LIGHT-EMITTING COMPONENT AND METHOD FOR PRODUCING A LIGHT-EMITTING COMPONENT

Abstract

Light-emitting component (100), comprising a light-emitting semiconductor chip (1) with a semiconductor layer sequence (10) comprising at least one light-emitting semiconductor layer (11) and a light coupling-out surface (13), a wavelength conversion layer (2) arranged on the light-outcoupling surface, wherein the wavelength conversion layer comprises quantum dots (20), wherein a surface structure (15) is provided on the light-outcoupling surface and the wavelength conversion layer is deposited directly on the surface structure, wherein the wavelength conversion layer is a conformal coating of the surface structure, and wherein the wavelength conversion layer is free of a matrix material.

Description

[0001] Embodiments of the present invention relate to a light-emitting component and a method for producing a light-emitting component. In particular, the light-emitting component can have a wavelength conversion layer. The wavelength conversion layer can preferably comprise or consist essentially of quantum dots (QDs).

[0002] Quantum dots are narrowband emitters used for wavelength conversion. They can offer advantages in terms of color quality and conversion efficiency, for example, in backlighting and solid-state lighting (SSL) applications. Quantum dots are suitable for such applications because they not only provide specific optical properties but also offer the potential for cost-effective manufacturing. QDs have a broad absorption spectrum in a wavelength range that typically extends from ultraviolet wavelengths to the first excitonic peak. They are non-scattering and efficient. The peak emission wavelength of QDs can be tuned within a few nanometers.

[0003] Today's colloidal QDs in dispersions typically exhibit high efficiencies of typically more than 80% or even more than 90% in large volumes in nonpolar solvents, and between approximately 70% and 80% in optimized polymer composites. In colloidal dispersions, the QDs are typically coated with organic ligands that passivate the surface, prevent agglomeration, and enable their miscibility with host materials. However, the nature of these ligands influences the feasibility of fabricating QD composites as well as their performance in applications. Currently, QD / polymer composites are used in backlighting and SSL applications as color-correcting films. The properties of QD / polymer composites are satisfactory for such applications where the operating temperature does not exceed 100°C.For applications where the converter can reach temperatures above 100°C, other forms of QD films must be manufactured. State-of-the-art QD compositions and host materials with higher thermal conductivity and thermal stability are used.

[0004] Typically, optical components containing QDs are manufactured as freestanding parts with an application-specific form factor. They can include QDs combined with polymers, hybrid organic / inorganic substances, and even dense composites on a supporting substrate. To prevent degradation of the QD properties in the ambient atmosphere, these components must be encapsulated. Challenges for the design and fabrication of QD converters intended to operate at elevated temperatures arise from the need to eliminate organic host materials. In such cases, freestanding QD composites in the form of densely packed films or composites of QDs with inorganic fillers may be applicable. However, the freestanding QD parts must be connected to the light source in a housing, which, in conjunction with mass production, increases the complexity of the process and increases costs.

[0005] The document US 2016 / 0 095 184 A1 describes a light-emitting component.

[0006] The document US 2014 / 0 233 212 A1 describes an optical element, a display device and a light-emitting device therewith.

[0007] An object of at least one embodiment is to provide a light-emitting component. A further object of at least one embodiment is to provide a method for producing a light-emitting component.

[0008] These objects are achieved, among others, with a component and a method according to the independent claims. Further embodiments and configurations are the subject of the dependent claims.

[0009] A light-emitting device comprises a light-emitting semiconductor chip and a wavelength conversion layer.

[0010] In a method for producing a light-emitting component, a light-emitting semiconductor chip is provided or produced, and a wavelength conversion layer is arranged on the light-emitting semiconductor chip.

[0011] The features and embodiments described herein relate to both the light-emitting component and the method for producing the light-emitting component.

[0012] The light-emitting semiconductor chip has a semiconductor layer sequence. The semiconductor layer sequence comprises at least one light-emitting semiconductor layer. The at least one light-emitting semiconductor layer forms an active region for generating light, so that, during operation of the light-emitting semiconductor chip, light is generated in the light-emitting semiconductor layer. The light-emitting semiconductor chip further comprises a light-outcoupling surface, via which the light generated in the active region is coupled out of the light-emitting semiconductor chip. The wavelength conversion layer is preferably arranged on the light-outcoupling surface.

[0013] The semiconductor layer sequence can particularly preferably be grown on a substrate, which can be referred to as a growth substrate, using an epitaxial process, for example, using metal-organic vapor phase epitaxy (MOVPE) or molecular beam epitaxy (MBE). The semiconductor layer sequence therefore comprises semiconductor layers arranged one above the other along an arrangement direction determined by the growth direction, which can also be referred to as the vertical direction. The layers of the semiconductor layer sequence have a main plane of extension that is perpendicular to the arrangement direction. Directions that run parallel to the main plane of extension of the semiconductor layers and thus perpendicular to the vertical direction can be referred to as lateral directions.

