Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
  • H01L33/58—Optical field-shaping elements
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
  • H01L33/16—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous
  • H01L33/18—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous within the light emitting region
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
  • H01L27/15—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission
  • H01L27/153—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars
  • H01L27/156—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components having potential barriers, specially adapted for light emission in a repetitive configuration, e.g. LED bars two-dimensional arrays
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
  • H01L33/08—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
  • H01L33/20—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a particular shape, e.g. curved or truncated substrate
  • H01L33/24—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a particular shape, e.g. curved or truncated substrate of the light emitting region, e.g. non-planar junction
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
  • H01L2933/0083—Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures

Definitions

• TITLE Optoelectronic device with three-dimensional light-emitting diodes of the axial type
• the present application relates to an optoelectronic device, in particular a display screen or an image projection device, comprising light-emitting diodes based on semiconductor materials, and their manufacturing methods.
• a light-emitting diode based on semiconductor materials generally comprises an active zone which is the region of the light-emitting diode from which the majority of the electromagnetic radiation supplied by the light-emitting diode is emitted.
• the structure and composition of the active area are configured to obtain electromagnetic radiation having the desired properties. In particular, it is generally desired to obtain electromagnetic radiation with a narrow spectrum, ideally substantially monochromatic.
• Examples of three-dimensional semiconductor elements are microwires or nanowires comprising a semiconductor material mainly comprising at least one element from group III and one element from group V (for example gallium nitride GaN), subsequently called III-V compound, or comprising mainly at least one element from group II and one element from group VI (eg zinc oxide ZnO), hereinafter called compound II-VI.
• a semiconductor material mainly comprising at least one element from group III and one element from group V (for example gallium nitride GaN), subsequently called III-V compound, or comprising mainly at least one element from group II and one element from group VI (eg zinc oxide ZnO), hereinafter called compound II-VI.
• Such devices are, for example, described in French patent applications FR 2 995 729 and FR 2 997 558.
• a single quantum well is produced by interposing, between two layers of a first semiconductor material, for example a III-V compound, in particular GaN, respectively doped with P and N type, a layer of a second semiconductor material, for example an alloy of the III-V compound and of a third element, in particular InGaN, whose forbidden band is different from the first semiconductor material.
• a multiple quantum well structure comprises a stack of semiconductor layers forming an alternation of quantum wells and barrier layers.
• the wavelength of the electromagnetic radiation emitted by the active zone of the optoelectronic device depends in particular on the forbidden band of the second material forming the quantum well.
• the wavelength of the radiation emitted depends in particular on the atomic percentage of the third element, for example indium. In particular, the higher the atomic percentage of indium, the higher the wavelength.
• a disadvantage is that when the atomic percentage of indium exceeds a threshold, it is observed differences in lattice parameters between the GaN and InGaN layers of the quantum well which can lead to the formation of non-radiative defects in the active area, such as dislocations, which leads to a significant decrease in the quantum efficiency of the active area of the device optoelectronics.
• the production of light-emitting diodes in III-V or II-VI compounds emitting in the red can be difficult.
• an object of an embodiment is to overcome at least in part the drawbacks of the optoelectronic devices with light-emitting diodes described above.
• each light-emitting diode comprises a stack of layers of semiconductor materials based on III-V or II-VI compounds.
• the optoelectronic device comprises light-emitting diodes configured to emit light radiation in the red without the use of photoluminescent materials.
• Another object of an embodiment is that the three-dimensional light-emitting diodes of the axial type based on III-V or II-VI compounds, the active zone of which has an emission spectrum having the desired properties, in particular comprising a narrow band around the target transmit frequency.
• Another object of an embodiment is that the emission frequency of light-emitting diodes can be modified after the formation of the active zones of the diodes. electroluminescent without the use of photoluminescent materials.
• One embodiment provides an optoelectronic device comprising a matrix of axial light-emitting diodes, the light-emitting diodes each comprising an active zone configured to emit electromagnetic radiation, the emission spectrum of which comprises a maximum at a first wavelength, the matrix forming a photonic crystal configured to be able to form three resonance peaks amplifying the intensity of said electromagnetic radiation at at least second, third and fourth wavelengths.
• each active zone is configured to emit electromagnetic radiation, the emission spectrum of which has a width at mid-height comprised between 100 nm and 180 nm.
• the photonic crystal is a two-dimensional photonic crystal.
• the light-emitting diodes are arranged in a network with a pitch of between 400 nm and 475 nm and each light-emitting diode is cylindrical with an average diameter of between 270 nm and 300 nm.
• the light-emitting diodes are based on a III-V or II-VI compound.
• the light-emitting diodes are separated by an electrically insulating material having a refractive index between 1.3 and 1.6, preferably between 1.45 and 1.56.
• one of the second, third, and fourth wavelengths is in the range of 430 nm to 480 nm, another of the second, third, and fourth wavelengths being in the range of 510 nm to 570 nm, and yet another of the second, third, and fourth wavelengths being in the range of 600 nm to 720 nm.
• the emission spectrum of the active zone has energy at the second wavelength.
• the device further comprises a first optical filter covering at least a first part of said matrix of light-emitting diodes, the first optical filter being configured to block said amplified radiation over a first range of lengths of wave comprising the first, third, and fourth wavelengths and for passing said amplified radiation over a second range of wavelengths comprising the second wavelength.
