CN112787210B

CN112787210B - Laser diode

Info

Publication number: CN112787210B
Application number: CN202011640564.3A
Authority: CN
Inventors: 李水清; 钟志白; 黄少华; 张宏铭; 李闳; 臧雅姝; 叶涛
Original assignee: Xiamen Sanan Optoelectronics Technology Co Ltd
Current assignee: Xiamen Sanan Optoelectronics Technology Co Ltd
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2022-05-27
Anticipated expiration: 2040-12-31
Also published as: CN112787210A

Abstract

The invention provides a laser diode which comprises a substrate, a semiconductor layer sequence positioned on a first surface of the substrate, and a reflector formed on the first surface of the substrate, wherein the reflector is close to an exit cavity surface of the semiconductor layer sequence and is distributed at a distance from an epitaxial layer. The light emitted by the exit facets of the semiconductor layer sequence is received and reflected by the mirror, and the reflected light is emitted in a direction perpendicular to the semiconductor layer sequence, forming a surface-emitting laser diode. Therefore, the substrate (wafer) comprising a plurality of laser diodes can be placed in a testing device for direct testing without cutting the edge-emitting laser diodes into bars for testing. The laser diode can greatly simplify the testing process and shorten the testing time. The laser diode realizes the wafer level test of the edge-emitting laser diode, so the debugging condition of the wafer can be visually displayed, and the adjustment of the subsequent laser diode manufacturing process is facilitated.

Description

Laser diode

Technical Field

The invention relates to the field of semiconductor devices, in particular to a laser diode.

Background

Laser diodes have the advantages of high efficiency, small size, and long lifetime, and have attracted great attention. The optoelectronic properties of a laser diode are important characteristics that affect its application. Therefore, the optoelectronic performance test is an essential critical step in the manufacturing process of the laser diode.

The laser diode mainly has a surface emitting laser diode emitting laser light perpendicular to the surface of the resonant cavity and an edge emitting laser diode emitting laser light on the side of the resonant cavity. Taking a GaN-based laser diode as an example, the edge-emitting laser diode has a structure as long as it has an edge-emitting ridge waveguide structure. When testing the edge-emitting laser diode, the edge-emitting laser diode needs to be split into bars for respective testing. The testing method has the disadvantages of multiple procedures, long time consumption and complex operation, can not visually display the debugging condition of the wafer for forming the laser diode, and has a series of testing defects.

Therefore, there is a need for an edge-emitting laser diode capable of performing wafer-level testing to solve the above drawbacks.

Disclosure of Invention

In view of the above-described drawbacks of the prior art, it is an object of the present invention to provide a laser diode in which a reflecting mirror is provided on the exit facet side of a ridge waveguide, the reflecting mirror being provided at a distance from the ridge waveguide structure, and being capable of receiving and reflecting the light emitted from the exit facet. The light emitted from the emitting cavity surface is reflected to the direction vertical to the ridge waveguide structure by adjusting the material composition and the inclination angle of the reflector, so that the light is emitted along the normal direction of the ridge waveguide to form a similar surface emitting laser diode, and the edge emitting laser diode on the whole wafer can be tested without being split into bars. The testing procedures are reduced, the testing time is shortened, and the debugging condition of the wafer can be displayed more intuitively.

To achieve the above and other related objects, the present invention provides a laser diode comprising:

a substrate having a first surface and a second surface disposed opposite to each other;

the semiconductor layer sequence is positioned on the first surface of the substrate, comprises a first semiconductor layer, an active layer and a second semiconductor layer, and is provided with a ridge waveguide structure, and an emergent cavity surface and a reflecting cavity surface are respectively formed at two ends of the ridge waveguide structure in the extension direction;

and the reflecting mirror is formed on the first surface of the substrate, is close to the exit cavity surface of the semiconductor layer sequence, and is distributed at intervals with the semiconductor layer sequence.

Optionally, one surface of the reflector close to the exit cavity surface is an inclined surface.

Optionally, an included angle between the inclined surface of the reflector and the substrate is between 20 ° and 80 °.

