ILLUMINATION UNIT, METHOD FOR PRODUCING AN ILLUMINATION UNIT, CONVERTER ELEMENT FOR AN OPTOELECTRONIC COMPONENT, RADIATION SOURCE INLCUDING AN LED AND A CONVERTER ELEMENT, OUTCOUPLING STRUCTURE, AND OPTOELECTRONIC DEVICE

Abstract

An illumination unit includes: at least one optoelectronic emitter unit which emits electromagnetic radiation via a light-emitting surface, and a photonic structure for beam shaping of the electromagnetic radiation before it exits via the light emitting surface, wherein the photonic structure shapes the electromagnetic radiation such that the electromagnetic radiation has a certain far field.

Claims

1-75. (canceled)

76. A lighting device, comprising: at least one optoelectronic emitter unit which emits electromagnetic radiation via a light emission surface; and a photonic structure for beam shaping the electromagnetic radiation before it exits via the light emitting surface, wherein the photonic structure shapes the electromagnetic radiation such that the electromagnetic radiation comprises a certain far field.

77. The lighting device according to claim 76, wherein the photonic structure is a one-dimensional photonic structure, in particular a one-dimensional photonic crystal.

78. The lighting device according to claim 76, wherein the photonic structure is formed as a one-dimensional photonic crystal in such a way that the radiated electromagnetic radiation is at least approximately collimated in a first spatial direction.

79. The lighting device according to claim 78, wherein a collimating optical system is arranged downstream of the light-emitting surface, as seen in the main radiation direction, the optical system being designed to collimate the electromagnetic radiation in a further, second spatial direction, which runs orthogonally to the first spatial direction.

80. The lighting device according to claim 76, wherein the photonic structure formed as a one-dimensional photonic crystal is configured in such a way that a main radiation direction of the electromagnetic radiation runs at an angle to the normal of the light emission surface, the angle not being equal to zero degrees.

81. The lighting device according to claim 80, wherein the photonic structure formed as a one-dimensional photonic crystal is arranged in a layer below the light-emitting surface, the one-dimensional photonic crystal having a periodically repeating sequence of two materials with different optical refractive indices extending in a first direction, the materials having mutually abutting interfaces which are not orthogonal but inclined to the light-emitting surface.

82. The lighting device according to claim 76, wherein the photonic structure is a two-dimensional photonic structure, in particular a two-dimensional photonic crystal.

83. The lighting device according to claim 82, wherein the two-dimensional photonic structure is designed in such a way that the electromagnetic radiation generates a defined, in particular a discrete, pattern in the far field.

84. The lighting device according to claim 76, wherein the photonic structure is arranged in a layer, in particular a semiconductor layer, below the light-emitting surface; and/or wherein the photonic structure is formed in a semiconductor layer of the optoelectronic emitter unit; and/or wherein the optoelectronic emitter unit comprises a layer with converter material, and the photonic structure is formed in the layer with converter material or in a layer between the layer with converter material and the light emission surface.

85. The lighting device according to claim 76, wherein the photonic structure is a quasiperiodic or deterministically aperiodic photonic structure.

86. A method of manufacturing a device, in particular an electronic component, in particular an opto-electronic component, in particular a light-emitting diode, comprising: creating a decoupling structure in a surface region of a semiconductor body providing the device by: structuring the surface region; and planarizing the structured surface region to obtain a planarized surface of the surface region; wherein structuring the surface region includes generating a random topology at the surface region; and wherein generating the random topology includes applying, in particular layer by layer, a transparent second material having a large refractive index, in particular greater than 2, to the surface region and roughening the second material.

87. The method according to claim 86, wherein generating the random topology includes directly roughening the surface of the surface region of the semiconductor body comprising a first material.

88. The method according to claim 86, wherein structuring the surface area includes creating an ordered topology at the surface area.

89. The method according to claim 88, wherein producing the ordered topology includes applying, in particular layer by layer, a transparent second material having a large refractive index, in particular greater than 2, to the surface region and structuring periodic photonic crystals or non-periodic photonic structures, in particular quasi-periodic or deterministic aperiodic photonic structures, into the second material.

90. The method according to claim 86, wherein the transparent second material with the large refractive comprises index Nb2O5.

91. The method according to any claim 86, wherein planarizing includes a first substep of applying, in particular layer by layer, a transparent third material with a small refractive index, in particular less than 1.5, to the structured surface region.

92. The method according to claim 91, wherein planarizing includes a second sub-step of a thinning of the attached transparent third material with small refractive index until the surface of the structured surface area ends plane and/or smooth with highest elevations in the first material of the semiconductor body or in the second material with large refractive index.

93. The method according to claim 92, wherein the transparent third material comprises SiO2 with a small refractive index and is applied in particular by means of TEOS (tetraethyl orthosilicate).

94. The method according to claim 92, wherein thinning includes chemical mechanical polishing (CMP).

95. The method according to claim 92, further comprising transferring the device by stamping technology.

96. A device, in particular electronic component, in particular opto-electronic component, in particular light-emitting diode, comprising: a decoupling structure in a surface region of a semiconductor body providing the device by patterning the surface region; a planarized surface of the surface region; and an outcoupling structure comprising a transparent third material with a small refractive index, in particular SiO2, on a roughened transparent second material with a large refractive index, in particular Nb2O5, the second material being attached to a first material of the semiconductor of the device.

97. The device according to claim 96, wherein the planarized surface is flat and/or smooth and has a roughness in the range of less than 20 nanometers, in particular less than 1 nanometer, as mean roughness value.

98. The device according to claim 96, wherein the decoupling structure comprises the transparent third material on a roughened portion of the first material of the semiconductor of the device.

99. The device according to claim 96, the second material being attached to the first material of the semiconductor of the device and comprising periodic photonic crystals or non-periodic photonic structures, in particular quasi-periodic or deterministic aperiodic photonic structures.

100. An optoelectronic device, comprising: an arrangement comprising a plurality of light sources for generating light emerging from a light emitting surface from the optoelectronic device; and at least one photonic structure disposed between the light emitting surface and the plurality of light sources.

101. The optoelectronic device according to claim 100, wherein the photonic structure is designed for beam shaping of the light generated by the light sources, in particular in such a way that the light emerges at least substantially perpendicularly from the light emitter surface.

102. The optoelectronic device according to claim 100, wherein the photonic structure has a photonic crystal.

103. The optoelectronic device according to claim 100, wherein the device is an array comprising a plurality of pixels as light sources arranged in a layer, and that a photonic crystal is arranged or formed in the layer.

104. The optoelectronic device according to claim 100, wherein the device is an array comprising as light sources a plurality of pixels arranged in a first layer, and that a photonic crystal is arranged in a further, second layer, the second layer being located between the first layer and the light emitting surface.

