WO2023169739A1

WO2023169739A1 - Laser assembly, optoelectronic system and method for producing a laser assembly

Info

Publication number: WO2023169739A1
Application number: PCT/EP2023/052046
Authority: WO
Inventors: Hubert Halbritter; Christoph Eichler; Martin Rudolf Behringer
Original assignee: Ams-Osram International Gmbh
Priority date: 2022-03-10
Filing date: 2023-01-27
Publication date: 2023-09-14
Also published as: DE102022105668A1

Abstract

The invention relates to a laser assembly (10). The laser assembly comprises an electrically contactable first waveguide layer (30), which has a first conductivity type, and a second waveguide layer (40), which has a second conductivity type opposite to the first conductivity type, and an active layer (50) for generating electromagnetic radiation by charge carrier recombination, wherein the active layer is arranged between the first waveguide layer and the second waveguide layer. The laser assembly further comprises zones (60) arranged periodically with respect to one another, which are arranged in the first waveguide layer or in the second waveguide layer, wherein the zones have a refractive index that differs from a refractive index of the waveguide layer embedding the zones and forms a two-dimensional photonic crystal with said waveguide layer. A periodicity of the zone arrangement is interrupted by at least one intermediate region (70) of the waveguide layer embedding the zones. The invention also relates to a method for producing a laser arrangement and to an optoelectronic system (300).

Description

LASER ARRANGEMENT, OPTOELECTRONIC SYSTEM AND METHOD FOR PRODUCING A LASER ARRANGEMENT

Structures that are formed by the periodic modulation of the refractive index of the medium used are called photonic crystals. A surface-emitting photonic crystal laser (Photonic Crystal Surface Emitting Laser, PCSEL ), hereinafter sometimes referred to as laser, laser arrangement or PCSEL, has an active layer that emits electromagnetic radiation when a drive current is applied. Doped layers, in particular waveguide layers, can be arranged on both sides of the active layer, with the photonic crystal being formed in one of these waveguide layers. For example, the photonic crystal is formed into the corresponding waveguide layer by dry etching, so that the resulting trenches or cavities in the waveguide layer form zones whose refractive index differs from the refractive index of the remaining waveguide layer. The structuring of the waveguide layer can cause etching damage, especially crystal damage in the waveguide layer. Since the waveguide layers also serve to transport electrical charge carriers to the active layer, the etching damage can lead to high electrical resistances, which can be accompanied by inhomogeneous current injection and thus a reduction in beam quality.

At least one task of certain embodiments is to provide a laser arrangement with high beam quality. Another task of certain embodiments is to specify an optoelectronic system that has such a laser arrangement. In addition, it is a task of certain embodiments to specify a method for producing such a laser arrangement.

These tasks are solved by subject matter according to the independent patent claims. Advantageous embodiments and further developments of the objects are characterized in the dependent claims and also emerge from the following description and the drawings.

According to at least one embodiment, a laser arrangement has an electrically contactable first waveguide layer which has a first conductivity type.

According to at least one embodiment, the laser arrangement further has a second waveguide layer which has a second conductivity type that is opposite to the first conductivity type.

According to at least one embodiment, the laser arrangement further has an active layer for generating electromagnetic radiation through charge carrier recombination, the active layer being arranged between the first waveguide layer and the second waveguide layer.

Electromagnetic radiation can be referred to below as “radiation” or “light”. Radiation or light can in particular be electromagnetic radiation with a or denote several wavelengths or wavelength ranges. The active layer has a first main surface on which the first waveguide layer is arranged and a second main surface opposite the first main surface and on which the second waveguide layer is arranged. The active layer has a main extension plane that runs in lateral directions. The first and second main surfaces are parallel to the lateral directions. The active layer has a thickness in a transverse direction perpendicular to the lateral directions. The electromagnetic radiation generated by the active layer is guided in the first and second waveguide layers. The first and second waveguide layers form a waveguide in which the active layer is embedded. An optical wave is guided in a lateral direction in the waveguide.

According to at least one embodiment, the active layer forms at least one quantum well, which is intended and designed to emit electromagnetic radiation of a predetermined wavelength when a driver current is applied. For this purpose, the active layer preferably comprises at least one quantum well in the form of a 2D quantum well (quantum well) or ID quantum well (quantum wire) or OD quantum well (quantum dot). English: "quantum dot"). For example, the active layer comprises a plurality of 2D quantum wells arranged one above the other in the transverse direction, each of which is separated by a barrier layer. This can mean that the active layer can comprise a plurality of layers that form at least one quantum well. A 2D quantum well can be formed by a thin intermediate layer of a first material, e.g. B. about 4-5 nm thick, are formed of barrier layers of a second material, e.g. B. about 3-10 nm thick, is surrounded. The barrier layers have a larger band gap than the intermediate layer. This creates a potential gap in the conduction and valence band between the two material groups, with a potential minimum being formed in the intermediate layer. Due to the quantization of the system, charge carriers in the intermediate layer can only assume discrete energy values. In one embodiment, the active layer forms at least one quantum well and at most one hundred quantum wells. The active layer preferably forms between two and ten quantum wells. The active layer can also be referred to as a “multi quantum well”, MQW. One in the growth direction

(transverse direction) first and a last layer of the layer stack formed by the active layer can be intended and designed to enclose charge carriers in the active layer, i.e. H . from leaving the active layer (“confinement”). This means that the first and last layers can be designed as electron barriers with a larger band gap.

The active layer, the first and the second waveguide layers may preferably comprise a semiconductor material. The semiconductor material is, for example, a II IV compound semiconductor material. The semiconductor material is preferably a nitride compound semiconductor material, such as Al _n In]__ _nm Ga _m N, where 0 <n <1, 0 <m <1 and m + n <1. The corresponding semiconducting layer can have dopants and additional components. For example, the first waveguide layer comprises at least one n-GaN layer. For example, the second waveguide layer comprises at least one p-GaN layer. Here “n” and “p” denote the conductivity type of the corresponding layer. The first waveguide layer, the second waveguide layer and the active layer may comprise or consist of multiple layers. Materials such as InGaN (with sometimes different In contents) or GaN are preferably used near the active layer. On the side facing away from the active layer, the waveguide layers can comprise cladding layers. The cladding layers can have or consist of one or more AlGaN layers.

According to at least one embodiment, the laser arrangement further has zones which are arranged periodically relative to one another and which are arranged in the first waveguide layer or in the second waveguide layer. The zones have a refractive index that differs from a refractive index of the waveguide layer embedding the zones. The zones form a two-dimensional photonic crystal with this waveguide layer. The photonic crystal is designed to influence the electromagnetic radiation generated by the active layer.

In particular, the photonic crystal scatters the radiation in the transverse direction.

The zones can contain a gas, e.g. B. Air, or a material, e.g. B. an oxide. In particular, the zones can be defined by recesses in the respective waveguide layer, the recesses being formed into the waveguide layer by etching. In other words, the zones can be etching trenches in the waveguide layer, whereby the trenches can be filled with a material. In particular, the zones can have a significantly lower refractive index than the corresponding material used for the waveguide layer. The zones are related to each other arranged regularly. This can mean that the zones are arranged in a matrix or - in a top view - are located at intersections of a grid. This can be an oblique, rectangular, centered rectangular, hexagonal or square grid. A grating period can be chosen to substantially coincide with a wavelength of the radiation generated by the active layer, or with a fraction, e.g. B. 1/4 or 1/2, this wavelength, or a multiple of this wavelength essentially matches. In this way, the Bragg condition is satisfied to achieve 2D feedback in the plane of the photonic crystal and light emission perpendicular to it. The grating period is defined by the periodically arranged zones. In the waveguide layer embedding the zones, the wavelength of the electromagnetic radiation depends on an effective refractive index, where

■10 ^— bg • n _e ff applies, with the vacuum wavelength X _o , the wavelength in the second waveguide layer X _G and the effective refractive index n _e ff . The effective refractive index of the waveguide layer is based on the refractive indices of the waveguide layer itself and the zones, and on their proportions in the waveguide layer. This means that the choice of a diameter of the zones influences the wavelength in the waveguide layer. The ratio between the diameter of the zones and the grating period can be chosen to be as small as possible in order to improve the quality factor (Q factor) of the emission. A high Q-factor reduces the laser's lasing threshold and results in low-attenuation wavelength mode resonance. On the other hand, a larger diameter of the zones improves the refractive index contrast of the photonic crystal. Electromagnetic radiation moving through the photonic crystal is reflected at the interfaces of the zones, i.e. H . generally due to irregularities, scattered. Scattered waves of electromagnetic radiation can interfere constructively or destructively with each other and with the original wave. Since these irregularities, i.e. H . the zones, being periodically distributed, can potentially achieve complete destructive interference or the formation of coherent radiation. Depending on its frequency and the lattice periodicity of the photonic crystal, electromagnetic radiation can only propagate in certain directions of the lattice and is reflected when it is directed in so-called forbidden directions. This can lead to the formation of a standing wave, whereby the radiation is repeatedly scattered at various non-uniformities and constructively interferes with itself. The standing wave is formed by multiple Bragg diffractions.

