Method for producing a semiconductor laser chip, and semiconductor laser chip

Abstract

The invention relates to a method for producing a semiconductor laser chip, comprising the following steps: - producing a grid structure (15) starting from a surface (10) of the semiconductor body (1), wherein the grid structure extends from a surface (10) of the semiconductor body (15) along at least one horizontal surface (Ahor) and along at least one vertical surface (Aver) of the semiconductor body (1). The invention also relates to a semiconductor laser chip.

Description

[0001] 2024PF01322 January 15, 2026

[0002] P2024, 1116 WO N - 1 -

[0003] Description

[0004] METHOD FOR MANUFACTURING A SEMICONDUCTOR LASER CHIP AND SEMICONDUCTOR LASER CHIP

[0005] A method for manufacturing a semiconductor laser chip and a semiconductor laser chip are described.

[0006] A simplified method for manufacturing a semiconductor laser chip is to be presented. Furthermore, an improved semiconductor laser chip, in particular an improved DFB semiconductor laser chip (DFB stands for "distributed feedback"), is to be presented.

[0007] These tasks are solved by a method comprising the steps of claim 1 and by a semiconductor laser chip comprising the features of claim 13.

[0008] Advantageous embodiments and further developments of the method and the semiconductor laser chip are the subject of the dependent claims.

[0009] According to one embodiment of the process for manufacturing a semiconductor laser chip, a semiconductor body is provided with an epitaxial semiconductor layer sequence that includes a waveguide. The epitaxial semiconductor layer sequence, in particular, has a plurality of epitaxial semiconductor layers stacked one above the other in a growth direction.

[0010] For example, the epitaxial semiconductor layer sequence comprises an n-doped semiconductor layer and a p-doped semiconductor layer, between which a 2024PF01322 15 January 2026

[0011] P2024, 1116 WO N 2

[0012] The active layer is arranged in a specific location. The active layer is specifically designed to generate electromagnetic radiation. For this purpose, the active layer may, for example, have a pn junction, which can also be part of a quantum structure such as a double heterostructure, a single quantum well, or a multiple quantum well.

[0013] Furthermore, it is possible that the semiconductor body includes a growth substrate on which the epitaxial semiconductor layer sequence has grown epitaxially.

[0014] The bridge waveguide is specifically designed as a projection in the epitaxial semiconductor layer sequence and extends from the semiconductor body along the growth direction. Furthermore, the bridge waveguide is, for example, designed as a strip extending along a longitudinal direction perpendicular to the growth direction. For instance, the projection is embedded in the p-doped semiconductor layer of the epitaxial semiconductor layer sequence. The active layer, viewed along the growth direction, extends beneath the projection that serves as the bridge waveguide. In other words, the active layer is not enclosed by the projection.

[0015] The epitaxial semiconductor layer sequence has, in particular, side faces that run parallel to the growth direction and are perpendicular to a principal extension plane of the epitaxial semiconductor layer sequence. The side faces of the epitaxial semiconductor layer sequence are, in particular, wholly or partially configured as facets that are specularly reflecting for the electromagnetic radiation emitted in the active layer. 2024PF01322 15 January 2026

[0016] P2024, 1116 WO N 3

[0017] Operation is generated. The facets form, in particular, an optical resonator in which the active layer is arranged as a laser-active medium. One optical axis of the resonator runs, in particular, parallel to the longitudinal direction. A lateral direction is perpendicular to both the longitudinal direction and the growth direction.

[0018] In particular, the active layer is configured as a laser-active medium designed to generate population inversion in conjunction with the optical resonator. Due to this population inversion, electromagnetic radiation is generated in the active layer by stimulated emission, leading to the generation of electromagnetic laser radiation in the optical resonator. This electromagnetic laser radiation typically exhibits a very high coherence length, a very narrow emission spectrum, and / or a high degree of polarization, especially compared to electromagnetic radiation generated by spontaneous emission. Electromagnetic laser radiation generated in the active layer propagates, in particular, along the longitudinal direction within the epitaxial semiconductor layer sequence. The waveguide is specifically designed to guide this electromagnetic radiation.

[0019] One of the facets includes, in particular, a radiation emission surface configured to emit electromagnetic laser radiation. Specifically, the semiconductor laser chip in question is therefore an edge-emitting semiconductor laser chip. 2024PF01322 January 15, 2026

[0020] P2024, 1116 WO N 4

[0021] According to another embodiment of the method, a lattice structure is created starting from a surface of the semiconductor body, extending along at least one vertical and at least one horizontal surface of the semiconductor body. For example, the lattice structure is created using a photoresist mask.

[0022] In particular, the vertical and horizontal surfaces of the semiconductor body are perpendicular to each other. However, it is also possible for the vertical and horizontal surfaces of the semiconductor body to have an acute or obtuse angle to each other. For example, the vertical surface runs along the growth direction and the horizontal surface runs along the lateral and / or longitudinal direction. For example, the vertical surface is a side surface of the bridge waveguide. For example, at least one side surface of the bridge waveguide is provided with the grid structure. For example, the horizontal surface is an end surface of the bridge waveguide.

