Periodic quantum dot enhanced semiconductor saturable absorption mirror and preparation method thereof
By using self-assembly technology and etching process to form a periodic nanocylindrical grating layer in a semiconductor saturable absorber, the complexity and insufficient performance of epitaxial growth process are solved, and efficient pulse width compression and laser amplification effect is achieved. It is suitable for Commercial production.
Patent Information
- Application Number
- CN202411022319.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-29
- Publication Date
- 2024-12-20
AI Technical Summary
The epitaxial growth process of existing semiconductor saturable absorber mirrors is complex and difficult, resulting in insufficient performance and difficult to meet the complex needs of ultrafast lasers.
The self-assembly technology and etching process are used to form a periodic nanocylindrical grating layer and a dielectric film grating layer on the substrate. By adjusting the diameter of the polystyrene microspheres, the grating structure is accurately controlled, reducing the preparation difficulty and improving performance.
It achieves high controllability and consistency of semiconductor saturable absorber, significantly improving the pulse width compression effect and laser output power, and is suitable for large-scale commercial production.
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Figure CN119171171A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductor technology, and in particular to a periodic quantum dot enhanced semiconductor saturable absorber mirror and a preparation method thereof. Background Art
[0002] With the rapid development of the laser industry, the requirements for laser performance are also increasing. Under the diversified and complex laser application requirements, traditional continuous lasers have gradually failed to meet the high standards of precision processing and other fields. Ultrafast pulsed lasers have shown excellent application potential in the field of precision laser processing with their advantages such as high single pulse energy, high peak power and low heat accumulation. These lasers have been widely used in many fields such as consumer electronics, display panels, and medical treatment. Semiconductor saturable absorber mirrors (SESAMs) have shown good repeatability and stability due to the use of mature semiconductor materials and processes, and are easy to achieve commercial production. Therefore, SESAM has become the most widely used and most used passive mode-locked element in ultrafast pulsed lasers.
[0003] However, since the epitaxial growth process of SESAM is very complex and difficult, it is very challenging to significantly improve and adjust the performance by simply improving the growth conditions. In other words, the preparation method of the epitaxial growth process is complex and difficult, and the prepared semiconductor saturable absorber is difficult to meet the increasingly complex ultrafast laser performance requirements. Summary of the invention
[0004] The embodiments of the present application provide a periodic quantum dot enhanced semiconductor saturable absorber mirror and a method for preparing the same, which at least solve the problem that the preparation method of the epitaxial growth process in the related art is complex and difficult, and the performance of the prepared semiconductor saturable absorber mirror is poor.
[0005] According to a first aspect of an embodiment of the present application, a method for preparing a periodic quantum dot enhanced semiconductor saturable absorber mirror is provided, comprising:
[0006] A Bragg reflection layer, a buffer layer, a quantum dot absorption layer, a cap layer and a mask layer are sequentially prepared on a substrate;
[0007] Laying a layer of polystyrene microspheres on the mask layer based on self-assembly technology;
[0008] Adjusting the diameter of the polystyrene microspheres to a preset target diameter by etching;
[0009] Using the polystyrene microspheres adjusted to the target diameter as a mask, etching the mask layer to etch the mask layer into a periodic two-dimensional grating pattern layer;
[0010] After removing the polystyrene microspheres, the quantum dot absorption layer and the cover layer on the substrate are etched using the two-dimensional grating cluster layer as a mask;
[0011] The periodic two-dimensional grating pattern layer is removed, a first dielectric film layer is deposited on the etched cover layer, and a second dielectric film layer is deposited on the buffer layer, so as to generate a periodic nano-cylindrical grating layer based on the etched quantum dot absorption layer, the cover layer and the first dielectric film layer, and a dielectric film grating layer is generated based on the second dielectric film layer.
[0012] According to a second aspect of an embodiment of the present application, a periodic quantum dot enhanced semiconductor saturable absorber mirror is provided, comprising: a substrate, a Bragg reflection layer, a buffer layer and a grating layer arranged in sequence from bottom to top, the grating layer comprising a periodic nano-cylindrical grating layer and a dielectric film grating layer, the periodic nano-cylindrical grating layer and the dielectric film grating layer are both arranged on the buffer layer, the periodic nano-cylindrical grating layer comprises a plurality of periodically arranged nano-cylindrical gratings, and the dielectric film grating layer is provided with holes adapted to the plurality of periodically arranged nano-cylindrical gratings;
[0013] The nano cylindrical grating includes a quantum dot absorption layer, a cover layer and a first dielectric film layer which are arranged in sequence from bottom to top, and the dielectric film grating layer includes a second dielectric film layer.
