JP2004311973A - Light emitting device and lighting device - Google Patents

Abstract

A light-emitting element having high light extraction efficiency and capable of obtaining diffused light is provided.
The light emitting device includes a light emitting diode including a multiple quantum well (MQW) light emitting layer and circular through holes formed on a p-type cladding layer of the light emitting diode and arranged symmetrically six times. A photonic crystal whose dielectric constant is periodically modulated in the in-plane direction, including a p-type contact layer 11 having p-type contact layer 11 and p-side electrode 12 buried in through-hole 11a of p-type contact layer 11; And a plano-concave lens 50 as a means for diffusing light from the light emitting diode formed through the n-side electrode 16.
[Selection diagram] Fig. 1

Description

  The present invention relates to a light emitting device and a lighting device, and more particularly to a light emitting device including a light emitting diode and a lighting device using the light emitting device.

  2. Description of the Related Art Conventionally, there is known a light emitting diode in which a photonic crystal is mounted on an emission surface of the light emitting diode to improve the efficiency of extracting outgoing light from the light emitting diode (for example, see Non-Patent Documents 1 and 2). ).

  FIG. 13 is a cross-sectional view for explaining a structure of a light emitting diode in which a conventional photonic crystal is mounted on an emission surface. Referring to FIG. 13, a structure of a light emitting diode in which a conventional photonic crystal is mounted on an emission surface will be described.

  In a conventional light emitting diode in which a photonic crystal is mounted on an emission surface, as shown in FIG. 13, an n-type cladding layer 202 made of n-type AlGaAs and a light-emitting layer 203 made of p-type GaAs are formed on an n-type GaAs substrate 201. , And a p-type cladding layer 204 made of p-type AlGaAs is sequentially laminated. As a result, a light emitting diode having a double hetero structure is formed. On the upper surface of the p-type cladding layer 204, a stripe-shaped (elongated) concavo-convex shape having a predetermined width and depth and periodically arranged is formed. Further, a metal layer 205 made of Ag is formed on the upper surface of the p-type clad layer 204 having the above-mentioned uneven shape.

In the conventional light emitting diode, as described above, the upper surface of the p-type cladding layer 204 is formed in a stripe-shaped unevenness having a predetermined width and depth and arranged periodically, and the upper surface of the unevenness is formed on the upper surface of the unevenness. Then, by forming the metal layer 205, a portion in which the dielectric constant is periodically modulated in the in-plane direction of the p-type cladding layer 204 and the metal layer 205 is formed. Thereby, the p-type cladding layer 204 can also function as a photonic crystal. As a result, the emitted light from the light emitting diode is emitted in a direction perpendicular to the emission surface, and the efficiency of extracting the emitted light can be improved.
"Highly Direct Light Sources Using Two-Dimensional Photonic Crystal Slabs," Applied Physics Letters, December 2001, Vol. 79, No. 26, pp. 4280-4282 "Strongly Direction Emission from AlGaAs / GaAs Light-Emitting Diodes", Applied Physics Letters, November 1990, Vol. 2327-2329

  However, since the light emitted from the light emitting diode in which the above-described conventional photonic crystal is mounted on the light emitting surface is emitted in a direction perpendicular to the light emitting surface, it is difficult to obtain diffused light suitable for indoor lighting or the like. There was an inconvenience of being. For this reason, there is a problem that it is difficult to use a conventional light emitting diode in which a photonic crystal is mounted on an emission surface for illumination.

  One object of the present invention is to provide a light-emitting element having high light extraction efficiency and capable of obtaining diffused light.

  Another object of the present invention is to provide a lighting device having high light extraction efficiency.

Means for Solving the Problems and Effects of the Invention

  In order to achieve the above object, a light emitting device according to a first aspect of the present invention is formed on a light emitting diode and a surface substantially parallel to a light emitting surface of the light emitting diode, and substantially corresponds to a light emitting surface. A portion whose permittivity is periodically modulated in an in-plane direction of a plane parallel to the light-emitting diode, and means for diffusing light emitted from the light-emitting diode, provided on the light emission surface side of the light-emitting diode. I have.

  In the light emitting device according to the first aspect, as described above, a portion whose dielectric constant is periodically modulated in the in-plane direction is formed on a surface substantially parallel to the light emission surface of the light emitting diode. By doing so, light emission from the light emitting element can be parallelized to light perpendicular to the light emission surface, so that light extraction efficiency from the light emitting diode can be improved. Further, by providing a means for diffusing the light emitted from the light emitting diode on the light emitting surface side of the light emitting diode, the parallel light emitted from the light emitting element can be diffused in various directions. can do. This makes it possible to obtain a light-emitting element having high light extraction efficiency and capable of emitting diffused light.

  In the light emitting device according to the first aspect, the portion where the dielectric constant is periodically modulated may be configured by periodically arranging materials having different dielectric constants. The portion may be made of a photonic crystal. According to this structure, a portion whose dielectric constant is periodically modulated can be easily obtained. The portion where the dielectric constant is periodically modulated may be configured by periodically arranging a dielectric and air or periodically arranging a dielectric and a vacuum.

  In the light emitting device according to the first aspect, preferably, the means for diffusing outgoing light has conductivity. According to this structure, when the light emitting diode and the means for diffusing emitted light are formed in close contact with each other, it is possible to electrically connect the light emitting diode and the means for diffusing emitted light. With this, the current introducing portion to the light emitting diode can be formed in the means for diffusing the emitted light, so that there is no need to directly wire the light emitting diode. As a result, the light emitting element can be easily assembled. Further, since there is no need to perform wiring on the light emitting surface, the wiring does not block the emitted light. As a result, the intensity of light emitted from the light emitting element can be improved.

  In the light emitting device according to the first aspect, the means for diffusing the emitted light may be constituted by a lens. According to this structure, the parallel light emitted from the light emitting diode can be easily converted into the diffused light. In this case, the means for diffusing the emitted light may include a concave lens. With this configuration, the parallel light emitted from the light emitting diode can be diffused by the concave lens, so that the parallel light can be easily converted into the diffused light. Further, in this case, the concave lens may include a plano-concave lens having a flat first surface and a concave second surface.

  The light emitting device according to the first aspect preferably further includes a phosphor provided between the light emitting surface and the means for diffusing the emitted light. With this configuration, the emitted light is scattered by the phosphor, so that diffused light can be obtained more easily. Further, since the wavelength of the light emitted from the light emitting diode can be converted to a different wavelength, white light emission suitable for illumination use can be obtained by combining various phosphors.

  In the light emitting device according to the first aspect, the means for diffusing the emitted light may include a convex mirror. With this configuration, the parallel light emitted from the light emitting diode can be reflected and diffused by the convex mirror, so that the parallel light can be easily converted to the diffused light.

  In the light emitting device according to the first aspect, the means for diffusing the emitted light may include a light transmitting member in which a light diffusing agent composed of substantially transparent fine particles is dispersed. According to this structure, the parallel light emitted from the light emitting diode can be diffused by the translucent member in which the light diffusing agent is dispersed, so that the parallel light can be easily converted into the diffused light. it can.

  In the light emitting device according to the first aspect, the means for diffusing the emitted light may include a translucent member having fine irregularities on at least one of the front surface and the back surface. According to this structure, the parallel light emitted from the light emitting diode can be diffused by the light-transmissive member having the fine irregularities, so that the parallel light can be easily converted to the diffused light. .

  In the light emitting device according to the first aspect, preferably, the light emitting diode includes a light emitting layer, and the light emitting layer is made of a nitride semiconductor. With this configuration, it is possible to easily obtain high-energy light emission with a short wavelength in the range from blue to ultraviolet, and thus it is possible to improve the intensity of emitted light.

