Multi-junction cascade quantum dot vertical cavity surface emitting laser structure and preparation method thereof

Abstract

The invention relates to the technical field of lasers of quantum dot active regions, and aims to solve the problems that a vertical cavity surface emitting laser taking a quantum well as an active region is generally poor in temperature stability, and a unijunction quantum dot vertical cavity surface emitting laser is low in output power and low in electro-optical conversion efficiency. According to the multi-junction cascade quantum dot vertical cavity surface emitting laser structure and the preparation method thereof, an oxidation limiting type vertical cavity surface emitting laser with the multi-junction cascade quantum dot active region structure not only can improve the limiting capability on current carriers, but also can effectively reduce photoelectric loss, reduce energy loss and improve the photoelectric conversion efficiency. According to the quantum dot active region structure, the limiting capacity and temperature stability of active region carriers are improved, the active regions are connected in series in the same resonant cavity through tunnel junctions, and the output power and the electro-optical conversion efficiency are remarkably improved while the resistance and the absorption loss are not increased by times.

Description

Technical Field

[0001] The invention relates to the technical field of lasers in quantum dot active regions, in particular to a multi-junction cascade quantum dot vertical cavity surface emitting laser structure and a preparation method thereof. Background Art

[0002] As the core component of the vertical cavity surface laser, the structure of the active region has a significant impact on its output characteristics. The active region of the oxidation-limited vertical cavity surface emitting laser usually adopts a quantum well structure. This type of structure has a high carrier injection efficiency. However, due to its poor ability to restrict carriers, it generally has the problem of low radiative recombination rate. In addition, when the oxidation aperture of the oxidation-limited vertical cavity surface emitting laser is larger, its power conversion efficiency at room temperature is higher, but its power loss is also more serious at high ambient temperature. Therefore, the temperature stability of the vertical cavity surface emitting laser with quantum well as the active region is usually poor. When the dimension of the active region is reduced, its effective active volume is smaller, the carrier localization is stronger, and the temperature stability is also higher. Therefore, the quantum well active region structure usually has the advantages of high radiative recombination rate, low threshold current and high temperature stability. However, the carrier injection efficiency of the single-junction quantum dot vertical cavity surface emitting laser is low, so it still has problems such as low output power and low electro-optical conversion efficiency.

[0003] The weak carrier confinement capability of the quantum well active region structure and the low injection efficiency of the quantum dot active region structure are the key issues that affect the further improvement of the output power and electro-optical conversion efficiency of the 1.3μm oxide-confined vertical cavity surface emitting laser. The quantum well active region structure has high carrier injection efficiency and low radiative recombination rate, so its non-radiative radiation is usually high, which leads to serious photoelectric loss and low temperature stability. The quantum dot active region structure has a significant improvement in radiative recombination efficiency, a lower threshold current and high temperature stability due to its enhanced three-dimensional carrier confinement capability. However, due to its low injection efficiency and serious energy loss, it is usually limited by low output power and low electro-optical conversion efficiency in long-wavelength band applications. Therefore, designing the active region structure of the oxide-confined vertical cavity surface emitting laser is of great significance to further improve its carrier confinement capability, temperature stability and output characteristics. Summary of the invention

[0004] In view of the problems faced by the current 1.3μm oxidation-confined vertical cavity surface emitting laser, such as weak carrier confinement ability, large photoelectric loss, poor temperature stability and low output power, the purpose of the present invention is to provide a multi-junction cascade quantum dot vertical cavity surface emitting laser structure and a preparation method. The oxidation-confined vertical cavity surface emitting laser with a multi-junction cascade quantum dot active area structure can not only improve the carrier confinement ability, but also effectively reduce photoelectric loss and energy loss. The quantum dot active area structure improves the carrier confinement ability and temperature stability of the active area. The present invention uses a tunnel junction to connect the active area in series in the same resonant cavity, while the resistance and absorption loss are not doubled, and the output power and electro-optical conversion efficiency are significantly improved.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A vertical cavity surface emitting laser structure with a multi-junction cascade quantum dot active region includes an n-GaAs substrate and an n-GaAs buffer layer, an n-distributed Bragg reflector, an Al 0.6 Ga 0.4 As space layer, quantum dot active layer, Al 0.6 Ga 0.4 As space layer, p-Al 0.98 Ga 0.02 As oxidation limiting layer, Al 0.6 Ga 0.4 As space layer, p-Al 0.05 Ga 0.95 As tunnel junction layer, n-GaAs tunnel junction layer, Al 0.6 Ga 0.4 As space layer, quantum dot active layer, Al 0.6 Ga 0.4 As space layer, p-Al 0.98 Ga 0.02 As oxide confinement layer, p-distributed Bragg reflector and p-GaAs cap layer, wherein:

