Semiconductor laser structure with cyclic strain buffer layer and P-type strain buffer layer

Abstract

The invention relates to the technical field of semiconductors, and particularly discloses a semiconductor laser structure with cyclic strain buffer layers and a P-type strain buffer layer, which comprises a contact layer, a P-surface limiting layer, the P-type strain buffer layer, a P-surface waveguide layer, an active layer, an N-surface waveguide layer, an N-surface limiting layer and a plurality of groups of cyclic strain buffer layers which are arranged in sequence, the material of the P-type strain buffer layer is AlaGa1-aInbP, and 0 lt; a < lt >; 1, 0lt; blt; 0.48, each group of cyclic strain buffer layers is provided with a strain layer and a buffer layer, the buffer layers are made of gallium arsenide, and the strain layers are made of Al < x > Ga < 1-x > In < y > P, xlt; 1, 0lt; yt; Yt; and 0.48, 3 to 50 groups of cyclic strain buffer layers are arranged. The laser epitaxial structure has the effect of improving the defect of serious warping caused by large pressure stress of the laser epitaxial structure.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular, to a semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer. Background Art

[0002] Most of the buffer layers of traditional high-power laser epitaxial structures are made of gallium arsenide materials. Except for the buffer layer, this structure is usually made of gallium aluminum arsenide materials with different aluminum contents. Although the lattice parameters of aluminum arsenide and gallium arsenide are very close, being 5.6691 Å and 5.6533 Å respectively, with a lattice mismatch of 1500 ppm, the total thickness of the aluminum-containing part of the entire laser epitaxial structure is between 4 - 10 μm, resulting in a relatively large accumulation of compressive stress.

[0003] After testing, for a 4-inch epitaxial wafer without thinning the substrate, the warpage reaches 20 μm; if the substrate is thinned to 150 μm, the warpage reaches about 260 μm. For a 6-inch epitaxial wafer, the warpage is 150 μm without thinning the substrate. If the substrate is thinned to 150 μm, the warpage is extremely severe, and it is very easy to fragment. Even if it does not fragment, cavity lines are likely to be generated during cleavage, resulting in the failure of cavity surface reliability. Summary of the Invention

[0004] In order to improve the defect that the compressive stress of the laser epitaxial structure is large, resulting in severe warpage, the present application provides a semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer.

[0005] The present application provides a semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer, adopting the following technical solution: A semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer includes a contact layer, a P-side confinement layer, a P-type strain buffer layer, a P-side waveguide layer, an active layer, an N-side waveguide layer, an N-side confinement layer, and several groups of cyclic strain buffer layers arranged in sequence. The material of the P-type strain buffer layer is Al a Ga 1-a In b P, where 0 < a < 1, 0 < b < 0.48. Each group of the cyclic strain buffer layers is provided with a strain layer and a buffer layer. The material of the buffer layer is gallium arsenide, and the material of the strain layer is Al x Ga 1-x In y P, where 0 < x < 1, 0 < y < 0.48. The cyclic strain buffer layers are provided with 3 - 50 groups.

[0006] By adopting the above technical solution, a number of cyclic strain buffer layers are set in the semiconductor laser structure, and the stress is adjusted by adjusting the proportion of indium components in the strain layer. When y=0.48, Al x Ga 1-x In y P is lattice matched with GaAs. When y < 0.48, Al x Ga 1-x In y The lattice of P is smaller than that of GaAs, and tensile stress is generated between the buffer layer and the strain layer. The tensile stress opposite to the compressive stress of the laser epitaxial structure is introduced into the structure, so that the stress of the entire epitaxial structure is balanced, the warping of the epitaxial wafer is reduced, the fragmentation rate is reduced, the cavity lines are cleaved, the yield is improved, and the defect of severe warping caused by large compressive stress of the laser epitaxial structure is improved; Compared with directly setting a strain layer and a buffer layer, setting a cyclic strain buffer layer can not only control the total stress of the structure, but also make each layer of GaAs and Al x Ga 1-x In y The thickness of P is reduced, thereby improving the interface quality between the strain layer and the buffer layer and enhancing the reliability of the entire semiconductor laser structure; The introduction of a P-type strain buffer layer into the structure not only balances the overall stress, but also controls the stress of the active layer, thereby controlling the quantum well recombination efficiency and improving the optical power. a Ga 1-a In b P has a high corrosion selectivity ratio to GaAsAl, and can be used as an corrosion stop layer to increase the reliability of the laser structure.