[0014] The light-emitting semiconductor chip comprises, in particular, two main surfaces arranged perpendicular to the growth direction. One of the main surfaces is designed as a light-outcoupling surface, via which the light generated during operation of the light-emitting semiconductor chip is emitted. In addition, the light-emitting semiconductor chip comprises a rear surface located on the side opposite the light-outcoupling surface and forming the second main surface of the light-emitting semiconductor chip. The light-outcoupling surface and the rear surface are connected to one another via side surfaces. In addition to the light emitted by the light-outcoupling surface, at least part of the light generated in the light-emitting semiconductor layer during operation can also be emitted via a side surface and / or the rear surface.

[0015] Depending on the light to be generated, the light-emitting semiconductor chip can have a semiconductor layer sequence based on different semiconductor material systems. A semiconductor layer sequence based on In x Ga y Al 1-x-y For example, As is suitable for long-wave infrared to red radiation, a semiconductor layer sequence based on In x Ga y Al 1-x-y P is suitable for red to yellow radiation, for example, and a semiconductor layer sequence based on In x Ga y Al 1-x-y N is suitable, for example, for short-wave visible radiation, ie in particular for green to blue radiation, and / or for UV radiation, where 0 ≥ x ≥ 1 and 0 ≥ y ≥ 1. In addition, a semiconductor layer sequence based on an antimonide, for example InSb, GaSb, AlSb or a combination thereof, may be suitable for long-wave infrared radiation.

[0016] The substrate, particularly in the case of a growth substrate, may comprise or be an insulating material or a semiconductor material, for example, a compound semiconductor material system mentioned above. In particular, the growth substrate may comprise or be made of sapphire, GaAs, GaP, GaN, InP, SiC, Si, and / or Ge.

[0017] The growth process can be carried out, in particular, using a wafer-based process. In other words, a growth substrate in the form of a wafer is provided, on which the semiconductor layer sequence is grown over a large area. The grown semiconductor layer sequence can be singulated into individual light-emitting semiconductor chips in a further process step, in which the side surfaces of the light-emitting semiconductor chips can be formed by singulation. The wavelength conversion layer can preferably be applied before singulation. In other words, the wavelength conversion layer can also be applied using a wafer-based process. Alternatively, the wavelength conversion layer can also be applied to an already singulated light-emitting semiconductor chip.

[0018] Additionally, the semiconductor layer sequence can be transferred to a carrier substrate prior to dicing, and the growth substrate can be thinned, i.e., at least partially or completely removed. The carrier substrate can comprise or be made of an electrically insulating or electrically conductive material, for example, a substrate material described above.

[0019] The semiconductor layer sequence of the light-emitting semiconductor chip can, for example, comprise a conventional pn junction, a double heterostructure, a single quantum well structure (SQW structure), or a multi-quantum well structure (MQW structure) as the light-emitting semiconductor layer. In addition to the at least one light-emitting semiconductor layer, the semiconductor layer sequence can comprise further functional layers and functional regions, for example, p- and n-type charge carrier transport layers, undoped or p- or n-conducting confinement, cladding, or waveguide layers, barrier layers, planarization layers, buffer layers, protective layers, and / or electrodes, as well as combinations thereof.In particular, the light-emitting semiconductor chip can comprise an electrical contact element for electrical contacting on the light-output surface and on the rear surface, for example in the form of a large-area or small-area electrode layer, or which can be a structured electrode layer. It is also possible for all electrical contacts to be provided on one side of the light-emitting semiconductor chip, for example, on the light-output surface or on the rear surface.In particular, the light-emitting semiconductor chip can be designed as a so-called volume emitter or as a flip chip, in both cases preferably comprising a semiconductor layer sequence grown on a sapphire substrate, or as a so-called thin-film semiconductor chip, preferably comprising a carrier substrate to which the semiconductor layer sequence was transferred according to the method and preferably further with a thinned or even completely removed growth substrate.

[0020] The structures described here relating to the light-emitting semiconductor chip as well as the light-emitting semiconductor layer and the further functional layers and regions, in particular their structure, function and construction, are known to the person skilled in the art and are therefore not described in more detail here.

[0021] The wavelength conversion layer comprises quantum dots (QDs). As described above, the QDs provide advantages in color performance, particularly narrowband emission with a finely tunable peak position, a broad absorption spectrum, and no inherent scattering.

