Method of producing photonic crystal and method of manufacturing light-emitting device

Abstract

To provide a method of producing a photonic crystal, capable of producing a photonic crystal that can exhibit a stable optical confinement effect.SOLUTION: A method of producing a photonic crystal includes: a step of forming a first hole, a second hole, a third hole, and a fourth hole, where the first hole and the third hole are formed such that a diameter of the first hole becomes larger than that of the third hole and the second hole and the fourth hole are formed such that a diameter of the second hole becomes larger than that of the fourth hole; and a step of forming a first low refractive index portion, a second low refractive index portion, a third low refractive index portion, and a fourth low refractive index portion, where crystal growth of a second layer is performed such that a difference between the diameter of the first hole and a diameter of the first low refractive index portion becomes larger than a difference between the diameter of the third hole and a diameter of the third low refractive index portion, and a difference between the diameter of the second hole and a diameter of the second low refractive index portion becomes larger than a difference between the diameter of the fourth hole and a diameter of the fourth low refractive index portion.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a photonic crystal and a method for manufacturing a light-emitting device.

Background Art

[0002] Photonic crystals in which the refractive index changes periodically are known.

[0003] For example, Patent Document 1 describes a method for manufacturing a two-dimensional photonic laser, which includes a step of forming a base material layer, a step of periodically forming holes in the base material layer, and a step of forming a layer made of Al x Ga 1-x As by an epitaxial method on the base material layer and the holes.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the method for manufacturing a two-dimensional photonic laser as described above, it is required to manufacture a photonic crystal capable of exhibiting a stable light confinement effect.

Means for Solving the Problems

[0006] One aspect of the method for manufacturing a photonic crystal according to the present invention is a step of forming a first layer, a step of forming, in the first layer, a first hole, a second hole spaced apart from the first hole by a first distance in a first direction, a third hole spaced apart from the first hole by a second distance greater than the first distance in a second direction intersecting the first direction, and a fourth hole spaced apart from the third hole by a third distance smaller than the second distance in the first direction, A step of growing a second layer in the first hole, the second hole, the third hole, and the fourth hole, forming a first low refractive index portion having a refractive index lower than that of the first layer in the first hole, forming a second low refractive index portion having a refractive index lower than that of the first layer in the second hole, forming a third low refractive index portion having a refractive index lower than that of the first layer in the third hole, and forming a fourth low refractive index portion having a refractive index lower than that of the first layer in the fourth hole; including In the step of forming the first hole, the second hole, the third hole, and the fourth hole, the first hole and the third hole are formed such that the diameter of the first hole is larger than the diameter of the third hole, the second hole and the fourth hole are formed such that the diameter of the second hole is larger than the diameter of the fourth hole, In the step of forming the first low refractive index portion, the second low refractive index portion, the third low refractive index portion, and the fourth low refractive index portion, the second layer is crystal-grown such that the difference between the diameter of the first hole and the diameter of the first low refractive index portion is larger than the difference between the diameter of the third hole and the diameter of the third low refractive index portion, and the difference between the diameter of the second hole and the diameter of the second low refractive index portion is larger than the difference between the diameter of the fourth hole and the diameter of the fourth low refractive index portion.

[0007] One aspect of the method for manufacturing a light-emitting device according to the present invention has one aspect of the method for manufacturing the photonic crystal.

Brief Description of Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present invention described in the claims. Also, not all of the configurations described below are essential constituent elements of the present invention.

[0010] 1. Light-emitting device First, the light-emitting device according to this embodiment will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing the light-emitting device 100 according to this embodiment. FIG. 2 is a plan view schematically showing the light-emitting device 100 according to this embodiment. Note that FIG. 1 is a cross-sectional view taken along line I-I of FIG. 2. Also, in FIG. 2, the X-axis, Y-axis, and Z-axis are shown as three axes orthogonal to each other.

[0011] As shown in FIGS. 1 and 2, the light-emitting device 100 includes, for example, a substrate 10, a first semiconductor layer 20, a light-emitting layer 30, a photonic crystal 40, a second semiconductor layer 70, a contact layer 80, a first electrode 90, and a second electrode 92. For convenience, in FIG. 2, the illustration of members other than the photonic crystal 40 is omitted. The light-emitting device 100 is, for example, a Photonic Crystal Surface Emitting Laser (PCSEL).

[0012] The substrate 10 is, for example, a GaAs substrate or the like. The substrate 10 has, for example, conductivity. The substrate 10 has, for example, translucency.

[0013] The first semiconductor layer 20 is provided on the substrate 10. The first semiconductor layer 20 is provided between the substrate 10 and the light-emitting layer 30. The first semiconductor layer 20 is, for example, an n-type AlGaAs layer doped with Si.

[0014] The light-emitting layer 30 is provided on the first semiconductor layer 20. The light-emitting layer 30 is provided between the first semiconductor layer 20 and the second semiconductor layer 70. The light-emitting layer 30 is provided between the first semiconductor layer 20 and the photonic crystal 40. The light-emitting layer 30 generates light when current is injected. The light-emitting layer 30 has, for example, a well layer and a barrier layer. The well layer and the barrier layer are i-type semiconductor layers that are not intentionally doped with impurities. The well layer is, for example, an InGaAs layer. The barrier layer is, for example, a GaAs layer. The light-emitting layer 30 has a MQW (Multiple Quantum Well) structure composed of a well layer and a barrier layer.

[0015] Note that the number of well layers and barrier layers constituting the light-emitting layer 30 is not particularly limited. For example, only one well layer may be provided, and in this case, the light-emitting layer 30 has a SQW (Single Quantum Well) structure.

[0016] The photonic crystal 40 is provided on the light-emitting layer 30. The photonic crystal 40 is provided between the light-emitting layer 30 and the second semiconductor layer 70. The shape of the photonic crystal 40 is, for example, layered. The photonic crystal 40 has a first layer 42, a second layer 44, and a low refractive index portion pair 60. For convenience, in FIG. 2, the outer edges of the hole pair 50 formed in the photonic crystal 40 and the outer edges of the low refractive index portion pair 60 are illustrated. The hole pair 50 is indicated by a dashed line.

[0017] As shown in FIG. 1, the first layer 42 is provided on the light-emitting layer 30. The first layer 42 is provided between the light-emitting layer 30 and the second layer 44. The first layer 42 is, for example, a p-type GaAs layer doped with C.

[0018] In the first layer 42, a pair of holes 50 is formed. The pair of holes 50 is formed by one hole 52 and the other hole 54. In the example shown in FIG. 2, the planar shape of one hole 52 is a circle. The planar shape of the other hole 54 is an ellipse.

