Lighting unit, method for manufacturing a lighting unit, conversion element for an optoelectronic structural element, radiation source with LED and conversion element, light extraction structure, and optoelectronic device

Abstract

To provide a photoelectronic device provided with an arrangement structure comprising a plurality of light sources for generating light.SOLUTION: An illumination unit comprises at least one photoelectron emitter unit (13) that emits electromagnetic radiation (19) through a light emission surface (15), and a photonic structure (17) that beam-shapes the electromagnetic radiation (19) before emitting the electromagnetic radiation (19) through the light emission surface (15), where the photonic structure (17) shapes the electromagnetic radiation (19) such that the electromagnetic radiation (19) has a specific far field (21).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This patent application claims the priority of German Patent Application Publication No. 102019112639.8, filed May 14, 2019, German Patent Application Publication No. 102019112616.9, filed May 14, 2019, German Patent Application Publication No. 102019115991.1, filed June 12, 2019, German Patent Application Publication No. 102019116313.7, filed June 14, 2019, German Patent Application Publication No. 102019118251.4, filed July 5, 2019, and International Application No. PCT / EP2020 / 052191, filed January 29, 2020, the disclosures of which are incorporated herein by reference.

[0002] The present invention relates to a lighting unit comprising at least one photoelectron emitter unit.

[0003] The invention also relates to an illumination unit comprising at least one emitter unit which emits radiation through a light exit surface and a polarizing element which is at least partially adjacent to the light exit surface and which changes the polarization and / or intensity of the radiation emitted by the emitter unit as it passes through the polarizing element.

[0004] The invention also relates to a conversion element for an optoelectronic component, to a radiation source comprising an LED and a conversion element, and to a method for producing a corresponding radiation source.

[0005] The invention also relates to a device, in particular an optoelectronic structural element, in particular a light-emitting diode.

[0006] The present invention relates to an optoelectronic device in which an arrangement with a plurality of light sources for generating light is provided, such an arrangement may for example be a pixelated array of LEDs, in which one pixel in each case forms one light source.

[0007] The light emitters of photoelectric emitter units are primarily LEDs (LED = Light Emitting Diode). LEDs are usually Lambertian radiators. The light emitted from the light exit surface is not directional. Therefore, the light is usually radiated over the entire solid angle range adjacent to the light exit surface.

[0008] In many applications, it is desirable to have a lighting unit with an optoelectronic emitter unit that has a desired radiation pattern. For example, in the case of very small components, such as components used in high-resolution displays or consumer electronics, it is desirable to have a lighting unit that allows directional radiation into a specific solid angle and suppresses radiation into other solid angles as much as possible.

[0009] Technical solutions for beam shaping of the electromagnetic radiation emerging from the light exit surface of an illumination unit are already known from the prior art. For example, optical systems, in particular lenses, can be used to collimate the electromagnetic radiation propagating freely in space. Such illumination units with optical systems downstream of the light exit surface can be quite large, which may be undesirable.

[0010] The invention is based on the problem of providing a lighting unit with an improved radiation pattern, in particular compared to a Lambertian radiator.

[0011] The lighting unit according to the present invention comprises at least one photoelectron emitter unit that emits electromagnetic radiation through a light exit surface, and a photonic structure that beam shapes the electromagnetic radiation before it emerges through the light exit surface, wherein the photonic structure shapes the electromagnetic radiation so that it has a constant far field.

[0012] In this way, the photonic structure changes the radiation pattern of the lighting unit from that of a Lambertian radiator to a defined radiation pattern in the far field. Thus, the expression that electromagnetic radiation has a specific far field means that the radiation pattern is defined specifically in the far field and is different from the radiation pattern of a Lambertian radiator. Here, "far field" refers to an area at least a few centimeters or meters away from the lighting unit, depending on the application.

[0013] The photonic structure may be arranged, in particular in a layer, below the light output surface and / or between the photoelectron emitter unit and the light output surface. The photonic structure may thus be integrated into the lighting unit and be compact. The photonic structure may be integrated into the light output surface or an end face of the photonic structure may form the light output surface.

[0014] The photoelectron emitter unit may comprise at least one LED. The photoelectron emitter unit may comprise a field of LEDs, also called an array.

[0015] The photonic structure may be a photonic crystal, a quasi-periodic photonic structure, or a deterministic aperiodic photonic structure. A photonic crystal is understood to be a periodic structure that periodically changes the refractive index of light, thereby creating a photon band structure. This band structure may have a band gap in a certain frequency range. These properties can be created by aperiodic, but nevertheless ordered, structures. Such structures are in particular quasi-periodic or deterministic aperiodic structures. They may, for example, be helical photonic arrangement structures.

[0016] The photonic structure may be a one-dimensional photonic structure, in particular a one-dimensional photonic crystal, which has a periodic variation of the refractive index along one direction, in particular, this direction may extend parallel to the light output surface.

[0017] The one-dimensional structure can form a beam in a first spatial direction. In this case, a photonic effect can be achieved even with just a few periods of the photonic structure. For example, the photonic structure can be configured such that the electromagnetic radiation is at least approximately collimated in the first spatial direction. Thus, a collimated beam can be generated at least in the first spatial direction.

[0018] A collimation optic may be arranged downstream of the light output surface in the radiation direction, the optic being configured to collimate the electromagnetic radiation in a further second spatial direction orthogonal to the first spatial direction. The first and second directions may be mutually orthogonal directions parallel to the planar light output surface. In this way, a bidirectionally collimated beam can be generated along a main radiation direction away from the light output surface and orthogonal to both the first and second directions.

[0019] According to one aspect of the invention, a photonic structure, in particular a photonic structure formed as a one-dimensional photonic crystal, may be configured such that the main emission direction of electromagnetic radiation extends at an angle relative to the normal to the light output surface, this angle being different from 0 degrees. The main emission direction may therefore extend obliquely relative to the normal to the light output surface. This allows a beam collimated in at least one direction to be emitted from the light output surface, for example obliquely.

[0020] The photonic structure formed as a one-dimensional photonic crystal may be arranged in a layer below, particularly directly below, the light-emitting surface. In this case, the one-dimensional photonic crystal may have a unidirectional, periodically repeated sequence of two materials with different optical refractive indices. Each of the materials may have a rectangular or parallelogram cross section. In this case, the interface where the materials meet may be inclined with respect to the light-emitting surface.

[0021] Such structures can be formed, for example, by etching parallel trenches in a substrate having a light-emitting surface at an angle to the light-emitting surface. The trenches can be filled with a material having a different optical index of refraction than the etched-away substrate material. The angle may depend on the inclination of the trench relative to the light-emitting surface, and the width of the trenches or the width of the substrate material remaining between the trenches affects the wavelength at which the photonic structure is effective. Typically, the width of the trenches and the width of the substrate material between the trenches are tailored to the wavelength of the electromagnetic radiation.

[0022] The photonic structure may be a two-dimensional photonic structure, in particular a two-dimensional photonic crystal. An end face of the two-dimensional photonic structure may form the light output surface of the lighting unit, or the two-dimensional photonic structure may be disposed in a layer below the light output surface.

[0023] The two-dimensional structure, in particular the two-dimensional photonic crystal, may be configured to influence electromagnetic radiation such that it forms a defined, in particular discrete, pattern in the far field, such that the illumination unit can be used, for example, in surface topography systems for face recognition.

[0024] As mentioned above, the photonic structure may be located in a layer below the light exit surface, or the end face of the photonic structure may form the light exit surface, so that the photonic structure is directly below the light exit surface and encompasses it together.

[0025] The photonic structure may be formed in a semiconductor layer of the photoelectron emitter unit.

[0026] The photoelectron emitter unit may include a layer having a conversion material, and the photonic structure may be formed in the layer having the conversion material or in a layer between the layer having the conversion material and the light exit surface.

[0027] The optoelectronic emitter unit may comprise at least one optoelectronic laser, for example a VCSEL (vertical-cavity surface-emitting laser). It is also conceivable to arrange several lasers in a field.

[0028] The present invention also relates to a surface topography detection system comprising an illumination unit, the illumination unit comprising: The surface topography detection system includes at least one photoelectron emitter unit that emits electromagnetic waves through a light exit surface and a photonic structure that beam-shapes the electromagnetic radiation before it emerges through the light exit surface, wherein the photonic structure shapes the electromagnetic radiation so that it has a constant far field, and the photonic structure is a two-dimensional photonic structure, in particular a two-dimensional photonic crystal, which is configured so that the electromagnetic radiation creates a defined, in particular discrete, pattern in the far field, and the surface topography detection system further includes a detection unit, in particular equipped with a camera, configured to detect the pattern in the far field.

[0029] The surface topography detection system may include an analysis device configured to determine deviations of the pattern relative to a predetermined reference pattern.

[0030] The analyzer may be configured to determine the shape and / or structure of the object illuminated by the pattern in response to the determined deviations.

[0031] The invention also relates to a scanner for scanning an object, wherein the scanner comprises an illumination device according to the invention, which can preferably be used for line-by-line detection of the object.

[0032] It can also be seen as a challenge to further design the lighting unit in such a way that it allows for a change in the polarization and / or brightness of the radiation emitted by the at least one emitter, in particular visible light, in a relatively simple manner, where it may be important that the corresponding lighting unit is designed as space-saving and energy-efficient as possible, where in particular the need for using additional optical elements should be reduced.

[0033] Furthermore, it may be considered desirable to provide a simple, safe, and robust lighting unit for emitting polarized electromagnetic radiation as required, which can be combined with other lighting units without major problems. Moreover, it is desirable to produce lighting units on an industrial scale, preferably using known manufacturing methods. Therefore, a technical solution is desired that is designed to be particularly space-saving, allows energy-efficient operation with a high light output, and can be manufactured within an economically reasonable framework.

[0034] Therefore, a preferred configuration of the lighting device according to the invention relates to a lighting unit comprising at least one emitter unit emitting radiation via a light exit surface and a polarizing element at least partially adjacent to the light exit surface and adapted to change the polarization and / or intensity of the radiation emitted by the emitter unit as it passes through the polarizing element, characterized in that the polarizing element has a three-dimensional photonic structure.

[0035] The discussion of a polarizing element changing polarization also includes the creation of polarized radiation from unpolarized radiation. A polarizing element can also cause only a wavelength-dependent change in the intensity of radiation, in some cases without creating or changing the polarization. Therefore, the term "polarizing element" should not be interpreted narrowly in the sense that all configurations must provide for the creation or change of polarization.

[0036] Based on the configuration according to the invention, an illumination unit is provided in which radiation generated by an emitter, such as an LED, directly reaches the polarizing element, thereby realizing a particularly compact unit for providing polarized radiation as required, which unit can also be advantageously combined with at least one further illumination unit and / or polarizing element, preferably at least one polarizing element with complementary properties.

[0037] The essential advantage of using three-dimensional photonic structures, in particular photonic crystals, for polarizing electromagnetic radiation, preferably visible light, is that arranging the photonic structures in the region of the light exit surface of the emitter provides a particularly compact and space-saving solution. By arranging a specially designed polarizing element adjacent to the light exit surface, the electromagnetic radiation can be appropriately polarized, while minimizing losses of electromagnetic radiation whose polarization does not correspond to the polarization direction of the polarizing element. It is generally conceivable that the photonic structure is arranged on the light exit surface or that the photonic structure is suitably formed in the semiconductor layer in which the light exit surface is arranged or on a semiconductor layer adjacent to the light exit surface in the beam direction.

[0038] It is particularly advantageous here that the three-dimensional structure used as a polarizing element allows the radiation pattern of the lighting unit to be changed particularly effectively in terms of its polarization properties, so that different wavelengths can be distinguished by different polarization properties or radiation directions.

[0039] According to one embodiment of the invention, the emitter unit comprises at least one LED, which preferably emits white, red, green or blue light, which is incident on a polarizing element, which polarizes the radiation in a vibration direction.

