DE102021113297A1 - PROCESS FOR MANUFACTURING A SEMICONDUCTOR LASER DIODE AND SEMICONDUCTOR LASER DIODE - Google Patents

Abstract

A method for manufacturing a semiconductor laser diode is specified with the following steps:
- Providing a growth substrate (1) with a growth area (2),
- introducing at least one structure (10) into at least one facet region (6) of the growth area (2),
- Epitaxial growth of an epitaxial semiconductor layer sequence (3) with an active zone (12), which generates electromagnetic radiation during operation, on the growth area (2), wherein
- the structure (10) is overgrown by semiconductor material of the epitaxial semiconductor layer sequence (3), so that the active zone (12) has a band gap in a non-absorbing mirror region (24) that is larger than in the remaining region of the active zone (12).
A semiconductor laser diode is also provided.

Description

A method for manufacturing a semiconductor laser diode and a semiconductor laser diode are specified.

A semiconductor laser diode is to be specified in which, in particular, the risk of damage to the facet during operation is reduced. Furthermore, a simplified method for producing such a semiconductor laser diode is to be specified.

These objects are solved by a method with the steps of patent claim 1 and by a semiconductor laser diode with the features of patent claim 5.

Advantageous embodiments and developments of the method for producing the semiconductor laser diode and the semiconductor laser diode are specified in the dependent claims.

According to one embodiment of the method, a growth substrate having a growth area is provided. In particular, the growth area is a main area of the growth substrate. The growth substrate preferably has a lattice constant which is the same as or similar to a lattice constant of the epitaxial semiconductor layer sequence to be grown.

According to a further embodiment of the method, at least one structure is introduced into a facet area of the growth area. For example, the structure can be introduced into the facet region of the growth area by etching, for example by dry etching.

In a plan view above or on the facet region of the growth area, in the finished semiconductor laser diode, in particular one facet is arranged.

Here and in the following, for reasons of clarity, only one structure and one facet area are mentioned. Advantageously, however, the growth area of the growth substrate has, in particular, a multiplicity of facet regions into which one or more structures are introduced. In particular, the growth substrate can be provided as a wafer with a growth area that has a multiplicity of facet regions. In this case, a multiplicity of semiconductor laser diodes can advantageously be produced simultaneously at the wafer level, which are finally isolated to form individual semiconductor laser diodes.

According to a further embodiment of the method, an epitaxial semiconductor layer sequence with an active zone, which generates electromagnetic radiation during operation, is epitaxially grown on the growth area.

According to a further embodiment of the method, the structure of semiconductor material of the epitaxial semiconductor layer sequence is overgrown during the epitaxial growth of the epitaxial semiconductor layer sequence, so that the active zone has a band gap in a non-absorbing mirror region that is larger than in the remaining region of the active zone.

The non-absorbing mirror area is at least partially congruent with the facet area, for example in a plan view. In particular, the non-absorbing mirror area is surrounded by a resonator of the finished semiconductor laser diode and is adjacent to a facet of the semiconductor laser diode. For example, starting from a facet of the finished semiconductor laser diode, the non-absorbing mirror area has a length in a main extension direction of the resonator of between 10 micrometers and 100 micrometers inclusive. In particular, the non-absorbing mirror area is transparent to electromagnetic radiation of the active zone.

In the present case, the term “transparent” means in particular that the element designated in this way transmits at least 80%, preferably at least 85% and particularly preferably 95% of the electromagnetic radiation.

In particular, the structure in the facet region of the growth area results in the semiconductor material of the active zone having an increased band gap in the non-absorbing mirror region. Here, the structure in the facet region of the growth surface changes the band gap, for example, in an area within a distance between 5 microns and 40 microns inclusive, or between 5 microns and 30 microns inclusive, or between 5 microns and 10 microns inclusive.

For example, the active zone has at least one quantum structure for generating the electromagnetic radiation during operation of the semiconductor laser diode. The term quantum structure does not contain any information about the dimensionality of the quantization. It thus includes quantum wells, quantum wires and quantum dots and any combination of these quantum structures. For example, at least the quantum structure in the non-absorbing mirror area has a band gap that is larger than in the remaining area of the quan ten structure. The band gap of the entire active zone is also preferably larger in the non-absorbing mirror area than in the remaining area of the active zone.

The band gap of the entire epitaxial semiconductor layer sequence is particularly preferably larger in the non-absorbing mirror region than in the remaining region of the epitaxial semiconductor layer sequence. In particular, waveguide layers between which the active zone is arranged can also have a band gap in the non-absorbing mirror area that is larger than in the remaining area. In this way, the epitaxial semiconductor layer sequence can be embodied on or above the facet region adjoining a facet of the future semiconductor laser diode so that it is transparent to the electromagnetic radiation generated in the active zone.