[0022] According to a further embodiment, the wavelength conversion layer is free of an organic matrix material. In particular, the wavelength conversion layer can consist essentially of the quantum dots. In other words, the wavelength conversion layer is not formed as a composite comprising a matrix material or filler material such as a polymer or other organic materials typically used in the prior art. In contrast, the wavelength conversion layer of the light-emitting component is preferably formed as a composite of the QDs deposited on a surface of the light-emitting semiconductor chip, so that the wavelength conversion layer is formed by the deposition process.The wavelength conversion layer is therefore not a freestanding component as commonly used in the prior art, but rather a part of the light-emitting component that is integrated into the light-emitting component and cannot be removed without being destroyed. In particular, the QDs are arranged next to one another and / or one above the other by the deposition process, thus forming the wavelength conversion layer. The wavelength conversion layer can preferably be deposited by at least one process selected from drop casting, inkjet printing, and layer transfer. Furthermore, the wavelength conversion layer can be deposited directly on a surface of the light-emitting semiconductor chip, in particular directly on the light-outcoupling surface, so that at least some of the QDs of the wavelength conversion layer can be in direct contact with the light-outcoupling surface of the light-emitting semiconductor chip.

[0023] Furthermore, an intermediate layer can be arranged on a surface of the light-emitting semiconductor chip, in particular on the light-outcoupling surface and preferably directly on the light-outcoupling surface, and the wavelength conversion layer can be deposited on the intermediate layer, in particular directly on the intermediate layer. The intermediate layer can comprise or consist of a transparent material and / or a wavelength conversion material. The wavelength conversion material, which can differ from the QDs, can be suitable for converting at least part of the light emitted by the light-emitting semiconductor chip into light of a different wavelength.When irradiated with the light from the light-emitting semiconductor chip, the wavelength conversion material of the intermediate layer can preferably emit light with a wavelength that differs from the wavelength of the light emitted by the wavelength conversion layer. In particular, the intermediate layer can comprise a ceramic wavelength conversion material, which can be provided, for example, as a ceramic layer or as particles dispersed in a matrix material. The wavelength conversion material of the intermediate layer can comprise, for example, a material from the group of garnets, for example yttrium aluminum garnet (YAG) and / or lutetium aluminum garnet (LuAG), and in particular doped garnets such as Ce-doped garnets.By combining the light-emitting semiconductor chip, the wavelength conversion layer containing the QDs, and the intermediate layer containing the wavelength conversion material, the light-emitting component can be, for example, a white-light emitting component with an integrated QD layer. The intermediate layer, which preferably comprises or consists of a wavelength conversion material, can be deposited on the light-outcoupling surface, in particular using a pulsed laser deposition (PLD) process.

[0024] A surface structure is provided on the light-outcoupling surface, and the wavelength conversion layer is applied directly to the surface structure. The surface structure can comprise depressions such as pits and / or gaps and / or furrows, as well as elevations such as domes and / or peaks and / or dam-like structures. Preferably, the light-outcoupling surface can be provided with the surface structure. In this case, the wavelength conversion layer is deposited directly on the surface structure of the light-outcoupling surface. In the case of an intermediate layer, preferably an intermediate layer that comprises or consists of a wavelength conversion material, the intermediate layer has a surface facing away from the light-outcoupling surface, which surface can have the surface structure. In this case, the wavelength conversion layer is applied directly to the surface structure of the intermediate layer.

[0025] The wavelength conversion layer is a conformal coating of the surface structure. In other words, the wavelength conversion layer can cover the surface structure in such a way that the structure of the wavelength conversion layer on the side facing away from the surface structure at least partially resembles the surface structure and is thus at least partially similar to the surface structure. Furthermore, the wavelength conversion layer can at least partially planarize the surface structure by at least partially filling depressions in the surface structure.

[0026] According to a further embodiment, the light-emitting semiconductor chip comprises a substrate having a first main surface and a second main surface, which are opposite one another, wherein the semiconductor layer sequence is arranged on the first main surface and the wavelength conversion layer is arranged on the second main surface. In a preferred embodiment, the second main surface is the light-outcoupling surface. The second main surface can have the surface structure. Alternatively, an intermediate layer as described above is arranged on the light-outcoupling surface formed by the second main surface. Furthermore, the first main surface of the substrate can have a further surface structure, and the semiconductor layer sequence is grown on the further surface structure.

[0027] According to a further embodiment, the substrate is provided with the first main surface, and the semiconductor layer sequence is arranged, preferably grown, on the first main surface. In particular, the semiconductor layer sequence is grown on the substrate using a wafer-based process, as described above. Subsequently, the wavelength conversion layer is deposited on the second main surface, which may be the light-outcoupling surface.

[0028] In cases where the second main surface of the substrate has a surface structure on which the wavelength conversion layer is deposited, the surface structure is created in the second main surface, so that the second main surface is provided with the surface structure before or after the semiconductor layer sequence is arranged on the first main surface.

[0029] For example, the surface structure is provided in the second main surface before the semiconductor layer sequence is arranged on the first main surface. In this case, it may be preferred for the substrate with the second main surface and thus with the surface structure to be arranged on a temporary carrier before the semiconductor layer sequence is arranged on the first main surface. The temporary carrier can be removed after the semiconductor layer sequence has been arranged on the first main surface, thereby exposing the surface structure on the second main surface. Alternatively, the surface structure can be provided on the second main surface after the semiconductor layer sequence has been arranged on the first main surface.In this case, it may be preferable for the substrate to be thinned before the surface structure is provided on the second main surface and after the semiconductor layer sequence is arranged on the first main surface. The second surface can be produced by the thinning process.

