Semiconductor laser chip for improving thermal lens effect of wide ridge

Abstract

The application discloses a semiconductor laser chip for improving wide ridge thermal lens effect, wherein a P-type limiting layer of the chip is in a ridge table shape, and both sides of the ridge table shape are inwardly recessed grooves. Surfaces of the grooves are covered with insulating layers. The top surface of the ridge table is covered with an ohmic contact layer. A P-face electrode layer is covered on the insulating layer and the ohmic contact layer, and a hole is formed between the P-face electrode layer and the insulating layer at the groove. The semiconductor laser chip structure of the application sets both side walls of the P-type limiting layer in a ridge table shape as a recessed groove structure, thereby forming a hole structure at the groove. Since the air heat dissipation coefficient in the insulating layer and the hole is very low, the heat dissipation efficiency at the side wall of the ridge P-type limiting layer is poor, the convex temperature distribution of the P-type limiting layer in the side wall direction is eliminated, the temperature of the middle region and the edge region of the P-type limiting layer is consistent, the thermal lens effect is eliminated, and the light beam quality of the semiconductor laser is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor laser, in particular to a semiconductor laser chip for improving thermal lens effect of wide ridge. BACKGROUND

[0002] The information disclosed in the background of the present application is only intended to increase the understanding of the overall background of the present application and should not necessarily be regarded as acknowledging or implicitly suggesting that this information constitutes prior art known to those of ordinary skill in the art.

[0003] Wide stripe high power semiconductor laser has been continuously developed due to its high output power, simple preparation process, simple packaging process, easy integration and mass production, and has been widely used in the fields of laser cutting, medical beauty and industrial pumping. Generally, wide stripe high power semiconductor laser adopts ridge stripe process, that is, a ridge structure with a depth not exceeding the P-type confinement layer is etched in the lateral direction of the wafer. Current passes through the ridge into the active region and radiates and recombines to generate photons. However, the current wide stripe high power semiconductor laser generally has a "thermal lens" effect, which affects the beam quality of the semiconductor laser.

[0004] Chinese patent CN104332823A discloses a method for improving the beam quality of wide stripe high power semiconductor laser. The method mainly applies a convex intensity distribution of tensile stress on the wide stripe high power semiconductor laser chip to weaken the convex refractive index distribution caused by the waveguide de-convex temperature distribution, suppress the thermal lens effect of the laser waveguide, and thus improve the beam quality of the wide stripe high power semiconductor laser. However, the present inventors have found that the method needs to introduce a solder pad in the edge region of the chip by packaging and apply pressure in the middle of the chip during soldering, which will result in low packaging efficiency and low yield, and is not suitable for mass production. SUMMARY

[0005] In view of the above problems, the present application provides a semiconductor laser chip for improving thermal lens effect of wide ridge. The semiconductor laser chip structure provided by the present application not only eliminates the thermal lens effect at the chip scale, does not change the later packaging process, and can be packaged by conventional packaging method, which improves the performance of the chip while ensuring the production efficiency of the chip. To achieve the above purpose, the present application discloses the technical scheme as shown below.

[0006] In the first aspect of the present application, a semiconductor laser chip for improving the wide ridge thermal lens effect is disclosed. The P-type confinement layer of the chip is in a ridge mesa shape, and the two sides of the ridge mesa are inwardly recessed grooves. The groove surface is covered with an insulating layer. The top surface of the ridge mesa is covered with an ohmic contact layer. The insulating layer and the ohmic contact layer are covered with a P-face electrode layer, and a hole is formed between the P-face electrode layer and the insulating layer at the groove.

[0007] Further, the P-type confinement layer is arranged on a P-type waveguide layer, and the insulating layer extends to cover the P-type waveguide layer around the P-type confinement layer.

[0008] Optionally, the material of the P-type confinement layer includes any one of AlGaAs, AlGaInP, etc.

[0009] Optionally, the material of the P-type waveguide layer includes any one of AlGaAs, AlGaInP, etc.

[0010] Further, the P-type waveguide layer is arranged on an active layer. Optionally, the active layer 7 is a narrow-bandgap intrinsic semiconductor material with a thickness of 7-10 nm.