105. The optoelectronic device according to claim 100, wherein the device comprises as light sources a plurality of LEDs arranged in a first layer, and that a photonic crystal is arranged in the further, second layer, the second layer being located between the first layer and the light emitting surface.

106. The optoelectronic device according to claim 100, wherein each of the light sources comprises a recombination zone and the photonic crystal is located close to the recombination zones in such a way that the photonic crystal changes an optical density of states present in the region of the recombination zones, in particular in such a way that a band gap is generated for at least one optical mode with a propagation direction parallel and/or at a small angle to the light emitter surface.

107. The optoelectronic device according to claim 100, wherein the photonic crystal is arranged with respect to a plane parallel to the light-emitting surface independently of the positioning of the light points; and/or wherein the photonic crystal is a two-dimensional photonic crystal which exhibits a periodic variation of the optical refractive index in two mutually perpendicular spatial directions spanning the plane.

108. The optoelectronic device according to claim 100, wherein said photonic structure comprises a plurality of pillar structures extending at least partially between said light emitting surface and said plurality of light sources, each pillar being associated with a light source and aligned with said light emitting surface as viewed in a direction perpendicular thereto.

109. The optoelectronic device according to claim 108, wherein the arrangement is an array comprising as light sources a plurality of pixels arranged in a first layer, and that the pillars are arranged in a further, second layer, the second layer being located between the first layer and the light emitting surface.

110. The optoelectronic device according to claim 108, wherein the arrangement comprises as light sources a plurality of LEDs arranged in a first layer, and that the pillars are arranged or formed in a further, second layer, the second layer being located between the first layer and the light emission surface.

111. The optoelectronic device according to claim 108, wherein the arrangement is an array comprising a plurality of pixels as light sources, each pixel being formed by a respective pillar.

112. A method of manufacturing an optoelectronic device according to claim 100, wherein an arrangement having a plurality of light sources for generating light emerging from a light emitting surface from the optoelectronic device is provided or fabricated; and at least one photonic structure is disposed between the light emitting surface and the plurality of light sources.

Description

[0137] In the following, exemplary embodiments of the invention are explained in more detail with reference to the attached figures.

[0138] The figures show, schematically in each case:

[0139] FIG. 1 a perspective view of a first variant of a lighting unit according to the invention.

[0140] FIG. 2 a sectional view of a second variant of a lighting unit according to the invention.

[0141] FIG. 3 an arrangement of a plurality of lighting units of FIG. 2.

[0142] FIG. 4 a perspective view of a fourth variant of a lighting unit according to the invention.

[0143] FIG. 5 a block diagram of a surface topography detection system with an illumination unit of FIG. 4.

[0144] FIG. 6 an illumination unit with an emitter unit that has a light-emitting surface on which a polarization element with a three-dimensional photonic structure is applied.

[0145] FIG. 7 a representation of a three-dimensional photonic structure with a plurality of spiral-shaped structural elements.

[0146] FIG. 8 an illumination unit with an emitter unit having a light-emitting surface on which a polarization element with a three-dimensional photonic structure having wavelength-selective properties is applied.

[0147] FIG. 9 an illumination unit with an emitter unit and a three-dimensional photonic structure in which converter material is filled.

[0148] FIG. 10 a top view and sectional view of a radiation source, with an LED and a converter element formed by a patterned layer filled with converter material located only in the uppermost layer of the LED semiconductor material.

[0149] FIG. 11 a cross-section of a radiation source having an LED, a converter element formed by a patterned layer filled with converter material located only in the uppermost layer of the LED semiconductor material, and a filter layer applied to the uppermost layer of the LED semiconductor material.

[0150] FIG. 12 a top view and sectional view of a radiation source with LED and converter element formed by a structured layer filled with converter material extending into the active zone of the LED semiconductor material.

[0151] FIG. 13 a cross-section through a radiation source having an LED, a converter element formed by a patterned layer filled with converter material extending into the active region of the LED semiconductor material, and a filter layer applied to the uppermost layer of the LED semiconductor material.

[0152] FIG. 14 an embodiment of a proposed device.

[0153] FIG. 15 another embodiment of a proposed device.

[0154] FIG. 16 another embodiment of a proposed device.

[0155] FIG. 17 an embodiment of a proposed method.

[0156] FIG. 18a a first proposed device in a plan view.

[0157] FIG. 18b the first proposed device in cross section.

[0158] FIG. 19a a second proposed device in a plan view.

[0159] FIG. 19b the second proposed device in cross-section.

[0160] FIG. 20a a third proposed device in a plan view.

[0161] FIG. 20b the third proposed device in cross-section.

[0162] FIG. 21a a fourth proposed device in a plan view.

[0163] FIG. 21b the fourth proposed device in cross-section.

[0164] FIG. 22a a fifth proposed device in a plan view.

[0165] FIG. 22b the fifth proposed device in cross-section.

[0166] FIG. 23a a sixth proposed device in a plan view.

[0167] FIG. 23b the sixth proposed device in cross-section.

[0168] FIG. 24a a seventh proposed device in a plan view.

[0169] FIG. 24b the seventh proposed device in cross-section.

[0170] FIG. 25a a top view of an eighth proposed device.

[0171] FIG. 25b the eighth proposed device in cross-section.

[0172] FIG. 26a a ninth proposed device in a plan view.

[0173] FIG. 26b the ninth proposed device in cross-section.

[0174] FIG. 27a a cross-sectional view of a further variant of a device according to the invention.

[0175] The illumination unit 11 shown in FIG. 1 comprises at least one optoelectronic emitter unit 13, which is designed to emit electromagnetic radiation 19, such as visible or infrared light of a wavelength, via a light emitter surface 15. In this regard, a photonic structure 17 is provided for beam shaping the electromagnetic radiation before it exits via the light emitting surface 15. The photonic structure 17 shapes the electromagnetic radiation 19 such that the electromagnetic radiation 19 has a defined characteristic 23 in the far field 21.

[0176] In particular, the photonic structure 17 of the illumination unit 11 of FIG. 1 is a one-dimensional photonic crystal 25. In the variant shown, this extends to the light-emitting surface 15. The end face of the photonic crystal 25 thus forms the light-emitting surface 15. The one-dimensional photonic crystal 25 exhibits a periodic variation of the optical refractive index along a first direction R1.

[0177] The crystal 25 or periodic variation is set to beamform electromagnetic radiation emitted from a light source (not shown) of the emitter unit. In particular, light propagation along the first direction R1 is blocked. As a result, the radiated emitted radiation 19 exhibits only a slight extension along the first direction R1 in the far field 21. Thus, a characteristic feature of the electromagnetic radiation 19 in the far field 21 is that it forms a narrow strip 27. The electromagnetic radiation 19 is therefore collimated with respect to the first direction 19.

