JP4263121B2 - LIGHT EMITTING ELEMENT AND LIGHTING DEVICE - Google Patents

Description

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

  Conventionally, there has been known a light emitting diode capable of improving the efficiency of extracting emitted light from the light emitting diode by attaching a photonic crystal on the emitting surface of the light emitting diode (for example, see Non-Patent Documents 1 and 2). ).

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

  In a light emitting diode having a conventional photonic crystal mounted on the emission surface, 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 as shown in FIG. , And a p-type cladding layer 204 made of p-type AlGaAs is sequentially stacked. Thereby, a light emitting diode having a double heterostructure is formed. Further, on the upper surface of the p-type cladding layer 204, a concavo-convex shape having a predetermined width and depth and a stripe shape (elongated shape) arranged periodically 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 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 striped uneven shape having a predetermined width and depth and periodically arranged, and on the upper surface of the uneven shape. In addition, by forming the metal layer 205, a portion whose 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 extraction efficiency of the emitted light can be improved.
“Highly direct light sources using two-dimensional photonic crystal slabs”, Applied Physics Letters, December 2001, vol. 4280-4282 “Strongly directed 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 having the above-described conventional photonic crystal mounted on the emission surface is emitted in a direction perpendicular to the emission surface, it is difficult to obtain diffused light suitable for indoor lighting. There was inconvenience that it was. For this reason, the conventional light-emitting diode in which the photonic crystal is mounted on the emission surface has a problem that it is difficult to use it for illumination.

  One object of the present invention is to provide a light-emitting element that has high light extraction efficiency and can obtain diffused light.

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

  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 formed with the light emitting surface. A portion whose dielectric constant is periodically modulated with respect to the in-plane direction of the surface parallel to the surface, and means for diffusing the light emitted from the light emitting diode, provided on the light emitting surface side of the light emitting diode. Yes.

  In the light emitting device according to the first aspect, as described above, a portion whose dielectric constant is periodically modulated with respect to the in-plane direction is formed on a surface substantially parallel to the light emitting surface of the light emitting diode. By doing so, light emitted from the light-emitting element can be collimated to light perpendicular to the light emission surface, so that light extraction efficiency from the light-emitting diode can be improved. Also, by providing 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, so that the diffused light is emitted. can do. Thereby, a light emitting element having high light extraction efficiency and capable of emitting diffused light can be obtained.

  In the light emitting device according to the first aspect, the portion whose dielectric constant is periodically modulated may be configured by periodically arranging materials having different dielectric constants, and the dielectric constant is periodically modulated. The portion may be made of a photonic crystal. If comprised in this way, the part by which the dielectric constant was modulated periodically can be obtained easily. Note that the portion whose dielectric constant is periodically modulated may be configured by periodically disposing a dielectric and air, or by periodically disposing a dielectric and vacuum.

  In the light emitting device according to the first aspect, preferably, the means for diffusing the emitted light has conductivity. According to this structure, when the light emitting diode and the means for diffusing the emitted light are formed in close contact with each other, electrical connection between the light emitting diode and the means for diffusing the emitted light can be performed. As a result, a current introducing portion to the light emitting diode can be formed in the means for diffusing the emitted light, and thus it is not necessary to directly wire the light emitting diode. As a result, the assembly of the light emitting element is facilitated. In addition, since there is no need to perform wiring on the light exit 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. If comprised in this way, the parallel light radiate | emitted from a light emitting diode can be easily converted into a diffused light. In this case, the means for diffusing the emitted light may include a concave lens. If comprised in this way, since the parallel light radiate | emitted from a light emitting diode can be diffused with a concave lens, parallel light can be easily converted into diffused light. Furthermore, 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 exit surface and the means for diffusing the emitted light. If comprised in this way, since emitted light is scattered by fluorescent substance, diffused light can be obtained more easily. Moreover, 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 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. If comprised in this way, since the parallel light radiate | emitted from a light emitting diode can be reflected and diffused with a convex mirror, parallel light can be easily converted into diffused light.