[0011] Further, the active layer is arranged on an N-type waveguide layer. Optionally, the material of the N-type waveguide layer includes any one of AlGaAs, AlGaInP, etc.

[0012] Further, the N-type waveguide layer is arranged on an N-type confinement layer. Optionally, the material of the N-type confinement layer includes any one of AlGaAs, AlGaInP, etc.

[0013] Further, the N-type confinement layer is arranged on a substrate. Optionally, the material of the substrate includes any one of XXX, etc.

[0014] Further, the N-face metal is arranged on the substrate. Optionally, the material of the N-face metal includes any one of AuGeNi, TiPtAu, etc.

[0015] Further, the thickness of the insulating layer is preferably maintained between 300 nm and 500 nm, which is greater than the thickness of the insulating layer in a conventional semiconductor laser chip, and helps to reduce the heat dissipation capacity at the edge of the ridge.

[0016] Further, the P-face electrode layer is prepared by electron beam evaporation process, and a relatively fast growth rate is used during preparation to ensure that the P-face electrode grows into a film quickly without being based on the insulating layer in the groove, thereby forming a hole on both sides of the ridge mesa. Preferably, the growth rate is not less than 10 nm / s.

[0017] Further, the ridge-shaped platform is a strip-shaped platform formed by protruding from the P-type confinement layer.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] The semiconductor laser chip structure provided by the present application not only eliminates the thermal lens effect at the chip scale, does not change the later packaging process, and can be packaged by using a conventional packaging method, thereby improving the chip performance while ensuring the production efficiency of the chip. The semiconductor laser chip structure of the present application sets the two side walls of the ridge-shaped P-type confinement layer into a groove-shaped structure that is recessed inward, thereby forming a hole structure at this location. Since the heat dissipation coefficient of air in the insulating layer and the hole is very low, the heat dissipation efficiency at the side wall of the ridge P-type confinement layer is poor, the convex temperature distribution of the ridge-shaped P-type confinement layer in the upward direction of the side wall is eliminated, the temperature of the middle region and the edge region of the P-type confinement layer is consistent, and the thermal lens effect is eliminated, thereby effectively improving the beam quality of the semiconductor laser. BRIEF DESCRIPTION OF DRAWINGS

[0020] The drawings constituting a part of the present application are used to provide a further understanding of the present application, and the schematic embodiments of the present application and the description thereof are used to explain the present application, and do not constitute an improper limitation on the present application.

[0021] Figure 1 Structure schematic diagram of the semiconductor laser chip for improving the thermal lens effect of the wide ridge strip in the embodiment.

[0022] Figure 2 Structure schematic diagram of the semiconductor laser chip for improving the thermal lens effect of the wide ridge strip in the embodiment.

[0023] The numerical labels in the figure respectively represent the following components: 1-P-type confinement layer, 2-insulating layer, 3-ohmic contact layer, 4-P-face electrode layer, 5-hole, 6-P-type waveguide layer, 7-active layer, 8-N-type waveguide layer, 9-N-type confinement layer, 10-substrate, and 11-N-face metal. DETAILED DESCRIPTION

[0024] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0025] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, devices, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, steps, operations, devices, components, and / or combinations thereof.

[0026] For the convenience of description, if the terms "upper", "lower", "left", "right" are used in the present application, they only mean the same direction as the upper, lower, left and right directions of the drawings themselves, and do not limit the structure, but only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to needs to have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The semiconductor laser coupler will be described in detail in conjunction with the drawings and specific embodiments.

[0027] Referring to Figure 1 and Figure 2 , an example semiconductor laser chip structure is provided to improve the thermal lens effect of a ridge with a large width on the chip, such as a width of more than 500 μm. The main reason for this problem is that a large working current is required for a high-power semiconductor laser, and the heat dissipation rate in the middle region of the ridge is lower than that in the edge region of the ridge, which causes the temperature in the middle region of the ridge to be higher than that in the edge region of the ridge, resulting in a convex temperature distribution in the lateral direction of the ridge, and further resulting in a convex effective refractive index, i.e., the effective refractive index in the middle region of the ridge is higher than that in the edge region of the ridge, i.e., a so-called "thermal lens" effect is generated, which will cause the deterioration of the beam quality of the semiconductor laser.