• - Bereitstellen des Wachstumssubstrats mit der Aufwachsfläche,
• - Einbringen der zumindest einen Struktur in den Facettenbereich der Aufwachsfläche,
• - epitaktisches Aufwachsen der epitaktischen Halbleiterschichtenfolge mit der aktiven Zone, die im Betrieb elektromagnetische Strahlung erzeugt, auf der Aufwachsfläche, wobei
• - die Struktur von dem Halbleitermaterial der epitaktischen Halbleiterschichtenfolge überwachsen wird, so dass die aktive Zone in einem nichtabsorbierenden Spiegelbereich eine Bandlücke aufweist, die größer ist als in dem restlichen Bereich der aktiven Zone.

According to a particularly preferred embodiment, the method has the following steps:

• - Provision of the growth substrate with the growth area,
• - introducing the at least one structure into the facet area of the growth area,
• - Epitaxial growth of the epitaxial semiconductor layer sequence with the active zone, which generates electromagnetic radiation during operation, on the growth area, wherein
• - the structure is overgrown by the semiconductor material of the epitaxial semiconductor layer sequence, so that the active zone has a band gap in a non-absorbing mirror region that is larger than in the remaining region of the active zone.

The above steps are preferably carried out in the order given.

According to a further embodiment of the method, the trenches are removed again in a further step.

According to a further embodiment of the method, the epitaxial semiconductor layer sequence is based on a semiconductor material with an indium content and the indium content is lower in the non-absorbing mirror area, so that the band gap of the semiconductor material in the non-absorbing mirror area is larger than in the remaining area of the active zone. In particular, the band gap of the semiconductor material is increased in a region of the epitaxial semiconductor layer sequence, which is comprised by a resonator in the finished semiconductor laser diode and adjoins a facet.

Furthermore, it is also possible that due to the structure in the facet region of the growth area, in addition or as an alternative to the indium content of the semiconductor material, a thickness of the active zone or a quantum structure of the active zone, an aluminum content of the semiconductor material, an atomic concentration of the semiconductor material and/or a strain in the semiconductor material are changed so that the band gap is increased as desired.

For example, the thickness of the active region or the quantum structure of the active region varies between 1% and 5% inclusive per one micron of distance from the structure.

For example, the atomic concentration of the semiconductor material varies between 5% inclusive and 15% inclusive per 5 micrometers distance from the structure.

In accordance with a further embodiment, the epitaxial semiconductor layer sequence and in particular the active zone are based on a nitride compound semiconductor material.

It is also possible for the epitaxial semiconductor layer sequence and in particular the active zone to consist of a nitride compound semiconductor material. Nitride compound semiconductor materials are compound semiconductor materials that contain nitrogen, such as the materials from the system In _x Al _y Ga _1-xy N with 0 ≤ x ≤ 1, 0 ≤ y ≤ 1 and x+y < 1. An active region comprising based on a nitride compound semiconductor material or consists of a nitride compound semiconductor material is particularly suitable for generating electromagnetic radiation from the ultraviolet to green spectral range. In particular, gallium nitride, sapphire or silicon carbide are suitable as a growth substrate for an epitaxial semiconductor layer sequence based on a nitride compound semiconductor material.

Furthermore, it is also possible that the epitaxial semiconductor layer sequence and in particular the active zone are based on a phosphide compound semiconductor material or consist of a phosphide compound semiconductor material. Phosphide compound semiconductor materials are compound semiconductor materials that contain phosphorus, such as the materials from the system In _x Al _y Ga _1-xy P with 0≦x≦1, 0≦y≦1 and x+y≦1 based on a phosphide compound semiconductor material or consists of a phosphide compound semiconductor material is particularly suitable for generating electromagnetic radiation from the green to red spectral range. In particular, gallium phosphide is used as a growth substrate for an epitaxial semiconductor layer sequence that is based on a phosphide compound semiconductor material.

In addition, the epitaxial semiconductor layer sequence and in particular the active zone can be based on an arsenide compound semiconductor material or consist of an arsenide compound semiconductor material. Arsenide compound semiconductor materials are compound semiconductor materials that contain arsenic, such as the materials from the system In _x Al _y Ga _1-xy As with 0 ≤ x ≤ 1, 0 ≤ y ≤ 1 and x+y ≤ 1. An active region comprising an arsenide compound semiconductor material is based or consists of an arsenide compound semiconductor material, is particularly suitable for generating electromagnetic radiation from the red to infrared spectral range. In particular, gallium arsenide is suitable as a growth substrate for an epitaxial semiconductor layer sequence based on an arsenide compound semiconductor material.

Finally, the epitaxial semiconductor layer sequence and in particular the active zone can be based on an antimonide compound semiconductor material or consist of an antimonide compound semiconductor material. Antimonide compound semiconductor materials are compound semiconductor materials containing antimony, such as the materials from the system In _x Al _y Ga _1-xy Sb with 0≦x≦1, 0≦y≦1 and x+y≦1 an antimonide compound semiconductor material is based or consists of an antimonide compound semiconductor material is particularly suitable for generating electromagnetic radiation from the infrared spectral range. In particular, gallium antimonide is suitable as a growth substrate for an epitaxial semiconductor layer sequence that is based on an antimonide compound semiconductor material.

