Light-emitting device having ingaalp passivation, and method of manufacturing

Abstract

The invention relates to a light-emitting device, in particular a microLED, comprising a semiconductor layer stack (2) consisting of at least a first layer (3) of a first conductivity type, a second layer (4) of a second conductivity type, an active AlGaAs region (5) positioned between the first and the second layers (3, 4) and configured so that it emits light in the infrared range, a top face (11a), a bottom face (11b) opposite the top face (11a), and a first lateral surface (11c) that extends from the top face (11a) towards the bottom face (11b). The light-emitting device additionally comprises an InGaAlP growth layer (16) which covers the first lateral surface (11c) and at least part of the upper face (11a). The first lateral surface (11c) comprises the second layer (4), the active region (5) and at least a part of the first layer (3).

Description

[0001] Light-emitting device with an INGAALP passivation and val-

[0002] DRIVE TO MANUFACTURE

[0003] The present application claims priority over German patent application No. 10 2024 114 718 . 0 of 24 May 2024, the disclosure content of which is hereby incorporated into the present application by reference.

[0004] The present invention relates to a light-emitting device, in particular an infrared light-emitting LED or pLED, with an InGaAlP layer extending along side surfaces of the light-emitting device. Furthermore, the invention relates to a method for manufacturing such a light-emitting device.

[0005] BACKGROUND pLEDs are light-emitting devices with lateral dimensions ranging from a few pm to about 40 pm. Such devices offer a wide variety of applications, including, but not limited to, displays.

[0006] To increase the external quantum efficiency (EQE) of, for example, pLEDs or, more generally, of small light-emitting structures, the geometry, shape, and structure (passivation, reflector mirrors, etc.) of the pLEDs can be designed to maximize the light extraction efficiency (LEE) within a specific solid angle. In addition to LEE, internal quantum efficiency (IQE) is equally important, with a major loss factor arising from non-radiative recombination (NRR) of charge carriers within the pLED.

[0007] In particular, pLEDs based on an AlGaAs material system, and thus designed to emit infrared light, suffer from decreasing performance at smaller sizes. One reason for this performance drop can be the NRR of the injected charge carriers on etched surfaces. Etching, for example, is a common standard procedure for pixel isolation (etching through the active region and physical separation of individual pixels), which, depending on the method used and the parameters, leads to damage to the surface and the underlying layers. In this case, damage means the formation of defect centers in the crystal lattice of the etched structure.The defects that form on the surface and below the active region—which is exposed during and after pixel etching—act as non-radiative recombination channels. These, in combination with the NRR (non-radiative recombination) that is already present on the outer surfaces of some pLED material systems, drastically reduce the IQE (interactive quantization efficiency) of the pLED and lead to poor overall performance. This effect is particularly pronounced for the AlGaAs material system due to its large charge carrier diffusion length and surface recombination velocities, as well as the Fermi-level pinning on the semiconductor surface. This poses a significant challenge, especially for small pixels, such as pLEDs with a high surface area-to-volume ratio, particularly a high ratio between the exposed surface area of ​​the active region at the pixel's sidewall and the total volume of the active region.

[0008] To reduce non-radiative recombination at the edges of a pLED, one possible approach is to passivate the pLED surface, for example, using dielectrics. However, this does not significantly improve performance in the desired way. Another approach to reducing non-radiative recombination at the side faces of a pLED is to keep charge carriers away from the side faces that represent the centers of non-radiative recombination. This can be achieved, for example, by quantum wave mixing of the active regions in areas along the pLED's side faces, where a suitable dopant diffuses into the vicinity of the active region and, through mixing processes, increases the band gap of the active region along the side faces. In this way, charge carriers can be kept away from the side faces that represent the centers of non-radiative recombination.In the InGaAlP material system, Zn diffusion has become established for laser diodes. However, such a process using Zn diffusion does not appear to be established in the AlGaAs material system. Instead, "Impurity Free Quantum Well Intermixing" has been reported for the AlGaAs material system, in which SiO₂ is deposited and mixed with the Ga from the semiconductor. However, the required process temperature is significantly higher than for Zn diffusion, and no productive application of such a process is yet known.

[0009] The objective of the present application is therefore to provide a light-emitting device that overcomes at least some of the aforementioned aspects, as well as to provide a method for manufacturing such a light-emitting device.

[0010] SUMMARY OF THE INVENTION

[0011] This need is addressed by the subject matter of the independent patent claims. Further developments and embodiments of the proposed principle are specified in the dependent claims.

[0012] The inventors have discovered that by growing an epitaxial InGaAlP passivation / regrowth layer along the entire side faces of an AlGaAs semiconductor stack in a light-emitting device, after exposing the side faces of an active region of the semiconductor stack and structuring the semiconductor stack itself, losses within the light-emitting device can be drastically reduced and manufacturing costs lowered. After etching through the active region of the semiconductor stack and subsequent cleaning of the etched areas, these are overgrown, particularly with undoped or lightly doped InGaAlP.

[0013] Cleaning removes oxides, and overgrowth protects the semiconductor layer stack from re-oxidation. Charge carriers in the active region are kept away from the etched surface by the overgrowth layer, which encompasses the centers for non-radiative recombination. Using an InGaAlP layer for epitaxial overgrowth of the AlGaAs semiconductor layer stack offers several advantages over an AlGaAs passivation layer: it has a particularly large band gap and is therefore especially suitable for keeping charge carriers away from the etched surface. While the band gap in AlGaAs can be adjusted by increasing the Al content, this increases its susceptibility to moisture and corrosion. InGaAlP, on the other hand, is significantly more stable in this respect. Furthermore, InGaAlP can be selectively etched compared to Al-deficient AlGaAs.In the manufacture of the light-emitting device, it is therefore possible to remove the InGaAlP overgrowth layer at a suitable location and to establish an electrical contact with the AlGaAs layer ( ) of the semiconductor layer stack.

[0014] Advantages that can arise from the proposed concept include more effective passivation of the etched sidewalls, since epitaxial passivation is more effective than dielectric passivation. Furthermore, a single epitaxial passivation step can significantly reduce costs compared to multiple separate passivation steps.

[0015] According to a first aspect, a light-emitting device, in particular a pLED, is provided with a semiconductor layer stack. The semiconductor layer stack comprises at least a first layer of a first conductivity type, a second layer of a second conductivity type, and an active AlGaAs region arranged between the first and second layers. The active region is composed of an AlGaAs material system and is configured to emit light in the infrared range. In particular, the active region of the semiconductor layer stack comprises at least one quantum well; however, the active region can also comprise a multi-quantum-well structure with multiple quantum wells.