[0007] The n-GaAs buffer layer is grown on the n-GaAs substrate, the n-distributed Bragg reflector is grown on the n-GaAs buffer layer, and the Al 0.6 Ga 0.4 The As spacer layer is grown on the n-distributed Bragg reflector, and the quantum dot active region layer is grown on the Al 0.6 Ga 0.4 As space layer growth, Al 0.6 Ga 0.4 The As spacer layer is grown on the quantum dot active region layer, and the p-Al 0.98 Ga 0.02 As oxidation limiting layer on Al0.6 Ga 0.4 As space layer growth, Al 0.6 Ga 0.4 As space layer in p-Al 0.98 Ga 0.02 As grows on the oxide restriction layer, p-Al 0.05 Ga 0.95 As tunnel junction layer in Al 0.6 Ga 0.4 As space layer, n-GaAs tunnel junction layer is grown on p-Al 0.05 Ga 0.95 As tunnel junction layer is grown on the 0.6 Ga 0.4 The As spacer layer is grown on the n-GaAs tunnel junction layer, and the quantum dot active region layer is grown on the Al 0.6 Ga 0.4 As space layer growth, Al 0.6 Ga 0.4 The As spacer layer is grown on the quantum dot active region layer, and the p-Al 0.98 Ga 0.02 As oxidation limiting layer on Al 0.6 Ga 0.4 As space layer, p-distributed Bragg reflector is grown on p-Al 0.98 Ga 0.02 As oxide confinement layer and p-GaAs capping layer grown on p-distributed Bragg reflector.

[0008] Furthermore, the quantum dot active layer, Al 0.6 Ga 0.4 As space layer, p-Al 0.98 Ga 0.02 As oxidation limiting layer, Al 0.6 Ga 0.4 As space layer, p-Al 0.05 Ga 0.95 As tunnel junction layer, n-GaAs tunnel junction layer and Al 0.6 Ga 0.4 After the As space layers are grown in sequence, they are cycled and grown three times in this order.

[0009] Furthermore, the n-distributed Bragg reflector includes 36 n-GaAs high refractive index layers and 35 Al 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, and the n-distributed Bragg reflector starts to grow from the n-GaAs buffer layer. x Ga1-x As composition gradient layer; the p-distributed Bragg reflector includes 14 pairs of n-GaAs high refractive index layers and Al 0.9 Ga 0.1 As low refractive index layer, p-distributed Bragg reflector from p-Al 0.98 Ga 0.02 The growth of the As oxidation restriction layer starts from Al x Ga 1-x As composition gradient layer; n-GaAs high refractive index layer and Al 0.9 Ga 0.1 AlAs is set between the low refractive index layers x Ga 1-x As composition gradient layer, Al x Ga 1-x The Al component in the As component gradient layer changes gradually, with the maximum value of the Al component being 0.9 and the minimum value being greater than 0; the Ga component changes gradually, with the maximum value of the Ga component being 1 and the minimum value being 0.1.

[0010] Furthermore, the n-distributed Bragg reflector is formed by a 20 nm thick Al layer in the growth direction starting from the n-GaAs buffer layer. x Ga 1-x 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 18 cm -3 ; Al with a thickness of 86nm 0.9 Ga 0.1 As low refractive index layer, n-type doping concentration is 2×10 18 cm -3 ; Al with a thickness of 20nm x Ga 1-x 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 18 cm -3 ; GaAs high refractive index layer with a thickness of 72nm and an n-type doping concentration of 2×10 18 cm -3 , growing for 35.5 cycles.

[0011] Furthermore, the p-distributed Bragg reflector is made from p-Al 0.98 Ga 0.02 The As oxidation restriction layer starts to grow in the direction of the growth, and then becomes Al with a thickness of 20 nm. x Ga 1-x As composition gradient layer, where x is a linear gradient from 0.9 to 0, and the p-type doping concentration is 6×10 18 cm -3; GaAs high refractive index layer with a thickness of 72nm and a p-type doping concentration of 6×10 17 cm -3 ; Al with a thickness of 20nm x Ga 1-x As composition gradient layer, where x is a linear gradient from 0 to 0.9, and the p-type doping concentration is 6×10 18 cm -3 ; Al with a thickness of 86nm 0.9 Ga 0.1 As low refractive index layer, p-type doping concentration is 6×10 17 cm -3 , grow for 14 cycles.

[0012] Furthermore, the quantum dot active region layer includes two layers of GaAs with a thickness of 10 nm. 0.855 P 0.145 Barrier layer, in two layers of GaAs 0.855 P 0.145 In layers with a thickness of 8 nm are placed 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 preparing a vertical cavity surface emitting laser structure with a multi-junction cascade quantum dot active region as described above specifically comprises the following steps:

[0014] Step 1. Cleaning the surface of the n-GaAs substrate: introducing hydrogen gas, with the reaction chamber temperature at 700-740° C., for 5-15 minutes, to clean the surface particle contaminants of the n-GaAs substrate and remove the surface oxygen atoms of the n-GaAs substrate;

[0015] Step 2. n-GaAs buffer layer growth: The reaction chamber temperature dropped to 650-680°C, the trimethylgallium flow rate was 90 sccm, the arsine flow rate was 440 sccm, the silane flow rate was 50-100 sccm, the growth thickness was 500 nm, and the n-type doping concentration was 2×10 18 cm -3 ;

[0016] Step 3. n-distributed Bragg reflector growth: The reaction chamber temperature is maintained at 650-680°C, and the n-distributed Bragg reflector grows Al with a thickness of 20 nm in one cycle. x Ga 1-xAs composition gradient layer, where x is a linear gradient from 0 to 0.9, and the n-type doping concentration is 2.5×10 18 cm -3 ; Al with a thickness of 86nm 0.9 Ga 0.1 As low refractive index layer, n-type doping concentration is 2×10 18 cm -3 ; Al with a thickness of 20nm x Ga 1-x 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 18 cm -3 ; GaAs high refractive index layer with a thickness of 72nm and an n-type doping concentration of 2×10 18 cm -3 ; Cycle growth for 35.5 cycles, and control the overall doping concentration by adjusting the SiH4 flow rate;

