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    • 专利摘要:
    The invention relates to a method for manufacturing an optoelectronic device (1) produced on the basis of GaN, comprising an emission structure (10) adapted to emit a first light radiation at the first wavelength (λ1), the process comprising the following steps: i. production of a growth structure (20) comprising a germination layer (23) in Inx2Ga1-X2N at least partially relaxed; ii. production of a conversion structure (30), comprising an emission layer (33) adapted to emit light radiation at a second wavelength (λ2), and an absorption layer (34) produced on the basis of 'InGaN; iii. transfer of the conversion structure (30) to the emission structure (10) so that the absorption layer (34) is located between the emission structure (10) and the emission layer (33) of the conversion structure.
    公开号:FR3075468A1
    申请号:FR1762422
    申请日:2017-12-19
    公开日:2019-06-21
    发明作者:Amelie DUSSAIGNE；Ivan-Christophe Robin
    申请人:Commissariat a lEnergie Atomique CEA；Thales SA；Commissariat a lEnergie Atomique et aux Energies Alternatives CEA；
    IPC主号:
    专利说明:

    METHOD FOR MANUFACTURING AN OPTOELECTRONIC DEVICE BY TRANSFERRING A CONVERSION STRUCTURE ONTO A TRANSMISSION STRUCTURE
    TECHNICAL FIELD [ooi] The field of the invention is that of optoelectronic devices comprising a structure for emitting a first light radiation, for example blue light, and a structure for converting at least part of the first light radiation in at least one second light radiation of longer wavelength, for example green or red light.
    STATE OF THE PRIOR ART Optoelectronic devices are known comprising an emission structure comprising one or more light-emitting diodes, these being generally formed by a stack of semiconductor layers adapted to emit light radiation, for example light blue. The semiconductor layers are usually predominantly made of a semiconductor compound, for example III-V, that is to say comprising elements of column III and of column V of the periodic table, such as a compound III-N, by for example gallium nitride (GaN), indium and gallium nitride (InGaN) or aluminum and gallium nitride (AlGaN).
    To emit a second light radiation in another wavelength, the optoelectronic device may include a conversion structure arranged on the emission structure so as to cover a transmission surface of the latter. The conversion structure can thus be adapted to absorb at least part of the first light radiation coming from the emission structure, and to emit in response a second light radiation in a wavelength greater than that of the first initial light radiation. For example, the conversion structure can absorb blue light emitted by the light-emitting diode (s), and to emit in response to green light.
    Patent application WO2O17 / 001760 describes an example of such an optoelectronic device in which the conversion structure is formed of a photoluminescent layer comprising phosphors, the latter being in the form of powder or grains dispersed in a transparent and optically inert binder matrix. Such phosphors can be chosen from yttrium and aluminum garnet (YAG) and semiconductor nanocrystals forming quantum dots.
    However, there is a need to have a method of manufacturing an optoelectronic device produced based on the same semiconductor compound, so that the emission structure and the conversion structure are both carried out at base of the same semiconductor compound, for example based on gallium nitride or its alloys, the semiconductor compound then having a good crystalline quality.
    One approach may consist in producing the conversion structure by epitaxial growth of a stack of conversion layers based on InGaN, this stack being adapted to ensure the optical conversion of the light emitted by the emission structure. . However, it may be necessary to produce a conversion structure comprising quantum wells in InGaN having a high atomic proportion of indium, for example of the order of approximately 25% in the case of the conversion of blue light into light. green. However, the strong mesh parameter mismatch between GaN and InGaN at 25% indium is likely to cause degradation of the crystal quality of InGaN.
    In addition, the conversion structure can be formed by alternating barrier layers in GaN and layers forming quantum wells in InGaN. The absorption and emission of the light emitted by the underlying light-emitting diode being carried out in the layers of InGaN, it may be necessary to carry out a large number of quantum wells of InGaN to convert a significant part of the light blue emitted. Thus, to convert nearly 80% of blue light, it may be necessary to make at least 20 quantum wells of InGaN each with a thickness of around 3nm. Such a configuration can also lead to a degradation of the crystal quality of the InGaN contained in the conversion structure.
    PRESENTATION OF THE INVENTION The object of the invention is to remedy at least in part the drawbacks of the prior art, and more particularly to propose a method for manufacturing an optoelectronic device based on gallium nitride, comprising an emission structure and a conversion structure exhibiting good crystal quality.
    For this, the object of the invention is a method of manufacturing an optoelectronic device made based on GaN, comprising an emission structure comprising an active area adapted to emit a first light radiation at the first length wave. The process includes the following steps:
    i. production of a growth structure comprising a germination layer of In x2 Gai- X 2N at least partially relaxed;
    ii. production of a conversion structure, by epitaxial growth from the growth structure, comprising an emission layer produced on the basis of InGaN from the germination layer and comprising an active area adapted to emit light radiation at a second wavelength greater than a first wavelength, and an absorption layer produced on the basis of InGaN from the emission layer and adapted to at least partially absorb the first light radiation;
    iii. transfer of the conversion structure to the emission structure so that the absorption layer is located between the emission structure and the emission layer of the conversion structure.
    [Ooio] Some preferred but non-limiting aspects of this manufacturing process are as follows.
    [ooii] The absorption layer can be made of InxôGai-xôN, the atomic proportion of indium x6 being chosen so that the absorption layer has a forbidden unwanted energy Eg (In X 6Gai- X 6N) lower than hc / λι, h being the Boltzmann constant and c the speed of light, λι being the first wavelength.
