Semiconductor laser diode and method for manufacturing the same

Abstract

To provide a ridge-type semiconductor laser diode realizing favorable current injection.SOLUTION: A semiconductor laser diode 100 comprises a semiconductor layer sequence 2 grown in a vertical direction, and a transparent electrically conductive cover layer 4 disposed on the semiconductor layer sequence. The semiconductor layer sequence 2 has an active layer 3. The semiconductor layer sequence terminates in a vertical direction 92 with a top side 20. The top side comprises a contact region 21 arranged in the vertical direction above the active region, and at least one cover region 22 directly adjoining the contact region in a lateral direction 91 perpendicular to the vertical and longitudinal directions. The cover layer is disposed contiguously on the top side on the contact region and the at least one cover region. The cover layer is disposed directly on the top side of the semiconductor layer sequence at least in the at least one cover region. At least one element 10 defining the at least one active region is disposed, the element covered by the cover layer.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] This application claims the priority of German patent application no. 102019106536.4, the disclosure content of which is hereby incorporated by reference.

[0002] SUMMARY OF THE DISCLOSURE Semiconductor laser diodes and methods for manufacturing semiconductor laser diodes are described herein.

[0003] A typical laser diode has a dielectric passivation on the side opposite the substrate, which may also cover the side of the ridge waveguide structure depending on the laser diode's configuration. After the ridge waveguide structure is produced and coated with a passivation material, the passivation material must then be removed again in the areas where electrical contacting is to be made. The steps required in this regard can be very complicated, especially when the structure dimensions of the ridge waveguide structure are in the range of several μm. Moreover, typical dielectric passivation materials, such as SiO2 or Si3N4, have only a very low thermal conductivity, which can be a disadvantage, especially when such laser diodes are mounted on a support with the passivated side.

[0004] At least one objective of certain embodiments is to provide a semiconductor laser diode. At least one further objective of certain embodiments is to provide a method for manufacturing a semiconductor laser diode.

[0005] These problems are solved by the subject matter and the methods according to the independent claims. The dependent claims describe advantageous embodiments and developments of the subject matter and the methods, which are further evident from the following description and the drawings.

[0006] According to at least one embodiment, the semiconductor laser diode has at least one active layer, which is adapted to generate light in an active region during operation. The active layer can in particular be part of a semiconductor layer sequence having a plurality of semiconductor layers and can have a main extension plane perpendicular to the direction in which the layers of the semiconductor layer sequence are arranged. For example, the active layer can have exactly one active region. Furthermore, the active layer can have several active regions. The active region can be influenced by one or more elements that define the active region, which are described further below. The term "at least one active region" used below can relate to an embodiment having exactly one active region and also to an embodiment having several active regions.

[0007] According to a further embodiment, in a method for manufacturing a semiconductor laser diode, a semiconductor layer sequence is provided with an active layer, which is adapted to generate light during operation of the semiconductor laser diode. In particular, the semiconductor layer sequence with the active layer can be manufactured by means of an epitaxial method. The embodiments and features described above and below apply equally to the semiconductor laser diode and to the method for manufacturing the semiconductor laser diode.

[0008] According to a further embodiment, the semiconductor laser diode has a light output surface and a back surface opposite to the light output surface. The light output surface and the back surface can in particular be side surfaces of the semiconductor laser diode, particularly preferably side surfaces of the semiconductor layer sequence, which may also be referred to as so-called facet surfaces. During operation, the semiconductor laser diode can emit light generated in at least one active region via the light output surface. On the light output surface and on the back surface, suitable optical coatings, in particular reflective or partially reflective layers or layer sequences, can be provided, which can form an optical cavity for the light generated in the active layer. The at least one active region can extend between the back surface and the light output surface along a direction, which is referred to here and below as the longitudinal direction. The longitudinal direction can in particular be parallel to the main extension plane of the active layer. The direction in which the layers are arranged one above the other, i.e. perpendicular to the main extension plane of the active layer, is referred to here and below as the vertical direction. The direction perpendicular to the longitudinal direction and perpendicular to the vertical direction is referred to here and below as the transverse direction. The longitudinal and lateral directions may thus define planes extending parallel to the main plane of extension of the active layer.

[0009] The semiconductor layer sequence can in particular be configured as an epitaxial layer sequence, i.e. as an epitaxially grown semiconductor layer sequence. The semiconductor layer sequence can then be based on InAlGaN, for example. InAlGaN-based semiconductor layer sequences include, in particular: epitaxially produced semiconductor layer sequences usually have a layer sequence consisting of a number of different individual layers, which are in turn layered on layers of the III-V compound semiconductor material system InAlGaN. x Al y Ga 1-x-y N, with 0≦x≦1, 0≦y≦1 and x+y≦1. In particular the active layer can be based on such a material. A semiconductor layer sequence having at least one active layer based on InAlGaN can emit electromagnetic radiation, for example, preferably in the ultraviolet to green wavelength range.

[0010] Alternatively or additionally, the semiconductor layer sequence can also be based on InAlGaP, i.e. the semiconductor layer sequence can have several different individual layers, at least one of which, for example the active layer, is based on InAlGaP from the III-V compound semiconductor material system. x Al y Ga 1-x-y P, with 0≦x≦1, 0≦y≦1 and x+y≦1. A semiconductor layer sequence having at least one active layer based on InAlGaP can, for example, preferably emit electromagnetic radiation having one or more spectral components in the green to red wavelength range.

[0011] Alternatively or additionally, the semiconductor layer sequence may comprise other III-V compound semiconductor material systems, for example InAlGaAs-based materials or II-VI compound semiconductor material systems. In particular, an active layer comprising an InAlGaAs-based material may be suitable for emitting electromagnetic radiation having one or more spectral components in the red to infrared wavelength range. II-VI compound semiconductor materials may comprise at least elements from the second main group, for example Be, Mg, Ca, Sr, and elements from the sixth main group, for example O, S, Se. For example, II-VI compound semiconductor materials include ZnSe, ZnTe, ZnO, ZnMgO, CdS, ZnCdS, and MgBeO.

[0012] The active layer, in particular the semiconductor layer sequence including the active layer, can be provided on a substrate. For example, the substrate can be formed as a growth substrate, on which the semiconductor layer sequence is grown. The active layer, in particular the semiconductor layer sequence including the active layer, can be produced by epitaxial methods, for example by metalorganic vapor phase epitaxy (MOVPE) or molecular beam epitaxy (MBE). This can in particular mean that the semiconductor layer sequence is grown on the growth substrate. Furthermore, the semiconductor layer sequence can be provided with electrical contacts in the form of one or more contact elements. In addition, it can also be possible that the growth substrate is removed after the growth process. In this case, the semiconductor layer sequence can also be transferred, for example, after growth, to a substrate formed as a carrier substrate. The substrate can comprise semiconductor materials, for example the compound semiconductor material systems mentioned above, or other materials. In particular, the substrate can comprise sapphire, GaAs, GaP, GaN, InP, SiC, Si, Ge and / or ceramic materials, such as SiN or AlN, or can consist of such materials.