[0007] Optionally, the total thickness of the buffer layer is 200 nm.

[0008] Optionally, the epitaxial growth temperature of the strained layer is 600-750° C., the epitaxial growth pressure is 80-200 mbar, and the epitaxial growth of the strained layer adopts PH3 thermal decomposition, and the flow rate of PH3 is 300-2000 sccm.

[0009] Optionally, the epitaxial growth temperature of the P-type strain buffer layer is 600-750° C., the epitaxial growth pressure is 80-200 mbar, and the epitaxial growth of the P-type strain buffer layer adopts PH3 thermal decomposition, and the flow rate of PH3 is 300-2000 sccm.

[0010] Optionally, the materials of the N-side limiting layer and the N-side waveguide layer are both GaAs Al, and the N-side limiting layer and the N-side waveguide layer are doped with silicon, and the doping concentration of silicon is 5×10 16 -3×10 18 cm -3The epitaxial growth temperature of the N-side confinement layer and the N-side waveguide layer is 600-750° C., and the epitaxial growth pressure is 80-200 mbar.

[0011] Optionally, the epitaxial growth of the N-side confinement layer and the N-side waveguide layer is performed by thermal decomposition of AsH3, the flow rate of AsH3 is 300-2000 sccm, and the total thickness of the N-side confinement layer and the N-side waveguide layer is 1-5 μm.

[0012] Optionally, the material of the active layer is indium gallium aluminum, the epitaxial growth temperature of the active layer is 580-750° C., the epitaxial growth pressure is 80-200 mbar, and the thickness is 2-10 nm.

[0013] Optionally, the materials of the P-plane limiting layer and the P-plane waveguide layer are both gallium aluminum arsenide, and the P-plane limiting layer and the P-plane waveguide layer are doped with carbon, and the carbon doping concentration is 5×10 16 -3×10 18 cm -3 The epitaxial growth temperature of the P-face limiting layer and the P-face waveguide layer is 600-750° C., the epitaxial growth pressure is 80-200 mbar, and the total thickness of the P-face limiting layer and the P-face waveguide layer is 1-5 μm.

[0014] Optionally, the epitaxial growth of the P-face confinement layer and the P-face waveguide layer is performed by thermal decomposition of AsH3, and the flow rate of AsH3 is 300-2000sccm.

[0015] Optionally, the material of the contact layer is gallium arsenide phosphorus, and the contact layer is doped with carbon, and the carbon doping concentration is 5×10 19 -5×10 20 cm -3 The epitaxial growth temperature of the contact layer is 550-650° C., the epitaxial growth pressure is 80-200 mbar, and the thickness is 50-500 nm.

[0016] In summary, the present application includes at least one of the following beneficial technical effects: Several cyclic strain buffer layers are set in the semiconductor laser structure. The stress is adjusted by adjusting the proportion of indium components in the strain layer. When y=0.48, Al x Ga 1-x In y P is lattice matched with GaAs. When y < 0.48, Al x Ga 1- x In yThe lattice of P is smaller than that of GaAs, and tensile stress is generated between the buffer layer and the strain layer. The tensile stress opposite to the compressive stress of the laser epitaxial structure is introduced into the structure, so that the stress of the entire epitaxial structure is balanced, the warping of the epitaxial wafer is reduced, the fragmentation rate is reduced, the cavity lines are cleaved, the yield is improved, and the defect of severe warping caused by large compressive stress of the laser epitaxial structure is improved; Compared with directly setting a strain layer and a buffer layer, setting a cyclic strain buffer layer can not only control the total stress of the structure, but also make each layer of GaAs and Al x Ga 1-x In y The thickness of P is reduced, thereby improving the interface quality between the strain layer and the buffer layer and enhancing the reliability of the entire semiconductor laser structure; The introduction of a P-type strain buffer layer into the structure not only balances the overall stress, but also controls the stress of the active layer, thereby controlling the quantum well recombination efficiency and improving the optical power. a Ga 1-a In b P has a high corrosion selectivity ratio to GaAsAl, and can be used as an corrosion stop layer to increase the reliability of the laser structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of a semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer according to an embodiment of the present application.