Photonic crystals, in particular two-dimensional photonic crystals, can be advantageously used in laser arrangements, whereby a so-called surface-emitting photonic crystal laser, PCSEL, can be formed. Stimulated light emission is achieved by coupling the modes of the photonic crystal with the active layer of the laser. This leads to the feedback effect described above within the crystal plane. Through first-order Bragg diffraction, coherent radiation is also emitted perpendicular to the crystal surface. It is also possible for coherent radiation to be emitted at an angle other than 90° to the crystal surface. The emitted radiation can be characterized primarily by its monomode, its narrow radiation profile and They are characterized by their high output power over a large radiation area.

According to at least one embodiment of the laser arrangement, a periodicity of the zone arrangement is interrupted by at least one intermediate region of the waveguide layer embedding the zones. The laser arrangement has at least one intermediate region in the respective waveguide layer, but it can also include a large number of intermediate regions. No zones are arranged in the at least one intermediate area, i.e. H . it is free of zones. This can mean that no trench etching has been carried out in the intermediate area. In lateral directions, the at least one intermediate region can preferably be wider than a distance between two adjacent zones within the periodic zone arrangement. In other words, the arrangement of the zones is exposed in the intermediate region of the waveguide layer embedding the zones, so that at least this intermediate region has an intact crystal structure. The electrical conductivity of the respective waveguide layer can thus be improved. The intermediate region only slightly influences the optical properties of the photonic crystal. The intermediate region can therefore serve as a defect-free driver current supply line to the active layer. In other words, the at least one intermediate region forms an island within the phonic crystal structure, via which the driver current can be routed to the active layer without loss.

The laser arrangement is therefore characterized in particular by the fact that the structuring of the photonic crystal is suspended at suitable locations in order to enable defect-free power supply lines. In this way the Current injection can be carried out much more homogeneously and the beam quality can therefore be improved.

According to at least one embodiment, a laser arrangement has the following features: an electrically contactable first waveguide layer which has a first conductivity type, a second waveguide layer which has a second conductivity type which is opposite to the first conductivity type, an active layer for generating electromagnetic radiation by charge carrier recombination, the active layer being arranged between the first waveguide layer and the second waveguide layer, and zones arranged periodically to one another, which are arranged in the first waveguide layer or in the second waveguide layer, the zones having a refractive index which is from a refractive index of the waveguide layer embedding the zones and form a two-dimensional photonic crystal with this waveguide layer. A periodicity of the zone arrangement is interrupted by at least one intermediate region of the waveguide layer embedding the zones.

According to at least one embodiment, in the lateral direction, the at least one intermediate region is wider than a distance between two adjacent zones within the periodic zone arrangement. This can mean that the intermediate region is wider than a lattice period of the photonic crystal outside the intermediate region. For example, the intermediate region is at least 1.1 times or at least 1.5 times or at least 2.0 times as wide as the distance between two adjacent zones within the periodic zone arrangement. When etching into the respective waveguide layer in which the zones are defined, an area around the etching may possibly be damaged by the crystal. For example, it may be that areas of the waveguide layer that are up to 50 nm away from the etching trench in the transverse direction and/or lateral directions suffer crystal damage as a result of the etching. As mentioned above, such crystal damage leads to impaired electrical conductivity. Since the zones in a photonic crystal can be arranged close to one another, in particular closer than 10 Onm apart, a drive current can only reach the active layer to a limited extent via the corresponding waveguide layer. With the help of the at least one intermediate region, which has a defect-free crystal structure due to the increased width, a homogeneous current injection to the active layer can be achieved.

According to at least one embodiment, the zones are defined by trenches or cavities in the waveguide layer embedding the zones. If the zones are defined by trenches, these trenches extend from a surface of the respective waveguide layer facing away from the active layer into this waveguide layer. According to one embodiment, the diameter of the trenches is in the nanometer range. For example, the trenches have a diameter of at least 5 nm and at most 1000 nm. The trenches preferably have a diameter of at least 10 nm and at most 50 nm. The trenches can also be referred to as holes or nano-holes, and vice versa. The shape of the trenches can be cylindrical, i.e. H . When viewed from above, the trenches can have a circular or elliptical profile. But it is also possible that the Trenches have a different profile, for example a polygonal, in particular triangular or square, profile. It may also be the case that at least two trenches have different profiles. The profile of the trenches affects a mode profile of the photonic crystal. For example, certain symmetries can lead to so-called leaky modes or non-leaky modes and thus influence the radiation efficiency of the laser arrangement. In the transverse direction, the trenches end in the respective waveguide layer. This means that there is a trench foot in the waveguide layer and the trench foot is spaced from the active layer. The trenches can be of different depths. In the transverse direction (ie in the growth direction), a depth of the trenches can correspond to 10-90%, 50-90% or 70-90% of the thickness of the corrugated layer, for example corresponding to 80% of the thickness of the corrugated layer. In other words, the trenches can penetrate the waveguide layer up to 90%. This can mean in particular that an overlap of the optical wave with the trenches can be large. The trenches allow a photonic crystal to be formed efficiently. In particular, no overgrowth is necessary. If the zones are formed by cavities in the respective waveguide layer, they are completely embedded in this waveguide layer. This can mean in particular that the zones do not extend to the surface of the waveguide layer, but rather are covered by this. Such an arrangement can be produced, for example, using the regrowth process. Here, after the trenches have been etched, they are covered and closed by a subsequent epitaxy process. According to at least one embodiment, the first electrical conductivity type is the n-type. This means that the second electrical conductivity type is the p-type. However, the assignment of the leadership ability types can also be reversed.

According to at least one embodiment, the zones are arranged in the first waveguide layer.

According to at least one embodiment, the zones are arranged in the second waveguide layer. Etching n-GaN layers can produce many defects, which is why the realization of the zones in the p-doped waveguide layer may be preferred.

According to at least one embodiment, the laser arrangement further has an accumulation layer which is arranged between the active layer and the second waveguide layer. According to one

In an embodiment, the accumulation layer is designed so that it provides an accumulation of electrically positive charge carriers in lateral directions. The accumulation layer can be formed by a heterojunction. This can mean that between the active layer, which can contain one or more quantum wells, and the second waveguide layer, there is a heterojunction from a layer with a high band gap (e.g. AlGaN) to a layer with a low band gap (e.g. GaN or InGaN) is arranged. Due to piezo fields, a collection of holes or a "hole gas" forms at this junction, which can contribute to a current expansion thanks to a higher lateral mobility of the charge carriers. The heterojunction can, for example, with the growth of an electron barrier at the active Layer can be connected. The electron barrier can be part of the active layer or alternatively part of the accumulation layer. As explained above, the electron barrier is intended to reduce the overflow of electrons from the active layer. The electron barrier can prevent electrons from overflowing on the side facing the active layer and can provide the required heterojunction on the side facing away from the active layer.

According to at least one embodiment, the laser arrangement further has a first contact layer which is arranged on the side of the first waveguide layer facing away from the active layer. The first contact layer is intended to provide electrical contact to the first waveguide layer.