Optionally, the mirror is a DBR structure formed of first and second material layers having different refractive indices, wherein the first and second material layers are both insulating material layers.

Optionally, the reflector is a total angle reflector, and includes a DBR structure and a reflective metal layer.

Optionally, the mirror comprises a transparent insulating layer and a reflective metal layer.

Optionally, the first semiconductor layer of the semiconductor layer sequence layer is an n-type GaN epitaxial layer, the second semiconductor layer is a p-type GaN epitaxial layer, and the active layer is a multiple quantum well.

Optionally, the substrate is a conductive substrate, the semiconductor layer sequence and the mirror are bonded to the conductive substrate at one side of the second semiconductor layer, and the first semiconductor layer forms the ridge waveguide structure.

Optionally, a reflective structure is further formed on a surface of the second semiconductor layer of the semiconductor layer sequence, the reflective structure being simultaneously formed on a reflective facet of the ridge waveguide structure, and the reflective structure on the reflective facet being higher than the active layer.

Optionally, the laser diode further comprises a first electrode formed over the first semiconductor layer of the ridge waveguide structure, and a second electrode formed between the bonding layer and the second semiconductor layer.

Optionally, the substrate is an n-type GaN substrate, the first semiconductor layer, the active layer and the second semiconductor layer of the semiconductor layer sequence are epitaxial layers sequentially grown on the first surface of the n-type GaN substrate, and the second semiconductor layer forms the ridge waveguide structure.

Optionally, the laser diode further comprises:

a first electrode on a second surface of the n-type GaN substrate;

a reflective structure located on a second surface of the n-type GaN substrate except the second electrode and wrapping a sidewall of the first electrode; and

a second electrode over the second semiconductor layer in the ridge waveguide structure.

Optionally, the substrate is a sapphire substrate, the first semiconductor layer, the active layer and the second semiconductor layer of the semiconductor layer sequence are epitaxial layers sequentially grown on the first surface of the sapphire substrate, and the second semiconductor layer, the active layer and a part of the first semiconductor layer form the ridge waveguide structure.

Optionally, the laser diode further comprises:

a first electrode over the first semiconductor layer outside the ridge waveguide structure;

a reflective structure located on a second surface of the sapphire substrate; and

As described above, the laser diode provided by the present invention has at least the following advantageous technical effects:

the laser diode of the invention comprises a substrate, a semiconductor layer sequence on a first surface of the substrate, and a mirror formed on the first surface of the substrate, which mirror is close to an exit facet of the semiconductor layer sequence and is spaced apart from the semiconductor layer sequence. The light emitted by the exit facets of the semiconductor layer sequence is received and reflected by the mirror, and the reflected light is emitted in a direction perpendicular to the semiconductor layer sequence, forming a surface-emitting laser diode. Therefore, the substrate (wafer) comprising the laser diodes can be placed in a testing device for direct testing, the wafer-level testing of the edge-emitting laser diodes is realized, and the edge-emitting laser diodes do not need to be cut into bars for testing. The laser diode can greatly simplify the testing process and shorten the testing time. The wafer-level test of the edge-emitting laser diode is realized, so that the debugging condition of the wafer can be visually displayed, and the adjustment of the subsequent laser diode manufacturing process is facilitated.

In addition, the reflecting mirror of the laser diode of the present invention may be formed of different materials, for example, a DBR structure formed by alternately stacking insulating materials having different refractive indexes, or an ODR structure formed by a DBR structure and a metal reflecting layer, or an ODR structure formed by a transparent insulating material and a reflecting metal layer. The side of the reflector, which receives and reflects the light emitted by the emitting cavity surface, is an inclined surface, the angle of the inclined surface is adjustable, and the height of the whole reflector is also adjustable, so that the optimal reflection effect is realized.

The substrate of the laser diode according to the invention can be selected from different types of substrates, for example, a conductive substrate (Si wafer or metal substrate), an epitaxial substrate that is homogenous with the semiconductor layer sequence, or another growth substrate (e.g., sapphire, etc.) on which an epitaxial layer can be grown. The substrate type can be selected according to actual needs, and the flexibility of design and manufacture of the laser diode is increased.