[0178] The light source is in particular an LED. This is typically a Lambertian radiator. By using the photonic structure 17 and the resulting beam shaping, a directed, collimated electromagnetic radiation 19 can be generated.

[0179] As FIG. 1 schematically shows, the emitted electromagnetic radiation 19 leaves the emitter unit 13 in the form of a light cone fanning out essentially along a second direction R2. The central axis of the light cone extends along a main radiation direction H which is perpendicular to the light emission surface 15. Not shown is an optional collimating optical system arranged downstream of the light-emitting surface 15, as seen in the main radiation direction H. The optional optical system can be used to fan out the electromagnetic light cone. By means of the optics, the electromagnetic radiation 19 can be collimated in the second spatial direction R2, which extends orthogonally to the first spatial direction R1. The electromagnetic radiation 19 can thus be collimated in the far field 21 with respect to the two directions R1, R2. A luminous point is formed.

[0180] An illumination device 11 according to FIG. 1 is particularly well suited for use in an optical scanner. In this case, the illumination device 11 can be used in particular for line scan applications due to the strip-like light image in the far field 21.

[0181] In the illumination device 11 shown in FIG. 2, a one-dimensional photonic crystal 25 is formed on the top surface of the emitter unit 13. The face of the crystal 25 forms the light emitting surface 15 for electromagnetic radiation generated by an optoelectronic light source, for example an LED, which is not shown, and is emitted through the photonic crystal 25 via the light emitting surface 25.

[0182] In contrast to the variant according to FIG. 1, in the illumination unit of FIG. 2 the main radiation direction H of the electromagnetic radiation 19 runs at an angle α to the normal N of the light emission surface 15. The angle α is not equal to zero degrees. For example, the angle α can be in the range between 30 and 60 degrees. This is achieved by the one-dimensional photonic crystal 25 having a periodically repeating sequence of two materials 31, 33 with different optical refractive indices extending in a first direction R1. The materials 31, 33 have a parallelogram-like cross-section and abutting interfaces of the materials 31, 33 do not run orthogonally but inclined to the light-emitting surface 15, as schematically shown in FIG. 2.

[0183] Such a structure can be formed, for example, by etching trenches 29 running parallel to each other at an angle to the light-emitting surface 15 into the substrate 31 having the light-emitting surface 15. The trenches 29 may be filled with a material 33 having a different optical refractive index than the substrate material 33 etched away, and the angle α may depend on the slope of the trenches 29 with respect to the light-emitting surface 15. The width of the trenches 29 and the width of any respective substrate material 31 remaining between two trenches 29 will affect the wavelengths at which the photonic crystal 25 can have an effect. Typically, the width of the trenches 29 and the width of the substrate material 33 located between two trenches, and thus the periodicity of the photonic crystal structure 25, are matched to the wavelength of electromagnetic radiation provided by the light source or a converter material located between the light source and the photonic crystal.

[0184] By means of the one-dimensional photonic crystal 25, the illumination unit 11 of FIG. 2 can again generate a light strip 27 in the far field 21, as were described 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 tilted by an angle α with respect to the normal N. By means of downstream collimation optics, the strip 27 can be brought into a point or circular structure in the far field 21.

[0185] The variant shown in FIG. 3 comprises a line-like or array-like arrangement of a plurality of illumination units 11 of FIG. 2. The light beams 19 emitted by the individual illumination units 11 have the same main radiation direction H. The light beams 19 can also be collimated by an additional, collimating optical system 35, in particular a lens. The light beams 19 can also be collimated by an additional collimating optical system 35, in particular a lens, in a second direction which is perpendicular to the image plane in the representation of FIG. 2. Thus, a point or circular image of the emitted radiation 19 is obtained in the far field behind the optics 35.

[0186] The use of a photonic crystal in an illumination device 11 according to FIGS. 2 and 3 results in an effectively higher resolution for a line- or array-like arrangement of the illumination devices 11 according to FIG. 3. In addition, smaller beam cross sections can be realized, in particular in the far field downstream of the optics 35. Since collimation in the first direction R1 (cf. FIG. 2) is already performed by the photonic crystals 25 integrated in the illumination devices 11, the optics 35 and possibly further, subsequent optics can be designed more compactly.

[0187] In the variant of FIG. 4, the illumination unit 11 comprises a photonic structure 17, which is a two-dimensional photonic crystal 37 whose end face forms the light emission surface 15. Viewed from the light emission surface 15, at least one optoelectronic light source, optionally with converter material, is arranged behind the photonic crystal 37. The photonic crystal 37 is designed to shape the electromagnetic radiation 19 emitted via the light-emitting surface in such a way that it generates a defined, discrete, pattern 39 in the far field 21. In the example shown, the pattern 39 comprises a plurality of distributed light spots 41, although other patterns are possible.

[0188] The illumination unit 11 of FIG. 4 is suitable for use, for example, in a surface topography detection system 43 exemplified in the block diagram of FIG. 5. In addition to the illumination unit 11, the system 43 includes a detection unit 45 having a camera 47 configured to detect the pattern 39 when it illuminates an object (not shown).

[0189] Further provided is an analysis device 49 adapted to determine a distortion of the pattern 39 with respect to a predetermined reference pattern. The reference pattern may be determined, for example, from the detection of the pattern 39 when it is projected onto a flat surface.

[0190] The analysis device 49 is further configured to determine a shape and/or a structure of the object illuminated by the pattern 39 in the far field 39 as a function of the determined distortion of the pattern 39. By means of the system 43, a face recognition can thus be realized, for example.

[0191] In the variant according to FIG. 4, downstream optics for pattern generation can be dispensed with, since the pattern 39 can already be generated by means of the photonic crystal 37. The illumination device 11 according to FIG. 4 and, consequently, the system 43 according to FIG. 5 can therefore be realized in a particularly compact form.

[0192] FIG. 6 shows an illumination unit 1 with an emitter unit 2, which has a light emission surface 3 on which a polarization element 4 in the form of a polarization layer with a three-dimensional photonic structure is applied. According to the embodiment example shown in FIG. 6, the emitter unit 2 is an LED 5 that emits light in the visible or possibly also in the ultraviolet wavelength range. The light emitted by the LED 5 is guided into the three-dimensional photonic structure and polarized here in a specific direction of oscillation, depending on the embodiment and dimensions of the structure. Depending on the design of the three-dimensional photonic structure, circular or linear polarization can take place. It is essential that only light with a certain polarization is emitted by the illumination unit 1.

[0193] If the three-dimensional photonic structure of the polarization element 4 has spiral-shaped structural elements 6, as shown in FIG. 7, circular polarization takes place. If, on the other hand, the structural elements of the three-dimensional photonic structure are rod-shaped, in particular as so-called nanorods, linear polarization of the radiation guided through the three-dimensional photonic structure is effected as a result.

