A 750-850 nm band photonic crystal surface emitting laser and a preparation method thereof

Abstract

The application discloses a 750-850nm waveband photonic crystal surface emitting laser and a preparation method, and belongs to the field of semiconductor lasers. The application is divided into surface etching and buried photonic crystal layer structures, uses n-GaAs as a substrate, combines surface etching or buried photonic crystal structures, uses amorphous silicon, titanium oxide, GaP or AlGaAs as main materials of a resonant cavity, utilizes large-area in-plane resonance and high coupling with a quantum well active layer, realizes low-loss resonance and optical gain, and realizes a 750-850nm waveband semiconductor laser with high light beam quality, high power and surface emission.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor lasers, specifically a 750-850nm photonic crystal surface-emitting laser and its fabrication method. Background Technology

[0002] Surface-emitting photonic crystal lasers (PCSELs) are a type of semiconductor laser with great development potential. They utilize the band-edge modes of a two-dimensional photonic crystal to achieve optical feedback and resonance. Their resonant cavity can cover the entire photonic crystal region, enabling large-area coherent oscillation and vertical emission. PCSELs possess outstanding advantages such as good single-mode performance, low divergence angle, small linewidth, high output power, and flexible wavelength design, making them promising for applications in optical communication, lidar, sensing and lighting, and materials processing.

[0003] Laser sources in the 750-850nm band play a crucial and irreplaceable role in short-range optical communication scenarios such as data centers / metropolitan area networks, Raman spectroscopy excitation, solid-state laser excitation, and atomic clock excitation. However, due to relatively large material absorption losses in this band, it is difficult to achieve lasing in large-area in-plane resonant microcavities such as PCSELs. Therefore, the main lasers currently used are vertical-cavity surface-emitting lasers (VCSELs), distributed Bragg feedback (DFB) lasers, and Fabry-Perot (FP) lasers. However, due to differences in lasing principles and cavity structures, these lasers generally suffer from insurmountable defects in beam quality, linewidth, divergence angle, single-mode characteristics, optical power, and emission patterns. If optical losses can be reduced in this band through unique design and technical means to achieve lasing based on the PCSEL principle, it will bring revolutionary changes to the aforementioned applications.

[0004] This invention focuses on the unique technical value of the focused band, combining the inherent advantages of PCSEL in power, beam quality, linewidth, divergence angle, mode characteristics, and surface emission, and building upon the maturity of epitaxial growth and processing of gallium arsenide material systems. It employs a unique structure to realize a novel 750-850nm band photonic crystal surface-emitting laser. Summary of the Invention

[0005] This invention provides an 800nm ​​band photonic crystal surface-emitting laser and its fabrication method, which solves the problem that it is difficult to achieve large-area in-plane resonant microcavity lasing in the 750-850nm band due to the large absorption loss of materials. It fully utilizes the inherent advantages of PCSELs and provides a high-performance 750-850nm band laser source.

[0006] Technical solution: This invention discloses a 750-850nm wavelength photonic crystal surface-emitting laser, the laser comprising, from top to bottom:

[0007] n-GaAs substrate layer;

[0008] The n-AlGaAs cladding layer is located on the n-GaAs substrate layer;

[0009] The first confinement layer of n-AlGaAs is located on the n-AlGaAs cladding layer;

[0010] The quantum well active layer, located above the first confinement layer of n-AlGaAs, is composed of multiple pairs of InAlGaAs and AlGaAs grown together.

[0011] The second p-AlGaAs confinement layer is located above the active layer of the quantum well;

[0012] The p+-GaAs contact layer is located above the p-AlGaAs second confinement layer;

[0013] A photonic crystal layer is located above the p+-GaAs contact layer or embedded inside the p-AlGaAs second confinement layer;

[0014] The p-electrode is located on the surface of the p+-GaAs layer;

[0015] The n-electrode is located on the bottom surface of the n-GaAs substrate.

[0016] The silicon oxide insulating confinement layer is located in the non-photonic crystal region and non-electrode region on the surface of the p+-GaAs contact layer and the bottom surface of the n-GaAs substrate layer.

[0017] (i) Preferably, the laser is a 750-850nm band photonic crystal surface-emitting laser with an etched amorphous silicon or titanium oxide photonic crystal layer structure, wherein the photonic crystal layer is an amorphous silicon or titanium oxide photonic crystal layer with periodic holes etched on the p+-GaAs contact layer.

[0018] Furthermore, the photonic crystal layer has a thickness of 200-500 nm, a lattice type of triangular lattice, square lattice or honeycomb lattice, a period of 200-250 nm, and a hole radius of 30-80 nm.

[0019] Furthermore, for the 750-850nm band photonic crystal surface-emitting laser of the etched amorphous silicon or titanium dioxide photonic crystal layer structure, the parameters of each of the remaining layers are as follows:

[0020] The n-GaAs substrate has a refractive index of 3.6-3.75;

[0021] The n-AlGaAs cladding has a thickness of 500-1200 nm, an Al content of 40%-60% (the percentage of Al in the total molar ratio of Al and Ga), and a refractive index of 3.25-3.35.

[0022] The n-AlGaAs first confinement layer has a thickness of 100-400 nm, an Al content of 20%-40% (the percentage of Al in the total molar ratio of Al and Ga), and a refractive index of 3.4-3.5.

