Light-emitting device and method for producing a light-emitting device

Abstract

The invention relates to a light-emitting device comprising a semiconductor layer stack having a first layer of a first conductivity type, a second layer of a second conductivity type, and an active region arranged between the first and second layers and designed to generate light of a first wavelength. In addition, the light-emitting device comprises a first contact layer, which is arranged on an underside of the semiconductor layer stack and electrically contacts the second layer; a second contact layer, which is substantially transparent to light of the first wavelength, is arranged on a top side of the semiconductor layer stack opposite the underside and electrically contacts the first layer; a first electrical contact electrically contacting the first contact layer; a first dielectric layer covering at least one lateral surface of the semiconductor layer stack that connects the top side and the underside; and a converter layer arranged on or above the second contact layer and configured to convert light of the first wavelength into light of a second wavelength. The converter layer completely covers a central region, via which light of the first wavelength generated in the semiconductor layer stack is coupled into the converter layer, and the central region is spaced apart in a plane parallel to the top side from an outer edge, lying in the plane, of the light-emitting device by at least 0.1 µm.

Description

[0001] Light-emitting device and method for manufacturing a light-emitting device

[0002] The present application claims priority over German patent application No. 10 2024 117 755 1 of 24 June 2024, the disclosure content of which is hereby incorporated into the present application by reference.

[0003] The present invention relates to a light-emitting device, in particular a p-LED with a converter layer, wherein the light-emitting device exhibits improved performance with respect to color homogeneity and light emission direction. Furthermore, the present invention relates to a method for manufacturing a light-emitting device.

[0004] BACKGROUND

[0005] Converting, for example, blue light emitted by a p-LED into white light is a common approach for various applications. It is advantageous if this is done as cost-effectively, as color-homogeneously as possible across location and beam angle, and as efficiently as possible.

[0006] Especially for applications where p-LEDs are to be placed in a transparent medium such as a glass window, the transmission of the transparent medium should be as high as possible, and thus the shading area (p-LED size including converter) should be as small as possible. Furthermore, for most applications, light emission in only one direction is desired, which is why back-emission from the p-LED should be avoided.

[0007] To date, p-LEDs are known that feature side and back mirrors to prevent back-emission. To convert the light emitted by such p-LEDs, the p-LEDs are transferred, for example, from a fabrication wafer to an intermediate substrate on which a light conversion layer is applied, completely encapsulating the p-LEDs. To ensure a homogeneous color across the location and emission angle of the emitted light, the conversion layer is positioned to extend over the entire p-LED, so that light emitted at a small angle to the side of the p-LED is also converted.

[0008] However, such p-LEDs encapsulated in a converter are very large, and additional processes are required to apply the conversion layer to the p-LEDs on the intermediate substrate.

[0009] It is therefore an object of the present application to counteract at least one of the aforementioned problems and to provide a light-emitting device with a converter layer, wherein the light-emitting device exhibits improved performance with regard to color homogeneity and light emission direction. Furthermore, a method for manufacturing such a light-emitting device is to be provided.

[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' concept involves physically reducing or restricting the area where light from the epistructure of a pixel in a light-emitting device exits into a converter layer, such that a converter layer can be readily deposited in this restricted area at the wafer level using standard methods. By reducing or restricting a central area through which light from the light-emitting structure of the device is coupled into the converter layer, the converter layer can be made smaller, in particular smaller than the lateral dimensions of the light-emitting device itself. This makes it possible to deposit the converter layer using standard methods while the semiconductor layer stack is still on the manufacturing wafer and thus at the wafer level.In one aspect, a light-emitting device is provided that comprises a semiconductor layer stack. The semiconductor layer stack includes a first layer of a first conductivity type, a second layer of a second conductivity type, and an active region arranged between the first and second layers, which is configured to emit light of a first wavelength. The first layer can, for example, be an n-doped semiconductor layer, while the second layer can, for example, be a p-doped semiconductor layer. The two layers can thus form a pn junction, between which the active region is located. The active region can, for example, comprise a quantum well or multi-quantum well structure, or quantum dots.

[0013] The light-emitting device further comprises a first contact layer arranged on a bottom side of the semiconductor layer stack and electrically contacting the second layer. The light-emitting device also comprises a second contact layer arranged on a top side of the semiconductor layer stack opposite the bottom side and electrically contacting the first layer.

[0014] The light-emitting device further comprises a first electrical contact that electrically contacts the first contact layer, and a first dielectric layer that covers at least one side surface of the semiconductor layer stack connecting the top and bottom surfaces. The first dielectric layer may also cover at least parts of the bottom surface and / or the first contact layer and / or be located in certain areas between the first contact layer and the first electrical contact. Furthermore, the first dielectric layer may extend from the bottom surface along the side surface of the semiconductor layer stack, at least in certain areas, to the top surface of the semiconductor layer stack. The light-emitting device can be supplied with a current, for example, via the first electrical contact and the second contact layer.The first dielectric layer, on the other hand, can serve as passivation of the semiconductor layer stack and electrical insulation of the side faces of the semiconductor layer stack.