The method is based, among other things, on the idea of reducing an indium content of the semiconductor material of the epitaxial semiconductor layers in a non-absorbing mirror region, which usually borders the facet and is surrounded by a resonator in the finished semiconductor laser diode, compared to the remaining semiconductor material, so that the Band gap of the semiconductor material is increased. Thus, the resonator of the finished semiconductor laser diode is transparent in the non-absorbing mirror area for the electromagnetic radiation generated in the active zone. The risk of damage to the facet, for example due to COD (“catastrophic optical damage”) and/or COMD (“catastrophic optical mirror damage”), is significantly reduced. As explained above, it is also possible that other parameters of the epitaxial semiconductor layer sequence, such as the layer thickness, the stress, the atomic concentration and/or aluminum content, are changed in places by the structure and the band gap of the semiconductor material is increased.

According to a further embodiment of the method, the structure has a trench-shaped recess. In particular, the structure has a trench-shaped recess that is arranged laterally next to a resonator area of the growth area. A resonator in particular is arranged in the finished semiconductor laser diode in a top view on or above the resonator of the growth area.

The trench-shaped recess is at a distance from the resonator region, for example, of between 1 micrometer and 100 micrometers inclusive. For example, the trench-shaped recess extends over a length of between 5 micrometers and 100 micrometers inclusive along a main direction of extension of the resonator region. For example, the trench-shaped recess has a depth of between 1 micrometer and 10 micrometers inclusive.

According to a further embodiment of the method, a facet of the semiconductor laser diode is produced by breaking through the facet areas or by etching through the facet areas. In particular, in a method at the wafer level, the multiplicity of semiconductor laser diodes can be completely or partially isolated by breaking or by etching. In other words, it is possible for the facet to form a side surface of the semiconductor laser diode. In the case of an etched facet in particular, however, it is also possible for the facet to be arranged set back in relation to the side surface.

Features and configurations are often described herein using a facet for the sake of clarity. However, such features and configurations may be formed on some or all of the facets produced in the process, for example at the wafer level.

The method described here is intended and suitable for producing a semiconductor laser diode. All features that are described in connection with the method can therefore also be implemented in the semiconductor laser diode and vice versa.

In accordance with one embodiment, the semiconductor laser diode comprises a growth substrate with a growth area into which a structure is introduced in a facet region.

In accordance with a further embodiment, the semiconductor laser diode has an epitaxial semiconductor layer sequence which is formed on the growth area is grown epitaxially and includes an active zone that generates electromagnetic radiation during operation of the semiconductor laser diode.

According to a further embodiment of the semiconductor laser diode, the structure of semiconductor material overgrows the epitaxial semiconductor layer sequence.

According to a further embodiment of the semiconductor laser diode, the active zone has a band gap in a non-absorbing mirror area that is larger than in the remaining area of the active zone.

According to a preferred embodiment, the semiconductor laser diode comprises a growth substrate with a growth area, in which a structure is introduced in a facet area, and an epitaxial semiconductor layer sequence, which is epitaxially grown on the growth area and includes an active zone that generates electromagnetic radiation during operation. In particular, the structure in this embodiment of the semiconductor laser diode is overgrown by semiconductor material of the epitaxial semiconductor layer sequence and the active zone has a band gap in a non-absorbing mirror area that is larger than in the remaining area of the active zone.

The semiconductor laser diode preferably has two non-absorbing mirror regions which lie opposite one another and each adjoin a facet of the semiconductor laser diode.

Since at least the active zone in the non-absorbing mirror area has a band gap that is larger than in the remaining area of the active zone, electromagnetic radiation that is generated and/or guided in the remaining area of the active zone can pass through the areas with the increased band gap very much can be transmitted well, as they are transparent to electromagnetic radiation. In this way, absorption of the electromagnetic radiation at the facet is reduced, so that the risk of damage to the facet, for example by COD and/or COMD, is significantly reduced.

According to a further embodiment, the semiconductor laser diode includes two facets that form a resonator. In particular, the facets are arranged opposite one another. The facets are preferably designed to be at least partially reflective for the electromagnetic radiation that is generated in the active zone. In particular, a standing wave of the electromagnetic radiation that is generated in the active zone forms in the resonator between the two facets. The resonator is arranged on or above a resonator region of the growth area of the growth substrate, in particular in a plan view.

For example, one of the facets is designed to be highly reflective for the electromagnetic radiation of the active zone, while another facet is partially transparent for the electromagnetic radiation of the active zone. During operation of the semiconductor laser diode, electromagnetic radiation is coupled out of the partially transparent facet through the partially transparent facet.

According to one embodiment, the resonator includes an amplifier section. The amplifier area is in particular the area of the resonator in which a population inversion is generated in the semiconductor material of the active zone during operation. Due to the population inversion, the electromagnetic radiation in the active zone is generated by stimulated emission, which leads to the formation of electromagnetic laser radiation. In particular, the active zone within the amplifier region has a bandgap that is not increased as in the non-absorbing mirror region. The amplifier area is preferably arranged between two non-absorbing mirror areas. For example, the amplifier area and the two non-absorbing mirror areas are encompassed by the resonator or are congruent with the resonator.

