Light-emitting semiconductor chip and method for manufacturing a light-emitting semiconductor chip

Description

[0001] A light-emitting semiconductor chip and a method for producing a light-emitting semiconductor chip are specified.

[0002] This patent application claims priority from German patent application 102020133177.0.

[0003] Laser light sources are often used in optical devices such as projectors, so-called VR and / or AR glasses (VR: "virtual reality"; AR: "augmented reality"), etc. However, due to the physical nature of coherent laser radiation, certain image artifacts such as interference and / or speckles or similar light granulation can occur, which are undesirable in many applications. To improve image quality in this regard, it can be helpful to work with multi-emitter components that, ideally, have emission wavelengths shifted from one another. Components with two, three, four, or more emitters whose emission wavelengths are shifted from one another in a defined manner can be particularly advantageous.

[0004] By varying the laser geometry, such as ridge width, resonator length, and / or mirroring, changes in wavelength can be achieved. However, these wavelength changes are usually accompanied by a change in laser parameters such as threshold, slope, and operating current, which is undesirable because all emitters on a chip should have comparable laser parameters. Emitters with different wavelengths can also be produced through multiple epitaxy. However, this requires a high level of technical effort and is expensive. Strain-modifying structures on the wafer can also influence the epitaxy in such a way that locally different wavelengths are formed. However, these structures require additional space on the chip, which is expensive, and can have undesirable side effects on laser parameters such as the far-field width.

[0005] The approaches chosen so far, for example a variation of the optical waveguide geometry parameters and / or the mirroring, are therefore sometimes very difficult to implement technically and inevitably lead to a variation of the operating parameters with the emission wavelength, whereas maintaining comparable operating parameters would be desirable.

[0006] Semiconductor lasers are known, for example, from the publications O. Voegeli et al., "Full-wafer technology for large-scale laser processing and testing", J. Vac. Sci. Technol. B 9(6), Nov / Dec 1991, pp. 2886-2892, US 2019 / 348568 A1, US 2004 / 0113164 A1 and WO 01 / 22543 A1.

[0007] At least one object of certain embodiments is to provide a light-emitting semiconductor chip.

[0008] At least one further object of certain embodiments is to provide a method for producing a light-emitting semiconductor chip.

[0009] These objects are achieved by a subject matter and a method according to the independent patent claims. Advantageous embodiments and further developments of the subject matter and method are characterized in the dependent claims and will further become apparent from the following description and the drawings.

[0010] According to at least one embodiment, a light-emitting semiconductor chip comprises a semiconductor body with at least one emitter unit. The light-emitting semiconductor chip preferably has a plurality of emitter units, for example greater than or equal to 2 or greater than or equal to 3 or greater than or equal to 4 emitter units. Particularly preferably, the emitter units can be identical or at least similar, unless otherwise described. Particularly preferably, the plurality of emitter units is formed monolithically in the semiconductor body. In a method for producing the light-emitting semiconductor chip, the semiconductor body is grown, for example on a substrate, wherein the semiconductor body has the one or the plurality of emitter units.Unless otherwise stated, the features described below apply equally to a light-emitting semiconductor chip with one emitter unit as well as to a light-emitting semiconductor chip with a plurality of emitter units. The following description also applies equally to the light-emitting semiconductor chip and to the method for producing the light-emitting semiconductor chip.

[0011] Each of the at least one emitter unit has an active region configured and intended to generate light during operation. Here and below, light can refer in particular to electromagnetic radiation with one or more spectral components in an infrared to ultraviolet wavelength range. Accordingly, the terms light, radiation, and electromagnetic radiation can be used synonymously. The light generated in the active region can be specified by a characteristic wavelength. The characteristic wavelength can refer to the most intense wavelength of the spectrum of the generated light. Alternatively, the characteristic wavelength can also refer to the mean wavelength of the spectral range in which the generated light lies.Furthermore, the characteristic wavelength can also refer to the average wavelength of the spectrum of the generated light weighted over the individual spectral intensities.

[0012] Furthermore, the active region of each of the at least one emitter unit is arranged in a resonator. The resonator is designed, in particular, to amplify the light generated in the active region. For example, the resonator can define a radiation direction along which light is emitted by an emitter unit during operation.

[0013] Depending on the wavelength, the semiconductor body can be manufactured as a semiconductor layer sequence based on various semiconductor material systems. For long-wave, infrared to red radiation, for example, a semiconductor layer sequence based on In x Ga y Al 1-xy As is suitable; for red to yellow radiation, for example, a semiconductor layer sequence based on In x Ga y Al 1-xy P is suitable; and for short-wave visible radiation, i.e., particularly in the green to blue light range, and / or for UV radiation, for example, a semiconductor layer sequence based on In x Ga y Al 1-xy N is suitable, where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1 apply in each case.

[0014] In particular, the semiconductor body can comprise or consist of a semiconductor layer sequence, particularly preferably an epitaxially grown semiconductor layer sequence. The semiconductor body can in particular be applied to a substrate. For this purpose, the semiconductor layer sequence can be grown on a growth substrate using an epitaxial process, for example metal-organic vapor phase epitaxy (MOVPE) or molecular beam epitaxy (MBE), and provided with electrical contacts. By singulating the growth substrate with the grown semiconductor layer sequence, a plurality of light-emitting semiconductor chips can be produced. Furthermore, the semiconductor body can be transferred to a carrier substrate before singulation, and the growth substrate can be thinned or removed entirely. The substrate can comprise a semiconductor material, for example a compound semiconductor material system mentioned above.In particular, the substrate may comprise sapphire, GaAs, GaP, GaN, InP, SiC, Si and / or Ge or be made of such a material.

[0015] The semiconductor body, and in particular the at least one emitter unit, can have, for example, a conventional pn junction, a double heterostructure, a single quantum well structure (SQW structure), or a multiple quantum well structure (MQW structure) as the active region. Furthermore, cascades of type II junctions (ICL: "interband cascade laser") or transitions only in the conduction band (QCL: "quantum cascade laser") are also possible. In addition to the active region, the semiconductor body can comprise further functional layers and functional regions, such as p- or n-doped charge carrier transport layers, i.e., electron or hole transport layers, undoped or p- or n-doped confinement, cladding, or waveguide layers, barrier layers, planarization layers, buffer layers, protective layers, and / or electrical contact points such as electrode layers, as well as combinations thereof.In addition, additional layers, such as buffer layers, barrier layers and / or protective layers, can also be arranged perpendicular to the growth direction of the semiconductor body, for example around the semiconductor body, for example on the side surfaces of the semiconductor body.

[0016] For example, the active region of each of the emitter units can be designed as a laser medium in which, during operation in conjunction with a suitable resonator, a population inversion is generated. Due to the population inversion, the light in the active region is generated by stimulated emission, which leads to the formation of laser light. Because the light is generated by stimulated emission, the laser light, in contrast to light generated by spontaneous emission, generally has a very long coherence length, a very narrow emission spectrum and / or a high degree of polarization. The laser light generated in the active region forms one or more standing waves within the respective resonator corresponding to a respective length of the resonator. For this purpose, the length of the respective resonator can generally be an integer multiple of half the wavelength of the light generated in the active region during operation.

[0017] According to a further embodiment, the resonator of each of the emitter units has an output side and a rear side. In particular, the output side and the rear side can be formed by opposing side surfaces of the semiconductor body. An emitter unit can emit light via the output side during operation. For this purpose, the output side can be anti-reflective or, preferably, partially mirrored. The rear side can be designed such that no light, or at least less light, is emitted than via the output side. The rear side can thus be fully mirrored or partially mirrored, for example. Furthermore, it is also possible for the rear side to be anti-reflective.

[0018] "Anti-reflective" here and below can mean that reflection is kept to a minimum, which can correspond to a reflection coefficient of less than or equal to 5%, less than or equal to 2%, or preferably less than or equal to 1%. "Fully mirrored" here and below can mean that transmission is kept to a minimum, which can correspond to a reflection coefficient of greater than or equal to 95%, greater than or equal to 98%, or preferably greater than or equal to 99%. "Partially mirrored" here and below can mean that a reflection coefficient lies between the aforementioned values ​​for anti-reflective and fully mirrored. Terms such as "anti-reflective," "partially mirrored," "fully mirrored," "reflective," etc., refer above and below, unless otherwise stated, to the light generated in the active region of the emitter units.

[0019] According to a further embodiment, the emission directions of the emitter units point in the same direction. The emitter units of the light-emitting semiconductor chip thus emit light in the same direction during operation. Furthermore, the emitter units can particularly preferably be formed next to one another in the semiconductor body perpendicular to the emission direction, so that the output side and the rear side of the emitter units can preferably be formed by identical side surfaces of the semiconductor body.

[0020] According to a further embodiment, the active region of each emitter unit is completely penetrated by at least one recess in the semiconductor body. This can mean that each emitter unit has at least one recess that completely penetrates the active region. In other words, the active region of each emitter unit is interrupted by a recess. The at least one recess is formed, for example, as a gap or slit and particularly preferably has a main extension direction that is non-parallel and preferably perpendicular to the emission direction.