  In the light emitting device according to the first aspect, the means for diffusing the emitted light may include a translucent member in which a light diffusing agent composed of substantially transparent fine particles is dispersed. If comprised in this way, since the parallel light radiate | emitted from a light emitting diode can be diffused by the translucent member in which the light-diffusion agent was disperse | distributed, parallel light can be easily converted into 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 a fine uneven shape on at least one of the front surface and the back surface. If comprised in this way, since the parallel light radiate | emitted from a light emitting diode can be diffused by the translucent member which has fine uneven | corrugated shape, parallel light can be easily converted into 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-based semiconductor. If comprised in this way, since it is easy to obtain light emission with a short wavelength of the range of blue-ultraviolet and high energy, the intensity | strength of emitted light can be improved.

  In the light-emitting element according to the first aspect, preferably, a plurality of light-emitting diodes are arranged in a matrix in a plan view. With such a configuration, a region where light is emitted can be increased, so that the light-emitting element can be easily used as a light source such as illumination.

  In this case, it is preferable that the means for diffusing the emitted light includes a lens, and a plurality of the lenses are arranged in a matrix in a plan view. If comprised in this way, the light radiate | emitted from the light emitting diode arrange | positioned at matrix form can be spread | diffused easily.

  An illumination device according to a second aspect of the present invention is formed on a light emitting diode and a surface substantially parallel to the light emitting surface of the light emitting diode, and an in-plane direction of the surface substantially parallel to the light emitting surface. The light emitting device includes a portion whose dielectric constant is periodically modulated, and means for diffusing light emitted from the light emitting diode, which is provided on the light emitting surface side of the light emitting diode.

  In the illumination device according to the second aspect, as described above, a portion whose dielectric constant is periodically modulated with respect to 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 emitted from the light-emitting element can be collimated to light perpendicular to the light emission surface, so that light extraction efficiency from the light-emitting diode can be improved. Further, by providing 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, so that the diffused light is emitted. 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 as an illumination device can be obtained. .

  The illumination device according to the second aspect preferably further includes a white light phosphor that is disposed at a predetermined interval from the light emitting element and converts the light emitted from the light emitting element into white light. If comprised in this way, the white light emission suitable for an illuminating device can be obtained easily. In this case, the white light phosphor may be formed by mixing a plurality of phosphor materials having different emission colors.

  In the illumination 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 a plan view. With such a configuration, a region where light is emitted can be increased, so that the light emitting element can be easily used as a light source of the lighting device. In this case, it is preferable that the means for diffusing the emitted light includes a lens, and a plurality of the lenses are arranged in a matrix when seen in a plan view. If comprised in this way, the light radiate | emitted from the light emitting diode arrange | positioned at matrix form can be spread | diffused easily.

  In the inventions 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 the emitted light having conductivity, preferably, the means for diffusing the emitted light having conductivity is formed so as to be in contact with the light emitting side portion of the light emitting diode. ing. If comprised in this way, an electrical connection with a means to diffuse a light emitting diode and emitted light can be performed easily.

  In the light emitting device including the means for diffusing the emitted light having conductivity, preferably, the means for diffusing the emitted light having conductivity is selected from the group consisting of n-type SiC, n-type AlN, and p-type diamond. It consists of at least one material. If a means for diffusing the emitted light is formed of the material as described above, good thermal conductivity can be obtained in addition to the conductivity. Therefore, the heat generated in the light emitting diode via the means for diffusing the 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 concavo-convex shape, the interval between adjacent convex portions in the fine concavo-convex shape may be about 200 nm or more and about 2000 nm or less. If the interval between adjacent convex portions is set to such an interval, the interval is equivalent to the emission wavelength or several times the emission wavelength, so that light can be diffused by the diffraction effect.

  In the light-emitting element including the substantially transparent means having the fine concavo-convex shape, the interval between adjacent convex portions in the fine concavo-convex shape 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 concavo-convex shape portion, so that the light can be easily diffused.