[0016] The semiconductor layer stack comprises a top surface, a bottom surface opposite the top surface, and a first side surface extending from the top surface towards the bottom surface. The first side surface, in particular, laterally delimits a light-emitting section of the semiconductor layer stack, which in the subsequent light-emitting device is configured to emit light in the infrared range. The first side surface extends from the top surface through the semiconductor layer stack, encompassing at least the second layer, the active region, and at least a portion of the first layer. The side surface can, for example, result from a step in the structuring of the semiconductor layer stack in which a portion of the semiconductor layer stack is removed, leaving another portion, in particular the light-emitting section, behind.The first side surface can be a resulting side surface of the remaining light-emitting section. In particular, the first side surface can result from an etching step for structuring the semiconductor layer stack, leading to an etched side surface that extends at least through the second layer, the active region, and at least partially through the first layer.

[0017] The light-emitting device further comprises an InGaAlP growth layer covering the first side surface and at least a portion of the top surface. By growing the InGaAlP layer, and particularly due to prior cleaning of the etched surfaces, defects on the first side surface can be removed, and the first side surface can then be passivated by means of the InGaAlP growth layer. Furthermore, the high band gap of the InGaAlP growth layer prevents charge carriers from diffusing towards the first side surface.

[0018] The idea is that the InGaAlP growth layer extends continuously along the first face, and thus along the entire thickness of the second layer and the active region, as well as along at least a portion of the first layer. This is to be understood as independent of whether the first face comprises a single continuous section or several laterally offset sections. Continuous or continuous means that the InGaAlP growth layer extends along the first face in one piece in the direction along the first face and, in particular, results from a single regrowth step (at least for each sublayer of the InGaAlP growth layer). In contrast, a compound growth layer resulting from multiple regrowth steps is to be understood as non-continuous.

[0019] According to some aspects, the first layer and / or the second layer is also formed from or comprises AlGaAs; therefore, in the following, one can also refer to a first AlGaAs layer and a second AlGaAs layer. However, it is also possible that the first layer and / or the second layer, or at least parts of it, are formed from InGaAlP or an As / P solid solution.

[0020] According to some aspects, the first conductivity type is an n-type and the second conductivity type is a p-type. Therefore, the first layer can be an n-type semiconductor layer and the second layer can be a p-type semiconductor layer.

[0021] According to some aspects, the first side surface comprises at least a first and a second side surface section, which are laterally offset from each other, with the first side surface section directly adjacent to the top surface. The first side surface section includes at least the second layer and the active area, while the second side surface section comprises "only" a portion of the first layer. The first and second side surface sections can, in particular, be connected by a substantially horizontal intermediate side surface section. For example, the first side surface section can result from a first etching step, while the second side surface section can result from a second etching step that is laterally offset from the first etching step.

[0022] According to some aspects, the semiconductor layer stack comprises a second side surface that is directly adjacent to the first side surface and laterally offset from it. The second side surface can, in particular, result from a further etching step that is laterally offset from one or more preceding etching steps leading to the first side surface. The first side surface and the second side surface can, in particular, be connected by a substantially horizontal intermediate side surface section. The second side surface extends from the first side surface through the first layer to the bottom. By means of the second side surface, the light-emitting section of the semiconductor layer stack can be further delimited, and in particular, the light-emitting section can be separated from other sections of the semiconductor layer stack.The second face, however, is free of the InGaAlP growth layer. This can result, in particular, from the fact that the subsequent etching step leading to the second face can be carried out after the InGaAlP growth layer has grown on the first face. Thus, the subsequent etching step allows both etching through the InGaAlP growth layer and the exposure of the second face of the semiconductor layer stack.

[0023] According to some descriptions, a first contact layer is arranged on the underside, which electrically contacts the first layer of the semiconductor stack. The first contact layer can consist of the same material system as the semiconductor stack, but it can also be a contact layer made of a metal and / or a transparent conductive oxide (TCO), such as indium tin oxide (ITO). A first potential can be applied to the light-emitting device via the first contact layer to operate it in a desired manner. The first contact layer can, in particular, consist of a TCO. According to some descriptions, such a light-emitting device is designed as a vertically contactable component.

[0024] According to some aspects, a second contact layer is arranged on the top surface, which electrically contacts the second layer of the semiconductor stack. This second contact layer can consist of the same material system as the semiconductor stack, but it can also be a contact layer made of a metal and / or a transparent conductive oxide (TCO), such as indium tin oxide (ITO). A second potential can be applied to the light-emitting device via this second contact layer to operate it in a desired manner. The second contact layer can, for example, consist of a TCO.According to some aspects, the light-emitting device further comprises a first dielectric layer or a dielectric layer stack which is arranged on at least one of the following layers: on the InGaAlP growth layer opposite the first side surface; on the InGaAlP growth layer opposite the top surface; on the second contact layer opposite the top surface, in particular exposing a contact area of ​​the second contact layer; and on the second side surface.

[0025] The first dielectric layer can, in particular, cover all side faces of the semiconductor layer stack that are not covered by the InGaAlP growth layer. Furthermore, in some embodiments, the first dielectric layer can form an electrical insulator between the first and second contact layers.

[0026] According to some aspects, the light-emitting device includes a reflective layer arranged on the dielectric layer and extending along the first side face and the top surface. The reflective layer can form a mirror, e.g., a parabolic or parabolic mirror, for the light generated in the semiconductor layer stack. With the aid of the mirror, the light generated in the semiconductor layer stack can be amplified and coupled out of the light-emitting device through the bottom surface, and focusing the light into a smaller solid angle is possible.

[0027] According to some accounts, the light-emitting device includes a second dielectric layer positioned on top of the reflecting layer, which, together with the first dielectric layer, encapsulates the reflecting layer. By encapsulating the reflecting layer between the first and second dielectric layers, it is possible to ensure that the reflecting layer is at a floating potential, i.e., not electrically connected. This can result in the reflecting layer exhibiting little to no aging.

[0028] According to some aspects, the semiconductor layer stack has a cavity that extends from the top towards the bottom, reaching down to the first layer. A first contact layer is arranged on one of the cavity's bottom surfaces, electrically contacting the first layer of the semiconductor layer stack. Furthermore, at least portions of the cavity's side surfaces are covered by the InGaAlP wax layer. The cavity and the first contact layer located on its bottom surface allow for the provision of a horizontally contactable device, since both the first contact layer and a second contact layer are formed on the top surface of the semiconductor layer stack, enabling the light-emitting device to be electrically connected to a power source from the top side.