[0014] According to a third aspect of an embodiment of the present application, a saturable absorption device is provided, comprising: a compound semiconductor saturable absorption mirror, wherein the compound semiconductor saturable absorption mirror is prepared based on the method described in the first aspect.
[0015] According to a fourth aspect of an embodiment of the present application, there is provided an application of the preparation method described in the first aspect in the field of semiconductor lasers.
[0016] The preparation method of a periodic quantum dot enhanced semiconductor saturable absorber provided in the embodiment of the present application can reduce the complexity and difficulty of preparing the semiconductor saturable absorber and improve the performance of the semiconductor saturable absorber. Specifically, a Bragg reflector layer, a buffer layer, a quantum dot absorption layer, a cap layer and a mask layer are prepared on the substrate in sequence, and a structure having a periodic nano cylindrical grating layer and a dielectric film grating layer is formed by using the self-assembly technology and etching process of polystyrene microspheres. By adjusting the diameter of the polystyrene microspheres, the size and period of the periodic nano cylindrical grating layer can be accurately controlled to make it suitable for different application scenarios. Standard semiconductor technology is used to ensure high controllability and consistency, which is suitable for large-scale commercial production and significantly reduces manufacturing costs. The periodic quantum dot enhanced semiconductor saturable absorber prepared by the preparation method achieves a high pulse width compression effect in the joint action of the Bragg reflector and the periodic nano cylindrical grating layer, and optimizes the output characteristics of the pulsed laser. The micro-resonant cavity formed by the first dielectric film layer and the second dielectric film on the top and the Bragg reflector effectively amplifies the pulsed laser, improves the output power and stability of the laser, and exhibits superior performance in various laser applications. Based on the above method, the size and period of the nanocolumns and dielectric film layers can be accurately adjusted, and the preparation cost and difficulty are reduced and the consistency is improved, thereby achieving excellent pulse width compression and laser amplification effects.
[0017] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other embodiments can be obtained based on these drawings without creative work.
[0019] Figure 1 A flow chart of a method for preparing a periodic quantum dot enhanced semiconductor saturable absorber mirror provided in an embodiment of the present application.
[0020] Figure 2 A schematic structural diagram of a periodic quantum dot enhanced semiconductor saturable absorber mirror provided in an embodiment of the present application.
[0021] Figure 3 A schematic diagram of the structure of a periodic nano-cylindrical grating layer provided in an embodiment of the present application.
[0022] Figure 4A schematic diagram of the structure of a plasma membrane grating layer provided in an embodiment of the present application.
[0023] Figure 5 A schematic diagram of the structure of a sample after epitaxial growth of a SESAM layer provided in an embodiment of the present application.
[0024] Figure 6 A schematic diagram of the structure of a sample after deposition of a silicon dioxide film provided in an embodiment of the present application.
[0025] Figure 7 A schematic diagram of the structure of a sample after self-assembly of polystyrene microspheres provided in an embodiment of the present application.
[0026] Figure 8 A schematic diagram of the structure of a polystyrene microsphere sample after etching provided in an embodiment of the present application.
[0027] Fig. 9 A schematic diagram of the structure of a sample after etching of a silicon dioxide film provided in an embodiment of the present application.
[0028] Fig.10 A schematic diagram of the structure of a sample after removing polystyrene microspheres provided in an embodiment of the present application.
[0029] Fig.11 A schematic diagram of the structure of a sample after inductively coupled plasma etching provided in an embodiment of the present application.
[0030] Fig.12 A schematic diagram of the structure of a sample after re-deposition of a silicon dioxide film provided in an embodiment of the present application.
[0031] Fig.13 This is a photoluminescence spectrum test diagram of a periodic quantum dot enhanced semiconductor saturable absorber mirror provided in an embodiment of the present application.
[0032] Fig.14 A reflection spectrum test diagram of a periodic quantum dot enhanced semiconductor saturable absorber mirror provided in an embodiment of the present application.
[0033] Fig.15 A test diagram of the nonlinear absorption characteristics of a periodic quantum dot enhanced semiconductor saturable absorber mirror provided in an embodiment of the present application.