[0023] The active layer of the quantum well consists of 3-5 pairs of alternating InAlGaAs and AlGaAs layers, wherein the refractive index of the InAlGaAs layer is 3.5-3.65 and the refractive index of the AlGaAs layer is 3.4-3.5; the InAlGaAs layer contains 5%-12% In (the percentage of In to the total molar content of In, Al, and Ga) and 10%-15% Al (the percentage of Al to the total molar content of In, Al, and Ga); the AlGaAs layer contains 20%-40% Al (the percentage of Al to the total molar content of Al and Ga).

[0024] The p-AlGaAs second confinement layer has a thickness of 100-300 nm, an Al content of 20%-40%, and a refractive index of 3.4-3.5.

[0025] The p+-GaAs contact layer has a thickness of 2-10 nm and a refractive index of 3.6-3.75.

[0026] The p electrode is an ohmic contact metal electrode or a composite electrode of a metal electrode and ITO.

[0027] The n-electrode is an ohmic contact metal electrode.

[0028] Furthermore, the fabrication method of the 750-850nm band photonic crystal surface-emitting laser with the etched amorphous silicon or titanium oxide photonic crystal layer structure is as follows:

[0029] Step 1: Epitaxially grow GaAs-based group III-V materials on an n-GaAs substrate, specifically, from bottom to top, an n-AlGaAs cladding layer, an n-AlGaAs first confinement layer, a quantum well active layer, a p-AlGaAs second confinement layer, and a p+-GaAs contact layer are formed sequentially.

[0030] Step 2: Deposit an amorphous silicon layer or titanium oxide layer of a certain thickness on the surface of the p+-GaAs contact layer;

[0031] Step 3: Prepare a photonic crystal mask layer by electron beam lithography (EBL) or nanoimprinting, and form periodic holes by dry etching of the amorphous silicon layer or titanium oxide layer. Remove the mask layer to obtain the photonic crystal layer.

[0032] Step 4: Expose the area on the surface of the p+-GaAs contact layer used for fabricating the p electrode by photolithography and etching;

[0033] Step 5: Deposit p-electrode material in the area where the p-electrode is to be fabricated, form the p-electrode structure by lift-off peeling, and anneal;

[0034] Step 6: Perform photolithography on the bottom surface of the n-GaAs substrate to deposit the n-electrode material, form the n-electrode structure by lift-off, and anneal;

[0035] Step 7: Deposit a silicon oxide insulating confinement layer in the non-photonic crystal region and non-electrode region located on the surface of the p+-GaAs contact layer and the bottom surface of the n-GaAs substrate layer using a photolithography-etching process.

[0036] (ii) Preferably, the laser is a 750-850nm band photonic crystal surface-emitting laser with an etched III-V group material photonic crystal layer structure, wherein the photonic crystal layer is embedded inside the p-AlGaAs second confinement layer, and the p+-GaAs contact layer and the p-AlGaAs second confinement layer are etched with periodic hole structures to form the photonic crystal layer.

[0037] Furthermore, the thickness of the photonic crystal layer is 100-400 nm, the lattice type of the photonic crystal layer is a triangular lattice, a square lattice or a honeycomb lattice, the period is 200-250 nm, and the aperture radius is 30-80 nm.

[0038] Furthermore, for the 750-850nm band photonic crystal surface-emitting laser of the etched III-V group material photonic crystal layer structure, the parameters of each of the remaining layers are as follows:

[0039] The n-GaAs substrate has a refractive index of 3.6-3.75;

[0040] The n-AlGaAs cladding has a thickness of 500-1200 nm, an Al content of 40%-60% (the percentage of Al in the total molar ratio of Al and Ga), and a refractive index of 3.25-3.35.

[0041] The n-AlGaAs first confinement layer has a thickness of 100-400 nm, an Al content of 20%-40% (the percentage of Al in the total molar ratio of Al and Ga), and a refractive index of 3.4-3.5.

[0042] The active layer of the quantum well consists of 3-5 pairs of alternating InAlGaAs and AlGaAs layers, wherein the refractive index of the InAlGaAs layer is 3.5-3.65 and the refractive index of the AlGaAs layer is 3.4-3.5; the InAlGaAs layer contains 5%-12% In (the percentage of In to the total molar content of In, Al, and Ga) and 10%-15% Al (the percentage of Al to the total molar content of In, Al, and Ga); the AlGaAs layer contains 20%-40% Al (the percentage of Al to the total molar content of Al and Ga).

[0043] The p-AlGaAs second confinement layer has a thickness of 100-300 nm, an Al content of 20%-40%, and a refractive index of 3.4-3.5.

[0044] The p+-GaAs contact layer has a thickness of 2-10 nm and a refractive index of 3.6-3.75.

[0045] The p electrode is an ohmic contact metal electrode or a composite electrode of a metal electrode and ITO.

[0046] The n-electrode is an ohmic contact metal electrode.