[0013] For light generation, the active layer 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). In addition to the active layer, the semiconductor layer sequence can comprise further functional layers and regions, for example p- or n-doped charge carrier transport layers, i.e. electron transport layers or hole transport layers, undoped or p- or n-doped confinement layers, cladding layers or waveguide layers, barrier layers, planarization layers, buffer layers, protective layers and / or electrode layers, and combinations thereof. Furthermore, additional layers, for example buffer layers, barrier layers and / or protective layers, can also be arranged perpendicular to the growth direction of the semiconductor layer sequence, for example around the semiconductor layer sequence, i.e. for example on the side surfaces of the semiconductor layer sequence.

[0014] According to a further embodiment, the semiconductor laser diode has a transparent conductive cover layer on the semiconductor layer sequence. In particular, the semiconductor layer sequence can be terminated at the top surface along the vertical direction. The cover layer can be provided in particular on the top surface. Particularly preferably, the top surface can be formed on the semiconductor layer sequence on the side opposite the substrate. In this case, the substrate can be a growth substrate or a carrier substrate. If the semiconductor laser diode does not have a substrate after the growth substrate is released, the top surface can be particularly preferably formed by the side opposite the released growth substrate. The cover layer can preferably at least partially adjoin the semiconductor material of the top surface of the semiconductor layer sequence directly and thus be in direct contact with the semiconductor material of the top surface of the semiconductor layer sequence. For example, the cover layer can be in direct contact with this top surface in the entire region of the top surface covered by the cover layer. It can also be possible that above at least one active region in the vertical direction, the cover layer is not in direct contact with the top surface of the semiconductor layer sequence, whereas in at least one region laterally offset relative to the active region, the cover layer is provided in direct contact with the top surface of the semiconductor layer sequence.

[0015] According to a further embodiment, the cover layer comprises at least one transparent conductive oxide (TCO). A transparent conductive oxide is a transparent conductive material, which is usually a metal oxide, for example zinc oxide, tin oxide, cadmium oxide, titanium oxide, indium oxide or indium tin oxide (ITO). The group of TCOs includes binary metal oxygen compounds, for example ZnO, SnO2 or In2O3, as well as compounds such as Zn2SnO4, CdSnO3, ZnSnO3, MgIn2O4, GaInO3, Zn2In2O5 or In4Sn3O4. 12Also included are ternary metal oxygen compounds such as, for example, ternary metal oxygen compounds, or mixtures of various transparent conductive oxides. Particularly preferably, the cover layer can comprise one or more of the following materials: ITO, which can also be called In2O3:Sn, with a particularly preferred proportion of 90% to 95% In2O3 and 5% to 10% SnO2, and also In2O3, SnO2, Sn2O3, ZnO, IZO (indium zinc oxide), GZO (zinc oxide doped with gallium). It can also be said that the TCO or TCOs of the cover layer do not necessarily have to correspond to a stoichiometric composition and can also be doped p-type or n-type.

[0016] A current injection can be particularly preferably carried out from the side of the top side into the semiconductor layer sequence via the cover layer. The cover layer can thus form a transparent, electrically conductive cover layer. On the bottom side of the semiconductor layer sequence facing away from the cover layer, a contact element can be provided in the form of an electrode layer. For electrically connecting the cover layer from the outside, for example by soldering or wire bonding, a metallic contact element can be arranged on the cover layer facing away from the semiconductor layer sequence. The contact element can be a bonding layer for wire bonding or soldering of the semiconductor laser diode, which can be formed, for example, in a single or multiple layers, and furthermore the contact element can comprise or consist of aluminum and / or silver and / or gold. In particular, the contact element can be arranged only in the area or areas on the cover layer that are required for the electrical connection by soldering or wire bonding, or a plurality of contact elements can also be arranged. In particular, the contact element or elements can be arranged independently of the requirements for current injection into the semiconductor layer sequence. The contact element or elements can preferably be arranged directly on the cover layer.

[0017] According to a further embodiment, the top face has a contact region arranged above the at least one active region in the vertical direction. At a position laterally offset relative to the contact region, the top face has a cover region directly adjacent to the contact region. This can also mean that the contact region is arranged laterally between two cover regions, which are laterally directly adjacent to the contact region in each case. The contact region can in particular have a main extension direction along the longitudinal direction and can therefore preferably be formed in the form of a stripe, which preferably extends from the radiation exit surface to the rear surface and is arranged along the transverse direction between the two cover regions. The features and embodiments described below mainly in the context of "at least one cover region" relate to embodiments with exactly one cover region as well as to embodiments with two or more cover regions directly adjacent to the contact region.

[0018] Via the contact layers, a current can be injected into the semiconductor layer sequence from the side of the top surface of the semiconductor layer sequence during operation of the semiconductor laser diode. During operation via the contact regions, in particular, a larger current is injected into the top surface of the semiconductor layer sequence than via the at least one cover region. This can mean, in particular, that a current is injected at least preferably or at least substantially or even exclusively via the contact regions, whereas during operation of the semiconductor laser diode, a current is injected less via the cover regions than via the contact regions, or substantially no current is injected, or even no current is injected at all.

[0019] According to a further embodiment, the cover layer is provided on the upper side continuously over the contact area and over the at least one cover area, particularly preferably covering the entire contact area and at least a part of the at least one cover area or also covering the at least one cover area entirely.

[0020] According to a further embodiment, the cover layer covers the entire top surface of the semiconductor layer sequence. As an alternative to this, the cover layer can cover only a portion of the top surface of the semiconductor layer sequence. The portion of the top surface that is not covered by the cover layer in this case can be selected in such a way that it has no effect on the formation of the active region and thus on the optical properties of the semiconductor laser diode, regardless of whether a cover layer is provided thereon. In particular, the cover layer can extend laterally over the top surface of the semiconductor layer sequence, as long as the region that is not covered by the cover layer also has no effect on the mode structure and thus on the active region.

[0021] According to a further embodiment, the semiconductor laser diode has at least one element defining at least one active region, which is covered by a cover layer. The at least one element defining at least one active region may also be referred to below for short as a defining element. Particularly preferably, the at least one defining element can be arranged on the top surface of the semiconductor layer sequence, for example in the form of a topographical structure and / or in the form of a semiconductor structure on the top surface and / or in the form of a layer provided on the top surface of the semiconductor layer sequence. That the defining element defines at least one active region can mean that the formation of optical modes in the active layer during laser operation, i.e. the formation of the active region, depends on the specific form of the defining element. In other words, the active region that is formed can be changed by changing the defining element. The defining element is thus used to adjust a specifically targeted mode distribution and thus a specifically targeted active region. In particular, the at least one defining element can influence at least one optical property and / or at least one property with regard to current injection of at least a portion of the semiconductor layer sequence. To define an active area, one or more defining elements may be provided, in particular the cooperation of multiple defining elements may result in the desired formation of the active area.

[0022] According to a further embodiment, in a method for manufacturing a semiconductor laser diode, a semiconductor layer sequence is provided which comprises an active layer and a top surface with a contact region and at least one cover region, during and / or subsequently at least one element defining the active region can be formed and a cover layer can be provided seamlessly on the contact region and on the at least one cover region.

