the anode of the third light-emitting diode and / or the cathode of the first light-emitting diode is not common with the cathode of the third light-emitting diode.

15. Optoelectronic device according to any one of claims 12 to 14, wherein the optical bandpass filter (F_LED) has a transmission maximum at a wavelength between 430 nm and 480 nm, and wherein the block (33) of the second photoluminescent material is configured to absorb the radiation emitted by the third light-emitting diode and convert it into radiation at a wavelength between 600 nm and 720 nm.

16. An optoelectronic device according to any one of claims 1 to 15, wherein the three-dimensional semiconductor elements (21) of the first light-emitting diode (GLED) are based on a III-V or II-VI compound.

17. Method for manufacturing optoelectronic devices (5; 50) comprising the following steps: - forming on a plate first light-emitting diodes (GLEDs) each comprising three-dimensional semiconductor elements (21), each corresponding to a microwire, a nanowire, or a conical or truncated element of micrometric or nanometric size, and an active zone (23) covering each three-dimensional semiconductor element,each first light-emitting diode being configured to emit radiation (RL) with an emission spectrum comprising a first wavelength range corresponding to the wavelength range for which the light intensity is greater than 80% of the maximum light intensity of the spectrum and a second wavelength range corresponding to the wavelength range for which the light intensity is greater than 50% of the maximum light intensity and for which the first wavelength range is greater than 30 nm and the second wavelength range is less than the first wavelength range increased by 30 nm; - forming a bandpass optical filter (F_LED) covering the first light-emitting diode for each optoelectronic device; and - cutting the plate to separate the first light-emitting diodes.,

18. The method of claim 17, wherein the first light emitting diodes (GLEDs) are formed by epitaxial growth.

19. A method according to claim 17 or 18, comprising a step of forming on the plate a mask (18) comprising openings (20), and a step of growing the three-dimensional semiconductor elements (21) in the openings, wherein the overall dispersion of the equivalent diameters of the openings is between 2% and 100% of the average equivalent diameter of the three-dimensional semiconductor elements (21) of the first light-emitting diode (GLED).

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