[0021] According to a further embodiment, each of the emitter units has a recess that is separate from the recesses of the other emitter units. In other words, the semiconductor body has separate recesses, with the active region of each emitter unit being penetrated by a dedicated recess. Alternatively, the semiconductor body can also contain a recess that extends through the active regions of two or more, and preferably all, emitter units. In the latter case, all active regions of the light-emitting semiconductor chip can thus be penetrated by a single recess.

[0022] The embodiments and features for the at least one recess described below relate both to the case where each of the emitter units has a dedicated recess, and to the case where a common recess extends through the active regions of more than one emitter unit. Thus, the at least one recess mentioned below can refer to a recess dedicated to each emitter unit or to a common recess.

[0023] According to a further embodiment, for each emitter unit, the at least one recess has a first side surface and a second side surface opposite the first side surface. The first and second side surfaces are arranged one behind the other in the radiation direction and are thus those side surfaces of the at least one recess by which the at least one recess is delimited along the radiation direction. For example, the recess has a rectangular base surface. For example, the first side surface and the second side surface run parallel to the main direction of extension. Furthermore, the recess can have, for example, a wedge-shaped and / or an at least partially rounded base surface. For this purpose, at least one side surface can run at least partially obliquely to the main direction of extension and / or at least partially curved.

[0024] For each emitter unit, the at least one recess in the region of the active region has a recess width that is measured along the emission direction. In particular, the recess width can thus be measured in a direction that is perpendicular or substantially perpendicular to the main extension direction of the recess. In the case of a recess with a non-rectangular base area, the recess width can preferably be a mean width that is averaged over the region in which light is generated in the respective emitter unit during operation. For each emitter unit, the recess width is preferably greater than or equal to 100 nm, greater than or equal to 300 nm, greater than or equal to 500 nm, and less than or equal to 20 µm, less than or equal to 10 µm, or less than or equal to 5 µm.

[0025] According to a further embodiment, the recess widths of the emitter units are at least partially different. In other words, at least one first emitter unit has a first recess width and at least one second emitter unit has a second recess width, wherein the first and second recess widths are different. In the case of more than two emitter units, the respective recess widths are preferably in pairs and thus all different. Furthermore, it is also possible for groups of two, three or more emitter units, for example pairs or triples of emitter units, to have the same recess width, but for the recess widths to differ from group to group. The groups can have the same or different numbers of emitter units.Thus, for example, it may also be possible for the majority of emitter units to comprise a group of multiple emitter units, each with the same recess width, while the remaining emitter units of the majority of emitter units have recess widths that differ from one another. Multiple emitter units in a group can, for example, amplify the respective emission spectrum in the overall spectrum, thereby improving color rendering. In the case of separately formed recesses for the emitter units, each of the recesses can particularly preferably be formed with a recess width that differs from the recess widths of the other emitter units.In the case of a recess which extends through the active regions of several or preferably all emitter units, the recess width of the at least one recess can increase continuously or in steps from emitter unit to emitter unit.

[0026] The recess widths of the emitter units may differ by an amount that is greater than or equal to 1 nm, or greater than or equal to 2 nm, or greater than or equal to 5 nm, or greater than or equal to 10 nm. Furthermore, the recess widths of the emitter units may differ by an amount that is less than or equal to 2 µm, or less than or equal to 1 µm, or less than or equal to 500 nm, or less than or equal to 200 nm, or less than or equal to 100 nm, or less than or equal to 90 nm, or less than or equal to 75 nm, or less than or equal to 60 nm, or less than or equal to 50 nm. Furthermore, the recess widths of the emitter units may differ by an amount that is greater than or equal to 1% or greater than or equal to 2% or greater than or equal to 5% or greater than or equal to 10% and less than or equal to 25% or less than or equal to 20% or greater than or equal to 15% or less than or equal to 10% of the characteristic wavelength of the light generated in the emitter units during operation.

[0027] According to a further embodiment, the light-emitting semiconductor chip has at least three emitter units, wherein the recess widths of the emitter units differ equidistantly from one another. In other words, the light-emitting semiconductor chip can have a first emitter unit with a first recess width, a second emitter unit with a second recess width, and a third emitter unit with a third recess width. The difference between the first and second recess widths, in the case of an equidistant difference, is equal to the difference between the second recess width and the third recess width. In the case of a fourth emitter unit with a fourth recess width, the difference between the third and fourth recess widths is equal to the two aforementioned differences. If more than four emitter units are present, the aforementioned preferably applies analogously.

[0028] In the light-emitting semiconductor chip described here, at least one recess, for example in the form of a slot, is introduced for each emitter unit. The at least one recess can be defined, for example, by a photographic technique and produced by plasma etching and / or wet-chemical etching. In particular, all recesses of the semiconductor body can be produced together in the same process steps. The at least one recess in the active region of each emitter unit can achieve a wavelength-dependent reflectivity, with the reflection spectrum being influenced by the recess width, i.e., the slot width.

[0029] In a light-emitting semiconductor chip with multiple emitter units, all emitter units would typically have the same wavelength with respect to the light they generate, given the same operating parameters. However, if these emitter units are to have emission wavelengths that differ from one another by a certain amount, this can be achieved by varying the recess width from emitter unit to emitter unit, as described above. For example, the recess width can become increasingly larger from a first emitter unit to a last emitter unit. This shifts the reflection maximum, forcing the various emitter units to operate at different wavelengths. The operating parameters—in the case of a laser light source, the laser parameters such as threshold, slope, and voltage—do not change significantly.For all the following embodiments, the spectral adaptation of the emitter units by changing the recess width is technically easy to implement, but the operating parameters are at least substantially not affected.

[0030] For each emitter unit, the at least one recess can preferably be provided and configured to electrically and / or optically isolate different segments of the emitter units of the semiconductor body from one another. The segments of the emitter units can have the same or different functionalities.

[0031] According to a further embodiment, for each emitter unit, the at least one recess has at least one coating that specifies a reflectivity of the recess for the light generated in the active region. In other words, by means of the coating, which can be formed, for example, in the form of one or more layers on at least one or more side surfaces of the at least one recess and / or as a filling, a desired reflectivity of the at least one recess for the light generated in the active region of the respective emitter unit can be set. Alternatively, the at least one recess for one or more or all emitter units can also be free of a coating. The reflectivity of the recess can be set for each emitter unit, in particular, such that the at least one recess is anti-reflective, partially mirrored, or fully mirrored as described above.Particularly preferably, the emitter units have the same coating. Particularly preferably, in the case of a coating in the at least one recess, the reflectivity of the at least one recess with the coating is less than or equal to 99.9% and greater than or equal to 80%.

[0032] According to a further embodiment, for each emitter unit, the first side surface has a first coating that specifies a reflectivity for the light generated in the active region. Alternatively or additionally, the second side surface has a second coating that specifies a reflectivity for the light generated in the active region. Particularly preferably, the emitter units have the same coating, i.e., the same first coating and / or the same second coating.

[0033] According to a further embodiment, the first coating and the second coating are identical. Alternatively, the first and second coatings can also be designed differently from one another.

[0034] All features and embodiments described in connection with the first coating can also be implemented in the second coating, and vice versa. In particular, the features and embodiments described above and below for the coating can be the same for all emitter units, so that the emitter units preferably differ only in the recess width.

[0035] As previously mentioned, the first coating and / or the second coating advantageously set the reflectivity for the light of the active region of each of the emitter units to a predetermined value. For example, the first coating specifies a different reflectivity for the light generated in the active region than the second coating. For example, the first coating is designed to be low-reflective, while the second coating is designed to be highly reflective. Likewise, it is possible for the first coating to be highly reflective, while the second coating is designed to be low-reflective. In this way, electrical and / or optical isolation of different segments of the emitter units of the semiconductor body from one another can be achieved.

[0036] The term "highly reflective" in this context specifically means that an element so designated reflects at least 20%, at least 40%, at least 50%, or at least 80% of the light generated in the active region. The term "low-reflective" in this context specifically means that an element so designated reflects at most 20%, at most 5%, at most 2%, and at least 0.1% or at least 1% of the light generated in the active region.

[0037] According to a further embodiment, the first coating is formed as a first layer sequence with a plurality of individual layers. For example, the individual layers are formed from two different materials and arranged alternately. More than two different materials can also be used for the individual layers. Alternatively or additionally, the second coating can be formed as a second layer sequence with a plurality of individual layers. For example, the individual layers can have a thickness of λ / 2 or λ / 4 or multiples thereof, based on the light generated in the active region, where λ can denote the characteristic wavelength of the light generated in the active region.

[0038] Preferably, the first coating and / or the second coating comprises a dielectric material or is formed from a dielectric material. For example, the individual layers comprise a dielectric material or are formed from a dielectric material. Suitable dielectric materials include, for example, compounds from the group of oxides or nitrides or oxynitrides of Al, Ce, Ga, Hf, In, Mg, Nb, Rh, Sb, Si, Sn, Ta, Ti, Zn, and Zr.