According to at least one embodiment, the laser arrangement further has a second contact layer which is arranged on the side of the second waveguide layer facing away from the active layer. The second contact layer is intended to provide electrical contact to the second waveguide layer.

The first and second contact layers can have a highly doped semiconductor material (e.g. GaN) and/or a metal. The first and second contact layers preferably comprise or consist of a metal, such as Ag, Pt, Au, Pd, Ti. The first and second contact layers can also be designed as a reflective layer, especially if they comprise a metal. A drive current can be introduced into the laser arrangement via the first and second contact layers, the drive current is transported to the active layer via the respective waveguide layers.

According to at least one embodiment, the first contact layer forms an aperture which is intended to couple electromagnetic radiation from the laser arrangement. In this case, the second contact layer can be applied over the entire surface on or above the second waveguide layer. Furthermore, in this case the laser arrangement can be used as a so-called. “Bottom emitter”. Starting from the active layer, electromagnetic radiation can leave the laser arrangement via the aperture on the first waveguide layer.

According to at least one embodiment, the second contact layer forms an aperture which is intended to couple electromagnetic radiation from the laser arrangement. In this case, the first contact layer can be applied over the entire surface on or above the first waveguide layer. Furthermore, in this case the laser arrangement can be used as a so-called. “Top emitter”. Starting from the active layer, electromagnetic radiation can leave the laser arrangement via the aperture on the second waveguide layer.

According to at least one embodiment, the laser arrangement further has a dielectric layer arranged between the second contact layer and the second waveguide layer. The dielectric layer has a high electrical resistance, so that direct electrical contact between the second waveguide layer and the second contact layer is reduced in areas in which the dielectric layer is arranged. The dielectric layer is preferably arranged in edge regions of the laser arrangement. This means that the drive current is only transported to the active layer via a central area of the laser arrangement. This allows the homogeneity of the current density to be increased.

Alternatively or in addition to the dielectric layer, the laser arrangement further has a crystal-damaged layer arranged between the second contact layer and the second waveguide layer. Similar to the dielectric layer, a crystal damaged layer has increased electrical resistance. In this way, a current flow in edge regions of the laser arrangement can also be reduced and a current flow in central regions of the laser arrangement can be increased by means of a crystal-damaged layer, so that the homogeneity of the current density is improved. The crystal damaged layer can be a surface layer of the second waveguide layer, which is z. B. was treated using reactive ion etching to locally damage the crystal structure.

According to at least one embodiment, the laser arrangement further has a current distribution layer which is arranged on the second waveguide layer. The current distribution layer is intended to distribute a drive current in lateral directions. For example, the current distribution layer includes or consists of a transparently conductive oxide, TCO for short, such as indium tin oxide, ITO for short. The charge carrier mobility, in particular that of the holes, can be limited in the second waveguide layer (for example p-GaN) and can be improved with the help of the current distribution layer. The power distribution layer can be seen on a top view be arranged in the central region of the second waveguide layer. Furthermore, the current distribution layer can be in direct contact with the second contact layer. In this way, the second waveguide layer can be electrically connected to the second contact layer via the current distribution layer.

According to at least one embodiment, the current distribution layer comprises or consists of a tunnel contact layer. The tunnel contact layer may comprise a layer stack of a thin layer of the first conductivity type (e.g. n-type) and a thin layer of the second conductivity type (e.g. p-type), the latter being between the second waveguide layer and the layer of the first conductivity type is arranged. In this way, the tunnel contact layer forms a tunnel diode. The tunnel contact layer also makes it possible to distribute a drive current in lateral directions.

According to at least one embodiment, the laser arrangement further has a third waveguide layer. The third waveguide layer is arranged on the tunnel contact layer. According to at least one embodiment, the third waveguide layer has the first conductivity type. The above-mentioned thin layer of the first conductivity type therefore faces the third waveguide layer. For example, the third waveguide layer comprises n-GaN. In this exemplary embodiment of the laser arrangement, the second waveguide layer can be electrically contacted via the tunnel contact layer and the third waveguide layer. According to at least one embodiment, the laser arrangement further has a further current distribution layer which is arranged on the third waveguide layer and is intended to distribute the drive current in lateral directions. For example, the further current distribution layer comprises or consists of a transparently conductive oxide, TCO for short, such as indium tin oxide, ITO for short. The further current distribution layer can be arranged on a central region of the third waveguide layer when viewed from above. Furthermore, the further current distribution layer can be in direct contact with the second contact layer. In this way, the second waveguide layer can be electrically connected to the second contact layer via the further current distribution layer and the third waveguide layer and the tunnel contact layer.

According to at least one embodiment, the laser arrangement further has a mirror layer which is arranged on the side of the second waveguide layer facing away from the active layer. In this embodiment, electromagnetic radiation is coupled out via a surface of the first waveguide layer facing away from the active layer, preferably via the aperture defined by the first contact layer. The mirror layer can be designed as a Bragg mirror (English: "distributed Bragg reflector", DBR). The mirror layer can comprise a layer stack of alternating thin layers of different refractive indices. The layers comprised by the mirror layer can be grown epitaxially (so-called "epi- DBR"). Alternatively or additionally, the mirror layer can comprise or consist of dielectric and/or metallic layers. The mirror layer reflects light scattered by the photonic crystal so that it is emitted primarily through the aperture.

According to at least one embodiment, the laser arrangement further has a mirror layer which is arranged on the side of the first waveguide layer facing away from the active layer. In this embodiment, electromagnetic radiation is coupled out via a surface of the second waveguide layer facing away from the active layer, preferably via the aperture defined by the second contact layer. In this case, the mirror layer can be designed as an epi-DBR.

According to at least one embodiment, the laser arrangement further has a large number of intermediate regions of the waveguide layer embedding the zones. As explained above, the intermediate regions enable a homogeneous current injection due to defect-free crystal regions with low electrical resistance.

According to at least one embodiment, the intermediate regions are regularly distributed in lateral directions. For example, the photonic crystal formed by the zones can be interrupted by intermediate regions at distances of X pm, where X can be, for example, 5 or 10 or 15. It is also possible that the photonic crystal formed by the zones is interrupted by intermediate regions every N zones, for example after 40 zones. Superlattice effects can be amplified in this way, which means that certain modes can be excited. Alternatively, the intermediate areas are randomly distributed in lateral directions. In this way, distances between the intermediate areas are not necessarily identical across the Radiation area distributed, which means that superlattice effects can be specifically suppressed. It is also possible for the intermediate regions to be distributed in a decreasing manner radially outwards in lateral directions. As a result, the current impression can be improved, especially in a central radiation area, in order to obtain a more homogeneous current density.

According to at least one embodiment, in a top view, the aperture is circular.

According to at least one embodiment, the contact layer forming the aperture comprises at least one web which extends radially from an edge of the aperture towards the center of the aperture. With the help of the bridge, the power supply via central areas of the laser arrangement can be improved. The bridge can also be mirrored in order to reflect radiation blocked by the bridge back into the laser arrangement.

According to at least one embodiment, the at least one web is arranged such that it lies in a node region of an electromagnetic wave emitted during operation of the laser arrangement. In this way, it is possible for the web to shade parts of the emitted wave, so that in the case of non-fundamental mode emission, the interference pattern in the far field becomes as narrow as possible, for example. Alternatively or additionally, the at least one web is arranged such that it is aligned with the at least one intermediate region of the waveguide layer embedding the zones. This can mean that the bridge at least partially covers the intermediate area in a top view. The influence of the intermediate region on the radiated mode profile can thus be reduced. According to at least one embodiment, an optoelectronic system is specified. The optoelectronic system has a laser arrangement according to one of the embodiments stated above. This means that all features disclosed for the laser arrangement are also disclosed for the optoelectronic system and vice versa. The laser arrangement can be integrated into the optoelectronic system. For example, the optoelectronic system is a LIDAR system or a headlight system. However, the optoelectronic system can also include other systems for which a high output power, monomode and/or a narrow radiation profile of the laser beam are desirable. Surface emission can also be used to make integration of the laser arrangement into the optoelectronic system more efficient compared to edge-emitting lasers.

