SEMICONDUCTOR LASER AND METHOD FOR PRODUCING A SEMICONDUCTOR LASER

Abstract

The invention relates to a semiconductor laser. The semiconductor laser comprises: a semiconductor layer sequence having a p-doped layer, an n-doped layer and an active region arranged between the p-doped layer and the n-doped layer for generating electromagnetic radiation; and an optical structure. The optical structure is arranged on the side of the active region facing away from the p-doped layer, and the optical structure has a refractive index that varies in a lateral direction for the electromagnetic radiation generated by the active region. The invention further relates to a method for producing a semiconductor laser.

Description

[0001] Description

[0002] SEMICONDUCTOR LASER AND METHOD FOR MANUFACTURING A SEMICONDUCTOR LASER

[0003] A semiconductor laser and a method for producing a semiconductor laser are specified.

[0004] One problem to be solved is to provide a semiconductor laser that can be operated efficiently. Furthermore, another problem to be solved is to provide a method by which such a semiconductor laser can be manufactured efficiently.

[0005] According to at least one embodiment of the semiconductor laser, the semiconductor laser is a surface-emitting semiconductor laser. The surface-emitting semiconductor laser can be, for example, a VCSEL (vertical-cavity surface-emitting laser) or a PCSEL (photonic crystal surface-emitting laser). Preferably, the semiconductor laser is a thin-film semiconductor laser. In other words, a growth substrate is partially or completely removed from the semiconductor laser. PCSELs, for example, have a large aperture.

[0006] According to at least one embodiment of the semiconductor laser, the semiconductor laser comprises a semiconductor layer sequence with a p-doped layer, an n-doped layer and an active region arranged between the p-doped layer and the n-doped layer for generating electromagnetic radiation. The electromagnetic radiation is, for example, radiation, in particular laser radiation in the visible range, in the UV range and / or in the IR range of the electromagnetic spectrum. The semiconductor layer sequence comprises, for example, a II IV compound semiconductor material. For example, the semiconductor layer sequence can comprise, comprise and / or consist of GaN and / or InGaN. The active region can, for example, have a pn junction and / or a quantum well structure.

[0007] The layers of the semiconductor layer sequence can each have a layer thickness. The layer thickness is preferably an extension, for example an average extension, of the layer along a stacking direction of the layers of the semiconductor layer sequence. The layers of the semiconductor layer sequence are, for example, arranged successively along a stacking direction. The layer thickness of the p-doped layer is, for example, 50 nm up to and including 500 nm, for example 150 nm up to and including 400 nm or, for example, 200 nm up to and including 300 nm. The n-doped layer can have a layer thickness of 30 nm up to and including 250 nm, in particular 50 nm up to and including 200 nm.

[0008] The layers of the semiconductor layer sequence can have a main extension plane. The main extension plane of a layer of the semiconductor layer sequence is preferably a plane which is perpendicular to the stacking direction of the semiconductor layer sequence. According to at least one embodiment, the semiconductor laser comprises an optical structure. The optical structure is designed, for example, to influence at least one degree of freedom of the electromagnetic radiation emitted by the active region. For example, at least one degree of freedom of the electromagnetic radiation can be influenced in a targeted manner. In other words, the electromagnetic radiation emitted by the semiconductor laser can be at least partially set and / or adapted, in particular specifically set and / or adapted, by means of the optical structure.

[0009] The at least one degree of freedom of the electromagnetic radiation is, for example, an emission wavelength and / or an emission direction of the semiconductor laser. For example, the optical structure can form a wavelength filter.

[0010] The optical structure can in particular be arranged close to the active region. This can be particularly advantageous for a semiconductor laser which is formed by or comprises a PCSEL. For example, the optical structure is arranged in the immediate vicinity of the active region. Close can mean that a distance between the optical structure and the active region is less than or equal to 2 times the layer thickness of the n-doped layer. For example, the distance is a maximum of 1.5 times, 1 time, half or a quarter of the layer thickness of the n-doped layer. The distance is in particular a distance between the active region and the point on the optical structure which is closest to the active region. The optical structure is, for example, a periodically varying structure.For example, the optical structure has a periodically varying refractive index.

[0011] The optical structure can be one-dimensional, two-dimensional, or three-dimensional. This means that the refractive index can vary, for example, periodically, in one lateral direction or two orthogonal lateral directions or two orthogonal lateral directions and one direction perpendicular to the main plane of extension of the active region.

[0012] The optical structure can have a fill factor. For example, the optical structure is formed by structuring a layer. For example, recesses, in particular at least one recess, are produced in the layer, for example in the n-doped layer. For example, a material which, for example, has a higher or a lower refractive index than the layer can be arranged in the recesses. For example, the recesses in the layer, for example the n-doped layer, are completely filled with the material. The recesses are filled, for example, with SiCt, air and / or ITO. The recesses can also be referred to, for example, as holes in the photonic crystal (PC holes) or as a cell. The fill factor of the optical structure can then be, in particular, the proportion of the recesses in the n-doped layer.For example, the fill factor is the area proportion of the recesses on the surface of the n-doped layer along the main extension plane of the n-doped layer. The recesses have, for example, an extension in a direction parallel to the main extension plane of the semiconductor layer sequence. For example, a diameter or a lateral extension along a direction parallel to the main extension plane of a recess or of all recesses of the optical structure each corresponds at most to the wavelength of the electromagnetic radiation generated by the active region. In particular, a diameter of a recess is at most or at least approximately half the wavelength of the electromagnetic radiation generated by the active region.

[0013] The recesses have, for example, a depth. The depth of the recesses is, in particular, an extension of the recess in a direction perpendicular to the main extension plane of the semiconductor layer sequence. The depth of a recess preferably corresponds to the maximum depth of the corresponding recess.

[0014] It is possible that the recesses or PC holes do not extend completely through the n-doped layer.

[0015] The optical structure can have a thickness . The thickness of the optical structure is, for example, an extension of the optical structure along a direction which runs perpendicular to a main extension plane of the semiconductor layer sequence or of the n-doped layer . For example, the thickness of the optical structure in the case of a one-dimensional or two-dimensional optical structure results from the extension of the recesses along a direction perpendicular to the main extension plane of the n-doped layer or from the depth of the recesses . According to at least one embodiment of the semiconductor laser, the optical structure is arranged on the side of the active region facing away from the p-doped layer . For example, the n-doped layer comprises the optical structure . Alternatively or additionally, the optical structure can partially comprise the n-doped layer .The optical structure can then be partially, in particular only partially, formed by the n-doped layer. Alternatively or additionally, the optical structure can be arranged on the side of the n-doped layer facing away from the active region. For example, the optical structure is flush or almost flush with the n-doped layer in a direction perpendicular to a main extension plane of the active region. Alternatively or additionally, the n-doped layer can be arranged on the side of the optical structure facing away from the active region.