[0194] The illumination unit 1 shown in FIG. 6 is manufactured using the two-photon lithography process, the glancing angle deposition process, laser interference lithography or holographic structuring. In this context, it is noted that the spiral-shaped structural elements 6 shown in FIG. 7 have been produced using the glancing angle deposition process.

[0195] An illumination unit 1, as shown in FIG. 6, can be combined in an advantageous manner with further illumination units that have complementary properties. Thus, illumination units 1 for image generation are combined which have different polarization and/or transmission properties.

[0196] Radiation generated by multiple illumination units, each with complementary properties, polarized in different directions of oscillation is preferably imaged onto a display or screen using common optics. Such devices can advantageously be used in applications to generate three-dimensional images.

[0197] With the three-dimensional photonic structure arranged on the surface or the light emission surface 3 of an LED chip according to FIG. 6, which forms a polarization element 4, it is possible to generate light with fundamentally different properties, in particular with defined polarization, than is possible with currently known LEDs. The major advantage here is that, due to the provision of a three-dimensional photonic structure on the chip surface, no additional optical components, such as a classic polarization filter, are required. The illumination unit can therefore be designed comparatively small. Due to the structuring directly on the semiconductor chip of the LED 5, such an illumination unit 1 is also more energy-efficient than the known illumination units in which a subsequent selection of the polarization takes place. Any photon that does not pass through the three-dimensional photonic structure due to its properties remains in the LED chip and can be re-emitted by a reabsorption process.

[0198] FIG. 8 shows an illumination unit 1 with an emitter unit 2 having a light-emitting surface 3 on which a polarizing element 4 with a three-dimensional photonic structure having wavelength-selective properties is applied.

[0199] In this case, the photonic structure is designed as a three-dimensional photonic crystal. Alternatively, several two-dimensional photonic crystals can be arranged in layers on top of each other.

[0200] The three-dimensional photonic structure is designed in such a way that it has a wavelength-specific transmittance and polarization properties. This means that the transmittance and the polarization properties of the three-dimensional photonic structure vary depending on the wavelength of the incident radiation.

[0201] The illumination unit 1 shown in FIG. 8 has an emitter unit, which in turn has an LED 5. Furthermore, a converter element 7 with a layer of converter material is provided. The converter material emits, due to excitation by excitation radiation 8 emitted from the LED 5, a converted radiation 9 having a wavelength changed from the wavelength of the excitation radiation 8.

[0202] If both unconverted excitation radiation 8 and converted radiation 9 impinge on the three-dimensional photonic structure, these radiations are influenced in different ways depending on their wavelength with respect to transmission and polarization. As can be seen in FIG. 8, the converted radiation 9 is coupled out perpendicular to the surface of the LED chip, while the excitation radiation 8 is deflected laterally.

[0203] Such illumination units can be used in a preferred manner in components in which radiation with different wavelengths is generated, whereby different functions can be implemented in a combination of LEDs and converter elements. Depending on the design of the three-dimensional photonic structure as well as the wavelength of the excitation radiation 8 emitted by an LED in each case, it is possible to achieve complete suppression of the excitation radiation 8 while the converted radiation 9 radiates through the three-dimensional photonic structure. Similarly, it is conceivable that the excitation radiation 8 is deflected while the converted radiation 9 is coupled out perpendicular to the chip surface, as shown in FIG. 8. Of course, the mechanism can also be the other way around. Furthermore, it is also conceivable to polarize the converted radiation 9 in a special way, while the excitation radiation 8 emerges unchanged over the chip surface. Here, too, the mechanism can be reversed.

[0204] The variant of an illumination unit shown in FIG. 9 comprises an emitter unit, here again in the form of an LED 15, and a three-dimensional photonic structure 11, for example in the form of a spiral. Converter material 13 is filled into the structure 11.

[0205] FIG. 10 shows in a top view and a sectional view a radiation source 6 with an LED and with a layer 2 arranged in a semiconductor substrate 8 of the LED 7, which has a structure 4 with a suitable converter material. The structured layer 2 with the converter material forms a converter element 1, wherein the converter material emits converted radiation into an emission area 3 of the radiation source 6 when excited by the excitation radiation emitted by the LED 7.

[0206] The structure 4 provided in the layer 2 with the converter material is designed in such a way that the converted radiation is emitted exclusively as a directed beam into a specific radiation area 3.

[0207] According to the embodiment example shown in FIG. 10, the converted radiation is emitted perpendicular to a plane in which the LED chip with its semiconductor substrates is located.

[0208] The patterned layer 2 shown in FIG. 10 is a two-dimensional photonic crystal etched into the LED semiconductor substrate. The individual, here rod-shaped, recesses of the structure 4 have been filled with the converter material. The layer thickness of the structure 4 is at least 500 nm, so that a band gap is created in the crystalline solid material, which causes directionality of the converted radiation emitted by the converter element 1.

[0209] By means of such a photonic structure, the directionality and thus also the efficiency, in particular also of etendue-limited systems, can be considerably increased. Due to the provision of a layer 2 with a corresponding structure 4 and suitable converter material directly on the surface of the LED 7, the otherwise additionally provided optical elements can be dispensed with and thus a comparatively small radiation source can be realized by exploiting the invention.

[0210] The radiation source 6 shown in FIG. 10 can also be used to realize very small components, such as pixelated LED arrays for high-resolution displays, or integrated components, for example for the field of consumer electronics.

[0211] Incidentally, an energetically particularly efficient radiation source is provided since, on the one hand, no light is emitted in a direction that is not required and is not perpendicular to the LED chip surface and, on the other hand, all of the converted light can be used. Furthermore, modes of the excitation radiation emitted by the LED 7, which are guided in the active zone 9 and have a low extraction efficiency from the LED 7, can thus also be converted efficiently.

[0212] In addition, FIG. 11 shows a sectional view of a radiation source 6 which is designed as explained in connection with FIG. 10, but additionally has a filter element 5 applied to the uppermost layer of the radiation source 6 in the form of a filter layer 5 which is opaque to radiation of selected wavelength ranges. The filter layer 5 has here preferably the function of a color filter.

[0213] Such a technical design is particularly suitable for radiation sources 6 in which an LED 7 and a converter element 1 are combined in such a way that the light emitted by the LED 7 is fully converted. With the aid of a suitably designed filter layer 5, the radiation emitted into the radiation area 3 can thus be limited to radiation with a desired wavelength. Likewise, such a filter layer 5 can be used to ensure that excitation radiation emitted by the LED 7, which is not converted into converted radiation by the converter element 1, is prevented from escaping into the radiation area 3 by means of the filter layer 5, if required.