[0039] For example, the first layer sequence and the second layer sequence are formed from individual layers of the same materials and with the same sequence, wherein a thickness of the first layer sequence in the region of the first side surface and a thickness of the second layer sequence in the region of the second side surface are the same or particularly preferably different from one another.

[0040] According to a further embodiment, the thickness of the first coating in the region of the first side surface to a thickness of the second coating in the region of the second side surface has a ratio of between 1:1 and 1:20 inclusive, preferably between 1:1 and 1:10 inclusive, particularly preferably between 1:1.5 and 1:4.5 inclusive.

[0041] According to a further embodiment, the thickness of the second coating in the region of the second side surface to a thickness of the first coating in the region of the first side surface has a ratio of between 1:1 and 1:20 inclusive, preferably between 1:1 and 1:10 inclusive, particularly preferably between 1:1.5 and 1:4.5 inclusive.

[0042] According to a further embodiment, the second layer sequence is formed identically to the first layer sequence except for an additional symmetry-breaking layer. The symmetry-breaking layer can be a single layer or a layer sequence. Alternatively, it is also possible for the first layer sequence to be formed identically to the second layer sequence except for an additional symmetry-breaking layer. In particular, a different formation of the first layer sequence and the second layer sequence, for example by incorporating a symmetry-breaking layer and in particular a symmetry-breaking layer sequence into one of the two layer sequences, leads to different optical properties of the first coating and the second coating.

[0043] For example, the first coating and the second coating for each emitter unit completely fill the at least one recess. Furthermore, it is also possible for a region of the recess between the first coating and the second coating to remain free of the first coating and the second coating. The region of the recess that remains free of the first coating and the second coating can be filled with a further material, which can also be referred to as a filling and which is preferably formed with or from a dielectric such as silicon dioxide, titanium dioxide, silicon nitride. In this way, a loss of light due to large differences in refractive index between the semiconductor material and the dielectric can be at least reduced during light coupling between the regions separated by the at least one recess.

[0044] According to a further embodiment, the light-emitting semiconductor chip comprises a semiconductor body with a plurality of emitter units, each formed with a first segment and a second segment, wherein the first segment is electrically and / or optically insulated from the second segment by the at least one recess. In particular, the emitter units can be formed identically with respect to the segments.

[0045] The first segment and the second segment, for example, have different functionalities. Furthermore, it is also possible for multiple segments of an emitter unit to have the same functionality. The first segment and the second segment are particularly preferably arranged along the emission direction of the respective emitter unit. For example, a first contact point is applied to the first segment and a second contact point to the second segment. The two contact points are configured to electrically contact the two segments independently of one another.

[0046] Each of the emitter units can also have more than two segments. For the sake of simplicity, only an emitter unit with two segments will be discussed in detail below. All embodiments and features disclosed in connection with the first and second segments can also be implemented in further segments and, in particular, for all emitter units. Depending on the functionality of the segments, at least one recess can be arranged in the rear side region and / or at least one recess can be arranged in the output side region of each emitter unit.

[0047] According to a further embodiment, the first segment has the light-generating part and the second segment has a modulation element which is designed to modulate an intensity of the light generated in the active region. For example, light is generated in the first segment, preferably laser light, which enters the modulation element through the at least one recess. The modulation element can be adjusted from being permeable to being absorbent for the light by varying the current supply, in particular by an electrical control including reverse voltage and forward current, via the second contact point. If the modulation element is designed to be absorbent for the light from the light-generating part, the modulation element is designed as an absorber element.

[0048] According to a further embodiment, the first segment and the second segment are electrically separated from each other and the second segment has an electrical switching element which is configured to switch the emitter unit on and off.

[0049] According to a further embodiment, at least one or more or all emitter units comprise a segment with one or more of the following elements: photodiode, passive waveguide, active waveguide, beam splitter, beam combiner, lens, wavelength-selective element, phase-shifting elements, frequency doubler, taper, amplifier, converter, transistor.

[0050] As an alternative to being designed as a laser light source, the emitter units can also be designed as a superluminescent diode, for example, in which the light generated in the active region is amplified within a resonator, but full laser operation is not achieved.

[0051] According to a further embodiment, a semiconductor body is provided, for example by growth, comprising an active layer with a plurality of active regions configured and provided to generate light during operation and arranged in a resonator. Each of the active regions is associated with an emitter unit, so that the semiconductor body has a plurality of monolithically integrated emitter units, each of which has an active region.

[0052] Furthermore, at least one recess is created in the semiconductor body in each of the emitter units, wherein in each of the emitter units the at least one recess completely penetrates the respective active region. In each emitter unit, the at least one recess has a first side surface and a second side surface, wherein the first side surface is arranged opposite the second side surface. For example, in each emitter unit the at least one recess is created by etching. As described above, in each of the emitter units the at least one recess has a recess width in the emission direction, which can particularly preferably correspond to a distance between the first and second side surfaces from one another in the emission direction. The emitter units are manufactured such that the recess widths differ.Particularly preferably, this can be produced in a common method step both in the case where each emitter unit has a specially assigned recess and in the case where a recess extends through the active regions of several emitter units.

[0053] According to a further embodiment, a coating is applied for each emitter unit, particularly preferably in a common process step, for example a first coating on the first side surface and / or a second coating on the second side surface.

[0054] For example, it is also possible for the second side surface of the at least one recess to be provided with a protective layer for each emitter unit. In a next step, the first side surface of the at least one recess can be provided with the first coating for each emitter unit, and the protective layer can be removed again, so that the semiconductor body is freely accessible in the region of the second side surface. A photoresist layer, for example, can be used as the protective layer.

[0055] For example, the first coating and / or the second coating can be deposited by means of vapor deposition, sputtering, atomic layer deposition (ALD) or chemical vapor deposition (CVD).

[0056] In evaporation and sputtering, the surface to be coated is provided in a volume. At least one starting material is also provided in the gas phase within the volume. The starting material condenses directly onto the surface, forming a coating on the surface. In evaporation, the starting material is converted into the gas phase by applying heat, whereas in sputtering, the starting material is converted into the gas phase by ion bombardment. Evaporation and sputtering are generally directional deposition processes in which more material is deposited along one preferred direction than along the others.

[0057] In the CVD process, the surface to be coated is also provided in a volume. At least one starting material is also provided within this volume, from which a solid coating is deposited on the surface to be coated through a chemical reaction. Typically, the volume contains at least a second starting material with which the first starting material chemically reacts to form the solid coating on the surface. The CVD process is thus characterized by at least one chemical reaction on the surface to be coated to form the CVD layer. In chemical vapor deposition, more than two starting materials can also be used.

[0058] Atomic layer deposition refers to a process in which the first gaseous starting material is introduced into the volume containing the surface to be coated, so that the first gaseous starting material adsorbs onto the surface. After the surface has been preferably completely or almost completely covered with the first starting material, the portion of the first starting material that is still in gaseous form or not adsorbed onto the surface is generally removed from the volume, and the second starting material is introduced. The second starting material is designed to chemically react with the first starting compound adsorbed onto the surface to form a solid coating.

[0059] The CVD process and the ALD process are generally non-directional or so-called isotropic deposition processes in which the material is deposited evenly along all directions.

[0060] Furthermore, the first coating may be provided with an additional protective layer, at least in the area of ​​the first side surface. This step is generally performed after the first coating has been applied to the first side surface. The second side surface is particularly preferably left free of the protective layer.

[0061] Furthermore, the second side surface can be coated with the second coating and the additional protective layer removed again, leaving the first coating freely accessible in the area of ​​the first side surface. This preferably occurs after the second coating has been applied. Using the two protective layers, two different coatings can advantageously be created.

[0062] As described above, the first coating and the second coating may be applied to the first side surface and the second side surface in sequential steps.

[0063] According to a further embodiment, the first coating and the second coating are applied simultaneously to the first side surface and the second side surface. In this embodiment of the method, the first coating is preferably formed as a first layer sequence of a plurality of individual layers, and the second coating is formed as a second layer sequence of a plurality of second individual layers. Particularly preferably, the first layer sequence and the second layer sequence in this embodiment of the method comprise individual layers of the same materials and in the same sequence. However, the first layer sequence and the second layer sequence particularly preferably differ in their thicknesses.Preferably, a thickness of the first layer sequence in the region of the first side surface to a thickness of the second layer sequence in the region of the second side surface has a ratio of between 1:1 and 1:20 inclusive, preferably between 1:1 and 1:10 inclusive, particularly preferably between 1:1.5 and 1:4.5 inclusive.

[0064] To produce such coatings, a deposition method is preferably used in which a preferred direction for applying the first coating and the second coating forms a predetermined angle with a main extension plane of the semiconductor body. The angle is preferably not equal to 90°. This makes it possible to achieve a first coating and a second coating whose thicknesses differ from one another on the first side surface and the second side surface, but which comprise the same materials and sequences of individual layers. In other words, a directed deposition method, such as thermal evaporation or sputtering, is particularly preferably used.

