CN120073478A

CN120073478A - Semiconductor laser structure and preparation method

Info

Publication number: CN120073478A
Application number: CN202311555010.7A
Authority: CN
Inventors: 姜超
Original assignee: Shanghai IC R&D Center Co Ltd
Current assignee: Shanghai IC R&D Center Co Ltd
Priority date: 2023-11-20
Filing date: 2023-11-20
Publication date: 2025-05-30

Abstract

The present invention discloses a semiconductor laser structure and a preparation method, by forming a quantum dot structure on the surface of a first semiconductor layer, and forming a surface plasmon structure composed of a metal layer-medium layer on the quantum dot structure, the near-field optical enhancement of the quantum dot laser formed by the semiconductor laser structure is realized based on the surface plasmon, thereby improving the comprehensive performance of the quantum dot laser. In addition, while optimizing the preparation process of the laser and reducing the difficulty of preparation, the emission power and spectral purity of the quantum dot laser can be enhanced, thereby effectively solving the problems of the difficulty of preparing the traditional germanium quantum dot laser, the poor laser emission power and spectral purity, and improving the comprehensive performance of the quantum dot laser.

Description

Semiconductor laser structure and preparation method

Technical Field

The invention relates to the technical field of semiconductor integrated circuit processes, in particular to a germanium quantum dot laser structure based on surface plasmons and a preparation method thereof.

Background

Since the last 90 s of the century, researchers began to grow dislocation-free germanium quantum dots epitaxially on silicon substrates for the first time, many groups began to study the optical properties of germanium quantum dots in succession, and because the three-dimensional localized effect of germanium quantum dots on excitons resulted in enhanced silent sub-luminescence, it is desirable to replace germanium tin system lasers.

The quantum confinement effect of germanium quantum dots can make an indirect to direct bandgap optical transition without phonon emission or absorption. This theory provides a broad opportunity for the development of silicon-based optoelectronic integrated devices, such as germanium quantum dot lasers. However, for germanium quantum dots, the photon and electron applications require precise control of the density, size, shape, number of layers and even positions of the quantum dots, which presents great challenges and difficulties for the growth of self-assembled grown germanium quantum dots.

Surface plasmons are electromagnetic modes generated by the interaction of free electrons on a metal surface with an incident light field at a metal/medium interface, wherein the electromagnetic modes are only transmitted along a flat and smooth metal/medium interface, and the intensity in the direction perpendicular to the interface is exponentially attenuated along with the increase of distance, and are generally based on the interaction process of electromagnetic radiation and conduction electrons in a metal-medium interface or a metal nano structure, and the interaction can generate a near-field optical enhancement effect of a sub-wavelength scale. While the nano laser based on the surface plasmon can generate a femtosecond time scale coherent light source on a nano scale far smaller than a diffraction limit, which has important significance for promoting the development of the nano scale laser.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a semiconductor laser structure and a preparation method thereof.

In order to achieve the above purpose, the technical scheme of the invention is as follows:

the present invention provides a semiconductor laser structure comprising:

The quantum dot structure is arranged on the surface of the first semiconductor layer and comprises a plurality of quantum dots distributed on the surface of the first semiconductor layer;

and the surface plasmon structure is arranged on the quantum dot structure.

Further, the quantum dot comprises a self-assembled island formed by a second semiconductor on the surface of the first semiconductor layer, and the surface plasmon structure comprises a dielectric layer covering the quantum dot structure and a metal layer located on the dielectric layer.

Further, the first semiconductor comprises silicon, and/or the second semiconductor comprises germanium, and/or the dielectric layer comprises silicon dioxide or aluminum oxide, and/or the metal layer comprises gold, silver, copper, or aluminum.

Further, the quantum dot structure further comprises end surface reflection structures which are respectively arranged on two sides of the quantum dot structure and the surface plasmon structure and penetrate through the first semiconductor layer, and the end surface reflection structures on two sides are provided with opposite surfaces with equal or unequal reflectivity.

Further, the semiconductor laser structure is arranged on an SOI substrate, the SOI substrate comprises a bottom silicon layer, an oxygen-buried layer and a top silicon layer which are sequentially arranged, and the top silicon layer forms the first semiconductor layer.

The invention also provides a preparation method of the semiconductor laser structure, which comprises the following steps:

providing a substrate with a first semiconductor layer on the surface;

Forming a quantum dot structure on the surface of the first semiconductor layer;

and forming a surface plasmon structure on the quantum dot structure.