  In the light emitting device according to the first aspect, preferably, a plurality of light emitting diodes are arranged in a matrix when viewed in plan. With such a configuration, a region from which light is emitted can be enlarged, so that the light-emitting element can be easily used as a light source for lighting or the like.

  In this case, it is preferable that the means for diffusing the outgoing light includes a lens, and the lenses are arranged in a matrix in a plan view. According to this structure, light emitted from the light emitting diodes arranged in a matrix can be easily diffused.

  A lighting device according to a second aspect of the present invention is a light emitting diode, and is formed on a surface substantially parallel to a light emitting surface of the light emitting diode, and has an in-plane direction of a surface substantially parallel to the light emitting surface. And a light emitting element including a portion whose dielectric constant is periodically modulated, and means for diffusing light emitted from the light emitting diode, provided on the light emitting surface side of the light emitting diode.

  In the lighting device according to the second aspect, as described above, a portion whose dielectric constant is periodically modulated in the in-plane direction is formed on a surface substantially parallel to the light emission surface of the light emitting diode. By doing so, light emission from the light emitting element can be parallelized to light perpendicular to the light emission surface, so that light extraction efficiency from the light emitting diode can be improved. Further, by providing a means for diffusing light emitted from the light emitting diode on the light emitting surface side of the light emitting diode, parallel light emitted from the light emitting element can be diffused in various directions. can do. As a result, a light-emitting element having high light extraction efficiency and capable of emitting diffused light can be obtained. By using this light-emitting element as a light source, a sufficient amount of light for a lighting device can be obtained. .

  The lighting device according to the second aspect preferably further includes a white-light phosphor disposed at a predetermined distance from the light-emitting element and configured to convert light emitted from the light-emitting element into white light. According to this structure, white light emission suitable for a lighting device can be easily obtained. In this case, the phosphor for white light may be formed by mixing a plurality of phosphor materials of different emission colors.

  In the lighting device according to the second aspect, preferably, a plurality of light-emitting diodes constituting the light-emitting element are arranged in a matrix when viewed in plan. With such a configuration, a region from which light is emitted can be enlarged, so that the light-emitting element can be easily used as a light source of a lighting device. In this case, it is preferable that the means for diffusing the outgoing light includes a lens, and the plurality of lenses are arranged in a matrix when viewed in plan. According to this structure, light emitted from the light emitting diodes arranged in a matrix can be easily diffused.

  In the invention according to the first and second aspects, the following configuration may be adopted.

  That is, in the light emitting element including the means for diffusing emitted light having conductivity, the means for diffusing emitted light having conductivity is preferably formed so as to be in contact with the light emitting side portion of the light emitting diode. ing. According to this structure, the electrical connection between the light emitting diode and the means for diffusing the emitted light can be easily performed.

  In the light emitting device including the means for diffusing emitted light having conductivity, the means for diffusing emitted light having conductivity is preferably selected from the group consisting of n-type SiC, n-type AlN, and p-type diamond. Consists of at least one material. If the means for diffusing emitted light is formed of the above-mentioned materials, good thermal conductivity can be obtained in addition to conductivity, so that the heat generated by the light emitting diode via the means for diffusing emitted light can be obtained. Can be easily dissipated. As a result, the light emitting element can be operated with a larger current, so that the intensity of the emitted light can be improved.

  In the light emitting element including the substantially transparent means having the fine unevenness, the interval between adjacent convex portions in the fine unevenness may be about 200 nm or more and about 2000 nm or less. If the interval between the adjacent convex portions is set to such an interval, the interval can be equal to or several times the emission wavelength, so that light can be diffused by the diffraction effect.

  In the light emitting device including the substantially transparent means having the fine unevenness, the interval between adjacent convex portions in the fine unevenness may be about 2 μm or more and about 100 μm or less. If the interval between the adjacent convex portions is set to such an interval, the light is refracted by the uneven portion, so that the light can be easily diffused.

  In the configuration having the plano-concave lens, a light emitting element may be arranged in contact with the flat first surface. With this configuration, the light emitting element and the lens can be easily joined. In addition, as compared with the case where the light emitting element and the lens are arranged apart from each other, it is possible to reduce reflection on the emission surface of the light emitting element and the flat first surface of the lens.

  Further, the concave lens may be arranged at a ratio of one for each of the plurality of light emitting diodes. In this case, the plurality of concave lenses and the light emitting diodes may be arranged in an array. With such a configuration, a region from which light is emitted can be enlarged, and thus it can be easily used as a light source such as illumination.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(1st Embodiment)
FIG. 1 is a cross-sectional view illustrating a structure of a light emitting device according to a first embodiment. FIG. 2 is a top view for explaining the planar structure of the p-type contact layer according to the first embodiment of the present invention. First, the structure of the light emitting device 10 according to the first embodiment of the present invention will be described with reference to FIGS. The light emitting device 10 of the first embodiment includes a light emitting diode and a plano-concave lens 50.

In the light-emitting diode of the first embodiment, an Si-doped film of about 5 μm is formed on the (0001) Ga surface of an n-type GaN substrate 1 having a thickness of about 200 to 400 μm, which is about 2 mm square and doped with oxygen or Si. A single-crystal n-type GaN layer 4 having a thickness is formed. On the n-type GaN layer 4, an n-type clad layer 6 made of single-crystal n-type Al _0.1 Ga _0.9 N doped with Si and having a thickness of about 0.15 μm is formed. On the n-type cladding layer 6, six barrier layers made of single-crystal undoped GaN having a thickness of about 5 nm and a single-crystal undoped Ga _0.9 In _0.1 having a thickness of about 5 nm are provided. An active layer 7 having a multiple quantum well (MQW) structure in which five well layers of N are alternately stacked is formed. On the active layer 7, a protective layer 8 made of single-crystal undoped GaN having a thickness of about 10 nm, and a single-crystal p-type Al _0.1 doped with Mg and having a thickness of about 0.15 μm are formed. A p-type cladding layer 9 made of Ga _0.9 N is formed in this order.

On the upper surface of the p-type cladding layer 9, a p-type contact layer 11 made of single-crystal p-type Ga _0.95 In _0.05 N having a thickness of about 30 nm is formed. As shown in FIG. 2, the p-type contact layer 11 has a diameter of about 250 nm and an interval of about 380 nm (equal to about 4/3 ^1/2 times the emission wavelength λ in the p-type cladding layer 9). In D), a plurality of circular through holes 11a arranged symmetrically six times are formed. The p-type contact layer 11 having such a through hole 11a is an example of the “portion in which the dielectric constant is periodically modulated in the in-plane direction of a plane substantially parallel to the emission surface” of the present invention. .

In the first embodiment, the value of the interval (D) was designed with the main light emission wavelength λ from the light emitting layer (active layer 7) being about 380 nm and the refractive index of the nitride semiconductor being 2.3. This interval (D) is preferably designed to be about 2/3 ^1/2 times the emission wavelength λ in the p-type cladding layer 9, but in this case, fine processing is required. Therefore, in the first embodiment, processing to be easier, the distance (D), were designed to correspond to about 4/3 ^half of the emission wavelength in the p-type cladding layer 9.

  A p-side electrode 12 is formed on the upper surface of the p-type contact layer 11 so as to fill the through-hole 11a of the p-type contact layer 11. The p-side electrode 12 includes, from the lower layer to the upper layer, an ohmic electrode layer having a thickness of about 2 nm formed of a Ni layer, a Pd layer or a Pt layer, and an oxide transparent layer formed of an ITO film having a thickness of about 200 nm. An electrode layer, a metal reflective layer having a thickness of about 1 μm comprising an Al layer, an Ag layer or a Rh layer, a barrier electrode comprising a Pt layer or a Ti layer, and a pad electrode comprising an Au layer or an Au—Sn layer. It is configured.