[0019] The diameter of the hole 52 is, for example, smaller than the diameter of the hole 54. The diameters of the holes 52 and 54 are, for example, 10 nm or more and 300 nm or less, preferably 20 nm or more and 200 nm or less, and more preferably 40 nm or more and 100 nm or less.

[0020] Note that the "diameter of the hole" is the diameter when the planar shape of the hole is a circle, and is the diameter of the minimum circumscribed circle when the planar shape of the hole is not a circle. For example, when the planar shape of the hole is a polygon, the diameter of the hole is the diameter of the smallest circle that includes the polygon, and when the planar shape of the hole is an ellipse, the diameter of the hole is the diameter of the smallest circle that includes the ellipse. This is the same for the diameter of the low refractive index portion and the diameter of the opening described later.

[0021] The depths of the holes 52 and 54 are, for example, the same. The depths of the holes 52 and 54 are, for example, 100 nm or more and 500 nm or less, preferably 200 nm or more and 400 nm or less, more preferably 250 nm or more and 350 nm or less, and even more preferably 300 nm. The holes 52 and 54 do not reach the light emitting layer 30.

[0022] A plurality of pairs of holes 50 are provided. As shown in FIG. 2, the plurality of pairs of holes 50 are arranged in a square lattice in a plan view. The plurality of pairs of holes 50 are arranged in a square lattice when viewed from the stacking direction of the first semiconductor layer 20 and the light emitting layer 30. The pitch of the plurality of pairs of holes 50 is, for example, 10 nm or more and 500 nm or less, preferably 100 nm or more and 400 nm or less, and more preferably 200 nm or more and 300 nm or less.

[0023] As shown in FIG. 1, the second layer 44 is provided on the first layer 42. The second layer 44 is provided between the first layer 42 and the second semiconductor layer 70. The second layer 44 is provided on the upper surface of the convex portion of the first layer 42 formed by the holes 52 and 54.

[0024] The second layer 44 is provided in the holes 52 and 54. The second layer 44 is provided on the side surfaces 2 and the bottom surfaces 4 of the holes 52 and 54. The side surfaces 2 and the bottom surfaces 4 are defined by the first layer 42. The portion provided on the side surface 2 of the second layer 44 has a portion with a gradually increasing thickness from the light-emitting layer 30 toward the second semiconductor layer 70. The portion with the gradually increasing thickness is located above the holes 52 and 54. In the illustrated example, at the lower part of the holes 52 and 54, the thickness of the portion provided on the side surface 2 and the bottom surface 4 of the second layer 44 is constant.

[0025] Although not shown, the second layer 44 may be provided in the holes 52 and 54 and not provided on the upper surface of the convex portion of the first layer 42. In this case, the second layers 44 provided in the holes 52 and 54 are spaced apart from each other.

[0026] The second layer 44 is, for example, a group III-V semiconductor layer. The second layer 44 is, for example, a p-type AlGaAs layer doped with C. The composition ratio of Al to Ga in the second layer 44 is, for example, 1:1. The refractive index of the first layer 42 and the refractive index of the second layer 44 are, for example, different from each other. The refractive index of the second layer 44 is, for example, smaller than the refractive index of the first layer 42. Note that the second layer 44 may be a GaAs layer.

[0027] The low refractive index portion pair 60 is provided in the hole pair 50. One of the low refractive index portions 62 of the low refractive index portion pair 60 is provided in one of the holes 52 of the hole pair 50. The other low refractive index portion 64 of the low refractive index portion pair 60 is provided in the other hole 54 of the hole pair 50. The shapes of the low refractive index portions 62 and 64 are defined by the second layer 44. The low refractive index portion 62 is a portion not filled with the second layer 44 in the hole 52. The low refractive index portion 64 is a portion not filled with the second layer 44 in the hole 54. The low refractive index portions 62 and 64 have a portion where the diameter gradually decreases from the light emitting layer 30 toward the second semiconductor layer 70.

[0028] The refractive indices of the low refractive index portions 62 and 64 are lower than the refractive index of the first layer 42. The refractive indices of the low refractive index portions 62 and 64 are lower than the refractive index of the second layer 44. In the illustrated example, the low refractive index portions 62 and 64 are voids. Although not shown, the low refractive index portions 62 and 64 may be composed of a member having a refractive index lower than that of the first layer 42 and the second layer 44 instead of voids.

[0029] A plurality of low refractive index portion pairs 60 are provided. As shown in FIG. 2, the plurality of low refractive index portion pairs 60 are arranged in a square lattice pattern in a plan view, similarly to the plurality of hole pairs 50. The pitch a of the plurality of low refractive index portion pairs 60 is, for example, the same as the wavelength of the light generated in the light emitting layer 30. In the illustrated example, the pitch a is the distance between the centers of the low refractive index portions 62 of adjacent low refractive index portion pairs 60. The plurality of low refractive index portion pairs 60 form a unit lattice. In the photonic crystal 40, two low refractive index portions 62 and 64 are provided per unit lattice. Although not shown, three low refractive index portions may be provided per unit lattice.

[0030] In one low refractive index portion pair 60, the low refractive index portion 62 is located 0.25a away from the low refractive index portion 64 in the +X axis direction. The low refractive index portion 62 is located 0.25a away from the low refractive index portion 64 in the -Y axis direction. Therefore, when the pitch a is equal to the wavelength λ of the light In the case where, for example, with respect to light propagating in the +X axis direction, the optical path difference between the light reflected by the low refractive index portion 62 and the light reflected by the low refractive index portion 64 becomes λ / 2, and destructive interference occurs. Thereby, light of a desired wavelength can be resonated. The plurality of low refractive index portion pairs 60 constitute a two-dimensional lattice photonic crystal.

[0031] As shown in FIG. 1, the second semiconductor layer 70 is provided on the photonic crystal 40. The second semiconductor layer 70 is provided on the second layer 44. The second semiconductor layer 70 is provided between the second layer 44 and the contact layer 80. The second semiconductor layer 70 is, for example, a p-type AlGaAs layer doped with C. The first semiconductor layer 20 and the second semiconductor layer 70 are cladding layers having a function of confining light in the light emitting layer 30. Note that the second semiconductor layer 70 may be provided continuously and integrally with the second layer 44.

[0032] In the light emitting device 100, a pin diode is formed by the p-type second semiconductor layer 70, the p-type first layer 42 and the second layer 44, the i-type light emitting layer 30, and the n-type first semiconductor layer 20. In the light emitting device 100, when a forward bias voltage of the pin diode is applied between the first electrode 90 and the second electrode 92, current is injected into the light emitting layer 30 and recombination of electrons and holes occurs in the light emitting layer 30. Light emission occurs due to this recombination. The light generated in the light emitting layer 30 propagates in the in-plane direction, forms a standing wave due to the effect of the photonic crystal 40, and undergoes gain in the light emitting layer 30 to cause laser oscillation. Then, the light emitting device 100 emits the +1st order diffracted light and the -1st order diffracted light as laser light in the stacking direction. The light traveling toward the second electrode 92 side is reflected by the second electrode 92. Thereby, the light emitting device 100 can emit light from the substrate 10 side.