[0034] In the figure, 1, substrate; 2, buffer layer; 3, Bragg reflection layer; 4, quantum dot absorption layer; 5, cover layer; 6, first dielectric film layer; 7, second dielectric film layer. DETAILED DESCRIPTION
[0035] Embodiments of the present embodiment will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present embodiment are shown in the accompanying drawings, it should be understood that the present embodiment can be implemented in various forms and should not be construed as being limited to the embodiments set forth herein, which are instead provided for a more thorough and complete understanding of the present embodiment. It should be understood that the drawings and embodiments of the present embodiment are only for exemplary purposes and are not intended to limit the scope of protection of the present embodiment.
[0036] Some embodiments of the present application are described in detail below in conjunction with the accompanying drawings. In the case where there is no conflict between the embodiments, the following embodiments and the features in the embodiments can be combined with each other. In addition, the step sequence in the following method embodiments is only an example and not a strict limitation.
[0037] With the rapid development of the laser industry and the increasing diversification and complexity of laser application requirements, conventional lasers are increasingly unable to meet existing needs. Compared with continuous lasers, ultrafast pulsed lasers have shown strong application advantages in the field of precision laser processing due to their high single pulse energy, high peak power and low heat accumulation. They are widely used in many fields such as consumer electronics, display panels, and medical treatment. Ultrafast pulsed lasers are capable of fine material cutting, micromachining, and surface treatment, meeting the requirements of modern industry for high precision and high efficiency.
[0038] One of the key elements to achieve ultrafast pulsed lasers is the saturable absorber. Current research on saturable absorber materials includes carbon nanotubes, graphene, transition metal sulfides, topological insulators, and semiconductor saturable absorber mirrors (SESAMs). Among them, carbon nanotubes, graphene, transition metal sulfides, and topological insulators are emerging saturable absorber materials in recent years, with excellent nonlinear optical properties and broadband absorption capabilities. However, their preparation processes have great challenges in terms of repeatability and consistency, making it difficult to achieve large-scale production, limiting their widespread application.
[0039] In contrast, SESAM is made of semiconductor materials and standard semiconductor processes, and has the advantages of good repeatability, stability and easy commercial production, making it the most widely used passive mode-locking element for ultrafast pulsed lasers. SESAM can achieve effective modulation and control of laser pulses through carefully designed epitaxial growth and structural optimization. However, although relevant technologies have conducted a lot of research on the epitaxial growth of quantum well and quantum dot SESAMs, attempting to improve their performance parameters by adjusting the epitaxial growth conditions, due to the complexity and difficulty of the epitaxial growth process itself, there are still many challenges to achieving performance improvement by simply improving the epitaxial growth conditions. Therefore, developing new structures and process methods to further optimize the performance of SESAM has become an important direction of current research.
[0040] To solve the above problems, the embodiments of the present application provide a periodic quantum dot enhanced semiconductor saturable absorber mirror and a method for preparing the same, so as to solve the problems in the related art that the preparation method of the epitaxial growth process is complex and difficult, and the performance of the prepared semiconductor saturable absorber mirror is poor.
[0041] Figure 1 A flow chart of a method for preparing a periodic quantum dot enhanced semiconductor saturable absorber mirror provided in an embodiment of the present application. Figure 1 As shown, the method comprises the following steps:
[0042] Step S101, sequentially preparing a Bragg reflection layer, a buffer layer, a quantum dot absorption layer, a cap layer and a mask layer on a substrate.
[0043] Step S102: laying a layer of polystyrene microspheres on the mask layer based on the self-assembly technology.
[0044] Step S103, adjusting the diameter of the polystyrene microspheres to a preset target diameter by etching.
[0045] In step S104 , the mask layer is etched using the polystyrene microspheres adjusted to a target diameter as a mask, so as to be etched into a periodic two-dimensional grating pattern layer.
[0046] Step S105 , after removing the polystyrene microspheres, the quantum dot absorption layer and the cover layer on the substrate are etched using the two-dimensional grating cluster layer as a mask.
[0047] Step S106, remove the periodic two-dimensional grating pattern layer, deposit a first dielectric film layer on the etched cover layer, and deposit a second dielectric film layer on the buffer layer, so as to generate a periodic nano-cylindrical grating layer based on the etched quantum dot absorption layer, the cover layer and the first dielectric film layer, and generate a dielectric film grating layer based on the second dielectric film layer.
