Structure and fabrication method of multi-junction cascaded quantum dot vertical-cavity surface-emitting laser

Abstract

This invention relates to the field of quantum dot active region laser technology. Vertical cavity surface-emitting lasers (VCSELs) with quantum wells as active regions typically suffer from poor temperature stability, and single-junction quantum dot VCSELs exhibit low output power and low electro-optical conversion efficiency. This invention provides a multi-junction cascaded quantum dot VCSEL structure and fabrication method. The oxide-confined VCSEL with a multi-junction cascaded quantum dot active region structure not only improves the carrier confinement capability but also effectively reduces photoelectric loss and energy loss. The quantum dot active region structure enhances the carrier confinement capability and temperature stability of the active region. By using tunnel junctions to connect the active regions in series within the same resonant cavity, the output power and electro-optical conversion efficiency are significantly improved without a substantial increase in resistance and absorption loss.

Description

Technical Field

[0001] This invention relates to the field of quantum dot active region laser technology, specifically to a multi-junction cascaded quantum dot vertical cavity surface-emitting laser structure and its fabrication method. Background Technology

[0002] As a core component of vertical-cavity surface-emitting lasers (VCSELs), the structure of the active region significantly impacts their output characteristics. Oxide-confined CCSELs typically employ quantum well structures as their active regions. While these structures offer high carrier injection efficiency, their poor carrier confinement leads to low radiative recombination rates. Furthermore, larger oxide apertures in oxide-confined CCSELs result in higher power conversion efficiency at room temperature, but also more severe power loss at high ambient temperatures. Consequently, CCSELs with quantum well active regions generally exhibit poor temperature stability. Conversely, smaller active volume, stronger carrier localization, and higher temperature stability result in smaller active regions. Therefore, quantum well active region structures typically offer advantages such as high radiative recombination rates, low threshold currents, and high temperature stability. However, single-junction quantum dot CCSELs suffer from low carrier injection efficiency, resulting in low output power and low electro-optical conversion efficiency.

[0003] The weak carrier confinement capability of quantum well active regions and the low injection efficiency of quantum dot active regions are key issues affecting further improvements in the output power and electro-optical conversion efficiency of 1.3 μm oxide-confined vertical-cavity surface-emitting lasers (VCSELs). Quantum well active regions exhibit high carrier injection efficiency but low radiative recombination rate, resulting in typically high non-radiative emissions, leading to severe photoelectric losses and low temperature stability. Quantum dot active regions, due to their enhanced three-dimensional carrier confinement, significantly improve radiative recombination efficiency, reduce threshold current, and exhibit high temperature stability. However, their low injection efficiency and significant energy losses typically limit their application in long-wavelength bands, resulting in low output power and low electro-optical conversion efficiency. Therefore, designing the active region structure of oxide-confined VCSELs is crucial for further improving their carrier confinement capability, temperature stability, and output characteristics. Summary of the Invention

[0004] To address the problems of weak carrier confinement, high photoelectric loss, poor temperature stability, and low output power in current 1.3μm oxide-confined vertical-cavity surface-emitting lasers (VCSELs), this invention aims to provide a multi-junction cascaded quantum dot VCSEL structure and fabrication method. The oxide-confined VCSEL with a multi-junction cascaded quantum dot active region structure not only improves carrier confinement capability but also effectively reduces photoelectric loss and energy loss. The quantum dot active region structure enhances carrier confinement capability and temperature stability in the active region. Furthermore, by utilizing tunnel junctions to connect the active regions in series within the same resonant cavity, this invention significantly improves output power and electro-optical conversion efficiency without substantially increasing resistance and absorption loss.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A vertical-cavity surface-emitting laser structure with a multi-junction cascaded quantum dot active region includes an n-GaAs substrate and an n-GaAs buffer layer, an n-distributed Bragg mirror, and an Al2O3 matrix sequentially arranged along the growth direction. 0.6 Ga 0.4 As space layer, quantum dot active region layer, Al 0.6 Ga 0.4 As space layer, p-Al 0.98 Ga 0.02 As oxidation confinement layer, Al 0.6 Ga 0.4 As space layer, p-Al 0.05 Ga 0.95 As tunneling layer, n-GaAs tunneling layer, Al 0.6 Ga 0.4 As space layer, quantum dot active region layer, Al 0.6 Ga 0.4 As space layer, p-Al 0.98 Ga 0.02 As oxide confinement layer, p-distributed Bragg mirror, and p-GaAs capping layer, wherein:

[0007] An n-GaAs buffer layer is grown on an n-GaAs substrate, and an n-distributed Bragg mirror is grown on the n-GaAs buffer layer. Al 0.6 Ga 0.4 The As space layer is grown on an n-distributed Bragg mirror, and the quantum dot active region layer is grown on Al. 0.6 Ga 0.4 As grows on the space layer, Al 0.6 Ga 0.4 As spatial layers are grown on the active region of quantum dots, p-Al 0.98 Ga 0.02 As oxidation confinement layer in Al0.6 Ga 0.4 As grows on the space layer, Al 0.6 Ga 0.4 As space layer in p-Al 0.98 Ga 0.02 p-Al grows on an As oxide confinement layer. 0.05 Ga 0.95 As tunneling layer in Al 0.6 Ga 0.4 n-GaAs tunnel junctions grow on p-Al space layers. 0.05 Ga 0.95 As grows on the tunnel layer, Al 0.6 Ga 0.4 As space layers are grown on n-GaAs tunnel junction layers, and quantum dot active regions are grown on Al. 0.6 Ga 0.4 As grows on the space layer, Al 0.6 Ga 0.4 As spatial layers are grown on the active region of quantum dots, p-Al 0.98 Ga 0.02 As oxidation confinement layer in Al 0.6 Ga 0.4 p-distributed Bragg mirrors grown on p-Al space layers 0.98 Ga 0.02 As oxide confinement layer is grown, and p-GaAs capping layer is grown on p-distributed Bragg mirror.

[0008] Furthermore, quantum dot active region layer, Al 0.6 Ga 0.4 As space layer, p-Al 0.98 Ga 0.02 As oxidation confinement layer, Al 0.6 Ga 0.4 As space layer, p-Al 0.05 Ga 0.95 As tunneling layer, n-GaAs tunneling layer and Al 0.6 Ga 0.4 After the As spatial layers grow sequentially, they are then grown in the same order three more times.