[0047] Furthermore, the fabrication method of the 750-850nm band photonic crystal surface-emitting laser with the etched III-V group material photonic crystal layer structure is as follows:

[0048] Step 1: Epitaxially grow GaAs-based group III-V materials on an n-GaAs substrate, specifically, from bottom to top, an n-AlGaAs cladding layer, an n-AlGaAs first confinement layer, a quantum well active layer, a p-AlGaAs second confinement layer, and a p+-GaAs contact layer are formed sequentially.

[0049] Step 2: Prepare a photonic crystal mask layer by electron beam lithography (EBL) or nanoimprinting, dry etch the p+-GaAs contact layer and p-AlGaAs second confinement layer to form periodic holes, and remove the mask layer to obtain the photonic crystal layer.

[0050] Step 3: Expose the area on the surface of the p+-GaAs contact layer used for fabricating the p electrode by photolithography and etching;

[0051] Step 4: Deposit p-electrode material in the area where the p-electrode is to be fabricated, form the p-electrode structure by lift-off peeling, and anneal;

[0052] Step 5: Perform photolithography on the bottom surface of the n-GaAs substrate to deposit the n-electrode material, form the n-electrode structure by lift-off, and anneal;

[0053] Step 6: Deposit a silicon oxide insulating confinement layer in the non-photonic crystal region and non-electrode region located on the surface of the p+-GaAs contact layer and the bottom surface of the n-GaAs substrate layer using a photolithography-etching process.

[0054] (iii) Preferably, the laser is a 750-850nm band photonic crystal surface-emitting laser with a buried GaP photonic crystal structure; its photonic crystal layer is embedded inside the p-AlGaAs second confinement layer, the p-AlGaAs second confinement layer includes an upper p-AlGaAs layer and a lower p-AlGaAs layer; a periodic hole structure composed of GaP or air is provided in the lower p-AlGaAs layer to form the photonic crystal layer.

[0055] Furthermore, the thickness of the photonic crystal layer is 100-400 nm; the lattice type of the photonic crystal layer is a triangular lattice, a square lattice, or a honeycomb lattice, with a period of 200-250 nm and a hole radius of 30-80 nm.

[0056] Furthermore, the thickness of the lower p-AlGaAs layer is 300-800 nm, the Al content is 20%-40%, and its refractive index is 3.4-3.5; the thickness of the upper p-AlGaAs layer is 300-1200 nm, the Al content is 40%-60%, and its refractive index is 3.25-3.35.

[0057] Furthermore, for the 750-850nm wavelength band surface-emitting laser of the buried GaP photonic crystal structure, the parameters of the remaining layers are as follows:

[0058] The n-GaAs substrate has a refractive index of 3.6-3.75;

[0059] The n-AlGaAs cladding has a thickness of 500-1200 nm, an Al content of 40%-60% (the percentage of Al in the total molar ratio of Al and Ga), and a refractive index of 3.25-3.35.

[0060] The n-AlGaAs first confinement layer has a thickness of 100-400 nm, an Al content of 20%-40% (the percentage of Al in the total molar ratio of Al and Ga), and a refractive index of 3.4-3.5.

[0061] The active layer of the quantum well consists of 3-5 pairs of alternating InAlGaAs and AlGaAs layers, wherein the refractive index of the InAlGaAs layer is 3.5-3.65 and the refractive index of the AlGaAs layer is 3.4-3.5; the InAlGaAs layer contains 5%-12% In (the percentage of In to the total molar content of In, Al, and Ga) and 10%-15% Al (the percentage of Al to the total molar content of In, Al, and Ga); the AlGaAs layer contains 20%-40% Al (the percentage of Al to the total molar content of Al and Ga).

[0062] The p+-GaAs contact layer has a thickness of 2-10 nm and a refractive index of 3.6-3.75.

[0063] The p electrode is an ohmic contact metal electrode or a composite electrode of a metal electrode and ITO.

[0064] The n-electrode is an ohmic contact metal electrode.

[0065] Furthermore, the fabrication method of the 750-850nm band surface-emitting laser of the buried GaP photonic crystal structure is as follows:

[0066] Step 1: Epitaxially grow GaAs-based group III-V materials on an n-GaAs substrate, specifically, from bottom to top, an n-AlGaAs cladding layer, an n-AlGaAs first confinement layer, a quantum well active layer, and a lower p-AlGaAs layer of a certain thickness;

[0067] Step 2: Deposit a GaP layer on the partially thick p-AlGaAs layer;

[0068] Step 3: Prepare a photonic crystal mask layer by electron beam lithography (EBL) or nanoimprint lithography, dry etch GaP to form a periodic structure, and remove the mask layer;

[0069] Step 4: Continue epitaxial growth of the lower p-AlGaAs layer to completely bury the GaP structure; then epitaxially grow the upper p-AlGaAs layer and the p+-GaAs contact layer.

[0070] Step 5: Expose the area on the surface of the p+-GaAs contact layer used for fabricating the p electrode by photolithography;

[0071] Step 6: Deposit p-electrode material in the area where the p-electrode is to be fabricated, form the p-electrode structure by lift-off peeling, and anneal;

[0072] Step 7: Perform photolithography on the bottom surface of the n-GaAs substrate to deposit the n-electrode material, form the n-electrode structure by lift-off, and anneal;

[0073] Step 8: Deposit a silicon oxide insulating confinement layer in the non-photonic crystal region and non-electrode region located on the surface of the p+-GaAs contact layer and the bottom surface of the n-GaAs substrate layer using a photolithography-etching process.