  Further, an n-side electrode 16 is formed on a region having a width of about 50 μm along the outer peripheral portion of the back surface of the n-type GaN substrate 1. The n-side electrode 16 includes an ohmic electrode layer made of an Al layer, a barrier electrode made of a Pt layer or a Ti layer, and a pad made of an Au layer or an Au—Sn layer in order from the side closer to the back surface of the n-type GaN substrate 1. And electrodes. The light emitting diode of the first embodiment has the above structure.

  A plano-concave lens 50 made of a material having good thermal conductivity and conductivity, such as n-type SiC, n-type AlN, or p-type diamond, is provided on the back surface of the n-side electrode 16 of the light emitting diode. Has been fused. The plano-concave lens 50 is fused to the n-side electrode 16 so that the plane side faces the n-type GaN substrate 1. Here, the plano-concave lens 50 is an example of the “means for diffusing light emitted from the light emitting diode” of the present invention. The light emitting diode 10 and the plano-concave lens 50 constitute the light emitting element 10 of the first embodiment shown in FIG.

  When a lighting device is formed using the light emitting element 10 according to the first embodiment, the upper surface of the p-side electrode 12 of the light emitting diode is sub-mount (heat radiator) made of diamond, AlN or SiC (not shown). ). In this case, the back surface of the n-type GaN substrate 1 on which the n-side electrode 16 is formed becomes an emission surface, and light is emitted in the direction indicated by the arrow in FIG.

Next, the manufacturing process of the light emitting device 10 according to the first embodiment will be described with reference to FIG. First, an n-type GaN substrate 1 having a thickness of about 200 to 400 μm, which is about 2 mm square and doped with oxygen or Si, is prepared. Then, while holding at about 1000 ° C. ~ about 1200 ° C., and a carrier gas consisting of _H 2 / _{N 2} mixed gas containing _{H 2} to about 50%, and a starting gas consisting of NH ₃ and trimethylgallium (TMGa), By using a dopant gas composed of SiH ₄ , Si was doped on the (0001) Ga surface of the n-type GaN substrate 1 using MOVPE (Metal Organic Vapor Phase Epitaxy). A single-crystal n-type GaN layer 4 having a thickness of about 5 μm is grown at a growth rate of about 3 μm / h.

The temperature of the n-type GaN substrate 1 about 1000 ° C. to about 1200 ° C., preferably being maintained at about 1150 ° C., of _{H 2} from about 1% to about 3% content to _H 2 / _{N 2} mixed gas Of n-type GaN layer 4 by using a carrier gas composed of Si, a source gas composed of NH ₃ , TMGa and trimethylaluminum (TMAl), and a dopant gas composed of SiH _4. Is grown at a growth rate of about 3 μm / h. The n-type cladding layer 6 is made of single-crystal n-type Al _0.1 Ga _0.9 N and has a thickness of

The temperature of the n-type GaN substrate 1 about 700 ° C. to about 1000 ° C., preferably being maintained at about 850 ° C., of _{H 2} from about 1% to about 5% content to _H 2 / _{N 2} mixed gas , And a source gas composed of NH ₃ , triethylgallium (TEGa) and trimethylindium (TMIn) are used to form a single-crystal undoped GaN having a thickness of about 5 nm on the n-type cladding layer 6. Active layer 7 having an MQW structure in which six barrier layers made of GaAs and five well layers made of single-crystal undoped Ga _0.9 In _0.1 N having a thickness of about 5 nm are alternately stacked. Is formed at a growth rate of about 0.4 nm / s. Further, a protection layer 8 made of single-crystal undoped GaN having a thickness of about 10 nm is continuously grown at a growth rate of about 0.4 nm / s.

Then, the temperature of the GaN substrate 1 of about 1000 ° C. to about 1200 ° C., preferably being maintained at about 1150 ° C., consisting of _{H 2} from about 1% to about 3% content to _H 2 / _{N 2} mixed gas By using a carrier gas, a source gas composed of NH ₃ , TMGa and TMAl, and a dopant gas composed of biscyclopentadienylmagnesium (Cp ₂ Mg), about 0 mg of Mg doped on the protective layer 8. A p-type cladding layer 9 made of single-crystal p-type Al _0.1 Ga _0.9 N having a thickness of .15 μm is grown at a growth rate of about 3 μm / h.

Next, using a lithography technique and an etching technique such as by electron beam lithography, which has a cylindrical shape with a diameter of approximately 250 nm, approximately about 4/3 ^half of the emission wavelength in the p-type cladding layer 9 lambda SiN layers (not shown) are formed six times symmetrically at equal intervals of about 380 nm. That is, a columnar SiN layer is formed at the position where the through hole 11a shown in FIG. 2 is formed. Using this SiN layer as a mask, a p-type contact layer 11 of single-crystal p-type Ga _0.95 In _0.05 N having a thickness of about 30 nm is grown on the p-type cladding layer 9 by MOVPE. Let it. At this time, the temperature of the GaN substrate 1 about 700 ° C. to about 1000 ° C., preferably being maintained at about 850 ° C., consisting of _{H 2} from about 1% to about 5% content to _H 2 / _{N 2} mixed gas The p-type contact layer 11 is formed at a growth rate of about 0.4 nm / s by using a carrier gas, a source gas composed of NH ₃ , TEGa and TMIn, and a dopant gas composed of Cp ₂ Mg.

Here, by forming the p-type cladding layer 9 and the p-type contact layer 11 under the condition that the hydrogen concentration of the carrier gas is low (H ₂ : about 1% to about 5%), the heat treatment is not performed in the N ₂ atmosphere. , Mg dopant is activated. Thereby, the p-type cladding layer 9 and the p-type contact layer 11 can be made into a p-type semiconductor layer having a high carrier concentration. Thereafter, by removing the SiN layer (not shown) on the p-type cladding layer 9, the p-type contact layer 11 having the through holes 11a as shown in FIG. 2 is formed.

  Thereafter, a film thickness of about 2 nm made of a Ni layer, a Pd layer, or a Pt layer is formed on the upper surface of the p-type contact layer 11 so as to fill the through-hole of the p-type contact layer 11 by using a vacuum deposition method or the like. An ohmic electrode layer, an oxide transparent electrode layer made of an ITO film having a thickness of about 200 nm, a metal reflective layer made of an Al layer, an Ag layer or a Rh layer having a thickness of about 1 μm, a Pt layer or Ti The p-side electrode 12 is formed by sequentially forming a barrier electrode composed of a layer and a pad electrode composed of an Au layer or an Au—Sn layer. Also, on a region of about 50 μm width along the outer peripheral portion of the back surface of the n-type GaN substrate 1, an ohmic electrode layer made of an Al layer, a barrier electrode made of a Pt layer or a Ti layer is formed by using a vacuum deposition method or the like. Then, an n-side electrode 16 is formed by sequentially forming a pad electrode made of an Au layer or an Au—Sn layer. Thus, the light emitting diode of the first embodiment is formed.

  Finally, a plano-concave lens made of a material having good thermal conductivity and conductivity, such as n-type SiC, n-type AlN, or p-type diamond, on the back surface of the n-type GaN substrate 1 via the n-side electrode 16. 50 is fused to the n-type GaN substrate 1 of the plano-concave lens 50. Thus, the light emitting device 10 according to the first embodiment of the present invention is formed.

