Method for manufacturing photonic crystal structure and photonic crystal structure

Abstract

The application discloses a photonic crystal structure manufacturing method and a photonic crystal structure. The manufacturing method comprises the following steps: providing a substrate, forming a first epitaxial layer containing Al elements on the surface of the substrate; forming a second epitaxial layer on the surface of the first epitaxial layer containing Al elements; forming a periodically distributed hole structure on the second epitaxial layer and the first epitaxial layer containing Al elements, the hole structure penetrating into the first epitaxial layer containing Al elements at least; taking the second epitaxial layer as a mask, and oxidizing the first epitaxial layer containing Al elements in the hole structure; and epitaxially growing a third epitaxial layer, the third epitaxial layer filling and / or covering the hole structure. The photonic crystal structure manufacturing method and the photonic crystal structure adopt the method of taking the second epitaxial layer as a mask, oxidizing the first epitaxial layer containing Al elements to form an Al oxide layer, and cooperating with secondary epitaxial regrowth, so that the photonic crystal structure with periodically arranged epitaxial layers / oxide layers or the photonic crystal structure with periodically arranged epitaxial layers / holes can be formed.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor laser technology, specifically relating to a method for fabricating a photonic crystal structure and the photonic crystal structure itself. Background Technology

[0002] Semiconductor lasers, characterized by their small size and high efficiency, have been widely used in sensing, communication, and industrial processing. Compared to gas and solid-state lasers, semiconductor lasers have a disadvantage in high-power output, and this is typically addressed by using transverse arrays and vertical integration of multiple emission regions to improve output power. Traditional semiconductor laser structures, such as edge-emitting lasers (EELs) and vertical-cavity surface-emitting lasers (VCSELs), struggle to simultaneously meet the requirements of high output power and high beam quality. However, by incorporating photonic crystals into semiconductor lasers to create photonic crystal surface-emitting lasers (PCSELs), the advantages of high output power from EELs and vertical emission from VCSELs can be combined. Furthermore, by utilizing the edge states of photonic crystals, the horizontal resonant cavity can activate a larger area of ​​the active emission region, thereby achieving higher peak power while maintaining stable single-mode output. Therefore, the structural design and fabrication of photonic crystals are key technologies for PCSEL lasers.

[0003] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a method for fabricating a photonic crystal structure and a photonic crystal structure, so as to solve the problems in the prior art.

[0005] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0006] A method for fabricating a photonic crystal structure includes:

[0007] A substrate is provided, and a first epitaxial layer containing Al is formed on the surface of the substrate;

[0008] A second epitaxial layer is formed on the surface of the first epitaxial layer containing Al;

[0009] A periodically distributed pore structure is formed on the second epitaxial layer and the first epitaxial layer containing Al, the pore structure extending at least into the first epitaxial layer containing Al.

[0010] Using the second epitaxial layer as a mask, the first epitaxial layer containing Al element within the hole structure is oxidized;

[0011] A third epitaxial layer is grown, which fills and / or covers the pore structure.

[0012] In one or more embodiments of the present invention, the second epitaxial layer does not contain Al elements.

[0013] In one or more embodiments of the present invention, the third epitaxial layer does not contain Al elements.

[0014] In one or more embodiments of the present invention, the material of the third epitaxial layer is the same as the material of the second epitaxial layer.

[0015] In one or more embodiments of the present invention, the thickness of the first epitaxial layer containing Al element ranges from 10 nm to 500 nm; the thickness of the second epitaxial layer ranges from 50 nm to 1000 nm.

[0016] In one or more embodiments of the present invention, the substrate does not contain Al.

[0017] In one or more embodiments of the present invention, the substrate includes an Al-free substrate or an Al-free fourth epitaxial layer.

[0018] In one or more embodiments of the present invention, the doping concentration of Al element in the first epitaxial layer containing Al element is in the range of 1E18cm. -3 ~5E19cm -3 .

[0019] In one or more embodiments of the present invention, a periodically distributed hole structure is formed on the second epitaxial layer and the first epitaxial layer containing Al, including:

[0020] Photolithography, dry etching, or wet etching are used to periodically remove portions of the second epitaxial layer and the first epitaxial layer containing Al elements to form a periodically distributed hole structure, wherein the hole structure completely penetrates the second epitaxial layer and the first epitaxial layer containing Al elements.