[0029] According to some aspects, the semiconductor layer stack also includes an InGaAlP layer between the first layer and the bottom surface, with the InGaAlP layer forming the bottom surface. In particular, the bottom surface, and thus the InGaAlP layer, is part of a light-emitting surface of the light-emitting device, wherein the light-emitting surface and the bottom surface are formed by a planar surface from which no, or substantially no, elements or areas of the light-emitting device protrude. The bottom surface and the light-emitting surface can, in particular, be provided by a CMP process, by which simple planarization of the bottom surface and the light-emitting surface can be achieved.

[0030] According to some aspects, the bottom surface of the cavity is formed by the InGaAlP layer. In particular, the InGaAlP layer forming the bottom surface can simultaneously act as a light-emitting surface and a current-expansion layer in the light-emitting device. The InGaAlP layer extends between the bottom surface and the bottom surface of the cavity, and no further AlGaAs layer is formed between these two surfaces. This can be particularly advantageous because selective etching during cavity formation can utilize the high material contrast between AlGaAs and InGaAlP to remove the AlGaAs layers within the cavity, while the etching automatically stops upon reaching the InGaAlP layer. Thus, precise exposure of the current-expansion layer in the light-emitting device can be achieved using simple processes.An electrical contact with the side of the semiconductor layer stack, which includes the first layer, can accordingly be provided through the cavity from the sides of the top and directly contacts the InGaAlP layer.

[0031] According to some aspects, the InGaAlP layer forms a planar emission surface of the final light-emitting device and optionally also the layer on which the contact path stops or which acts as a current-expansion layer in the final light-emitting device. An InGaAlP layer is particularly suitable because the material contrast between AlGaAs and InGaAlP is so high that selective etching is possible. This allows, firstly, the creation of a planar emission surface using CMP (chemical mechanical polishing), and secondly, the precise exposure of the InGaAlP current-expansion layer integrated into the layer sequence for electrical contact.

[0032] In particular, such an InGaAlP layer makes it possible to planarize the light-out side of a light-emitting device in a chip process, for example, via a CMP process. Specifically, if the side faces of the epitaxial layer sequence of the light-emitting device are passivated with aluminum oxide (A1O), the proposed method provides a suitable process in which the A1O can be removed along with the regions of the epitaxial layer sequence, thus preventing the formation of protruding A1O peaks at the edges of the light-emitting device. Advantageously, the InGaAlP layer has a low Al content, which improves contact with the AlGaAs layer sequence and also leads to an increased refractive index. The latter is advantageous for light extraction from the light-emitting device if the InGaAlP layer includes light-scattering structures.The presence of a relatively thick InGaAlP layer can also offer advantages by reducing potential stress / bending of the growth substrate as well as the light-emitting device itself. Alternatively or additionally to the InGaAlP layer, the semiconductor layer stack may include an AlGaAs interlayer within the first layer, specifically designed as an AlGaAs layer with a lower aluminum content than the first AlGaAs layer. This AlGaAs interlayer may be located between the bottom surface and the active region of the first AlGaAs layer, and may form the bottom surface of the cavity. Similarly, the current-expansion layer may also be formed by an AlGaAs interlayer with a lower aluminum content than the first AlGaAs layer.In particular, the AlGaAs interlayer can be embedded between regions of the first AlGaAs layer, each of which has a higher Al content than the AlGaAs interlayer. This can be particularly advantageous because, through selective etching during cavity creation, the material contrast (different Al content) between the AlGaAs interlayer and the first AlGaAs layer can be used to remove the first AlGaAs layer in the cavity area, while the etching automatically stops upon reaching the AlGaAs interlayer. Thus, precise exposure of the current-expansion layer in the light-emitting device can be achieved using simple processes. Electrical contact with the side of the semiconductor layer stack containing the first AlGaAs layer can be provided by the cavity from the top side and directly contacts the AlGaAs interlayer.

[0033] According to certain aspects, the light-emitting device comprises a first contact element that is electrically coupled to the first layer or the first contact layer. The first contact element can, in particular, be configured as a contact pad by means of which the light-emitting device can be electrically connected. In the case of a cavity in the semiconductor layer stack, the first contact element can, in particular, be arranged on the top side and extend from the first contact layer to a height above the top side, in particular to a height of a second contact element arranged on the second contact layer, thus providing a horizontally contactable component. Such a first contact element can, in particular, be electrically insulated from the InGaAlP growth layer, the active region, the second layer, and the second contact layer by means of the first and / or second dielectric layer.The first contact element allows the light-emitting device to be electrically connected, in particular by means of a soldering or bonding process.

[0034] According to some aspects, the light-emitting device comprises a second contact element that is electrically coupled to the second layer or the second contact layer. The second contact element can, in particular, be designed as a contact pad by means of which the light-emitting device can be electrically connected. Such a second contact element can, in particular, be electrically insulated from the InGaAlP growth layer, the active area, the first layer, and the first contact layer by means of the first and / or second dielectric layer. The light-emitting device can be electrically connected by means of the second contact element, in particular by means of a soldering or bonding process.

[0035] According to some aspects, the light-emitting device comprises a first contact element that is electrically coupled to the first layer or the first contact layer, wherein the first contact element optionally consists of a reflective material and circumferentially surrounds the light-emitting section of the semiconductor layer stack. The first contact element can, for example, be a metallic grid that circumferentially surrounds the light-emitting section. In particular, the first contact element can be in the form of a metallic grid that includes an element that circumferentially surrounds the semiconductor layer stack. Due to its conductivity, the metallic grid, together with the first contact layer or the second contact layer, can be used, in particular, to electrically connect the light-emitting device to a power source.

[0036] According to some aspects, the light-emitting device is a pLED array, wherein the semiconductor layer stack comprises several first side faces that laterally bound several light-emitting sections of the semiconductor layer stack arranged side by side. The light-emitting sections may be arranged on a common support substrate, in particular a semiconductor substrate. In some aspects, the common support substrate may be formed by a continuous residue of the first layer.

[0037] According to another aspect, a method for manufacturing a light-emitting device is provided. In particular, the method can be a method for manufacturing a light-emitting device according to at least some of the aforementioned aspects. Thus, all aspects already described for the light-emitting device can be applied in the same way to the method for manufacturing it.