In the first embodiment, as described above, the interval D (see FIG. 2) between the through holes 11a of the p-type contact layer 11 is set to about 4/3 ^1/2 times the emission wavelength λ in the p-type cladding layer 9. At the same time, by embedding the ohmic electrode layer and the transparent oxide electrode layer constituting the p-side electrode 12 in the through hole 11a, the dielectric constant of the p-type contact layer 11 is periodically modulated in the in-plane direction. Function as a two-dimensional photonic crystal. Further, by forming the p-type contact layer 11 having the above structure on a surface parallel to the back surface of the GaN substrate 1 which is the light emitting surface of the light emitting diode, light emitted from the light emitting diode emits light perpendicular to the light emitting surface. , The light extraction efficiency can be increased. Further, by providing the plano-concave lens 50 on the emission surface, the outgoing light parallelized in the direction perpendicular to the emission surface by the concave surface of the plano-concave lens 50 can be easily diffused in various directions. it can. As a result, it is possible to obtain a light emitting diode having high light extraction efficiency and capable of emitting diffused light.

  In the first embodiment, the plano-concave lens 50 is made of a material having good thermal conductivity, such as n-type SiC, n-type AlN, or p-type diamond, so that heat generated in the light emitting diode can be easily radiated. can do. As a result, the light emitting element can be operated with a larger current, so that the intensity of the emitted light can be improved. Further, if a heat radiating portion such as a heat radiating fin is attached to the plano-concave lens 50, heat can be more easily radiated.

  Further, in the first embodiment, the plano-concave lens 50 is formed of a conductive material such as n-type SiC, and the n-side electrode 16 of the light emitting diode and the plano-concave lens 50 are formed in close contact with each other to emit light. Electrical connection between the diode and the plano-concave lens 50 can be made. Thus, since the electrodes of the light emitting diode can be formed on the plano-concave lens 50, there is no need to directly wire the light emitting diode. For this reason, assembling of the light emitting diode becomes easy, and the reliability of the light emitting diode can be improved. Further, since there is no need to perform wiring on the emission surface, the wiring does not block the emitted light. As a result, the intensity of light emitted from the light emitting diode can be improved.

  Further, in the first embodiment, if the thickness of the ohmic electrode layer forming the p-side electrode 12 is reduced, light absorption can be reduced. In addition, the oxide transparent electrode layer forming the p-side electrode 12 can prevent the ohmic electrode layer forming the p-side electrode 12 from reacting with the metal reflection layer. Further, the reaction between the metal reflective layer forming the p-side electrode 12 and the pad electrode can be suppressed by the barrier electrode forming the p-side electrode 12. Further, the reaction between the ohmic electrode layer forming the n-side electrode 16 and the pad electrode can be suppressed by the barrier electrode forming the n-side electrode 16.

(2nd Embodiment)
FIG. 3 is a cross-sectional view illustrating a structure of a light emitting device according to a second embodiment. FIG. 4 is a top view for explaining the planar structure of the metal layer according to the second embodiment of the present invention. First, with reference to FIGS. 3 and 4, in the second embodiment, unlike the first embodiment, a portion where the dielectric constant is periodically modulated (two-dimensional photo The structure of the light emitting element 20 on which the (nick crystal) is formed will be described. The light emitting device 20 according to the second embodiment includes a light emitting diode and a plano-concave lens 50.

In the light emitting diode according to the second embodiment, a single crystal n-type Al _0.2 Ga _0.8 having a thickness of about 40 nm doped with Si is formed on the upper surface of the single crystal n-type GaN layer 24 doped with Si. An n-type multilayer reflective layer 25 is formed by alternately stacking 10 layers of an N layer and a single-crystal n-type GaN layer having a thickness of about 40 nm doped with Si. On the n-type multilayer reflective layer 25, an n-type clad layer 26 made of a single-crystal n-type Al _0.1 Ga _0.9 N layer doped with Si and having a thickness of about 0.15 μm is formed. . On the n-type cladding layer 26, an SQW active layer 27 having a single quantum well (SQW) structure composed of a single-crystal undoped Ga _0.8 In _0.2 N well layer having a thickness of about 5 nm is formed. ing.

On the SQW active layer 27, a protective layer 28 made of single-crystal undoped GaN having a thickness of about 10 nm, and a single crystal p-type Al _0.1 doped with Mg and having a thickness of about 0.15 μm A p-type cladding layer 29 made of Ga _0.9 N is formed in this order. On the p-type cladding layer 29, a single-crystal p-type Al _0.2 Ga _0.8 N layer having a thickness of about 40 nm doped with Mg and a single crystal having a thickness of about 40 nm doped with Mg are provided. A p-type multilayer reflective layer 30 in which p-type GaN layers are alternately laminated by 10 layers is formed. On the p-type multilayer reflective layer 30, a p-type contact layer 31 made of single-crystal p-type Ga _0.95 In _0.05 N doped with Mg and having a thickness of about 30 nm is formed.

  Further, a p-side electrode 32 is formed on the upper surface of the p-type contact layer 31. The p-side electrode 32 includes, from the lower layer to the upper layer, an ohmic electrode layer having a thickness of about 2 nm made of a Ni layer, a Pd layer or a Pt layer, and an oxide transparent layer made of an ITO film having a thickness of about 200 nm. An electrode layer, a metal reflective layer having a thickness of about 1 μm comprising an Al layer, an Ag layer or a Rh layer, a barrier electrode comprising a Pt layer or a Ti layer, and a pad electrode comprising an Au layer or an Au—Sn layer. It is configured.

  A support substrate 33 having a thickness of about 200 μm to about 1 mm is formed on the upper surface of the p-side electrode 32. The support substrate 33 is made of a p-type diamond substrate, an n-type SiC substrate, a polycrystalline AlN substrate, or the like. On the front surface and the back surface of the support substrate 33, electrodes 37 and 38 each composed of an Al / Pt / Au layer, which are laminated in the order of the Al layer, the Pt layer, and the Au layer from the support substrate 33 side, are formed. The support substrate 33 is bonded to the p-side electrode 32 via the electrode 37.

  Here, in the second embodiment, a metal layer 34 made of an Al layer having a thickness of about 50 nm is formed on the back surface of the n-type GaN layer 24. As shown in FIG. 4, the metal layer 34 has a diameter of about 120 nm and is arranged four times symmetrically at an interval (D) of about 190 nm which is substantially equal to the emission wavelength λ in the p-type cladding layer 29. A plurality of circular through holes 34a are formed. The metal layer 34 having such a through hole 34a is an example of the “portion in which the dielectric constant is periodically modulated in an in-plane direction of a plane substantially parallel to the emission surface” of the present invention. The value of the interval (D) was designed with the main light emission wavelength λ from the light emitting layer (SQW active layer 27) being about 440 nm and the refractive index of the nitride-based semiconductor being 2.3. On the back surface of the metal layer 34, an n-side electrode 35 made of an oxide transparent conductive film such as ITO is formed so as to fill the through hole 34a of the metal layer 34. Further, a pad electrode 36 made of an Au layer or an Au—Sn layer is formed on a region having a width of about 50 μm along the outer peripheral portion on the back surface of the n-side electrode 35. The light emitting diode of the second embodiment has the above structure.

  In the second embodiment, a plano-concave lens 50 made of a material having good thermal conductivity and conductivity such as n-type SiC, n-type AlN, or p-type diamond is provided on the back surface of the pad electrode 36 of the light emitting diode. Are fused so that the plane side faces the n-side electrode 35. The plano-concave lens 50 is an example of the “means for diffusing light emitted from the light emitting diode” of the present invention. The light emitting diode 20 and the plano-concave lens constitute the light emitting device 20 according to the second embodiment shown in FIG.