According to at least one embodiment, a method for producing a laser arrangement is specified. All features disclosed for the laser arrangement are also disclosed for manufacturing processes and vice versa.

According to at least one embodiment, the method includes providing a substrate having a main surface. The substrate can have the same material system as the waveguide layers and the active layer. For example, the substrate has or consists of GaN. The substrate can serve as a starting material for the subsequent epitaxial deposits of the waveguide layers and the active layer. The substrate can be removed again after the waveguide layers and the active layer have been produced. Alternatively the substrate serves as a cladding layer of the waveguide formed by the waveguide layers.

According to at least one embodiment, the method further comprises arranging a first waveguide layer on the main surface of the substrate, the first waveguide layer having a first conductivity type. The first waveguide layer can be formed on the substrate by epitaxial deposition.

According to at least one embodiment, the method further comprises arranging an active layer on the first waveguide layer, wherein the active layer is designed to generate electromagnetic radiation through charge carrier recombination. The active layer can be formed by epitaxial deposition on the first waveguide layer.

According to at least one embodiment, the method further comprises arranging a second waveguide layer on a side of the active layer facing away from the first waveguide layer, wherein the second waveguide layer has a second conductivity type that is opposite to the first conductivity type. The second waveguide layer can be formed on the active layer by epitaxial deposition.

In particular, the active layer, the first and the second waveguide layers can be grown in a continuous epitaxy process. The continuous epitaxy process can increase material quality by reducing the possibility of contamination with foreign atoms and crystal defects. According to at least one embodiment, the method further comprises forming zones arranged periodically with respect to one another in the first waveguide layer or in the second waveguide layer. The zones have a refractive index that differs from a refractive index of the waveguide layer embedding the zones. The zones form a two-dimensional photonic crystal with this waveguide layer. The zones can be formed by trenches that are formed into the respective waveguide layer using electron beam lithography, nanoimprint lithography, UV/DUV/EUV lithography and/or dry etching. The trenches can optionally be filled with a material, such as an oxide, using a deposition process.

According to at least one embodiment, a periodicity of the zone arrangement is interrupted by at least one intermediate region of the waveguide layer embedding the zones. This can mean that no zones are formed in the intermediate areas, i.e. H . no trench etching takes place. The intermediate areas therefore have an intact crystal structure. The laser arrangement is therefore characterized in particular by the fact that the structuring of the photonic crystal is suspended at suitable locations in order to enable defect-free power supply lines. In this way, the current injection can be carried out much more homogeneously and the beam quality can therefore be improved.

According to at least one embodiment, a method for producing a laser arrangement comprises the following process steps: providing a substrate having a main surface, arranging a first waveguide layer on the main surface of the substrate, the first waveguide layer having a first conductivity type having, arranging an active layer on the first waveguide layer, wherein the active layer is designed to generate electromagnetic radiation by charge carrier recombination, arranging a second waveguide layer on a side of the active layer facing away from the first waveguide layer, wherein the second waveguide layer has a second, the first Conductivity type has opposite conductivity type, forms of zones arranged periodically to one another in the first waveguide layer or in the second waveguide layer, the zones having a refractive index that differs from a refractive index of the waveguide layer embedding the zones and with this waveguide layer a two-dimensional photonic Form a crystal, and wherein a periodicity of the zone arrangement is interrupted by at least an intermediate region of the waveguide layer embedding the zones.

According to at least one embodiment, the method further comprises arranging a release layer on the main surface of the substrate, wherein the first waveguide layer is arranged on a side of the release layer facing away from the substrate. The release layer is applied to the substrate before the first waveguide layer is formed. The substrate can be removed in a later process step using the release layer.

According to at least one embodiment, the method further comprises arranging a carrier on a side of the second waveguide layer facing away from the active layer. The carrier can comprise another semiconductor substrate or a printed circuit board. The carrier serves, among other things, to: Rotate the layer structure in order to treat it from the other side using backside processing.

According to at least one embodiment, the method further comprises detaching the substrate along the release layer. This is preferably done after turning the layer structure onto the carrier. The release layer is designed to be removed by an etching process, whereby the substrate detaches from the remaining layer structure. This makes it possible to expose the first waveguide layer.

According to at least one embodiment, the zones are formed by dry etching trenches or cavities into the first waveguide layer or the second waveguide layer is formed.

According to at least one embodiment, the method includes wet chemical etching, which is intended to reduce etching damage caused by the dry etching in the waveguide layer around the zones that embeds the zones.

Alternatively or additionally, the method includes annealing, which is intended to reduce etching damage caused by the dry etching in the waveguide layer around the zones that embeds the zones. By reducing the etching damage, the electrical conductivity of the respective waveguide layer into which the etching trenches were introduced can be increased in order to achieve a more homogeneous current density of the driver current.

Further embodiments of the manufacturing process can be found for the experienced reader from those described above

Embodiments for the laser arrangement. The previous and The following description refers equally to the laser arrangement, the optoelectronic system and the production of the laser arrangement.

Further advantages, advantageous embodiments and further developments result from the exemplary embodiments described below in connection with the figures.

In the exemplary embodiments and figures, identical, similar or identically acting elements can each be provided with the same reference symbols. The elements shown and their size ratios to one another are not to be viewed as true to scale; rather, individual elements, such as layers, components, components and areas, may be shown exaggeratedly large for better display and/or understanding.

Figures 1 to 2 show laser arrangements in cross section according to exemplary embodiments.

Figure 3 shows a schematic representation of a band structure.

Figures 4 to 20 show laser arrangements in cross section according to further exemplary embodiments.

Figures 21 to 24 show laser arrangements in plan view according to further exemplary embodiments.

Figure 25 shows an exemplary interference pattern of a radiated electromagnetic wave in the far field. Figure 26 shows a top view of a laser arrangement according to a further exemplary embodiment.

Figure 27 shows a schematic representation of an optoelectronic system according to an exemplary embodiment.

A laser arrangement 10 is shown in connection with FIG. 1. In particular, the laser arrangement forms a so-called surface-emitting photonic crystal laser, PCSEL. In the following, the laser arrangement 10 can therefore also be called a laser or PCSEL. The laser arrangement 10 may comprise a semiconductor material.

The laser arrangement 10 has an active layer 50 which is designed to generate electromagnetic radiation through charge carrier recombination. The active layer 50 may comprise a semiconductor material. The active layer 50 has a first main surface and a second main surface opposite the first main surface. The active layer 50 has a main extension plane that runs in lateral directions x, y. The active layer 50 has a thickness in a transverse direction z, which is perpendicular to the main extension plane. The first main surface and second main surface run parallel to the lateral directions x, y. The active layer 50 may be formed by a plurality of layers (not shown). In particular, the active layer 50 can form at least one quantum well, which is intended and designed to emit electromagnetic radiation of a predetermined wavelength when a drive current is applied. For example, the at least one quantum well is a 2D quantum well, which is formed by a thin intermediate layer first material is formed surrounded by barrier layers of a second material. The barrier layers have a larger band gap than the intermediate layer.

The active layer 50 is arranged between a first waveguide layer 30 and a second waveguide layer 40 . This can mean that the active layer 50 is in direct contact with the waveguide layers 30, 40. The first waveguide layer 30 is arranged on or on the first main surface of the active layer 50. The second waveguide layer 40 is arranged on or on the second main surface of the active layer 50. It is also possible that there are intermediate layers between the active layer 50 and the respective waveguide layers 30, 40 (not shown in FIG. 1). The first waveguide layer 30 can be electrically contacted and has a first conductivity type. For example, the first conductivity type is n-type. The first waveguide layer 30 can therefore be doped with an n-type dopant (e.g. silicon (Si)). The second waveguide layer 40 can also be electrically contacted and has a second conductivity type. The second conductivity type is opposite to the first conductivity type. For example, the second is

Conductivity type the p-type. The second waveguide layer 40 can therefore be doped with a p-type dopant (e.g. magnesium (Mg)).

