US20160365699A1 - Laser Diode Chip Having Coated Laser Facet - Google Patents
Laser Diode Chip Having Coated Laser Facet Download PDFInfo
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- US20160365699A1 US20160365699A1 US15/118,041 US201515118041A US2016365699A1 US 20160365699 A1 US20160365699 A1 US 20160365699A1 US 201515118041 A US201515118041 A US 201515118041A US 2016365699 A1 US2016365699 A1 US 2016365699A1
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- layer
- reflection
- diode chip
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/028—Coatings ; Treatment of the laser facets, e.g. etching, passivation layers or reflecting layers
- H01S5/0282—Passivation layers or treatments
- H01S5/0283—Optically inactive coating on the facet, e.g. half-wave coating
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/028—Coatings ; Treatment of the laser facets, e.g. etching, passivation layers or reflecting layers
- H01S5/0282—Passivation layers or treatments
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/024—Arrangements for thermal management
- H01S5/02469—Passive cooling, e.g. where heat is removed by the housing as a whole or by a heat pipe without any active cooling element like a TEC
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/028—Coatings ; Treatment of the laser facets, e.g. etching, passivation layers or reflecting layers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/028—Coatings ; Treatment of the laser facets, e.g. etching, passivation layers or reflecting layers
- H01S5/0281—Coatings made of semiconductor materials
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/028—Coatings ; Treatment of the laser facets, e.g. etching, passivation layers or reflecting layers
- H01S5/0287—Facet reflectivity
Definitions
- the invention relates to a laser diode chip having at least one laser facet with a coating.
- Laser diode chips capable of emitting in the UV spectral range, the visible spectral range or the infrared spectral range, for example, are used in many applications such as projection devices, in lighting technology or optical sensors, for example for gesture recognition.
- Embodiments of the invention provide a laser diode chip which is characterized by improved long term stability.
- the laser diode chip has at least one laser facet with a coating.
- the laser facet forms one of the resonator mirrors of the laser diode chip.
- the laser diode chip may be an edge emitter laser diode chip in which the resonator mirror is formed by two laser facets located opposite to one another.
- both laser facets each have one coating, where the coatings may be different from one another at least in their optical properties, particularly the reflectivity.
- at least the laser facet of the laser diode chip serving as the radiation exit surface has the coating described herein.
- the coating of the at least one laser facet advantageously comprises at least one inorganic layer, preferably multiple inorganic layers, and at least one organic layer.
- the coating is an inorganic-organic hybrid structure.
- the at least one inorganic layer contained in the coating may be a reflection-increasing or reflection-reducing layer, for example.
- the coating may contain multiple inorganic layers, which are at least partially contained in a reflection-reducing or reflection-increasing layer sequence.
- the reflectivity of the laser facet can specifically be adjusted by the reflection-increasing or reflection-decreasing layer or layer sequence.
- At least one additional function of the coating may be realized by the at least one organic layer contained in the coating.
- the at least one organic layer may have the function of a protective layer, which particularly improves the long-term stability of the laser diode chip.
- the at least one organic layer particularly allows reducing the diffusion of moisture and the adsorption of particles.
- the inorganic-organic hybrid structure is characterized by an improved protection of the laser diode chip against degradation when compared to purely inorganic coatings.
- the at least one inorganic layer of the coating is advantageously produced by atomic layer deposition (ALD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PEVCD), ion beam deposition (IBD) or ion plating (IP).
- ALD atomic layer deposition
- CVD chemical vapor deposition
- PEVCD plasma enhanced chemical vapor deposition
- IBD ion beam deposition
- IP ion plating
- the at least one organic layer is preferably produced by molecular vapor deposition (MVD) or molecular layer deposition (MLD). These deposition methods are particularly suitable for producing organic layers serving as a diffusion barrier. Furthermore, the at least one organic layer can be produced by a physical vapor deposition (PVD) method, a sol gel process or by dip coating, for example.
- PVD physical vapor deposition
- the at least one organic layer comprises a diffusion barrier layer.
- the organic diffusion barrier layer particularly forms a barrier for moisture and/or oxygen. This achieves reducing a degradation of the laser facet, particularly caused by oxidation.
- the at least one organic layer provides the advantage of being relatively elastic when compared to inorganic dielectric layers, so that the organic layer is capable of elastic deformation in the case of operational temperature changes. This achieves reducing the risk of crack formation in the coating caused by thermally-induced stress.
- the at least one organic layer, particularly the diffusion barrier layer preferably contains an alkane, an alkene, an alkyne, a cycloalkane, a cycloalkene, a polyamide or an aluminum alkoxide.
- the at least one organic layer comprises an organic cover layer.
- the organic cover layer is the outmost layer of the coating adjacent to the surrounding medium.
- the organic cover layer is a hydrophobic layer and/or a non-stick layer.
- the surface of the coating facing away from the laser facet preferably is hydrophobic and/or adhesion-inhibiting. Penetration of moisture and/or particle adsorption is advantageously reduced by the hydrophobic layer and/or the non-stick layer.
- the organic cover layer has a contact angle for water greater than 90°. The contact angle is a measure for the wettability of the surface with water.
- the organic cover layer may particularly comprise carbon nanotubes, an organic fluorine or sulfur compound, a thiol or a silane. These materials are particularly suitable for the formation of a hydrophobic layer.
- the organic cover layer is a monolayer, particularly a self-assembled monolayer (SAM).
- the organic cover layer contains a chlorosilane, an amine, an alcohol, a carbon acid, a siloxane or a dimethylamino silane. These materials are particularly suitable for formation of a non-stick layer.
- the non-stick layer is preferably applied by a molecular vapor deposition (MVD) method.
- the water-repellent or adhesion-inhibiting property of the organic cover layer may depend on the material of the cover layer, particularly the chemical properties of the surface, and/or the structure thereof.
- the organic cover layer may have a surface structure by means of which a water-repellant effect, the so-called lotus effect, is achieved.
- the at least one inorganic layer comprises a heat conductive layer.
- the heat conductive layer allows advantageously dissipating heat that develops during operation of the laser diode chip at the laser facet.
