A suspended magic-angle nanocavity photonic crystal device and a preparation method thereof
By growing a multi-quantum-well active layer on an InP substrate and combining dry and wet etching techniques, a suspended magic-angle nanocavity photonic crystal device was fabricated, solving the problems of suspended structure collapse and fabrication accuracy consistency, and achieving high device integrity and repeatability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING ACAD OF QUANTUM INFORMATION SCI
- Filing Date
- 2026-05-11
- Publication Date
- 2026-07-28
AI Technical Summary
Existing technologies for fabricating devices combining multi-quantum-well active regions with suspended nanocavity structures suffer from problems such as suspension structure collapse and difficulty in controlling processing precision and consistency. In particular, it is difficult to achieve the integrity and repeatability of the suspended structure during wet etching.
A multi-step fabrication method is employed, including growing a multi-quantum-well active layer on an InP substrate, depositing a mask layer, exposing and etching the magic-angle nanostructure, and combining dry and wet etching to ensure the integrity and uniformity of the suspension structure of the magic-angle nanocavity photonic crystal device.
We have achieved high integrity, high uniformity and high repeatability in the fabrication of suspended magic-angle nanocavity photonic crystal devices, solved the problems of material brittleness, substrate anisotropic corrosion and selective corrosion of heterogeneous materials, and improved the intensity of light-matter interaction and device performance.
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Figure CN122151265B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor quantum device technology, specifically to a suspended magic-angle nanocavity photonic crystal device and its fabrication method. Background Technology
[0002] InGaAsP / InP materials are widely used in core optoelectronic devices such as semiconductor lasers, electro-absorption modulators, and photonic crystals due to their wide tunable bandgap, strong electron confinement capabilities, and good matching with optical communication wavelengths. In recent years, photonic crystal devices based on magic-angle nanocavity structures have become a research hotspot because they can achieve localized enhancement of the optical field at the subwavelength scale and significantly improve the intensity of light-matter interactions. These devices typically combine multi-quantum-well active regions with suspended nanocavity structures to effectively improve characteristics such as radiative recombination efficiency, light-matter coupling strength, and photon density of states in research areas such as nanophotonics, quantum optics, and nonlinear optics.
[0003] This application reveals that existing technologies still face numerous bottlenecks in the fabrication of devices combining multi-quantum-well active regions with suspended nanocavity structures. For example, the collapse of the suspended structure or the partial loss of the pattern severely affects the device yield and structural integrity; the corrosion morphology in all directions during wet etching is difficult to control synchronously, limiting processing accuracy and consistency; and problems such as over-etching or incomplete suspension during wet etching affect the forming quality and repeatability of the suspended structure, thus limiting its performance in physical applications such as enhancing light-matter interactions, quantum light sources, and on-chip integrated optical quantum circuits.
[0004] Therefore, it is necessary to develop a fabrication technology for InGaAsP / InP-based magic-angle nanocavity photonic crystal devices that can comprehensively solve the above problems. Summary of the Invention
[0005] To address the aforementioned deficiencies in this field, this application aims to provide a suspended magic-angle nanocavity photonic crystal device and its fabrication method.
[0006] According to one aspect of this application, a method for fabricating a suspended magic-angle nanocavity photonic crystal device is provided, comprising: Provide InP substrates; A multi-quantum-well active layer is grown on the first surface of an InP substrate; A first mask layer is deposited on the surface of the multi-quantum-well active layer; A second mask layer is spin-coated onto the surface of the first mask layer; Magic-angle nanostructure patterns are exposed on the surface of the second mask layer; Magic-angle nanostructure patterns were etched onto the surface of the first mask layer; Remove the remaining second mask layer; The magic angle nanostructure pattern is transferred from the first mask layer to the multi-quantum well active layer; Remove any remaining first mask layer; A cavity was fabricated on an InP substrate by wet etching of a magic-angle nanostructure with multiple quantum well active layers, thus obtaining a suspended magic-angle nanocavity photonic crystal device.
