Semiconductor laser, preparation method thereof and laser projection equipment

Abstract

The invention relates to a semiconductor laser, a preparation method thereof and laser projection equipment. The semiconductor laser comprises a first electrode, an N-type substrate, an N-type buffer layer, an N-type limiting layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, a P-type limiting layer, an ohmic contact layer, an insulating layer and a second electrode which are sequentially arranged. One side, far away from the N-type substrate, of the first electrode and / or one side, far away from the ohmic contact layer, of the second electrode further comprises a soaking structure; in the first direction, the semiconductor laser comprises an injection region and a non-injection region, and the soaking structure located in the non-injection region comprises first parts and second parts which are alternately arranged; the first direction is parallel to the plane of the first electrode or the second electrode; wherein the first part and the second part are different in heat conductivity. Based on the scheme, the thermal lens effect can be improved, and the light beam quality of the semiconductor laser can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of display devices, and in particular to a semiconductor laser and a preparation method thereof, and a laser projection device. Background Art

[0002] Wide stripe high-power laser diodes (WS-HPLDs) are widely used in various fields due to their advantages, including wide output band coverage, high output power, compact size, and long life. As their application areas continue to expand, higher requirements are placed on their output power and electro-optical conversion efficiency. Currently, the output power of a single wide stripe semiconductor laser has reached tens of watts. Furthermore, certain fields also require WS-HPLDs to simultaneously achieve high brightness output, such as fiber coupling, laser projection, optical communications, laser medical treatment, and scientific research.

[0003] During the operation of a semiconductor laser, as the injection current increases, the probability of non-radiative recombination of carriers in the active region of the semiconductor laser increases, thereby increasing the thermal power of the semiconductor laser. The semiconductor laser may exhibit a high center temperature and a low edge temperature, which will cause the refractive index distribution of the semiconductor laser waveguide material to change, triggering a "thermal lens effect", which in turn causes the divergence angle of the semiconductor laser to increase and the beam quality to decrease. Summary of the Invention

[0004] In a first aspect, the present application provides a semiconductor laser, comprising a first electrode, an N-type substrate, an N-type buffer layer, an N-type confinement layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, a P-type confinement layer, an ohmic contact layer, an insulating layer, and a second electrode, which are arranged in sequence;

[0005] The side of the first electrode away from the N-type substrate and / or the side of the second electrode away from the ohmic contact layer further includes a heat distribution structure;

[0006] Along a first direction, the semiconductor laser includes an injection region and a non-injection region, and the heat-dissipating structure located in the non-injection region includes a first portion and a second portion that are alternately arranged; the first direction is parallel to a plane where the first electrode or the second electrode is located;

[0007] The first portion and the second portion have different thermal conductivities.

[0008] In a second aspect, the present application further provides a method for preparing a semiconductor laser, the method being used to prepare the semiconductor laser described in the first aspect; the method comprising:

[0009] A semiconductor structure is provided; wherein the semiconductor structure includes the first electrode, the N-type substrate, the N-type buffer layer, the N-type confinement layer, the N-type waveguide layer, the active layer, the P-type waveguide layer, the P-type confinement layer, the ohmic contact layer, the insulating layer, and the second electrode, which are arranged in sequence;

[0010] preparing a photoresist layer on a side of the first electrode away from the N-type substrate and / or a side of the second electrode away from the ohmic contact layer;

[0011] Preparing the photoresist layer having patterns corresponding to the first portion and the second portion based on the photoresist layer; preparing a heat-saturating layer on the surface of the photoresist layer;

[0012] removing the photoresist layer so that the heat-sinking layer forms the heat-sinking structure having the first portion and the second portion;

[0013] A surface layer is prepared on the surface of the heat-saturating structure, and the material of the surface layer is the same as that of the first electrode and / or the second electrode.

[0014] In a third aspect, the present application further provides a laser projection device, comprising a display control component, a light source driving component, a light source, a light valve, and a projection lens;

[0015] The display control component is electrically connected to the light source driving component and the light valve respectively, and the light source driving component is electrically connected to the light source;

[0016] The light source includes at least one semiconductor laser according to the first aspect.

