A semiconductor laser structure with a stepped strain layer

Abstract

The application relates to the technical field of semiconductors, and particularly discloses a semiconductor laser structure with stepped strain layers, which comprises a contact layer, a P-plane limiting layer, a P-plane waveguide layer, an active layer, an N-plane waveguide layer, an N-plane limiting layer and a buffer layer arranged in sequence, the material of the buffer layer is gallium arsenide, a plurality of first strain layers are arranged between the buffer layer and the N-plane limiting layer, the material of the first strain layers is Al x Ga 1‑x In y P, wherein 0 < x < 1 and 0 < y < 0.48, a second strain layer is arranged between the P-plane waveguide layer and the active layer, and the material of the second strain layer is Al a Ga 1‑ a In b P, wherein 0

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of semiconductors, in particular to a semiconductor laser structure with a stepped strain layer. BACKGROUND

[0002] The buffer layer of a conventional high-power laser epitaxial structure is mostly made of gallium arsenide material. The structure is usually made of gallium aluminum arsenide materials with different aluminum contents except the buffer layer. Although the lattice parameters of aluminum arsenide and gallium arsenide are very close, being 5.6691 Å and 5.6533 Å respectively, the lattice mismatch is 1500 ppm, but the total thickness of the aluminum-containing part of the entire laser epitaxial structure is between 4-10 μm, so that the total stress accumulation is large.

[0003] It is detected that the warpage of a 4-inch epitaxial wafer reaches 20 μm when the substrate is not thinned, and the warpage reaches about 260 μm when the substrate is thinned to 150 μm. For a 6-inch epitaxial wafer, the warpage is 150 μm when the substrate is not thinned, and the warpage is extremely serious when the substrate is thinned to 150 μm, and the wafer is easily broken, even if the wafer is not broken, cleaving is easy to produce cavity lines, resulting in cavity surface reliability failure. SUMMARY

[0004] In order to improve the defect that the stress of the laser epitaxial structure is large and the warpage is serious, the application provides a semiconductor laser structure with a stepped strain layer.

[0005] The application provides a semiconductor laser structure with a stepped strain layer, which adopts the following technical scheme:

[0006] The semiconductor laser structure with a stepped strain layer comprises a contact layer, a P-plane limiting layer, a P-plane waveguide layer, an active layer, an N-plane waveguide layer, an N-plane limiting layer and a buffer layer arranged in sequence, the material of the buffer layer is gallium arsenide, a plurality of first strain layers are arranged between the buffer layer and the N-plane limiting layer, the material of the first strain layer is Al x Ga 1-x In y P, wherein 0 a Ga 1-a In b P, wherein 0

[0007] By adopting the above technical scheme, the first strain layer is arranged between the buffer layer and the N-plane limiting layer, the stress size is adjusted by adjusting the proportion of indium components, when y=0.48, Al x Ga 1-x Iny P and gallium arsenide lattice match, when y < 0.48, Al x Ga 1-x In y The lattice of P is smaller than the lattice of gallium arsenide, which introduces tensile stress opposite to the laser epitaxial structure stress in the structure, balances the stress of the whole epitaxial structure, reduces the wafer warping, reduces the wafer breakage rate, cleavage cavity, improves the yield, and improves the laser epitaxial structure stress, which causes the defect of serious warping;

[0008] The second strain layer is arranged between the P-face waveguide layer and the active layer, the second strain layer can provide tensile stress for the structure and also play the role of electron limitation, by adjusting the value of a, the refractive index and the barrier height of the second strain layer can be changed, thereby improving the quantum limitation and light field limitation.

[0009] Optionally, the epitaxial growth temperature of the first strain layer and the second strain layer is 600-750℃, and the epitaxial growth pressure is 80-200mbar.

[0010] Optionally, the epitaxial growth of the first strain layer and the second strain layer adopts PH3 thermal decomposition, and the flow rate of PH3 is 300-2000sccm.

[0011] Optionally, the number of the first strain layer is 3-10, and the value of y of the plurality of first strain layers changes linearly.