- Transparent conductive oxides such as ITO or ZnO are preferred materials for the heat conductive layer.
- Further preferred materials include GaN, AlN, diamond-like carbon (DLC), SiC or graphene.
- the heat conductive layer may particularly also be electrically conductive. This is why it is advantageous to not attach or apply the heat conductive layer directly to the laser facet, since otherwise there would be a short-circuit risk for the semiconductor layers of the laser diode chip.
- the heat conductive layer may also be directly applied or attached to the laser facet. In this case, heat can be dissipated from the laser diode chip in a particularly good manner.
- the heat conductive layer is arranged between a first organic diffusion barrier layer and a second organic diffusion barrier layer.
- the organic diffusion barrier layers are comparatively elastic and therefore capable of compensating a temperature-dependent expansion of the heat conductive layer preferably in the elastic expansion range.
- the at least one inorganic layer comprises a dielectric protective layer, which is directly adjacent to the laser facet.
- the dielectric protective layer is a layer produced by atomic layer deposition. Atomic layer deposition allows producing especially dense layers, the dense layers particularly forming a diffusion barrier for moisture.
- the dielectric protective layer preferably comprises one oxide, nitride or oxynitride.
- the coating may particularly comprise multiple inorganic layers.
- the inorganic layers are at least partially arranged in a reflection-increasing or reflection-decreasing layer sequence.
- the reflection-increasing or reflection-decreasing layer sequence may particularly comprise alternating layers having a refractive index that alternates between higher and lower values.
- the inorganic layers of the coating preferably contain dielectric materials, particularly oxides, nitrides or oxynitrides.
- the inorganic layers may particularly comprise at least one of the materials SiO 2 , Al 2 O 3 , TiO 2 , Ta 2 O 5 , Si 3 N 4 , ZrO 2 , HfO 2 , Nb 2 O 5 , Y 2 O 3 , Ho 2 O 3 , CeO 3 , Lu 2 O 3 , V 2 O 5 , HfZrO, MgO, TaC, ZnO, CuO, In 2 O 3 , Yb 2 O 3 , Sm 2 O 3 , Nd 2 O 3 , Sc 2 O 3 , B 2 O 3 , Er 2 O 3 , Dy 2 O 3 , Tm 2 O 3 , SrTiO 3 , BaTiO 3 , PbTiO 3 , PbZrO 3 , Ga
- reflection-increasing or reflection-decreasing layer sequence consists exclusively of inorganic layers.
- the coating comprises a heat conductive layer arranged between a dielectric reflection-increasing or reflection-decreasing layer sequence and an organic diffusion barrier layer.
- the heat conductive layer is advantageously insulated from the laser facet by the dielectric reflection-increasing or reflection-decreasing layer sequence, which may therefore also comprise an electrically-conductive material.
- the reflection-increasing or reflection-decreasing layer sequence contains both inorganic and organic layers, particularly alternating inorganic and organic layers.
- the reflection-increasing or reflection-decreasing layer sequence may particularly comprise alternating inorganic layers having a high refractive index and organic layers having a low refractive index, or, as an alternative, alternating inorganic layers having a low refractive index and organic layers having a high refractive index.
- the inorganic and/or organic layers advantageously have a thickness between 1 nm and 350 nm, preferably between 5 nm and 200 nm, and particularly preferably between 10 nm and 100 nm.
- the number of layers in the reflection-increasing layer sequence advantageously ranges between 2 and 50, particularly preferably between 4 and 20.
- FIG. 1 a schematic illustration of a cross-section through a partial region of a laser diode chip according to a first exemplary embodiment
- FIG. 2 a schematic illustration of a cross-section through a partial region of a laser diode chip according to a second exemplary embodiment
- FIG. 3 a schematic illustration of a cross-section through a partial region of a laser diode chip according to a third exemplary embodiment
- FIG. 4 a schematic illustration of a cross-section through a partial region of a laser diode chip according to a fourth exemplary embodiment
- FIG. 5 a schematic illustration of a cross-section through a partial region of a laser diode chip according to a fifth exemplary embodiment
- FIG. 6 a schematic illustration of a cross-section through a partial region of a laser diode chip according to a sixth exemplary embodiment
- FIG. 7 a schematic illustration of a cross-section through a partial region of a laser diode chip according to a seventh exemplary embodiment
- FIG. 8 a schematic illustration of a cross-section through a partial region of a laser diode chip according to an eighth exemplary embodiment.
- the laser chip diode 1 schematically shown in cross-section in FIG. 1 comprises a semiconductor layer sequence attached to a substrate 6 .
- the semiconductor layer sequence contains a buffer layer 2 applied to the substrate 6 , a first cladding layer 3 a, a first waveguide layer 4 a, an active layer 5 , a second waveguide layer 4 b and a second cladding layer 3 b.
- the semiconductor layer sequence may contain further layers, which are not shown for simplification.
- at least partial regions of the semiconductor layer sequence may be structured, for example as a ridge waveguide structure. Suitable waveguide structures for laser diode chips are known per se and thus not shown in detail for simplification.
- the active layer 5 of the edge-emitting semiconductor laser can be configured as pn-junction, double hetero structure, single quantum well structure or multi quantum well structure, for example.
- quantum well structure includes any structure in which charge carriers receive quantization of their energy states by confinement.
- quantum well structure does not contain information regarding the dimensionality of the quantization. Thus, it comprises, inter alia, quantum wells, quantum wires and quantum dots and any combination of these structures.
- the semiconductor layer sequence of the laser diode chip 1 is preferably based on a III-V-compound semiconductor material, particularly on an arsenide, nitride or phosphide compound semiconductor material.
- the semiconductor layer sequence may contain In x Al y Ga 1-x-y As, In x Al y Ga 1-x-y N or In x Al y Ga 1-x-y P, each with 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1 and x+y ⁇ 1.
- the III-V-compound semiconductor material does not need to have a mathematically-exact composition according to one of the above formulas. It may rather comprise one or multiple dopants as well as additional components that do not substantially change the physical properties of the material.