[0015] Furthermore, a converter layer is arranged on or above the second contact layer, designed to convert light of the first wavelength into light of a second wavelength. The converter layer can be formed from, for example, Ce:YAG, x:YAG, nitride, in-siloxane, a silicon matrix with light-conversion particles, or another suitable light-conversion material, or it can comprise such a material. The converter layer can, for example, comprise or consist of quantum dots, which are optionally embedded in a matrix material. Alternatively, the converter layer can also comprise, for example, minute phosphorus crystals (crystallites) or perovskites, which are / can be embedded in a matrix material.

[0016] The lateral dimensions of the converter layer are smaller than the lateral dimensions of the light-emitting device, while simultaneously completely covering a central area of ​​the light-emitting device, through which light from the semiconductor layer stack is coupled into a converter layer. This allows the converter layer to be easily applied locally on or above the second contact layer, ensuring sufficient distance from the outer edges of the light-emitting device while still completely covering the central area. In particular, the central area is effectively limited to increase the color homogeneity and light emission direction of the light-emitting device, to ensure the manufacturability of such a device, and at the same time to minimize the footprint of the light-emitting device encompassing the converter layer.

[0017] To ensure that the central region where light exits the semiconductor layer stack into a converter layer is smaller than the lateral dimensions of the light-emitting device, an optical aperture is arranged between the converter layer and the active region, exposing only a central region of the light-emitting device. This allows the light generated in the active region to be coupled into the converter layer only through this central region. The converter layer is arranged such that it covers at least the central region and, in particular, extends beyond it, but does not need to extend over or even encapsulate the entire light-emitting device.In this way, the area in which light escapes from the semiconductor layer stack into the converter layer is effectively limited in order to increase the color homogeneity and light emission direction of the light-emitting device while keeping the footprint of the light-emitting device small.

[0018] To ensure that the central area where light from the semiconductor layer stack is coupled into the converter layer is smaller than the lateral dimensions of the light-emitting device, an alternative or additional material layer can be provided that covers the side faces of the semiconductor layer stack in addition to the first dielectric layer. This material layer allows the light-emitting device to be thickened laterally, so that the semiconductor layer stack, or the central area through which light is coupled from the semiconductor layer stack into the converter layer, is physically reduced in size relative to the lateral dimensions of the entire light-emitting device as the material layer thickens.This makes it possible for the converter layer to at least cover the central area and, in particular, to extend beyond the central area, but does not have to extend over the entire light-emitting device or even encapsulate the entire light-emitting device. In this way, the area in which light can escape from the semiconductor layer stack into the converter layer is effectively limited relative to the lateral dimensions of the entire light-emitting device, in order to increase the color homogeneity and the light emission direction of the light-emitting device while simultaneously keeping the footprint of the light-emitting device small. The term "central" area in this context is not to be understood as an area that must be located centrally with respect to the semiconductor layer stack, but can also be located away from the outer perimeter of the light-emitting device, e.g.with different distances to opposite outer edges of the light-emitting device.

[0019] In some aspects, the central region is spaced at least 1 pm, at least 3 pm, 5 pm, or at least 10 pm from an outer edge of the light-emitting device lying in that plane, in a plane parallel to the top surface. In particular, the central region in a plane parallel to the top surface may have an area that is at least 5%, 10%, or 15% smaller than a cross-sectional area of ​​the entire light-emitting device in that plane. At the same time, however, the entire central region is completely covered by the converter layer, at least in the sense that a projection of the converter layer into the plane parallel to the top surface is larger than or at least equal to the central region in that plane.

[0020] The light-emitting device is designed, in particular, as a vertically contactable component, with a second electrical contact provided on the same side as the top surface. For example, the optical aperture can be made of a conductive material and serve as the second electrical contact, or another conductive material can be provided on the second contact layer, serving as a second electrical contact. Likewise, the second contact layer itself can also serve as an electrical contact, through which the light-emitting device can be electrically supplied together with the first electrical contact. The light-emitting device can thus be electrically contactable from two opposite sides.

[0021] The light-emitting device can be, in particular, a small light-emitting component / element such as a small LED or p-LED. A p-LED, in particular, can be a very small LED with edge lengths of up to 40 pm, up to 10 pm, up to 5 pm, or even less. Such small LEDs can be free of a growth substrate and require special handling and processing to improve their internal quantum efficiency (IQE) and light-out coupling efficiency. One exemplary approach to improving the IQE of the p-LED is to cover the side faces of the semiconductor layer stack with a regrowth layer. Such a regrowth layer can, for example, be provided between the first dielectric layer and the side faces of the semiconductor layer stack.

[0022] In some aspects, a second dielectric layer is arranged between the second contact layer and the converter layer, whereby the second dielectric layer, in particular, electrically isolates the converter layer from the second contact layer. The second dielectric layer can, in particular, be a thin layer applied by ALD (atomic layer deposition), which prevents an electrical voltage from being applied to the converter layer.

