Optoelectronic device and method for manufacturing an optoelectronic device

Abstract

The present invention relates to an optoelectronic three-dimensional structure comprising a pyramid 21 made of a first InGaN-based material formed from a substrate 2, 2a, 2b, characterized in that the three-dimensional structure 1 includes wires 24 made of a second GaN-based material, different from the first material, extending in a longitudinal direction perpendicular to the plane of the substrate 2, 2a, 2b between the substrate 2, 2a, 2b and the base 210 of the InGaN-based pyramid 21, so that the three-dimensional structure has the general shape of a pencil. The present invention also relates to a method for manufacturing such a three-dimensional structure, and to an optoelectronic device using a plurality of such three-dimensional structures.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronics. In particular, it can find advantageous applications in the field of gallium nitride (GaN)-based light-emitting diodes having a three-dimensional structure.

Background Art

[0002] A light-emitting diode (LED) generally includes a region called an active region where radiative recombination of electron-hole pairs occurs, whereby light radiation having a main wavelength can be obtained.

[0003] In display applications, LEDs can be configured to generate light radiation having a main wavelength of blue, green, or red.

[0004] This main wavelength depends particularly on the composition of the active region. To generate green or red light radiation, the active region can usually be based on InGaN. The higher the concentration of indium [In], the longer the main wavelength. Therefore, in order to obtain an LED that emits red light, it may be necessary to incorporate a concentration of indium [In] ≧ 10 at%.

[0005] GaN-based LEDs are generally manufactured by a technique called planar technology, in which 2D layers are stacked in a direction perpendicular to the base surface on the base surface of a substrate.

[0006] This stack typically may consist of a GaN buffer region, an N-doped GaN region, an InGaN-based active region, and a P-doped GaN region, starting from the substrate.

[0007] By subsequently structuring this stack by means of a lithography / etching process or the like, a plurality of LEDs or micro-LEDs can be formed, each of which usually has a mesa structure consisting of an upper surface and sidewalls (Figure 1).

[0008] However, when the indium concentration is high (for example, [In] ≥ 10 at%), mechanical stress occurs due to the mismatch of lattice constants between the GaN-based region and the InGaN-based active region 22, and plastic relaxation ultimately generates structural defects. These structural defects affect the radiation efficiency of LEDs and micro-LEDs. In particular, obtaining red LEDs with good radiation efficiency is especially difficult.

[0009] Another drawback of this type of mesa structure concerns posterior structuring. The sidewalls 200 obtained by etching generally have defects that promote the appearance of non-radioactive surface recombination, further reducing the radiation efficiency of the LED.

[0010] One solution to reduce sidewall defects is to directly form a GaN-based three-dimensional structure. This three-dimensional structure can be conical, as shown in Figure 2. To further restrict the plastic stress relaxation phenomenon, these cones can constitute a bulk InGaN region below the active region 22. The paper "Nanoscale selective area growth of thick, dense, uniform, In-rich, InGaN nanostructure arrays on GaN / sapphire template, S. Sundaram and al., Journal of Applied Physics 116, 163105 (2014)" discloses, for example, a bulk InGaN conical region. Hereinafter, such a bulk InGaN conical region 21 will be referred to as an "InGaN cone". [Prior art documents] [Non-patent literature]

[0011] [Non-Patent Document 1] Nanoscale selective area growth of thick, dense, uniform, In-rich, InGaN nanostructure arrays on GaN / sapphire template, S. Sundaram and al., Journal of Applied Physics 116, 163105 (2014) [Overview of the Initiative] [Problems that the invention aims to solve]

[0012] InGaN cones can be grown by epitaxy from a GaN layer 11 partially covered by a masking layer 12.

[0013] A drawback of the InGaN cones 21 formed in this way is that they may have numerous structural defects. Therefore, the crystal quality of the bulk InGaN region is not sufficient for manufacturing optoelectronic devices, especially LEDs, that have satisfactory performance.

[0014] To improve the crystal quality of epitaxial InGaN cones 21, one solution involves growing these cones 21 from a GaN buffer layer 11. Such a buffer layer 11 is particularly thicker than conventional thin layers. The buffer layer 11 allows structural defects to be trapped at the interface with the underlying support 10, for example, made of silicon, beneath the layer 11. Since the concentration of these structural defects generally decreases along the thickness of the layer, the crystal quality of the GaN buffer layer 11 is improved above it. However, the use of such a thick GaN buffer layer 11 introduces a problem of curvature relative to the silicon support 10 in the shape of a wafer. Such a buffer layer is also expensive to manufacture.

[0015] Another drawback of this type of conical structure is that the indium incorporation into the bulk InGaN region 21 remains limited, even on the GaN buffer layer 11. In particular, it is difficult to form InGaN cones 21 with satisfactory crystallinity and an indium concentration [In] ≥ 10 at%. Therefore, these three-dimensional conical InGaN structures cannot be used to form red-emitting micro-LEDs with satisfactory radiation efficiency.

[0016] The present invention aims to overcome at least partially some of the above-mentioned drawbacks.

[0017] In particular, the objective of the present invention is to provide a three-dimensional structure made of InGaN cones with improved crystal quality.

[0018] Another object of the present invention is to provide a method for forming InGaN cones that can reduce the manufacturing cost of InGaN cones and / or improve the crystal quality of InGaN cones.

[0019] Another object of the present invention is to provide a photoelectronic device, particularly a GaN-based 3D LED, that includes an InGaN cone that emits red or green light with improved radiant efficiency.

[0020] Other objects, features, and advantages of the present invention will become apparent from the following description and accompanying drawings. It will be understood that other advantages can be incorporated. [Means for solving the problem]

[0021] To achieve the above objective, the present invention provides, according to a first aspect, a three-dimensional structure for photoelectrons including a cone made of a first InGaN-based material formed from a planar substrate.

[0022] Advantageously, the three-dimensional structure includes a wire made of a second GaN-based material different from the first material, and the wire extends in a longitudinal direction perpendicular to the plane of the substrate between the substrate and the base portion of the InGaN-based cone so that each three-dimensional structure has the general shape of a pencil.

[0023] Thus, the GaN-based wire functions as a three-dimensional substrate for the InGaN-based cone. This wire-shaped three-dimensional substrate advantageously acts as an alternative to a thick GaN buffer layer-shaped planar substrate. This wire-shaped substrate has particularly better crystal quality and is more economical to manufacture than a thick GaN planar substrate.

[0024] Such a GaN-based wire is preferably obtained by bottom-up growth by an approach called "bottom-up" rather than top-down etching by a reverse approach called "top-down". In such bottom-up growth, the emergence of mechanical stress in GaN can be restricted, especially because a free surface exists on the wall surface of the growing wire. Thereby, the generation of structural defects in the wire can be suppressed, and the crystallinity of the GaN-based wire can be improved. Also, unlike the top-down method that promotes the generation of surface defects, the generation of surface defects on the wall surface of the wire can be suppressed or removed.