[0030] According to a further embodiment, the light-outcoupling surface is a surface of the semiconductor layer sequence, in particular an outermost semiconductor layer of the semiconductor layer sequence. In this case, the outermost semiconductor layer can have the surface structure. Alternatively, an intermediate layer as described above can be arranged on the outermost semiconductor layer.

[0031] According to a further embodiment, an encapsulation layer is arranged on the wavelength conversion layer. The encapsulation layer is preferably transparent and can be arranged directly on the wavelength conversion layer. This can mean, in particular, that the encapsulation layer is arranged in direct contact with at least some of the QDs of the wavelength conversion layer. The encapsulation layer can comprise or consist of one or more layers responsible for a barrier effect of the encapsulation layer. The one or more layers can comprise one or more inorganic and / or organic materials. Inorganic materials can be applied, for example, by means of atomic layer deposition (ALD), sputtering, or plasma-enhanced chemical vapor deposition (PECVD).Suitable inorganic materials can be, for example, transparent inorganic materials such as aluminum oxide, zinc oxide, zirconium oxide, titanium oxide, hafnium oxide, lanthanum oxide, silicon nitride, silicon oxide, silicon oxynitride, silicon carbide, indium tin oxide, indium zinc oxide, aluminum-doped zinc oxide, and mixtures and alloys thereof. Suitable organic materials can be, for example, transparent polymers containing siloxanes, epoxides, imides, carbonates, acrylates, and mixtures and combinations thereof. The encapsulation layer preferably has a layer sequence with a plurality of layers, for example, a plurality of exclusively inorganic layers or a plurality of inorganic and organic layers arranged alternately one above the other.

[0032] Further features, advantages and expediencies will become apparent from the following description of embodiments in conjunction with the figures. The Fig. 1A to 1C show schematic representations of a light-emitting device according to an embodiment, Fig. 2A and Fig. 2B show electron micrographs of a wavelength conversion layer of light-emitting components according to further embodiments, Fig. 3A to 3D show schematic representations of method steps of a method for producing a light-emitting component according to a further embodiment, Fig. 4A to 4C show schematic representations of method steps of a method for producing a light-emitting component according to a further embodiment, Fig. 5 to 7 show schematic representations of light-emitting components according to further embodiments.

[0033] In the figures, elements of the same design and / or function are identified by the same reference numerals. It is understood that the embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale.

[0034] In the following, specific details, such as specific features and advantageous effects of a light-emitting device and a method for manufacturing a light-emitting device, are set forth to provide a comprehensive understanding of embodiments of the invention. It will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details.

[0035] Fig. 1A shows a schematic representation of a light-emitting device 100 according to an embodiment. Fig. 1B and Fig. 1C show details of the light-emitting component 100 of the Fig. 1A. The following description applies equally to the Fig. 1A to 1C.

[0036] The light-emitting component 100 comprises a light-emitting semiconductor chip 1. The light-emitting semiconductor chip 1 has a semiconductor layer sequence 10 comprising at least one light-emitting semiconductor layer 11 that emits light during operation of the light-emitting semiconductor chip 1. By means of electrical contacts in the form of electrode layers 12, an electric current can be applied to the light-emitting semiconductor layer 11 to operate the light-emitting semiconductor chip 1. The semiconductor layer sequence 10 can be based on InAlGaN, for example, and can be configured to generate ultraviolet, blue, or green light. Alternatively, the semiconductor layer sequence 10 can also be based on another semiconductor material, as described in the general part.

[0037] The light generated in the light-emitting semiconductor layer 11 during operation of the light-emitting semiconductor chip 1 is emitted by the chip 1 via a light-outcoupling surface 13. Opposite the light-outcoupling surface 13, the semiconductor chip 1 has a rear surface 13'. The light-outcoupling surface 13 and the rear surface 13' are connected to one another via side surfaces 13''. The light generated during operation can be emitted not only through the light-outcoupling surface 13 but also through the side surfaces 13'' and / or through parts of the rear surface 13'.

[0038] A wavelength conversion layer 2 comprising quantum dots (QDs) 20 is arranged on the light-output surface 13. The light emitted by the light-emitting semiconductor layer 11 can be absorbed by the QDs 20 and converted into light with a different wavelength. Accordingly, the light generated by the light-emitting semiconductor layer 11 can also be referred to as pump light for the QDs 20. The wavelength conversion layer 2 with the QDs 20 is integrated into the light-emitting component 100, as described in detail below.