[0007] According to some embodiments of this application, the multi-quantum-well active layer is composed of In x=0.56 Ga 1-x As y=0.938 P 1-y Quantum well layers and In x=0.734 Ga 1-x As y=0.57 P 1-y The barrier layers are alternately composed.
[0008] According to some embodiments of this application, the multi-quantum-well active layer consists of 5-8 periods of In x=0.56 Ga 1-x As y= 0.938 P 1-y Quantum well layers and In x=0.734 Ga 1-x As y=0.57 P 1-y The barrier layers are alternately composed.
[0009] According to some embodiments of this application, the multi-quantum-well active layer consists of 6 periods of In x=0.56 Ga 1-x As y=0.938 P 1-y Quantum well layers and In x=0.734 Ga 1-x As y=0.57 P 1-y The barrier layers are alternately composed.
[0010] According to some embodiments of this application, the first mask layer is SiO2.
[0011] According to some embodiments of this application, the second mask layer is an electron beam resist.
[0012] According to some embodiments of this application, the InP substrate thickness is 300-600 μm; the thickness of the multi-quantum-well active layer is 150-200 nm; the thickness of each quantum well layer is 8-15 nm; and the thickness of each barrier layer is 15-25 nm.
[0013] According to some embodiments of this application, the InP substrate thickness is 350 μm; the thickness of the multi-quantum-well active layer is 180 nm; the thickness of each quantum well layer is 10 nm; and the thickness of each barrier layer is 20 nm.
[0014] According to some embodiments of this application, the thickness of the first mask layer is 100-200 nm; the thickness of the second mask layer is 200-500 nm.
[0015] According to some embodiments of this application, the wet etching solution ratio is HCl:H2O = (2.5-3.5):1.
[0016] According to some embodiments of this application, the wet etching solution ratio is HCl:H2O = 3:1.
[0017] According to some embodiments of this application, the wet etching time is 3-10 min.
[0018] According to another aspect of this application, a suspended magic-angle nanocavity photonic crystal device prepared by the above-described preparation method is also provided. Attached Figure Description
[0019] Figure 1 The sample structure of this application example embodiment includes a substrate and a multi-quantum well active layer located on the surface of the substrate.
[0020] Figure 2 This is a schematic diagram illustrating the fabrication process of the suspended magic-angle nanocavity photonic crystal device, which is an example embodiment of this application.
[0021] Figure 3 , Figure 4 Scanning electron microscope images of the magic angle nanostructure pattern transfer process in an example embodiment of this application.
[0022] Figure 5 The image shows the color change before and after SiO2 removal during the fabrication process of the suspended magic angle nanocavity photonic crystal device, which is an example embodiment of this application.
[0023] Figure 6 Scanning electron microscope comparison images of devices subjected to wet etching with and without SiO2.
[0024] Figure 7 Comparison of scanning electron microscope images of suspended magic-angle nanocavity photonic crystal devices under different corrosion times.
[0025] Figure 8 Scanning electron microscope image of a suspended magic angle nanocavity sample from an example embodiment of this application. Detailed Implementation
[0026] The technical solution of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0027] It should be particularly noted that similar substitutions and modifications made to this application are obvious to those skilled in the art, and they are all considered to be included in this application. Those skilled in the art can obviously make modifications or appropriate alterations and combinations to the methods and applications described herein without departing from the content, spirit, and scope of this application to implement and apply the technology of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.
[0028] Unless otherwise specified, this application is conducted under standard conditions or conditions recommended by the manufacturer. The raw materials or excipients used, as well as the reagents or instruments used, whose manufacturers are not specified, are all conventional products that can be obtained commercially.
[0029] The following is a detailed description of this application.