[0065] According to a further embodiment, prior to the application of the first coating and the second coating, a shading element is applied to a region of a main surface of the semiconductor body that directly adjoins the first side surface of the at least one recess for each emitter unit, such that the thickness of the first coating in the region of the first side surface differs from the thickness of the second coating in the region of the second side surface. Thus, a shading element can also be used to simultaneously apply a first coating and a second coating to the side surfaces, which have different thicknesses at least in the region of the first side surface and the second side surface.

[0066] According to a further embodiment, the first coating is formed as a first layer sequence with a plurality of individual layers. According to a further embodiment of the method, the second coating is formed as a second layer sequence with a plurality of individual layers.

[0067] The at least one recess can be arranged for each emitter unit in the rear side region or in the region of the output side. "Rear side region" can mean, in particular, that the at least one recess is arranged closer to the rear side than to the output side along the emission direction. "Rear side region" can mean, in particular, that the at least one recess is arranged closer to the output side than to the rear side along the emission direction.

[0068] In a preferred embodiment, the at least one recess for each emitter unit is preferably formed in the region of the rear side of the resonator, so that the rear-side reflectivity can be modulated. A targeted coating, which can advantageously be applied in the wafer assembly, creates the appropriate reflectivity and modulation depending on the recess width. Because the at least one recess is formed in the region of the rear side, the light coupled out on the coupling-out side does not have to propagate through the at least one recess, resulting in better steel quality.

[0069] Alternatively or additionally, at least one recess can also be formed in the region of the output coupling side of each emitter unit, whereby this also depends on the recess width. This can be particularly advantageous for multi-section components, while the design on the rear side is also possible for "simple" laser resonators.

[0070] Furthermore, it is also possible to form at least one recess in the rear area and at least one recess in the output side area of ​​each emitter unit in order to enhance the modulation effect or to achieve even narrower reflection maxima. Since the maxima of the reflection spectrum have a certain spectral width, a significantly narrower wavelength window within which the emitter units must emit can be achieved by using two slightly shifted spectra in the rear area and in the output side area. Advantageously, the functionality is not dependent on the absolute recess width of the emitter units, but only on the relative differences in recess width between the emitter units, since the modulation repeats periodically with the recess width. This means that production fluctuations in the recess width are not critical and this solution is technically very simple to implement.

[0071] With the light-emitting semiconductor chip described here, it may thus be possible to achieve a wavelength variation across the individual emitter units of a light-emitting semiconductor chip with a defined shift, which keeps the operating parameters approximately the same. Such a solution can also be applicable to special components such as multi-segment lasers, since the formation of multiple segments can expand the functionality of the emitter units with regard to optimal usability in optical devices. For example, a light-emitting semiconductor chip with emitter units can be designed, each with an amplifier section and a modulator section, in order to be able to continuously regulate the light output even for low output powers, which can be very advantageous for high-contrast displays.

[0072] The light-emitting semiconductor chip described here can be used, for example, in one of the following applications: augmented reality, virtual reality, pico-projection, LIDAR ("light detection and ranging"), and communication.

[0073] The light-emitting semiconductor chip described here makes it particularly possible to easily implement different wavelengths in adjacent emitter units, something that would otherwise be difficult to achieve. The simplicity of the process allows for cost-effective production. The different wavelengths can significantly improve image quality, for example, in AR / VR applications. The described method is insensitive to process fluctuations, allowing high and stable manufacturing yields to be achieved. Due to the stability against process fluctuations, in-situ control is unnecessary, thus saving costs.

[0074] Further advantages, advantageous embodiments and further developments emerge from the exemplary embodiments described below in conjunction with the figures.

[0075] The Figures 1A to 1Eshow schematic representations of a light-emitting semiconductor chip and various stages of a method for producing the light-emitting semiconductor chip and an exemplary emission spectrum according to an embodiment.

[0076] The Figures 2A and 2B show schematic representations of parts of light-emitting semiconductor chips according to further embodiments.

[0077] The Figures 3A to 3D show simulations of the reflectivity R as a function of the wavelength λ for a coating according to an embodiment.

[0078] The Figures 4A and 4B show simulations of the reflectivity R and the mirror losses L as a function of the wavelength λ for a coating according to an embodiment.

[0079] The Figures 5A and 5Bshow a schematic representation of a part of a light-emitting semiconductor chip and a simulation of the reflectivity R as a function of the wavelength λ for a coating according to an embodiment.

[0080] The Figures 6A and 6B show schematic representations of a light-emitting semiconductor chip according to a further embodiment.

[0081] The Figures 7A and 7B show schematic representations of a light-emitting semiconductor chip according to a further embodiment.

[0082] The Figures 8A and 8B show schematic representations of a light-emitting semiconductor chip according to a further embodiment.

[0083] The Figures 9A and 9B show simulations of the reflectivity R as a function of the wavelength λ for coatings according to further embodiments.

[0084] The Figures 10A to 10Cshow a schematic representation of a part of a light-emitting semiconductor chip as well as simulations of the reflectivity R as a function of the wavelength λ for coatings according to further embodiments.

[0085] The Figures 11A to 11C show simulations of the reflectivity R as a function of the wavelength λ for coatings according to further embodiments.

[0086] The Figures 12A to 12E show simulations of the reflectivity R and the gain G as a function of the wavelength λ as well as of spectral parameters as a function of the recess width A for a coating according to a further embodiment.

[0087] The Figures 13A to 19C show schematic representations of light-emitting semiconductor chips and parts thereof according to further embodiments.

[0088] In the exemplary embodiments and figures, identical, similar, or similarly functioning elements may be provided with the same reference numerals. The illustrated elements and their relative sizes are not to be considered to scale; rather, individual elements, such as layers, components, structural elements, and regions, may be exaggerated for clarity and / or clarity.

[0089] In connection with the Figures 1A to 1E An embodiment of a light-emitting semiconductor chip 100 and method steps for producing the same are shown. Figure 1A shows a top view of the light-emitting semiconductor chip 100. The Figures 1B to 1D show process steps using excerpts and the Figure 1E shows an exemplary emission spectrum of the light-emitting semiconductor chip 100. The following description refers equally to the Figures 1A to 1E .

[0090] The light-emitting semiconductor chip 100, which is designed in particular as a multi-emitter laser light source, has a semiconductor body 1 which has a plurality of emitter units 101. Purely by way of example, Figure 1A four emitter units 101 are indicated, each having an active region 2 in which, during operation, light is generated, which is emitted by the emitter units 101 via an output side 22 along the indicated emission directions 99. The light-emitting semiconductor chip 100 can also have more or fewer emitter units 101.

[0091] The semiconductor body 1 is applied as a semiconductor layer sequence on a substrate 3. For example, the semiconductor body 1 can be grown on the substrate 3 as described in the general part and comprise a material described in the general part. The semiconductor layer sequence and in particular the active region 2, which can comprise, for example, one or, as indicated in the figures, several layers, can be formed as described in the general part. For the sake of clarity, no further individual layers of the semiconductor body 1 are indicated in the figures apart from the active region 2.

[0092] The active region 2 of each of the at least one emitter unit 10 is arranged in a resonator. The resonator is designed, in particular, to amplify the light generated in the active region 2. For example, the resonator and an exemplary ridge waveguide structure 24, which can also be referred to as a ridge, can define the emission direction 99 along which light is emitted by an emitter unit 101 during operation. In the exemplary embodiment shown, the resonator is delimited by a first layer 21 on a rear side and a second layer 23 on the coupling-out side 22, wherein the rear side 20 and the coupling-out side 22 are side surfaces of the semiconductor body 1. For example, the first layer 21 can be a layer or layer sequence that partially or fully mirrors the rear side 20, while the second layer 23 can be a layer or layer sequence that partially mirrors the coupling-out side 22.

[0093] In the semiconductor body 1, a recess 4 is created for each emitter unit 101, which completely penetrates the respective active region 2. In the exemplary embodiment shown, each emitter unit 101 has a dedicated recess 4, which is separate from the recesses 4 of the other emitter units 101. The recesses 4 can penetrate the semiconductor body 1 completely or, as indicated in the figures, partially. In particular, the recesses 4 can extend into a semiconductor layer of the semiconductor body 1 below the active region 2, for example, into a waveguide layer, a cladding layer, or a buffer layer.

[0094] The recesses 4 each have a first side surface 6 and a second side surface 7, which lies opposite the first side surface 6, as well as a bottom surface 11. The recesses 4 are created, for example, by etching, such as plasma etching and / or wet-chemical etching, in a common mask- and photo-based process. For this purpose, one or more etch stop layers can be present in the semiconductor body 1, which can stop an etching process of the recesses 4 and thus define the bottom surface 11. In this way, a depth of the recesses 4 can be determined. The Figure 1C The cross-section of one of the recesses 4 with vertical side walls 6, 7 indicated in a partial view of a sectional representation through the light-emitting semiconductor chip 101 is to be understood purely as an example. The shape of the side walls may differ from the shape shown depending on the etching process.