[0023] According to a further embodiment, the at least one defining element has or is formed by a ridge formed in the contact region of the top surface. For example, the ridge can be formed by a portion of the semiconductor layer sequence. The ridge can in particular be formed by a ridge-like raised region extending in the longitudinal direction at the top surface of the semiconductor layer sequence. In other words, the ridge extends in the longitudinal direction, protruding perpendicularly from the laterally adjacent surface regions. The side surfaces laterally adjacent to the ridge can have a stepped cross section, in particular together with the adjacent surface regions of the top surface of the semiconductor layer sequence. The terms "ridge-like region" and "ridge" may be used synonymously below. Furthermore, the semiconductor layer sequence can also have several ridge-like regions, which are arranged laterally juxtaposed and spaced apart from one another and each extend in the longitudinal direction. In order to produce the ridge, after the growth of the semiconductor layer sequence, a portion of the semiconductor layer sequence can be removed from the top surface. In particular, this removal can be carried out by an etching process. The cover layer can particularly preferably cover the entire ridge, in particular it can extend laterally away from the ridge over the top surface of the semiconductor layer sequence.

[0024] Particularly preferably, the contact region can be formed by a ridge top surface. In other words, the contact region has the same shape as the ridge when viewed vertically from above on the top surface of the semiconductor layer sequence. The shape of the ridge, in particular the shape of the ridge top surface, can therefore determine the shape of the contact region and thus the region for current injection. Furthermore, the contact region can additionally have ridge side surfaces or parts thereof that laterally adjoin the ridge.

[0025] Furthermore, the ridge can form a ridge waveguide structure for index guiding of light generated in the active region. In this case, the ridge has a sufficient height and is sufficiently close to the active layer so that the ridge has an effect on the guiding and thus the mode shaping in the active layer. As an alternative to this, the ridge can have a small height and a large spacing to the active layer so that the ridge also provides only little or no index guiding of the light generated in the active region. In other words, in this case, the ridge can be formed such that the mode shaping in the active layer is provided mainly or only by gain guiding.

[0026] Furthermore, due to the formation of the ridge, the semiconductor layer sequence can have a first semiconductor material in the contact region and a second semiconductor material in the cover region, where the first semiconductor material can have a higher electrical conductivity and / or a lower electrical contact resistance to the cover layer than the second semiconductor material. For example, the semiconductor layer sequence can be terminated vertically towards the top side by a cladding layer and further a semiconductor contact layer thereon, where the semiconductor contact layer can have a higher doping than the cladding layer, i.e. a higher electrical conductivity and / or a lower electrical contact resistance to the cover layer. In order to form the ridge, at least the semiconductor contact layer or the semiconductor contact layer and at least a part of the cladding layer can be removed in the cover region. The ridge can thus be formed by the parts of the semiconductor layer or of the semiconductor layer and part of the cladding layer that remain after the formation of the ridge, so that the top surface in the contact region is formed by the material of the semiconductor contact layer, while the top surface in the cover region is formed by the semiconductor material of the cladding layer. The different electrical properties of the semiconductor contact and cladding layers can result in the above-mentioned different current injection in the contact and cover regions, thereby acting to define the active region.

[0027] According to a further embodiment, the ridge comprises a transparent conductive contact layer. The transparent conductive contact layer can be provided directly on the top side of the semiconductor layer sequence, i.e. in direct contact with the semiconductor material of the semiconductor layer sequence. In particular in this case, the ridge can be formed by a contact layer. For this purpose, after the growth of the semiconductor layer sequence, a contact layer can be provided in the contact region. The contact layer can in particular comprise a TCO, as explained above in connection with the cover layer. Furthermore, the ridge can be formed by a transparent conductive contact layer and a part of the semiconductor layer sequence.

[0028] Furthermore, the transparent conductive contact layer can have a first TCO, whereas the cover layer can have a different second TCO. The first TCO can have a higher electrical conductivity and / or a lower electrical contact resistance to the semiconductor layer sequence than the second TCO. The different electrical properties of the materials of the cover layer and the contact layer can result in the above-mentioned different current injections in the contact region and in the cover region, which can serve to define the active region. Alternatively or additionally, the second TCO can have a lower refractive index than the first TCO. The TCO of the contact layer is overlaid by the TCO of the cover layer, which can affect the waveguiding properties in the semiconductor laser diode and thus serve to define the active region.

[0029] According to a further embodiment, the cover layer comprises two or more TCOs. In particular, the cover layer comprises a first TCO in the contact region and a second TCO in at least one of the cover regions. The second TCO can be at least partially covered by the first TCO. The second TCO can, for example, have a lower optical absorption than the first TCO. Furthermore, the first TCO can have a higher electrical conductivity and / or a higher electrical contact resistance to the semiconductor layer sequence than the second TCO.

[0030] According to a further embodiment, at least one element defining the active region has or is formed by a damage-treated semiconductor structure in at least one cover region. In particular, the damage-treated semiconductor structure can be formed on the top surface of the semiconductor layer sequence. The damage-treated structure can be produced, for example, by an etching process. Particularly preferably, the etching process can be a dry etching process. The parameters of the etching process can be adjusted in this case in such a way that the semiconductor material exposed to the etching medium is damaged by plasma and / or ion bombardment. In this case, no or only very little electrical contact is formed on the damage-treated top surface to the cover layer, so that no or practically no current can be injected in this region, which can thus serve to define the active region. Particularly preferably, the damage-treated semiconductor structure can be combined with the above-mentioned ridge. In particular, the damage-treated semiconductor structure can be produced within the framework of a ridge production.

[0031] According to a further embodiment, a metallic contact layer is arranged on the top surface of the semiconductor layer sequence in the contact region, directly adjacent to said top surface. The metallic contact layer is in particular covered by a cover layer. Suitable materials for the metallic contact layer include, for example, one or more metals selected from among Pt, Pd, Rh and Ni. The metallic contact layer can increase the electrical connection of the contact region to the cover layer, and in this way the metallic contact layer can also form a defining element.

[0032] Furthermore, the semiconductor laser diode can be free of dielectric material on the top side, which acts on the active region. In other words, the semiconductor laser diode has no dielectric material on the top side, in particular no dielectric passivation, as is common in the prior art, in areas where such dielectric material would act on at least one active region. Particularly preferably, the semiconductor laser diode can be free of dielectric material on the top side. In other words, in this case, no dielectric material is provided on the top side at all, in particular no dielectric material in the form of passivation.

[0033] According to a further embodiment, a plurality of contact regions are provided on the top surface. Furthermore, a plurality of elements for defining the active regions can be provided. In particular, a plurality of defining elements can provide that a plurality of active regions are present during operation in the active layer, with a contact region being arranged vertically above each active region. The defining elements are covered by a cover layer. The contact regions and / or the defining elements can each be configured identically or differently and can have one or more of the above-mentioned features. The semiconductor laser diode can in particular be configured as a so-called laser bar. Particularly preferably in this case, the semiconductor layer sequence and in particular the active layer can be configured to generate visible light, so that the semiconductor laser diode can be a multiple radiation source in the visible wavelength range.

[0034] Furthermore, several cover regions can be provided, with the contact regions being separated from one another by the cover regions. The cover layer can be arranged seamlessly above the contact regions and the cover regions. As an alternative to this, the cover layer can also be divided into mutually separated sections, with each section being assigned to an active region and arranged, as described above, on the respectively assigned contact region and on the respectively assigned cover region.