[0040] In another development of the invention, the emitter unit, particularly the LED and the polarizing element, are formed from different layers arranged one above the other in a layer stack. It is also important that the radiation generated in at least one layer of the emitter enters a polarizing element, also in the form of a layer, before being emitted from the layer stack into the environment. In an advantageous manner, the three-dimensional structure used as the polarizing element can be arranged on or within the same semiconductor chip as the emitter unit. When the emitter unit is used with an LED, it is further conceivable that the photonic structure is applied to the LED chip or is at least part of the LED chip. This inventive configuration allows for a particularly space-saving and energy-efficient lighting unit, in which polarized radiation is generated directly at the chip level, eliminating the need for additional optical elements in the downstream beam path. This technical solution therefore represents a cost-effective, space-saving, and energy-efficient solution for providing polarized radiation.

[0041] In a further embodiment of the invention, the polarizing element has spiral and / or rod-shaped structural elements. In this case, the three-dimensional photonic structure is configured so that light emitted by an emitter unit, in particular an LED, exits the photonic structure only with a specific polarization. Corresponding three-dimensional photonic structures having spiral and / or rod-shaped structural elements in the region of the light exit surface transmit radiation only with a specific polarization direction. Advantageously, the structure's configuration and dimensions are in each case adapted to the radiation emitted by the emitter unit, in particular an LED. A spiral structure results in circular polarization, while a rod-shaped structure results in linear polarization of radiation passing through the structure.

[0042] In a further development, the lighting unit may have an LED as an emitter unit, and the radiation emitted by the LED may impinge on a conversion element having a conversion material as excitation light, which emits converted radiation. In this case, it is generally conceivable that a three-dimensional photonic structure is arranged in the beam path between the LED and the conversion element and / or behind the conversion element, which polarizes the excitation light and / or the converted radiation in an appropriate manner. It is also possible to combine the conversion element and the three-dimensional photonic structure in the same layer. This allows for directly polarized converted light to be generated.

[0043] For example, a three-dimensional photonic structure can be filled with a conversion material. 3+ (Ce is cerium), Eu 2+ (Eu is europium), Mn 4+ The host material may be doped with manganese (Mn) or neodymium ions. For example, YAG or LuAG can be used. Here, YAG stands for yttrium aluminum garnet. LuAG stands for lutetium aluminum garnet.

[0044] Quantum dots can also be used as conversion materials to fill three-dimensional photonic structures.

[0045] Quantum dots can be very small, for example, in the 10 nm range. This makes them particularly suitable for filling three-dimensional photonic structures. A typical method for producing such structures is to etch away material from the layer in which they are formed. The recesses thus formed can then be filled with a conversion material, for example, containing quantum dots. The quantum dots can be incorporated, for example, in a liquid material filling the recesses. The liquid material can be at least partially evaporated, leaving the quantum dots in the recesses. In this case, some of the liquid material can solidify. The quantum dots can therefore be embedded in a matrix.

[0046] In a further configuration of the invention, the polarizing element comprises at least one three-dimensional photonic crystal. It is equally conceivable that the polarizing element comprises at least two two-dimensional photonic crystals arranged in succession along the beam path of the radiation passing through the polarizing element.

[0047] Advantageously, by using a three-dimensional photonic crystal or at least two two-dimensional photonic crystals arranged in succession in the beam path, it may be possible to make the structure on which the radiation is incident transparent to radiation of a specific wavelength or wavelengths and / or only in a specific direction. In this way, it is also possible to adjust the desired polarization of the radiation incident on the polarizing element. In this regard, it is conceivable to manufacture the structure directly from the conversion material or to incorporate additional layers of other materials. Here, the properties of the three-dimensional photonic structure are preferably designed so that the transmission conditions are different for different wavelengths. In this way, for example, the converted radiation can pass through the polarizing element unimpeded, while the excitation light can be redirected. Similarly, it is conceivable that at least one of the radiation, i.e., the excitation light on the one hand, and the converted radiation on the other hand, passes through the polarizing element only with a specific polarization.

[0048] In one embodiment of the invention, it may further be provided that the polarizing element has at least two different transmittances depending on the wavelength of the radiation passing through the polarizing element. In this connection, a special development provides that the emitter unit comprises an LED and a conversion element having a conversion material that emits converted radiation when excited by excitation light emitted by the LED, and that the excitation light incident on the polarizing element is polarized differently and / or absorbed with a different strength when passing through the polarizing element compared to when the converted radiation passes through.

[0049] In this way, the properties of the 3D photonic structure can be engineered to provide different transmission conditions for different wavelengths. In this case, for example, the converted light can pass through the 3D photonic structure unimpeded, while the excitation light can be redirected. Similarly, the converted radiation can exit the 3D photonic structure only with a specific polarization.

[0050] Furthermore, it is believed that one of the two radiations having different wavelengths can be distinguished by the different polarization and propagation direction characteristics of the polarizing element. Therefore, it is advantageously provided that a combination of an LED and a conversion element that achieves complete conversion filters out part of the excitation light except for a relatively small portion of radiation having a specific wavelength, thereby allowing the use of a thinner layer of conversion material.

[0051] The advantages of the present invention can be utilized in a particularly advantageous manner when an emitter unit including an LED is provided, and the three-dimensional structure of the polarizing element is applied directly to the LED chip, preferably to a semiconductor layer of the LED through which the generated radiation reaches the light exit surface. In this configuration, the three-dimensional photonic structure is arranged directly on or within the LED chip. This technical solution allows for an improved image generation resolution based on polarized radiation emission, and allows for a relatively compact beam-generating component. This can be achieved, for example, by imaging radiation emitted by several components or lighting units with complementary properties via a common optical system. Suitable optical systems for this purpose are disclosed in the present application. Therefore, lighting units formed in this manner can be used, in particular, in the field of household appliances.

[0052] In other respects, the invention relates to a method for manufacturing an illumination unit comprising at least one emitter unit which emits radiation through a light exit surface and a polarizing element which is at least partially adjacent to the light exit surface and which changes the polarization and / or intensity of the radiation emitted by the emitter unit as the radiation passes through the polarizing element.

[0053] According to the invention, this method could be further developed by providing a chip with an LED as an emitter unit and applying a three-dimensional photonic structure as a polarizing element to its light exit surface, for example by two-photon lithography or oblique deposition, and / or by introducing a photonic structure into the semiconductor layer of the LED adjacent to the light exit surface.

[0054] According to a special development of the method, the three-dimensional structure can change its dimensions depending on the wavelength of the radiation emitted by the LED.

[0055] Advantageously, a lighting unit configured according to at least one configuration example according to the invention can be used in a device for generating three-dimensional images, in particular for displaying them on a display, monitor or screen.

[0056] Particularly advantageously, the lighting unit configured according to the invention can also be used for computer-aided generation of three-dimensional images, whereby the lighting unit according to the invention with a three-dimensional photonic structure as a polarizing element advantageously changes the radiation pattern of the LED with respect to its polarization properties, so that differentiation of different wavelengths can be achieved due to different wavelength-specific polarization properties or radiation directions.

[0057] A major advantage here is that polarized radiation, especially polarized light, can be generated directly on the substrate with the emitter unit, especially at the level of the LED chip, or that complete conversion can improve selectivity. By emitting appropriately polarized radiation, the resolution of three-dimensional images can be improved while simultaneously reducing the size of the structural elements or lighting units required for image generation. This can be advantageously achieved by imaging the light of several structural elements with complementary properties onto a display or screen via a common optical system. Particularly in the field of consumer electronics, the combination of complementary polarizing elements allows for particularly favorable three-dimensional image generation.

[0058] It may also be desirable to further design conversion elements for optoelectronic components, as well as radiation sources comprising such conversion elements, in such a way that the arrangement of the individual elements is particularly space-saving, and thus the structural form of the radiation source consisting of an emitter for emitting excitation light and a conversion element can be particularly small. Here, it may be of great importance to selectively radiate the radiation emitted by the radiation source into a specific spatial region and to reliably prevent radiation into other regions in a relatively simple manner. Furthermore, it may be desirable to have a technical solution that is characterized by high energy efficiency and thus a relatively high light output compared to known technical solutions.

[0059] Furthermore, it may be considered desirable that a radiation source consisting of an emitter for emitting excitation light and a conversion element for generating converted radiation can be realized in a simple and cost-effective manner in terms of manufacturing technology, in particular by known manufacturing methods. In this respect, it may be considered desirable to specify a method for manufacturing the radiation source.

[0060] The present invention also relates to a conversion element for an optoelectronic component, which comprises at least one layer containing a conversion material that emits converted radiation toward the emission region when excited by incident excitation light. According to the invention, the conversion element is characterized in that the layer comprises, at least in part, a structure in which the conversion material is at least partially arranged, which structure is configured so that radiation is emitted as a directed beam toward the emission region. An essential feature of the invention is the provision of a suitably patterned layer in or on which a conversion material is applied that emits converted radiation when excited by excitation or pump light. The combination of the conversion material, on the one hand, and the patterned layer components for selective beam steering and / or shaping, on the other hand, creates an element that can selectively emit radiation toward the emission region of a radiation source in a particularly space-saving manner, limiting it to a desired spatial region. In this context, it is conceivable that the excitation light as well as the converted radiation emitted by the conversion element can be directed in a suitable manner so that radiation is emitted only in a specific direction while excluding emission of such radiation in other directions and / or regions.

[0061] It is generally conceivable that at least some regions of the structure, also referred to herein as photonic structure, are coated with a suitable conversion material and / or at least individual regions, for example recesses of the structure, are filled with a suitable conversion material. In this case, the structure is configured so that the emitted converted radiation is emitted as a beam bundle in the desired direction of the emission area. In this connection, it is also conceivable to configure the structure so that there are different regions from which beam bundles of radiation are emitted. In this way, conversion elements can be provided for use in optoelectronic components, which adjust the radiation pattern of the optoelectronic component as required. In particular, by suitable patterning of layers, it is possible to provide conversion elements whose emission profile of the optoelectronic component in which the conversion element is used can be changed so that no further radiation is emitted according to Lambert's law and a suitably unidirectionally directed beam or beam bundle is generated.

[0062] The conversion material is Ce 3+ (Ce is cerium), Eu 2+ (Eu is europium), Mn 4+ The host material may be doped with manganese (Mn) or neodymium ions. For example, YAG or LuAG can be used. Here, YAG stands for yttrium aluminum garnet. LuAG stands for lutetium aluminum garnet.

[0063] Quantum dots are also considered as conversion materials. They are very small, for example in the 10 nm range. This makes them particularly suitable for filling the aforementioned recesses in photonic structures. A typical method for producing a photonic structure involves etching away the material of the recesses from the layer in which the photonic structure is formed. The recesses can then be filled with a conversion material, including, for example, quantum dots. The quantum dots may, for example, be incorporated into a liquid material filling the recesses. The liquid material may be at least partially evaporated, leaving the quantum dots in the recesses. In this case, some of the liquid material may solidify. Therefore, the quantum dots may be embedded in a matrix.

[0064] Photonic structures typically do not change the spectral properties of quantum dots. However, quantum dots have a narrow emission spectrum. Photonic structures can be adapted to this narrow emission spectrum, thereby improving the directional selectivity they offer. Thus, photonic structures can very efficiently influence the radiation pattern of quantum dots as converters.

[0065] In one embodiment of the present invention, the structure has structural elements arranged quasi-periodically or deterministically aperiodically. Such a regular structure offers the advantage that the optical properties of the conversion element with the corresponding patterned layer can be adjusted particularly reliably, safely, and reproducibly. In this case, the structure is preferably configured so that radiation of a specific wavelength or a specific wavelength range can be transmitted through the layer in a specific direction, while this radiation cannot be transmitted through the layer in other directions. Alternatively or additionally, the patterned layer can be configured so that it is transparent or non-transparent to radiation of the specific wavelength, at least over a wide range.