[0025] Furthermore, wire-shaped growth is more efficient than bulk layer growth. The surface area to volume ratio of the wire is indeed larger than that of the planar layer. Since growth is restricted by surface phenomena, wire-shaped growth has a higher growth efficiency. Thereby, by replacing the prior art GaN-based substrate with a wire shape, the manufacturing cost can be reduced.

[0026] Such wire-shaped substrates can also be advantageously formed on large-sized silicon wafers, such as 8-inch or 12-inch wafers, without the latter suffering from bending problems. Mechanical stresses associated with the difference in lattice constants between silicon and GaN-based materials are significantly reduced by growing wire shapes of this material compared to growing layer shapes of this material (when layer thickness and wire height are equal).

[0027] A second aspect of the present invention relates to a gallium nitride (GaN)-based optoelectronic device that includes a plurality of three-dimensional structures according to the first aspect of the present invention.

[0028] The three-dimensional structures are advantageously arranged with a separation distance ds of 650 nm or less, preferably 600 nm or less, between them.

[0029] Through the development leading to this invention, we were able to confirm that a high density of GaN-based wires promotes the growth of InGaN-based structures at the top of the wires, rather than at the wire walls. Technically, growth by vapor-phase epitaxy using organometallic precursors (MOVPEs) generates a substantially conforming layer on the substrate surface, regardless of whether it is structured or not. Therefore, according to this assumption, MOVPE deposition of InGaN on GaN-based wires forms a structure called a radial three-dimensional structure, having continuous layers of InGaN at the wire walls and top.

[0030] In contrast, within the framework of the present invention's development, it was found that by performing such InGaN MOVPE film deposition on a pair of GaN-based wires that are sufficiently close to each other, a structure called an axial 3D structure can be obtained, in which the InGaN-based material is mainly located at the top of the wires.

[0031] Furthermore, unexpectedly, these InGaN-based top structures grow in a conical shape rather than as wire-like layers. This is thought to be because the close proximity of the InGaN-based materials disrupts the equilibrium of the thermodynamic system, leading to the formation of the cones.

[0032] For example, it was found that when InGaN wells and AlGaN barriers are periodically deposited on a substrate as GaN-based wires spaced approximately 200 nm apart, InGaN-based bulk cones are formed at the top of the wires.

[0033] Under such high wire density conditions, the distance ds between wires is 650 nm or less, so indium is homogeneously dispersed when the cone structure is formed at the top.

[0034] By obtaining such bulk InGaN-based cones, it is advantageous to grow active InGaN-based regions having improved crystal quality and / or increased indium concentration.

[0035] InGaN-based cones can advantageously have inclined surfaces corresponding to semipolar surfaces. These semipolar surfaces are, for example, of the {10-11} type. Such semipolar surfaces promote indium uptake compared to the nonpolar surfaces of the wire wall. Therefore, the top InGaN cones can have a sufficient indium concentration, for example, [In]≧10at%, and LEDs configured to emit green or red light can be formed with improved radiation efficiency.

[0036] A third aspect of the present invention relates to a method for manufacturing a plurality of three-dimensional structures for optoelectronics, each consisting of an InGaN-based cone.

[0037] This method involves the following steps: - A step of providing a substrate including at least one surface layer that enables GaN nucleation and growth, for example, based on GaN, AlN, and / or other metal nitrides, - A step of depositing a masking layer on the GaN-based substrate, wherein the masking layer includes an opening through which the surface layer is exposed. - A step of forming GaN-based wires extending from the base portion to the top portion in a longitudinal direction substantially perpendicular to the surface layer by epitaxial growth from the exposed portion of the surface layer, and the base portion being connected to the surface layer through an opening, - The process includes the step of forming an InGaN-based cone on the top portion of a GaN-based wire by epitaxial growth.

[0038] This method allows for the formation of InGaN-based cones from a surface layer, also known as the nucleating layer, that is advantageously thin. This epitaxial wire exhibits higher crystal quality than a bulk layer of comparable thickness. Therefore, it is advantageous for forming a high-quality three-dimensional GaN-based substrate for growing InGaN-based cones, thereby improving the crystal quality of the InGaN-based cones.

[0039] Furthermore, GaN-based wire epitaxy is more efficient and consumes less precursor compared to GaN-based bulk layer epitaxy. Therefore, this method ultimately makes it possible to reduce the manufacturing cost of InGaN-based cones.

[0040] According to favorable possibilities, the openings in the masking layer are regularly distributed in an array shape with a pitch of 700 nm or less, for example, between 50 nm and 650 nm. This pitch partially determines the spacing ds between wires. As a result, after the growth of the GaN-based wires, the wires become relatively close to each other. This allows for the promotion of axial growth of InGaN at the top of the wires in a cone shape.

[0041] It is understood that the features and advantages of one aspect of the present invention may be applied mutatis mutandis to other aspects of the present invention.

[0042] The object, subject matter, features, and advantages of the present invention will become more apparent from a detailed description of the latter embodiments illustrated by the accompanying drawings below. [Brief explanation of the drawing]

[0043] [Figure 1] Figure 1 shows a 3D LED structure with a mesa structure according to conventional technology, and Figure 2 shows a 3D LED structure with a mesa structure according to conventional technology. [Figure 2] Figure 2 shows a 3D LED structure made of InGaN-based cones according to prior art. [Figure 3] Figure 3 shows a three-dimensional structure made of InGaN-based cones according to one embodiment of the present invention. [Figure 4A] Figure 4A is a scanning transmission electron microscope (STEM) image of a three-dimensional structure according to one embodiment of the present invention. [Figure 4B] Figure 4B is an enlarged view of the image in Figure 4A, showing the top cone of a three-dimensional structure according to one embodiment of the present invention. [Figure 4C] Figure 4C is an EDX mapping of Figure 4B showing the distribution of indium in the top pyramidal portion of a three-dimensional structure according to one embodiment of the present invention. [Figure 5] Figure 5 is a scanning electron microscope (SEM) image of an optoelectronic device containing multiple three-dimensional structures according to one embodiment of the present invention. [Figure 6] Figure 6 shows a scanning electron microscope (SEM) image of a photoelectronic device consisting of multiple three-dimensional structures according to another embodiment of the present invention. [Figure 7A] Figure 7A is a cathodoluminescence image formed for a wavelength λR in the red light region in a top view of the optoelectronic device shown in Figure 6. [Figure 7B] Figure 7B shows the image in Figure 7A with an expanded dynamic range of contrast, emphasizing the difference in emission intensity at wavelength λR of the InGaN-based cones in the top portion. [Figure 7C] Figure 7C is a hyperspectral image showing the cathodoluminescence emission spectra associated with each point in the spatial profile shown in Figure 7B. [Figure 8]Figure 8 shows the photoluminescence spectrum of the optoelectronic device shown in Figure 6. [Figure 9] Figure 9 shows the photoluminescence spectrum of a photoelectronic device including multiple three-dimensional structures according to another embodiment of the present invention. [Figure 10A] Figure 10A is a scanning electron microscope (SEM) image of a photoelectronic device including multiple three-dimensional structures according to another embodiment of the present invention. [Figure 10B] Figure 10B shows the photoluminescence spectrum of the optoelectronic device shown in Figure 10A. [Modes for carrying out the invention]

[0044] The drawings are provided for illustrative purposes only and do not limit the invention. They constitute a schematic representation of the principles intended to facilitate understanding of the invention and are not necessarily on a practical scale. In particular, the dimensions of the various elements of the three-dimensional structure are not necessarily representative of reality.