- the above formulas do only contain the essential components of the crystal lattice for simplification, even though the components may be replaced by minor quantities of further materials.
- the substrate 6 is selected by the preferably epitaxially-grown semiconductor sequence and may particularly comprise GaAs, sapphire, SiC, GaN or silicon.
- a first contact layer 7 is arranged on a rear side of the substrate 6 facing away from the semiconductor layer sequence and a second contact layer 8 is arranged on the side of the semiconductor layer sequence facing away from the substrate 6 .
- the laser diode chip 1 comprises a laser facet 9 provided with a coating 10 .
- the laser facet 9 can particularly form one of the resonator mirrors of the laser diode chip 1 .
- a further laser facet which is not shown in the detail and which is located opposite the laser facet 9 can form a second resonator mirror of the laser diode chip and be provided with a further coating, which may have the same advantageous configurations as the coating 10 of the laser facet 9 to be described in the following.
- the further coating does not need to be identical to the coating 10 but may have optical properties different from that of the coating 10 , particularly a different reflectivity, for example.
- the laser facet 9 provided with the coating 10 can particularly be provided as a radiation exit surface of the laser diode chip 1 .
- coating 10 comprises a first reflection-increasing or reflection-decreasing layer sequence ii, which has multiple alternating first layers 13 and second layers 14 .
- the reflection-increasing or reflection-decreasing layer sequence 11 in the exemplary embodiment has three layer pairs composed of first layers 13 and second layers 14 , that is a total number of 6 layers.
- the number of layers 13 , 14 is between 2 and 50, preferably between 4 and 20.
- the alternating layers 13 , 14 are inorganic dielectric layers respectively, which alternate between having a high refractive index or a low refractive index.
- the reflection-increasing or reflection-decreasing layer sequence 11 may have alternating first layers 13 made of Al 2 O 3 and second layers 14 made of one of the materials TiO 2 , ZrO 2 or Ta 2 O 5 , for example.
- the first layers each have a low refractive index and the second layers each have a high refractive index.
- the first layers may have a high refractive index, the second layers having a low refractive index.
- the reflection-increasing or reflection-decreasing layer sequence 11 may also have or comprise an uneven number of layers, i.e., a further layer with a low or high refractive index is contained in the layer sequence 11 in addition to the layer pairs.
- coating 10 further comprises a second reflection-increasing or reflection-decreasing layer sequence 12 , which is composed of alternating third layers 15 and fourth layers 16 , which just like in the first reflection-increasing or reflection-decreasing layer sequence 11 , advantageously have alternating low refractive indices and high refractive indices.
- a second reflection-increasing or reflection-decreasing layer sequence 12 is composed of alternating third layers 15 and fourth layers 16 , which just like in the first reflection-increasing or reflection-decreasing layer sequence 11 , advantageously have alternating low refractive indices and high refractive indices.
- Use of two successive reflection-increasing or reflection-decreasing layer sequences 11 , 12 may be appropriate, for example to adjust the material of the first reflection-increasing or reflection-decreasing layer sequence ii with respect to the thermal expansion coefficient to the adjacent semiconductor material of the laser diode chip.
- coating 10 only contains one reflection-increasing or reflection-decreasing layer sequence 11 . It is also possible that a reflection-increasing or reflection-decreasing single layer is used instead of the first and/or second reflection-increasing or reflection-decreasing layer sequence 11 , 12 .
- the first reflection-increasing or reflection-decreasing layer sequence 11 or the second reflection-increasing or reflection-decreasing layer sequence 12 comprises alternating inorganic and organic layers.
- the first reflection-increasing or reflection-decreasing layer sequence 11 comprises organic first layers 13 and inorganic second layers 14 , for example.
- the organic layers 13 integrated in the reflection-increasing or reflection-decreasing layer sequence 11 provide the advantage that they are comparatively elastic when compared to inorganic dielectric layers. This is particularly advantageous if temperature-dependent stress occurs during operation of the laser diode 1 .
- coating 10 advantageously comprises a cover layer 20 , which is a hydrophobic organic layer in the exemplary embodiment of FIG. 1 .
- the hydrophobic organic cover layer 20 has a contact angle for water greater than 90°.
- the hydrophobic organic cover layer 20 particularly serves for protection of the laser facet 9 against moisture.
- the hydrophobic organic cover layer 20 may contain carbon nanotubes, organic fluorine or sulfur compounds, which in particular contain thiol or silane groups.
- the hydrophobic organic cover layer 20 preferably is a monolayer, particularly a self-assembled monolayer.
- FIG. 2 illustrates a second exemplary embodiment of the laser diode chip 1 .
- This embodiment is different from the first exemplary embodiment in that the an organic layer follows the second reflection-increasing or reflection-decreasing layer sequence 12 in the growth direction of the layer 10 , which particularly is a diffusion barrier layer 21 for reducing the diffusion of oxygen or moisture.
- the laser facet 9 is even better protected against oxidation.
- the organic diffusion barrier layer 21 preferably contains an alkane, alkene, alkyne, a cycloalkane, cycloalkene, a polyamide or an aluminum alkoxide.
- the second exemplary embodiment corresponds to the above described first exemplary embodiment.
- a coating 10 is applied to the laser facet 9 , which comprises, starting from the laser facet 9 , a dielectric protective layer 18 , a reflection-increasing or reflection-decreasing layer sequence ii and an organic diffusion barrier layer 21 .
- the dielectric protective layer 18 is directly adjacent to the laser facet 9 and preferably is a layer produced by atomic layer deposition. Atomic layer deposition allows depositing especially dense dielectric layers, the layers providing an especially good protection against the penetration of moisture.
- the dielectric protective layer preferably comprises an oxide, nitride or oxynitride.
- the dielectric protective layer 18 may comprise SiO 2 , Si(O x N 1-x ) 2 , Al S O 3 or Al 2 (O x N 1-x ) 3 or combinations thereof, for example.
- the reflection-increasing or reflection-decreasing layer sequence 11 following the dielectric protective layer 18 corresponds to the first exemplary embodiment regarding the advantageous configurations thereof.