[0039] Furthermore, the light-emitting semiconductor chip 1 has a substrate 14, which can be a growth substrate or a carrier substrate. The substrate 14 has a first main surface 141 and a second main surface 142. The semiconductor layer sequence 10 is arranged on the first main surface 141, while the second main surface 142 is the light-outcoupling surface 13. In the embodiment shown, the substrate 14 is a growth substrate onto which the semiconductor layer sequence 10 is grown. The electrode layers 12 can be arranged on the same side of the semiconductor layer sequence 10 as the rear side surface 13', so that the light-emitting semiconductor chip 1 is designed, for example, as a so-called flip chip.

[0040] On the second main surface 142 of the substrate, and thus on the light-outcoupling surface 13, the light-emitting semiconductor chip 1 has a surface structure 15, to which the wavelength conversion layer 2 is directly applied. Since, in the embodiment shown, the second main surface 142 is the light-outcoupling surface 13 and has the surface structure 15, the wavelength conversion layer 2 is applied directly to the light-outcoupling surface 13. The surface structure preferably has structure sizes on the order of micrometers.

[0041] As shown in the detailed view in Fig. 1B, the substrate 14 can have a further surface structure 16 on the first main surface 141. The further surface structure is preferably on the order of micrometers. In particular, the first main surface 141 can be a substantially planar and two-dimensional surface on which a plurality of three-dimensional surface elements are arranged, which protrude from the plane formed by the planar surface. The three-dimensional surface elements are designed as elevations that extend upwards away from the planar surface. The surface elements can be round and, in particular, circular when viewed in the vertical direction, so that the surface elements can be designed as conical elevations.Alternatively, the further surface structure 16 can comprise surface elements that, viewed in the vertical direction, have a square, for example, hexagonal, cross-section, so that the surface elements can also be formed as pyramidal elevations on the flat surface. Alternatively, the surface elements can also be formed as depressions that protrude from the flat surface into the substrate 14. Similar to the previously described elevations, the depressions can, for example, be conical or pyramid-shaped.

[0042] In the embodiment shown, the substrate 14 can comprise sapphire, i.e., aluminum oxide, or be made therefrom. In particular, the substrate 14 can be formed as a sapphire wafer on which the semiconductor layer sequence 10 is grown over a large area. By dividing the wafer with the grown semiconductor layer sequence, a plurality of light-emitting semiconductor chips can be produced. The planar surface of the first main surface 141 is preferably formed by a crystallographic c-surface or (-c)-surface of the aluminum oxide, which is particularly suitable for the growth of nitride-based semiconductor materials. Accordingly, the surfaces of the surface elements of the further surface structure 16 are formed by a plurality of other crystal faces according to their orientation relative to the planar surface.As an alternative to the embodiment shown, the substrate 14 can, for example, also comprise a first main surface 141 formed by silicon or silicon carbide, and can accordingly be designed, for example, as a silicon wafer or silicon carbide wafer. Furthermore, a further possibility exists for the substrate 14 to comprise or consist of another material mentioned in the general section above. Furthermore, the first main surface 141 can be designed without the further surface structure 16.

[0043] The wavelength conversion layer 2 can preferably be applied to the surface structure 15 by a method selected from drop casting, inkjet printing, or layer transfer. The QDs 20 can be dispersed in a solvent, which can be hexane or chloroform or other non-polar solvents, and the dispersion can be applied to the surface. Subsequently, the solvent can be evaporated so that essentially only the QDs 20 remain on the surface. As shown in the detailed view in Fig. As shown in Figure 1C, the wavelength conversion layer 2 consists essentially of the QDs 20 and is free of any organic matrix material or other filler material. Accordingly, the wavelength conversion layer 2 is not formed as a composite comprising a matrix material or filler material such as a polymer or other organic materials. Rather, the wavelength conversion layer 2 is formed by a composite of the QDs 20, with the wavelength conversion layer 2 being formed by the deposition process. Consequently, the wavelength conversion layer 2 is not a freestanding component as is commonly used in the art, but is an integrated part of the light-emitting device 1 that cannot be removed without being destroyed.

[0044] The surface structure 15 prevents a coffee stain-like effect during evaporation of the solvent, allowing homogeneous coverage of the light-outcoupling surface 13 with the QDs 20. The wavelength conversion layer 2 thus forms a conformal coating of the surface structure 15. In other words, the wavelength conversion layer 2 covers the surface structure 15 such that the structure of the wavelength conversion layer 2 on the side facing away from the surface structure 15 at least partially resembles the surface structure 15. It is also possible for the wavelength conversion layer 2 to at least partially planarize the surface structure.

[0045] As in the Fig. 1A and Fig. 1C, the surface with the surface structure 15 can be a substantially flat and two-dimensional surface on which a plurality of three-dimensional surface elements are arranged, which protrude from the plane formed by the flat surface or protrude from the flat surface into the element with the surface structure 15. Thus, the surface elements can be, for example, elevations in the form of peaks and / or points or depressions in the form of pits and / or gaps and / or furrows. Viewed in the vertical direction, the surface elements can have a polygonal or round cross-section. In the embodiment shown, the surface structure 15 comprises hemispherical gaps. Fig. Figure 2A shows an SEM (scanning electron microscope) image of a surface structure in which the gaps are arranged hexagonally. Fig. Figure 2B shows an SEM image of another surface structure with hexagonally arranged peaks. In both cases, it is clearly visible that the surface structure is conformally covered by the wavelength conversion layer, which consists primarily of the QDs.

