Quantum well laser and preparation method thereof

Abstract

The invention provides a quantum well laser and a preparation method thereof. The laser comprises a first electrode; the patterned substrate is arranged on the upper surface of the first electrode, and a groove is etched in the upper surface of the patterned substrate; the epitaxial layer grows in the groove, extends out of the groove and covers a preset area of the upper surface of the patterned substrate, and the area of the preset area is smaller than that of the patterned substrate; the filling layer is filled between the side wall of the epitaxial layer and the upper surface of the patterned substrate, and the height of the filling layer is greater than that of the epitaxial layer; the second electrode is located on the upper surfaces of the epitaxial layer and the filling layer.

Description

Technical Field

[0001] The present disclosure relates to the field of optoelectronic devices, and in particular to a quantum well laser and a method for preparing the same. Background Art

[0002] Silicon-based selective epitaxial III-V group lasers have great application prospects in silicon-based monolithic integrated light source solutions. Compared with bonding and thick buffer epitaxial solutions, silicon-based selective epitaxial III-V group quantum well laser solutions based on high aspect ratio confinement (ART) technology have the advantages of large-scale integration and compatibility with CMOS processes.

[0003] However, due to the serious lattice mismatch between the epitaxial substrate InP and silicon of the typical long-wavelength gain material, the active area of ​​the silicon-based III-V laser prepared by the ART method can only be limited to the vicinity of the silicon oxide mask strip, resulting in the active area being limited by the size parameters of the patterned substrate. At the same time, since the ART technology usually uses a trench less than 1 μm wide to limit epitaxial defects, the active area of ​​the III-V laser is small, the light field mode leakage loss is large, the injection efficiency is low, and the active material cannot provide sufficient gain during the electrical injection process, resulting in the device being unable to achieve electrically pumped lasing. In addition, the monolithic integration of silicon-based lasers and silicon-based modulators prepared by the ART method is immature, and there are problems such as complex process, large coupling loss and high cost, which limit its application as a commercial silicon-based high-speed device. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the above problems, the present disclosure provides a quantum well laser and a preparation method thereof, so as to at least partially solve the technical problems existing in traditional III-V lasers, such as small active area, large light field mode leakage loss, low injection efficiency, poor gain performance, complex process, large coupling loss and high cost.

[0006] (II) Technical solution

[0007] On the one hand, the present disclosure provides a quantum well laser, comprising: a first electrode; a patterned substrate, arranged on the upper surface of the first electrode, a groove being etched on the upper surface of the patterned substrate; an epitaxial layer, grown in the groove and extending out of the groove to cover a predetermined area on the upper surface of the patterned substrate, the area of ​​the predetermined area being smaller than the area of ​​the patterned substrate; a filling layer, filled between the side wall of the epitaxial layer and the upper surface of the patterned substrate, the height of the filling layer being greater than the height of the epitaxial layer; and a second electrode, located on the upper surfaces of the epitaxial layer and the filling layer.

[0008] According to an embodiment of the present disclosure, the patterned substrate includes: a silicon substrate and a mask strip; wherein the groove is formed by etching in a selected area on the surface of the silicon substrate; the mask strip is located on the upper surface of the silicon substrate and does not cover the groove.

[0009] According to an embodiment of the present disclosure, the epitaxial layer includes, from bottom to top: a bottom conductive layer, a lower conductive transition layer, an undoped lower waveguide layer, an undoped multi-quantum well layer, an undoped upper waveguide layer, a first upper conductive layer, a grating structure layer, a second upper conductive layer and a contact layer.

[0010] According to an embodiment of the present disclosure, the filling layer includes, from the inside to the outside, a first inorganic insulating material layer, an organic insulating material layer and a second inorganic insulating material layer.

[0011] According to an embodiment of the present disclosure, the material of the epitaxial layer is a III-V compound.

[0012] According to an embodiment of the present disclosure, the material of the first electrode is TiAu alloy, the material of the second electrode is TiAu, TiPtAu or AuZn alloy, and the pad shape of the second electrode is circular.