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

[0018] Step 5. Growth of quantum dot active layer: GaAs 0.855 P 0.145 Barrier layer growth: The reaction chamber temperature remains unchanged, the trimethylgallium flow rate is 45sccm, the arsine flow rate is 800-1500sccm, the phosphine flow rate is 300-500sccm, the growth time is 36 seconds, and the Al 0.6 Ga 0.4 GaAs with a thickness of 10nm is grown on the As spacer layer 0.855 P 0.145 Barrier layer;

[0019] In 0.05 Ga 0.95 As wetting layer growth: temperature rises to 680-700°C, trimethylgallium flow rate is 64 sccm, trimethylindium flow rate is 50 sccm, arsine flow rate is 1000-2000 sccm, growth time is 18 seconds, in Ga 0.855 As 0.145 An InGaAs wetting layer with a thickness of 8 nm is grown on the P barrier layer;

[0020] In 0.52 Ga 0.48As quantum dot layer growth: keep the temperature constant, the trimethylgallium flow rate is 64sccm, the trimethylindium flow rate is 240sccm, and the arsine flow rate is 100-200sccm. Keep the temperature constant and stop the flow of trimethylgallium and trimethylindium. Keep the flow for 3 seconds to form In 0.52 Ga 0.48 As quantum dots;

[0021] In 0.52 Ga 0.48 As quantum dot cap layer growth: the temperature remains unchanged, the trimethyl gallium flow rate is 64sccm, the trimethyl indium flow rate is 240sccm, the arsine flow rate is 1000-2000sccm, the growth time is 5 seconds, and the growth thickness is 8nm. 0.05 Ga 0.95 As cap layer;

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

[0023] GaAs 0.855 P 0.145 Barrier layer growth: The reaction chamber temperature remains unchanged, the trimethylgallium flow rate is 45 sccm, the arsine flow rate is 800-1500 sccm, the phosphine flow rate is 300-500 sccm, the growth time is 36 seconds, and the In 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: Al in step 4 0.6 Ga 0.4 The growth conditions of the As space layer were the same, and the growth thickness was 264nm;

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

[0026] Step 8.Al 0.6 Ga 0.4 As spatial layer growth: Al in step 4 0.6 Ga 0.4 The growth conditions of the As space layer are the same, and the growth thickness is 180nm;

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

[0028] Step 10. n-GaAs tunnel junction layer growth: the temperature is reduced to 550-650°C, the trimethyl gallium flow rate is 90 sccm, the arsine flow rate is 440 sccm, the silane flow rate is 50-100 sccm, the growth thickness is 20 nm, and the n-type doping concentration is 3×10 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 to 11 three times;

[0031] Step 13. Growth of quantum dot active region layer: the same as the growth process of quantum dot active region layer in step 5;

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

[0033] Step 15. p-Al 0.98 Ga 0.02 As oxide limiting 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 the p-Al 0.98 Ga 0.02 The As oxide limiting layer and the p-GaAs cap layer are doped at the same doping level. For the p-GaAs cap layer, the DEZn flow rate is 5 sccm. For the p-Al 0.98 Ga 0.02 As oxidation limiting layer, DEZn source flow rate is 50sccm, and p-distributed Bragg reflector grows Al with a thickness of 20nm in one cycle. x Ga 1-x As composition gradient layer, where x is a linear gradient from 0.9 to 0, and the p-type doping concentration is 6×10 18 cm -3 ; GaAs high refractive index layer with a thickness of 72nm and a p-type doping concentration of 6×10 17 cm -3 ; Al with a thickness of 20nm x Ga 1-x As composition gradient layer, where x is a linear gradient from 0 to 0.9, and the p-type doping concentration is 6×10 18 cm -3 ; Al with a thickness of 86nm 0.9 Ga 0.1 As low refractive index layer, p-type doping concentration is 6×10 17 cm -3 ; Cyclic growth for 14 cycles;

[0035] Step 17. p-GaAs cap layer growth: the temperature is reduced to 550-650°C, the trimethylgallium flow rate is 90 sccm, the arsine flow rate is 440 sccm, the carbon tetrabromide flow rate is 10-25 sccm, the growth thickness is 5 nm, and the p-type doping concentration is greater than 1×10 19 cm -3 .

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

[0037] The present invention sets the quantum dot size, composition and surface density of the quantum dot active area, reduces the dimension of the active area, makes the active volume smaller, and the carrier localization is stronger, thereby achieving the purpose of improving the radiation recombination efficiency, further reducing the threshold current, and improving the temperature stability; the present invention can not only improve the limiting ability of the carriers, but also effectively reduce the photoelectric loss and reduce the energy loss; the laser prepared by the present invention is a high-power output quantum dot vertical cavity surface emitting laser, the quantum dot active area structure improves the limiting ability and temperature stability of the active area carriers, and multiple quantum dot active areas are connected in series through a highly doped tunnel junction, and the output power is doubled without increasing the light-emitting area. At the same time, the tunnel junction connects multiple active areas in series in the same resonant cavity, and the resistance and absorption loss are not doubled. The present invention can solve the serious problems of carrier leakage, photoelectric loss and energy loss, reduce the non-radiative recombination of the active area, thereby reducing the threshold current and operating voltage of the vertical cavity surface emitting laser, and improving the output power and electro-optical conversion efficiency of the vertical cavity surface emitting laser. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0041] Figure 4 Single-junction, three-junction cascade, and five-junction cascade quantum dot active area vertical cavity surface emitting lasers under room temperature continuous conditions: (a) PI curve; (b) PCE-I curve. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0044] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] like Figures 1 to 4 As shown, the present invention discloses a vertical cavity surface emitting laser structure of a multi-junction cascade quantum dot active region, comprising an n-GaAs substrate 1 and an n-GaAs buffer layer 2, an n-distributed Bragg reflector 3, an Al 0.6 Ga 0.4 As space layer 4, quantum dot active layer 5, Al 0.6 Ga 0.4 As space layer 6, p-Al 0.98 Ga 0.02 As oxidation limiting layer 7, Al 0.6 Ga 0.4 As space layer 8, p-Al 0.05 Ga 0.95 As tunnel junction layer 9, n-GaAs tunnel junction 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 oxidation confinement layer 14, p-distributed Bragg reflector 15 and p-GaAs cap layer 16, wherein:

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

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

[0048] The n-distributed Bragg reflector 3 includes 36 n-GaAs high refractive index layers and 35 Al 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, and the n-distributed Bragg reflector 3 starts to grow from the n-GaAs buffer layer 2. x Ga 1-x As composition gradient layer, in one growth cycle, it is Al x Ga 1-x As composition gradient layer, n-GaAs high refractive index layer, Al x Ga 1-x As composition gradient layer, Al 0.9 Ga 0.1 After 35 cycles of growth, the n-GaAs low refractive index layer is grown for another half cycle to the n-GaAs high refractive index layer, thus completing the growth of the n-distributed Bragg reflector 3; the p-distributed Bragg reflector 15 includes 14 pairs of n-GaAs high refractive index layers and Al 0.9 Ga 0.1 As low refractive index layer, p-distributed Bragg reflector 15 is made of p-Al 0.98 Ga 0.02 The As oxidation limiting layer 14 starts to grow from Al x Ga 1-x As composition gradient layer, in one growth cycle, it is Al x Ga 1-x As composition gradient layer, n-GaAs high refractive index layer, Al x Ga 1-x As composition 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 AlAs is set between the low refractive index layers x Ga 1-x As composition gradient layer, Al x Ga1-x The Al component in the As component gradient layer changes gradually, with the maximum value of Al being 0.9 and the minimum value being greater than 0; the Ga component changes gradually, with the maximum value of Ga being 1 and the minimum value being 0.1. x Ga 1-x The Al component in the As component gradient layer increases linearly from the high refractive index layer to the low refractive index layer, and 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 along the growth direction, and one period is Al with a thickness of 20nm. x Ga 1-x 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 18 cm -3 ; Al with a thickness of 86nm 0.9 Ga 0.1 As low refractive index layer, n-type doping concentration is 2×10 18 cm -3 ; Al with a thickness of 20nm x Ga 1-x 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 18 cm -3 ; GaAs high refractive index layer with a thickness of 72nm and an n-type doping concentration of 2×10 18 cm -3 , growing for 35.5 cycles.

[0050] p-Distributed Bragg Reflector 15 from p-Al 0.98 Ga 0.02 The As oxidation restriction layer 14 starts from the Al2O3 layer with a thickness of 20 nm in a cycle along the growth direction. x Ga 1-x As composition gradient layer, where x is a linear gradient from 0.9 to 0, and the p-type doping concentration is 6×10 18 cm -3 ; GaAs high refractive index layer with a thickness of 72nm and a p-type doping concentration of 6×10 17 cm -3 ; Al with a thickness of 20nm x Ga 1-x As composition gradient layer, where x is a linear gradient from 0 to 0.9, and the p-type doping concentration is 6×10 18 cm -3 ; Al with a thickness of 86nm 0.9 Ga 0.1 As low refractive index layer, p-type doping concentration is 6×10 17 cm-3 , grow for 14 cycles.

[0051] The quantum dot active region layer 5 includes two layers of GaAs with a thickness of 10 nm. 0.855 P 0.145 Barrier layer, in two layers of GaAs 0.855 P 0.145 In layers with a thickness of 8 nm are placed 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] The present invention also discloses a method for preparing a vertical cavity surface emitting laser structure with a multi-junction cascade quantum dot active region as described above, which specifically comprises the following steps:

[0053] Step 1. Cleaning the surface of the n-GaAs substrate 1: introducing hydrogen gas, with the reaction chamber temperature at 700-740° C. for 5-15 minutes, to clean away particle contaminants on the surface of the n-GaAs substrate 1 and remove oxygen atoms on the surface of the n-GaAs substrate 1.

[0054] Step 2. Growth of n-GaAs buffer layer 2: The reaction chamber temperature is reduced to 650-680°C, the trimethylgallium flow rate is 90 sccm, the arsine 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 .

[0055] Step 3. Growth of n-distributed Bragg reflector 3: The temperature of the reaction chamber is maintained at 650-680°C, and the n-distributed Bragg reflector is grown in turn with a thickness of 20 nm. x Ga 1-x 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 18 cm -3 ; Al with a thickness of 86nm 0.9 Ga 0.1 As low refractive index layer, n-type doping concentration is 2×10 18 cm -3 ; Al with a thickness of 20nm x Ga 1-x As composition gradient layer, where x is a linear gradient from 0.9 to 0, and the n-type doping concentration is 2.5×1018 cm -3 ; GaAs high refractive index layer with a thickness of 72nm and an n-type doping concentration of 2×10 18 cm -3 ; Cycle growth for 35.5 cycles, by adjusting the SiH4 flow rate to control the overall doping concentration; the last half cycle in Al 0.9 Ga 0.1 The As low refractive index layer ends the growth of the n-distributed Bragg reflector 3, and the overall doping concentration is controlled by adjusting the SiH4 flow rate.

