Edge-emitting semiconductor laser, method for producing a plurality of edge-emitting semiconductor lasers, laser component, and method for producing a laser component

Abstract

The invention relates to an edge-emitting semiconductor laser (18), comprising: - an epitaxial semiconductor layer stack (14) comprising a plurality of epitaxial semiconductor layers (4, 4'), which are stacked one above the other in a stacking direction (Rs), wherein - the epitaxial semiconductor layer stack (14) comprises an active region (22) in which, during operation, electromagnetic laser radiation (L) is generated, - the epitaxial semiconductor layer stack (14) has at least one facet (19), which laterally delimits the epitaxial semiconductor layer stack (14), and the facet (19) has a vertical structure (15) in the stacking direction (Rs), which influences at least one vertical mode (Myo, Mvi, MV2 ) of the electromagnetic laser radiation (L). The invention also relates to a method for producing a plurality of edge-emitting semiconductor lasers, a laser component, and a method for producing a laser component.

Description

[0001] DESCRIPTION

[0002] EDGE-EMMITTING SEMICONDUCTOR LASER, METHOD FOR PRODUCING A PLURALITY OF EDGE-EMMITTING

[0003] SEMICONDUCTOR LASER, LASER COMPONENT AND METHOD FOR MANUFACTURING A LASER COMPONENT

[0004] An edge-emitting semiconductor laser, a method for producing a plurality of edge-emitting semiconductor lasers, a laser component and a method for producing a laser component are specified.

[0005] The aim is to provide an improved edge-emitting semiconductor laser. In particular, an edge-emitting semiconductor laser with a long lifetime is to be provided.

[0006] Furthermore, a simplified method for producing a large number of edge-emitting semiconductor lasers, which in particular have a long lifetime, is to be specified.

[0007] Finally, an improved laser component and a simplified method for its manufacture are to be specified.

[0008] These objects are achieved by an edge-emitting semiconductor laser having the features of patent claim 1, by a laser component having the features of patent claim 15, by a method for producing a plurality of edge-emitting semiconductor lasers having the steps of patent claim 16 and by a method for producing a laser component having the steps of patent claim 20.

[0009] Advantageous embodiments and further developments of the edge-emitting semiconductor laser, the method for producing a plurality of edge-emitting semiconductor lasers, the laser component and the method for producing a laser component are specified in the respective dependent claims.

[0010] According to one embodiment, the edge-emitting semiconductor laser comprises an epitaxial semiconductor layer stack with a plurality of epitaxial semiconductor layers stacked one above the other in a stacking direction. In particular, the epitaxial semiconductor layers are epitaxially grown on a growth substrate. The growth substrate can be part of the edge-emitting semiconductor laser or removed from the finished semiconductor laser.

[0011] In particular, the edge-emitting semiconductor laser is an edge-emitting semiconductor laser diode.

[0012] According to a further embodiment of the edge-emitting semiconductor laser, the epitaxial semiconductor layer stack comprises an active zone in which electromagnetic laser radiation is generated during operation of the edge-emitting semiconductor laser. In particular, the active zone serves as a laser medium arranged within a resonator of the edge-emitting semiconductor laser. In conjunction with the resonator, a population inversion is generated within the active zone so that electromagnetic laser radiation is generated in the active zone by stimulated emission. Because the electromagnetic laser radiation is generated by stimulated emission, the electromagnetic laser radiation, in contrast to electromagnetic radiation generated by spontaneous emission, generally has a very high coherence length, a very narrow emission spectrum and / or a high degree of polarization.

[0013] According to a further embodiment of the edge-emitting semiconductor laser, the epitaxial semiconductor layer stack has at least one facet that laterally delimits the epitaxial semiconductor layer stack. The facet is, in particular, part of the epitaxial semiconductor layer stack. In particular, the facet completely or partially forms a side surface of the epitaxial semiconductor layer stack. In other words, the facet is, in particular, formed from the semiconductor material of the semiconductor layer stack.

[0014] According to a further embodiment of the edge-emitting semiconductor laser, the semiconductor layer stack has a further facet. The two facets are preferably located opposite one another and completely or partially form the side surfaces of the epitaxial semiconductor layer stack. In particular, the two facets run parallel to one another. All embodiments and features described here in connection with one facet can also be implemented in both facets.

[0015] According to a further embodiment, a highly reflective layer is applied to one of the facets, which is highly reflective for the electromagnetic laser radiation. Particularly preferably, a less reflective layer is applied to the other facet, which is partially transparent to a portion of the electromagnetic laser radiation generated in the active zone. In particular, the highly reflective layer and the less reflective layer together form the resonator of the edge-emitting semiconductor laser. For this purpose, the highly reflective layer and the less reflective layer are spaced from one another by a distance proportional to an integer multiple of half the wavelength of the electromagnetic laser radiation.An optical axis of the resonator is perpendicular to the facets and runs parallel to a main extension plane of the epitaxial semiconductor layers as well as parallel to a longitudinal direction. The longitudinal direction is perpendicular to the stacking direction. Furthermore, a lateral direction runs perpendicular to the stacking direction of the epitaxial semiconductor layers and perpendicular to the longitudinal direction.

[0016] According to one embodiment, the edge-emitting semiconductor laser has a radiation exit region from which the edge-emitting semiconductor laser emits electromagnetic laser radiation during operation. The radiation exit region of the edge-emitting semiconductor laser is, in particular, enclosed by the low-reflective layer, which is partially transparent to the electromagnetic laser radiation.

[0017] According to a further embodiment of the edge-emitting semiconductor laser, the facet has a vertical structure in the stacking direction, which influences at least one vertical mode of the electromagnetic laser radiation and / or at least reduces a current flow in the region of the facet. In particular, the vertical structure reduces or prevents the current flow through the facet, particularly preferably in the stacking direction. In particular, the electromagnetic laser radiation generally initially has different vertical, lateral and longitudinal modes. The longitudinal modes of the electromagnetic laser radiation extend in particular along the longitudinal direction, the lateral modes of the electromagnetic laser radiation extend along the lateral direction and the vertical modes of the electromagnetic laser radiation extend along the stacking direction.The vertical modes of electromagnetic laser radiation differ in wavelength, phase, and / or amplitude. The lateral modes of electromagnetic laser radiation and the longitudinal modes of electromagnetic laser radiation also differ in wavelength, phase, and / or amplitude.