[0023] For example, the end face of the bridge waveguide is provided with the grid structure. Similarly, surfaces of the epitaxial semiconductor layer sequence that border the side faces of the bridge waveguide, particularly directly, can be horizontal surfaces that are wholly or partially covered with the grid structure.

[0024] In particular, the at least one horizontal surface and the at least one vertical surface to be provided with the grid structure need not be contiguous. 2024PF01322 15 January 2026

[0025] P2024, 1116 WO N 5

[0026] In particular, the process for manufacturing the semiconductor laser chip comprises the following steps:

[0027] - Providing the semiconductor body with the epitaxial semiconductor layer sequence comprising the bridge waveguide, and

[0028] - Generating the lattice structure that runs along vertical and horizontal surfaces of the semiconductor body, starting from the surface of the semiconductor body.

[0029] According to another embodiment of the process, the lattice structure is produced using an isotropic etching process. In this context, the term "etching process" does not necessarily refer to a process involving the removal of material. Specifically, it refers to processes for oxidation, passivation, and / or ion implantation. The etching process is characterized, in particular, by the fact that it alters the material of the semiconductor body and / or the epitaxial semiconductor layer sequence. In the etching process used here, the material change is isotropic, meaning it has no preferred direction.

[0030] The process is based in particular on the idea of ​​simultaneously providing vertical and horizontal surfaces of the semiconductor body with the lattice structure to which electromagnetic laser radiation can couple. The simultaneous generation of the lattice structure along and / or in at least one horizontal surface and along and / or in at least one vertical surface can be achieved, in particular, with an omnidirectional etching process. This allows for the advantageous and simple fabrication of an improved semiconductor laser chip. 2024PF01322 January 15, 2026

[0031] P2024, 1116 WO N 6

[0032] For example, isotropic etching involves treatment with a plasma, such as an oxygen plasma, an argon plasma, a boron plasma, or a borochloride plasma. With an oxygen plasma, oxidation of the treated surface is achieved in particular. If the lattice structure is created with an oxygen plasma, the lattice structure comprises or consists of an oxide. For example, the surface of the semiconductor body in which the lattice structure is created contains gallium, and the finished lattice structure is gallium oxide (GaOx).

[0033] It is also possible that ions are implanted into the treated semiconductor material during isotropic etching. Specifically, treatment with an argon plasma, a boron plasma, or a boron chloride plasma implants the plasma ions, i.e., Ar ions or B ions. This alters, for example, the electrical conductivity of the treated semiconductor material at its surface and / or within its interior, and / or its electrical contact resistance at the surface. It is also possible that the isotropic etching process results in a change in the refractive index and / or the absorption coefficient of the treated semiconductor material. For example, DFB coupling can be achieved via reflection coupling and / or gain / absorption coupling.

[0034] According to another embodiment of the method, the lattice structure is one-dimensional. The lattice structure has, for example, a large number of structural elements, which are, in particular, of a similar design. The structural elements are, in particular, in at least one 2024PF01322 15 January 2026

[0035] P2024, 1116 WO N 7

[0036] The spatial direction is arranged periodically. The term "one-dimensional" specifically means that the structural elements of the grid structure extend periodically in a single direction. For example, the one-dimensional grid structure has strip-shaped structural elements that are arranged parallel to each other. For example, the strip-shaped structural elements extend along the lateral direction and are arranged repeatedly along the longitudinal direction.

[0037] According to another embodiment of the method, the lattice structure is configured to optically couple electromagnetic laser radiation from the semiconductor laser chip to the lattice structure. For example, the spacing between the structural elements of the lattice structure is a multiple of half the wavelength of the electromagnetic laser radiation guided in the semiconductor body. In particular, the lattice structure is configured to suppress modes of electromagnetic laser radiation generated within the optical resonator, so that only a single mode of electromagnetic laser radiation is formed in the optical resonator. Specifically, the lattice structure is configured to operate the semiconductor laser chip in a DFB mode.

[0038] According to another embodiment of the method, the semiconductor body comprises a nitride compound semiconductor material. In particular, the epitaxial semiconductor layer sequence comprises or consists of one or more nitride compound semiconductor materials.

[0039] Nitride compound semiconductor materials are 2024PF01322 15 January 2026

[0040] P2024, 1116 WO N - 8 -

[0041] Compound semiconductor materials containing nitrogen, such as the materials from the system In x Al y Ga 1-x-y N with 0 < x < 1, 0 < y < 1 and x+y < 1. For example, the nitride compound semiconductor material is AlGaN. If the surface of the semiconductor body, which has a nitride compound semiconductor material, is oxidized, the resulting oxide is in particular GaOx.

[0042] According to another embodiment of the process, the generation of the lattice structure by oxidation with an oxygen plasma creates lattice-like regions on the surface of the semiconductor body that have a different refractive index than the surrounding semiconductor material. In other words, the semiconductor body is treated with an undirected oxygen plasma in an isotropic etching process. For example, prior to oxidation with the oxygen plasma, a photoresist mask with the inverse structure of the lattice pattern is applied to the semiconductor body, so that only the areas of the surface not covered by the photoresist mask are oxidized.