  In the configuration having the plano-concave lens, the light emitting element may be disposed in contact with the flat first surface. If comprised in this way, a light emitting element and a lens can be joined easily. In addition, compared with a case where the light emitting element and the lens are arranged apart from each other, reflection at the light emitting element emission surface and the flat first surface of the lens can be reduced.

  Moreover, the concave lens may be arranged at a rate 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. If comprised in this way, since the area | region which light radiate | emits can be enlarged, it can be easily used as light sources, such as illumination.

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

(First reference form)
Figure 1 is a cross-sectional view for illustrating a structure of a light-emitting device according to the first referential embodiment of the present invention. 2 is a top view for illustrating the planar structure of the p-type contact layer of the first reference embodiment of the present invention. First, referring to FIGS. 1 and 2, a description will be given of the structure of the light emitting device 10 according to the first referential embodiment of the present invention. The light emitting element 10 according to the first reference embodiment includes a light emitting diode and a plano-concave lens 50.

In the light emitting diode of the first reference form, a film of about 5 μm doped with Si on the (0001) Ga surface of the n-type GaN substrate 1 having a thickness of about 200 to 400 μm and about 2 mm square 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 cladding layer 6 made of single crystal n-type Al _0.1 Ga _0.9 N having a thickness of about 0.15 μm doped with Si is formed. Further, on the n-type cladding layer 6, there are six barrier layers made of single-crystal undoped GaN having a thickness of about 5 nm and single-crystal undoped Ga _0.9 In _0.1 having a thickness of about 5 nm. An active layer 7 having a multiple quantum well (MQW) structure in which five well layers made 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 having a thickness of about 0.15 μm doped with Mg. 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 an interval of about 380 nm having a diameter of about 250 nm and approximately 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 “part where the dielectric constant is periodically modulated with respect to the in-plane direction of the surface substantially parallel to the emission surface” of the present invention. .

In the first reference embodiment, the value of the interval (D) is designed by setting the main emission wavelength λ from the light emitting layer (active layer 7) to about 380 nm and the refractive index of the nitride semiconductor to 2.3. This distance (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 that case, fine processing is required. For this reason, in the first reference embodiment, the distance (D) is designed to correspond to about 4/3 ^1/2 times the emission wavelength in the p-type cladding layer 9 so that the processing is easier.

  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. This p-side electrode 12 consists of an ohmic electrode layer having a thickness of about 2 nm made of a Ni layer, a Pd layer or a Pt layer and a transparent oxide oxide made of an ITO film having a thickness of about 200 nm from the lower layer to the upper layer. An electrode layer, a metal reflective layer having a thickness of about 1 μm made of an Al layer, an Ag layer, or an Rh layer, a barrier electrode made of a Pt layer or a Ti layer, and a pad electrode made of an Au layer or an Au—Sn layer It is configured.

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 reference form has the above structure.

On the back surface of the n-side electrode 16 of the light emitting diode, 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. It is 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” in the present invention. The light emitting diode 10 of the first reference form shown in FIG. 1 is configured by the light emitting diode and the plano-concave lens 50 described above.

In the case of forming the illumination apparatus using the light-emitting element 10 according to the first reference embodiment, the submount (heat radiation block) comprising the upper surface of the p-side electrode 12 of the light emitting diodes diamond, from 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 the emission surface, and light is emitted in the direction indicated by the arrow in FIG.

Next, referring to FIG. 1, a description will be given of a manufacturing process of the light emitting device 10 according to the first reference embodiment. First, an n-type GaN substrate 1 having a thickness of about 200 to 400 μm and about 2 mm square 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 made of SiH ₄ , Si was doped on the (0001) Ga surface of the n-type GaN substrate 1 using a MOVPE method (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.

Next, an H ₂ / N ₂ mixed gas containing about 1% to about 3% of H ₂ while maintaining the temperature of the n-type GaN substrate 1 at about 1000 ° C. to about 1200 ° C., preferably about 1150 ° C. About 0.15 μm doped with Si on the n-type GaN layer 4 by using a carrier gas composed of NH ₃ , a source gas composed of TMGa and trimethylaluminum (TMAl), and a dopant gas composed of SiH _4. An n-type clad layer 6 made of single-crystal n-type Al _0.1 Ga _0.9 N having a thickness of 1 mm is grown at a growth rate of about 3 μm / h.