[0074] Beneficial effects:

[0075] 1. This invention uses a two-dimensional photonic crystal resonator to achieve intra-field resonance and gain in the active region of the optical field, and at the same time uses second-order diffraction to achieve surface emission. This principle enables the optical lasing in the 800nm ​​band to have excellent single-mode characteristics, a narrow linewidth of less than 1nm, a divergence angle of less than 3 degrees, and high emission power (the larger the resonant area, the higher the emission power).

[0076] 2. This invention utilizes amorphous silicon layers, titanium dioxide, GaP, and AlGaAs as the main materials for the photonic crystal and resonant cavity, effectively overcoming the significant absorption problem of GaAs in this wavelength band. Simultaneously, silicon and titanium dioxide possess relatively high refractive indices, enabling high optical field coupling strength in the photonic crystal region and facilitating the realization of high-quality photonic crystal hole structures, thus generally benefiting low-loss, large-area resonance. Buried GaP facilitates the realization of high confinement factors and more stable structures and resonances. The use of a relatively high Al content n-AlGaAs cladding, a transitional relatively low Al content n-AlGaN layer, and the aforementioned unique layer structure design ensures both the quality of the epitaxial material and the high optical field coupling strength between the active layer and the photonic crystal layer. All of these lay the foundation for high-performance photolasing. Attached Figure Description

[0077] Figure 1 This is a side view of the structure of the photonic crystal surface-emitting laser of Example 1;

[0078] Figure 2 The figure shows the simulation test results of the photonic crystal surface-emitting laser in Example 1;

[0079] Figure 3 This is a flowchart illustrating the fabrication process of the photonic crystal surface-emitting laser in Example 1.

[0080] Figure 4 This is a side view of the structure of the photonic crystal surface-emitting laser in Example 2;

[0081] Figure 5 The figure shows the simulation test results of the photonic crystal surface-emitting laser in Example 2;

[0082] Figure 6 This is a flowchart illustrating the fabrication process of the photonic crystal surface-emitting laser in Example 2.

[0083] Figure 7 This is a side view of the structure of the photonic crystal surface-emitting laser in Example 3;

[0084] Figure 8 This is a flowchart illustrating the fabrication process of the photonic crystal surface-emitting laser in Example 3. Detailed Implementation

[0085] The technical solution of the present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the embodiments described.

[0086] Example 1

[0087] Example 1 provides a 750-850nm wavelength photonic crystal surface-emitting laser with an etched amorphous silicon photonic crystal layer structure, as shown in the side view below. Figure 1 As shown, the laser consists of the following components from bottom to top:

[0088] (1) The n-GaAs substrate layer is the basic support layer of the entire laser structure.

[0089] (2) n-AlGaAs cladding, located on the substrate layer, specifically n-Al 0.5 Ga 0.5 The as cladding has a thickness of 800 nm and a refractive index of 3.3.

[0090] The cladding layer serves to longitudinally confine the light field and reduce leakage loss of the light field towards the substrate by using the difference in refractive index with the adjacent layers.

[0091] (3) The first confinement layer of n-AlGaAs, specifically n-Al 0.3 Ga 0.7 As layer, located in n-Al 0.5 Ga 0.5 The As cladding is 200 nm thick and has a refractive index of 3.45.

[0092] The first confinement layer of n-AlGaAs acts as a confinement layer, with n-Al 0.5 Ga 0.5 As cladding and subsequent p-Al 0.3 Ga 0.7 With the addition of As layers and other components, the longitudinal confinement of the light field is further optimized.

[0093] (4) The active layer of the quantum well is located in n-Al 0.3 Ga 0.7 Above the As layer are three pairs of alternating In layers. 0.08 Al 0.13 Ga 0.79 As layer and Al 0.3 Ga 0.7 As layer; In 0.08 Al 0.13 Ga 0.79The As layer thickness is 6nm; Al 0.3 Ga 0.7 The As layer thickness is 8 nm; In 0.08 Al 0.13 Ga 0.79 The refractive index of the As layer is 3.58, and the Al layer... 0.3 Ga 0.7 The refractive index of the As layer is 3.45.

[0094] The active layer of a quantum well is the core region that generates laser emission, releasing energy through the recombination of electrons and holes.

[0095] (5) p-AlGaAs second confinement layer, specifically p-Al 0.3 Ga 0.7 The As layer, located above the active layer, has a thickness of 200 nm; it participates in the vertical confinement of the light field and provides a suitable growth basis for the p⁺-GaAs layer above.

[0096] (6) p+-GaAs contact layer, located in p-Al 0.3 Ga 0.7 Above the As layer, there is a thickness of 5nm and a refractive index of 3.7.

[0097] The p⁺-GaAs layer is a p-type contact layer. Its core function is to optimize the ohmic contact between the p electrode and the semiconductor through high-concentration doping, ensuring efficient current injection into the active region while also taking into account the impact on the optical field distribution.

[0098] (7) Photonic crystal layer, specifically an amorphous silicon layer with periodic holes etched on it. It is located above the p+-GaAs contact layer, with a thickness of 400 nm, a square lattice type, a period of 230 nm, and a hole radius of 40 nm.

