Bar chip heat dissipation structure in semiconductor laser

Abstract

The invention provides a heat dissipation structure for a bar chip in a semiconductor laser, which can improve the heat dissipation capability of the semiconductor laser, ensure the working reliability of the laser and prolong the service life of the laser. The solar cell sequentially comprises a positive plate, a first waveguide layer, a first light limiting layer, an active layer, a second waveguide layer, a second light limiting layer, a substrate layer and a negative plate from top to bottom, wherein the outer surfaces of the positive plate and the negative plate are respectively connected with a secondary heat sink; the sum of the thicknesses formed by the first waveguide layer, the first light limiting layer, the active layer, the second waveguide layer and the second light limiting layer is smaller than the thickness of the substrate layer, and the thickness of the substrate layer is 40-110 microns; and a graphene film layer is deposited on the negative electrode surface of the substrate layer.

Description

Technical Field

[0001] The invention relates to the technical field of lasers, in particular to a heat dissipation structure of a bar chip in a semiconductor laser. Background Art

[0002] With the rapid development of the semiconductor laser industry, the industry's demand for high-power output of semiconductor lasers is increasing. Semiconductor lasers are electrically pumped lasers. In the active region, the carriers provided by external electrical injection recombine and generate coherent light radiation, oscillating the gain between the resonant cavity formed by the front and rear ends of the bar chip, and finally lasing output from the front cavity surface, that is, emitting lasers. However, the electrical energy provided by external electrical injection cannot be completely converted into light energy output, and the remaining energy will be completely converted into heat, that is, the effects of non-radiative recombination of carriers in the active region, carrier absorption, and light absorption in the waveguide layer will generate waste heat. Under electrical load, the various layers of materials outside the active region will also generate ohmic heat, among which the heat generation near the active region is dominant; during the working process, the generation and accumulation of these waste heat will produce multiple negative effects such as red shift of the output wavelength, widening of the full width at half maximum of the output waveform, and decrease in electro-optical conversion efficiency, thereby hindering the long-term stable operation of the semiconductor laser and even causing the laser to fail quickly. Therefore, the heat dissipation capacity of the semiconductor laser is an important factor restricting the output power.

[0003] At present, the packaging form of semiconductor lasers is as follows: the positive side (upper electrode) and the negative side (back electrode) of the bar chip are respectively connected and fixed to the secondary heat sink by welding. The secondary heat sink is made of materials with high thermal conductivity and electrical conductivity. While realizing circuit conduction, it also completes the extraction of the working waste heat of the bar chip. The thermal conductivity of the bar chip itself is significantly lower than the secondary heat sink. Therefore, the shorter the distance between the active layer (close to the positive side of the bar chip) and the secondary heat sinks on both sides of the bar chip, the easier it is to conduct the working waste heat generated by the active layer to the secondary heat sink. However, the thickness of the substrate layer between the active layer and the negative side of the bar chip of the conventional bar chip is relatively large, that is, the distance between the active layer and the negative side is relatively large, which makes it difficult for the working waste heat generated by the active layer to be conducted to the secondary heat sink on the negative side, that is, only the heat dissipation of the active layer on the positive side is realized, and the heat dissipation capacity of the secondary heat sink on the negative side cannot be fully utilized, which not only causes a waste of heat dissipation resources and space resources, but also may make the overall heat dissipation capacity of the semiconductor laser insufficient, ultimately affecting the normal operation of the semiconductor laser, and may even cause a decrease in the reliability of the laser and a shortened working life. Summary of the invention

[0004] In view of the above problems, the present invention provides a heat dissipation structure of a bar chip in a semiconductor laser, which can improve the heat dissipation capacity of the semiconductor laser, ensure the working reliability of the laser and extend the working life.