  In the light emitting device 20 according to the second embodiment, the back surface of the n-side electrode 35 serves as a light emission surface, and emits light in a direction indicated by an arrow in FIG.

  FIG. 5 is a sectional view for explaining the manufacturing process of the light emitting device according to the second embodiment shown in FIG. Next, the manufacturing process of the light emitting device 20 according to the second embodiment will be described with reference to FIGS.

First, as shown in FIG. 5, a semiconductor substrate 21 having a surface made of a (111) plane (or a Ga plane) such as GaP, GaAs, or Si is prepared. Then, on the upper surface of the semiconductor substrate 21, a selective growth mask 22 made of SiO ₂ , SiN _x, or the like having stripe-shaped openings or hexagonal or circular openings scattered is formed. Thereafter, while the temperature of the semiconductor substrate 21 is maintained at about 400 ° C. to about 700 ° C., selective growth is performed by using a source gas composed of NH ₃ , TMGa, and TMAl and a dopant gas composed of SiH _4. On the surface of the semiconductor substrate 21 exposed between the masks 22, an n-type low-temperature n-type GaN, AlGaN, or AlN non-single-crystal n-doped GaN having a film thickness of about 10 nm to about 50 nm is formed by MOVPE. The buffer layer 23 is formed.

Then, the semiconductor substrate 21 about 1000 ° C. ~ about 1200 ° C., preferably being maintained at about 1150 ° C., and a carrier gas consisting of _H 2 / _{N 2} mixed gas containing _{H 2} to about 50%, NH ₃ An n-type GaN layer 24 is grown on the n-type low-temperature buffer layer 23 at a growth rate of about 3 μm / h by using a source gas of TMGa and TMGa and a dopant gas of SiH ₄ .

Then, the temperature of the semiconductor substrate 21 about 1000 ° C. to about 1200 ° C., preferably being maintained at about 1150 ° C., consisting of _{H 2} from about 1% to about 3% content to _H 2 / _{N 2} mixed gas By using a carrier gas, a source gas composed of NH ₃ , TMGa and TMAl, and a dopant gas composed of SiH ₄ , a single-crystal Si-doped single crystal having a thickness of about 40 nm is formed on the n-type GaN layer 24. An n-type multilayer reflective layer 25 in which n-type Al _0.2 Ga _0.8 N layers and Si-doped single-crystal n-type GaN layers each having a thickness of about 40 nm are alternately laminated in layers of about 3 μm / The growth rate is h.

Then, the temperature of the semiconductor substrate 21 about 1000 ° C. to about 1200 ° C., preferably being maintained at about 1150 ° C., consisting of _{H 2} from about 1% to about 3% content to _H 2 / _{N 2} mixed gas By using a carrier gas, a source gas composed of NH ₃ , TMGa and TMAl and a dopant gas composed of SiH ₄ , the n-type multilayer reflective layer 25 has a thickness of about 0.15 μm doped with Si. An n-type clad layer 26 made of a single-crystal n-type Al _0.1 Ga _0.9 N layer is grown at a growth rate of about 3 μm / h.

Then, the temperature of the semiconductor substrate 21 from about 700 ° C. to about 1000 ° C., preferably being maintained at about 850 ° C., consisting of _{H 2} from about 1% to about 5% content to _H 2 / _{N 2} mixed gas By using a carrier gas and a source gas composed of NH ₃ , TEGa and TMIn, a single-crystal undoped Ga _0.8 In _0.2 N well layer having a thickness of about 5 nm is formed on the n-type cladding layer 26. Is grown at a growth rate of about 0.4 nm / s. Further, a protective layer 28 made of single-crystal undoped GaN having a thickness of about 10 nm is continuously grown at a growth rate of about 0.4 nm / s.

Then, the temperature of the semiconductor substrate 21 about 1000 ° C. to about 1200 ° C., preferably being maintained at about 1150 ° C., consisting of _{H 2} from about 1% to about 3% content to _H 2 / _{N 2} mixed gas By using a carrier gas, a source gas composed of NH ₃ , TMGa and TMAl, and a dopant gas composed of Cp ₂ Mg, a Mg-doped single crystal having a thickness of about 0.15 μm is formed on the protective layer 28. The p-type cladding layer 29 made of p-type Al _0.1 Ga _0.9 N is formed at a growth rate of about 3 μm / h.

Then, the temperature of the semiconductor substrate 21 about 1000 ° C. to about 1200 ° C., preferably being maintained at about 1150 ° C., consisting of _{H 2} from about 1% to about 3% content to _H 2 / _{N 2} mixed gas By using a carrier gas, a source gas composed of NH ₃ , TMGa and TMAl, and a dopant gas composed of Cp ₂ Mg, a Mg-doped single crystal having a thickness of about 40 nm is formed on the p-type cladding layer 29. The p-type multilayer reflective layer 30 in which 10 p-type Al _0.2 Ga _0.8 N layers and Mg-doped single-crystal p-type GaN layers each having a thickness of about 40 nm are alternately laminated by about 3 μm / H growth rate.

Here, the p-type cladding layer 29 and the p-type multilayer reflective layer 30 are heat-treated in an N ₂ atmosphere by forming under a condition that the hydrogen concentration of the carrier gas is low (H ₂ : about 1% to about 3%). Without this, the Mg dopant is activated. Thereby, the p-type cladding layer 29 and the p-type multilayer reflective layer 30 can be made into a p-type semiconductor layer having a high carrier concentration.

Then, the temperature of the semiconductor substrate 21 from about 700 ° C. to about 1000 ° C., preferably being maintained at about 850 ° C., consisting of _{H 2} from about 1% to about 5% content to _H 2 / _{N 2} mixed gas By using a carrier gas and a source gas composed of NH ₃ , TEGa and TMIn, a single crystal undoped Ga _0.95 In _0.05 N having a thickness of about 30 nm is formed on the p-type multilayer reflective layer 30. The contact layer 31 is grown at a growth rate of about 0.4 nm / s.

Next, while the temperature of the semiconductor substrate 21 is maintained at about 400 ° C. to about 900 ° C., preferably about 800 ° C., hydrogen is desorbed from the contact layer 31 by annealing in an N ₂ atmosphere. As a result, the hydrogen concentration in the contact layer 31 is reduced to about 5 × 10 ¹⁸ cm ⁻³ or less. After that, Mg is ion-implanted into the contact layer 31 at a dose of about 1 × 10 ¹⁸ cm ⁻³ to about 1 × 10 ¹⁹ cm ⁻³ , and then annealed at about 800 ° C. in an N ₂ atmosphere to thereby form the contact layer. 31 is made p-type.

  Thereafter, using a vacuum deposition method or the like, on the upper surface of the contact layer 31, from the lower layer to the upper layer, an ohmic electrode layer having a thickness of about 2 nm made of a Ni layer, a Pd layer, or a Pt layer is formed. An oxide transparent electrode layer made of an ITO film having a thickness of about 1 μm, a metal reflection layer having a thickness of about 1 μm made of an Al layer, an Ag layer or a Rh layer, a barrier electrode made of a Pt layer or a Ti layer, and Au A p-side electrode 32 composed of a layer or a pad electrode made of an Au—Sn layer is formed.

  Electrodes 37 and 38 made of Al / Pt / Au are formed on the front and back surfaces, respectively, and a support substrate 33 made of a p-type diamond substrate, an n-type SiC substrate and a polycrystalline AlN substrate and having a thickness of about 200 μm to about 1 mm. Prepare Then, the support substrate 33 is bonded on the upper surface of the p-side electrode 32 via the electrode 37.