[0018] Explanation of the accompanying drawings: 1. Contact layer; 2. P-side confinement layer; 3. P-type strain buffer layer; 4. P-side waveguide layer; 5. Active layer; 6. N-side waveguide layer; 7. N-side confinement layer; 8. Strain layer; 9. Buffer layer; 10. Substrate. DETAILED DESCRIPTION

[0019] The following is combined with Figure 1 This application is described in further detail.

[0020] Example

[0021] The embodiment of the present application discloses a semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer.

[0022] Example 1

[0023] Reference Figure 1 A semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer includes a contact layer 1, a P-face confinement layer 2, a P-type strain buffer layer 3, a P-face waveguide layer 4, an active layer 5, an N-face waveguide layer 6, an N-face confinement layer 7, a plurality of cyclic strain buffer layers and a substrate 10 which are arranged in sequence.

[0024] The material of the contact layer 1 is gallium arsenide phosphide, and the contact layer 1 is doped with carbon. The doping concentration of carbon is 5×10 19 -5×10 20 cm -3 , the epitaxial growth temperature is 550 - 650 °C, the epitaxial growth pressure is 80 - 200 mbar, and the thickness is 50 - 500 nm. In this embodiment, the doping concentration of carbon in the contact layer 1 is 5×10 20 cm -3 , the epitaxial growth temperature is 620 °C, the epitaxial growth pressure is 170 mbar, and the thickness is 200 nm.

[0025] The material of the P-side confinement layer 2 is aluminum gallium arsenide, and the P-side confinement layer 2 is fixedly connected to the contact layer 1. The P-side confinement layer 2 is doped with carbon. The doping concentration of carbon is 5×10 16 -3×10 18 cm -3 . The epitaxial growth of the P-side confinement layer 2 uses AsH3 thermal decomposition, and the flow rate of AsH3 is 300 - 2000 sccm. The epitaxial growth temperature of the P-side confinement layer 2 is 600 - 750 °C, and the epitaxial growth pressure is 80 - 200 mbar. In this embodiment, the material of the P-side confinement layer 2 is Al 0.2 GaAs. The doping concentration of carbon in the P-side confinement layer 2 is 3×10 18 cm -3 , the flow rate of AsH3 is 2000 sccm, the epitaxial growth temperature is 660 °C, the epitaxial growth pressure is 175 mbar, and the thickness is 500 nm.

[0026] The material of the P-type strain buffer layer 3 is Al a Ga 1-a In b P, where 0 < a < 1 and 0 < b < 0.48. The P-type strain buffer layer 3 is fixedly connected to the P-side confinement layer 2. The epitaxial growth of the P-type strain buffer layer 3 uses PH3 thermal decomposition, and the flow rate of PH3 is 300 - 2000 sccm. The epitaxial growth temperature of the P-type strain buffer layer 3 is 600 - 750 °C, and the epitaxial growth pressure is 80 - 200 mbar. In this embodiment, the material of the P-type strain buffer layer 3 is Al 0.3 Ga 0.7 In 0.3 P, the flow rate of PH3 is 1500 sccm. The epitaxial growth temperature of the P-type strain buffer layer 3 is 700 °C, the epitaxial growth pressure is 180 mbar, and the thickness is 50 nm.