[0028] To this end, the two sides of the P-type confinement layer 1 of the ridge-shaped mesa / ridge-shaped chip are designed as inwardly recessed groove-shaped structures. The P-type confinement layer 1 of the ridge-shaped mesa is prepared by etching the P-type confinement layer 1 with a phosphoric acid etching solution to form a ridge-shaped mesa 2. The material of the P-type confinement layer 1 can be selected from AlGaAs, AlGaInP, or any other suitable material.

[0029] The surface of the groove on both sides of the P-type confinement layer 1 is covered with an insulating layer 2 of XXX (SiO2 or Si3N4) material. The thickness of the insulating layer 3 is between 300 nm and 500 nm, such as 300 nm, 305 nm, 320 nm, 350 nm, 370 nm, 400 nm, 410 nm, 430 nm, 450 nm, 460 nm, 480 nm, 500 nm, etc. It should be noted that the thickness of the insulating layer 2 exceeds the thickness of the insulating layer in a conventional semiconductor laser chip, which helps to reduce the heat dissipation capacity at the edge of the ridge.

[0030] The top surface of the ridge-shaped platform 2 is covered with an ohmic contact layer 3. The insulating layer 2 and the ohmic contact layer 3 are covered with a P-face electrode layer 4, and a hole 5 is formed between the P-face electrode layer 4 and the insulating layer 2 at the groove. The P-face electrode layer is prepared by electron beam evaporation process, and a relatively fast growth rate is used during preparation. In general, the rate is not less than 10 nm / s, which ensures that the P-face electrode grows into a film quickly without being based on the insulating layer in the groove, thereby forming a hole 5 on both sides of the ridge-shaped platform.

[0031] The embodiment sets the sidewalls of the P-type confinement layer in a ridge-shaped platform into a groove-shaped structure that is recessed inward, thereby forming a hole structure there. Since the air heat dissipation coefficient in the insulating layer and the hole is very low, the heat dissipation efficiency at the sidewall of the ridge P-type confinement layer is poor, which eliminates the convex temperature distribution of the P-type confinement layer in the sidewall direction, realizes the temperature consistency of the middle region and the edge region of the P-type confinement layer, and further eliminates the thermal lens effect, effectively improving the beam quality of the semiconductor laser.

[0032] Further, the semiconductor laser chip structure mentioned in the above embodiment is further exemplarily illustrated in the following embodiments. For example, the P-type confinement layer 1 is arranged on a P-type waveguide layer 6, and the insulating layer 2 extends to cover the P-type waveguide layer 6 around the P-type confinement layer 1. The P-type waveguide layer 6 is arranged on an active layer 7. The active layer 7 is a narrow-bandgap intrinsic semiconductor with a thickness of 7-10 nm. The active layer 7 is arranged on an N-type waveguide layer 8. The N-type waveguide layer 8 is arranged on an N-type confinement layer 9. The N-type confinement layer 9 is arranged on a substrate 10. The substrate 10 is arranged on an N-face metal 11.

[0033] The material of the P-type waveguide layer 6 can be selected from AlGaAs, AlGaInP, etc. The material of the N-type waveguide layer 8 can be selected from AlGaAs, AlGaInP. The material of the N-type confinement layer 9 can be selected from AlGaAs, AlGaInP, etc. The material of the substrate 10 can be selected from GaAs, etc. The material of the N-face metal 11 can be selected from AuGeNi, TiPtAu, etc. The technical solution of the embodiment overcomes the thermal lens effect existing in the prior art wide-bar-shaped high-power semiconductor laser, which is that the two side walls of the ridge-shaped table-shaped P-type confinement layer 1 are set as a recessed groove structure, thereby forming a hole structure at the two side walls. Since the heat dissipation coefficient of air in the hole and the insulating layer 3 is very low, the heat dissipation efficiency at the side wall of the ridge P-type confinement layer 1 is poor, the convex temperature distribution of the P-type confinement layer 1 in the side wall direction is eliminated, the temperature of the middle region and the edge region of the P-type confinement layer 1 is consistent, and the thermal lens effect is eliminated, thereby effectively improving the beam quality of the semiconductor laser.