[0095] The active region 2 of each emitter unit 101 is thus interrupted by a recess 4. The respective recess 4 is formed, for example, as a gap or slot and particularly preferably has a main extension direction that is non-parallel and preferably perpendicular to the emission direction 99, as in Figure 1Dis indicated in a three-dimensional section. The first and second side surfaces 6, 7 are arranged one behind the other, in particular in the radiation direction 99, and are thus, for each emitter unit 101, those side surfaces of the respective recess 4 by which the recess 4 is delimited along the radiation direction 99. For example, the recesses 4 have, as shown, a rectangular base area. The first side surface 6 and the second side surface 7 run parallel to the main extension direction of the respective recess 4. Furthermore, the recesses 4 can, as shown further below, have, for example, a wedge-shaped and / or at least partially rounded base area. For this purpose, at least one of the first and second side surfaces 6, 7 can run at least partially obliquely to the main extension direction and / or at least partially curved.

[0096] For each emitter unit 101, the respective recess 4 in the region of the active region 2 has a recess width A, which is measured along the emission direction 99. In particular, the recess width A can thus be measured in a direction that is perpendicular or substantially perpendicular to the main extension direction of the recess 4. Preferably, for each emitter unit 101, the recess width A is greater than or equal to 100 nm, greater than or equal to 300 nm, greater than or equal to 500 nm, and less than or equal to 20 µm, less than or equal to 10 µm, or less than or equal to 5 µm.

[0097] As in Figure 1A As indicated, the recess widths A of the emitter units 101 are different. In other words, each emitter unit has a recess 4 with a recess width A, wherein the recess widths A differ from one another in pairs.

[0098] The recess widths A of at least two or more or all emitter units 101 can each differ in pairs by an amount that is greater than or equal to 1 nm or greater than or equal to 2 nm or greater than or equal to 5 nm or greater than or equal to 10 nm and that is less than or equal to 2 µm or less than or equal to 1 µm or less than or equal to 500 nm or less than or equal to 200 nm or less than or equal to 100 nm or less than or equal to 90 nm or less than or equal to 75 nm or less than or equal to 60 nm or less than or equal to 50 nm. Furthermore, the recess widths A of the emitter units 101 may differ by an amount that is greater than or equal to 1% or greater than or equal to 2% or greater than or equal to 5% or greater than or equal to 10% and less than or equal to 25% or less than or equal to 20% or greater than or equal to 15% or less than or equal to 10% of the characteristic wavelength of the light generated in the emitter units 101 during operation.

[0099] In a particularly preferred embodiment, the recess widths A of the emitter units 101 are equidistant from each other. This means in the embodiment shown that the difference between the recess widths of the Figure 1A shown two uppermost emitter units 101 is equal to the difference between the recess widths of the Figure 1A shown two middle emitter units 101, which in turn is equal to the difference between the recess widths of the Figure 1A shown two lowest emitter units 101.

[0100] Through the respective recess 4 in the active region 2 of each emitter unit 101, a wavelength-dependent reflectivity can be achieved, wherein the reflection spectrum is influenced by the respective recess width A. By varying the recess widths A, the emitter units can thus emit emission spectra E1, E2, E3 and E4 with different emission wavelengths, as shown for example in Figure 1E is indicated. For a light-emitting semiconductor chip 100 with emission spectra in the visible wavelength range, the spectral spacings of the individual emission spectra E1, E2, E3, E4 can be greater than or equal to + / -0.5 nm, preferably greater than or equal to + / -1.0 nm, and particularly preferably greater than or equal to + / -3 nm by varying the recess width A.

[0101] For applications in other wavelength ranges, for example at shorter wavelengths or in the infrared spectral range, such as for infrared imaging, gas sensing or other applications in which shifted emission wavelengths are relevant in a multi-emitter chip, the relevant wavelength spacing and the total wavelength range to be covered typically scale with the wavelength itself.

[0102] For the present embodiment and for all subsequent embodiments, the spectral adaptation of the emitter units by changing the slot width is technically easy to implement and has virtually no influence on the operating parameters.

[0103] For each emitter unit 101, the respective recess 4 is preferably provided and configured to electrically and / or optically insulate different segments 25, 26 of the emitter units 101 of the semiconductor body 1 from one another. The segments 25, 26 of the emitter units 101 can have the same or different functionalities. Figures 1A and 1C Two segments 25, 26 are indicated, of which a first segment 25 is electrically contacted by means of a first electrical contact point 27, for example in the form of an electrode layer, while the other, second segment 26 remains uncontacted. Alternatively, as described further below, the segments can be contacted separately. Alternatively, the segments can also be short-circuited via a common contact point.

[0104] The position of the recess 4 of each of the emitter units 101 can be located at any point along the total resonator length, but preferably in the region and in particular near the rear side 20, as is the case in the present embodiment, or in the region and in particular near the coupling-out side 22, as described further below.

[0105] By separating the cavities of the emitter units 101 into two segments or, in the case of a formation of multiple recesses 4 per emitter unit 101 as shown below, into more than two segments, the segments can be configured for adjusting different properties of the light-emitting semiconductor chip 100. A non-electrically contacted and thus passive segment can be configured, for example, as a passive mode filter or for spectral broadening, for example, in a superluminescent diode. A separately electrically contacted and thus active segment can be configured as a modulator or dimmer or with another functionality described in the general section.

[0106] In the Figures 2A and 2B schematic representations of parts of emitter units of light-emitting semiconductor chips according to further embodiments are shown, which correspond to the views in the Figures 1B and 1CCompared to the previous embodiment, the emitter units according to the embodiments of the Figures 2A and 2Ba coating in the recesses 4, which specifies a reflectivity of the recesses 4 for the light generated in the respective active region 2. In other words, by means of the coating, which is formed in particular with a first coating 10 and a second coating 13 in the form of one or, as indicated, several layers 12, a desired reflectivity of the recesses 4 for the light generated in the active region 2 of the respective emitter unit can be set. The reflectivity of the recess 4 can be set for each emitter unit in particular such that the respective recess 4 is anti-reflective, partially mirrored, or fully mirrored. Particularly preferably, all emitter units of the light-emitting semiconductor chip have the same coating in the respective recess 4. Particularly preferably, the reflectivity of the recesses 4 with a coating is less than or equal to 99.9% and greater than or equal to 80%.

[0107] As in the Figures 2A and 2B As can be seen, for each emitter unit, the first side surface 6 has a first coating 10 and the second side surface 7 has a second coating 13, which each specify a reflectivity for the light generated in the active region 2. In the embodiments of the Figures 2A and 2B The first coating 10 and the second coating 13 are identical. Alternatively, the first and second coatings 10, 13 can also be designed differently from one another, or a coating can be present only on one of the side surfaces 6, 7.

[0108] Preferably, the first coating 10 and / or the second coating 13 comprises a dielectric material or is formed from a dielectric material. For example, the individual layers 12 comprise a dielectric material or are formed from a dielectric material. Suitable dielectric materials include, for example, compounds from the group of oxides or nitrides or oxynitrides of Al, Ce, Ga, Hf, In, Mg, Nb, Rh, Sb, Si, Sn, Ta, Ti, Zn, and Zr. The thicknesses of the individual layers 12 can, for example, be selected such that they have a thickness of λ / 2 or λ / 4 or multiples thereof, where λ denotes the characteristic wavelength of the light generated in the active region 2.

[0109] For example, the first coating 10 and the second coating 13 completely fill the respective recess 4 for each emitter unit. Furthermore, it is also possible that between the first coating 10 and the second coating 13, a region of the recess 4 remains free of the first coating 10 and the second coating 13, as in Figure 2A The area of ​​the recess 4 which remains free of the first coating 10 and the second coating 13 can continue to be coated as shown in Figure 2BAs indicated, the recess 4 can be filled with a further material, which can be referred to as filling 15 and which is preferably formed with or from a dielectric such as silicon dioxide, titanium dioxide, silicon nitride. Furthermore, the filling 15 can comprise one or more materials that were previously described in connection with the first and second coatings. In this way, a loss of light due to large differences in refractive index between the semiconductor material and the dielectric during light coupling between the segments separated by the at least one recess 4 can be at least reduced. Particularly preferably, the part of the recess 4 that is not filled by the first and second coatings 10, 13 is filled by the filling 15, so that the recess 4 is completely filled.

[0110] In the examples of the Figures 1A to 2BThe recesses 4 are provided with different widths in the rear area. The recesses 4 are preferably at least partially filled with layers that impart highly reflective properties to the recesses 4 and have the different widths described above.

[0111] The rear side preferably has a coating with the previously described first layer, which, for example, has a very low reflectivity, so that back reflections into the resonator can be avoided. The coated recesses 4 themselves can thus serve as a highly reflective facet. Because the second segments 26 to the left of the recesses 4 are not electrically contacted and are thus passive, they are merely an "appendage" and no longer have any influence on the reflectivity due to the anti-reflective coating described. Alternatively, it may also be possible to use the first layer on the rear side as a rear-side mirror with at least partial reflectivity.

[0112] If the recess 4 is filled with layer pairs with individual layers 12 that are at least approximately designed as λ / 4 layers, highly reflective mirrors with strong modulation can be produced. Figures 3A to 3DSimulations of the reflectivity R as a function of the wavelength λ for a coating 10, 13 with the composition given in Table 1 are shown.