[0045] Before commencing a detailed examination of embodiments of the present invention, it should be noted that the present invention in its first aspect includes, in particular, any of the following features that can be used in combination or as substitutes:

[0046] According to one embodiment, the wire has a height of 150 nm or more.

[0047] According to one embodiment, the wire has a diameter of 30 nm or more and / or 500 nm or less.

[0048] According to one embodiment, the InGaN-based cone has a base diameter, and the wire diameter is less than or equal to the base diameter.

[0049] According to one embodiment, the base portion of the InGaN-based cone is substantially parallel to the plane of the substrate.

[0050] In one embodiment, the GaN-based wire comprises a base that rests on a planar substrate and a top portion that supports the base portion of an InGaN-based cone, with the top portion surrounded by an InGaN-based collar portion.

[0051] According to one embodiment, the InGaN-based cone has a surface inclined at an angle of approximately 30° with respect to the longitudinal direction, and these inclined surfaces substantially correspond to {10-11} type semipolar planes.

[0052] According to one embodiment, the three-dimensional structure further comprises an active InGaN region on at least one face of an InGaN-based cone, the active region being configured to emit or receive light emission.

[0053] According to one embodiment, the InGaN-based cone has an indium level [In] ≥ 10%.

[0054] According to one embodiment, the InGaN-based cone has a height of 50 nm or more and / or a height of 500 nm or less.

[0055] In one embodiment, the diameter of the wire is larger than the diameter of the opening in the masking layer.

[0056] The present invention, in its second aspect, is particularly characterized by the following features which can be used in combination or alternately:

[0057] For example, at least a portion of the three-dimensional structure of an optoelectronic device is configured to emit light with a dominant wavelength, which varies depending on the diameter Φ of the wires of the three-dimensional structure and the separation distance ds that separates two adjacent three-dimensional structures.

[0058] According to one embodiment, multiple three-dimensional structures have the same separation distance ds and the same wire diameter Φ, and the three-dimensional structures are configured to emit light with a main wavelength λ, which is partially determined by the wire diameter Φ and separation distance ds, particularly to green three-dimensional structures on the same plate (especially the active layer having the same growth conditions).

[0059] According to one embodiment, the optoelectronic device includes at least first, second, and third pluralities of three-dimensional structures respectively having first, second, and third separation distances ds1, ds2, ds3 of the wire (24) and first, second, and third diameters Φ1, Φ2, Φ3 such that ds1 < ds2 < ds3 and / or Φ1 > Φ2 > Φ3, and the first, second, and third pluralities of three-dimensional structures (1) each have first, second, and third wavelengths λ1, λ2, λ3 that are different from each other, and preferably emit light radiation such that λ1 > λ2 > λ3.

[0060] According to one embodiment, the optoelectronic device includes first and second pluralities of three-dimensional structures respectively having first and second separation distances ds1, ds2 of the wire and first and second diameters Φ1, Φ2 of the wire such that ds ▁ 1 < ds2 and Φ1 > Φ2, and the first and second pluralities of three-dimensional structures each have first and second wavelengths λ1, λ2 that are different from each other, and preferably emit light radiation such that λ1 > λ2.

[0061] According to one embodiment, the optoelectronic device includes at least a first plurality of three-dimensional structures having a first separation distance ds1 and a first diameter Φ1, and the three-dimensional structures emit light radiation having a first wavelength λ1 belonging to the spectrum of red light.

[0062] According to one embodiment, the optoelectronic device includes at least a second plurality of three-dimensional structures having a second separation distance ds2 and a second diameter Φ2 of the wire, and the three-dimensional structures emit light radiation having a second wavelength λ2 belonging to the spectrum of green light.

[0063] According to one embodiment, the optoelectronic device includes at least a third plurality of three-dimensional structures having a third separation distance ds3 and a third diameter Φ3 of the wire, and the three-dimensional structures emit light radiation having a third wavelength λ3 belonging to the spectrum of blue light.

[0064] According to one embodiment, ds1 < ds2 < ds3 and / or Φ1 > Φ2 > Φ3.

[0065] According to one embodiment, the first wavelength λ1 is greater than 600 nm.

[0066] According to one embodiment, the second wavelength λ2 is configured between 500 nm and 600 nm.

[0067] According to one embodiment, the third wavelength λ3 is less than 500 nm.

[0068] For example, the dominant wavelength λ of the light emission is 400 nm or greater and / or 700 nm or less.

[0069] For example, the dominant wavelength λ of light emission is composed of wavelengths between 500 nm and 650 nm.

[0070] The third aspect of the present invention particularly includes any of the following features that can be used in combination or alternately:

[0071] For example, this method involves the following steps: - A step of providing a substrate including at least one surface layer that enables GaN nucleation and growth, for example, based on GaN, AlN, and / or other metal nitrides, - A step of depositing a masking layer on the substrate, wherein the masking layer includes an opening through which the surface layer is exposed, - A step of forming GaN-based wires extending from the base portion to the top portion in a longitudinal direction substantially perpendicular to the surface layer by epitaxial growth from the exposed portion of the surface layer, and the base portion being connected to the surface layer through an opening, - The process includes the step of forming an InGaN-based cone on the top portion of a GaN-based wire by epitaxial growth.

[0072] According to one embodiment, the surface layer has a thickness between 1 nm and 200 nm, preferably between 10 nm and 200 nm.

[0073] According to one embodiment, the formation of InGaN-based cones and / or the formation of GaN-based wires is performed by metalorganic vapor phase epitaxy MOVPE.

[0074] According to one embodiment, the openings of the masking layer are arranged at intervals with a pitch configured between 50 nm and 700 nm.

[0075] According to one embodiment, the openings of the masking layer are -2 above 4 μm and / or -2 below 400 μm and are distributed so as to have the following surface density.