[0038] The process includes the following steps:

[0039] Providing a semiconductor layer stack consisting of at least one first layer of a first conductivity type on a growth substrate, a second layer of a second conductivity type, and an active AlGaAs region positioned between the first and second layers and configured to emit light in the infrared range;

[0040] Structuring the semiconductor layer stack, wherein at least one first section of the semiconductor layer stack remains and a second section of the semiconductor layer stack adjacent to the at least one first section is removed, such that the at least one first section comprises a first side surface extending from a top surface of the semiconductor layer stack towards the growth substrate, wherein the first side surface comprises the second layer, the active region and at least a part of the first layer; and

[0041] Growth of an InGaAlP growth layer on the first side surface and at least part of the top surface.

[0042] According to some aspects, the step of structuring the semiconductor layer stack includes: a first step of mesa-etching the semiconductor layer stack, which leads to a first side-face section of the first side face adjacent to the top and includes at least the second layer and the active region; and a second step of mesa-etching the semiconductor layer stack, which leads to a second side-face section of the first side face, which includes a part of the first layer.

[0043] The first and second mesa etching steps are carried out in such a way that the first and second side surface sections are laterally offset from each other, and in particular the first and second mesa etching steps are carried out at laterally offset positions.

[0044] According to some aspects, the method includes further structuring of the semiconductor layer stack, in particular a third step of mesa-etching the semiconductor layer stack, which creates a second side surface adjacent to the first. This step is performed such that the first and second side surfaces are laterally offset from each other, and in particular, the step is carried out at a position laterally offset from the structuring that leads to the first side surface. The resulting second side surface comprises a portion of the first layer and extends, in particular, from the first side surface to the growth substrate or to a bottom surface of the semiconductor layer stack opposite the top surface. By means of the second side surface, a light-emitting section of the semiconductor layer stack can be separated, in particular, from other sections of the semiconductor layer stack.The second surface, however, is particularly free of the InGaAlP growth layer. This can result, in particular, from the fact that the subsequent etching step leading to the second surface can be carried out after the InGaAlP growth layer has formed on the first surface.

[0045] According to some considerations, the growth of the InGaAlP layer occurs before further structuring of the semiconductor layer stack. The subsequent etching step can therefore both etch through the InGaAlP growth layer and expose the second face of the semiconductor layer stack.

[0046] According to some aspects, the method further comprises a step of applying a first dielectric layer or a dielectric layer stack to at least one of the following areas: on the InGaAlP growth layer opposite the first side surface; on the InGaAlP growth layer opposite the top surface; on the second contact layer opposite the top surface, in particular exposing a contact area of ​​a second contact layer; and on the second side surface.

[0047] The first dielectric layer can, in particular, cover all side faces of the semiconductor layer stack that are not covered by the InGaAlP growth layer. Furthermore, in some embodiments, the first dielectric layer can form an electrical insulator between the first and second contact layers.

[0048] According to some aspects, the method further comprises providing a reflective layer on the first dielectric layer, extending along the first side face and the top surface, wherein the reflective layer is, in particular, electrically insulated from the first and the second layers. Furthermore, the method may optionally include providing a second dielectric layer on the reflective layer, which, together with the first dielectric layer, encapsulates the reflective layer.

[0049] According to some aspects, the step of structuring the semiconductor layer stack includes creating a cavity that extends from the top surface towards the growth substrate and into the first layer. Furthermore, the step of growing the InGaAlP growth layer includes covering at least some areas of the cavity's side surfaces with the InGaAlP growth layer. The process also includes providing a first contact layer on a bottom surface of the cavity, which electrically contacts the first layer of the semiconductor layer stack. According to some aspects, the process also includes providing a second contact layer on the top surface, which electrically contacts the second layer of the semiconductor layer stack.Together with the cavity already described and the first contact layer located on the bottom surface of the cavity, a horizontally contactable component can be provided, since both the first contact layer and a second contact layer are formed on the top of the semiconductor layer stack on the same side of the semiconductor layer stack, so that the light-emitting device can be electrically connected to a power source from the top side.

[0050] According to some aspects, the procedure also includes at least one of the following steps:

[0051] Applying a first contact element that is electrically coupled to the first contact layer;

[0052] Applying a second contact element that is electrically coupled to the second contact layer;

[0053] Applying a sacrificial layer to at least one of the first dielectric layer, the second dielectric layer, the first contact element, the second contact element, the InGaAlP growth layer, and the semiconductor layer stack;

[0054] Applying a potting layer, in particular to the sacrificial layer, in particular such that the potting layer is in direct contact with at least one of the first dielectric layer, the second dielectric layer, the first contact element, the second contact element, the InGaAlP wax layer, and the semiconductor layer stack;

[0055] Removal of the growth substrate;

[0056] Exposing one of the undersides of the semiconductor layer stack opposite the top side;

[0057] Structuring the underside to create a visually effective structure;

[0058] Applying an optical element to the underside;

[0059] Applying a first contact layer to the underside;

[0060] Removal of the sacrificial layer; and lifting a light-emitting device from the potting layer. According to some aspects, the step of providing the semiconductor layer stack includes providing an InGaAlP layer between the first layer and the growth substrate. Furthermore, the method includes exposing a bottom side of the semiconductor layer stack opposite the top side, the bottom side being formed by the InGaAlP layer.

[0061] According to some aspects, the semiconductor layer stack includes, in particular, an InGaAlP layer which, after the exposure step, forms a bottom surface of the semiconductor layer stack. Specifically, the bottom surface, and thus the InGaAlP layer, is part of a light-emitting surface of the light-emitting device, wherein the light-emitting surface and the bottom surface are formed by a planar surface from which no, or substantially no, elements or areas of the light-emitting device protrude. The bottom surface or the light-emitting surface can, in particular, be provided by means of a CMP process, by which a simple planarization of the bottom surface or the light-emitting surface can be achieved. Accordingly, the exposure step can include a CMP process that effects a planarization of the bottom surface.

[0062] According to some considerations, creating the cavity allows the InGaAlP layer (AlGaAs layers are etched, but the InGaAlP layer is not) to be exposed using a selective etching process, so that the InGaAlP layer forms the bottom of the cavity. For selective etching, an aqueous etching medium based on sulfuric acid and hydrogen peroxide can be used, for example.