[0013] According to an embodiment of the present disclosure, the grating structure layer is a first-order or high-order Bragg grating.

[0014] According to an embodiment of the present disclosure, the undoped multi-quantum well layer is made of InGaAsP or AlGaInAs material, the number of quantum wells is 3 to 8, the thickness of the quantum wells is 3 to 7 nm, the number of potential barriers is greater than the number of quantum wells, the thickness of the potential barriers is 10 to 15 nm, and the band gap wavelength is 1.1 to 1.3 μm.

[0015] The second aspect of the present disclosure provides a method for preparing a quantum well laser, comprising: etching a groove in a selected area on the surface of a silicon substrate to obtain a patterned substrate with a mask strip on the surface; growing an epitaxial layer in a predetermined area on the upper surface of the patterned substrate within the groove of the patterned substrate and extending out of the groove through epitaxial technology, wherein the area of ​​the predetermined area is smaller than the area of ​​the patterned substrate; depositing a filling layer between the side wall of the epitaxial layer and the upper surface of the patterned substrate, wherein the height of the filling layer is greater than the height of the epitaxial layer; photolithography and deposition of a second electrode on the upper surfaces of the epitaxial layer and the filling layer; and obtaining a first electrode on the lower surface of the patterned substrate through thinning and deposition technology.

[0016] According to an embodiment of the present disclosure, the method of growing an epitaxial layer in a predetermined area on the upper surface of the patterned substrate within the groove of the patterned substrate and extending out of the groove by epitaxial technology includes: obtaining a bottom conductive layer on the inner side of the silicon substrate of the groove by low-temperature epitaxial technology; obtaining a lower conductive transition layer on the inner side and upper surface of the mask strip by low-temperature and high-temperature epitaxial technology; obtaining an undoped lower waveguide layer, an undoped multi-quantum well layer, an undoped upper waveguide layer, a first upper conductive layer and a grating structure layer in sequence from bottom to top on the upper surface of the mask strip and the upper surface of the lower conductive transition layer by high-temperature epitaxial technology; and obtaining a second upper conductive layer and a contact layer in sequence from bottom to top on the upper surface of the mask strip and the upper surface of the grating structure layer by high-temperature secondary epitaxial technology.

[0017] (III) Beneficial effects

[0018] The quantum well laser provided by the present disclosure increases the gain area of ​​the group III-V quantum well in the epitaxial layer, enhances the light field confinement factor, and reduces the mode loss, thereby promoting electrically pumped lasing. At the same time, a Bragg grating is used in the grating structure layer in the epitaxial layer to achieve single-mode output. In addition, a low dielectric constant filling material and a second electrode of a circular pad are used to reduce parasitic capacitance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] For a more complete understanding of the present disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

[0020] Figure 1 The schematic diagram of the structure of the quantum well laser provided according to the embodiment of the present disclosure is shown;

[0021] Figure 2 A schematic diagram of a patterned substrate of a quantum well laser provided according to an embodiment of the present disclosure is schematically shown;

[0022] Figure 3 A schematic diagram of an epitaxial layer of a quantum well laser provided according to an embodiment of the present disclosure is shown;

[0023] Figure 4 A schematic diagram of the structure of a filling layer of a quantum well laser provided according to an embodiment of the present disclosure is shown;

[0024] Figure 5 A schematic top view of a quantum well laser structure provided according to an embodiment of the present disclosure is shown;

[0025] Figure 6 The small signal response curve of the quantum well laser structure provided according to the embodiment of the present disclosure is schematically shown;

[0026] Figure 7The flowchart of the method for preparing a quantum well laser provided in accordance with an embodiment of the present disclosure is schematically shown.