[0016] The optical structure can be arranged in the n-doped layer and / or border, in particular directly border, the side of the n-doped layer facing away from the active region.

[0017] It is possible that the n-doped layer is at least partially located between the active region and the optical structure. This may mean that the n-doped layer is completely located between the active region and the optical structure.

[0018] The n-doped layer can be formed in multiple layers. The optical structure can then be arranged on the side of the multilayer n-doped layer facing away from the active region. This can mean, in particular, that the optical structure is not arranged between two n-doped layers formed at a distance from one another. For example, the optical structure is not followed by an n-doped layer on its side facing away from the active region, for example, no further n-doped layer follows it.

[0019] According to at least one embodiment of the semiconductor laser, the optical structure has a refractive index that varies in a lateral direction for the electromagnetic radiation generated by the active region. The lateral direction is, in particular, a direction that runs parallel to a main extension plane of the semiconductor layer sequence, for example, parallel to the main extension plane of the active region.

[0020] In particular, the variation of the refractive index of the optical structure for the electromagnetic radiation generated by the active region is not random. In other words, the refractive index of the optical structure, which varies in a lateral direction, can be deliberately designed.

[0021] For example, the optical structure comprises at least two regions with different refractive indices. In particular, the optical structure can have more than two regions, for example a plurality of regions with different refractive indices. The refractive indices of the at least two regions can differ in pairs. For example, the at least two regions with pairwise different refractive indices are arranged alternately, in particular alternately along the lateral direction. Alternatively or additionally, the optical structure can have regions with different refractive indices along a direction that runs perpendicular to the lateral direction.

[0022] A region of the optical structure is preferably formed by the layer which is structured to produce the optical structure.

[0023] According to at least one embodiment of the semiconductor laser, the semiconductor laser comprises a semiconductor layer sequence with a p-doped layer, an n-doped layer and an active region arranged between the p-doped layer and the n-doped layer for generating electromagnetic radiation, and an optical structure, wherein the optical structure is arranged on the side of the active region facing away from the p-doped layer, and the optical structure has a refractive index varying in a lateral direction for the electromagnetic radiation generated by the active region.

[0024] One idea of ​​the semiconductor laser described here is, among other things, to provide a semiconductor laser in which the optical structure is arranged on the n-doped side. In particular, the semiconductor laser described here can thus have particularly few defects because, for example, the optical structure is only structured after the semiconductor layer sequence has been grown. In a thin-film semiconductor laser, the growth substrate is partially or completely removed. This makes the n-doped layer accessible. The optical structure can thus be subsequently structured efficiently close to the active region.

[0025] By subsequently structuring the optical structure, the optical structure does not influence the formation of the active region, since the active region was created before the optical structure was formed. In other words, overgrowth of the optical structure is advantageously not necessary with the semiconductor laser described here. The active region can thus have particularly few defects and damage, or be free or almost free of defects.

[0026] According to at least one embodiment, the optical structure comprises a photonic crystal. The optical structure can, in particular, comprise and / or consist of a photonic crystal. The optical structure is, for example, a one-dimensional (1D), two-dimensional (2D), or three-dimensional (3D) photonic crystal.

[0027] According to at least one embodiment of the semiconductor laser, a high-refractive index layer is arranged on the side of the n-doped layer facing away from the active region, wherein a refractive index of the high-refractive index layer is at least 1.7. For example, the refractive index of the high-refractive index layer is greater than or equal to 1.8, greater than or equal to 1.9, or greater than or equal to 2. For example, the refractive index of the high-refractive index layer is greater than an average refractive index of the semiconductor layer sequence. In particular, the refractive index of the high-refractive index layer is greater than a refractive index of the n-doped layer. The high-refractive index layer can have a layer thickness of at least 10 nm, for example at least 200 nm, in particular at least 300 nm. The high-refractive index layer pushes the mode towards the n-doped layer. An overlap of the mode with the optical structure can thus be increased.

[0028] According to at least one embodiment, the high-refractive-index layer is permeable to the electromagnetic radiation generated by the active region. Alternatively or additionally, the high-refractive-index layer can be permeable to the electromagnetic radiation influenced by the optical structure. The fact that the high-refractive-index layer is permeable to electromagnetic radiation can mean that the high-refractive-index layer is at least translucent, in particular transparent, to the electromagnetic radiation.

[0029] The high-refractive-index layer can have a transmission coefficient. Preferably, the transmission coefficient is greater than zero. In other words, the electromagnetic radiation can be at least partially transmitted through the high-refractive-index layer. The electromagnetic radiation can thus be efficiently coupled out of the semiconductor laser.

[0030] According to at least one embodiment of the semiconductor laser, an electrically conductive layer is arranged between the high-refractive-index layer and the n-doped layer, wherein the electrically conductive layer is configured to electrically contact the n-doped layer.

[0031] The electrically conductive layer comprises, for example, a transparent conductive oxide (TCO), for example indium tin oxide, or ITO for short. For example, the electrically conductive layer directly borders the high-refractive-index layer and / or the n-doped layer. In other words, the electrically conductive layer can be arranged directly between the high-refractive-index layer and the n-doped layer. The electrically conductive layer preferably borders the n-doped layer and / or the optical structure over its entire area. The electrically conductive layer can be designed to spread the current and to impress current into the semiconductor layer sequence. For example, the electrically conductive layer is designed to make electrical contact with the semiconductor layer sequence, in particular the n-doped layer and / or the optical structure.A layer thickness of the electrically conductive layer is, for example, at most 10 nm, in particular at most 50 nm.

[0032] According to at least one embodiment of the semiconductor laser, a further electrically conductive layer is arranged on the side of the high-refractive-index layer facing away from the active region, and the high-refractive-index layer has at least one via.

[0033] The at least one via preferably extends from the further electrically conductive layer to the electrically conductive layer or vice versa. The at least one via extends, for example, through the high-refractive-index layer. In particular, the at least one via can extend completely through the high-refractive-index layer. The electrically conductive layer can be connected to the further electrically conductive layer via the at least one via.

[0034] The layer can be electrically connected. For example, the further electrically conductive layer is designed as a contact layer. The electrically conductive layer is then designed, for example, as a current distribution layer or current spreading layer.

[0035] The at least one via can be channel-shaped or linear. Channel-shaped here can mean that a lateral extent of the via in a mutually perpendicular direction is equal or at least approximately equal. Linear can mean that the lateral extent of the via along one of the mutually perpendicular directions is greater, for example a multiple, than the lateral extent of the via along the direction perpendicular to this direction.

[0036] If the via is required merely as an electrically conductive connection from one electrically conductive layer to another, the via can be simply arranged and created in the high-refractive-index layer. The via then does not need to be positioned precisely, for example, it can be positioned exactly at the recesses of the optical structure. Preferably, the via is positioned such that absorption of the electromagnetic radiation generated by the active region at the via is minimized.