[0009] Furthermore, the n-distributed Bragg mirror comprises 36 n-GaAs high-refractive-index layers and 35 Al layers. 0.9 Ga 0.1 As low refractive index layer, n-GaAs high refractive index layer and Al 0.9 Ga 0.1 As low-refractive-index layers are grown alternately, the n-distributed Bragg mirror starts growing from an n-GaAs buffer layer with Al as the initial layer. x Ga1-x As composition graded layer; p-distributed Bragg mirror includes 14 pairs of n-GaAs high refractive index layers and Al. 0.9 Ga 0.1 As a low-refractive-index layer, the p-distributed Bragg mirror is derived from p-Al. 0.98 Ga 0.02 The growth of the As oxide confinement layer begins at Al. x Ga 1-x As composition graded layer; n-GaAs high refractive index layer and Al 0.9 Ga 0.1 Al is set between the low refractive index layers. x Ga 1-x As component graded layer, Al x Ga 1-x The As component gradient layer has a gradient Al component with a maximum value of 0.9 and a minimum value greater than 0; the Ga component has a gradient with a maximum value of 1 and a minimum value of 0.1.

[0010] Furthermore, the n-distributed Bragg mirror consists of an Al layer with a thickness of 20 nm, starting from the n-GaAs buffer layer and growing in one cycle along the growth direction. x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0 to 0.9, and the n-type doping concentration is 2.5 × 10⁻⁶. 18 cm -3 Al with a thickness of 86nm 0.9 Ga 0.1 As a low-refractive-index layer, the n-type doping concentration is 2 × 10⁻⁶. 18 cm -3 ; 20nm thick Al x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0.9 to 0, and the n-type doping concentration is 2.5 × 10⁻⁶. 18 cm -3 A 72 nm thick GaAs high-refractive-index layer with an n-type doping concentration of 2 × 10⁻⁶. 18 cm -3 It grows over 35.5 cycles.

[0011] Furthermore, the p-distributed Bragg mirror from p-Al 0.98 Ga 0.02 The As oxide confinement layer begins with a 20 nm thick Al layer along the growth direction, forming a cycle. x Ga 1-x An As composition graded layer, where x is a linear gradient from 0.9 to 0, and the p-type doping concentration is 6 × 10⁻⁶. 18 cm -3A 72 nm thick GaAs high-refractive-index layer with a p-type doping concentration of 6 × 10⁻⁶. 17 cm -3 ; 20nm thick Al x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0 to 0.9, and the p-type doping concentration is 6 × 10⁻⁶. 18 cm -3 Al with a thickness of 86nm 0.9 Ga 0.1 As a low-refractive-index layer, the p-type doping concentration is 6 × 10⁻⁶. 17 cm -3 It grows in 14 cycles.

[0012] Furthermore, the quantum dot active region layer comprises two GaAs layers with a thickness of 10 nm. 0.855 P 0.145 Barrier layer, consisting of two GaAs layers 0.855 P 0.145 In layers with a thickness of 8 nm are sequentially arranged between the barrier layers. 0.05 Ga 0.95 As wetting layer, In 0.52 Ga 0.48 As quantum dot layer, In with a thickness of 8nm 0.05 Ga 0.95 As quantum dot capping layer, In with a thickness of 8nm 0.05 Ga 0.95 As wetting layer.

[0013] A method for fabricating a vertical-cavity surface-emitting laser structure with a multi-junction cascaded quantum dot active region, as described above, specifically includes the following steps:

[0014] Step 1. Clean the surface of the n-GaAs substrate: Introduce hydrogen gas and keep the reaction chamber temperature at 700-740℃ for 5-15 minutes to clean off particulate contaminants on the surface of the n-GaAs substrate and remove oxygen atoms from the surface of the n-GaAs substrate.

[0015] Step 2. n-GaAs buffer layer growth: The reaction chamber temperature is reduced to 650–680℃, the trimethylgallium flow rate is 90 sccm, the arsenane flow rate is 440 sccm, the silane flow rate is 50–100 sccm, the growth thickness is 500 nm, and the n-type doping concentration is 2 × 10⁻⁶. 18 cm -3 ;

[0016] Step 3. n-distributed Bragg mirror growth: The reaction chamber temperature is maintained at 650–680℃, and an Al layer with a thickness of 20 nm is grown sequentially in one cycle using an n-distributed Bragg mirror. x Ga 1-xAn As composition-gradient layer, where x is a linear gradient from 0 to 0.9, and the n-type doping concentration is 2.5 × 10⁻⁶. 18 cm -3 Al with a thickness of 86nm 0.9 Ga 0.1 As a low-refractive-index layer, the n-type doping concentration is 2 × 10⁻⁶. 18 cm -3 ; 20nm thick Al x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0.9 to 0, and the n-type doping concentration is 2.5 × 10⁻⁶. 18 cm -3 A 72 nm thick GaAs high-refractive-index layer with an n-type doping concentration of 2 × 10⁻⁶. 18 cm -3 The growth cycle was repeated for 35.5 cycles, and the overall doping concentration was controlled by adjusting the SiH4 flow rate.

[0017] Step 4.Al 0.6 Ga 0.4 As space layer growth: The reaction chamber temperature was maintained at 650-680℃, the flow rate of trimethylgallium was 55 sccm, the flow rate of trimethylaluminum was 125 sccm, the flow rate of arsine was 440 sccm, and the growth thickness was 200 nm.

[0018] Step 5. Quantum dot active region layer growth: GaAs 0.855 P 0.145 Barrier layer growth: The reaction chamber temperature was kept constant, the trimethylgallium flow rate was 45 sccm, the arsine flow rate was 800–1500 sccm, the phosphine flow rate was 300–500 sccm, and the growth time was 36 seconds, in Al 0.6 Ga 0.4 GaAs with a thickness of 10 nm is grown on the As space layer. 0.855 P 0.145 Barrier layer;

[0019] In 0.05 Ga 0.95 As wetting layer growth: Temperature increased to 680–700℃, trimethylgallium flow rate was 64 sccm, trimethylindium flow rate was 50 sccm, arsine flow rate was 1000–2000 sccm, and growth time was 18 seconds. 0.855 As 0.145 An 8 nm thick InGaAs wetting layer is grown on the P-barrier layer.