[0018] Particularly in the case of an edge-emitting semiconductor laser with a comparatively wide vertical waveguide, the electromagnetic laser radiation generated in the resonator generally has a plurality of vertical modes. Therefore, particularly in the case of an edge-emitting semiconductor laser with a wide vertical waveguide, selection of the vertical modes by means of a vertical structure in the stacking direction in the facet is particularly expedient. For example, the vertical waveguide has a width of between 50 nanometers and 50 micrometers inclusive, preferably between 100 nanometers and 2 micrometers inclusive. A comparatively wide vertical waveguide advantageously reduces the facet loading due to irradiation with electromagnetic laser radiation. In particular, the vertical structure varies along the stacking direction.For example, the vertical structure is formed by recesses and / or projections in the facet which vary along the stacking direction. In particular, the vertical structure is not introduced into the facet randomly, but in a targeted manner. Furthermore, structural elements of the vertical structure, such as recesses and / or projections, do not have a random distribution in the facet. The vertical structure is designed in particular to specifically scatter and / or attenuate unwanted vertical modes, for example higher order modes, of the electromagnetic laser radiation, so that only one desired mode, for example the vertical fundamental mode, of the electromagnetic laser radiation is formed. The electromagnetic laser radiation which is emitted from the radiation exit region preferably has only one mode, for example the vertical fundamental mode.

[0019] According to a further embodiment of the edge-emitting semiconductor laser, the vertical structure is arranged so as to completely or partially overlap a radiation exit region of the edge-emitting semiconductor laser in the stacking direction. In other words, the vertical structure is arranged in the facet covered with the less reflective layer that comprises the radiation exit region, the vertical structure overlapping the radiation exit region in a plan view of the facet. Furthermore, it is also possible for the vertical structure to be arranged in the facet covered with the highly reflective layer and from which no electromagnetic laser radiation emerges. In this case, the vertical structure is likewise arranged so as to overlap the radiation exit region in a plan view of the facet.According to a further embodiment of the edge-emitting semiconductor laser, the vertical structure has at least one recess in the stacking direction or is formed by a recess. In particular, the recess extends from the facet in the longitudinal direction into the semiconductor layer stack. The recess can extend along the entire lateral direction within the epitaxial semiconductor layer stack or only partially. In particular, with the aid of the recess it is possible to reduce or prevent the current flow in the region of the facet in the stacking direction through the epitaxial semiconductor layer stack. In this way, damage to the facet during operation of the edge-emitting semiconductor laser by the electromagnetic laser radiation ("catastrophic optical damage" (COD for short)) can at least be reduced. This extends the lifetime of the edge-emitting semiconductor laser.

[0020] According to a further embodiment of the edge-emitting semiconductor laser, the vertical structure has two or more recesses in the stacking direction or consists of two or more recesses that have different depths in the longitudinal direction. In other words, the recesses extend to different depths in the longitudinal direction into the epitaxial semiconductor layer stack.

[0021] It is also possible for the vertical structure to have multiple recesses or to be formed from multiple recesses. The recesses may be of the same type or different configurations. All features and embodiments disclosed herein for one recess may also be implemented in other recesses of the vertical structure.

[0022] According to a further embodiment of the edge-emitting semiconductor laser, the recess is formed by etching one of the epitaxial semiconductor layers starting from the facet. For example, the material of one of the epitaxial semiconductor layers of the epitaxial semiconductor layer stack is partially or completely removed starting from the facet in a region extending in the longitudinal and / or lateral direction. For example, the etch has a depth, that is to say an extent in the longitudinal direction starting from the facet, which lies between 50 nanometers and 30 micrometers inclusive, or between 100 nanometers and 5 micrometers inclusive, or between 500 nanometers and 2 micrometers inclusive.

[0023] According to a further embodiment of the edge-emitting semiconductor laser, the epitaxial semiconductor layers of the epitaxial semiconductor layer stack comprise a III / V compound semiconductor material according to the formula In x Al y Gai- x-yGV with 0 < x < 1, 0 < y < 1 and x+y < 1 or are formed from such a III / V compound semiconductor material, where GV is an element of the fifth main group of the periodic table. In particular, GV is Al, In or Ga. Preferably, the epitaxial semiconductor layer with the etching has a higher aluminum content and / or a higher indium content than at least one of the directly adjacent epitaxial semiconductor layers. In particular, varying the aluminum content and / or the indium content enables selective etching of one of the epitaxial semiconductor layers compared to at least one directly adjacent epitaxial semiconductor layer of the epitaxial semiconductor layer stack.

[0024] According to one embodiment of the edge-emitting semiconductor laser, the epitaxial semiconductor layer with the etching has a different, preferably a higher, doping than at least one of the directly adjacent epitaxial semiconductor layers of the epitaxial semiconductor layer stack. Due to the different, preferably higher, doping, the epitaxial semiconductor layer preferably has a higher etching rate with respect to an etching medium than at least one of the directly adjacent epitaxial semiconductor layers, so that selective etching is possible. For example, the epitaxial semiconductor layer with the etching has a doping of at least 2 * 10 18 cm -3 or at least 10 19 cm -3 while at least one of the directly adjacent epitaxial semiconductor layers has a doping of at most 10 18 cm -3The epitaxial semiconductor layer with the higher doping is particularly preferably an n-doped epitaxial semiconductor layer.

[0025] According to one embodiment of the edge-emitting semiconductor laser, the epitaxial semiconductor layer is n-doped with the etching and has a higher doping than at least one of the directly adjacent epitaxial semiconductor layers.

[0026] For example, the recess is arranged in an n-doped cladding layer of the epitaxial semiconductor layer stack. In particular, the epitaxial semiconductor layer with the etching that forms the recess is arranged in the n-doped cladding layer of the epitaxial semiconductor layer stack. Thus, the recess has a distance in the stacking direction from the active zone that is sufficient to avoid damaging the active zone during etching of the epitaxial semiconductor layer and nevertheless to specifically influence the vertical modes, in particular higher-order modes.

[0027] Typically, the epitaxial semiconductor layer stack comprises two waveguide layers, namely a p-doped waveguide layer and an n-doped waveguide layer, between which the active zone is arranged. The waveguide layers are designed to guide the electromagnetic laser radiation within the resonator.

[0028] According to a further embodiment of the edge-emitting semiconductor laser, the recess is arranged between a waveguide layer of the epitaxial semiconductor layer stack and a substrate of the edge-emitting semiconductor laser. For example, the substrate is the growth substrate of the epitaxial semiconductor layer stack.

[0029] According to a further embodiment of the edge-emitting semiconductor laser, the recess is arranged between a waveguide layer of the epitaxial semiconductor layer stack and an electrical contact layer of the edge-emitting semiconductor laser. The electrical contact layer is designed in particular to impress a current into the active zone. The electrical contact layer is preferably arranged on or at a main surface of the epitaxial semiconductor layer stack that faces away from the substrate. The electrical contact layer can comprise a highly doped semiconductor material or be formed from a highly doped semiconductor material and be part of the epitaxial layer stack.Furthermore, it is also possible for the electrical contact layer to comprise a transparent conductive oxide (TCO for short), such as indium tin oxide (ITO for short), or to be formed from such a material. The electrical contact layer is, in particular, p-doped.