[0113] The materials listed in Table 1 and the following tables are purely examples to explain the underlying principles. Alternatively or additionally, other materials mentioned may also be used. In particular, the compositions of the materials may also deviate from a stoichiometric composition. The order of the materials from top to bottom listed in Table 1 and the following tables corresponds to an order along the radiation direction from the first side surface to the second side surface of the recess, with the side surfaces being formed by the semiconductor body, which is therefore listed at the beginning and end of the tables. Table 1 material Thickness (nanometers) Refractive index n semiconductor body 2,5 first coating SiN 62,5 1,8 first coating SiO2 75 1,5 first coating SiN 62,5 1,8 first coating SiO2 75 1,5 first coating SiN 62,5 1,8 first coating SiO2 75 1,5 first coating SiN 62,5 1,8 first coating SiO2 75 1,5 first coating SiN 62,5 1,8 first coating SiO2 75 1,5 first coating SiN 62,5 1,8 first coating SiO2 75 1,5 filling SiN x 1,8 second coating SiO2 75 1,5 second coating SiN 62,5 1,8 second coating SiO2 75 1,5 second coating SiN 62,5 1,8 second coating SiO2 75 1,5 second coating SiN 62,5 1,8 second coating SiO2 75 1,5 second coating SiN 62,5 1,8 second coating SiO2 75 1,5 second coating SiN 62,5 1,8 second coating SiO2 75 1,5 second coating SiN 62,5 1,8 semiconductor body 2,5

[0114] By changing the recess width, the width x of the filling specified in the table changes while the coating remains the same, which shifts the modulations. Figure 3A For a wavelength in the range of 450 nm, the reflectivity R of the filled recess is shown as a function of the wavelength λ for x = 3040 nm, which, for example, means a reflectivity maximum for an indicated wavelength of approximately 446 nm. For x = 3070 nm ( Figure 3B ) and x = 3100 nm ( Figure 3C) the maximum shifts to higher wavelengths, as indicated by the respective arrow. The shift is periodic, so in the example shown, for x = 3165 nm, a maximum is again at the same position as for x = 3040 nm, as in 3D figure is shown. Due to this periodicity, the absolute recess width is uncritical, since the relative changes in the recess width cause the displacement.

[0115] In the Figures 4A and 4B Simulations of the reflectivity R and the mirror losses L as a function of the wavelength λ for a coating according to a further embodiment are shown. The mirror losses L are calculated according to the formula L = -ln((R1×R2) / (2×L)), where R1 is the reflectivity of the recess according to Figure 4A , R2 is the reflectivity of the mirror formed by the second layer on the output side and L is the resonator length. For the simulation in Figure 4Bthe values ​​R2 = 50% and L = 600 µm were assumed.

[0116] As in Figure 4B As can be easily seen, even small changes in the reflectivity of the recess result in significant changes in the mirror losses L, so that the light generated in the active region is forced to the wavelength with the lowest mirror losses, since a laser usually starts lasing at the wavelength with the lowest losses. Therefore, the wavelength of the light generated in the active region of an emitter unit shifts with the Figures 3A to 3D The shift in the reflection spectrum shown by changing the recess width. This principle applies regardless of whether the recesses are located on the rear side or on the output side.

[0117] By using suitable coatings, different reflectivities, modulation depths and periodicities can be adjusted. Figures 5A and 5Bshow, according to a further embodiment, a schematic representation of a part of an emitter unit of a light-emitting semiconductor chip with different first and second coatings 10, 13 and a filling 15 as well as a simulation of the reflectivity R as a function of the wavelength λ for such a coating. Purely by way of example and for the sake of clarity, Figure 5A only three individual layers 12 are shown for the first and second coating.

[0118] Compared to the previous exemplary embodiments, the second coating 13 on the second side surface 7 is half as thick as the first coating 10 on the first side surface 6. For this purpose, for example, the first coating 10 and the second coating 13 can be deposited separately from one another and thus one after the other. Suitable method steps as described in the general part can be used for this purpose. Furthermore, the first coating 10 and the second coating 13 can also be deposited simultaneously. For this purpose, for example, a deposition method is used which has a preferred direction 16 which forms an angle α with a main extension plane 17 of the semiconductor body 1. Thus, the first coating 10 and the second coating 13 are deposited simultaneously, wherein the second coating 13 has a different thickness, at least on the second side surface 7, than the first coating 10 on the first side surface 6.This is achieved by self-shadowing of the recess 4 during deposition due to the preferred direction 16. Sputtering or vapor deposition, for example, are suitable as directed deposition processes. By appropriately selecting the angle α, the thickness ratio between the first and second coatings 10, 13 on the side surfaces 6, 7 can be adjusted.

[0119] The first and second coatings 10, 13 produced in this way each comprise a layer sequence of individual layers 12 of the same material and in the same sequence. The first coating 10 and the second coating 13 differ only in their thickness on the first side surface 6 and the second side surface 7 of the recess 4. The remaining gap is filled as in the exemplary embodiment of the Figure 2B filled with a filling 15.

[0120] In Figure 5Ba simulation of the reflectivity R as a function of the wavelength λ for such a coating with the first and second coatings 10, 13 and the filling 15 with the composition given in Table 2 is shown. Table 2 material Thickness (nanometers) Refractive index n semiconductor body 2,5 first coating SiO2 73 1,5 first coating TiO 47 2,2 first coating SiO2 79 1,5 first coating TiO 50 2,2 first coating SiO2 75 1,5 first coating TiO 49 2,2 first coating SiO2 72 1,5 first coating TiO 52 2,2 first coating SiO2 78 1,5 first coating TiO 44 2,2 filling TiO 3000 2,2 second coating TiO 22 2,2 second coating SiO2 39 1,5 second coating TiO 26 2,2 second coating SiO2 36 1,5 second coating TiO 24,5 2,2 second coating SiO2 37,5 1,5 second coating TiO 25 2,2 second coating SiO2 39, 5 1,5 second coating TiO 23,5 2,2 second coating SiO2 36, 5 1,5 semiconductor body 2,5

[0121] In the Figures 6A and 6Bschematic representations of a light-emitting semiconductor chip 100 according to a further exemplary embodiment are shown, in which, in addition to the first segment 25, the second segment 26 of each emitter unit 101 is also electrically contacted by means of second electrical contact points 28, for example electrode layers, compared to previous exemplary embodiments. For example, the second segments 26 of the emitter units 101 can be designed and used as an integrated photodiode. For this purpose, it can be advantageous if the reflectivity of the recesses 4 is set, for example, to less than or equal to 99%, preferably less than or equal to 97%, and particularly preferably less than or equal to 95%, by means of a suitable coating. The first layer 21 on the rear side 20 is particularly preferably an anti-reflective coating in order to avoid back reflections in the direction of the first segments 25.

[0122] The Figures 7A and 7Bshow schematic representations of a light-emitting semiconductor chip 100 according to a further embodiment, in which, in comparison to the previous embodiments, the recesses 4 are arranged with different recess widths in the region of the coupling-out side 22.

[0123] The recesses 4 are unfilled as shown or can alternatively be filled, for example, with a material with a specific refractive index. The second layer 23 on the output side 22 is formed by a coating with very low reflectivity, which prevents back reflections into the semiconductor body 1.

[0124] In the embodiment shown here, the second segments 26 are not electrically contacted on the output side 22 and are therefore passive. Alternatively, as shown in the Figures 8A and 8B However, as shown, these can also be electrically contacted separately by means of second electrical contact points 28.

[0125] Due to the non-reflective second layer 23, the second segments 26 have no influence on the reflectivity at the output side 22. Rather, the reflectivity is defined by the recesses 4. By effectively "shifting" the position of the output reflectivity from the facet of the semiconductor body 1 on the output side 22 of the light-emitting semiconductor chip 100 into the recesses 4, it can advantageously be achieved that the second segments 26 can be used with additional properties. These can, for example, be used, optionally in combination with changes to the ridge waveguide geometry in the second segments 26, as mode filters or for spectral broadening or as modulators, etc.

[0126] In the simplest case, the modulation can be realized via an unfilled or a material-filled recess 4 in the active regions 2 of the emitter units 101. This allows, for example, reflectivities of less than approximately 50% in the AlInGaN material system with air-filled recesses 4, as in Figure 9A in another simulation of an air-filled cavity with a cavity width of 5000 nm. By filling it with a material with a higher refractive index, a lower reflectivity can be achieved, as shown in Figure 9Bshown in another simulation with a similar recess filled with SiO 2 with a refractive index of 1.5. Since the modulations are relatively far apart in the case of air fillings, a large recess width may be necessary to achieve the required smaller modulation spacing. However, since this entails a reduction in coupling efficiency and some applications require reflectivities greater than 50% or which cannot be achieved with a single filler material, multilayer coatings can be used as an alternative, for example, as described below.