[0033] Note that the "in-plane direction" is a direction orthogonal to the stacking direction of the first semiconductor layer 20 and the light-emitting layer 30. Although not shown in the figure, a reflective layer may be provided between the second semiconductor layer 70 and the contact layer 80. The reflective layer is, for example, a DBR (Distributed Bragg Reflector) layer. The reflective layer reflects the light generated in the light-emitting layer 30 toward the substrate 10 side.

[0034] The contact layer 80 is provided on the second semiconductor layer 70. The contact layer 80 is provided between the second semiconductor layer 70 and the second electrode 92. The impurity concentration of the contact layer 80 is higher than that of the second semiconductor layer 70. The contact layer 80 is, for example, a p-type GaAs layer doped with C.

[0035] The first electrode 90 is provided under the substrate 10. The substrate 10 may be in ohmic contact with the first electrode 90. The first electrode 90 is electrically connected to the first semiconductor layer 20 via the substrate 10. The material of the first electrode 90 is, for example, a metal such as Au, Ge, Ni or an alloy thereof. The first electrode 90 is one of the electrodes for injecting current into the light-emitting layer 30.

[0036] An opening 91 is formed in the first electrode 90. The opening 91 penetrates the first electrode 90. In a plan view, the opening 91 overlaps with the second electrode 92. The light generated in the light-emitting layer 30 is emitted through the opening 91.

[0037] The second electrode 92 is provided on the contact layer 80. The contact layer 80 may be in ohmic contact with the second electrode 92. The second electrode 92 is electrically connected to the second semiconductor layer 70 via the contact layer 80. The planar shape of the second electrode 92 is, for example, a square. The material of the second electrode 92 is, for example, a metal such as Au, Ge, Ni or an alloy thereof. The second electrode 92 is the other electrode for injecting current into the light-emitting layer 30.

[0038] The light-emitting device 100 is applied to, for example, a laser processing device. As the laser processing device are, for example, a metal 3D printer using a selective laser melting (SLM) method, a laser cleaner that removes rust on metal with laser light, a laser annealing device that heats the surface of metal or resin with laser light, and the like. The light-emitting device 100 is further applied to, for example, a LiDAR (Light Detection And Ranging) sensing system for autonomous driving of automobiles and autonomous running of robots.

[0039] 2. Manufacturing method of the light-emitting device Next, a manufacturing method of the light-emitting device 100 according to the present embodiment will be described with reference to the drawings. FIG. 3 is a flowchart for explaining the manufacturing method of the light-emitting device 100 according to the present embodiment. FIG. 4 is a cross-sectional view schematically showing the manufacturing process of the light-emitting device 100 according to the present embodiment. FIG. 5 is a plan view schematically showing the manufacturing process of the light-emitting device 100 according to the present embodiment. FIGS. 6 to 10 are cross-sectional views schematically showing the manufacturing process of the light-emitting device 100 according to the present embodiment. FIG. 11 is a plan view schematically showing the manufacturing process of the light-emitting device 100 according to the present embodiment. FIGS. 12 and 13 are cross-sectional views schematically showing the manufacturing process of the light-emitting device 100 according to the present embodiment. FIG. 14 is a plan view schematically showing the manufacturing process of the light-emitting device 100 according to the present embodiment. FIGS. 15 to 19 are cross-sectional views schematically showing the manufacturing process of the light-emitting device 100 according to the present embodiment.

[0040] As shown in FIGS. 3 and 4, a first semiconductor layer 20a, a light-emitting layer 30a, and a first layer 42a are grown in this order on a substrate 10a (step S1). Specifically, the first semiconductor layer 20a, the light-emitting layer 30a, and the first layer 42a are epitaxially grown by a metal organic chemical vapor deposition (MOCVD) method.

[0041] The substrate 10a, the first semiconductor layer 20a, the light-emitting layer 30a, and the first layer 42 are cut in step S15 described later to become the substrate 10, the first semiconductor layer 20, the light-emitting layer 30, and the first layer 42 shown in FIG. 1, respectively.

[0042] The substrate 10a is, for example, a wafer as shown in FIG. 5. The substrate 10a has a central portion 12 including the center and a peripheral portion 14 located at the periphery in plan view. The central portion 12 and the peripheral portion 14 are spaced apart from each other. The distance between the central portion 12 and the peripheral portion 14 is, for example, larger than 1 / 3 of the diameter of the wafer. FIGS. 4 and 6 to 19 show the central portion 12 and the peripheral portion 14 of the substrate 10a.

[0043] As shown in FIG. 6, a mask layer 110 is formed on the first layer 42a, and a first resist layer 120 is formed on the mask layer 110 (step S2). The mask layer 110 is formed, for example, by a plasma CVD (Chemical Vapor Deposition) method. The mask layer 110 is, for example, a silicon nitride layer. The first resist layer 120 is formed, for example, by a spin coating method.

[0044] The substrate 10a warps due to heat in, for example, the step of crystal growth (step S1) of the first semiconductor layer 20a, the light-emitting layer 30a, and the first layer 42a. Therefore, as shown in FIG. 6, for example, the thickness T1 of the first resist layer 120 in the peripheral portion 14 is smaller than the thickness T2 of the first resist layer 120 in the central portion 12.

[0045] As shown in FIG. 7, a plurality of openings 122 and 124 are formed in the first resist layer 120 (step S3). The openings 122 and 124 are formed by exposure and development. The exposure may be performed using an electron beam lithography apparatus. The opening 122 is an opening for forming the hole 52. The opening 124 is an opening for forming the hole 54. Since the thickness T1 of the first resist layer 120 in the peripheral portion 14 is smaller than the thickness T2 of the first resist layer 120 in the central portion 12, the diameter D1 of the opening 122 in the peripheral portion 14 is at the center portion 12 It becomes larger than the diameter E1 of the opening 122 in the center portion 12. Similarly, the diameter of the opening 124 in the peripheral portion 14 becomes larger than the diameter of the opening 124 in the center portion 12. Note that the openings 122 and 124 may be formed using a nanoimprint method.