- the organic layer 21 may serve particularly as a diffusion barrier. In this exemplary embodiment, it simultaneously forms the cover layer of the coating 10 .
- the organic diffusion barrier layer 21 provides the advantage that it is comparatively elastic and thus particularly tear-resistant when compared to inorganic layers. This reduces the risk that cracks occur in the diffusion barrier layer 21 during operation of the laser diode chip 1 , for example caused by temperature-dependent stress.
- a coating 10 is applied to the laser facet 9 , the coating comprising, starting from the laser facet 9 , a reflection-increasing or reflection-decreasing layer sequence 11 , a heat-conductive barrier layer 21 and a hydrophobic organic layer 20 as a cover layer.
- This exemplary embodiment is different from the above described second exemplary embodiment in that the heat-conductive layer 17 is advantageously arranged between the reflection-increasing or reflection-decreasing layer sequence ii and the organic diffusion barrier layer 21 , making it possible to dissipate at least part of the heat developing during operation of the laser diode chip 1 through the layer 17 .
- the heat-conductive layer 17 may particularly also comprise an electrically-conductive material, since it is insulated from the semiconductor layer sequence of the laser diode 1 by the dielectric reflection-increasing layer sequence 11 .
- the heat-conductive layer 17 may contain ITO, ZnO, GaN, AlN, diamond-like carbon (DLC), SiC or graphene, for example.
- the fifth exemplary embodiment shown in FIG. 5 is different from the fourth exemplary embodiment in that an organic non-stick layer 22 is contained in the coating 10 as cover layer in place of the hydrophobic organic cover layer.
- the non-stick layer 22 reduces adsorption of particles at the laser facet. Otherwise, such particle adsorption could occur as a consequence of the electrostatic interactions during operation of the laser diode chip 1 .
- the non-stick layer 22 is applied by an MVD method or an MLD method and preferably contains a chlorosilane, an amine, an alcohol, a carbon acid, a siloxane or a dimethylamino silane.
- the coating 10 comprises, starting from the laser facet 9 , a dielectric protective layer 18 , a heat conductive layer 17 , a reflection-increasing or reflection-decreasing layer sequence 11 and a hydrophobic organic layer 20 as cover layer.
- the coating 10 comprises, starting from the laser facet 9 , a reflection-increasing or reflection-decreasing layer sequence 11 , a first organic diffusion barrier layer 21 a, a heat-conductive layer 17 , a second organic diffusion barrier layer 21 b and a hydrophobic organic cover layer 20 .
- the heat-conductive layer 17 is arranged between two organic diffusion barrier layers 21 a, 21 b, the latter being elastic and thus being capable of compensating a temperature-dependent expansion of the heat-conductive layer 17 preferably in the elastic expansion range.
- the functions and advantageous configurations of the individual layers correspond to the exemplary embodiments described above and will thus not be explained in further detail.
- the coating comprises, starting from the laser facet 9 , a dielectric protective layer 18 , a reflection-increasing or reflection-decreasing layer sequence 11 , a heat-conductive layer 17 , an organic diffusion barrier layer 21 and a hydrophobic organic layer 20 as a cover layer.
- a hydrophobic organic cover layer 20 an organic non-stick layer could serve as cover layer just as well.
Abstract
A laser diode chip has a laser facet, which includes a coating. The coating includes an inorganic layer and an organic layer. In one example, the coating has a number of inorganic layers, including a heat-conductive layer. For example, the inorganic layers may form a reflection-increasing or reflection-decreasing layer sequence.
Description
- This patent application is a national phase filing under section 371 of PCT/EP2015/053218, filed Feb. 16, 2015, which claims the priority of
German patent application 10 2014 102 360.9, filed Feb. 24, 2014, each of which is incorporated herein by reference in its entirety. - The invention relates to a laser diode chip having at least one laser facet with a coating.
- Laser diode chips capable of emitting in the UV spectral range, the visible spectral range or the infrared spectral range, for example, are used in many applications such as projection devices, in lighting technology or optical sensors, for example for gesture recognition.
- Many laser diode chip applications utilize the achievable high optical power density. However, the high optical power density reached in laser diodes results in the light-emitting laser facet being particularly exposed to very high electric, optical and thermal loads. In particular, it turned out that oxidation of the laser facet may occur when operating the laser diode under the influence of moisture, the oxidation leading to a degradation of the laser diode chip. Furthermore, there is a risk of particles adsorbing at the laser facet as a result of the electrostatic interaction when operating the laser diode chip, what may lead to shadowing effects in the far field, a reduced slope of the laser characteristic curve or overheating of the mirror and even the catastrophic optical damage (COD, German: Zerstörung).
- Further, high sensitivity of the laser facets requires very high efforts in the mounting of the laser diode chip.
- Embodiments of the invention provide a laser diode chip which is characterized by improved long term stability.
- According to at least one embodiment, the laser diode chip has at least one laser facet with a coating. In particular, the laser facet forms one of the resonator mirrors of the laser diode chip. In particular, the laser diode chip may be an edge emitter laser diode chip in which the resonator mirror is formed by two laser facets located opposite to one another. In this case, preferably both laser facets each have one coating, where the coatings may be different from one another at least in their optical properties, particularly the reflectivity. Preferably, at least the laser facet of the laser diode chip serving as the radiation exit surface has the coating described herein.
- In the laser diode chip, the coating of the at least one laser facet advantageously comprises at least one inorganic layer, preferably multiple inorganic layers, and at least one organic layer. In other words, the coating is an inorganic-organic hybrid structure.
- The at least one inorganic layer contained in the coating may be a reflection-increasing or reflection-reducing layer, for example. In particular, the coating may contain multiple inorganic layers, which are at least partially contained in a reflection-reducing or reflection-increasing layer sequence. The reflectivity of the laser facet can specifically be adjusted by the reflection-increasing or reflection-decreasing layer or layer sequence.