[0048] Firstly, a Bragg reflection layer, a buffer layer, a quantum dot absorption layer, a cap layer and a mask layer are sequentially prepared on a substrate.
[0049] In this embodiment, the substrate serves as the basis of the entire structure, and semiconductor materials such as silicon or gallium arsenide are generally used. The Bragg reflector layer is formed by alternately depositing multiple layers of optical materials, and can be used to reflect light of a specific wavelength to form a mirror with high reflectivity. The buffer layer can be used to reduce lattice mismatch and stress to ensure the growth quality of subsequent layers. The quantum dot absorption layer contains periodically distributed quantum dots that can absorb light of a specific wavelength and produce a saturable absorption effect. The cap layer can protect the quantum dot absorption layer while optimizing the optical performance. The mask layer can be used in subsequent lithography and etching steps to form a precise pattern structure.
[0050] In an optional embodiment, when the Bragg reflection layer, the buffer layer, the quantum dot absorption layer, the cap layer and the mask layer are sequentially prepared on the substrate, the Bragg reflection layer, the buffer layer, the quantum dot absorption layer and the cap layer can first be epitaxially grown sequentially on the substrate, and then the mask layer can be prepared on the cap layer by plasma enhanced chemical vapor deposition.
[0051] Optionally, the mask layer may include a silicon dioxide mask layer, a silicon nitride mask layer, a tantalum oxide mask layer, etc. The thickness of the mask layer may be 50 nm to 200 nm.
[0052] Then, a layer of polystyrene microspheres is laid on the mask layer based on the self-assembly technology. In this embodiment, the diameter of the polystyrene microspheres can be 200nm to 700nm.
[0053] In this embodiment, the self-assembly technology is a technology that utilizes the spontaneous arrangement characteristics of microspheres in a solution to achieve uniform distribution. The size of polystyrene microspheres is controllable and can be used as an etching mask to provide high-precision pattern formation.
[0054] After laying a layer of polystyrene microspheres on the mask layer based on the self-assembly technology, the diameter of the polystyrene microspheres can be adjusted to a preset target diameter by etching.
[0055] In this embodiment, the diameter of the polystyrene microspheres can be reduced by etching technology to reach a preset target size. Optionally, the preset target diameter can include 30% to 80% of the diameter of the polystyrene microspheres.
[0056] In an optional embodiment, when the diameter of the polystyrene microspheres is adjusted to the preset target diameter by etching, the polystyrene microspheres may be etched by a reactive ion etcher to adjust the diameter of the polystyrene microspheres to the preset target diameter.
[0057] After the diameter of the polystyrene microspheres is adjusted to a preset target diameter, the mask layer can be etched using the polystyrene microspheres adjusted to the target diameter as a mask, so as to etch the mask layer into a periodic two-dimensional grating pattern layer.
[0058] In an optional embodiment, polystyrene microspheres adjusted to a target diameter may be used as a mask, and a reactive ion etcher may be used to etch the mask layer to form a periodic two-dimensional grating pattern layer.
[0059] Subsequently, after removing the polystyrene microspheres, the quantum dot absorption layer and the capping layer are etched based on the periodic two-dimensional grating pattern layer to remove the quantum dot absorption layer and the capping layer outside the area covered by the periodic two-dimensional grating pattern layer on the substrate.
[0060] In this embodiment, the polystyrene microspheres can be removed by using a solvent or heat treatment. Optionally, the solvent can include acetone or the like.
[0061] In an optional embodiment, the polystyrene microspheres can be removed by acetone, and then the periodic two-dimensional grating pattern layer is cleaned and dried by a preset cleaning solution. Finally, the quantum dot absorption layer and the cover layer are etched by an inductively coupled plasma etcher using the periodic two-dimensional grating pattern layer as a mask to remove the quantum dot absorption layer and the cover layer outside the periodic two-dimensional grating pattern layer coverage area on the substrate.
[0062] In this embodiment, when the polystyrene microspheres are removed by acetone, the sample may be immersed in an acetone solution; the preset cleaning solution may include ethanol, deionized water, and the like.
[0063] Finally, the periodic two-dimensional grating pattern layer is removed, and a first dielectric film layer is deposited on the etched cover layer, and a second dielectric film layer is deposited on the buffer layer, so as to generate a first grating unit based on the etched quantum dot absorption layer, the cover layer and the first dielectric film layer, and generate a second grating unit based on the second dielectric film layer.