[0021] In one or more embodiments of the present invention, a periodically distributed hole structure is formed on the second epitaxial layer and the first epitaxial layer containing Al, including:

[0022] Photolithography, dry etching, or wet etching are used to periodically remove portions of the second epitaxial layer and the first epitaxial layer containing Al elements to form a periodically distributed hole structure, wherein the hole structure completely penetrates the second epitaxial layer but does not penetrate the first epitaxial layer containing Al elements.

[0023] In one or more embodiments of the present invention, the first epitaxial layer containing Al is completely oxidized using the second epitaxial layer as a mask to form an Al oxide layer.

[0024] In one or more embodiments of the present invention, a third epitaxial layer is epitaxially grown, the third epitaxial layer filling and / or covering the hole structure, including:

[0025] A third epitaxial layer is grown within the hole structure, the third epitaxial layer completely filling the hole structure, and the surface of the third epitaxial layer is flush with the surface of the second epitaxial layer.

[0026] In one or more embodiments of the present invention, the first epitaxial layer containing Al elements within the pore structure is surface-oxidized using the second epitaxial layer as a mask to form an Al oxide layer.

[0027] In one or more embodiments of the present invention, a third epitaxial layer is epitaxially grown, the third epitaxial layer filling and / or covering the hole structure, including:

[0028] A third epitaxial layer is grown laterally on the second epitaxial layer within the hole structure, the third epitaxial layer covering the hole structure, and the surface of the third epitaxial layer being flush with the surface of the second epitaxial layer.

[0029] A specific embodiment of the present invention also provides a photonic crystal structure, which is fabricated by the above-described method for fabricating a photonic crystal structure.

[0030] In one or more embodiments of the present invention, the photonic crystal structure includes:

[0031] Base;

[0032] An Al oxide layer is formed on the surface of the substrate, and a periodically distributed first pore structure is formed on the Al oxide layer, wherein the first pore structure does not penetrate the Al oxide layer.

[0033] An epitaxial layer is formed on the surface of the Al oxide layer and covers the first pore structure.

[0034] In one or more embodiments of the present invention, the photonic crystal structure includes:

[0035] Base;

[0036] An Al oxide layer is formed on the surface of the substrate, and a periodically distributed first pore structure is formed on the Al oxide layer, the first pore structure penetrating the Al oxide layer.

[0037] An epitaxial layer is formed on the surface of the Al oxide layer and fills the first pore structure.

[0038] In one or more embodiments of the present invention, the photonic crystal structure includes:

[0039] Base;

[0040] An Al-containing first epitaxial layer is formed on the surface of the substrate. A periodically distributed first pore structure is formed on the Al-containing first epitaxial layer. The first pore structure penetrates the Al-containing first epitaxial layer. An Al-containing oxide layer is formed on the inner wall of the first pore structure.

[0041] An epitaxial layer is formed on the surface of the first epitaxial layer containing Al elements and fills the first hole structure.

[0042] In one or more embodiments of the present invention, the photonic crystal structure includes:

[0043] Base;

[0044] An Al-containing first epitaxial layer is formed on the surface of the substrate. A periodically distributed first pore structure is formed on the Al-containing first epitaxial layer. The first pore structure does not penetrate the Al-containing first epitaxial layer. An Al-containing oxide layer is formed on the inner wall of the first pore structure.

[0045] An epitaxial layer is formed on the surface of the first epitaxial layer containing Al elements and covers the first hole structure.

[0046] Compared with the prior art, the method for fabricating the photonic crystal structure and the photonic crystal structure of the present invention adopts a method of oxidizing the first epitaxial layer containing Al element to form an Al oxide layer using the second epitaxial layer as a mask, and combined with secondary epitaxial regeneration, to form a photonic crystal structure with periodic arrangement of epitaxial layer / oxide layer or a photonic crystal structure with periodic arrangement of epitaxial layer / pore.