[0027] Description of reference numerals:

[0028] 10- a first electrode;

[0029] 11- patterned substrate;

[0030] 111-silicon substrate;

[0031] 112-mask strip;

[0032] 12- epitaxial layer;

[0033] 121- bottom conductive layer;

[0034] 122-lower conductive transition layer;

[0035] 123- undoped lower waveguide layer;

[0036] 124- undoped multiple quantum well layer;

[0037] 125- undoped upper waveguide layer;

[0038] 126-first upper conductive layer;

[0039] 127-grating structure layer;

[0040] 128- a second upper conductive layer;

[0041] 129-contact layer;

[0042] 13-filling layer;

[0043] 131- a first inorganic insulating material layer;

[0044] 132- organic insulating material layer;

[0045] 133- a second inorganic insulating material layer;

[0046] 14- a second electrode;

[0047] 15-Non-light-emitting end face;

[0048] 16-Light exit end face. DETAILED DESCRIPTION

[0049] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0050] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0051] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0052] Figure 1 The schematic diagram shows the structure of a quantum well laser provided according to an embodiment of the present disclosure.

[0053] like Figure 1 As shown, the quantum well laser includes: a first electrode 10; a patterned substrate 11, which is arranged on the upper surface of the first electrode 10, and a groove is etched on the upper surface of the patterned substrate 11; an epitaxial layer 12, which grows in the groove and extends out of the groove to cover a predetermined area on the upper surface of the patterned substrate 11, and the area of ​​the predetermined area is smaller than the area of ​​the patterned substrate 11; a filling layer 13, which is filled between the side wall of the epitaxial layer 12 and the upper surface of the patterned substrate 11, and the height of the filling layer 13 is greater than the height of the epitaxial layer 12; a second electrode 14, which is located on the upper surfaces of the epitaxial layer 12 and the filling layer 13.

[0054] In the embodiment of the present disclosure, grooves are formed on the surface of the patterned substrate 11 to guide the growth direction of the epitaxial layer 12 and help form the desired optical cavity structure. The material of the epitaxial layer 12 is a III-V compound, which has excellent luminescence performance and carrier mobility, that is, the quantum well laser of the embodiment of the present disclosure is a silicon-based III-V quantum well laser. The quantum well structure is achieved by precisely controlling the growth thickness and composition of different materials in the epitaxial layer 12, thereby forming an energy potential well in the energy band to allow electrons and holes to recombine in a specific energy state and emit light of a specific wavelength. The filling layer 13 can provide a smooth interface with the epitaxial layer 12.

[0055] It is understandable that the quantum well laser provided by the embodiment of the present disclosure can increase the gain area of ​​the quantum well by optimizing the growth conditions of the epitaxial layer and the design of the patterned substrate, thereby improving the output power and efficiency of the laser. At the same time, by accurately controlling the refractive index difference between the epitaxial layer and the filling layer, the confinement of the light field in the quantum well structure can be enhanced, the mode loss can be reduced, and the performance stability of the laser can be improved, thereby outputting a high-speed direct modulation signal in an electrically pumped manner, which is easy to integrate on a large scale and compatible with CMOS processes.

[0056] Figure 2 A schematic diagram of a patterned substrate for a quantum well laser provided according to an embodiment of the present disclosure is schematically shown.

[0057] like Figure 2 As shown, the patterned substrate 11 includes a silicon substrate 111 and a mask strip 112. A groove is formed by etching in a selected area on the surface of the silicon substrate 111, and the mask strip 112 is located on the upper surface of the silicon substrate 111 and does not cover the groove.

[0058] Optionally, the groove on the upper surface of the silicon substrate 111 is a V-shaped groove, and the width of the V-shaped groove is 500-1000 nm. The silicon substrate 111 is an N-type silicon substrate, and the doping concentration is 2e17-3e18 cm -3 The thickness after thinning is 50~100 μm.

[0059] Optionally, the mask strips 112 are silicon oxide mask strips, with a mask height of 1000-1500 nm and a period of 3-10 μm.

[0060] Figure 3 A schematic diagram of the epitaxial layer of a quantum well laser provided according to an embodiment of the present disclosure is schematically shown.