Further, the method for forming the quantum dot structure on the surface of the first semiconductor layer comprises the steps of forming a plurality of quantum dots on the surface of the first semiconductor layer in a distributed mode, forming a surface plasmon structure on the quantum dot structure, forming a dielectric layer covering the surfaces of the quantum dots, and forming a metal layer on the surface of the dielectric layer.

Further, the method for forming the plurality of quantum dots specifically comprises the following steps:

Forming an epitaxial window on the surface of the first semiconductor layer, and epitaxially forming a self-assembled island of energy quantization of a second semiconductor material in the epitaxial window, thereby forming a plurality of quantum dots distributed on the surface of the first semiconductor layer;

The method for forming the dielectric layer and the metal layer specifically comprises the following steps:

forming a dielectric layer covering the exposed surfaces of the plurality of quantum dots on the surface of the first semiconductor layer, enabling the top of the dielectric layer to be higher than the top of the plurality of quantum dots, and flattening to obtain a flat surface of the dielectric layer;

and forming a metal layer positioned above the plurality of quantum dots on the surface of the dielectric layer.

Further, the quantum dot structure comprises end face reflection structures which sequentially penetrate through the metal layer, the dielectric layer and the first semiconductor layer are formed on two sides of the quantum dot structure, and the end face reflection structures on two sides are provided with opposite surfaces with equal or unequal reflectivity.

Further, the substrate comprises an SOI substrate, wherein the SOI substrate comprises a bottom silicon layer, an oxygen-buried layer and a top silicon layer which are sequentially arranged, the top silicon layer is the first semiconductor layer, and the substrate comprises the following components in detail when the end face reflection structure is formed:

forming grooves which sequentially penetrate through the metal layer, the dielectric layer and the first semiconductor layer on two sides of the quantum dot structure and stopping on the oxygen-buried layer;

and depositing metals with different reflectivities on the grooves on two sides, or depositing single layers of the same dielectric insulating layer or different dielectric insulating layers, or sequentially depositing multiple layers of dielectric insulating layers, wherein the refractive indexes of any two adjacent dielectric insulating layers are different, and the filling orders of the dielectric insulating layers in the grooves on two sides are the same or different, so that an end surface reflecting structure with the bottoms penetrating through the top silicon layer is formed on two sides of the quantum dot structure and the surface plasmon structure.

According to the technical scheme, the quantum dot structure (germanium quantum dot structure) is formed on the first semiconductor layer, the surface plasmon structure formed by the metal layer-medium layer is formed on the quantum dot structure, and near-field optical enhancement of the quantum dot laser (germanium quantum dot laser) formed by the semiconductor laser structure is realized based on the surface plasmon, so that the comprehensive performance of the quantum dot laser is improved. In addition, the preparation process flow of the laser can be optimized, the preparation difficulty is reduced, and the emission power and the spectral purity of the quantum dot laser are enhanced, so that the problems of high preparation difficulty and poor emission power and spectral purity of the traditional germanium quantum dot laser are effectively solved.

Drawings

Fig. 1 is a schematic view of a semiconductor laser structure according to a preferred embodiment of the invention.

Fig. 2-7 are schematic views illustrating a method for fabricating a semiconductor laser structure according to a preferred embodiment of the present invention.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. Unless otherwise defined, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. As used herein, the word "comprising" and the like means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof without precluding other elements or items.

The invention aims to solve the problems that the traditional germanium quantum dot (Ge QDs) laser has higher requirement on the growth of quantum dots due to quantum confinement effect, and has lower emission power, poor spectral purity and the like due to the traditional laser, and designs a semiconductor laser structure based on the surface plasmon (SPP) theory by forming a germanium quantum dot structure on a first semiconductor layer, the surface plasmon structure formed by the metal layer-dielectric layer is further formed on the germanium quantum dot structure, and the surface plasmon structure can be used for forming a germanium quantum dot laser structure based on surface plasmon. Therefore, near-field optical enhancement of the germanium quantum dot laser can be realized based on surface plasmons, so that the comprehensive performance of the germanium quantum dot laser is improved.

The following describes the embodiments of the present invention in further detail with reference to the drawings.

Reference is made to fig. 1. A semiconductor laser structure of the present invention includes a quantum dot structure 12 provided on an upper surface of a first semiconductor layer 11, and a surface plasmon structure 13 provided on the quantum dot structure 12.

The quantum dot structure 12 includes a plurality of quantum dots 121 distributed on the upper surface of the first semiconductor layer 11.