  Next, after the semiconductor substrate 21 is removed by wet etching or the like, the back surface of the n-type GaN layer 24 is exposed by removing the selective growth mask 22 and the n-type low-temperature buffer layer 23 by polishing or the like.

  Next, as shown in FIG. 3, a metal layer 34 of an Al layer having a thickness of about 50 nm is formed on the exposed back surface of the n-type GaN layer 24 by using a vacuum evaporation method or the like. Then, using a process similar to the process of forming the through hole 11a of the p-type contact layer 11 of the first embodiment, the metal layer 34 has a diameter of about 120 nm as shown in FIG. Circular through-holes 34a are formed four times symmetrically at an interval (D) of approximately 190 nm approximately equal to the emission wavelength λ in the cladding layer 29.

  Next, an n-side electrode 35 made of an oxide transparent conductive film such as an ITO film is formed on the back surface of the metal layer 34 so as to fill the through hole 34a of the metal layer 34. Further, a pad electrode 36 made of an Au layer or an Au—Sn layer is formed on a region having a width of about 50 μm along the outer peripheral portion on the back surface of the n-side electrode 35. Thus, the light emitting diode of the second embodiment is formed.

  Next, a plano-concave lens 50 made of a material having good thermal conductivity and conductivity, such as n-type SiC, n-type AlN, or p-type diamond, is formed on the back surface of the n-side electrode 35 via the pad electrode 36. , So that the flat side faces the n-side electrode 35. Thus, the light emitting device 20 according to the second embodiment including the light emitting diode and the plano-concave lens 50 shown in FIG. 3 is formed.

  In the second embodiment, as described above, the interval D (see FIG. 4) between the through holes 34a of the metal layer 34 is set to be substantially equal to the emission wavelength λ in the p-type cladding layer 29, and By embedding a transparent conductive oxide film forming the n-side electrode 35 in the hole 34a, the metal layer 34 can function as a two-dimensional photonic crystal whose dielectric constant is periodically modulated in the in-plane direction. Can be. By forming the metal layer 34 having such a structure on a surface parallel to the back surface of the n-side electrode 35 that is the light emitting surface of the light emitting diode, light emission from the light emitting diode is converted into light perpendicular to the light emitting surface. Since the light is collimated, the light extraction efficiency can be increased. In addition, by providing the plano-concave lens 50 on the emission surface, the emitted light parallelized in a direction perpendicular to the emission surface can be easily diffused in various directions. As a result, it is possible to obtain the light emitting element 20 that has high light extraction efficiency and can emit diffused light.

(Third embodiment)
FIG. 6 is a sectional view illustrating a structure of a lighting device using a light emitting device according to a third embodiment of the present invention. With reference to FIG. 6, in the third embodiment, a lighting device 40 including a light emitting diode 41 constituting the light emitting element 10 of the first embodiment will be described.

  The lighting device 40 according to the third embodiment uses a light emitting diode 41 having a structure in which the plano-concave lens 50 is removed from the light emitting device 10 of the first embodiment shown in FIG. The light emitting diode 41 is bonded to the inner bottom surface of the light emitting element package 42 made of a highly heat conductive material such as Cu with the light emitting surface facing upward by a fusion material such as Au-Sn solder. The n-side electrode (not shown) and the p-side electrode (not shown) of the light emitting diode 41 are electrically connected to the terminals 43 of the light emitting element package 42 by wire bonding.

  A phosphor 44 is arranged on the upper opening surface of the light emitting element package 42. On the upper surface of the phosphor 44, an insulating plano-concave lens 55 made of glass, quartz, resin or the like is arranged.

  In the third embodiment, as described above, by disposing the phosphor 44 between the emission surface and the plano-concave lens 55, the emission light parallelized in the direction perpendicular to the emission surface from the light emitting diode 41 is scattered. Therefore, diffused light can be easily obtained. Also, the outgoing light is diffused by the plano-concave lens 55, so that diffused light can be more easily obtained. When the light emitting diode 41 is made of a nitride-based semiconductor, high-energy light is emitted from the light emitting diode 41 at a short wavelength in the range from blue to ultraviolet, and is emitted to the phosphor 44. Thereby, the wavelength of the emitted light can be efficiently converted to a different wavelength from the emitted light by using the phosphor 44. Therefore, when various phosphors are combined, white light emission suitable for illumination use is obtained. be able to.

(Fourth embodiment)
FIG. 7 is a cross-sectional view illustrating a structure of a light emitting device according to a fourth embodiment. In the fourth embodiment, an example in which a convex mirror is used instead of the plano-concave lens of the second embodiment will be described with reference to FIG. The other structure of the fourth embodiment is the same as that of the second embodiment.

  The light emitting device 60 according to the fourth embodiment has a structure obtained by removing the plano-concave lens 50 from the light emitting device 20 according to the second embodiment shown in FIG. That is, the light emitting diode of the fourth embodiment includes the metal layer 34 that functions as a two-dimensional photonic crystal whose dielectric constant is periodically modulated in the in-plane direction. A convex mirror 65 is arranged at a predetermined distance from the light emitting surface so as to face the light emitting surface of the light emitting diode. The convex mirror 65 is formed by coating the surface of a convex portion made of resin or glass with a reflective film made of Al or Ag. The convex mirror 65 is an example of the “means for diffusing light emitted from the light emitting diode” of the present invention.

  In the light emitting device 60 according to the fourth embodiment, as in the second embodiment, the metal layer 34 can function as a two-dimensional photonic crystal whose dielectric constant is periodically modulated in the in-plane direction. In addition, light emitted from the light emitting diode can be parallelized to light perpendicular to the emission surface. Thereby, light extraction efficiency can be improved.

  In the light emitting element 60 according to the fourth embodiment, as described above, the convex mirror 65 is disposed so as to face the light emitting surface of the light emitting diode, so that light emitted from the light emitting diode is reflected by the convex mirror 65. Can be diffused.

(Fifth embodiment)
FIG. 8 is a plan view illustrating a structure of a light emitting device according to a fifth embodiment. FIG. 9 is a cross-sectional view illustrating a structure of a light emitting device according to a fifth embodiment. With reference to FIGS. 8 and 9, in a light emitting device 70 according to the fifth embodiment, an example will be described in which a plano-concave lens 72a and a light emitting diode 71 are two-dimensionally (planarly) arranged in an array (matrix). .

  In the light emitting device 70 according to the fifth embodiment, as shown in FIG. 8, a plurality of light emitting diodes 71 are arranged in a matrix (array) as viewed in plan on a lens member 72 made of, for example, polycarbonate. I have. Specifically, 324 light emitting diodes are arranged in a matrix of 18 × 18. The light emitting diode 71 has a structure obtained by removing the plano-concave lens 50 from the light emitting diode according to the first embodiment shown in FIG. 1 or a structure obtained by removing the plano-concave lens 50 from the light emitting diode according to the second embodiment shown in FIG. Having. That is, the light emitting diode 71 of the fifth embodiment has the p-type contact layer 11 (see FIG. 1) or the metal layer 34 which functions as a two-dimensional photonic crystal whose dielectric constant is periodically modulated in the in-plane direction. (See FIG. 3).