[0035] According to a further embodiment, the method for manufacturing a semiconductor laser diode may preferably comprise the following steps: providing a substrate; Providing a semiconductor layer sequence by epitaxial growth, covering with a mask what will become the contact areas; Etching a ridge in the contact region and / or damaging one or more cover regions located laterally to the sides of the contact region; removing the mask; providing, in particular over the entire surface, a transparent conductive cover layer which can particularly preferably form a p-type contact for the semiconductor layer sequence; Providing one or more metallic contact elements on and / or at the cover layer.

[0036] The step of providing a further electrical contact, which in this case may in particular be an n-type contact, as well as further necessary steps, can be placed anywhere in the process flow. As an alternative to or in addition to the steps of producing a ridge and / or producing a damaged semiconductor structure, a step of providing a metallic or transparent conductive contact layer in the contact area can be carried out.

[0037] Thus, according to the semiconductor laser diode described herein, after the production of the semiconductor layer sequence with the semiconductor structure, which may be treated as described above with the ridge and / or damage formation, a transparent conductive cover layer is provided, which is in direct contact with the semiconductor material of the semiconductor layer sequence at least in at least one cover region and preferably comprises or consists of a TCO. In contrast, the dielectric passivation layer as is typical in the prior art can be omitted, particularly in the region of the top surface of the semiconductor layer sequence, where the layers and elements provided thereon affect the properties of the active region. Since the TCO usually has a higher thermal conductivity than the dielectrics typically used for passivation, according to the semiconductor laser diode described herein, the thermal resistance at the top surface can be reduced, which leads to improved power performance, improved high-temperature properties and reduced aging. The cover layer thus simultaneously forms a thermally conductive passivation and an electrical connection layer for contacting the semiconductor layer sequence. Moreover, this manufacturing method can have a significantly simplified self-adjusting process management. This allows the production to be carried out at lower cost, faster and with improved process stability than in the prior art.

[0038] Further advantages, advantageous embodiments and developments emerge from the exemplary embodiments described below with reference to the drawings. [Brief description of the drawings]

[0039] [Figure 1A] 1A-1D show schematic diagrams of semiconductor layer sequences for a semiconductor laser diode and for process steps of a method for manufacturing a semiconductor laser diode according to several embodiments; [Figure 1B] 1A-1D show schematic diagrams of semiconductor layer sequences for a semiconductor laser diode and for process steps of a method for manufacturing a semiconductor laser diode according to several embodiments; [Figure 1C] 1A-1D show schematic diagrams of semiconductor layer sequences for a semiconductor laser diode and for process steps of a method for manufacturing a semiconductor laser diode according to several embodiments; [Figure 1D] 1A-1D show schematic diagrams of semiconductor layer sequences for a semiconductor laser diode and for process steps of a method for manufacturing a semiconductor laser diode according to several embodiments; [Figure 1E] 1A-1D show schematic diagrams of semiconductor layer sequences for a semiconductor laser diode and for process steps of a method for manufacturing a semiconductor laser diode according to several embodiments; [Figure 2A] 3 shows a schematic representation of a semiconductor laser diode according to a further embodiment, in particular also within the framework of a semiconductor laser diode manufacturing method. [Figure 2B] 3 shows a schematic representation of a semiconductor laser diode according to a further embodiment, in particular also within the framework of a semiconductor laser diode manufacturing method. [Figure 2C] 3 shows a schematic representation of a semiconductor laser diode according to a further embodiment, in particular also within the framework of a semiconductor laser diode manufacturing method. [Diagram 3] 3A and 3B are schematic diagrams illustrating semiconductor laser diodes according to further embodiments; [Figure 4] 3A and 3B are schematic diagrams illustrating semiconductor laser diodes according to further embodiments; [Diagram 5] 3A and 3B are schematic diagrams illustrating semiconductor laser diodes according to further embodiments; [Figure 6] 3A and 3B are schematic diagrams illustrating semiconductor laser diodes according to further embodiments; [Figure 7] 3A and 3B are schematic diagrams illustrating semiconductor laser diodes according to further embodiments; [Figure 8] 3A and 3B are schematic diagrams illustrating semiconductor laser diodes according to further embodiments; [Figure 9] 3A and 3B are schematic diagrams illustrating semiconductor laser diodes according to further embodiments; [Figure 10] 3A and 3B are schematic diagrams illustrating semiconductor laser diodes according to further embodiments;

[0040] In the examples and figures, identical, similar or similarly acting elements may be respectively provided with the same reference numerals. The illustrated elements and their mutual size ratios should not be considered to be to scale, rather individual elements, such as layers, components, elements and regions, may be drawn with exaggerated sizes for ease of depiction and / or understanding.

[0041] Figures 1A to 1E show exemplary embodiments of a semiconductor layer sequence 2 on a substrate 1, which is provided and used to produce a semiconductor laser diode as described below. Figure 1A shows a top view of the light output surface 6 of what will later become the laser diode, and Figure 1B shows a cross section of the semiconductor layer sequence 2 and the substrate 1 in a plane cut perpendicular to the light output surface 6. Figure 1C shows one exemplary embodiment of the structure of the semiconductor layer sequence 2. Figures 1D and 1E show variants of the semiconductor layer sequence 2.

[0042] As shown in FIGS. 1A to 1C, a substrate 1 is provided, which is for example a growth substrate for a semiconductor layer sequence 2 to be produced thereon by epitaxial growth. As an alternative to this, the substrate 1 can also be a carrier substrate onto which the semiconductor layer sequence 2 grown on the growth substrate is subsequently transferred. For example, the substrate 1 can consist of GaN, onto which the semiconductor layer sequence 2 based on InAlGaN compound semiconductor material is grown. Furthermore, other materials are also possible for the substrate 1 and for the semiconductor layer sequence 2, as mentioned in particular in the overview part. As an alternative to this, it is also possible for the finished semiconductor laser diode not to be provided with a substrate. In this case, the semiconductor layer sequence 2 can be grown on a growth substrate, which is then removed. The semiconductor layer sequence 2 has an active layer 3 which is suitable for generating light 8 during operation of the finished semiconductor laser diode, in particular for generating laser light when a laser threshold is exceeded, and emitting it via the light exit surface 6.

[0043] 1A and 1B, the direction extending parallel to the main extension direction of the layers of the semiconductor layer sequence 2 when viewed from above on the light output surface 6 is referred to here and below as lateral direction 91. The direction of the arrangement of the layers above and below the semiconductor layer sequence 2 as well as the semiconductor layer sequence 2 on the substrate 1 is referred to here and below as vertical direction. The direction perpendicular to the lateral direction 91 and the vertical direction 92, which corresponds to the direction in which light 8 is emitted during operation of the completed semiconductor laser diode, is referred to here and below as longitudinal direction 93.

