Light-emitting device and projector

Abstract

To provide a light emitting device that can reduce scattering of light generated in a luminous layer in first holes.SOLUTION: A light emitting device has a substrate, a laminate that has a plurality of columnar parts, and an electrode that is provided on the laminate on the opposite side of the substrate. The plurality of columnar parts each has a luminous layer. The electrode is provided with a plurality of first holes. The plurality of columnar parts forms a first photonic crystal. The electrode forms a second photonic crystal. The first photonic crystal and the second photonic crystal are optically coupled to each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a light-emitting device and a projector. [Background technology]

[0002] Semiconductor lasers are expected to be the next generation of high-brightness light sources. In particular, semiconductor lasers that incorporate nanocolumns are expected to be able to emit high-power light with a narrow beam angle due to the photonic crystal effect of the nanocolumns.

[0003] For example, Patent Document 1 describes that in a light-emitting device having multiple columnar sections each having a light-emitting layer and an electrode provided on the multiple columnar sections, by providing multiple holes in the electrode, light absorption can be reduced by the amount of the holes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-7136 Summary of the Invention [Problem to be solved by the invention]

[0005] When holes are provided in the electrode as described above, it is desirable that the light generated in the light-emitting layer is not scattered by the holes, since scattering of light by the holes increases light loss. [Means for solving the problem]

[0006] One aspect of the light emitting device according to the present invention is A substrate; a laminate having a plurality of columnar portions; an electrode provided on the laminate opposite to the substrate; and each of the plurality of columnar portions has a light-emitting layer; The electrode is provided with a plurality of first holes, the plurality of columns constitute a first photonic crystal, the electrode constitutes a second photonic crystal; The first photonic crystal and the second photonic crystal are optically coupled.

[0007] One aspect of the projector according to the present invention is The light emitting device has one aspect. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a light-emitting device according to an embodiment of the present invention. [Figure 2] FIG. 3 is a plan view schematically showing a columnar portion and a first hole of the light emitting device according to the embodiment. [Figure 3] 5A to 5C are cross-sectional views schematically showing the manufacturing process of the light emitting device according to the embodiment. [Figure 4] 5A to 5C are cross-sectional views schematically showing the manufacturing process of the light emitting device according to the embodiment. [Figure 5] 5A to 5C are cross-sectional views schematically showing the manufacturing process of the light emitting device according to the embodiment. [Figure 6] FIG. 10 is a cross-sectional view schematically showing a light emitting device according to a first modified example of the present embodiment. [Figure 7] FIG. 10 is a plan view schematically showing a columnar portion and a first hole of a light emitting device according to a first modified example of the present embodiment. [Figure 8] FIG. 10 is a plan view schematically showing a columnar portion and a first hole of a light emitting device according to a first modified example of the present embodiment. [Figure 9] FIG. 10 is a cross-sectional view schematically showing a light emitting device according to a second modified example of the present embodiment. [Figure 10] FIG. 10 is a plan view schematically showing a columnar portion and a first hole of a light emitting device according to a third modified example of the present embodiment. [Figure 11] FIG. 10 is a plan view schematically showing a columnar portion and a first hole of a light emitting device according to a third modified example of the present embodiment. [Figure 12] FIG. 10 is a plan view schematically showing a columnar portion and a first hole of a light emitting device according to a third modified example of the present embodiment. [Figure 13]FIG. 10 is a cross-sectional view schematically showing a light emitting device according to a fourth modified example of the embodiment. [Figure 14] FIG. 10 is a cross-sectional view schematically showing a light emitting device according to a fifth modified example of the embodiment. [Figure 15] FIG. 11 is a plan view schematically showing a columnar portion, a second electrode, and a first hole of a light emitting device according to a fifth modified example of the embodiment. [Figure 16] FIG. 10 is a cross-sectional view schematically showing a light emitting device according to a sixth modified example of the embodiment. [Figure 17] FIG. 1 is a diagram schematically showing a projector according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present invention as defined in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

[0010] 1. Light-emitting device 1.1. Overall structure First, the light emitting device according to the present 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 the present embodiment. Fig. 2 is a plan view schematically showing the light emitting device 100 according to the present embodiment. Fig. 1 is a cross-sectional view taken along line II-II in Fig. 2. Figs. 1 and 2 also illustrate an X-axis, a Y-axis, and a Z-axis as three mutually orthogonal axes.

[0011] 1, the light emitting device 100 includes, for example, a substrate 10, a laminate 20, a first electrode 40, and a second electrode 42. The light emitting device 100 is, for example, a semiconductor laser.

[0012] The substrate 10 is, for example, a Si substrate, a GaN substrate, a sapphire substrate, or a SiC substrate.

[0013] The laminate 20 is provided on a substrate 10. In the illustrated example, the laminate 20 is provided on the substrate 10. The laminate 20 has, for example, a buffer layer 22 and a plurality of columnar sections 30. For convenience, components other than the columnar sections 30 are not shown in FIG. 2.

[0014] In this specification, in the stacking direction of the laminate 20 (hereinafter also simply referred to as the "stacking direction"), when the light emitting layer 34 of the columnar section 30 is used as a reference, the direction from the light emitting layer 34 toward the second semiconductor layer 36 of the columnar section 30 is referred to as the "upper" direction, and the direction from the light emitting layer 34 toward the first semiconductor layer 32 of the columnar section 30 is referred to as the "lower" direction. A direction perpendicular to the stacking direction is also referred to as an "in-plane direction." The "stacking direction of the laminate 20" refers to the stacking direction of the first semiconductor layer 32 and the light emitting layer 34, and is the direction of the perpendicular line N to the substrate 10. Specifically, the "perpendicular line N to the substrate 10" is a perpendicular line to the top surface of the substrate 10. In the illustrated example, the stacking direction is the Z-axis direction.

[0015] The buffer layer 22 is provided on the substrate 10. The buffer layer 22 is, for example, an n-type GaN layer doped with Si. A mask layer 24 for growing the columnar section 30 is provided on the buffer layer 22. The mask layer 24 is, for example, a titanium layer, a silicon oxide layer, or the like. Examples include a silicon layer, a titanium oxide layer, and an aluminum oxide layer.