[0064] In an optional embodiment, the periodic two-dimensional grating pattern layer can be removed by a preset cleaning solvent; the first dielectric film layer is deposited on the cap layer and the second dielectric film layer is deposited on the buffer layer by a plasma enhanced chemical vapor deposition method.
[0065] In this embodiment, the preset cleaning solvent may include hydrofluoric acid, an acidic or alkaline remover or an organic solvent, etc. In practical applications, the sample may be immersed in the preset cleaning solvent for 1 to 3 minutes to remove the periodic two-dimensional grating pattern layer. Furthermore, the periodic two-dimensional grating pattern layer may also be removed by selective etching.
[0066] In another optional embodiment, the periodic two-dimensional grating pattern layer can be retained, and the retained periodic two-dimensional grating pattern layer is used as the first dielectric film layer. In addition, the second dielectric film layer is deposited only on the buffer layer.
[0067] The first dielectric film layer and thickness and the second dielectric film thickness can be the same or different. Different functions can be achieved by setting different first dielectric film layers and thicknesses and second dielectric film thicknesses.
[0068] In an optional embodiment, the first dielectric film layer and the second dielectric film layer may include a silicon dioxide mask layer, a silicon nitride mask layer, a tantalum oxide mask layer, etc. The thickness of the first dielectric film layer and the second dielectric film layer may be 100 nm to 200 nm.
[0069] Based on the above method, through a series of precise preparation and etching steps, a grating structure with a periodic nanocylindrical grating (i.e., a periodic nanocylindrical grating layer) and a dielectric film grating layer (i.e., a second dielectric film layer) is formed on the substrate, which significantly enhances the optical performance of the quantum dot absorption layer. The use of polystyrene microsphere self-assembly and etching process not only achieves high-precision structural control, but also reduces production costs. This method uses standard semiconductor processes, has good repeatability and consistency, is suitable for large-scale commercial production, and effectively improves the pulse width compression and amplification effects of the laser through the optimized grating structure, providing strong technical support for the application of ultrafast pulsed lasers in consumer electronics, display panels, and medical fields.
[0070] Based on the method for preparing the periodic quantum dot enhanced semiconductor saturable absorber mirror in the above-mentioned embodiment, the embodiment of the present application further provides a periodic quantum dot enhanced semiconductor saturable absorber mirror.
[0071] Figure 2 The schematic diagram of the structure of a periodic quantum dot enhanced semiconductor saturable absorber provided in the embodiment of the present application. Figure 2 As shown, the semiconductor saturable absorption mirror comprises:
[0072] The substrate 1, Bragg reflection layer 2, buffer layer 3 and grating layer are arranged in sequence from bottom to top. The grating layer includes a periodic nano-cylindrical grating layer and a dielectric film grating layer. The periodic nano-cylindrical grating layer and the dielectric film grating layer are both arranged on the buffer layer 3. The periodic nano-cylindrical grating layer includes a plurality of periodically arranged nano-cylindrical gratings. The dielectric film grating layer is provided with a hole buffer layer 3 adapted to the plurality of periodically arranged nano-cylindrical gratings. The structural schematic diagram of the periodic nano-cylindrical grating layer is shown in FIG. Figure 3 The structural diagram of the dielectric film grating layer is shown in Figure 4 shown.
[0073] The nano cylindrical grating includes a quantum dot absorption layer 4, a cap layer 5 and a first dielectric film layer 6 arranged in sequence from bottom to top, and the dielectric film grating layer includes a second dielectric film layer 7. In this embodiment, the substrate 1 can be used to support the entire structure, provide mechanical strength and thermal conductivity. Specifically, the material of the substrate 1 can include gallium arsenide, silicon, etc., and an adaptive thickness is selected to ensure sufficient mechanical strength and thermal conductivity.
[0074] The Bragg reflector layer 2 can form a mirror with high reflectivity, enhance the light reflection effect, and improve the laser output efficiency. Specifically, the Bragg reflector layer 2 can be made of alternating stacks of high and low refractive index materials, such as gallium arsenide / aluminum gallium arsenide, aluminum nitride / gallium nitride, etc.; the thickness of each layer of the Bragg reflector layer 2 can be a multiple of a quarter wavelength.