[0027] The material of the P-side waveguide layer 4 is aluminum gallium arsenide, and the P-side waveguide layer 4 is fixedly connected to the P-type strain buffer layer 3. The P-side waveguide layer 4 is doped with carbon. The doping concentration of carbon is 5×10 16 -3×1018 cm -3 The epitaxial growth of the P-face waveguide layer 4 is carried out by thermal decomposition of AsH3, the flow rate of AsH3 is 300-2000sccm, the epitaxial growth temperature of the P-face waveguide layer 4 is 600-750°C, the epitaxial growth pressure is 80-200mbar, and the total thickness of the P-face confinement layer 2 and the P-face waveguide layer 4 is 1-5μm. In this embodiment, the material of the P-face waveguide layer 4 is Al 0.4 GaAs. The carbon doping concentration of the P-side waveguide layer 4 is 6×10 17 cm -3 , the flow rate of AsH3 is 300sccm, the epitaxial growth temperature is 740℃, the epitaxial growth pressure is 200mbar, and the thickness is 1000nm.

[0028] The material of the active layer 5 is indium gallium arsenide, and the active layer 5 is fixedly connected to the P-side waveguide layer 4. The epitaxial growth of the active layer 5 adopts AsH3 thermal decomposition, the flow rate of AsH3 is 50-100 sccm, the epitaxial growth temperature of the active layer 5 is 580-750°C, the epitaxial growth pressure is 80-200 mbar, and the thickness is 2-10 nm. In this embodiment, the material of the active layer 5 is In 0.08 GaAs. The epitaxial growth temperature of the active layer 5 is 590° C., the epitaxial growth pressure is 110 mbar, the thickness is 6 nm, and the flow rate of AsH3 is 70 sccm.

[0029] The material of the N-side waveguide layer 6 is gallium aluminum arsenide, and the N-side waveguide layer 6 is fixedly connected to the active layer 5. The N-side waveguide layer 6 is doped with silicon, and the doping concentration of silicon is 5×10 16 -3×10 18 cm -3 The epitaxial growth of the N-side waveguide layer 6 is carried out by thermal decomposition of AsH3, the flow rate of AsH3 is 300-2000 sccm, the epitaxial growth temperature of the N-side waveguide layer 6 is 600-750°C, and the epitaxial growth pressure is 80-200 mbar. In this embodiment, the material of the N-side waveguide layer 6 is Al 0.4 GaAs. The silicon doping concentration of the N-side waveguide layer 6 is 6×10 16 cm -3 , the flow rate of AsH3 is 2000sccm, the epitaxial growth temperature is 700℃, the epitaxial growth pressure is 150mbar, and the thickness is 1000nm.

[0030] The material of the N-side limiting layer 7 is gallium aluminum arsenide, and the N-side limiting layer 7 is fixedly connected to the N-side waveguide layer 6. The N-side limiting layer 7 is doped with silicon, and the doping concentration of silicon is 5×10 16 -3×10 18 cm -3。The epitaxial growth of the N-side confinement layer 7 uses the thermal decomposition of AsH3. The flow rate of AsH3 is 300 - 2000 sccm. The epitaxial growth temperature of the N-side confinement layer 7 is 600 - 750 °C, the epitaxial growth pressure is 80 - 200 mbar, and the thickness is 1 - 5 μm. In this embodiment, the material of the N-side confinement layer 7 is Al 0.2 GaAs. The doping concentration of silicon element in the N-side confinement layer 7 is 2×10 18 cm -3 , the flow rate of AsH3 is 1800 sccm, the epitaxial growth temperature is 640 °C, the epitaxial growth pressure is 200 mbar, and the thickness is 500 nm.

[0031] There are 3 - 50 groups of cyclic strain buffer layers. In this embodiment, there are 5 groups of strain buffer layers. Each group of cyclic strain buffer layers includes a strain layer 8 and a buffer layer 9 arranged in sequence.