[0030] According to a further embodiment of the edge-emitting semiconductor laser, the recess is arranged in a waveguide layer of the epitaxial semiconductor layer stack, preferably in an n-doped waveguide layer.

[0031] In particular, the recess has a comparatively large distance from the active zone in the stacking direction. For example, the recess has a distance of at least 100 nanometers, preferably at least 200 nanometers, particularly preferably at least 500 nanometers from the active zone. The recess is arranged on a side of the waveguide layer facing away from the active zone.

[0032] According to a further embodiment of the edge-emitting semiconductor laser, the facet is free of current flow during operation of the edge-emitting semiconductor laser. This protects the facet from damage during operation. The current flow is interrupted, in particular, by the recess.

[0033] According to a further embodiment of the edge-emitting semiconductor laser, the recess is limited in the lateral direction. In other words, the recess does not extend completely in the lateral direction in a plan view of the main surface of the epitaxial semiconductor layer stack. If the recess is limited in the lateral direction, the facet has a lateral structure along the lateral direction. In this way, lateral modes of the electromagnetic laser radiation can also be specifically influenced in the lateral direction. In particular, it is also possible in this embodiment for the recess to have a variable width in the longitudinal direction in a plan view of the main surface of the epitaxial layer stack. If the geometry of the recess varies in the longitudinal direction, the facet also has a longitudinal structure along the longitudinal direction.In this way, longitudinal modes of the electromagnetic laser radiation can also be specifically influenced in the longitudinal direction.

[0034] According to a further embodiment of the edge-emitting semiconductor laser, the recess is completely or partially filled with a porous semiconductor material. For example, the porous semiconductor material is the semiconductor material of the etched epitaxial semiconductor layer. In other words, the recess of the epitaxial semiconductor layer is preferably not first completely etched free and subsequently filled with the porous semiconductor material; rather, the porous semiconductor material is created during the creation of the recess. For example, the recess is created by an etching process and adjusted such that the porous semiconductor material is created.

[0035] According to a further embodiment, the edge-emitting semiconductor laser has a ridge waveguide. The ridge waveguide is generally formed by a projection in the main surface of the epitaxial semiconductor layer stack that faces away from the substrate. The ridge waveguide is designed to guide the electromagnetic laser radiation within the epitaxial semiconductor layer stack. Therefore, the radiation exit region of the edge-emitting semiconductor laser is generally arranged below the ridge waveguide along the stacking direction.

[0036] According to a further embodiment, the edge-emitting semiconductor laser is an index-guided edge-emitting semiconductor laser which is free of a ridge waveguide.

[0037] The edge-emitting semiconductor laser is particularly suitable for use in a laser component. The laser component, in particular, comprises at least two edge-emitting semiconductor lasers. Features and embodiments disclosed herein in connection with the edge-emitting semiconductor laser can also be implemented in the laser component, and vice versa.

[0038] In particular, the edge-emitting semiconductor lasers of a laser component can be configured differently from one another or of the same type. For example, the edge-emitting semiconductor lasers of a laser component emit electromagnetic laser radiation that is at least partially different from one another. In particular, the electromagnetic laser radiation of the edge-emitting semiconductor lasers can have different wavelengths. Furthermore, it is possible for the edge-emitting semiconductor lasers to have identical or different vertical facet structures in the stacking direction.

[0039] A plurality of edge-emitting semiconductor lasers can be manufactured using the method described below. Features and embodiments described herein in connection with the edge-emitting semiconductor laser can also be implemented in the method, and vice versa. According to one embodiment of the method for manufacturing a plurality of edge-emitting semiconductor lasers, an epitaxial semiconductor layer sequence is provided which comprises a plurality of epitaxial semiconductor layers stacked one above the other in a stacking direction. The epitaxial semiconductor layer sequence comprises an active region in which electromagnetic radiation is generated during operation.

[0040] According to a further embodiment of the method, one or more trenches are created in the epitaxial semiconductor layer sequence. In particular, a side surface of a trench at least partially forms a facet of a finished edge-emitting semiconductor laser.

[0041] For example, the trenches in the epitaxial semiconductor layer sequence are created using a dry etching process, in which the side surfaces of the trenches are generally initially tilted relative to the stacking direction. Furthermore, the side surfaces of the trenches are generally initially rough after the dry etching process. The dry etching process involves, for example, a plasma etching process or reactive ion etching (RIE for short).

[0042] According to a further embodiment of the method, vertical structures are produced in the side surfaces of the trenches in the stacking direction. In particular, the vertical structures are structures which have a variation in the stacking direction. According to a further embodiment of the method, the vertical structures in the side surfaces of the trenches are recesses which are formed by selectively etching at least one epitaxial semiconductor layer starting from the side surfaces of the trenches. In particular, at least one or exactly one epitaxial semiconductor layer of the epitaxial semiconductor layer sequence is etched starting from the side surfaces of the trenches in the longitudinal and / or lateral direction, such that the semiconductor material of the etched epitaxial semiconductor layer is removed or made porous.This is particularly possible if the epitaxial semiconductor layer to be etched has a higher etching rate with respect to an etching medium than at least one epitaxial semiconductor layer directly adjacent to the epitaxial semiconductor layer to be etched. For example, the epitaxial semiconductor layer to be etched has a higher aluminum and / or indium content and / or a higher doping compared to at least one directly adjacent epitaxial semiconductor layer. The differences in the aluminum content, the indium content and / or the doping can produce selectivity with respect to an etching medium.

[0043] The selective etching of the at least one epitaxial semiconductor layer is carried out in particular by wet-chemical etching. For example, one or more of the following materials can be used as the liquid etching medium: KOH, TMAH (tetramethylammonium hydroxide), NH3, NaOH.

[0044] In particular, the method for producing a large number of edge-emitting semiconductor lasers has the advantage that there is no need for a lithographic mask to form the vertical structure. Instead, the vertical structure is achieved by different etching rates of the various epitaxial semiconductor layers in relation to an etching medium. In this way, very small vertical structures in particular can be specifically produced and positioned in the facet, the dimensions of which in the stacking direction are predetermined by the thickness of the epitaxial semiconductor layers. The epitaxial semiconductor layers have a thickness of one atomic layer up to several micrometers. For example, the thickness of the epitaxial semiconductor layers is between 1 nanometer and 10 micrometers inclusive, or between 20 nanometers and 1 micrometer inclusive.