[0017] In the above scheme, the semiconductor laser provided by the present application adds a heat-distributing structure consisting of a first part and a second part alternately arranged in the non-injection area to transfer and block the heat generated in the non-injection area, so that the temperature distribution of the semiconductor laser is more uniform, thereby suppressing the thermal lens effect of the semiconductor laser and improving the beam quality of the semiconductor laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of a beam path provided for one or more embodiments of the present application;

[0019] Figure 2 A schematic diagram of another beam path provided for one or more embodiments of the present application;

[0020] Figure 3 A schematic diagram of a semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application;

[0021] Figure 4A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application;

[0022] Figure 5 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application;

[0023] Figure 6 A schematic diagram of a temperature distribution curve provided for one or more embodiments of the present application;

[0024] Figure 7 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application;

[0025] Figure 8 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application;

[0026] Figure 9 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application;

[0027] Figure 10 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application;

[0028] Figure 11 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application;

[0029] Figure 12 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application;

[0030] Figure 13 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application;

[0031] Figure 14 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application;

[0032] Figure 15 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application;

[0033] Figure 16 A schematic diagram of a copper electroplating structure provided for one or more embodiments of the present application;

[0034] Figure 17 A schematic diagram of another electroplating layer structure provided for one or more embodiments of the present application;

[0035] Figure 18A schematic diagram of another electroplating layer structure provided for one or more embodiments of the present application;

[0036] Figure 19 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application;

[0037] Figure 20 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application;

[0038] Figure 21 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application;

[0039] Figure 22 A schematic diagram of the structure of a laser projection device provided in one or more embodiments of the present application. DETAILED DESCRIPTION

[0040] In order to make the purpose and implementation of this application clearer, the exemplary implementation of this application will be clearly and completely described below in conjunction with the drawings in the exemplary embodiments of this application. Obviously, the described exemplary embodiments are only part of the embodiments of this application, not all of the embodiments.

[0041] It should be noted that the brief descriptions of terms in this application are only for the purpose of facilitating the understanding of the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise specified, these terms should be understood according to their ordinary and usual meanings.

[0042] In the specification and claims of this application and the accompanying drawings, the terms "first," "second," "third," etc. are used to distinguish similar or similar objects or entities, and are not necessarily intended to limit a particular order or sequence, unless otherwise noted. It should be understood that the terms used in this manner are interchangeable under appropriate circumstances.

[0043] The terms "comprise," "comprises," and "having," and any variations thereof, are intended to cover but not exclude inclusion; for example, a product or device comprising a list of components is not necessarily limited to all the components expressly listed but may include other components not expressly listed or inherent to such product or device.

[0044] Wide stripe high-power laser diodes (WS-HPLDs) are widely used in various fields due to their advantages, including wide output band coverage, high output power, compact size, and long life. As their application areas continue to expand, higher requirements are placed on their output power and electro-optical conversion efficiency. Currently, the output power of a single wide stripe semiconductor laser has reached tens of watts. Furthermore, certain fields also require WS-HPLDs to simultaneously achieve high brightness output, such as fiber coupling, laser projection, optical communications, laser medical treatment, and scientific research.

[0045] During the operation of a semiconductor laser, as the injection current increases, the probability of non-radiative recombination of carriers in the active region of the semiconductor laser increases, thereby increasing the thermal power of the semiconductor laser. If there is no temperature change inside the chip, the light beams are all parallel light, such as Figure 1 As shown, Figure 1 A schematic diagram of a beam path provided for one or more embodiments of the present application. If the local temperature changes, with a high center temperature and a low edge temperature, the refractive index distribution of the semiconductor laser waveguide material will change, as shown in formula (1):

[0046]

[0047] In formula (1), Δn represents the change in the refractive index of the material. Indicates the coefficient of change of the material's refractive index with temperature, ΔT indicates the temperature change, α fc Represents the refractive index-carrier concentration relationship coefficient, ΔN fc is the change in carrier concentration.

[0048] When the light beam passes through this position, it will be refracted to varying degrees, similar to the convergence or divergence effect produced by an optical lens, that is, the thermal lens effect, which will increase its divergence angle and reduce the quality of the light beam. Figure 2 As shown, Figure 2 Another schematic diagram of a light beam path is provided for one or more embodiments of the present application.

[0049] In order to solve the above technical problems, the present invention provides a semiconductor laser. Figures 3 to 5 A schematic diagram of a semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application includes a first electrode 101, an N-type substrate 102, an N-type buffer layer 103, an N-type confinement layer 104, an N-type waveguide layer 105, an active layer 106, a P-type waveguide layer 107, a P-type confinement layer 108, an ohmic contact layer 109, an insulating layer 110, and a second electrode 201, which are arranged in sequence.