[0030] This application finds that the fabrication of devices combining multi-quantum-well active regions and suspended nanocavity structures in the prior art has at least the following problems: Structural reliability issues caused by the inherent properties of the material: The InGaAsP multi-quantum-well material used in the core structure of the device is inherently brittle, especially in the magic-angle nanocavity structure. At the connection of the micropores with feature sizes of 2-20 nm, the material is prone to breakage during processing due to insufficient mechanical properties, which seriously affects the structural integrity and yield of the device.
[0031] Anisotropic etching of substrates leads to processing uniformity issues: When InP is used as the substrate material, its etching rate in the etching solution is affected by different crystal planes, exhibiting typical anisotropic etching. This characteristic makes it difficult to synchronously control the etching morphology and size in different directions during micro- and nano-fabrication, which in turn leads to asymmetric failures or dimensional deviations in the device structure, reducing processing accuracy and consistency.
[0032] The challenge of matching selective etching with the time window for heterogeneous materials: In wet etching processes, it is necessary to simultaneously consider the etching selectivity between the InGaAsP levitation layer and the InP substrate, and precisely control the etching time to achieve complete and stable levitation of the microcavity structure. Existing processes struggle to achieve fully levitation magic-angle nanocavity photonic crystal devices by performing localized non-penetrating etching on the underlying InP substrate while ensuring sufficient protection of the InGaAsP layer's porous structure. This presents a problem of balancing selective etching with the process time window, easily leading to over-etching or incomplete levitation, affecting the forming quality and repeatability of the levitation structure.
[0033] To solve at least one of the above-mentioned technical problems, this application provides the following technical solution: A method for fabricating a suspended magic-angle nanocavity photonic crystal device includes: Provide InP substrates; A multi-quantum-well active layer is grown on the first surface of an InP substrate; A first mask layer is deposited on the surface of the multi-quantum-well active layer; A second mask layer is spin-coated onto the surface of the first mask layer; Magic-angle nanostructure patterns are exposed on the surface of the second mask layer; Magic-angle nanostructure patterns were etched onto the surface of the first mask layer; Remove the remaining second mask layer; The magic angle nanostructure pattern is transferred from the first mask layer to the multi-quantum well active layer; Remove any remaining first mask layer; A cavity was fabricated on an InP substrate by wet etching of a magic-angle nanostructure with multiple quantum well active layers, thus obtaining a suspended magic-angle nanocavity photonic crystal device.
[0034] In some examples, this application further provides the following technical solutions: An InP substrate is provided; optionally, the InP substrate thickness is 300-600 μm; further optionally, the InP substrate thickness is 350 μm; like Figure 1 As shown, a multi-quantum well active layer is grown on the first surface of an InP substrate; optionally, from top to bottom, the layers are: a 180 nm thick multi-quantum well active layer and a 350 μm thick InP substrate layer.
[0035] Optionally, the multi-quantum-well active layer is composed of In x=0.56 Ga 1-x As y=0.938 P 1-y Quantum well layers and In x=0.734 Ga 1-x As y= 0.57P 1-y The barrier layers are alternately composed.
[0036] Optionally, the multi-quantum-well active layer consists of 5-8 cycles of In x=0.56 Ga 1-x As y=0.938 P 1-y Quantum well layers and In x=0.734 Ga 1-x As y=0.57 P 1-y The barrier layers are alternately arranged. The thickness of the multi-quantum-well active layer is 150-200 nm; the thickness of each quantum well layer is 8-15 nm; and the thickness of each barrier layer is 15-25 nm.
[0037] Further, optionally, the multi-quantum-well active layer consists of six 10 nm thick quantum well layers of In... x=0.56 Ga 1- x As y=0.938 P 1-y and a 20 nm thick barrier layer In x=0.734 Ga 1-x As y=0.57 P 1-y Alternating configurations form a strain-compensated quantum well structure. This structure serves as the active region of a laser or an electroabsorption modulator, used to achieve optical gain or electroabsorption effects.
[0038] Soak and wash in acetone, ethanol and deionized water for 5 minutes in sequence, then dry with nitrogen.