  The lens member 72 is composed of a plurality of plano-concave lenses 72a arranged in a matrix (array) as viewed in plan. As shown in FIG. 8, the plano-concave lenses 72a are arranged in a matrix of 3 × 3 (9 in total). Further, each of the plano-concave lenses 72a is arranged at a ratio of one for each of the plurality of (36) light emitting diodes 71. Here, a transparent electrode such as ITO is formed on the surface on the plane side of the plano-concave lens 72a. Electric current is supplied to the light emitting diode 71 from the transparent electrode via an ohmic electrode layer made of metal. The plano-concave lens 72a is an example of the “means for diffusing light emitted from the light emitting diode” of the present invention.

  In the fifth embodiment, as described above, by arranging the plano-concave lens 72a and the light-emitting diodes 71 two-dimensionally (in a planar manner) in an array (matrix), the area from which light is emitted can be increased. . Thereby, it can be easily used as a light source such as illumination.

  In the fifth embodiment, as in the first or second embodiment, the light parallelized in the direction perpendicular to the emission surface by the p-type contact layer 11 or the metal layer 34 functioning as a two-dimensional photonic crystal. As a result, the light extraction efficiency can be improved, and the parallel light can be diffused by the plano-concave lens 72a.

  The other effects of the fifth embodiment are the same as those of the first or second embodiment.

(Sixth embodiment)
FIG. 10 is a cross-sectional view illustrating a structure of a light emitting device according to a sixth embodiment. Referring to FIG. 10, in a light emitting device 80 according to the sixth embodiment, as a means for diffusing light emitted from light emitting diode 81, a light transmissive film in which a diffusing agent 82a made of transparent fine particles is diffused is used. An example using the diffusion sheet 82 will be described.

  That is, in the sixth embodiment, a transparent electrode made of ITO is formed on the surface of the diffusion sheet made of glass or transparent plastic. A plurality of light emitting diodes 81 are arranged in a matrix (array) in plan view on a transparent electrode on the surface of the diffusion sheet 82 via an ohmic electrode layer made of metal. In this case, the light emitting surface of the light emitting diode 81 is attached to the surface of the diffusion sheet 82. The light emitting diode 81 has a structure obtained by removing the plano-concave lens 50 from the light emitting diode according to the first embodiment shown in FIG. 1 or a structure obtained by removing the plano-concave lens 50 from the light emitting diode according to the second embodiment shown in FIG. Having. That is, the light emitting diode 81 of the sixth embodiment has the p-type contact layer 11 (see FIG. 1) or the metal layer 34 functioning as a two-dimensional photonic crystal whose dielectric constant is periodically modulated in the in-plane direction. (See FIG. 3). Accordingly, light that is collimated in the direction perpendicular to the emission surface is emitted from the light emitting diode 81, so that light extraction efficiency is improved.

Here, in the sixth embodiment, a light diffusing agent 82a composed of substantially spherical particles having a particle diameter of about 1 μm to about 20 μm is added to the diffusion sheet 82. The light diffusing agent 82a is made of an inorganic material such as SiNx, TiO ₂ , Al ₂ O ₃ , or polymethyl methacrylate, polyacrylonitrile, polyester, silicone, polyethylene, epoxy, melamine / formaldehyde condensate, benzoguanamine / formaldehyde condensate And organic materials such as melamine / benzoguanamine / formaldehyde condensate. Further, for example, when the diffusion sheet 82 is formed of a transparent plastic film and the light diffusing agent 82a is formed of a melamine-benzoguanamine-formaldehyde condensate, the weight ratio between the plastic film and the melamine-benzoguanamine-formaldehyde condensate is as follows: About 30: about 70.

  In the light emitting element 80 according to the sixth embodiment, as described above, the light emitting region can be enlarged by arranging the light emitting diodes 81 two-dimensionally (in a planar manner) in an array (matrix). . Thereby, it can be easily used as a light source such as illumination.

  In the sixth embodiment, the light-emitting diodes 81 can be easily emitted from the light-emitting diodes 81 arranged in a matrix by attaching the light-emitting diodes 81 to the surface of the diffusion sheet 82 to which the light-diffusing agent 82a is added. Light can be diffused.

  The other effects of the sixth embodiment are the same as those of the first or second embodiment.

(Seventh embodiment)
FIG. 11 is a cross-sectional view illustrating a structure of a light emitting device according to a seventh embodiment. Referring to FIG. 11, in the light emitting device 90 according to the seventh embodiment, unlike the sixth embodiment, as a means for diffusing light emitted from the light emitting diode 91, fine irregularities 93a and 93b are formed on the front and rear surfaces. An example in which the diffusion sheet 93 formed with is formed will be described.

  That is, in the seventh embodiment, as shown in FIG. 11, fine uneven portions 93a and 93b are formed on the front and back surfaces of a light-transmitting diffusion sheet 93 made of a glass sheet or a transparent plastic film. I have. In these fine concave-convex portions 93a and 93b, the pitch (interval) between adjacent concave portions is set to about 200 nm to about 2000 nm, or about 2 μm to about 100 μm. When the pitch (interval) between adjacent recesses is about 200 to about 2000 nm, the light is diffused by the diffraction effect because the interval is equal to or several times the emission wavelength. When the pitch (interval) between adjacent concave portions is about 2 μm to about 100 μm, light is diffused by being refracted by the concave and convex portions 93a and 93b.

  A plurality of light emitting diodes 91 are arranged in a matrix (array) in a plan view on the surface of a support plate 92 made of a material having high reflectance and good heat dissipation such as Al. In this case, the side opposite to the emission surface of the light emitting diode 91 is attached to the surface of the support plate 92. The diffusion sheet 93 is arranged at a predetermined distance from the light emitting diodes 91 so as to face the light emitting surface of the light emitting diodes 91 attached to the surface of the support plate 92.

  The light emitting diode 91 has a structure obtained by removing the plano-concave lens 50 from the light emitting diode according to the first embodiment shown in FIG. 1 or a structure obtained by removing the plano-concave lens 50 from the light emitting diode according to the second embodiment shown in FIG. Having. That is, the light emitting diode 91 of the seventh embodiment has the p-type contact layer 11 (see FIG. 1) or the metal layer 34 which functions as a two-dimensional photonic crystal whose dielectric constant is periodically modulated in the in-plane direction. (See FIG. 3). Thus, the light emitted from the light emitting diode 91 is collimated in the direction perpendicular to the emission surface, so that the light extraction efficiency is improved.

  In the light emitting element 90 according to the seventh embodiment, as described above, by arranging the light emitting diodes 91 two-dimensionally (in a planar manner) in an array (matrix), the light emitting area can be increased. . Thereby, it can be easily used as a light source such as illumination.

  In the seventh embodiment, the light emitted from the light-emitting diodes 91 arranged in a matrix can be easily diffused by providing the diffusion sheet 93 having fine irregularities 93a and 93b on the front and back surfaces. Can be.

  The other effects of the seventh embodiment are the same as those of the first or second embodiment.

(Eighth embodiment)
FIG. 12 is a cross-sectional view illustrating a structure of a lighting device using a light emitting device according to an eighth embodiment. In the eighth embodiment, a lighting device 100 using the light emitting element 70 according to the fifth embodiment will be described with reference to FIG.

  In the lighting device 100 according to the eighth embodiment, as shown in FIG. 12, the plano-concave lens 72a and the light emitting diode 71 according to the fifth embodiment are arrayed on the surface of a reflective plate 101 made of Al which also serves as a heat sink. The light emitting elements 70 arranged two-dimensionally (in a plane) in a matrix are attached. Specifically, the surface of the light emitting element 70 opposite to the light emitting surface of the light emitting diode 71 is attached to the reflector 101. A concave glass plate 102 is mounted so as to surround the light emitting element 70. A white light phosphor layer 103 for white illumination is formed inside the concave glass plate 102.