[0061] like Figure 3 As shown, the epitaxial layer 12 includes, from bottom to top, a bottom conductive layer 121, a lower conductive transition layer 122, an undoped lower waveguide layer 123, an undoped multi-quantum well layer 124, an undoped upper waveguide layer 125, a first upper conductive layer 126, a grating structure layer 127, a second upper conductive layer 128 and a contact layer 129.

[0062] Exemplarily, the bottom conductive layer 121 is an N-type GaAs layer, which is disposed in the N-type silicon substrate of the V-shaped groove of the patterned substrate 11, and the doping concentration of the bottom conductive layer 121 is 1e17-1e18 cm -3 , thickness is 300~800 nm, and the upper surface is {001} plane.

[0063] Exemplarily, the lower conductive transition layer 122 is a lower N-type InP layer, which is disposed inside and on the upper surface of the mask strip 112 of the patterned substrate 11, and has a doping concentration of 1e17-1e18 cm -3 , thickness is 1300~1600 nm, and the upper surface is {110} plane, {111} plane, and {001} plane.

[0064] Exemplarily, the undoped lower waveguide layer 123 is disposed on the upper surface of the mask strip 112 of the patterned substrate 11 and the upper surface of the lower conductive transition layer 122, and can be made of InGaAsP or AlGaInAs material, with a thickness of 20-100 nm and a band gap wavelength of 1.1-1.3 μm.

[0065] In the embodiment of the present disclosure, the undoped multi-quantum well layer 124 is disposed on the upper surface of the mask strip 112 of the patterned substrate 11 and the upper surface of the undoped lower waveguide layer 123, and is made of InGaAsP or AlGaInAs material, with 3 to 8 quantum wells, a quantum well thickness of 3 to 7 nm, a gain spectrum peak in the C band or the O band, and a compressive strain of 0 to 1%. The number of potential barriers is greater than the number of quantum wells, which can be the number of quantum wells + 1, the potential barrier thickness is 10 to 15 nm, the band gap wavelength is 1.1 to 1.3 μm, and the tensile strain is 0 to 0.4%.

[0066] Exemplarily, the undoped upper waveguide layer 125 is disposed on the upper surface of the mask strip 112 of the patterned substrate 11 and the upper surface of the undoped multi-quantum well layer 124, and can be InGaAsP or AlGaInAs material, with a thickness of 20-100 nm and a band gap wavelength of 1.1-1.3 μm.

[0067] Exemplarily, the first upper conductive layer 126 is a first upper P-type InP layer, which is disposed on the upper surface of the mask strip 112 of the patterned substrate 11 and the upper surface of the undoped upper waveguide layer 125, and has a doping concentration of 5e16-1e17 cm -3 , thickness is 50~100nm, and the upper surface is {110} plane, {111} plane, and {001} plane.

[0068] In the embodiment of the present disclosure, the grating structure layer 127 is a first-order or high-order Bragg grating, the material is InGaAsP, and the band gap wavelength is 1.1-1.2 μm. The grating structure layer 127 can be a P-type grating layer, which is arranged on the upper surface of the mask strip 112 of the patterned substrate 11 and the upper surface of the first upper conductive layer 126, and the doping concentration is 5e16-1e17 cm -3 The thickness is 50-80 nm, and the upper surface is {110} plane, {111} plane, and {001} plane. The Bragg center wavelength of the grating structure layer 127 is in the C band or the O band, and the upper surface of the Bragg grating is {111} plane and {001} plane.

[0069] It can be understood that by using a Bragg grating, single-mode output of the laser can be achieved.

[0070] Exemplarily, the second upper conductive layer 128 may be a second upper P-type InP layer, which is disposed on the upper surface of the mask strip 112 of the patterned substrate 11 and the upper surface of the grating structure layer 127, and has a doping concentration of 1e17-5e17 cm -3 , thickness is 1000~1200nm, and the upper surface is {110} plane, {111} plane, and {001} plane.

[0071] For example, the contact layer 129 may be a P-type InGaAs contact layer, which is disposed on the upper surface of the mask strip 112 of the patterned substrate 11 and the upper surface of the second upper conductive layer 128, and has a doping concentration of 5e18-1e19 cm -3 , thickness is 100~200nm, and the upper surface is {110} plane, {111} plane, and {001} plane.