[0056] Step 4.Al 0.6 Ga 0.4 Growth of As space layer 4: the reaction chamber temperature was maintained at 650-680°C, the trimethylgallium flow rate was 55 sccm, the trimethylaluminum flow rate was 125 sccm, the arsine flow rate 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 remains unchanged, the trimethylgallium flow rate is 45sccm, the arsine flow rate is 800-1500sccm, the phosphine flow rate is 300-500sccm, the growth time is 36 seconds, and the Al 0.6 Ga 0.4 GaAs with a thickness of 10 nm is grown on the As spacer 4 0.855 P 0.145 Barrier layer.

[0058] In 0.05 Ga 0.95 As wetting layer growth: temperature rises to 680-700°C, trimethylgallium flow rate is 64 sccm, trimethylindium flow rate is 50 sccm, arsine flow rate is 1000-2000 sccm, growth time is 18 seconds, in Ga 0.855 As 0.145 An InGaAs wetting layer with a thickness of 8 nm is grown on the P barrier layer.

[0059] In 0.52 Ga 0.48 As quantum dot layer growth: keep the temperature constant, the trimethylgallium flow rate is 64sccm, the trimethylindium flow rate is 240sccm, and the arsine flow rate is 100-200sccm. Keep the temperature constant and stop the flow of trimethylgallium and trimethylindium. Keep the flow for 3 seconds to form In 0.52 Ga 0.48 As quantum dots.

[0060] In 0.52 Ga 0.48As quantum dot cap layer growth: the temperature remains unchanged, the trimethyl gallium flow rate is 64sccm, the trimethyl indium flow rate is 240sccm, the arsine flow rate is 1000-2000sccm, the growth time is 5 seconds, and the growth thickness is 8nm. 0.05 Ga 0.95 As cap layer.

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

[0062] GaAs 0.855 P 0.145 Barrier layer growth: The reaction chamber temperature remains unchanged, the trimethylgallium flow rate is 45 sccm, the arsine flow rate is 800-1500 sccm, the phosphine flow rate is 300-500 sccm, the growth time is 36 seconds, and the In 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 space layer 6 growth: the same as step 4 Al 0.6 Ga 0.4 The growth conditions of As space layer 4 are the same, and the growth thickness is 264nm. 0.6 Ga 0.4 The thickness of the As space layers is different in order to keep the thickness of the resonant cavity an integer multiple of the wavelength.

[0064] Step 7. p-Al 0.98 Ga 0.02 Growth of As oxide limiting layer 7: The growth process is as follows: 1. The growth temperature is 650-680°C, the trimethyl gallium flow rate is 55 sccm, the trimethyl aluminum flow rate is 125 sccm, the arsine flow rate is 440 sccm, the carbon tetrabromide flow rate is 10-25 sccm, the growth thickness is 30 nm, and the p-doping concentration is 6×10 17 cm -3 .

[0065] Step 8.Al 0.6 Ga 0.4As space layer 8 growth: the same as step 4 Al 0.6 Ga 0.4 The growth conditions of the As space layer (4) are the same, and the growth thickness is 180 nm.

[0066] Step 9. p-Al 0.05 Ga 0.95 As tunnel junction layer 9 growth: growth temperature is 650-680°C, trimethylgallium flow rate is 97sccm, trimethylaluminum flow rate is 28sccm, arsine flow rate is 1160sccm, carbon tetrabromide flow rate is 10-25sccm, growth thickness is 20nm, p-type doping concentration is 10×10 19 cm -3 .

[0067] Step 10. Growth of n-GaAs tunnel junction layer 10: temperature drops to 550-650°C, trimethylgallium flow rate is 90 sccm, arsine flow rate is 440 sccm, silane flow rate is 50-100 sccm, growth thickness is 20 nm, n-type doping concentration is 3×10 19 cm -3 .

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

[0069] Step 12. Repeat steps 5 to 11 three times; so far, 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 oxidation limiting layer 7, Al 0.6 Ga 0.4 As space layer 8, p-Al 0.05 Ga 0.95 As tunnel junction layer 9, n-GaAs tunnel junction layer 10 and Al 0.6 Ga 0.4 The As space layer 11 forms a four-cycle structure.

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

[0071] Step 14.Al 0.6 Ga 0.4 As space layer 13 growth: the same as step 4 Al 0.6 Ga 0.4 The growth conditions of As space layer 4 are the same, and the growth thickness is 200nm.

[0072] Step 15. p-Al0.98 Ga 0.02 Growth of As oxidation restriction layer 14: Same as step 7.