[0050] The side of the first electrode 101 away from the N-type substrate 102 and / or the side of the second electrode 201 away from the ohmic contact layer 109 further includes a heat distribution structure 202 .

[0051] Along a first direction F1, the semiconductor laser includes an injection region S1 and a non-injection region S2. The insulating layer 110 blocks current, forming the non-injection region S2. The heat dissipation structure 202 within the non-injection region S2 includes alternating first portions 301 and second portions 302. The first direction F1 is parallel to the plane of the first electrode 101 or the second electrode 201.

[0052] The first portion 301 and the second portion 302 have different thermal conductivities.

[0053] See Figures 3 to 5 The first electrode 101 can be an N-side electrode, and the second electrode 201 can be a P-side electrode. In this embodiment of the present application, a heat spreader 202 can be provided on the side of the first electrode 101 away from the N-type substrate 102, or on the side of the second electrode 201 away from the ohmic contact layer 109. Furthermore, in addition to providing the heat spreader 202 on the side of the first electrode 101 away from the N-type substrate 102, a heat spreader 202 can also be provided on the side of the second electrode 201 away from the ohmic contact layer 109. In some schemes, the distance between the active layer 106 and the second electrode 201 is closer. Therefore, in the embodiment of the present application, a heat dissipation structure 202 is preferably set on the side of the second electrode 201 away from the ohmic contact layer 109. For the sake of simplicity of description, in the subsequent drawings of other embodiments, only the heat dissipation structure 202 is set on the side of the second electrode 201 away from the ohmic contact layer 109 for example, and all possibilities are no longer described one by one. In addition, for the convenience of illustration in the embodiment of the present application, the thickness ratio of the epitaxial layer structure is not illustrated. The thickness ratio between some epitaxial layer structures may be distorted, but it can be explained through textual description in the example of the present application.

[0054] The heat-dissipating structure 202 in the embodiment of the present application is used to control the temperature of the semiconductor laser and improve the temperature uniformity at different locations. Figure 3 For example, the thermal conductivity of the first part 301 and the thermal conductivity of the second part 302 can be one high and one low. The first part 301 with high thermal conductivity is used to transfer heat and enhance the heat dissipation effect of the semiconductor laser, and the second part 302 with low thermal conductivity is used to improve the thermal lens effect and enhance the beam quality of the semiconductor laser.

[0055] Continue reading Figure 3 In some embodiments, the heat dissipation structure 202 located in the implantation region S1 includes a first portion 301 .

[0056] The thermal conductivity of the first portion 301 is greater than the thermal conductivity of the second portion 302 .

[0057] The material of the first portion 301 includes at least one of diamond, silver, copper, gold, boron phosphide, beryllium oxide, aluminum nitride, silicon carbide, and aluminum. The material of the second portion 302 includes at least one of air, silicon dioxide, aluminum oxide, and titanium.

[0058] In the embodiment of the present application, the heat-distributing structure 202 located in the injection region S1 may adopt a first portion 301 with higher thermal conductivity. Thus, the heat generated by the semiconductor laser during operation may be quickly conducted through the first portion 301 to a heat sink connected to the semiconductor laser, thereby reducing the temperature of the injection region S1.

[0059] This embodiment of the present application uses copper as the first portion 301 and air as the second portion 302. The inventors compared the heat flow and temperature distribution of a conventional electrode structure COS package (NAS-LD) with a semiconductor laser width of 500μm and an active region strip width of 100μm, a base heat sink COS package (THS-LD), and a micro-thermal channel electrode structure COS package (MCAS-LD) provided in this embodiment. The laser thermal power was 10W.

[0060] The test results show that:

[0061] In the COS packaging structure with common electrode structure, heat distribution is transmitted in the active area and on both sides. The internal temperature distribution is high in the center and low on both sides, resulting in uneven temperature distribution, which in turn causes uneven refractive index distribution, forming a thermal lens effect and affecting the beam quality of the laser.

[0062] The base heat sink structure COS packaging structure is conducive to uniform temperature distribution inside the laser and suppresses the thermal lens effect, but the overall temperature of the laser increases, which is not conducive to long-term operation of the laser and reduces reliability; and the heat dissipation cost will also increase in order to dissipate heat.

[0063] The structure adopted in the embodiment of the present application can maintain a relatively uniform temperature distribution in the active area of ​​the chip, thereby reducing the overall temperature of the chip and improving the life and reliability of the laser.