In some embodiments, the plurality of quantum dots 121 includes a plurality of self-assembled islands 1211 of energy quantization formed on the upper surface of the first semiconductor layer 11 by the second semiconductor.

In some embodiments, surface plasmonic structure 13 includes a dielectric layer 14 overlying quantum dot structure 12, and a metal layer 15 on a surface of dielectric layer 14 overlying quantum dot structure 12.

In some embodiments, the first semiconductor comprises silicon.

The second semiconductor includes germanium.

Dielectric layer 14 material comprises silicon dioxide or aluminum oxide.

The metal layer 15 material comprises gold, silver, copper or aluminum.

Noble metals such as gold, silver, copper, aluminum and the like in metal materials are often used for surface plasmon research, and the dielectric constants of the noble metal materials are negative in real part (except aluminum which is located in ultraviolet band) in visible light band, and have large absolute value, positive in imaginary part and small absolute value. These properties provide the possibility for the generation of metal surface plasmons. However, among the numerous metal materials, gold may be preferred as the material of the metal layer 15 due to its good stability and other excellent properties.

Reference is made to fig. 1. In some embodiments, the semiconductor laser structure of the present invention further includes an end-facet reflective structure 16. Wherein there are two end surface reflecting structures 16, and two end surface reflecting structures 16 are provided on both sides of quantum dot structure 12 and surface plasmon structure 13, respectively, and pass through first semiconductor layer 11.

Since the SPP-based laser confines photoelectrons to the surfaces of the metal layer 15 and the dielectric layer 14 and propagates along the metal-dielectric interface, in order to limit the propagation direction of light, end-surface reflecting structures 16 may be provided on both sides of the semiconductor laser structure, i.e. on both sides of the quantum dot structure 12 and the surface plasmon structure 13, which may in principle provide a fabry-perot resonator reflecting surface for the propagation of SPP, and when the surface plasmon propagates to the end-surface reflecting structures 16, it will be reflected by the opposite surfaces of the two end-surface reflecting structures 16, thus propagating reciprocally to form oscillations.

In some embodiments, the end surface reflective structures 16 on both sides have opposing surfaces with equal or unequal reflectivity.

In some embodiments, the end surface reflection structures 16 on both sides are respectively formed by metal materials having different reflectivities, so that the end surface reflection structures 16 on both sides have opposite surfaces having different reflectivities.

In some embodiments, the two side end surface reflective structures 16 are formed by a single dielectric insulating layer of the same material such that the two side end surface reflective structures 16 have opposite surfaces of equal reflectivity.

In some embodiments, the end surface reflection structures 16 on both sides are respectively formed by single dielectric insulating layers of different materials, so that the end surface reflection structures 16 on both sides have opposite surfaces with different reflectivities.

In some embodiments, the end surface reflective structure 16 forms a composite reflective layer from a plurality of dielectric insulating layers arranged in a horizontal direction. Wherein, the refractive index between any two adjacent insulating mediums in the composite reflecting layer is different. Or the materials between any two adjacent insulating media in the composite reflecting layer are different. Also, the order of arrangement of the dielectric insulating layers in the two-sided end surface reflection structure 16 may be the same or different. By laterally stacking several insulating dielectric films of different refractive indexes or different materials, effective reflection of equal or unequal reflectivity to surface plasmons can be formed on opposite surfaces of the two end surface reflection structures 16.

In some embodiments, the metallic material of the end surface reflective structure 16 comprises gold, silver, copper, or aluminum. The dielectric insulating layer material comprises silicon nitride, silicon dioxide, silicon oxynitride or nitrogen-containing silicon carbide. The composite reflecting layer material comprises at least two of silicon nitride, silicon dioxide, silicon oxynitride and silicon carbide containing nitrogen.

In some embodiments, a semiconductor laser structure is provided on the SOI substrate 100. The SOI substrate 100 includes a bottom silicon layer 103, a buried oxide layer 102, and a top silicon layer 101, which are sequentially disposed. Wherein the top silicon layer 101 forms the first semiconductor layer 11 (or the first semiconductor layer 11 is formed by the top silicon layer 101). And, the bottom of the end surface reflection structure 16 passes through the top silicon layer 101 and falls on the buried oxide layer 102, and the top of the end surface reflection structure 16 is not lower than the surface of the metal layer 15.

The semiconductor laser structure further forms a germanium quantum dot laser based on surface plasmons.