[0076] According to one embodiment, the formation of InGaN-based cones is configured such that the InGaN-based cones have an indium level [In] ≧ 10 at%.

[0077] According to one embodiment, the formation of InGaN-based cones is performed at a temperature of 780 °C or higher.

[0078] According to one embodiment, the masking layer has at least first, second, and third pitches p1, p2, p3 such that p1 < p2 < p3 and Φo1 > Φo2 > Φo3, and first, second, and third opening diameters Φo1, Φo2, Φo3, and includes at least first, second, and third plural openings respectively. The three-dimensional structures are formed so as to simultaneously form first, second, and third plural three-dimensional structures respectively having mutually different first, second, and third wavelengths λ1, λ2, λ3, and preferably emitting light radiation with λ1 > λ2 > λ3.

[0079] According to one example, the masking layer has first and second pitches p1, p2 such that p1 < p2 and first and second opening diameters Φo1, Φo2 such that Φo1 > Φo2, and includes first and second plural openings, and is configured to simultaneously form first and second plural three-dimensional structures respectively emitting light radiation having mutually different first and second wavelengths λ1, λ2, and preferably λ1 > λ2.

[0080] It is understood that, as long as they do not contradict each other, three-dimensional structures, manufacturing methods, and optoelectronic devices can be constructed by applying any of the above-mentioned features mutatis mutandis.

[0081] In this invention, the three-dimensional structure made of InGaN-based cones is particularly specialized for the manufacture of three-dimensional LEDs.

[0082] The present invention can be more broadly implemented in various optoelectronic devices having a three-dimensional structure, particularly in optoelectronic devices that constitute an active region.

[0083] The active region of a photoelectronic device refers to the region from which most of the light radiation supplied by the device is emitted, or the region from which most of the light radiation received by the device is captured.

[0084] Therefore, the present invention can also be implemented in the context of laser devices or photovoltaic devices.

[0085] Unless explicitly stated otherwise, in the context of the present invention, the relative arrangement of a third layer interposed between the first and second layers does not necessarily mean that the layers are in direct contact with each other, but rather that the third layer is in direct contact with the first and second layers or separated from them by at least one other layer or at least one other element.

[0086] The process of forming various elements is understood in a broad sense: they can be carried out in several sub-processes that are not necessarily strictly sequential.

[0087] The diameter of the wire or the base of the cone represents its maximum lateral dimension. In this invention, the wire does not necessarily have to have a circular cross-section. In particular, in the case of GaN-based wires, this cross-section may be hexagonal. In this case, the diameter corresponds to the distance between two opposite vertices of the hexagonal cross-section. Alternatively, it can correspond to the average diameter calculated from the diameter of the circle inscribed in the polygon of the cross-section and the diameter of the circumscribed circle of this polygon. The diameter of the three-dimensional structure is approximately equal to the diameter of the wire in this three-dimensional structure.

[0088] A pencil shape refers to a shape consisting of a cylindrical body and a tapered tip provided at one end of the body. The body is preferably a right circular cylinder. It may have a hexagonal or polygonal cross-section. In this patent application, the cross-section is substantially constant along the height of the cylinder. Nevertheless, it may vary slightly, for example, up to 5% or 10% of its surface, and this does not cast doubt on the definition of the cylindrical body described above. This cylinder corresponds to the GaN-based wire in this patent application. The tapered tip is attached to one end of the cylinder. It preferably has the same base portion as the cylinder and preferably extends continuously, converging toward a point or top portion region. The tapered tip may optionally consist of one or more degrees. The tapered tip corresponds to the top portion of the InGaN-based cone in this patent application.

[0089] A wire refers to a three-dimensional structure with an elongated shape in the longitudinal direction. The longitudinal dimension of the wire is greater than, preferably much greater than, the transverse dimension of the wire in the plane xy in the figure, along the z axis in the figure. The longitudinal dimension is, for example, at least 5 times, preferably at least 10 times, the transverse dimension.

[0090] The surface density of a three-dimensional structure depends on the separation distance ds that separates two adjacent three-dimensional structures. In particular, it can be inversely proportional to this distance ds according to k / ds², where k is the proportionality constant.

[0091] In this patent application, the terms "concentration," "level," and "content" are synonymous.

[0092] More specifically, concentration is expressed in relative units such as mole fraction or atomic fraction (at%), or the number of atoms per cubic centimeter (at.cm³). -3 It can be expressed in absolute units such as ).

[0093] In the following, unless otherwise specified, concentrations are expressed as atomic fractions in at%.

[0094] In this patent application, the terms “light-emitting diode,” “LED,” or simply “diode” are used synonymously. Furthermore, “LED” may also be understood as “microLED.”

[0095] In the following, the following abbreviations related to material M will be used as appropriate.

[0096] Mi, following the terminology of the suffix -i commonly used in the field of microelectronics, refers to a material M that is inherently or unintentionally doped.

[0097] Mn refers to material M doped with N, N+, or N++, and the suffix -n follows terminology commonly used in the field of microelectronics.

[0098] Mp refers to material M doped with P, P+, or P++, following the glossary of terms commonly used in the field of microelectronics due to the suffix -p.

[0099] A substrate, layer, or device "based on" material M means a substrate, layer, or device consisting of material M alone, or material M and optionally other materials, such as alloying elements, impurities, or doping elements. Therefore, a gallium nitride (GaN)-based wire may consist, for example, gallium nitride (GaN or GaN-i) or doped gallium nitride (GaN-p, GaN-n). A gallium nitride-indium (InGaN)-based cone may consist, for example, gallium nitride-aluminum (AlGaN) or gallium nitride (GaInAlN) having different content of aluminum and indium. In the context of this invention, material M is generally crystalline.

[0100] A set of reference marks, preferably orthogonal, consisting of axes x, y, and z, is shown in the attached diagram.

[0101] In this patent application, preferably, the thickness of the layer and the height of the device are considered. The thickness is taken in a direction perpendicular to the main extension plane of the layer, and the height is taken in a direction perpendicular to the base plane xy of the substrate. Thus, the buffer layer or surface layer typically has a thickness along z, and the wire has a height along z.

[0102] Dimensional values ​​will match within the manufacturing tolerance and measurement tolerance range. Therefore, two theoretically identical spacing distances ds or two wire diameters may actually have slight dimensional variations.

[0103] The terms "substantially," "approximately," and "of the order of" mean "within 10%" of a value when referring to a value, and "within 10°" of a direction when referring to an angular direction. Therefore, a direction substantially perpendicular to a plane means a direction that has an angle of 90 ± 10° with respect to that plane.

[0104] Scanning electron microscopy (SEM), transmission electron microscopy (TEM), or scanning transmission electron microscopy (STEM) analysis can be performed to determine the shape, crystallographic orientation, and composition of various elements of the three-dimensional structure (particularly wires, cones, collars, and active regions).