According to a further embodiment of the semiconductor laser diode, an electrical contact is arranged at a distance from the facet on a main area of the epitaxial semiconductor layer sequence. For example, the electrical contact is arranged centrally between the two facets on the main surface of the epitaxial semiconductor layer sequence. In particular, the electrical contact is set up and provided for impressing electrical current into the epitaxial semiconductor layer sequence and in particular into the active zone during operation. For example, the electrical contact is arranged in a top view so that it overlaps or is congruent with the amplifier area.

Due to the generation of the electromagnetic laser radiation by stimulated emission, the electromagnetic laser radiation, in contrast to electromagnetic radiation that is generated by spontaneous emission, usually has a very long coherence length, a very narrow emission spectrum and/or a high degree of polarization.

The electromagnetic laser radiation generated in the amplifier area is at least partially reflected at the facets of the resonator, so that a standing wave of the electromagnetic laser radiation forms in the resonator. Outside the amplifier area in the non-absorbing mirror areas, the resonator only has a wave-guiding effect for the electromagnetic laser radiation.

In addition to the amplifier area, in which a population inversion is generated in the active zone, the resonator also has the non-absorbing mirror areas in which a standing wave of the electromagnetic laser radiation forms due to the reflection at the facets, but not due to the population inversion is reinforced. The non-absorbing mirror areas are only designed to be wave-guiding for the electromagnetic laser radiation.

The amplifier area is preferably completely surrounded by the resonator, which is defined by the facets.

According to a further embodiment, a length of the amplifier region is shorter than an edge of the semiconductor laser diode. In this way, a semiconductor laser diode with the properties of a short resonator can advantageously be achieved, which, however, at the same time has a large chip area, so that handling and manufacture are simplified.

According to a further embodiment of the semiconductor laser diode, the length of the amplifier region is at most 300 micrometers, preferably at most 100 micrometers.

According to a further embodiment of the semiconductor laser diode, the edge length of the semiconductor laser diode is at least 300 micrometers, preferably at least 600 micrometers.

In accordance with a further embodiment of the semiconductor laser diode, the structure has a trench-shaped recess in the growth area, which has an edge that is directly adjacent to the facet. In this embodiment, the facet may be formed on a side face of the semiconductor laser diode. If the facet is formed on a side face of the semiconductor laser diode, the facet is formed by breaking in particular. Furthermore, it is also possible for the facet to be set back from the side surface. A facet that is set back from the side surface of the semiconductor laser diode is produced, in particular, by etching.

In accordance with a further embodiment of the semiconductor laser diode, the structure has a trench-shaped recess in the growth area, the trench-shaped recess having an edge which is arranged set back from a facet in a plan view. In this embodiment of the semiconductor laser diode, breaking to form the facet is facilitated.

According to a further embodiment of the semiconductor laser diode, the structure has a trench-shaped recess in the growth area, which has a triangular base area in a plan view of the growth area. In other words, the width of the trench-shaped recess varies here. In particular, the width decreases starting from the facet. This leads to a variation in the indium content or one of the other parameters already listed above in the semiconductor material of the epitaxial semiconductor layer sequence in the non-absorbing mirror region with the distance from the facet. In particular, the indium content increases with the distance from the facet, so that the band gap of the semiconductor material decreases with the distance from the facet.

According to a further embodiment, the semiconductor laser diode comprises a ridge waveguide, the structure being arranged to the side of the ridge waveguide. For example, the ridge waveguide is formed by a ridge-shaped projection that is produced, for example, by etching the epitaxial semiconductor layer sequence. For example, an electrical contact is arranged on the surface of the ridge waveguide, which is provided and set up to impress current into the active zone during operation. In particular, the ridge waveguide is encompassed by the resonator or forms part of the resonator.

In accordance with a further embodiment of the semiconductor laser diode, the structure has a trench-shaped recess, with a main extension direction of the trench-shaped recess being arranged obliquely to a side surface of the semiconductor laser diode in a plan view.

According to a further embodiment of the semiconductor laser diode, the structure has a trench-shaped recess, the width of which varies along the main extension direction in a plan view of the growth area.

It is possible for the structure to have a number of structural elements, for example a number of trench-shaped recesses. The structural elements of a structure can be designed in the same way or differently. If the structure comprises a plurality of structural elements, these are preferably arranged symmetrically with respect to an axis of symmetry of the resonator.

According to a further embodiment of the semiconductor laser diode, the structure has a trench-shaped recess whose spacing increases a resonator, which is formed by facets, varies along a main extension direction of the resonator. In particular, the trench-shaped recess in the facet area is at a smaller distance from the resonator than in a central area of the growth area. If the distance between the trench-shaped recess and the resonator is smaller, then the indium content is reduced and the band gap of the semiconductor material is thus increased. Furthermore, one of the other above-mentioned parameters of the epitaxial semiconductor layer sequence, such as thickness, aluminum content, atomic concentration and/or strain, can also be varied and lead to or at least contribute to an increase in the band gap.