[0063] According to some aspects, the step of deploying the semiconductor layer stack includes deploying an AlGaAs interlayer within the first layer, where the first layer is specifically formed by an AlGaAs layer and the AlGaAs interlayer has a lower aluminum content than the first AlGaAs layer. The step of creating the cavity, which extends from the top surface towards the growth substrate down to the first AlGaAs layer, is carried out in such a way that the bottom surface of the cavity is formed by the AlGaAs interlayer. The cavity can be created, in particular, by means of a selective etching process (AlGaAs layers are etched, but the AlGaAs interlayer is not). For selective etching, for example, an aqueous etching medium based on sulfuric acid and hydrogen peroxide can be used.

[0064] BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Further aspects and embodiments according to the proposed principle will be revealed in relation to the various embodiments and examples, which are described in detail in conjunction with the accompanying drawings.

[0066] Figures 1A to IE show steps of a method for manufacturing a light-emitting device according to the proposed principle;

[0067] Figures 2A to 21 show further steps of a method for manufacturing a light-emitting device according to the proposed principle;

[0068] Figures 3A to 3M show further steps of a method for manufacturing another embodiment of a light-emitting device according to the proposed principle;

[0069] Figures 4A to 4Q show steps of a method for manufacturing a further embodiment of a light-emitting device according to the proposed principle; and

[0070] Fig. 5 shows another embodiment of a light-emitting device according to the proposed principle. DETAILED DESCRIPTION

[0071] The following embodiments and examples illustrate various aspects and their combinations according to the proposed principle. The embodiments and examples are not always to scale. Likewise, various elements may be enlarged or reduced to highlight individual aspects. It is understood that the individual aspects and features of the embodiments and examples shown in the figures can readily be combined without affecting the principle of the invention. Some aspects have a regular structure or shape. It should be noted that in practice, minor deviations from the ideal shape may occur without contradicting the inventive idea.

[0072] Furthermore, the individual figures, features, and aspects are not necessarily depicted at the correct size, and the proportions between the individual elements may not be entirely accurate. Some aspects and features are emphasized by being shown enlarged. However, terms such as "above," "below," "below," "larger," "smaller," and the like are correctly represented in relation to the elements in the figures. Thus, it is possible to deduce such relationships between the elements from the illustrations.

[0073] Figures 1A to IE show first steps of a method for fabricating a light-emitting device 1 according to some aspects of the proposed principle. In a first step, shown in Figure 1A, a semiconductor layer stack 2 is provided on a growth substrate 6. The semiconductor layer stack 2 comprises a first AlGaAs layer 3 of a first conductivity type, an active region 5, and a second AlGaAs layer 4 of a second conductivity type. In the case shown, the semiconductor layer stack 2 also includes an InGaAlP layer 7, which is formed on the growth substrate 6 between the growth substrate 6 and the first AlGaAs layer 3. The first conductivity type is, in particular, an n-type and the second conductivity type is a p-type. The first layer 3 can thus be an n-type semiconductor layer and the second layer 4 can be a p-type semiconductor layer.The active region 5 and in particular the quantum well (s) contained therein can be designed to emit light in the infrared range when supplied with a corresponding current.

[0074] The semiconductor layer stack 2 is then structured, as shown in Fig. 1B, starting from a top surface 11a, leaving a first section 17a of the semiconductor layer stack 2 and removing a second section 17b of the semiconductor layer stack 2 adjacent to the first section 17a. This structuring results in exposed side surface sections of the first layer 3, the active region 5, and the second layer 4, forming a first side surface 11c of the semiconductor layer stack 2.

[0075] In a further step, as shown in Figure IC, an InGaAlP growth layer 16 is grown onto the resulting structure, and in particular at least onto the first side surface 11c and the top surface 11a. The InGaAlP growth layer 16 can passivate defects on the etched side surfaces and block charge carriers with high energy barriers to prevent diffusion from the core of the active region of a light-emitting part of the semiconductor layer stack 2 to the first side surface 11c. This reduces the NRR in the active region 5 and the subsequent final light-emitting device.

[0076] The InGaAlP growth layer 16 is subsequently structured, as shown in Fig. ID, to expose an area of ​​the top surface 11a on which, as shown in Fig. IE, a second contact layer 9, e.g., of a TCO, is provided, which is in electrically conductive contact with the second AlGaAs layer 4. Figures 2A to 21 show further steps of a method for producing a light-emitting device 1 according to some aspects of the proposed principle, which may follow the steps described above.

[0077] As shown in Figure 2A, a first dielectric layer 15a is applied over the entire structure, and in particular over the entire InGaAlP growth layer 16 and the second contact layer 9. The first dielectric layer 15a serves to passivate the InGaAlP growth layer 16 and to prevent short circuits within the subsequent light-emitting device. Subsequently, as shown in Figure 2B, the first dielectric layer 15a is structured to expose areas of the second contact layer 9. A second contact element 14b, in the form of another contact layer, is then applied to the existing structure, as shown in Figure 2C, which electrically contacts the second contact layer 9.The second contact element 14b is formed by a metal and extends along the first side surface 11c to provide an underside reflector for the light-emitting device 1 with the desired optical properties.

[0078] The structure is then bonded to a support substrate 18, as shown in Figure 2D. The support substrate 18 can, for example, be or comprise an integrated circuit for controlling the light-emitting device 1 and can thus be connected to the second contact element 14b, for example, by means of electrical contacts (not shown).

[0079] Subsequently, as shown in Fig. 2E, the growth substrate 6 is removed and the InGaAlP layer 7 is removed, e.g. by means of a CMP process or by means of wet chemical etching (see Fig. 2F), so that a flat underside 11b of the semiconductor layer stack 2 opposite the top side 11a is exposed.

[0080] The underside 11b is subsequently structured (see Fig. 2G) in the area of ​​a light-emission window to provide an optically effective structure 19. As shown in Figure 2H, a further structuring process then takes place to separate a light-emitting section and a section of the semiconductor layer stack 2 associated with a light-emitting device from the remaining sections of the semiconductor layer stack. This further structuring step of the semiconductor layer stack 2 creates a second side surface 11d adjacent to the first side surface 11c, extending from the underside 11d. The resulting second side surface 11d comprises a portion of the first AlGaAs layer 3 and extends from the first side surface 11c to the underside 11b of the semiconductor layer stack 2.

[0081] On the underside 11b, a first contact element 14a is arranged, which is electrically coupled to the first AlGaAs layer 3. The first contact element 14a consists of an absorbing or reflective material, which optionally also forms a reflective structure and surrounds the semiconductor layer stack 2, and in particular a light-emission window of the semiconductor layer stack 2, in a circumferential direction U. In an embodiment not shown, the first contact element can also be arranged as a kind of comb structure on the underside 11b and be coupled to that of the first AlGaAs layer 3. The comb structure can, for example, consist of an absorbing or reflective material and be configured to electrically connect the first AlGaAs layer 3 over a large area, while at the same time minimizing the area covered by the comb structure on the underside 11b.