[0016] The columnar portion 30 is provided on the buffer layer 22. The columnar portion 30 has a columnar shape that protrudes upward from the buffer layer 22. In other words, the columnar portion 30 protrudes upward from the substrate 10 via the buffer layer 22. The columnar portion 30 is also called, for example, a nanocolumn, a nanowire, a nanorod, or a nanopillar. The planar shape of the columnar portion 30 is, for example, a polygon such as a hexagon, or a circle. In the example shown in FIG. 2, the planar shape of the columnar portion 30 is a regular hexagon.

[0017] The diameter of the columnar section 30 is, for example, 50 nm or more and 500 nm or less. By setting the diameter of the columnar section 30 to 500 nm or less, it is possible to obtain a light-emitting layer 34 with high-quality crystals and reduce strain inherent in the light-emitting layer 34. This allows the light generated in the light-emitting layer 34 to be amplified with high efficiency.

[0018] The "diameter of the columnar portion 30" refers to the diameter when the columnar portion 30 has a circular planar shape, and refers to the diameter of the smallest encompassing circle when the columnar portion 30 has a non-circular planar shape. For example, when the columnar portion 30 has a polygonal planar shape, the diameter of the columnar portion 30 refers to the diameter of the smallest circle that includes the polygon, and when the columnar portion 30 has an ellipse planar shape, the diameter of the smallest circle that includes the ellipse. The same applies to the "diameter of the first hole 44" described below.

[0019] A plurality of columnar sections 30 are provided. The interval between adjacent columnar sections 30 is, for example, 1 nm or more and 500 nm or less. The plurality of columnar sections 30 are arranged in a predetermined direction at a predetermined period T1 when viewed from the stacking direction. The plurality of columnar sections 30 are arranged in, for example, a triangular lattice pattern or a square lattice pattern. In the example shown in FIG. 2, the plurality of columnar sections 30 are arranged in a regular triangular lattice pattern. The plurality of columnar sections 30 can exhibit the effect of a photonic crystal.

[0020] The "period T1 of the columnar portion 30" is the distance between the centers C1 of the columnar portions 30 adjacent to each other in a predetermined direction. When the planar shape of the columnar portion 30 is a circle, the "center C1 of the columnar portion 30" is the center of the circle. When the planar shape of the columnar portion 30 is a non-circular shape, the "center C1 of the columnar portion 30" is the center of the smallest circle that contains the polygon. For example, when the planar shape of the columnar portion 30 is a polygon, the center C1 of the columnar portion 30 is the center of the smallest circle that contains the polygon. When the planar shape of the columnar portion 30 is an ellipse, the center C1 of the smallest circle that contains the ellipse.

[0021] As shown in FIG. 1, the columnar section 30 includes, for example, a first semiconductor layer 32, a light emitting layer 34, and a second semiconductor layer 36.

[0022] The first semiconductor layer 32 is provided on the buffer layer 22. The first semiconductor layer 32 is provided between the substrate 10 and the light emitting layer 34. The first semiconductor layer 32 is a semiconductor layer of a first conductivity type. The first semiconductor layer 32 is, for example, an n-type GaN layer doped with Si.

[0023] The light emitting layer 34 is provided between the first semiconductor layer 32 and the second semiconductor layer 36. The light emitting layer 34 generates light when a current is injected into it. The light emitting layer 34 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 InGaN layer. The barrier layer is, for example, a GaN layer. The light emitting layer 34 has an MQW (Multiple Quantum Well) structure composed of the well layer and the barrier layer.

[0024] There is no particular limitation on the number of well layers and barrier layers that make up the light-emitting layer 34. For example, only one well layer may be provided, in which case the light-emitting layer 34 has an SQW (Single Quantum Well) structure.

[0025] The second semiconductor layer 36 is provided on the light emitting layer 34. The second semiconductor layer 36 is provided between the light emitting layer 34 and the second electrode 42. The second semiconductor layer 36 is a semiconductor layer of a second conductivity type different from the first conductivity type. The second semiconductor layer 36 is, for example, a p-type GaN layer doped with Mg. The first semiconductor layer 32 and the second semiconductor layer 36 are cladding layers that have the function of confining light in the light emitting layer 34.

[0026] Although not shown, an OCL (Optical Confinement Layer) made of an i-type InGaN layer and a GaN layer may be provided at least one between the first semiconductor layer 32 and the light emitting layer 34 and between the light emitting layer 34 and the second semiconductor layer 36. The second semiconductor layer 36 may also have an EBL (Electron Blocking Layer) made of a p-type AlGaN layer.

[0027] The first electrode 40 is provided on the buffer layer 22. The buffer layer 22 may be in ohmic contact with the first electrode 40. The first electrode 40 is electrically connected to the first semiconductor layer 32. In the illustrated example, the first electrode 40 is electrically connected to the first semiconductor layer 32 via the buffer layer 22. The first electrode 40 is one of the electrodes for injecting current into the light-emitting layer 34. The first electrode 40 may be, for example, an electrode formed by laminating a Cr layer, a Ni layer, and an Au layer in this order from the buffer layer 22 side.

[0028] The second electrode 42 is provided on the side of the laminate 20 opposite to the substrate 10. The second electrode 42 is provided on the second semiconductor layer 36. The second semiconductor layer 36 may be in ohmic contact with the second electrode 42. The second electrode 42 is the other electrode for injecting current into the light-emitting layer 34. For example, ITO (Indium Tin Oxide) or the like is used as the second electrode 42.

[0029] Although the above description has been given of an InGaN-based light emitting layer 34, various material systems that can emit light when a current is injected depending on the wavelength of the emitted light can be used for the light emitting layer 34. For example, semiconductor materials such as AlGaN-based, AlGaAs-based, InGaAs-based, InGaAsP-based, InP-based, GaP-based, and AlGaP-based materials can be used.