[0046] As shown in FIG. 8, using the first resist layer 120 as a mask, the mask layer 110 is etched to form a plurality of openings 112 and 114 in the mask layer 110 (step S4). The etching is, for example, dry etching using a fluorine-based gas. The opening 112 is an opening that overlaps the opening 122 in plan view. The opening 114 is an opening that overlaps the opening 124 in plan view. Since the diameter D1 of the opening 122 in the peripheral portion 14 is larger than the diameter E1 of the opening 122 in the center portion 12, the diameter D2 of the opening 112 in the peripheral portion 14 becomes larger than the diameter E2 of the opening 112 in the center portion 12. Similarly, the diameter of the opening 114 in the peripheral portion 14 becomes larger than the diameter of the opening 114 in the center portion 12. In the illustrated example, the diameters D1 and D2 are the same as each other. The diameters E1 and E2 are the same as each other.

[0047] As shown in FIG. 9, the first resist layer 120 is removed (step S5). The removal of the first resist layer 120 is performed, for example, by ashing.

[0048] As shown in FIG. 10, using the mask layer 110 as a mask, the first layer 42a is etched to form a plurality of holes 52 and 54 in the first layer 42a (step S6). The etching is, for example, dry etching using a chlorine-based gas.

[0049] In this project, as shown in Fig. 11, holes 52 are formed such that the diameter D3 of the holes 52 in the peripheral portion 14 is larger than the diameter E3 of the holes 52 in the central portion 12. Further, holes 54 are formed such that the diameter D4 of the holes 54 in the peripheral portion 14 is larger than the diameter E4 of the holes 54 in the central portion 12. Since the diameter D3 of the opening 112 in the peripheral portion 14 is larger than the diameter E3 of the opening 112 in the central portion 12, the diameter D3 of the holes 52 in the peripheral portion 14 is larger than the diameter E3 of the holes 52 in the central portion 12. Similarly, the diameter D4 of the holes 54 in the peripheral portion 14 is larger than the diameter E4 of the holes 54 in the central portion 12. In the example shown in Fig. 10, the diameters D2 and D3 are the same as each other. The diameters E2 and E3 are the same as each other.

[0050] As shown in Fig. 11, among the plurality of holes 52, the first hole 52a is a hole 52 provided in the peripheral portion 14, for example, the hole 52 located at the outermost periphery among the plurality of holes 52. Among the plurality of holes 54, the second hole 54a is a hole 54 provided in the peripheral portion 14, for example, the hole 54 located at the outermost periphery among the plurality of holes 54. Among the plurality of holes 52, the third hole 52b is a hole 52 provided in the central portion 12, for example, the hole 52 closest to the center of the substrate 10a. Among the plurality of holes 54, the fourth hole 54b is a hole 54 provided in the central portion 12, for example, the hole 54 closest to the center of the substrate 10a.

[0051] The second hole 54a is formed at a first distance L1 from the first hole 52a in the first direction. The third hole 52b is formed at a second distance L2 from the first hole 52a in the second direction. The fourth hole 54b is formed at a third distance L3 from the third hole 52b in the first direction. In the illustrated example, the first direction is a direction inclined by 45° with respect to the -X axis direction and the +Y axis direction when viewed from the Z axis direction. The second direction is a direction intersecting the first direction and is the +X axis direction.

[0052] The first distance L1 is the distance between the center of the first hole 52a and the center of the second hole 54a. The second distance L2 is the distance between the center of the first hole 52a and the center of the third hole 52b. The second distance L2 is greater than the first distance L1. The third distance L3 is the distance between the center of the third hole 52b and the center of the fourth hole 54b. The third distance L3 is smaller than the second distance L2. In the illustrated example, the first distance L1 and the third distance L3 are the same as each other. The fourth hole 54b is formed at a distance of the third distance L3 from the second hole 54a in the +X axis direction.

[0053] As shown in FIG. 12, the mask layer 110 is removed (step S7). The removal of the mask layer 110 is performed, for example, by wet etching. Next, the surface of the first layer 42a is cleaned by thermal cleaning or the like.

[0054] As shown in FIG. 13, the second layer 44a is grown crystallographically in the holes 52 and 54, a low refractive index portion 62 is formed in the hole 52, and a low refractive index portion 64 is formed in the hole 54 (step S8). Specifically, the second layer 44a is epitaxially grown by the MOCVD method. The second layer 44a is formed on the first layer 42a. By this step, the photonic crystal 40a is formed. The second layer 44a and the photonic crystal 40a are cut in step S15 described later to become the second layer 44 and the photonic crystal 40 shown in FIG. 1, respectively.

[0055] The growth temperature of the second layer 44a is, for example, 550°C or higher and 650°C or lower, preferably 570°C or higher and 640°C or lower, and more preferably 600°C or higher and 625°C or lower. For the crystal growth of the second layer 44a, a first gas for supplying a group III element and a second gas for supplying a group V element are used. The first gas includes, for example, trimethylgallium (TMG) which is a raw material of Ga and trimethylaluminum (TMA) which is a raw material of Al. The second gas includes, for example, tertiarybutylarsine (TBA) which is a raw material of As. The ratio of the flow rate of the second gas to the flow rate of the first gas is, for example, 10 or more and 30 or less, preferably 15 or more and 25 or less, and more preferably 17 or more and 23 or less.

[0056] In this process, the flow rates of the first gas and the second gas supplied to hole 52 are less than the flow rates of the first gas and the second gas supplied above hole 52. Therefore, the lateral growth rate of the second layer 44a at hole 52 is smaller than the lateral growth rate of the second layer 44a above hole 52. Thus, the area above hole 52 is blocked by the second layer 44a first. As a result, the first gas and the second gas are no longer supplied to hole 52. Consequently, a low refractive index portion 62, which is a void, is formed. The same applies to the low refractive index portion 64 provided in hole 54.

[0057] In this process, as shown in FIG. 14, the crystal growth of the second layer 44a is grown such that the difference between the diameter D3 of hole 52 in the peripheral portion 14 and the diameter D5 of the low refractive index portion 62 in the peripheral portion 14 is larger than the difference between the diameter E3 of hole 52 in the central portion 12 and the diameter E5 of the low refractive index portion 62 in the central portion 12. Further, the crystal growth of the second layer 44a is grown such that the difference between the diameter D4 of hole 54 in the peripheral portion 14 and the diameter D6 of the low refractive index portion 64 in the peripheral portion 14 is larger than the difference between the diameter E4 of hole 54 in the central portion 12 and the diameter E6 of the low refractive index portion 64 in the central portion 12.

[0058] In this process, the area above hole 52 in the peripheral portion 14 is blocked by the second layer 44a later than the area above hole 52 in the central portion 12. That is, when the area above hole 52 in the central portion 12 is blocked by the second layer 44a, the area above hole 52 in the peripheral portion 14 is not yet blocked by the second layer 44a. Therefore, more of the first gas and the second gas are supplied to hole 52 in the peripheral portion 14 than to hole 52 in the central portion 12. By exhibiting the shadow effect in which more gas is supplied to the hole 52 with the larger diameter in this way, the difference between the diameter D3 and the diameter D5 can be made larger than the difference between the diameter E3 and the diameter E5. The same applies to hole 54.