[0127] In Figure 10A is a schematic partial representation of an emitter unit of a light-emitting semiconductor chip according to the embodiment of the Figures 7A and 7B shown, where unlike in the embodiment of the Figures 7A and 7BIn addition, such a coating in the form of a first coating 10 and a second coating 13 is applied in the recesses 4. The Figures 10B and 10C show simulations of the reflectivity R as a function of the wavelength λ for coatings according to Tables 3 and 4. Table 3 material Thickness (nanometers) Refractive index n semiconductor body 2,5 first coating TiO 34 2,2 first coating SiO2 148 1,5 first coating TiO 33 2,2 first coating SiO2 94 1,5 first coating TiO 98 2,2 filling TiO 2000 2,2 second coating TiO 68, 6 2,2 second coating SiO2 65, 8 1,5 second coating TiO 23, 1 2,2 second coating SiO2 103,6 1,5 second coating TiO 23,8 2,2 semiconductor body 2,5 Table 4 material Thickness (nanometers) Refractive index n semiconductor body 2,5 first coating SiO2 24 1,5 first coating TiO 79 2,2 first coating SiO2 70 1,5 first coating TiO 54 2,2 first coating SiO2 39 1,5 first coating TiO 74 2,2 first coating SiO2 157 1,5 filling TiO 3050 2,2 second coating SiO2 78,5 1,5 second coating TiO 37 2,2 second coating SiO2 19, 5 1,5 second coating TiO 27 2,2 second coating SiO2 35 1,5 second coating TiO 39, 5 2,2 second coating SiO2 12 1,5 semiconductor body 2,5

[0128] As in Figure 10B As can be seen, with the coating specified in Table 3, in which the thickness of the second coating in the area of ​​the second side surface to the thickness of the first coating in the area of ​​the first side surface has a ratio of 7:10, a similar modulation height and modulation width can be achieved as with the coating in connection with the Figures 7A, 7B and 9AThe air-filled recess shown can be achieved, but with a significantly smaller recess width. This results in lower coupling losses and thus better laser performance.

[0129] As in Figure 10C As can be seen, with the coating specified in Table 4, in which the thickness of the second coating in the area of ​​the second side surface to the thickness of the first coating in the area of ​​the first side surface has a ratio of 1:2, a reflectivity of about 75% can be achieved, which would not be possible with purely air-filled recesses. Based on the results obtained in conjunction with the Figures 10B and 10C From the coatings explained above, it can be seen that any desired reflectivity can be set using a coating in the recesses.

[0130] The modulation distance, i.e., the distance between reflection maxima, can be adjusted, for example, via the refractive index of the filling. The higher the refractive index n of the filling, the smaller the modulation distance, as this is proportional to λ 2< / (2×n×B), where B is the width of the filling. Figures 11A to 11C show this relationship in simulations of the reflectivity R as a function of the wavelength λ for coatings according to further embodiments with the composition given in Table 5. The refractive index of the filling is n = 1.5 ( Figure 11A ), n = 1.8 ( Figure 11B ) and n = 2.2 ( Figure 11C). Due to the variation in the refractive index n of the filling, no exemplary material is given in Table 5. Depending on the desired reflectivity, this can be specifically selected by a specialist. For example, for the refractive index n = 2.2 TiO . In this case, the composition of the coating and thus the Figure 11C Reflectivity shown of the composition of the coating and the reflectivity associated with the Figure 10B For the refractive indices n = 1.5 and n = 1.8, for example, SiO 2 and SiN can be chosen. Table 5 material Thickness (nanometers) Refractive index n semiconductor body 2,5 first coating TiO 34 2,2 first coating SiO2 148 1,5 first coating TiO 33 2,2 first coating SiO2 94 1,5 first coating TiO 98 2,2 filling 2000 n second coating TiO 68,6 2,2 second coating SiO2 65,8 1,5 second coating TiO 23, 1 2,2 second coating SiO2 103,6 1,5 second coating TiO 23,8 2,2 semiconductor body 2,5

[0131] From the dependence λ 2 < / (2×n×B) of the modulation spacing, it is also evident that with increasing fill width, the spacing of the reflection maxima decreases. The position of the maxima repeats itself proportionally to λ / (2×n), and the shift of the maxima with fill width B is proportional to λ / B. The larger the fill width and thus the recess width for a fixed first and second coating, the smaller the shift of the maxima with changing slot width.

[0132] Table 6 shows the structure of the coating shown in Table 3, whereby the width B of the filling is variable compared to Table 3. Table 6 material Thickness (nanometers) Refractive index n semiconductor body 2,5 first coating TiO 34 2,2 first coating SiO2 148 1,5 first coating TiO 33 2,2 first coating SiO2 94 1,5 first coating TiO 98 2,2 filling TiO B 2,2 second coating TiO 68,6 2,2 second coating SiO2 65,8 1,5 second coating TiO 23,1 2,2 second coating SiO2 103,6 1,5 second coating TiO 23,8 2,2 semiconductor body 2,5

[0133] The Figures 12A and 12Bshow simulations of the reflectivity R as a function of the wavelength λ for the composition given in Table 6 with B = 2000 nm and B = 3000 nm. Figure 12A The reflectivity shown corresponds to that shown in Figure 10B shown.

[0134] The Figures 12C and 12D show simulations for the distance M of the maxima, i.e. the modulation distance, as well as for the displacement V of the maxima as a function of the recess width A, while in Figure 12Ean exemplary simulation of the gain G of a laser diode as a function of the wavelength λ for different operating currents is shown. With a fixed first and second coating, the aforementioned dependencies on the filling width B also apply accordingly with regard to the recess width A. In order to force the emitter units to different wavelengths, the distance M between the maxima should be greater than the (half-width) of the gain spectrum, which means that a smaller recess width is advantageous for this purpose. At the same time, the shift V of the maxima should be as small as possible so that the differences between the emitter units can be adjusted as well as possible and process variations have only a small impact, which means that large recess widths A are advantageous. In order to keep coupling losses low, the recess width A should in turn be as small as possible.From these boundary conditions, it follows for preferred embodiments that the recess width is greater than or equal to 0.1 nm and less than or equal to 20 µm, preferably greater than or equal to 0.3 nm and less than or equal to 10 µm and particularly preferably greater than or equal to 0.5 nm and less than or equal to 5 µm.

[0135] The features and embodiments described above for the recesses and the coating of the recesses are to be understood purely as examples. In particular, materials, layer thicknesses, layer combinations, fillings, recess widths, and recess positions can be specifically adapted depending on the wavelength spectrum and technical requirements of the light-emitting semiconductor chip.

[0136] In conjunction with the following figures, further embodiments for the construction of the light-emitting semiconductor chip and in particular of the emitter units are shown, which represent modifications of the previously described embodiments.

[0137] The Figures 13A and 13B show emitter units 101 for a light-emitting semiconductor chip, which have two recesses 4, one of which is formed in the region of the rear side 20 and the other in the region of the coupling-out side 22. As a result, the emitter units 101 shown each have a first segment 25, which forms the light-generating part, a second segment 26 in the region of the coupling-out side 22, which, for example, as in connection with the Figures 8A and 8B described, and a third segment 29 in the area of ​​the rear side 29. For the Figure 13A The rear third segment 29 of the emitter unit 101 shown can be arranged as in connection with the Figures 1A to 2Bdescribed as an uncontacted and thus passive segment, while the rear third segment 29 is for the Figure 13B shown emitter unit 101 as in connection with the Figures 6A and 6Bdescribed can be designed as an active segment which has a third electrical contact point 30, for example an electrode layer. In particular, for example, the recess 4 in the region of the rear side 20 can form a rear-side mirror coating and the recess 4 in the region of the output side 22 can form an output mirror coating for the resonator formed by the first segment 25. The first and second layers 21, 23 can be designed to be as low-reflective as possible. The recesses 4 in the region of the rear side 20 and the recesses 4 in the region of the output side 22 can be designed as in the previously described embodiments and, in particular, each have different recess widths, as can also be seen in the figures in conjunction with the following embodiments.The recesses 4, which are assigned to a same emitter unit 101, can be designed the same or different with regard to the dimensions and / or a coating.

[0138] By a combination of several recesses 4 per emitter unit 101 as in the Figures 13A and 13BAs shown, modulation effects can be enhanced and / or narrower reflection maxima can be achieved. For example, superposition effects can also be achieved by different designs of the recesses in relation to the recess width and the coating. Since the maxima of the respective reflection spectra have a certain spectral width, a significantly narrower wavelength window in which the emitter unit 101 must emit can be achieved by two spectra slightly shifted against each other in the region of the output side and in the region of the rear side. If the designs of the recesses in the region of the output side and in the region of the rear side are different, multiply corrugated spectra can be generated, for example. If the designs of the recesses in the region of the output side and in the region of the rear side are the same, an enhancement of the modulation can be achieved.As an alternative to the embodiments shown, other combinations with one, two or more active and / or passive segments may also be possible by a suitable number and arrangement of recesses.