[0099] The photonic crystal layer utilizes the photonic bandgap effect and periodic dielectric structure to modulate the propagation of light, thereby achieving high-performance optical field confinement, mode selection, and vertical laser output.

[0100] (8) Electrodes:

[0101] Two p electrodes are located on the surface of the p+-GaAs layer, which are two Ti / Pt / Au structures that are spaced apart and stacked sequentially.

[0102] An n-electrode is located on the bottom surface of the n-GaAs substrate, and consists of a Ti / Al / Ni / Au structure stacked sequentially.

[0103] (9) A silicon oxide insulating confinement layer is located on the p+-GaAs surface and the bottom surface of the n-GaAs substrate, respectively, and is located in the non-photonic crystal region and the non-electrode region. The thickness of the silicon oxide insulating confinement layer is 1000 nm.

[0104] Figure 2 The image shows the simulation test results of the photonic crystal surface-emitting laser in Example 1; from Figure 2 The field distribution test results show that the resonant mode field at a wavelength of 806 nm is well confined between the photonic crystal and the cladding layer, forming a good fundamental mode resonance. The confinement factors of both the photonic crystal layer and the active layer exceed 6%, and the quality factor exceeds 6000.

[0105] like Figure 3 As shown, the fabrication process of the laser in Example 1 is as follows:

[0106] Step 1: On an n-GaAs substrate, GaAs-based group III-V materials are epitaxially grown by MOCVD. Specifically, from bottom to top, an n-AlGaAs cladding layer, an n-AlGaAs first confinement layer, a quantum well active layer, a p-AlGaAs second confinement layer, and a p+-GaAs contact layer are formed sequentially.

[0107] Step 2: Deposit a 400 nm thick amorphous silicon layer on the surface of the p+-GaAs contact layer as an amorphous silicon layer;

[0108] Step 3: Spin-coat PMMA onto the surface of the epitaxial wafer using electron beam lithography (EBL) to prepare a mask layer for the photonic crystal. Use Bosch's dry etching process to etch the amorphous silicon layer to form periodic holes. Remove the mask layer to obtain the photonic crystal layer.

[0109] Step 4: Spin coating, UV lithography, overlay with photonic crystal structure, silicon etching again to expose the area on the p+-GaAs contact layer surface used to fabricate the p electrode, so as to fabricate the p electrode on it.

[0110] Step 5: Deposit p-electrode material, lift-off to form p-electrode structure, anneal;

[0111] Step 6: Photolithography is performed on the bottom surface of the n-GaAs substrate layer, overlaying it with the front photonic crystal structure, depositing the n-electrode material, lift-off to form the n-electrode structure, and annealing.

[0112] Step 7: Deposit a silicon oxide layer of a certain thickness using PECVD. Then, deposit a silicon oxide insulating confinement layer in the non-photonic crystal region and non-electrode region located on the surface of the p+-GaAs contact layer and the bottom surface of the n-GaAs substrate layer using ultraviolet lithography-etching process.

[0113] Example 2

[0114] Example 2 provides a 750-850nm wavelength photonic crystal surface-emitting laser with an etched III-V group material photonic crystal layer structure. Its side view is shown below. Figure 4As shown, the laser consists of the following components from bottom to top:

[0115] (1) Substrate layer, wherein the substrate layer is an n-GaAs substrate layer.

[0116] (2) n-AlGaAs cladding, located on the substrate layer, specifically n-Al 0.45 Ga 0.55 The As cladding has a thickness of 1200 nm and a refractive index of 3.35.

[0117] (3) The first confinement layer of n-AlGaAs, specifically n-Al 0.35 Ga 0.65 As layer, located in n-Al 0.45 The material has a Ga0.55As cladding layer with a thickness of 300 nm and a refractive index of 3.42.

[0118] (4) The active layer of the quantum well is located in n-Al 0.35 Ga 0.65 Above the As layer are 5 pairs of alternating In layers. 0.1 Al 0.13 Ga 0.77 As layer and Al 0.35 Ga 0.65 As layer; In 0.1 Al 0.13 Ga 0.77 The thickness of the As layer is 6nm, and the Al layer... 0.35 Ga 0.65 The thickness of the As layer is 8nm.

[0119] In 0.1 Al 0.13 Ga 0.77 The refractive index of the As layer is 3.6, and the Al layer... 0.35 Ga 0.65 The refractive index of the As layer is 3.42.

[0120] (5) p-AlGaAs second confinement layer, specifically p-Al 0.35 Ga 0.65 An As layer, 400 nm thick, is located above the quantum well layer; p-Al 0.35 Ga 0.65 The refractive index of the As layer is 3.42.

[0121] (6) p+-GaAs contact layer, located in p-Al 0.35 Ga 0.65 Above the As layer, the thickness is 10nm.

[0122] (7) Photonic crystal layer, for etching p+-GaAs (p+-GaAs contact layer) and p-Al to a certain depth. 0.35Ga 0.65 An As layer (p-AlGaAs second confinement layer) is formed with a thickness of 300 nm, a square lattice type, a period of 225 nm, and a hole radius of 50 nm.