[0039] A first mask layer is deposited on the surface of the multi-quantum-well active layer using a plasma-chemical vapor deposition system, such as... Figure 2 As shown in (b); optionally, it is a SiO2 hard mask layer, and further optionally, the thickness of the first mask layer is 100-200 nm.
[0040] A second mask layer is prepared on the surface of the first mask layer; optionally, an electron beam resist is spin-coated and baked at high temperature to form the second mask layer. Figure 2 As shown in (c); optionally, the thickness of the second mask layer is 200-500 nm.
[0041] A high-voltage electron beam lithography machine is used to transfer nanometer-precision magic-angle nanostructure patterns onto a second mask layer, such as... Figure 2 As shown in (d).
[0042] Optionally, a voltage of 125 kV, compared to the commonly used 30 kV voltage, results in less forward scattering, lower proximity effect, and better collimation. The actual pattern size obtained after exposure has an error of approximately 10 nm compared to the design size, which is crucial for achieving a linewidth of 2-20 nm for magic-angle nanostructures. Precise dose testing determined that the exposure dose for InGaAsP magic-angle nanostructures is 340 μC / cm². 2 - 380 μC / cm 2 between.
[0043] Dry etching of the sample was performed using an inductively coupled plasma etching (ICP-C) machine to precisely transfer the pattern of the second mask layer to the first mask layer. The remaining second mask layer was then removed. The SEM image is shown below. Figure 3 As shown. Then, an inductively coupled plasma etching (ICP) machine was used to precisely transfer the pattern of the first mask layer to the multi-quantum-well active layer (InGaAsP layer). The SEM image is shown below. Figure 4 As shown in the diagram. Figure 2 As shown in (e).
[0044] The physical mechanism of the inductively coupled plasma etching (ICP) method for etching InGaAsP multiple quantum wells in this application is as follows: high-density plasma fully dissociates Cl2, BCl3, CH4, and Ar, forming a high concentration of active free radicals (Cl, BCl3, and Ar). x H) and high-energy ions (Ar) + In this process, Cl radicals react with each component of InGaAsP to form chlorides, with InCl3 being the least volatile product. H atoms provided by CH4 convert As and P into highly volatile AsH3 and PH3, forming a dual-channel chemical etching process. BCl3 effectively reduces surface oxides and promotes the desorption of the non-volatile InCl3 at 60℃. Ar + A vertical physical bombardment, applied at a bias voltage of 100 W, assists in removing residual products such as InCl3 while selectively removing bottom hydrocarbon polymers while preserving the sidewall passivation layer. The low gas pressure of 4 mTorr ensures high ion directionality. Ultimately, through the synergistic effect of chemical etching and physical bombardment, highly anisotropic, low-residue, and uniformly layered etching of InGaAsP multi-quantum-well structures can be achieved. Figure 8 (c) and Figure 8 (d) As shown in the stereo SEM image, the excellent sidewall verticality and clear and uniform multi-quantum well layer morphology are visible.
[0045] The residual first mask layer is removed using wet etching to eliminate the impact of SiO2 on subsequent processes. Figure 2 As shown in (f).
[0046] Figure 5The color change before and after SiO2 removal is visible. After wet etching, the blue SiO2 film on the sample surface dissolves, revealing the gray InGaAsP itself.
[0047] This application reveals that although residual SiO2 at a density of tens of nanometers has almost no impact on subsequent optical testing, failure to remove SiO2 will create closed cavities during the next step of etching and hollowing out the InP substrate. This restricts solution diffusion in a specific direction, causing over-etching in one of the X and Y directions within the horizontal plane, while the other direction is under-etched. This directly leads to large-area collapse of the suspended sample, such as... Figure 6 As shown, see the next step for details.
[0048] A stable suspended structure was obtained by hollowing out the InP substrate using wet etching, such as... Figure 2 As shown in (g).