The innovation point of the invention is that a novel germanium quantum dot (Ge QDs) laser structure based on surface plasmons is provided according to SPP theory. The laser is generated by the process that firstly, the gain medium is excited by external photon radiation to generate electron-hole pairs, the electron-hole pairs relax to an exciton state, when the gain medium is positioned on a resonant metal surface, exciton energy is transferred into an SPP mode in a metal layer through resonance coupling, the coupling action can provide another composite channel for the laser, and when electrons localized in the SPP mode state meet the population inversion condition, the laser is radiated. In the process, the surface plasmon is generated by a metal structure, the gain material around the medium amplifies the surface plasmon and resonates in the nanoscale resonant cavity, and the mode size and the physical size of the laser can be reduced to be below half wavelength at the same time, so that the nanoscale coherent light source which far exceeds the diffraction limit and has ultra-fast dynamics characteristics is formed.

The following describes a semiconductor laser structure manufacturing method according to the present invention in further detail by means of the detailed description and with reference to the accompanying drawings.

Reference is made to fig. 2-7. The method for preparing the semiconductor laser structure of the present invention can be used for preparing the semiconductor laser structure of the present invention shown in fig. 1, for example, a germanium quantum dot laser structure based on surface plasmon (SPP), and comprises the following steps:

step S1 provides a substrate having a first semiconductor layer 11 on a surface thereof.

As shown in fig. 2, a cleaned SOI substrate 100 is employed. The SOI substrate 100 is provided with a bottom silicon layer 103, a buried oxide layer 102, and a top silicon layer 101 in this order from bottom to top. The top silicon layer 101 is used as the first semiconductor layer 11, so that other component structures in the semiconductor laser structure can be further prepared on the top silicon layer 101.

In some embodiments, a cleaning process such as ultrasonic cleaning plus an organic solvent soak is used to remove particulates, organics, etc. from the surface of the SOI substrate 100 and a gas purge dry is performed.

Step S2, forming a quantum dot structure 12 on the surface of the first semiconductor layer 11.

A quantum dot structure 12 is formed on the surface of the first semiconductor layer 11 (top silicon layer 101), including a plurality of quantum dots 121 formed and distributed on the surface of the first semiconductor layer 11.

As shown in fig. 3, an epitaxial window 18 is formed on the surface of the top silicon layer 101 using a photolithography and etching process.

A photolithographic masking layer 17 may be grown on the surface of the top silicon layer 101 using, for example, a Plasma Enhanced Chemical Vapor Deposition (PECVD) process. The mask layer 17 material may be, for example, silicon dioxide.

Then, an epitaxial window 18 is formed on the surface of the mask layer 17 by photolithography and etching processes, exposing the surface of the top silicon layer 101.

In some embodiments, after the surface of the mask layer 17 is subjected to the photolithography processing of the epitaxial window 18, in order to prepare an epitaxial window 18 region with high sharpness and uniform and smooth width, an ICP etching process with high selectivity and directionality is selected, and the surface of the mask layer 17 after the photolithography is subjected to the etching of the epitaxial window 18, so that not only can good etching directionality be obtained, but also the etching speed is greatly improved.

And after etching and photoresist removal, cleaning is carried out to remove residual photoresist and residual particles, so that preparation is carried out for the next silicon-based germanium (second semiconductor) epitaxy.

As shown in fig. 4, germanium quantum dots 121 are formed in epitaxial window 18 using an epitaxial process.

Due to the lattice mismatch and thermal expansion mismatch of about 4.18% between germanium and silicon, germanium is heterologously delayed on the top silicon layer 101, and when the thickness of the initial layer exceeds the critical thickness, it will grow through the S-K (Stranski-Krastanov) mode and form self-assembled islands 1211 of energy quantized germanium, namely germanium quantum dots 121 (Ge QDs), on the top silicon layer 101, thereby forming a plurality of germanium quantum dots 121 distributed on the surface of the top silicon layer 101 and forming germanium quantum dot structures 12 in the epitaxial window 18.

The optimization of the germanium quantum dots 121 may be achieved by optimizing external delay growth parameters, such as substrate temperature, deposition rate, germanium coverage, and annealing temperature and time.

In other embodiments, schemes of selectively growing island structures of germanium quantum dots in patterned nanoscale regions may also be used. The scheme includes that a pre-pattern array is manufactured on a top silicon layer, and then an island-shaped structure of germanium quantum dots is grown in gaps of the pre-pattern array through an epitaxial process.

Step S3, forming a surface plasmon structure 13 on the quantum dot structure 12.