• the emission spectrum of the active zone has energy at the third wavelength.
• the device further comprises a second optical filter covering at least a second part of said matrix of light-emitting diodes, the second optical filter being configured to block said amplified radiation over a third range of wavelengths. wave comprising the first, second and fourth wavelengths and for passing said amplified radiation over a fourth range of wavelengths comprising the third wavelength.
• the emission spectrum of the active zone has energy at the fourth wavelength.
• the device further comprises a third optical filter covering at least a third part of said matrix of light-emitting diodes, the third optical filter being configured to block said amplified radiation over a fifth range of wavelengths. wave comprising the first, second, and third wavelengths and for passing said amplified radiation over a sixth range of wavelengths comprising the fourth wavelength.
• the device comprises a support on which the light-emitting diodes rest, each light-emitting diode comprising a stack of a first semiconductor portion resting on the support, of the active zone in contact with the first semiconductor portion and a second semiconductor portion in contact with the active area.
• the second semiconductor portions of the light-emitting diodes are covered with an electrically conductive layer which is at least partly transparent to the radiation emitted by the light-emitting diodes.
• At least one of the resonance peaks is attenuated relative to the other resonance peaks.
• the side walls of the first and second semiconductor portions of at least part of the light-emitting diodes are covered with a sheath.
• a first part of the electrically conductive layer covering a first group of said light-emitting diodes has a first thickness and a second part of the electrically conductive layer covering a second group of said light-emitting diodes has a second thickness, strictly less than the first thickness.
• the light-emitting diodes of a first group of said light-emitting diodes are separated by a first electrically insulating material having a first refractive index and the light-emitting diodes of a second group of said light-emitting diodes are separated by a second electrically insulating material having a second refractive index different from the first refractive index
• One embodiment also provides a method for manufacturing an optoelectronic device comprising a matrix of axial light-emitting diodes, the light-emitting diodes each comprising an active zone configured to emit electromagnetic radiation, the emission spectrum of which comprises a maximum at a first wavelength, the matrix forming a photonic crystal configured to be able to form three resonance peaks amplifying the intensity of said electromagnetic radiation at at least second, third and fourth wavelengths.
• the formation of the light-emitting diodes of the matrix comprises the following steps:
• the light-emitting diodes are distributed at least into first and second groups of light-emitting diodes.
• the method includes forming a first optical filter on the first group and a second optical filter on the second group, the second optical filter being different from the first optical filter.
• the method comprises the attenuation of at least one of the resonance peaks with respect to the other resonance peaks after the formation of the light-emitting diodes.
• Figure 1 is a sectional view, partial and schematic, of an embodiment of an optoelectronic device comprising light-emitting diodes;
• Figure 2 is a perspective view, partial and schematic, of the optoelectronic device shown in Figure 1;
• FIG. 3 schematically represents an example of arrangement of the light-emitting diodes of the optoelectronic device represented in FIG. 1;
• FIG. 4 schematically represents another example of arrangement of the light-emitting diodes of the optoelectronic device represented in FIG. 1;
• FIG. 5 schematically represents curves of evolution of light intensities of the radiation emitted by the optoelectronic device of FIG. 1 illustrating a configuration with three resonances;
• FIG. 6 illustrates a method for selecting a resonance of the radiation emitted in a configuration with three resonances
• FIG. 7 illustrates a method for selecting another resonance of the radiation emitted in a configuration with three resonances
• FIG. 8 illustrates a method of selecting two resonances of the radiation emitted in a configuration with three resonances
• FIG. 9 illustrates a method for selecting a resonance of the radiation emitted in a configuration with three resonances
• FIG. 10 schematically represents curves of evolution of light intensities of the radiation emitted by an optoelectronic device illustrating a configuration with one resonance obtained from an initial configuration with three resonances;
• Figure 11 is a sectional view, partial and schematic, of an embodiment of an optoelectronic device having the emission spectrum of Figure 10;
• FIG. 12 is a partial and schematic sectional view of an embodiment of an optoelectronic device having the emission spectrum of FIG. 10;
• Figure 13 is a sectional view, partial and schematic, of an embodiment of a device optoelectronics having the emission spectrum of Figure 10;
• FIG. 14A illustrates a step of an embodiment of a method of manufacturing the optoelectronic device shown in FIG. 1;
• FIG. 14B illustrates another step in the manufacturing process
• FIG. 14C illustrates another step in the manufacturing process
• FIG. 14D illustrates another step in the manufacturing process
• FIG. 14E illustrates another step in the manufacturing process
• FIG. 14F illustrates another step in the manufacturing process
• FIG. 14G illustrates another step in the manufacturing process
• FIG. 15 illustrates a step of another embodiment of a method of manufacturing the optoelectronic device represented in FIG. 1;
• FIG. 16 is a grayscale map of the light intensity emitted at a first wavelength by a light-emitting diode of a photonic crystal of the optoelectronic device as a function of the pitch of the photonic crystal and the diameter of the light emitting diode ;
• FIG. 17 is a map in grayscale of the light intensity emitted at a second wavelength by a light-emitting diode of a photonic crystal of the optoelectronic device as a function of the pitch of the photonic crystal and the diameter of the light emitting diode ;
• FIG. 18 is a map in grayscale of the light intensity emitted at a third wavelength by a light-emitting diode of a photonic crystal of the optoelectronic device as a function of the pitch of the photonic crystal and the diameter of the light emitting diode ; and
• FIG. 19 represents a curve of evolution of the light intensity of the light-emitting diodes as a function of the wavelength measured during a test.