The laser arrangement 10 also has zones 60 which are arranged periodically relative to one another and which are arranged in the first waveguide layer 30 or in the second waveguide layer 40 . In the example shown in Figure 1, the zones 60 are in the second Waveguide layer 40 arranged. The zones 60 have a refractive index that differs from a refractive index of the waveguide layer 30 , 40 embedding the zones 60 . The zones 60 thus form a two-dimensional photonic crystal with this waveguide layer 30, 40. As shown, the zones 60 can be defined, for example, by recesses in the corresponding waveguide layer 30, 40. In the example shown, the zones 60 are formed by trenches which extend from a surface of the second waveguide layer 40 facing away from the active layer 50 into the second waveguide layer 40 . The zones 60 may therefore comprise air or gas as a material, as shown. But it is also possible for the zones 60 to comprise a different material, e.g. B. an oxide. For example, the trenches can be filled with the other material. The zones 60 may have been subsequently introduced into the second waveguide layer 40. This can mean that the second waveguide layer 40 is initially formed as a continuous layer comprising a semiconductor material. The zones 60 may be formed by material modification, material removal or material replacement in the second waveguide layer 40. A refractive index difference between the zones 60 and the corresponding waveguide layer 30, 40 (here the second waveguide layer 40) can be large.

The zones 60 can be arranged in a matrix or - in a top view (see for example FIG. 21) - located at intersections of a grid. The grid can consist of a base with several elements. A grating period can be chosen to substantially match a wavelength of the radiation generated by the active layer 50, or a represents an integer or non-integer multiple of it. The zones 60 are spaced from the active layer 50 in the transverse direction z. A distance between the zones 60 and the active layer 50 can be the same for all zones 60 or can vary. That is, a depth of the trenches forming the zones 60 may be different. In a top view (see FIG. 21), the zones 60 may have a circular or elliptical profile. But it is also possible for the zones 60 to have a different profile, e.g. B. have a polygonal, especially triangular or square, profile. It may also be the case that at least two zones 60 have different profiles. The depth of the zones 60 in the transverse direction z and the profile of the zones 60 in the lateral directions x, y affect a mode profile of the photonic crystal.

If the zones 60 are subsequently introduced into the second waveguide layer 40 by forming trenches, this can be accomplished, for example, by an etching process. The trenches can be formed using electron beam lithography, nanoimprint lithography, UV/DUV/EUV lithography and/or dry etching. The etching process can damage the waveguide layer 40, in particular crystal defects can occur around the etching. Such crystal defects are shown in Fig. 1 using a dot pattern around the zones 60. The crystal defects can deteriorate the electrical conductivity of the second waveguide layer 40 at least in the damaged areas. According to one exemplary embodiment, the etching damage caused by the dry etching in the waveguide layer 30, 40 embedding the zones 60 around the zones 60 is reduced by wet chemical etching and/or tempering. For example, the damaged ones Areas etched away with potassium hydroxide (KOH) or annealed with high process temperatures. Alternatively, the crystal defects are not eliminated since the laser arrangement 10 has defect-free areas, as will be described below.

The laser arrangement 10 has at least one intermediate region 70 in the second waveguide layer 40 in which no zones 60 are arranged, i.e. H . where no trench etching is carried out. This means that a periodicity of the zone arrangement is interrupted by the at least one intermediate region 70 of the waveguide layer 30 , 40 embedding the zones 60 . In the lateral directions x, y, the intermediate region 70 is arranged next to the zones 60, or is surrounded by zones 60. In other words, the at least one intermediate region 70 forms a defect in the photonic crystal. In lateral directions x, y, the at least one intermediate region 70 is wider than a distance between two adjacent zones 60 within the periodic zone arrangement. In other words, the arrangement of the zones 60 is exposed in the intermediate region 70 of the second waveguide layer 40, so that at least this intermediate region 70 has an intact crystal structure.

The electrical conductivity of the second waveguide layer 40 can thus be improved. The intermediate region 70 only slightly influences the optical properties of the photonic crystal. The intermediate region 70 can therefore serve as a defect-free driver current supply line to the active layer 50.

The laser arrangement 10 according to FIG. 1 also has a substrate

20, which is arranged on the surface of the first waveguide layer 30 facing away from the active layer 50. In other words, the first waveguide layer 30 is arranged between the active layer 50 and the substrate 20. The substrate 20 may be a semiconductor substrate. The substrate 20 can be doped, and in particular have the same conductivity type as the first waveguide layer 30 (the first conductivity type). The substrate 20 can serve as a starting material in a manufacturing process for the laser arrangement 10. This can mean that the substrate 20 is removed again at the end of the manufacturing process. However, it is also possible for the substrate 20 to serve as a cladding layer for the laser arrangement 10 and to form an interface with the first waveguide layer 30. For this purpose, the jacket layer, i.e. H . the substrate 20 has a lower refractive index than the first waveguide layer 30, so that a laterally traveling optical wave is reflected, in particular totally reflected, at the interface between the first waveguide layer 30 and the cladding layer.

As mentioned above, the laser assembly 10 may include a semiconductor material. In particular, the active layer 50, the first and second waveguide layers 30, 40 and the substrate 20 (if present) may comprise an I I I-V compound semiconductor material from the Al InGaN system.

A further exemplary embodiment of the laser arrangement 10 is shown in conjunction with FIG. 2. The exemplary embodiment according to FIG. 2 differs from the exemplary embodiment according to FIG. 1 in that an accumulation layer 80 is arranged between the active layer 50 and the second waveguide layer 40. The accumulation layer 80 is designed to be in lateral directions x, y provides an accumulation of electrically positive charge carriers. The accumulation layer 80 may be formed by a heterojunction. Due to piezo fields, a collection of holes or a "hole gas" forms at this transition, which can contribute to a current expansion thanks to a higher lateral mobility of the charge carriers. The current expansion is shown in Figure 2 by arrows pointing outwards. The current expansion takes place in a transverse manner Direction z below the intermediate region 70.

Figure 3 shows schematically the effect of the accumulation layer 80 using a band diagram. The energy “E” is plotted over the position “pos” along a heterojunction. A valence band VB and a conduction band LB are formed in the semiconductor. At the heterojunction, i.e. H . At the transition from a layer with a high band gap to a layer with a low band gap, potential barriers for electrons or holes.

Figure 3 also shows the quasi-Fermi levels E _F ^e , E _F ^h for electrons and holes. These are shifted by the accumulation layer 80, so that charge carrier accumulations arise in areas where the quasi-Fermi levels E _F ^e , E _F ^h lie outside the band gap. In this way, electrically positive charge carriers (holes) accumulate at the junction, i.e. H . A two-dimensional hole gas is formed.

A further exemplary embodiment of the laser arrangement 10 is shown in conjunction with FIG. 4. According to this exemplary embodiment, the zones 60 are completely embedded in the second waveguide layer 40. This means that the zones 60 do not extend to the surface of the second waveguide layer 40, but from it are enclosed. In this case, the zones 60 can be formed, for example, by cavities or closed areas may be formed in the second waveguide layer 40. Such an arrangement can be produced, for example, using the “regrowth” process. Starting from the exemplary embodiment according to FIG The further waveguide layer 40' also has the second conductivity type. This can mean that the further waveguide layer 40' comprises p-GaN, which is epitaxially deposited onto the structured waveguide layer. A process temperature of the “regrowth” process can be high, but lower than a process temperature when growing the active layer 50.

A further exemplary embodiment of the laser arrangement 10 is shown in conjunction with FIG. 5. Here, the laser arrangement additionally has a current distribution layer 90, which is arranged on the second waveguide layer 40 (or 40 '). In other words, the second waveguide layer 40 is arranged between the current distribution layer 90 and the active layer 50. The current distribution layer 90 is intended to distribute a drive current in lateral directions x, y. The current distribution here takes place in the transverse direction z over the intermediate region 70. The charge carrier mobility, in particular that of the holes, can be limited in the second waveguide layer 40 (for example p-GaN) and improved with the help of the current distribution layer 90 become . For example, the current distribution layer 90 includes or consists of a transparent conductive oxide, TCO for short, such as indium tin oxide, ITO for short.