    [ooi2] The emission layer can form an active zone comprising an alternation of barrier layers in In x4 Gai- X 4N such that x4 is greater than or equal to x2, and at least one emissive layer in InxsGai-xsN forming a quantum well interposed between two barrier layers, the atomic proportion of indium x4 of the barrier layers being chosen so that they have an energy of forbidden bands Eg (Inx 4 Gai-x 4 N) less than hc // λι.
    [ooi3] The active area of the emission structure can include at least one quantum well in In X iGai-xiN, the atomic proportion of indium x4 being greater than or equal to xi and less than X5.
    The active area of the emission structure may include at least one quantum well in In X iGai-xiN, the absorption layer being produced in InxôGai-xôN with an atomic proportion of indium x6 greater than or equal to xi and less than X5.
    The atomic proportion of indium x5 can be between 22% and 30%.
    The germination layer can be produced in In x2 Gai-x2N with an atomic proportion of indium x2 of between 1% and 14%.
    The germination layer can have a mesh parameter equal to its natural value to within 0.75% in compression and to close to 0.15% in tension, and preferably equal to its natural value to ± 0.03% near.
    The emission layer can form an active zone comprising alternating barrier layers in In x4 Gai- x4 N such that x4 is greater than or equal to x2, and at least one emissive layer in Inx 5 Gai-x5N forming a quantum well interposed between two barrier layers, in which step ii of producing the conversion structure comprises producing a buffer layer, produced on the basis of Inx 3 Gai-x3N from the germination layer, configured to allow mesh adaptation between Inx 2 Gai-x2N of the germination layer and In x4 Gai-x 4 N of a barrier layer of the emission layer with which it is intended to be in contact .
    [ooi9] The buffer layer may be formed by alternating layers based on GaN and layers in In X 3'Gai-x 3 'N.
    The layers of In X 3'Gai-x 3 'N may have an atomic proportion of indium X3' greater than or equal to X4.
    The buffer layer can be produced in In x3 Gai-x3N with an atomic proportion of indium X3 which increases between the value x2 at the interface with the germination layer and the value X4 at the interface with the barrier layer of the emission layer in contact with the buffer layer.
    The growth structure can be formed from a stack of a support layer, a tie layer and the germination layer.
    The germination layer can be formed by transfer to the bonding layer of a layer of In x2 Gai-x2N previously epitaxied from a growth substrate, followed by separation of the layer of In x2 Gai -x2N in two parts at the level of a weakened zone following a preliminary ion implantation, the part in contact with the bonding layer forming the germination layer.
    The process may include, after step iii of postponement, the removal of the support layer and the bonding layer of the growth structure.
    BRIEF DESCRIPTION OF THE DRAWINGS Other aspects, aims, advantages and characteristics of the invention will appear better on reading the following detailed description of preferred embodiments thereof, given by way of nonlimiting example, and made with reference to the accompanying drawings in which:
    Figures 1A to 1F are sectional views which schematically illustrate different steps of a method of manufacturing an optoelectronic device according to one embodiment;
    Figures 2A and 2B are sectional views, schematic and partial, of optoelectronic devices obtained by the manufacturing process according to alternative embodiments.
    DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS In the figures and in the following description, the same references represent the same or similar elements. In addition, the different elements are not shown to scale so as to favor the clarity of the figures. Furthermore, the different embodiments and variants are not mutually exclusive and can be combined with one another. Unless otherwise indicated, the terms "substantially", "approximately", "in the order of" mean to within io%. Furthermore, the expression "comprising a" should be understood as "comprising at least one", unless otherwise indicated.
    The invention relates to a method for manufacturing an optoelectronic device 1 comprising:
    an emission structure îo formed by at least one light-emitting diode adapted to emit a first light radiation at a first wavelength λι, for example blue light, and
    a conversion structure 30 adapted to absorb light emitted by the light-emitting diode of the emission structure 10 and to emit in response to at least a second light radiation at a second wavelength λ 2 , the latter then being greater than λι, for example a green or red light.
    In general, light radiation in blue corresponds to a spectrum comprising an intensity peak at a wavelength between 440nm to approximately 4 nm, green at a wavelength between 495nm and 56onm approximately, and red at a wavelength between 6oonm and ôsonm approximately.
    The optoelectronic device 1 is produced based on the same crystalline semiconductor compound, and more precisely based on gallium nitride GaN. In other words, the emission structure 10 and the conversion structure 30 are produced on the basis of GaN, that is to say that they are mainly produced in GaN or in one of its alloys.
    The emission structure 10 can be qualified as active in the sense that it is adapted to emit a first light radiation, for example blue light, as a result of the electrical polarization of the light-emitting diode (s). The conversion structure 30 can be qualified as passive in the sense that it is adapted to emit a second light radiation in response to the absorption of at least part of the first light radiation coming from the emission structure 10. The structure conversion 30 is thus not electrically polarized by means of electrodes.
    Figures 1A to 1F are cross-sectional views schematically illustrating different steps of a method of manufacturing an optoelectronic device 1 according to one embodiment.
    We define here and for the remainder of the description a direct orthogonal three-dimensional coordinate system (Χ, Υ, Ζ), where the axes X and Y form a plane parallel to the main planes along which the emission structure is extended. and the conversion structure 30, and where the axis Z is oriented in a manner substantially orthogonal to the plane XY in a direction of light emission from the optoelectronic device 1.