[0047] The method for fabricating a photonic crystal structure and the photonic crystal structure of the present invention utilize the characteristic that the first epitaxial layer containing Al is easily oxidized, and use the second epitaxial layer without Al as a mask to form a periodic hole structure. This eliminates the need for the deposition, etching, and removal processes of dielectric layers such as silicon oxide and silicon nitride in the prior art. Furthermore, it can take advantage of the characteristic that the second epitaxial layer without Al is easy to grow again and the characteristic that the first epitaxial layer containing Al cannot grow after oxidation, so as to flexibly control the coverage of the Al oxide layer in the first epitaxial layer containing Al. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a process flow diagram of a method for fabricating a photonic crystal structure according to an embodiment of the present invention;

[0050] Figures 2a-2c This is a flowchart illustrating the process steps of fabricating a photonic crystal structure in the first embodiment of the present invention.

[0051] Figure 3 This is a schematic diagram of the photonic crystal structure in the first embodiment of the present invention;

[0052] Figures 4a-4c This is a flowchart illustrating the process steps of fabricating a photonic crystal structure in the second embodiment of the present invention.

[0053] Figure 5 This is a schematic diagram of the photonic crystal structure in the second embodiment of the present invention;

[0054] Figures 6a-6c This is a flowchart illustrating the process steps of the method for fabricating a photonic crystal structure in the third embodiment of the present invention;

[0055] Figure 7 This is a schematic diagram of the photonic crystal structure in the third embodiment of the present invention;

[0056] Figures 8a-8c This is a flowchart illustrating the process steps of fabricating a photonic crystal structure in the fourth embodiment of the present invention.

[0057] Figure 9 This is a schematic diagram of the photonic crystal structure in the fourth embodiment of the present invention. Detailed Implementation

[0058] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0059] As mentioned in the background section, applying photonic crystals to semiconductor lasers to form PCSELs can combine the advantages of high output power of EELs with vertical output of VCSELs. By utilizing the edge states of the photonic crystal, the horizontal resonant cavity can activate a larger area of ​​the light-emitting active region, thereby achieving higher peak power and maintaining stable single-mode output. Therefore, the structural design and fabrication of photonic crystals are key technologies for PCSEL lasers.

[0060] Photonic crystals require a periodic high refractive index contrast and are therefore constructed from semiconductor materials combined with dielectric materials or air holes. This invention provides a method for fabricating a photonic crystal structure and the resulting structure. Utilizing the ease of oxidation of the first epitaxial layer containing Al, a second epitaxial layer without Al is used as a mask to form a periodic hole structure. The first epitaxial layer containing Al within the hole structure is then directly oxidized to form an Al oxide layer. Taking advantage of the fact that the oxidized first epitaxial layer cannot be epitaxially grown again, while the second epitaxial layer without Al is easily re-epitaxially grown, a photonic crystal structure with a periodic arrangement of epitaxial layers / oxide layers or a periodic arrangement of epitaxial layers / air holes can be constructed through secondary epitaxial growth.

[0061] like Figure 1 As shown, a method for fabricating a photonic crystal structure in one embodiment of the present invention includes:

[0062] S1 provides a substrate, and forms a first epitaxial layer containing Al on the substrate surface;

[0063] S2, a second epitaxial layer is formed on the surface of the first epitaxial layer containing Al;

[0064] S3, a periodically distributed pore structure is formed on the second epitaxial layer and the first epitaxial layer containing Al elements, the pore structure extending at least into the first epitaxial layer containing Al elements;

[0065] S4, using the second epitaxial layer as a mask, oxidize the first epitaxial layer containing Al elements within the pore structure;

[0066] S5, a third epitaxial layer is grown epitaxially, and the third epitaxial layer fills and / or covers the hole structure.

[0067] In step S1, the substrate can be an Al-free substrate, an Al-free fourth epitaxial layer, or an Al-free fourth epitaxial layer grown on the surface of an Al-free substrate. The thickness of the Al-containing first epitaxial layer ranges from 10 nm to 500 nm. The Al doping concentration in the Al-containing first epitaxial layer ranges from 1E18 cm⁻¹. -3 ~5E19cm -3 .

[0068] In step S2, the second epitaxial layer does not contain Al. The thickness of the second epitaxial layer ranges from 50 nm to 1000 nm.

[0069] In step S3, photolithography, dry etching, or wet etching processes can be used to form a periodically distributed hole structure on the second epitaxial layer and the first epitaxial layer containing Al, wherein the retained portions of the second epitaxial layer and the first epitaxial layer containing Al are alternately arranged with the hole structure. The hole structure can completely penetrate the second epitaxial layer and the first epitaxial layer containing Al; alternatively, the hole structure can completely penetrate the second epitaxial layer but not the first epitaxial layer containing Al.