[0032] The material of the strain layer 8 is Al x Ga 1-x In y P, where 0 < x < 1, 0 < y < 0.48, and one of the strain layers 8 is fixedly connected to the N-side confinement layer 7. The epitaxial growth of the strain layer 8 uses the thermal decomposition of PH3. The flow rate of PH3 is 300 - 2000 sccm. The epitaxial growth temperature of the strain layer 8 is 600 - 750 °C, and the epitaxial growth pressure is 80 - 200 mbar. In this embodiment, the materials of the five strain layers 8 are all Al 0.3 Ga 0.7 In 0.4 P, the flow rate of PH3 is 1400 sccm. The epitaxial growth temperature of the strain layer 8 is 750 °C, and the epitaxial growth pressure is 140 mbar.

[0033] The material of the buffer layer 9 is gallium arsenide, and the buffer layer 9 is fixedly connected to the strain layer 8. The total thickness of the buffer layer 9 is 200 nm. Therefore, in this embodiment, the thickness of each buffer layer 9 is 40 nm.

[0034] The material of the substrate 10 is gallium arsenide, and the substrate 10 is fixedly connected to a buffer layer 9. In this embodiment, the size of the substrate 10 is 6 inches, and the thickness is 650 μm. The sizes of the contact layer 1, P-side confinement layer 2, P-type strain buffer layer 3, P-side waveguide layer 4, active layer 5, N-side waveguide layer 6, N-side confinement layer 7, strain layer 8, and buffer layer 9 are all equal to that of the substrate 10.

[0035] In this embodiment, the total compressive stress generated by the contact layer 1, the P-face confinement layer 2, the P-face waveguide layer 4, the active layer 5, the N-face waveguide layer 6 and the N-face confinement layer 7 is 283ppm×500nm+567ppm×1000nm+5731ppm×6nm+567ppm×1000nm+283ppm×500nm=1451386.

[0036] Since the material of the P-type strain buffer layer 3 is Al 0.3 Ga 0.7 In 0.3 The thickness of the P-type strain buffer layer 3 is 50 nm, and the material of the strain layer 8 is Al 0.3 Ga 0.7 In 0.4 P, through XRD analysis software, it can be concluded that the stress difference between the P-type strain buffer layer 3 and the buffer layer 9 is -12000ppm, and the stress difference between the strain layer 8 and the buffer layer 9 is -4595ppm. In this embodiment, the total thickness of the strain layer 8 is (1451386-12000×50) / 4595=185nm. Therefore, the thickness of each strain layer 8 is 37nm.

[0037] Example 2

[0038] The difference between Example 2 and Example 1 is that in Example 2, three groups of cyclic strain buffer layers are provided.

[0039] In this embodiment, since the values ​​of x and y remain unchanged, the total thickness of the strain layer 8 and the buffer layer 9 remains unchanged, so the thickness of each strain layer 8 is 62 nm, and the thickness of each buffer layer 9 is 67 nm.

[0040] Example 3

[0041] The difference between Example 3 and Example 1 is that in Example 3, 50 groups of cyclic strain buffer layers are provided.

[0042] In this embodiment, since the values ​​of x and y remain unchanged, the total thickness of the strain layer 8 and the buffer layer 9 remains unchanged, so the thickness of each strain layer 8 is 3.7 nm, and the thickness of each buffer layer 9 is 4 nm.

[0043] Combining Examples 1-3, it can be seen that when y<0.48, Al x Ga 1-x In yThe lattice of P is smaller than that of GaAs, so that tensile stress is generated between the strain layer 8 and the buffer layer 9. Similarly, when b<0.48, tensile stress is generated between the P-type strain buffer layer 3 and the buffer layer 9. The tensile stress opposite to the compressive stress of the laser epitaxial structure is introduced into the structure to balance the stress of the entire epitaxial structure, reduce the warping of the epitaxial wafer, reduce the fragmentation rate, cleave the cavity lines, improve the yield, and improve the defect of the laser epitaxial structure with large compressive stress and severe warping.