    FIGS. 1A and 1B illustrate a prior step in producing an emission structure 10 comprising at least one light-emitting diode resting on a control chip 15.
    The emission structure 10 comprises a stack of semiconductor layers 12,13,14 forming one or more light emitting diodes, this stack resting on a control chip 15. A single light emitting diode is shown here.
    Firstly (fig.iA), the stack of semiconductor layers 12, 13, 14 is formed by epitaxial growth forming one or more light-emitting diodes from a growth substrate 11. The growth substrate 11 can be an insulating material, for example sapphire, or a semiconductor material, for example silicon or based on a III-V or II-VL compound It can be a solid substrate (bulk, in English) or a stack of distinct layers such as an SOI substrate (for Silicon-On-Insulator, in English) The light-emitting diode (s) are therefore formed of a stack of semiconductor layers 12, 13, 14 produced on the basis of GaN , that is to say mainly made of GaN or its alloys. It thus comprises a first layer 12 doped with a first conductivity type, for example n-type doped GaN, and a second layer 14 doped with a second conductivity type opposite to the first type, for example doped GaN type p, between which there is an active area 13. The active area 13 is the region of the light-emitting diode from which the first light radiation of wavelength λι is mainly emitted. The face of the first n-doped layer 12, opposite the active area 13, is intended to form a transmission surface 3 through which the first light radiation is emitted. On this face 3 will rest the conversion structure 30. As an illustration, the p-doped layer 14 may have a thickness of between 50 nm and 20 μm and the n-doped layer 12 may have a thickness of between o, ipm and 2θμηι. The p-doped layer 14 may comprise an intermediate electron blocking layer (not shown) located at the interface with the active area 13. The doped layers 12, 14 may have a homogeneous or variable dopant density depending on the thickness of the layers.
    The active area 13 is formed by a stack of barrier layers 13.1 and at least one emissive layer 13.2 forming a quantum well. Preferably, the active area 13 comprises several quantum wells 13.2, each being located between two barrier layers 13.1. The active area 13 is also made based on GaN. Thus, the layers 13.2 forming the quantum wells are preferably made of InxiGai-xiN with an atomic proportion of indium xi of, for example, between 9% and 18% approximately when the first light radiation emitted is blue light, preferably equal to around 16%. They may have a thickness of between mm and about 7 nm. The barrier layers 13.1 can be made of GaN, or even InGaN with an atomic proportion of indium less than xi, and can have a thickness of between mm and 50nm approximately. The layers 13.1, 13.2 of the active area 13 are preferably unintentionally doped. The active area 13 may have a thickness of between about ½ and 500 nm.
    The stacking of the semiconductor layers forming the light-emitting diode (s) can be carried out by conventional epitaxy techniques such as chemical vapor deposition (CVD), for example organometallic (MOCVD, for Metal-Organic Chemical Vapor Déposition), molecular beam epitaxy (MBE, for Molecular Beam Epitaxy), hydride vapor epitaxy (HVPE, for Hybrid Vapor Phase Epitaxy), atomic layer epitaxy (ALE , for Atomic Layer Epitaxy), atomic layer deposition (ALD, for Atomic Layer Deposition), or even by evaporation or sputtering (sputtering).
    The stack of semiconductor layers further comprises electrically conductive portions (not shown) adapted to ensure the electrical polarization of the light-emitting diode (s).
    In a second step (fig.iB), it is possible to carry out the transfer of the stack of semiconductor layers 12, 13, 14 on a control chip 15, followed by the removal of the growth substrate 11. The chip control 15 includes connection elements (not shown) for polarizing the light-emitting diode (s). It may include electronic elements, of the transistor type, ensuring the emission control of the light-emitting diode. Alternatively, it can be a passive component essentially comprising only electrical connection lines extending up to remote electronic elements.
    As described below with reference to FIGS. 2A and 2B, steps for structuring the stack of semiconductor layers 12, 13, 14 can be carried out so as to produce a plurality of light emitting diodes which are distinct from each other. This structuring phase includes steps for depositing dielectric layers and electrically conductive layers, as well as photolithography and etching steps. They can be performed before or after the transfer step on the control chip. The light-emitting diodes may have a structure identical or similar to that described in the publication by Fan et al entitled III-nitride micro-emetter arrays development and applications, J. Phys. D: Appl. Phys., 41 (2008) 094001. Alternatively, and preferably, they can be identical or similar to the structure described in patent application EP2960940.
    This gives an emission structure 10 adapted to emit a first light radiation, having a substantially planar emission face 3, intended to receive the conversion structure 30. The transmission face 3 is here formed by a face of one of the doped layers, here the n-type doped layer 12. As a variant, it may be formed by a face of a layer or an intermediate plate made of a dielectric material, transparent and optically inert with respect to the first light radiation, for example a silicon oxide or nitride, even glass, pyrex or other. The thickness of this intermediate layer may have a thickness of between 500 nm and 50 μm, for example between π and 5 μm.