[0005] The present invention adopts the following technical scheme: a heat dissipation structure of a bar chip in a semiconductor laser, which includes, from top to bottom, a positive electrode sheet, a first waveguide layer, a first light confinement layer, an active layer, a second waveguide layer, a second light confinement layer, a substrate layer, and a negative electrode sheet, wherein the outer surfaces of the positive electrode sheet and the negative electrode sheet are respectively connected to a secondary heat sink; the total thickness formed by the first waveguide layer, the first light confinement layer, the active layer, the second waveguide layer, and the second light confinement layer is less than the thickness of the substrate layer, and the thickness of the substrate layer is 40 μm to 110 μm; a graphene film layer is deposited on the negative electrode surface of the substrate layer.

[0006] Furthermore, the material of the substrate layer is GaAs;

[0007] Furthermore, the first waveguide layer is a ridge waveguide, and the positive electrode sheet covers the ridge surface of the first waveguide layer;

[0008] Furthermore, the thickness of the active layer is 0.1 μm to 0.3 μm;

[0009] Furthermore, the thickness of the graphene film layer is 10nm to 12nm;

[0010] Furthermore, the material of the substrate layer is Si or SiO2;

[0011] Furthermore, the surface of the positive electrode sheet correspondingly contacting the first waveguide layer is serrated; and the surface of the negative electrode sheet correspondingly contacting the substrate layer is serrated.

[0012] The beneficial effect of the present invention is that, due to the thickness of the substrate layer and the deposition of a graphene film layer on the negative electrode surface of the substrate layer, the efficiency of heat conduction from the active layer in the bar chip to the negative electrode side can be improved while ensuring the structural strength and conductive properties, thereby improving the overall heat dissipation capacity of the semiconductor laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the structure of the present invention;

[0014] Figure 2 1 is a graph showing the maximum temperature of the laser changing with the thickness of the substrate layer in an embodiment of the present invention. DETAILED DESCRIPTION

[0015] like Figure 1As shown, a heat dissipation structure of a bar chip in a semiconductor laser of the present invention comprises, from top to bottom, a positive electrode sheet 1, a first waveguide layer 2, a first light confinement layer 3, an active layer 4, a second waveguide layer 5, a second light confinement layer 6, a substrate layer 7, and a negative electrode sheet 8. The outer surfaces of the positive electrode sheet 1 and the negative electrode sheet 8 are respectively connected to a secondary heat sink (not shown in the figure) by welding; the material of the substrate layer 7 is GaAs; the first waveguide layer 2 is a ridge waveguide, and the positive electrode sheet 1 is covered on the ridge surface of the first waveguide layer 2;

[0016] The total thickness formed by the first waveguide layer 2, the first light confinement layer 3, the active layer 4, the second waveguide layer 5, and the second light confinement layer 6 is less than the thickness of the substrate layer 7. The substrate layer 7 is subjected to a grinding and sectioning process so that the thickness of the substrate layer 7 is 40 μm to 110 μm. A graphene film layer 9 is deposited on the negative electrode surface of the substrate layer 7 by an epitaxial growth method, so that the graphene film layer 9 is well combined with the negative electrode surface of the substrate layer 7. Graphene is an allotrope of carbon. As a new type of material with excellent properties, it is increasingly being used in the preparation and packaging of electronic devices. The graphene film has the excellent properties of high strength, high electrical conductivity and high thermal conductivity. At the same time, since the thermal conductivity of the graphene material has anisotropic characteristics, its thermal conductivity is extremely high in the direction parallel to the film and low in the vertical direction. Therefore, based on this characteristic, the present invention prepares the graphene film layer 9 on the negative electrode surface of the substrate layer 7, which can achieve efficient heat conduction and heat distribution of the bar chip.

[0017] The thickness of the active layer 4 is 0.1 μm to 0.3 μm; the thickness of the graphene film layer 9 is 10 nm to 12 nm; and the material of the substrate layer 7 is Si or SiO2.

[0018] The surface of the positive electrode sheet 1 corresponding to the first waveguide layer 2 is serrated, and the surface of the negative electrode sheet 8 corresponding to the substrate layer 7 is serrated, thereby improving the uniformity of current injection and avoiding the crowding effect of current injection.