[0066] According to a further development of the invention, it is provided that the layer comprises at least one photonic crystal. Using a suitable photonic crystal, it is possible to specifically block the propagation of radiation of a selected wavelength or wavelength range, at least in a specific direction, so that a beam or beam bundle of converted radiation can be emitted, if necessary, in a directionally directed manner, into a spatial region or emission region provided for this purpose. Deterministic aperiodic and quasi-periodic structures can have the same functionality as photonic crystals. However, slightly different properties may exist in the far field. Thus, when photonic crystals are mentioned in this specification, this also applies to deterministic aperiodic and / or quasi-periodic structures.

[0067] Photonic crystals are periodic structures that periodically change the refractive index of light, thereby creating a photon band structure. This band structure can have a band gap in a certain frequency range. Alternatively, this property can also be created in aperiodic, but ordered, structures. Such structures are in particular quasi-periodic or deterministic aperiodic photonic structures. They can be arranged, for example, in a spiral.

[0068] Furthermore, it is advantageous for the structure to have at least one recess in which the conversion material is arranged. It is advantageous in this connection to propose that the structure have a plurality of protrusions and recesses, the recesses being at least partially filled with a suitable conversion material. In this way, by combining the structure provided by the present invention with a conversion material, a conversion element can be realized relatively easily, so that the converted radiation is emitted only in a particularly limited radiation area and thus in a specifically targeted radiation manner. In principle, it is conceivable in this connection to configure the conversion element so that the excitation light is appropriately directed by the structure to the area of ​​the conversion material provided for this purpose, and / or the converted radiation enters the structure and is thus emitted in a specifically targeted radiation area as a beam bundle.

[0069] Advantageously, the layer having the structure is configured so that it has at least one optical bandgap. In this context, a bandgap is understood to be the region of the layer having a solid material between the valence band and the conduction band. This bandgap makes the solid used in the layer, and thus the conversion element including the layer, transparent to radiation in a certain frequency range. By appropriately adjusting the bandgap and / or selecting the solid material, the optical properties of the conversion element can be appropriately adjusted. In particular, it is possible to configure the layer so that only a portion of the incident radiation passes through the layer and is emitted into the emission region. Advantageously, the structure of the layer has an average thickness of at least 500 nm. In this case, it is advantageous to select a photonic structure, in particular a photonic crystal, a quasi-periodic structure, or a deterministic aperiodic structure, having a layer thickness of at least 500 nm, thereby creating the optical bandgap.

[0070] In one development of the invention, it is provided that the layer with the structures is configured in such a way that the directional beam is emitted perpendicular to the plane in which the layer is arranged, such that the radiation emitted into the emission region is arranged perpendicular to the layer plane, while the radiation components emitted into other spatial regions are reliably suppressed.

[0071] Furthermore, an advantageous development of the invention is when an optical filter element is arranged on at least one side of the layer. Preferably, such a filter element is configured as a filter layer that is applied to the side of the patterned layer with conversion material. The use of such a filter element or filter layer allows only a certain portion of the radiation to be incident on the layer with conversion material, or only a certain portion of the converted radiation emitted by the patterned layer with conversion material to be emitted in a desired spatial region.

[0072] Thus, advantageously, the filter element, in particular the filter layer, is configured so that only that part of the radiation that is required as excitation light or that should be properly emitted in the emission region can pass through the filter element or filter layer.

[0073] The present invention also relates to a radiation source having an LED that irradiates excitation light onto a conversion element formed according to at least one of the previously described embodiments of the conversion element according to the present invention. The conversion element itself has at least one layer containing a conversion material that, when excited by the excitation light emitted by the LED, emits converted radiation into a radiation region. In this context, it is conceivable to combine the LED with the conversion element in such a way that all of the excitation light emitted by the LED is converted into converted radiation, or that only a portion of the excitation light emitted by the LED is converted into converted radiation. It is also important that the radiation emitted by the radiation source is directed only into a desired spatial region. In this way, the radiation source generates a directional beam or a directional beam bundle that is emitted in a suitably selected direction or into a suitably selected radiation region.

[0074] According to one development of the invention, the patterning layer with the conversion material is part of the semiconductor substrate of the LED. In this case, the structure can advantageously be formed in the semiconductor substrate of the LED. In this connection, it is further advantageously conceivable to produce the structure by suitable etching of the LED semiconductor substrate and then at least partially coat the structure with the conversion material and / or fill the etched recesses of the structure with the conversion material.

[0075] Furthermore, it is advantageously contemplated that the structure with the conversion material is configured so that the converted radiation is emitted to the emission region in a direction perpendicular to the plane in which the semiconductor substrate is arranged. In this case, the structure is configured so that, due to the bandgap effect, the converted radiation is emitted to the emission region only in a direction perpendicular to the surface of the LED chip. This technical solution results in a high degree of directionality of the converted radiation emitted from the conversion element. In this regard, it is conceivable that the structure, in particular a photonic structure in the form of, for example, a photonic crystal, is arranged only in the topmost semiconductor material layer of the LED or at least partially in the active zone as well. It is also advantageous that the layer thickness of the structure is at least 500 nm to ensure the generation of the optical bandgap.

[0076] In a particular embodiment, it is provided that at least one filter layer is arranged on at least one side of the patterning layer. In this connection, it is conceivable that the filter layer can be used to suppress the excitation light generated by the LED in a specific wavelength range. In this way, the generation of directional radiation in the patterning layer of the conversion element can make systems based on complete conversion of the excitation light, especially those with étendue limitations, significantly more efficient than known technical solutions.

[0077] According to a development of the invention, the radiation source is configured to emit visible white light or visible converted light having colors characteristic of the RGB color space, namely red, green and blue.

[0078] According to a further configuration, the radiation source comprises one LED or several LEDs which are arranged next to each other in an array and can be individually driven and controlled.

[0079] According to a further configuration, the radiation source may be a pixelated array, for example, where individual pixels of a larger component are individually turned on and off.

[0080] It is advantageous to use photonic structures such as those described herein in combination with very small LEDs, such as those mentioned above, or pixelated arrays, because classical optical components such as lenses have very limited usability at small sizes. Furthermore, photonic structures can be used to improve the contrast between adjacent pixels because they provide directionality.

[0081] According to a further configuration, it is also possible to design the radiation source as a chip-sized package, in particular for components without a suitable housing, where optical elements of the type described here are particularly advantageous, since classical lenses would not be suitable for very compact components or would make the components too large.

[0082] Furthermore, the present invention relates to a method for manufacturing a radiation source having at least one of the above-mentioned specific characteristics, characterized in that the structure is formed by at least one etching step in the semiconductor substrate of the LED, whereby advantageously the structure, in particular selected recesses therein, are at least partially filled with a conversion material.

[0083] There may be a need for structures that can provide extraction, particularly light extraction, from a semiconductor body.

[0084] According to a first aspect, a method for producing a device, in particular an electronic component, in particular an optoelectronic component, in particular a light-emitting diode, is proposed, in which a surface region of a semiconductor body providing the device is patterned and the patterned surface region is planarized to produce an extraction structure, in particular an optical extraction structure, in order to obtain a planarized surface of the surface region, in particular planarization means producing a planarity, which can also be called flatness.

[0085] According to a second aspect, a device, in particular an electronic component, in particular an optoelectronic component, in particular a light-emitting diode, is proposed, in which an extraction structure is created in a surface region of a semiconductor body providing the device by patterning the surface region and planarizing the patterned surface region to obtain a planarized surface of the surface region.

[0086] The proposed extraction structure can be used to emit light from a surface in a direction normal to the surface.

[0087] According to the proposed arrangement, patterning of a surface area of ​​a semiconductor body, which may also be called a die, can be performed by generating a random topology in the surface area.

[0088] According to a further proposed configuration, the random topology can be generated by directly roughening the surface of the surface region of the semiconductor body that comprises the first material.

[0089] According to a further proposed configuration, the random topology can be created by applying a transparent second material, in particular Nb2O5, having a high refractive index, in particular a refractive index greater than 2, to the surface region and roughening this second material, which can be provided as a layer on the surface region.

[0090] According to a further proposed configuration, the patterning of the surface region of the semiconductor body can be performed by creating an ordered topology in the surface region.

[0091] According to a further proposed configuration, ordered topologies can be generated by applying a transparent second material, in particular Nb2O5, with a high refractive index, in particular a refractive index greater than 2, and patterning periodic photonic crystals or aperiodic photonic structures, in particular quasi-periodic or deterministic aperiodic photonic structures, in this material. The second material can be provided as a layer.

[0092] Photonic crystals are periodic structures that periodically change the refractive index of light, thereby creating a photon band structure. This band structure can have a band gap in a certain frequency range. Alternatively, this property can also be created in aperiodic, but ordered, structures. Such structures are in particular quasi-periodic or deterministic aperiodic photonic structures. They can be arranged, for example, in a spiral.

[0093] According to a further proposed configuration, the planarization of the surface region of the semiconductor body can be achieved by applying a transparent third material having a low refractive index, in particular less than 1.5, in particular SiO2, to the surface region. The third material can be provided as a layer.

[0094] According to a further proposed configuration, TEOS (tetraethyl orthosilicate) can be used to apply SiO2 as a transparent third material with a low refractive index.

[0095] According to a further proposed configuration, the thinning of the low refractive index third material can be carried out until the highest peaks of the first material or the highest peaks of the high refractive index second material of the semiconductor body at the surface are flat and / or smooth.

[0096] According to a further proposed configuration, the thinning can be performed by chemical mechanical polishing (CMP).

[0097] According to a further proposed configuration, the transfer of the device can be performed using stamping techniques.

[0098] According to a further proposed configuration, the planarized surface may be flat and / or smooth and have a roughness in the range of an average roughness value of less than 20 nanometers, in particular less than 1 nanometer.

[0099] According to a further proposed configuration, the extraction structure may comprise a transparent third material with a low refractive index, in particular SiO2, on the semiconductor roughened first material of the structural element.

[0100] According to a further proposed configuration, the extraction structure can comprise a transparent third material with a low refractive index, in particular SiO2, on a roughened transparent second material with a high refractive index, in particular Nb2O5, where the second material may be provided on a semiconductor first material of the structural element.

[0101] According to a further proposed configuration, the extraction structure can comprise a transparent third material with a low refractive index, in particular SiO2, on a transparent second material with a high refractive index, where the second material is provided on the semiconductor first material of the structural element and can comprise a periodic photonic crystal or an aperiodic photonic structure, in particular a quasi-periodic or deterministic aperiodic photonic structure.

[0102] It may also be considered desirable to provide improved optoelectronic devices that emit light at least substantially normal to the light emitting surface.

[0103] The present invention also relates to an optoelectronic device including an arrangement structure with a plurality of light sources for generating light to be emitted from a light emission surface of the optoelectronic device, and further including at least one photonic structure disposed between the light emission surface and the plurality of light sources.

[0104] At least one photonic structure (in particular a photonic crystal or a pillar structure, also referred to herein as a column structure) allows for beam shaping of the emitted light before it leaves the device through the light exit surface.

[0105] In particular, the photonic structure may be configured to beam shape the light generated by the light source, and in particular may be formed such that the light exits at least substantially perpendicularly from the light exit surface, thereby improving the directionality of the emitted light.

[0106] Photonic crystals are known per se. They are, in particular, periodic structures of the optical refractive index that occur or are created in a transparent solid. In particular, so-called two-dimensional photonic crystals are relevant here, in which the optical refractive index varies periodically in two mutually perpendicular spatial directions, in particular in two mutually perpendicular spatial directions that run parallel to the light exit surface.

[0107] According to one aspect of the invention, the arrangement is an array having a plurality of pixels arranged in layers as light sources, and the photonic crystal is arranged or formed in layers. Therefore, the photonic crystal may be arranged directly in the layer in which the pixels of the array are arranged. However, the photonic crystal may also be arranged in a layer above the light source, so that the photonic crystal is still located between the light source and the light output surface.