[0123] (8) Electrodes:

[0124] Two p electrodes are located on the surface of the p+-GaAs contact layer, which are two Ti / Pt / Au structures that are spaced apart and stacked sequentially.

[0125] An n-electrode is located on the bottom surface of the n-GaAs substrate, and consists of a Ti / Al / Ni / Au structure stacked sequentially.

[0126] (9) A silicon oxide insulating confinement layer is located on the p+-GaAs surface and the bottom surface of the n-GaAs substrate, respectively, and is located in the non-photonic crystal region and the non-electrode region. The thickness of the silicon oxide insulating confinement layer is 1500 nm.

[0127] Figure 5 The image shows the simulation test results of the photonic crystal surface-emitting laser in Example 2; from Figure 5 From the field distribution test results, Figure 5 The field distribution test results show that the resonant mode field at a wavelength of 800nm ​​is well confined between the photonic crystal and the cladding layer, forming a good fundamental mode resonance. The confinement factor of the photonic crystal layer is around 3%, the confinement factor of the active layer exceeds 6%, and the quality factor exceeds 13000.

[0128] like Figure 6 As shown, the fabrication process of the photonic crystal surface-emitting laser in Example 2 is as follows:

[0129] Step 1: GaAs-based group III-V materials are epitaxially grown on an n-GaAs substrate using MOCVD. Specifically, from bottom to top, an n-AlGaAs cladding layer, an n-AlGaAs first confinement layer, a quantum well active layer, a p-AlGaAs second confinement layer, and a p+-GaAs contact layer are formed sequentially.

[0130] Step 2: Prepare a mask layer for the photonic crystal using nanoimprint lithography. Use RIE (Rich Imaging Electrode) to etch the p+-GaAs contact layer and p-AlGaAs second confinement layer to form periodic holes. Remove the mask layer to obtain the photonic crystal layer.

[0131] Step 3: Spin coating, UV lithography, overlay with photonic crystal structure, development, expose the area on the p+-GaAs contact layer surface used to fabricate the p electrode, so as to fabricate the p electrode on it;

[0132] Step 4: Deposit p-electrode material in the area where the p-electrode is to be fabricated, form the p-electrode structure by lift-off peeling, and anneal;

[0133] Step 5: Perform photolithography on the bottom surface of the n-GaAs substrate, overlay it with the front photonic crystal structure, deposit the n-electrode material, lift-off to form the n-electrode structure, and anneal;

[0134] Step 6: Deposit a silicon oxide layer of a certain thickness using the PECVD method. Specifically, a silicon oxide insulating confinement layer is deposited in the non-photonic crystal region and non-electrode region located on the surface of the p+-GaAs contact layer and the bottom surface of the n-GaAs substrate layer using ultraviolet lithography-etching process.

[0135] Example 3

[0136] Example 3 provides a 750-850nm wavelength photonic crystal surface-emitting laser with a buried GaP photonic crystal structure, the side view of which is shown below. Figure 7 As shown, the laser consists of the following components from bottom to top:

[0137] (1) n-GaAs substrate;

[0138] (2) n-AlGaAs cladding, specifically n-Al 0.5 Ga 0.5 An As cladding layer, 600 nm thick, is located on the n-GaAs substrate, and an n-Al layer... 0.5 Ga 0.5 The refractive index of the As cladding is 3.3.

[0139] (3) The first confinement layer of n-AlGaAs, specifically n-Al 0.3 Ga 0.7 As layer, located in n-Al 0.5 Ga 0.5 Above the As cladding, the thickness is 200 nm; n-Al 0.3 Ga 0.7 The refractive index of the As layer is 3.45.

[0140] (4) The active layer of the quantum well is located in n-Al 0.3 Ga 0.7 Above the As layer are three pairs of alternating In layers. 0.08 Al 0.13 Ga 0.79 As layer and Al 0.3 Ga 0.7 As layer; In 0.08 Al 0.13 Ga 0.79 The thickness of the As layer is 6nm, and the Al layer... 0.3 Ga 0.7The thickness of the As layer is 8nm;

[0141] In 0.08 Al 0.13 Ga 0.79 The refractive index of the As layer is 3.58, and the Al layer... 0.3 Ga 0.7 The refractive index of the As layer is 3.45.

[0142] (5) The second p-AlGaAs confinement layer includes an upper p-AlGaAs layer and a lower p-AlGaAs layer;

[0143] The lower p-AlGaAs layer, specifically p-Al 0.3 Ga 0.7 An As layer, 500 nm thick, is located above the quantum well layer; p-Al 0.3 Ga 0.7 The refractive index of the As layer is 3.45.

[0144] The upper p-AlGaAs layer, specifically p-Al 0.5 Ga 0.5 As layer, located in p-Al 0.3 Ga 0.7 Above the As layer, a 500nm thick p-Al 0.5 Ga 0.5 The refractive index of the As layer is 3.3.

[0145] (6) Photonic crystal layer, specifically a photonic crystal layer composed of GaP periodic structures, located in the lower p-Al 0.3 Ga 0.7 The As layer has a thickness of 300 nm, a triangular lattice type, a period of 240 nm, and a hole radius of 30 nm.

[0146] (7) p+-GaAs contact layer, located in p-Al 0.5 Ga 0.5 Above the As layer (upper p-AlGaAs layer), the thickness is 10nm.