A further exemplary embodiment of the laser arrangement 10 is shown in conjunction with FIG. 6. The laser arrangement 10 further comprises a first contact layer 100, which is arranged on the side of the first waveguide layer 30 facing away from the active layer 50. In the exemplary embodiment shown, the first contact layer 100 is arranged on the substrate 20, specifically on the side of the substrate 20 facing away from the first waveguide layer 30. The first contact layer 100 covers the entire surface of the substrate 20. The first contact layer 100 is intended to provide electrical contact to the first waveguide layer 30. In particular, a drive current for the active layer 50 is provided via the first contact layer 100 and the first waveguide layer 30.

The laser arrangement 10 further comprises a second contact layer 110, which is arranged on the side of the second waveguide layer 40 facing away from the active layer 50. In the lateral direction x, y, the second contact layer 110 is arranged next to the current distribution layer 90 and surrounds it in the lateral directions x, y. The second contact layer 110 may be in direct contact with the power distribution layer 90. The second contact layer 110 may be in direct contact with the second waveguide layer 40, or alternatively may be spaced from it by a dielectric intermediate layer (not shown). It is also possible that the second contact layer 110 is in direct contact with the second Waveguide layer 40 is an interface but is processed in such a way that direct electrical contact is reduced. For example, the surface of the second waveguide layer 40 is crystal damaged by means of reactive ion etching, so that an electrical resistance is increased. The second contact layer 110 is intended to provide electrical contact to the second waveguide layer 40. Preferably, an electrical connection is provided via the power distribution layer 90. The first and second contact layers 100, 110 may comprise a highly doped semiconductor material and/or a metal. The first and second contact layers 100, 110 preferably comprise or consist of a metal, such as Ag, Pt, Au, Pd, Ti.

The first or second contact layer 100 , 110 forms an aperture 210 which is intended to couple electromagnetic radiation out of the laser arrangement 10 . In the exemplary embodiment according to FIG. 6, the second contact layer forms such an aperture 210. The coupled out electromagnetic radiation is illustrated by an arrow pointing upwards. This means that electromagnetic radiation is coupled out via a surface of the second waveguide layer 40 facing away from the active layer 50 . In this exemplary embodiment, the laser arrangement 10 forms a so-called "top emitter" since it emits electromagnetic radiation in a direction encompassing the growth direction (the transverse direction z). In the exemplary embodiment shown, a mirror layer 120 is on that of the active layer 50 arranged on the opposite side of the first waveguide layer 30. The mirror layer

120 is between the substrate 20 and the first

Waveguide layer 30 arranged. In one During the manufacturing process, the mirror layer 120 can be deposited on the substrate 20 before the first waveguide layer 30. The mirror layer 120 can be designed as a Bragg mirror (distributed Bragg reflector, DBR). The mirror layer 120 can comprise a layer stack of alternating thin layers of different refractive indices. The layers comprised by the mirror layer 120 can be grown epitaxially (so-called "epi-DBR"). The mirror layer 120 reflects light scattered by the photonic crystal to be emitted primarily through the aperture 210 .

A further exemplary embodiment of the laser arrangement 10 is shown in conjunction with FIG. 7. In this exemplary embodiment, the laser arrangement 10 forms a so-called “bottom emitter” because it emits electromagnetic radiation counter to the growth direction (opposite to the transverse direction z). The coupled-out electromagnetic radiation is illustrated by a downward-pointing arrow. This means that electromagnetic Radiation is coupled out via a surface of the first waveguide layer 30 facing away from the active layer 50. In the exemplary embodiment according to FIG. 7, the first contact layer 100 forms the aperture 210. The mirror layer 120 is arranged here on the side of the second waveguide layer 40 facing away from the active layer 50 The mirror layer 120 can be arranged on the current distribution layer 90. The mirror layer 120 can be designed as an epi-DBR. Alternatively or additionally, the mirror layer 120 can comprise or consist of dielectric and/or metallic layers. Parts of the second contact layer 110 can be the mirror layer 120 cover, as in Figure 7 shown. In other words, the mirror layer 120 may be arranged between the current distribution layer 90 and the second contact layer 110. The mirror layer 120 reflects light scattered by the photonic crystal to be emitted primarily through the aperture 210 .

In conjunction with Figure 8 is a further exemplary embodiment of the laser arrangement 10. Similar to the exemplary embodiment according to FIG. 6, the laser arrangement 10 is designed as a top emitter. Instead of the further waveguide layer 40 'formed using the "regrowth" process, the current distribution layer 90 is applied directly to the structured second waveguide layer 40. This can mean that the current distribution layer 90 closes the trenches forming the zones 60 in the second waveguide layer 40 and covers them The current distribution layer 90, which comprises, for example, or consists of ITO, can be deposited using sputtering methods. In contrast to the exemplary embodiment according to FIG. 6, the current distribution layer 90 can have a greater thickness in the transverse direction z.

A further exemplary embodiment of the laser arrangement 10 is shown in conjunction with FIG. 9. Similar to the exemplary embodiment according to FIG. 7, FIG.

Figure 10 shows a further exemplary embodiment of the laser arrangement 10. The current distribution layer 90 here includes or is as such a tunnel contact layer 130 educated . The tunnel contact layer 130 is applied directly to the structured second waveguide layer 40. This can mean that the tunnel contact layer 130 closes the trenches forming the zones 60 in the second waveguide layer 40 and covers them. The tunnel contact layer 130 may comprise a layer stack of a thin layer of the first conductivity type (e.g. n-type) and a thin layer of the second conductivity type (e.g. p-type), the latter between the second waveguide layer 40 and the layer of the first

Conductivity type is arranged. In this way, the tunnel contact layer 130 forms a tunnel diode.

A further exemplary embodiment of a laser arrangement 10 with a tunnel contact layer 130 is shown in FIG. The laser arrangement 10 here further comprises a third waveguide layer 140, which is arranged on the tunnel contact layer 130 and has the first conductivity type. The above-mentioned thin layer of the first conductivity type thus faces the third waveguide layer 140. For example, the third waveguide layer 140 comprises n-GaN. In this example, the zones 60 extend through the third waveguide layer 140 and the tunnel contact layer 130 into the second waveguide layer 40. In other words, the tunnel contact layer 130 is located in the transverse direction z at the same height as the zones 60, which form the photonic crystal. The zones 60 continue to extend into the third waveguide layer 140. This means that the zones 60 are defined by the second waveguide layer 40 , the tunnel contact layer 130 and the third waveguide layer 140 . A further exemplary embodiment of a laser arrangement 10 with a tunnel contact layer 130 is shown in FIG. In this example, the tunnel contact layer 130 is arranged over the zones 60 in the transverse direction z. The zones 60 are, as in Figure 5, completely embedded in the second waveguide layer 40. The tunnel contact layer 130 is arranged on the second waveguide layer 40. The third waveguide layer 140 is arranged on the tunnel contact layer 130 . 10 to 12, the tunnel contact layer 130 can serve as an overgrowth layer of the zones 60, or can be incorporated into the zones 60, or can be arranged above the zones 60 and spaced apart from them.

13 shows a further development of the laser arrangement 10 according to FIG This means that the third waveguide layer 140 is arranged between the tunnel contact layer 130 and the further current distribution layer 160. The further current distribution layer 160 has the same effect as the current distribution layer 90 from Figure 6 and can also comprise or consist of a transparently conductive oxide. Between The substrate 20 and the first waveguide layer 30 in turn have a mirror layer 120. The first contact layer 100 is arranged over the entire surface on the surface of the substrate 20 facing away from the mirror layer 120. The second contact layer 110 is arranged and shaped on or above the third waveguide layer 140 an aperture 210. The second contact layer 110 is intended for this purpose designed to provide an electrical contact via the further current distribution layer 160. A dielectric layer 150 is arranged between the second contact layer 110 and the third waveguide layer 140, which can also be a crystal-damaged surface layer of the third waveguide layer 140. In this way, electrical resistance is increased and the electrical connection is preferably provided via the further current distribution layer 160.