[0073] Step 16. Growth of p-distributed Bragg reflector 15: The growth temperature is 680°C to control the amount of Zn source doping, in order to control the p-Al 0.98 Ga 0.02 The As oxidation limiting layer 14 and the p-GaAs cap layer 16 are doped at the same doping level. For the p-GaAs cap layer 16, the DEZn flow rate is 5 sccm, and for the p-Al 0.98 Ga 0.02 As oxidation restriction layer 14, DEZn source flow rate is 50sccm, and p-distributed Bragg reflector is grown in sequence with a thickness of 20nm Al x Ga 1-x As composition gradient layer, where x is a linear gradient from 0.9 to 0, and the p-type doping concentration is 6×10 18 cm -3 ; GaAs high refractive index layer with a thickness of 72nm and a p-type doping concentration of 6×10 17 cm -3 ; Al with a thickness of 20nm x Ga 1-x As composition gradient layer, where x is a linear gradient from 0 to 0.9, and the p-type doping concentration is 6×10 18 cm -3 ; Al with a thickness of 86nm 0.9 Ga 0.1 As low refractive index layer, p-type doping concentration is 6×10 17 cm -3 ; Cycle growth for 14 cycles.

[0074] Step 17. Growth of p-GaAs cap layer 16: the temperature is reduced to 550-650°C, the trimethyl gallium flow rate is 90 sccm, the arsine flow rate is 440 sccm, the carbon tetrabromide flow rate is 10-25 sccm, the growth thickness is 5 nm, and the p-type doping concentration is greater than 1×10 19 cm -3 .

[0075] Multiple quantum dot active regions are connected in series into the same resonant cavity by heavily doped reverse tunnel junctions. The energy band diagram of the multi-junction cascade quantum dot active region structure is shown in Figure 2. Figure 3 As shown, without increasing the light-emitting area, the carrier concentration in the active region is reduced, the carrier confinement capability is improved, thereby reducing the non-radiative recombination in the epitaxial structure, and further reducing the threshold current, improving the output power and electro-optical conversion efficiency. By increasing the tunneling junction structure, the recombination of one electron with multiple holes during the transmission process can be achieved, thereby improving the radiative recombination efficiency. Figure 4(a) shows 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 5-junction quantum dot vertical cavity surface emitting laser is 188.1mW. Figure 4 (b) shows that the peak electro-optical conversion efficiency of the single-junction quantum dot vertical cavity surface emitting laser reaches 44.4%, and the peak electro-optical conversion efficiency of the five-junction quantum dot vertical cavity surface emitting laser reaches 58.4%; when the injected current is 20mA, the power of the five-junction vertical cavity surface emitting laser is increased by about 85% compared with the three-junction vertical cavity surface emitting laser.

[0076] The tunnel junction connecting multiple quantum dots in series should be heavily doped with high degenerate energy levels in the p+ and n+ semiconductor layers (>10 19 cm -3 ) to provide a high tunneling current with the lowest voltage drop. To maximize the optical gain, the multi-quantum well active region needs to be placed at the antinode of the standing wave field; at the same time, the oxide layer and the tunnel junction should be placed at the node of the standing wave field to reduce the current crowding effect at the edge of the oxide layer and the free carrier absorption loss caused by the heavily doped tunnel junction. In order to meet the above requirements, the optical distance between each active region should be at least 1λ, where λ represents the wavelength of light. At the same time, in order to minimize the influence of oxide layer stress accumulation and tunnel junction impurity diffusion on the active region, it is better to adjust the optical spacing between adjacent active regions to 2λ.

[0077] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

[0078] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than 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 the technical solution of the present invention can be modified and replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A vertical cavity surface emitting laser structure with a multi-junction cascade quantum dot active region, characterized in that: The invention comprises an n-GaAs substrate (1), an n-GaAs buffer layer (2), an n-distributed Bragg reflector (3), an Al 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 oxidation limiting layer (7), Al 0.6 Ga 0.4 As space layer (8), p-Al 0.05 Ga 0.95 As tunnel junction layer (9), n-GaAs tunnel junction 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 oxidation confinement layer (14), p-distributed Bragg reflector (15) and p-GaAs cap layer (16), wherein: The n-GaAs buffer layer (2) is grown on the n-GaAs substrate (1), the n-distributed Bragg reflector (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 the n-distributed Bragg reflector (3), and the quantum dot active region layer (5) is grown on the Al 0.6 Ga 0.4 As space layer (4) grows, the Al 0.6 Ga 0.4 The As space layer (6) is grown on the quantum dot active region layer (5), and the p-Al 0.98 Ga 0.02 As oxidation limiting layer (7) on Al 0.6 Ga 0.4 As space layer (6) grows, the Al 0.6 Ga 0.4 As space layer (8) in p-Al 0.98 Ga 0.02 As is grown on the oxidation restriction layer (7), the p-Al 0.05 Ga 0.95 As tunnel junction layer (9) on Al 0.6 Ga 0.4 The n-GaAs tunnel junction layer (10) is grown on the p-Al 0.05 Ga 0.95 As tunnel junction layer (9), the Al 0.6 Ga 0.4 The As space layer (11) is grown on the n-GaAs tunnel junction layer (10), and the quantum dot active region layer (12) is grown on the Al 0.6 Ga 0.4 As space layer (11) is grown, the Al 0.6 Ga 0.4 The As space layer (13) is grown on the quantum dot active region layer (12), and the p-Al 0.98 Ga 0.02 As oxidation limiting layer (14) on Al 0.6 Ga 0.4 The p-distributed Bragg reflector (15) is grown on the p-Al space layer (13). 0.98 Ga 0.02 The p-GaAs cap layer (16) is grown on the p-distributed Bragg reflector (15).