Drawings

Fig. 1 is a schematic structural diagram of an edge-emitting laser diode in the prior art.

Fig. 2 is a schematic structural diagram of a laser diode according to an embodiment of the invention.

Fig. 3 shows a schematic structural diagram of a semiconductor layer sequence formed on a growth substrate.

Fig. 4 shows a schematic diagram of a structure for forming a mirror mesa in the semiconductor layer sequence shown in fig. 3.

Fig. 5 is a schematic diagram illustrating a structure of forming a mirror and a reflecting structure in the structure shown in fig. 4.

Fig. 6 is a schematic diagram illustrating a structure of forming a bonding layer in the structure shown in fig. 5.

Fig. 7 is a schematic diagram of the structure of fig. 6 bonded to a substrate.

Fig. 8 is a schematic structural diagram of a laser diode according to a second embodiment of the present invention.

Fig. 9 is a schematic structural diagram of a laser diode according to a third embodiment of the present invention.

Fig. 10 is a schematic structural diagram illustrating a perspective view of the laser diode shown in fig. 9.

List of reference numerals

10 substrate 1013 second semiconductor layer

11 epitaxial layer 102 mirror

11-1 first semiconductor layer 1021 first material layer

11-2 active layer 1022 second material layer

11-3 second semiconductor layer 103 reflective structure

12 first electrode 104 first electrode

13 second electrode 105 second electrode

14-ridge waveguide structure 106 bonding layer

15 outgoing light 107 reflecting cavity surface

100 base plate 200 growth substrate

101 semiconductor layer sequence 201 recess

1011 first semiconductor layer 202 forming a mirror mesa

1012 active layer

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and although the drawings only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation, the form, quantity, position relationship and proportion of the components in actual implementation can be changed freely on the premise of implementing the technical solution of the present invention, and the layout form of the components may be more complicated.

As shown in fig. 1, a side-emitting laser diode of the prior art is shown. The laser diode comprises a substrate 10 and an epitaxial layer 11 formed on a first surface of the substrate 10, wherein the epitaxial layer at least comprises a first semiconductor layer 11-1, an active layer 11-2 and a second semiconductor layer 11-3 which are grown in sequence. As shown in fig. 1, the second semiconductor layer 11-1 (e.g., a P-type semiconductor layer) forms a ridge structure that forms a ridge waveguide structure 14 in the laser diode, and one end of the ridge waveguide structure 14 is an emission facet and the other end is a reflection facet. A second electrode 13 is formed on the second semiconductor surface of the ridge waveguide structure 14, a first electrode 12 is formed on the second surface of the substrate, and a bias voltage is applied to the first electrode and the second electrode, so that the laser diode emits an emission light 15 from the emission cavity surface of the ridge waveguide structure 14.

Before the subsequent processes such as packaging of the laser diode are performed, a test is required, and generally, the LIV curve of the laser diode, that is, the light-current-voltage curve of the laser diode, needs to be tested. The test is to test the light extraction efficiency of the laser diode, so for the edge-emitting laser diode, the bar needs to be cut first, and then the test is performed. The above process is complicated and time-consuming, and the wafer (substrate) debugging condition cannot be obtained subjectively. In view of the above-mentioned disadvantages of the edge-emitting laser diode during testing, the present invention provides a laser diode capable of implementing wafer-level testing, which is described in detail by the following embodiments.

Example one

The present embodiment provides a laser diode, as shown in fig. 2, which includes a substrate 100, a semiconductor layer sequence 101 formed on a first surface of the substrate 100, and a mirror 102 formed on the first surface of the substrate 100.

In this embodiment, the substrate 100 is a conductive substrate, and may be a semiconductor substrate, such as a monocrystalline silicon wafer, or a metal substrate. In the present embodiment, a Si wafer is taken as an example for explanation.