[0037] The via has, for example, an extension in a direction parallel to the main extension plane of the semiconductor layer sequence . The extension of the via can be the diameter of the via. The extension of the via is, for example, at least approximately a maximum of half the wavelength of the electromagnetic radiation generated by the active region . For example, a diameter of the via corresponds at least approximately to the diameter of a recess in the optical structure . Alternatively, in particular if the vias are only designed to make electrical contact with the semiconductor layer sequence, the diameter or the lateral extension of the via can be greater than the wavelength of the electromagnetic radiation generated by the active region .

[0038] According to at least one embodiment of the semiconductor laser, the semiconductor laser comprises at least one further via. The at least one further via can be arranged at a distance from the at least one via. For example, the at least one further via runs parallel to the at least one via. Alternatively, the at least one further via can run perpendicular to the at least one via. For example, the at least one further via and the at least one via are in direct contact in places. For example, the vias are designed in a grid shape. The at least one further via can have the same properties or at least partially the same properties as the at least one via.By at least two vias in the high-refractive-index layer, current distribution in the electrically conductive layer can be improved.

[0039] According to at least one embodiment of the semiconductor laser, the semiconductor laser comprises at least one further via, and the at least one via and the at least one further via are designed to at least partially extend the optical structure. The at least one via preferably has a lower refractive index than the high-refractive-index layer. For example, the at least one via overlaps with a PC hole in a lateral direction. In particular, the at least one via can completely overlap with a PC hole. A lateral extent of the at least one via can, for example, at least approximately correspond to a lateral extent of the PC hole. The optical structure then, for example, at least partially comprises the at least one via and / or the high-refractive-index layer.For example, by means of the at least one via, the optical structure is formed as a double grating structure.

[0040] According to at least one embodiment of the semiconductor laser, the high-refractive index layer comprises niobium oxide (NbO), titanium oxide (TiO) and / or gallium nitride (GaN). A refractive index of the high-refractive index layer or an average refractive index of the high-refractive index layer is preferably greater than an average refractive index of the semiconductor layer sequence. According to at least one embodiment of the semiconductor laser, the high-refractive index layer has a thickness of at least 150 nm. For example, the layer thickness of the high-refractive index layer is at least 200 nm. By means of a high-refractive index layer which is at least 150 nm thick, the mode profile can be efficiently pushed or shifted towards the n-doped side. This improves the overlap of the mode profile of the electromagnetic radiation with the optical structure.

[0041] According to at least one embodiment of the semiconductor laser, a low-refractive-index layer is arranged on the side of the p-doped layer facing away from the active region, wherein a refractive index of the low-refractive-index layer is smaller than an average refractive index of the semiconductor layer sequence.

[0042] The low-refractive-index layer comprises, for example, an ITO layer and / or a Bragg mirror. The low-refractive-index layer can have a low-refractive-index layer stack and / or, alternatively or in addition to the ITO layer and / or the Bragg mirror, comprise further layers and / or layer stacks.

[0043] The low-refractive index layer has, for example, a refractive index, for example an average refractive index, which is smaller than a refractive index, for example an average refractive index, of the semiconductor layer sequence. Alternatively, the refractive index of the low-refractive index layer can be equal to an average refractive index of the semiconductor layer sequence. By arranging a low-refractive index layer on the side of the semiconductor layer sequence on which the p-doped layer is arranged, a mode profile of the electromagnetic radiation can be pushed or shifted further towards the n-doped side. This improves the overlap of the mode profile of the electromagnetic radiation with the optical structure. Improved can in particular mean that the overlap is increased and / or maximized.

[0044] According to at least one embodiment of the semiconductor laser, a metal reflector is arranged on the side of the p-doped layer facing away from the active layer. For example, the metal reflector is arranged on the side of the low-refractive-index layer facing away from the p-doped layer. Alternatively, the metal reflector can be directly adjacent to the p-doped layer.

[0045] According to at least one embodiment of the semiconductor laser, the sum of the layer thicknesses of the p-doped layer, the low-refractive-index layer, and / or the metal reflector is at least 10 μm. For example, the sum of the layer thicknesses corresponds at least to the wavelength of the electromagnetic radiation emitted by the active region; in particular, the sum of the layer thicknesses corresponds to a multiple of the wavelength. For example, the sum of the layer thicknesses is less than three times the wavelength of the electromagnetic radiation emitted by the active region. This can improve resonance in the semiconductor laser.

[0046] According to at least one embodiment of the semiconductor laser, the semiconductor laser has a contact, the contact comprises an opening, and at least one conductive connection is arranged in the opening.

[0047] The contact is configured, for example, for electrically contacting the semiconductor layer sequence, in particular the p-doped layer or the n-doped layer. The contact comprises, for example, an electrically conductive material, such as a metal.

[0048] The contact opening is, for example, circular, rectangular, free-form, nearly circular, or nearly rectangular. The contact opening is, in particular, arranged such that the optical structure is not covered or largely not covered by the contact. In other words, the contact opening is arranged, for example, on the optical structure and / or the n-doped layer or the p-doped layer.

[0049] The optical structure and / or n-doped layer or p-doped layer arranged thereon is freely accessible through the opening. The optical structure and / or the n-doped layer or the p-doped layer is thus free of the contact material, particularly in the area of ​​the opening.

[0050] The contact can comprise at least one conductive connection. The at least one conductive connection of the contact can be arranged in the opening of the contact. For example, at least two conductive connections or a plurality of conductive connections are arranged in the opening of the contact. The at least one conductive connection of the contact extends, for example, from the contact into the opening of the contact. For example, the at least one conductive connection extends completely over the opening. The, for example, at least two conductive connections can run parallel to one another, for example. The at least one conductive connection can be designed as a metal line and / or wire. The at least one conductive connection is set up, for example, to impress current into the semiconductor layer sequence.

[0051] The at least one conductive connection in the contact opening improves current distribution in the layer adjacent to the contact. In the area of ​​the opening, electromagnetic radiation generated and emitted by the semiconductor laser can be coupled out of the semiconductor laser particularly efficiently.

[0052] According to at least one embodiment of the semiconductor laser, the active region emits polarized electromagnetic radiation during operation, and the at least one conductive connection of the contact runs perpendicular to the polarization of the polarized electromagnetic radiation emitted by the active region. In particular, the at least one conductive connection runs perpendicular to the transverse electric field (TE field). The at least one conductive connection of the contact is then transparent or approximately transparent to the electromagnetic radiation emitted by the semiconductor laser. This allows the electromagnetic radiation to be efficiently coupled out of the semiconductor laser.

[0053] According to at least one embodiment of the semiconductor laser, the n-doped layer has a layer thickness of at least 300 nm. The n-doped layer has, for example, a particularly high layer thickness. The layer thickness of the n-doped layer can be, for example, at least 350 nm, for example at least 400 nm. The n-doped layer can be highly doped. For example, the n-doping of the n-doped layer is greater than or equal to 2 * 10 18 1 / cm 3 .