[0075] The buffer layer 3 can reduce the lattice mismatch between the substrate 1 and the upper layer material, improve the interface quality, and protect the quantum dot absorption layer 4. Specifically, the material of the buffer layer 3 may include aluminum gallium arsenide, indium phosphide, and the like.
[0076] The nano cylindrical grating can be used to absorb light of a specific wavelength and modulate light pulses. Specifically, the nano cylindrical grating is composed of a quantum dot absorption layer 4, a cap layer 5 and a first dielectric film layer 6. The material of the quantum dot absorption layer 4 may include indium gallium arsenide (InGaAs) quantum dots, etc.; the material of the cap layer 5 may include gallium arsenide, etc.; the material of the first dielectric film layer 6 may include silicon dioxide, silicon nitride tantalum oxide, etc., and the thickness may be 100nm to 200nm.
[0077] The dielectric film grating layer can provide contrast of the grating structure and enhance the diffraction effect. Specifically, the material of the second dielectric film layer 7 may include silicon dioxide, silicon nitride, tantalum oxide, etc., and the thickness may be 100nm to 200nm.
[0078] The following is a detailed description of the method for preparing the periodic quantum dot enhanced semiconductor saturable absorber mirror provided by the embodiment of the present invention in conjunction with the accompanying drawings and specific embodiments. Specifically, the method comprises the following steps:
[0079] Step 1: Prepare the substrate.
[0080] In this embodiment, a gallium arsenide substrate with a clean surface and no dirt is used to ensure that the surface is smooth and free of defects.
[0081] Step 2: epitaxially grow a SESAM layer.
[0082] In this embodiment, metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) equipment is used on a gallium arsenide substrate to sequentially grow the following layers:
[0083] Bragg reflection layer: a multi-layer structure that enhances light reflection. Buffer layer: reduces lattice mismatch and improves crystal quality. Quantum dot absorption layer: used to absorb light of a specific wavelength. Cover layer: protects the quantum dot absorption layer and improves structural stability.
[0084] Among them, the structural schematic diagram of the sample after epitaxial growth of the SESAM layer is as follows Figure 5 shown.
[0085] Step 3: depositing a silicon dioxide film.
[0086] In this embodiment, a layer of silicon dioxide film is deposited on the surface of the SESAM layer using a plasma chemical vapor deposition device.
[0087] The deposition parameters are: silane flow rate is 12 sccm, nitrous oxide flow rate is 480 sccm, nitrogen flow rate is 240 sccm, pressure is 90 Pa, RF power is 50 W, heater temperature is 350° C., and deposition time is 1-2 minutes.
[0088] The schematic diagram of the structure of the sample after deposition of silicon dioxide film is shown in the figure. Figure 6 shown.
[0089] Step 4: Self-assembled polystyrene microspheres.
[0090] In this embodiment, a layer of polystyrene microspheres with a diameter of about 300 nanometers is deposited on the surface of the silicon dioxide film by a self-assembly method.
[0091] The structural diagram of the sample after self-assembly of polystyrene microspheres is shown in Figure 7 shown.
[0092] Step 5: Etching of polystyrene microspheres.
[0093] In this embodiment, a reactive ion etching device is used to etch the polystyrene microspheres to reduce the size of the microspheres and adjust the distribution.
[0094] The etching parameters are: the flow rate of nitrous oxide is 35 sccm, the flow rate of argon is 15 sccm, the pressure is 30 torr, the RF power is 500 watts, and the etching time is 1-3 minutes.
[0095] The structural diagram of the sample after etching of polystyrene microspheres is shown in the figure. Figure 8 shown.
[0096] Step 6: Etching of silicon dioxide film.
[0097] The silicon dioxide film can be dry-etched by reactive ion etching equipment using polystyrene microspheres as a mask.
[0098] The etching parameters are: the flow rate of trifluoromethyl is 35 sccm, the flow rate of argon is 15 sccm, the pressure is 30 torr, the RF power is 500 watts, and the etching time is 2-5 minutes.
[0099] The schematic diagram of the structure of the sample after etching the silicon dioxide film is as follows: Fig. 9 shown.
[0100] Step 7: Remove the polystyrene microspheres and wash.
[0101] In this embodiment, the sample was immersed in acetone for 5 minutes to remove the polystyrene microspheres. The sample surface was thoroughly cleaned with ethanol and deionized water to ensure that residues and impurities were removed. Finally, the sample surface was blown dry with a nitrogen gun to prevent moisture from remaining.