[0023] In some aspects, the light-emitting device further comprises a protective layer that covers the converter layer and, in particular, encapsulates the converter layer together with the second contact layer. The protective layer can, firstly, protect the converter layer from external influences, such as downstream processing steps for the light-emitting device or external influences acting on the light-emitting device in a final product. Secondly, the protective layer can be formed by a DBR and / or be designed to be reflective or absorbent, at least for light of the first wavelength, in order to achieve complete conversion of the first-wavelength light generated by the semiconductor layer stack into light of the second wavelength, or to prevent first-wavelength light from escaping the light-emitting device.For example, the protective layer can be formed by an AI2O3 layer, or at least include an AI2O3 layer as the outermost layer.

[0024] In some aspects, the material layer covers the first dielectric layer or forms the outermost layer of the light-emitting device, thereby forming its outer edge. In particular, a projection of the material layer in the plane parallel to the top surface can form the outer edge of the light-emitting device, from which the central region is spaced. Alternatively, the second contact layer can also form the outer edge of the light-emitting device, from which the central region is spaced, especially if the second contact layer is substantially flush with the material layer.

[0025] In some aspects, the material layer is designed to be reflective or at least includes a reflective layer. For example, the material layer can provide a reflective structure configured to reflect first and / or second wavelength light emitted through the side faces and bottom of the semiconductor layer stack towards the top of the semiconductor layer stack. For example, the reflective structure surrounds the first electrical contact. In particular, the reflective structure, together with the first electrical contact, can be configured to reflect the light generated in the active region towards the top, thereby improving the light emission efficiency of the light-emitting device.A potential loss of luminance can be minimized, in particular, by improving the reflectivity at the side face and / or the underside of the semiconductor layer stack. The reflectivity of the reflective structure at the side face and / or underside can be improved, for example, by choosing a lower-loss material for the reflective structure (e.g., aluminum or silver) and additionally applying a single-layer coating (e.g., SiO₂) thick enough to allow total internal reflection with minimal loss. Alternatively, a multi-layer coating can be applied that acts as a distributed Bragg mirror to improve the reflectivity across all angles of incidence.

[0026] In some aspects, the material layer has a thickness of at least 0.05 pm, 0.5 pm, or 2 pm. This material layer allows the light-emitting device to be thickened laterally, so that the semiconductor layer stack, or the central area through which light is coupled from the semiconductor layer stack into the converter layer, is physically reduced relative to the lateral dimensions of the entire light-emitting device as the material layer thickens. At the same time, however, the material layer must not be thicker than 5 pm in order to keep the footprint of the light-emitting device as small as possible despite the thickening.

[0027] The optical aperture can consist, for example, of Al, Ag, a dielectric mirror, a metal and a dielectric mirror, or another material that is absorbing or reflecting at least the first wave light generated in the active area.

[0028] The optical aperture can be located, for example, between the second contact layer and the converter layer, particularly on the second contact layer itself. However, the optical aperture can also be located between the top surface and the second contact layer, for example, on the top surface. It is also possible for the optical aperture to be wholly or partially embedded or integrated into the second layer.

[0029] The optical aperture is arranged and designed in such a way that it at least partially defines the central region. "At least partially" means that the optical aperture can be designed such that the central region is defined only partially by the optical aperture and partially by the outer dimensions of the semiconductor layer stack, or that the central region is defined completely by the optical aperture.

[0030] In some aspects, the optical aperture is arranged and / or designed asymmetrically or off-center relative to the semiconductor layer stack, such that the central area, in particular, is also arranged or designed off-center relative to the semiconductor layer stack. In other aspects, however, the optical aperture is arranged and / or designed point- and / or axis-symmetrically relative to the semiconductor layer stack, such that the central area, in particular, is arranged or designed centrally and point- and / or axis-symmetrically relative to the semiconductor layer stack.

[0031] For example, the optical aperture can be in the form of a strip extending along the outer edge of the light-emitting device, or it can be in the form of several strips extending along adjacent and / or opposite outer edges of the light-emitting device. It is also possible for the optical aperture to be annular or otherwise shaped to appropriately delimit the central area.

[0032] In some aspects, the top surface exhibits a roughened structure, particularly in the central region. This improves the coupling of light, especially in the central region, into the converter layer. For example, this can further limit the area where light is coupled from the semiconductor stack into the converter layer. The roughened structure can include, for example, a nanostructure, a cylindrical roughening, or another roughened structure that increases the coupling efficiency of the top surface.

[0033] In some aspects, the top surface comprises a roughened structure in, for example, a sub-region of the central area, as well as a non-roughened structure surrounding this sub-region. Due to the different refractive indices of the semiconductor layer stack and the overlying material, the non-roughened area can act as a kind of reflector, especially for light incident on the top surface at shallow angles. This can further contribute to limiting the area where light exits the semiconductor layer stack into the converter layer.