[0147] (8) Electrodes:

[0148] Three p electrodes, including two metal electrodes and one ITO electrode, are located on the surface of the p+-GaAs layer; two Ti / Pt / Au (metal electrodes) are located on both sides of the photonic crystal, and the ITO electrode is located directly above the photonic crystal region.

[0149] An n-electrode is located on the bottom surface of the n-GaAs substrate, which is a stacked Ti / Al / Ni / Au structure.

[0150] (9) A silicon oxide insulating confinement layer is located on the surface of the p+-GaAs contact layer and the bottom surface of the n-GaAs substrate layer, respectively, and is located in the non-photonic crystal region and the non-electrode region.

[0151] like Figure 8 As shown, the preparation process is as follows:

[0152] Step 1: Epitaxially grow GaAs-based group III-V materials on an n-GaAs substrate, forming an n-AlGaAs cladding layer, an n-AlGaAs first confinement layer, a quantum well active layer, and a lower p-AlGaAs layer of a certain thickness from bottom to top.

[0153] Step 2: Epitaxially grow a 300nm thick GaP layer;

[0154] Step 3: Prepare a photonic crystal mask layer PMMA by electron beam lithography (EBL), etch GaP using RIE dry etching to form a periodic structure, and remove the mask layer;

[0155] Step 4: Continue epitaxial growth of the lower p-AlGaAs layer to completely bury the GaP structure; epitaxially grow the upper p-AlGaAs layer and the p+-GaAs contact layer.

[0156] Step 5: By photolithography, the surface of the p+-GaAs contact layer used to fabricate the p electrode and ITO electrode area is exposed, so that the p electrode can be fabricated on it.

[0157] Step 6: Deposit electrode material, lift-off to form p-electrode structure, anneal;

[0158] Step 7: Backside photolithography overlay, deposition of n-electrode material, lift-off to form n-electrode structure, annealing;

[0159] Step 8: Deposit a silicon oxide insulating confinement layer using PECVD. Specifically, through photolithography-etching processes, deposit a silicon oxide insulating confinement layer in the non-photonic crystal region and non-electrode region located on the surface of the p+-GaAs contact layer and the bottom surface of the n-GaAs substrate layer.

[0160] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention.

Claims

1. A 750-850nm wavelength photonic crystal surface-emitting laser, characterized in that, The laser, from top to bottom, comprises: n-GaAs substrate layer; The n-AlGaAs cladding layer is located on the n-GaAs substrate layer; The first confinement layer of n-AlGaAs is located on the n-AlGaAs cladding layer; The quantum well active layer, located above the first confinement layer of n-AlGaAs, is composed of multiple pairs of InAlGaAs and AlGaAs grown together. The second p-AlGaAs confinement layer is located above the active layer of the quantum well; The p+-GaAs contact layer is located above the p-AlGaAs second confinement layer; A photonic crystal layer is located above the p+-GaAs contact layer or embedded inside the p-AlGaAs second confinement layer; The p-electrode is located on the surface of the p+-GaAs layer; The n-electrode is located on the bottom surface of the n-GaAs substrate. The silicon oxide insulating confinement layer is located in the non-photonic crystal region and non-electrode region on the surface of the p+-GaAs contact layer and the bottom surface of the n-GaAs substrate layer.

2. The laser according to claim 1, characterized in that, The photonic crystal layer is an amorphous silicon or titanium oxide photonic crystal layer with periodic holes etched on top of the p+-GaAs contact layer. The photonic crystal layer has a thickness of 200-500 nm, a lattice type of triangular lattice, square lattice or honeycomb lattice, a period of 200-250 nm, and a hole radius of 30-80 nm. The p-AlGaAs second confinement layer has a thickness of 100-300 nm, an Al content of 20%-40%, and a refractive index of 3.4-3.

5.

3. The laser according to claim 1, characterized in that, The photonic crystal layer is embedded inside the p-AlGaAs second confinement layer, and the p+-GaAs contact layer and the p-AlGaAs second confinement layer are etched with periodic hole structures to form the photonic crystal layer; The thickness of the photonic crystal layer is 100-400nm, the lattice type of the photonic crystal layer is a triangular lattice, a square lattice or a honeycomb lattice, the period is 200-250nm, and the hole radius is 30-80nm. The p-AlGaAs second confinement layer has a thickness of 100-300 nm, an Al content of 20%-40%, and a refractive index of 3.4-3.

5.

4. The laser according to claim 1, characterized in that, The photonic crystal layer is embedded inside the second p-AlGaAs confinement layer, which includes an upper p-AlGaAs layer and a lower p-AlGaAs layer. A periodic hole structure composed of GaP or air is formed in the lower p-AlGaAs layer to form the photonic crystal layer. The thickness of the photonic crystal layer is 100-400 nm; the lattice type of the photonic crystal layer is a triangular lattice, a square lattice, or a honeycomb lattice, with a period of 200-250 nm and a hole radius of 30-80 nm. The thickness of the lower p-AlGaAs layer is 300-800 nm, the Al content is 20%-40%, and its refractive index is 3.4-3.

5. The thickness of the upper p-AlGaAs layer is 300-1200 nm, the Al content is 40%-60%, and the refractive index is 3.25-3.