[0045] According to a further embodiment of the method, during the selective etching of at least one of the epitaxial semiconductor layers, an electrical voltage is applied to the epitaxial semiconductor layer sequence. For example, the electrical voltage has a value between 0.5 volts and 25 volts inclusive or between 1 volt and 10 volts inclusive. In particular, the electrical voltage is applied only to partial regions of the epitaxial semiconductor layer sequence, for example by applying metallic contacts only to partial areas of the ridge waveguide and / or a main area of ​​the epitaxial semiconductor layer sequence. In this way, current can flow through only partial areas of the epitaxial semiconductor layer sequence during etching, so that the etching is increased by the current flow.Thus, in addition to a vertical structure in the stacking direction, a lateral structure in the lateral direction and / or a longitudinal structure in the longitudinal direction starting from the facet can also be produced. According to a further embodiment of the method, during the selective etching of the at least one epitaxial semiconductor layer, partial regions of the epitaxial semiconductor layer sequence are irradiated with electromagnetic radiation. In particular, the electromagnetic radiation with which partial regions of the epitaxial semiconductor layer sequence are irradiated has an energy that is greater than an electronic band gap of the epitaxial semiconductor layer to be etched. Thus, during irradiation with the electromagnetic radiation, charge carriers are generated in the irradiated regions, which locally increase the etching rate.In this way, in addition to a vertical structure in the stacking direction, a lateral structure in the lateral direction and / or a longitudinal structure in the longitudinal direction starting from the facet can also be created.

[0046] The method for producing a plurality of edge-emitting semiconductor lasers preferably takes place at the wafer level. This means that the epitaxial semiconductor layer sequence is part of a wafer composite or is formed as a wafer composite, and the plurality of edge-emitting semiconductor lasers is manufactured simultaneously. This simplifies the manufacturing process.

[0047] At the end of the process, the edge-emitting semiconductor lasers are separated, for example by scribing and breaking, stealth dicing, or laser cutting. In particular, the trenches in the epitaxial semiconductor layer sequence define separation lines along which the semiconductor lasers are separated.

[0048] During singulation, the edge-emitting semiconductor lasers are created with the epitaxial semiconductor layer stacks and the active zone. The epitaxial semiconductor layer stacks of the various edge-emitting semiconductor lasers are part of the active semiconductor layer sequence at the wafer level, and the active zones are part of the active region at the wafer level. Features and embodiments described herein in connection with the epitaxial semiconductor layer stack and the active zone can therefore also be implemented in the epitaxial semiconductor layer sequence and the active region, and vice versa.

[0049] The following describes a method for producing a laser component with at least two edge-emitting semiconductor lasers. Features and embodiments described herein in connection with the method for producing a plurality of edge-emitting semiconductor lasers can also be implemented in the method for producing the laser component, and vice versa.

[0050] According to one embodiment of the method for producing a laser component, a wafer assembly with a plurality of edge-emitting semiconductor lasers is provided. The edge-emitting semiconductor lasers of the wafer assembly are configured, for example, as already described.

[0051] According to a further embodiment of the method, the wafer composite is singulated into separate laser components, for example by breaking and scribing, in particular along the trenches. After singulation, each laser component comprises at least two edge-emitting semiconductor lasers. The edge-emitting semiconductor lasers have epitaxial semiconductor layer stacks that are laterally delimited by facets. Furthermore, the epitaxial semiconductor layer stacks have a plurality of epitaxial semiconductor layers that are stacked one above the other in a stacking direction.

[0052] According to a further embodiment of the method, vertical structures are produced in the facets of the edge-emitting semiconductor lasers in a stacking direction.

[0053] According to a further embodiment of the method, the vertical structures in the facets are recesses which are formed by selectively etching at least one epitaxial semiconductor layer starting from the facet.

[0054] According to a further embodiment of the method, an electrical voltage is applied to the epitaxial semiconductor layer stacks during the selective etching and / or at least partial regions of the epitaxial semiconductor layer stacks are irradiated with electromagnetic radiation.

[0055] In other words, it is possible that in order to produce a laser component with at least two edge-emitting semiconductor lasers, the laser components are first completely separated from the wafer composite, for example by scribing and breaking, and subsequently the facets of the edge-emitting semiconductor lasers of the laser component are provided with a vertical structure in the stacking direction by the method already described.

[0056] The edge-emitting semiconductor laser described here and / or the laser component described here can be used, for example, in AR devices (AR: short for "augmented reality"), VR devices (VR: short for "virtual reality"), projection devices, laser illumination, devices for material processing and / or devices for distance measurement, for example with LIDAR (short for "light detection and ranging" or "light imaging, detection and ranging").

[0057] Further advantageous embodiments and developments of the edge-emitting semiconductor laser, the method for producing a plurality of edge-emitting semiconductor lasers, the laser component and the method for producing a laser component emerge from the embodiments described below in conjunction with the figures.

[0058] Figures 1 to 3 show schematic representations of stages of a method for producing a plurality of edge-emitting semiconductor lasers according to an embodiment.

[0059] Figures 4 to 5 show schematic representations of stages of a method for producing a plurality of edge-emitting semiconductor lasers according to a further embodiment.

[0060] Figures 6 to 8 show schematic representations of an edge-emitting semiconductor laser according to an embodiment.

[0061] Figures 9 to 11 show schematic representations of an edge-emitting semiconductor laser according to a further embodiment.

[0062] Figures 12 to 16 schematically show sections of an edge-emitting semiconductor laser according to further embodiments. Figures 17 and 18 show schematic representations of stages of a method for producing a plurality of edge-emitting semiconductor lasers according to a further embodiment.

[0063] Figure 19 shows a schematic representation of an edge-emitting semiconductor laser according to a further embodiment.

[0064] Figures 20 and 21 show embodiments of metallic contacts as can be used in the method according to the embodiment of Figures 17 and 18.

[0065] Figure 22 shows a schematic representation of a stage of a method for producing a plurality of edge-emitting semiconductor lasers according to a further embodiment.

[0066] Figures 23 to 25 show schematic representations of stages of a method for producing a laser component according to an embodiment.

[0067] Figures 26 and 27 show schematic representations of a laser component according to various embodiments.

[0068] Figure 28 shows a schematic representation of a stage of a method for producing a plurality of edge-emitting semiconductor lasers according to a further embodiment.

[0069] Identical, similar, or functionally identical elements are provided with the same reference symbols in the figures. The figures and the relative sizes of the elements depicted in the figures are not to be considered to scale. Rather, individual elements, particularly layer thicknesses, may be exaggerated for clarity and / or clarity.

[0070] In the method for producing a plurality of edge-emitting semiconductor lasers according to the exemplary embodiment of Figures 1 to 3, an epitaxial semiconductor layer sequence 1 is first provided, which is part of a wafer assembly 2 (Figure 1). In addition to the epitaxial semiconductor layer sequence 1, the wafer assembly 2 comprises a substrate 3, which is, for example, a growth substrate on which the epitaxial semiconductor layer sequence 1 has been epitaxially grown.

[0071] The epitaxial semiconductor layer sequence 1 comprises a plurality of epitaxial semiconductor layers 4 arranged in a stacking direction R s are stacked one above the other. In particular, the epitaxial semiconductor layer sequence 1 comprises an active region 5 in which electromagnetic radiation is generated during operation.