[0046] Since the wavelength conversion layer 2 with the QDs 20 is deposited directly on the surface structure 15 on the light coupling surface 13, which in the case of the embodiment of the Fig. 1A to 1C, the light-emitting semiconductor chip 1 provides a mechanically strong, thermally highly conductive support for holding the QDs 20 in close proximity to the light-emitting semiconductor layer 11, which generates the pumping light. This arrangement is an improvement over previously known freestanding QD solutions, which require a substrate made of (porous) ceramic, glass, or other materials to accommodate the QDs. The integrated arrangement of the QDs 20 enables an on-chip QD converter that is superior in terms of reduced light loss due to reduced scattering and provides high conversion efficiency. In particular, the wavelength conversion layer can be designed to enable complete conversion, i.e., that essentially all of the light emitted by the light-emitting semiconductor layer toward the wavelength conversion layer is converted by the QDs.In addition, excellent thermal properties are provided with the possibility of active cooling of the entire structure.

[0047] The Fig. 3A to 3D show method steps of a method for manufacturing the light-emitting component 100 according to the embodiment of the Fig. 1A to 1C. As in Fig. 3A, in a first step, a substrate 14 is provided which has a first main surface 141 with the further surface structure 16, as in connection with the Fig. 1A to 1C. Alternatively, the substrate 14 can also be provided with a flat first main surface 141 without the further surface structure 16. In particular, the substrate 14 can be provided as a substrate wafer, so that the following method steps can be carried out in a wafer-based method. The substrate 14, which can be, for example, a sapphire substrate, as explained above, is a growth substrate on which the semiconductor layer sequence 10, as in Fig. 3B. The semiconductor layer sequence 10 comprises a light-emitting semiconductor layer and, as explained above, can be provided with electrode layers 12.

[0048] Since the substrate 14 provided as a growth substrate wafer has a thickness that is significantly greater than the desired substrate thickness in the final light-emitting semiconductor chip, the substrate 14 is thinned in a further process step in order to reduce the substrate thickness, as shown in Fig. 3C. The thinning can be performed, for example, by etching or grinding. Typically, the thickness of the substrate 14 is reduced to approximately 150 µm. Alternatively, the final substrate thickness can also be greater or smaller, depending on the desired properties of the substrate. Subsequently, or in conjunction with the thinning process, the surface structure 15 is produced on the side of the substrate 14 facing away from the first main surface 141, whereby the second main surface 142 is formed with the surface structure 15, as shown in Fig. 3D. The formation of the surface structure 15 can be achieved, for example, by an etching process. As described above, the second main surface 142 of the substrate 14 forms the light-outcoupling surface 13.

[0049] In a further process step, the wavelength conversion layer with QDs is then applied to the light output surface 13 and the wafer is separated so that a plurality of light-emitting components 100, as in the Fig. 1A to 1C.

[0050] The Fig. 4A to 4C show process steps of a method for manufacturing the light-emitting component 100 of the Fig. 1A to 1C according to a further embodiment. The substrate 14 is provided with a first main surface 141 and a second main surface 142, wherein the second main surface 142 is provided with the surface structure 15 and the first main surface 141 is provided with the further surface structure 16. Alternatively, the substrate 14 can also be provided with a flat first main surface 141 without the further surface structure 16. Thus, in contrast to the embodiment of the Fig. 3A to 3D as a wafer with two structured main surfaces and a thickness corresponding to the desired final substrate thickness in the light-emitting component. Since this thickness is generally too small for sufficient stability in the subsequent process steps, the substrate 14 is attached to the second main surface 142 on a temporary carrier 91 by means of a bonding layer 92, which can be an adhesive, for example. The composite formed by the temporary carrier 91 and the substrate 14 has a thickness that can typically be significantly more than approximately 150 µm and provides sufficient stability.

[0051] As in Fig. 4B, the semiconductor layer sequence 10 and the electrode layers 12 are deposited on the first main surface 141 as explained above. Subsequently, as shown in Fig. 4C, the temporary carrier 91 and the connecting layer 92 are removed by a lift-off process to expose the substrate 14 with the chip layers deposited thereon from the temporary carrier 91. As described above, the now exposed second main surface 142 of the substrate 14 forms the light-outcoupling surface 13. In a further process step, the wavelength conversion layer with QDs is applied to the light-outcoupling surface 13 and the wafer is singulated into a plurality of light-emitting components 100, as shown in the Fig. 1A to 1C.

[0052] The following figures illustrate further embodiments of the light-emitting device 100, which are modifications of the previously described embodiments. The following description therefore focuses primarily on the differences from the previous embodiments.