- Advantageously, at least one additional function of the coating may be realized by the at least one organic layer contained in the coating. In particular, the at least one organic layer may have the function of a protective layer, which particularly improves the long-term stability of the laser diode chip. The at least one organic layer particularly allows reducing the diffusion of moisture and the adsorption of particles. As a result, the inorganic-organic hybrid structure is characterized by an improved protection of the laser diode chip against degradation when compared to purely inorganic coatings.
- The at least one inorganic layer of the coating is advantageously produced by atomic layer deposition (ALD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PEVCD), ion beam deposition (IBD) or ion plating (IP).
- The at least one organic layer is preferably produced by molecular vapor deposition (MVD) or molecular layer deposition (MLD). These deposition methods are particularly suitable for producing organic layers serving as a diffusion barrier. Furthermore, the at least one organic layer can be produced by a physical vapor deposition (PVD) method, a sol gel process or by dip coating, for example.
- According to one embodiment, the at least one organic layer comprises a diffusion barrier layer. The organic diffusion barrier layer particularly forms a barrier for moisture and/or oxygen. This achieves reducing a degradation of the laser facet, particularly caused by oxidation.
- Furthermore, the at least one organic layer provides the advantage of being relatively elastic when compared to inorganic dielectric layers, so that the organic layer is capable of elastic deformation in the case of operational temperature changes. This achieves reducing the risk of crack formation in the coating caused by thermally-induced stress.
- The at least one organic layer, particularly the diffusion barrier layer, preferably contains an alkane, an alkene, an alkyne, a cycloalkane, a cycloalkene, a polyamide or an aluminum alkoxide.
- According to an advantageous configuration, the at least one organic layer comprises an organic cover layer. In this configuration, the organic cover layer is the outmost layer of the coating adjacent to the surrounding medium.
- Advantageously, the organic cover layer is a hydrophobic layer and/or a non-stick layer. In this case, the surface of the coating facing away from the laser facet preferably is hydrophobic and/or adhesion-inhibiting. Penetration of moisture and/or particle adsorption is advantageously reduced by the hydrophobic layer and/or the non-stick layer. Advantageously, the organic cover layer has a contact angle for water greater than 90°. The contact angle is a measure for the wettability of the surface with water.
- The organic cover layer may particularly comprise carbon nanotubes, an organic fluorine or sulfur compound, a thiol or a silane. These materials are particularly suitable for the formation of a hydrophobic layer. Preferably, the organic cover layer is a monolayer, particularly a self-assembled monolayer (SAM).
- In another preferred configuration, the organic cover layer contains a chlorosilane, an amine, an alcohol, a carbon acid, a siloxane or a dimethylamino silane. These materials are particularly suitable for formation of a non-stick layer. The non-stick layer is preferably applied by a molecular vapor deposition (MVD) method.
- The water-repellent or adhesion-inhibiting property of the organic cover layer may depend on the material of the cover layer, particularly the chemical properties of the surface, and/or the structure thereof. In particular, the organic cover layer may have a surface structure by means of which a water-repellant effect, the so-called lotus effect, is achieved.
- According to a preferred configuration, the at least one inorganic layer comprises a heat conductive layer. Advantageously, the heat conductive layer allows advantageously dissipating heat that develops during operation of the laser diode chip at the laser facet. Transparent conductive oxides such as ITO or ZnO are preferred materials for the heat conductive layer. Further preferred materials include GaN, AlN, diamond-like carbon (DLC), SiC or graphene. The heat conductive layer may particularly also be electrically conductive. This is why it is advantageous to not attach or apply the heat conductive layer directly to the laser facet, since otherwise there would be a short-circuit risk for the semiconductor layers of the laser diode chip.
- In the case that the heat conductive layer has an electric conductivity as low as not to pose a risk of short circuits, the heat conductive layer may also be directly applied or attached to the laser facet. In this case, heat can be dissipated from the laser diode chip in a particularly good manner.
- In a preferred configuration, the heat conductive layer is arranged between a first organic diffusion barrier layer and a second organic diffusion barrier layer. This is advantageous since the organic diffusion barrier layers are comparatively elastic and therefore capable of compensating a temperature-dependent expansion of the heat conductive layer preferably in the elastic expansion range.
- In a preferred configuration, the at least one inorganic layer comprises a dielectric protective layer, which is directly adjacent to the laser facet. Preferably, the dielectric protective layer is a layer produced by atomic layer deposition. Atomic layer deposition allows producing especially dense layers, the dense layers particularly forming a diffusion barrier for moisture. The dielectric protective layer preferably comprises one oxide, nitride or oxynitride.
- The coating may particularly comprise multiple inorganic layers. According to an advantageous configuration, the inorganic layers are at least partially arranged in a reflection-increasing or reflection-decreasing layer sequence. The reflection-increasing or reflection-decreasing layer sequence may particularly comprise alternating layers having a refractive index that alternates between higher and lower values.
- The inorganic layers of the coating, particularly the reflection-increasing or reflection-decreasing layer sequence, preferably contain dielectric materials, particularly oxides, nitrides or oxynitrides. The inorganic layers may particularly comprise at least one of the materials SiO2, Al2O3, TiO2, Ta2O5, Si3N4, ZrO2, HfO2, Nb2O5, Y2O3, Ho2O3, CeO3, Lu2O3, V2O5, HfZrO, MgO, TaC, ZnO, CuO, In2O3, Yb2O3, Sm2O3, Nd2O3, Sc2O3, B2O3, Er2O3, Dy2O3, Tm2O3, SrTiO3, BaTiO3, PbTiO3, PbZrO3, Ga2O3, HfAlO or HfTaO.
- It is possible that the reflection-increasing or reflection-decreasing layer sequence consists exclusively of inorganic layers.
- In a preferred configuration, the coating comprises a heat conductive layer arranged between a dielectric reflection-increasing or reflection-decreasing layer sequence and an organic diffusion barrier layer. In this case, the heat conductive layer is advantageously insulated from the laser facet by the dielectric reflection-increasing or reflection-decreasing layer sequence, which may therefore also comprise an electrically-conductive material.