[0072] Figure 4 The schematic diagram of the structure of the filling layer of the quantum well laser provided according to the embodiment of the present disclosure is schematically shown.

[0073] like Figure 4 As shown, the filling layer 13 includes, from the inside to the outside, a first inorganic insulating material layer 131 , an organic insulating material layer 132 and a second inorganic insulating material layer 133 .

[0074] It should be noted that the selection of the material of the filling layer 13 should take into account its refractive index, dielectric constant and compatibility with the epitaxial layer. The filling material with a low dielectric constant helps to reduce parasitic capacitance and improve the performance of the laser.

[0075] Exemplarily, the first inorganic insulating material layer 131 is silicon oxide or silicon nitride, and has a thickness of 100-300 nm.

[0076] Exemplarily, the organic insulating material layer 132 is polyimide or benzocyclobutene, and has a thickness of 2000-2400 nm.

[0077] Exemplarily, the second inorganic insulating material layer 133 is silicon oxide or silicon nitride, and has a thickness of 200-400 nm.

[0078] Figure 5 A top view of a quantum well laser structure provided according to an embodiment of the present disclosure is schematically shown.

[0079] In the embodiments of the present disclosure, Figure 5 As shown, the first electrode 10 is an N-side electrode made of TiAu alloy and is used to provide current input.

[0080] The second electrode 14 is a P-surface electrode made of TiAu, TiPtAu or AuZn alloy, and is used to provide current input and collect photons generated by the quantum well structure. The electrode pad of the second electrode 14 is in the shape of a circle with a diameter of 70-100 μm.

[0081] It can be understood that by adopting low dielectric constant filling materials and circular electrode pad design, the parasitic capacitance and contact resistance of the laser can be effectively reduced, and its high-speed modulation capability and stability can be improved.

[0082] In some exemplary embodiments, the cavity length of the quantum well laser is 100-300 μm, the non-light-emitting end face 15 of the laser is evaporated with a high reflectivity film with a reflectivity of 90-95%, and the light-emitting end face 16 of the laser is a natural cleavage surface or a focused ion beam etched cavity surface.

[0083] Figure 6 The small signal response curve of the quantum well laser structure provided according to the embodiment of the present disclosure is schematically shown.

[0084] like Figure 6 As shown, the 3dB cutoff bandwidth of the quantum well laser provided by the embodiment of the present disclosure increases with current injection, and the 3dB bandwidth can exceed 10 GHz.

[0085] Figure 7 The flowchart of the method for preparing a quantum well laser provided in accordance with an embodiment of the present disclosure is schematically shown.

[0086] like Figure 7 As shown, it specifically includes operations S1-S5.

[0087] In operation S1, a groove is formed by etching in a selected area on the surface of the silicon substrate 111 to obtain a patterned substrate 11 with a mask strip 112 on the surface.

[0088] Specifically, a patterned substrate 11 with silicon oxide mask strips 112 and V-shaped grooves on the surface is obtained on an N-type silicon substrate 111 through deposition (such as plasma enhanced chemical vapor deposition), lithography (such as contact lithography) and etching (such as wet and dry etching).

[0089] In operation S2 , an epitaxial layer 12 is grown in a predetermined region of the upper surface of the patterned substrate 11 within the groove of the patterned substrate 11 and extending out of the groove by epitaxial technology, and the area of ​​the predetermined region is smaller than the area of ​​the patterned substrate 11 .

[0090] Specifically, by epitaxial technology, such as metal organic chemical vapor deposition, a bottom conductive layer 121, a lower conductive transition layer 122, an undoped lower waveguide layer 123, an undoped multi-quantum well layer 124, an undoped upper waveguide layer 125, a first upper conductive layer 126, and a grating structure layer 127 are obtained on the patterned substrate 11. Then, by photolithography and etching methods, such as electron beam lithography, a Bragg grating is obtained in the grating structure layer 127. Then, by epitaxial method, a second upper conductive layer 128 and a contact layer 129 are obtained on the grating structure layer 127.