• the expressions "about”, “approximately”, “substantially”, and “in the order of” means to within 10%, preferably within 5%.
• the terms “insulating” and “conductive” are herein considered to mean “electrically insulating” and “electrically conducting”, respectively.
• the internal transmittance of a layer corresponds to the ratio between the intensity of the radiation leaving 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.
• a layer is said to be transparent to radiation when the absorption of radiation through the layer is less than 60%.
• a layer is said to be radiation-absorbent when the absorption of radiation in the layer is greater than 60%.
• a radiation presents a spectrum of general "bell" shape, for example of Gaussian shape, having a maximum, one calls wavelength of the radiation, or central or main wavelength of the radiation, the wavelength at which the maximum of the spectrum is reached.
• the refractive index of a material corresponds to the refractive index of the material for the range of wavelengths of the radiation emitted by the optoelectronic device.
• the refractive index is considered to be substantially constant over the range of wavelengths of the useful radiation, for example equal to the average of the index of refraction over the range of wavelengths of the radiation emitted by the optoelectronic device
• diode axial electroluminescent denotes a three-dimensional structure of elongated shape, for example cylindrical, in a preferred direction, of which at least two dimensions, called minor dimensions, are between 5 nm and 2.5 ⁇ m, preferably between 50 nm and 2, 5 p.m.
• the third dimension, called 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.
• the minor dimensions can be less than or equal to approximately 1 ⁇ m, preferably between 100 nm and 1 ⁇ m, more preferably between 100 nm and 800 nm.
• the height of each light-emitting diode can be greater than or equal to 500 nm, preferably between 1 ⁇ m and 50 ⁇ m.
• the average diameter of a wire is called the diameter of the wire with a circular base, the surface of which is the same as the surface of the base of the wire in question.
• Figures 1 and 2 are respectively a side sectional view and a perspective view, partial and schematic, of an embodiment of an optoelectronic device 10 with light-emitting diodes.
• the optoelectronic device 10 comprises, from bottom to top in FIG. 1:
• each axial light-emitting diode comprising, from bottom to top in FIG. 1, a lower semiconductor portion 18, not shown in FIG. 2, in contact with electrode layer 14 , an active area 20, not shown in Figure 2, in contact with the semiconductor portion 18, and an upper semiconductor portion 22, not shown in Figure 2, in contact with the active area 20;
• Each light-emitting diode LED is said to be axial insofar as the active area 20 is in the extension of the lower portion 18 and the upper portion 22 is in the extension of the active area 20, the assembly comprising the lower portion 18 , the active zone 20, and the upper portion 22 extending along an axis A, called the axis of the axial light-emitting diode.
• the axes A of the light-emitting diodes LED are parallel and orthogonal to the face 16.
• the support 12 can correspond to an electronic circuit.
• the electrode layer 14 can be metallic, for example silver, copper or zinc.
• the thickness of electrode layer 14 is sufficient for electrode layer 14 to form a mirror.
• the electrode layer 14 has a thickness greater than 100 nm.
• Electrode layer 14 may completely cover support 12. Alternatively, electrode layer 14 may be divided into separate portions so as to permit separate control. of light-emitting diode groups of the light-emitting diode matrix.
• face 16 may be reflective.
• the electrode layer 14 can then present a specular reflection.
• the electrode layer 14 can present a Lambertian reflection. To obtain a surface having a Lambertian reflection, one possibility is to create irregularities on a conductive surface.
• a texturing of the surface of the base can be carried out before the deposition of the metallic layer so that the face 16 of the layer metal, once deposited, has reliefs.
• the second electrode layer 26 is conductive and transparent.
• the electrode layer 26 is a layer of transparent and conductive oxide (TCO), such as indium tin oxide (or ITO, acronym for Indium Tin Oxide), zinc oxide doped or not with aluminum or gallium, or graphene.
• TCO transparent and conductive oxide
• ITO Indium Tin Oxide
• the electrode layer 26 has a thickness comprised between 5 nm and 200 nm, preferably between 20 nm and 50 nm.
• the insulating layer 24 can be made of an inorganic material, for example silicon oxide or silicon nitride.
• the insulating layer 24 can be made of an organic material, for example an insulating polymer based on benzocyclobutene (BCB).
• Coating 28 may comprise an optical filter, or optical filters arranged next to each other, as will be described in more detail below.
• the refractive index of the material of the insulating layer 24 is between 1.3 and 1.6, preferably between 1.45 and 1.56.
• all LED light-emitting diodes have the same height.
• the thickness of the insulating layer 24 is for example chosen equal to the height of the light-emitting diodes LED in such a way that the upper face of the insulating layer 24 is coplanar with the upper faces of the light-emitting diodes.
• the semiconductor portions 18 and 22 and the active areas 20 are, at least in part, made of a semiconductor material.
• the semiconductor material is chosen from the group comprising III-V compounds, II-VI compounds, and group IV semiconductors or compounds.
• group III elements include gallium (Ga), indium (In), or aluminum (Al).
• group IV elements include nitrogen (N), phosphorus (P), or arsenic (As).