[0072] The active region 5 is arranged between an n-doped waveguide layer 6 and a p-doped waveguide layer 7, which in the present case directly adjoin the active region 5. In addition, the epitaxial semiconductor layer sequence 1 comprises an n-doped cladding layer 8 and a p-doped cladding layer 9, between which the n-doped waveguide layer 6, the p-doped waveguide layer 7 and the active region 5 are arranged. Furthermore, the epitaxial semiconductor layer sequence 1 comprises a highly p-doped electrical contact layer 10, which is arranged on a main surface of the epitaxial layer facing away from the substrate 3.

[0073] Semiconductor layer sequence 1 is arranged.

[0074] The n-doped cladding layer 8 and the n-doped waveguide layer 6 are part of an n-doped region 32 of the epitaxial semiconductor layer sequence 1, while the p-doped cladding layer 9 and the p-doped waveguide layer 7 are part of a p-doped region 31 of the epitaxial semiconductor layer sequence 1.

[0075] Finally, the epitaxial semiconductor layer sequence 1 comprises an epitaxial semiconductor layer 4', which in the present case is arranged between the n-doped waveguide layer 6 and the n-doped cladding layer 8, which is designed to be provided with a recess 11 by selective etching against a directly adjacent epitaxial semiconductor layer 4". The epitaxial semiconductor layer 4' to be etched lies in the n-doped region 32 of the epitaxial semiconductor layer sequence 1.

[0076] In a next step, which is schematically illustrated in Figure 2, a plurality of trenches 12 are produced in the epitaxial semiconductor layer sequence 1. However, for reasons of clarity, only two trenches 12 are shown here. In particular, the trenches 12 penetrate the epitaxial semiconductor layer sequence 1 completely and the substrate 3 partially. The trenches 12 are produced here by a dry etching process and have oblique side surfaces 13 which are oriented relative to the stacking direction R s are arranged tilted. Furthermore, the side surfaces 13 of the trenches 12 are rough. By introducing the trenches 12, epitaxial semiconductor layer stacks 14 are defined, which are arranged between two directly adjacent trenches 12 and are delimited by their side surfaces 13.

[0077] In a next step, vertical structures 15 are formed in the side surfaces 13 of the trenches 12 in the stacking direction R sgenerated (Figure 3). In particular, recesses 11 are generated in the epitaxial semiconductor layer sequence 1 starting from the side surfaces 13 of the trenches 12 by wet-chemical etching. In the present case, the recesses 11 are generated in the epitaxial semiconductor layer 4' to be etched by wet-chemical selective etching with an alkaline etching medium, such as KOH, TMAH, NH3 and / or NaOH. The epitaxial semiconductor layer 4' to be etched has a higher etching rate compared to the alkaline etching medium compared to the directly adjacent epitaxial semiconductor layer 4", which in the present case serves as an etching stop layer, for example due to a higher aluminum content and / or a higher indium content and / or a greater doping. For example, the recesses 11 are arranged on a side of the cladding layer 6 facing away from the active region 5.The side surfaces 13 of the trenches 12 are further formed vertically by wet chemical etching with the alkaline etching medium.

[0078] Finally, the edge-emitting semiconductor lasers are separated along separating lines 16 which run in the trenches 12 (not shown).

[0079] In the method according to the embodiment of Figures 4 and 5, the structure of the epitaxial semiconductor layer sequence 1 differs from the structure of the epitaxial semiconductor layer sequence 1 according to the embodiment of Figures 1 to 3. In particular, the epitaxial semiconductor layer sequence 1 has two epitaxial semiconductor layers 4', into which etchings 17 are to be introduced as recesses 11 by selective etching.

[0080] First, as already described with reference to Figure 2, a plurality of trenches 12 are introduced into the epitaxial semiconductor layer sequence 1 using a dry etching process (Figure 4).

[0081] As already described with reference to Figure 3, a wet-chemical etching is then carried out using a liquid etching medium, the epitaxial semiconductor layers 4' to be etched being etched selectively with respect to at least one directly adjacent epitaxial semiconductor layer 4, so that etches 17 are formed as recesses 11 starting from the side surfaces 13 of the trenches 12 in the epitaxial semiconductor layer stacks 14. In the present case, the epitaxial semiconductor layers 4' to be etched are of identical design, so that the recesses 11 are also formed in the same way in the epitaxial semiconductor layer stacks 14 (Figure 5).

[0082] The edge-emitting semiconductor laser 18 according to the embodiment of Figures 6 to 8 can be produced, for example, using the method according to Figures 1 to 3.

[0083] The edge-emitting semiconductor laser 18 according to the embodiment of Figures 6 to 8 has an epitaxial semiconductor layer stack 14 with a plurality of epitaxial semiconductor layers 4 arranged in a stacking direction R s are stacked one above the other. The epitaxial semiconductor layer stack 14 is laterally delimited by facets 19, which lie opposite one another and run parallel to one another. The epitaxial semiconductor layer stack 14 further comprises an active zone 22, in which electromagnetic laser radiation L is generated during operation of the edge-emitting semiconductor laser 18.

[0084] Furthermore, a less reflective layer 20 is applied to one facet 19, which is partially transparent to the electromagnetic laser radiation. Therefore, during operation of the edge-emitting semiconductor laser 18, electromagnetic laser radiation L is coupled out of this facet 19 from a radiation exit region 21 (Figures 7 and 8).

[0085] Furthermore, a highly reflective layer 23 is formed on the opposite facet 19, which is highly reflective for the electromagnetic laser radiation L of the active zone 22. The highly reflective layer 23 on one facet 19 and the less reflective layer 20 on the other facet 19 form a resonator 24 of the edge-emitting semiconductor laser 18. An optical axis 25 of the resonator 24 extends along a longitudinal direction R L0 . Perpendicular to the longitudinal direction R LO and to the stacking direction R sextends a lateral direction R LA ( Figure 6 ) .

[0086] As shown by way of example in Figure 7, the facets 19 have a vertical structure 15 in the stacking direction R s. In particular, the vertical structure 15 is formed in the present case by a recess 11 which extends from the facet 19 into the epitaxial semiconductor layer stack 14. In the present case, the recess 11 is formed by etching one of the epitaxial semiconductor layers 4 ' of the epitaxial semiconductor layer stack 14. The edge-emitting semiconductor laser 18 according to Figures 6 to 8 has a metallic contact layer 26 on the electrical contact layer 10 which is designed to impress a current into the edge-emitting semiconductor laser 18 and in particular into the active zone 5. For this purpose, a further metallic contact layer is applied to a rear main surface of the substrate 3, which is not shown here for reasons of clarity.