[0059] Among the plurality of low refractive index portions 62, the first low refractive index portion 62a is the low refractive index portion 62 provided in the first hole 52a. Among the plurality of low refractive index portions 64, the second low refractive index portion 64a is the low refractive index portion 64 provided in the second hole 54a. Among the plurality of low refractive index portions 62, the third low refractive index portion 62b is the low refractive index portion 62 provided in the third hole 52b. Among the plurality of low refractive index portions 64, the fourth low refractive index portion 64b is the low refractive index portion 64 provided in the fourth hole 54b.

[0060] The first low refractive index portion 62a and the second low refractive index portion 64a form the first low refractive index portion pair 60a among the plurality of low refractive index portion pairs 60. The third low refractive index portion 62b and the fourth low refractive index portion 64b form the second low refractive index portion pair 60b among the plurality of low refractive index portion pairs 60.

[0061] In the illustrated example, the diameter D3 is the maximum width of the hole 52a. The diameter E3 is the maximum width of the hole 52b. The diameter D4 is the maximum width of the hole 54a. The diameter E4 is the maximum width of the hole 54b. The diameter D5 is the maximum width of the low refractive index portion 62a. The diameter E5 is the maximum width of the low refractive index portion 62b. The diameter D6 is the maximum width of the low refractive index portion 64a. The diameter E6 is the maximum width of the low refractive index portion 64b. The diameter D5 is smaller than the diameter D3. The diameter E5 is smaller than the diameter E3. The diameter D6 is smaller than the diameter D4. The diameter E6 is smaller than the diameter E4.

[0062] Note that the diameters D1 to D6 and the diameters E1 to E6 are measured by, for example, a TEM (Transmission Electron Microscope) or an SEM (Scanning Electron Microscope).

[0063] As shown in FIG. 15, on the second layer 44a, the second semiconductor layer 70a and the contact layer 80a are crystal-grown in this order (step S9). Specifically, the second semiconductor layer 70a and the contact layer 80a are epitaxially grown by the MOCVD method. The second semiconductor layer 70a and the contact layer 80a are cut in step S15 described later to become the second semiconductor layer 70 and the contact layer 80 shown in FIG. 1, respectively.

[0064] As shown in FIG. 16, a second resist layer 130 is formed on the contact layer 80a (step S10). The second resist layer 130 is formed, for example, by a spin coating method. Although not shown, the thickness of the second resist layer 130 in the peripheral portion 14 may be smaller than the thickness of the second resist layer 130 in the central portion 12.

[0065] As shown in FIG. 17, an opening 132 is formed in the second resist layer 130 (step S11). The opening 132 is formed by exposure and development. The exposure may be performed using an electron beam lithography apparatus.

[0066] As shown in FIG. 18, an electrode material 92a to be the second electrode 92 is formed on the contact layer 80a and on the second resist layer 130 (step S12). The electrode material 92a is formed, for example, by a vacuum evaporation method or a sputtering method.

[0067] As shown in FIG. 19, the second resist layer 130 is removed, and the second electrode 92 is formed by a lift-off method (step S13).

[0068] Next, a first electrode 90 is formed under the substrate 10 (step S14). The first electrode 90 is formed, for example, by a vacuum evaporation method after mirror-polishing the lower surface of the substrate 10. Then, the first electrode 90 is patterned to form an opening 91. The patterning is performed, for example, by photolithography and etching.

[0069] Through the above steps, a structure 100a having a plurality of light-emitting devices 100 can be manufactured.

[0070] Next, the structure 100a is cut to separate the light-emitting devices 100 into individual pieces (step S15). Examples of the cutting method include blade dicing and laser dicing.

[0071] Through the above steps, the light-emitting device 100 shown in FIG. 1 can be manufactured.

[0072] 3. Function and Effect In the method for manufacturing the photonic crystal 40a, the method includes a step of forming a first layer 42a, and forming, in the first layer 42a, a first hole 52a, a second hole 54a that is separated from the first hole 52a by a first distance L1 in a first direction, a third hole 52b that is separated from the first hole 52a by a second distance L2 that is greater than the first distance L1 in a second direction intersecting the first direction, and a fourth hole 54b that is separated from the third hole 52b by a third distance L3 that is smaller than the second distance L2 in the first direction. Further, in the method for manufacturing the photonic crystal 40a, crystal growth of a second layer 44a is performed on the first hole 52a, the second hole 54a, the third hole 52b, and the fourth hole 54b, and a first low refractive index portion 62a having a refractive index lower than that of the first layer 42a is formed in the first hole 52a, a second low refractive index portion 64a having a refractive index lower than that of the first layer 42a is formed in the second hole 54a, a third low refractive index portion 62b having a refractive index lower than that of the first layer 42a is formed in the third hole 52b, and a fourth low refractive index portion 64b having a refractive index lower than that of the first layer 42a is formed in the fourth hole 54b. In the step of forming the first hole 52a, the second hole 54a, the third hole 52b, and the fourth hole 54b, the first hole 52a and the third hole 52b are formed such that the diameter D3 of the first hole 52a is larger than the diameter E3 of the third hole 52b, and the second hole 54a and the fourth hole 54b are formed such that the diameter D4 of the second hole 54a is larger than the diameter E4 of the fourth hole 54b. In the step of forming the first low refractive index portion 62a, the second low refractive index portion 64a, the third low refractive index portion 62b, and the fourth low refractive index portion 64b, the second layer 44a is crystal-grown such that the difference between the diameter D3 of the first hole 52a and the diameter D5 of the first low refractive index portion 62a is larger than the difference between the diameter E3 of the third hole 52b and the diameter E5 of the third low refractive index portion 62b, and the difference between the diameter D4 of the second hole 54a and the diameter D6 of the second low refractive index portion 64a is larger than the difference between the diameter E4 of the fourth hole 54b and the diameter E6 of the fourth low refractive index portion 64b.

[0073] Therefore, in the method for manufacturing the photonic crystal 40a, for example, compared with the case where the difference between the diameter D3 and the diameter D5 in the crystal growth of the second layer is the same as the difference between the diameter E3 and the diameter E5, the difference between the diameter D5 of the first low refractive index portion 62a and the diameter E5 of the third low refractive index portion 62b can be reduced. Further, for example, compared with the case where the difference between the diameter D4 and the diameter D6 in the crystal growth of the second layer is the same as the difference between the diameter E4 and the diameter E6, the difference between the diameter D6 of the second low refractive index portion 64a and the diameter E6 of the fourth low refractive index portion 64b can be reduced. Thereby, the variation in the light confinement coefficient can be reduced. Therefore, it is possible to manufacture the photonic crystal 40a that can exhibit a stable light confinement effect.