[0064] By providing a high thermal conductivity material in the injection region S1, the temperature of the active region is quickly transferred to the heat sink. The non-injection region S2 is provided with a periodically distributed first portion 301 and a second portion 302, which simultaneously transfers and blocks the heat generated by the current non-injection regions S2 on both sides. On the one hand, heat accumulation is formed on both sides of the active region of the semiconductor laser, making the temperature distribution more uniform, thereby suppressing the thermal lens effect of the semiconductor laser and improving the beam quality of the semiconductor laser; on the other hand, the overall temperature of the laser is reduced, thereby improving the performance and reliability of the laser.

[0065] Figure 6 A schematic diagram of a temperature distribution curve provided for one or more embodiments of the present application. Figure 6 As shown, the maximum temperature difference between the center and edge of the NAS-LD active region is 62.3°C and 1.8°C, respectively. The maximum temperature difference between the center and edge of the THS-LD active region is 68.2°C and 0.57°C, respectively. The maximum temperature difference between the center and edge of the active region of the semiconductor laser epitaxial layer structure MCAS-LD provided in the embodiment of the present application is 64.5°C and 1.1°C, respectively. The edge temperatures of the NAS-LD, THS-LD, and MCAS-LD are 43.75°C, 67.42°C, and 44.6°C, respectively.

[0066] from Figure 6 Comparative data shows that the embodiment of the present application improves temperature distribution uniformity by 39% compared to NAS-LD. Compared to THS-LD, the edge temperature of the semiconductor laser drops by 22.82°C, and the temperature of the non-injection region S2 is essentially the same as that of NAS-LD, significantly reducing the temperature of the semiconductor laser. This reduces heat dissipation pressure, which is beneficial for improving the output performance and reliability of the semiconductor laser and reducing heat dissipation costs.

[0067] As can be seen from formula (1), improving the uniformity of temperature distribution can reduce the refractive index change caused by temperature change, improve the thermal lens focal length, and thus reduce the slow axis divergence angle of the laser, thereby improving the beam quality. According to the experimental results, through theoretical calculations, the equivalent thermal lens focal length of NAS-LD is about 242.5μm, the slow axis divergence angle is about 11.65°, the equivalent thermal lens focal length of THS-LD is about 560.2μm, and the slow axis divergence angle is only 5.1°. The equivalent thermal lens focal length corresponding to the embodiment of the present application is about 419.26μm, and the slow axis divergence angle is only 6.86°, an improvement of about 41.1%.

[0068] Therefore, the embodiments of the present application can suppress the thermal lens effect, reduce the slow-axis far-field divergence angle and improve the output beam quality while reducing the overall temperature of the laser. The semiconductor laser provided by the embodiments of the present application has higher reliability and heat dissipation performance, which is conducive to broadening its application field.

[0069] Continue reading Figure 3 In some embodiments, the heat dissipation structure 202 in the non-implantation region S2 adjacent to the implantation region S1 includes a second portion 302 . Figure 3 Specifically shown as A2, the heat dissipation structure 202 in the non-injection area S2, which is the largest distance from the injection area S1, includes a first portion 301, Figure 3Specifically indicated as A1 in FIG. Setting the heat-dissipating structure 202 adjacent to the injection region S1 as the second portion 302 with low thermal conductivity is beneficial for reducing the temperature difference near the injection region S1 and improving the thermal lens effect. Setting the heat-dissipating structure 202 in the non-injection region S2 farthest from the injection region S1 as the first portion 301 with high thermal conductivity is beneficial for improving the heat dissipation characteristics of the semiconductor laser edge and enhancing the reliability of the semiconductor laser.

[0070] Figure 7 A schematic diagram of another semiconductor laser epitaxial layer structure provided in one or more embodiments of the present application. In some other embodiments, the heat dissipation structure 202 adjacent to the injection region S1 may be configured as a first portion 301 with high thermal conductivity, and the heat dissipation structure 202 in the non-injection region S2 farthest from the injection region S1 may be configured as a second portion 302 with low thermal conductivity.

[0071] Figure 8 Another schematic diagram of a semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application. In some embodiments, along the first direction F1, the ratio of the width of the second portion 302 within the non-injection region S2 to the width of the first portion 301 can be greater than or equal to one-quarter, or less than or equal to one-half.

[0072] The number of the first portions 301 in a single non-implantation region S2 may be greater than or equal to 1, or less than or equal to 10.