[0044] According to one embodiment, the ridge 9 is formed at the top side 20 of the semiconductor layer sequence 2 facing away from the substrate 1 by removing parts of the semiconductor material of the semiconductor layer sequence 2 facing away from the substrate 1. For this purpose, a suitable mask can be applied to the grown semiconductor layer sequence 2 in the region in which the ridge is to be formed. The semiconductor material can be removed by an etching process. The mask can then be removed again. The ridge 9 is formed by such a process in such a way that it extends in the longitudinal direction 93 and is bounded on both sides in the lateral direction 91 by side surfaces, which may also be referred to as ridge flanks or ridge faces.

[0045] In addition to the active layer 3, the semiconductor layer sequence 2 can comprise further semiconductor layers, for example buffer layers, cladding layers, waveguide layers, barrier layers, current spreading layers and / or current limiting layers. As shown in FIG. 1C, the semiconductor layer sequence 2 on the substrate 1 can for example comprise a buffer layer 31, on which a first cladding layer 32 and on which a first waveguide layer 33 are provided, on which the active layer 3 is provided. On top of the active layer 3, a second waveguide layer 34, a second cladding layer 35 and a semiconductor contact layer 36 can be provided. In the illustrated embodiment, the ridge 9 is formed by the semiconductor contact layer 36 and a part of the second cladding layer 35, whereby after growth of the semiconductor layer sequence 2, a part of the semiconductor layer sequence 2 is removed from the side of the top side 20 in order to produce the ridge 9. In particular, the removal can be performed by an etching process. The abrupt change in the refractive index at the side of the ridge 9 into the adjacent material, and if it is sufficiently close to the active layer 3, can result in so-called index guiding of the light generated in the active layer 3, which can decisively result in the formation of an active region 5 in the semiconductor layer sequence 2, which defines a region in which the generated light is guided and amplified in one or more laser modes during laser operation. The ridge 9 thus forms in this embodiment a so-called ridge waveguide structure and is an element that defines an active region, which will be explained in more detail below. It is also possible for the ridge 9 to have a lower or higher height than shown, so that less or more semiconductor material is removed to form the ridge 9. For example, the ridge 9 can be formed only by the semiconductor contact layer 36 or only by a part of it, or by the semiconductor contact layer 36 and the second cladding layer 35. By matching the height of the ridge 9, matching of the index guiding can be achieved. The lower the height and / or the greater the distance between the ridge 9 and the active layer 3, the less noticeable the index guiding can be. In this case, the mode guiding in the active region is at least partly effected by so-called gain guiding.

[0046] If the semiconductor layer sequence 2 is based on InAlGaN compound semiconductor material as described above, the buffer layer 31 can comprise or consist of undoped or n-type doped GaN, the first cladding layer 32 can comprise n-type doped AlGaN, the first waveguide layer 33 can comprise n-type doped GaN, the second waveguide layer 34 can comprise p-type doped GaN, the second cladding layer can comprise p-type doped AlGaN, and the semiconductor contact layer 36 can comprise or consist of p-type doped GaN. As n-type dopant, for example, Si can be used, and as p-type dopant, for example, Mg can be used. The active layer 3 can be formed by a pn junction or by a quantum well structure with multiple layers, as shown in FIG. 1C, which can be formed by alternating layers with or consisting of InGaN and GaN, for example. The substrate can comprise or consist of n-type doped GaN, for example. Alternatively, other layer and material combinations are possible, as discussed in the general description section.

[0047] Furthermore, on the lateral light output face 6 and the opposing rear face 7 of the semiconductor layer sequence 2 and of the substrate 1, reflective or partially reflective layers or layer sequences, which are not shown in the drawing for the sake of clarity, are provided and arranged in such a way that an optical cavity is formed in the semiconductor layer sequence 2.

[0048] For example, as can be seen from FIG. 1A, the ridge 9 can be formed by completely removing the semiconductor material laterally on both sides of the ridge 9. As an alternative to this, as shown in FIG. 1D, a so-called "tripod" can also be formed, whereby the semiconductor material is removed laterally only along two grooves on the sides of the ridge 9 to form the ridge 9. As an alternative to this, the finished semiconductor laser diode can also be formed as a so-called broad-area laser diode, whereby a semiconductor layer sequence 2 without a ridge or with a low ridge is produced and prepared for further process steps. FIG. 1E shows a semiconductor layer sequence 2 of this kind, whereby the mode guiding can be based exclusively or at least substantially on the gain guiding method.

[0049] Further process steps for producing a semiconductor laser diode as well as examples relating to a semiconductor laser diode are now described with reference to the further figures. These examples are described primarily on the basis of a semiconductor layer sequence 2 with a ridge 9 as shown in Figures 1A-1C, purely by way of example. Alternatively thereto, however, the following process steps and examples are also possible for variant embodiments of the semiconductor layer sequence 2 with a tripod structure as shown in Figures 1D and 1E or without a ridge. The detailed structure of the semiconductor layer sequence 2 shown in Figure 1C should not be taken as limiting thereto and is not shown in the following figures for clarity.

[0050] FIG. 2A partially shows a semiconductor laser diode 100 with a semiconductor layer sequence 2, which is produced in a first process step as described above within the framework of the production of the semiconductor laser diode 100 and is prepared for further process steps. In a further process step, a transparent conductive cover layer 4 is applied to the top side 20. In particular, the top side 20 has a contact region 21 arranged above at least one active region 5 in the vertical direction 92. At a position laterally offset with respect to the contact region 21, the top side 20 has at least one cover region 22 directly adjacent to the contact region 21. In particular, two cover regions 22 can be provided as shown directly adjacent to the contact region 21 at a position laterally offset with respect to the contact region 21. As can be particularly seen from FIG. 2A, the contact region 21 is arranged between two cover regions 22 in the lateral direction 91, which cover regions 22 are each directly adjacent to the contact region 21 in the lateral direction 91. The following description, which applies at least to the embodiment having two coverage areas, applies equally to the embodiments having semiconductor laser diodes having one coverage area or three or more coverage areas.

[0051] In the illustrated embodiment, the contact region 21 is formed by the top surface of the ridge 9 and at least partially by the side surfaces of the ridge 9. The contact region 21 accordingly has a main extension direction along the longitudinal direction, the shape of the ridge 9 being preferably formed in the following in the form of a stripe, which can preferably extend from the radiation exit surface to the rear surface. In the illustrated embodiment, the cover region 22 is formed by the part of the top surface 20 that is not formed by the contact region 21, i.e. by the part of the top surface 20 that is arranged adjacent to the ridge 9 laterally.

[0052] The transparent conductive cover layer 4 is applied continuously on the top side over the contact regions 21 and over the cover regions 22. In the exemplary embodiment shown, the cover layer 4 thus covers the entire contact region 21 and the entire cover region 22, and therefore the entire top side 20 is covered by the cover layer 4. In particular, in the exemplary embodiment shown, the cover layer 4 is in direct contact with the entire top side 20 of the semiconductor layer sequence 2, i.e. both in the contact regions 21 and in the cover regions 22.

[0053] The transparent conductive cover layer 4 comprises or consists of at least one TCO. In particular, the cover layer 4 can comprise or consist of one or more of the TCOs mentioned above in the general description, in particular selected from ITO, In2O3, SnO2, Sn2O3, ZnO, IZO and GZO. The cover layer 4 is arranged and arranged to inject a current from the top side into the semiconductor layer sequence 2, i.e. into the active layer 3, during operation of the semiconductor laser diode 100, and thus forms a transparent electrical contact. On the bottom side of the semiconductor layer sequence 2 opposite the top side 20, an electrode layer can be provided as a further electrical contact (not shown).