[0074] In the method for manufacturing the photonic crystal 40a, the diameter D3 of the first hole 52a is smaller than the diameter D4 of the second hole 54a, and the diameter E3 of the third hole 52b is smaller than the diameter E4 of the fourth hole 54b. Therefore, in the method for manufacturing the photonic crystal 40a, the asymmetry in the unit lattice can be increased, and the radiation of light in the vertical direction can be enhanced.

[0075] In the method for manufacturing the photonic crystal 40a, the first low refractive index portion 62a and the second low refractive index portion 64a form the first low refractive index portion pair 60a, the third low refractive index portion 62b and the fourth low refractive index portion 64b form the second low refractive index portion pair 60b, and the first low refractive index portion pair 60a and the second low refractive index portion pair 60b form a unit lattice. Therefore, in the method for manufacturing the photonic crystal 40a, it is possible to form the photonic crystal 40a having a double unit lattice.

[0076] In the method for manufacturing the photonic crystal 40a, the refractive index of the first layer 42a and the refractive index of the second layer 44a are different from each other. Therefore, in the method for manufacturing the photonic crystal 40a, it is easy to adjust the refractive index of the photonic crystal 40a.

[0077] In the method for manufacturing the photonic crystal 40a, the second layer 44a is crystal-grown by the MOCVD method. Therefore, in the method for manufacturing the photonic crystal 40a, the shadow effect can be exhibited during the crystal growth of the second layer 44a.

[0078] In the method for manufacturing the photonic crystal 40a, the growth temperature of the second layer 44a is 550°C or higher and 650°C or lower. Therefore, in the method for manufacturing the photonic crystal 40a, the shadow effect can be exhibited during the crystal growth of the second layer 44a. Further, since the growth temperature of the second layer 44a is 550°C or higher, crystal defects are less likely to occur in the second layer 44a. Further, since the growth temperature of the second layer 44a is 650°C or lower, the shapes of the holes 52a, 52b, 54a, and 54b are less likely to collapse due to heat.

[0079] In the method for manufacturing the photonic crystal 40a, the second layer 44a is a group III-V semiconductor layer, and in the crystal growth of the second layer 44a, the ratio of the flow rate of the second gas that supplies a group V element to the flow rate of the first gas that supplies a group III element is 10 or more and 30 or less. Therefore, in the method for manufacturing the photonic crystal 40a, the shadow effect can be exhibited during the crystal growth of the second layer 44a.

[0080] In the method for manufacturing the photonic crystal 40a, the first low refractive index portion 62a, the second low refractive index portion 64a, the third low refractive index portion 62b, and the fourth low refractive index portion 64b are voids. Therefore, in the method for manufacturing the photonic crystal 40a, the refractive indices of the low refractive index portions 62a, 62b, 64b, and 64b can be lowered.

[0081] In the crystal growth of the second layer, the upper parts of the first hole 52a, the second hole 54a, the third hole 52b, and the fourth hole 54b are blocked by the second layer 44a, so that the first gas and the second gas are not supplied to the first hole 52a, the second hole 54a, the third hole 52b, and the fourth hole 54b, and voids are formed. The upper part of the first hole 52a is blocked later than the upper part of the third hole 52b, and the upper part of the second hole 54a is blocked later than the upper part of the fourth hole 54b. Therefore, in the method for manufacturing the photonic crystal 40, the difference between the diameter D3 of the first hole 52a and the diameter D5 of the first low refractive index portion 62a can be made larger than the difference between the diameter E3 of the third hole 52b and the diameter E5 of the third low refractive index portion 62b. Furthermore, the difference between the diameter D4 of the second hole 54a and the diameter D6 of the second low refractive index portion 64a can be made larger than the difference between the diameter E4 of the fourth hole 54b and the diameter E6 of the fourth low refractive index portion 64b.

[0082] The method for manufacturing the light emitting device 100 includes a method for manufacturing the photonic crystal 40a. As described above, in the method for manufacturing the photonic crystal 40a, the variation in the light confinement factor can be reduced. As shown in the following formula (1), the light confinement factor Γ is related to the threshold current density J th and has an impact. Therefore, in the method for manufacturing the light emitting device 100, the variation in the threshold current density J th can be reduced.

[0083]

Number

[0084] In formula (1), J0 and g0 are fixed values. η spon is the internal quantum efficiency during spontaneous emission. d is the thickness of the light emitting layer 30. α int is the internal loss. α / / is the in-plane loss. α ⊥ is the radiative loss. R is the power reflectivity. θ is the phase shift. g is the gain, which is represented by the above formula (2). In formula (2), J nom is the normalized current density.

[0085] In the above description, an example where the first hole and the second hole are holes in the peripheral portion 14 and the third hole and the fourth hole are holes in the central portion 12 has been described. However, if the diameter of the first hole is larger than the diameter of the third hole and the diameter of the second hole is larger than the diameter of the fourth hole, the positions of the first hole, the second hole, the third hole, and the fourth hole in plan view are not particularly limited.

[0086] Also, in the above description, an example where the diameters of the first hole, the second hole, the third hole, and the fourth hole are due to the thickness of the first resist layer 120 has been described. However, if the diameter of the first hole is larger than the diameter of the third hole and the diameter of the second hole is larger than the diameter of the fourth hole, the diameters of the first hole, the second hole, the third hole, and the fourth hole may be due to other conditions rather than the thickness of the first resist layer 120.

[0087] 4. Modification Example of Light-Emitting Device Next, a light-emitting device according to a modification example of the present embodiment will be described with reference to the drawings. FIG. 20 is a cross-sectional view schematically showing a light-emitting device 200 according to a modification example of the present embodiment. Hereinafter, in the light-emitting device 200 according to the modification example of the present embodiment, members having the same functions as the constituent members of the light-emitting device 100 according to the above-described present embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0088] In the above-described light-emitting device 100, as shown in FIG. 1, the depths of the hole 52 and the hole 54 were the same.

[0089] On the other hand, in the light-emitting device 200, as shown in FIG. 20, the hole 52 is shallower than the hole 54. By changing the etching time when forming the holes 52 and 54, the depths of the holes 52 and 54 can be changed. Note that, as shown in FIG. 21, the hole 52 may be deeper than the hole 54.