[0030] 1.2. First and second photonic crystals The plurality of columnar sections 30 constitute a first photonic crystal 50. In the example shown in Fig. 1, the first photonic crystal 50 is constituted by the plurality of columnar sections 30 and gaps between adjacent columnar sections 30.

[0031] A plurality of first holes 44 are provided in the second electrode 42. The first holes 44, for example, penetrate the second electrode 42. In the example shown in the figure, the first holes 44 penetrate the second electrode 42 in the stacking direction. The first holes 44 are through-holes. In the example shown in the figure, the first holes 44 are voids. Although not shown, the first holes 44 may be filled with a material having a lower refractive index than the second electrode 42. In the example shown in FIG. 2, the planar shape of the first holes 44 is a circle. The shape of the first holes 44 may be an ellipse or a polygon. In the example shown in FIG. 2, the plurality of first holes 44 have the same size.

[0032] 2, the diameter of the first holes 44 is smaller than the diameter of the columnar portions 30. The diameter of the first holes 44 is equal to or less than the period T1 of the columnar portions 30. The diameter of the first holes 44 is equal to or less than the wavelength of the light generated in the light-emitting layer 34. The distance between adjacent first holes 44 is equal to or less than the wavelength of the light generated in the light-emitting layer 34.

[0033] The first holes 44 do not overlap with the columnar portions 30 when viewed from the stacking direction. The outer edges of the first holes 44 do not intersect with the outer edges of the columnar portion 30. In the example shown in the figure, six first holes 44 are provided around one columnar portion 30 at equal intervals.

[0034] 2, two adjacent first holes 44 aligned in the Y-axis direction constitute one first hole group 46. In the example shown, the multiple first hole groups 46 are arranged in a regular triangular lattice pattern. The period T2 of the first hole groups 46 is the same as the period T1 of the columnar portion 30.

[0035] The "period T2 of the first hole group 46" is the distance between the centers C2 of the first hole groups 46 adjacent to each other in a predetermined direction. The "center C2 of the first hole group 46" is the center of the smallest encompassing circle that includes the two first holes 44 that make up the first hole group 46. In the illustrated example, the "center C2 of the first hole group 46" is the midpoint of the line segment connecting the center of one of the two first holes 44 that make up the first hole group 46 to the center of the other first hole 44.

[0036] The second electrode 42 constitutes a second photonic crystal 52. In the example shown in FIG. 1, the second photonic crystal 52 is constituted by the second electrode 42 and a plurality of first holes 44 provided in the second electrode 42.

[0037] The first photonic crystal 50 and the second photonic crystal 52 are optically coupled. Here, "the first photonic crystal 50 and the second photonic crystal 52 are optically coupled" refers to a state in which the first photonic crystal 50 and the second photonic crystal 52 influence each other, and a state in which the first photonic crystal 50 and the second photonic crystal 52 exhibit a single photonic crystal effect. When the first photonic crystal 50 and the second photonic crystal 52 are optically coupled, the waveguide mode in the first photonic crystal 50 and the waveguide mode in the second photonic crystal 52 are coupled. In other words, laser oscillation in the same oscillation mode is obtained in the first photonic crystal 50 and the second photonic crystal 52. In the light-emitting device 100, the first photonic crystal 50 and the second photonic crystal 52 are optically coupled to form an optical confinement mode.

[0038] The first photonic crystal 50 and the second photonic crystal 52 have, for example, the same type of lattice arrangement and are arranged at the same period. The first photonic crystal 50 and the second photonic crystal 52 have, for example, the same in-plane arrangement orientation. Therefore, in the light emitting device 100, the first photonic crystal 50 and the second photonic crystal 52 can be optically coupled to reduce scattering of light in the first hole 44.

[0039] In the illustrated example, the plurality of columnar portions 30 constituting the first photonic crystal 50 and the plurality of first hole groups 46 constituting the second photonic crystal 52 are both arranged in a regular triangular lattice pattern. Furthermore, the period T1 of the plurality of columnar portions 30 constituting the first photonic crystal 50 and the period T2 of the plurality of first hole groups 46 constituting the second photonic crystal 52 are the same.

[0040] Furthermore, the in-plane arrangement orientation A of the multiple columnar portions 30 constituting the first photonic crystal 50 and the in-plane arrangement orientation B of the multiple first hole groups 46 constituting the second photonic crystal 52 coincide with each other. The in-plane arrangement orientation A of the multiple columnar portions 30 is the direction in which the columnar portions 30 are lined up in a planar view. The in-plane arrangement orientation B of the multiple first hole groups 46 is the direction in which the first hole groups 46 are lined up in a planar view. "The arrangement orientation A and the arrangement orientation B coincide with each other" refers to a state in which the direction of a predetermined row of columnar portions 30 coincides with the direction of a row of first hole groups 46 corresponding to the predetermined row, i.e., a state in which there is no rotational misalignment between the row of columnar portions 30 and the corresponding row of first hole groups 46.

[0041] In this way, in the light emitting device 100, the plurality of columnar sections 30 and the plurality of first hole groups 46 are of the same type. Since the first photonic crystal 50 and the second photonic crystal 52 have the same type of lattice arrangement, have the same period, and have the same in-plane arrangement orientation, the first photonic crystal 50 and the second photonic crystal 52 have the same type of lattice arrangement, have the same period, and have the same in-plane arrangement orientation.

[0042] In the light-emitting device 100, the relative positional relationship between the first photonic crystal 50 and the second photonic crystal 52 is constant within the plane. Therefore, the first photonic crystal 50 and the second photonic crystal 52 are optically coupled to each other, and can exhibit the effect of a single photonic crystal. For example, if the relative positional relationship between the two is not constant and a positional misalignment occurs within the plane, this positional misalignment will change the photonic band, preventing laser oscillation in a single mode and preventing an ideal light trapping effect.

[0043] The configuration of the first photonic crystal 50 and the second photonic crystal 52 is not limited to the above example, as long as the first photonic crystal 50 and the second photonic crystal 52 can be optically coupled to obtain the effect of reducing scattering of light in the first hole 44.