[0054] For electrical connection of the cover layer 4 from the outside, at least one metallic contact element 11 is arranged on the cover layer 4 on the side facing away from the semiconductor layer sequence 2 or at the cover layer 4. The contact element 11 can be a bonding layer for wire bonding or soldering of the semiconductor laser diode 100 and can be formed, for example, in a single layer or in multiple layers. For example, the contact element 11 can have or consist of aluminum and / or silver and / or gold. The contact element 11 is preferably arranged directly on the cover layer 4 as shown and can be provided over a large area above the ridge 9, which can be advantageous in particular if the semiconductor laser diode 100 is soldered with the contact element 11, i.e. with the p-side facing down ("p-down").

[0055] The exemplary embodiment shown in Fig. 2A, as well as further exemplary embodiments, are designed such that during operation, a higher current is injected into the upper surface 20 of the semiconductor layer sequence 2 via the contact region 21 than via the cover region 22. As mentioned in the overview, this can mean in particular that the current injection with the cover layer 4 takes place at least preferably or at least substantially or even exclusively via the contact region 21, whereas during operation of the semiconductor laser diode 100, less current is injected via the cover region 22 than via the contact region 21, or substantially no current is injected, or even no current is injected at all. This is achieved in the exemplary embodiment of Fig. 2A by the following: due to the ridge 9, the contact region 21 is formed completely on the ridge top surface and at least partially on the ridge side surfaces by the semiconductor contact layer as described with reference to Fig. 1C, whereas the cover region 22 is formed by a second cladding layer or a second waveguide layer, each of which has significantly less dopant than the semiconductor contact layer. Furthermore, the semiconductor contact layer can have a lower aluminum content or can be aluminum-free compared to the underlying layers, so that the contact region 21 has a lower electrical contact resistance to the cover layer 4 than the cover region 22, which facilitates the desired higher current injection in the contact region 21.

[0056] Thus, the ridge 9 can influence the current injection from the side of the top surface 20, as already mentioned. Furthermore, the ridge 9 can be formed as a ridge waveguide structure, as explained with reference to Figs. 1A-1C, which can provide refractive index guiding of the light generated in the active layer 3 during operation. Since both the selective current injection via the contact region 21 and the refractive index guiding provided by the ridge waveguide structure can contribute to the formation of the active region 5, which can be changed by modifying the ridge 9, the ridge 9, as already mentioned quite some time ago, constitutes an element 10 defining the active region, which is also called defining element for short, as mentioned in the overview part. As shown and previously explained, the defining element 10 is covered by a cover layer 4, which serves on the one hand as a transparent contact for the current supply. Since the cover layer 4 also directly covers in particular the ridge flanks, the cover layer 4 also influences the guiding of the ridge waveguide structure on the other hand by a jump in the refractive index at the corresponding interfaces. Furthermore, the cover layer 4 protects the optical mode in the semiconductor material from the metal of the contact element 11. This makes it unnecessary in the case of the illustrated semiconductor laser diode 100 to provide a passivation layer at the ridge, as is customary in the prior art, so that the semiconductor laser diode 100 according to the illustrated embodiment can be free of any dielectric material on the top surface 20. Furthermore, as in the illustrated embodiment, a separate metallic contact connection layer can be free of being provided on the top surface of the ridge.

[0057] As an alternative to the metallic contact elements 11 covering the entire contact region 21 over a large area, the contact elements 11 can also be arranged as one or more contact elements 11 only in one or more specific regions on the cover layer 4 that are required for an electrical connection by soldering or wire bonding. As shown in Figures 2B and 2C, the contact elements 11 can be arranged, for example, only laterally at the contact region 21, i.e., in the illustrated embodiment, at the ridge 9, on one side or, in the case of two metallic contact elements 11, on both sides. The laterally arrangement can serve to relieve mechanical loads on the ridge 9, especially in the "tripod"-type construction shown in Figure 2C, for example in the case of a "p-down" soldering attachment of the contact elements 11 on the support. Furthermore, in the illustrated embodiment of Figures 2B and 2C, the cover layer 4 can be made thinner than in the embodiment of Figure 2A, since no contact absorption is to be expected by the metallic contact elements 11 either.

[0058] FIG. 3 shows an embodiment of a semiconductor laser diode 100, according to which, in contrast to the previously described embodiment, a damage-treated semiconductor structure 12 is produced in a cover region 22 as an additional defining element 10 for producing the active region 5. In this embodiment, the cover region 22 also comprises the ridge side surfaces, whereas the contact region 21 is formed by the ridge top surface. The damage-treated semiconductor structure 12 is produced on the top surface 20 of the semiconductor layer sequence 2 that is exposed after the ridge production, except for the ridge top surface. In particular, the damage-treated semiconductor structure 12 can be produced within the framework of the ridge production, in particular as a final step of the ridge production. The damage-treated structure 12 can be produced, for example, by an etching process and / or sputtering, which is particularly preferably a dry etching process. The parameters of the etching process are then adjusted in such a way that the semiconductor material exposed to the etching medium is damaged by plasma and / or ion bombardment. In this case, no or only a small electrical contact is formed on the damaged top surface with the damaged semiconductor structure 12 to the cover layer 4, so that preferably no or practically no current can be injected in this region. This effect can be further enhanced by removing the highly doped semiconductor contact layer laterally of the ridge 9 in the cover region 22, as explained with reference to the previous embodiment. In the following embodiments, the damaged semiconductor structure 12 is always shown purely by way of example. However, the following embodiments can alternatively also be produced without a damaged semiconductor structure.

[0059] Although in the previous exemplary embodiments a single radiation source has been shown, the semiconductor laser diode 100 can also be formed as a so-called laser bar or multiple radiation source. As shown in FIG. 4, a number of contact regions 21 can be provided on the top surface 20. Accordingly, a number of active region-defining elements 10 are also provided, which are used to form a number of active regions 5 arranged laterally in the vertical direction below the contact region 21. The definition elements 10 are covered by a cover layer 4 as in the previous exemplary embodiment and, merely by way of example, have a ridge 9 and a damage-processed semiconductor structure 12. Simply by way of example, the semiconductor laser diode 100 of the exemplary embodiment of FIG. 4 is formed similarly to the exemplary embodiment of FIG. 3. The contact regions 21 and / or the definition elements 10 can generally be formed in the same way or differently. Furthermore, a number of cover regions 22 are provided, by which the contact regions 21 are separated from one another. As shown, the cover layer 4 can be arranged seamlessly above the contact regions 21 and the cover regions 22. This allows all active regions 5 to be controlled simultaneously. Alternatively, the cover layer 4 can also be divided into mutually separated sections, each of which is assigned to one active region 5 and is arranged, as described above, on the respectively assigned contact region 21 and partially on the respectively assigned cover region 22, so that the active regions 5 can be controlled independently of one another. In this case, a separate metallic contact element is assigned to each active region 5. Particularly preferably, the semiconductor layer sequence 2 and in particular the active layer 3 can be formed to generate visible light, so that the semiconductor laser diode 100 is a multiple radiation source in the visible wavelength range. The features described with reference to the exemplary embodiment mentioned above and also with reference to the following exemplary embodiment can also be applied to the semiconductor laser diode 100 of FIG. 4.