[0043] According to another implementation of the process, oxidized semiconductor material is removed from the lattice structure, and the lattice structure is then re-oxidized with an oxygen plasma. For example, the oxidized semiconductor material is removed from the lattice structure using wet chemical methods, such as HCl. It is also possible to remove the oxidized semiconductor material from the lattice structure using dry chemical methods. This allows the lattice structure to be embedded deeper into the semiconductor body, starting from its surface. It is also possible that the lattice structure is not re-oxidized with the oxygen plasma. 2024PF01322 January 15, 2026

[0044] P2024, 1116 WO N - 9 -

[0045] Instead, only the oxidized semiconductor material of the lattice structure is removed. This allows the refractive index difference between the lattice structure and the surrounding semiconductor material to be increased.

[0046] In another embodiment of the process, the lattice structure is smoothed using wet chemical methods. This is particularly relevant for lattice structures that contain or are formed from oxidized semiconductor material. Specifically, wet chemical smoothing of the lattice structure is performed when it is created by removing oxidized semiconductor material and is thus at least partially formed by air-filled structures within the semiconductor material. Such a lattice structure exhibits a comparatively large refractive index difference compared to the surrounding semiconductor material and therefore enables effective coupling of electromagnetic laser radiation. For example, the lattice structure is smoothed crystallographically, meaning that roughness is smoothed at the atomic scale. Wet chemical smoothing is performed, for instance, using KOH.Wet chemical smoothing reduces scattering losses in the operation of the semiconductor laser chip and increases the coupling of electromagnetic radiation to the grid structure.

[0047] According to another embodiment of the method, the lattice structure exhibits a different electrical conductivity and / or electrical contact resistance than the surrounding semiconductor material. In particular, the electrical conductivity and / or electrical contact resistance of the lattice structure is modified compared to the surrounding semiconductor material, especially by the 2024PF01322 15 January 2026

[0048] P2024, 1116 WO N - 10 -

[0049] isotropic etching process. In this embodiment, the lattice structure exhibits, in particular, no refractive index difference compared to the surrounding semiconductor material. Preferably, the lattice structure has a lower electrical conductivity and / or a lower electrical contact resistance than the surrounding semiconductor material. In this

[0050] In this implementation, the lattice structure is generated, in particular, wholly or partially within the interior of the semiconductor body. A lattice structure with a different electrical conductivity and / or a different electrical contact resistance is generated, in particular, by implanting boron ions with a boron plasma or a boron chlorine plasma, or by implanting argon ions with an argon plasma.

[0051] According to another embodiment of the process, the lattice structure causes a charge carrier density modulation in the active layer of the epitaxial semiconductor layer sequence. This is particularly the case when the lattice structure has a different electrical conductivity and / or electrical contact resistance than the surrounding semiconductor material. For example, the semiconductor body treated with the isotropic etching process may have a surface containing p-doped or p++-doped GaN, i.e., highly doped GaN. Treating this semiconductor body with the isotropic etching process significantly alters the electrical contact capability of the p-doped or p++-doped GaN. For instance, the isotropic etching process achieves a type of passivation with a deep effect within the semiconductor body.This leads to the following: due to the limited lateral charge carrier mobility in GaN and / or in p-GaN2024PF01322, January 15, 2026.

[0052] P2024, 1116 WO N 11

[0053] A charge carrier density modulation occurs in the active layer.

[0054] For example, the lattice structure with the different electrical conductivity and / or the different electrical contact resistance extends from the surface of the semiconductor body to the active layer.

[0055] For example, the lattice structure exhibits restricted lateral charge carrier mobility in the adjacent, particularly p-doped, semiconductor material. In other words, the lattice structure originates from the p-doped semiconductor layer of the epitaxial semiconductor layer sequence and extends into the undoped active layer. Specifically, charge carrier density modulation arises in the active layer due to the lattice structure in the overlying p-doped epitaxial layer. This charge carrier density modulation within the active layer leads, for example, to regions within the quantum structures of the active layer that are configured to amplify electromagnetic laser radiation and regions within the quantum structures of the active layer that are configured to absorb electromagnetic laser radiation.

[0056] According to one embodiment of the method, the lattice structure is produced by one of the following processes: treatment with a B-plasma, treatment with an Ar-plasma, treatment with a BCl-plasma, B-implantation, ion etching, e.g., with argon. These specified processes are particularly suitable for producing a lattice structure that exhibits a different electrical conductivity and / or electrical contact resistance than the surrounding semiconductor material. 2024PF01322 January 15, 2026

[0057] P2024, 1116 WO N 12

[0058] According to one implementation of the process, no material removal occurs during the generation of the lattice structure. This is particularly the case when treated with a B-plasma, an Ar-plasma, a BCl-plasma, B-implantation and / or ion etching to generate a lattice structure with a different electrical conductivity and / or a different electrical contact resistance than the surrounding semiconductor material.

[0059] The method is specifically designed to produce the semiconductor laser chip described below.

[0060] Consequently, features and embodiments that are described here only in connection with the method can also be present in the semiconductor laser chip and vice versa.