    FIG. 1C illustrates a step for producing a growth structure 20. This comprises a germination layer 23, or nucleation layer, produced in Inx 2 Gai-x2N at least partially relaxed, that is to say that is, partially relaxed or preferably relaxed. By partially relaxed InGaN is meant that the compound has a mesh parameter equal to its natural value to within 0.75% in compression and to about 0.15% in tension. By relaxed InGaN, it is meant that its mesh parameter is equal to its natural value to within ± 0.03%. The natural value of the mesh parameter is the value when the compound is not subjected to mechanical stresses, in particular in tension or compression. The mesh parameter can be measured by X-ray diffraction by mapping the reciprocal network. For example, for InGaN at 8% indium, the natural mesh parameter is equal to 3.215Â. It is said to be partially relaxed if the mesh parameter is between 3, i9i and 3.22oÂ, and is considered to be relaxed if the mesh parameter is equal to 3.215 to ± o, ooiÂ.
    The germination layer 23 is preferably the upper layer of a stack of separate layers 21, 22, 23. It can thus be a structure called InGaNoS (for InGaN-on-Substrate, in English) formed of a support layer 21, for example a sapphire (AI2O3) or silicon (Si) substrate, a bonding layer 22 in a dielectric material, and the germination layer 23 in Inx 2 Gai-x2N at least partially relaxed and preferably relaxed.
    This growth structure 20 can be obtained by a manufacturing process described in particular in patent application EP2330697. Thus, the epitaxial growth of a layer of Inx 2 Gai-x2N is first of all carried out from a temporary growth substrate, for example a layer of GaN formed on a sapphire substrate. The layer of Inx 2 Gai-x2N may have a thickness less than its critical thickness from which a plastic relaxation of the mechanical stresses takes place, in order to limit the formation of structural defects. The relaxed character of the layer of Inx 2 Gai-x2N can be improved by means of successive anneals. As a variant, the layer of Inx 2 Gai-x2N can be a so-called thick layer insofar as it has a thickness greater than its critical thickness. An implantation of H + ions (Smart Cut ™ technology) is then carried out in the thick layer of Inx 2 Gai-x2N to form a weakened area facilitating transfer to the support layer. Next, the thick layer of Inx 2 Gai-x2N is joined to a bonding layer 22 made of a dielectric material, for example a silicon oxide or nitride, previously deposited on the support layer 21, the latter being able to be a sapphire substrate. The growth substrate is removed and the thick layer of Inx 2 Gai-x2N is finally separated into two parts at the level of the zone weakened by the implantation of H + ions. A growth structure is thus obtained formed of a stack comprising the support layer 21, the bonding layer 22 and the germination layer 23 in At x2 GaN at least partially relaxed. This can have a thickness, for example, of between 5nm and 5oonm. Due to its partially relaxed and preferably relaxed structure, it has a particularly low density of structural defects such as dislocations of mesh detuning. In the case of the conversion of blue light into green light, the atomic proportion of indium x2 can be between 1% and 14%, and preferably between 1% and 8%.
    FIG. 1D illustrates a step of producing the conversion structure 30, by epitaxial growth from the growth structure 20. The epitaxial growth can be implemented by one of the techniques mentioned above.
    The conversion structure 30 comprises a stack of semiconductor layers 32, 33, 34 made on the basis of GaN, and more precisely based on InGaN, namely an optional but advantageous buffer layer 32, an emission layer 33 , and an absorption layer 34.
    Firstly, the buffer layer 32 (buffer) is formed, by epitaxy from the germination layer 23 in In x2 Gai-x 2 N. This buffer layer 32 is configured to allow adaptation of the mesh parameter between the germination layer 23 and the emission layer 33, and more precisely with a first barrier layer 33.1 made of Inx 4 Gai-x 4 N with which it is in contact. This buffer layer 32 can be omitted in the case where the germination layer 23 in In x2 Gai-x 2 N and the first barrier layer 33.1 in Inx 4 Gai-x 4 N have the same value of atomic proportion of indium x2 = x4, which results in the same mesh parameter value. It is preferably present when these layers have different mesh parameters, in particular when x2 is less than X4. By way of example, the germination layer 23 can be produced in In x2 Gai-x 2 N with x2 = approximately 8% and the first barrier layer 33.1 in In x4 Gai-x4N with χ4 = ιγ% approximately. In this case, the mesh adaptation buffer layer 32 is advantageously produced.
    The buffer layer 32 is produced based on Inx 3 Gai-x3N with an atomic proportion of indium X3, this value can be constant or variable depending on the thickness of the layer. It can thus be locally understood, depending on the thickness of the layer, between approximately x2 and x4. It can have a thickness of between 5 nm and 11 µm.
    According to a variant, it can thus be produced in In x3 Gai-x3N with an atomic proportion of indium x3 which varies according to its thickness, and more precisely which increases between a low value equal to the atomic proportion of indium x2 at the interface with the germination layer 23 in In x2 Gai-x2N, and a high value equal to the atomic proportion of indium X4 at the interface with the first barrier layer 33.1 in In x4 Gai-x4N of the layer d 'emission 33. It may have a thickness of between 5 nm and 11 µm. In the case of the conversion of blue light into green light, it can thus have an atomic proportion of indium X3 varying continuously between 8% of Inx2Gai-x 2 N and 17% of 1 In x4 Gai-x4N.