[0054] An advantage of this embodiment is that the particularly large layer thickness of the n-doped layer increases the overlap of the mode of the electromagnetic radiation generated by the active region with the optical structure or the photonic crystal.

[0055] According to at least one embodiment, the fill factor of the optical structure is at most 30%, for example at most 20%, in particular at most 15% or, for example, at most 10%. This, for example, increases the contact area in which the electrically conductive layer is in direct contact with the n-doped layer, and improves the current injection into the n-doped layer.

[0056] According to at least one embodiment, the semiconductor laser comprises a cover and / or an anti-reflection coating.

[0057] The cover is arranged, for example, on the optical structure. In particular, the cover can be arranged on the side of the contact facing away from the optical structure. The cover can partially or completely cover the opening of the contact. The cover is, for example, permeable, in particular transparent, to the electromagnetic radiation generated and / or emitted by the active region and / or the optical structure. For example, the cover comprises glass or is formed from glass. The cover can be connected to the contact by soldering, gluing and / or metal-to-metal bonding.

[0058] For example, the cover has an anti-

[0059] Reflective coating (AR coating). In particular, the cover has an AR coating on the side facing the semiconductor layer sequence and / or on the side facing away from the semiconductor layer sequence. The AR coating can in particular completely cover the corresponding side. Alternatively or additionally, the n-doped layer can have an AR coating. For example, the AR coating is applied to the n-doped layer. In particular, the AR coating can be arranged directly on the side of the n-doped layer facing away from the active region.

[0060] According to at least one embodiment, a carrier is arranged on the side of the p-doped layer facing away from the active region. The carrier is, for example, the mechanically supporting component of the semiconductor laser.

[0061] Furthermore, a method for producing a semiconductor laser is specified. The semiconductor laser described here can preferably be produced using a method for producing a semiconductor laser described here. In other words, all features disclosed for the method for producing a semiconductor laser are also disclosed for the semiconductor laser, and vice versa.

[0062] According to at least one embodiment of the method for producing a semiconductor laser, the method comprises growing a semiconductor layer sequence on a growth substrate. For example, an n-doped layer of the semiconductor layer sequence is grown on the growth substrate before a p-doped layer of the semiconductor layer sequence.

[0063] The growth substrate comprises, for example, GaN, Si and / or sapphire. In addition, the growth substrate can comprise further layers, which for example have InAlGaN. This makes it possible to achieve a low defect density. This means that the semiconductor layers of the semiconductor layer sequence can be grown on the growth substrate with as few defects as possible. For example, the growth substrate comprises a release layer. After the semiconductor layer sequence has been grown on the growth substrate, the growth substrate can be removed. For example, the growth substrate is removed using the release layer. The growth substrate is detached from the semiconductor layer sequence, for example by means of laser lift-off.

[0064] By removing the growth substrate, the n-doped layer is then easily accessible. The optical structure can then be subsequently and easily created in the n-doped layer.

[0065] According to at least one embodiment of the method for producing a semiconductor laser, the method comprises providing a layer sequence comprising a semiconductor layer sequence with a p-doped layer, an n-doped layer, and an active region arranged between the p-doped layer and the n-doped layer for generating electromagnetic radiation on a carrier. The carrier is preferably arranged on the side of the p-doped layer facing away from the active region.

[0066] According to at least one embodiment of the method for producing a semiconductor laser, the method comprises providing a further carrier with a further layer sequence arranged on the further carrier. The further layer sequence has at least one layer. The at least one layer of the further layer sequence comprises, for example, a transparent conductive oxide, for example ITO, a high-refractive dielectric, gallium nitride, in particular n-doped gallium nitride and / or a material with no or low absorption, for example silicon dioxide (SiO2). The further carrier has, for example, sapphire or is formed therefrom.

[0067] According to at least one embodiment of the method for producing a semiconductor laser, the method comprises producing an optical structure, wherein the optical structure has a refractive index that varies in the lateral direction for the electromagnetic radiation generated by the active region. For example, the optical structure is a photonic crystal or the optical structure has a photonic crystal. Producing the optical structure comprises, for example, structuring a layer, for example the n-doped layer and / or an electrically conductive layer. Structuring the layer comprises, for example, partially removing the layer. Regions in which the layer is removed can have a refractive index that is different from the refractive index of the layer.According to at least one embodiment of the method for producing a semiconductor laser, the method comprises connecting the layer sequence to the further layer sequence. Preferably, the layer sequence is connected on the side facing away from the carrier to the side of the further layer sequence that faces away from the further carrier. Particularly in the case of air- and / or gas-filled PC holes, the layer sequences are connected to one another, for example, in a vacuum and / or in a defined atmosphere. The defined atmosphere can, for example, comprise a specific gas.

[0068] According to at least one embodiment of the method for producing a semiconductor laser, the method comprises the following steps:

[0069] - Providing a layer sequence comprising a semiconductor layer sequence with a p-doped layer, an n-doped layer and an active region arranged between the p-doped layer and the n-doped layer for generating electromagnetic radiation on a carrier,

[0070] - Providing a further carrier with a further layer sequence arranged on the further carrier,

[0071] - producing an optical structure, wherein the optical structure has a refractive index varying in the lateral direction for the electromagnetic radiation generated by the active region, and

[0072] - Connecting the layer sequence with the further layer sequence.

[0073] For example, the steps listed are carried out in the specified order. According to at least one embodiment of the method for producing a semiconductor laser, the optical structure is produced in the layer sequence and / or in the further layer sequence before the layer sequence is connected to the further layer sequence. The further layer sequence can comprise the electrically conductive layer. ITO can be processed in a simplified manner by means of plasma etching. The optical structure can thus be produced in a simplified and reproducible manner. If the optical structure is produced in the ITO layer, absorption in the ITO is reduced because the ITO is partially removed.

[0074] According to at least one embodiment of the method for producing a semiconductor laser, the optical structure is created in the layer sequence, and after the layer sequence is connected to the further layer sequence, the optical structure is at least partially delimited by the further layer sequence. This can mean that the further layer sequence at least partially directly borders the optical structure, in particular directly borders at least one PC hole of the optical structure.

[0075] According to at least one embodiment of the method for producing a semiconductor laser, after the layer sequence has been connected to the further layer sequence, at least one via is produced in the further layer sequence.

[0076] According to at least one embodiment of the method for producing a semiconductor laser, the additional carrier is removed after the layer sequence has been bonded to the additional layer sequence. The additional carrier is removed, for example, by means of laser lift-offs. The semiconductor laser described here and the method for producing a semiconductor laser described here are explained in more detail below in conjunction with exemplary embodiments and the associated figures.

[0077] Figure 1 shows a semiconductor layer sequence on a growth substrate.