[0105] The crystallographic orientation of various elements can be directly estimated from TEM or SEM images, and can also be precisely determined, for example, by microdiffraction in a TEM.

[0106] TEM and STEM are also suitable for observing and identifying structural defects, particularly dislocations within InGaN cones. A variety of techniques, including dark-field and bright-field imaging, weak beam imaging, and high-angle diffraction (HAADF) imaging, can be performed non-extensively, as listed below.

[0107] The chemical composition of various elements can be determined using the well-known EDX or X-EDS method (energy dispersive x-ray spectroscopy).

[0108] This method is suitable for compositional analysis of small devices such as 3D LEDs. A scanning electron microscope (SEM) can be used to analyze the metal structure, and a transmission electron microscope (TEM) can be used to analyze thin sections.

[0109] The optical properties of various elements, particularly the main emission wavelengths of the cones and / or the active regions of InGaN systems, can be determined by spectroscopy.

[0110] Cathodoluminescence (CL) and photoluminescence (PL) spectroscopy are well suited for optically characterizing the three-dimensional structures described in the present invention.

[0111] The above techniques, in particular, make it possible to determine whether a photoelectronic device having a three-dimensional structure consists of InGaN-based cones formed on the top portion of a GaN-based wire, as described in the present invention. Furthermore, the possibility of color being present can also be easily observed using these techniques.

[0112] Next, a first embodiment of the three-dimensional structure according to the present invention will be described with reference to Figures 3 and 4A to 4C.

[0113] Figure 3 shows a plurality of adjacent three-dimensional structures 1 arranged on the same substrate 2a. The following description relating to one of these three-dimensional structures naturally extends to the other three-dimensional structures among these plurality that are considered to be substantially identical to one another.

[0114] The three-dimensional structure 1 is composed of at least one wire 24 and one cone 21 provided on the top of the wire 24. Preferably, it is formed directly from a substrate 2a. This substrate 2a may be a laminated structure in the direction z, consisting of a support 10, a surface layer 13 called a nucleating layer, and a masking layer 12. The substrate 2a is substantially planar and parallel to the plane xy.

[0115] The support 10 can be made of sapphire, in particular to minimize lattice constant mismatch with GaN, or it can be made of silicon for cost reduction and technical compatibility reasons. In the latter case, it can be made into a wafer shape with a diameter of 200 mm or 300 mm. In particular, it functions as a support for three-dimensional structures.

[0116] The nucleation layer 13 is preferably AlN-based. Alternatively, it can be based on other metal nitrides, such as GaN or AlGaN. This nucleation layer 13 can be any layer that enables GaN nucleation and growth as known to those skilled in the art. It can be formed on the silicon support 10 by epitaxy, preferably by organometallic vapor phase epitaxy (MOVPE). Advantageously, it has a thickness of 200 nm or less, preferably 100 nm or less, for example, on the order of 50 nm. This limits the mechanical stress induced on the support 10 by this layer 13. This avoids harmful bending of the support 10. Such a thickness also allows for limiting the appearance of structural defects in the nucleation layer 13. In particular, the growth of this nucleation layer 13 can be pseudo, i.e., it is possible to elastically relax the epitaxy stress (particularly related to the difference in lattice constants between Si and AlN, GaN, or AlGaN) during growth. Thus, the crystal quality of this nucleation layer 13 can be optimized.

[0117] The masking layer 12 is preferably made of a dielectric material, such as silicon nitride (Si3N4). It can be deposited on the nucleation layer 13 by chemical vapor deposition (CVD). It consists of preferably circular openings 120 that partially cover the nucleation layer 13 and expose areas of the nucleation layer 13. These openings 120 typically have dimensions, e.g., a diameter Φo or average diameter, between 30 nm and 500 nm. The openings 120 can be distributed uniformly within the masking layer 12, for example, in the shape of an ordered array. The pitch, i.e., the distance separating the centers of two adjacent openings 120, is preferably 700 nm or less. It can be configured between 50 nm and 650 nm. The openings 120 are advantageously 4 μm -2It has a higher surface density. This ultimately allows for the acquisition of a densely distributed three-dimensional structure on the substrate 2a. These openings 120 can be fabricated, for example, by UV or DUV (Deep UV) lithography, by electron beam lithography, or by NIL (Nanoimprint lithography). Thus, the formation of the masking layer 12 typically consists of forming the openings 120, typically by lithography, following the deposition of a dielectric material. Such a masking layer 12 allows for the localized growth of the three-dimensional structure at each opening 120. In particular, during a preliminary growth process called germination, GaN-based seeds 20 are formed in the openings 120 and then fill the openings 120. Subsequently, the growth of the wire 24 is carried out locally from these seeds 20.

[0118] Wire 24 is GaN-based. It is preferably oriented parallel to z in the crystallographic direction

[0001] corresponding to axis c of the hexagonal structure.

[0119] The GaN-based wire 24 can be formed by epitaxy, preferably by organometallic vapor phase epitaxy (MOVPE), as specifically defined in Publication WO2012136665. The source of gallium in the form of an organometallic precursor (precursor III) may typically be trimethylgallium (TMGa) or triethylgallium (TEGa). The nitrogen source may typically be ammonia (NH3) (precursor V). The growth temperature is preferably 700°C or higher, for example, on the order of 1000°C. The gas pressure in the growth reactor is, for example, on the order of 425 Torr. Growth is preferably carried out under a neutral and / or reducing atmosphere, typically by adding nitrogen (N2) and / or dihydrogen (H2). Various gas flow rates can be adapted in ways known to those skilled in the art, particularly depending on the volume of the reactor.

[0120] Alternatively, the formation of wire 24 can be carried out by molecular beam epitaxy (MBE), vapor phase epitaxy using a chlorinated gaseous precursor (HVPE, an acronym for "Hydride Vapor Phase Epitaxy"), chemical vapor deposition (CVD), and MOCVD (an acronym for "MetalOrganic Chemical Vapor Deposition").

[0121] Optionally, conventional surface preparation processes (chemical cleaning, heat treatment) for the seed 20 can be performed before the epitaxial growth of the wire 24.

[0122] The wire 24 may consist of N-doped GaN regions. In known embodiments, these N-doped regions may result from growth, implantation, and / or activation annealing. N-doping can be obtained directly, in particular, during growth by adding silane, disilane, or Germanium vapor from a silicon or germanium source. The growth conditions required for the formation of such wire 24 are widely known.