[0139] The Figure 14 The exemplary embodiment shown for the light-emitting semiconductor chip 100 again has, purely by way of example, two recesses 4 per emitter unit 101 for subdividing into three segments 25, 26, 29, wherein the ridge waveguide structure 24 in the second region 26 is designed as a waveguide and combiner. The light-emitting semiconductor chip 100 can thus be designed as a photonically integrated laser component. As an alternative to the passively designed third segments 29, these can also be designed here and also in the following exemplary embodiments, for example, as an integrated photodiode and thus actively, as described above.

[0140] In the in the Figures 15A and 15BIn the embodiments shown for the light-emitting semiconductor chip 100, the ridge waveguide structures 24 of the emitter units 101 in the second segment 26 each have a slope ( Figure 15A ) or a curvature ( Figure 15B ), which can lead to superluminescent behavior. The light-emitting semiconductor chips 100 according to the Figures 15A and 15B can therefore be designed as superluminescent diodes.

[0141] In Figure 16A further embodiment of the light-emitting semiconductor chip 100 is shown, in which a wavelength-selective element 33, for example a type of grating such as a DFB structure (DFB: "distributed feedback laser"), is provided in the second segment 26 of the emitter units 101. The wavelength-selective element 33 can, for example, be formed laterally on the ridge waveguide structure 24 and / or on and / or above and / or in the ridge waveguide structure 24.

[0142] In the previously described embodiments, each emitter unit 101 of the light-emitting semiconductor chip 100 has at least one dedicated recess 4, which is separate from all other recesses 4 in the semiconductor body 1. Alternatively, at least one recess 4 may be present in the semiconductor body 1, which extends through the active regions of several and preferably all emitter units 101, as shown in the Figures 17A and 17Bis shown. The recess 4 can thus be designed as a continuous slot or gap with a changing recess width. In this case, at least one side surface of the recess can advantageously be aligned perpendicular to the emission direction of the generated light. In the exemplary embodiments shown, all active regions of the light-emitting semiconductor chip 100 are each penetrated by a single recess 4. In order for the recess widths for the emitter units 101 to differ, the recess 4 can have a base area with a double-sided or single-sided wedge shape, as in the Figures 17A and 17B is indicated. Accordingly, one or both side surfaces of the recess 4 can extend partially obliquely to the main extension direction of the recess 4. Alternatively or additionally, an at least partially curved and / or stepped course of one or both side surfaces is also possible.

[0143] The ridge waveguide structures 24 can, as shown in the previous embodiments, be designed, for example, as strips of constant width, which are interrupted by the at least one recess 4. In order to achieve a better facet quality, the ridge waveguide structures 24 can also have a thickening 24' in the region of the at least one recess 4 in the form of a widening along the main extension direction of the at least one recess 4, as shown in the Figures 18A to 18C is indicated. The at least one recess 4 can be located within the widening 24' ( Figure 18A ), it can be the same width as the widening 24' (not shown) or it can protrude beyond the widening 24' along the main extension direction of the recess 4 ( Figure 18B ). The thickening 24` can, as in the Figures 18A and 18BIt may also be advantageous if the ridge waveguide structure 24 gradually widens towards the recess 4 ( Figure 18C ), which can also be called a taper, to reduce coupling losses.

[0144] In order to reduce coupling losses, the at least one recess 4, as shown in the Figures 19A to 19C Instead of a rectangular basic shape, they can also have round or one-sided or two-sided convex or concave shapes. Purely as an example, the Figures 19A and 19B a one-sided convex and a two-sided convex shape are shown. The at least one recess 4 can also have more complex shapes, for example that of a retroreflector (cat's eye), as in Figure 19C is indicated.

[0145] 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.

[0146] The invention is not limited to the embodiments described in the accompanying drawings. The invention is defined in the appended claims. List of reference symbols

[0147] 1Semiconductor body 2Active region 3Substrate 4Recess 6First side surface 7Second side 10First coating 11Bottom surface 12Single layer 13Second coating 15Filling 16Preferred direction 17Main extension plane 20Rear side of the semiconductor body 21First layer 22Output side of the semiconductor body 23Second layer 24Ridge waveguide structure 24Thickening 25First segment 26Second segment 27First electrical contact point 28Second electrical contact point 29Third segment 30Third electrical contact point 33Wavelength-selective element 99Emission direction 100Light-emitting semiconductor chip 101Emitter unit ARecess width E1, E2, E3, E4Emission spectrum

Claims

1. A light-emitting semiconductor chip (100), comprising a semiconductor body (1) comprising a plurality of emitter units (101), wherein each emitter unit comprises an active region (2) which is arranged in a resonator having an outcoupling side (22) and a rear side (20) and which is intended and configured to emit light during operation at the outcoupling side along a radiation emission direction (99), in each emitter unit the active region is completely penetrated by at least one recess (4) in the semiconductor body, in each emitter unit, in the region of the active region the recess has a recess width (A) measured along the radiation emission direction, characterized in that the recess widths of the emitter units are at least partially different.

2. The light-emitting semiconductor chip of claim 1, wherein the recess widths of the emitter units differ by an amount that is greater than or equal to 1 nm and less than or equal to 2 µm.

3. The light-emitting semiconductor chip according to any one of the preceding claims, wherein at least three emitter units are present and the recess widths of the emitter units differ equidistantly from each other.

4. The light-emitting semiconductor chip according to any one of the preceding claims, wherein each of the emitter units has at least one recess that is separate from the recesses of the other emitter units.

5. The light-emitting semiconductor chip according to any one of the preceding claims, wherein the at least one recess extends through the active regions of two or more emitter units.

6. The light-emitting semiconductor chip according to the preceding claim, wherein the recess width of the at least one recess increases continuously or stepwise from emitter unit to emitter unit.

7. The light-emitting semiconductor chip according to any one of the preceding claims, wherein the at least one recess has a rectangular base surface or an at least partially wedge-shaped and / or at least partially rounded base.

8. The light-emitting semiconductor chip according to any one of the preceding claims, wherein for each emitter unit the semiconductor body comprises a ridge waveguide structure (24) and the ridge waveguide structure comprises, in the region of the at least one recess, a thickening (24') along a main extension direction of the at least one recess.

9. The light-emitting semiconductor chip according to any one of the preceding claims, wherein, for each emitter unit, at least one recess is arranged in the region of the rear side.

10. The light-emitting semiconductor chip according to any one of the preceding claims, wherein, for each emitter unit, at least one recess is arranged in the region of the outcoupling side.

11. The light-emitting semiconductor chip according to any one of the preceding claims, wherein, for each emitter unit, the active region is completely penetrated by at least two recesses and wherein one of the recesses is arranged in the region of the rear side and the other of the recesses is arranged in the region of the outcoupling side.

12. The light-emitting semiconductor chip according to any one of the preceding claims, wherein, for each emitter unit, the at least one recess has at least one coating (10, 13, 15) that specifies a reflectivity of the recess for the light generated in the active region, the reflectivity being less than or equal to 99.9% and greater than or equal to 80%.

13. The light-emitting semiconductor chip according to any one of the preceding claims, wherein, for each emitter unit, - the at least one recess has, in the radiation emission direction, a first side surface (6) and a second side surface (7) opposite the first side surface, and - the first side surface has a first coating (10) which provides a reflectivity for the light generated in the active region and which is formed as a first layer sequence with a plurality of individual layers (12), and / or - the second side surface has a second coating (13) which provides a reflectivity for the light generated in the active region and which is formed as a second layer sequence with a plurality of individual layers (12).

14. The light-emitting semiconductor chip according to the preceding claim, wherein the first coating and the second coating are embodied differently from each other.

15. The light-emitting semiconductor chip according to the preceding claim, wherein a thickness of the first coating in the region of the first side surface to a thickness of the second coating in the region of the second side surface has a ratio between 1:1 and 1:20, inclusive.

16. The light-emitting semiconductor chip according to any one of claims 12 to 15, wherein a filling (15) is provided in the recess.

17. The light-emitting semiconductor chip according to any one of the preceding claims, wherein each of said emitter units comprises a first segment (25) and a second segment (26), said first segment being electrically and / or optically isolated from said second segment by said at least one recess (4).

18. The light-emitting semiconductor chip according to the preceding claim, wherein, for each emitter unit, the first segment comprises a light generating part and the second segment is a modulating element adapted to modulate an intensity of the electromagnetic radiation of the active region.

19. The light-emitting semiconductor chip according to any one of the preceding claims, wherein at least one of the emitter units comprises a segment comprising one or more of the following: photodiode, passive waveguide, active waveguide, beam splitter, beam combiner, lens, wavelength selective element, phase shift elements, frequency doubler, taper, amplifier, converter, transistor.

20. A method for manufacturing a light-emitting semiconductor chip (100) according to any one of the preceding claims, comprising the steps of: - producing a semiconductor body (1) comprising a plurality of emitter units (101), each emitter unit having an active region (2) which is arranged in a resonator having an outcoupling side (22) and a rear side (20) and which is intended and configured to emit light during operation at the outcoupling side along a radiation emission direction (99), - producing at least one recess (4) in the semiconductor body, by means of which, for each emitter unit, the active region is completely penetrated, the at least one recess in the region of the active region having a recess width (A), which is measured along the radiation emission direction, for each emitter unit, and the recess widths of the emitter units being different.