[0049] Optionally, the wet etching solution ratio is HCl:H2O = (2.5-3.5):1; further optionally, the wet etching solution ratio is HCl:H2O = 3:1.
[0050] Optionally, the wet etching time is 3-10 minutes.
[0051] InP has a zincblende structure. In hydrochloric acid (HCl) etching solution, the etching rates of different crystal planes of (001) oriented InP wafers vary significantly. The (111) crystal plane has two polarities: the (111)B plane is terminated by phosphorus atoms, which reacts violently with HCl and rapidly releases a large amount of PH3 gas; the (111)A plane is terminated by indium atoms, which inhibits the release of PH3. Therefore, the (111)B plane (phosphorus-terminated plane) has higher chemical reactivity and a significantly faster etching rate than the (111)A plane.
[0052] This application found that retaining SiO2 creates a closed cavity, restricting diffusion. Due to the difference in corrosion rates between the (111)B and (111)A crystal planes, the corrosion exhibits significant anisotropy. Figure 6 As shown in (a), the etching rate in the vertical direction (i.e., the (111)B crystal plane of InP) is significantly faster than in other directions, forming "rhomboid" grooves; as Figure 6 (b) and Figure 6 As shown in (c), with the etching time extended, the etching rate in other directions outside the (111)B crystal plane is extremely slow. The corner positions have not been fully etched, and the InGaAsP micropores in the central part of 2-20nm have been displaced by lateral etching fracture.
[0053] In the preparation method of this application, SiO2 is removed, and HCl directly etches the exposed InGaAsP and InP. The etching solution has a uniform flow field, and the microfluidic effect caused by the SiO2 mask is eliminated, resulting in uniform diffusion. Figure 6 (d) Figure 6 (e) and Figure 6 As shown in (f), the InP at the center, corners, and the bottom of the entire structure has been etched, and the magic-angle nanocavity structure remains intact and is stably suspended. Simply put, removing SiO2 is equivalent to removing the hard, acid-insoluble roof. While the remaining InGaAsP is also porous, it is acid-soluble, so it can no longer maintain a closed, confined microenvironment like SiO2. The etching solution can then penetrate uniformly, and the corrosion manifests as uniform diffusion. The physical mechanisms are compared in Table 1.
[0054] Table 1
[0055] For the etching of InP materials, this embodiment uses HCl as a diluent. A balance needs to be struck between the etching selectivity ratio of InGaAsP to InP and the etching time window. At an etching time of 8 minutes, the etchant corrodes the sidewalls and upper and lower surfaces of the InGaAsP pores, leading to breakage at the 2-20nm junctions, collapse at the center of the magic-angle nanocavity, or the appearance of localized defects. Figure 7 (a) and Figure 7 As shown in (b), magnification reveals uneven wrinkles in the thin film, such as... Figure 7 As shown in (c); under the premise of ensuring complete etching below the magic-angle nanocavity, shortening the etching time to 5 min can ensure that the HCl dilution solution can etch InP to form a stable suspension structure while maximally protecting the integrity of the InGaAsP layer's pore structure, such as... Figure 7 (d) Figure 7 (e) and Figure 7 As shown in (f).
[0056] The technical solution of this application will be further described below with reference to specific embodiments.
[0057] The two-inch wafer was dissected along the crystal orientation into 6 mm * 6 mm dimensions, soaked in acetone, ethanol and deionized water for 5 minutes, and then dried with a nitrogen gun.
[0058] A SiO2 hard mask of approximately 150 nm thickness was deposited on the substrate surface using a SAMCO PD-220NL plasma chemical vapor deposition system as the first mask layer. The process included: placing the substrate on a SiC tray and transferring it into the growth reaction chamber; setting the temperature of the upper electrode (the inlet electrode for the deposition reaction gas) and the lower electrode (the electrode for placing the sample and the RF electrode) to 150 °C and 350 °C, respectively; after reaching the set temperature, introducing gas at a flow rate of 100 sccm Ar diluted SiH4 (5% SiH4 / 95% Ar) and 460 sccm N2O, with a process pressure of 80 Pa, an RF power of 50 W, and a growth time of 3 min.