[0034] In some aspects, the first and / or second contact layer can, for example, comprise or consist of a transparent conductive oxide (TCO) such as indium tin oxide (ITO). The first and / or second contact layer can also, for example, comprise or consist of a transparent conductive oxide (TCO) such as indium tin oxide (ITO) in combination with a gold (Au)-germanium (Ge) alloy layer.

[0035] In some aspects, the first electrical contact can have a gold (Au), platinum (Pt), and / or titanium (Ti) layer, as well as a titanium (Ti), platinum (Pt), gold-indium-tin (AuInSn), NilnSn, AuSn, InSn, and / or gold (Au)-based solder material as the contact surface. According to another aspect, a method for manufacturing a light-emitting device is provided. The method can, in particular, 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.

[0036] According to some aspects, the process for manufacturing a light-emitting device comprises the following steps:

[0037] Providing a semiconductor layer stack comprising a first layer of a first conductivity type, a second layer of a second conductivity type, and an active region arranged between the first and second layers, configured to generate light of a first wavelength, on a growth substrate;

[0038] Structuring the semiconductor layer stack, thereby forming a bottom surface and side surfaces of the semiconductor layer stack that extend from the bottom surface in a direction away from the bottom surface;

[0039] Providing a first contact layer on the underside of the semiconductor layer stack, which electrically contacts the second layer;

[0040] Providing a first dielectric layer on the side surfaces;

[0041] Providing an initial electrical contact that establishes the first

[0042] Electrically contacted contact layer; removal of the growth substrate and exposure of a top surface of a separate light-emitting device opposite the bottom surface of the semiconductor layer stack;

[0043] Providing a second contact layer on the top side that electrically contacts the first layer; and

[0044] Providing a converter layer on or above the second contact layer; wherein the converter layer is configured to convert light of the first wavelength into light of a second wavelength; wherein the converter layer completely covers a central region through which light of the first wavelength generated by the semiconductor layer stack is coupled into the converter layer; and wherein the central region is spaced at least 0.1 pm apart in a plane parallel to the top surface from an outer edge of the light-emitting device lying in the plane.

[0045] To ensure that the central area through which light exits the semiconductor layer stack into the converter layer is smaller than the lateral dimensions of the light-emitting device, the method, according to some aspects, includes a further step of providing an optical aperture arranged between the converter layer and the active region, which exposes the central region so that light generated in the active region can only be coupled into the converter layer through the central region. It is then possible for the converter layer to at least cover the central region and, in particular, to extend beyond the central region, but need not extend over the entire light-emitting device or even encapsulate the entire light-emitting device.In this way, the area in which light escapes from the semiconductor layer stack into the converter layer is effectively limited, and the optical aperture at least partially defines the central area.

[0046] The optical aperture can, for example, be applied directly to the top surface using a lift-off process before the second contact layer is subsequently applied to the optical aperture and the top surface, or the optical aperture can be applied to the second contact layer using a lift-off process after the second contact layer has been applied to the top surface.

[0047] To ensure that the central area through which light exits the semiconductor layer stack into the converter layer is smaller than the lateral dimensions of the light-emitting device, the method can, according to some aspects, additionally or alternatively include a further step, namely the provision of a material layer that covers the first dielectric layer and, in particular, forms the outer edge of the light-emitting device. By means of this material layer, the light-emitting device can be thickened in the lateral direction, so that the semiconductor layer stack, or the central area through which light is coupled from the semiconductor layer stack into the converter layer, is physically reduced in size relative to the lateral dimensions of the entire light-emitting device as the material layer thickens.This makes it possible for the converter layer to at least cover the central area and, in particular, to extend beyond the central area, but does not have to extend over the entire light-emitting device or even encapsulate the entire light-emitting device. In this way, the area in which light can escape from the semiconductor layer stack into the converter layer is effectively limited with respect to the lateral dimensions of the entire light-emitting device, and the material layer at least partially defines the central area.

[0048] The material layer can, for example, be designed to be reflective or at least include a reflective layer. For example, the material layer, particularly together with the first electrical contact, can provide a reflective structure configured to reflect first and / or second wavelength light emitted by the side faces and the bottom of the semiconductor layer stack towards the top of the semiconductor layer stack. In some aspects, the method further includes providing a protective layer on the converter layer, wherein the protective layer covers the converter layer and, in particular, encapsulates the converter layer and, optionally, a second dielectric layer between the second contact layer and the converter layer together with the second contact layer.The protective layer can be applied, for example, via a lift-off process and serves two purposes: firstly, to protect the converter layer from external influences, such as downstream processing steps for the light-emitting device or external influences acting on the light-emitting device in a final product; and secondly, to be formed by a DBR and / or be designed to be reflective or absorbent, at least for light of the first wavelength, in order to achieve complete conversion of the first-wavelength light generated by the semiconductor layer stack into light of the second wavelength, or to prevent first-wavelength light from escaping the light-emitting device. For example, the protective layer can be formed by an A12O3 layer, or at least include an A12O3 layer as the outermost layer.However, other materials are also possible for the protective layer, for example a protective layer that can be produced via an ALD or CVD process.