[0073] The number of the second portions 302 in a single non-implantation region S2 may be greater than or equal to 1, or less than or equal to 10.

[0074] Figure 8 In the figure, the width of the first part 301 is indicated as L1, and the width of the second part 302 is indicated as L2. After research, it was found that if the ratio of the width of the second part 302 to the width of the first part 301 is too large, it may lead to poor heat dissipation effect of the semiconductor laser. If the ratio of the width of the second part 302 to the width of the first part 301 is too small, it may cause the temperature uniformity of the semiconductor laser to decrease. In the embodiment of the present application, the ratio of the width of the second part 302 to the width of the first part 301 can preferably be set to be greater than or equal to one-fourth, or the ratio of the width of the second part 302 to the width of the first part 301 can be set to be less than or equal to one-half. In this way, better heat dissipation effect can be achieved and the thermal lens effect can be better alleviated.

[0075] Figure 8In the embodiment, a non-injection region S2 is provided on both sides of the injection region S1. For each non-injection region S2, if the number of first portions 301 and second portions 302 is too large, the manufacturing difficulty is relatively large. Therefore, in the embodiment of the present application, the number of first portions 301 in a single non-injection region S2 can be greater than or equal to 1, or less than or equal to 10, and the number of second portions 302 in a single non-injection region S2 can be greater than or equal to 1, or less than or equal to 10. In this way, the purpose of suppressing the thermal lens effect can be achieved while reducing the manufacturing difficulty.

[0076] Figure 9 Another schematic diagram of a semiconductor laser epitaxial layer structure provided in one or more embodiments of the present application: In some embodiments, along the first direction F1, the widths of any two adjacent first portions 301 and / or any two adjacent second portions 302 in the non-injection region S2 are different.

[0077] During the operation of a semiconductor laser, the temperature of the injection region S1 is generally the highest. The temperature gradually decreases in the direction toward the non-injection region S2 and away from the injection region S1. The temperature at different locations is not the same, and the requirements for heat distribution and heat dissipation are also different.

[0078] In the embodiment of the present application, the first portion 301 and the second portion 302 of different widths are arranged at different positions to respectively control the temperature and dissipate heat for the semiconductor laser, so that the temperature and temperature uniformity of the semiconductor laser are better.

[0079] Continue reading Figure 9 In some embodiments, along the first direction F1 , the width of the first portion 301 and / or the second portion 302 increases as the portion is further away from the implantation region S1 .

[0080] Figure 9 L3, L4, L5, L6, L7, L8, L9, and L10 are schematically shown, where L3 < L5 < L7 < L9, L4 < L6 < L8 < L10. Alternatively, L3 ≥ 2 × L4, L5 ≥ 2 × L6, L7 ≥ 2 × L8, and L9 ≥ 2 × L10 can be achieved. The first portion 301 and the second portion 302, located near the injection region S1, have smaller widths, facilitating temperature control in the active region. The first portion 301 and the second portion 302, located away from the injection region S1, have larger widths, facilitating heat dissipation from the semiconductor laser and reducing the overall temperature of the semiconductor laser.

[0081] Figure 10 Another schematic diagram of a semiconductor laser epitaxial layer structure provided in one or more embodiments of the present application: In some embodiments, along the first direction F1, any two adjacent first portions 301 and / or any two adjacent second portions 302 in the non-injection region S2 have different thicknesses.

[0082] The embodiment of the present application can also set the first part 301 and the second part 302 of different thicknesses based on the different temperatures at different positions during the operation of the semiconductor laser to respectively regulate the temperature and dissipate heat for the semiconductor laser, so that the temperature and temperature uniformity of the semiconductor laser can achieve better results.

[0083] Continue reading Figure 10 In some embodiments, along the first direction F1 , the farther away from the implantation region S1 , the greater the thickness of the first portion 301 and / or the second portion 302 .

[0084] Figure 10 H1, H2, H3, and H4 are schematically shown in the figure. The second portion 302 has the same thickness as one of its adjacent first portions 301 and is therefore not further illustrated. H1 < H2 < H3 < H4 can be achieved. The first and second portions 301 and 302 located near the injection region S1 have smaller thicknesses, facilitating temperature control of the injection region S1. The first and second portions 301 and 302 located farther from the injection region S1 have larger thicknesses, facilitating heat dissipation from the semiconductor laser and reducing its overall temperature.

[0085] Figure 11 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application.