[0082] The first contact element 14a, together with the second contact element 14b, forms a mirror, in particular a parabolic mirror, for the light generated in the semiconductor layer stack 2. By means of the combined mirror, the light generated in the semiconductor layer stack 2 can be coupled out of the light-emitting device 1 in an improved manner, and focusing the light into a smaller solid angle is also possible.

[0083] The first contact element 14a can be configured as a metallic grid surrounding the light-emitting window of the semiconductor layer stack 2 in the circumferential direction U. In particular, the first contact element 14a can be configured as a metallic grid comprising an element surrounding the light-emitting window of the semiconductor layer stack 2 in the circumferential direction U, and comprising webs or remnants of webs connecting elements surrounding the light-emitting window of the semiconductor layer stack 2 in the circumferential direction U. Due to its conductivity, the metallic grid, together with the second contact element 14b, can be used to electrically connect the light-emitting device 1 to a power source.

[0084] Figures 3A to 3M show further steps of a method for producing another embodiment of a light-emitting device 1 according to some aspects of the proposed principle, which can follow the steps described in Figures 1A to IE. However, a difference compared to the embodiment described in Figures 1A to IE is that the growth substrate 6 has leveling layers adjacent to the InGaAlP layer 7.

[0085] First, as shown in Figure 3A, a further structuring process is carried out to separate a light-emitting section and a section of the semiconductor layer stack 2 associated with a light-emitting device from the remaining sections of the semiconductor layer stack. This further structuring step of the semiconductor layer stack 2 creates a second side surface 11 ld adjacent to the first side surface 11c. The resulting second side surface 11 ld comprises part of the first AlGaAs layer 3 and the InGaAlP layer 7 and extends from the first side surface 11c towards the growth substrate 6. This further structuring step also etches through the InGaAlP growth layer 16, so that its etched edges lie in a plane with the second side surface 11 ld.

[0086] As shown in Figure 3B, a first dielectric layer 15a is then applied over the entire structure, and in particular over the entire InGaAlP growth layer 16, the second contact layer 9, and the second side surface 11d. The first dielectric layer 15a serves to passivate the InGaAlP growth layer 16 and to prevent short circuits within the subsequent light-emitting device. Subsequently, as shown in Figure 3C, the first dielectric layer 15a is structured to expose areas of the second contact layer 9. A second contact element 14b, in the form of another contact layer, is then applied to the existing structure, as shown in Figure 3D, which electrically contacts the second contact layer 9.The second contact element 14b is formed by a metal and forms an underside reflector for the light-emitting device 1 in order to reflect light emitted in the direction of the second contact element 14b back towards a subsequent light-emitting surface.

[0087] As shown in Figure 3E, a sacrificial layer 12 is then applied to the structure. This layer is structured, as shown in Figure 3F, to expose an area of ​​the second contact element 14b. The structure is then encapsulated in a potting layer 13 (see Figure 3G) or bonded to a temporary support (not shown) to detach the growth substrate 6, as shown in Figures 3H to 3J. This process exposes the InGaAlP layer 7, for example, by means of a CMP process, thus providing a flat bottom surface 11b of the semiconductor layer stack 2 opposite the top surface 11a. In this process, the sacrificial layer 12 is also exposed, making it accessible for a later step of removing the sacrificial layer 12.

[0088] On the underside, as shown in Fig. 3K, a first contact layer 8 is then applied, which is in electrically conductive connection to the InGaAlP layer 7 or the first AlGaAs layer 3. On the underside 11b or the first contact layer 8, a first contact element 14a, in particular made of a TCO, is then provided (see Fig. 3L) and can be used together with the second contact element 14b to electrically connect the light-emitting device 1 to a power source.

[0089] As shown in Fig. 3M, the sacrificial layer 12 is then removed, for example by dissolving or etching it, so that the light-emitting device 1 is connected to the second contact element 14b in the illustrated embodiment only via one or more small retaining pins (s) formed by the potting layer 13. The illustrated light-emitting device 1 can then be lifted off, for example by means of a punch, and transferred to a target substrate.

[0090] Figures 4A to 4Q show steps of a method for producing a further embodiment of a light-emitting device 1 according to the proposed principle. In contrast to the embodiment shown in Figures 3A to 3M, the light-emitting device 1 resulting from the method described in Figures 4A to 4Q is a horizontally contactable component. In a first step, shown in Figure 4A, a semiconductor layer stack 2 is provided on a growth substrate 6. The semiconductor layer stack 2 comprises a first AlGaAs layer 3 of a first conductivity type, an active region 5, and a second AlGaAs layer 4 of a second conductivity type.In the illustrated case, the semiconductor layer stack 2 also includes an InGaAlP layer 7, which is formed on the growth substrate 6 between the growth substrate 6 and the first AlGaAs layer 3, and an AlGaAs intermediate layer 23, which is formed in the first AlGaAs layer 3 between the InGaAlP layer 7 and the active region.

[0091] The semiconductor layer stack 2 is then structured, as shown in Fig. 4B, starting from a top surface 11a, leaving a first section 17a of the semiconductor layer stack 2 and removing a second section 17b of the semiconductor layer stack 2 adjacent to the first section 17a. This structuring results in exposed side surface sections of the first AlGaAs layer 3, the active region 5, and the second AlGaAs layer 4, forming a first side surface 11c of the semiconductor layer stack 2. Simultaneously, a cavity 20 is created in the semiconductor layer stack 2, which also extends from the top surface 11a through the second AlGaAs layer 4 and the active region 5 to the first AlGaAs layer 3. However, the depth of the first structuring, which leads to the cavity 20 and the first side surface 11c, is chosen such that it stops before reaching the AlGaAs intermediate layer 23.

[0092] In a further step, as shown in Figure 4C, an InGaAlP growth layer 16 is grown onto the resulting structure, and in particular at least onto the first side surface 11c, the inner surfaces of the cavity 20, and the top surface 11a. The InGaAlP growth layer 16 can passivate defects on the etched side surfaces and block charge carriers with high energy barriers to prevent diffusion from the core of the active region of a light-emitting part of the semiconductor layer stack 2 to the first side surface 11c. This reduces the NRR in the active region 5 or the subsequent final light-emitting device. The InGaAlP growth layer 16 is then patterned to expose a region of the top surface 11a on which, as shown in Figure 4D, a second contact layer 9, e.g., from a TCO, which is in electrically conductive contact with the second AlGaAs layer 4.