[0020] In 0.52 Ga 0.48As quantum dot layer growth: Temperature is kept constant; trimethylgallium flux is 64 sccm; trimethylindium flux is 240 sccm; arsine flux is 100–200 sccm for 3 seconds; temperature is kept constant; then the inflow of trimethylgallium and trimethylindium is stopped for 3 seconds to form In. 0.52 Ga 0.48 As quantum dots;

[0021] In 0.52 Ga 0.48 As quantum dot capping layer growth: Temperature remained constant; trimethylgallium flux was 64 sccm; trimethylindium flux was 240 sccm; arsine flux was 1000–2000 sccm; growth time was 5 seconds; and the growth thickness was 8 nm. 0.05 Ga 0.95 As capping layer;

[0022] In 0.05 Ga 0.95 As wetting layer growth: The reaction chamber temperature was raised to 680–700℃, the trimethylgallium flow rate was 64 sccm, the trimethylindium flow rate was 50 sccm, the arsine flow rate was 1000–2000 sccm, and the growth time was 18 seconds. 0.52 Ga 0.48 An 8nm thick In nanofiber is grown on an As quantum dot capping layer. 0.05 Ga 0.95 As wetting layer;

[0023] GaAs 0.855 P 0.145 Barrier layer growth: The reaction chamber temperature was kept constant, the trimethylgallium flow rate was 45 sccm, the arsine flow rate was 800–1500 sccm, the phosphine flow rate was 300–500 sccm, and the growth time was 36 seconds. 0.05 Ga 0.95 GaAs with a thickness of 10 nm is grown on the As wetting layer. 0.855 P 0.145 Barrier layer;

[0024] Step 6.Al 0.6 Ga 0.4 As spatial layer growth: with Al in step 4 0.6 Ga 0.4 The As space layer was grown under the same conditions, with a thickness of 264 nm.

[0025] Step 7. p-Al 0.98 Ga 0.02As oxide confinement layer growth: The growth process is as follows: growth temperature 650–680℃, trimethylgallium flux 55 sccm, trimethylaluminum flux 125 sccm, arsine flux 440 sccm, carbon tetrabromide flux 10–25 sccm, growth thickness 30 nm, p-doping concentration 6 × 10⁻⁶. 17 cm -3 ;

[0026] Step 8.Al 0.6 Ga 0.4 As spatial layer growth: with Al in step 4 0.6 Ga 0.4 The As space layer was grown under the same conditions, with a thickness of 180 nm.

[0027] Step 9. p-Al 0.05 Ga 0.95 As tunnel junction growth: growth temperature 650–680℃, trimethylgallium flux 97 sccm, trimethylaluminum flux 28 sccm, arsine flux 1160 sccm, carbon tetrabromide flux 10–25 sccm, growth thickness 20 nm, p-type doping concentration 10 × 10⁻⁶. 19 cm -3 ;

[0028] Step 10. n-GaAs tunnel junction growth: Temperature reduced to 550–650℃, trimethylgallium flux of 90 sccm, arsenane flux of 440 sccm, silane flux of 50–100 sccm, growth thickness of 20 nm, n-type doping concentration of 3 × 10⁻⁶ 19 cm -3 ;

[0029] Step 11.Al 0.6 Ga 0.4 As spatial layer growth: Same as step 6;

[0030] Step 12. Repeat steps 5 through 11 three times;

[0031] Step 13. Quantum dot active region layer growth: The process is the same as in Step 5.

[0032] Step 14.Al 0.6 Ga 0.4 As spatial layer growth: with Al in step 4 0.6 Ga 0.4 The As space layer was grown under the same conditions, with a thickness of 200 nm.

[0033] Step 15. p-Al 0.98 Ga 0.02 As oxide confinement layer growth: Same as step 7;

[0034] Step 16. p-Distributed Bragg Reflector Growth: The growth temperature is 680℃ to control the Zn source doping amount, in order to control p-Al 0.98 Ga 0.02 The As oxide confinement layer and the p-GaAs cap layer are doped at the same doping level. For the p-GaAs cap layer, the DEZn flux is 5 sccm, and for the p-Al... 0.98 Ga 0.02 As oxide confinement layer, DEZn source flux is 50 sccm, and a p-distributed Bragg mirror is used to sequentially grow Al layers with a thickness of 20 nm in one cycle. x Ga 1-x An As composition graded layer, where x is a linear gradient from 0.9 to 0, and the p-type doping concentration is 6 × 10⁻⁶. 18 cm -3 A 72 nm thick GaAs high-refractive-index layer with a p-type doping concentration of 6 × 10⁻⁶. 17 cm -3 ; 20nm thick Al x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0 to 0.9, and the p-type doping concentration is 6 × 10⁻⁶. 18 cm -3 Al with a thickness of 86nm 0.9 Ga 0.1 As a low-refractive-index layer, the p-type doping concentration is 6 × 10⁻⁶. 17 cm -3 ; It grows in 14 cycles;

[0035] Step 17. p-GaAs capping layer growth: Temperature reduced to 550–650℃, trimethylgallium flux of 90 sccm, arsenane flux of 440 sccm, carbon tetrabromide flux of 10–25 sccm, growth thickness of 5 nm, p-type doping concentration greater than 1 × 10⁻⁶ 19 cm -3 .

[0036] In summary, the beneficial effects of the invention are:

[0037] This invention reduces the dimensionality of the active region by setting the size, composition, and areal density of the quantum dots, resulting in a smaller active volume and stronger carrier localization. This improves radiative recombination efficiency, further reduces the threshold current, and enhances temperature stability. This invention not only improves carrier confinement but also effectively reduces photoelectric and energy losses. The laser fabricated using this invention is a high-power quantum dot vertical-cavity surface-emitting laser (VCSEL). The quantum dot active region structure enhances carrier confinement and temperature stability. By connecting multiple quantum dot active regions in series through a highly doped tunnel junction, the output power is increased several times without increasing the emitting area. Simultaneously, the tunnel junction connects multiple active regions in the same resonant cavity without a significant increase in resistance and absorption losses. This invention solves the problems of severe carrier leakage, photoelectric and energy losses, reduces non-radiative recombination in the active region, thereby lowering the threshold current and operating voltage of the VCSEL and improving its output power and electro-optical conversion efficiency. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the multi-junction cascaded quantum dot active region vertical cavity surface-emitting laser of the present invention;

[0039] Figure 2 This is a schematic diagram of the quantum dot active region structure of the 1.3μm oxide-confined vertical-cavity surface-emitting laser of the present invention;

[0040] Figure 3 This is a schematic diagram of the energy band structure of the multi-junction cascaded quantum dot active region of the present invention;

[0041] Figure 4 For single-junction, 3-junction cascaded, and 5-junction cascaded quantum dot active region vertical cavity surface emission lasers under continuous room temperature conditions: (a) PI curve; (b) PCE-I curve. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0044] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0045] like Figures 1-4 As shown, this invention discloses a vertical-cavity surface-emitting laser structure with a multi-junction cascaded quantum dot active region, including an n-GaAs substrate 1 and an n-GaAs buffer layer 2, an n-distributed Bragg mirror 3, and an Al2O3 matrix sequentially arranged along the growth direction. 0.6 Ga 0.4 As spatial layer 4, quantum dot active region layer 5, Al 0.6 Ga 0.4 As spatial layer 6, p-Al 0.98 Ga 0.02 As oxidation confinement layer 7, Al 0.6 Ga 0.4 As spatial layer 8, p-Al 0.05 Ga 0.95 As tunneling layer 9, n-GaAs tunneling layer 10, Al 0.6 Ga 0.4 As spatial layer 11, quantum dot active region layer 12, Al 0.6 Ga 0.4 As spatial layer 13, p-Al 0.98 Ga 0.02 As oxide confinement layer 14, p-distributed Bragg mirror 15, and p-GaAs capping layer 16, wherein:

[0046] An n-GaAs buffer layer 2 is grown on an n-GaAs substrate 1, and an n-distributed Bragg mirror 3 is grown on the n-GaAs buffer layer 2. Al 0.6 Ga 0.4As space layer 4 is grown on n-distributed Bragg mirror 3, and quantum dot active region layer 5 is grown on Al. 0.6 Ga 0.4 As grown on space layer 4, the Al 0.6 Ga 0.4 As space layer 6 is grown on quantum dot active region layer 5, p-Al 0.98 Ga 0.02 As oxidation confinement layer 7 in Al 0.6 Ga 0.4 As grows on space layer 6, Al 0.6 Ga 0.4 As space layer 8 in p-Al 0.98 Ga 0.02 p-Al grows on As oxide confinement layer 7. 0.05 Ga 0.95 As tunnel layer 9 in Al 0.6 Ga 0.4 n-GaAs tunnel junction 10 grows on p-Al space layer 8. 0.05 Ga 0.95 As grows on tunnel layer 9, Al 0.6 Ga 0.4 As space layer 11 is grown on n-GaAs tunnel junction layer 10, quantum dot active region layer 12 is grown on Al 0.6 Ga 0.4 As grows on space layer 11, Al 0.6 Ga 0.4 As space layer 13 is grown on quantum dot active region layer 12, p-Al 0.98 Ga 0.02 As oxide confinement layer 14 in Al 0.6 Ga 0.4 A p-distributed Bragg mirror 15 is grown on p-Al space layer 13. 0.98 Ga 0.02 As oxide confinement layer 14 is grown, and p-GaAs capping layer 16 is grown on p-distributed Bragg mirror 15.

[0047] Quantum dot active region layer 5, Al 0.6 Ga 0.4 As spatial layer 6, p-Al 0.98 Ga 0.02 As oxidation confinement layer 7, Al 0.6 Ga 0.4 As spatial layer 8, p-Al 0.05 Ga 0.95 As tunneling layer 9, n-GaAs tunneling layer 10 and Al 0.6 Ga 0.4After As space layer 11 is grown sequentially, it is grown in the same order three times to form four cyclic structures. The quantum dot active region layer 5 in the first cyclic structure is in Al 0.6 Ga 0.4 As is grown on layer 4, and the quantum dot active region layer 5 in the other three loop structures is at the end of the previous loop structure. 0.6 Ga 0.4 As grows on space layer 11, such as Figure 1 As shown.

[0048] The n-distributed Bragg mirror 3 includes 36 n-GaAs high-refractive-index layers and 35 Al layers. 0.9 Ga 0.1 As low refractive index layer, n-GaAs high refractive index layer and Al 0.9 Ga 0.1 As low-refractive-index layers are grown alternately, the n-distributed Bragg mirror 3 starts growing from the n-GaAs buffer layer 2, with Al as the initial growth stage. x Ga 1-x As component graded layer, in one growth cycle, Al is successively formed. x Ga 1-x As composition graded layer, n-GaAs high refractive index layer, Al x Ga 1-x As component gradient layer, Al 0.9 Ga 0.1 After 35 growth cycles of the low-refractive-index As layer, a second half-cycle is grown to form the high-refractive-index n-GaAs layer, thus ending the growth of the n-distributed Bragg mirror 3; the p-distributed Bragg mirror 15 comprises 14 pairs of n-GaAs high-refractive-index layers and Al... 0.9 Ga 0.1 As a low refractive index layer, p-distributed Bragg mirror 15 from p-Al 0.98 Ga 0.02 As oxide confinement layer 14 begins to grow from Al. x Ga 1-x As component graded layer, in one growth cycle, Al is successively formed. x Ga 1-x As composition graded layer, n-GaAs high refractive index layer, Al x Ga 1-x As component gradient layer, Al 0.9 Ga 0.1 As low refractive index layer; n-GaAs high refractive index layer and Al 0.9 Ga 0.1 Al is set between the low refractive index layers. x Ga 1-x As component graded layer, Al x Ga1-x In the As-component graded layer, the Al component is graded, with a maximum value of 0.9 and a minimum value greater than 0; the Ga component is graded, with a maximum value of 1 and a minimum value of 0.1. x Ga 1-x In the As-component graded layer, the Al component increases linearly from the high-refractive-index layer to the low-refractive-index layer, while the Ga component decreases linearly from the high-refractive-index layer to the low-refractive-index layer.

[0049] The n-distributed Bragg reflector 3 starts from the n-GaAs buffer layer 2 and grows along the direction, with each cycle consisting of Al layers with a thickness of 20 nm. x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0 to 0.9, and the n-type doping concentration is 2.5 × 10⁻⁶. 18 cm -3 Al with a thickness of 86nm 0.9 Ga 0.1 As a low-refractive-index layer, the n-type doping concentration is 2 × 10⁻⁶. 18 cm -3 ; 20nm thick Al x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0.9 to 0, and the n-type doping concentration is 2.5 × 10⁻⁶. 18 cm -3 A 72 nm thick GaAs high-refractive-index layer with an n-type doping concentration of 2 × 10⁻⁶. 18 cm -3 It grows over 35.5 cycles.

[0050] p-distributed Bragg mirror 15 self-p-Al 0.98 Ga 0.02 Starting from the As oxide confinement layer 14, one cycle along the growth direction consists of Al layers with a thickness of 20 nm. x Ga 1-x An As composition graded layer, where x is a linear gradient from 0.9 to 0, and the p-type doping concentration is 6 × 10⁻⁶. 18 cm -3 A 72 nm thick GaAs high-refractive-index layer with a p-type doping concentration of 6 × 10⁻⁶. 17 cm -3 ; 20nm thick Al x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0 to 0.9, and the p-type doping concentration is 6 × 10⁻⁶. 18 cm -3 Al with a thickness of 86nm 0.9 Ga 0.1 As a low-refractive-index layer, the p-type doping concentration is 6 × 10⁻⁶. 17 cm-3 It grows in 14 cycles.

[0051] The quantum dot active region layer 5 consists of two GaAs layers with a thickness of 10 nm. 0.855 P 0.145 Barrier layer, consisting of two GaAs layers 0.855 P 0.145 In layers with a thickness of 8 nm are sequentially arranged between the barrier layers. 0.05 Ga 0.95 As wetting layer, In 0.52 Ga 0.48 As quantum dot layer, In with a thickness of 8nm 0.05 Ga 0.95 As quantum dot capping layer, In with a thickness of 8nm 0.05 Ga 0.95 As wetting layer.