[0086] like Figure 11 As shown, the embodiment of the present application can also be combined with Figure 9 and Figure 10 , based on the fact that the width of the first portion 301 and / or the second portion 302 is larger as it is further away from the injection region S1 along the first direction F1, the thickness of the first portion 301 and / or the second portion 302 is larger as it is further away from the injection region S1. The technical effect achieved is similar to Figure 9 and Figure 10 Similar, no further description is given here.

[0087] The present application also provides a method for preparing a semiconductor laser, which is used to prepare the semiconductor laser according to any one of the above semiconductor laser embodiments; the method comprises:

[0088] A semiconductor structure is provided; wherein the semiconductor structure includes a first electrode 101, an N-type substrate 102, an N-type buffer layer 103, an N-type confinement layer 104, an N-type waveguide layer 105, an active layer 106, a P-type waveguide layer 107, a P-type confinement layer 108, an ohmic contact layer 109, an insulating layer 110 and a second electrode 201, which are arranged in sequence.

[0089] For the sake of brevity, the present embodiment will not describe in detail all the processes of preparing the semiconductor laser. The method for preparing the semiconductor laser provided in the present embodiment can be prepared based on a semiconductor structure including a first electrode 101, an N-type substrate 102, an N-type buffer layer 103, an N-type confinement layer 104, an N-type waveguide layer 105, an active layer 106, a P-type waveguide layer 107, a P-type confinement layer 108, an ohmic contact layer 109, an insulating layer 110, and a second electrode 201. Figure 12 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application.

[0090] A photoresist layer 401 is formed on a side of the first electrode 101 away from the N-type substrate 102 and / or a side of the second electrode 201 away from the ohmic contact layer 109 .

[0091] For the sake of simplicity, in the embodiment of the present application, only the heat dissipation structure 202 is provided on the side of the second electrode 201 away from the ohmic contact layer 109 for example. Figure 13 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application.

[0092] A photoresist layer 401 having patterns corresponding to the first portion 301 and the second portion 302 is prepared based on the photoresist layer 401. Figure 14 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application.

[0093] A heat-saturating layer 402 is prepared on the surface of the photoresist layer 401 .

[0094] The embodiment of the present application adopts the method of electroplating copper to prepare the heat-dissipating layer 402. The active area of ​​the semiconductor laser is closer to the second electrode 201. Setting it on the surface of the second electrode 201 is more conducive to heat conduction and internal temperature control. The high thermal conductivity electrode structure of the copper material is set. On the basis of improving temperature control, it can reduce the stress problem caused by high-temperature eutectic during packaging and improve the reliability of the packaged device. Moreover, when performing patch packaging, the electrode structure does not require the active area position of the semiconductor laser to be precisely mounted on the base heat sink, so that patch packaging can be achieved, which greatly reduces the difficulty and complexity of the process. In addition, compared with the method of evaporating the gold layer [thermal conductivity 318W / (m·K)], the thermal conductivity of electroplated copper [thermal conductivity 401W / (m·K)] is better, and the material cost and preparation method are simpler, the process complexity is low, and it is conducive to mass production. In addition to the method of electroplating copper, the embodiment of the present application can also use chemical vapor deposition (CVD) or magnetron sputtering (PVD) equipment to prepare the first part 301.

[0095] Specifically, the embodiment of the present application can prepare the copper electroplating solution and Figure 14The semiconductor laser epitaxial layer structure is placed in an electrolyte using a specialized fixture, and copper electroplating is performed on its surface. After forming a heat-sinking layer 402 on the surface of the photoresist, since the photoresist layer 401 includes a pattern of first portion 301 and second portion 302, a portion of the second electrode 201 is exposed to air. Therefore, the heat-sinking layer 402 is located both on the surface of the second electrode 201 and above the photoresist layer 401. Figure 15 A schematic diagram of another semiconductor laser epitaxial layer structure provided for one or more embodiments of the present application.