Figure 14 shows the laser arrangement 10 according to Figure 13 as a bottom emitter. All features shown were explained in connection with exemplary embodiments already discussed (see in particular FIG. 7).

Figure 15 shows an intermediate product of the laser arrangement 10 within the manufacturing process. The hatched area may optionally represent the portion 40' of the second waveguide layer 40, the current distribution layer 90, or the third waveguide layer 140 (along with the tunnel contact layer 130), or a combination thereof, as discussed above. Hereafter, this area can also be called the middle class. The mirror layer 120 is arranged on the middle layer. The second contact layer 110 completely covers the mirror layer 120. The mirror layer 120 can be designed as a DBR mirror with dielectric and/or metallic layers. Alternatively, if no current distribution layer 90 made of TCO is used, the mirror layer can also be designed as an epi-DBR. A further mirror layer 120 can optionally be arranged between the first waveguide layer 30 and the substrate 20, but this can also be omitted. On the surface of the substrate 20 facing the first waveguide layer 30 there is a release layer 170 (English: “release layer”) is arranged. The release layer 170 is intended and designed to release the substrate 20 in a subsequent process step. For this purpose, as can be seen in Figure 16, a carrier 180 can be on or above one of the active layer 50 opposite side of the second waveguide layer 40. After attaching the carrier 180, the laser arrangement 10 is rotated onto the carrier 180 in order to detach the substrate 20 along the release layer 170.

FIG. 16 shows the laser arrangement 10 according to FIG. 15 after the substrate 20 has been detached. In this example, the carrier 180 is arranged on the second contact layer 110. After the substrate 20 has been detached together with the release layer 170, an anti-reflective layer 190 can optionally be arranged on the side of the first waveguide layer 30 facing away from the active layer 50, as can be seen in Figure 16. The antireflective layer 190 can be structured. Furthermore, the first contact layer 100 is preferably arranged directly on the first waveguide layer 30 and structured to form an aperture 210. By removing the substrate 20, electrical contact to the first waveguide layer 30 and/or the emission characteristics of a laser arrangement 10 designed as a bottom emitter can be improved.

Figure 17 shows a further exemplary embodiment of the laser arrangement 10 with the substrate 20 detached, the laser arrangement 10 being designed as a top emitter. In this case, the first contact layer 100 can completely cover a mirror layer 120 arranged on the first waveguide layer 30. In this exemplary embodiment, electromagnetic radiation is emitted via the carrier 180, which is located in the middle class. In this case, the second contact layer 110 can be arranged on the carrier 180 and form an aperture 210 and produce an electrical contact. In this case, the carrier is electrically conductive.

Figures 18 and 19 show a possible manufacturing process of the laser arrangement, in which the zones 60 are not realized in the second waveguide layer 40, but in the first waveguide layer 30. In particular, this manufacturing process is combined with the detachment of the substrate 20, as described above, since this allows the first waveguide layer 30 to be exposed (see FIG.

18). After applying the carrier 180 and detaching the substrate 20, the zones 60 arranged periodically to one another are introduced into the exposed first waveguide layer 30, again for example by means of electron beam lithography, nanoembossing lithography, UV/DUV/EUV lithography and/or dry etching ( see figure

19). In this example, the zones 60 have a refractive index that differs from a refractive index of the first waveguide layer 30. The zones 60 thus form a two-dimensional photonic crystal with the first waveguide layer 30. The first waveguide layer 30 includes an intermediate region 70 which interrupts the periodicity of the zone arrangement. A cover layer 200, which covers the zones 60, can be arranged on the first waveguide layer 30 structured in this way. The cover layer 200 can, for example, comprise or consist of a transparently conductive oxide (e.g. indium tin oxide). Furthermore, the cover layer 200 can also be designed as an antireflective coating (ARC). On the cover layer 200, as in Fig. 19, the first contact layer 100 is arranged and defines the aperture 210 through which electromagnetic radiation is emitted.

Figure 20 shows a further development of the laser arrangement 10 according to Figure 19. Here, the layers arranged above the second waveguide layer 40, in particular the carrier 180 and the second contact layer 110, are made wider in the lateral directions x, y, so that in a top view they protrude laterally at least beyond the active layer 50 and the first waveguide layer 30. This serves to contact the second waveguide layer 40 from the same side as the first waveguide layer 30 and thus facilitate the electrical contacting of an overall structure. Between the second contact layer 110 and the second waveguide layer 40 is the middle layer, whereby the middle layer, as explained above, can be the part 40' of the second waveguide layer 40, the current distribution layer 90 or a third waveguide layer 140. The middle layer therefore has electrical conductivity. In a top view, the middle layer also protrudes laterally at least beyond the active layer 50 and the first waveguide layer 30. On the middle layer, on a side of the laterally projecting regions facing the active layer 50, contact surfaces 110' are arranged, via which the second waveguide layer 40 can be contacted.

Figure 21 shows a top view of the aperture 210, which, as indicated, is formed either by the first contact layer 100 or by the second contact layer 110, depending on whether the laser arrangement 10 is used as a top or bottom emitter is trained . The aperture 210 according to FIG. 21 is circular. It can also be seen that the zones 60 are arranged in a grid shape, i.e. H . are located at intersections of a grid. In the exemplary embodiment shown, the laser arrangement 10 has a large number of intermediate regions 70 of the waveguide layer 30 or 40, whereby the intermediate areas 70 are regularly distributed in lateral directions x, y. But it is also possible for the intermediate areas 70 to be randomly distributed in lateral directions x, y. As can be seen in Figure 22, it is also possible for the intermediate regions 70 to extend radially outwards, i.e. H . are distributed decreasingly in the direction of the aperture edge.

As can be seen in Figure 23, the aperture 210 can also be circular, with the contact layer 100 or . 110 comprises at least one web 111 which extends radially from an edge of the aperture 210 towards the center of the aperture 210. The web 111 thus improves the electrical contact, since a driver current can be fed in not only from a peripheral area, but also centrally above the radiation area. In the example shown, the respective contact layer 100, 110 has a large number of webs which extend over the aperture 210 like a cartwheel. The webs can be aligned with the intermediate regions 70 of the waveguide layer 30, 40 embedding the zones 60. This can mean in particular that when viewed from above, the webs 111 at least partially cover the intermediate areas 70. The webs 111 can also be mirrored on a side facing the respective waveguide layer 30, 40 in order to emit light that comes from the Webs 111 are blocked from reflecting back into the waveguide 30, 40 and thus continuing to be usable.

Figure 24 further shows that the webs 111 can only extend over a peripheral region of the aperture 210, and a central region of the aperture 210 is therefore free of webs 111. In this way, a beam intensity of the emitted light in the central area can be increased and at the same time an improved electrical contact can be provided.

Figure 25 shows a possible mode profile of the emitted radiation in the near field of the laser arrangement 10. This is an interference pattern of a radiation emission that is different from the fundamental mode emission. The mode profile includes several nodal regions. As can be seen in FIG. 26, the webs 111 can also be arranged in such a way that they lie in certain node regions of an electromagnetic wave emitted during operation of the laser arrangement 10 (the node regions of the mode profile from FIG. 25 are illustrated by circles in FIG. 26). In this way, it is possible for the webs 111 to shade parts of the emitted wave, so that in the case of non-fundamental mode emission, the interference pattern in the far field becomes as narrow as possible, for example.

As indicated in FIG. 27, the laser arrangement 10 can be integrated in an optoelectronic system 300. The optoelectronic system 100 may be a system in which a VCSEL (vertical cavity surface emitting laser) or an EEL (edge emitting laser) is typically used. The contact layers 100, 110 of the laser arrangement 10 can be made using wire connections or flip-flops. Chip assembly can be connected to a printed circuit board or circuit board of the optoelectronic system 300. The optoelectronic system 300 may include additional optical and/or electronic components, such as optical filters, lenses, photodetectors and/or integrated circuits.