[0061] According to one embodiment, the semiconductor laser chip comprises a semiconductor body with an epitaxial sequence of semiconductor layers, which includes a bridge waveguide.

[0062] According to another embodiment, the semiconductor laser chip comprises a lattice structure extending from a surface of the semiconductor body along at least one vertical and at least one horizontal surface of the semiconductor body. In particular, the lattice structure is embedded in at least one vertical and at least one horizontal surface of the semiconductor body.

[0063] According to one embodiment, the semiconductor laser chip comprises the semiconductor body with the epitaxial semiconductor layer sequence, which includes the waveguide and the lattice structure extending from the surface of the 2024PF01322 15 January 2026

[0064] P2024, 1116 WO N 13

[0065] a semiconductor body that extends along at least one vertical surface and at least one horizontal surface of the semiconductor body. For example, the lattice structure is incorporated into the at least one horizontal surface and the at least one vertical surface.

[0066] Due to the lattice structure, which extends along both the vertical and horizontal surfaces of the semiconductor body, good coupling of the electromagnetic laser radiation generated in the semiconductor laser chip can be advantageously achieved. Particularly good coupling of the electromagnetic laser radiation to the lattice structure occurs when there is a high overlap between the electromagnetic radiation and the lattice structure. This is achieved primarily through the simultaneous use of horizontal and vertical lattices. Thus, an improved semiconductor laser chip with preferably single-mode operation can be provided.

[0067] According to another embodiment of the semiconductor laser chip, the lattice structure has a different refractive index than the surrounding semiconductor material. This allows electromagnetic laser radiation to optically couple to the lattice structure.

[0068] According to another embodiment of the semiconductor laser chip, the lattice structure has GaOx or consists of GaOx.

[0069] Here, the lattice structure is arranged in particular on and / or in a surface of the semiconductor body, and the surrounding semiconductor material is a p-doped nitride compound semiconductor material, for example p-doped AlGaN, p++-doped AlGaN, p-doped GaN, or p++-doped GaN. 2024PF01322 January 15, 2026

[0070] P2024, 1116 WO N - 14 -

[0071] According to another embodiment of the semiconductor laser chip, the material of the lattice structure exhibits a different electrical conductivity and / or a different electrical contact resistance than the surrounding semiconductor material. In particular, the lattice structure with the altered electrical conductivity extends from a surface of the epitaxial semiconductor layer sequence towards the active layer.

[0072] In particular, the variation in electrical contact resistance and / or electrical conductivity is transferred to the quantum structures within the active layer.

[0073] In this embodiment, the surface of the semiconductor laser chip is formed by a p-doped nitride-based semiconductor layer or a p++-doped nitride-based semiconductor layer, and the lattice structure with the modified electrical conductivity and / or the modified electrical contact resistance extends from the p-doped or p++-doped surface to the active layer inside the semiconductor body. Specifically, the active layer lies below a waveguide and is not enclosed by it.

[0074] For example, the material of the lattice structure exhibits a different electrical contact resistance than the surrounding semiconductor material. This refers specifically to the lattice structure material that is arranged on a surface of the semiconductor body or the epitaxial semiconductor layer sequence. If the electrical contact resistance of the lattice structure is altered, particularly if it is lower than that of the surrounding semiconductor material, less current is injected into the epitaxial semiconductor layer sequence from the lattice structure into the active layer during operation of the semiconductor laser chip, resulting in a 2024PF01322 15 January 2026

[0075] P2024, 1116 WO N 15

[0076] Charge carrier density modulation occurs in the active layer. This charge carrier density modulation, in turn, leads to a modulation of the amplification of the electromagnetic laser radiation in the active layer. The grating structure can be arranged, in particular, on horizontal surfaces on the waveguide, on the side surfaces of the waveguide, or next to the waveguide.

[0077] According to another embodiment of the semiconductor laser chip, it is a DFB semiconductor laser chip. The DFB semiconductor laser chip features, in particular, a lattice structure for coupling electromagnetic laser radiation to it and selecting predetermined spectral modes of the electromagnetic laser radiation. Specifically, the lattice structure leads to the selection of a single spectral mode, so that the DFB semiconductor laser chip emits only a single spectral mode of electromagnetic laser radiation during operation. The DFB semiconductor laser chip is specifically designed to operate in spectrally monomode mode. Most preferably, the DFB semiconductor laser chip exhibits a side mode suppression of at least 20 decibels or at least 30 decibels.

[0078] The semiconductor laser chip can find applications particularly in components for artificial or virtual reality, material processing, projection, illumination, sensors, analytics, or quantum computers. Medical applications are also conceivable.

[0079] Advantageous implementation forms and further developments of the process for manufacturing a semiconductor laser chip and the semiconductor laser chip result from the following in 2024PF01322 15 January 2026

[0080] P2024, 1116 WO N 16

[0081] In conjunction with the exemplary embodiments described in the figures.

[0082] Figures 1 to 6 show schematic representations of stages of a process according to an exemplary embodiment.

[0083] Figure 7 shows a schematic representation of a semiconductor laser chip according to an exemplary embodiment.