Next, an H ₂ / N ₂ mixed gas containing about 1% to about 5% of H ₂ while maintaining the temperature of the n-type GaN substrate 1 at about 700 ° C. to about 1000 ° C., preferably about 850 ° C. And a source gas consisting of NH ₃ , triethylgallium (TEGa) and trimethylindium (TMIn) to form a single crystal undoped GaN having a film thickness of about 5 nm on the n-type cladding layer 6. An active layer 7 having an MQW structure in which six barrier layers made of 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. At a growth rate of about 0.4 nm / s. Further, a protective 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.

Next, the GaN substrate 1 is composed of a H ₂ / N ₂ mixed gas containing about 1% to about 3% of H ₂ while maintaining the temperature of the GaN substrate 1 at about 1000 ° C. to about 1200 ° C., preferably about 1150 ° C. 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 doped with Mg 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 such as electron beam lithography and an etching technique, it has a cylindrical shape with a diameter of about 250 nm and is approximately 4/3 ^1/2 times the emission wavelength λ in the p-type cladding layer 9. SiN layers (not shown) are formed which are arranged six times symmetrically at an equal interval of about 380 nm. That is, a cylindrical SiN layer is formed at a 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 made of single crystal p-type Ga _0.95 In _0.05 N having a film thickness of about 30 nm is grown on the p-type cladding layer 9 by using the MOVPE method. Let At this time, the GaN substrate 1 is made of a H ₂ / N ₂ mixed gas containing about 1% to about 5% of H ₂ while maintaining the temperature of the GaN substrate 1 at about 700 ° C. to about 1000 ° C., preferably about 850 ° C. 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, the p-type cladding layer 9 and the p-type contact layer 11 are formed under conditions where the hydrogen concentration of the carrier gas is low (H ₂ : about 1% to about 5%), so that the heat treatment is not performed in an 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, the SiN layer (not shown) on the p-type cladding layer 9 is removed to form the p-type contact layer 11 having a through hole 11a as shown in FIG.

Thereafter, a 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 embed 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 having a thickness of about 1 μm made of an Al layer, an Ag layer or an Rh layer, and a Pt layer or Ti The p-side electrode 12 is formed by sequentially forming a barrier electrode made of a layer and a pad electrode made of an Au layer or an Au—Sn layer. Further, an ohmic electrode layer made of an Al layer, a barrier electrode made of a Pt layer, or a Ti layer 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 using a vacuum deposition method or the like. Then, the n-side electrode 16 is formed by sequentially forming a pad electrode made of an Au layer or an Au—Sn layer. In this way, the light emitting diode of the first reference form 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 an n-side electrode 16. 50 is fused so as to face the n-type GaN substrate 1 of the plano-concave lens 50. Thus, the light emitting device 10 according to the first reference embodiment of the present invention is formed.

In the first reference embodiment, as described above, the interval D (see FIG. 2) of 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. In addition, by embedding the ohmic electrode layer and the oxide transparent 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. It can function as a two-dimensional photonic crystal. In addition, 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 that is the emission surface of the light emitting diode, light emitted from the light emitting diode is light perpendicular to the emission surface. The light extraction efficiency can be increased. Further, by providing the plano-concave lens 50 on the exit surface, the exit light collimated in a direction perpendicular to the exit surface by the concave surface of the plano-concave lens 50 can be easily diffused in various directions. it can. As a result, a light emitting diode having high light extraction efficiency and capable of emitting diffused light can be obtained.

In the first reference 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 part such as a heat radiating fin is attached to the plano-concave lens 50, heat can be radiated more easily.