[0049] In some aspects, the method further includes providing a second dielectric layer on the second contact layer, such that the second dielectric layer is positioned between the second contact layer and the converter layer after the converter layer has been applied. The second dielectric layer provides electrical isolation between the converter layer and the second contact layer. For example, the second dielectric layer can be a thin layer applied by ALD or CVD, which prevents an electrical voltage from being applied to the converter layer.

[0050] In some aspects, the process, particularly before the removal of the growth substrate, further includes the application of a sacrificial layer to the first dielectric layer or material layer and the first electrical contact. The sacrificial layer is applied specifically to the structure existing at the time of its application and covers, in particular, a structure opposite the growth substrate and created on the growth substrate. The sacrificial layer may be designed to be selectively removed at a later stage in order to detach separated light-emitting devices from a remaining support structure. The sacrificial layer may, for example, be a layer of SiÜ2 or Si, designed such that it can be selectively removed / etched in a later step to detach the subsequent light-emitting devices from the underlying structure.However, it is also possible that the sacrificial layer is formed by an organic material, especially a carbon-containing material.

[0051] Furthermore, the method can include applying a bonding layer to the sacrificial layer, wherein the bonding layer substantially covers the sacrificial layer. The bonding layer can, for example, fill gaps and cavities between several subsequent light-emitting devices and provide a flat surface on which a support substrate can be placed.

[0052] The sacrificial layer can, for example, be structured and partially expose the first dielectric layer or material layer and / or the first electrical contact, so that the compound layer applied to the sacrificial layer is in contact with the first dielectric layer or material layer and / or the first electrical contact. The interfaces between the compound layer and the first dielectric layer or material layer and / or the first electrical contact can, in particular, form the aforementioned support structure for one or more light-emitting devices.

[0053] In some aspects, the step of removing the growth substrate and exposing a top surface opposite the bottom of the semiconductor layer stack also includes simultaneously exposing the sacrificial layer, so that the sacrificial layer can be selectively removed over the exposed area without damaging the light-emitting device(s) and the interconnect layer. The light-emitting device(s) are then held only by the interconnect layer, in particular by retaining pins formed by the interconnect layer, and can subsequently be lifted from the substrate, for example, with a punch tool.

[0054] In some aspects, the converter layer provisioning step involves the large-area application of converter material to the exposed top surface(s) of one or more light-emitting devices, followed by structuring the converter material such that each light-emitting device is assigned a converter layer that completely covers a central area through which light of the first wavelength generated by the semiconductor layer stack is coupled into the converter layer, while simultaneously being sufficiently spaced from an outer edge of the light-emitting device. The structuring step can be performed, for example, by plasma etching.

[0055] BRIEF DESCRIPTION OF THE DRAWINGS

[0056] 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.

[0057] Fig. 1 shows a cross-sectional view of an embodiment of several light-emitting devices according to some aspects of the proposed principle during their manufacture; Figs. 2, 3A and 3B each show a cross-sectional view of another embodiment of several light-emitting devices according to some aspects of the proposed principle during their manufacture;

[0058] Figures 4A to 4F each show a top view of embodiments of a light-emitting device according to some aspects of the proposed principle; and

[0059] Figures 5A and 5B show two steps for further processing of a light-emitting device according to some aspects of the proposed principle.

[0060] DETAILED DESCRIPTION

[0061] 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.

[0062] Furthermore, the individual figures, features, and aspects are not necessarily shown 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," "above," "below," "below," "larger," "smaller," and the like are correctly represented in relation to the elements in the figures. Thus, it is possible to derive such relationships between the elements from the figures. Figure 1 shows a cross-sectional view of an embodiment of a light-emitting device 1 according to some aspects of the proposed principle. In particular, Figure 1 shows several light-emitting devices 1 during their manufacture, at a point when they are still held on a support substrate 24 by means of a sacrificial layer 21 or a bonding layer 22.The structure of the light-emitting devices 1 j is described below as an example, but only for one light-emitting device 1.

[0063] The light-emitting device 1 comprises a semiconductor layer stack 2 with a first layer 3 of a first conductivity type, a second layer 4 of a second conductivity type, and an active region 5 arranged between the first and second layers. The semiconductor layer stack 2 comprises a bottom surface 9 and inclined and stepped side surfaces 16 extending from the bottom surface 9 away from the bottom surface 9 to a top surface 11 opposite the bottom surface, defining the shape of the semiconductor layer stack 2.

[0064] On the underside 9, a first contact layer 7, in particular made of ITO, is arranged, which is electrically coupled to the second layer 4. The first contact layer 7 can in particular act as a current expansion layer to conduct a current applied to the first contact layer 7 via a first electrical contact 6 into the second layer 4.