[0012] Optionally, the materials of the N-face confinement layer and the N-face waveguide layer are both gallium aluminum arsenide, the N-face confinement layer and the N-face waveguide layer are doped with silicon element, and the doping concentration of silicon is 5×10 16 -3×10 18 cm -3 The epitaxial growth temperature of the N-face confinement layer and the N-face waveguide layer is 600-750℃, and the epitaxial growth pressure is 80-200mbar.

[0013] Optionally, the epitaxial growth of the N-face confinement layer and the N-face waveguide layer adopts AsH3 thermal decomposition, the flow rate of AsH3 is 300-2000sccm, and the total thickness of the N-face confinement layer and the N-face waveguide layer is 1-5μm.

[0014] Optionally, the material of the active layer is gallium aluminum indium, the epitaxial growth temperature of the active layer is 580-750℃, the epitaxial growth pressure is 80-200mbar, and the thickness is 2-10nm.

[0015] Optionally, the materials of the P-face confinement layer and the P-face waveguide layer are both gallium aluminum arsenide, the P-face confinement layer and the P-face waveguide layer are doped with carbon element, and the doping concentration of carbon is 5×10 16 -3×1018 cm -3 The epitaxial growth temperature of the P-plane confinement layer and the P-plane waveguide layer is 600-750℃, the epitaxial growth pressure is 80-200mbar, and the total thickness of the P-plane confinement layer and the P-plane waveguide layer is 1-5μm.

[0016] Optionally, the epitaxial growth of the P-plane confinement layer and the P-plane waveguide layer uses AsH3 thermal decomposition, and the flow rate of AsH3 is 300-2000sccm.

[0017] Optionally, the material of the contact layer is gallium arsenide phosphorus, the contact layer is doped with carbon elements, and the doping concentration of carbon is 5×1018-5×1020cm-3. 19 -5×1020 20 cm -3 The epitaxial growth temperature of the contact layer is 550-650℃, the epitaxial growth pressure is 80-200mbar, and the thickness is 50-500nm.

[0018] In summary, the present application includes at least one of the following beneficial technical effects:

[0019] The first strain layer is arranged between the buffer layer and the N-plane confinement layer, the stress size is adjusted by adjusting the proportion of indium components, when y=0.48, the lattice of AlxGa1-xInyP matches the lattice of gallium arsenide, when y<0.48, the lattice of AlxGa1-xInyP is smaller than the lattice of gallium arsenide, the tensile stress opposite to the compressive stress of the laser epitaxial structure is introduced in the structure, the stress of the whole epitaxial structure is balanced, the wafer warping is reduced, the wafer breakage rate is reduced, the cleavage cavity is reduced, the yield is improved, and the defect that the laser epitaxial structure has large compressive stress and causes serious warping is improved.

[0020] The second strain layer is arranged between the P-plane waveguide layer and the active layer, the second strain layer can provide tensile stress for the structure and also play the role of electron confinement, by adjusting the value of a, the refractive index and the barrier height of the second strain layer can be changed, so that the quantum confinement and the light field confinement effect are improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a structural schematic diagram of a semiconductor laser structure with a stepped strain layer according to an embodiment of the present application.

[0022] Explanation of reference signs: 1, contact layer; 2, P-plane confinement layer; 3, P-plane waveguide layer; 4, second strain layer; 5, active layer; 6, N-plane waveguide layer; 7, N-plane confinement layer; 8, first strain layer; 9, buffer layer; 10, substrate. DETAILED DESCRIPTION

[0023] The following will be described in detail in combination with the accompanying drawings. Figure 1 The present application will be further described in detail. Example

[0024] This application discloses a semiconductor laser structure with a stepped strain layer.

[0025] Example 1

[0026] Reference Figure 1 A semiconductor laser structure with a stepped strain layer includes a contact layer 1, a P-plane confinement layer 2, a P-plane waveguide layer 3, a second strain layer 4, an active layer 5, an N-plane waveguide layer 6, an N-plane confinement layer 7, a first strain layer 8, a buffer layer 9, and a substrate 10 arranged sequentially.