[0096] In order to obtain a high-quality electroplated layer (heat-saturation layer 402) with low surface roughness, good flatness, good density, the electrolysis temperature can be greater than or equal to 20°C, or less than or equal to 30°C; the current density can be greater than or equal to 27mA / cm 2 , or less than or equal to 35mA / cm 2 The thickness of the copper layer can be greater than or equal to 5μm, or less than or equal to 35μm; the electroplating time can be greater than or equal to 8min, or less than or equal to 20min; the electrolyte needs to be stirred during the copper electroplating process to obtain a more uniform electroplated layer. Figure 16 This is a schematic diagram of a copper electroplating structure provided by one or more embodiments of the present application. If the current density is low, the electroplating rate on the second electrode 201 surface is fast, and the electroplating rate on the photoresist layer 401 surface is slow, resulting in a shape where the second electrode 201 surface is high and the photoresist surface is low, and the plated surface is relatively rough. Figure 17 Another schematic diagram of an electroplating layer structure provided for one or more embodiments of the present application. If the current density is large, lateral electroplating will occur on the surface of the photoresist layer 401, widening the width of the second electrode 201 and affecting the device improvement effect. Figure 18 A schematic diagram of another electroplating layer structure provided for one or more embodiments of the present application.

[0097] Copper electroplating solution ratio scheme:

[0098] Copper sulfate pentahydrate (CuSO4·5H2O): The concentration can be greater than or equal to 55g / L, or less than or equal to 80g / L; the role of copper sulfate pentahydrate is to provide Cu 2+ And enhance electrical conductivity.

[0099] Sulfuric acid (H2SO4): The concentration can be greater than or equal to 170g / L and less than or equal to 240g / L; the function of sulfuric acid is to improve the conductivity and electroplating uniformity.

[0100] Chloride ion (CI - ): The concentration can be greater than or equal to 25ppm, or less than or equal to 80ppm; the role of chloride ions is to help the anode dissolve and promote the precipitation and crystallization of copper.

[0101] Leveling agent: The concentration can be greater than or equal to 8ml / L. It can also be less than or equal to 27ml / L. The function of the leveling agent is to improve the flatness of the electroplating layer.

[0102] Brightener: The concentration can be greater than or equal to 0.1ml / L, or less than or equal to 0.52ml / L; the function of the brightener is to reduce the surface impedance of the electroplating layer and improve the crystallization quality and ductility of the electroplating layer.

[0103] Wetting agent: works synergistically with leveling agent and brightener.

[0104] Deionized water.

[0105] The photoresist layer 401 is removed, so that the heat-dissipating layer 402 forms a heat-dissipating structure 202 having a first portion 301 and a second portion 302 .

[0106] Figure 19 A schematic diagram of another semiconductor laser epitaxial layer structure provided in one or more embodiments of the present application. Figure 15 On the basis of the above, after the photoresist layer 401 is removed, the heat-sinking layer 402 attached to the surface of the photoresist layer 401 is removed along with the photoresist layer 401, while the heat-sinking layer 402 attached to the surface of the second electrode 201 remains on the surface of the second electrode 201. Thus, a heat-sinking structure 202 is formed with a first portion 301 formed of copper and a second portion 302 formed of air. The heat-sinking structure 202 can improve the temperature uniformity of the semiconductor laser, suppress the thermal lens effect, reduce the overall temperature of the semiconductor laser, and enhance the reliability of the semiconductor laser.

[0107] A surface layer 403 is prepared on the surface of the heat-saturating structure 202 . The material of the surface layer 403 is the same as that of the first electrode 101 and / or the second electrode 201 .

[0108] Figure 20 A schematic diagram of another semiconductor laser epitaxial layer structure provided in one or more embodiments of the present application is provided. Figure 21 A schematic diagram of another semiconductor laser epitaxial layer structure provided in one or more embodiments of the present application. Figure 20 As shown, in order to avoid the occurrence of welding gaps between the first part 301 and the solder during the packaging process of the semiconductor laser in the above embodiment, the inventors can also use magnetron sputtering to sputter a surface layer 403 of Ti / Au material on the surface of the first part 301 after preparing the heat-saturating structure 202. The thickness of Ti can be greater than or equal to 20nm, or less than or equal to 32nm, and the thickness of Au can be greater than or equal to 120nm, or less than or equal to 170nm, thereby improving the problem of welding gaps and enhancing the welding effect. Figure 20 and Figure 21In the embodiment of the present application, the surface layer 403 may be provided only on the surface of the first portion 301 , or the surface layer 403 may be provided on the surfaces of both the first portion 301 and the second portion 302 .

[0109] Compared with conventional structure semiconductor lasers, the slow axis divergence angle of the semiconductor laser prepared by this method is reduced from 6° to 5.2° when the injection current is 2A, which greatly improves the thermal lens effect of the semiconductor laser and improves the beam quality of the semiconductor laser.