[0044] In the light-emitting device 100, a p-type second semiconductor layer 36, an i-type light-emitting layer 34 that is not intentionally doped with impurities, and an n-type first semiconductor layer 32 form a p-i diode. When a forward bias voltage of the p-i diode is applied between the first electrode 40 and the second electrode 42, a current is injected into the light-emitting layer 34, causing electrons and holes to recombine in the light-emitting layer 34. This recombination generates light. The light generated in the light-emitting layer 34 propagates in the in-plane direction through the first semiconductor layer 32 and the second semiconductor layer 36, forms a standing wave due to the effect of the optically coupled first photonic crystal 50 and second photonic crystal 52, and receives gain in the light-emitting layer 34 to produce laser oscillation. The light-emitting device 100 then emits the +1st-order diffracted light and the −1st-order diffracted light as laser light in the stacking direction.

[0045] Although not shown, a reflective layer may be provided between the substrate 10 and the buffer layer 22 or below the substrate 10. The reflective layer is, for example, a DBR (Distributed Bragg Reflector) layer. The reflective layer can reflect light generated in the light-emitting layer 34, and the light-emitting device 100 can emit light only from the second electrode 42 side.

[0046] 1.3. Effects In the light emitting device 100, each of the multiple columnar sections 30 has a light emitting layer 34, the second electrode 42 is provided with multiple first holes 44, the multiple columnar sections 30 form a first photonic crystal 50, the second electrode 42 forms a second photonic crystal 52, and the first photonic crystal 50 and the second photonic crystal 52 are optically coupled. In the light emitting device 100, the first photonic crystal 50 and the second photonic crystal 52 are coupled to each other to produce a single photonic crystal effect, thereby reducing scattering of light generated in the light emitting layer 34 at the first holes 44.

[0047] In the light emitting device 100, each of the plurality of first holes 44 penetrates the second electrode 42. Therefore, in the light emitting device 100, the average refractive index in the in-plane direction in the portion of the light emitting device 100 where the second electrode 42 is provided can be made smaller than in a case where the first holes do not penetrate the second electrode 42. This makes it possible to increase the optical confinement coefficient.

[0048] In the light emitting device 100, when viewed from the stacking direction, each of the multiple first holes 44 does not overlap with the multiple columnar portions 30. Therefore, in the light emitting device 100, when the first holes 44 are formed by etching, damage to the columnar portions 30 due to etching can be suppressed.

[0049] 2. Light-emitting device manufacturing method Next, a method for manufacturing the light emitting device 100 according to this embodiment will be described with reference to the drawings. Figures 3 to 5 are cross-sectional views that schematically show the manufacturing process for the light emitting device 100 according to this embodiment.

[0050] 3, a buffer layer 22 is epitaxially grown on a substrate 10. Examples of methods for epitaxial growth include MOCVD (Metal Organic Chemical Vapor Deposition) and MBE (Molecular Beam Epitaxy).

[0051] Next, a mask layer 24 is formed on the buffer layer 22. The mask layer 24 is formed by film formation using, for example, an electron beam evaporation method or a sputtering method, and patterning. The patterning is performed by, for example, electron beam lithography and dry etching.

[0052] 4, the first semiconductor layer 32, the light-emitting layer 34, and the second semiconductor layer 36 are epitaxially grown in this order on the buffer layer 22 using the mask layer 24 as a mask. Examples of methods for epitaxial growth include MOCVD and MBE. This process allows the formation of multiple columnar sections 30.

[0053] 5, a second electrode 42 is formed on the second semiconductor layer 36. The second electrode 42 is formed by, for example, a sputtering method or a vacuum deposition method. In the step of forming the second electrode 42, oblique deposition may be performed so that the electrode material does not adhere to the side surface of the columnar section 30.

[0054] 1, the second electrode 42 is patterned to form a plurality of first holes 44. The patterning is performed by, for example, electron beam lithography and dry etching.

[0055] Next, the first electrode 40 is formed on the buffer layer 22. The first electrode 40 is formed by, for example, a sputtering method, a vacuum deposition method, or the like. Note that the order of the step of forming the first electrode 40 and the step of forming the second electrode 42 is not particularly limited.

[0056] Through the above steps, the light emitting device 100 can be manufactured.

[0057] 3. Modifications of the Light-Emitting Device 3.1. First Variant Next, a light emitting device 200 according to a first modified example of this embodiment will be described with reference to the drawings. Fig. 6 is a cross-sectional view schematically showing the light emitting device 200 according to the first modified example of this embodiment. Fig. 7 is a plan view schematically showing the columnar section 30 and the first hole 44 of the light emitting device 200 according to the first modified example of this embodiment. Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 7.

[0058] Hereinafter, in the light emitting device 200 according to the first modified example of this embodiment, components having the same functions as the components of the light emitting device 100 according to this embodiment described above will be denoted by the same reference numerals, and detailed description thereof will be omitted. This also applies to the light emitting devices according to the second to sixth modified examples of this embodiment described later.

[0059] In the light emitting device 100 described above, as shown in FIGS. 1 and 2, the first holes 44 do not overlap with the columnar sections 30 when viewed in the stacking direction.

[0060] In contrast, in the light emitting device 200, as shown in FIGS. 6 and 7, the first holes 44 overlap with the columnar portions 30 when viewed from the stacking direction. The outer edges of the first holes 44 are located inside the outer edges of the columnar portions 30. In the illustrated example, when viewed from the stacking direction, all of the first holes 44 overlap with the columnar portions 30. The center of the first hole 44 and the center of the columnar portion 30, for example, coincide with each other.

[0061] 6, the plurality of columnar portions 30 constituting the first photonic crystal 50 and the plurality of first holes 44 constituting the second photonic crystal 52 are both arranged in a regular triangular lattice pattern. Furthermore, the period of the plurality of columnar portions 30 constituting the first photonic crystal 50 is the same as the period of the plurality of first holes 44 constituting the second photonic crystal 52. Furthermore, the in-plane arrangement orientation of the plurality of columnar portions 30 constituting the first photonic crystal 50 is the same as the in-plane arrangement orientation of the plurality of first holes 44 constituting the second photonic crystal 52. Therefore, in the light emitting device 200, the first photonic crystal 50 and the second photonic crystal 52 can be optically coupled.