• Die schematischen Schnittdarstellungen der 1, 3 und 4 zeigen Stadien eines Verfahrens gemäß einem Ausführungsbeispiel.
• 2 zeigt eine schematische Draufsicht auf eine Aufwachsfläche gemäß einem Ausführungsbeispiel.
• 5 zeigt eine schematische Draufsicht auf eine Halbleiterlaserdiode gemäß einem Ausführungsbeispiel.
• 6 zeigt einen Ausschnitt einer schematischen Schnittdarstellung der Halbleiterlaserdiode gemäß dem Ausführungsbeispiel der 5.
• 7 zeigt exemplarisch die Wellenlänge einer elektromagnetischen Strahlung einer aktiven Zone in Abhängigkeit vom Abstand von einer grabenförmigen Ausnehmung.
• Die 8 bis 22 zeigen schematische Draufsichten auf Halbleiterlaserdioden gemäß verschiedener Ausführungsbeispiele.

Further advantageous embodiments and developments of the method and of the semiconductor laser diode result from the exemplary embodiments described below in connection with the figures.

• The schematic sectional views of the 1 , 3 and 4 show stages of a method according to an embodiment.
• 2 shows a schematic plan view of a growth area according to an embodiment.
• 5 shows a schematic plan view of a semiconductor laser diode according to an embodiment.
• 6 shows a detail of a schematic sectional view of the semiconductor laser diode according to the embodiment of FIG 5 .
• 7 shows an example of the wavelength of an electromagnetic radiation of an active zone as a function of the distance from a trench-shaped recess.
• the 8th until 22 show schematic plan views of semiconductor laser diodes according to various embodiments.

Elements that are the same, of the same type or have the same effect are provided with the same reference symbols in the figures. The figures and the relative sizes of the elements shown in the figures are not to be regarded as being to scale. Rather, individual elements, in particular layer thicknesses, can be shown in an exaggerated size for better representation and/or for better understanding.

In the method according to the embodiment of 1 until 4 a growth substrate 1 is provided in a first step ( 1 ). The growth substrate 1 has a growth area 2 on which an epitaxial semiconductor layer sequence 3 is to be epitaxially deposited. In the present case, the growth area 2 forms a main area of the growth substrate 1 . In the present case, the growth substrate 1 is in the form of a wafer. In the method according to the embodiment of 1 until 4 it is therefore a process that is carried out at the wafer level and in which a multiplicity of semiconductor laser diodes 4 is produced.

The schematic plan view of the growth area 2 of 2 shows a large number of separating lines 5 along which the finished semiconductor laser diodes 4 are separated at a later point in time. Furthermore, the growth area 2 comprises a multiplicity of facet regions 6, on which a facet 17 is arranged in the respective subsequent semiconductor laser diode 4. In addition, the growth area 2 has a multiplicity of resonator regions 8 . A resonator 9 is arranged on a resonator region 8 in a finished semiconductor laser diode 4 .

A large number of structures 10 are introduced into the growth area 2 ( 3 ). In the present case, the structures 10 are trench-shaped recesses 11 which extend from the growth area 2 into the growth substrate 1 . Furthermore, the trench-like recesses 11 are arranged in the facet areas 6 of the growth area 2 .

In a next step, an epitaxial semiconductor layer sequence 3 is epitaxially deposited on the growth area 2 (see FIG 4 ). The epitaxial semiconductor layer sequence 3 is based on a nitride compound semiconductor material, for example. The epitaxial semiconductor layer sequence 3 comprises an active zone 12 which, during operation, generates electromagnetic radiation from the ultraviolet to green spectral range.

A semiconductor material of the epitaxial semiconductor layer sequence 3 grows over the trench-shaped recesses 11 during epitaxial growth, so that the active zone 12 in the area of the structure 10 has a band gap that is larger than in the remaining area of the active zone 12. In particular, the band gap of the active zone 12 on or above the facet areas 6 greater than in the rest of the active zone 12.

In a last step, the semiconductor laser diodes 4 produced in the wafer assembly are separated from one another, so that a large number of semiconductor laser diodes 4 are produced (not shown).

The semiconductor laser diode 4 according to the embodiment of FIG 5 until 7 can example wise be generated with a method as is based on the 1 until 4 was described.

The semiconductor laser diode 4 according to the embodiment of FIG 5 until 7 has a growth substrate 1 with a growth area 2 . In the present case, the growth area 2 comprises two facet regions 6 which lie opposite one another. Each facet area 6 also has a structure 10 which is introduced into the growth area 2 . In the present case, the structure 10 comprises two structural elements 13 which are each formed as trench-shaped recesses 11 in the growth area 2 ( 5 ).

The semiconductor laser diode 4 also includes an epitaxial semiconductor layer sequence 3, which has grown epitaxially on the growth area 2 and includes an active zone 12, which generates electromagnetic radiation during operation of the semiconductor laser diode 4 ( 6 ). In the present case, the epitaxial semiconductor layer sequence 3 is formed from a nitride compound semiconductor material.