[0078] Figures 2 to 5 show the semiconductor layer sequence shown in Figure 1 with additional layers arranged on the p-doped layer according to various embodiments.

[0079] Figures 6 and 8 show cross sections through a semiconductor laser according to embodiments.

[0080] Figure 7 shows a plan view of a semiconductor laser according to an embodiment.

[0081] Figures 9 to 13 show cross sections through semiconductor lasers according to embodiments in which the optical structure is arranged in the n-doped layer.

[0082] Figure 14 shows a plan view of a semiconductor laser according to an embodiment.

[0083] Figures 15 and 16 show sectional views through the high-refractive-index layer according to embodiments.

[0084] Figures 17 and 18 show cross sections of further

[0085] Embodiments of a semiconductor laser. Figures 19 and 20 show steps in a method for manufacturing a semiconductor laser according to an embodiment.

[0086] Figures 21 and 22 show steps in a method for manufacturing a semiconductor laser according to a further embodiment.

[0087] Figures 23 and 24 show steps in a method for manufacturing a semiconductor laser according to a further embodiment.

[0088] Figures 25 and 26 show steps in a method for manufacturing a semiconductor laser according to a further embodiment.

[0089] Figures 27 and 28 show steps in a method for manufacturing a semiconductor laser according to a further embodiment.

[0090] Figures 29, 30, 31, 32 and 33 show steps in a method for producing a semiconductor laser according to a further embodiment.

[0091] Figures 34, 35, 36, 37 and 38 show semiconductor lasers according to further embodiments.

[0092] Figure 39 shows a plan view of a semiconductor laser according to an embodiment.

[0093] Figure 40 shows a method step in a method for producing a semiconductor laser according to another embodiment. Figure 41 shows a plan view of a semiconductor laser according to an embodiment.

[0094] 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.

[0095] Figure 1 shows a semiconductor layer sequence 2 grown on a substrate 20, comprising an n-doped layer 4, a p-doped layer 3 and an active region 5 arranged between the n-doped layer 4 and the p-doped layer 3, according to one exemplary embodiment. The semiconductor layer sequence 2 can at least partially form a semiconductor laser 1. The n-doped layer 4 of the semiconductor layer sequence 2 faces the growth substrate 20. This can mean that the n-doped layer 4 is grown on the growth substrate 20 first. A release layer 21 is arranged between the n-doped layer 4 and the growth substrate 20. Alternatively, the growth substrate 20 can have or comprise a release layer 21. The release layer 21 is then preferably arranged on or at the side of the growth substrate 20 facing the semiconductor layer sequence 2.By means of the release layer 21, the growth substrate 20 can be released from the semiconductor layer sequence 2, for example.

[0096] Figures 2 to 5 show the system shown in Figure 1

[0097] Growth substrate 20 with semiconductor layer sequence 2 grown thereon in further embodiments, wherein Figures 2 to 5 differ from Figure 1 in that additional layers are arranged on the p-doped layer.

[0098] In Figures 2, 3, and 4, a low-refractive-index layer 10 is arranged on the side of the semiconductor layer sequence 2 facing away from the growth substrate 20. The low-refractive-index layer 10 is applied to the semiconductor layer sequence 2, for example, after the semiconductor layer sequence 2 has been grown on the growth substrate 20. A metal reflector 23 is arranged on the side of the low-refractive-index layer 10 facing away from the semiconductor layer sequence 2. The metal reflector 23 can be directly adjacent to the low-refractive-index layer 10.

[0099] In the exemplary embodiment of Figure 2, the low-refractive-index layer 10 comprises an ITO layer 10a and a Bragg mirror 10b. The low-refractive-index layer 10 has, for example, a refractive index, for example, an average refractive index, which is smaller than a refractive index, for example, an average refractive index, of the semiconductor layer sequence 2.

[0100] Alternatively, as shown in the embodiment of Figure 3, the low-refractive-index layer 10 may comprise and / or consist of only the ITO layer 10a.

[0101] In the embodiment illustrated in Figure 4, the low-refractive-index layer 10 comprises exclusively a Bragg mirror 10b. Alternatively, not shown, the low-refractive-index layer 10 may comprise further layers and / or layer stacks. Figure 5 shows an embodiment in which the metal reflector 23 directly adjoins the semiconductor layer sequence 2 and, in particular, directly adjoins the p-doped layer 3.

[0102] Figure 6 shows a semiconductor laser 1 according to an embodiment. The structure of the semiconductor laser 1 essentially corresponds to the structure shown in Figure 3. In contrast, the n-doped layer 4 of the semiconductor layer sequence 2 has, for example, a great layer thickness. The layer thickness of the n-doped layer 4 is, for example, at least 300 nm. On the side of the n-doped layer 4 facing away from the active region 5, a contact 13 shown in Figure 7 is arranged, for example. The recesses or PC holes 26, 27 have, for example, a great depth. For example, the recesses or PC holes 26, 27 have a depth in the range from 20 nm up to and including 150 nm. A carrier is arranged on the side of the metal reflector 23 facing away from the semiconductor layer sequence 2.

[0103] Figure 7 shows a plan view of a semiconductor laser 1 according to an embodiment. The semiconductor laser 1 has a contact 13. The contact 13 can be arranged on the side of the n-doped layer 4 facing away from the active region 5. For example, the contact 13 is arranged on the optical structure 6. The fact that the contact 13 is arranged on the n-doped layer 4 and / or on the optical structure 6 can mean that the contact 13 is at least partially, in particular completely, in direct contact with the n-doped layer 4 and / or the optical structure 6. In particular, the contact 13 can be electrically conductively connected to the n-doped layer 4 and / or the optical structure 6.

[0104] The contact 13 has an opening 14. The opening 14 can be completely surrounded laterally by the material of the contact 13. In particular, the opening 14 is at least partially free of the material of the contact 13. At least one conductive connection 15 is arranged in the opening 14. For example, at least two conductive connections 15 or a plurality of conductive connections 15 are arranged in the opening 14. The conductive connections 15 extend, for example, from the contact 13 into the opening 14. For example, the at least one conductive connection 15 extends completely over the opening 14. The at least one conductive connection 15 can be designed as a wire. In the exemplary embodiment shown here, a plurality of conductive connections 15 run over the opening 14. The conductive connections 15 are spaced apart from one another.For example, the conductive connections 15 are arranged in pairs spaced apart from one another. The conductive connections 15 run parallel or nearly parallel to one another. Alternatively, not shown, the conductive connections 15 can run obliquely to one another and / or at least partially directly touch one another. Preferably, the at least one conductive connection 15 runs perpendicular to a polarization of the polarized electromagnetic radiation emitted by the active region 5 of the semiconductor laser 1.