[0059] A layer of electron beam resist ZEP520A was spin-coated on the surface of the first mask layer as a second mask layer. The experimental parameters in this embodiment were: 300 rpm for 6 seconds, accelerated to 3000 rpm for 60 seconds, and the adhesive thickness was about 380 nm.
[0060] The sample with the homogenized adhesive was then placed on a hot plate for baking and curing at 180°C for 180 seconds.
[0061] After the samples cooled naturally to room temperature, they were exposed using an electron beam exposure system (Elionix ELS-F125, Japan). Specific parameters were: write field size 100 μm. 100 μm, accelerating voltage 125 kV, beam current 300 pA, step size 2 nm, aperture size 120 μm, exposure dose 360 μC / cm 2 .
[0062] Dry etching was performed using an inductively coupled plasma etching machine (Plasma Pro 100Cobra from Oxford Instruments, UK) to precisely transfer the pattern from the second mask layer to the first mask layer.
[0063] The sample to be etched was adhered to a single-crystal silicon wafer using thermally conductive silicone oil and placed in a pre-vacuum chamber. After the vacuum reached the preset value, it was transferred to the etching chamber. The etching parameters were as follows: the sample stage temperature was set to 10 ℃, the pressure of He gas purging on the back of the sample was 10 Torr, the process pressure was 1 mTorr, the upper electrode (ICP) power was 1000 W, the lower electrode (Bias) power was 35 W, the etching gas was a mixture of trifluoromethane (CHF3) and argon (Ar), the gas component flow rate was CHF3 / Ar = 20 sccm / 10 sccm, and the process time was 2 min 10 s.
[0064] The residual photoresist on the dry-etched sample was removed using the following process parameters: large areas of residual photoresist were dissolved by immersion in N,N-dimethylacetamide (ZEP520A) for 8 minutes. Then, small areas of residual photoresist were removed using a plasma photoresist remover with an O2 flow rate of 50 sccm, an RF power of 200 W, and a processing time of 10 minutes.
[0065] The pattern of the first mask layer was transferred to the InGaAsP layer using an inductively coupled plasma etching (ICP) machine. The etching parameters were as follows: stage temperature set at 60℃, He gas purging pressure on the back side of the sample at 10 Torr, process pressure at 4 mTorr, upper electrode (ICP) power at 1000 W, lower electrode (Bias) power at 100 W, and a quaternary gas mixture of chlorine (Cl2), boron trichloride (BCl3), methane (CH4), and argon (Ar) as the etching gas. The gas flow rates were Cl2 / BCl3 / CH4 / Ar = 10 sccm / 5 sccm / 5 sccm / 20 sccm, and the process time was 2 min.
[0066] The residual SiO2 first mask layer was removed by wet etching, and it could be completely removed by soaking in 40% HF for 1 minute.
[0067] Prepare an HCl:H₂O (3:1) etching solution and wet-etch the InP substrate for 5 minutes. After etching, transfer the sample to deionized water and soak for 10 minutes. Then transfer the sample to isopropanol and soak for 3 minutes. Slowly remove the sample from the isopropanol and place it in the air to allow the isopropanol to evaporate naturally and form a stable suspension structure. Do not use a nitrogen gun to blow on the sample, as this will cause the suspension structure to collapse.
[0068] The scanning electron microscope image of the suspended magic-angle nanocavity sample prepared by the above technical solution in this application is as follows: Figure 8 As shown, it is clear that this process has achieved significant technical advantages in the fabrication of InGaAsP suspended magic-angle nanocavity devices.