Facets 17 are arranged on side surfaces 16 of the semiconductor laser diode 4 . The facets 17 are opposite one another and form a resonator 18 . The resonator 18 is arranged on a resonator area 8 of the growth area 2 . A standing wave of electromagnetic laser radiation forms in the resonator 18 during operation of the semiconductor laser diode.

The semiconductor laser diode 4 also includes a ridge waveguide 14 on which an electrical contact 15 is arranged. In this case, the ridge waveguide is encompassed by the resonator. The ridge waveguide 14 is formed, for example, as a ridge-shaped projection in the epitaxial semiconductor layer sequence 3 and is set up to guide electromagnetic laser radiation within a resonator 18 .

The electrical contact 15 is set up and provided to energize the epitaxial semiconductor layer sequence 3 during operation and in particular to pump the active zone 12 electrically, so that a population inversion for generating electromagnetic laser radiation in the active zone 12 is achieved.

In the present case, the electrical contact 15 is arranged on or above an amplifier region 19 which is encompassed by the resonator 18 . In the amplifier region 19, a population inversion is formed within the active zone 12 when the semiconductor laser diode 4 is in operation. Furthermore, the resonator 18 comprises non-absorbing mirror regions 24 which only have a wave-guiding character.

Starting from the side faces 16 of the semiconductor laser diode 4, the trench-shaped recesses 11 in the growth area 2 extend laterally along the resonator 18 to the amplifier region 19. In other words, the trench-shaped recesses 11 extend to the amplifier region 19. The trench-shaped recess 11 is directly adjacent to the facet 17 .

7 shows an example of a wavelength λ of the electromagnetic radiation generated in the active zone 12 in nanometers as a function of the distance y to an edge 21 of the trench-shaped recess 11. 7 shows in particular that the wavelength λ of the electromagnetic radiation generated in the active zone increases with the distance y from the edge 21 of the trench-shaped recess 11. Consequently, a band gap of the semiconductor material decreases accordingly and the indium content of the semiconductor material of the epitaxial semiconductor layer sequence 3 increases.

In particular, the active zone 12 in the area of the trench-shaped recess 11 has a band gap that is larger than in the remaining area of the active zone 12. The reason for this is that an indium content of the semiconductor material of the epitaxial semiconductor layer sequence 3 is at a distance x from the edge 21 of the trench-shaped recess 11 increases. Furthermore, it is also possible for another parameter of the epitaxial semiconductor layer sequence 3 to vary due to the structure 10, as already disclosed in the general part of the description.

For the sake of simplicity in the 8th until 16 only a portion of the respective semiconductor laser diode 4 with a side surface 16 is shown.

The semiconductor laser diodes 4 according to the exemplary embodiments of FIG 8th until 10 have facets 17 which are arranged on a side face 16 of the semiconductor laser diode 4 . In the present case, the facets 17 are produced by breaking.

The semiconductor laser diode 4 according to the embodiment of FIG 8th has like the semiconductor laser diode 4 according to the embodiment of FIG 5 until 7 a structure 10 with two trench-shaped recesses 11. The trench-shaped recesses 11 are arranged directly adjacent to a side face 16 of the semiconductor laser diode 4 . The trench-shaped recesses 11 are directly adjacent to the facet 17 .

For example, the facet 17 is designed to be partially transparent to electromagnetic laser radiation that is generated by the semiconductor laser diode 4 . In this case, the facet 17 is considered radiant exit surface of the semiconductor laser diode 4 is formed.

The trench-shaped recesses 11 have a constant width. In a plan view, the trench-shaped recesses 11 have a rectangular base area.

The trench-shaped recesses 11 are arranged symmetrically to an axis of symmetry 22 of a resonator 18 in the present semiconductor laser diode 4 . The resonator 18 is formed by the two opposite facets 17 . In the present case, the trench-shaped recesses 11 extend along a non-absorbing mirror region 24 of the resonator 18, which is only designed to be wave-guiding. Another edge 21 of the trench-shaped recesses 11 adjoins an electrical contact 15 on a main area of the epitaxial semiconductor layer sequence 3 . Furthermore, it is also possible for the trench-shaped recess 11 to overlap with the electrical contact 15 in a plan view.

In contrast to the semiconductor laser diode 4 according to the embodiment of FIG 8th has the semiconductor laser diode according to the embodiment of FIG 9 a structure 10 which comprises four trench-shaped recesses 11 in a growth area 2 of a growth substrate 1. The trench-shaped recesses 11 are of the same design and are arranged symmetrically to an axis of symmetry 22 of a resonator 18 .

The semiconductor laser diode 4 according to the embodiment of FIG 10 has in contrast to the semiconductor laser diode 4 according to the embodiment of FIG 8th Trench-shaped recesses 11, which have a triangular base in plan view. A width of the trench-shaped recess 11 therefore decreases continuously starting from a side surface 16 of the semiconductor laser diode 4 . The indium content in the nitride compound semiconductor material of the epitaxial semiconductor layer sequence 3 is thus varied in a non-absorbing mirror region 24 .