[0027] The material of contact layer 1 is gallium arsenide phosphide, and contact layer 1 is doped with carbon, with a carbon doping concentration of 5 × 10⁻⁶. 19 -5×10 20 cm -3 The epitaxial growth temperature is 550-650℃, the epitaxial growth pressure is 80-200 mbar, and the thickness is 50-500 nm. In this embodiment, the carbon doping concentration of contact layer 1 is 5 × 10⁻⁶. 20 cm -3 The epitaxial growth temperature is 600℃, the epitaxial growth pressure is 200mbar, and the thickness is 200nm.

[0028] The p-side confinement layer 2 is made of aluminum gallium arsenide and is fixedly connected to the contact layer 1. The p-side confinement layer 2 is doped with carbon at a concentration of 5 × 10⁻⁶. 16 -3×10 18 cm -3 The epitaxial growth of the P-side confinement layer 2 is achieved through the thermal decomposition of AsH3, with an AsH3 flow rate of 300-2000 sccm. The epitaxial growth temperature of the P-side confinement layer 2 is 600-750℃, 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 carbon doping concentration of the p-face confinement layer 2 is 5 × 10⁻⁶. 16 cm -3 The flow rate of AsH3 was 1800 sccm, the epitaxial growth temperature was 650℃, the epitaxial growth pressure was 200 mbar, and the thickness was 500 nm.

[0029] The P-plane waveguide layer 3 is made of aluminum gallium arsenide and is fixedly connected to the P-plane confinement layer 2. The P-plane waveguide layer 3 is doped with carbon at a concentration of 5 × 10⁻⁶. 16 -3×10 18 cm -3。The epitaxial growth of the P-side waveguide layer 3 is carried out by thermal decomposition of AsH3. The flow rate of AsH3 is 300 - 2000 sccm. The epitaxial growth temperature of the P-side waveguide layer 3 is 600 - 750 °C, the epitaxial growth pressure is 80 - 200 mbar, and the total thickness of the P-side confinement layer 2 and the P-side waveguide layer 3 is 1 - 5 μm. In this embodiment, the material of the P-side waveguide layer 3 is Al 0.4 GaAs. The carbon element doping concentration of the P-side waveguide layer 3 is 3×10 17 cm -3 , the flow rate of AsH3 is 1600 sccm, the epitaxial growth temperature is 750 °C, the epitaxial growth pressure is 200 mbar, and the thickness is 1000 nm.

[0030] The material of the second strain layer 4 is Al a Ga 1-a In b P, where 0 < a < 0.4 and 0 < b < 0.48. The second strain layer 4 is fixedly connected to the P-side waveguide layer 3. The epitaxial growth of the second strain layer 4 is carried out by thermal decomposition of PH3. The flow rate of PH3 is 300 - 2000 sccm. The epitaxial growth temperature of the second strain layer 4 is 600 - 750 °C, and the epitaxial growth pressure is 80 - 200 mbar. In this embodiment, the material of the second strain layer 4 is Al 0.3 Ga 0.7 In 0.4 P, the flow rate of PH3 is 2000 sccm. The epitaxial growth temperature of the second strain layer 4 is 700 °C, and the epitaxial growth pressure is 180 mbar.

[0031] The material of the active layer 5 is gallium indium arsenide. The active layer 5 is fixedly connected to the second strain layer 4. The epitaxial growth of the active layer 5 is carried out by thermal decomposition of AsH3. 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 4 is 630 °C, the epitaxial growth pressure is 120 mbar, the thickness is 6 nm, and the flow rate of AsH3 is 80 sccm.

[0032] The material of the N-side waveguide layer 6 is gallium aluminum arsenide. The N-side waveguide layer 6 is fixedly connected to the active layer 5. The N-side waveguide layer 6 is doped with silicon element, 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 uses the 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 doping concentration of silicon element in the N-side waveguide layer 6 is 5×10 17 cm -3 . The flow rate of AsH3 is 1900 sccm, the epitaxial growth temperature is 670 °C, the epitaxial growth pressure is 150 mbar, and the thickness is 1000 nm.