[0070] In step S4, the first epitaxial layer containing Al can be completely oxidized using the second epitaxial layer as a mask to form an Al oxide layer. Alternatively, the first epitaxial layer containing Al within the pore structure can be surface-oxidized using the second epitaxial layer as a mask to form an amorphous Al oxide layer on the surface of the first epitaxial layer containing Al.

[0071] In step S5, if the pore structure completely penetrates the second epitaxial layer and the first epitaxial layer containing Al, a third epitaxial layer is grown within the pore structure, completely filling the pore structure, and its surface is flush with the surface of the second epitaxial layer. If the pore structure completely penetrates the second epitaxial layer but not the first epitaxial layer containing Al, a third epitaxial layer is grown laterally on the second epitaxial layer within the pore structure, covering the pore structure, and its surface is flush with the surface of the second epitaxial layer. The pore structure within the first epitaxial layer containing Al forms a cavity. This is because crystalline epitaxial layers cannot be regrown on an amorphous Al oxide layer. Therefore, when growing the third epitaxial layer, it can only be grown vertically on the substrate and laterally within the pore structure of the second epitaxial layer. The area enclosed by the Al oxide layer within the pore structure forms a cavity. The third epitaxial layer does not contain Al, and its material is the same as that of the second epitaxial layer.

[0072] The following detailed description of the method for fabricating the photonic crystal structure of this application and the photonic crystal structure fabricated by the method is provided through several specific embodiments to facilitate a further understanding of the technical solution of this application.

[0073] First embodiment:

[0074] Please refer to Figure 2aAs shown, an Al-containing first epitaxial layer 20 and an Al-free second epitaxial layer 30 are sequentially grown on an Al-free single-crystal substrate or on an Al-free fourth epitaxial layer 10 using an epitaxial growth method. The thickness of the Al-containing first epitaxial layer 20 ranges from 10 nm to 500 nm, and the Al doping concentration within the Al-containing first epitaxial layer 20 ranges from 1E18 cm⁻¹. -3 ~5E19cm -3 The thickness of the topmost, al-free second epitaxial layer 30 is 50-1000 nm. The material combination of the al-containing first epitaxial layer 20 and the al-free second epitaxial layer 30 can be GaAs / AlGaAs or InP / InAlAs.

[0075] Please refer to Figure 2b As shown, by combining photolithography with dry etching or wet etching, portions of the second epitaxial layer 30 (containing no Al) and the first epitaxial layer 20 (containing Al) are periodically removed to form periodically distributed hole structures 40 on the second epitaxial layer 30 and the first epitaxial layer 20. The retained portions of the second epitaxial layer 30 and the first epitaxial layer 20 (containing Al) alternate with the removed portions—the hole structures 40. In the first embodiment of this application, the hole structures 40 formed by the removed portions completely penetrate the second epitaxial layer 30 and the first epitaxial layer 20 (containing Al) in the thickness direction, exposing a portion of the single-crystal substrate (containing no Al) or the fourth epitaxial layer 10 (containing no Al). The retained portions of the second epitaxial layer 30 and the first epitaxial layer 20 (containing Al) have rectangular cross-sections.

[0076] Please refer to Figure 2c As shown, using the second epitaxial layer 30 as a mask, the first epitaxial layer 20 containing Al is completely oxidized, so that the first epitaxial layer 20 containing Al is transformed into an amorphous Al oxide layer 20a. The main material composition of the Al oxide layer 20a is aluminum oxide (Al2O3).

[0077] Please refer to Figure 3 As shown, a third epitaxial layer 50 is grown within the hole structure 40 using epitaxial regeneration technology, and the third epitaxial layer 50 completely fills the hole structure 40. The surface of the third epitaxial layer 50 is flush with the surface of the second epitaxial layer 30. The third epitaxial layer 50 does not contain Al, and the material of the third epitaxial layer 50 is the same as that of the second epitaxial layer 30. In the first embodiment of this application, the regenerated third epitaxial layer 50 is merged with the original second epitaxial layer 30 and then covered with an Al oxide layer 20a.