[0087] Figure 8 shows a section of the epitaxial semiconductor layer stack 14 with one of the facets 19. As the arrows illustrate, the epitaxial semiconductor layer 4' with the etching 17 limits the current flow through the active zone 5. At the facet 19, a crystal of the epitaxial semiconductor layer stack 14 is interrupted, so that non-radiative recombination centers are arranged there in particular. During operation, the non-radiative recombination centers generate heat when current flows, which promotes damage to the facet 19 due to COD.

[0088] Furthermore, the metallic contact layer 26, which is applied to the main surface of the epitaxial semiconductor layer stack 14 facing away from the substrate 3, is arranged retracted from the two facets 19. In this way, too, the current flow in regions of the epitaxial semiconductor layer stack 14 close to the facets can at least be reduced. However, it is also possible for the metallic contact layer 26 to directly adjoin the facets 19, since the current flow is already prevented accordingly by the recess 11. In this way, structuring of the metallic contact layer 26 can advantageously be dispensed with. As can be seen in Figures 7 and 8, the substrate 3 has a projection 27 relative to the epitaxial semiconductor layer stack 14.In particular, the facet 19 is formed by the plasma etching process and the subsequent wet-chemical process, while a complete separation within the trenches 12 is achieved by a further separation process, such as mechanical breaking. This typically forms the protrusion 27 in the substrate 3.

[0089] The edge-emitting semiconductor laser 18 according to the embodiment of Figures 9 to 11 can be produced, for example, using the method according to Figures 4 and 5.

[0090] The edge emitting semiconductor laser 18 has an active zone 22 which is arranged between two epitaxial semiconductor layers 4 ' which are provided with recesses 11 , starting from a facet 19 , in the longitudinal direction R L0 in the epitaxial semiconductor layer stack 14. Through the recesses 11, a vertical structure 15 is formed in the facet 19 in the stacking direction R s formed ( Figure 9 ) .

[0091] The edge-emitting semiconductor laser 18 according to the exemplary embodiment of Figures 9 to 11 further comprises a ridge waveguide 28 formed by a projection 29 in the epitaxial semiconductor layer stack 14. In particular, Figure 10 shows a schematic plan view of the facet 19 of the edge-emitting semiconductor laser 18 with the ridge waveguide 28.

[0092] Figure 11 shows the section A marked by a dashed rectangle in Figure 10. In particular, Figure 11 schematically shows the formation of vertical modes of the electromagnetic laser radiation L. Figure 11 shows the course of the zero-order vertical mode Mvo (vertical fundamental mode) of the electromagnetic laser radiation L, the first-order vertical mode M Vi the electromagnetic laser radiation L and the vertical second-order mode M Vo of the electromagnetic laser radiation L in a vertical waveguide 30 of width B . The vertical fundamental mode M V o is amplified in the vertical waveguide 30 , since the minimum of the vertical fundamental mode Mvo with the etched epitaxial semiconductor layers 4 ' and the maximum of the vertical fundamental mode M V o overlaps with the active zone 22 .

[0093] Furthermore, the first-order vertical mode M Vi of the electromagnetic laser radiation L reaches a minimum in the active zone 22 , so that the vertical first-order mode M Vi is not amplified during operation of the edge-emitting semiconductor laser 18.

[0094] The second-order vertical mode M V However, o has a maximum in the active zone 22 , so that the vertical second-order mode M Vo would be enhanced without further measures. However, since another maximum of the second-order vertical mode M V o overlaps with the etched epitaxial semiconductor layer 4 ' , the vertical second order mode M V o strong scattering losses in this area and is thus attenuated. Thus, a comparatively wide vertical waveguide 30 can be realized in the edge-emitting semiconductor laser 18 and nevertheless, due to the vertical structure 15 in the facet 19, only the vertical fundamental mode Mvo of the electromagnetic laser radiation L can be formed during operation of the edge-emitting semiconductor laser 18. In the edge-emitting semiconductor lasers 18 according to the embodiments of Figures 12 to 16, in particular the vertical structures 15 along the stacking direction R s in facet 19 .

[0095] In the edge-emitting semiconductor laser 18 according to the embodiment of Figure 12, the epitaxial semiconductor layer 4' with the etching 17 is arranged in a p-doped region 31 of the epitaxial semiconductor layer stack 14. In particular, the epitaxial semiconductor layer 4' with the etching 17 is arranged between a highly p-doped electrical contact layer 10 and a p-doped cladding layer 9. In this way, too, as symbolized by the arrows, a current flow in the region of the facet 19 can be at least reduced in order to at least reduce the exposure of the facet 19 to electromagnetic laser radiation L during operation of the edge-emitting semiconductor laser 18.

[0096] In the edge-emitting semiconductor laser 18 according to the embodiment of Figure 13, several epitaxial semiconductor layers 4' of the epitaxial semiconductor layer stack 14 are provided with a recess 11, in particular an etching 17, starting from a facet 19 of the edge-emitting semiconductor laser 18. The recesses 11 extend to different depths along a longitudinal direction R LO into the epitaxial semiconductor layer stack 14 .

[0097] In the edge-emitting semiconductor laser 18 according to Figure 14, the epitaxial semiconductor layer sequence 1 is formed before etching, as already described with reference to Figures 4 and 5. In contrast to the method according to the exemplary embodiment of Figures 4 and 5, however, the etching process for forming the etchings 17 in the epitaxial semiconductor layers 4' to be etched is modified, so that the semiconductor material of the epitaxial semiconductor layers 4' to be etched is not completely removed, but is porous. Consequently, the recess 11 is filled with a porous material 33.

[0098] The edge-emitting semiconductor laser 18 according to the embodiment of Figure 15, in contrast to the edge-emitting semiconductor laser 18 according to the embodiment of Figure 14, has etchings 17 that are only partially filled with a porous semiconductor material 33. In particular, the recesses 11 are filled with different porous semiconductor materials 33, 33'. The recesses 11 of the epitaxial semiconductor layers 4' according to Figure 14 have, in particular, two different porous semiconductor materials 33, 33'. Furthermore, the recesses 11 are not completely filled with the porous semiconductor materials 33, 33'. This can be achieved by a further modification of the etching process.

[0099] The edge-emitting semiconductor laser 18 according to the embodiment of Figure 16 likewise has two etched epitaxial semiconductor layers 4' which have recesses 11 starting from the facet 19. The etched epitaxial semiconductor layers 4' differ in their material composition. Therefore, one recess 11 is filled with a porous semiconductor material 33 which was produced by not completely etching out the recess 11, but by the semiconductor material of the epitaxial semiconductor layer 4' being only partially porosified by the etching process. The other epitaxial semiconductor layer 4', however, has an empty recess 11.