[0084] Figures 8 to 13 show schematic representations of stages of a process according to a further embodiment.

[0085] Figure 14 shows a schematic representation of a stage of a process according to a further embodiment.

[0086] Figures 15 and 16 show schematic representations of a semiconductor laser chip according to a further embodiment.

[0087] Figure 17 schematically shows absorption and amplification of electromagnetic laser radiation in an active layer of the semiconductor laser chip according to the embodiment shown in Figures 15 and 16.

[0088] Identical, similar, or similarly functioning elements are marked 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, especially layer thicknesses, may be exaggerated for clarity and / or better understanding. 2024PF01322 January 15, 2026

[0089] P2024, 1116 WO N - 17 -

[0090] In the method according to the embodiment shown in Figures 1 to 6, a semiconductor body 1 is first provided (Figure 1). The semiconductor body 1 has an epitaxial semiconductor layer sequence 2 comprising a p-doped semiconductor layer 3, an n-doped semiconductor layer 4, and an active layer 5. The active layer 5 is configured to generate electromagnetic radiation. The active layer 5 is arranged between the p-doped semiconductor layer 3 and the n-doped semiconductor layer 4. In this case, the epitaxial semiconductor layer sequence 2 is mounted on a growth substrate 6 in a growth direction R. w It grew epitaxially.

[0091] Furthermore, the epitaxial semiconductor layer sequence 2 comprises a bridge waveguide 7, which extends as a projection 8 of the epitaxial semiconductor layer sequence 2 from the p-doped semiconductor layer 3 in the growth direction R. wThe bridge waveguide 7 is configured to guide electromagnetic laser radiation in an active region 9 of the epitaxial semiconductor layer sequence 2, which at least partially encompasses the active layer 5. The bridge waveguide 7 is designed as a strip extending along a longitudinal direction R. long extends along the growth direction R w It stands upright.

[0092] A photoresist mask 11 is applied to a surface 10 of the semiconductor body 1, which includes the waveguide 7. This mask is shown in particular in the top view of the waveguide 7 of the semiconductor body 1 in Figure 2. The photoresist mask 11 comprises strip-shaped structural elements 12 that extend along a lateral direction Ri. at via a surface 13 of the epitaxial 2024PF01322 January 15, 2026

[0093] P2024, 1116 WO N 18

[0094] Semiconductor layer sequence 2 extends. The lateral direction Riat is aligned with the growth direction R. w and the longitudinal direction R long perpendicular.

[0095] The strip-shaped structural elements 12 of the photoresist mask 11 expose strip-shaped structural elements 14 of a surface 13 of the epitaxial semiconductor layer sequence 2. The exposed structural elements 14 of the surface 13 are arranged periodically and each has a distance from the other corresponding to an integer multiple of half the wavelength of the electromagnetic radiation generated by the active layer 5.

[0096] Starting from the surface 10 of the semiconductor body 1, a lattice structure 15 is created, which extends along horizontal surfaces A hor and vertical surfaces A ver of the semiconductor body 1 (Figures 3 and 4). The vertical surfaces A verof the semiconductor body 1 run in particular along the growth direction R w or at least partially at an acute angle to the growth direction R w For example, the side surfaces 16 of the bridge waveguide 7 are vertical surfaces A ver - The horizontal surfaces A hor run particularly along the lateral direction Ri at or form an acute angle with the lateral direction Ri at one. For example, an end face 17 of the bridge waveguide 7 and the areas of the surface 13 of the epitaxial semiconductor layer sequence 1 that directly adjoin the bridge waveguide 7 are horizontal surfaces A hor - For example, the horizontal surfaces A hor perpendicular to the vertical surfaces A ver or stand on the vertical surfaces A ver vertical.2024PF01322 January 15, 2026

[0097] P2024, 1116 WO N 19

[0098] To generate the lattice structure 15, the surface 10 of the semiconductor body 1 is exposed to an oxygen plasma 18. The surface 10 of the semiconductor body 1 exposed to the oxygen plasma 18 comprises the semiconductor material of the p-doped semiconductor layer 3 of the epitaxial semiconductor layer sequence 2. The surface 10 of the semiconductor body 1 oxidized by the oxygen plasma 18 comprises p-doped AlGaN or is composed of p-doped AlGaN. It is also possible that the surface 10 of the semiconductor body 1 oxidized by the oxygen plasma 18 comprises p-doped GaN or is composed of p-doped GaN.

[0099] The oxygen plasma 18 oxidizes the exposed strip-shaped structural elements 14 of the surface 10 of the semiconductor body 1. In particular, the side surfaces 16 of the bridge waveguide 7 and the end surface 17 of the bridge waveguide 7, as well as surfaces of the p-doped semiconductor layer 3 that are arranged laterally to and directly adjacent with the bridge waveguide 7, are treated simultaneously with the oxygen plasma 18. At the same time, the areas of the surface of the p-doped semiconductor layer 3 that are not covered by the photoresist mask 11 are also oxidized by the oxygen plasma 18.