[0102] The structural diagram of the sample after removing the polystyrene microspheres is shown in Fig.10 shown.
[0103] Step 8: Inductively coupled plasma etching.
[0104] In this embodiment, an inductively coupled plasma etcher is used to etch the quantum dot absorption layer and the capping layer.
[0105] The etching parameters are: nitrogen flow rate is 4 sccm, boron trichloride flow rate is 8 sccm, chlorine flow rate is 10 sccm, pressure is 10 mtorr, IPC RF power is 200 watts, table RF power is 50 watts, and etching time is 1-2 minutes.
[0106] The schematic diagram of the structure of the sample after inductively coupled plasma etching is shown in Fig.11 shown.
[0107] Step 9: depositing a silicon dioxide film again.
[0108] In this embodiment, a PECVD device is used to deposit a layer of silicon dioxide film on the surface of the sample. The deposition parameters are the same as those in step 3, and the deposition time is 1-2 minutes.
[0109] Through the above detailed steps, the prepared periodic quantum dot enhanced semiconductor saturable absorption mirror has optimized optical performance and structural stability, and is suitable for application in high-performance optoelectronic devices such as ultrafast pulsed lasers.
[0110] The schematic diagram of the structure of the sample after the silicon dioxide film is deposited again is as follows: Fig.12 shown.
[0111] Fig.13 A side view of the photoluminescence spectrum of a periodic quantum dot enhanced semiconductor saturable absorber provided in an embodiment of the present application. Fig.13 As shown, the horizontal axis is wavelength and the vertical axis is photoluminescence. It can be seen that the periodic quantum dot enhanced semiconductor saturable absorption mirror prepared in the embodiment of the present application has strong luminescence near the 1030 wavelength band.
[0112] Fig.14 This is a reflection spectrum test diagram of a periodic quantum dot enhanced semiconductor saturable absorber provided in an embodiment of the present application. Fig.14 As shown, the abscissa is the wavelength and the ordinate is the reflectivity. It can be seen that the reflectivity test chart shows the reflectivity change of the saturable absorber mirror at different wavelengths, specifically, there is 20% absorption in the 1030nm band.
[0113] Fig.15This is a test diagram of the nonlinear absorption characteristics of a periodic quantum dot enhanced semiconductor saturable absorber provided in an embodiment of the present application. Fig.15 As shown, the horizontal axis is power density and the vertical axis is reflectivity. It can be seen that the curve of the nonlinear absorption characteristic test diagram shows that the reflectivity of the prepared saturable absorption mirror is significantly different under low-intensity and high-intensity incident light conditions, showing obvious nonlinear absorption characteristics.
[0114] The embodiment of the present application further provides a saturable absorption device, comprising: a compound semiconductor saturable absorption mirror, wherein the compound semiconductor saturable absorption mirror is prepared based on the preparation method in the above embodiment.
[0115] It should be noted that the term "including" and its variations used in the embodiments of the present application are open inclusions, that is, "including but not limited to". The term "based on" means "based at least in part on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments". The modifications of "one" and "multiple" mentioned in the embodiments of the present application are illustrative and not restrictive. Those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more".
[0116] The user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in the embodiments of the present application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant laws, regulations and standards of relevant countries and regions, and provide corresponding operation entrances for users to choose to authorize or refuse.
[0117] The various steps described in the method implementation methods provided in the embodiments of the present application can be performed in different orders and / or in parallel. In addition, the method implementation methods may include additional steps and / or omit the steps shown. The scope of protection of the present application is not limited in this respect.
[0118] The term "embodiment" in this specification refers to specific features, structures or characteristics described in conjunction with the embodiment that can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily mean the same embodiment, nor does it mean that it is mutually exclusive with other embodiments and is independent or optional. The various embodiments in this specification are described in a related manner, and the same or similar parts between the various embodiments refer to each other. In particular, for the device, equipment, and system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts refer to the partial description of the method embodiment.
[0119] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of patent protection. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the scope of protection of the present application. Therefore, the scope of protection of the present application shall be subject to the attached claims.