As also shown in fig. 2, the semiconductor layer sequence 101 comprises a second semiconductor layer 103 bonded to a Si wafer, an active layer 1012 and a first semiconductor layer 101. Taking a GaN-based laser diode as an example, the first semiconductor layer 1011 may be an n-type layer, the active layer 1012 may be a quantum well layer, and the second semiconductor layer may be a p-type layer. The first semiconductor layer 1011 forms a ridge structure (see the structure described in fig. 1) extending in the direction indicated by the arrow a, and the surface of the ridge structure forms the first electrode 104. The ridge structure forms a ridge waveguide structure when the laser diode works, so that the laser diode emits light along one end of the ridge waveguide structure. As shown in fig. 2, in this embodiment, along the extending direction of the ridge waveguide structure, one end of the semiconductor layer sequence 101 close to the reflector forms an exit cavity surface, and the end opposite to the exit cavity surface forms a reflection cavity surface, and both the exit cavity surface and the reflection cavity surface are vertical cavity surfaces.

The surface of the second semiconductor layer is formed with a second electrode 105 and a reflective structure 103 covering all but the surface of the second semiconductor layer 105 and being flush with the surface of the second electrode structure. At the same time, the reflective structure 103 is also formed on the reflection facets of the semiconductor layer sequence 102, on which the reflective structure covers at least the active layer 1012, i.e. the height of the reflective structure 103 on the reflection facets is higher than the active layer or is flush with the active layer. Preferably, the reflective structure is formed higher than the active layer on sidewalls of the portion of the first semiconductor layer. The reflection structure can effectively reflect the light emitted by the active layer, so that the emergent light is emitted along the surface of the emitting cavity.

Referring also to fig. 2, the mirror 102 is formed on the exit facet side of the semiconductor layer sequence 102 and is spaced apart from the semiconductor layer sequence. The height of the mirror is higher than the height of the active layer in order to be able to receive all the light emitted by the semiconductor layer sequence. The surface of the mirror 102 which is close to the exit facet of the semiconductor layer sequence is formed as an inclined surface, i.e. the distance between the exit facet of the semiconductor layer sequence 101 and the mirror 102 increases from the substrate 100 in the direction of the semiconductor layer sequence. The angle between the inclined surface and the surface of the substrate 100 is 20 to 80 °, preferably 30 to 60 °. The height of the reflector and the inclination angle of the inclined plane are adjustable, and can be adjusted according to the irradiation range of the light emitted by the semiconductor layer sequence, so that the light emitted by the semiconductor layer sequence is totally reflected to be emitted along the normal direction of the substrate.

In an alternative embodiment, the mirror 102 is a DBR structure, and is formed by alternately stacking first material layers 1021 and second material layers 1022 having different refractive indexes. Fig. 2 illustrates only one reflective film group composed of a first material layer and a second material layer, and it is understood that the reflective mirror 102 may include several reflective film groups. The first material layer and the second material layer may be any materials having different refractive indexes, and may be selected from silicon oxide, titanium oxide, silicon nitride, aluminum oxide, and the like. In this embodiment, the first material layer and the second material layer forming the reflecting mirror may be silicon oxide and titanium oxide, or may be silicon oxide and silicon nitride.

In another optional embodiment of the present embodiment, the reflective mirror 102 is an ODR structure formed by a DBR and a reflective metal layer, and the ODR structure can perform all-directional reflection on the outgoing light of the semiconductor layer sequence, so that the test result is more accurate. Alternatively, the first material layer and the second material layer forming the DBR structure may be any materials having different refractive indexes, and in an example, the first material layer and the second material layer forming the reflective mirror may be selected from silicon oxide, titanium oxide, silicon nitride, aluminum oxide, and the like. The reflective metal layer may be Ag or Al, etc. In an alternative embodiment, the mirror 102 may also be an ODR structure formed with a transparent insulating layer and a reflective metal layer, such as an ODR structure formed of silicon dioxide and Ag.