[0065] The semiconductor layer stack 2 is covered / encapsulated along its side surfaces 16 by a first dielectric layer 19, which insulates and passivates the side surfaces 16. In the illustrated case, the first dielectric layer 19 also extends in some areas between the first contact layer 7 and the first electrical contact 6; however, the illustration is only to be understood as exemplary.

[0066] On the top surface 11 of the semiconductor layer stack 2, a second contact layer 18 is arranged, which is electrically coupled to the first layer 3. The second contact layer 18 is formed by a conductive transparent material, such as ITO, which is transparent at least to the light generated in the semiconductor layer stack 2.

[0067] A converter layer 10 is also arranged on the second contact layer 18. This converter layer is configured to convert light of a first wavelength generated by the semiconductor stack 2 into light of a second wavelength that differs from the first. A second dielectric layer 20 is formed between the converter layer 10 and the second contact layer 18, electrically isolating the converter layer 10 from the second contact layer 18. Furthermore, the converter layer 10 is covered or encapsulated with a protective layer 17 to protect it from external influences, and / or to achieve complete conversion of the light generated by the semiconductor stack 2, and / or to prevent emission of the light generated by the semiconductor stack 2 to the outside.

[0068] The converter layer 10 covers only a central area 13 of the light-emitting device, which is sufficiently far from an outer edge 15 of the light-emitting device 1, so that the application and subsequent structuring of the converter layer 10 is possible at the wafer level using common processes. To simultaneously ensure that, despite the converter layer 10 being applied only locally, essentially all light generated in the semiconductor layer stack 2 is coupled into the converter layer 10, measures are provided to appropriately restrict the central area 13.

[0069] To limit the central area 13, through which light generated in the semiconductor layer stack 2 is coupled into the converter layer 10, an optical aperture 14 is arranged in the illustrated embodiment between the first layer 3 and the second contact layer 18, in particular embedded in the first layer 3. The optical aperture 14 covers an edge region of the semiconductor layer stack 2. The optical aperture 14 is formed in the form of a strip that covers one edge region of the semiconductor layer stack 2. In addition, a material layer 23 is arranged on the first dielectric layer 19, which surrounds the semiconductor layer stack 2 or the first electrical contact 6 in the circumferential direction.The optical aperture physically reduces the top surface of the semiconductor layer stack 2, through which light is emitted towards the converter layer 10, and the material layer thickens a non-light-emitting area of ​​the light-emitting luminaire in a lateral direction, in order to reduce the central area 13 compared to the lateral dimensions of the entire light-emitting luminaire.

[0070] In particular, the semiconductor layer stack 2, together with the first and second contact layers 7, 18, as well as the first dielectric layer 19, the material layer 23, and the optical aperture 14, form a light-generating structure which has a top surface 12 on one side opposite the first contact layer 7. The top surface 12 is formed by the second contact layer 18, with only a central region 13 of it designed to couple light generated in the light-generating structure into the converter layer 10 applied to the light-generating structure. The central region 13 is bounded at its edge by the first dielectric layer 19 and the material layer 23, or a projection thereof, and additionally by the optical aperture 14, or a projection thereof, arranged between the first layer 3 and the second contact layer 18.The central region 13 is spaced at least 0.1 pm away from an outer edge 15 of the top surface 12 of the light-emitting structure on at least one side to ensure that the converter layer 10 can also be spaced at least 0.1 pm away from the outer edge 15 of the top surface 12 of the light-emitting structure while simultaneously completely covering the central region 13. For this to be possible, sufficient space must be available between adjacent central regions 13 of adjacent light-emitting devices 1 to allow the converter layer 10 to be deposited and subsequently structured at the wafer level using standard processes. Thanks to a converter layer 10 designed and arranged in this way, light of a first wavelength, which is generated in the active region 5, can be efficiently converted into light of a second wavelength.Furthermore, the proposed arrangement allows for the provision of a very compact light-emitting device.

[0071] Figures 2, 3A and 3B each show a cross-sectional view of a further embodiment of several light-emitting devices 1 according to some aspects of the proposed principle. As in the embodiment shown in Figure 1, several light-emitting devices 1 are depicted during their manufacture, at a point in time when they are still held on a support substrate 24 by means of a sacrificial layer 21 or bonding layer 22.

[0072] Figure 2 shows an embodiment in which no optical aperture 14 is provided, but a restriction of the central area 13 is achieved solely by a sufficiently thick material layer 23. In particular, the material layer can have a thickness of at least 0.05 pm to provide the desired added value.

[0073] Figures 3A and 3B, however, each show an embodiment in which a material layer 23 specifically provided for limiting the central region 13 is omitted, or is so thin that it has a negligible effect on limiting the central region 13. In the illustrated embodiments, the central region 13 is limited only by an optical aperture 14, in particular a circumferential optical aperture 14. In the embodiment shown in Figure 3A, the optical aperture 14 is arranged in an annular shape between the first layer 3 and the second contact layer 18, in particular embedded in the first layer 3, and covers a circumferential edge region of the semiconductor layer stack 2.In the embodiment shown in Figure 3A, the optical aperture 14 is arranged in an annular shape on the second contact layer 18, and the converter layer 10 extends to an area of ​​the second contact layer 18 exposed by the optical aperture 14, or to the top surface 12 of the light-generating structure.