- In a preferred configuration, the reflection-increasing or reflection-decreasing layer sequence contains both inorganic and organic layers, particularly alternating inorganic and organic layers. The reflection-increasing or reflection-decreasing layer sequence may particularly comprise alternating inorganic layers having a high refractive index and organic layers having a low refractive index, or, as an alternative, alternating inorganic layers having a low refractive index and organic layers having a high refractive index. In this configuration, the inorganic and/or organic layers advantageously have a thickness between 1 nm and 350 nm, preferably between 5 nm and 200 nm, and particularly preferably between 10 nm and 100 nm.
- The number of layers in the reflection-increasing layer sequence advantageously ranges between 2 and 50, particularly preferably between 4 and 20.
- In the following, the invention will be explained in greater detail by exemplary embodiments in conjunction to
FIGS. 1 to 8 . - Shown are in:
-
FIG. 1 a schematic illustration of a cross-section through a partial region of a laser diode chip according to a first exemplary embodiment, -
FIG. 2 a schematic illustration of a cross-section through a partial region of a laser diode chip according to a second exemplary embodiment, -
FIG. 3 a schematic illustration of a cross-section through a partial region of a laser diode chip according to a third exemplary embodiment, -
FIG. 4 a schematic illustration of a cross-section through a partial region of a laser diode chip according to a fourth exemplary embodiment, -
FIG. 5 a schematic illustration of a cross-section through a partial region of a laser diode chip according to a fifth exemplary embodiment, -
FIG. 6 a schematic illustration of a cross-section through a partial region of a laser diode chip according to a sixth exemplary embodiment, -
FIG. 7 a schematic illustration of a cross-section through a partial region of a laser diode chip according to a seventh exemplary embodiment, and -
FIG. 8 a schematic illustration of a cross-section through a partial region of a laser diode chip according to an eighth exemplary embodiment. - Equal or equivalent components are marked with the same reference numeral in the figures, respectively. The components shown as well as the proportions of the components amongst one another are not to be considered to be true to scale.
- The
laser chip diode 1 schematically shown in cross-section inFIG. 1 comprises a semiconductor layer sequence attached to asubstrate 6. - For example, the semiconductor layer sequence contains a
buffer layer 2 applied to thesubstrate 6, afirst cladding layer 3 a, afirst waveguide layer 4 a, anactive layer 5, asecond waveguide layer 4 b and asecond cladding layer 3 b. The semiconductor layer sequence may contain further layers, which are not shown for simplification. Furthermore, at least partial regions of the semiconductor layer sequence may be structured, for example as a ridge waveguide structure. Suitable waveguide structures for laser diode chips are known per se and thus not shown in detail for simplification. - The
active layer 5 of the edge-emitting semiconductor laser can be configured as pn-junction, double hetero structure, single quantum well structure or multi quantum well structure, for example. In the scope of the application, the term quantum well structure includes any structure in which charge carriers receive quantization of their energy states by confinement. In particular, the term quantum well structure does not contain information regarding the dimensionality of the quantization. Thus, it comprises, inter alia, quantum wells, quantum wires and quantum dots and any combination of these structures. - The semiconductor layer sequence of the
laser diode chip 1 is preferably based on a III-V-compound semiconductor material, particularly on an arsenide, nitride or phosphide compound semiconductor material. For example, the semiconductor layer sequence may contain InxAlyGa1-x-yAs, InxAlyGa1-x-yN or InxAlyGa1-x-yP, each with 0≦x≦1, 0≦y≦1 and x+y≦1. Here, the III-V-compound semiconductor material does not need to have a mathematically-exact composition according to one of the above formulas. It may rather comprise one or multiple dopants as well as additional components that do not substantially change the physical properties of the material. However, the above formulas do only contain the essential components of the crystal lattice for simplification, even though the components may be replaced by minor quantities of further materials. - Here, material selection is effected by the desired emission wavelength of the
laser diode chip 1. Thesubstrate 6 is selected by the preferably epitaxially-grown semiconductor sequence and may particularly comprise GaAs, sapphire, SiC, GaN or silicon. - For the electric contacting of the laser diode chip, a
first contact layer 7 is arranged on a rear side of thesubstrate 6 facing away from the semiconductor layer sequence and asecond contact layer 8 is arranged on the side of the semiconductor layer sequence facing away from thesubstrate 6. - The
laser diode chip 1 comprises alaser facet 9 provided with acoating 10. Thelaser facet 9 can particularly form one of the resonator mirrors of thelaser diode chip 1. A further laser facet, which is not shown in the detail and which is located opposite thelaser facet 9 can form a second resonator mirror of the laser diode chip and be provided with a further coating, which may have the same advantageous configurations as thecoating 10 of thelaser facet 9 to be described in the following. In this case, the further coating does not need to be identical to thecoating 10 but may have optical properties different from that of thecoating 10, particularly a different reflectivity, for example. - The
laser facet 9 provided with thecoating 10 can particularly be provided as a radiation exit surface of thelaser diode chip 1. - In the exemplary embodiment, coating 10 comprises a first reflection-increasing or reflection-decreasing layer sequence ii, which has multiple alternating first layers 13 and second layers 14. The reflection-increasing or reflection-decreasing
layer sequence 11 in the exemplary embodiment has three layer pairs composed of first layers 13 and second layers 14, that is a total number of 6 layers. Generally, the number of layers 13, 14 is between 2 and 50, preferably between 4 and 20. For example, the alternating layers 13, 14 are inorganic dielectric layers respectively, which alternate between having a high refractive index or a low refractive index. The reflection-increasing or reflection-decreasinglayer sequence 11 may have alternating first layers 13 made of Al2O3 and second layers 14 made of one of the materials TiO2, ZrO2 or Ta2O5, for example. In this configuration, the first layers each have a low refractive index and the second layers each have a high refractive index. As an alternative it is also possible for the first layers to have a high refractive index, the second layers having a low refractive index. Furthermore, the reflection-increasing or reflection-decreasinglayer sequence 11 may also have or comprise an uneven number of layers, i.e., a further layer with a low or high refractive index is contained in thelayer sequence 11 in addition to the layer pairs. - In the exemplary embodiment, coating 10 further comprises a second reflection-increasing or reflection-decreasing
layer sequence 12, which is composed of alternating third layers 15 and fourth layers 16, which just like in the first reflection-increasing or reflection-decreasinglayer sequence 11, advantageously have alternating low refractive indices and high refractive indices. Use of two successive reflection-increasing or reflection-decreasinglayer sequences layer sequence 11 may be selected for obtaining a most great difference in their refractive indices, for example. - However, as an alternative, it is also possible that coating 10 only contains one reflection-increasing or reflection-decreasing