[0100] In the method for producing a plurality of edge-emitting semiconductor lasers according to the exemplary embodiment of Figures 17 to 18, an epitaxial semiconductor layer sequence 1 is again provided which comprises a plurality of epitaxial semiconductor layers 4. Furthermore, the epitaxial semiconductor layer sequence 1 comprises a plurality of epitaxial semiconductor layer stacks 14, each epitaxial semiconductor layer stack 14 having a projection 29 which forms a ridge waveguide 29 in the finished semiconductor laser 18. For reasons of clarity, only one epitaxial semiconductor layer stack 14 is shown in the figures. However, the epitaxial semiconductor layer sequence 1 comprises a plurality of epitaxial semiconductor layer stacks 14 which are separated from one another by trenches 12.

[0101] Two metallic contacts 34 are applied to the projection 29 and extend from a side surface 13 of the trench 12 along the longitudinal direction R L0 extend on the projection 29 ( Figure 17 ) .

[0102] The epitaxial semiconductor layer sequence 1 with the trenches 12 and the metallic contacts 34 on the projections 29 are introduced into an alkaline etching medium 35 in a next step, which is schematically illustrated in Figure 18. In this case, a voltage U is applied between the metallic contacts 34 on the projection 29 and an electrode 36 in the alkaline etching medium 35. Due to the applied voltage U, a current flows through the epitaxial semiconductor layer stacks 14 of the epitaxial semiconductor layer sequence 1 during the wet-chemical selective etching of at least one epitaxial semiconductor layer 4', so that the epitaxial semiconductor layer 4' to be etched is etched only in the region of the metallic contacts 34. Thus, in addition to a vertical structure 15 in the stacking direction R sfor controlling vertical modes of the electromagnetic laser radiation L also a lateral structure 37 for controlling lateral modes of the electromagnetic laser radiation L in lateral direction R LA be introduced into facet 19 .

[0103] Figure 19 shows schematically the theoretical course of a zero-order lateral mode M L0 ( lateral fundamental mode ) of the electromagnetic laser radiation L and a lateral first-order mode M L1 of the electromagnetic laser radiation L in the edge-emitting semiconductor laser 18, which is manufactured, for example, using the method according to Figures 17 and 18. The lateral fundamental mode M L0 the electromagnetic laser radiation L overlaps with the lateral structures 37 formed by the etchings 17 in the facet 19 .

[0104] This causes the lateral fundamental mode M L0scattered and does not form or only forms to a small extent in the resonator 24 of the edge-emitting semiconductor laser 18. The first-order lateral mode M L1 The electromagnetic laser radiation L , on the other hand, is not or only slightly disturbed by the etched lateral structures 37 , so that it can form in a lateral waveguide 38 .

[0105] Figures 20 and 21 show further embodiments of the metallic contacts 34 on the main surface of the projection 29. The metallic contacts 34 according to Figure 20 have a rectangular shape in plan view. In contrast, the metallic contacts 34 on the projection 29 according to Figure 21 initially have a continuous, completely connected base surface, from which two strip-shaped regions extend in the longitudinal direction R L0which taper starting from the side surface 13 of the trench 12. The shapes of the metallic contacts 34 are transferred into the shapes of the recesses 11 during the wet-chemical etching.

[0106] 22, a mask 39 is applied to the projection 29, which forms the ridge waveguide 28 in the finished edge-emitting semiconductor laser 18. The mask is made, for example, from metal or from an absorbing dielectric, such as silicon or germanium or a mixture of these materials. The wafer composite 2 with the introduced trenches 12 is in turn introduced into an alkaline etching medium 35. During etching in the alkaline etching medium 35, the epitaxial semiconductor layer sequence 1 is irradiated with UV electromagnetic radiation from the ultraviolet spectral range. As a result, charge carriers are induced in the parts of the active region 5 that are not covered by the mask 39, which charge carriers lead to intensified etching of the epitaxial semiconductor layer 4' to be etched. In this way, a lateral structure 37 can also be achieved in the facet 19.

[0107] In the method according to the embodiment of Figures 23 to 26, a wafer composite 2 with a plurality of edge-emitting semiconductor lasers 18 is provided (Figure 23). The wafer composite 2 is separated into separate laser components comprising at least two edge-emitting semiconductor lasers 18, for example by breaking and scribing (Figure 24). The edge-emitting semiconductor lasers 18 have epitaxial semiconductor layer stacks 14, which are laterally delimited by facets 19 and comprise a plurality of epitaxial semiconductor layers 4, which are arranged in a stacking direction R s are stacked on top of each other. Furthermore, the epitaxial semiconductor layer stacks 14 have projections 29 which serve as ridge waveguides 28. In a next step, vertical structures 15 are inserted into the facets 19 of the edge-emitting semiconductor lasers 18 in a stacking direction R sby etching in an etching medium 35 ( Figure 25 ) , as already described .

[0108] The laser component according to the exemplary embodiment of Figure 26 can be manufactured, for example, using the method described with reference to Figures 23 to 25. In particular, vertical structures 15 in facets 19 of the two edge-emitting semiconductor lasers 18 are formed identically.

[0109] In contrast, facets 19 of the edge-emitting semiconductor lasers 18 of the laser component according to the embodiment of Figure 27 are treated differently, so that different vertical structures 15 in the stacking direction R sare generated in the facets 19. This can be achieved by a suitable selection of the previously described parameters during etching, such as the current supply or illumination. Thus, different edge-emitting semiconductor lasers 18 with different emission properties can be realized in one laser component.

[0110] In the method according to the embodiment of Figure 28, in contrast to the method according to the embodiment of Figures 17 and 18, not only is a voltage U applied between the metallic contacts 34 on the projections 29 of the epitaxial semiconductor layer stacks 14 and the electrode 36 in the etching medium 35, but irradiation with ultraviolet light UV also takes place at the same time. The invention is not limited to the embodiments by the description based on these. Rather, the invention encompasses any new feature and any combination of features, which in particular includes any combination of features in the patent claims, even if this feature or this combination itself is not explicitly stated in the patent claims or embodiments.