[0091] In operation S3 , a filling layer 13 is deposited between the sidewall of the epitaxial layer 12 and the upper surface of the patterned substrate 11 , and a height of the filling layer 13 is greater than a height of the epitaxial layer 12 .

[0092] Specifically, the filling layer 13 is obtained on both sides of the epitaxial layer 12 by deposition, photolithography and etching techniques, and the deposition method may include plasma enhanced chemical vapor deposition.

[0093] It should be noted that when the material of the filling layer is BCB (benzocyclobutene) or PI (polyimide), it is usually applied by spin coating (also called spinning) rather than deposition.

[0094] In operation S4 , a second electrode is photolithographically and deposited on the upper surfaces of the epitaxial layer and the filling layer.

[0095] By means of photolithography and deposition (such as sputtering) technology, a second electrode (P-side electrode) is obtained on the upper surfaces of the epitaxial layer 12 and the filling layer 13 .

[0096] In operation S5 , a first electrode (N-side electrode) is obtained on the lower surface of the patterned substrate by thinning and deposition techniques.

[0097] Finally, through alloying, cleavage and deposition techniques, silicon-based III-V quantum well lasers are obtained. In this process, the band offset in the quantum well structure is adjusted through alloying methods such as rapid thermal annealing, thereby optimizing the emission wavelength and efficiency of the laser. In addition, the cleavage process can be guided along a specific crystal plane through focused ion beam etching, thereby obtaining high-quality crystal sheets and reducing damage and defects during the cleavage process.

[0098] On the basis of the above-mentioned embodiments, in the present embodiment, an epitaxial layer 12 is grown in a predetermined area on the upper surface of the patterned substrate 11 in the groove of the patterned substrate 11 and extending out of the groove by epitaxial technology, including: obtaining a bottom conductive layer 121 on the inner side of the silicon substrate 111 of the groove by low-temperature epitaxial technology; obtaining a lower conductive transition layer 122 on the inner side and upper surface of the mask strip 112 by low-temperature and high-temperature epitaxial technology; obtaining an undoped lower waveguide layer 123, an undoped multi-quantum well layer 124, an undoped upper waveguide layer 125, a first upper conductive layer 126 and a grating structure layer 127 in sequence from bottom to top on the upper surface of the mask strip 112 and the upper surface of the lower conductive transition layer 122 by high-temperature epitaxial technology; and obtaining a second upper conductive layer 128 and a contact layer 129 in sequence from bottom to top on the upper surface of the mask strip 112 and the upper surface of the grating structure layer 127 by high-temperature secondary epitaxial technology.

[0099] Specifically, a bottom conductive layer 121 is obtained in an N-type silicon substrate 111 of a V-groove by a low-temperature epitaxial method. Then, a lower conductive transition layer 122 is obtained in the mask strip 112 and on the upper surface by low-temperature and high-temperature epitaxial methods. Then, an undoped lower waveguide layer 123, an undoped multi-quantum well layer 124, an undoped upper waveguide layer 125, a first upper conductive layer 126, and a grating structure layer 127 are obtained on the upper surface of the mask strip 112 and the upper surface of the lower conductive transition layer 122 by a high-temperature epitaxial method. Finally, a second upper conductive layer 128 and a contact layer 129 are obtained on the upper surface of the mask strip 112 and the upper surface of the grating structure layer 127 by a high-temperature secondary epitaxial method.

[0100] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations and / or combinations are not explicitly described in the present disclosure. In particular, the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways without departing from the spirit and teachings of the present disclosure. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0101] Although the present disclosure has been shown and described with reference to specific exemplary embodiments of the present disclosure, it should be understood by those skilled in the art that various changes in form and details may be made to the present disclosure without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. Therefore, the scope of the present disclosure should not be limited to the above-mentioned embodiments, but should be determined not only by the appended claims, but also by the equivalents of the appended claims.