[0053] In Fig. 5 shows a further embodiment of the light-emitting component 100, which has an intermediate layer 3 arranged on a surface of the light-emitting semiconductor chip 1. In particular, the intermediate layer 3 is arranged on, preferably directly on, the light-outcoupling surface 13. The intermediate layer 3 can be deposited, for example, by a pulsed laser deposition method (PLD) or bonded to the second main surface 142. As shown in Fig. As shown in Figure 5, the light-outcoupling surface 13, which in the present embodiment is the second main surface 142 of the substrate 14, can be flat and without a surface structure. Alternatively, the light-outcoupling surface 13 can have a surface structure, and the intermediate layer 3 can be applied directly to the surface structure of the light-outcoupling surface 13.

[0054] The wavelength conversion layer 2 is deposited on the intermediate layer 3, preferably directly on the intermediate layer 3. The intermediate layer 3 has a surface facing away from the light-outcoupling surface 13, which surface has a surface structure 15. As shown, the wavelength conversion layer 2 is deposited directly on the surface structure 15 of the intermediate layer 3. The surface structure 15 can be formed as described above.

[0055] The intermediate layer 3 preferably comprises or consists of a wavelength conversion material. The wavelength conversion material, which may differ from QDs, may be suitable for converting at least part of the light emitted by the light-emitting semiconductor chip 1 into light with a different wavelength, which may also differ from the wavelength of the light emitted by the wavelength conversion layer 2. For example, the intermediate layer 3 may comprise a ceramic wavelength conversion material, which may be in the form of a ceramic layer or in the form of particles dispersed in a matrix material. The wavelength conversion material of the intermediate layer 3 may, for example, comprise YAG and / or LuAG or another garnet and may, for example, be doped with Ce.The combination of the light-emitting semiconductor chip 1, the wavelength conversion layer 2 with the QDs and the intermediate layer 3 with the wavelength conversion material can preferably result in a white light-emitting component 100 with an integrated QD layer.

[0056] In the Fig. 6A and Fig. 6B shows a further embodiment of the light-emitting component 100, which has an encapsulation layer 4 arranged on the wavelength conversion layer 2. Fig. 6B shows a detailed view of a part of the light-emitting component 100 from Fig. 6A.

[0057] Preferably, the encapsulation layer 4 is transparent and can, as in the Fig. 6A and Fig. 6B, be arranged directly on the wavelength conversion layer 2, so that the encapsulation layer 4 is arranged in direct contact with at least some of the QDs of the wavelength conversion layer 2. The encapsulation layer 4 can comprise or consist of one or more layers that are responsible for a barrier effect of the encapsulation layer 4. The one or more layers can comprise one or more inorganic and / or organic materials, as described above in the general part. Preferably, the encapsulation layer 4 has a layer sequence that has a plurality of layers, for example a plurality of exclusively inorganic layers or a plurality of inorganic and organic layers that are arranged alternately one above the other. By way of example, in the detailed view in Fig. 6B shows three layers 41, 42, 43 of the encapsulation layer 4. Alternatively, the encapsulation layer 4 may also have fewer or more than three layers.

[0058] In the embodiments explained above, the light-outcoupling surface 13 is formed by the second main surface 142 of the substrate 14. In this way, it is possible to manufacture the light-emitting component 100 as a light-emitting conversion component using a one- or two-sided structured surface substrate, in particular made of sapphire, and an integrated QD film formed by the wavelength conversion layer 2 deposited on one of the structured surfaces of the substrate 14 or an intermediate layer 3 on the substrate 14. By introducing a suitable topography on the non-epitaxy side of the substrate, it is possible to use the conventional process sequence for manufacturing the light-emitting semiconductor chip in combination with the introduction of the wavelength conversion layer specifically formed by QDs.As explained above, after the fabrication of the light-emitting semiconductor chip, which may be, for example, a blue-light-emitting semiconductor chip, the QD layer is deposited on the surface structure.

[0059] Furthermore, it is possible for the light-emitting semiconductor chip to comprise a carrier substrate to which the layer sequence has been transferred after the semiconductor layers have grown on a growth substrate. In this case, the light-outcoupling surface can be formed by another surface of the light-emitting semiconductor chip. For example, the light-outcoupling surface 13 can be a surface of the semiconductor layer sequence 10, as shown in the detailed view in Fig.7. The wavelength conversion layer 2 can be deposited directly on a surface structure 15 on the light-outcoupling surface 13 of the semiconductor layer sequence 10. Alternatively, an intermediate layer, which can comprise a transparent material and / or a wavelength conversion material, can be arranged on the light-outcoupling surface 13 of the semiconductor layer sequence 10, and the wavelength conversion layer 2 can be deposited on the intermediate layer.