The formation of surface plasmonic structures 13 on quantum dot structure 12 includes forming a dielectric layer 14 overlying the surfaces of the plurality of quantum dots 121, and forming a metal layer 15 on the surface of dielectric layer 14.

As shown in fig. 5, a deposition process is used to form a dielectric layer 14 on the surface of mask layer 17, and the deposited dielectric layer 14 covers the entire exposed surface of quantum dot structure 12 (germanium quantum dots 121 in the form of a plurality of self-assembled islands 1211) in the epitaxial window 18.

A layer of stable silicon dioxide may be grown as dielectric layer 14 using a Plasma Enhanced Chemical Vapor Deposition (PECVD) process.

Alternatively, atomic Layer Deposition (ALD) techniques may be used to deposit aluminum oxide as dielectric layer 14.

Thereafter, a planar surface of the dielectric layer 14 is obtained by planarizing the top of the dielectric layer 14, such as by a chemical mechanical polishing process. The planarized surface of the dielectric layer 14 needs to be a distance above the tops of the plurality of quantum dots 121 to completely cover the quantum dot structure 12.

As shown in fig. 6, a deposition process is used to form a metal layer 15 on the surface of the dielectric layer 14, and the metal layer 15 is located above the quantum dot structure 12.

Gold may be preferentially deposited as the material of the metal layer 15 due to its good stability and other excellent properties. A PVD process, such as sputtering or evaporation, may be used to deposit a gold layer as the metal layer 15 on the dielectric layer 14.

And S4, forming end surface reflection structures 16 on two sides of the quantum dot structure 12 and the surface plasmon structure 13.

As shown in fig. 7, a photolithography and etching process is first used to form trenches with bottoms penetrating through the metal layer 15, the dielectric layer 14 and the top silicon layer 101 in sequence on the surfaces of the metal layers 15 on both sides of the quantum dot structure 12, and the bottoms of the trenches are stopped on the buried oxide layer 102 (the mask layer 17 may be removed or left before the end surface reflection structure 16 if necessary, and if the mask layer 17 is still left in this step, the trenches need to penetrate through the metal layer 15, the dielectric layer 14, the mask layer 17 and the top silicon layer 101 in sequence).

Then, by filling the trench, the end surface reflection structure 16 is formed in the trench, so that one end surface reflection structure 16 is formed on each side of the quantum dot structure 12 and the surface plasmon structure 13. The top of the end surface reflection structure 16 is not lower than the surface of the metal layer 15, and the bottom of the end surface reflection structure 16 passes through the top silicon layer 101 and is located on the oxygen-buried layer 102.

In some embodiments, when filling the trenches, the trenches on both sides can be filled by deposition of different metals.

In some embodiments, when filling the trenches, the same dielectric insulating layer or different dielectric insulating layers of the single layer may be deposited on the trenches on both sides.

In some embodiments, during trench filling, sequential deposition filling of multiple dielectric insulating layers may be performed on the trench along the inner wall surface of the trench until the trench is filled. The trenches are sequentially filled with at least two materials of silicon nitride, silicon dioxide, silicon oxynitride, nitrogen-containing silicon carbide and the like, so that any two adjacent dielectric insulating layers have different refractive indexes, and an end surface reflecting structure 16 of a composite reflecting layer structure radially stacked along the trenches is formed. The filling order of each dielectric insulating layer in the grooves at two sides can be the same or different.

By forming the end surface reflection structures 16, it is possible to efficiently reflect when surface plasmons propagate to the opposite surfaces of the two end surface reflection structures 16.

The end surface reflecting structure 16 is formed and simultaneously the metal layer 15 and the dielectric layer 14 are patterned, so that the patterned surface plasmon structure 13, the quantum well structure and the first semiconductor layer 11 are patterned between the two end surface reflecting structures 16.

In summary, the quantum dot structure 12 (germanium quantum dot structure 12) is formed on the first semiconductor layer 11 (top silicon layer 101), and the surface plasmon structure 13 formed by the metal layer 15 and the dielectric layer 14 is formed on the quantum dot structure 12, so that near-field optical enhancement of a quantum dot laser (germanium quantum dot laser) formed by the semiconductor laser structure is realized based on the surface plasmon, and the comprehensive performance of the quantum dot laser is improved. In addition, the preparation process flow of the laser can be optimized, the preparation difficulty is reduced, and the emission power and the spectral purity of the quantum dot laser are enhanced, so that the problems of high preparation difficulty and poor emission power and spectral purity of the traditional germanium quantum dot laser are effectively solved, and the comprehensive performance of the quantum dot laser is improved.