[0123] The wire 24 has a diameter Φ of 30 nm or more and / or 500 nm or less. This diameter Φ may be larger than the diameter of the opening 120 and the diameter of the seed 20 that gave rise to the wire 24. In this case, the base portion 240 of the wire 24 puts a load on the masking layer 12 of the substrate 2a. The cross-section of the wire 24 in the plane xy typically has a more or less regular hexagonal shape. The wire 24 also has a height h of 150 nm or more. The top portion 241 of the wire 24 is preferably substantially flat and parallel to the plane xy so as to accommodate the base portion 210 of the cone 21. The wire 24 preferably has an aspect ratio h / Φ greater than 1, preferably an aspect ratio greater than 5. This improves the crystallinity of the wire 24 at its top portion 241. This also allows the top portion 241 to be separated from the underlying planar substrate 2a. Therefore, the local environment of the top portion 241 is not disturbed by the underlying planar substrate 2a. Therefore, the formation of the InGaN cone 21 at the top portion 241 of the wire 24 is not affected by the planar substrate 2a.

[0124] The cones 21 are based on InGaN. Preferably, they are oriented in the same crystallographic direction as the wire 24. The InGaN-based cones 21 can be formed by epitaxy, preferably by metal-organic vapor deposition (MOVPE). The growth conditions required for the formation of the cones 21 are different from those required for the formation of the wire 24. An indium source in the form of an organometallic precursor, such as trimethylindium (TMIn) or triethylindium (TEIn), is added to a source of gallium (TEGa), trimethylgallium (TMGa), and nitrogen (NH3) to grow the InGaN-based material. The ratio of the indium precursor element (TMIn, TEIn) to all precursor III (TEGa, TMGa, and TMIn, TEIn...) can be on the order of 0.3. The growth temperature can be about 800°C. The gas pressure in the growth reactor is, for example, on the order of 100 Torr. The V / III or In / III ratio, pressure, and growth temperature can be adjusted according to the design of the epitaxy reactor and the target emission wavelength.

[0125] According to one possibility, the Ga / N elemental ratio may be greater than 100. This promotes the growth of cone shapes in this InGaN-based material.

[0126] According to one possibility, the growth of wire 24 is configured to acquire Ga polarity at the top portion 241 of wire 24. Such polarity also promotes a cone-shaped growth morphology.

[0127] The immediate environment at the top portion 241 of the wire 24 can also affect the growth morphology. In particular, proximity to other wires 24 and other adjacent top portions 241 can locally alter the growth conditions of the InGaN-based material. In the context of the development of this invention, the wire density on the substrate 2a is high, especially 4 μm -2 It appeared that larger sizes promoted the growth morphology of cone-shaped cells. Furthermore, it was observed that the higher the surface density of the wire 24, the higher the concentration of indium [In] incorporated into the cones 21.

[0128] The growth temperature of the cones 21 is preferably 700°C or higher, more preferably 750°C or higher, and advantageously on the order of 780°C. This can improve the crystallinity of the cones 21. The formation of the InGaN-based cones 21 and the wires 24 can advantageously be carried out on one same growth frame.

[0129] Figures 4A and 4B are STEM-HAADF images of the three-dimensional structure obtained by MOVPE. These images show, in particular, that the wire 24 is substantially free of structural defects and that the cones 21 also have very good crystal quality.

[0130] Structurally, the cone 21 consists of a base portion 210 resting on the top portion 241 of the wire 24, and a top portion 211 located opposite the base portion 210 along the z axis, the top portion 211 of the cone 21 can form a tip, which may be more or less truncated or flattened (Figure 4A). The base portion 210 of the cone 21 has a diameter Φp that is larger than or equal to the diameter Φ of the wire 24. This base portion 210 typically has the same more or less regular hexagonal shape as the cross-section of the wire 24. The cone 21 extends from the base portion 210 to the top portion 211 while maintaining a cross-section that is typically more or less regular hexagonal in the plane xy. Thus, the cone 21 consists of inclined sides or faces 212 extending from the base portion 210 to the top portion 211. In particular, there may be six of these faces 212. The cone 21 has a height hp. This height hp is on the order of the height h of the wire 24, preferably at least twice as small, preferably at least five times as small, and may be, for example, about ten times as small. The cone 21 preferably has an aspect ratio hp / Φp of the order of 1, which corresponds to an inclination of the surface 212 of the order of 60° with respect to the plane xy. Such a surface 212 can advantageously correspond to a {10-11} type surface. This can facilitate the uptake of indium in the cone 21 or in the active region 22 formed on these surfaces 212. According to another possibility, the surface 212 can be inclined at an angle of about 80° with respect to the plane xy. Such an inclination of the surface 212 substantially coincides with a {20-21} type semipolar surface.

[0131] The cone 21 can extend below the base portion 210, around the top portion 241 of the wire 24, for example, in the shape of a collar 26 (Figure 4B). This collar 26 can constitute a facet 262 as a continuation of the surface 212 of the cone 21. Typically, together with the cone 21, the collar 26 forms a cap covering the top portion 241 of the wire 24. The collar 26 allows for, for example, improved mechanical cohesive force between the wire 24 and the cone 21. The collar 26 can have a considerable height, for example, on the order of one-third or half the height of the cone. It can also extend toward the base portion 240 of the wire 24 in the shape of a thin layer of several nanometers, for example on the order of 1-5 nm, covering the vertical wall of the wire 24. The collar 26 may consist of a series of irregular rings along z, which may thus have castellations forming a process or level in cross-section along zx. The collar 26 does not necessarily have to be continuous with the cone 21. It may be something independent of that.

[0132] The InGaN-based cone 21 preferably has an indium concentration of 10 at% or more. The indium is distributed throughout the entire volume of the cone 21, as shown by the EDX mapping of the indium element in Figure 4C. Preferably, it is homogeneously distributed within the cone 21 and, where appropriate, within the collar 26.

[0133] To manufacture a photoelectronic device that emits or receives light radiation, the three-dimensional structure 1 may consist, in particular, of an active region 22 on the side surface 212 of a cone 21 and a GaN-based region 23 on the active region 22, as shown in Figure 3.

[0134] In the case of LEDs, the active region 22 can typically comprise multiple quantum wells configured to emit light at a dominant wavelength λ, and these quantum wells are, for example, based on InGaN. These can conventionally be separated from each other by barriers based on AlGaN.

[0135] Region 23 can be based on GaN, particularly P-doped GaN. It typically covers the active region 22 and allows for the injection of carriers into the active region 22. The growth of region 23 on the active region 22 is preferably carried out to obtain a conformal layer. The thickness of this layer is preferably limited to tens of nanometers, e.g., less than 100 nm or less than 50 nm, to limit the reabsorption of light radiation emitted by the active region 22. The edges of the layer forming region 23 may have linear sides parallel to z, as shown in Figure 3. Alternatively, these sides are inclined and extend to either side of the three-dimensional structure. The sides of region 23 on a given three-dimensional structure can optionally be joined to the sides of region 23 on at least one adjacent three-dimensional structure. In this case, a single region 23 in the shape of a substantially continuous layer can be formed on a plurality of adjacent three-dimensional structures.