[0093] Subsequently, as shown in Fig. 4E, the InGaAlP growth layer 16 in the cavity 20 is structured in the area of ​​a bottom surface 21 of the cavity 20, and the cavity 20 is deepened by selective etching until the AlGaAs intermediate layer 23 is reached. The resulting “new” bottom surface 21 of the cavity 20 is accordingly formed by the AlGaAs intermediate layer 23.

[0094] On the base surface 21, a first contact layer 8 is then applied, as shown in Fig. 4 F, which is in electrically conductive connection to the AlGaAs intermediate layer 23 or the first AlGaAs layer 3.

[0095] Subsequently, as shown in Figure 4G, a further structuring process is carried out to separate a light-emitting section and a section of the semiconductor layer stack 2 associated with a light-emitting device from the remaining sections of the semiconductor layer stack. This further structuring step of the semiconductor layer stack 2 creates a second side surface lld adjacent to the first side surface 11c. The resulting second side surface lld comprises a portion of the first AlGaAs layer 3, the AlGaAs intermediate layer 23, and a portion of the InGaAlP layer 7, and extends from the first side surface 11c towards the growth substrate 6. This further structuring step also etches through the InGaAlP growth layer 16, so that its etched edges lie in a plane with the second side surface lld.

[0096] As shown in Figure 4H, a first dielectric layer 15a is then applied over the entire structure, and in particular over the entire InGaAlP growth layer 16, the first and second contact layers 8, 9, and the second side surface 11121 ...The first and second dielectric layers 15a, 15b are structured in such a way that areas of the first and second contact layers 8, 9 are exposed.

[0097] As shown in Fig. 4K, a first and a second contact element 14a, 14b, each in the form of a further contact layer, are then applied to the existing structure. These contact elements electrically contact the first and second contact layers 8, 9, but are separated from each other. The first and second contact elements 14a, 14b are each formed by a metal and together they form an underside reflector for the light-emitting device 1 to reflect light emitted towards the first and second contact elements 14a, 14b back towards a subsequent light-emitting surface.

[0098] As shown in Figure 4L, a structured sacrificial layer 12 is then applied to the structure, exposing a region of the first and second contact elements 14a and 14b, respectively. The structure is then encapsulated in a potting layer 13 (see Figure 4M) or bonded to a temporary support (not shown) in order to detach the growth substrate 6, as shown in Figures 4N to 4P, and expose the InGaAlP layer 7, for example, by means of a CMP process, thus providing a flat bottom surface 11b of the semiconductor layer stack 2 opposite the top surface 11a. In this process, the sacrificial layer 12 is also exposed, making it accessible for a later step of removing the sacrificial layer 12.

[0099] As shown in Fig. 4Q, the sacrificial layer 12 is then removed, for example by dissolving or etching it, so that the light-emitting device 1 is connected to the first and second contact elements 14a, 14b in the illustrated embodiment only via small retaining pins formed by the potting layer 13. The illustrated light-emitting device 1 can then be lifted off, for example by means of a punch, and transferred to a target substrate.

[0100] Figure 5 shows another embodiment of a light-emitting device 1 according to the proposed principle. However, the light-emitting device 1 does not have the AlGaAs intermediate layer 23 shown in Figures 4A to 4Q, but rather the cavity 20 extends to the InGaAlP layer 7, which forms the bottom surface 21 of the cavity 20. The InGaAlP layer 7 accordingly acts both as the underside 11b of the semiconductor layer stack 2, i.e., the light-emitting surface of the light-emitting device 1, and as a current distribution layer for contacting the first AlGaAs layer 3. The InGaAlP layer 7 has the advantage that the cavity can be produced very precisely up to the InGaAlP layer 7 by selective etching. [REFERENCE SYMBOL LIST]

[0101] 1 light-emitting device

[0102] 2 semiconductor layer stacks

[0103] 3 first AlGaAs layer

[0104] 4 second AlGaAs layer

[0105] 5 active area

[0106] 6 Growth substrate

[0107] 7 InGaAlP layer

[0108] 8 first contact layer

[0109] 9 second contact layer

[0110] 10 reflective layers

[0111] 11a Top

[0112] 11b Underside

[0113] 11c first face lld second face

[0114] 12a, 12b Sacrifice layer

[0115] 13 Potting layer

[0116] 14a, 14b Contact element

[0117] 15a, 15b dielectric layer

[0118] 16 InGaAlP growth layer

[0119] Sections 17a and 17b

[0120] 18 Carrier substrate

[0121] 19 optically effective structures

[0122] 20 cavities

[0123] 21 floor area

[0124] 22 side surface

[0125] 23 AlGaAs interlayer

[0126] U circumferential direction

Claims

PATENT CLAIMS 1. Light-emitting device (1), in particular pLED, comprising: a semiconductor layer stack (2) of at least one first layer (3) of a first conductivity type, a second layer (4) of a second conductivity type, an active AlGaAs region (5) arranged between the first and the second layer (3, 4) and configured to emit light in the infrared range, a top (11a), a bottom (11b) opposite the top (11a), and a first side surface (11c) extending from the top (11a) towards the bottom (11b); and an InGaAlP growth layer (16) comprising the first side surface (llc) and covers at least part of the top surface (11a); wherein the first side surface (11c) comprises the second layer (4), the active area (5) and at least part of the first layer (3).

2. The light-emitting device according to claim 1, wherein the semiconductor layer stack (2) has a second side surface (11d) comprises which adjoins the first side surface (11c) and is laterally offset from it, wherein the second side surface (11d) comprises at least a part of the first layer (3) and in particular extends from the first side surface (11c) to the underside (11b), and wherein the second side surface (11d) is in particular free of the InGaAlP growth layer (16).

3. The light-emitting device according to one of the preceding claims , wherein a first contact layer (8) is arranged on the underside (11b) which electrically contacts the first layer (3) of the semiconductor layer stack (2), and the light-emitting device is designed in particular as a vertically contactable component.

4. The light-emitting device according to one of the preceding claims, wherein a second contact layer (9) is arranged on the top surface (11a) which electrically contacts the second layer (4) of the semiconductor layer stack (2).

5. The light-emitting device according to one of the preceding claims, further comprising a first dielectric layer (15a) arranged on at least one of the following areas: on the InGaAlP wax layer (16) opposite the first side surface (11c); on the InGaAlP wax layer (16) opposite the top surface (11a); on the second contact layer (9) opposite the top surface (11a), in particular exposing a contact area of ​​the second contact layer (9); and on the second side surface (11d).