[0090] 5. Experimental Example 5.1. Preparation of Samples On a GaAs substrate, a GaAs layer was crystal-grown by the MOCVD method. Next, a SiN layer was formed on the GaAs layer by the plasma CVD method. Next, a resist layer was formed on the SiN layer by the spin coating method. Next, the resist layer was exposed with an electron beam lithography apparatus and further developed. Next, using the resist layer as a mask, the SiN layer was dry-etched with a fluorine-based gas. Next, the resist layer was removed by ashing. Next, using the SiN layer as a mask, the GaAs layer was dry-etched with a chlorine-based gas to form a plurality of holes in the GaAs layer. Next, the SiN layer was removed by wet etching. Next, the surface of the GaAs layer was cleaned by thermal cleaning.

[0091] Next, an AlGaAs layer was crystal-grown on the GaAs layer by the MOCVD method. The growth temperature of the AlGaAs layer was set to 600 °C. In the crystal growth of the AlGaAs layer, a first gas containing TMG and TMA and a second gas containing TBA were used. The flow rate of the second gas with respect to the flow rate of the first gas was set to 20. The crystal growth of the AlGaAs layer was performed so that the composition ratio of Al and Ga was 1:1.

[0092] Through the above steps, a sample was fabricated.

[0093] 5.2. Cross-sectional Observation After processing the above sample with a FIB (Focused Ion Beam) processing apparatus, the cross-section was observed by STEM (Scanning Transmission Electron Microscope). As the FIB processing apparatus, "Helios" manufactured by JEOL Ltd. was used. The dose amount of the FIB processing apparatus was set to 0.7 μs. As the STEM, "Talos" manufactured by Thermo Scienti fic was used. The acceleration voltage of the STEM was set to 200 kV.

[0094] The cross-sectional observation was performed on three regions of the sample, namely, the first region, the second region, and the third region. The first region, the second region, and the third region are regions with different positions in plan view.

[0095] Figure 22 shows the HAADF (High-Angle Annular Dark Field)-STEM image and the BF (Bright-Field)-STEM image of the first region. Figure 23 shows the HAADF-STEM image and the BF-STEM image of the second region. Figure 24 shows the HAADF-STEM image and the BF-STEM image of the third region.

[0096] As shown in Figure 22, in the first region, voids were confirmed in the holes. In the first region, the diameter W1 of the holes was 127 mm. The diameter W2 of the voids was 91 mm. The pitch of the holes was 261 nm. The thickness W3 of the AlGaAs layer on the side surface of the holes was 18 nm. Note that W3 = (W1 - W2) / 2.

[0097] As shown in Figure 23, in the second region, voids were confirmed in the holes. In the second region, the diameter W1 of the holes was 164 mm. The diameter W2 of the voids was 118 mm. The pitch of the holes was 264 nm. The thickness W3 was 23 nm.

[0098] As shown in Figure 24, in the third region, voids were confirmed in the holes. In the third region, the diameter W1 of the holes was 182 mm. The diameter W2 of the voids was 133 mm. The pitch of the holes was 264 nm. The thickness W3 was 24.5 nm.

[0099] Figure 25 is a graph showing the relationship between the diameter of the holes, the pitch of the holes, the diameter of the voids, and the thickness of the AlGaAs layer on the side surface of the holes in the first region, the second region, and the third region.

[0100] As shown in Figures 22 to 25, the larger the diameter W1 of the holes, the larger the thickness W3 of the AlGaAs layer on the side surface of the holes. Therefore, according to the crystal growth of the AlGaAs layer shown in this experimental example, it was found that the shadow effect can be expressed. In the first region, the second region, and the third region, the pitch of the holes hardly changed.

[0101] The above-described embodiments and modified examples are merely examples and are not limited thereto. For example, it is also possible to appropriately combine each embodiment and each modified example.

[0102] The present invention includes configurations that are substantially the same as the configurations described in the embodiments, for example, configurations having the same functions, methods, and results, or configurations having the same objectives and effects. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. For example, a material containing GaN may be crystallized on a GaN substrate to form a first semiconductor layer 20, a light-emitting layer 30, a first layer 42, a second layer 44, and a second semiconductor layer 70 made of the material containing GaN. The present invention also includes configurations that exhibit the same operational effects as the configurations described in the embodiments or configurations that can achieve the same objectives. The present invention also includes configurations in which known technologies are added to the configurations described in the embodiments.

[0103] The following contents are derived from the above-described embodiments and modified examples.

[0104] One aspect of a method for manufacturing a photonic crystal is a step of forming a first layer, forming, in the first layer, a first hole, a second hole spaced apart from the first hole by a first distance in a first direction, and a third hole spaced apart from the first hole by a second distance greater than the first distance in a second direction intersecting the first direction and a step of forming a fourth hole spaced apart from the third hole by a third distance smaller than the second distance in the first direction, crystal-growing a second layer in the first hole, the second hole, the third hole, and the fourth hole to form a first low-refractive-index portion having a refractive index lower than that of the first layer in the first hole, a second low-refractive-index portion having a refractive index lower than that of the first layer in the second hole, a third low-refractive-index portion having a refractive index lower than that of the first layer in the third hole, and a fourth low-refractive-index portion having a refractive index lower than that of the first layer in the fourth hole, including in the step of forming the first hole, the second hole, the third hole, and the fourth hole, Form the first hole and the third hole such that the diameter of the first hole is larger than the diameter of the third hole. Form the second hole and the fourth hole such that the diameter of the second hole is larger than the diameter of the fourth hole. In the step of forming the first low refractive index portion, the second low refractive index portion, the third low refractive index portion, and the fourth low refractive index portion. Grow the second layer such that the difference between the diameter of the first hole and the diameter of the first low refractive index portion is larger than the difference between the diameter of the third hole and the diameter of the third low refractive index portion, and the difference between the diameter of the second hole and the diameter of the second low refractive index portion is larger than the difference between the diameter of the fourth hole and the diameter of the fourth low refractive index portion.

[0105] According to this method for manufacturing a photonic crystal, a photonic crystal capable of exhibiting a stable light confinement effect can be manufactured.

[0106] In one aspect of the method for manufacturing a photonic crystal. The diameter of the first hole is smaller than the diameter of the second hole. The diameter of the third hole may be smaller than the diameter of the fourth hole.

[0107] According to this method for manufacturing a photonic crystal, the asymmetry in the unit cell can be increased, and the radiation of light in the vertical direction can be enhanced.

[0108] In one aspect of the method for manufacturing a photonic crystal. The first low refractive index portion and the second low refractive index portion form a first pair. The third low refractive index portion and the fourth low refractive index portion form a second pair. The first pair and the second pair may form a unit cell.

[0109] According to this method for manufacturing a photonic crystal, a photonic crystal having a double unit cell can be formed.

[0110] In one aspect of the method for manufacturing a photonic crystal. The refractive index of the first layer and the refractive index of the second layer may be different from each other.

[0111] According to this method for manufacturing a photonic crystal, it is easy to adjust the refractive index of the photonic crystal.