[0136] The dominant wavelength of the light emission from the active region 22 depends particularly on the concentration of indium in the quantum well. As the indium content increases, the dominant wavelength increases towards the red light region of the visible spectrum. In particular, indium concentrations greater than 15 at% or 20 at% can result in the emission of red light with a dominant wavelength of 600 nm or greater.

[0137] For this light emission to be satisfactory as an LED, the radiation efficiency must be sufficiently high, for example, on the order of 20%. To achieve such efficiency, the active region 22 must have good crystal quality.

[0138] The InGaN-based cones 21 of the three-dimensional structure advantageously form a transition region between the GaN-based wires 24 and the active InGaN-based region 22. Therefore, the concentration of incorporated indium can be gradually increased, for example, stepwise, from the cones 21 toward the active region 22. This suppresses the appearance of structural defects in the active region 22. In this way, the indium concentration required in the active region 22 for red light emission can be achieved without reducing the crystallinity of the active region 22. Such a three-dimensional structure consisting of GaN-n wires 24, InGaN-based cones 21, In(Al)GaN-based active region 22, and GaN-p-based region 23 can therefore advantageously emit red light with high radiation efficiency.

[0139] Figure 5 shows how multiple three-dimensional structures, as described earlier, are distributed on a high-density array. In this example, the three-dimensional structures have a diameter of approximately 200 nm and a diameter of 20 μm. -2 It has a surface density of the order of [order of magnitude].

[0140] According to another exemplary embodiment, Figure 6 shows a diameter of approximately 100 nm and 25 μm. -2 The following shows multiple three-dimensional structures with surface densities of the order of . InGaN-based cones 21 are excluded from these examples.

[0141] Figures 7A and 7C show some optical properties obtained by cathodoluminescence spectroscopy in SEM for the three-dimensional structures exemplified in Figure 6. Figure 7A specifically shows the mapping of cathodoluminescence intensity at acquisition wavelengths on the order of 610 nm in the top view of these three-dimensional structures. It can be seen that most of the InGaN-based cones emit light at this wavelength when stimulated by SEM electron beam scanning. Figure 7B shows the data taken from Figure 7A with increased contrast intensity dynamics. Different emission intensity thresholds of the cones at wavelength λ ≈ 620 nm are visible. The data profile shown on the map in Figure 7B is extracted and shown in Figure 7C. Each point in the profile corresponds to a wavelength spectrum acquired over a range of approximately 250 nm to 750 nm. These spectra are collected in Figure 7C. The emission spectra of the cones all appear to be concentrated at wavelength λ ≈ 620 nm. Also, the width of the emission peaks is very small, on the order of tens of nanometers. Such spectral purity indicates particularly good crystallinity of the cones.

[0142] Figure 8 shows the photoluminescence spectra associated with these multiple three-dimensional structures. The strongest emission peaks are concentrated around λ ≈ 610 nm. The width of half the height of this peak is approximately 45 nm. This peak corresponds to the InGaN cones of the three-dimensional structure.

[0143] The measured radiation efficiency for these cones is on the order of 20%. This confirms that the cones of the three-dimensional structure obtained according to the embodiments described above have crystal quality suitable for the manufacture of red LEDs.

[0144] Therefore, multiple such three-dimensional structures can be advantageously implemented within a red 3D LED.

[0145] Figure 9 shows diameters of approximately 100 nm and 6 μm. -2Another example of a photoluminescence spectrum obtained for a three-dimensional structure having a surface density of the order of is shown (not shown). Here, the surface density of the three-dimensional structure is divided to approximately twice that of the previous example. In this example, the strongest emission peak corresponding to the InGaN cones of the three-dimensional structure is centered around λ ≈ 480 nm (blue light region). The width of half the height of this peak is approximately 20 nm. Therefore, multiple such three-dimensional structures can be advantageously implemented in a blue 3D LED. Another example of a three-dimensional structure is shown in Figure 10A.

[0146] Figure 10B shows the photoluminescence spectrum associated with the three-dimensional structure in this example. The strongest emission peak is centered around λ ≈ 515 nm (green light range). The width of half the height of this peak is approximately 20 nm. This peak corresponds to the InGaN cones of the three-dimensional structure shown in Figure 10A. Therefore, multiple such three-dimensional structures can be advantageously implemented within a green 3D LED.

[0147] Thus, through these various examples, it can be seen that by reducing the surface density of a three-dimensional structure with respect to a given diameter, the main emission peak of the three-dimensional structure shifts to shorter wavelengths. Furthermore, the width of the intermediate height of this peak also decreases.

[0148] Conversely, increasing the surface density and thus the diameter shifts the main emission peak to a larger wavelength.

[0149] Therefore, a wide range of wavelength settings can be obtained by changing the surface density and / or diameter of the three-dimensional structure.

[0150] Therefore, by adapting the surface density and diameter of these three-dimensional structures, the three-dimensional structures according to the present invention can be advantageously implemented in different types of optoelectronic devices, particularly red 3D LEDs, green 3D LEDs, and blue 3D LEDs.

[0151] A three-dimensional structure having different diameters Φ of the wire 24 and different separation distances ds can be advantageously disposed on the same substrate 2a so as to form regions that emit light radiation at different principal wavelengths. For example, an optoelectronic device can be as follows: - A first region composed of a three-dimensional structure having a first diameter Φ1 and a first separation distance ds1, wherein the three-dimensional structure emits light radiation at a first wavelength λ1 (red light range) greater than, for example, 600 nm. - A second region composed of a three-dimensional structure having a second diameter Φ2 and a second separation distance ds2, wherein the three-dimensional structure emits light radiation at a second wavelength λ2 (green light range) configured between, for example, 500 nm and 600 nm. - A third region including a three-dimensional structure having a third diameter Φ3 and a third separation distance ds3, wherein the three-dimensional structure emits light radiation at a third wavelength λ3 less than, for example, 500 nm (blue light range).

[0152] These first, second, and third regions may be partially embedded within each other such that there are respectively present first, second, and third subsets configured to emit light in the red, green, and blue light regions.

[0153] The present invention also relates to a method for manufacturing a 3D LED as described through the previous exemplary embodiments.

[0154] According to an advantageous embodiment, the method enables the simultaneous formation of first, second, and third regions of a three-dimensional structure configured to respectively emit light radiation having first, second, and third wavelengths λ1, λ2, λ3. In particular, such first, second, and third three-dimensional structure regions are formed from a masking layer 12 deposited on a substrate 2b including first, second, and third pluralities of apertures 120 respectively having first, second, and third pitches p1, p2, p3 and first, second, and third opening diameters Φo1, Φo2, Φo3 such that p1 < p2 < p3 and / or Φo1 > Φo2 > Φo3.