Claims

1. A quantum well laser, characterized in that: include: a first electrode; A patterned substrate is disposed on the upper surface of the first electrode, and a groove is etched on the upper surface of the patterned substrate; an epitaxial layer, grown in the groove and extending out of the groove to cover a predetermined area of ​​the upper surface of the patterned substrate, wherein the area of ​​the predetermined area is smaller than the area of ​​the patterned substrate; A filling layer, filled between the side wall of the epitaxial layer and the upper surface of the patterned substrate, wherein the height of the filling layer is greater than the height of the epitaxial layer; The second electrode is located on the upper surfaces of the epitaxial layer and the filling layer.

2. The quantum well laser according to claim 1, characterized in that The patterned substrate comprises: A silicon substrate and a mask strip; wherein, Etching the groove in a selected area on the surface of the silicon substrate; The mask strip is located on the upper surface of the silicon substrate and does not cover the trench.

3. The quantum well laser according to claim 1, characterized in that The epitaxial layer includes, from bottom to top: A bottom conductive layer, a lower conductive transition layer, an undoped lower waveguide layer, an undoped multi-quantum well layer, an undoped upper waveguide layer, a first upper conductive layer, a grating structure layer, a second upper conductive layer and a contact layer.

4. The quantum well laser according to claim 1, characterized in that: The filling layer includes, from the inside to the outside: A first inorganic insulating material layer, an organic insulating material layer and a second inorganic insulating material layer.

5. The quantum well laser according to claim 1, characterized in that: The material of the epitaxial layer is a III-V compound.

6. The quantum well laser according to claim 1, characterized in that: The material of the first electrode is TiAu alloy, the material of the second electrode is TiAu, TiPtAu or AuZn alloy, and the pad shape of the second electrode is circular.

7. The quantum well laser according to claim 3, characterized in that: The grating structure layer is a first-order or high-order Bragg grating.

8. The quantum well laser according to claim 3, characterized in that: The undoped multi-quantum well layer is made of InGaAsP or AlGaInAs material, the number of quantum wells is 3-8, the thickness of the quantum wells is 3-7 nm, the number of potential barriers is greater than the number of quantum wells, the thickness of the potential barriers is 10-15 nm, and the band gap wavelength is 1.1-1.3 μm.

9. A method for preparing a quantum well laser, characterized in that: include: A groove is formed by etching in a selected area on the surface of the silicon substrate to obtain a patterned substrate with a mask strip on the surface; By epitaxial technology, an epitaxial layer is grown in a predetermined area on the upper surface of the patterned substrate in the groove of the patterned substrate and extending out of the groove, wherein the area of ​​the predetermined area is smaller than the area of ​​the patterned substrate; Depositing a filling layer between the sidewall of the epitaxial layer and the upper surface of the patterned substrate, wherein the height of the filling layer is greater than the height of the epitaxial layer; Photolithography and deposition of a second electrode on the upper surfaces of the epitaxial layer and the filling layer; A first electrode is obtained on the lower surface of the patterned substrate through thinning and deposition technology.

10. The method for preparing a quantum well laser according to claim 9, characterized in that: The step of growing an epitaxial layer in a predetermined area on the upper surface of the patterned substrate by epitaxial technology in the groove of the patterned substrate and extending out of the groove comprises: By low temperature epitaxial growth technology, a bottom conductive layer is obtained inside the silicon substrate of the trench; By low temperature and high temperature epitaxial growth technology, a lower conductive transition layer is obtained on the inner side and upper surface of the mask strip; By high temperature epitaxial growth technology, an undoped lower waveguide layer, an undoped multi-quantum well layer, an undoped upper waveguide layer, a first upper conductive layer and a grating structure layer are sequentially obtained from bottom to top on the upper surface of the mask strip and the upper surface of the lower conductive transition layer; By means of high temperature secondary epitaxial growth technology, a second upper conductive layer and a contact layer are sequentially obtained from bottom to top on the upper surface of the mask strip and the upper surface of the grating structure layer.

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