[0033] The material of the N-side confinement layer 7 is aluminum gallium arsenide, and the N-side confinement layer 7 is fixedly connected to the N-side waveguide layer 6. The N-side confinement layer 7 is doped with silicon element, 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, and the epitaxial growth pressure is 80 - 200 mbar. 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 5×10 16 cm -3 . The flow rate of AsH3 is 2000 sccm, the epitaxial growth temperature is 700 °C, the epitaxial growth pressure is 120 mbar, and the thickness is 500 nm.

[0034] The material of the first strain layer 8 is Al x Ga 1-x In y P, where 0 < x < 1 and 0 < y < 0.48. The first strain layer 8 is fixedly connected to the N-side confinement layer 7. The epitaxial growth of the first strain layer 8 uses the thermal decomposition of PH3. The flow rate of PH3 is 300 - 2000 sccm. The epitaxial growth temperature of the first strain layer 8 is 600 - 750 °C, and the epitaxial growth pressure is 80 - 200 mbar. In this embodiment, there are three first strain layers 8, and the materials of the three first strain layers 8 are respectively Al 0.3 Ga 0.7 In 0.25 P, Al 0.3 Ga 0.7 In 0.3 P, and Al 0.3 Ga 0.7 In 0.35P, the flow rate of PH3 is 1000 seem. The epitaxial growth temperature of the first strain layer 8 is 720°C, and the epitaxial growth pressure is 190 mbar.

[0035] The material of the buffer layer 9 is gallium arsenide, and the buffer layer 9 is fixedly connected with the first strain layer 8. In this embodiment, the thickness of the buffer layer 9 is 200 nm.

[0036] The material of the substrate 10 is gallium arsenide, and the substrate 10 is fixedly connected with the buffer layer 9. In this embodiment, the size of the substrate 10 is 6 inches, and the thickness is 675 μm. The size of the contact layer 1, the P-face confinement layer 2, the P-face waveguide layer 3, the second strain layer 4, the active layer 5, the N-face waveguide layer 6, the N-face confinement layer 7, the first strain layer 8 and the buffer layer 9 is equal to that of the substrate 10.

[0037] In this embodiment, the total compressive stress generated by the contact layer 1, the P-face confinement layer 2, the P-face waveguide layer 3, the active layer 5, the N-face waveguide layer 6 and the N-face confinement layer 7 is 283 ppm x 500 nm + 567 ppm x 1000 nm + 5731 ppm x 6 nm + 567 ppm x 1000 nm + 283 ppm x 500 nm = 1451386.

[0038] Since the materials of the three first strain layers 8 are Al 0.3 Ga 0.7 In 0.25 P, Al 0.3 Ga 0.7 In 0.3 P and Al 0.3 Ga 0.7 In 0.35 P, the material of the second strain layer 4 is Al 0.3 Ga 0.7 In 0.4 P, through the XRD analysis software, it can be obtained that the stress difference between the three first strain layers 8 and the buffer layer 9 is -15691 ppm, -12000 ppm and -8294 ppm respectively, and the stress difference between the second strain layer 4 and the buffer layer 4 is -4595 ppm. In order to eliminate the stress difference, the thickness of the first strain layer 8 and the second strain layer 4 has multiple values. In this embodiment, the thickness of the three first strain layers 8 is 20 nm, 20 nm and 30 nm respectively, and the thickness of the second strain layer 4 is 141 nm.

[0039] Embodiment 2

[0040] The difference between embodiment 2 and embodiment 1 is that the thickness of the first strain layer 8 and the second strain layer 4 is different.

[0041] In this embodiment, the thickness of the three first strain layers 8 is 30 nm, and the thickness of the second strain layer 4 is 80 nm.

[0042] As can be seen from Embodiments 1-2, the thickness of the first strain layer 8 and the second strain layer 4 is determined by the stress difference between the first strain layer 8 and the buffer layer 9, and the total compressive stress generated by the contact layer 1, the P-face confinement layer 2, the P-face waveguide layer 3, the active layer 5, the N-face waveguide layer 6 and the N-face confinement layer 7. The stress difference between the first strain layer 8 and the buffer layer 9 is determined by the values of x and y, and the stress difference between the second strain layer 4 and the buffer layer 9 is determined by the values of a and b.