    According to another variant (not shown), the buffer layer 32 can be formed of a stack of semiconductor layers in which alternate thin layers of (Al, Ga) N and layers of In x3 Gai-x3N. The atomic proportion of indium X3 can be equal to the value X4 at the interface with rin x4 Gai-x4N of the first barrier layer 33.1, for example 17% in the case of the conversion of blue light into red light. The atomic proportion of indium X3 can be identical for all the layers of In x3 Gai-x3N, or can vary according to the thickness between a low value equal to approximately x2 and a high value equal to approximately x4, as mentioned previously. The layers of (Al, Ga) N can have a thickness between o.25nm and sonm, preferably equal to 2nm, and the layers of In X 3Gai-x 3 N can have a thickness between 2.5nm and ioonm, for example equal to 2onm. The buffer layer 32 can have a total thickness of between 11 µm and 11 µm, for example equal to soonm.
    According to another variant (not shown), the buffer layer 32 can have a superlattice structure and be formed of a stack of semiconductor layers in which alternate layers of In x3 Gai-x3'N and layers based on (Ga, In) N, the atomic proportion X3 ′ being adapted so that the buffer layer 32 corresponds to an equivalent layer produced in Inx3Gai-x 3 N with an average atomic proportion of indium X3 equal to approximately x4. The layers of Inx3'Gai-x3'N preferably have an atomic proportion of indium X3 'which can be identical for all the layers of Inx3'Gai-x3'N. The layers based on (Ga, In) N, can be produced in GaN or InGaN with an atomic proportion of indium lower than that of rinx3'Gai-x 3 'N and have a thickness of the order of o. 25nm to îonm, preferably equal to 2nm. The Inx3'Gai-x 3 'N layers preferably have a thickness of the same value or even less than that of the GaN layers, for example equal to half. Thus, the layers of InxyGai-xyN may have a high concentration of indium, but their thin thickness makes it possible to avoid plastic relaxation, which can form structural defects. For example, the GaN and Inx ^ Gai-x ^ N layers have the same thickness, for example equal to 2nm, and the atomic proportion of indium X3 'is equal to twice x4, so that obtain a buffer layer 32 corresponding to an equivalent layer produced in In x3 Gai- x3 N with x3 = x4.
    In a second step, the emission layer 33 is produced by epitaxy from the buffer layer 32 when it is present, or from the germination layer 23 if necessary. The emission layer 33 forms the active area of the conversion structure 30 in the sense that it corresponds to the region from which the second light radiation is mainly emitted in response to the absorption of the first light radiation. It is formed by a stack of barrier layers 33.1 in Inx 4 Gai-x 4 N and at least one emissive layer 33.2 forming a quantum well in InxsGai-xsN. Preferably, it comprises several quantum wells 33.2, each being located between two barrier layers 33.1. The layers 33.1, 33.2 of the active area 33 are preferably unintentionally doped.
    The barrier layers 33.1 are made of Inx 4 Gai-x 4 N with an atomic proportion of indium X4 less than X5. Preferably, the atomic proportion of indium X4 is chosen so that the barrier layers 33.1 have a band energy Eg (Inx 4 Gai-x 4 N) less than hc / λι, thus also making it possible to absorb at least part of the first light radiation. It can thus, in the case of the conversion of blue light into green light, be greater than or equal to the atomic proportion xi of the emissive layers 13.2 of the emission structure 10, for example be equal to approximately 17%, all by being less than the atomic proportion of indium X5 of the InxsGai-xsN of the quantum wells 33.2 of the emission layer 33. They may have a thickness of between mm and 50nm approximately. A first barrier layer 33.1 is in contact with the buffer layer 32 when it is present, or if appropriate with the germination layer 23 · The quantum wells 33.2 are produced in InxsGai-xsN with an atomic proportion of indium X5 comprised, for example, between 22% and 30% approximately when the second light radiation emitted is green light, and preferably equal to approximately 25%. It can be between 30% and 40% approximately for an emission in the red, for example being equal to approximately 35%. The layers 33.2 forming the quantum wells can have a thickness of between mm and 8 nm approximately.
    In a third step, the absorption layer 34 is produced by epitaxy from the emission layer 33, and more precisely from a last barrier layer 33.1 situated on the side opposite to the first barrier layer 33.1 which is in contact with the buffer layer 32. It is intended to allow the absorption of at least part of the first light radiation emitted by the emission structure 10. During absorption in the absorption layer 34, an electron-hole pair is formed and these charge carriers can then recombine in a radiative manner in a quantum well of the emission layer 33. The absorption layer 34 is made based on GaN and more precisely is made in InxôGai -xôN with an atomic proportion of indium x6 preferably homogeneous within the layer. It has a thickness of between Ionm and Iopm, and preferably greater than Ioonm to help effectively absorb the first light radiation. In the case of the conversion of blue light into green light, the absorption layer 34 has an atomic proportion of indium x6 chosen so that it has a band gap energy Eg (In X 6Gai-x6N) less than hc / λι, thus making it possible to absorb at least partially the blue light emitted by the emission structure 10. It can thus be greater than or equal to the atomic proportion xi of the emissive layers 13.2 of the emission structure 10, by example be equal to 17% and be less than the atomic proportion of indium X5 of the InxsGai-xsN of the quantum wells 33.2 of the emission layer 33.
    This gives an emission structure 30 made mainly of InGaN, comprising an emission layer 33 and an absorption layer 34, and if necessary a buffer layer 32 in contact with the face of the layer of emission 33 opposite to the absorption layer 34. The barrier layers 33.1 of the emission layer 33 are advantageously adapted to absorb at least part of the first light radiation.