[0044] Compared with directly setting a strain layer 8 and a buffer layer 9, setting a cyclic strain buffer layer 9 can not only control the total stress of the structure, but also make each layer of GaAs and Al x Ga 1-x In y The thickness of P is reduced, thereby improving the interface quality between the strain layer 8 and the buffer layer 9, and enhancing the reliability of the entire semiconductor laser structure; The introduction of the P-type strain buffer layer 3 in the structure not only balances the overall stress, but also controls the stress of the active layer, thereby controlling the quantum well recombination efficiency and improving the optical power. a Ga 1-a In b P has a high corrosion selectivity ratio to GaAsAl, and can be used as an corrosion stop layer to increase the reliability of the laser structure.

[0045] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer, characterized in that: It includes a contact layer (1), a P-side confinement layer (2), a P-type strain buffer layer (3), a P-side waveguide layer (4), an active layer (5), an N-side waveguide layer (6), an N-side confinement layer (7), and several groups of cyclic strain buffer layers arranged in sequence. The material of the P-type strain buffer layer (3) is Al a Ga 1-a In b P, where 0 < a < 1 and 0 < b < 0.

48. Each group of the cyclic strain buffer layers is provided with a strain layer (8) and a buffer layer (9). The material of the buffer layer (9) is gallium arsenide, and the material of the strain layer (8) is Al x Ga 1-x In y P, where 0 < x < 1 and 0 < y < 0.

48. The cyclic strain buffer layers are provided with 3 - 50 groups.

2. The semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer according to claim 1, characterized in that: The total thickness of the buffer layer (9) is 200 nm.

3. The semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer according to claim 1, characterized in that: The epitaxial growth temperature of the strain layer (8) is 600-750° C., the epitaxial growth pressure is 80-200 mbar, and the epitaxial growth of the strain layer (8) adopts PH3 thermal decomposition, and the flow rate of PH3 is 300-2000 sccm.

4. The semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer according to claim 1, characterized in that: The epitaxial growth temperature of the P-type strain buffer layer (3) is 600-750° C., the epitaxial growth pressure is 80-200 mbar, and the epitaxial growth of the P-type strain buffer layer (3) adopts PH3 thermal decomposition, and the flow rate of PH3 is 300-2000 sccm.

5. The semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer according to claim 1, characterized in that: The materials of the N-side limiting layer (7) and the N-side waveguide layer (6) are both gallium aluminum arsenide, the epitaxial growth temperature of the N-side limiting layer (7) and the N-side waveguide layer (6) is 600-750° C., and the epitaxial growth pressure is 80-200 mbar.

6. The semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer according to claim 5, characterized in that: The epitaxial growth of the N-side limiting layer (7) and the N-side waveguide layer (6) is carried out by thermal decomposition of AsH3, with the flow rate of AsH3 being 300-2000sccm.

7. The semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer according to claim 1, characterized in that: The material of the active layer (5) is indium gallium aluminum, the epitaxial growth temperature of the active layer (5) is 580-750° C., and the epitaxial growth pressure is 80-200 mbar.

8. The semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer according to claim 1, characterized in that: The materials of the P-face limiting layer (2) and the P-face waveguide layer (4) are both gallium aluminum arsenide, the epitaxial growth temperature of the P-face limiting layer (2) and the P-face waveguide layer (4) is 600-750° C., and the epitaxial growth pressure is 80-200 mbar.

9. The semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer according to claim 8, characterized in that: The epitaxial growth of the P-face limiting layer (2) and the P-face waveguide layer (4) is carried out by thermal decomposition of AsH3, and the flow rate of AsH3 is 300-2000sccm.

10. The semiconductor laser structure with a cyclic strain buffer layer and a P-type strain buffer layer according to claim 1, characterized in that: The material of the contact layer (1) is gallium arsenide phosphide, the epitaxial growth temperature of the contact layer (1) is 550-650° C., and the epitaxial growth pressure is 80-200 mbar.

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