The white light phosphor layer 103 for white illumination is formed by, for example, mixing phosphor materials of four colors of blue, green, red and yellow. In this case, BaMgAl ₁₀ O ₁₇ : Eu or (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu is used as the blue phosphor material, and ZnS: Cu and Al are used. In addition, Y ₂ O ₂ S: Eu is used as the red phosphor material, and (Y, Gd) ₃ Al ₅ O ₁₂ : Ce is used as the yellow phosphor material. Note that a terminal (not shown) for energizing the light emitting element 70 is provided on the reflection plate 101.

  In the lighting device 100 according to the eighth embodiment, as described above, by using the light emitting diode 71 including the p-type contact layer 11 or the metal layer 34 functioning as a two-dimensional photonic crystal, Since the collimated light can be obtained, the light extraction efficiency of the light emitting diode 71 can be improved. Further, since the parallel light emitted from the light emitting diode 71 can be diffused by the plano-concave lens 72a, diffused light suitable for illumination can be obtained. Further, by using the light-emitting element 70 in which the plano-concave lens 72a and the light-emitting diode 71 are arranged two-dimensionally (in a planar manner) in an array (matrix), the area from which light is emitted can be enlarged, so that the light-emitting element can be easily manufactured. In addition, it is possible to obtain the required brightness as a lighting device.

  It should be noted that the embodiment disclosed this time is an example in all respects and is not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description of the embodiments, and includes all modifications within the scope and meaning equivalent to the terms of the claims.

  For example, in the above embodiment, as a means for diffusing light emitted from the light emitting diode of the present invention, a plano-concave lens, a convex mirror, a diffusion sheet containing a diffusing agent, and a diffusion sheet having fine irregularities are used. The invention is not limited to this, and a lens, a mirror, a diffraction grating, or the like having another shape may be used as a means for diffusing emitted light.

  Further, in the above embodiment, the example in which the photonic crystal is used as the periodically modulated portion of the present invention is described. However, the present invention is not limited to this, and the dielectric constant is periodically modulated. As the portion, a structure other than the photonic crystal may be used.

  In the light emitting device of the fourth embodiment, one convex mirror is arranged for one light emitting diode. However, the present invention is not limited to this, and the convex mirror is provided for each of the plurality of light emitting diodes. The convex mirrors and the light emitting diodes may be arranged in an array (matrix).

  In the lighting device of the eighth embodiment, the example in which the light-emitting element of the fifth embodiment is incorporated has been described. However, the present invention is not limited to this. The light emitting element of the embodiment may be incorporated.

  In the first and second embodiments, a transparent electrode may be formed on the plane side of a plano-concave lens made of an insulator such as glass, and a light emitting diode may be fused on this plane side.

FIG. 2 is a cross-sectional view illustrating a structure of the light emitting device according to the first embodiment. FIG. 2 is a top view for explaining a planar structure of a p-type contact layer according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view illustrating a structure of a light emitting device according to a second embodiment. FIG. 9 is a top view for explaining a planar structure of a metal layer according to a second embodiment of the present invention. FIG. 5 is a cross-sectional view for explaining a manufacturing process of the light emitting device according to the second embodiment shown in FIG. 3. FIG. 9 is a cross-sectional view illustrating a structure of a lighting device using a light emitting device according to a third embodiment of the present invention. FIG. 9 is a cross-sectional view illustrating a structure of a light emitting device according to a fourth embodiment. FIG. 11 is a plan view illustrating a structure of a light emitting device according to a fifth embodiment. FIG. 9 is a cross-sectional view illustrating a structure of a light emitting device according to a fifth embodiment. FIG. 15 is a sectional view illustrating a structure of a light emitting device according to a sixth embodiment; FIG. 15 is a sectional view illustrating a structure of a light emitting device according to a seventh embodiment; It is a sectional view for explaining the structure of the lighting installation using the light emitting element by an 8th embodiment of the present invention. FIG. 9 is a cross-sectional view illustrating a structure of a light emitting diode (light emitting element) in which a conventional photonic crystal is mounted on an emission surface.

Explanation of reference numerals

REFERENCE SIGNS LIST 1 n-type GaN substrate 4, 24 n-type GaN layer 6, 26 n-type cladding layer 7 active layer 8, 28 protective layer 9, 29 p-type cladding layer 10 light-emitting element 11, 31 p-type contact layer 11 a, 34 a through hole 12 , 32 p-type electrode 16, 35 n-side electrode 50, 72 plano-concave lens (means for diffusing light emitted from light emitting diode)
65 Convex mirror (means for diffusing light emitted from light emitting diode)
82, 93 Diffusion sheet (means for diffusing light emitted from light emitting diode)

Claims (19)

A light emitting diode,
A portion formed on a surface substantially parallel to the light emission surface of the light emitting diode, and having a periodically modulated dielectric constant with respect to an in-plane direction of a surface substantially parallel to the light emission surface; ,
A light emitting element provided on a light emitting surface side of the light emitting diode and diffusing light emitted from the light emitting diode.   The light emitting device according to claim 1, wherein the portion where the dielectric constant is periodically modulated is configured by periodically disposing materials having different dielectric constants.   The light emitting device according to claim 1, wherein the portion where the dielectric constant is periodically modulated is made of a photonic crystal.   The light emitting device according to claim 1, wherein the means for diffusing the outgoing light has conductivity.   The light emitting device according to claim 1, wherein the means for diffusing the emitted light includes a lens.   The light emitting device according to claim 5, wherein the means for diffusing the emitted light includes a concave lens.   The light emitting device according to claim 6, wherein the concave lens includes a plano-concave lens having a flat first surface and a concave second surface.   The light emitting device according to any one of claims 1 to 7, further comprising a phosphor provided between the light emitting surface and the means for diffusing the emitted light.   The light emitting device according to any one of claims 1 to 4, wherein the means for diffusing the emitted light includes a convex mirror.   The light emitting device according to any one of claims 1 to 4, wherein the means for diffusing the emitted light includes a light transmitting member in which a light diffusing agent made of substantially transparent fine particles is dispersed.   The light emitting device according to any one of claims 1 to 4, wherein the means for diffusing the emitted light includes a translucent member having fine irregularities on at least one of a front surface and a back surface. The light emitting diode includes a light emitting layer,
The light emitting device according to claim 1, wherein the light emitting layer is made of a nitride semiconductor.   The light emitting device according to claim 1, wherein a plurality of the light emitting diodes are arranged in a matrix when viewed in plan. The means for diffusing the outgoing light includes a lens,
The light emitting device according to claim 13, wherein a plurality of the lenses are arranged in a matrix when viewed in plan. A light emitting diode,
A portion formed on a surface substantially parallel to the light emission surface of the light emitting diode, and having a periodically modulated dielectric constant with respect to an in-plane direction of a surface substantially parallel to the light emission surface; ,
A lighting device, comprising: a light emitting element provided on a light emitting surface side of the light emitting diode and configured to diffuse light emitted from the light emitting diode.   The lighting device according to claim 15, further comprising a white light phosphor disposed at a predetermined distance from the light emitting element and configured to convert light emitted from the light emitting element to white light.   17. The lighting device according to claim 16, wherein the phosphor for white light is formed by mixing phosphor materials of a plurality of colors.   The lighting device according to any one of claims 15 to 17, wherein a plurality of the light-emitting diodes constituting the light-emitting element are arranged in a matrix when viewed in plan. The means for diffusing the outgoing light includes a lens,
The lighting device according to claim 18, wherein the plurality of lenses are arranged in a matrix when viewed in plan.

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