[0214] FIG. 12 again shows a radiation source 6, which has an LED 7 and a converter element 1 applied to a semiconductor substrate 8 of the LED 7. The converter element 1 has a layer 2 with converter material and a structure 4, which is applied to a semiconductor substrate 8 of the LED 7. The structured layer 2 is preferably a photonic crystal, a quasiperiodic or deterministic aperiodic photonic structure. The structure 4 of the layer 2 is filled with suitable converter material.

[0215] In contrast to the embodiment example explained in FIG. 10, however, the patterned layer 2 is not only arranged in a semiconductor substrate in the upper region of the radiation source 6, but extends into the active zone 9 of the LED 7. Again, a patterned layer 2 with a layer thickness greater than 500 nm is provided, thus creating an optical band gap. Also in this case, modes of the excitation radiation emitted by the LED 7, which are guided in the active zone 9 and have a low extraction efficiency from the LED, can be efficiently converted.

[0216] In addition, FIG. 13 shows an embodiment of a radiation source 6 which is designed as shown in FIG. 12 and additionally has a filter element 5 applied to the uppermost layer of the radiation source 6, which is designed in the form of a filter layer serving as a color filter. Such color filters offer the possibilities of limiting the emission of the converted radiation into the radiation area in the case of a full conversion of the excitation radiation emitted by the LED 7, or of selectively suppressing the emission of non-converted excitation radiation in the case of an incomplete conversion.

[0217] FIG. 14 shows an embodiment of a proposed device. According to FIG. 14, a semiconductor body comprising a first material 1 is shown, which can also be referred to as a raw chip and which is formed here as a light-emitting diode.

[0218] A decoupling structure A is formed. A planarized surface 7 is formed on a surface region 9 of the semiconductor body providing the device. The surface area 9 is structured for this purpose and then planarized.

[0219] The semiconductor body can be produced epitaxially in such a way that the surface region 9 was produced facing away from a carrier not shown. In principle, all surface regions of a semiconductor body providing the device can be structured and then planarized for the formation of, in particular, optical outcoupling structures A. Other wavelengths of electromagnetic radiation can also be coupled out if the structuring and planarization are matched to this.

[0220] FIG. 14 shows a patterning of the surface region 9 of the semiconductor body, wherein a random topology is generated at the surface region 9. The random topology is formed here by directly roughening the first material 1 of the semiconductor body on the surface region 9.

[0221] Topology here is in particular a spatial structure.

[0222] Then the surface area 9 of the semiconductor body is planarized by applying a transparent third material 5 with a low refractive index, in particular less than 1.5. This is followed by a thinning of the applied transparent third material 5 with a low refractive index until the surface 7 of the structured surface area 9 is even and/or smooth with the highest elevations in the first material 1 of the semiconductor body. The third material 5 can be applied as a layer.

[0223] Thinning can be done by chemical mechanical polishing (CMP). Possible structures embossed in a surface area 9 can be random topologies, such as roughened surfaces. Random topologies such as roughened surfaces are already used in larger LEDs.

[0224] Light extraction is improved by an extraction structure A with a planarized surface 7. According to FIG. 14, the first material 1 of the LED semiconductor or LED raw chip, for example, is first directly structured.

[0225] The transparent third material 5 with low refractive index used for planarization can be SiO2, and this can be applied in particular using TEOS (tetraethyl orthosilicate).

[0226] The refractive index, also called refractive index or optical density, formerly also refractive index, is an optical material property. It is the ratio of the wavelength of light in a vacuum to the wavelength in the material, and thus of the phase velocity of light in a vacuum to that in the material. The refractive index is dimensionless, and it generally depends on the frequency of the light, which is called dispersion. At the interface of two media of different refractive indices, light is refracted and reflected. In this process, the medium with the larger refractive index is called the optically denser one.

[0227] Small refractive indices can be smaller than 1.5 in particular. Other usable materials with a small refractive index include crown glass with a refractive index of, for example, 1.46, PMMA with a refractive index of, for example, 1.49, and fused silica with a refractive index of, for example, 1.46. These refractive indices are obtained at the 589 nm wavelength of the sodium D-line. A refractive index of silicon dioxide is, for example, 1.458. Other materials can also be used.

[0228] Identical reference signs in all figures indicate identical features.

[0229] FIG. 15 shows a second embodiment of a proposed device.

[0230] To improve light extraction, a transparent second material 3 with a large refractive index can be applied to the light-emitting diode and structured in a suitable manner as an alternative to the embodiment example shown in FIG. 15. A suitable second material 3 with a high refractive index is, for example, Nb2O5. This alternative is shown in FIG. 15 and FIG. 16.

[0231] A large refractive index can in particular be greater than 2. Other usable materials with a large refractive index 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 result, in particular, at the 589 nm wavelength of the sodium D-line. A refractive index of niobium(V) oxide is, for example, 2.3. Other materials can also be used.

[0232] A decoupling structure A is formed in a surface region 9 of a semiconductor body providing the device. Likewise, structuring of the surface region 9 is performed here.

[0233] The structuring of the surface area 9 is carried out, as is also the case in FIG. 14, by generating a random topology on the surface area 9. While according to FIG. 14 the random topology is generated by directly roughening the surface 7 of the surface area 9 of the semiconductor body comprising a first material 1, according to FIG. 15, the random topology is formed by applying, in particular layer by layer, a transparent second material 3 having a large refractive index, in particular greater than 2, to the surface region 9 and by roughening the second material 3.

[0234] This is followed by planarization by applying, in particular in layers, a transparent third material 5 with a low refractive index, in particular less than 1.5, to the structured surface area 9. The third material 5 can be applied as a layer. Afterwards, the attached transparent third material 5 with low refractive index is thinned until the surface 7 of the structured surface area 9 is even and/or smooth with the highest elevations in the second material 3 with high refractive index.

[0235] The transparent third material 5 with low refractive index can be SiO2, and this is applied in particular by means of TEOS (tetraethyl orthosilicate). Thinning can be performed by chemical mechanical polishing (CMP).

[0236] FIG. 16 shows an embodiment of a proposed device.

[0237] Alternatively, for structuring a surface area 9, ordered topologies can likewise be created at the surface area 9.

[0238] The ordered topology is created here by applying, in particular layer by layer, a transparent second material 3 having a large refractive index, in particular greater than 2, to the surface region 9 and structuring periodic photonic crystals or non-periodic photonic structures, in particular quasi-periodic or deterministic aperiodic photonic structures, into the second material 3.

[0239] Alternatively, periodic photonic crystals or non-periodic photonic structures, in particular quasi-periodic or deterministic aperiodic photonic structures, can in principle be patterned directly, without a second material 3, into the first material 1 of the semiconductor body. In this context, a device with an outcoupling structure A can be formed, wherein a transparent third material 5 with a small refractive index, in particular SiO2, has been applied to a first material 1 of a semiconductor of a device and periodic photonic crystals or non-periodic photonic structures, in particular quasi-periodic or deterministic aperiodic photonic structures, can be patterned into the first material 1.