35.

5. The laser according to any one of claims 1-4, characterized in that, The n-GaAs substrate has a refractive index of 3.6-3.75; The n-AlGaAs cladding has a thickness of 500-1200 nm, an Al content of 40%-60%, and a refractive index of 3.25-3.

35. The n-AlGaAs first confinement layer has a thickness of 100-400 nm, an Al content of 20%-40%, and a refractive index of 3.4-3.

5. The active layer of the quantum well consists of 3-5 pairs of alternating InAlGaAs and AlGaAs layers, wherein the refractive index of the InAlGaAs layer is 3.5-3.65 and the refractive index of the AlGaAs layer is 3.4-3.5; the In content of the InAlGaAs layer is 5%-12% and the Al content is 10%-15%; the Al content of the AlGaAs layer is 20%-40%. The p+-GaAs contact layer has a thickness of 2-10 nm and a refractive index of 3.6-3.

75. The p electrode is an ohmic contact metal electrode or a composite electrode of a metal electrode and ITO. The n-electrode is an ohmic contact metal electrode.

6. The method for preparing the laser according to claim 2, characterized in that, Step 1: Epitaxially grow GaAs-based group III-V materials on an n-GaAs substrate, specifically, from bottom to top, an n-AlGaAs cladding layer, an n-AlGaAs first confinement layer, a quantum well active layer, a p-AlGaAs second confinement layer, and a p+-GaAs contact layer are formed sequentially. Step 2: Deposit an amorphous silicon layer or titanium oxide layer of a certain thickness on the surface of the p+-GaAs contact layer; Step 3: Prepare a photonic crystal mask layer by electron beam lithography (EBL) or nanoimprinting, and form periodic holes by dry etching of the amorphous silicon layer or titanium oxide layer. Remove the mask layer to obtain the photonic crystal layer. Step 4: Expose the area on the surface of the p+-GaAs contact layer used for fabricating the p electrode by photolithography and etching; Step 5: Deposit p-electrode material in the area where the p-electrode is to be fabricated, form the p-electrode structure by lift-off peeling, and anneal; Step 6: Perform photolithography on the bottom surface of the n-GaAs substrate to deposit the n-electrode material, form the n-electrode structure by lift-off, and anneal; Step 7: Deposit a silicon oxide insulating confinement layer in the non-photonic crystal region and non-electrode region located on the surface of the p+-GaAs contact layer and the bottom surface of the n-GaAs substrate layer using a photolithography-etching process.

7. The method for preparing the laser according to claim 3, characterized in that, Includes the following steps: Step 1: Epitaxially grow GaAs-based group III-V materials on an n-GaAs substrate, specifically, from bottom to top, an n-AlGaAs cladding layer, an n-AlGaAs first confinement layer, a quantum well active layer, a p-AlGaAs second confinement layer, and a p+-GaAs contact layer are formed sequentially. Step 2: Prepare a photonic crystal mask layer by electron beam lithography (EBL) or nanoimprinting, dry etch the p+-GaAs contact layer and p-AlGaAs second confinement layer to form periodic holes, and remove the mask layer to obtain the photonic crystal layer. Step 3: Expose the area on the surface of the p+-GaAs contact layer used for fabricating the p electrode by photolithography and etching; Step 4: Deposit p-electrode material in the area where the p-electrode is to be fabricated, form the p-electrode structure by lift-off peeling, and anneal; Step 5: Perform photolithography on the bottom surface of the n-GaAs substrate to deposit the n-electrode material, form the n-electrode structure by lift-off, and anneal; Step 6: Deposit a silicon oxide insulating confinement layer in the non-photonic crystal region and non-electrode region located on the surface of the p+-GaAs contact layer and the bottom surface of the n-GaAs substrate layer using a photolithography-etching process.

8. The method for preparing the laser according to claim 4, characterized in that, Includes the following steps: Step 1: Epitaxially grow GaAs-based group III-V materials on an n-GaAs substrate, specifically, from bottom to top, an n-AlGaAs cladding layer, an n-AlGaAs first confinement layer, a quantum well active layer, and a lower p-AlGaAs layer of a certain thickness; Step 2: Deposit a GaP layer on the partially thick p-AlGaAs layer; Step 3: Prepare a photonic crystal mask layer by electron beam lithography (EBL) or nanoimprint lithography, dry etch GaP to form a periodic structure, and remove the mask layer; Step 4: Continue epitaxial growth of the lower p-AlGaAs layer to completely bury the GaP structure; then epitaxially grow the upper p-AlGaAs layer and the p+-GaAs contact layer. Step 5: Expose the area on the surface of the p+-GaAs contact layer used for fabricating the p electrode by photolithography; Step 6: Deposit p-electrode material in the area where the p-electrode is to be fabricated, form the p-electrode structure by lift-off peeling, and anneal; Step 7: Perform photolithography on the bottom surface of the n-GaAs substrate to deposit the n-electrode material, form the n-electrode structure by lift-off, and anneal; Step 8: Deposit a silicon oxide insulating confinement layer in the non-photonic crystal region and non-electrode region located on the surface of the p+-GaAs contact layer and the bottom surface of the n-GaAs substrate layer using a photolithography-etching process.

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