[0062] In the light emitting device 200, when viewed from the stacking direction, each of the multiple first holes 44 overlaps with the multiple columnar sections 30. Therefore, in the light emitting device 200, the refractive index directly above the light emitting layer 34, where light is easily trapped, can be lowered compared to, for example, a case where the first holes do not overlap with the columnar sections, and the light confinement coefficient can be increased.

[0063] In the light emitting device 200, the first holes 44 are formed, for example, by wet etching the second electrode 42. Therefore, damage caused by etching to the columnar section 30 can be reduced compared to when the first holes 44 are formed by dry etching.

[0064] 8, the light emitting device 200 may be provided with first holes 44 that overlap with the columnar section 30 and first holes 44 that do not overlap with the columnar section 30 when viewed from the stacking direction. In the example shown in Fig. 8, the multiple first holes 44 have an arrangement that combines the first holes 44 shown in Fig. 2 and the first holes 44 shown in Fig. 7.

[0065] 8, a first hole 44 overlapping with the columnar section 30 and two first holes 44 adjacent to the first hole 44 overlapping with the columnar section 30, which are located in the −X-axis direction of the first hole 44 overlapping with the columnar section 30 and adjacent to each other in the Y-axis direction, constitute one first hole group 46. In the example shown in FIG. 8, the average refractive index in the in-plane direction in the portion where the second electrode 42 of the light emitting device 200 is provided can be reduced compared to, for example, the example shown in FIG. 2 and the example shown in FIG. 7.

[0066] 8, the plurality of columnar portions 30 constituting the first photonic crystal 50 and the plurality of first hole groups 46 constituting the second photonic crystal 52 are both arranged in a regular triangular lattice pattern. Furthermore, the period of the plurality of columnar portions 30 constituting the first photonic crystal 50 is the same as the period of the plurality of first hole groups 46 constituting the second photonic crystal 52. Furthermore, the in-plane arrangement orientation of the plurality of columnar portions 30 constituting the first photonic crystal 50 is the same as the in-plane arrangement orientation of the plurality of first hole groups 46 constituting the second photonic crystal 52. Therefore, the first photonic crystal 50 and the second photonic crystal 52 can be optically coupled.

[0067] 3.2. Second Variant Next, a light emitting device 300 according to a second modified example of this embodiment will be described with reference to the drawings. Fig. 9 is a cross-sectional view that schematically shows the light emitting device 300 according to the second modified example of this embodiment.

[0068] In the light emitting device 100 described above, the first holes 44 penetrate the second electrode 42 as shown in FIG.

[0069] 9, the first holes 44 in the light emitting device 300 do not penetrate the second electrode 42. The first holes 44 are bottomed holes. Furthermore, in the light emitting device 300, the first holes 44 overlap with the columnar portions 30 when viewed in the stacking direction, similar to the light emitting device 200 shown in FIGS. 6 and 7.

[0070] The second electrode 42 has a first layer 42a in which the first holes 44 are not provided, and a second layer 42b in which the first holes 44 are provided. The first layer 42a is provided on the plurality of columnar sections 30. The first layer 42a defines bottom surfaces 45 of the first holes 44. The first layer 42a is provided between the plurality of columnar sections 30 and the second layer 42b. The second layer 42b is provided on the first layer 42a. The first holes 44 may be formed by dry etching or wet etching.

[0071] The optical distance between the first photonic crystal 50 and the second photonic crystal 52 is 3λ or less, where λ is the oscillation wavelength. The optical distance is the so-called optical path length, which is the distance that light travels multiplied by the refractive index. By arranging the first photonic crystal 50 and the second photonic crystal 52 at a distance of 3λ or less, the first photonic crystal 50 and the second photonic crystal 52 can be strongly optically coupled. In the illustrated example, the optical distance between the first photonic crystal 50 and the second photonic crystal 52 can be determined from the thickness and refractive index of the first layer 42a.

[0072] In the light emitting device 300, each of the plurality of first holes 44 does not penetrate the second electrode 42. Therefore, in the light emitting device 300, damage to the columnar section 30 caused by etching for forming the first holes 44 can be suppressed.

[0073] 3.3. Third Variant Next, a light emitting device 400 according to a third modified example of this embodiment will be described with reference to the drawings. Fig. 10 is a plan view schematically showing the columnar section 30 and the first hole 44 of the light emitting device 400 according to the third modified example of this embodiment.

[0074] In the light emitting device 100 described above, as shown in FIG. 2, the first holes 44 do not overlap with the columnar sections 30 when viewed in the stacking direction.

[0075] In contrast, in the light emitting device 400, as shown in Fig. 10, the first holes 44 overlap with multiple columnar portions 30 when viewed from the stacking direction. In the example shown, one first hole 44 overlaps with three columnar portions 30 when viewed from the stacking direction. The multiple first holes 44 are arranged in a regular triangular lattice pattern. The first holes 44 are formed, for example, by wet etching the second electrode 42.

[0076] Three columnar sections 30 overlapping one first hole 44 constitute a columnar section group 130. The columnar section groups 130 constituting the first photonic crystal 50 and the first holes 44 constituting the second photonic crystal 52 are both arranged in a regular triangular lattice pattern. Furthermore, the period of the columnar section groups 130 constituting the first photonic crystal 50 is the same as the period of the first holes 44 constituting the second photonic crystal 52. Furthermore, the in-plane arrangement orientation of the columnar section groups 130 constituting the first photonic crystal 50 is the same as the in-plane arrangement orientation B of the first holes 44 constituting the second photonic crystal 52. Therefore, in the light emitting device 400, the first photonic crystal 50 and the second photonic crystal 52 can be optically coupled.