[0108] In particular, this layer may comprise a semiconductor material, and the photonic crystal may be patterned in the semiconductor material. Examples of semiconductor materials include the GaN or AlInGaP material systems, where GaN stands for gallium nitride and AlInGaP stands for aluminum indium gallium phosphide. Other possible material systems include AlN (aluminum nitride) and InGaAs (indium gallium arsenide).

[0109] Photonic crystals can be realized by forming a periodic change in the optical refractive index in a semiconductor material. For this purpose, a high refractive index material such as Nb2O5 (niobium (V) oxide) can be used and appropriately introduced into the semiconductor material. In this case, the photonic crystal is preferably formed as a two-dimensional photonic crystal having a periodic change in the optical refractive index in two mutually perpendicular spatial directions within a plane extending parallel to the light emission direction.

[0110] According to one aspect of the present invention, the array structure includes a plurality of pixels arranged in a first layer as light sources, and a photonic crystal arranged in a second layer, the second layer being located between the first layer and the light exit surface. Therefore, the photonic crystal can be arranged or housed in an additional second layer above the layer having the plurality of pixels. The photonic crystal may again be formed, for example, as a two-dimensional photonic crystal. The photonic crystal may be realized by holes or recesses formed in a high-refractive-index material, such as Nb2O5. In this way, the photonic crystal can be formed or may have been formed by forming corresponding patterning in the high-refractive-index material. The photonic structure may be filled with a low-refractive-index material, such as silicon dioxide.

[0111] According to one aspect of the present invention, the arrangement structure has a plurality of LEDs as light sources, the LEDs being arranged in a first layer, and a photonic crystal being arranged or formed in a second additional layer, the second layer being located between the first layer and the light-emitting surface. Particularly in combination with an array of LEDs, the photonic crystal may be provided in a second additional layer above the first layer having the LEDs. This is preferably formed as a two-dimensional photonic crystal, realizing a periodic change in the optical refractive index in two spatial directions parallel to the light-emitting surface and extending perpendicular to each other. An example of a high-refractive-index material is again Nb2O5, and the photonic crystal may be patterned by providing holes or recesses in the high-refractive-index material. The photonic structure may be filled with a low-refractive-index material, such as silicon dioxide.

[0112] LEDs can be distinguished between horizontal and vertical LEDs. In the case of horizontal LEDs, the electrical terminals are on the back of the LED, not facing the light-emitting surface. In contrast, vertical LEDs have one electrical terminal on the front and one on the back of the LED, with the front facing the light-emitting surface.

[0113] In pixelated arrays with rear-facing electrical contacts of both polarities, the entire array surface can be patterned, for example in the form of a photonic crystal, without omitting mesa trenches or contact areas. A similar arrangement can be achieved with horizontal light-emitting diodes arranged below the carrier substrate.

[0114] According to one aspect of the present invention, in an array or arrangement of horizontal light-emitting diodes for electrically contacting light sources, the two poles may be electrically connected to each other by a contact layer that reflects the generated light and that is located below the photonic structure and the light source when viewed from the light output surface on the top surface, and the contact layer may have at least two electrically isolated regions to avoid short circuits between the poles.

[0115] According to another configuration of the invention, in an arrangement of a vertical light-emitting diode for electrical contact with a light source, the first pole, which does not face the light output surface, in particular the positive pole, may be electrically connected to a contact layer that reflects the generated light, the contact layer being located below the photonic structure and the light source as seen from the light output surface on the top.

[0116] According to one embodiment of the invention, the second, in each case other, particularly negative, pole facing the light exit surface may be electrically connected by a layer of an electrically conductive, optically transparent material, in particular ITO, and a filler material may be arranged between the layer and the reflective contact layer.

[0117] According to one aspect of the present invention, each light source may have a recombination zone, and a photonic crystal may be arranged in the vicinity of the recombination zone so that the photonic crystal modifies the optical density of states present in the region of the recombination zone, in particular so that a bandgap is generated for at least one optical mode whose propagation direction is parallel and / or at a small angle to the light output surface. To generate an optical bandgap in the region of the recombination zone, it is advantageous for the photonic crystal to be very close to the recombination zone. Furthermore, to generate a bandgap, it is advantageous for the photonic crystal to have a large height, in particular 300 nm or more, as viewed perpendicular to the light output surface. The photonic crystal can thus suppress the emission of light whose propagation direction is parallel and / or at a small angle to the light output surface, thereby directing the light already emitted in the light-generating region. This allows light to be generated only in a limited emission cone perpendicular to the light output surface. Here, the opening angle of the emission cone depends on the photonic crystal and can be a small value, for example, up to 20°, up to 15°, up to 10° or up to 5°.

[0118] The photonic crystal may be arranged on a plane extending parallel to the light exit surface, regardless of the position of the light spot.

[0119] Photonic crystals can be produced using known lithography techniques, such as nanoimprint lithography or immersion EUV steppers (EUV stands for extreme ultraviolet).

[0120] The photonic structure may include a plurality of pillar structures extending at least partially between the light output surface and a plurality of light sources, each pillar being assigned to a light source and aligned so as to be coplanar with the light output surface when viewed in a direction perpendicular to the light output surface.

[0121] A pillar may also be called a column. A pillar or column preferably has a longitudinal axis extending perpendicular to the light exit surface. If a pillar and its assigned light source are aligned in the same plane, this means in particular that the longitudinal extension axis of the pillar intersects the center point of the light source.

[0122] When viewed perpendicular to the longitudinal axis, the pillars may have a circular, square, or polygonal cross section. Preferably, the pillars have a height-to-diameter aspect ratio of at least 3:1, where the height is measured in the direction of the pillar's longitudinal axis.

[0123] In particular, the pillars are made of a high-refractive-index material, such as Nb2O5. Because of their higher refractive index compared to the surrounding materials, the amount of light emitted parallel to the pillar's longitudinal axis can be increased compared to other spatial directions. The pillars act as waveguides, allowing light along the pillar's longitudinal axis to be extracted more efficiently than light propagating along other directions. This improves the directionality of the light along the longitudinal axis. Furthermore, because the longitudinal axis of the light preferably extends perpendicular to the light-emitting surface, light extraction perpendicular to the light-emitting surface can be improved.

[0124] The arrangement may be an array having a plurality of pixels arranged on a first layer as light sources, and the pillars may be arranged on a second layer between the first layer and the light exit surface. Therefore, the pillars may be arranged on the surface of the pixelated array. In this case, the pillar or column structure may be formed independently from a high refractive index material. Furthermore, the gaps between the pillars may be filled with a filler material, such as silicon dioxide, having a low refractive index.

[0125] The arrangement structure may have a plurality of LEDs arranged on a first layer as light sources, and the pillars may be arranged or formed on a further second layer, where the second layer is between the first layer and the light exit surface.

[0126] The arrangement may be an array having a plurality of pixels arranged on a first layer as light sources, and pillars may also be arranged on the first layer. In particular, the pillars may be arranged on the first layer such that at least a portion of each pillar is closer to the light output surface than the light source assigned to the pillar. This allows the pillars to function as optical waveguides between the light source and the light output surface. The pillars may be formed from a semiconductor material of the array arranged on the first layer, the semiconductor material having a high refractive index. In particular, the semiconductor material of the first layer may be removed by etching so that the pillars remain. The gaps between the pillars may again be filled with a low refractive index material.

[0127] This arrangement may be an array having a plurality of pixels, particularly LEDs, as light sources, where the pixels are formed on pillars. In this way, an array can be created in which the individual pixels are in the form of pillars. In this respect, each pillar is advantageously an LED and functions as an individual pixel. The length of the pillar, as viewed relative to the longitudinal axis of the pillar, can correspond to half the wavelength of the emitted light, and the recombination zone of the LED formed by the pillar is preferably located at the center of the pillar. The recombination zone is therefore located at a local maximum in the photonic density of states. This allows for a significant increase in the amount of light emitted parallel to the longitudinal direction of the pillar. Due to the waveguide effect, light propagating parallel to the longitudinal axis is extracted more efficiently than light propagating in other directions.

[0128] The aspect ratio of the pillar height to diameter is preferably 3:1. At typical emission wavelengths, the pillar height is approximately 100 nm and the diameter is 30 nm. Scaling up to larger heights and / or diameters is possible, which is easier to manufacture. The space between the pillars carrying the light source may be filled with a material with a lower refractive index than the semiconductor material of the pillars, such as silicon dioxide.

[0129] In the case of pillars with a light source, a p-type contact can be provided on the lower surface of the pillar, not facing the light-emitting surface. An n-type contact can be provided, for example, on the upper surface of the pillar, at half the height of the pillar. The n-type contact can be provided on a transparent conductive material, in particular as an intermediate layer of fill material or as a top layer on the pillar. Possible materials for the n-type contact layer include, for example, ITO (indium tin oxide). It is also possible to reverse the n-type and p-type contacts.

[0130] In particular, in the case of an arrangement of light-emitting diodes for electrical contact connection shaped as a pillar or column, in particular vertical, one first pole, in each case the positive one, may be electrically connected to a reflective contact layer which may be formed on and / or along a first longitudinal end of the light-emitting diode.

[0131] The other, in each case particularly the negative, second pole may be electrically connected to a further layer of electrically conductive and optically transparent material, in particular ITO, which may be arranged as an intermediate layer in the center of the pillar or column or on and / or along the second longitudinal end of the pillar, the second longitudinal end being opposite the first longitudinal end.

[0132] According to a further aspect, an optoelectronic device is proposed for generating light emission perpendicular to the light-emitting surface, in particular from a planar, pixelated array or arrangement of light-emitting diodes, in which optically active structures, in particular nanostructures such as photonic crystals or pillar structures, are patterned along the entire light-emitting surface in order to emit light in the perpendicular direction.

[0133] According to a further aspect, a method for manufacturing an optoelectronic device for generating light emission perpendicular to the light emitting surface, in particular from a planar, pixelated array or arrangement of light emitting diodes, is proposed, in which optically active structures are patterned along the entire light emitting surface for vertical light emission.

[0134] In particular, a planar array means in particular a planar array. Furthermore, the surface of the array or field is advantageously smooth. In particular, a pixelated array is a monolithic pixelated array.

[0135] All the materials mentioned, especially those in the photonic crystal, pillars or filler material, preferably have a low absorption coefficient, which is a measure of the loss of intensity of electromagnetic radiation as it passes through a given material.