[0078] For example, an N-type doped layer with a thickness of 500 nm and a doping concentration of 5E18 cm⁻¹ is grown on an N-type GaAs substrate using MOCVD.-3 Al 0.95 Ga 0.05 The As layer is regrown to a thickness of 800 nm with an N-type doping concentration of 1E19cm. -3 The GaAs layer was etched using photolithography and dry etching to create a micro-cylindrical array (the retained portion) with a spacing of 900 nm and a diameter of 200 nm. The cylinders were 1300 nm high. The AlGaAs layer at the bottom of the cylinders was completely oxidized to Al2O3 using an oxidation furnace. After surface cleaning, the oxidized cylindrical array was placed in MOCVD for secondary epitaxial growth, depositing an N-type GaAs layer with a thickness of 1300 nm and a doping concentration of 1E19 cm⁻¹. -3 This forms a GaAs-covered periodic Al2O3 photonic crystal structure.

[0079] Please refer to Figure 3 As shown, the first embodiment of this application also provides a photonic crystal structure, including a substrate, an Al oxide layer 20a, and an epitaxial layer. The substrate is an Al-free substrate or an Al-free fourth epitaxial layer 10. The Al oxide layer 20a is formed on the surface of the substrate, and a periodically distributed first hole structure is formed on the Al oxide layer 20a, the first hole structure penetrating the Al oxide layer 20a; the epitaxial layer is formed on the surface of the Al oxide layer 20a and fills the first hole structure.

[0080] Second embodiment:

[0081] Please refer to Figure 4a As shown, an Al-containing first epitaxial layer 20 and an Al-free second epitaxial layer 30 are sequentially grown on an Al-free single-crystal substrate or on an Al-free fourth epitaxial layer 10 using an epitaxial growth method. The thickness of the Al-containing first epitaxial layer 20 ranges from 10 nm to 500 nm, and the Al doping concentration within the Al-containing first epitaxial layer 20 ranges from 1E18 cm⁻¹. -3 ~5E19cm -3 The thickness of the topmost, al-free second epitaxial layer 30 is 50-1000 nm. The material combination of the al-containing first epitaxial layer 20 and the al-free second epitaxial layer 30 can be GaAs / AlGaAs or InP / InAlAs.

[0082] Please refer to Figure 4bAs shown, by combining photolithography with dry etching or wet etching, portions of the second epitaxial layer 30 (containing no Al) and the first epitaxial layer 20 (containing Al) are periodically removed to form periodically distributed hole structures 40 on the second epitaxial layer 30 and the first epitaxial layer 20. The retained portions of the second epitaxial layer 30 and the first epitaxial layer 20 (containing Al) alternate with the removed portions—the hole structures 40. In the second embodiment of this application, the hole structures 40 formed by the removed portions completely penetrate the second epitaxial layer 30 in the thickness direction, but do not penetrate the first epitaxial layer 20 (containing Al), thus maintaining communication at the bottom of the first epitaxial layer 40. The cross-sections of the retained portions of the second epitaxial layer 30 and the first epitaxial layer 20 (containing Al) are trapezoidal.

[0083] Please refer to Figure 4c As shown, using the second epitaxial layer 30 as a mask, the first epitaxial layer 20 containing Al is completely oxidized, so that the first epitaxial layer 20 containing Al is transformed into an amorphous Al oxide layer 20a. The main material composition of the Al oxide layer 20a is aluminum oxide (Al2O3).

[0084] Please refer to Figure 5 As shown, a third epitaxial layer 50 is laterally grown on the second epitaxial layer 30 within the hole structure 40 using epitaxial regeneration technology until the third epitaxial layer 50 is closed to cover the hole structure 40. The surface of the third epitaxial layer 50 is flush with the surface of the second epitaxial layer 30. The third epitaxial layer 50 does not contain Al, and the material of the third epitaxial layer 50 is the same as that of the second epitaxial layer 30. In the second embodiment of this application, the regenerated third epitaxial layer 50 merges with the original second epitaxial layer 30 to cover the hole structure within the first epitaxial layer 20 containing Al, thereby forming a cavity within the hole structure of the first epitaxial layer 20 containing Al.