[0105] Figure 8 shows a semiconductor laser 1 according to an embodiment. The semiconductor laser 1 of Figure 8 differs from the semiconductor laser 1 shown in Figure 6 in that a cover 24 is arranged on the optical structure 6. The cover 24 is arranged, for example, on the side of the contact 13 facing away from the optical structure 6. In other words, the cover 24 is at least partially applied to the contact 13. In particular, the cover 24 covers the opening 14 of the contact 13 at least partially or, for example, completely. The cover 24 has, for example, an AR coating. The cover 24 is, for example, permeable, in particular transparent, to the electromagnetic radiation generated and / or emitted by the active region 5 and / or by the optical structure 6. For example, the cover 24 has glass or is formed therefrom.The cover 24 is connected to the contact, for example, by means of soldering, gluing and / or metal-to-metal bonding.

[0106] Figures 9 to 13 show exemplary embodiments of a semiconductor laser 1 in which the optical structure 6 is arranged in the n-doped layer 4 and in which a high-refractive-index layer 7 is arranged on the side of the n-doped layer 4 facing away from the active region 5.

[0107] Figure 9 shows a semiconductor laser 1 in which an electrically conductive layer 8, a high-refractive-index layer 7, and a further electrically conductive layer 9 are arranged on the optical structure 6. At least one via 11 extends through the high-refractive-index layer. The at least one via 11 preferably extends from the further electrically conductive layer 9 to the electrically conductive layer 8. In the exemplary embodiment chosen here, the via 11 is not, for example, adapted to the optical structure 6.

[0108] The embodiment shown in Figure 10 differs from the embodiment shown in Figure 9 in that the high-refractive-index layer 7 has a via 11 and at least one further via 12. The via 11 and / or the at least one further via 12 can be designed as a vertically running channel, for example in the shape of a channel. Vertical here means in particular that the channel runs perpendicular or almost perpendicular to a main extension plane of the high-refractive-index layer 7. The via 11 and the at least one further via 12 electrically connect the electrically conductive layer 8 and the further electrically conductive layer 9 to one another. Figure 10 shows a schematic mode profile M. The mode M overlaps with the optical structure 6.For example, the via 11 and / or the at least one further via 12 overlaps with a PC hole 26, 27 in a lateral direction. In particular, the at least one via 11 and / or the at least one further via 12 can completely overlap with a PC hole 26, 27. A lateral extent of the via 11, 12 can, for example, at least approximately correspond to a lateral extent of the PC hole 26, 27.

[0109] The semiconductor laser 1 of Figure 11 differs from the embodiment shown in Figure 10 in that the via 11 and the at least one further via 12 do not extend each PC cell. For example, the optical structure is formed as a double grating structure by means of the vias 11, 12.

[0110] Figures 12 and 13 show further embodiments of a semiconductor laser 1 which differ from the semiconductor laser 1 shown in Figure 11 in that the distance between the via 11 and the further via 12 is greater. The distance between the vias can be greater than a lattice constant of the optical structure 6. For example, the distance between the vias 11, 12 is a multiple of the distances between regions with different refractive indices in the optical structure 6. A sum of the layer thicknesses L of the p-doped layer 3, the low-refractive-index layer 10 and / or the metal reflector 23 is, for example, at least 10 μm.

[0111] In the exemplary embodiment of Figure 13, the vias 11, 12 are arranged such that the optical structure 6 has no recesses or PC holes 26, 27 in the region of the vias 11, 12. Current injection from the electrically conductive layer 8 into the n-doped layer 4 is thus improved.

[0112] Figure 14 shows a plan view of a semiconductor laser 1 according to an embodiment. The semiconductor laser 1 has a contact 13 described in connection with Figure 7. In the embodiment of Figure 14, the contact 13 is applied to the further electrically conductive layer 9 of a semiconductor laser 1 shown, for example, in Figures 9 to 13. Figures 15 and 16 show sectional views through the high-refractive index layer 7 according to embodiments. In the embodiment shown in Figure 15, the through-contacts 11, 12 are lattice-shaped. In the embodiment of Figure 16, the through-contacts 11, 12 are linear.

[0113] Figures 17 and 18 show further embodiments of a semiconductor laser. The optical structure 6 is formed in the electrically conductive layer 8. This can mean, in particular, that the optical structure 6 is at least partially, in particular partially, formed by the electrically conductive layer 8 and / or comprises the electrically conductive layer 8. The electrically conductive layer 8 comprises, for example, ITO.

[0114] The semiconductor laser 1 of Figure 18 differs from the semiconductor laser 1 shown in Figure 17 in that the semiconductor laser 1 has at least one further via. In particular, as shown here, the number of vias 11, 12 corresponds at least approximately to the number of cells of the optical structure 6. The vias 11, 12 have a refractive index that is smaller than a refractive index of the high-index layer 7. In other words, the optical structure 6 is at least partially extended by the vias 11, 12.

[0115] Figures 19 and 20 show steps in a method for producing a semiconductor laser 1 according to an embodiment.

[0116] 19, for example, a semiconductor layer sequence 2 was grown on a substrate 20. For example, the semiconductor layer sequence 2 was subsequently applied to a carrier and then the substrate 20 was removed. The substrate 20 was removed, for example, using a removal layer 21 arranged between the substrate 20 and the semiconductor layer sequence 2. An optical structure 6 was produced in the n-doped layer 4. For example, as shown here, before the optical structure 6 was produced, part of the electrically conductive layer 8 was applied to the n-doped layer 4. The optical structure 6 can then, for example, also be produced in the n-doped layer and in the electrically conductive layer 8. For example, before the process step shown in FIG. 19, a further electrically conductive layer 9 was grown on a further carrier 18.Subsequently, a high-refractive-index layer 7 can be applied to the further electrically conductive layer 9. In particular, at least one via 11 was created in the high-refractive-index layer 7 and then at least a part of the electrically conductive layer 8 was applied to the high-refractive-index layer 7. For the at least one via 11, for example, a hole or a channel was created which extends through the high-refractive-index layer 7. The hole or the channel can, for example, be filled with electrically conductive material before the electrically conductive layer 8 is applied to the high-refractive-index layer 7. Alternatively, the hole or the channel can be filled in the step in which the electrically conductive layer 8 is applied. In the method step in Figure 19, the carrier 17 with the layer sequence 16 and the further carrier 18 with the further layer sequence 19 are provided.Figure 20 shows a finished semiconductor laser 1 according to an exemplary embodiment. Between the method step shown in Figure 19 and the finished semiconductor laser 1 of Figure 20, the further layer sequence 19 is connected to the layer sequence 16. In particular, the further layer sequence 19 then borders the side of the layer sequence 16 on which the n-doped layer 4 is arranged. The further carrier 18 is subsequently removed.

[0117] Figures 21 and 22 show steps in a method for producing a semiconductor laser 1 according to a further embodiment. In contrast to the method step shown in Figure 19, the layer on the further carrier

[0118] 18 provided further layer sequence 19 no vias 11 , 12 on . The further layer sequence

[0119] 19 comprises, shown here, an electrically conductive layer 8 and a high-refractive-index layer 7.