[0019] like Figure 2As shown, the present invention uses finite element analysis software ANSYS Workbench to perform thermal simulation, and verifies the following conclusions: under different working conditions (working temperature, working current, duty cycle, etc.), there are differences in the heat dissipation capabilities of the bar chip and the semiconductor laser packaged therewith; generally, when the working temperature is the same, the higher the working current or duty cycle, the greater the difference in heat dissipation performance, and the difference in heat dissipation performance under CW (i.e., continuous wave laser) continuous working conditions is the largest. In order to maximize the improvement in heat dissipation performance brought about by thinning the substrate layer 7, the bar laser is set to work under CW conditions, and the bottom of the secondary heat sink is controlled to be constant at 25°C. When the thickness of the substrate layer 7 is 110μm, 100μm, 90μm, 80μm, 70μm, 60μm, 50μm and 40μm, respectively, through ANSYS Workbench to conduct thermal analysis, and the results are shown in the figure: when the thickness of the substrate layer 7 changes within the range of 40μm to 110μm, as the thickness of the substrate layer 7 decreases, the maximum temperature of the bar laser gradually decreases; and when the thickness of the substrate layer 7 is small, the rate of decrease of the maximum temperature gradually accelerates; the above results show that using the improved bar chip of the present invention to replace the conventional bar chip for semiconductor laser production can significantly improve the overall heat dissipation capacity of the semiconductor laser, reduce the temperature of the active area, and provide a strong guarantee for the long-term stable operation of the semiconductor laser;

[0020] In summary, when the thickness of the substrate layer 7 varies within the range of 40 μm to 110 μm, as the thickness of the substrate layer 7 decreases, the maximum operating temperature of the bar laser gradually decreases, which indicates that reducing the thickness of the substrate layer 7 of the bar chip can effectively improve the heat dissipation performance. The distance between the active layer 4 and the negative electrode sheet 8 of the improved bar chip is shortened. Therefore, after it is packaged into a semiconductor laser, the distance between the active layer 4 and the secondary heat sink on the side of the negative electrode sheet 8 is shortened. As the heat conduction distance is shortened, the heat transfer efficiency is improved; and because the graphene film layer 9 on the negative electrode surface of the substrate layer 7 has an extremely high thermal conductivity, the waste heat generated by the active layer 4 can be dissipated faster through the secondary heat sink, thereby making full use of the heat dissipation capacity of the secondary heat sink on the negative electrode side, thereby improving the heat dissipation capacity of the semiconductor laser, ensuring the working reliability of the laser and extending the working life.

[0021] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0022] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A heat dissipation structure of a semiconductor laser chip, characterized in that: The invention comprises, from top to bottom, a positive electrode sheet, a first waveguide layer, a first light confinement layer, an active layer, a second waveguide layer, a second light confinement layer, a substrate layer, and a negative electrode sheet, wherein the outer surfaces of the positive electrode sheet and the negative electrode sheet are respectively connected to the secondary heat sink; the total thickness formed by the first waveguide layer, the first light confinement layer, the active layer, the second waveguide layer, and the second light confinement layer is less than the thickness of the substrate layer, and the thickness of the substrate layer is 40 μm to 110 μm; and a graphene film layer is deposited on the negative electrode surface of the substrate layer.

2. The heat dissipation structure of a semiconductor laser chip according to claim 1, characterized in that: The material of the substrate layer is GaAs.

3. The heat dissipation structure of a semiconductor laser chip according to claim 1, characterized in that: The first waveguide layer is a ridge waveguide, and the positive electrode sheet covers the ridge surface of the first waveguide layer.

4. The heat dissipation structure of a semiconductor laser chip according to claim 1, characterized in that: The thickness of the active layer is 0.1 μm to 0.3 μm.

5. The heat dissipation structure of a semiconductor laser chip according to claim 1, characterized in that: The thickness of the graphene film layer is 10nm-12nm.

6. The heat dissipation structure of a semiconductor laser chip according to claim 1, characterized in that: The material of the substrate layer is Si or SiO2.

7. The heat dissipation structure of a semiconductor laser chip according to claim 1, characterized in that: The surface of the positive electrode sheet correspondingly contacting the first waveguide layer is serrated; the surface of the negative electrode sheet correspondingly contacting the substrate layer is serrated.

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