[0077] As long as the first photonic crystal 50 and the second photonic crystal 52 can be optically coupled, there is no particular limitation on the number of columnar portions 30 with which the first holes 44 overlap when viewed from the stacking direction. 11, one first hole 44 may overlap four columnar portions 30. The four columnar portions 30 overlapping one first hole 44 constitute a columnar portion group 130.

[0078] 12 , a columnar section group 130 consisting of four columnar sections 30 may be overlapped with a first hole group 46 consisting of three first holes 44 when viewed from the stacking direction. The plurality of columnar section groups 130 constituting the first photonic crystal 50 and the plurality of first hole groups 46 constituting the second photonic crystal 52 are both arranged in a regular triangular lattice pattern. Furthermore, the period of the plurality of columnar section groups 130 constituting the first photonic crystal 50 is the same as the period of the plurality of first hole groups 46 constituting the second photonic crystal 52. Furthermore, the in-plane arrangement orientation of the plurality of columnar section groups 130 constituting the first photonic crystal 50 is consistent with the in-plane arrangement orientation B of the plurality of first hole groups 46 constituting the second photonic crystal 52. Therefore, the first photonic crystal 50 and the second photonic crystal 52 can be optically coupled.

[0079] 3.4. Fourth Variant Next, a light emitting device 500 according to a fourth modification of this embodiment will be described with reference to the drawings. Fig. 13 is a cross-sectional view that schematically shows the light emitting device 500 according to the fourth modification of this embodiment.

[0080] In the light emitting device 100 described above, as shown in FIG. 1, a gap is provided between the adjacent columnar portions 30.

[0081] In contrast, in the light emitting device 500, as shown in FIG. 13, the laminate 20 has a light propagation layer 26 provided between adjacent columns.

[0082] The light propagation layer 26 is provided on the mask layer 24. The light propagation layer 26 is made of, for example, a dielectric material. Specifically, the light propagation layer 26 is a silicon oxide layer. More specifically, the light propagation layer 26 is a SiO2 layer. Light generated in the light emitting layer 34 propagates in the in-plane direction through the light propagation layer 26. The first photonic crystal 50 is made up of a plurality of columnar sections 30 and the light propagation layer 26 between adjacent columnar sections 30.

[0083] The light propagation layer 26 has second holes 28. The second holes 28 are connected to the first holes 44. A plurality of second holes 28 are provided. The number of second holes 28 is, for example, the same as the number of first holes 44. The bottom surfaces 29 of the second holes 28 are provided between the second semiconductor layers 36 of adjacent columnar sections 30. The second holes 28 are not provided between the light emitting layers 34 of adjacent columnar sections 30. The second holes 28 do not reach the light emitting layers 34 in the stacking direction. The bottom surfaces 29 are defined by the second semiconductor layers 36. In the illustrated example, the second holes 28 are voids. Although not illustrated, the second holes 28 may be filled with a material having a lower refractive index than the light propagation layer 26. Alternatively, the second holes 28 may not be provided.

[0084] The light propagation layer 26 is formed by, for example, a chemical vapor deposition (CVD) method or a spin coating method. The second holes 28 are formed by patterning the light propagation layer 26. The second holes 28 are formed, for example, continuously with the first holes 44.

[0085] In the light emitting device 500, the laminate 20 has a light propagation layer 26 provided between adjacent columnar sections 30 of the plurality of columnar sections 30, and the light propagation layer 26 is provided with a second hole 28, which communicates with one of the plurality of first holes 44, and the bottom surface 29 of the second hole 28 is located between the second semiconductor layers 36 of the adjacent columnar sections 30 of the plurality of columnar sections 30. Therefore, in the light emitting device 500, the average refractive index in the in-plane direction in the portion where the second hole 28 of the light emitting device 500 is provided can be made lower than in a case where the second hole is not provided. This This increases the optical confinement coefficient. Furthermore, since the light propagation layer 26 is provided between the adjacent columnar sections 30, it is possible to prevent the electrode material from adhering to the side surfaces of the columnar sections 30 when forming the second electrode 42.

[0086] 3.5. Fifth Variant Next, a light emitting device 600 according to a fifth modified example of this embodiment will be described with reference to the drawings. Fig. 14 is a cross-sectional view schematically showing the light emitting device 600 according to the fifth modified example of this embodiment. Fig. 15 is a plan view schematically showing the columnar section 30, the second electrode 42, and the first hole 44 of the light emitting device 600 according to the fifth modified example of this embodiment. Fig. 14 is a cross-sectional view taken along line XIV-XIV in Fig. 15.

[0087] In the light emitting device 100, the second electrode 42 had a film shape that was continuous in the in-plane direction, as shown in Fig. 1. In the light emitting device 100, the second electrode 42 was patterned to form the first holes 44.

[0088] In contrast, in the light emitting device 600, the first holes 44 are formed without patterning the second electrode 42. In the light emitting device 600, the second electrode 42 is formed under conditions that make it easier for the second electrode 42 to inherit the shape of the columnar section 30, compared to the light emitting device 100. This makes it difficult for the second electrode 42 to grow in the in-plane direction, and as shown in Figures 14 and 15, the first holes 44 are formed in the second electrode 42. For example, by forming the second electrode 42 by sputtering and adjusting the sputtering temperature, it is possible to form a second electrode 42 that is difficult to grow in the in-plane direction.

[0089] In this way, in the light emitting device 600, the first holes 44 can be formed without patterning the second electrode 42.

[0090] 3.6. Sixth Variant Next, a light emitting device 700 according to a sixth modified example of this embodiment will be described with reference to the drawings. Figure 16 is a cross-sectional view that schematically shows the light emitting device 700 according to the sixth modified example of this embodiment.

[0091] In the light emitting device 100 described above, the diameter of the columnar section 30 in the first semiconductor layer 32 is the same as the diameter of the columnar section 30 in the light emitting layer 34, as shown in FIG.