2. The vertical cavity surface emitting laser structure with 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 oxidation limiting layer (7), Al 0.6 Ga 0.4 As space layer (8), p-Al 0.05 Ga 0.95 As tunnel junction layer (9), n-GaAs tunnel junction layer (10) and Al 0.6 Ga 0.4 After the As space layer (11) is grown in sequence, it is cycled and grown three times in this order.

3. The vertical cavity surface emitting laser structure with multi-junction cascaded quantum dot active region according to claim 1, characterized in that: The n-distributed Bragg reflector (3) comprises 36 n-GaAs high refractive index layers and 35 Al 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, and the n-distributed Bragg reflector (3) starts to grow from the n-GaAs buffer layer (2) and the starting point is Al x Ga 1-x As component gradient layer; The p-distributed Bragg reflector (15) comprises 14 pairs of n-GaAs high refractive index layers and Al 0.9 Ga 0.1 As low refractive index layer, p-distributed Bragg reflector (15) from p-Al 0.98 Ga 0.02 The As oxidation limiting layer (14) starts to grow from Al x Ga 1-x As component gradient layer; n-GaAs high refractive index layer and Al 0.9 Ga 0.1 AlAs is set between the low refractive index layers x Ga 1-x As composition gradient layer, Al x Ga 1- x The Al component in the As component gradient layer is gradient, the maximum value of Al component is 0.9, and the minimum value is greater than 0; The Ga component changes gradually, with the maximum value of Ga component being 1 and the minimum value being 0.

1.

4. The vertical cavity surface emitting laser structure with multi-junction cascaded quantum dot active region according to claim 3, characterized in that: The n-distributed Bragg reflector (3) is composed of Al2O3 layers with a thickness of 20 nm, starting from the n-GaAs buffer layer (2) and along the growth direction. x Ga 1-x 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 18 cm -3 ; Al with a thickness of 86nm 0.9 Ga 0.1 As low refractive index layer, n-type doping concentration is 2×10 18 cm -3 ; 20nm thick Al x Ga 1-x 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 18 cm -3 ; GaAs high refractive index layer with a thickness of 72nm and an n-type doping concentration of 2×10 18 cm -3 , growing for 35.5 cycles.

5. The vertical cavity surface emitting laser structure with multi-junction cascaded quantum dot active region according to claim 3, characterized in that: The p-distributed Bragg reflector (15) is made of p-Al 0.98 Ga 0.02 The As oxidation limiting layer (14) starts from the growth direction and is successively composed of Al with a thickness of 20 nm. x Ga 1-x As composition gradient layer, where x is a linear gradient from 0.9 to 0, and the p-type doping concentration is 6×10 18 cm -3 ; GaAs high refractive index layer with a thickness of 72nm and a p-type doping concentration of 6×10 17 cm -3 ; Al with a thickness of 20nm x Ga 1-x As composition gradient layer, where x is a linear gradient from 0 to 0.9, and the p-type doping concentration is 6×10 18 cm -3 ; Al with a thickness of 86nm 0.9 Ga 0.1 As low refractive index layer, p-type doping concentration is 6×10 17 cm -3 , grow for 14 cycles.

6. The vertical cavity surface emitting laser structure with multi-junction cascaded quantum dot active region according to claim 1, characterized in that: The quantum dot active region layer (5) comprises two layers of GaAs with a thickness of 10 nm. 0.855 P 0.145 Barrier layer, in two layers of GaAs 0.855 P 0.145 In layers with a thickness of 8 nm are placed 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.