[0060] Since in all embodiments the wavelength conversion layer containing the QDs is an integral part of the light-emitting component, it is possible to produce a solid QD-containing composite with the possibilities of improved control and stability of the position of the QDs, as well as protection and encapsulation of the QDs. Furthermore, the integrated QD-containing wavelength conversion layer enables improved color matching of the light-emitting component. Since the deposition of the wavelength conversion layer containing the QDs can be integrated into a conventional design and process flow for manufacturing light-emitting semiconductor chips, a cost reduction is possible compared to approaches using freestanding QD converters.

[0061] Alternatively or in addition to the features described in connection with the figures, the embodiments illustrated in the figures may include further features described in the general part of the description. Furthermore, features and embodiments of the figures may be combined with one another, even if such a combination is not explicitly described. Reference symbol 1 light-emitting semiconductor chip 2 wavelength conversion layer 3 Intermediate layer 4 Encapsulation layer 10 Semiconductor layer sequence 11 light-emitting semiconductor layer 12 Electrode layer 13 Light extraction surface 13' rear surface 13'' side surface 14 Substrat 15 Surface structure 16 additional surface structures 20 quantum dots 41, 42, 43 shift 91 temporary carrier 92 connection layer 100 light-emitting component 141 first main area 142 second main area

Claims

[1] Light-emitting component (100), comprising a light-emitting semiconductor chip (1) with a semiconductor layer sequence (10) comprising at least one light-emitting semiconductor layer (11) and a light coupling-out surface (13), a wavelength conversion layer (2) arranged on the light-outcoupling surface, wherein the wavelength conversion layer comprises quantum dots (20), wherein a surface structure (15) is provided on the light-outcoupling surface and the wavelength conversion layer is deposited directly on the surface structure, wherein the wavelength conversion layer is a conformal coating of the surface structure, and wherein the wavelength conversion layer is free of a matrix material. [2] The light-emitting device according to claim 1, wherein the wavelength conversion layer consists essentially of the quantum dots. [3] Light-emitting component according to one of the preceding claims, wherein the light coupling-out surface is a surface of the semiconductor layer sequence. [4] Light-emitting component according to one of the preceding claims, wherein the light-emitting semiconductor chip comprises a substrate (14) having a first main surface (141) and a second main surface (142), wherein the semiconductor layer sequence is arranged on the first main surface, wherein the wavelength conversion layer is arranged on the second main surface. [5] The light-emitting component according to claim 4, wherein the second main surface is the light-coupling surface and has the surface structure. [6] Light-emitting component according to claim 4 or 5, wherein the first main surface has a further surface structure (16) and the semiconductor layer sequence is grown on the further surface structure. [7] Light-emitting component according to one of the preceding claims, wherein an intermediate layer (3) is arranged on the light coupling surface, wherein the intermediate layer has a surface facing away from the light coupling surface, which surface has the surface structure. [8] A light-emitting device according to claim 7, wherein the intermediate layer comprises a wavelength conversion material. [9] Light-emitting component according to one of the preceding claims, wherein an encapsulation layer (4) is deposited on the wavelength conversion layer. [10] The light-emitting device according to claim 9, wherein the encapsulation layer comprises a plurality of layers. [11] Method for producing a light-emitting component (100), wherein a light-emitting semiconductor chip (1) is provided, wherein the light-emitting semiconductor chip has a semiconductor layer sequence (10) comprising at least one light-emitting semiconductor layer (11) and a light coupling-out surface (13), wherein a wavelength conversion layer (2) is deposited on the light-outcoupling surface, wherein the wavelength conversion layer comprises quantum dots (20), wherein a surface structure (15) is provided on the light-outcoupling surface and the wavelength conversion layer is deposited directly on the surface structure, wherein the wavelength conversion layer is a conformal coating of the surface structure, and wherein the wavelength conversion layer is free of a matrix material. [12] The method according to claim 11, wherein the wavelength conversion layer is deposited by at least one of the following methods: drop casting, inkjet printing, layer transfer. [13] The method according to any one of claims 11 or 12, wherein a substrate (14) having a first main surface (141) and a second main surface (142) is provided, wherein the semiconductor layer sequence is grown on the first main surface, wherein the wavelength conversion layer is deposited on the second main surface. [14] Method according to claim 13, wherein the surface structure is created in the second main surface. [15] Method according to claim 13 or 14, wherein the surface structure is provided in the second main surface before the semiconductor layer sequence is arranged on the first main surface, wherein the substrate is arranged with the second main surface on a temporary carrier (91) before the semiconductor layer sequence is arranged on the first main surface, and wherein the temporary carrier is removed after arranging the semiconductor layer sequence on the first main surface, thereby exposing the surface structure on the second main surface. [16] Method according to one of claims 13 to 15, wherein the surface structure is provided on the second main surface after the semiconductor layer sequence is arranged on the first main surface. [17] Method according to one of claims 13 to 16, wherein the substrate is thinned before the surface structure is provided on the second main surface and after the semiconductor layer sequence is arranged on the first main surface.

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