[0092] 16 , in the light emitting device 700, the diameter of the first semiconductor layer 32 of the columnar section 30 is smaller than the diameter of the light emitting layer 34 of the columnar section 30. This makes it possible to increase the difference between the average refractive index in the in-plane direction in the portion of the light emitting device 700 where the first semiconductor layer 32 is provided and the average refractive index in the in-plane direction in the portion of the light emitting device 700 where the light emitting layer 34 is provided, compared to when the diameter of the first semiconductor layer 32 of the columnar section 30 is the same as the diameter of the light emitting layer 34 of the columnar section 30. This makes it possible to increase the optical confinement coefficient.

[0093] In the light-emitting device 700, the columnar section 30 has an optical confinement layer 38. The optical confinement layer 38 is provided on the first semiconductor layer 32. The optical confinement layer 38 is provided between the first semiconductor layer 32 and the light-emitting layer 34. In the example shown, the optical confinement layer 38 has a portion where the diameter of the columnar section 30 gradually increases from the first semiconductor layer 32 toward the light-emitting layer 34. The optical confinement layer 38 is composed of, for example, an i-type InGaN layer and an i-type GaN layer. The In composition of the InGaN layer that constitutes the optical confinement layer 38 is smaller than the In composition of the InGaN layer that constitutes the light-emitting layer 34. The optical confinement layer 38 is an OCL that confines light in the light-emitting layer 34.

[0094] The light emitting device 700 has a dummy columnar section 730 spaced apart from the second electrode 42. The dummy columnar section 730 does not emit light. The configuration of the dummy columnar section 730 is, for example, the same as the configuration of the columnar section 30. For example, a plurality of dummy columnar sections 730 are provided. The dummy columnar sections 730 are grown, for example, in the same process as the columnar section 30.

[0095] An insulating layer 740 is provided between the dummy columnar section 730 and the second electrode 42. The insulating layer 740 surrounds the dummy columnar section 730 when viewed from the stacking direction. The insulating layer 740 covers the dummy columnar section 730. The insulating layer 740 is provided on the mask layer 24. The insulating layer 740 is, for example, a silicon oxide layer. More specifically, the insulating layer 740 is an SiO2 layer. The insulating layer 740 is formed by, for example, a CVD method or a spin coating method.

[0096] In the illustrated example, the first electrode 40 is provided in an engraved portion of the buffer layer 22. For example, a portion of the buffer layer 22 is etched, and the first electrode 40 is formed in the etched portion of the buffer layer 22.

[0097] An electrode pad 750 is provided on the second electrode 42. When viewed from the stacking direction, the electrode pad 750 overlaps the dummy columnar section 730. The electrode pad 750 is made of, for example, titanium, gold, etc. A wire bonding (not shown) is connected to the electrode pad 750. The electrode pad 750 is formed by, for example, a CVD method or a sputtering method.

[0098] 4. Projector Next, a projector according to this embodiment will be described with reference to the drawings. Fig. 17 is a diagram schematically showing a projector 800 according to this embodiment.

[0099] The projector 800 includes, for example, a light emitting device 100 as a light source.

[0100] Projector 800 has a housing (not shown) and red light source 100R, green light source 100G, and blue light source 100B that are provided in the housing and emit red light, green light, and blue light, respectively. For convenience, red light source 100R, green light source 100G, and blue light source 100B are simplified in FIG. 17.

[0101] The projector 800 further includes, within the housing, a first optical element 802R, a second optical element 802G, a third optical element 802B, a first light modulation device 804R, a second light modulation device 804G, a third light modulation device 804B, and a projection device 808. The first light modulation device 804R, the second light modulation device 804G, and the third light modulation device 804B are, for example, transmissive liquid crystal light valves. The projection device 808 is, for example, a projection lens.

[0102] Light emitted from red light source 100R is incident on first optical element 802R. The light emitted from red light source 100R is collected by first optical element 802R. Note that first optical element 802R may have a function other than collecting light. The same applies to second optical element 802G and third optical element 802B, which will be described later.

[0103] The light collected by the first optical element 802R is incident on the first light modulation device 804R. The first light modulation device 804R modulates the incident light in accordance with image information. The projection device 808 then enlarges the image formed by the first light modulation device 804R and projects it onto a screen 810.

[0104] The light emitted from green light source 100G is incident on second optical element 802G. The light emitted from green light source 100G is collected by second optical element 802G.

[0105] The light collected by the second optical element 802G is incident on the second light modulation device 804G. The second light modulation device 804G modulates the incident light in accordance with image information. The projection device 808 then enlarges the image formed by the second light modulation device 804G and projects it onto the screen 810.

[0106] The light emitted from blue light source 100B is incident on third optical element 802B. The light emitted from blue light source 100B is collected by third optical element 802B.

[0107] The light collected by the third optical element 802B enters the third light modulation device 804B. The third light modulation device 804B modulates the incident light in accordance with image information. The projection device 808 then enlarges the image formed by the third light modulation device 804B and projects it onto the screen 810.

[0108] The projector 800 may also have a cross dichroic prism 806 that combines the light emitted from the first light modulation device 804R, the second light modulation device 804G, and the third light modulation device 804B and guides the combined light to the projection device 808.

[0109] The three colored lights modulated by the first light modulation device 804R, the second light modulation device 804G, and the third light modulation device 804B enter the cross dichroic prism 806. The cross dichroic prism 806 is formed by bonding four right-angle prisms together, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are disposed on its inner surface. These dielectric multilayer films combine the three colored lights to form light that represents a color image. The combined light is then projected onto a screen 810 by a projection device 808, and an enlarged image is displayed.

[0110] Note that red light source 100R, green light source 100G, and blue light source 100B may directly form an image without using first light modulation device 804R, second light modulation device 804G, and third light modulation device 804B, by controlling light emitting device 100 as pixels of the image in accordance with image information. Then, projection device 808 may enlarge and project the image formed by red light source 100R, green light source 100G, and blue light source 100B onto screen 810.

[0111] In the above example, a transmissive liquid crystal light valve is used as the light modulation device, but a light valve other than a liquid crystal light valve or a reflective light valve may also be used. Examples of such light valves include a reflective liquid crystal light valve and a digital micromirror device. The configuration of the projection device can be changed as appropriate depending on the type of light valve used.