7. A method for preparing a vertical cavity surface emitting laser structure with a multi-junction cascaded quantum dot active region as claimed in any one of claims 1 to 6, characterized in that: The specific steps include: Step 1. Cleaning the surface of the n-GaAs substrate (1): introducing hydrogen gas, with the reaction chamber temperature at 700-740° C., for 5-15 minutes to clean off particle contaminants on the surface of the n-GaAs substrate (1) and remove oxygen atoms on the surface of the n-GaAs substrate (1); Step 2. Growth of n-GaAs buffer layer (2): The reaction chamber temperature was lowered to 650-680°C, the trimethylgallium flow rate was 90 sccm, the arsine flow rate was 440 sccm, the silane flow rate was 50-100 sccm, the growth thickness was 500 nm, and the n-type doping concentration was 2×10 18 cm -3 ; Step 3. Growth of n-distributed Bragg reflector (3): The temperature of the reaction chamber is maintained at 650-680°C, and the n-distributed Bragg reflector is grown in turn with a thickness of 20 nm. x Ga 1-x 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 18 cm -3 ; Al with a thickness of 86nm 0.9 Ga 0.1 As low refractive index layer, n-type doping concentration is 2×10 18 cm -3 ; 20nm thick Al x Ga 1-x 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 18 cm -3 ; GaAs high refractive index layer with a thickness of 72nm and an n-type doping concentration of 2×10 18 cm -3 ; Cycle growth for 35.5 cycles, and control the overall doping concentration by adjusting the SiH4 flow rate; Step 4.Al 0.6 Ga 0.4 Growth of As space layer (4): the reaction chamber temperature was maintained at 650-680°C, the trimethylgallium flow rate was 55 sccm, the trimethylaluminum flow rate was 125 sccm, the arsine flow rate was 440 sccm, and the growth thickness was 200 nm; Step 5. Growth of quantum dot active region layer (5): GaAs 0.855 P 0.145 Barrier layer growth: The reaction chamber temperature remains unchanged, the trimethylgallium flow rate is 45sccm, the arsine flow rate is 800-1500sccm, the phosphine flow rate is 300-500sccm, the growth time is 36 seconds, and the Al 0.6 Ga 0.4 A GaAs layer 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 rises to 680-700°C, trimethylgallium flow rate is 64 sccm, trimethylindium flow rate is 50 sccm, arsine flow rate is 1000-2000 sccm, growth time is 18 seconds, in Ga 0.855 As 0.145 An InGaAs wetting layer with a thickness of 8 nm is grown on the P barrier layer; In 0.52 Ga 0.48 As quantum dot layer growth: keep the temperature constant, the trimethylgallium flow rate is 64sccm, the trimethylindium flow rate is 240sccm, and the arsine flow rate is 100-200sccm. Keep the temperature constant and stop the flow of trimethylgallium and trimethylindium. Keep the flow for 3 seconds to form In 0.52 Ga 0.48 As quantum dots; In 0.52 Ga 0.48 As quantum dot cap layer growth: the temperature remains unchanged, the trimethyl gallium flow rate is 64sccm, the trimethyl indium flow rate is 240sccm, the arsine flow rate is 1000-2000sccm, the growth time is 5 seconds, and the growth thickness is 8nm. 0.05 Ga 0.95 As cap layer; In 0.05 Ga 0.95 As wetting layer growth: the reaction chamber temperature was raised to 680-700°C, the trimethylgallium flow rate was 64 sccm, the trimethylindium flow rate was 50 sccm, the arsine flow rate was 1000-2000 sccm, the growth time was 18 seconds, and the In 0.52 Ga 0.48 An 8 nm thick Indium layer is grown on the As quantum dot cap layer. 0.05 Ga 0.95 As wetting layer; GaAs 0.855 P 0.145 Barrier layer growth: The reaction chamber temperature remains unchanged, the trimethylgallium flow rate is 45sccm, the arsine flow rate is 800-1500sccm, the phosphine flow rate is 300-500sccm, the growth time is 36 seconds, and the In 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: same as Al in step 4 0.6 Ga 0.4 The As spacer layer (4) was grown under the same growth conditions and had a thickness of 264 nm; Step 7. p-Al 0.98 Ga 0.02 Growth of As oxide restriction layer (7): Growth process: Growth temperature is 650-680°C, trimethylgallium flow rate is 55 sccm, trimethylaluminum flow rate is 125 sccm, arsine flow rate is 440 sccm, carbon tetrabromide flow rate is 10-25 sccm, growth thickness is 30 nm, p doping concentration is 6×10 17 cm -3 ; Step 8.Al 0.6 Ga 0.4 As space layer (8) growth: same as Al in step 4 0.6 Ga 0.4 The As spacer layer (4) was grown under the same growth conditions and had a thickness of 180 nm; Step 9. p-Al 0.05 Ga 0.95 Growth of As tunnel junction layer (9): growth temperature is 650-680°C, trimethylgallium flow rate is 97 sccm, trimethylaluminum flow rate is 28 sccm, arsine flow rate is 1160 sccm, carbon tetrabromide flow rate is 10-25 sccm, growth thickness is 20 nm, p-type doping concentration is 10×10 19 cm -3 ; Step 10. Growth of n-GaAs tunnel junction layer (10): temperature drops to 550-650°C, trimethylgallium flow rate is 90 sccm, arsine flow rate is 440 sccm, silane flow rate is 50-100 sccm, growth thickness is 20 nm, n-type doping concentration is 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 to 11 three times; Step 13. Growth of quantum dot active region layer (12): the same as the growth process of the quantum dot active region layer (5) in step 5; Step 14.Al 0.6 Ga 0.4 As space layer (13) growth: same as Al in step 4 0.6 Ga 0.4 The growth conditions of the As spacer layer (4) are the same, and the growth thickness is 200 nm; Step 15. p-Al 0.98 Ga 0.02 As oxide limiting layer (14) growth: same as step 7; Step 16. Growth of p-distributed Bragg reflector (15): Growth temperature is 680°C to control the amount of Zn source doping, in order to control the p-Al 0.98 Ga 0.02 The As oxidation limiting layer (14) and the p-GaAs cap layer (16) are doped at the same doping level. For the p-GaAs cap layer (16), the DEZn flow rate is 5 sccm, and for the p-Al 0.98 Ga 0.02 As oxidation restriction layer (14), DEZn source flow rate is 50sccm, p-distributed Bragg reflector is grown in sequence with a thickness of 20nm Al x Ga 1-x As composition gradient layer, where x is a linear gradient from 0.9 to 0, and the p-type doping concentration is 6×10 18 cm -3 ; GaAs high refractive index layer with a thickness of 72nm and a p-type doping concentration of 6×10 17 cm -3 ; Al with a thickness of 20nm x Ga 1-x As composition gradient layer, where x is a linear gradient from 0 to 0.9, and the p-type doping concentration is 6×10 18 cm -3 ; Al with a thickness of 86nm 0.9 Ga 0.1 As low refractive index layer, p-type doping concentration is 6×10 17 cm -3 ; Cyclic growth for 14 cycles; Step 17. Growth of p-GaAs cap layer (16): temperature drops to 550-650°C, trimethylgallium flow rate is 90 sccm, arsine flow rate is 440 sccm, carbon tetrabromide flow rate is 10-25 sccm, growth thickness is 5 nm, p-type doping concentration is greater than 1×10 19 cm -3 .

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