[0069] Figure 8 (a) and Figure 8 (b) shows that the micropores with feature sizes of only 2-20 nm in the magic-angle nanocavity structure of the device maintain structural integrity at their connections, without any fracture or collapse caused by the brittleness of the InGaAsP material. This fully verifies the effectiveness of this process in controlling the mechanical stability of nanoscale structures. At the same time, the corrosion morphology of the suspended structure in all directions of the device exhibits high symmetry and consistency, without any non-uniform etching features caused by the anisotropic corrosion of the InP substrate. This indicates that this process precisely controls the corrosion rate differences in different crystal orientations and achieves uniform and controllable suspension layer contours.
[0070] also, Figure 8 (c) and Figure 8 (d) The suspended layer shows smooth and flat sidewalls, a clear multi-quantum-well layered structure, good verticality, and complete removal of the InP substrate below the pattern without any byproduct residue. The InGaAsP suspended layer also shows no corrosion or uneven thinning issues, demonstrating that this process achieves a good balance between corrosion selectivity and process time window. In summary, this technical solution successfully solves the technical challenges of simultaneously addressing the brittleness of InGaAsP material, the anisotropic corrosion of the InP substrate, and the selective corrosion of heterogeneous materials, achieving high integrity, high uniformity, and high repeatability in the fabrication of suspended nanocavity structures.
[0071] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of this application. It should be noted that, for those skilled in the art, several improvements and modifications can be made to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.
Claims
1. A method for fabricating a suspended magic-angle nanocavity photonic crystal device, characterized in that, include: Provide InP substrates; A multi-quantum-well active layer is grown on the first surface of the InP substrate; A first mask layer is deposited on the surface of the multi-quantum-well active layer; A second mask layer is spin-coated onto the surface of the first mask layer; Magic-angle nanostructure patterns are exposed on the surface of the second mask layer; A magic-angle nanostructure pattern is etched onto the surface of the first mask layer; Remove any remaining second mask layer; The magic angle nanostructure pattern is transferred from the first mask layer to the multi-quantum well active layer; Remove any remaining first mask layer; A cavity is prepared by wet etching of the InP substrate using the magic angle nanostructure pattern of the multi-quantum well active layer, thereby obtaining a suspended magic angle nanocavity photonic crystal device. The solution ratio for the wet etching process is HCl:H2O = (2.5-3.5):1; the wet etching time is 3-10 min.
2. The method for fabricating the suspended magic-angle nanocavity photonic crystal device according to claim 1, characterized in that, The multi-quantum-well active layer is composed of In x=0.56 Ga 1-x As y=0.938 P 1-y Quantum well layers and In x=0.734 Ga 1-x As y=0.57 P 1-y The barrier layers are alternately composed.
3. The method for fabricating the suspended magic-angle nanocavity photonic crystal device according to claim 1, characterized in that, The multi-quantum-well active layer consists of 5-8 periods of In x=0.56 Ga 1-x As y=0.938 P 1-y Quantum well layers and In x=0.734 Ga 1-x As y=0.57 P 1-y The barrier layers are alternately composed.
4. The method for fabricating the suspended magic-angle nanocavity photonic crystal device according to any one of claims 1-3, characterized in that, The first mask layer is SiO2.
5. The method for fabricating the suspended magic-angle nanocavity photonic crystal device according to claim 4, characterized in that, The second mask layer is an electron beam resist.
6. The method for fabricating the suspended magic-angle nanocavity photonic crystal device according to claim 2 or 3, characterized in that, The InP substrate has a thickness of 300-600 μm; The thickness of the multi-quantum-well active layer is 150-200 nm; The thickness of each quantum well layer is 8-15 nm; The thickness of each barrier layer is 15-25 nm.
7. The method for fabricating the suspended magic-angle nanocavity photonic crystal device according to claim 6, characterized in that, The thickness of the first mask layer is 100-200 nm; The thickness of the second mask layer is 200-500 nm.
8. A suspended magic-angle nanocavity photonic crystal device prepared by any one of the preparation methods of claims 1-7.