layer sequence 11. It is also possible that a reflection-increasing or reflection-decreasing single layer is used instead of the first and/or second reflection-increasing or reflection-decreasinglayer sequence - It is not mandatory for the first reflection-increasing or reflection-decreasing
layer sequence 11 or the second reflection-increasing or reflection-decreasinglayer sequence 12 to consist exclusively of inorganic layers. As an alternative, it is rather also possible that at least one of the reflection-increasing or reflection-decreasinglayer sequences layer sequence 11 comprises organic first layers 13 and inorganic second layers 14, for example. In this configuration, the organic layers 13 integrated in the reflection-increasing or reflection-decreasinglayer sequence 11 provide the advantage that they are comparatively elastic when compared to inorganic dielectric layers. This is particularly advantageous if temperature-dependent stress occurs during operation of thelaser diode 1. - Furthermore, coating 10 advantageously comprises a
cover layer 20, which is a hydrophobic organic layer in the exemplary embodiment ofFIG. 1 . The hydrophobicorganic cover layer 20 has a contact angle for water greater than 90°. The hydrophobicorganic cover layer 20 particularly serves for protection of thelaser facet 9 against moisture. The hydrophobicorganic cover layer 20 may contain carbon nanotubes, organic fluorine or sulfur compounds, which in particular contain thiol or silane groups. The hydrophobicorganic cover layer 20 preferably is a monolayer, particularly a self-assembled monolayer. -
FIG. 2 illustrates a second exemplary embodiment of thelaser diode chip 1. This embodiment is different from the first exemplary embodiment in that the an organic layer follows the second reflection-increasing or reflection-decreasinglayer sequence 12 in the growth direction of thelayer 10, which particularly is adiffusion barrier layer 21 for reducing the diffusion of oxygen or moisture. As a result, thelaser facet 9 is even better protected against oxidation. - The organic
diffusion barrier layer 21 preferably contains an alkane, alkene, alkyne, a cycloalkane, cycloalkene, a polyamide or an aluminum alkoxide. Apart from that, the second exemplary embodiment corresponds to the above described first exemplary embodiment. - In the third exemplary embodiment shown in
FIG. 3 , acoating 10 is applied to thelaser facet 9, which comprises, starting from thelaser facet 9, a dielectricprotective layer 18, a reflection-increasing or reflection-decreasing layer sequence ii and an organicdiffusion barrier layer 21. Advantageously, the dielectricprotective layer 18 is directly adjacent to thelaser facet 9 and preferably is a layer produced by atomic layer deposition. Atomic layer deposition allows depositing especially dense dielectric layers, the layers providing an especially good protection against the penetration of moisture. The dielectric protective layer preferably comprises an oxide, nitride or oxynitride. The dielectricprotective layer 18 may comprise SiO2, Si(OxN1-x)2, AlSO3 or Al2(OxN1-x)3 or combinations thereof, for example. - The reflection-increasing or reflection-decreasing
layer sequence 11 following the dielectricprotective layer 18 corresponds to the first exemplary embodiment regarding the advantageous configurations thereof. - As in the second exemplary embodiment, the
organic layer 21 may serve particularly as a diffusion barrier. In this exemplary embodiment, it simultaneously forms the cover layer of thecoating 10. The organicdiffusion barrier layer 21 provides the advantage that it is comparatively elastic and thus particularly tear-resistant when compared to inorganic layers. This reduces the risk that cracks occur in thediffusion barrier layer 21 during operation of thelaser diode chip 1, for example caused by temperature-dependent stress. - In the fourth exemplary embodiment shown in
FIG. 4 , acoating 10 is applied to thelaser facet 9, the coating comprising, starting from thelaser facet 9, a reflection-increasing or reflection-decreasinglayer sequence 11, a heat-conductive barrier layer 21 and a hydrophobicorganic layer 20 as a cover layer. - This exemplary embodiment is different from the above described second exemplary embodiment in that the heat-
conductive layer 17 is advantageously arranged between the reflection-increasing or reflection-decreasing layer sequence ii and the organicdiffusion barrier layer 21, making it possible to dissipate at least part of the heat developing during operation of thelaser diode chip 1 through thelayer 17. The heat-conductive layer 17 may particularly also comprise an electrically-conductive material, since it is insulated from the semiconductor layer sequence of thelaser diode 1 by the dielectric reflection-increasinglayer sequence 11. The heat-conductive layer 17 may contain ITO, ZnO, GaN, AlN, diamond-like carbon (DLC), SiC or graphene, for example. - The fifth exemplary embodiment shown in
FIG. 5 is different from the fourth exemplary embodiment in that an organicnon-stick layer 22 is contained in thecoating 10 as cover layer in place of the hydrophobic organic cover layer. Advantageously, thenon-stick layer 22 reduces adsorption of particles at the laser facet. Otherwise, such particle adsorption could occur as a consequence of the electrostatic interactions during operation of thelaser diode chip 1. - Preferably, the
non-stick layer 22 is applied by an MVD method or an MLD method and preferably contains a chlorosilane, an amine, an alcohol, a carbon acid, a siloxane or a dimethylamino silane. - In the sixth exemplary embodiment shown in
FIG. 6 , thecoating 10 comprises, starting from thelaser facet 9, a dielectricprotective layer 18, a heatconductive layer 17, a reflection-increasing or reflection-decreasinglayer sequence 11 and a hydrophobicorganic layer 20 as cover layer. The functions and advantageous configurations of the individual layers correspond to the exemplary embodiments described above and will thus not be explained in further detail. - In the seventh exemplary embodiment shown in
FIG. 7 , thecoating 10 comprises, starting from thelaser facet 9, a reflection-increasing or reflection-decreasinglayer sequence 11, a first organic diffusion barrier layer 21 a, a heat-conductive layer 17, a second organic diffusion barrier layer 21 b and a hydrophobicorganic cover layer 20. In this exemplary embodiment, the heat-conductive layer 17 is arranged between two organic diffusion barrier layers 21 a, 21 b, the latter being elastic and thus being capable of compensating a temperature-dependent expansion of the heat-conductive layer 17 preferably in the elastic expansion range. The functions and advantageous configurations of the individual layers correspond to the exemplary embodiments described above and will thus not be explained in further detail. - In the other exemplary embodiment shown in
FIG. 8 , the coating comprises, starting from thelaser facet 9, a dielectricprotective layer 18, a reflection-increasing or reflection-decreasinglayer sequence 11, a heat-conductive layer 17, an organicdiffusion barrier layer 21 and a hydrophobicorganic layer 20 as a cover layer. In place of the hydrophobicorganic cover layer 20, an organic non-stick layer could serve as cover layer just as well. The functionality of the individual layers corresponds to the exemplary embodiments described above and will thus not be explained in further detail. - The invention is not limited by the description with reference to the exemplary embodiments. The invention rather comprises each and every new feature as well as any combination of features, which particularly includes any combination in the patent claims, even though the feature or the combination is not explicitly stated in the patent claims or exemplary embodiments.