• III-N compounds are GaN, AlN, InN, InGaN, AlGaN or AlInGaN.
• group II elements include group IIA elements including beryllium (Be) and magnesium (Mg) and group IIB elements including zinc (Zn), cadmium (Cd) and mercury ( Hg).
• group VI elements include group VIA elements, including oxygen (O) and tellurium (Te).
• compounds II-VI are ZnO, ZnMgO, CdZnO, CdZnMgO, CdHgTe, CdTe or HgTe.
• the elements in the compound III-V or II-VI can be combined with different mole fractions.
• Group IV semiconductor materials are silicon (Si), carbon (G), germanium (Ge), silicon carbide alloys (SiC), silicon-germanium alloys (SiGe) or carbide alloys of germanium (GeC)
• Semiconductor portions 18 and 22 may comprise a dopant.
• the dopant can be chosen from the group comprising a group II P-type dopant, for example, magnesium (Mg), zinc (Zn), cadmium (Cd ) or mercury (Hg), a Group IV P-type dopant, e.g. carbon (G) or an N-type dopant of group IV, for example silicon (Si), germanium (Ge), selenium (Se), sulfur (S), terbium (Tb) or tin (Sn).
• the semiconductor portion 18 is made of P-doped GaN and the semiconductor portion 22 is made of N-doped GaN.
• the active area 20 may include containment means.
• the active zone 20 can comprise a single quantum well. It then comprises a semiconductor material different from the semiconductor material forming the semiconductor portions 18 and 22 and having a band gap lower than that of the material forming the semiconductor portions 18 and 22.
• the active zone 20 can comprise multiple quantum wells. It then comprises a stack of semiconductor layers forming an alternation of quantum wells and barrier layers.
• each light-emitting diode LED has the shape of a cylinder with a circular base with an axis A.
• each light-emitting diode LED can have the shape of a cylinder with an axis A with a polygonal base. , for example square, rectangular or hexagonal.
• each light-emitting diode LED has the shape of a cylinder with a hexagonal base.
• the height H of the light-emitting diode LED is called the sum of the height h1 of the lower portion 18, of the height h2 of the active zone 20, of the height h3 of the upper portion 22, of the thickness of the electrode layer 26, and coating thickness 28.
• the light-emitting diodes LED are arranged to form a photonic crystal. Twelve light-emitting diodes LED are represented by way of example in figure 2. In practice, the matrix 15 can comprise between 7 and 100,000 light-emitting diodes LED.
• the light-emitting diodes LED of the matrix 15 are arranged in rows and columns (3 rows and 4 columns being represented by way of example in FIG. 2).
• the step 'a' of the matrix 15 is the distance between the axis of a light-emitting diode LED and the axis of a close light-emitting diode LED, of the same line or of an adjacent line.
• the pitch a is substantially constant. More specifically, the pitch a of the matrix is chosen such that the matrix 15 forms a photonic crystal.
• the photonic crystal formed is for example a 2D photonic crystal.
• the properties of the photonic crystal formed by the matrix 15 are advantageously chosen so that the matrix 15 of the light-emitting diodes forms a resonant cavity in the plane perpendicular to the axis A and a resonant cavity along the axis A in particular to obtain a coupling and increase the selection effect.
• This allows the intensity of the radiation emitted by the set of light-emitting diodes LED of the matrix 15 by the emission face 30 to be amplified for certain wavelengths compared to a set of light-emitting diodes LED which would not form a photonic crystal.
• FIGS. 3 and 4 schematically represent examples of arrangements of the light-emitting diodes LED of the matrix 15.
• FIG. 3 illustrates a so-called square mesh arrangement
• FIG. 4 illustrates a so-called hexagonal mesh arrangement.
• FIGS. 3 and 4 each represent three rows of four light-emitting diodes LED.
• a light-emitting diode LED is located at each intersection of a row and a column, the rows being perpendicular to the columns.
• the diodes on a line are offset by half the pitch a with respect to the light-emitting diodes on the preceding line and the following line.
• each light emitting diode LED has a circular cross section of diameter D in a plane parallel to the face 16.
• the diameter D can be between 0.05 ⁇ m and 2 ⁇ m.
• the pitch a can be between 0.1 ⁇ m and 4 ⁇ m.
• the height H of the light-emitting diode LED is chosen so that each light-emitting diode LED forms a resonant cavity along the axis A at the desired central wavelength ⁇ of the radiation emitted by the optoelectronic device 10.
• the height H is chosen substantially proportional to k* ( ⁇ /2) *neff , neff being the effective refractive index of the light-emitting diode in the optical mode considered and k being a positive integer.
• the effective refractive index is for example defined in the work “Semiconductor Optoelectronic Devices: Introduction to Physics and Simulation” by Joachim Piprek.
• the height H can nevertheless be the same for all the light-emitting diodes. It can then be determined from the theoretical heights which would make it possible to obtain resonant cavities for the light-emitting diodes of each group, and is for example equal to the average of these theoretical heights.
• the properties of the photonic crystal, formed by the matrix 15 of light-emitting diodes LED are selected to increase the light intensity emitted by the matrix 15 of light-emitting diodes LED at at least three wavelengths. targets.
• the active zone 20 of each light-emitting diode LED has a relatively spread emission spectrum, in particular having a maximum at a first wavelength and a width at mid-height greater than 100 nm, preferably greater than 180 nm, so as to cover the three target wavelengths, that is to say that the energy of the emission spectrum of the active zone 20 at the target wavelengths is not zero.