[0120] Figure 22 shows a position in the method for manufacturing the semiconductor laser 1 according to an exemplary embodiment. The further layer sequence 19 is connected to the layer sequence 16. The further carrier 18 is removed after the layer sequences 16, 19 have been connected.

[0121] Following the process stage shown in Figure 22, at least one through-connection 11 is produced. The at least one through-connection 11 is produced, for example, from the side of the further layer sequence 19 facing away from the layer sequence 16. A further electrically conductive layer 9 is applied to the side of the layer sequence 19 facing away from the layer sequence 16, preferably to the high-index layer 7. In the process step shown in Figure 23 according to an exemplary embodiment, a layer sequence 16 is provided on a carrier 17 and a further layer sequence 19 is provided on a further carrier 18. The layer sequence 16 differs from the layer sequence 16 shown in Figure 21 in that the layer sequence 16 does not comprise an electrically conductive layer 8. The n-doped layer 4 thus at least partially forms the outer surface of the layer sequence 16 facing away from the carrier 17.The further layer sequence 19 comprises an n-doped layer 4 and / or is formed therefrom.

[0122] Figure 24 shows a semiconductor laser 1 manufactured using the process step shown in Figure 23. The n-doped layer 4 of the further layer sequence 19 is connected to the n-doped layer 4 of the layer sequence 16.

[0123] Figures 25 and 26 show steps in a method for producing a semiconductor laser according to a further exemplary embodiment. The method shown here essentially corresponds to the method described in connection with Figures 23 and 24. The methods and the semiconductor lasers 1 differ in that the optical structure 6 of Figures 25 and 26 is an inverse optical structure 6. This means that a refractive index of the recesses 26, 27 in the n-doped layer 4 is higher than a refractive index of the n-doped layer 4.

[0124] Figures 27 and 28 show steps in a method for producing a semiconductor laser according to a further exemplary embodiment. The exemplary embodiment shown here differs from the exemplary embodiment shown in Figures 23 and 24 in that the optical structure 6 is arranged in the further layer sequence 19. The further layer sequence 19 then has, for example, the n-doped layer 4. The n-doped layer 4 can be arranged on the side of the optical structure 6 facing away from the further carrier 18, as shown here. Alternatively, the optical structure 6 can form an outer surface of the further layer sequence 19 facing away from the further carrier 18. A semiconductor laser 1 shown here is based, for example, on GaN. Such a semiconductor laser 1 can, for example, have improved thermal properties. In addition, the active region can be defect-free or designed with particularly few defects.

[0125] Figures 29, 30, 31, 32 and 33 show steps in a method for producing a semiconductor laser 1 according to a further embodiment.

[0126] In this exemplary embodiment, the further layer sequence 19 is formed from a transparent material 25 with low absorption. The transparent material 25 comprises, for example, SiCt, NbO, and / or SiN. The transparent material 25 also forms, for example, an outer surface of the layer sequence 16 facing away from the carrier 17 (Figure 29).

[0127] In Figure 30, the optical structure 6 is then at least partially delimited by the transparent material 25. The further carrier 18 is removed after the further layer sequence 19 has been connected to the layer sequence 16.

[0128] In the process step shown in Figure 31, the material 25 is partially removed to expose the n-doped layer 4 in places. The transparent material 25 is preferably arranged only in the region of the recesses 26, 27 of the optical structure 6.

[0129] In a subsequent process step, Figure 32, the electrically conductive layer 8 is applied to the n-doped layer 4 and / or to the transparent material 25.

[0130] Figure 33 shows a finished semiconductor laser 1. After the process step shown in Figure 32, a high-index layer 7, a further electrically conductive layer 9, and vias are arranged on the semiconductor laser 1.

[0131] Figures 34, 35, 36, 37 and 38 show semiconductor lasers 1 according to further embodiments.

[0132] Figure 34 shows the semiconductor laser 1 of Figure 11, wherein a contact 13 is applied to the further electrically conductive layer 9. The contact 13 corresponds, for example, to the contact 13 shown in Figure 7. An anti-reflection coating 30 is arranged in the opening 14 of the contact 13. An electrical contact element 28, in particular a p-contact 28, is applied to the side of the carrier 17 facing away from the semiconductor layer sequence 2. For example, the carrier 17 is designed to be electrically conductive.

[0133] The semiconductor laser 1 of Figure 35 differs from the semiconductor laser 1 shown in Figure 34 in that the semiconductor laser 1 has a further opening A on the p-doped side. The further opening A is created, for example, by arranging a dielectric material outside the further opening A or by plasma-assisted etching, for example by reactive ion etching of regions outside the further opening A. For example, the p-doped side has a mesa, which is formed, for example, by etching. A lateral extension of the mesa corresponds, for example, at least approximately to a lateral extension of the further opening A.

[0134] Figure 36 shows a semiconductor laser 1 which differs from the semiconductor laser 1 shown in Figure 34 in that a contact 13 is arranged on the p-doped side. In addition, the low-refractive-index layer 10 between the carrier 17 and the semiconductor layer sequence 2 is formed at least partially by a low-refractive-index dielectric, for example SiO2. This can reduce absorption in the low-refractive-index layer 10. The contact 13 is, for example, electrically conductively connected to the metal reflector 23 and / or to the electrical contact element 28. A better electrical and / or thermal connection can be achieved by means of the contact 13.

[0135] In contrast to the semiconductor laser 1 shown in Figure 36, the low-refractive-index layer 10 of the semiconductor laser 1 shown in Figure 37 is formed exclusively from a low-refractive-index dielectric.

[0136] Figure 38 shows a semiconductor laser 1 which differs from the semiconductor laser 1 shown in Figure 37 in that the low-refractive-index layer 10 has a Bragg mirror. Figure 39 shows a plan view of a semiconductor laser 1 according to an exemplary embodiment. For example, it is a plan view of the p-doped side 3 of the semiconductor laser 1. The contact 13 is applied to the low-refractive-index layer 10. Conductive connections 15 are arranged in the opening 14 of the contact 13.

[0137] Figure 40 shows a method step in a method for producing a semiconductor laser 1 according to a further exemplary embodiment. The electrically conductive layer 8 is applied to the optical structure 6, for example by means of oblique sputtering S or by oblique deposition S using an electron beam. The carrier 17 or the semiconductor layer sequence 2 is rotated R during the application of the electrically conductive layer 8. As a result, the electrically conductive layer 8 can extend partially into the recesses 26, 27 of the optical structure 6. The electrically conductive layer 8 can then be planarized.Preferably, the electrically conductive layer 8 can be applied by means of the method shown in connection with Figure 40 if the recesses have a lateral extent of a maximum of 10 nm, for example a maximum of 50 nm, in particular a maximum of 20 nm and a depth of at least 50 nm, at least 10 nm or at least 150 nm.