Claims (22)
1-17. (canceled)
18. A laser diode chip having a laser facet, which comprises a coating, wherein the coating comprises an inorganic layer and an organic layer.
19. The laser diode chip according to claim 18 , wherein the organic layer comprises a diffusion barrier layer.
20. The laser diode chip according to claim 19 , wherein the inorganic layer comprises a heat-conductive layer, wherein the coating comprises a plurality of inorganic layers, which are at least partially arranged in a reflection-increasing or reflection-decreasing layer sequence, and wherein the heat-conductive layer is arranged between the reflection-increasing or reflection-decreasing layer sequence and the diffusion barrier layer.
21. The laser diode chip according to claim 18 , wherein the organic layer comprises an alkane, alkene, alkyne, a cycloalkane, cycloalkene, a polyamide or an aluminum alkoxide.
22. The laser diode chip according to claim 18 , wherein the organic layer comprises an organic cover layer.
23. The laser diode chip according to claim 22 , wherein the organic cover layer is a hydrophobic layer or a non-stick layer.
24. The laser diode chip according to claim 23 , wherein the organic cover layer has a contact angle for water greater than 90°.
25. The laser diode chip according to claim 22 , wherein the organic cover layer contains carbon nanotubes, an organic fluorine or sulfur compound, a thiol, a silane, a chlorosilane, an amine, an alcohol, a carbon acid, a siloxane or a dimethylamino silane.
26. The laser diode chip according to claim 18 , wherein the inorganic layer comprises a heat-conductive layer.
27. The laser diode chip according to claim 26 , wherein the heat-conductive layer is arranged between a first organic diffusion barrier layer and a second organic diffusion barrier layer.
28. The laser diode chip according to claim 26 , wherein the heat-conductive layer comprises a transparent conductive oxide, ITO, ZnO, GaN, AlN, diamond-like carbon (DLC), SiC or graphene.
29. The laser diode chip according to claim 18 , wherein the inorganic layer comprises a dielectric protective layer that is in direct contact with the laser facet.
30. The laser diode chip according to claim 29 , wherein the dielectric protective layer is an ALD-layer.
31. The laser diode chip according to claim 18 , wherein the inorganic layer comprises a reflection-increasing or a reflection-decreasing layer.
32. The laser diode chip according to claim 18 , wherein the coating comprises a plurality of inorganic layers, which are at least partially arranged in a reflection-increasing or reflection-decreasing layer sequence.
33. The laser diode chip according to claim 32 , wherein the reflection-increasing or reflection-decreasing layer sequence contains both inorganic layers and organic layers.
34. The laser diode chip according to claim 18 , wherein the inorganic layer comprises at least one material selected from the group consisting of SiO2, Al2O3, TiO2, Ta2O5, Si3N4, ZrO2, HfO2, Nb2O5, Y2O3, Ho2O3, CeO3, Lu2O3, V2O5, HfZrO, MgO, TaC, ZnO, CuO, In2O3, Yb2O3, Sm2O3, Nd2O3, Sc2O3; B2O3, Er2O3, Dy2O3, Tm2O3, SrTiO3, BaTiO3, PbTiO3, PbZrO3, Ga2O3, HfAlO, and HfTaO.
35. A laser diode chip having a laser facet, which comprises a coating, wherein the coating comprises a plurality of inorganic layers and an organic layer;
wherein the inorganic layers comprise a heat-conductive layer;
wherein the heat-conductive layer comprises a transparent conductive oxide, ITO, ZnO, GaN, AlN, diamond-like carbon (DLC), SiC or graphene;
wherein the inorganic layers comprise a reflection-increasing or reflection-decreasing layer sequence;
wherein the number of layers in the reflection-increasing or reflection-decreasing layer sequence ranges between 2 and 50; and
wherein the heat-conductive layer is arranged between the reflection-increasing or reflection-decreasing layer sequence and the organic layer.
36. The laser diode chip according to claim 35 , wherein the organic layer comprises an organic cover layer.
37. The laser diode chip according to claim 35 , wherein the organic layer comprises a diffusion barrier layer.
38. The laser diode chip according to claim 35 , wherein the number of layers in the reflection-increasing or reflection-decreasing layer sequence ranges between 4 and 20.
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DE102014102360A1 (en) | 2015-08-27 |
WO2015124531A3 (en) | 2015-10-15 |
JP2017506834A (en) | 2017-03-09 |
DE112015000938A5 (en) | 2016-12-22 |
JP6321197B2 (en) | 2018-05-09 |
DE112015000938B4 (en) | 2020-01-09 |
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