[0100] In particular, the oxygen plasma 18 is non-directional, that is, both the vertical surfaces A ver as well as the horizontal surfaces A horThe semiconductor body 1 is simultaneously oxidized and thus provided with the lattice structure 15, which is defined by the photoresist mask 11. The surface 10 of the semiconductor body 1 is formed in particular by p-doped AlGaN and is attached to the surfaces with the 2024PF01322 15 January 2026

[0101] P2024, 1116 WO N 20

[0102] Gallium oxide forms at the oxygen plasma treated sites (18). The thickness of the gallium oxide, starting from the surface (10) of the semiconductor body (1), is, for example, approximately 10 nanometers.

[0103] After oxidation with the oxygen plasma 18, the photoresist mask 11 is removed (Figures 5 and 6). The lattice structure 15 is now formed on the end face 17 of the bridge waveguide 7, on the side faces 16 of the bridge waveguide 7, and on the surface 13 of the epitaxial semiconductor layer sequence 1 directly adjacent to the bridge waveguide 7. The lattice structure 15 has strip-shaped structural elements 20 at a periodic interval. The distance between the strip-shaped structural elements 20 of the lattice structure 15 is, in particular, an integer multiple of half the wavelength of the electromagnetic laser radiation in the semiconductor body. The strip-shaped structural elements 20 are perpendicular to a longitudinal direction along which the electromagnetic laser radiation propagates in the semiconductor laser chip.

[0104] The lattice structure 15, formed from the GaOx, has, for example, a refractive index of approximately 1.95 at a wavelength of 450 nanometers, while a surrounding semiconductor material 19, which may consist of various nitride compound semiconductor materials with the formula Al x In y Gai- x -yN has a refractive index of approximately 2.47 at 450 nanometers. In other words, the refractive index difference between the lattice structure 15 and the surrounding semiconductor material 19 is approximately 0.52 at a wavelength of 450 nanometers. 2024PF01322 January 15, 2026

[0105] P2024, 1116 WO N - 21 -

[0106] The semiconductor laser chip according to the embodiment shown in Figure 7 can, for example, be manufactured using the method already described with reference to Figures 1 to 6.

[0107] The semiconductor body 1 of the semiconductor laser chip according to Figure 7 has an epitaxial semiconductor layer sequence 2 which is epitaxially deposited on a growth substrate 6 along a growth direction R w has grown. The epitaxial semiconductor layer sequence 2 has an active layer 5, which is arranged between an n-doped semiconductor layer 4 and a p-doped semiconductor layer 3. Furthermore, a projection 8 is introduced in the p-doped epitaxial semiconductor layer 3 as a bridge waveguide 7. Side surfaces 21 of the epitaxial semiconductor layer sequence 1, which are shown here perpendicular to a longitudinal direction R longThe facets 22 are configured as facets and are specularly reflecting the electromagnetic radiation generated in the active layer 5. The facets 22 form an optical resonator 23 in which electromagnetic laser radiation is generated within an active region 9 of the epitaxial semiconductor layer sequence 2. The electromagnetic laser radiation is emitted from a radiation exit surface 25, which is encompassed by one of the facets 22.

[0108] A lattice structure 15, which is one-dimensional in this case, is applied to an end face 17 of the bridge waveguide 7, to side faces 16 of the bridge waveguide 7, and to a region of the epitaxial semiconductor layer sequence 2 that directly adjoins the bridge waveguide 7. The lattice structure is shown in the following document: 152024PF01322 15 January 2026

[0109] P2024, 1116 WO N

[0110] Strip-shaped structural elements 20 are present, each spaced a multiple of half the wavelength of the electromagnetic laser radiation emitted by the semiconductor laser chip during operation (see also Figure 6). In particular, the lattice structure 15 of the semiconductor laser chip in Figure 7 contains or consists of oxidized gallium.

[0111] The electromagnetic radiation generated in the active region 9 of the semiconductor laser chip can overlap with the grating structure 15 at all edges of the waveguide 7 in the semiconductor laser chip according to Figure 7, thus optically coupling to the grating structure 15. This advantageously allows the semiconductor laser chip to be operated in DFB mode according to the embodiment shown in Figure 7. With the aid of the grating structure 15, a specific spectral mode of the electromagnetic laser radiation within the active region 24 is amplified and emitted from the radiation exit surface 25, while other modes of the electromagnetic laser radiation are absorbed or amplified to a significantly lesser extent.

[0112] In the embodiment according to the method of Figures 8 to 13, a grid structure 15 is first formed along vertical surfaces A ver and horizontal surfaces A horstarting from a surface 10 of a semiconductor body 1, as already described with reference to Figures 1 to 4. The lattice structure 15 is formed here from GaOx and has strip-shaped structural elements 20 which are surrounded by a nitride-based semiconductor material 19 (see Figures 8 and 9). In particular, a photoresist mask 11 is arranged between the strip-shaped structural elements 20. Instead of a photoresist mask 11, a 2024PF01322 15 January 2026 could also be used.

[0113] P2024, 1116 WO N - 23 -

[0114] A hard mask comprising a dielectric material or a TCO (short for transparent conductive oxide) may be used.