[0085] Please refer to Figure 5 As shown, a second embodiment of this application also provides a photonic crystal structure, including a substrate, an Al oxide layer 20a, and an epitaxial layer. The substrate is an Al-free substrate or an Al-free fourth epitaxial layer 10. The Al oxide layer 20a is formed on the surface of the substrate, and a periodically distributed first hole structure is formed on the Al oxide layer 20a, the first hole structure not penetrating the Al oxide layer 20a; the epitaxial layer is formed on the surface of the Al oxide layer 20a and covers the first hole structure.

[0086] Third embodiment:

[0087] Please refer to Figure 6aAs shown, an Al-containing first epitaxial layer 20 and an Al-free second epitaxial layer 30 are sequentially grown on an Al-free single-crystal substrate or on an Al-free fourth epitaxial layer 10 using an epitaxial growth method. The thickness of the Al-containing first epitaxial layer 20 ranges from 10 nm to 500 nm, and the Al doping concentration within the Al-containing first epitaxial layer 20 ranges from 1E18 cm⁻¹. -3 ~5E19cm -3 The thickness of the topmost, al-free second epitaxial layer 30 is 50-1000 nm. The material combination of the al-containing first epitaxial layer 20 and the al-free second epitaxial layer 30 can be GaAs / AlGaAs or InP / InAlAs.

[0088] Please refer to Figure 6b As shown, by combining photolithography with dry etching or wet etching, portions of the second epitaxial layer 30 (containing no Al) and the first epitaxial layer 20 (containing Al) are periodically removed to form periodically distributed hole structures 40 on the second epitaxial layer 30 and the first epitaxial layer 20. The retained portions of the second epitaxial layer 30 and the first epitaxial layer 20 (containing Al) alternate with the removed portions—the hole structures 40. In the third embodiment of this application, the hole structures 40 formed by the removed portions completely penetrate the second epitaxial layer 30 and the first epitaxial layer 20 (containing Al) in the thickness direction, exposing a portion of the single-crystal substrate (containing no Al) or the fourth epitaxial layer 10 (containing no Al). The cross-sections of the retained portions of the second epitaxial layer 30 and the first epitaxial layer 20 (containing Al) are rectangular.

[0089] Please refer to Figure 6c As shown, using the second epitaxial layer 30 as a mask, the first epitaxial layer 20 containing Al elements within the hole structure 40 is surface-oxidized to form an amorphous Al-containing oxide layer 20b on the surface of the first epitaxial layer 20 containing Al elements within the hole structure 40. The main material of the Al-containing oxide layer 20b is aluminum oxide (Al2O3).

[0090] Please refer to Figure 7 As shown, a third epitaxial layer 50 is grown within the hole structure 40 using epitaxial regeneration technology, and the third epitaxial layer 50 completely fills the hole structure 40. The surface of the third epitaxial layer 50 is flush with the surface of the second epitaxial layer 30. The third epitaxial layer 50 does not contain Al, and the material of the third epitaxial layer 50 is the same as that of the second epitaxial layer 30. In the third embodiment of this application, after the regenerated third epitaxial layer 50 is merged with the original second epitaxial layer 30, it covers the Al oxide layer 20b together with the Al-containing first epitaxial layer 20.

[0091] Please refer to Figure 7As shown, a third embodiment of this application also provides a photonic crystal structure, including a substrate, a first epitaxial layer 20 containing Al, and an epitaxial layer. The substrate is an Al-free substrate or a fourth epitaxial layer 10 containing Al. The first epitaxial layer 20 containing Al is formed on the surface of the substrate, and a periodically distributed first hole structure is formed on the first epitaxial layer 20 containing Al. The first hole structure penetrates the first epitaxial layer 20 containing Al, and an Al oxide layer 20b is formed on the inner wall of the first hole structure. The epitaxial layer is formed on the surface of the first epitaxial layer 20 containing Al and completely fills the first hole structure.

[0092] Fourth embodiment:

[0093] Please refer to Figure 8a As shown, an Al-containing first epitaxial layer 20 and an Al-free second epitaxial layer 30 are sequentially grown on an Al-free single-crystal substrate or on an Al-free fourth epitaxial layer 10 using an epitaxial growth method. The thickness of the Al-containing first epitaxial layer 20 ranges from 10 nm to 500 nm, and the Al doping concentration within the Al-containing first epitaxial layer 20 ranges from 1E18 cm⁻¹. -3 ~5E19cm -3 The thickness of the topmost, al-free second epitaxial layer 30 is 50-1000 nm. The material combination of the al-containing first epitaxial layer 20 and the al-free second epitaxial layer 30 can be GaAs / AlGaAs or InP / InAlAs.