[0034] Therefore, it should be understood that in the present application, the P-type waveguide layer 6, the active layer 7, the N-type waveguide layer 8, the N-type confinement layer 9, the substrate 10, and the N-face metal 11 are mainly used as a carrier structure, and the selection of the material and the adjustment and change of the structure do not have a decisive influence on the design of eliminating the thermal lens effect by setting the two side walls of the ridge-shaped table-shaped P-type confinement layer as a recessed groove structure. Therefore, those skilled in the art can also select other suitable structures of the carrier structure according to the needs. Therefore, any technical solution containing the above technical concept is considered as an equivalent replacement of the technical solution of the present application.

[0035] Finally, it should be noted that any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application. Although the specific embodiments of the present application are described above with reference to the accompanying drawings, the present application is not limited to the above-described embodiments, and various modifications or changes can be made by those skilled in the art without creative labor, which are still within the protection scope of the present application.

Claims

1. A semiconductor laser chip for improving the thermal lens effect of a wide ridge, wherein, a P-type confinement layer of the chip is in a ridge mesa shape with two sides being inwardly recessed grooves; a surface of the grooves is covered with an insulating layer; and a top surface of the ridge mesa is covered with an ohmic contact layer; a P-face electrode layer is covered on the insulating layer and the ohmic contact layer, and a hole is formed between the P-face electrode layer and the insulating layer at the grooves.

2. The semiconductor laser chip that ameliorates wide ridge thermal lens effect according to claim 1, characterized in that, the P-type confinement layer is disposed on a P-type waveguide layer, and the insulating layer extends to cover the P-type waveguide layer around the P-type confinement layer.

3. The semiconductor laser chip that ameliorates wide ridge thermal lens effect according to claim 2, characterized in that, a material of the P-type confinement layer comprises any one of AlGaAs and AlGaInP.

4. The semiconductor laser chip of claim 2, wherein, a material of the P-type waveguide layer comprises any one of AlGaAs and AlGaInP.

5. The semiconductor laser chip of claim 2, wherein, the P-type waveguide layer is disposed on an active layer.

6. The semiconductor laser chip that ameliorates wide ridge thermal lens effect according to claim 5, characterized in that, the active layer is a narrow band gap intrinsic semiconductor with a thickness of 7-10 nm.

7. The semiconductor laser chip of claim 5, wherein, the active layer is disposed on an N-type waveguide layer.

8. The semiconductor laser chip that ameliorates wide ridge thermal lens effect according to claim 7, characterized in that, a material of the N-type waveguide layer comprises any one of AlGaAs and AlGaInP.

9. The semiconductor laser chip of claim 7, wherein, the N-type waveguide layer is disposed on an N-type confinement layer.

10. The semiconductor laser chip that ameliorates the wide ridge thermal lens effect according to claim 9, wherein, a material of the N-type confinement layer comprises any one of AlGaAs and AlGaInP.

11. The semiconductor laser chip that ameliorates wide ridge thermal lens effect according to claim 9, characterized in that, the N-type confinement layer is disposed on a substrate.

12. The semiconductor laser chip that ameliorates the wide ridge thermal lens effect according to claim 11, wherein, a material of the substrate comprises any one of GaAs.

13. The semiconductor laser chip that ameliorates wide ridge thermal lens effect according to claim 11, wherein, the substrate is disposed on an N-face metal.

14. The semiconductor laser chip that ameliorates wide ridge thermal lens effect according to claim 13, wherein, a material of the N-face metal comprises any one of AuGeNi and TiPtAu.

15. The semiconductor laser chip that ameliorates the wide ridge thermal lens effect according to any one of claims 1-14, wherein, a thickness of the insulating layer is kept between 300 nm and 500 nm.

16. The semiconductor laser chip that ameliorates the wide ridge thermal lens effect according to any one of claims 1-14, wherein, the P-face electrode layer is prepared by an electron beam evaporation process.

17. The semiconductor laser chip that ameliorates the wide ridge thermal lens effect according to any one of claims 1-14, wherein, the ridge mesa is a strip-shaped boss formed by protruding part of the P-type confinement layer.

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