[0052] This invention also discloses a method for fabricating a vertical-cavity surface-emitting laser structure with a multi-junction cascaded quantum dot active region as described above, specifically including the following steps:

[0053] Step 1. Clean the surface of n-GaAs substrate 1: Introduce hydrogen gas and keep the reaction chamber temperature at 700-740℃ for 5-15 minutes to clean off particulate contaminants on the surface of n-GaAs substrate 1 and remove oxygen atoms from the surface of n-GaAs substrate 1.

[0054] Step 2. Growth of n-GaAs buffer layer 2: The reaction chamber temperature is reduced to 650–680℃, the trimethylgallium flow rate is 90 sccm, the arsenane flow rate is 440 sccm, the silane flow rate is 50–100 sccm, the growth thickness is 500 nm, and the n-type doping concentration is 2 × 10⁻⁶. 18 cm -3 .

[0055] Step 3. Growth of n-distributed Bragg reflectors: The reaction chamber temperature is maintained at 650–680 °C, and Al layers with a thickness of 20 nm are grown sequentially in one cycle using n-distributed Bragg reflectors. x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0 to 0.9, and the n-type doping concentration is 2.5 × 10⁻⁶. 18 cm -3 Al with a thickness of 86nm 0.9 Ga 0.1 As a low-refractive-index layer, the n-type doping concentration is 2 × 10⁻⁶. 18 cm -3 ; 20nm thick Al x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0.9 to 0, and the n-type doping concentration is 2.5 × 10⁻⁶.18 cm -3 A 72 nm thick GaAs high-refractive-index layer with an n-type doping concentration of 2 × 10⁻⁶. 18 cm -3 The growth cycle consisted of 35.5 cycles, with the overall doping concentration controlled by adjusting the SiH4 flow rate; the final half-cycle was performed on Al... 0.9 Ga 0.1 The growth of the n-distributed Bragg reflector 3 is completed by the low refractive index layer, and the overall doping concentration is controlled by adjusting the SiH4 flow rate.

[0056] Step 4.Al 0.6 Ga 0.4 As space layer 4 growth: The reaction chamber temperature was maintained at 650-680℃, the flow rate of trimethylgallium was 55 sccm, the flow rate of trimethylaluminum was 125 sccm, the flow rate of arsenane was 440 sccm, and the growth thickness was 200 nm.

[0057] Step 5. Growth of quantum dot active region layer 5: GaAs 0.855 P 0.145 Barrier layer growth: The reaction chamber temperature was kept constant, the trimethylgallium flow rate was 45 sccm, the arsine flow rate was 800–1500 sccm, the phosphine flow rate was 300–500 sccm, and the growth time was 36 seconds, in Al 0.6 Ga 0.4 GaAs with a thickness of 10 nm is grown on As space layer 4. 0.855 P 0.145 Barrier layer.

[0058] In 0.05 Ga 0.95 As wetting layer growth: Temperature increased to 680–700℃, trimethylgallium flow rate was 64 sccm, trimethylindium flow rate was 50 sccm, arsine flow rate was 1000–2000 sccm, and growth time was 18 seconds. 0.855 As 0.145 An 8 nm thick InGaAs wetting layer is grown on the P-barrier layer.

[0059] In 0.52 Ga 0.48 As quantum dot layer growth: Temperature is kept constant; trimethylgallium flux is 64 sccm; trimethylindium flux is 240 sccm; arsine flux is 100–200 sccm for 3 seconds; temperature is kept constant; then the inflow of trimethylgallium and trimethylindium is stopped for 3 seconds to form In. 0.52 Ga 0.48 As quantum dots.

[0060] In 0.52 Ga 0.48As quantum dot capping layer growth: Temperature remained constant; trimethylgallium flux was 64 sccm; trimethylindium flux was 240 sccm; arsine flux was 1000–2000 sccm; growth time was 5 seconds; and the growth thickness was 8 nm. 0.05 Ga 0.95 As capping layer.

[0061] In 0.05 Ga 0.95 As wetting layer growth: The reaction chamber temperature was raised to 680–700℃, the trimethylgallium flow rate was 64 sccm, the trimethylindium flow rate was 50 sccm, the arsine flow rate was 1000–2000 sccm, and the growth time was 18 seconds. 0.52 Ga 0.48 An 8nm thick In nanofiber is grown on an As quantum dot capping layer. 0.05 Ga 0.95 As wetting layer.

[0062] GaAs 0.855 P 0.145 Barrier layer growth: The reaction chamber temperature was kept constant, the trimethylgallium flow rate was 45 sccm, the arsine flow rate was 800–1500 sccm, the phosphine flow rate was 300–500 sccm, and the growth time was 36 seconds. 0.05 Ga 0.95 GaAs with a thickness of 10 nm is grown on the As wetting layer. 0.855 P 0.145 Barrier layer.

[0063] Step 6.Al 0.6 Ga 0.4 As spatial layer 6 growth: with Al in step 4 0.6 Ga 0.4 The As space layer 4 was grown under the same conditions, with a thickness of 264 nm. Five Al atoms were added. 0.6 Ga 0.4 The purpose of varying the thickness of the space layers is to ensure that the thickness of the resonant cavity is an integer multiple of the wavelength.

[0064] Step 7. p-Al 0.98 Ga 0.02 As oxide confinement layer 7 growth: The growth process is as follows: 1. Growth temperature is 650–680℃, trimethylgallium flux is 55 sccm, trimethylaluminum flux is 125 sccm, arsine flux is 440 sccm, carbon tetrabromide flux is 10–25 sccm, growth thickness is 30 nm, and p-doping concentration is 6 × 10⁻⁶. 17 cm -3 .

[0065] Step 8.Al 0.6 Ga 0.4As spatial layer 8 growth: with Al in step 4 0.6 Ga 0.4 The As space layer (4) was grown under the same conditions, with a growth thickness of 180 nm.

[0066] Step 9. p-Al 0.05 Ga 0.95 As tunnel junction 9 growth: growth temperature 650–680℃, trimethylgallium flux 97 sccm, trimethylaluminum flux 28 sccm, arsine flux 1160 sccm, carbon tetrabromide flux 10–25 sccm, growth thickness 20 nm, p-type doping concentration 10 × 10⁻⁶. 19 cm -3 .

[0067] Step 10. Growth of n-GaAs tunnel junction layer 10: Temperature reduced to 550–650 °C, trimethylgallium flux of 90 sccm, arsenane flux of 440 sccm, silane flux of 50–100 sccm, growth thickness of 20 nm, and n-type doping concentration of 3 × 10⁻⁶. 19 cm -3 .