The semiconductor laser diode 4 according to the embodiments of 11 until 13 have as the semiconductor laser diodes 4 according to the embodiments of 8th until 10 Facets 17 which are arranged on side surfaces 16 of the respective semiconductor laser diode 4. The facets 17 are in the embodiments of 11 until 13 generated by breaking.

The semiconductor laser diode 4 according to the embodiment of FIG 11 has in contrast to the semiconductor laser diode 4 according to the embodiment of FIG 8th Trench-shaped recesses 11 with an edge 20 which are set back from a facet 17 of the semiconductor laser diode 4 in plan view.

Likewise, the edges 20 of the trench-shaped recesses 11 of the semiconductor laser diode 4 according to the embodiment of FIG 12 in contrast to the semiconductor laser diode 4 according to the embodiment of FIG 9 arranged set back from a facet 17 .

The trench-shaped recesses 11 of the semiconductor laser diode 4 according to the embodiment of FIG 13 have in contrast to the semiconductor laser diode 4 according to the embodiment of FIG 10 an edge 20 which is set back from a facet 17 .

The semiconductor laser diodes 4 according to the exemplary embodiments of FIG 14 until 16 have in contrast to the semiconductor laser diodes 4 according to the embodiments of 8th until 13 Facets 17 which are arranged set back from a side face 16 of the semiconductor laser diode 4 . The facets 17 are in the embodiments of 14 until 16 generated by etching. Otherwise, the semiconductor laser diodes 4 correspond to the exemplary embodiment of FIG 14 to the semiconductor laser diode 4 according to the embodiment of FIG 11 and the semiconductor laser diode 4 according to the embodiment of FIG 15 to the semiconductor laser diode 4 according to the embodiment of FIG 12 . Furthermore, the semiconductor laser diode 4 corresponds to the embodiment of FIG 16 to the semiconductor laser diode 4 according to the embodiment of FIG 13 .

The semiconductor laser diode 4 according to the embodiment of FIG 17 has in particular a comparatively short amplifier region 19 since the non-absorbing mirror regions 24 extend comparatively far into the resonator 18.

In the semiconductor laser diode 4 according to the embodiment of FIG 18 the structure 10 includes trench-like recesses 11 in the growth area 2 of the growth substrate 1, the distance from a resonator 18 varies along a main extension direction 23 of the resonator 18. In particular, the structure 10 has in each case a multiplicity of structural elements 13 which have a rectangular base area in a plan view. The structural elements 13 are connected continuously. The structural elements 13 are at a distance from the resonator 18 which increases starting from a side face 16 of the semiconductor laser diode 4 . This results in a continuously decreasing to the side surface 16 of the semiconductor laser diode Indium content within the semiconductor material of the epitaxial semiconductor layer sequence 3.

In this case, the indium content is reduced in the non-absorbing mirror regions 24 not only in the active zone 12 and its quantum structures, but also in the surrounding waveguide layers between which the active zone 12 is arranged. In this way, the guidance of the electromagnetic laser radiation in the resonator 18 can be advantageously influenced. If the indium content is lower, the electromagnetic radiation is guided weaker and a near field of the electromagnetic radiation emitted by the semiconductor laser diode 4 is wider, while a far field is narrower. This contributes to reducing the stress on the facet 17 during the operation of the semiconductor laser diode 4.

The semiconductor laser diode 4 according to the embodiment of FIG 19 has trench-shaped recesses 11, which are arranged obliquely to a side face 16 of the semiconductor laser diode 4. A varying distance between the trench-shaped recess 11 and a resonator 18 can also be produced in this way, which leads to the already described variation of the indium content or another of the parameters already described in the epitaxial semiconductor layer sequence 3 .

Also in the case of the semiconductor laser diodes 4 according to the exemplary embodiments of FIG 20 until 22 the trench-shaped recesses 11 have a varying distance along the main extension direction 23 of a resonator 18 . This varying distance also leads to a variation in the indium content or another of the described parameters of the epitaxial semiconductor layer sequence 3, as already described.

The semiconductor laser diode 4 according to the embodiment of FIG 20 has in particular a trench-shaped recess 11 which extends continuously along the entire resonator 18 . In contrast to the semiconductor laser diode 4 according to the embodiment of FIG 18 , In which the trench-shaped recesses 11 are not formed continuously along the entire resonator 18, the semiconductor laser diode 4 according to the embodiment of FIG 20 additional strip-shaped structural elements 23 which run parallel to the resonator 18 in a central area of the growth area 2 .

The semiconductor laser diode 4 according to the embodiment of FIG 21 has trench-shaped recesses 11 which, in regions adjoining the side surface 16 , comprise structural elements 23 which have a greater width than structural elements 23 which are arranged in a central region of the growth surface 2 . Here, too, the trench-shaped recesses 11 extend along the entire resonator 18.