[0240] Photonic crystals consist of structured semiconductors, glasses or polymers and are usually produced by processes known from microelectronics. By means of their specific structure, they force the light to propagate in the medium in the manner required for the component function. This makes it possible not only to guide light to dimensions that are on the order of the wavelength, but also to filter and reflect it in a wavelength-selective manner.

[0241] They are periodic dielectric structures whose period length is tuned to affect the propagation of electromagnetic waves in much the same way that the periodic potential in semiconductor crystals affects the propagation of electrons. They therefore exhibit unique optical properties, such as Bragg reflection of visible light.

[0242] In particular, analogous to the formation of the electronic band structure, a photonic band structure is created which can have regions of forbidden energy in which electromagnetic waves cannot propagate within the crystal (photonic band gaps, PBG). Photonic crystals can therefore be regarded in some ways as the optical analogue of electronic semiconductors, i.e. as “optical semiconductors”.

[0243] After periodic photonic crystals or non-periodic photonic structures, in particular quasi-periodic or deterministic aperiodic photonic structures, have been patterned, a transparent third material 5 with a low refractive index is applied to the patterned surface area 9, in particular in layers, for planarization. Suitable for this purpose is, for example, SiO2, which is deposited with the aid of TEOS (tetraethyl orthosilicate). The third material 5 is then thinned until the surface 7 ends smoothly with the highest elevations in the highly refractive second material 3.

[0244] A process suitable for thinning is chemical mechanical polishing (CMP) to uniformly remove layers with thicknesses in the micrometer and nanometer range. The resulting surface is flat and/or smooth. In particular, a roughness is in the range of a few nanometers as the mean roughness value (rms). The planarized surface 7 produced can be used for transferring the light-emitting diodes using the conventional stamping technique.

[0245] In this way, a decoupling efficiency can be improved compared to an unprocessed surface. A transfer process by means of stamp technology remains possible.

[0246] FIG. 17 shows an embodiment of a proposed method.

[0247] A first step S1 is performed to pattern a surface area 9 of a semiconductor body providing the device to form a decoupling structure A. A second step S2 is performed to planarize the patterned surface area 9 to obtain a planarized surface 7 of the surface area 9. A second step S2 planarizes the patterned surface region 9 to obtain a planarized surface 7 of the surface region 9. The planarizing comprises two substeps.

[0248] By means of a first substep S2.1, a transparent third material 5 with a small refractive index, in particular less than 1.5, is applied to the structured surface area 9, in particular in layers.

[0249] By means of a second sub-step S2.2, the attached transparent third material 5 with a small refractive index is thinned until the surface 7 of the structured surface area 9 is even and/or smooth with the highest elevations in the first material 1 of the semiconductor body or in the second material 3 with a large refractive index.

[0250] With a third step S3, a transfer of the device can be carried out by means of stamp technology, whereby the semiconductor body is lifted off at the planarized surface 7.

[0251] According to all embodiments described below, GaN, AlInGaP, AlN or InGaAs material systems in particular can be used as semiconductor materials.

[0252] FIGS. 18a and 18b show an optoelectronic device for emitting light that preferably emerges vertically from a light-emitting surface 21. The device comprises an array 11 having pixels, wherein optically acting nanostructures in the form of a photonic crystal K are formed over the entire emitting surface of the light emitting surface 21. The array 11 further comprises an array-like arrangement of light sources, each having a recombination zone 2 lying in a recombination plane 1.

[0253] The recombination zones 2 are formed in a first layer of optically active semiconductor material 3 of the array 11. In this layer with the semiconductor material 3, the photonic crystal or photonic crystal structures K are structured, namely in the form of a two-dimensional photonic crystal. In this case, the photonic crystal K is located between the recombination zones 2 and the light emission surface 21. The photonic crystal structures K can be arranged independently of the positioning of individual pixels, whereby in the example shown, one pixel corresponds to a light source with a recombination zone 2.

[0254] The optically acting photonic crystal structures K are free-standing in air or, as shown, filled with a, in particular electrically insulating and optically transparent first filler material 7, in particular SiO2, with a refractive index smaller than the refractive index of the semiconductor material 3. The filler material 7 preferably also has a small absorption coefficient.

[0255] In the array 11, both electrical poles of a respective light source are electrically connected by means of an optically reflective contacting layer 5 for electrical contacting of the light sources. The contacting layer 5 is located on a side of the optically active semiconductor material 3 facing away from the optically acting photonic crystal structures K and is arranged at the bottom as shown in FIG. 1b. Such a contacting enables very strongly localized recombination zones 2. The contacting layer 5 can thereby have at least two electrically separated areas in order to be able to connect the poles electrically separated from each other.

[0256] The photonic crystal K can be structured over the entire emitting surface 21 in such a way that at least approximately only light with a propagation direction perpendicular to the surface 21 can leave the component. If the photonic crystal K is close to the recombination plane 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 is additionally changed.

[0257] Thus, a complete band gap for optical modes with propagation direction parallel and at a small angle to the surface of the, in particular planar, i.e. in particular flat and/or smooth, pixel array 11 can be generated. The emission of light with propagation direction parallel to the emitting surface is then completely suppressed.

[0258] In particular, light generation can take place exclusively in a limited emission cone, which is specified by the photonic crystal K. In this case, directionality is already ensured at the level of light generation, which effectively increases the efficiency compared to an angle-selective optical element, since such an element only influences the light extraction.

[0259] The alignment of the photonic crystal K is independent of the positioning of the individual pixels, in particular in such a way that an alignment of the pixel structure to the photonic structure K is not necessary and a processing of an entire wafer surface is possible.

[0260] Advantageously, the device is homogeneous in its optical properties over the entire surface of the array 11, or varies only slightly so as not to disturb the optical environment of the photonic crystal K.

[0261] FIGS. 19a and 19b show a second proposed optoelectronic device in a top view and in cross section, respectively. In the pixelated array 11, the photonic crystal K is arranged in a second layer of a material 9, in particular Nb2O5, over a first layer of the optically active semiconductor material 3, alternatively to the embodiment example according to FIGS. 18a and 18b. In this case, the material 9 has a large optical refractive index, and it is arranged on the flat and/or smooth surface of the semiconductor material 3. Preferably, the material 9 also has a low absorption.

[0262] The photonic crystal K may again be free-standing as a two-dimensional photonic crystal made of the aforementioned material 9, in which case air is present in the free space. As shown, the free space can again be filled with a material 7 with a smaller refractive index. A possible filling material is for example SiO2.

[0263] The contacting is similar to that shown in FIGS. 18a and 18b and allows for very localized recombination zones 2.