[0074] Figures 4A to 4F each show a top view of embodiments of a light-emitting device 1 according to some aspects of the proposed principle. In particular, the figures show a top view of a converter layer 10 applied to the second contact layer 18, as well as the central region 13 (dashed lines) and, in Figures 4A, 4B, 4C, 4E and 4F, the optical aperture 14 (dashed lines). In Figure 4D, however, no optical aperture is provided.

[0075] The figures show different possible cross-sectional areas (rectangle, square, polygon, hexagon, octagon) of the light-emitting device 1, as well as different possible arrangements and designs of the optical aperture 14, which at least partially define the central area 13.

[0076] Figures 4A and 4C show an embodiment in which the optical aperture 14 is formed in the form of a strip which, as also shown in cross-section in Figure 1, covers an edge region of the semiconductor layer stack 2. The central region 13 is thus limited on one side by the optical aperture 14 and simultaneously at its other outer edges by the edges of the semiconductor layer stack 2 or the edge region between the half-liter layer stack 2 and the material layer 23.

[0077] Figure 4B shows an embodiment in which the optical aperture 14 is formed in the form of two strips covering opposite edge regions of the semiconductor layer stack 2. The central region 13 is accordingly bounded on two sides by an optical aperture 14 arranged symmetrically with respect to the semiconductor layer stack and bounded at its further outer edges by the edges of the semiconductor layer stack 2 or the edge region between the semiconductor layer stack 2 and the material layer 23.

[0078] Figure 4D shows an embodiment in which no optical aperture 14 is provided, and the central region 13 is accordingly limited by the edges of the semiconductor layer stack 2 or the edge region between the half-micrometer layer stack 2 and the material layer 23. Figure 4E shows an embodiment in which an annular optical aperture 14 according to the embodiment in Figure 3A is provided, in which the central region 13 is circumferentially limited by the optical aperture 14.

[0079] Figure 4F shows an embodiment in which the optical aperture 14 is formed as an asymmetrically shaped ring that covers the peripheral region of the semiconductor layer stack 2 in the circumferential direction. The central region 13 is thus completely enclosed by the optical aperture 14. Due to the asymmetrical shape of the aperture, the central region 13, and consequently also the converter layer 10, are arranged / formed off-center above the half-liter layer stack 2. This has the advantage, as also shown in Figures 4A and 4C, that the light-emitting device can be readily used to electrically connect the light-emitting device via the larger exposed area of ​​the second contact layer 18 adjacent to the converter layer 10.

[0080] The embodiments shown in Figures 1 to 4 F are, however, to be understood as exemplary and aspects thereof can certainly be combined within the scope of professional practice.

[0081] Figures 5A and 5B show two steps of further processing of a light-emitting device 1 according to some aspects of the proposed principle. The light-emitting device 1 is shown in a highly simplified form, but can be designed according to the embodiments described above.

[0082] For electrical contact, the light-emitting device 1 can be arranged on a target substrate 26, with its first electrical contact 6 being electrically coupled to a solder pad 27. A second electrical contact 8 can be, for example, the optical aperture 14, which is electrically coupled to a second solder pad 29 via a conductor track 28 or a planar connection. A structured filler material 25 is provided for mechanically fixing the light-emitting device 1 to the target substrate 26 and for creating the conductor track 28, on which the conductor track 28 is deposited.

[0083] REFERENCE SYMBOL LIST light-emitting device Semiconductor layer stack first layer second layer active area first electrical contact first contact layer second electrical contact bottom side converter layer top layer plane central area optical aperture outer edge side surface protective layer second contact layer dielectric layer dielectric layer sacrificial layer interconnect layer material layer support substrate filler material target substrate solder pad conductor track solder pad

Claims

PATENT CLAIMS 1. Light-emitting device (1) comprising: a semiconductor stack (2) comprising a first layer (3) of a first conductivity type, a second layer (4) of a second conductivity type, and an active region (5) arranged between the first and second layers, configured to generate light of a first wavelength; a first contact layer (7) arranged on a bottom surface (9) of the semiconductor stack (2) and electrically contacts the second layer (4); a second contact layer (18) substantially transparent to light of the first wavelength, arranged on a top surface (11) of the semiconductor stack (2) opposite the bottom surface (9) and electrically contacts the first layer (4); a first electrical contact (6) electrically contacts the first contact layer (7);a first dielectric layer (19) covering at least one side surface (16) of the semiconductor layer stack (2) connecting the top (11) and the bottom (9); and a converter layer (10) arranged on or above the second contact layer (18) and configured to convert light of the first wavelength into light of a second wavelength; wherein the converter layer (10) completely covers a central region (13) through which light of the first wavelength generated in the semiconductor layer stack (2) is coupled into the converter layer (10); and wherein the central region (13) is spaced at least 0.1 pm apart in a plane (12) parallel to the top (11) from an outer edge (15) of the light-emitting device (1) lying in the plane (12).