[0136] The structural modifications of the present invention will be described in more detail below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0137] [Figure 1] 1 is a perspective view of a first variant of a lighting unit according to the invention; [Figure 2] FIG. 10 is a cross-sectional view of a second variant of the lighting unit according to the present invention. [Figure 3] 3 is a diagram showing an arrangement structure of a plurality of lighting units in FIG. 2. FIG. [Figure 4] FIG. 10 is a perspective view of a fourth variant of the lighting unit according to the invention. [Figure 5] 5 shows a block diagram of a surface topography detection system including the illumination unit of FIG. 4. [Figure 6] FIG. 1 shows an illumination unit including an emitter unit having a light exit surface to which a polarizing element of a three-dimensional photonic structure is applied. [Figure 7] FIG. 1 illustrates a three-dimensional photonic structure having multiple helical structural elements. [Figure 8] FIG. 1 shows an illumination unit comprising an emitter unit having a light exit surface to which a polarizing element having a three-dimensional photonic structure with wavelength-selective properties is applied. [Figure 9] FIG. 1 shows an illumination unit having an emitter unit and a three-dimensional photonic structure filled with a conversion material. [Figure 10] 1A and 1B show top and cross-sectional views of a radiation source comprising an LED and a conversion element formed of a patterned layer filled with conversion material located only on top of the LED semiconductor material; [Figure 11] FIG. 1 shows a cross-sectional view of a radiation source having an LED, a conversion element formed of a patterned layer filled with conversion material arranged only on the topmost layer of LED semiconductor material, and a filter layer applied to the topmost layer of LED semiconductor material; [Figure 12]1A and 1B show top and cross-sectional views of a radiation source comprising an LED and a conversion element formed of a patterned layer filled with a conversion material that extends into the active zone of the LED semiconductor material; [Figure 13] FIG. 1 shows a cross-sectional view of a radiation source having an LED, a conversion element formed of a patterned layer filled with conversion material that extends to the active zone of the LED semiconductor material, and a filter layer applied to the top layer of the LED semiconductor material. [Figure 14] FIG. 1 is a diagram illustrating an example of the configuration of a proposed device. [Figure 15] FIG. 10 is a diagram showing a further example configuration of the proposed device. [Figure 16] FIG. 10 is a diagram showing a further example configuration of the proposed device. [Figure 17] FIG. 1 is a diagram illustrating an example of a configuration of a proposed method. [Figure 18a] FIG. 1 is a top view of the first proposed device. [Figure 18b] FIG. 1 is a cross-sectional view of a first proposed device. [Figure 19a] FIG. 10 is a top view of the second proposed device. [Figure 19b] FIG. 10 is a cross-sectional view of a second proposed device. [Figure 20a] FIG. 10 is a top view of the third proposed device. [Figure 20b] FIG. 10 is a cross-sectional view of a third proposed device. [Figure 21a] FIG. 10 is a top view of the fourth proposed device. [Figure 21b] FIG. 10 is a cross-sectional view of the fourth proposed device. [Figure 22a] FIG. 10 is a top view of the fifth proposed device. [Figure 22b] FIG. 10 is a cross-sectional view of the fifth proposed device. [Figure 23a] FIG. 10 is a top view of the sixth proposed device. [Figure 23b] FIG. 10 is a cross-sectional view of the sixth proposed device. [Figure 24a] FIG. 10 is a top view of the seventh proposed device. [Figure 24b] FIG. 10 is a cross-sectional view of the seventh proposed device. [Figure 25a] FIG. 10 is a top view of the eighth proposed device. [Figure 25b] FIG. 10 is a cross-sectional view of the eighth proposed device. [Figure 26a] FIG. 10 is a top view of the ninth proposed device. [Figure 26b] FIG. 10 is a cross-sectional view of the ninth proposed device. [Figure 27] 1 shows a cross-sectional view of a further variant of the device according to the invention.

[0138] The illumination unit 11 shown in Fig. 1 comprises at least one photoelectron emitter unit 13, which is configured to emit electromagnetic radiation 19, e.g. visible or infrared light of different wavelengths, via a light exit surface 15. Here, a photonic structure 17 is provided for beam shaping the electromagnetic radiation before it exits via the light exit surface 15. The photonic structure 17 shapes the electromagnetic radiation 19 such that the electromagnetic radiation has a defined pattern 23 in the far field 21.

[0139] In particular, the photonic structure 17 of the lighting unit 11 of Fig. 1 is a one-dimensional photonic crystal 25. In the illustrated variant, this structure extends to the light exit surface 15. Therefore, the end faces of the photonic crystal 25 form the light exit surface 15. The one-dimensional photonic crystal 25 has a periodic variation in the optical refractive index along the first direction R1.

[0140] The crystal 25 or periodic variation is configured to beam-shape the electromagnetic radiation emitted by the light source (not shown) of the emitter unit. In particular, light propagation along the first direction R1 is blocked. As a result, the emitted radiation 19 in the far field 21 spreads only slightly along the first direction R1. Characteristically, the electromagnetic radiation 19 in the far field 21 thus forms a narrow strip 27. The electromagnetic radiation 19 is therefore collimated with respect to the first direction R1.

[0141] The light source is in particular an LED, which is typically a Lambertian radiator. Using the photonic structure 17 and the resulting beam shaping, directional collimated electromagnetic radiation 19 can be generated.

[0142] As shown diagrammatically in FIG. 1, the emitted electromagnetic radiation 19 leaves the emitter unit 13 in the form of a light cone that substantially fan-out along the second direction R2. The central axis of the light cone extends along the main radiation direction H, which extends perpendicular to the light exit surface 15. Not shown is an optional collimation optic downstream of the light exit surface 15, as viewed in the main radiation direction H. This optic can collimate the electromagnetic radiation 19 in a second spatial direction R2 that extends perpendicular to the first spatial direction R1. In this way, the electromagnetic radiation 19 can be collimated in the far field 21 with respect to the two directions R1, R2. This results in a spot.

[0143] The illumination device 11 according to Figure 1 is particularly suitable for use in optical scanners, where the illumination device 11 can be used in particular for line scanning applications with a strip-like light image in the far field 21.

[0144] 2, a one-dimensional photonic crystal 25 is formed on top of the emitter unit 13. An end face of the crystal 25 forms the light exit surface 15 for electromagnetic radiation generated by an optoelectronic light source (not shown), for example an LED, which passes through the photonic crystal 25 and is emitted via the light exit surface 15.

[0145] In contrast to the variant described in FIG. 1, in the lighting unit of FIG. 2, the main emission direction H of the electromagnetic radiation 19 extends at an angle α with respect to the normal N of the light output surface 15. Here, the angle α is not 0 degrees. For example, the angle α can be in the range of 30 to 60 degrees. This is achieved by the one-dimensional photonic crystal 25 having a periodically repeated sequence of two materials 31, 33 with different optical refractive indices extending in a first direction R1. The materials 31, 33 have a parallelogram-shaped cross section, as shown schematically in FIG. 2, and the interface where the materials 31, 33 meet is inclined with respect to the light output surface 15 rather than being orthogonal.

[0146] Such a structure can be formed, for example, by etching parallel trenches 29 in a substrate 31 having a light-emitting surface 15 at an angle relative to the light-emitting surface 15. The trenches 29 can be filled with a material 33 having a different optical refractive index than the etched-away substrate material 33. The angle α may depend on the inclination of the trenches 29 relative to the light-emitting surface 15. The width of the trenches 29 and the width of the remaining substrate material 31 between the two trenches 29 affect the wavelengths at which the photonic crystal 25 can be effective. Typically, the width of the trenches 29 and the width of the substrate material 33 located between the two trenches, and thus the periodicity of the photonic crystal structure 25, are tailored to the wavelength of electromagnetic radiation provided by the light source or the conversion material disposed between the light source and the photonic crystal.

[0147] By means of the one-dimensional photonic crystal 25, the lighting unit 11 according to Fig. 2 can also generate light strips 27 in the far field 21, as explained with reference to Fig. 1. In contrast to the variant of Fig. 1, the main radiation direction H in the variant of Fig. 2 is inclined by an angle α to the normal N. Collimation optics arranged downstream can make the strips 27 into point-like or circular structures in the far field 21.

[0148] The variant shown in Figure 3 comprises a number of lighting units 11 of Figure 2 arranged in a line or array. The light beams 19 emitted by the individual lighting units 11 have the same main radiation direction H. The light beams 19 can also be collimated by additional collimation optics 35, in particular lenses, in a second direction which extends perpendicular to the image plane in the illustration of Figure 2. This results in a point-like or circular imaging of the emitted radiation 19 in the far field behind the optics 35.

[0149] The use of photonic crystals in the illumination device 11 shown in Figures 2 and 3 effectively results in higher resolution compared to a line or array arrangement of the illumination device 11 shown in Figure 3. Furthermore, a smaller beam cross section can be achieved, especially in the far field downstream of the optical system 35. This allows the optical system 35, and possibly further subsequent optical systems, to be made more compact, since collimation in the first direction R1 (see Figure 2) occurs solely through the photonic crystal 25 incorporated in the illumination device 11.

[0150] In the variant of Fig. 4, the illumination unit 11 comprises a photonic structure 17 which is a two-dimensional photonic crystal 37, the end faces of which form the light exit surface 15. At least one optoelectronic light source, optionally provided with a conversion material, is arranged behind the photonic crystal 37 as viewed from the light exit surface 15. The photonic crystal 37 is shaped to shape the electromagnetic radiation 19 emitted through the light exit surface to generate a defined, discrete pattern 39 in the far field 21. In the example shown, the pattern 39 consists of a plurality of dispersed light spots 41, although other patterns are possible.

[0151] The illumination unit 11 of Figure 4 is suitable for use, for example, in a surface topography detection system 43 illustrated in the block diagram of Figure 5. In addition to the illumination unit 11, the system 43 includes a detection unit 45 with a camera 47 configured to detect the pattern 39 when it illuminates an object (not shown).

[0152] Furthermore, an analysis device 49 is provided which is configured to determine the deviation of the pattern 39 relative to a predetermined reference pattern, which can for example be determined from the detection of the pattern 39 when projected onto a flat surface.

[0153] The analysis device 49 is further configured to determine the shape and / or structure of an object illuminated by the pattern 39 in the far field 21 depending on the determined deviation of the pattern 39. Thus, the system 43 can, for example, realize face detection.

[0154] In the variant of Figure 4, downstream optics for pattern generation can be omitted, since the pattern 39 is already generated by the photonic crystal 37. The illumination device 11 according to Figure 4 and thus the system 43 according to Figure 5 can therefore be realized in a particularly compact form.

[0155] FIG. 6 shows a lighting unit 1 equipped with an emitter unit 2 having a light exit surface 3 on which a polarizing element 4 is applied in the form of a polarizing layer with a three-dimensional photonic structure. According to the exemplary configuration shown in FIG. 6, the emitter unit 2 is an LED 5 that emits light in the visible or possibly ultraviolet wavelength range. The light emitted by the LED 5 is guided to the three-dimensional photonic structure, where it is polarized in a specific vibration direction depending on the structure's configuration and dimensions. Depending on the configuration of the three-dimensional photonic structure, circular or linear polarization can occur. It is important that only light with a specific polarization is emitted from the lighting unit 1.

[0156] 7, when the three-dimensional photonic structure of the polarizing element 4 has helical structural elements 6, circular polarization occurs. On the other hand, when the structural elements of the three-dimensional photonic structure are rod-shaped, particularly those called nanorods, linear polarization of the radiation guided through the three-dimensional photonic structure occurs.

[0157] The lighting unit 1 shown in Figure 6 is fabricated by two-photon lithography, oblique deposition, laser interference lithography or holographic patterning. In this regard, it should be noted that the spiral structural element 6 shown in Figure 7 was fabricated using an oblique deposition process.

[0158] As shown in Figure 6, the illumination unit 1 can be advantageously combined with further illumination units having complementary properties, so that illumination units 1 with different polarization and / or transmission properties are combined for image generation.

[0159] The radiation polarized in different vibration directions, generated by a plurality of illumination units each having complementary properties, is imaged onto a display or screen using a common optical system, and such a device can be advantageously used to create three-dimensional images.

[0160] As shown in Figure 6, a three-dimensional photonic structure with a polarizing element 4 formed on the surface or light output surface 3 of an LED chip can be used to generate light with fundamentally different properties from currently known LEDs, particularly defined polarization. The provision of a three-dimensional photonic structure on the chip surface offers the significant advantage of eliminating the need for additional optical components, such as conventional polarization filters. This allows for a relatively small lighting unit. Because the structure is directly patterned on the semiconductor chip of the LED 5, such a lighting unit 1 is also more energy-efficient than known lighting units in which polarization selection is performed at a later stage. Photons that fail to pass through the three-dimensional photonic structure due to its properties remain within the LED chip and can be re-emitted through a reabsorption process.

[0161] FIG. 8 shows an illumination unit 1 comprising an emitter unit 2 having a light exit surface 3 to which is applied a polarizing element 4 having a three-dimensional photonic structure with wavelength-selective properties.

[0162] In this case, the photonic structure is configured as a three-dimensional photonic crystal, or it can be configured as multiple two-dimensional photonic crystals stacked one on top of the other.