In this embodiment, the reflective structure 103 and the mirror 102 may be the same structure, for example, the reflective structure 103 is also a DBR structure or an ODR structure formed by a DBR structure and a reflective metal layer.

Also referring to fig. 2, between the mirror and the reflective structure and the substrate 100, there is further a bonding layer 106, the bonding layer 106 being a bonding metal layer, which may be one or more layers of structure, through which the semiconductor layer sequence and the mirror are bonded to the substrate 100.

As shown in fig. 2, since the reflector is formed on one side of the exit cavity surface of the semiconductor layer sequence, light emitted from the exit cavity surface of the semiconductor layer sequence can be emitted along the normal direction of the substrate after being reflected by the reflector, i.e. a laser diode similar to a surface emitting laser is formed, when testing, the light emitting efficiency of the laser diode can be directly tested on the front surface of the substrate, and the edge emitting laser diode does not need to be split into bars. The testing process and time are saved, the wafer-level testing of the edge-emitting laser diode is realized, and the debugging condition of the wafer can be visually displayed.

The laser diode shown in fig. 2 can be manufactured by the following method:

first, as shown in fig. 3, a growth substrate 200 is provided, for example, the growth substrate 200 may be sapphire or the like. An n-type GaN layer 1011, a quantum well layer 1012, and a p-type GaN layer 1013 are sequentially grown on a growth substrate to form a semiconductor layer sequence. Then, as shown in fig. 4, the semiconductor layer sequence is etched to form a groove 201 above the substrate, an inclined surface is formed at one end of the semiconductor layer sequence on both sides of the groove to form a mesa 202 for forming a mirror, and a right-angled surface is formed on a side wall of the semiconductor layer sequence opposite to the inclined surface to serve as a reflection cavity surface of the laser diode. In this step, the semiconductor layer sequence may be etched by dry etching, and the etching depth and the etching angle are controlled by controlling parameters such as the etching duration, the flow rate of etching gas, and the angle, so as to control the height of the subsequently formed reflector and the angle of the inclined surface. As shown in fig. 4, in this embodiment, a groove 201 is formed by etching until the growth substrate 200 is exposed. The groove 201 is formed in an inverted trapezoid-like opening shape in which the opening gradually becomes larger in the growth direction of the semiconductor layer.

After the mesa 202 and recess 201 are formed, layers of materials of different refractive indices are deposited on the mesa 202 and the bottom and sidewall facets of the recess 201 to form the mirror 102. In this embodiment, the mirror and the reflecting structure are the same structure and are formed simultaneously. As shown in fig. 5, a first material layer 1021 and a second material layer 1022 having different refractive indexes are sequentially deposited on the sidewalls and the bottom of the groove 201 and the surface of the second semiconductor layer to form a mirror and a reflective structure 103. The reflective structure 103 is simultaneously formed on the reflective facets of the semiconductor layer sequence and covers at least the active layer 1012 on the reflective facets.

Then, as shown in fig. 6, a second electrode 105 is first formed on the second semiconductor layer, the second electrode 105 is formed by, for example, etching the reflective structure, depositing a conductive material, and the like, and then a bonding metal layer 106 is deposited, which fills the groove 201 and is formed on the surface of the reflective structure. And flattening the bonding metal layer. Thereafter, as shown in fig. 7, the structure shown in fig. 6 is turned over so that the bonding metal layer 106 faces the substrate 100 and is bonded to the substrate 100. The growth substrate 200 is then stripped, exposing the n-type GaN layer. And etching the semiconductor layer sequence to form an exit cavity surface, and forming a gap between the exit cavity surface of the semiconductor layer sequence and the reflector to isolate the semiconductor layer sequence and the reflector. Finally, a ridge structure is formed in the n-type GaN, and a first electrode 104 is formed on the surface of the ridge structure.

As described above, in this embodiment, the reflecting structure on the reflecting cavity surface of the mirror and the semiconductor layer sequence can be formed simultaneously by using the same material, so that the manufacturing process is saved while the light is emitted from the surface of the edge emitting diode.