The features and exemplary embodiments described in connection with the figures can be combined with one another according to further exemplary embodiments, even if not all combinations are explicitly described. Furthermore, the exemplary embodiments described in connection with the figures can alternatively or additionally have further features according to the description in the general part.

The invention is not limited to the description based on the exemplary embodiments. Rather, the invention encompasses every new feature and every combination of features, which in particular includes every combination of features in the patent claims, even if this feature or this combination itself is not explicitly stated in the patent claims or exemplary embodiments.

This patent application claims priority over German patent application 102022105668. 6, the disclosure content of which is hereby incorporated by reference. reference character list

10 laser arrangement

20 substrate

30 first waveguide layer

40 second waveguide layer

50 active shift

60 zones

70 intermediate area

80 accumulation layer

90 power distribution layer

100 first contact layer

110 second contact layer

111 jetty

120 mirror layer

130 tunnel contact layer

140 third waveguide layer

150 dielectric layer

160 additional power distribution layer

170 release layer

180 carriers

190 antireflective layer

200 top coat

210 aperture

300 optoelectronic system

LB conduction band

VB valence band

E _F ^e , E _F ^h Quasi-Fermi levels for electrons and holes x, y lateral directions z transverse direction

Claims

Patent claims

1. Laser arrangement (10), comprising:

- an electrically contactable first waveguide layer (30) which has a first conductivity type,

- A second waveguide layer (40) which has a second conductivity type opposite to the first

has conductivity type,

- an active layer (50) for generating electromagnetic radiation through charge carrier recombination, the active layer (50) being arranged between the first waveguide layer (30) and the second waveguide layer (40),

- a first contact layer (100), which is arranged on the side of the first waveguide layer (30) facing away from the active layer (50) and is intended to provide electrical contact to the first waveguide layer (30), and a second contact layer (110), which is arranged on the side of the second waveguide layer (40) facing away from the active layer (50) and is intended to provide electrical contact to the second waveguide layer (40), wherein the first or second contact layer (100, 110) has an aperture (210 ) which is intended to couple out electromagnetic radiation from the laser arrangement (10),

- a dielectric and/or crystal-damaged layer (150) arranged between the second contact layer (110) and the second waveguide layer (40), and

- Zones (60) arranged periodically to one another, which are arranged in the first waveguide layer (30) or in the second waveguide layer (40), the zones (60) having a refractive index that differs from one Refractive index of the waveguide layer (30, 40) embedding the zones (60) and form a two-dimensional photonic crystal with this waveguide layer (30, 40), whereby

- A periodicity of the zone arrangement is interrupted by at least one intermediate region (70) of the waveguide layer (30, 40) embedding the zones (60).

2. Laser arrangement (10) according to claim 1, wherein in lateral

Direction (x, y) of the at least one intermediate region (70) is wider than a distance between two adjacent zones

(60) within the periodic zone arrangement.

3. Laser arrangement (10) according to one of claims 1 to 2, wherein the zones (60) are defined by trenches or cavities in the waveguide layer (30, 40) embedding the zones (60).

4. Laser arrangement (10) according to one of claims 1 to 3, wherein the first electrical conductivity type is n-type, and the zones (60) are arranged in the first waveguide layer (30).

5. Laser arrangement (10) according to one of claims 1 to 3, wherein the second electrical conductivity type is p-type, and the zones (60) are arranged in the second waveguide layer (40).

6. Laser arrangement (10) according to one of claims 1 to 5, further comprising an accumulation layer (80) which is arranged between the active layer (50) and the second waveguide layer (40) and is designed to be in lateral Directions (x, y) an accumulation of electrically positive

Provides load carriers.

7. Laser arrangement (10) according to one of claims 1 to 6, further comprising a current distribution layer (90) which is arranged on the second waveguide layer (40) and is intended to distribute a drive current in lateral directions (x, y).

8. Laser arrangement (10) according to claim 7, wherein the current distribution layer comprises a tunnel contact layer (130), and the laser arrangement (10) further comprises a third waveguide layer (140) arranged on the tunnel contact layer (130) and the first conductivity type having.

9. Laser arrangement (10) according to claim 8, further comprising a further current distribution layer (160) which is arranged on the third waveguide layer (140) and is intended to distribute the drive current in lateral directions (x, y).

10. Laser arrangement (10) according to one of claims 1 to 9, further comprising a mirror layer (120), which

- is arranged on the side of the second waveguide layer (40) facing away from the active layer (50), electromagnetic radiation being coupled out via a surface of the first waveguide layer (30) facing away from the active layer (50), or

- Is arranged on the side of the first waveguide layer (30) facing away from the active layer (50), electromagnetic radiation being transmitted via one of the active layers (50) facing away from the surface of the second waveguide layer (40) is coupled out.

11. Laser arrangement (10) according to one of claims 1 to 10, further comprising a plurality of intermediate regions (70) of the waveguide layer (30, 40) embedding the zones (60), wherein in lateral directions (x, y) the intermediate regions (70 ) are regularly distributed, or are randomly distributed, or are distributed decreasing radially outwards.

12. Laser arrangement (10) according to one of claims 1 to 11, wherein, in a top view, the aperture (210) is circular and the contact layer (100, 110) forming the aperture (210) comprises at least one web (111), which extends radially from an edge of the aperture (210) towards the center of the aperture (210).

13. Laser arrangement (10) according to claim 12, wherein the at least one web (111) is arranged so that it lies in a node region of an electromagnetic wave emitted during operation of the laser arrangement (10), and / or that it lies at the at least one intermediate region (70) of the waveguide layer (30, 40) embedding the zones (60) is aligned.

14. Optoelectronic system (300) having a laser arrangement (10) according to one of claims 1 to 13.

15. Method for producing a laser arrangement (10), comprising:

- Providing a substrate (20) having a main surface, - Arranging a first waveguide layer (30) on the main surface of the substrate (20), the first waveguide layer (30) having a first conductivity type,

- Arranging an active layer (50) on the first waveguide layer (30), the active layer (50) being designed to generate electromagnetic radiation through charge carrier recombination,

- Arranging a second waveguide layer (40) on a side of the active layer (50) facing away from the first waveguide layer (30), the second waveguide layer (40) having a second conductivity type opposite to the first conductivity type,

- Forming zones (60) arranged periodically to one another in the first waveguide layer (30) or in the second waveguide layer (40), the zones (60) having a refractive index that differs from a refractive index of the waveguide layer (60) embedding the zones (60). 30, 40) and form a two-dimensional photonic crystal with this waveguide layer (30, 40), and a periodicity of the zone arrangement is interrupted by at least one intermediate region (70) of the waveguide layer (30, 40) embedding the zones (60),

- Arranging a first contact layer (100) on the side of the first waveguide layer (30) facing away from the active layer (50), which is intended to provide electrical contact to the first waveguide layer (30),

Arranging a second contact layer (110) on the side of the second waveguide layer (40) facing away from the active layer (50), which is intended for this purpose to provide electrical contact to the second waveguide layer (40),

- wherein the first or second contact layer (100, 110) forms an aperture (210) which is intended to couple out electromagnetic radiation from the laser arrangement (10), and

- Arranging a dielectric and/or crystal-damaged layer (150) between the second contact layer (110) and the second waveguide layer (40).

16. The method of claim 15, further comprising

- Arranging a release layer (170) on the main surface of the substrate (20), the first waveguide layer (30) being arranged on a side of the release layer (170) facing away from the substrate (20),

- Arranging a carrier (180) on one of the active layers

(50) facing away from the second waveguide layer (40), and

- Detachment of the substrate (20) along the detachment layer

(170) .

17. The method according to any one of claims 15 to 16, wherein the zones (60) are formed by dry etching trenches or cavities in the first waveguide layer (30) or the second

Waveguide layer (40) are formed.

18. The method according to claim 17, further comprising:

- wet chemical etching, which is intended to reduce etching damage caused by the dry etching in the waveguide layer (30, 40) around the zones (60) embedding the zones (60), and/or - Tempering, which is intended to reduce etching damage caused by the dry etching in the waveguide layer (30, 40) around the zones that embeds the zones (60).