[0068] Step 11.Al 0.6 Ga 0.4 As spatial layer 11 growth: Same as step 6;

[0069] Step 12. Repeat steps 5 through 11 three times; at this point, the quantum dot active region layer 5 and Al... 0.6 Ga 0.4 As spatial layer 6, p-Al 0.98 Ga 0.02 As oxidation confinement layer 7, Al 0.6 Ga 0.4 As spatial layer 8, p-Al 0.05 Ga 0.95 As tunneling layer 9, n-GaAs tunneling layer 10 and Al 0.6 Ga 0.4 As spatial layer 11 forms 4 loop structures.

[0070] Step 13. Growth of quantum dot active region layer 12: The process is the same as that of quantum dot active region layer 5 in step 5.

[0071] Step 14.Al 0.6 Ga 0.4 As space layer 13 growth: with Al in step 4 0.6 Ga 0.4 The As space layer 4 was grown under the same conditions, with a thickness of 200 nm.

[0072] Step 15. p-Al0.98 Ga 0.02 As oxide confinement layer 14 growth: Same as step 7.

[0073] Step 16. Growth of p-distributed Bragg reflector 15: The growth temperature is 680℃ to control the Zn source doping amount, in order to control p-Al 0.98 Ga 0.02 The As oxide confinement layer 14 and the p-GaAs capping layer 16 are doped at the same doping level. For the p-GaAs capping layer 16, the DEZn flux is 5 sccm, and for the p-Al... 0.98 Ga 0.02 As oxide confinement layer 14, DEZn source flux of 50 sccm, and p-distributed Bragg mirror sequentially growing Al layers with a thickness of 20 nm per cycle. x Ga 1-x An As composition graded layer, where x is a linear gradient from 0.9 to 0, and the p-type doping concentration is 6 × 10⁻⁶. 18 cm -3 A 72 nm thick GaAs high-refractive-index layer with a p-type doping concentration of 6 × 10⁻⁶. 17 cm -3 ; 20nm thick Al x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0 to 0.9, and the p-type doping concentration is 6 × 10⁻⁶. 18 cm -3 Al with a thickness of 86nm 0.9 Ga 0.1 As a low-refractive-index layer, the p-type doping concentration is 6 × 10⁻⁶. 17 cm -3 It grows in 14 cycles.

[0074] Step 17. Growth of p-GaAs capping layer 16: Temperature reduced to 550–650 °C, trimethylgallium flux of 90 sccm, arsenane flux of 440 sccm, carbon tetrabromide flux of 10–25 sccm, growth thickness of 5 nm, p-type doping concentration greater than 1 × 10⁻⁶ 19 cm -3 .

[0075] Multiple quantum dot active regions are connected in series through heavily doped reverse tunnel junctions into the same resonant cavity. A schematic diagram of the energy band structure of a multi-junction cascaded quantum dot active region is shown below. Figure 3 As shown, without increasing the emitting area, reducing the carrier concentration in the active region improves the carrier confinement capability, thereby reducing nonradiative recombination in the epitaxial structure, which in turn reduces the threshold current and improves the output power and electro-optical conversion efficiency. By adding a tunnel junction structure, it is possible to achieve recombination of one electron with multiple holes during transmission, thereby improving the radiative recombination efficiency. Figure 4(a) indicates that under 30mA conditions, the power of a single-junction quantum dot vertical-cavity surface-emitting laser is 31.1mW, and the power of a five-junction quantum dot vertical-cavity surface-emitting laser reaches 188.1mW. Figure 4 (b) shows that the peak electro-optic conversion efficiency of the single-junction quantum dot vertical-cavity surface-emitting laser is 44.4%, and the peak electro-optic conversion efficiency of the five-junction quantum dot vertical-cavity surface-emitting laser is 58.4%; at an injection current of 20 mA, the power of the five-junction vertical-cavity surface-emitting laser is about 85% higher than that of the three-junction vertical-cavity surface-emitting laser.

[0076] The tunnel junction, which connects multiple quantum dot active regions, should be heavily doped (>10) in the p+ and n+ semiconductor layers with high degeneracy levels. 19 cm -3 To provide high tunneling current with the lowest voltage drop, the multi-quantum-well active region needs to be placed at the antinode of the standing wave field to maximize optical gain. Simultaneously, the oxide layer and tunnel junction should be placed at the nodes of the standing wave field to reduce current crowding at the oxide layer edge and free carrier absorption loss caused by the heavily doped tunnel junction, respectively. To meet these requirements, the optical distance between each active region should be at least 1λ, where λ represents the wavelength of light. Furthermore, to minimize the impact of oxide layer stress accumulation and tunnel junction impurity diffusion on the active region, adjusting the optical distance between adjacent active regions to 2λ is even more effective.

[0077] Any aspects of this invention not described in detail are well-known to those skilled in the art.

[0078] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications and equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A vertical-cavity surface-emitting laser structure with a multi-junction cascaded quantum dot active region, characterized in that: Includes an n-GaAs substrate (1) and an n-GaAs buffer layer (2), an n-distributed Bragg mirror (3), and Al, arranged sequentially along the growth direction. 0.6 Ga 0.4 As space layer (4), quantum dot active region layer (5), Al 0.6 Ga 0.4 As space layer (6), p-Al 0.98 Ga 0.02 As oxide confinement layer (7), Al 0.6 Ga 0.4 As space layer (8), p-Al 0.05 Ga 0.95 As tunneling layer (9), n-GaAs tunneling layer (10), Al 0.6 Ga 0.4 As space layer (11), quantum dot active region layer (12), Al 0.6 Ga 0.4 As space layer (13), p-Al 0.98 Ga 0.02 As oxide confinement layer (14), p-distributed Bragg mirror (15), and p-GaAs capping layer (16), wherein: The n-GaAs buffer layer (2) is grown on the n-GaAs substrate (1), the n-distributed Bragg mirror (3) is grown on the n-GaAs buffer layer (2), and the Al 0.6 Ga 0.4 The As space layer (4) is grown on an n-distributed Bragg mirror (3), and the quantum dot active region layer (5) is grown on an Al 0.6 Ga 0.4 As grows on the space layer (4), the Al 0.6 Ga 0.4 The As space layer (6) is grown on the quantum dot active region layer (5), wherein the p-Al 0.98 Ga 0.02 As oxide confinement layer (7) in Al 0.6 Ga 0.4 As grows on the space layer (6), the Al 0.6 Ga 0.4 As space layer (8) in p-Al 0.98 Ga 0.02 p-Al grows on the As oxide confinement layer (7). 0.05 Ga 0.95 As tunnel layer (9) in Al 0.6 Ga 0.4 The n-GaAs tunnel junction (10) is grown on the As space layer (8) and is located on the p-Al space layer (8). 0.05 Ga 0.95 As grows on the tunnel layer (9), the Al 0.6 Ga 0.4 An As space layer (11) is grown on an n-GaAs tunnel junction layer (10), and the quantum dot active region layer (12) is grown on an Al... 0.6 Ga 0.4 As grown on the space layer (11), the Al 0.6 Ga 0.4 The As space layer (13) is grown on the quantum dot active region layer (12), the p-Al 0.98 Ga 0.02 As oxide confinement layer (14) in Al 0.6 Ga 0.4 The p-distributed Bragg mirror (15) is grown on the As space layer (13) and is grown on p-Al. 0.98 Ga 0.02 The p-GaAs capping layer (16) is grown on a p-distributed Bragg mirror (15).