6. The light-emitting device according to claim 5, further comprising a reflective layer (10) arranged on the first dielectric layer (15a) and extending along the first side surface (11c) and the top surface (11a), wherein the reflective layer (10) is in particular electrically insulated from the first and the second layer (3, 4).

7. The light-emitting device according to claim 6, further comprising a second dielectric layer (15b) arranged on the reflective layer (10) and together with the first dielectric layer (15a) encapsulates the reflective layer (10).

8. The light-emitting device according to one of the preceding claims, wherein the semiconductor layer stack (2) has a cavity (20) extending from the top (11a) towards the bottom (11b) into the first layer (3); wherein a first contact layer (8) is arranged on a bottom surface (21) of the cavity (20), which electrically contacts the first layer (3) of the semiconductor layer stack (2); wherein at least areas of side surfaces (22) of the cavity (20) are covered by the InGaAlP growth layer (16); and wherein the light-emitting device (1) is in particular designed as a horizontally contactable component.

9. The light-emitting device according to one of the preceding claims, wherein the semiconductor layer stack (2) has an InGaAlP layer (7) between the first layer (3) and the bottom (11b); and wherein the InGaAlP layer (7) forms the bottom (11b).

10. The light-emitting device according to claim 9, wherein the bottom surface (21) of the cavity (20) is formed by the InGaAlP layer (7).

11. The light-emitting device according to any one of claims 1 to 9, wherein the semiconductor layer stack (2) has an AlGaAs interlayer (23) within the first layer (3), wherein the first layer (3) is formed by an AlGaAs layer and the AlGaAs interlayer (23) has a lower Al content than the first AlGaAs layer (3); and wherein, in particular, the bottom surface (21) of the cavity (20) is formed by the AlGaAs interlayer (23).

12. Method for manufacturing a light-emitting device (1) , comprising the steps: Providing a semiconductor layer stack (2) comprising at least: a first layer (3) of a first conductivity type on a growth substrate (6), a second layer (4) of a second conductivity type, and an active AlGaAs region (5) arranged between the first and second layers (3, 4) and configured to emit light in the infrared range; Structuring the semiconductor layer stack (2) , wherein at least one first section (17a) of the semiconductor layer stack (2) remains and a second section (17b) of the semiconductor layer stack adjacent to the at least one first section (17a) (2) is removed, such that the at least one first section (17a) comprises a first side surface (11c) extending from a top surface (11a) of the semiconductor layer stack (2) towards the growth substrate (6), wherein the first side surface (llc) the second layer (4), the active area (5) and at least part of the first layer (3); and Growth of an InGaAlP growth layer (16) on the first side surface (11c) and at least a part of the top surface (11a) .

13. The method of claim 12, further comprising further structuring the semiconductor layer stack (2) by forming a second side surface (11d) adjacent to the first side surface (11c); wherein the first side surface (11c) and the second side surface (11d) are laterally offset from each other; and wherein the second side surface (11d) comprises a part of the first layer (2) and extends in particular from the first side surface (11c) to the growth substrate (6) or to a bottom surface (Hb) of the semiconductor layer stack (2) opposite the top surface (11a).

14. Method according to claim 13, wherein the growth step is carried out prior to further structuring the semiconductor layer stack (2).

15. Method according to any one of claims 12 to 14, further comprising a step of providing a first dielectric layer (15a) on at least one of the following areas: on the InGaAlP growth layer (16) opposite the first side surface (11c); on the InGaAlP growth layer (16) opposite the top surface (11a); on the second contact layer (9) opposite the top surface (11a), in particular exposing a contact area of ​​the second contact layer (9); and on the second side surface (11d).

16. The method of claim 15, further comprising providing a reflective layer (10) on the first dielectric layer (15a) extending along the first side surface (11c) and the top surface (11a), wherein the reflective layer (10) is in particular electrically insulated from the first and the second layer (3, 4); and optionally further comprising providing a second dielectric layer (15b) on the reflective layer (10) which, together with the first dielectric layer (15a), encapsulates the reflective layer (10).

17. A method according to any one of claims 12 to 16, wherein the step of structuring the semiconductor layer stack (2) comprises creating a cavity (20) extending from the top surface (11a) towards the growth substrate (6) into the first layer (3); and wherein the step of growing the InGaAlP growth layer (16) comprises covering at least areas of side surfaces (22) of the cavity (20) by means of the InGaAlP growth layer (16); further comprising providing a first contact layer (8) on a bottom surface (21) of the cavity (22) which electrically contacts the first layer (3) of the semiconductor layer stack (2).

18. Method according to any one of claims 12 to 17, further comprising providing a second contact layer (9) on the top surface (11a) which electrically contacts the second layer (3) of the semiconductor layer stack (2).

19. A method according to any one of claims 12 to 18, further comprising at least one of the following steps: Applying a first contact element (14a) which is electrically coupled to the first contact layer (8); Applying a second contact element (14b) which is electrically coupled to the second contact layer (9); Applying a sacrificial layer (12) to at least one of the first dielectric layer (15a), the second dielectric layer (15b), the first contact element (14a), the second contact element (14b), the InGaAlP growth layer (16), and the semiconductor layer stack (2); Applying a potting layer (13) , in particular onto the sacrificial layer (12) , in particular such that the potting layer (13) is in direct contact with at least one of the first dielectric layer (15a) , the second dielectric layer (15b) , the first contact element (14a) , the second contact element (14b) , the InGaAlP wax layer (16) , and the semiconductor layer stack (2); Removal of the growth substrate (6) ; Exposing one of the bottom surfaces (11b) of the semiconductor layer stack (2) opposite the top surface (11a) ; Structuring the underside (11b) to create an optically effective structure (19) ; Applying an optical element to the underside (11b) ; Applying a first contact layer (8) to the underside (11b) ; Removal of the sacrificial layer (12) ; and Lifting a light-emitting device (1) from the potting layer (13) .

20. Method according to any one of claims 12 to 19, wherein the step of providing the semiconductor layer stack (2) the provision of an InGaAlP layer (7) between the first layer (3) and the growth substrate (6); wherein the method further comprises exposing a bottom surface (11b) of the semiconductor layer stack (2) opposite the top surface (11a), wherein the bottom surface (11b) is formed by the InGaAlP layer (7); and wherein, in particular, the bottom surface (21) of the cavity (20) is formed by the InGaAlP layer (7).

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