[0264] FIGS. 20a and 20b show a third proposed optoelectronic device in plan view and cross-section, respectively. The device shown includes as light sources an array of vertical light-emitting diodes 13 and a two-dimensional photonic crystal structure K disposed in an overlying layer extending beneath the entire emitting surface 21 and formed of a high refractive index material 9. The free spaces of the structure K is in turn filled with filler material 7 of lower optical refractive index.

[0265] The vertical light emitting diodes 13 have an upper and a lower electrical contact along a vertically oriented longitudinal axis that is perpendicular to the light emitting surface 21. The light-emitting diodes thus have an electrical contact on their front side and an electrical contact on their rear side. Here, the rear side is referred to as the side of the LEDs 13 facing away from the light-emitting surface 21, while the front side faces the light-emitting surface 21.

[0266] The device comprises an electrically conductive and the generated light reflecting contacting layer 5 for electrically contacting the contacts on the rear side of the LEDs 13. For electrically contacting the contacts on the front side of the LEDs 13, a third layer is provided which comprises an electrically conductive and optically transparent material 17, for example ITO. An electrical connection to the corresponding pole of a current source can be established via a bonding wire 19.

[0267] In and along the recombination plane 1, a further, in particular electrically insulating, filler material 15 can be arranged between the third layer and the optically reflective contacting layer 5.

[0268] FIGS. 21a and 21b show a fourth proposed optoelectronic device in plan view and cross-section. The device comprises an array of horizontal light-emitting diodes (LEDs) 13 with respective recombination zones 2 and an optically acting two-dimensional photonic crystal structure K under the entire emitting surface 21. The photonic crystal structure K is located in a layer of a material 9 with a large refractive index, for example Nb2O5. Free spaces are in turn filled with filler material 7, for example silicon dioxide, with lower optical refractive index.

[0269] In the case of the horizontal LEDs 13, both electrical contacts are located on the rear side of the LEDs 13. In each case, both poles of the LEDs 13 are electrically connected by means of electrically separated areas of the optically reflective contacting layer 5.

[0270] In the region of the recombination plane 1, a filler material 15, in particular an electrically insulating one, is arranged between the material layer 9 and the contacting layer 5.

[0271] The efficiency with respect to light generation can be relatively high in the embodiments according to FIGS. 18a to 21b, since in these embodiments directionality or directionality of the light can already be achieved during light generation, in particular if by means of the band structure of the photonic crystal K a higher photonic density of states can be achieved in the region of the recombination zones 2 for the emission of light in the direction perpendicular to the light emission surface. Another advantage may be that the patterning of the photonic crystal K can be homogeneous over an entire wafer. A specific positioning or orientation of the photonic crystal to the individual pixels or light emitting diodes is not required. This can significantly reduce the manufacturing complexity, especially compared to alternative approaches where structures are placed individually over each pixel.

[0272] FIGS. 22a and 22b show a fifth proposed optoelectronic device in a top view and in cross section. The device comprises a pixelated array 11 and optically acting pillar structures P, in particular with pillars or columns patterned over the entire emitting surface 21. The array 11 is preferably smooth and planar.

[0273] The pixelated array 11 comprises pixels each having a light source comprising a respective recombination zone 2. The recombination zones 2 of the pixels are located in a recombination plane 1 and they are arranged in a first layer with optically active semiconductor material 3.

[0274] Pillar structures P are formed above this first layer. A pillar P is thereby associated with a light source, so that each pillar P is arranged directly above the recombination zone 2 of the associated light source. A longitudinal axis L of a respective pillar P runs in particular through the center M of the recombination zone 2 of the associated light source 2.

[0275] The Pillars P consist of a material 9 with a high refractive index, for example Nb2O5. A filler material 7 with a lower refractive index, such as silicon dioxide, can be placed in the spaces between the pillars P.

[0276] The pillars P can be arranged above the layer with the light sources, in particular by additionally applying the pillars P above the array 11. Alternatively, the pillars can be etched into the semiconductor material 3. For this purpose, the semiconductor material layer must have a correspondingly high configuration. Since the semiconductor material normally has a high refractive index, material can be etched away in such a way that the pillars 9 remain. The areas freed up by the etching can be filled with material with a low refractive index.

[0277] The pillars P act as waveguides that direct light upward in the direction of the longitudinal axis L, so that the pillars P can provide enhanced radiation of light in a direction perpendicular to the light emitting surface 21.

[0278] In the array 11, for electrical contacting of the light sources with the recombination zones 2, both electrical poles of a light source are electrically connected in each case by means of a reflective contacting layer 5. The contacting layer 5 is formed on a side of the semiconductor material 3 facing away from the optically acting pillar structures P. The contacting layer 5 can have two separate areas in order to be able to electrically contact the two poles separately. Such a type of contacting enables very strongly localized recombination zones 2.

[0279] FIGS. 23a and 23b show a sixth proposed optoelectronic device in plan view and cross-section. The device comprises an array of vertical light-emitting diodes 13, also referred to as LEDs. Optically acting pillar structures P, in particular with pillars or columns, are arranged above the arrangement with light-emitting diodes 13. Thereby, the longitudinal axis L of the pillars P runs at least substantially through the centers of the recombination zones 2 of the LEDs 13.

[0280] The pillar structures P can be free-standing in air or filled with a first filling material 7, in particular electrically insulating and optically transparent, above the light-emitting diodes. The filling material 7 can have a smaller refractive index than the refractive index of the material 9 of the pillars P and/or the semiconductor material 3 of the LEDs 3.

[0281] As already mentioned, the LEDs are vertical light-emitting diodes 13, which have one, in particular positive, electrical pole on their rear side facing the reflective contacting layer 5 and another electrical pole on the front side facing the pillars P. The LEDs are also vertical light-emitting diodes (LEDs).

[0282] The pole at the front of the light sources is electrically connected to a corresponding power supply (not shown) by means of a layer of an electrically conductive and optically transparent material 17, in particular ITO, and by means of a contact wire 19. The layer with the material 17 is arranged between the light sources and the pillars 17, as shown.

[0283] In this case, a second filler material 15 can be arranged in free spaces in the layer of LEDs 13 and thus between the layer with the material 17 and the contacting layer 5.

[0284] The dimensioning of the pillar structures P can correspond to the dimensioning of the light emitting diodes 13 or the pixels of an array 11.

[0285] FIGS. 24a and 24b show a seventh proposed optoelectronic device in a plan view and in cross section. In contrast to the variant of FIGS. 23a and 23b, the device according to FIGS. 24a and 24b comprises an arrangement of horizontal light-emitting diodes 13 whose electrical poles are located on the rear side of the light-emitting diodes 13. For electrical contacting, both electrical poles of a light source can be electrically connected via two electrically separated areas of the specular contacting layer 5. The intermediate layer with material 17 as in the variant with vertical light-emitting diodes described above is therefore not required.