[0043] Through XRD analysis software, it can be found that when y < 0.48, the lattice of Al x Ga 1-x In y P is smaller than the lattice of GaAs, so that tensile stress is generated between the first strain layer 8 and the buffer layer 9. The introduction of tensile stress in the structure, which is opposite to the compressive stress of the laser epitaxial structure, balances the stress of the whole epitaxial structure, reduces the wafer warping, reduces the wafer breakage rate, reduces the cleavage cavity, improves the yield, and improves the defect that the laser epitaxial structure has large compressive stress, which leads to serious warping.

[0044] The second strain layer 4 can also play the role of electron confinement while providing tensile stress for the structure. By adjusting the value of a, the refractive index and the barrier height of the second strain layer 4 can be changed, so as to improve the quantum confinement and optical field confinement.

[0045] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, any equivalent changes made on the basis of the structure, shape and principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A semiconductor laser structure with a stepped strain layer, comprising a contact layer (1), a P-plane confinement layer (2), a P-plane waveguide layer (3), an active layer (5), an N-plane waveguide layer (6), an N-plane confinement layer (7), and a buffer layer (9) arranged sequentially, characterized in that: The material of the buffer layer (9) is gallium arsenide. There are 3 - 10 first strain layers (8) provided between the buffer layer (9) and the N - side confinement layer (7). The material of the first strain layer (8) is Al x Ga 1-x In y P, where 0 < x < 1, 0 < y < 0.

48. The y value of the first strain layer (8) changes linearly. There is a second strain layer (4) provided between the P - side waveguide layer (3) and the active layer (5). The material of the second strain layer (4) is Al a Ga 1-a In b P, where 0 < a < 0.4, 0 < b < 0.

48.

2. The semiconductor laser structure with a stepped strain layer according to claim 1, characterized in that: The epitaxial growth temperature of the first strain layer (8) and the second strain layer (4) is 600-750℃, and the epitaxial growth pressure is 80-200mbar.

3. The semiconductor laser structure with a stepped strain layer according to claim 2, characterized in that: The epitaxial growth of the first strain layer (8) and the second strain layer (4) is carried out by PH3 thermal decomposition, with a PH3 flow rate of 300-2000 sccm.

4. The semiconductor laser structure with a stepped strain layer according to claim 1, characterized in that: The N-plane confinement layer (7) and the N-plane waveguide layer (6) are both made of aluminum gallium arsenide. The epitaxial growth temperature of the N-plane confinement layer (7) and the N-plane waveguide layer (6) is 600-750℃, and the epitaxial growth pressure is 80-200mbar.

5. A semiconductor laser structure with a stepped strain layer according to claim 4, characterized in that: The epitaxial growth of the N-plane confinement layer (7) and the N-plane waveguide layer (6) is carried out by AsH3 thermal decomposition, with a flow rate of 300-2000 sccm for AsH3.

6. The semiconductor laser structure with a stepped strain layer according to claim 1, characterized in that: The active layer (5) is made of aluminum gallium indium phosphate (IGAP), and the epitaxial growth temperature of the active layer (5) is 580-750℃, and the epitaxial growth pressure is 80-200mbar.

7. A semiconductor laser structure with a stepped strain layer according to claim 1, characterized in that: The materials of the P-plane confinement layer (2) and the P-plane waveguide layer (3) are both aluminum gallium arsenide. The epitaxial growth temperature of the P-plane confinement layer (2) and the P-plane waveguide layer (3) is 600-750℃, and the epitaxial growth pressure is 80-200mbar.

8. A semiconductor laser structure with a stepped strain layer according to claim 7, characterized in that: The epitaxial growth of the P-plane confinement layer (2) and the P-plane waveguide layer (3) is carried out by thermal decomposition of AsH3, with a flow rate of 300-2000 sccm.

9. A semiconductor laser structure with a stepped strain layer according to claim 1, characterized in that: The contact layer (1) is made of gallium arsenide phosphide, and the epitaxial growth temperature of the contact layer (1) is 550-650℃, and the epitaxial growth pressure is 80-200mbar.

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