• the maximum of the spectrum of the radiation emitted by the active zone 20 is at a wavelength different from at least two of the target wavelengths.
• FIG. 5 schematically represents, as a function of the wavelength ⁇ , an evolution curve C1 (solid line) of the light intensity I emitted by the active zones 20 of the light-emitting diodes LED considered separately, an evolution curve C2 (in dashed lines in FIG. 5 and in solid lines in FIGS. 6 to 10) of the amplification factor due to the coupling with the photonic crystal and an evolution curve C3 (in dotted lines) the light intensity emitted by the matrix 15 of light-emitting diodes.
• Curve C1 has a general "bell" shape and has a peak at a central wavelength ⁇ c .
• Curve C2 comprises three narrow resonance peaks, a first resonance peak P 1 centered on the target wavelength ⁇ T1 , a second resonance peak P 2 centered on the target wavelength ⁇ T2 , and a third peak resonance P3 centered on the target wavelength ⁇ T3 .
• the curve C3 comprises an intensity peak P' 1 at the target wavelength ⁇ T1 , an intensity peak P' 2 at the target wavelength ⁇ T2 , an intensity peak P'3 at the target wavelength ⁇ T3 , and substantially follows curve C1 for the other wavelengths.
• the bandwidth of curve C1 at mid-height for vertex S is greater than the bandwidth of curve C3 at mid-height for each peak P'i, P'2 and P'3, by example of a factor of 2, in particular a factor of 10.
• the target wavelength ⁇ T1 corresponds to blue light, that is to say radiation whose wavelength is in the range from 430 nm to 480 nm.
• the target wavelength ⁇ T2 corresponds to green light, that is to say radiation whose wavelength is in the range from 510 nm to 570 nm.
• the target wavelength ⁇ T3 corresponds to red light, that is to say radiation whose wavelength is in the range from 600 nm to 720 nm.
• an optoelectronic device 10 emitting narrow-spectrum light radiation at one of the target wavelengths ⁇ T1 , ⁇ T2 , or ⁇ T3 can be obtained by filtering the radiation emitted by the matrix 15 of light-emitting diodes LED to keep only the intensity peak at the desired target wavelength. This can be achieved by providing an optical filter in the coating 28.
• Figures 6 and 7 illustrate the principle of filtering the radiation emitted by the matrix 15 of light-emitting diodes.
• An optoelectronic device emitting narrow-spectrum light radiation centered on a target wavelength can be obtained by blocking the part undesired emission spectrum of the matrix 15 of light-emitting diodes.
• the blocked part of the spectrum of the radiation emitted by the matrix 15 of light-emitting diodes is hatched and only one of the resonance peaks is retained, the resonance peak P 1 at the target wavelength ⁇ T1 in figure 6 and the resonance peak P 3 at the target wavelength ⁇ T3 in figure 7.
• the height h1 of the lower portion 18 and the height h2 of the upper portion 22 can advantageously be determined so that the light intensity of the peak at the target wavelength is maximum.
• the filtering of the radiation emitted by the matrix of light-emitting diodes can be achieved by any means.
• the filtering is obtained by covering the light-emitting diodes with a layer of a colored material.
• the filtering is obtained by covering the light-emitting diodes with an interference filter.
• the light-emitting diodes of the matrix of light-emitting diodes can be divided into first and second groups of light-emitting diodes.
• a first filtering is implemented for the light-emitting diodes of the first group to retain only a first resonance peak and a second filtering is implemented for the light-emitting diodes of the second group to retain only a second resonance peak.
• An optoelectronic device configured for the emission of a first radiation at a first target wavelength and of a second radiation at a second target wavelength can thus be obtained while the active areas of the light-emitting diodes and the matrices light-emitting diodes of the first and second groups have the same structure.
• the light-emitting diodes can be divided into first, second and third groups of light-emitting diodes.
• a first filtering is implemented for the light-emitting diodes of the first group to retain only a first resonance peak.
• a second filtering is implemented for the light-emitting diodes of the second group to retain only a second resonance peak.
• a third filtering is implemented for the light-emitting diodes of the third group to retain only a third resonance peak.
• An optoelectronic device configured to emit first radiation at a first target wavelength, second radiation at a second target wavelength, and third radiation at a third target wavelength can thus be obtained while the active areas of the light-emitting diodes and the matrices of the light-emitting diodes of the first, second and third groups have the same structure. This notably allows the production of display sub-pixels for a display pixel of a screen for displaying a color image.
• the radiation after filtering of the first group of light-emitting diodes corresponds to blue light, that is to say radiation whose wavelength is in the range from 430 nm to 480 nm. n.
• the radiation after filtering of the second group of light-emitting diodes corresponds to green light, that is to say radiation whose wavelength is in the range from 510 nm to 570 nm.
• the radiation after filtering of the third group of light-emitting diodes corresponds to red light, i.e. radiation whose wavelength is in the range of 600 nm to 720 nm.
• active zones 20 having the same structure and the same composition can be used to manufacture optoelectronic devices capable of emitting radiation with narrow spectra at different target wavelengths.
• design of a new optoelectronic device can be made with the same structure, so that the initial steps of the manufacturing process at least until the manufacturing of the light-emitting diodes can be common for the manufacturing of different optoelectronic devices.