[0286] Compared to the arrangements with the photonic crystal structures K according to FIGS. 18 to 21, the variants with the pillars P can be manufactured in a simpler way using standard technologies, since the structure sizes are significantly larger with diameters of up to 1 μm or more. The process requirements are thus lower and high-resolution lithography can suffice to manufacture the pillars.

[0287] Pillar structures, in particular pillars or columns, made of the optically active semiconductor material 3 or a material 9 with a refractive index as high as possible can be precisely structured via individual pixels of the array 11 or via vertical light-emitting diodes 13 (FIGS. 23a and 23b) or via horizontal light-emitting diodes 13 (FIGS. 24a and 24b). The individual pixels or light emitting diodes 13 may be smaller than 1 μm in diameter, and the pillars may have an aspect ratio of height:diameter of at least 3:1. The pillars are preferably etched directly into the semiconductor material 3, as possible in FIGS. 22a and b and in FIGS. 24a and b, since no third layer 17 is formed according to FIG. 23b, or they consist of another material 9 with a large refractive index and preferably low absorption, which is applied to the surface of the array 11. For example, a possible material with a large refractive index is Nb2O5. The pillar structures can be free-standing or filled with a material 7 with a small refractive index. A possible filling material with low refractive index is for example SiO2. Due to the larger refractive index of the pillars compared to the surrounding material, the emission parallel to the longitudinal axis of the pillars is enhanced compared to other spatial directions. Due to a waveguide effect, light along the longitudinal axis of the pillars is additionally coupled out more efficiently than light with other propagation directions. This can improve the directionality of the emitted light.

[0288] FIGS. 25a and 25b show an eighth proposed optoelectronic device in plan view and cross section. The device comprises an array of light-emitting diodes 13, each of which is in the form of a pillar P and thus in the form of a column.

[0289] The length of the pillars P may correspond to half a wavelength of the emitted light in the semiconductor material 3 and the recombination zone 2 may preferably be located in the center M of a respective pillar and thus in a local maximum of the photonic density of states. The aspect ratio height:diameter of the pillars P may be at least 3:1.

[0290] In the arrangement shown, the pillars P can be about 100 nm high and have a diameter of only about 30 nm. This requires a very finely resolved structuring technique and can be implemented at wafer level with effort using current manufacturing technologies.

[0291] Alternatively, the dimensions can be scaled up to simplify fabrication, with the directionality of the emitted light decreasing as the size of the pillar patterning increases. The length of the pillars P is preferably a multiple of half the wavelength of the emitted light in the semiconductor material, and the respective recombination zone 2 can be located in a maximum of the photonic density of states.

[0292] Due to the pillar structuring of the light emitting diodes 13, the emission parallel to the longitudinal axis of the pillars P is effectively amplified by the greater photonic density of states. Due to a waveguide effect, light with propagation direction along the longitudinal axis of the pillars P is additionally coupled out more efficiently than light with other propagation directions. The space between the pillars P is filled with a material 7 which preferably has a very small absorption coefficient and a smaller refractive index than the semiconductor material 3. A possible filling material with a small refractive index is for example SiO2.

[0293] In this arrangement of light-emitting diodes 13, which are shaped as pillars P or columns and are in particular vertical, a first pole, in particular a positive pole, is electrically connected in each case by means of a specular contacting layer 5 for contacting recombination zones 2 arranged in a recombination plane 1. The contacting layer 5 is formed at the lower, first longitudinal ends of the light-emitting diodes 13.

[0294] The respective other, in particular negative, second pole is electrically connected to a third layer of a conductive transparent material 17, in particular ITO, and is connected by means of a bonding wire 19, for example, to the corresponding pole of a power supply.

[0295] According to this arrangement, the third layer is formed in and along the recombination plane 1 in the longitudinal centers of the light emitting diodes 13 formed as pillars P or columns.

[0296] FIGS. 26a and 26b show a ninth proposed optoelectronic device in plan view and cross section. In contrast to the variant of FIGS. 25a and 25b, the device according to FIGS. 26a and 26b features vertical LEDs formed as pillars P.

[0297] The electrical contact at the bottom, in particular the p-contact, is made via the underside of the pillars P and in particular by contacting the contacting layer 5.

[0298] The electrical contact on top, in particular the n-contact, is located on the upper side of the Pillars P. The contact is made via an upper layer with optically transparent and electrically conductive material 17. The upper layer extends over the Pillars P and the first filling material 7, with which the free spaces between the Pillars P are filled. A possible material 17 for the upper layer is, for example, ITO (indium tin oxide). A connection to a power supply can be established via the bonding wire 19.

[0299] The electrical contacting of the light emitting diodes in the Pillars P enables very localized recombination zones 2, whereby the upper contact, in particular an n-contact, can be formed at the height of the recombination zones 2 or on the upper side of the Pillars P. Each Pillar P generates an individual pixel.

[0300] The emission of light parallel to the longitudinal axis of the light-emitting diodes 13 in the form of pillars as shown in FIGS. 25a to 26b is increased. This improves the directionality of the emitted light compared to conventional light emitting diodes with a small aspect ratio. Compared to an arrangement according to FIGS. 22a to 24b, the process of light generation can be influenced much more by an arrangement according to FIGS. 25a to 26b, whereby a high directionality and efficiency can be achieved.

[0301] FIG. 27 shows a cross-sectional view of a further optoelectronic device in which a two-dimensional photonic crystal K is arranged above a layer with an array-like arrangement of light sources with recombination zones 2. In this case, the photonic crystal K is arranged close to the recombination zones 2 in such a way that the photonic crystal K changes an optical density of states present in the region of the recombination zones 2, in particular in such a way that a band gap is generated for at least one optical mode with a propagation direction parallel and/or at a small angle to the light emitter surface 21 and/or the density of states is increased for at least one optical mode with a propagation direction perpendicular to the light emitter surface 21.

[0302] This can be achieved in particular by ensuring that the height H of the photonic crystal K is at least 300 to 500 nm, preferably up to 1 μm. The height H of the photonic crystal may depend on the high refractive index material of the photonic crystal.

[0303] Furthermore, preferably a distance A between the center M of the recombination zones 2 and the bottom of the photonic crystal K is at most 1 μm and preferably a few nm.

[0304] In all described embodiments with a photonic crystal K, it is preferably a two-dimensional photonic crystal which comprises a periodic variation of the optical refractive index in two mutually perpendicular spatial directions which are parallel to the light-emitting surface. Furthermore, it is preferably a pillar structure comprising an array-like arrangement of pillars P or columns with the longitudinal axis L of the pillars P being perpendicular to the light emitting surface 21.

[0305] Possible fields of application of devices described herein are, for example, automotive, lighting of any kind, consumer electronics, video walls.

[0306] Features mentioned in connection with one embodiment and/or claim may also be combined with other embodiments and/or claims, even if not mentioned in connection therewith.