[0111] LIST OF REFERENCE SYMBOLS

[0112] 1 epitaxial semiconductor layer sequence

[0113] 2 wafer composite

[0114] 3 Substrat

[0115] 4 , 4 ' , 4 '' epitaxial semiconductor layer

[0116] 5 active area

[0117] 6 n-doped waveguide layer

[0118] 7 p-doped waveguide layer

[0119] 8 n-doped cladding layer

[0120] 9 p-doped cladding layer

[0121] 10 electrical contact layer

[0122] 11 Recess

[0123] 12 trenches

[0124] 13 Side surface

[0125] 14 epitaxial semiconductor layer stack

[0126] 15 vertical structure

[0127] 16 dividing line

[0128] 17 Etching

[0129] 18 edge-emitting semiconductor lasers

[0130] 19 facets

[0131] 20 low reflective layer

[0132] 21 Radiation exit area

[0133] 22 active zone

[0134] 23 highly reflective layer

[0135] 24 resonators

[0136] 25 optical axis

[0137] 26 metallic contact layer

[0138] 27 Projection of the substrate

[0139] 28 ridge waveguides

[0140] 29 lead

[0141] 30 vertical waveguide

[0142] 31 p-doped region 32 n-doped region

[0143] 33 , 33 ' porous semiconductor material

[0144] 34 metallic contact

[0145] 35 corrosive medium

[0146] 36 Electrode

[0147] 37 lateral structure

[0148] 38 lateral waveguide

[0149] 39 Mask

[0150] R s Stacking direction

[0151] L electromagnetic laser radiation

[0152] RLO longitudinal direction

[0153] RLA lateral direction

[0154] A section

[0155] Myo vertical zero-order mode

[0156] Mvi vertical first-order mode

[0157] MV2 vertical second-order mode

[0158] U voltage

[0159] M L0 zero-order lateral mode

[0160] M L1 first-order lateral mode

[0161] UV electromagnetic radiation

Claims

Patentan's Sayings 1. Edge-emitting semiconductor laser (18) with: - an epitaxial semiconductor layer stack (14) comprising a plurality of epitaxial semiconductor layers (4, 4') arranged in a stacking direction (R s ) are stacked on top of each other, with - the epitaxial semiconductor layer stack (14) comprises an active zone (22) in which electromagnetic laser radiation (L) is generated during operation, - the epitaxial semiconductor layer stack (14) has at least one facet (19) which laterally delimits the epitaxial semiconductor layer stack (14), and - the facet (19) in the stacking direction (R s ) has a vertical structure (15) which influences at least one vertical mode (Myo, Mvi, MV2 ) of the electromagnetic laser radiation (L), wherein the vertical structure (15) in the stacking direction (R s) has at least one recess (11) and the recess (11) is arranged between a waveguide layer (6, 7) of the epitaxial semiconductor layer stack (14) and a substrate (3) of the edge-emitting semiconductor laser (18) on a side of the waveguide layer (6, 7) facing away from the active zone (22).

2. Edge-emitting semiconductor laser (18) according to the preceding claim, wherein the vertical structure (15) is at least partially arranged in the stacking direction (R s ) is arranged overlapping with a radiation exit region (21) of the edge-emitting semiconductor laser ( 18 ).

3. Edge-emitting semiconductor laser (18) according to claim 1 or 2, wherein the vertical structure (15) in the stacking direction (R s ) has two or more recesses (11) which have different depths in a longitudinal direction (RLO).

4. Edge-emitting semiconductor laser (18) according to one of the preceding claims, wherein the recess (11) is formed by an etching (17) of one of the epitaxial semiconductor layers (4') starting from the facet (19).

5. Edge-emitting semiconductor laser (18) according to claim 4, wherein - the epitaxial semiconductor layers (4, 4', 4'') of the epitaxial semiconductor layer stack (14) comprise a III / V compound semiconductor material according to the formula In x Al y Gai- x-y GV with 0 < x < 1, 0 < y < 1 and x+y < 1, where GV is an element of the fifth main group of the periodic table, and - the epitaxial semiconductor layers (4') with the etching (17) have a higher aluminum content and / or a higher indium content than at least one of the directly adjacent epitaxial semiconductor layers (4'').

6. Edge-emitting semiconductor laser (18) according to one of the preceding claims, wherein the epitaxial semiconductor layer (4') is n-doped with the etching (17) and has a higher doping than at least one of the directly adjacent epitaxial semiconductor layers (4'').

7. Edge-emitting semiconductor laser (18) according to claim 6, wherein the recess (11) is formed in an n-doped cladding layer (8) of the epitaxial semiconductor layer stack (14).

8. Edge-emitting semiconductor laser (18) according to one of the preceding claims, wherein the recess (11) extends in a lateral direction (R LA ) is limited.

9. Edge-emitting semiconductor laser (18) according to claim 8, wherein the recess (11) is in a longitudinal direction (R L O) has a variable width.

10. Edge-emitting semiconductor laser (18) according to one of the preceding claims, wherein the recess (11) is completely or partially filled with a porous semiconductor material (33, 33').

11. Laser component with at least two edge-emitting Semiconductor lasers (18) according to one of the preceding claims.

12. A method for producing a plurality of edge-emitting semiconductor lasers (18) comprising the following steps: - Providing an epitaxial semiconductor layer sequence (1) comprising a plurality of epitaxial semiconductor layers (4, 4', 4'') arranged in a stacking direction (R s ) are stacked one above the other, wherein the epitaxial semiconductor layer sequence (1) comprises an active region (5) in which electromagnetic radiation is generated during operation, - producing one or more trenches (12) in the epitaxial semiconductor layer sequence (1), - producing vertical structures (15) in side surfaces (13) of the trenches (12) in the stacking direction (Rs), wherein the vertical structures (15) in the side surfaces (13) of the trenches ben (12) are recesses (11) which are formed by selective etching of at least one epitaxial semiconductor layer (4') starting from the side surfaces (13) of the trenches (12), and the recesses (11) are arranged between a waveguide layer (6, 7) of the epitaxial semiconductor layer stack (14) and a substrate (3) of the edge-emitting semiconductor laser (18) on a side of the waveguide layer (6, 7) facing away from the active zone (22).

13. The method according to claim 12, wherein an electrical voltage (U) is applied to the epitaxial semiconductor layer sequence (1) during the selective etching of the at least one epitaxial semiconductor layer (4').

14. Method according to one of claims 12 or 13, wherein during the selective etching partial regions of the epitaxial semiconductor layer sequence (1) are irradiated with electromagnetic radiation (UV).

15. A method for manufacturing a laser component comprising the following steps: - Providing a wafer assembly (2) with a plurality of edge-emitting semiconductor lasers (18), - Singulating the wafer assembly (2) into laser components separated from one another, comprising at least two edge-emitting semiconductor lasers (18), wherein the edge-emitting semiconductor lasers (18) have epitaxial semiconductor layer stacks (14) which are laterally delimited by facets (19) and comprise a plurality of epitaxial semiconductor layers (4, 4', 4'') arranged in a stacking direction (R s ) are stacked on top of each other, - generating vertical structures (15) in the facets (19) of the edge-emitting semiconductor lasers (18) in the sta- pel direction (Rs), wherein the vertical structures (15) in the facets (19) of the edge-emitting semiconductor lasers (18) are recesses (11) which are formed by selectively etching at least one epitaxial semiconductor layer (4') starting from the side surfaces (13) of the trenches (12), and the recesses (11) are arranged between a waveguide layer (6, 7) of the epitaxial semiconductor layer stack (14) and a substrate (3) of the edge-emitting semiconductor laser (18) on a side of the waveguide layer (6, 7) facing away from the active zone (22).