[0163] The three-dimensional photonic structure is configured to have wavelength-specific transmittance and polarization characteristics, which means that the transmittance and polarization characteristics of the three-dimensional photonic structure change depending on the wavelength of the incident radiation.

[0164] The lighting unit 1 shown in Figure 8 has an emitter unit which in turn has an LED 5. Furthermore, a conversion element 7 is provided which has a layer of a conversion material. Upon excitation by excitation light 8 emitted by the LED 5, the conversion material emits converted radiation 9 which has a wavelength different from the wavelength of the excitation light 8.

[0165] When both the unconverted excitation light 8 and the converted radiation 9 strike the 3D photonic structure, they are affected differently in terms of transmission and polarization depending on their wavelength. As can be seen in Figure 8, the converted radiation 9 is extracted normal to the surface of the LED chip, while the excitation light 8 is polarized laterally.

[0166] Such lighting units can be preferably used in components in which radiation with different wavelengths is generated, where different functions can be realized by combining an LED and a conversion element. Depending on the configuration of the three-dimensional photonic structure and the wavelength of the excitation light 8 emitted by the LED in each case, it is possible to completely suppress the excitation light 8 while the converted radiation 9 is emitted via the three-dimensional photonic structure. It is also conceivable to polarize the excitation light 8 while the converted radiation 9 is extracted perpendicular to the chip surface, as shown in FIG. 8. Of course, this mechanism can also be reversed. It is also conceivable to polarize the converted radiation 9 in a special way while the excitation light 8 is emitted unchanged via the chip surface. Here, too, the mechanism can be reversed.

[0167] 9 includes an emitter unit, again in the form of an LED 15, and a three-dimensional photonic structure 11, configured, for example, as a spiral. The structure 11 is filled with a conversion material 13.

[0168] 10 shows a top view and a cross section of a radiation source 6 comprising an LED and a layer 2 arranged on a semiconductor substrate 8 of the LED 7, the layer 2 having structures 4 with a suitable conversion material. The patterned layer 2 with the conversion material forms a conversion element 1, which emits converted radiation into the emission region 3 of the radiation source 6 when excited by excitation light emitted by the LED 7.

[0169] The structures 4 provided in the layer 2 with conversion material are configured in such a way that the converted radiation is emitted exclusively in a directional beam flux in a specific emission area 3 .

[0170] According to the configuration example shown in FIG. 10, the converted radiation is emitted in a direction perpendicular to the plane in which the LED chip is disposed together with its semiconductor substrate.

[0171] The patterning layer 2 shown in Figure 10 is a two-dimensional photonic crystal etched into the LED semiconductor substrate. The individual, here rod-shaped, recesses of the structures 4 are filled with a conversion material. The layer thickness of the structures 4 is at least 500 nm, which creates a band gap in the crystalline solid material and imparts directionality to the converted radiation emitted by the conversion element 1.

[0172] Such photonic structures can significantly improve the directivity and therefore the efficiency, especially for etendue-limited systems. By providing the corresponding structures 4 and the layer 2 with a suitable conversion material directly on the surface of the LED 7, additional optical elements that would otherwise be required are no longer necessary, and thus the present invention can be used to realize a radiation source with a relatively small design.

[0173] The radiation source 6 shown in FIG. 10 can also be used to realize very small components, for example pixelated LED arrays for high resolution displays, or integrated components, for example in the field of consumer electronics.

[0174] Otherwise, a particularly energy-efficient radiation source is provided, since, on the one hand, light is not emitted in unnecessary directions that are not aligned perpendicular to the surface of the LED chip, and, on the other hand, the entire converted light can be utilized. Furthermore, the mode of the excitation light emitted by the LED 7, which is directed to the active zone 9 and has a low extraction efficiency from the LED 7, can also be efficiently converted in this way.

[0175] Additionally, Figure 11 shows a cross-section of a radiation source 6 that is configured as described in relation to Figure 10, but that additionally comprises a filter element 5 applied to the top of the radiation source 6 in the form of a filter layer 5 that is opaque to radiation in a selected wavelength range, in this case having the function of a color filter.

[0176] Such a technical configuration is found in particular in radiation sources 6, in which LEDs 7 are combined with conversion elements 1 in such a way that the light emitted by the LEDs 7 is completely converted. By means of a suitably configured filter layer 5, the radiation emitted into the emission area 3 can be limited to radiation of a desired wavelength. Likewise, the use of such a filter layer 5 ensures that excitation light emitted by the LEDs 7 that has not been converted into radiation converted by the conversion elements 1 is prevented from emitting into the emission area 3, if necessary.

[0177] 12 again shows a radiation source 6 comprising an LED 7 and a conversion element 1 applied to a semiconductor substrate 8 of the LED 7. The conversion element 1 comprises a layer 2 with a conversion material and a structure 4 applied to the semiconductor substrate 8 of the LED 7. The patterning layer 2 is preferably a photonic crystal, a quasi-periodic or deterministic aperiodic photonic structure. The structure 4 of the layer 2 is filled with a suitable conversion material.

[0178] 10, the patterning layer 2 is not only arranged on the semiconductor substrate in the region above the radiation source 6, but also extends to the active zone 9 of the LED 7. Here too, a patterning layer 2 having a layer thickness of more than 500 nm is provided, thus creating an optical bandgap. In this case too, the mode of the excitation light emitted by the LED 7, which is guided to the active zone 9 and has a low extraction efficiency from the LED, can be efficiently converted.

[0179] 13 shows a configuration of a radiation source 6 configured as shown in FIG. 12, with an additional filter element 5 applied to the top of the radiation source 6, the filter element 5 being configured in the form of a filter layer acting as a color filter. Such a color filter offers the possibility to limit the emission of converted radiation within the emission range in case of complete conversion of the excitation light emitted by the LED 7, or to selectively suppress the emission of unconverted excitation light in case of incomplete conversion.

[0180] An example of the construction of the proposed device is shown in Figure 14. According to Figure 14, a semiconductor body with a first material 1, which may also be called a die, is shown, here formed as a light-emitting diode.

[0181] An extraction structure A is formed. A surface region 9 of the semiconductor body that will provide the device is provided with a planarized surface 7. The surface region 9 is patterned for this purpose and then planarized.

[0182] The semiconductor body can be produced epitaxially, such that the surface region 9 is produced facing a carrier (not shown). In principle, all surface regions of the semiconductor body that provide the device can be patterned and subsequently planarized to form extraction structures A, in particular optical extraction structures A. Electromagnetic radiation of other wavelengths can also be extracted, provided that the patterning and planarization are matched thereto.

[0183] 14 shows patterning of a surface region 9 of a semiconductor body, where a random topology is generated in the surface region 9. Here, the random topology is formed by directly roughening the first material 1 of the semiconductor body on the surface region 9.

[0184] Here, topology refers specifically to spatial structure.

[0185] A transparent third material 5 having a low refractive index, in particular less than 1.5, is then applied to planarize the surface region 9 of the semiconductor body. This is followed by thinning of the applied transparent third material 5 having a low refractive index until the highest peaks of the first material 1 of the semiconductor body are flat and / or smooth at the surface 7 of the patterned surface region 9. The third material 5 can be applied as a layer.

[0186] Thinning can be done by chemical mechanical polishing (CMP).

[0187] Possible structures embossed into the surface region 9 may be random topologies, such as roughened surfaces, which are already used in large LEDs.

[0188] Light extraction is improved by the extraction structure A having a planarized surface 7. For this purpose, the first material 1, for example of an LED semiconductor or LED die, is first directly patterned as in FIG.

[0189] The low refractive index transparent third material 5 used for planarization can be SiO2, which can in particular be provided by TEOS (tetraethyl orthosilicate).

[0190] The refractive index (Brechungsindex), also known as the refractive index (Brechzahl) or optical density, and formerly known as the refractive index (Brechungszahl), is a property of optical materials. It is the ratio of the wavelength of light in a vacuum to the wavelength in the material, and therefore the ratio of the phase velocity of light in a vacuum to the phase velocity in the material. The refractive index is dimensionless and generally depends on the frequency of the light, a phenomenon known as dispersion. At the interface between two media with different refractive indices, light is refracted or reflected. A medium with a higher refractive index is said to be optically dense.

[0191] A low refractive index can be, in particular, less than 1.5. Other usable materials with low refractive index are, for example, crown glass with a refractive index of, for example, 1.46, PMMA with a refractive index of, for example, 1.49, and quartz glass with a refractive index of, for example, 1.46. These refractive indices occur at the wavelength of the sodium D line, 589 nm. The refractive index of silicon dioxide is, for example, 1.458. Other materials can be used as well.

[0192] The same reference numbers in all figures represent the same features.

[0193] FIG. 15 shows a second example configuration of the proposed device.

[0194] To improve light extraction, instead of the configuration example according to Fig. 15, a transparent second material 3 with a high refractive index can be applied to the light-emitting diode and patterned in a suitable manner. A suitable second material 3 with a high refractive index is, for example, Nb2O5. These alternatives are shown in Figs. 15 and 16.

[0195] A high refractive index may particularly be greater than 2. Other usable high refractive index materials include, for example, zinc sulfide with a refractive index of, for example, 2.37, diamond with a refractive index of, for example, 2.42, titanium dioxide with a refractive index of, for example, 2.52, silicon carbide with a refractive index of, for example, 2.65, and titanium dioxide with a refractive index of, for example, 3.10. These refractive indices occur particularly at the wavelength of the sodium D line, 589 nm. For example, the refractive index of niobium (V) oxide is 2.3. Other materials may also be used.

[0196] The semiconductor body providing the device has formed in its surface region 9 an extraction structure A. Similarly, the surface region 9 is also patterned here.

[0197] The patterning of the surface region 9 is effected by generating a random topology in the surface region 9, as in the case of Figure 14. According to Figure 14, the generation of the random topology is effected by directly roughening the surface 7 of the surface region 9 with the first material 1, whereas according to Figure 15 the random topology is formed by applying a transparent second material 3 with a high refractive index, in particular a refractive index greater than 2, to the surface region 9, in particular in the form of a layer, and roughening the second material 3.

[0198] This is followed by planarization, in particular by applying a transparent third material 5 having a low refractive index, in particular less than 1.5, to the patterned surface region 9. The third material 5 can be applied as a layer. The applied transparent third material 5 having a low refractive index can then be thinned until the highest peaks of the second material 3 having a high refractive index at the surface 7 of the patterned surface region 9 are flat and / or smooth.

[0199] The third material 5, which has a low refractive index and is transparent, can be SiO2, and is in particular provided by TEOS (tetraethyl orthosilicate). The thinning can be done by chemical mechanical polishing (CMP).

[0200] FIG. 16 shows an example of the configuration of the proposed device.

[0201] Alternatively, an ordered topology can be generated in the surface region 9 in order to pattern the surface region 9 .

[0202] In this case, a transparent second material 3 having a high refractive index, in particular a refractive index greater than 2, is applied to the surface region 9, in particular in the form of a layer, and an ordered topology is generated by patterning periodic photonic crystals or aperiodic photonic structures, in particular quasi-periodic or deterministic aperiodic photonic structures, in the second material 3.

[0203] Alternatively, it is also possible in principle to pattern periodic photonic crystals or aperiodic photonic structures, in particular quasi-periodic photonic structures or deterministic aperiodic photonic structures, directly into the first material 1 of the semiconductor body without using a second material 3. In this case, a device with an extraction structure A can be formed, in which the semiconductor first material 1 of the structural element is provided with a transparent third material 5 with a low refractive index, in particular SiO2, and the first material 1 can be patterned with periodic photonic crystals or aperiodic photonic structures, in particular quasi-periodic or deterministic aperiodic photonic structures.

[0204] Photonic crystals consist of patterned semiconductors, glasses, or polymers and are usually fabricated by methods known from microelectronics. Their special structure allows light to propagate through the medium in the way required for the component's function. This allows light to be guided to dimensions of the order of wavelength, as well as filtered and wavelength-selectively reflected.