In contrast to the semiconductor laser diode 4 according to the embodiment of FIG 21 has the semiconductor laser diode 4 according to the embodiment of FIG 22 Structural elements 23 which have a triangular base area in plan view of a growth area 2 . The structural elements 23 with the triangular base continuously connect strip-shaped structural elements 23 with a greater width in the area of the facet regions 6 with strip-shaped structural elements 23 with a smaller width in a central region of the growth area 2 .

The invention is not limited to these by the description based on the exemplary embodiments. Rather, the invention encompasses every new feature and every combination of features, which in particular includes every combination of features in the patent claims, even if this feature or this combination itself is not explicitly stated in the patent claims or exemplary embodiments.

reference list

1

growth substrate

2

growth area

3

epitaxial semiconductor layer sequence

4

semiconductor laser diode

5

parting line

6

facet area

7

facet

8th

resonator area

9

resonator

10

structure

11

trench-shaped recess

12

active zone

13

structural element

14

ridge waveguide

15

electric contact

16

side face

17

facets

18

resonator

19

amplifier section

20

edge

21

another edge

22

axis of symmetry

23

main extension direction

24

non-absorbing mirror area

Claims (17)

Method for manufacturing a semiconductor laser diode (4) with the following steps: - Providing a growth substrate (1) with a growth area (2), - introducing at least one structure (10) into at least one facet region (6) of the growth area (2), - Epitaxial growth of an epitaxial semiconductor layer sequence (3) with an active zone (12), which generates electromagnetic radiation during operation, on the growth area (2), wherein - the structure (10) is overgrown by semiconductor material of the epitaxial semiconductor layer sequence (3), so that the active zone (12) has a band gap in a non-absorbing mirror region (24) that is larger than in the remaining region of the active zone (12). Method according to the preceding claim, in which - the epitaxial semiconductor layer sequence (3) is based on a semiconductor material with an indium content, and - The indium content in the non-absorbing mirror area (24) is reduced, so that the band gap in the non-absorbing mirror area (24) is larger than in the remaining area of the active zone (12). Method according to one of the above claims, in which the structure (10) has a trench-shaped recess (11) which is arranged laterally next to a resonator region (8) of the growth area (2). Method according to one of the above claims, in which a facet (17) of the semiconductor laser diode (4) is produced by breaking through the facet regions (6) or by etching through the facet regions (6). Semiconductor laser diode (4) comprising: - a growth substrate (1) with a growth area (2) into which a structure (10) is introduced in a facet region (6), - An epitaxial semiconductor layer sequence (3) which is epitaxially grown on the growth area (2) and comprises an active zone (12) which generates electromagnetic radiation during operation, wherein - the structure (10) is overgrown by semiconductor material of the epitaxial semiconductor layer sequence (3), and - The active zone (12) has a band gap in a non-absorbing mirror area (24) which is larger than in the remaining area of the active zone (12). Semiconductor laser diode (4) according to the preceding claim, comprising two facets (17) forming a resonator (18). Semiconductor laser diode (4) according to one of Claims 5 until 6 , in which an electrical contact (15) is arranged at a distance from a facet (17) on a main surface of the epitaxial semiconductor layer sequence (3). Semiconductor laser diode (4) according to one of Claims 5 until 7 , in which the resonator (18) comprises an amplifier region (19). Semiconductor laser diode (4) according to the preceding claim, in which a length of the amplifier region (19) is at most 300 micrometers. Semiconductor laser diode (4) according to one of Claims 5 until 9 , in which an edge length of the semiconductor laser diode (4) has at least 300 microns. Semiconductor laser diode (4) according to one of Claims 5 until 10 , in which the structure (10) has a trench-shaped recess (11) in the growth area (2) which is directly adjacent to the facet (17). Semiconductor laser diode (4) according to one of Claims 5 until 10 , in which the structure (10) has a ditch-like recess (11) in the growth area (2), which has an edge (20) which is set back from a facet (17) when viewed from above. Semiconductor laser diode (4) according to one of Claims 5 until 12 , in which the structure (10) has a trench-shaped recess (11) in the growth area (2), which has a triangular base area in a plan view of the growth area (2). Semiconductor laser diode (4) according to one of Claims 5 until 13 comprising a ridge waveguide (14), the structure (10) being arranged laterally of the ridge waveguide (14). Semiconductor laser diode (4) according to one of Claims 5 until 14 , in which the structure (10) has a trench-shaped recess (11), wherein a main extension direction (23) of the trench-shaped recess (11) in plan view at an angle a side surface (17) of the semiconductor laser diode (4) is arranged. Semiconductor laser diode (4) according to one of Claims 5 until 15 , in which the structure (10) has a trench-like recess (11), the width of which varies along a main direction of extent (23) of the resonator (18) in a plan view of the growth area (2). Semiconductor laser diode (4) according to one of Claims 5 until 16 In which the structure (10) has a trench-shaped recess (11) whose distance from the resonator (18) varies along a main extension direction (23) of the resonator (18).

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