• the active zone 20 may also be advantageous for the active zone 20 to emit radiation of maximum intensity at a central wavelength ⁇ c different from the target wavelengths ⁇ T1 , ⁇ T2 , or ⁇ T3 , or at least of two of them.
• the central wavelength of the radiation emitted increases with the proportion of indium.
• the central wavelength of the radiation emitted increases with the proportion of indium.
• the central wavelength of the radiation emitted increases with the proportion of indium.
• an emission wavelength corresponding to red it would be necessary to obtain a proportion of indium greater than 16%, which results in a drop in the quantum efficiency of the active zone.
• the fact of using an active area 20 emitting radiation of maximum intensity at a central wavelength ⁇ c less than the target wavelength ⁇ T1 then makes it possible to use an active area 20 with improved quantum efficiency.
• This also makes it possible to obtain radiation at the target wavelength ⁇ T1 using a active zone 20 emitting radiation of maximum intensity at the central wavelength ⁇ c , which is easier to manufacture without
• an active area 20 emitting radiation whose spectrum is more spread than the desired spectrum for the radiation emitted by the optoelectronic device. This can make the design and manufacture of the active area 20 simpler.
• the selection of the target wavelength of the radiation emitted by the optoelectronic device can be obtained by using an active zone whose emission spectrum, although spread, does not cover the three target wavelengths ⁇ T1 , ⁇ T2 , and ⁇ T3 . Only an intensity peak or intensity peaks are then obtained in the radiation emitted by the matrix 15 of light-emitting diodes for the target wavelengths ⁇ T1 , ⁇ T2 , or ⁇ T3 which are in the band of the radiation emitted by active areas 20.
• FIG. 8 is a figure similar to FIG. 5, except that the evolution curve C1 of the spectrum emitted by the active zones 20 covers only two narrow resonance peaks of the curve C2 centered respectively on the lengths d target wave ⁇ T2 and ⁇ T3 .
• the corresponding curve C3 (not shown) then includes the peak S at the central wavelength ⁇ c , an intensity peak at the target wavelength ⁇ T2 , and an intensity peak at the wavelength target ⁇ T3 .
• FIG. 9 is a figure similar to FIG. 5, except that the evolution curve C1 of the spectrum emitted by the active zones 20 only covers a single narrow resonance peak of the curve C2 centered on the length of target wave ⁇ T3 .
• the corresponding C3 curve (not shown) then comprises the peak S at the central wavelength ⁇ c , and an intensity peak at the target wavelength ⁇ T3 .
• the epitaxial growth conditions of the active areas 20 can be chosen so that the spectrum emitted by the active areas 20 only alternately covers the wavelength ⁇ T1 , ⁇ T2 or ⁇ T3 without modifying the photonic crystal .
• This can be achieved for example by modifying only the indium concentration in the active area 20 when the active areas 20 comprise InGaN quantum wells. This advantageously allows the industrial manufacture of devices emitting at three different target wavelengths with essentially identical basic manufacturing parameters except for the growth of the active areas 20.
• the selection of the target wavelength of the radiation emitted by the optoelectronic device can be obtained by modifying the properties of the photonic crystal with respect to the reference structure previously described in relation to the figures 1 and 2 and which results in the presence of the three resonance peaks, so as to reduce the amplitude of one of the resonance peaks, preferably to cancel one of the resonance peaks, or even to reduce the amplitude by two resonance peaks, preferably to cancel two of the resonance peaks.
• the spectrum of the radiation emitted by the matrix 15 of light-emitting diodes comprises a smaller number of intensity peaks compared with what is obtained with the reference structure.
• the modification of the properties of the photonic crystal with respect to the reference structure is carried out after the formation of the matrix 15 of light-emitting diodes.
• One possibility is to introduce an element, in particular a nanomaterial, around the wires to promote resonance.
• Another possibility consists in modifying the material making up the insulating layer 24 and/or the coating 28.
• Another possibility consists in modifying the total height H of the structure, for example by modifying the thickness of the electrode layer 26. This fact, all the light-emitting diodes can be made with the same structure, so that the initial steps of the manufacturing process at least until the manufacturing of the light-emitting diodes can be common for the manufacturing of different optoelectronic devices.
• FIG. 10 is a figure similar to FIG. 8 except that the resonance peak P 2 of the evolution curve C2 of the amplification factor due to the photonic crystal at the target wavelength ⁇ T2 a substantially disappeared and the amplitude of the resonance peak P 3 of the evolution curve C2 at the target wavelength ⁇ T3 is reduced.
• the radiation emitted by the matrix 15 of light-emitting diodes comprises only an intensity peak without the use of an optical filter being necessary.
• Figures 11, 12, and 13 are sectional views, partial and schematic, of embodiments of optoelectronic devices for obtaining the curves C1 and C2 shown in Figure 10.
• the coating 28, possibly present, n is not represented in FIGS. 11, 12, and 13.
• the reference structure of the optoelectronic device 10 represented in FIG. 1 is kept in a first zone ZI to obtain radiation in the first zone ZI with three intensity peaks and the reference structure of the optoelectronic device 10 represented in FIG. 1 is modified in a second zone Z2 to obtain radiation in the second zone Z2 with fewer intensity peaks.
• the height H of the diodes light-emitting LED is changed in the second zone Z2.