[0138] Figure 41 shows a plan view of a semiconductor laser 1 according to an exemplary embodiment. Figure 41 shows the contact 13 on the n-doped layer 4. The contact 13 comprises an opening 14 and conductive connections 15. The conductive connections 15 are in direct contact with one another in the opening 14, at least in places. For example, as shown here, the conductive connections 15 run in a star shape, starting from an intersection point. The recesses 26, 27 of the optical structure 6 have, for example, an approximately triangular basic shape. The recesses 26, 27 are, for example, arranged in a circle around the intersection point of the conductive connections 15.

[0139] The features and exemplary embodiments described in conjunction 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 conjunction with the figures can alternatively or additionally comprise further features according to the description in the general part.

[0140] This patent application claims priority from German patent application 102022134979.9, the disclosure of which is hereby incorporated by reference.

[0141] The invention is not limited to the embodiments by the description. Rather, the invention encompasses any novel feature and any combination of features, including, in particular, any combination of features in the claims, even if this feature or combination itself is not explicitly stated in the claims or embodiments. List of reference symbols

[0142] 1 semiconductor laser

[0143] 2 Semiconductor layer sequence

[0144] 3 p-doped layer

[0145] 4 n-doped layer

[0146] 5 active area

[0147] 6 optical structure

[0148] 7 high-index layer

[0149] 8 electrically conductive layer

[0150] 9 additional electrically conductive layer

[0151] 10 low-refractive layer

[0152] 10a ITO layer

[0153] 10b Bragg Mirror (DBR)

[0154] 11 Through-hole plating

[0155] 12 additional vias

[0156] 13 Contacting

[0157] 14 Opening

[0158] 15 conductive connection

[0159] 16 layer sequence

[0160] 17 carriers

[0161] 18 additional carriers

[0162] 19 further layer sequence

[0163] 20 Growth substrate

[0164] 21 Release layer

[0165] 22 Polarization

[0166] 23 Metal reflector

[0167] 24 Cover

[0168] 25 transparent material

[0169] 26 PC holes

[0170] 27 additional PC holes

[0171] 28 Contact element (p-contact)

[0172] 30 AR coating M mode profile

[0173] L length

[0174] A further opening

[0175] S oblique sputtering R rotation

Claims

Patent claims 1. Semiconductor laser (1) comprising - a semiconductor layer sequence (2) with a p-doped layer (3), an n-doped layer (4) and an active region (5) arranged between the p-doped layer (3) and the n-doped layer (4) for generating electromagnetic radiation, and - an optical structure (6) , wherein - the optical structure (6) at the p-doped layer (3) facing away from the active area (5), - the optical structure (6) has a refractive index varying in a lateral direction for the electromagnetic radiation generated by the active region (5), and - the n-doped layer (4) is arranged at least partially between the active region (5) and the optical structure (6).

2. Semiconductor laser (1) according to claim 1, wherein the optical structure (6) comprises a photonic crystal.

3. Semiconductor laser (1) according to one of the preceding claims, in which a high-refractive-index layer (7) is arranged on the side of the n-doped layer (4) facing away from the active region (5), wherein a refractive index of the high-refractive-index layer (7) is at least 1.

7.

4. Semiconductor laser (1) according to the preceding claim, wherein the high-refractive-index layer (7) is permeable to the electromagnetic radiation generated by the active region (5).

5. Semiconductor laser (1) according to one of claims 3 or 4, wherein an electrically conductive layer (8) is arranged between the high-refractive-index layer (7) and the n-doped layer (4), wherein the electrically conductive layer (8) is configured to electrically contact the n-doped layer (4).

6. Semiconductor laser (1) according to one of claims 3 to 5, wherein a further electrically conductive layer (9) is arranged on the side of the high-refractive-index layer (7) facing away from the active region (5), and the high-refractive-index layer (7) has at least one via (11).

7. Semiconductor laser (1) according to the preceding claim, in which the semiconductor laser (1) has at least one further Via (12), and the at least one via (11) and the at least one further via (12) are designed to at least partially extend the optical structure (6).

8. Semiconductor laser (1) according to one of claims 3 to 7, wherein the high-refractive-index layer (7) comprises NbO, TiO and / or GaN.

9. Semiconductor laser (1) according to one of claims 3 to 8, wherein the high-refractive-index layer (7) has a thickness of at least 150 nm.

10. Semiconductor laser (1) according to one of the preceding claims, in which a low-refractive index layer (10) is arranged on the side of the p-doped layer (3) facing away from the active region (5), wherein a refractive index of the low-refractive-index layer (10) smaller than a medium Refractive index of the semiconductor layer sequence (2).

11. Semiconductor laser (1) according to one of the preceding claims, wherein - the semiconductor laser (1) has a contact (13), - the contact (13) comprises an opening (14), and - at least one conductive connection (15) is arranged in the opening (14).

12. Semiconductor laser (1) according to the preceding claim, wherein the active region (5) emits polarized electromagnetic radiation with a polarization (22) during operation of the semiconductor laser (1) and the at least one conductive connection (15) runs perpendicular to the polarization (22) of the polarized electromagnetic radiation.

13. Semiconductor laser (1) according to one of the preceding claims, wherein the n-doped layer (4) has a thickness of at least 300 nm.

14. A method for producing a semiconductor laser (1) according to one of claims 1 to 13, comprising the following steps: - Providing a layer sequence (16) comprising a semiconductor layer sequence (2) with a p-doped layer (3), an n-doped layer (4) and an active region (5) arranged between the p-doped layer (3) and the n-doped layer (4) for generating electromagnetic radiation on a carrier (17), - Providing a further carrier (18) with a further layer sequence arranged on the further carrier (18) (19) , - producing an optical structure (6), wherein the optical Structure (6) a laterally varying refractive index for the electromagnetic radiation generated by the active region (5), and - Connecting the layer sequence (16) with the further layer sequence (19).

15. A method for producing a semiconductor laser (1) according to the preceding claim, wherein the optical structure (6) is produced in the layer sequence (16) or in the further layer sequence (19) before the layer sequence (16) is connected to the further layer sequence (19).

16. A method for producing a semiconductor laser (1) according to one of claims 14 to 15, wherein the optical structure (6) is produced in the layer sequence (16) and, after the layer sequence (16) has been connected to the further layer sequence (19), is at least partially delimited by the further layer sequence (19).

17. A method for producing a semiconductor laser (1) according to one of claims 14 to 16, wherein after the layer sequence (16) has been connected to the further layer sequence (19), through-contacts (11, 12) are produced in the further layer sequence (19).

18. A method for producing a semiconductor laser (1) according to one of claims 14 to 17, wherein the further carrier (18) is removed after the layer sequence (16) has been connected to the further layer sequence (19).

19. A method for producing a semiconductor laser (1) according to one of claims 14 to 18, wherein a semiconductor laser (1) is produced according to one of claims 1 to 13.