2. The vertical-cavity surface-emitting laser structure of the multi-junction cascaded quantum dot active region according to claim 1, characterized in that: The quantum dot active region layer (5), Al 0.6 Ga 0.4 As space layer (6), p-Al 0.98 Ga 0.02 As oxide confinement layer (7), Al 0.6 Ga 0.4 As space layer (8), p-Al 0.05 Ga 0.95 As tunneling layer (9), n-GaAs tunneling layer (10) and Al 0.6 Ga 0.4 After the As space layer (11) grows sequentially, it will grow in the same order three times.

3. The vertical-cavity surface-emitting laser structure of the multi-junction cascaded quantum dot active region according to claim 1, characterized in that: The n-distributed Bragg mirror (3) comprises 36 n-GaAs high refractive index layers and 35 Al layers. 0.9 Ga 0.1 As low refractive index layer, n-GaAs high refractive index layer and Al 0.9 Ga 0.1 As low-refractive-index layers are grown alternately, the n-distributed Bragg mirror (3) starts growing from the n-GaAs buffer layer (2) with Al as the initial growth point. x Ga 1-x As component gradient layer; The p-distributed Bragg mirror (15) comprises 14 pairs of p-GaAs high refractive index layers and Al 0.9 Ga 0.1 As a low refractive index layer, the p-distributed Bragg mirror (15) is derived from p-Al. 0.98 Ga 0.02 The growth of the As oxide confinement layer (14) begins with Al. x Ga 1-x As component gradient layer; n-GaAs high refractive index layer and Al 0.9 Ga 0.1 Al is set between the low refractive index layers. x Ga 1-x As component graded layer, Al x Ga 1- x The Al component in the As component gradient layer is gradient, with a maximum value of 0.9 and a minimum value greater than 0. The Ga component varies gradually, with a maximum value of 1 and a minimum value of 0.

1.

4. The vertical-cavity surface-emitting laser structure of the multi-junction cascaded quantum dot active region according to claim 3, characterized in that: The n-distributed Bragg reflector (3) consists of Al layers with a thickness of 20 nm, starting from the n-GaAs buffer layer (2) and growing in one cycle along the growth direction. x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0 to 0.9, and the n-type doping concentration is 2.5 × 10⁻⁶. 18 cm -3 ; 86 nm thick Al 0.9 Ga 0.1 As a low-refractive-index layer, the n-type doping concentration is 2 × 10⁻⁶. 18 cm -3 ; 20 nm thick Al x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0.9 to 0, and the n-type doping concentration is 2.5 × 10⁻⁶. 18 cm -3 A 72 nm thick GaAs high-refractive-index layer with an n-type doping concentration of 2 × 10⁻⁶. 18 cm -3 It grows over 35.5 cycles.

5. The vertical-cavity surface-emitting laser structure of the multi-junction cascaded quantum dot active region according to claim 3, characterized in that: The p-distributed Bragg mirror (15) is from p-Al 0.98 Ga 0.02 The As oxide confinement layer (14) begins with an Al layer of 20 nm thickness along the growth direction in one cycle. x Ga 1-x An As composition graded layer, where x is a linear gradient from 0.9 to 0, and the p-type doping concentration is 6 × 10⁻⁶. 18 cm -3 A 72 nm thick GaAs high-refractive-index layer with a p-type doping concentration of 6 × 10⁻⁶. 17 cm -3 Al with a thickness of 20 nm x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0 to 0.9, and the p-type doping concentration is 6 × 10⁻⁶. 18 cm -3 ; 86nm thick Al 0.9 Ga 0.1 As a low-refractive-index layer, the p-type doping concentration is 6 × 10⁻⁶ 17 cm -3 It grows in 14 cycles.

6. The vertical-cavity surface-emitting laser structure of the multi-junction cascaded quantum dot active region according to claim 1, characterized in that: The quantum dot active region layer (5) comprises two GaAs layers with a thickness of 10 nm. 0.855 P 0.145 Barrier layer, consisting of two GaAs layers 0.855 P 0.145 In layers with a thickness of 8 nm are sequentially arranged between the barrier layers. 0.05 Ga 0.95 As wetting layer, In 0.52 Ga 0.48 As quantum dot layer, In with a thickness of 8 nm 0.05 Ga 0.95 As quantum dot capping layer, In with a thickness of 8nm 0.05 Ga 0.95 As wetting layer.