[0112] The light source can also be applied to a light source device of a scanning type image display device having a scanning means which is an image forming device that displays an image of a desired size on a display surface by scanning light from the light source on a screen.

[0113] The light emitting devices according to the above-described embodiments can be used for purposes other than projectors. Examples of uses other than projectors include indoor and outdoor lighting, displays, laser printers, scanners, in-vehicle lights, sensing devices that use light, light sources for communication devices, and display devices for head-mounted displays. The light emitting devices according to the above-described embodiments can also be used for applications such as LEDs (Light Emitting Diodes) that display images by arranging minute light emitting elements in an array. ) It can also be applied to light-emitting elements in displays.

[0114] The above-described embodiment and modifications are merely examples, and the present invention is not limited to these. For example, the embodiments and modifications can be combined as appropriate.

[0115] The present invention includes configurations that are substantially the same as the configurations described in the embodiments, for example, configurations with the same functions, methods, and results, or configurations with the same purpose and effects. The present invention also includes configurations that replace non-essential parts of the configurations described in the embodiments. The present invention also includes configurations that achieve the same effects or purposes as the configurations described in the embodiments. The present invention also includes configurations that add publicly known technology to the configurations described in the embodiments.

[0116] The following can be derived from the above-described embodiment and modifications.

[0117] One aspect of the light emitting device is A substrate; a laminate having a plurality of columnar portions; an electrode provided on the laminate opposite to the substrate; and each of the plurality of columnar portions has a light-emitting layer; The electrode is provided with a plurality of first holes, the plurality of columns constitute a first photonic crystal, the electrode constitutes a second photonic crystal; The first photonic crystal and the second photonic crystal are optically coupled.

[0118] According to this light emitting device, scattering of light generated in the light emitting layer in the first hole can be reduced.

[0119] In one embodiment of the light emitting device, Each of the plurality of first holes may penetrate through the electrode.

[0120] This light emitting device can increase the optical confinement coefficient.

[0121] In one embodiment of the light emitting device, When viewed from the direction perpendicular to the substrate, each of the plurality of first holes may not overlap with the plurality of columnar portions.

[0122] According to this light emitting device, when the first hole is formed by etching, damage to the columnar portion due to etching can be suppressed.

[0123] In one embodiment of the light emitting device, Each of the plurality of columnar portions is a first semiconductor layer of a first conductivity type; a second semiconductor layer of a second conductivity type different from the first conductivity type; and the light emitting layer is provided between the first semiconductor layer and the second semiconductor layer, the first semiconductor layer is provided between the substrate and the light emitting layer, the laminate has a light propagation layer provided between adjacent columnar portions of the plurality of columnar portions, a second hole is provided in the light propagation layer; the second hole communicates with one of the plurality of first holes; The bottom surface of the second hole may be located between the second semiconductor layers of adjacent columnar portions of the plurality of columnar portions.

[0124] This light emitting device can increase the optical confinement coefficient.

[0125] In one embodiment of the light emitting device, When viewed from the direction perpendicular to the substrate, each of the plurality of first holes may overlap with the plurality of columnar portions.

[0126] This light emitting device can increase the optical confinement coefficient.

[0127] In one embodiment of the light emitting device, Each of the plurality of first holes may not penetrate through the electrode.

[0128] According to this light emitting device, it is possible to prevent damage to the columnar portion caused by etching for forming the first hole.

[0129] One aspect of the projector is The light emitting device has one aspect. [Explanation of symbols]

[0130] 10...substrate, 20...laminated body, 22...buffer layer, 24...mask layer, 26...light propagation layer, 28...second hole, 29...bottom surface, 30...columnar portion, 32...first semiconductor layer, 34...light emitting layer, 36...second semiconductor layer, 38...light confinement layer, 40...first electrode, 42...second electrode, 42a...first layer, 42b...second layer, 44...first hole, 45...bottom surface, 46...first hole group, 50...first photonic crystal, 52...second photonic crystal, 100...light emitting device, 13 0...group of columns, 200, 300, 400, 500, 600, 700...light-emitting device, 730...dummy column, 740...insulating layer, 750...electrode pad, 800...projector, 802R...first optical element, 802G...second optical element, 802B...third optical element, 804R...first light modulation device, 804G...second light modulation device, 804B...third light modulation device, 806...cross dichroic prism, 808...projection device, 810...screen

Claims

1. A substrate; a laminate having a plurality of columnar portions; an electrode provided on the laminate opposite to the substrate; and each of the plurality of columnar portions has a light-emitting layer; The electrode is provided with a plurality of first holes, the plurality of pillars constitute a first photonic crystal, the electrode constitutes a second photonic crystal; the first photonic crystal and the second photonic crystal oscillate in the same oscillation mode to form an optical confinement mode; A light emitting device, wherein the optical distance between the first photonic crystal and the second photonic crystal is 3λ or less, where λ is an oscillation wavelength.

2. In claim 1, Each of the plurality of first holes penetrates the electrode.

3. In claim 2, When viewed from a direction perpendicular to the substrate, each of the plurality of first holes does not overlap with the plurality of columnar portions.

4. In claim 3, Each of the plurality of columnar portions is a first semiconductor layer of a first conductivity type; a second semiconductor layer of a second conductivity type different from the first conductivity type; and the light emitting layer is provided between the first semiconductor layer and the second semiconductor layer, the first semiconductor layer is provided between the substrate and the light emitting layer, the laminate has a light propagation layer provided between adjacent columnar portions of the plurality of columnar portions, a second hole is provided in the light propagation layer; the second hole communicates with one of the plurality of first holes; a bottom surface of the second hole is located between the second semiconductor layers of adjacent columnar portions of the plurality of columnar portions.

5. In claim 1, When viewed from a direction perpendicular to the substrate, each of the plurality of first holes overlaps with one of the plurality of columnar portions.

6. In claim 5, a light-emitting device, wherein each of the plurality of first holes does not penetrate the electrode;

7. A projector comprising the light emitting device according to claim 1 .

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