[0115] In a next step, the GaOx of the lattice structure 15 is selectively removed using wet chemical methods, for example with HCl.

[0116] Alternatively, the lattice structure 15 can also be removed using dry chemical processes. The removal of the GaOx results in a lattice structure 15 that is air-filled and surrounded by semiconductor material 19 with a high refractive index of approximately 2.47. This yields a lattice structure 15 with a refractive index difference of approximately 1.47 compared to the surrounding semiconductor material 19 (Figures 10 and 11).

[0117] In a next step, another oxidation step is performed by exposing the semiconductor body 1 to an oxygen plasma 18, with the photoresist mask 11 covering the areas between the structural elements 20 of the lattice structure 15 (not shown). This creates another gallium oxide layer starting from the recessed surface within the lattice structure 15, again with a depth of approximately 10 nanometers. These steps can now be repeated several times. In particular, a lattice structure 15 can be created that includes air-filled areas 24 and oxidized areas 29 with GaOx, arranged one above the other along a growth direction R. w are arranged. In other words, a lattice structure 15 can be created which, starting from the semiconductor material, has an oxidized semiconductor layer with GaOx, followed by an air layer (see Figures 12 and 13). 2024PF01322 January 15, 2026

[0118] P2024, 1116 WO N - 24 -

[0119] Alternatively, it is also possible to remove the gallium oxide by wet chemical means as a final step, resulting in a deep air-filled lattice structure 15 in the surface 13 of the epitaxial semiconductor layer sequence 2 (not shown).

[0120] In the method according to the embodiment shown in Figure 14, a lattice structure 15, from which GaOx has been removed by wet chemical etching, is crystallographically smoothed in an additional wet chemical process. For this purpose, the semiconductor body 1 in the present embodiment is immersed in an alkaline solution 26, such as KOH. If the semiconductor body is based on a semiconductor material other than a nitride compound semiconductor material, a different etching agent could also be used. This minimizes scattering losses within the finished semiconductor laser chip and improves the coupling of electromagnetic radiation from the active layer 5 to the lattice structure 15.

[0121] The semiconductor laser chip according to the embodiment shown in Figures 15 and 16, unlike the semiconductor laser chip according to the embodiment shown in Figure 7, has a lattice structure 15 that is produced, for example, by ion etching, boron implantation, a BCl plasma, and / or an Ar plasma. The lattice structure 15 of the semiconductor laser chip has no or only a slight difference in refractive index compared to the surrounding semiconductor material 19. Instead, the lattice structure 15 has a different electrical conductivity and / or electrical contact capability compared to the surrounding semiconductor material 19. 2024PF01322 January 15, 2026

[0122] P2024, 1116 WO N - 25 -

[0123] The lattice structure 15 is presently embedded in p-GaN or highly doped p++-GaN, which at least partially forms a surface 10 of the semiconductor body 1. The electrical conductivity and / or electrical contact capability of the lattice structure 15 approaches that of quantum structures 30 in the active layer 5 (Figure 15). This leads to a modulation of the amplification and absorption of electromagnetic radiation within the active layer 5. The surface 10 of the semiconductor body 1, however, remains largely intact during the creation of the lattice structure 15, as no material is removed. Whether material is removed during plasma treatment can be controlled by the duration of the plasma treatment, the power of the plasma treatment, and / or the plasma density. If the surface 10 of the semiconductor body 1 remains largely intact, scattering at the surface 10 is reduced.In particular, a type of passivation with a deep effect is achieved during the production of the lattice structure 15, especially when using a BCl plasma.

[0124] Due to the restricted lateral charge carrier mobility in GaN or p-GaN, a charge carrier density modulation arises in the quantum structures of the active layer 5. In particular, regions with absorption 27 and regions with gain 28 of electromagnetic radiation alternate periodically in the active layer 5, with the distances between regions with gain 27 and regions with absorption 28 having a value corresponding to an integer multiple of half the wavelength of the electromagnetic radiation in the active layer 5.

[0125] P2024, 1116 WO N 26

[0126] Layer 5 is created. However, a refractive index difference is not provided for in the active layer 5.

[0127] Figure 17 schematically shows the path of electromagnetic radiation within the active layer 5 according to Figures 15 and 16. Nodes of the electromagnetic wave overlap with regions 27 in the active layer 5 where absorption occurs, while maxima of the electromagnetic radiation overlap with regions of amplification 28. In contrast to spontaneous emission with longer charge carrier lifetimes, lateral diffusion of charge carriers occurs only minimally during the generation of electromagnetic laser radiation. Therefore, the lattice structure 15 is well represented in the quantum structures 30 of the active layer 5 as an amplification profile modulation.

[0128] The present application claims priority over German application DE 102025109348.2, the disclosure content of which is hereby incorporated by reference.