7. A method for fabricating a vertical-cavity surface-emitting laser structure with a multi-junction cascaded quantum dot active region as described in any one of claims 1 to 6, characterized in that, Specifically, the following steps are included: Step 1. Clean the surface of n-GaAs substrate (1): Introduce hydrogen gas and keep the reaction chamber temperature at 700-740℃ for 5-15 minutes to clean off particulate contaminants on the surface of n-GaAs substrate (1) and remove oxygen atoms from the surface of n-GaAs substrate (1). Step 2. n-GaAs buffer layer (2) growth: The reaction chamber temperature is reduced to 650-680℃, the trimethylgallium flow rate is 90 sccm, the arsenane flow rate is 440 sccm, the silane flow rate is 50-100 sccm, the growth thickness is 500 nm, and the n-type doping concentration is 2×10 18 cm -3 ; Step 3. n-distributed Bragg reflector (3) growth: The reaction chamber temperature is maintained at 650-680℃, and an Al layer with a thickness of 20nm is grown sequentially in one cycle of the n-distributed Bragg reflector. x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0 to 0.9, and the n-type doping concentration is 2.5 × 10⁻⁶. 18 cm -3 ; 86nm thick Al 0.9 Ga 0.1 As a low-refractive-index layer, the n-type doping concentration is 2 × 10⁻⁶ 18 cm -3 ; 20nm thick Al x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0.9 to 0, and the n-type doping concentration is 2.5 × 10⁻⁶. 18 cm -3 A 72 nm thick GaAs high-refractive-index layer with an n-type doping concentration of 2 × 10⁻⁶. 18 cm -3 The growth cycle was repeated for 35.5 cycles, and the overall doping concentration was controlled by adjusting the SiH4 flow rate. Step 4. Al 0.6 Ga 0.4 As space layer (4) growth: The reaction chamber temperature is maintained at 650-680℃, the flow rate of trimethylgallium is 55 sccm, the flow rate of trimethylaluminum is 125 sccm, the flow rate of arsine is 440 sccm, and the growth thickness is 200 nm; Step 5. Growth of the quantum dot active region layer (5): GaAs 0.855 P 0.145 Barrier layer growth: The reaction chamber temperature was kept constant, the trimethylgallium flow rate was 45 sccm, the arsine flow rate was 800~1500 sccm, the phosphine flow rate was 300~500 sccm, and the growth time was 36 seconds, in Al 0.6 Ga 0.4 GaAs with a thickness of 10 nm is grown on the As space layer (4). 0.855 P 0.145 Barrier layer; In 0.05 Ga 0.95 As wetting layer growth: Temperature increased to 680~700 ℃, trimethylgallium flow rate was 64 sccm, trimethylindium flow rate was 50 sccm, arsine flow rate was 1000~2000 sccm, and growth time was 18 seconds. 0.855 As 0.145 An 8 nm thick InGaAs wetting layer is grown on the P-barrier layer. In 0.52 Ga 0.48 As quantum dot layer growth: Temperature remains constant; trimethylgallium flux is 64 sccm; trimethylindium flux is 240 sccm; arsine flux is 100-200 sccm for 3 seconds; temperature remains constant; then the inflow of trimethylgallium and trimethylindium is stopped for 3 seconds to form In. 0.52 Ga 0.48 As quantum dots; In 0.52 Ga 0.48 As quantum dot capping layer growth: Temperature remained constant; trimethylgallium flux was 64 sccm; trimethylindium flux was 240 sccm; arsine flux was 1000–2000 sccm; growth time was 5 seconds; and the growth thickness was 8 nm. 0.05 Ga 0.95 As capping layer; In 0.05 Ga 0.95 As wetting layer growth: The reaction chamber temperature was raised to 680~700 ℃, the trimethylgallium flow rate was 64 sccm, the trimethylindium flow rate was 50 sccm, the arsine flow rate was 1000~2000 sccm, and the growth time was 18 seconds. 0.52 Ga 0.48 An 8 nm thick In layer is grown on an As quantum dot capping layer. 0.05 Ga 0.95 As wetting layer; GaAs 0.855 P 0.145 Barrier layer growth: The reaction chamber temperature was kept constant, the trimethylgallium flow rate was 45 sccm, the arsine flow rate was 800~1500 sccm, the phosphine flow rate was 300~500 sccm, and the growth time was 36 seconds. 0.05 Ga 0.95 GaAs with a thickness of 10 nm is grown on the As wetting layer. 0.855 P 0.145 Barrier layer; Step 6. Al 0.6 Ga 0.4 As space layer (6) growth: with Al from step 4 0.6 Ga 0.4 The As space layer (4) was grown under the same conditions, with a growth thickness of 264 nm. Step 7. p-Al 0.98 Ga 0.02 As oxide confinement layer (7) growth: The growth process is as follows: growth temperature is 650~680 ℃, trimethylgallium flux is 55 sccm, trimethylaluminum flux is 125 sccm, arsine flux is 440 sccm, carbon tetrabromide flux is 10~25 sccm, growth thickness is 30 nm, and p doping concentration is 6×10 17 cm -3 ; Step 8. Al 0.6 Ga 0.4 As space layer (8) growth: with Al from step 4 0.6 Ga 0.4 The As space layer (4) was grown under the same conditions, with a growth thickness of 180 nm. Step 9. p-Al 0.05 Ga 0.95 As tunnel junction (9) growth: growth temperature was 650~680 ℃, trimethylgallium flux was 97 sccm, trimethylaluminum flux was 28 sccm, arsine flux was 1160 sccm, carbon tetrabromide flux was 10~25 sccm, growth thickness was 20 nm, and p-type doping concentration was 10×10 19 cm -3 ; Step 10. n-GaAs tunnel junction layer (10) growth: Temperature reduced to 550~650 ℃, trimethylgallium flux of 90 sccm, arsenane flux of 440 sccm, silane flux of 50~100 sccm, growth thickness of 20 nm, n-type doping concentration of 3×10 19 cm -3 ; Step 11. Al 0.6 Ga 0.4 As space layer (11) growth: Same as step 6; Step 12. Repeat steps 5 through 11 three times; Step 13. Growth of the quantum dot active region layer (12): The growth process is the same as that of the quantum dot active region layer (5) in step 5; Step 14. Al 0.6 Ga 0.4 As space layer (13) growth: with Al from step 4 0.6 Ga 0.4 The As space layer (4) was grown under the same conditions, with a growth thickness of 200 nm. Step 15. p-Al 0.98 Ga 0.02 As oxide confinement layer (14) growth: same as step 7; Step 16. Growth of p-distributed Bragg mirror (15): The growth temperature is 680 ℃ to control the Zn source doping amount, in order to control p-Al 0.98 Ga 0.02 The As oxide confinement layer (14) and the p-GaAs capping layer (16) are doped at the same doping level. For the p-GaAs capping layer (16), the DEZn flux is 5 sccm, and for the p-Al... 0.98 Ga 0.02 As oxide confinement layer (14), DEZn source flux is 50 sccm, and p-distributed Bragg mirrors are used to sequentially grow Al layers with a thickness of 20 nm in one cycle. x Ga 1-x An As composition graded layer, where x is a linear gradient from 0.9 to 0, and the p-type doping concentration is 6 × 10⁻⁶. 18 cm -3 A 72 nm thick GaAs high-refractive-index layer with a p-type doping concentration of 6 × 10⁻⁶. 17 cm -3 Al with a thickness of 20 nm x Ga 1-x An As composition-gradient layer, where x is a linear gradient from 0 to 0.9, and the p-type doping concentration is 6 × 10⁻⁶. 18 cm -3 ; 86 nm thick Al 0.9 Ga 0.1 As a low-refractive-index layer, the p-type doping concentration is 6 × 10⁻⁶. 17 cm -3 ; It grows in 14 cycles; Step 17. p-GaAs capping layer (16) growth: Temperature reduced to 550~650 ℃, trimethylgallium flux of 90 sccm, arsenane flux of 440 sccm, carbon tetrabromide flux of 10~25 sccm, growth thickness of 5 nm, p-type doping concentration greater than 1×10 19 cm -3 .

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