• the diameter of the light-emitting diodes LED is modified in the second zone Z2.
• the refractive indices of the materials making up the photonic sensor are modified in the second zone Z2.
• FIG. 11 represents an optoelectronic device 32 comprising all the elements of the optoelectronic device 10 represented in FIG. 1, except that the electrode layer 26 does not have a constant thickness.
• the thickness of the electrode layer 26 in the first zone ZI of the optoelectronic device 32 is thicker than the thickness of the electrode layer 26 in the second zone Z2 of the optoelectronic device 32.
• the thickness of the electrode layer 26 in the first zone ZI is that determined for the reference structure which leads to the presence of three intensity peaks in the radiation supplied by the matrix 15 of light-emitting diodes LED in the first zone Zl.
• the reduced thickness of the electrode layer 26 in the second zone Z2 leads to a modification of the properties of the photonic crystal, so that the curves C1 and C2 represented in FIG. 10 are obtained for the matrix 15 of light-emitting diodes LED in the second Z2 area.
• FIG. 12 represents an optoelectronic device 34 comprising all the elements of the optoelectronic device 10 represented in FIG. 1, except that a sheath 35 surrounds the side walls of each light-emitting diode LED in the second zone Z2.
• each sheath 35 is made of a material whose refractive index is close to the refractive index of the material making up the semiconductor portions 18 and 22. Everything then happens as if the diameter of the light-emitting diodes is increased in the second zone Z2 relative to the diameter of the light emitting diodes in the first zone Zl. The increased diameter in the second zone Z2 leads to a modification of the properties of the photonic crystal, so that the curves C1 and C2 represented in FIG. 10 are obtained for the matrix 15 of light-emitting diodes LED in the second zone Z2.
• FIG. 13 represents an optoelectronic device 36 comprising all the elements of the optoelectronic device 10 represented in FIG. 1, except that the insulating layer 24 is, in the second zone Z2, made of a material with a different refractive index. with respect to the first zone Z1, which is illustrated by a limit 38 between the two zones Z1 and Z2.
• the modification of the refractive index of the insulating layer 24 in the second zone Z2 leads to a modification of the properties of the photonic crystal, so that the curves C1 and C2 represented in FIG. 10 are obtained for the matrix 15 of light-emitting diodes LED in the second area Z2.
• FIGS. 14A to 14G are sectional, partial and schematic views of the structures obtained at successive stages of an embodiment of a manufacturing method for the optoelectronic device 10 shown in FIG. 1.
• FIG. 14A illustrates the structure obtained after the forming steps described below.
• a seed layer 40 is formed on a substrate 42. Light-emitting diodes LED are then formed from the seed layer 40. More specifically, the light-emitting diodes LED are formed in such a way that the upper portions 22 are in contact with the seed layer 40.
• the seed layer 40 is made of a material which promotes the growth of the upper portions 22. For each diode electroluminescent LED, the active area 20 is formed on the upper portion 22 and the lower portion 18 is formed on the active area 20.
• the light-emitting diodes LED are located so as to form the matrix 15, that is to say to form rows and columns with the desired pitch of the matrix 15. Only one row is partially represented on Figures 14A to 14G.
• a mask can be formed before the formation of the light-emitting diodes on the seed layer 40 so as to uncover only the parts of the seed layer 40 at the locations where the light-emitting diodes will be located.
• the seed layer 40 can be etched, before the formation of the light-emitting diodes, so as to form pads located at the locations where the light-emitting diodes will be formed.
• the process for growing light-emitting diodes LEDs can be a process of the type or a combination of processes of the chemical vapor phase deposition (CVD, English acronym for Chemical Vapor Deposition) or organometallic chemical vapor deposition (MOCVD, acronym for Metal-Organic Chemical Vapor Deposition), also known as metal-organic vapor phase epitaxy (or MOVPE, acronym for Metal-Organic Vapor Phase Epitaxy).
• MOVPE metal-organic vapor phase epitaxy
• processes such as Molecular Beam Epitaxy (MBE), gas-source MBE (GSMBE), organometallic MBE (MOMBE), plasma-assisted MBE (PAMBE), Atomic Layer Epitaxy (ALE) or Hydride Vapor Phase Epitaxy (HVPE) can be used.
• electrochemical processes can be used, for example, chemical bath deposition (CBD, acronym for Chemical Bath Deposition), hydrothermal processes, liquid aerosol pyrolysis or electrodeposition.
• CBD chemical bath
• the growth conditions of the light-emitting diodes LED are such that all the light-emitting diodes of the matrix 15 are formed sensibly at the same speed.
• the heights of the semiconductor portions 22 and 18 and the height of the active zone 20 are substantially identical for all the light-emitting diodes of the matrix 15 .
• the height of the semiconductor portion 22 is greater than the desired value h3. Indeed, it can be difficult to precisely control the height of the upper portion 22 in particular because of the start of growth of the upper portion 22 from the germination layer 40 . Additionally, forming the semiconductor material directly on seed layer 40 can cause crystal defects in the semiconductor material just above seed layer 40 . One may therefore want to remove part of the upper portion 22 to obtain a constant height before forming the active zone 20 .
• FIG. 14B illustrates the structure obtained after the formation of the layer 24 of filling material, for example an electrically insulating material, for example silicon oxide.