[0110] The embodiment of the present application also provides a laser projection device, Figure 22 A schematic diagram of the structure of a laser projection device provided in one or more embodiments of the present application is shown in FIG. Figure 22 As shown, the laser projection device includes a display control component 1, a light source driving component 2, a light source 3, a light valve 4 and a projection lens 5.

[0111] The display control component 1 is electrically connected to the light source driving component 2 and the light valve 4 , and the light source driving component 2 is electrically connected to the light source 3 .

[0112] The light source 3 includes at least one semiconductor laser among the above-mentioned semiconductor laser embodiments.

[0113] The laser projection device provided in the embodiment of the present application can achieve the same or at least similar technical effects as the above-mentioned semiconductor laser embodiment, and will not be repeated here.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

[0115] For ease of explanation, the above description has been presented in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Based on the above teachings, various modifications and variations are possible. The above embodiments have been selected and described to better explain the principles and practical applications, thereby enabling those skilled in the art to better utilize the embodiments and various different variations of the embodiments suitable for specific use considerations.

Claims

1. A semiconductor laser, characterized in that The device comprises a first electrode, an N-type substrate, an N-type buffer layer, an N-type confinement layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, a P-type confinement layer, an ohmic contact layer, an insulating layer, and a second electrode, which are sequentially arranged; The side of the first electrode away from the N-type substrate and / or the side of the second electrode away from the ohmic contact layer further includes a heat distribution structure; Along a first direction, the semiconductor laser includes an injection region and a non-injection region, and the heat-dissipating structure located in the non-injection region includes a first portion and a second portion that are alternately arranged; the first direction is parallel to a plane where the first electrode or the second electrode is located; The first portion and the second portion have different thermal conductivities.

2. The semiconductor laser according to claim 1, wherein The heat dissipation structure located in the injection area includes the first portion; The thermal conductivity of the first portion is greater than the thermal conductivity of the second portion; The material of the first part includes at least one of diamond, silver, copper, gold, boron phosphide, beryllium oxide, aluminum nitride, silicon carbide and aluminum, and the material of the second part includes at least one of air, silicon dioxide, aluminum oxide and titanium.

3. The semiconductor laser according to claim 1, wherein The heat dissipation structure in the non-injection region adjacent to the injection region includes the second portion, and the heat dissipation structure in the non-injection region that is the farthest away from the injection region includes the first portion.

4. The semiconductor laser according to claim 1, wherein Along the first direction, a ratio of a width of the second portion in the non-implantation region to a width of the first portion is greater than or equal to one quarter and / or less than or equal to one half; The number of the first parts in a single non-implantation region is greater than or equal to 1 and / or less than or equal to 10; The number of the second parts in a single non-implantation region is greater than or equal to 1 and / or less than or equal to 10.

5. The semiconductor laser according to claim 1, wherein Along the first direction, widths of any two adjacent first portions and / or any two adjacent second portions in the non-implantation region are different.

6. The semiconductor laser according to claim 5, characterized in that Along the first direction, the farther away from the implantation region the first portion and / or the second portion are, the larger the width is.

7. The semiconductor laser according to claim 1, wherein Along the first direction, thicknesses of any two adjacent first portions and / or any two adjacent second portions in the non-implantation region are different.

8. The semiconductor laser according to claim 7, wherein: Along the first direction, the farther away from the implantation region, the greater the thickness of the first portion and / or the second portion.

9. A method for preparing a semiconductor laser, characterized in that: The method is used to prepare the semiconductor laser according to any one of claims 1 to 8; the method comprises: A semiconductor structure is provided; wherein the semiconductor structure includes the first electrode, the N-type substrate, the N-type buffer layer, the N-type confinement layer, the N-type waveguide layer, the active layer, the P-type waveguide layer, the P-type confinement layer, the ohmic contact layer, the insulating layer, and the second electrode, which are arranged in sequence; preparing a photoresist layer on a side of the first electrode away from the N-type substrate and / or a side of the second electrode away from the ohmic contact layer; preparing the photoresist layer having patterns corresponding to the first portion and the second portion based on the photoresist layer; preparing a heat-saturating layer on the surface of the photoresist layer; The photoresist layer is removed, so that the heat-dissipating layer forms the heat-dissipating structure having the first portion and the second portion.

10. A laser projection device, characterized in that: The laser projection device includes a display control component, a light source driving component, a light source, a light valve and a projection lens; The display control component is electrically connected to the light source driving component and the light valve respectively, and the light source driving component is electrically connected to the light source; The light source comprises at least one semiconductor laser according to any one of claims 1 to 8.

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