[0205] These are periodic dielectric structures whose periodic length can be adjusted to affect the propagation of electromagnetic waves in the same way that periodic potentials affect the propagation of electrons in semiconductor crystals, and which therefore exhibit unique optical properties, such as Bragg reflection of visible light.

[0206] In particular, similar to the formation of an electronic band structure, a photonic band structure is formed, which can have a forbidden energy region (photonic band gap, PBG) where electromagnetic waves cannot propagate within the crystal. In other words, photonic crystals can be considered as the optical analogue of electronic semiconductors, that is, "optical semiconductors."

[0207] After patterning the periodic photonic crystal or aperiodic photonic structure, in particular a quasi-periodic or deterministic aperiodic photonic structure, a transparent third material 5 with a low refractive index is applied, in particular in the form of a layer, to the patterned surface region 9 and planarized. Suitable for this purpose is, for example, SiO2 deposited using TEOS (tetraethyl orthosilicate). Subsequently, the third material 5 is thinned until the highest peaks of the second material 3 with a high refractive index at the surface 7 are smoothed out.

[0208] A suitable process for thinning is CMP (chemical mechanical polishing), which uniformly removes layers with thicknesses in the micrometer and nanometer range. The resulting surface is flat and / or smooth. The roughness is in the range of a few nanometers, in particular as root mean square (rms) roughness values. The resulting planarized surface 7 can be used to transfer light-emitting diodes using conventional stamping techniques.

[0209] In this way, the removal efficiency can be improved compared to an untreated surface.Transfer processes using stamping techniques remain possible.

[0210] FIG. 17 shows an example of the configuration of the proposed method.

[0211] In a first step S1, a surface region 9 of the semiconductor body providing the device is patterned to form extraction structures A. In a second step S2, the patterned surface region 9 is planarized to obtain a planarized surface 7 of the surface region 9. This planarization comprises two sub-steps.

[0212] According to a first substep S2.1, a transparent third material 5 with a low refractive index, in particular below 1.5, is applied to the patterned surface region 9, in particular in the form of a layer.

[0213] In the second substep S2.2, the provided transparent third material 5 with a low refractive index is thinned until the highest peaks of the first material 1 of the semiconductor body or the highest peaks of the second material 3 with a high refractive index at the surface 7 of the patterned surface region 9 are flat and / or smooth.

[0214] In a third step S3, the transfer of the device can be carried out using stamping techniques, in which the semiconductor body is lifted up from the planarized surface 7.

[0215] In all of the configuration examples described below, the semiconductor materials may be in particular material systems of GaN, AlInGaP, AlN or InGaAs.

[0216] 18a and 18b show an optoelectronic device for emitting light, preferably perpendicularly from a light exit surface 21. The device comprises an array 11 with pixels, in which optically active nanostructures in the form of photonic crystals K are formed over the entire light-emitting surface of the light exit surface 21. Furthermore, the array 11 comprises an array of light sources, each with a recombination zone 2 located at a recombination surface 1.

[0217] The recombination zone 2 is formed in a first layer of optically active semiconductor material 3 of the array 11. In this layer comprising semiconductor material 3, photonic crystals or photonic crystal structures K are patterned, i.e. in the form of two-dimensional photonic crystals. Here, the photonic crystals K are arranged between the recombination zone 2 and the light exit surface 21. In this regard, the photonic crystal structures K may be arranged independently of the position of the individual pixels, with one pixel corresponding to one light source having the recombination zone 2 in the illustrated example.

[0218] The optically active photonic crystal structure K is free-standing in air or, as shown, filled with a first filling material 7, in particular SiO2, which is in particular electrically insulating and optically transparent and has a refractive index lower than that of the semiconductor material 3. The filling material 7 also advantageously has a low absorption coefficient.

[0219] In the array 11, the two electrical poles of each light source are electrically connected by an optically reflective contact layer 5. The contact layer 5 is located on the side of the optically active semiconductor material 3 that faces away from the optically active photonic crystal structure K, and is arranged at the bottom as shown in FIG. 1b. Such contact connection results in a very strong and localized recombination zone 2. Here, the contact layer 5 has at least two regions that are electrically insulated from each other so that the electrically separated poles can be connected.

[0220] The photonic crystal K can be patterned over the entire light-emitting surface 21 such that only light with a propagation direction at least approximately perpendicular to the surface 21 can leave the component. If the photonic crystal K is close to the recombination surface 1 and the layer thickness of the photonic crystal K is large compared to the distance to the recombination zone 2, the optical density of states in the light generation region will be further modified.

[0221] In this way, a complete bandgap of optical modes with a propagation direction parallel to a particularly flat, i.e. particularly planar and / or smooth, surface of the pixelated array 11 can be generated, with a small angle therebetween, in which case the emission of light with a propagation direction parallel to the light-emitting surface is completely suppressed.

[0222] In particular, light can be generated only within a limited emission cone specified by the photonic crystal K. In this case, directionality is already ensured at the light generation stage, effectively increasing efficiency compared to angle-selective optics that only affect light extraction.

[0223] The orientation of the photonic crystal K is independent of the position of the individual pixels, and no particular orientation of the pixel structure relative to the photonic structure K is required, allowing processing of the entire surface of the wafer.

[0224] It is advantageous if the device has uniform optical properties across the entire surface of the array 11, or which vary only slightly so as not to disturb the optical environment of the photonic crystal K.

[0225] 19a and 19b show a second proposed optoelectronic device in plan and cross-sectional views, respectively. In the pixelated array 11, the photonic crystal K is arranged in a second layer of material 9, specifically Nb2O5, on top of a first layer of optically active semiconductor material 3, as an alternative to the configuration shown in FIGS. 18a and 18b. Here, material 9 has a high optical refractive index and is arranged on a planar and / or smooth surface of semiconductor material 3. Advantageously, material 9 also has low absorption.

[0226] The photonic crystal K may also be formed as a free-standing two-dimensional photonic crystal from the aforementioned material 9, where the free space is air. In this way, the free space may be filled with a material 7 having a lower refractive index. The filling material may be, for example, SiO2.

[0227] The contact connections here are similar to those shown in FIGS. 18a and 18b, allowing for a very localized recombination zone 2.

[0228] 20a and 20b show a third proposed optoelectronic device in plan view and cross section, respectively. The device shown includes an arrangement of vertical light-emitting diodes 13 as a light source and, arranged in an overlying layer, a two-dimensional photonic crystal structure K extending beneath the entire light-emitting surface 21 and made of a material 9 with a high refractive index. The gaps in the structure K are filled with a filler material 7, which again has a low optical refractive index.

[0229] The vertically oriented light-emitting diode 13 has upper and lower electrical contacts along a vertically oriented longitudinal axis that extends perpendicular to the light-emitting surface 21. Thus, the light-emitting diode has an electrical contact on the front side and an electrical contact on the back side. Here, the side of the LED 13 that does not face the light-emitting surface 21 is referred to as the back side, while the front side faces the light-emitting surface 21.

[0230] The device includes an electrically conductive, light-reflecting contact layer 5 for electrically connecting the rear contacts of the LEDs 13. A third layer of an electrically conductive, optically transparent material 17, for example ITO, is provided for electrically connecting the front contacts of the LEDs 13. Via bonding wires 19, electrical connections can be made to the corresponding poles of a current source.

[0231] In and along the recombination surface 1 a further, in particular electrically insulating, filler material 15 may be arranged between the third layer and the optically reflective contact layer 5 .

[0232] 21a and 21b show a fourth proposed optoelectronic device in plan and cross-sectional views. The device includes an arrangement of lateral light-emitting diodes (LEDs) 13 with respective recombination zones 2 and an optically active two-dimensional photonic crystal structure K underlying the entire light-emitting surface 21. The photonic crystal structure K is in a layer of a high refractive index material 9, e.g., Nb2O5. The gap is also filled with a filler material 7 with a low optical refractive index, e.g., silicon dioxide.

[0233] In the case of a lateral light-emitting diode 13, the two electrical contacts are located on the rear surface of the light-emitting diode 13. The two poles of the LED 13 are in each case electrically connected by electrically isolated areas of the optically reflective contact layer 5.

[0234] In the region of the recombination surface 1, between the material layer 9 and the contact layer 5, a filling material 15, in particular an electrically insulating filling material 15, is arranged.

[0235] The light generation efficiency can be relatively high in the configurations described in Figures 18a to 21b. This is because in these configuration examples, light directionality or directional property can already be achieved during light generation, especially if the band structure of the photonic crystal K allows a higher density of photonic states in the region of the recombination zone 2 for light emission perpendicular to the light output surface. Furthermore, patterning of the photonic crystal K can be advantageously performed uniformly across the entire wafer. No specific positional or orientational relationship between the photonic crystal and the individual pixels or light-emitting diodes is required. This can significantly reduce the manufacturing effort, especially compared to alternative approaches that place structures individually for each pixel.

[0236] Figures 22a and 22b show a fifth proposed optoelectronic device in plan and cross-sectional views. The device includes a pixelated array 11 and an optically active pillar structure P, in particular a structure having pillars or columns patterned across an emitting surface 21. The array 11 is preferably smooth and flat.

[0237] The pixelated array 11 comprises pixels each with one light source comprising a respective recombination zone 2, where the recombination zone 2 of the pixel is located in a recombination plane 1, which is arranged in a first layer comprising an optically active semiconductor material 3.

[0238] On this first layer, pillar structures P are formed, where the pillars P are assigned to light sources, such that each pillar P is positioned directly above the recombination zone 2 of the assigned light source 2. In this regard, the longitudinal axis L of each pillar P passes in particular through the center M of the recombination zone 2 of the assigned light source 2.

[0239] The pillars P consist of a high refractive index material 9, for example Nb2O5. The spaces between the columns P may be filled with a low refractive index filler material 7, for example silicon dioxide.

[0240] The pillars P may be arranged above the layer comprising the light sources, in particular by additionally applying pillars P above the array 11. Alternatively, the pillars can be etched into the semiconductor material 3. For this purpose, the semiconductor material layer may be configured with a corresponding height. Since semiconductor materials usually have a high refractive index, the material can be etched away to leave the pillars 9. The areas vacated by the etching can be filled with a material with a lower refractive index.

[0241] The pillars P function like waveguides that guide light upward in the direction of the longitudinal axis L, and therefore the pillars P can improve the emission of light in a direction perpendicular to the light exit surface 21.

[0242] In the array 11, the two electrical poles of the light sources are electrically connected in each case by means of a reflective contact layer 5 in order to establish an electrical contact between the light sources and the recombination zone 2. The contact layer 5 is formed on the side of the semiconductor material that faces away from the optically active pillar structures P. The contact layer 5 can have two separate regions so that the two poles can be electrically contacted separately from each other. This type of contact leads to a very strong and localized recombination zone 2.

[0243] 23a and 23b show a sixth proposed optoelectronic device in plan view and cross-section. The device comprises an arrangement of vertical light-emitting diodes 13, also called LEDs, on top of which an optically active pillar structure P, in particular having a pillar or column, is arranged, with the longitudinal axis L of the pillar P passing at least substantially through the center point of the recombination zone 2 of the LEDs 13.

[0244] The pillar structure P may be free-standing in air or may be filled with a first, in particular electrically insulating and optically transparent, filling material 7 and arranged above the light-emitting diode. The filling material 7 may have a refractive index that is smaller than the refractive index of the material 9 of the pillar P and / or the semiconductor material 3 of the LED 3.

[0245] As already mentioned, the LEDs are vertical light-emitting diodes 13. They have one, particularly positive, electrical pole on their rear side facing the reflective contact layer 5 and another electrical pole on their front side facing the pillar P.

[0246] The pole on the front side of the light source is electrically connected to a corresponding current supply circuit (not shown) by a layer of electrically conductive and optically transparent material 17, in particular ITO, and by contact wires 19. The layer with material 17 is arranged between the light source and the pillar 17 as shown.