    FIG. 1E illustrates a step of transferring the conversion structure 30 to the transmission structure 10. More specifically, the conversion structure 30 is assembled to the transmission structure 10 so that the free face of the absorption layer 34 is fixed to the transmission face 3 of the emission structure 10. The free face 3 of the emission structure 10 can be that of the doped layer (as shown in fig.iE) or that an intermediate layer (not shown). Thus, the absorption layer 34 is located between the emission structure 10 on the one hand, and the emission layer 33 on the other hand. This step can be carried out by one of the conventional transfer and assembly techniques, for example by bonding the two structures 10, 30 using an epoxy adhesive, the latter being transparent to the first light radiation and advantageously electrically insulating. Other techniques are possible, such as direct bonding, among others.
    Figure 1F illustrates a step of removing the support layer 21 and the bonding layer 22 of the growth structure 20. This removal step can be performed by grinding and / or etching, or even by means of a laser by a laser lift-off type process. The germination layer 23 in Inx 2 Gai-x2N at least partially relaxed can be kept (as shown in fig.iF) or deleted.
    Thus, the manufacturing process makes it possible to obtain an optoelectronic device 1 based on the same semiconductor compound, namely here in gallium nitride and its alloys, more specifically comprising an emission structure 10 mainly made of GaN and a conversion structure 30 carried out mainly in InGaN. This optoelectronic device 1 therefore allows the emission of at least one second light radiation of wavelength λ 2 , for example green or red light, in response to the absorption of a first excitation light radiation more short wavelength λι, for example blue light.
    The conversion structure 30 based on InGaN can thus include quantum wells 33.2 with a high atomic proportion of indium, thus allowing conversion into green or red, while exhibiting good crystalline quality.
    These structural characteristics are possible by the use of a germination layer 23 of at least partially relaxed InGaN, here preferably obtained by InGaNoS technology (for InGaN-on-Substrate, in English). Indeed, it appears that a germination layer 23 of at least partially relaxed InGaN makes it possible to incorporate more indium in the epitaxial layers 32, 33, 34 based on InGaN while minimizing the presence of structural defects such as mesh disagreement dislocations. The optical properties of the optoelectronic device 1 are thus improved.
    It is then possible to improve the conversion rate, that is to say the number of photons emitted from the second light radiation by number of photons emitted from the first light radiation, by producing quantum wells 33.2 of the structure conversion 30 with good internal quantum efficiency, and in particular barrier layers 33.1 which also make it possible to absorb the first light radiation, in addition to the absorption layer 34.
    For example, in the case of a conversion of blue light into green light, the optoelectronic device 1 emits towards the conversion structure 30 blue light at the emissive layers 13.2 into InxiGaixiN with xi equal to around 15%. The conversion structure 30 absorbs at least part of the blue light, in the absorption layer 34 made of InxôGai-xôN with x6 equal to approximately 17% (xi <x6 <x5), and preferably also in the barrier layers 33.1 produced in Inx 4 Gai-x 4 N with x4 equal to around 17% (xi <x4 <x5), and emits in response a second light radiation of longer wavelength, here green light, at the layers 33.2 emissives produced in Inx 5 Gai-x5N with X5 equal to approximately 25%.
    In the embodiment described above, the absorption layer 34 and the buffer layer 32 are separate from the first and last barrier layers 33.1 of the emission layer 33. However, as a variant, they can be confused with these latest.
    Furthermore, the emission structure 10 can be formed from a stack of continuous semiconductor layers (as shown in fig.iA-iF). As a variant, it may include a plurality of light-emitting diodes which are distinct from each other. In addition, the conversion structure 30 can be in the form of a stack of continuous semiconductor layers extending opposite the emission structure îo. As a variant, it may be in the form of a plurality of pads which are distinct from each other, the pads being formed by localized etching of the initial stack of the semiconductor layers 32, 33, 34. Each conversion pad can be extend next to one or more light emitting diodes.
    As such, Figure 2A is a sectional view which schematically illustrates an optoelectronic device 1 obtained according to another embodiment of the manufacturing process. The emission structure 10 here comprises several light-emitting diodes 2 which can be connected to each other in parallel or in series. The conversion structure 30 comprises several conversion pads 35, obtained from the same stack of semiconductor layers 32, 33, 34, each arranged opposite a light-emitting diode 2. Thus, the optoelectronic device comprises a matrix of light pixels, each light pixel here comprising a single light-emitting diode 2 surmounted or not by a conversion pad 35, the pixels being able to be activated independently of one another. In this example, three pixels are represented, a blue pixel Pb not comprising a conversion pad 35 and two red pixels Pr each comprising a conversion pad 35.
    The light-emitting diodes 2 are each formed of a stack of a first doped portion 12, here of the n type, and of a second doped portion 14, here of the p type, between which is an active area 13. They form mesa structures that are substantially coplanar with each other. This structure of light-emitting diodes is similar or identical to that described in document EP2960940. By mesa structure is meant a structure formed by a stack of semiconductor portions projecting above a growth substrate 11 (cf. fig.iA) following an etching step. The mesa structures are substantially coplanar in the sense that the first doped portions 12 of the light-emitting diodes are respectively coplanar. It is the same for the active zones 13 and the second doped portions 14.
    Each light-emitting diode 2 has a first doped portion 12 of which a surface 3 opposite the active area 13 is a surface through which the light radiation from the diode is emitted. The lateral flanks of the doped first portion 12 and of the doped second portion 14, as well as those of the active area 13, are covered with a dielectric layer 41, with the exception of a detachment surface 42 of the first portion 12 doped.