[0155] The present invention is not limited to the embodiments described above, but extends to all embodiments described in the claims. [Explanation of Symbols]

[0156] 1 3D structure 2, 2a, 2b flat board 2, 2a, 2b board 10 Support 11 Buffer Layer 12 masking layers 13 Surface layer 21. Cones 22 Active area 24 wires 26 Color section 120 opening 200 side wall 210 Base section 211 Top section 240 Base section 241 Top section

Claims

1. A gallium nitride (GaN)-based optoelectronic device comprising a plurality of first and second three-dimensional structures (1), Each of the first and second plurality of three-dimensional structures (1) includes an InGaN-based cone (21) made of a first InGaN-based material formed from a planar substrate (2, 2a, 2b), and a GaN-based wire (24) made of a second GaN-based material different from the first material, wherein the GaN-based wire (24) is connected to the base portion (210) of the InGaN-based cone (21) between the planar substrate (2, 2a, 2b) and the InGaN-based cone (21) so that each three-dimensional structure (1) has the general shape of a pencil. Between the planar substrates (2, 2a, 2b), the plurality of three-dimensional structures (1) extend in the longitudinal direction perpendicular to the plane, and each of the first and second plurality of three-dimensional structures (1) has first and second spacing distances ds1 and ds2 between the GaN-based wires (24) such that ds1 < ds2 and Φ1 > Φ2, and first and second diameters Φ1 and Φ2 of the GaN-based wires (24), and the plurality of three-dimensional structures (1) emit light radiation having first and second wavelengths λ1 and λ2 such that λ1 > λ2, respectively. The optoelectronic device comprises a GaN-based wire (24) having a base portion (240) that rests on the planar substrates (2, 2a, 2b) and a top portion (241) that supports the base portion (210) of the InGaN-based cone (21), the top portion (241) being surrounded by an InGaN-based color portion (26), the InGaN-based color portion (26) together with the InGaN-based cone (21) forming a cap that covers the top portion (241) of the GaN-based wire (24).

2. The optoelectronic device according to claim 1, wherein the base portion (210) of the InGaN-based cone (21) is substantially parallel to the plane of the planar substrate (2, 2a, 2b).

3. The optoelectronic device according to claim 1 or 2, wherein the InGaN-based cone (21) has a base diameter Φp, the GaN-based wire (24) has a diameter Φ, and the diameter Φ of the GaN-based wire (24) is less than or equal to the base diameter Φp.

4. The optoelectronic device according to any one of claims 1 to 3, wherein each of the three-dimensional structures (1) further comprises an InGaN-based active region (22) on at least one face (212) of the InGaN-based cone (21), and the active region (22) is configured to emit or receive light radiation.

5. The optoelectronic device according to any one of claims 1 to 4, wherein the first plurality of three-dimensional structures (1) are spaced apart from each other by a separation distance ds1 of 650 nm or less, and the second plurality of three-dimensional structures (1) are spaced apart from each other by a separation distance ds2 of 650 nm or less.

6. The optoelectronic device according to any one of claims 1 to 5, comprising at least first, second, and third three-dimensional structures (1) having first, second, and third separation distances ds1, ds2, and ds3 and first, second, and third diameters Φ1, Φ2, and Φ3 of the GaN-based wire (24) such that ds1 < ds2 < ds3 and / or Φ1 > Φ2 > Φ3, wherein the first, second, and third three-dimensional structures (1) emit light radiation having first, second, and third wavelengths λ1, λ2, and λ3 such that λ1 > λ2 > λ3.

7. A method for manufacturing the optoelectronic device described in Claim 1, The aforementioned optoelectronic device is based on gallium nitride (GaN), The method includes a first and second plurality of three-dimensional structures (1) for photoelectrons, each of which includes an InGaN-based cone (21) and a GaN-based wire (24), and the method comprises the following steps: - A step of providing a substrate (2b) having at least one surface layer (13) based on GaN, AlN, and / or other metal nitrides that enables GaN nucleation and growth, - A step of forming a masking layer (12) on the substrate (2b), wherein the masking layer (12) includes an opening (120) through which the surface layer (13) is exposed, - A step of forming the GaN-based wire (24) from the exposed portion of the surface layer (13) to the top portion (241) in a longitudinal direction substantially perpendicular to the surface layer (13), and the base portion (240) being connected to the surface layer (13) via the opening (120), - The process includes the step of forming the InGaN-based cone (21) on the top portion (241) of the GaN-based wire (24), - The method is characterized in that, in order to simultaneously form a plurality of first and second three-dimensional structures (1) having first and second spacing distances ds1 and ds2 between the GaN-based wires (24) such that ds1 < ds2 and Φ1 > Φ2, and first and second diameters Φ1 and Φ2 of the GaN-based wires (24), the masking layer (12) is formed with at least a plurality of first and second openings (120) having first and second pitches p1 and p2 such that p1 < p2 and Φo1 > Φo2, and first and second aperture diameters Φo1 and Φo2, respectively, and the plurality of first and second three-dimensional structures (1) are configured to emit light having first and second wavelengths λ1 and λ2 such that λ1 > λ2.

8. The method according to claim 7, wherein the surface layer (13) has a thickness between 1 nm and 200 nm.

9. The method according to claim 7 or 8, wherein the formation of the InGaN-based cone (21) and / or the GaN-based wire (24) is carried out by organometallic vapor phase epitaxy (MOVPE).

10. The method according to any one of claims 7 to 9, wherein the openings (120) of the masking layer (12) are spaced apart by a pitch consisting of 50 nm and 700 nm.

11. The opening (120) of the masking layer (12) is 4 μm －２ Above and / or 400 μm －２ The method according to any one of claims 7 to 10, wherein the surface density is distributed to have the following surface density.

12. The method according to any one of claims 7 to 11, wherein the formation of the InGaN-based cone (21) is configured such that the InGaN-based cone (21) has an indium level [In] ≥ 10 at%.

13. The method according to any one of claims 7 to 12, wherein the formation of the InGaN-based cone (21) is carried out at a temperature of 780°C or higher.

14. The method according to any one of claims 7 to 13, wherein the masking layer (12) further comprises a third plurality of openings (120) having a pitch p3 such that p1 < p2 < p3 and Φo1 > Φo2 > Φo3, and a third opening diameter Φo3, in order to simultaneously form a plurality of first, second, and third three-dimensional structures (1) having first, second, and third separation distances ds1, ds2, ds3 between the GaN-based wires (24) such that ds1 < ds2 < ds3 and / or Φ1 > Φ2 > Φ3, and first, second, and third diameters Φ1, Φ2, Φ3 of the GaN-based wires (24), and the plurality of first, second, and third three-dimensional structures (1) are configured to emit light having first, second, and third wavelengths λ1, λ2, λ3, respectively, such that λ1 > λ2 > λ3.

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