2. The light-emitting device according to claim 1, wherein a second dielectric layer (20) is arranged between the second contact layer (18) and the converter layer (10). is which in particular electrically insulates the converter layer (10) from the second contact layer (18).

3. The light-emitting device according to claim 1 or 2, further comprising a protective layer (17) which covers the converter layer (10) and in particular encapsulates the converter layer (10) together with the second contact layer (18).

4. The light-emitting device according to claim 3, wherein the protective layer (13) is formed by a DBR and / or is designed to be reflective or absorbent at least for light of the first wavelength.

5. The light-emitting device according to one of the preceding claims, further comprising a material layer (23) covering the first dielectric layer (19) and in particular forming the outer edge (15) of the light-emitting device (1).

6. The light-emitting device according to claim 5, wherein the material layer (23) is designed to be reflective or at least comprises a reflective layer.

7. The light-emitting device according to claim 5 or 6, wherein the material layer (23) has a thickness of at least 0.05 pm .

8. The light-emitting device according to one of the preceding claims, further comprising an optical aperture (14) arranged between the converter layer (10) and the active area (5), wherein the optical aperture (14) at least partially defines the central area (13).

9. The light-emitting device according to claim 8, wherein the optical aperture (14) is arranged between the second contact layer (18) and the converter layer (10).

10. The light-emitting device according to claim 8, wherein the optical aperture (14) is at least partially embedded in the second layer (4).

11. The light-emitting device according to claim 8 or 10, wherein the optical aperture (14) is arranged between the top surface (11) and the second contact layer (18).

12. The light-emitting device according to any one of claims 8 to 11, wherein the optical aperture (14) is formed in the form of a strip extending along the outer edge (14) of the light-emitting device (1).

13. The light-emitting device according to one of claims 8 to 12, wherein the optical aperture (14) is arranged and / or designed asymmetrically with respect to the semiconductor layer stack (2).

14. The light-emitting device according to one of claims 8 to 12, wherein the optical aperture (14) is arranged and / or designed in a point- and / or axis-symmetric manner with respect to the semiconductor layer stack (2).

15. The light-emitting device according to one of claims 8 to 14, wherein the optical aperture (14) is designed to reflect at least light of the first wavelength.

16. The light-emitting device according to any of the preceding claims, wherein the converter layer (10) comprises or is formed from quantum dots and / or perovskites.

17. Method for manufacturing a light-emitting device (1) , comprising the steps: Providing a semiconductor layer stack (2) comprising a first layer (3) of a first conductivity type, a second layer (4) of a second conductivity type and an active region (5) arranged between the first and second layers, configured to generate light of a first wavelength, on a growth substrate; Structuring the semiconductor layer stack (2) , forming a bottom surface (9) and side surfaces (16) of the semiconductor layer stack (2) which extend from the bottom surface (9) in a direction away from the bottom surface (9); Providing a first contact layer (7) on the underside (9) of the semiconductor layer stack (2) which electrically contacts the second layer (4); Providing a first dielectric layer (19) on the side surfaces (16) ; Providing a first electrical contact (6) which electrically contacts the first contact layer (7); Removal of the growth substrate and exposure of one of the top surfaces (11) of a separate light-emitting device (1) opposite the bottom surface (9) of the semiconductor layer stack (2); Providing a second contact layer (18) on the top surface (9) which electrically contacts the first layer (4); and Providing a converter layer (10) on or above the second contact layer (18); wherein the converter layer (10) is configured to convert light of the first wavelength into light of a second wavelength; wherein the converter layer (10) completely covers a central region (13) through which light of the first wavelength generated in the semiconductor layer stack (2) is coupled into the converter layer (10); and wherein the central region (13) is spaced at least 0.1 pm apart in a plane (12) parallel to the top surface (11) from an outer edge (15) of the light-emitting device (1) lying in the plane (12).

18. Method according to claim 17, further comprising providing an optical aperture (14) between the converter layer (10) and the active area (5), wherein the optical aperture (14) defines at least part of the central area (13).

19. Method according to claim 17 or 18, further comprising providing a protective layer (17) covering the converter layer (10) and in particular encapsulating the converter layer (10) together with the second contact layer (18), wherein the protective layer (17) is in particular formed by a DBR and / or is designed to be reflective or absorbent at least for light of the first wavelength.

20. A method according to any one of claims 17 to 19, further comprising providing a material layer (23) covering the first dielectric layer (19) and in particular forming the outer edge (15) of the light-emitting device (1), wherein the material layer (23) is in particular designed to be reflective or at least comprises a reflective layer; and wherein the material layer (23) in particular has a thickness of at least 0.05 pm.

Images