[0129] The invention is not limited to the description provided by means of the exemplary embodiments. Rather, the invention encompasses every new feature as well as every combination of features, which in particular includes every combination of features in the claims, even if that feature or combination itself is not explicitly stated in the claims or exemplary embodiments. 2024PF01322 January 15, 2026

[0130] P2024, 1116 WO N - 27 -

[0131] Reference symbol list

[0132] 1 Semiconductor body

[0133] 2 epitaxial semiconductor layer sequence

[0134] 3 p-doped semiconductor layer

[0135] 4 n-doped semiconductor layer

[0136] 5 active layer

[0137] 6. Growth substrate

[0138] 7 Bridge waveguides

[0139] 8 lead

[0140] 9 active area

[0141] 10 Surface of the semiconductor body

[0142] 11 Photoresist mask

[0143] 12. Strip-shaped structural element of the photoresist mask 13. Surface of the epitaxial semiconductor layer sequence 14. Strip-shaped structural element of the surface of the epitaxial semiconductor layer sequence

[0144] 15 Grid structure

[0145] 16 Side surface of the bridge waveguide

[0146] 17 End face of the bridge waveguide

[0147] 18 Oxygen plasma

[0148] 19 surrounding semiconductor material

[0149] 20 Strip-shaped structural element of the lattice structure 21 Side surface of the epitaxial semiconductor layer sequence 22 Facet

[0150] 23 optical resonator

[0151] 24 air-filled area

[0152] 25 Radiation emission area

[0153] 26 alkaline solution

[0154] 27 Area with absorption

[0155] 28 Area with amplification

[0156] 29 oxidized area

[0157] 30 Quantum Structures 2024PF01322 January 15, 2026

[0158] P2024, 1116 WO N

[0159] - 28 -

[0160] R w direction of growth

[0161] R long longitudinal direction

[0162] R lat lateral direction

[0163] A hor horizontal surface

[0164] A ver vertical surface

Claims

2024PF01322 January 15, 2026 P2024, 1116 WO N - 29 - Patent claims 1. Method for manufacturing a semiconductor laser chip comprising the following steps: - Providing a semiconductor body ( 1 ) with an epitaxial semiconductor layer sequence (2 ) comprising a bridge waveguide (7 ), and - Generating a lattice structure ( 15) starting from a surface ( 10) of the semiconductor body ( 1 ), wherein the lattice structure extends from a surface ( 10) of the semiconductor body ( 15) along at least one horizontal surface (A ). hor ) and along at least one vertical surface (A ver ) of the semiconductor body ( 1 ).

2. Method according to the preceding claim, wherein the lattice structure ( 15) is produced using an isotropic etching process.

3. Method according to any of the preceding claims, wherein the lattice structure ( 15) is one-dimensional.

4. Method according to one of the preceding claims, wherein the grid structure ( 15) is configured to optically couple electromagnetic laser radiation from the semiconductor laser chip to the grid structure ( 15).

5. A method according to any one of the preceding claims, wherein the semiconductor body (1) comprises a nitride compound semiconductor material. 2024PF01322 15 January 2026 P2024, 1116 WO N 30 6. Method according to one of the preceding claims, wherein in the production of the lattice structure ( 15) lattice-shaped regions are produced on the surface ( 10) of the semiconductor body ( 1 ) by oxidation with an oxygen plasma ( 18 ) which have a different refractive index than the surrounding semiconductor material ( 19).

7. Method according to the preceding claim, wherein - oxidized semiconductor material of the lattice structure ( 15) is removed, and - the lattice structure ( 15) is oxidized again with an oxygen plasma ( 18 ).

8. Method according to the preceding claim, wherein the lattice structure ( 1 ) is smoothed by wet chemical means.

9. Method according to any of the preceding claims, wherein the lattice structure ( 15) has a different electrical conductivity and / or electrical contact resistance than the surrounding semiconductor material ( 19).

10. Method according to any of the preceding claims, wherein the lattice structure ( 15) causes a charge carrier density modulation in an active layer (5) of the epitaxial semiconductor layer sequence (2 ).

11. A method according to claim 9 or 10, wherein the lattice structure (15) is produced by one of the following methods: treatment with a B-plasma, treatment with a BCl-plasma, treatment with an Ar-plasma, B-implantation, ion etching. 2024PF01322 January 15, 2026 P2024, 1116 WO N - 31 - 12. Method according to the preceding claim, wherein no material removal occurs during the creation of the lattice structure ( 15).

13. Semiconductor laser chip comprehensive: - a semiconductor body ( 1 ) with an epitaxial semiconductor layer sequence (2 ) comprising a bridge waveguide (7 ), and - a lattice structure ( 15) originating from a surface ( 10) of the semiconductor body ( 1 ) extending along at least one vertical surface (A ) ver ) and along at least one horizontal surface (A hor ) of the semiconductor body ( 1 ).

14. Semiconductor laser chip according to the previous claim, wherein the lattice structure ( 15) has a different refractive index than the surrounding semiconductor material ( 19).

15. Semiconductor laser chip according to one of claims 13 or 14, wherein the lattice structure ( 15) GaOx has.

16. Semiconductor laser chip according to one of claims 13 to 15, wherein the material of the lattice structure ( 15) has a different electrical conductivity and / or a different electrical contact resistance than the surrounding semiconductor material ( 19).

17. Semiconductor laser chip according to one of claims 13 to 16, wherein It is a DFB semiconductor laser chip.

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