[0247] Thereby, the second filler material 15 may be disposed in gaps within the layers of the LED 13 and thus between the layer with material 17 and the contact layer 5 .

[0248] The dimensions of the pillar structures P may correspond to the dimensions of the light emitting diodes 13 or pixels of the array 11 .

[0249] Figures 24a and 24b show the seventh proposed optoelectronic device in plan view and cross-section. Unlike the variants of Figures 23a and 23b, the device shown in Figures 24a and 24b includes a horizontal light-emitting diode 13 arrangement, the electrical poles of which are arranged on the backside of the light-emitting diode 13. Therefore, for electrical contact, the electrical poles of the light source can be electrically connected via two electrically separated regions of the reflective contact layer 5. Therefore, an intermediate layer with material 17, as in the variant with vertical light-emitting diodes described above, is not required.

[0250] 18 to 21, the pillar P variant has significantly larger structures with diameters of up to 1 μm or more, making it easier to manufacture using standard techniques. This reduces process requirements, and high-resolution lithography is sufficient to manufacture the pillars.

[0251] Pillar structures, particularly pillars or columns, made of an optically active semiconductor material 3 or a material 9 with the highest possible refractive index can be precisely patterned above the individual pixels of the array 11 or above the vertical light-emitting diodes 13 (FIGS. 23a and 23b) or horizontal light-emitting diodes 13 (FIGS. 24a and 24b). The individual pixels or light-emitting diodes 13 may be less than 1 μm in diameter, and the pillars may have a height-to-diameter aspect ratio of at least 3:1. The pillars are preferably etched directly into the semiconductor material 3, as is possible in FIGS. 22a and 23b and 24a and 24b, since according to FIG. 23b no third layer 17 is formed. Alternatively, the pillars are made of another material 9 with a high refractive index and preferably low absorption, which is applied to the surface of the array 11. Nb2O5, for example, is conceivable as a material with a high refractive index. The pillar structures may be freestanding or filled with a material 7 with a low refractive index. An example of a low-refractive-index filler material is SiO2. Because the refractive index of the pillars is higher than that of the surrounding material, light emitted parallel to the longitudinal axis of the pillars is enhanced compared to other spatial directions. Due to the waveguide effect, light along the longitudinal axis of the pillars is extracted more efficiently than light propagating in other directions. This can improve the directivity or directionality of the emitted light.

[0252] Figures 25a and 25b show in plan and cross-sectional views an eighth proposed optoelectronic device, which comprises an arrangement of light-emitting diodes 13, each formed as a pillar P and thus in the shape of a column.

[0253] The length of the pillars P corresponds to half the wavelength of the light emitted in the semiconductor material 3, and the recombination zone 2 may advantageously be located at the center M of each pillar and thus at the local maximum of the photonic density of states. The height:diameter aspect ratio of the pillars P may be at least 3:1.

[0254] In the illustrated arrangement, the pillars P can be approximately 100 nm high and only approximately 30 nm in diameter, which requires very fine-resolution patterning techniques that are difficult to translate at the wafer level with current manufacturing techniques.

[0255] Alternatively, the dimensions can be scaled up for ease of fabrication, in which case the directionality of the emitted light decreases as the size of the pillar patterning increases. The length of the pillar P is preferably a multiple of half the wavelength of the emitted light in the semiconductor material, and each recombination zone 2 can be located at a maximum of the density of photonic states.

[0256] Due to the pillar patterning of the LED 13, light emission parallel to the longitudinal axis of the pillar P is effectively enhanced due to a greater density of photonic states. Due to the waveguide effect, light having a propagation direction along the longitudinal axis of the pillar P is extracted more efficiently than light having other propagation directions. The space between the pillars P is filled with a material 7, which advantageously has a very low absorption coefficient and a refractive index smaller than that of the semiconductor material 3. An example of a filling material with a small refractive index is SiO2.

[0257] In this arrangement of light-emitting diodes 13 shaped as pillars P or columns, in particular vertical light-emitting diodes 13, a first pole, in particular a positive first pole, is in each case electrically connected by a reflective contact layer 5 for contact-connection to a recombination zone 2 arranged in the recombination surface 1. The contact layer 5 is formed at a first longitudinal end on the underside of the light-emitting diode 13.

[0258] The other, in each case the second, particularly negative, pole is electrically connected to a third layer of conductive transparent material 17, in particular ITO, and is connected by a bonding wire 19, for example, to a corresponding pole of a current supply circuit.

[0259] According to this arrangement, the third layer is formed in and along the recombination surface 1 at the longitudinal center of the light-emitting diode 13 shaped as a pillar P or column.

[0260] Figures 26a and 26b show a ninth proposed optoelectronic device in plan view and cross-section. In contrast to the variant of Figures 25a and 25b, the device according to Figures 26a and 26b has a vertical LED formed as a pillar P.

[0261] The lower electrical contact, in particular the p-type contact, is established via the lower surface of the pillar P, in particular by contact connection to the contact layer 5 .

[0262] The top electrical contact, in particular the n-type contact, is on the upper side of the pillars P. This contact is established via a top layer of an optically transparent and electrically conductive material 17 that extends over the pillars P and a first filling material 7 that fills the gaps between the pillars P. The top layer material 17 can be, for example, ITO (indium tin oxide). Via bonding wires 19, connections to a current supply circuit can be established.

[0263] By electrically contacting the light-emitting diodes within the pillars P, a very strong localized recombination zone 2 is created, and a top contact, in particular an n-type contact, can be formed at the level of the recombination zone 2 or on the upper side of the pillars P. Each pillar P creates an individual pixel.

[0264] The pillar-shaped light-emitting diodes 13 shown in Figures 25a-26b have enhanced light emission parallel to their longitudinal axes, which improves the directionality of the emitted light compared to conventional low aspect ratio light-emitting diodes. Compared to the arrangements shown in Figures 22a-24b, the arrangements shown in Figures 25a-26b can significantly influence the light generation process, thereby achieving higher directionality and efficiency.

[0265] 27 shows a cross-sectional view of a further optoelectronic device in which a two-dimensional photonic crystal K is arranged on top of a layer in which an array of light sources having a recombination zone 2 is arranged. In this case, the photonic crystal K is arranged in the region near the recombination zone 2 in such a way that it changes the optical density of states present in the region of the recombination zone 2, in particular in such a way that a band gap of at least one optical mode having a propagation direction parallel and / or at a small angle to the light output surface 21 is created and / or the density of states of at least one optical mode having a propagation direction perpendicular to the light output surface 21 is increased.

[0266] This is achieved in particular by the height H of the photonic crystal K being at least 300-500 nm, preferably at most 1 μm. The height H of the photonic crystal may depend on the high refractive index material of the photonic crystal.

[0267] Furthermore, preferably, the distance A between the center M of the recombination zone 2 and the lower surface of the photonic crystal K is at most 1 μm, preferably a few nm.

[0268] All the configurations described using the photonic crystal K are advantageously two-dimensional photonic crystals in which the optical refractive index varies periodically in two perpendicular spatial directions extending parallel to the light exit surface, and more advantageously pillar structures in which the pillars P or columns are arranged in an array such that the longitudinal axes L of the pillars P extend perpendicular to the light emitting surface 21.

[0269] Possible fields of application for the devices described herein include, for example, the automotive, all types of lighting, home appliances and video walls.

[0270] Features mentioned in connection with one embodiment and / or claim may be combined with other embodiments and / or claims even if the features are not mentioned in connection with other embodiments and / or claims.

Claims

1. 1. An optoelectronic device comprising: an arrangement (11) comprising a plurality of light sources for generating light emitted from a light exit surface of the optoelectronic device; At least one photonic structure (K, P) arranged between the light exit surface and the plurality of light sources; 1. An optoelectronic device comprising: the photonic structure is configured to beam shape light generated by the light source such that the light exits the light exit surface at least substantially perpendicularly; light diffusion along at least one first spatial direction (R1) is inhibited; The photonic structure has a photonic crystal (K), each of the light sources has a recombination zone, and the photonic crystal is arranged in a region adjacent to the recombination zone such that the photonic crystal modifies the optical density of states present in the region of the recombination zone, creating a band gap for at least one optical mode whose propagation direction is parallel and / or at a small angle to the light output surface; An optoelectronic device comprising:

2. 2. The optoelectronic device according to claim 1, wherein the arrangement structure (11) is an array having a plurality of pixels arranged in a layer as light sources, and a photonic crystal is arranged or formed in the layer.

3. 2. The optoelectronic device of claim 1, wherein the arrangement structure (11) is an array having a plurality of pixels arranged in a first layer as light sources, and a photonic crystal arranged in a further second layer, wherein the second layer is arranged between the first layer and the light exit surface.

4. 2. The optoelectronic device of claim 1, wherein the arrangement structure (11) has a plurality of LEDs arranged in a first layer as light sources, and a photonic crystal arranged in a further second layer, the second layer being arranged between the first layer and the light emitting surface.

5. the photonic crystal (K) is arranged with respect to a plane extending parallel to the light exit surface, and / or the photonic crystal is a two-dimensional photonic crystal having a periodic change in optical refractive index in two spatial directions perpendicular to each other within the plane; An optoelectronic device according to any one of claims 1 to 4.

6. 6. An optoelectronic device according to claim 1, wherein the photonic structure comprises a plurality of pillar structures (P) extending at least partially between the light emitting surface and the plurality of light sources, each pillar being assigned to one light source and aligned so as to be coplanar with the light emitting surface when viewed in a direction perpendicular to the light emitting surface.

7. 7. The optoelectronic device of claim 6, wherein the arrangement structure (11) is an array having a plurality of pixels arranged on a first layer as light sources, and the pillars are arranged on a further second layer, wherein the second layer is arranged between the first layer and the light exit surface.

8. 7. The optoelectronic device of claim 6, wherein the arrangement structure (11) has a plurality of LEDs arranged in a first layer as light sources, and the pillars are arranged or formed in a further second layer, wherein the second layer is arranged between the first layer and the light exit surface.

9. 7. An optoelectronic device according to claim 6, wherein the arrangement structure (11) is an array having a plurality of pixels as light sources, each pixel being formed by a respective pillar.

10. 1. An optoelectronic device comprising: an arrangement (11) comprising a plurality of light sources for generating light emitted from a light exit surface of the optoelectronic device; At least one photonic structure (K, P) arranged between the light exit surface and the plurality of light sources; It has In optoelectronic devices, the photonic structure is configured to beam shape light generated by the light source such that the light exits the light exit surface at least substantially perpendicularly; light diffusion along at least one first spatial direction (R1) is inhibited; the photonic structure includes a plurality of pillar structures (P) extending at least partially between the light exit surface and the plurality of light sources, each pillar being assigned to one light source, and the plurality of pillar structures (P) being aligned so that end faces are flush with the light exit surface; An optoelectronic device comprising:

11. 11. The optoelectronic device of claim 10, wherein the arrangement structure (11) is an array having a plurality of pixels arranged on a first layer as light sources, and the pillars are arranged on a further second layer, wherein the second layer is arranged between the first layer and the light exit surface.

12. 11. The optoelectronic device of claim 10, wherein the arrangement structure (11) has a plurality of LEDs arranged in a first layer as light sources, and the pillars are arranged or formed in a further second layer, wherein the second layer is arranged between the first layer and the light exit surface.

13. 11. The optoelectronic device according to claim 10, wherein the arrangement structure (11) is an array having a plurality of pixels as light sources, where each pixel is formed by a respective pillar.

14. A method for manufacturing an optoelectronic device according to any one of claims 1 to 13, comprising the steps of: providing or manufacturing an arrangement (11) comprising a plurality of light sources for generating light to be emitted from a light emitting surface of the optoelectronic device; The method further comprises disposing at least one photonic structure (K, P) between said light exit surface and said plurality of light sources.

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