    The light emitting diodes 2 are separated from each other by lateral elements 43 of electrical connection which extend along the axis Z between the diodes. Each light-emitting diode 2 is thus associated with a lateral connection element 43 which comes into electrical contact with the detachment surface 42 of the first doped portion 12, making it possible to apply a determined electrical potential to the latter. This lateral connection element 43 is however electrically isolated from the adjacent diodes 2 by the dielectric layers 41 thereof.
    The emission structure 10 comprises in this example a layer 45 of electrical connection, which participates in forming a support layer, the layer 45 allowing electrical contact between the control chip 15 on the one hand, and the lateral elements 43 of electrical connection and portions 44 of electrical connection located in contact with the second doped portions 14. The connection layer 45 thus comprises connection pads 46 electrically insulated from each other by a dielectric material. Thus, the control chip 15 can apply an electrical potential to one and / or the other of the light-emitting diodes 2, and thus activate them independently of each other.
    An intermediate layer 47, made of a dielectric material transparent to the first light radiation, here covers the upper face of the first doped portions 12 as well as the lateral connection elements 43. It can optionally also include a planarization layer. It can be made of a silicon oxide or nitride (S1O2, Si 3 N 4 , SiON ...). The face 3 of the intermediate layer 47 opposite the light-emitting diodes 2 forms the transmission surface 3 of the emission structure 10. As a variant, the intermediate layer 47 can be an added transparent plate, made of glass, for example borosilicate glass , in pyrex, sapphire or other. The transparent plate can be assembled by gluing.
    In this example, the conversion structure 30 is formed of conversion pads 35 obtained by localized etching of the stack of semiconductor layers 32, 33, 34 (cf. fig.iD), this stack having been assembled at the transmission surface 3 of the transmission structure 10 (cf. fig.iE). The etching can be a dry etching, for example a plasma etching (RIE, ICP ...).
    Figure 2B is a sectional view which schematically illustrates an optoelectronic device 1 obtained according to another embodiment of the manufacturing process.
    This optoelectronic device 1 differs from that of FIG. 2A in particular in that the emission structure 10 comprises light-emitting diodes 2 without the detachment surface 35 and which can be connected in parallel with one another. It thus comprises a layer 47 doped with the same type of conductivity as that of the first portions 12, and preferably overdoped, for example n +, extending continuously to contact each of the first portions 12 doped n. Thus, the first doped portions 12 can be electrically polarized via the overdoped layer 47, and the second doped portions 14 can be electrically via the electrical connection portions 44.
    This optoelectronic device 1 differs from that of FIG. 2A also in that the conversion structure 30 comprises first conversion pads 35 adapted to convert at least part of the first light radiation into a second light radiation, for example into green light, and second conversion pads 36 adapted to converting at least part of the second light radiation into a third light radiation, for example into red light. The first conversion pads 35 rest on the transmission surface 3 of the transmission structure 10, and the second conversion pads 36 rest on the opposite face of the first conversion pads 35. Each of the first pads 35 and of the second pads 36 may extend opposite one or more light-emitting diodes 2. The second conversion pads 36 have a surface, in the XY plane, less than or equal to that of the first pads 35 of conversion on which they are based. The optoelectronic device 1 can thus comprise different types of conversion pads 35, 36 ... adapted to convert the incident light into light of longer wavelength.
    Particular embodiments have just been described. Different variants and modifications will appear to those skilled in the art, in particular depending on the intended applications.
    权利要求:
    Claims (15)
    [1" id="c-fr-0001]
    1. Method for manufacturing an optoelectronic device (i) made from GaN, comprising:
    o an emission structure (îo) comprising an active area (13) adapted to emit a first light radiation at a first wavelength (λι), the method comprising the following steps:
    1. creation of a growth structure (20) comprising:
    o a germination layer (23) of In X 2Gai- X 2N at least partially relaxed, X2 being the atomic proportion of indium;
    ii. production of a conversion structure (30), by epitaxial growth from the growth structure (20), comprising:
    o an emission layer (33), produced from InGaN from the germination layer (23), comprising an active area (33) adapted to emit light radiation at a second wavelength (λ 2) greater than the first wavelength (λι), and o an absorption layer (34), produced on the basis of InGaN from the emission layer (33), adapted to at least partially absorb the first radiation luminous ;
    III. transfer of the conversion structure (30) to the emission structure (10) so that the absorption layer (34) is located between the emission structure (10) and the emission layer (33) of the conversion structure (30).
    [2" id="c-fr-0002]
    2. Method according to claim 1, in which the absorption layer (34) is made of In X ôGai- X 6N, the atomic proportion of indium x6 being chosen so that the absorption layer (34) has an energy forbidden bands Eg (In X 6Gai- X ôN) less than hc / λι, h being the Boltzmann constant and c the speed of light, and λι being the first wavelength.
    [3" id="c-fr-0003]
    3. Method according to claim 1 or 2, wherein the emission layer (33) forms an active area comprising an alternation of barrier layers (33.1) in In X 4Gai- x4 N such that the atomic proportion of indium x4 is greater than or equal to the atomic proportion of indium X2, and at least one emissive layer (33.2) in
    InxsGai-xsN of atomic proportion of indium χβ forming a quantum well interposed between two barrier layers (33.1), the atomic proportion of indium X4 of the barrier layers (33.1) being chosen so that they have an energy of forbidden bands Eg ( In X 4Gai-x4N) less than hc / λι.