[0094] Please refer to Figure 8b As shown, by combining photolithography with dry etching or wet etching, portions of the second epitaxial layer 30 (containing no Al) and the first epitaxial layer 20 (containing Al) are periodically removed to form periodically distributed hole structures 40 on the second epitaxial layer 30 and the first epitaxial layer 20. The retained portions of the second epitaxial layer 30 and the first epitaxial layer 20 (containing Al) alternate with the removed portions—the hole structures 40. In the fourth embodiment of this application, the hole structures 40 formed by the removed portions completely penetrate the second epitaxial layer 30 in the thickness direction, but do not penetrate the first epitaxial layer 20 (containing Al), thus maintaining communication at the bottom of the first epitaxial layer 40. The cross-sections of the retained portions of the second epitaxial layer 30 and the first epitaxial layer 20 (containing Al) are trapezoidal.

[0095] Please refer to Figure 8cAs shown, using the second epitaxial layer 30 as a mask, the first epitaxial layer 20 containing Al elements within the hole structure 40 is surface-oxidized to form an amorphous Al-containing oxide layer 20b on the surface of the first epitaxial layer 20 containing Al elements within the hole structure 40. The main material of the Al-containing oxide layer 20b is aluminum oxide (Al2O3).

[0096] Please refer to Figure 9 As shown, a third epitaxial layer 50 is laterally grown on the second epitaxial layer 30 within the hole structure 40 using epitaxial regeneration technology until the third epitaxial layer 50 is closed to cover the hole structure 40. The surface of the third epitaxial layer 50 is flush with the surface of the second epitaxial layer 30. The third epitaxial layer 50 does not contain Al, and the material of the third epitaxial layer 50 is the same as that of the second epitaxial layer 30. In the fourth embodiment of this application, the regenerated third epitaxial layer 50 merges with the original second epitaxial layer 30 to cover the hole structure within the first epitaxial layer 20 containing Al, thereby forming a cavity within the hole structure of the first epitaxial layer 20 containing Al.

[0097] For example, an undoped InP layer with a thickness of 300 nm was grown on a semi-insulating InP substrate using MOCVD, followed by the growth of a 40 nm P-type doped layer with a concentration of 5E18 cm⁻¹. -3 In 0.52 Al 0.48 As, the p-type doping concentration for the 150nm thick layer is 3E18cm. -3 The InP layer was used to create a micro-conical array (the retained portion) with a periodic spacing of 1300 nm and a diameter of 400 nm through photolithography and wet etching, with a cone height of 170 nm. The lower 20 nm of the InAlAs surface layer of the cones was oxidized to Al2O3 using an oxidation furnace. After surface cleaning, the oxidized cone array was placed in MOCVD for secondary epitaxial growth, depositing a 200 nm thick P-type InP layer with a doping concentration of 3E18 cm⁻¹. -3 This results in a photonic crystal structure consisting of an InAlAs layer with a periodic surface covered by InP, and cavities.

[0098] Please refer to Figure 9 As shown, the fourth embodiment of this application also provides a photonic crystal structure, including a substrate, a first epitaxial layer 20 containing Al, and an epitaxial layer. The substrate is an Al-free substrate or a fourth epitaxial layer 10 containing Al. The first epitaxial layer 20 containing Al is formed on the surface of the substrate, and a periodically distributed first hole structure is formed on the first epitaxial layer 20 containing Al. The first hole structure does not penetrate the first epitaxial layer 20 containing Al, and an Al oxide layer 20b is formed on the inner wall of the first hole structure. The epitaxial layer is formed on the surface of the first epitaxial layer 20 containing Al and covers the first hole structure.

[0099] Compared with the prior art, the method for fabricating the photonic crystal structure and the photonic crystal structure of the present invention adopts a method of oxidizing the first epitaxial layer containing Al element to form an Al oxide layer using the second epitaxial layer as a mask, and combined with secondary epitaxial regeneration, to form a photonic crystal structure with periodic arrangement of epitaxial layer / oxide layer or a photonic crystal structure with periodic arrangement of epitaxial layer / pore.