[0060] 5 shows a further exemplary embodiment of a semiconductor laser diode 100, according to which, in contrast to the previously described exemplary embodiment, a metallic contact layer 13 is arranged in a contact region 21 on the semiconductor layer sequence 2. The metallic contact layer 13 is in particular arranged in the contact region 21 on the upper surface 20 of the semiconductor layer sequence 2 directly adjacent to the upper surface 20 and is covered by a transparent conductive cover layer 4.

[0061] As material for the metallic contact layer 13, one or more metals can be used, for example, selected from Pt, Pd, Rh and Ni. The metallic contact layer 13 can increase the electrical coupling between the top surface 20 and the cover layer 4 in the contact region 21 by reducing the electrical contact resistance, and thus increase the current injection from the cover layer 4 into the semiconductor layer sequence 2 in the contact region 21, which can have an effect on the formation of the active region below the contact region 21. The metallic contact layer 13 can thus also form the defining element 10. In this configuration, as in the other exemplary embodiments, the semiconductor laser diode 100 does not need to be provided with a dielectric passivation, i.e. no dielectric material needs to be provided on the top surface 20, so that a better, i.e. lower, thermal resistance can be achieved on the top surface than in the prior art.

[0062] 6 shows an embodiment of a semiconductor laser diode 100 which, in contrast to the previously described embodiment, has a transparent conductive contact layer 14 directly above the contact region 21 instead of the metallic contact layer 13. The transparent conductive contact layer 14 can thus form a ridge 9 together with the underlying semiconductor material of the semiconductor layer sequence 2 in the contact region 21, so that the ridge 9 is formed by the semiconductor material of the semiconductor layer sequence 2 and the material of the transparent conductive contact layer 14. The transparent conductive contact layer 14 can in particular have a TCO, as explained above in connection with the cover layer 4. The transparent conductive contact layer 14 preferably has a first TCO, whereas the cover layer 4 has a different second TCO. The first TCO can preferably have a higher electrical conductivity and / or a lower electrical contact resistance to the semiconductor layer sequence 2 than the second TCO. For example, the first TCO may comprise ITO or ZnO, or may be ITO or ZnO, while the second TCO may be a different TCO, or may have a different stoichiometry. Different electrical properties of the material of the cover layer 4 and the material of the transparent conductive contact layer 14 may facilitate the above-mentioned different current injection in the contact region 21 and in the cover region 22, as in the already mentioned embodiments, and thus serve to define the active region.

[0063] As shown in FIG. 7, the ridge 9 can also be formed by a transparent conductive contact layer 14. This makes it possible to achieve a particularly low-cost production of the ridge 9, in particular a ridge waveguide structure. In particular, a first TCO can be deposited on the top surface of the completed semiconductor layer sequence 2 in the contact region 21 and structured into stripes forming the transparent conductive contact layer 14. At the same time, the regions on the sides of the stripe, i.e. the cover region 22, can be treated by suitable measures, for example by damage processing and / or sputtering and / or oxidation, in order to increase the electrical contact resistance to the subsequently applied material, in particular to the material of the cover layer 4, by forming the damage-processed semiconductor structure 12. To form the cover layer 4, a second TCO having a smaller refractive index than the first TCO is deposited on and to the sides of the first TCO of the transparent conductive contact layer 14. This again results in a lateral refractive index jump for the light waves generated in the active layer 3 during operation, which thus results in the above-mentioned lateral waveguiding, i.e. the refractive index waveguiding. At the same time, it can be achieved that the current is injected into the upper surface 20 of the semiconductor layer sequence 2 only in the regions of higher refractive index, i.e. in the contact regions 21, or at least substantially only in these regions, so that a so-called self-aligned ridge laser is formed. As in the previous exemplary embodiment, the contact layer 14 and the cover layer 4 can each have a different TCO or can each consist of a different TCO, i.e. can have different materials, such as zinc oxide and tin oxide, and / or different material compositions and / or stoichiometries. A particular advantage of this exemplary embodiment is that substantially no etching of the semiconductor material is required, and therefore no lateral refractive index jumps have to be adjusted by means of precise etching depths, which is relatively difficult to achieve precisely from a technical standpoint. Instead, only a coating with the material of the transparent conductive contact layer 14 is required, which can be selected with the right refractive index and can be applied to the right thickness.

[0064] As further shown in FIG. 8, the cover layer 4 can have two or more TCOs. In particular, the cover layer 4 can have different layers with different TCOs or can consist of such layers. Such possibilities can be combined with other embodiments described herein. In particular, the cover layer 4 can have a first layer 41 with a first TCO at least in the contact region 21 and a second layer 42 with a second TCO different from the first TCO in the cover region 22. The second TCO can be at least partially covered by the first TCO. The first layer 41 can thus cover the second layer 42 in the cover region as shown. In particular, the second layer 42 can be arranged only in the cover region 22 as shown, so that in the contact region 21 the second layer 42 is not arranged either above or below the first layer 41. Thus, the transparent contact formed by the cover layer 4 can be constructed from several layers, with the second layer 42 preferably not extending above the contact region 21 .

[0065] For example, in the cover region 22, i.e. in the region to the side of the contact region 21, which in the illustrated embodiment also means to the side of the ridge 9, a second TCO with a particularly low absorption can be used, but for this purpose it has, for example, a lower electrical conductivity than the first TCO. This is covered by the first TCO with a high electrical conductivity, which in this way also forms an electrical connection to the semiconductor material in the contact region 21. In this case, the first TCO can have, for example, a higher optical absorption than the second TCO. The first and second layers 41, 42 of the cover layer 4 can thus additionally form the defining element 10.

[0066] 2A-8 each include a ridge 9 which, depending on its configuration, may provide index guiding. Alternatively, the semiconductor laser diode 100 may include the features described above for defining the active region 5, excluding the ridge 9, and may therefore be based on a gain guiding scheme.

[0067] 9 shows, purely by way of example, a semiconductor laser diode 100, which is constructed like the embodiment of FIG. 3 except for the ridge and is formed as a gain-guided laser, in which the top surface 20, but only in the contact window forming the contact region 21, is not damaged, for example by plasma or sputtering, for forming a damaged semiconductor structure 12 in the cover region 22. This results in no or only a slight step in the top surface 20, so that essentially no ridge is formed or only a ridge of a slight height is formed. In particular, the top surface 20 can be formed in the cover region 22, as in the contact region 21, by a semiconductor contact layer, which can typically have a thickness in the range of 30 nm to 200 nm and is at most only partially removed in the cover region 22. If a ridge is provided, it therefore has a height slightly less than the thickness of the semiconductor contact layer. As mentioned above, the damage-treated semiconductor structure 12 makes it possible to achieve that an electrical contact between the semiconductor layer sequence 2 and the cover layer 4 effectively only occurs in the contact regions 21 .