    [4" id="c-fr-0004]
    4. Method according to claim 3, in which the active zone (13) of the emission structure (10) comprises at least one quantum well (13.2) in In X iGai- X iN, the atomic proportion of indium X4 being greater than or equal to the atomic proportion of indium xi and less than the atomic proportion of indium X5.
    [5" id="c-fr-0005]
    5. Method according to claim 3 or 4, wherein the active area (13) of the emission structure (10) comprises at least one quantum well (13.2) in InxiGai-xiN, the absorption layer (34) being produced in InxôGai-xôN with an atomic proportion of indium x6 greater than or equal to the atomic proportion of indium xi and less than the atomic proportion of indium X5.
    [6" id="c-fr-0006]
    6. Method according to any one of claims 3 to 5, wherein the atomic proportion of indium X5 is between 22% and 30%.
    [7" id="c-fr-0007]
    7. Method according to any one of claims 1 to 6, wherein the germination layer (23) is made of In x2 Gai- X 2N with an atomic proportion of indium X2 of between 1% and 14%.
    [8" id="c-fr-0008]
    8. Method according to any one of claims 1 to 7, in which the germination layer (23) has a mesh parameter equal to its natural value to within 0.75% in compression and to 0.15% in tension , and preferably equal to its natural value to within ± 0.03%.
    [9" id="c-fr-0009]
    9. Method according to any one of claims 1 to 8, in which the emission layer (33) forms an active zone comprising an alternation of barrier layers (33.1) in Inx4Gai- X 4N such as the atomic proportion of indium. X4 is greater than or equal to the atomic proportion of indium X2, and at least one emissive layer (33.2) in In X5 Gai-x 5 N forming a quantum well interposed between two barrier layers (33.1), in which the step ii of producing the conversion structure (30) includes carrying out:
    o a buffer layer (32), produced from Inx 3 Gai- x3 N from the germination layer (23), configured to allow a mesh adaptation between the InxaGai-xaN of the germination layer (23 ) and the Inx4Gai-x4N of a barrier layer (33.1) of the emission layer (33) with which it is intended to be in contact.
    [10" id="c-fr-0010]
    10. The method of claim 9, wherein the buffer layer (32) is formed of alternating GaN-based layers and layers of Inx 3 Gai-x 3 N of atomic proportion of indium X3 '.
    [11" id="c-fr-0011]
    11. The method of claim 10, wherein the layers in In x3 'Gai-x 3 N have an atomic proportion of indium X3' greater than or equal to the atomic proportion of indium X4.
    [12" id="c-fr-0012]
    12. The method of claim 9, wherein the buffer layer (32) is made of In x3 Gai- x3 N with an atomic proportion of indium x3 which increases between the value x2 at the interface with the germination layer (23 ) and the value X4 at the interface with the barrier layer (33.1) of the emission layer (33) in contact with the buffer layer (32).
    [13" id="c-fr-0013]
    13. Method according to any one of claims 1 to 12, in which the growth structure (20) is formed by a stack of a support layer (21), a tie layer (22) and the germination layer (23).
    [14" id="c-fr-0014]
    14. The method of claim 13, wherein the germination layer (23) is formed by transfer to the bonding layer (22) of a layer of In X 2Gai- X 2N previously epitaxied from a growth substrate , followed by separation of the layer of Inx2Gai-x 2 N into two parts at the level of a weakened zone following a prior ion implantation, the part in contact with the bonding layer (22) forming the germination layer ( 23).
    [15" id="c-fr-0015]
    15. Method according to any one of claims 1 to 14, comprising, after step iii of postponement, the removal of the support layer (21) and the bonding layer (22) of the growth structure (20).
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    同族专利:
    公开号 | 公开日
    EP3503222B1|2020-08-12|
    US20190189835A1|2019-06-20|
    US10886429B2|2021-01-05|
    CN110010744A|2019-07-12|
    EP3503222A1|2019-06-26|
    FR3075468B1|2019-12-20|
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    法律状态:
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    2019-06-21| PLSC| Search report ready|Effective date: 20190621 |
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    优先权:
    申请号 | 申请日 | 专利标题
    FR1762422|2017-12-19|
    FR1762422A|FR3075468B1|2017-12-19|2017-12-19|METHOD FOR MANUFACTURING AN OPTOELECTRONIC DEVICE BY TRANSFERRING A CONVERSION STRUCTURE ONTO A TRANSMISSION STRUCTURE|FR1762422A| FR3075468B1|2017-12-19|2017-12-19|METHOD FOR MANUFACTURING AN OPTOELECTRONIC DEVICE BY TRANSFERRING A CONVERSION STRUCTURE ONTO A TRANSMISSION STRUCTURE|
    EP18213127.6A| EP3503222B1|2017-12-19|2018-12-17|Method for manufacturing an optoelectronic device by transferring a conversion structure onto an emission structure|
    US16/223,806| US10886429B2|2017-12-19|2018-12-18|Method of manufacturing an optoelectronic device by transferring a conversion structure onto an emission structure|
    CN201811555727.0A| CN110010744A|2017-12-19|2018-12-19|By the manufacturing method for adding the optoelectronic device of transformational structure on emitting structural|
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