[0100] The method for fabricating a photonic crystal structure and the photonic crystal structure of the present invention utilize the characteristic that the first epitaxial layer containing Al is easily oxidized, and use the second epitaxial layer without Al as a mask to form a periodic hole structure. This eliminates the need for the deposition, etching, and removal processes of dielectric layers such as silicon oxide and silicon nitride in the prior art. Furthermore, it can take advantage of the characteristic that the second epitaxial layer without Al is easy to grow again and the characteristic that the first epitaxial layer containing Al cannot grow after oxidation, so as to flexibly control the coverage of the Al oxide layer in the first epitaxial layer containing Al.

[0101] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0102] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for fabricating a photonic crystal structure, characterized in that, include: A substrate is provided, and a first epitaxial layer containing Al is formed on the surface of the substrate; A second epitaxial layer is formed on the surface of the first epitaxial layer containing Al, wherein the second epitaxial layer does not contain Al. A periodically distributed pore structure is formed on the second epitaxial layer and the first epitaxial layer containing Al, the pore structure extending at least into the first epitaxial layer containing Al. Using the second epitaxial layer as a mask, the first epitaxial layer containing Al elements within the hole structure is oxidized to form an amorphous Al-containing oxide layer; A third epitaxial layer is grown, which fills and / or covers the pore structure.

2. The method for fabricating a photonic crystal structure according to claim 1, characterized in that, The third epitaxial layer does not contain Al; and / or, The material of the third epitaxial layer is the same as the material of the second epitaxial layer; and / or, The thickness of the first epitaxial layer containing Al element ranges from 10nm to 500nm; the thickness of the second epitaxial layer ranges from 50nm to 1000nm.

3. The method for fabricating a photonic crystal structure according to claim 1, characterized in that, The substrate does not contain Al; and / or, The substrate includes an Al-free substrate and / or an Al-free fourth epitaxial layer.

4. The method for fabricating a photonic crystal structure according to claim 1, characterized in that, The doping concentration of Al in the first epitaxial layer containing Al is in the range of 1E18cm. -3 ~5E19cm -3 .

5. The method for fabricating a photonic crystal structure according to claim 1, characterized in that, A periodically distributed pore structure is formed on the second epitaxial layer and the first epitaxial layer containing Al, including: Photolithography, dry etching, or wet etching are used to periodically remove portions of the second epitaxial layer and the first epitaxial layer containing Al to form a periodically distributed hole structure, wherein the hole structure completely penetrates the second epitaxial layer and the first epitaxial layer containing Al; or, Photolithography, dry etching, or wet etching are used to periodically remove portions of the second epitaxial layer and the first epitaxial layer containing Al elements to form a periodically distributed hole structure, wherein the hole structure completely penetrates the second epitaxial layer but does not penetrate the first epitaxial layer containing Al elements.

6. The method for fabricating a photonic crystal structure according to claim 5, characterized in that, Using the second epitaxial layer as a mask, the first epitaxial layer containing Al is completely oxidized to form an Al oxide layer.

7. The method for fabricating a photonic crystal structure according to claim 6, characterized in that, Epitaxial growth of a third epitaxial layer, wherein the third epitaxial layer fills and / or covers the hole structure, comprising: A third epitaxial layer is grown within the hole structure, the third epitaxial layer completely filling the hole structure, and the surface of the third epitaxial layer is flush with the surface of the second epitaxial layer.

8. The method for fabricating a photonic crystal structure according to claim 5, characterized in that, Using the second epitaxial layer as a mask, the first epitaxial layer containing Al elements within the pore structure is subjected to surface oxidation to form an Al oxide layer.

9. The method for fabricating a photonic crystal structure according to claim 8, characterized in that, Epitaxial growth of a third epitaxial layer, wherein the third epitaxial layer fills and / or covers the hole structure, comprising: A third epitaxial layer is grown laterally on the second epitaxial layer within the hole structure, the third epitaxial layer covering the hole structure, and the surface of the third epitaxial layer being flush with the surface of the second epitaxial layer.

10. A photonic crystal structure, characterized in that, It is manufactured by the method for fabricating a photonic crystal structure according to any one of claims 1-9.

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