[0112] In one aspect of the method for manufacturing a photonic crystal, The second layer may be crystal-grown by the MOCVD method.

[0113] According to this method for manufacturing a photonic crystal, a shadow effect can be exhibited in the crystal growth of the second layer.

[0114] In one aspect of the method for manufacturing a photonic crystal, The growth temperature of the second layer may be 550°C or higher and 650°C or lower.

[0115] According to this method for manufacturing a photonic crystal, a shadow effect can be exhibited in the crystal growth of the second layer.

[0116] In one aspect of the method for manufacturing a photonic crystal, The second layer is a group III-V semiconductor layer, In the crystal growth of the second layer, the ratio of the flow rate of the second gas supplying a group V element to the flow rate of the first gas supplying a group III element may be 10 or more and 30 or less.

[0117] According to this method for manufacturing a photonic crystal, a shadow effect can be exhibited in the crystal growth of the second layer.

[0118] In one aspect of the method for manufacturing a photonic crystal, The first low refractive index portion, the second low refractive index portion, the third low refractive index portion, and the fourth low refractive index portion may be voids.

[0119] According to this method for manufacturing a photonic crystal, the refractive indices of the first low refractive index portion, the second low refractive index portion, the third low refractive index portion, and the fourth low refractive index portion can be reduced.

[0120] In one aspect of the method for manufacturing the photonic crystal, In the crystal growth of the second layer, the upper parts of the first hole, the second hole, the third hole, and the fourth hole are blocked by the second layer, so that the first gas and the second gas are not supplied to the first hole, the second hole, the third hole, and the fourth hole, and the voids are formed. The upper part of the first hole is blocked later than the upper part of the third hole. The upper part of the second hole may be blocked later than the upper part of the fourth hole.

[0121] According to this method for manufacturing a photonic crystal, the difference between the diameter of the first hole and the diameter of the first low refractive index portion can be made larger than the difference between the diameter of the third hole and the diameter of the third low refractive index portion. Further, the difference between the diameter of the second hole and the diameter of the second low refractive index portion can be made larger than the difference between the diameter of the fourth hole and the diameter of the fourth low refractive index portion.

[0122] One aspect of the method for manufacturing a light emitting device is having one aspect of the method for manufacturing the photonic crystal.

[0123] According to this method for manufacturing a light emitting device, the variation in the threshold current density can be reduced.

Description of Reference Numerals

[0124] 2... Side, 4... Bottom surface, 10, 10a... Substrate, 12... Central part, 14... Peripheral part, 20, 20a... First semiconductor layer, 30, 30a... Light-emitting layer, 40, 40a... Photonic crystal, 42, 42a... First layer, 44, 44a... Second layer, 50... Hole pair, 52... Hole, 52a... First hole, 52b... Third hole, 54... Hole, 54a... Second hole, 54b... Fourth hole, 60... Low refractive index part pair, 60a... First low refractive index part pair, 60b... Second low refractive index part pair, 62a... First low refractive index part, 62b... Third low refractive index part, 64a... Second low refractive index part, 64b... Fourth low refractive index part, 70, 70a... Second semiconductor layer, 80, 80a... Contact layer, 90... First electrode, 91... Opening, 92... Second electrode, 92a... Electrode material, 100... Light-emitting device, 100a... Structure, 110... Mask layer, 112... Opening, 120... First resist layer, 122... Opening, 130... Second resist layer, 132... Opening , 200... Light-emitting device

Claims

1. A step of forming a first layer; In the first layer, a first hole, a second hole spaced apart from the first hole by a first distance in a first direction, a third hole spaced apart from the first hole by a second distance greater than the first distance in a second direction intersecting the first direction, and a fourth hole spaced apart from the third hole by a third distance smaller than the second distance in the first direction are formed; A second layer is crystallized in the first hole, the second hole, the third hole, and the fourth hole, a first low refractive index portion having a refractive index lower than that of the first layer is formed in the first hole, a second low refractive index portion having a refractive index lower than that of the first layer is formed in the second hole, a third low refractive index portion having a refractive index lower than that of the first layer is formed in the third hole, and a fourth low refractive index portion having a refractive index lower than that of the first layer is formed in the fourth hole; including In the step of forming the first hole, the second hole, the third hole, and the fourth hole, The first hole and the third hole are formed such that the diameter of the first hole is larger than the diameter of the third hole; The second hole and the fourth hole are formed such that the diameter of the second hole is larger than the diameter of the fourth hole; In the step of forming the first low refractive index portion, the second low refractive index portion, the third low refractive index portion, and the fourth low refractive index portion, The second layer is crystallized such that the difference between the diameter of the first hole and the diameter of the first low refractive index portion is larger than the difference between the diameter of the third hole and the diameter of the third low refractive index portion, and the difference between the diameter of the second hole and the diameter of the second low refractive index portion is larger than the difference between the diameter of the fourth hole and the diameter of the fourth low refractive index portion. A method for manufacturing a photonic crystal.

2. In claim 1, The diameter of the first hole is smaller than the diameter of the second hole; The diameter of the third hole is smaller than the diameter of the fourth hole. A method for manufacturing a photonic crystal.

3. In claim 1, The first low refractive index portion and the second low refractive index portion form a first pair; The third low refractive index portion and the fourth low refractive index portion form a second pair, The first pair and the second pair form a unit cell, a method for manufacturing a photonic crystal.

4. In claim 1, The refractive index of the first layer and the refractive index of the second layer are different from each other, a method for manufacturing a photonic crystal.

5. In claim 1, The second layer is crystal-grown by the MOCVD method, a method for manufacturing a photonic crystal.

6. In claim 5, The growth temperature of the second layer is 550°C or higher and 650°C or lower, a method for manufacturing a photonic crystal.

7. In claim 6, The second layer is a group III-V semiconductor layer, In the crystal growth of the second layer, the ratio of the flow rate of the second gas supplying a group V element to the flow rate of the first gas supplying a group III element is 10 or more and 30 or less, a method for manufacturing a photonic crystal method.

8. In claim 7, The first low refractive index portion, the second low refractive index portion, the third low refractive index portion, and the fourth low refractive index portion are voids, a method for manufacturing a photonic crystal.

9. In claim 8, In the crystal growth of the second layer, the upper parts of the first hole, the second hole, the third hole, and the fourth hole are blocked by the second layer, so that the first gas and the second gas are not supplied to the first hole, the second hole, the third hole, and the fourth hole, and the voids are formed, The upper part of the first hole is blocked later than the upper part of the third hole, The upper part of the second hole is blocked later than the upper part of the fourth hole, a method for manufacturing a photonic crystal.

10. A method for manufacturing a light-emitting device, comprising the method for manufacturing a photonic crystal according to any one of Claims 1 to 9.

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