• Layer 24 is for example formed by depositing a layer of filling material on the structure represented in FIG. 14A, the layer having a thickness greater than the height of the light-emitting diodes LED. The layer of filling material is then partially removed so as to be planarized to uncover the upper faces of the semiconductor portions 18. The upper face of the layer 24 is then substantially coplanar with the upper face of each semiconductor portion 18.
• the method may comprise an etching step during which the semiconductor portions 18 are partially etched.
• the filling material is chosen in such a way that the photonic crystal formed by the matrix 15 has the desired properties, that is to say that it selectively improves in wavelength the intensity of the radiation emitted by the matrix of light-emitting diodes LED.
• FIG. 14C illustrates the structure obtained after deposition of electrode layer 14 on the structure obtained in the previous step.
• Figure 14D illustrates the structure obtained after the fixing to the support 12 of the layer 14, for example by metal-metal bonding, by thermocompression or by brazing with the use of a eutectic on the side of the support 12.
• FIG. 14E illustrates the structure obtained after the removal of the substrate 42 and of the seed layer 40.
• the layer 24 and the upper portions 22 are etched in such a way that the height of each upper portion 22 has the desired h3 value. This step makes it possible, advantageously, to control exactly the height h of the light-emitting diodes and to remove the parts of the upper portions 22 which may have crystalline defects.
• FIG. 14F illustrates the structure obtained after deposition of electrode layer 26.
• FIG. 14G illustrates the structure obtained after the formation of at least one optical filter on all or part of the structure represented in FIG. 14E.
• first, second, and third optical filters F R , F G , F B placed respectively on first, second, and third groups of light-emitting diodes LED.
• FIG. 15 illustrates a variant of the method of manufacturing the optoelectronic device represented in FIG. 1, in which a step of partial etching of the free end of each upper portion 22 of the light-emitting diodes LED is implemented before the formation of the electrode layer 26.
• the partial etching step may include the formation of inclined flanks 44 at the free end of the upper portions 22. This makes it possible to slightly modify the properties of the photonic crystal. This therefore makes it possible to finely modify the position of the resonance peaks of the amplification due to the photonic crystal
• the lower semiconductor portion 18 was made of p-type doped GaN.
• the upper semiconductor portion 22 was made of n-type doped GaN.
• upper 18 and 22 was about 2.4.
• the active area 20 corresponded to a layer of InGaN.
• the height h2 of the active zone 20 was equal to 40 nm.
• Electrode layer 14 was aluminum.
• the insulating layer 24 was made of BGB-based polymer. The refractive index of insulating layer 24 was between 1.45 and 1.56. For the simulations, a specular reflection on face 16 was considered.
• FIGS 16, 17, and 18 are maps in gray levels of the luminous intensity of the radiation emitted in a direction inclined by 5 degrees with respect to a direction orthogonal to the emission face 30 respectively at a first , second, and third wavelength of the array 15 of light-emitting diodes LED as a function of the pitch 'a' of the photonic crystal and the diameter 'D' of each light-emitting diode.
• the first wavelength was 450 nm (blue color)
• the second wavelength was 530 nm (green color)
• the third wavelength was 630 nm (red color)
• Each of the gray level maps comprises lighter areas which correspond to resonance peaks. Such areas with resonance peaks are indicated, schematically, by contours B in solid lines in FIG. 16, by contours G in dotted lines in FIG. 17 and by contours R in dashed lines in FIG. 18.
• the contours B of figure 16 have been superimposed on the contours G. This therefore means, by way of example, that by selecting the pitch 'a' of the photonic crystal and the diameter 'D' of the light-emitting diodes to be located in one of the regions delimited both by the contours B and G in FIG. 17, the emission spectrum of the matrix 15 of light-emitting diodes LED, obtained without filtering, exhibits at least one resonance peak to the wavelength of 450 nm and a resonance peak at the wavelength of 530 nm.
• the contours B of figure 16 and the contours G of figure 17 have been superimposed on the contours R.
• the emission spectrum of the matrix 15 of light-emitting diodes LED obtained without filtering, has at least one resonance peak at the wavelength of 450 nm, a resonance peak at the wavelength of 530 nm, and a resonance peak at the wavelength of 630 nm.
• the three peaks are obtained with a height H equal to approximately 1 pm, a pitch 'a' of the photonic crystal equal to 400 nm, and the diameter of the circle circumscribed at the hexagonal base of the light-emitting diodes varying between 260 nm and 270 nm +/ - 25 nm, which corresponds to a corrected diameter varying between 280 nm and 290 nm.
• the light-emitting diodes had a hexagonal base. Approximately, it was considered that the simulations carried out for light-emitting diodes with a circular base with a given radius are equivalent to simulations for which the light-emitting diodes would be with a hexagonal base, with a circle circumscribing the hexagonal cross-section having a radius equal to 1.1 times the given radius.
• the semiconductor portions 18 and 22 and the active areas 20 of all the photodiodes were produced simultaneously by MOCVD.
• FIG. 19 represents a curve of evolution CRGB of the light intensity I, in arbitrary units, of the matrix 15 of light-emitting diodes as a function of the wavelength for the test. Three resonance peaks are well obtained respectively at wavelengths of 450 nm, 590 nm, and 700 nm.
• the coating 28 described previously can comprise additional layers other than an optical filter or optical filters.
• the coating 28 can include an anti-reflection layer, a protective layer, etc.

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