Example two

The present embodiment also provides a laser diode, as shown in fig. 8, which includes a substrate 100, a semiconductor layer sequence 101 formed on a first surface of the substrate 100, and a mirror 102 formed on the first surface of the substrate 100. The same parts as those in the first embodiment are not described again, but the differences are as follows:

in this embodiment, the substrate 100 of the laser diode is a substrate that is homogeneous with the semiconductor layer sequence. Taking a GaN-based laser diode as an example, the substrate 100 is an n-type GaN substrate, and the semiconductor layer sequence 101 includes an n-type GaN layer 1011, a quantum well layer 1012, and a p-type GaN layer 1013 epitaxially grown in this order on the substrate 100. Wherein the p-type GaN layer 1013, the quantum well layer 1012, and the portion of the n-type GaN layer 1011 form a ridge structure. The reflective facets 107 are formed on the rear facet of the ridge structure, on which reflective facets can be formed, for example, by atomic layer deposition.

The mirror 102 is formed on the side of the exit facet of the semiconductor layer sequence and is spaced apart from the semiconductor layer sequence. The mirror is formed in this embodiment on a mesa 202 formed by the semiconductor layer sequence. After the formation of the semiconductor layer sequence, the exit facet can be formed by means of etching on the other side of the ridge opposite the reflection facet, and a mesa 202 with inclined side faces is further formed in the semiconductor layer sequence, which mesa 202 is spaced apart from the semiconductor layer sequence serving as a laser diode. Layers of materials of different refractive indices are then deposited on the surface of the mesa 202 to form a mirror. The mirror is the same as in the first embodiment and will not be described in detail.

As shown in fig. 8, a first electrode is formed on the second surface of the n-type GaN substrate 100, and a second electrode 105 is formed on the p-type GaN layer of the ridge structure. While the second surface of the substrate 100 also forms a reflective structure 103, the reflective structure 103 covering all second surfaces of the substrate 100 except the first electrode. The reflective structure may be a DBR structure.

EXAMPLE III

The present embodiment also provides a laser diode, as shown in fig. 9, which includes a substrate 100, a semiconductor layer sequence 101 formed on a first surface of the substrate 100, and a mirror 102 formed on the first surface of the substrate 100. The same parts as those in the first embodiment are not described again, but the differences are as follows:

in this embodiment, the substrate 100 of the laser diode is a substrate that is heterogeneous to the semiconductor layer sequence, and may be, for example, a sapphire substrate used as a growth substrate, and in the case of a GaN-based laser diode, the semiconductor layer sequence 101 includes an n-type GaN layer 1011, a quantum well layer 1012, and a p-type GaN layer 1013 epitaxially grown in this order on the substrate 100. Wherein the p-type GaN layer 1013, the quantum well layer 1012, and a portion of the n-type GaN layer 1011 form a ridge structure. The reflective facets 107 are formed on the rear facet of the ridge structure, on which reflective facets a reflective structure can be formed, for example, by atomic layer deposition.

The mirror 102 is formed on the side of the exit facet of the semiconductor layer sequence and is spaced apart from the semiconductor layer sequence. The mirror is formed in this embodiment on a mesa 202 formed by the semiconductor layer sequence. After the formation of the semiconductor layer sequence, the exit facet can be formed by means of etching on the other side of the ridge opposite the reflection facet, and a mesa 202 with inclined side faces is further formed in the semiconductor layer sequence, which mesa 202 is spaced apart from the semiconductor layer sequence serving as a laser diode. Layers of materials of different refractive indices are then deposited on the surface of mesa 202 to form a mirror. The mirror is the same as in the first embodiment and will not be described in detail.

As shown in fig. 10, a first electrode 104 is formed on the n-type GaN layer exposed at one side of the ridge structure, a second electrode 105 is formed on the p-type GaN layer of the ridge structure, and a reflective structure 103 is further formed on the second surface of the substrate 100, the reflective structure 103 covering all the second surface of the substrate 100 except the first electrode. The reflective structure may be a DBR.