While embodiments of the present invention have been described in detail hereinabove, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. It is to be understood that such modifications and variations are within the scope and spirit of the present invention as set forth in the following claims. Moreover, the invention described herein is capable of other embodiments and of being practiced or of being carried out in various ways.

Claims

1. A semiconductor laser structure, characterized in that it comprises:

A quantum dot structure disposed on the surface of the first semiconductor layer, the quantum dot structure comprising a plurality of quantum dots distributed on the surface of the first semiconductor layer;

A surface plasmon structure is provided on the quantum dot structure.

2. The semiconductor laser structure according to claim 1 is characterized in that the quantum dots include self-assembled islands formed by a second semiconductor on the surface of the first semiconductor layer, and the surface plasmon structure includes a dielectric layer covering the quantum dot structure and a metal layer located on the dielectric layer.

3. The semiconductor laser structure according to claim 2, characterized in that the first semiconductor comprises silicon; and/or the second semiconductor comprises germanium; and/or the dielectric layer comprises silicon dioxide or aluminum oxide; and/or the metal layer comprises gold, silver, copper or aluminum.

4. The semiconductor laser structure according to claim 1 is characterized in that it also includes an end face reflection structure, which is arranged on both sides of the quantum dot structure and the surface plasmon structure and passes through the first semiconductor layer, and the end face reflection structures on both sides have relative surfaces with equal or unequal reflectivity.

5. The semiconductor laser structure according to claim 1 is characterized in that the semiconductor laser structure is arranged on an SOI substrate, the SOI substrate comprises a bottom silicon layer, a buried oxide layer and a top silicon layer arranged in sequence, and the top silicon layer forms the first semiconductor layer.

6. A method for preparing a semiconductor laser structure, comprising:

Providing a substrate having a first semiconductor layer on its surface;

forming a quantum dot structure on a surface of the first semiconductor layer;

A surface plasmon structure is formed on the quantum dot structure.

7. The method for preparing a semiconductor laser structure according to claim 6 is characterized in that the forming of a quantum dot structure on the surface of the first semiconductor layer comprises forming a plurality of quantum dots distributed on the surface of the first semiconductor layer; and the forming of a surface plasmon structure on the quantum dot structure comprises forming a dielectric layer covering the surfaces of the plurality of quantum dots, and forming a metal layer on the surface of the dielectric layer.

8. The method for preparing a semiconductor laser structure according to claim 7, wherein the method for forming a plurality of quantum dots comprises:

forming an epitaxial window on the surface of the first semiconductor layer, epitaxially forming energy quantized self-assembled islands of a second semiconductor material in the epitaxial window, thereby forming a plurality of quantum dots distributed on the surface of the first semiconductor layer;

The method for forming the dielectric layer and the metal layer specifically includes:

forming a dielectric layer on the surface of the first semiconductor layer to cover the exposed surfaces of the plurality of quantum dots, so that the top of the dielectric layer is higher than the tops of the plurality of quantum dots, and obtaining a flat surface of the dielectric layer by planarization;

A metal layer is formed on the surface of the dielectric layer and is located above the plurality of quantum dots.

9. The method for preparing a semiconductor laser structure according to claim 7, further comprising: forming end face reflection structures on both sides of the quantum dot structure that sequentially penetrate the metal layer, the dielectric layer and the first semiconductor layer, and making the end face reflection structures on both sides have relative surfaces with equal or unequal reflectivity.

10. The method for preparing a semiconductor laser structure according to claim 9, characterized in that the substrate comprises an SOI substrate, the SOI substrate comprises a bottom silicon layer, a buried oxide layer and a top silicon layer arranged in sequence, the top silicon layer is the first semiconductor layer; when forming the end face reflection structure, specifically comprising:

Forming grooves on both sides of the quantum dot structure that sequentially penetrate the metal layer, the dielectric layer, and the first semiconductor layer, and stop on the buried oxide layer;

Metals with different reflectivity are deposited on the grooves on both sides, or a single layer of the same dielectric insulating layer or different dielectric insulating layers are deposited, or multiple dielectric insulating layers are deposited in sequence, and the refractive index between any two adjacent dielectric insulating layers is different, and the filling order of each dielectric insulating layer in the grooves on both sides is the same or different, thereby forming an end face reflection structure with the bottom passing through the top silicon layer on both sides of the quantum dot structure and the surface plasmon structure.