Claims
1. A method for preparing a periodic quantum dot enhanced semiconductor saturable absorber mirror, characterized in that: include: A Bragg reflection layer, a buffer layer, a quantum dot absorption layer, a cap layer and a mask layer are sequentially prepared on a substrate; Laying a layer of polystyrene microspheres on the mask layer based on self-assembly technology; Adjusting the diameter of the polystyrene microspheres to a preset target diameter by etching; Using the polystyrene microspheres adjusted to the target diameter as a mask, etching the mask layer to etch the mask layer into a periodic two-dimensional grating pattern layer; After removing the polystyrene microspheres, the quantum dot absorption layer and the cover layer on the substrate are etched using the two-dimensional grating pattern layer as a mask; The periodic two-dimensional grating pattern layer is removed, a first dielectric film layer is deposited on the etched cover layer, and a second dielectric film layer is deposited on the buffer layer, so as to generate a periodic nano-cylindrical grating layer based on the etched quantum dot absorption layer, the cover layer and the first dielectric film layer, and a dielectric film grating layer is generated based on the second dielectric film layer.
2. The method according to claim 1, characterized in that The method of sequentially preparing a Bragg reflection layer, a buffer layer, a quantum dot absorption layer, a cap layer and a mask layer on a substrate comprises: epitaxially growing the Bragg reflection layer, the buffer layer, the quantum dot absorption layer and the cap layer in sequence on the substrate; The mask layer is prepared on the cap layer by a plasma enhanced chemical vapor deposition method.
3. The method according to claim 1, characterized in that The diameter of the polystyrene microspheres is 200nm-700nm.
4. The method according to claim 1, characterized in that: The preset target diameter includes 30% to 80% of the diameter of the polystyrene microspheres. The method of adjusting the diameter of the polystyrene microspheres to a preset target diameter by etching includes: The polystyrene microspheres are etched by a reactive ion etcher to adjust the diameter of the polystyrene microspheres to the preset target diameter.
5. The method according to claim 1, characterized in that The method of etching the mask layer using the polystyrene microspheres adjusted to the target diameter as a mask to etch the mask layer into a periodic two-dimensional grating pattern layer comprises: The polystyrene microspheres adjusted to the target diameter are used as a mask, and the mask layer is etched by a reactive ion etcher to etch the mask layer into the periodic two-dimensional grating pattern layer.
6. The method according to claim 1, characterized in that After removing the polystyrene microspheres, etching the quantum dot absorption layer and the cover layer on the substrate using the two-dimensional grating cluster layer as a mask includes: The polystyrene microspheres are removed by acetone, and the periodic two-dimensional grating pattern layer is cleaned and dried by a preset cleaning liquid; The quantum dot absorption layer and the cap layer are etched by an inductively coupled plasma etcher using the periodic two-dimensional grating pattern layer as a mask to remove the quantum dot absorption layer and the cap layer outside the area covered by the periodic two-dimensional grating pattern layer on the substrate.
7. The method according to claim 1, characterized in that The removing of the periodic two-dimensional grating pattern layer, depositing a first dielectric film layer on the etched cap layer, and depositing a second dielectric film layer on the buffer layer include: removing the periodic two-dimensional grating pattern layer by a preset cleaning solvent; The first dielectric film layer is deposited on the cap layer, and the second dielectric film layer is deposited on the buffer layer by a plasma enhanced chemical vapor deposition method.
8. A periodic quantum dot enhanced semiconductor saturable absorber mirror, characterized in that: include: A substrate, a Bragg reflection layer, a buffer layer and a grating layer are sequentially arranged from bottom to top, wherein the grating layer comprises a periodic nano-cylindrical grating layer and a dielectric film grating layer, wherein the periodic nano-cylindrical grating layer and the dielectric film grating layer are both arranged on the buffer layer, wherein the periodic nano-cylindrical grating layer comprises a plurality of periodically arranged nano-cylindrical gratings, and the dielectric film grating layer is provided with holes adapted to the plurality of periodically arranged nano-cylindrical gratings; The nano cylindrical grating includes a quantum dot absorption layer, a cover layer and a first dielectric film layer which are arranged in sequence from bottom to top, and the dielectric film grating layer includes a second dielectric film layer.
9. A saturable absorption device, comprising: A compound semiconductor saturable absorber mirror, wherein the compound semiconductor saturable absorber mirror is prepared based on the method according to any one of claims 1 to 7.
10. Application of the method for preparing the periodic quantum dot enhanced semiconductor saturable absorber mirror according to any one of claims 1 to 7 in the field of semiconductor lasers.