The above embodiments only schematically illustrate the substrate type of the laser diode, and it is understood that the laser diode can be selected from any suitable substrate or substrate, and can be selected according to actual needs, thereby increasing the flexibility of the design and manufacture of the laser diode.

In addition, the reflecting mirror of the laser diode of the present invention may be formed of different materials, for example, a DBR structure formed by alternately stacking insulating materials having different refractive indexes, or an ODR structure formed by a DBR structure and a metal reflecting layer, or an ODR structure formed by a transparent insulating material and a reflecting metal layer. One side of the reflector, which receives and reflects the light emitted from the light-emitting cavity surface, is an inclined plane, the angle of the inclined plane is adjustable, and the height of the whole reflector is also adjustable, so that the optimal reflection effect is realized.

The substrate of the laser diode according to the invention can be selected from different types of substrates, for example, a conductive substrate (Si wafer or metal substrate), an epitaxial substrate that is homogenous with the semiconductor layer sequence, or another growth substrate (e.g., sapphire, etc.) on which an epitaxial layer can be grown. The type of the substrate can be selected according to actual needs, and the flexibility of design and manufacture of the laser diode is increased.

Claims

1. A laser diode, comprising:

and the reflector is formed on the first surface of the substrate, is close to the exit cavity surface of the semiconductor layer sequence and is distributed at intervals with the semiconductor layer sequence, and the material layers with different refractive indexes are deposited in the grooves formed in the semiconductor layer sequence to form the reflector.

2. The laser diode of claim 1, wherein a surface of said mirror adjacent to said exit facet is tilted.

3. The laser diode of claim 2, wherein the angle between the tilted surface of the mirror and the substrate is between 20 ° and 80 °.

4. The laser diode of claim 1, wherein the mirror is a DBR structure formed of first and second material layers having different refractive indices, wherein the first and second material layers are both insulating material layers.

5. The laser diode of claim 1, wherein the mirror is a total angle mirror comprising a DBR structure and a reflective metal layer.

6. The laser diode of claim 1, wherein the mirror comprises a transparent insulating layer and a reflective metal layer.

7. The laser diode of claim 1, wherein the first semiconductor layer of the sequence of semiconductor layers is an n-type GaN epitaxial layer, the second semiconductor layer is a p-type GaN epitaxial layer, and the active layer is a multiple quantum well.

8. The laser diode according to claim 7, wherein the substrate is a conductive substrate, the semiconductor layer sequence and the mirror are bonded to the conductive substrate via a bonding layer on the side of the second semiconductor layer, the first semiconductor layer forming the ridge waveguide structure.

9. The laser diode of claim 8, wherein a reflective structure is further formed on a surface of the second semiconductor layer of the semiconductor layer sequence, the reflective structure being simultaneously formed on a reflective facet of the ridge waveguide structure, and the reflective structure on the reflective facet being higher than the active layer.

10. The laser diode of claim 9, further comprising a first electrode formed over the first semiconductor layer of the ridge waveguide structure and a second electrode formed between the bonding layer and the second semiconductor layer.

11. The laser diode of claim 7, wherein the substrate is an n-type GaN substrate, the first semiconductor layer, the active layer, and the second semiconductor layer of the sequence of semiconductor layers are epitaxial layers sequentially grown on a first surface of the n-type GaN substrate, the second semiconductor layer forming the ridge waveguide structure.

12. The laser diode of claim 11, further comprising:

a first electrode on a second surface of the n-type GaN substrate;

a reflective structure located on a second surface of the n-type GaN substrate except the first electrode and wrapping a sidewall of the first electrode; and

13. The laser diode of claim 7, wherein the substrate is a sapphire substrate, the first semiconductor layer, the active layer, and the second semiconductor layer of the semiconductor layer sequence are epitaxial layers sequentially grown on the first surface of the sapphire substrate, and the second semiconductor layer, the active layer, and a portion of the first semiconductor layer form the ridge waveguide structure.

14. The laser diode of claim 13, further comprising:

a first electrode located over the first semiconductor layer outside the ridge waveguide structure;