[0068] As an alternative to the exemplary embodiments described above, in which the cover layer 4 always covers the entire upper surface 20 of the semiconductor layer sequence 2 in each case, the cover layer 4 can also cover only a portion of the upper surface 20 of the semiconductor layer sequence 2 in the exemplary embodiments shown. In this case, the portions of the upper surface 20 that are not covered in this case by the cover layer 4 are respectively selected such that they have no effect on the formation of the active region 5 and thus on the optical properties of the semiconductor laser diode 100, regardless of whether a cover layer 4 is provided thereon. In particular, the cover layer 4 always extends laterally over the upper surface 20 of the semiconductor layer sequence 2, i.e. over at least a portion of the contact region 21 and the cover region 22, insofar as the regions that are not covered by the cover layer 4 also have no effect on the active region 5. The exemplary embodiments shown so far can therefore also form part of a semiconductor laser diode 100 in which further elements can be provided at a considerable distance from the active region 5 in the lateral direction 91.

[0069] FIG. 10 shows an embodiment of a semiconductor laser diode 100, which corresponds to the embodiment of FIG. 3, purely by way of example, with regard to the configuration around the active region 5. At a considerable distance from the active region 5 in the lateral direction 91, in this embodiment on both sides of the active region, mesa trenches 18 are provided in the semiconductor layer sequence 2, which can extend through the active layer 3 and be passivated by a dielectric material 19, which has no effect on the laser mode, and thus on the active region 5. The semiconductor layer sequence 2 around the contact region 21 is thus covered only by the cover layer 4 and the electrical contact elements 11, which ensures good heat transfer. As shown, the cover layer 4 and the semiconductor layer sequence 2 can be covered, for example, completely or partially, by the dielectric material 19 in a region remote from the active region 5, which region can be left uncovered, for example, by the electrical contact elements 11. This makes the semiconductor laser diode 100 more stable against chemical attack and leakage currents can be avoided, for example, at the mesa edges.

[0070] The embodiments and features shown in the drawings are not limited to the combinations shown in the drawings, respectively. Rather, the illustrated embodiments and individual features can be combined with one another, even if not all combination possibilities are explicitly stated. Moreover, the embodiments illustrated in the drawings can alternatively or additionally have further features that are described in the general description.

[0071] The invention is not limited to the embodiments described herein, but rather includes each and every novel feature and each and every combination of features, and in particular includes each and every combination of features in the claims, even if those features or combinations themselves are not explicitly recited in the claims or examples. [Explanation of symbols]

[0072] 1 Board 2. Semiconductor Layer Sequence 3 Active layer 4 Cover Layer 5 Active area 6 Light exit surface 7 Back 8 light 9. Ridge 10. Factors that define the active region 11 Contact element 12. Damage-treated semiconductor structure 13 Metal contact layer 14 Transparent conductive contact layer 18 Mesa Trench 19 Dielectric Materials 20 Top side 21 Contact Area 22 Coverage Area 31 Buffer layer 32, 35 Cladding layer 33, 34 Waveguide layer 41 First Layer 42 Second Layer 91 Horizontal 92 Vertical 93 Longitudinal 100 Semiconductor laser diode

Claims

1. A semiconductor laser diode, a vertically grown semiconductor layer sequence; a transparent conductive cover layer provided on said semiconductor layer sequence; the semiconductor layer sequence comprises an active layer arranged to generate light in at least one active region extending in a longitudinal direction during operation, the semiconductor layer sequence terminates in a vertical direction at an upper surface which has a contact region arranged in the vertical direction above the active region and at least one cover region which is directly connected to the contact region in a lateral direction perpendicular to the vertical direction and to the longitudinal direction, the transparent conductive cover layer is disposed on a top surface thereof, contiguous over the contact area and the at least one cover area; the transparent conductive cover layer is provided directly on the top side of the semiconductor layer sequence at least in the at least one cover region, at least one element defining said at least one active area is provided, said element being covered by said transparent conductive cover layer; the transparent conductive cover layer has a first layer with a first transparent conductive oxide at least in the contact area and a second layer with a second transparent conductive oxide different from the first transparent conductive oxide in the at least one cover area, the first layer covering the second layer in the at least one cover area; Semiconductor laser diode.

2. the second layer is disposed only within the at least one cover region.

2. The semiconductor laser diode according to claim 1.

3. The second transparent conductive oxide has a lower optical absorption rate than the first transparent conductive oxide.

3. The semiconductor laser diode according to claim 1 or 2.

4. a metallic contact element is arranged on the transparent conductive cover layer on its side facing away from the semiconductor layer sequence.

2. The semiconductor laser diode according to claim 1.

5. The metallic contact element is a bond layer for wire bonding or soldering the semiconductor laser diode.

5. The semiconductor laser diode according to claim 4.

6. At least one element defining the active region has a ridge formed in an upper contact region.

2. The semiconductor laser diode according to claim 1.

7. the ridge is formed by a portion of the semiconductor layer sequence.

7. The semiconductor laser diode according to claim 6.

8. the ridge providing a ridge waveguide structure for index guiding of light generated within the active region.

8. The semiconductor laser diode according to claim 6 or 7.

9. the ridge has a low height such that the ridge does not provide index guiding of light generated in the active region.

8. The semiconductor laser diode according to claim 6 or 7.

10. the ridge having a transparent conductive contact layer; 8. The semiconductor laser diode according to claim 6 or 7.

11. the ridge is formed by a transparent conductive contact layer formed by a transparent conductive oxide; 7. The semiconductor laser diode according to claim 6.

12. the at least one element defining the active region has a semiconductor structure that has been subjected to a damage formation process within the at least one cover region; 2. The semiconductor laser diode according to claim 1.

13. the damage-treated semiconductor structure is formed on the top surface of the semiconductor layer sequence.

13. The semiconductor laser diode according to claim 12.

14. a metallic or transparent conductive contact layer is arranged on the top surface of the semiconductor layer sequence in the contact region directly adjacent to the top surface, the metallic or transparent conductive contact layer being covered by the transparent conductive cover layer.

3. The semiconductor laser diode according to claim 1 or 2.

15. the semiconductor laser diode is free of any dielectric material on the top surface that acts on the active region; 3. The semiconductor laser diode according to claim 1 or 2.

16. a plurality of contact regions on the top surface; a plurality of active regions are present in the active layer during operation, with a respective contact region disposed vertically above each of the active regions; the contact areas are separated from one another by cover areas of a plurality of cover areas; a plurality of elements defining the active area are provided, the elements being covered by the transparent conductive cover layer; 2. The semiconductor laser diode according to claim 1.

17. the transparent conductive cover layer is disposed seamlessly over the plurality of contact areas and the plurality of cover areas; 17. The semiconductor laser diode of claim 16.

18. the transparent conductive cover layer is divided into a plurality of mutually separated sections, each of which is assigned to one active area; 17. The semiconductor laser diode of claim 16.

19. 3. A method for manufacturing a semiconductor laser diode according to claim 1, comprising the steps of: Providing a semiconductor layer sequence having an active layer and a top surface with contact regions and at least one cover region; forming at least one element defining an active area; providing the transparent conductive cover layer continuously over the contact area and over the at least one cover area; A method for manufacturing a semiconductor laser diode comprising the steps of:

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