In the first reference 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, thereby emitting light. Electrical connection between the diode and the plano-concave lens 50 can be made. Thereby, since the electrode of a light emitting diode can be formed in the plano-concave lens 50, it is not necessary to wire directly to a light emitting diode. For this reason, since the assembly of the light emitting diode becomes easy, the reliability of the light emitting diode can be improved. In addition, since there is no need to perform wiring on the exit surface, the wiring does not block outgoing light. As a result, the intensity of light emitted from the light emitting diode can be improved.

Further, in the first reference embodiment, if the thickness of the ohmic electrode layer constituting the p-side electrode 12 is formed small, light absorption can be reduced. Further, the oxide transparent electrode layer constituting the p-side electrode 12 can suppress the reaction between the ohmic electrode layer constituting the p-side electrode 12 and the metal reflection layer. Further, the barrier electrode constituting the p-side electrode 12 can suppress the reaction between the metal reflective layer constituting the p-side electrode 12 and the pad electrode. Further, the barrier electrode constituting the n-side electrode 16 can suppress the reaction between the ohmic electrode layer constituting the n-side electrode 16 and the pad electrode.

(Second reference form)
Figure 3 is a cross-sectional view for illustrating a structure of a light-emitting device according to a second referential embodiment of the present invention. 4 is a top view for illustrating the planar structure of the metal layer according to the second referential embodiment of the present invention. First, referring to FIG. 3 and FIG. 4, in the second reference embodiment, unlike the first reference embodiment, a portion (two-dimensional photo) whose permittivity is periodically modulated on the back surface (light emitting surface) side. The structure of the light emitting element 20 in which the nick crystal is formed will be described. The light emitting element 20 according to the second reference embodiment includes a light emitting diode and a plano-concave lens 50.

The light emitting diode according to the second reference embodiment, on the upper surface of the n-type GaN layer 24 of a single crystal doped with Si, n-type single crystal having a thickness of about 40nm doped with Si _Al 0.2 _{Ga 0.8} An n-type multilayer reflective layer 25 is formed, in which N layers and single-crystal n-type GaN layers having a thickness of about 40 nm doped with Si are alternately laminated by 10 layers. On the n-type multilayer reflective layer 25, an n-type cladding layer 26 made of a single crystal n-type Al _0.1 Ga _0.9 N layer having a thickness of about 0.15 μm doped with Si 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 having a thickness of about 0.15 μm doped with Mg. 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 doped with Mg and having a thickness of about 40 nm and a single-crystal layer doped with Mg and having a thickness of about 40 nm are formed. A p-type multilayer reflective layer 30 in which 10 p-type GaN layers are alternately stacked 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 having a thickness of about 30 nm doped with Mg is formed.

  A p-side electrode 32 is formed on the upper surface of the p-type contact layer 31. The p-side electrode 32 is composed of an ohmic electrode layer having a thickness of about 2 nm composed of a Ni layer, a Pd layer or a Pt layer and a transparent oxide made of an ITO film having a thickness of about 200 nm from the lower layer to the upper layer. An electrode layer, a metal reflective layer having a thickness of about 1 μm made of an Al layer, an Ag layer, or an Rh layer, a barrier electrode made of a Pt layer or a Ti layer, and a pad electrode made of 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 made of an Al / Pt / Au layer, which are laminated in this order from the support substrate 33 side in the order of an Al layer, a Pt layer, and an Au layer, are formed. The support substrate 33 is bonded to the p-side electrode 32 via the electrode 37.

Here, in the second reference 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 with 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 “part in which the dielectric constant is periodically modulated with respect to the in-plane direction of the surface substantially parallel to the emission surface” of the present invention. The distance (D) was designed with the main 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. Further, an n-side electrode 35 made of an oxide transparent conductive film such as ITO is formed on the back surface of the metal layer 34 so as to fill the through hole 34 a of the metal layer 34. 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 of the back surface of the n-side electrode 35. The light emitting diode of the second reference form has the above structure.

In the second reference 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. The plane side is fused so as to face the n-side electrode 35. The plano-concave lens 50 is an example of the “means for diffusing emitted light from the light emitting diode” in the present invention. By a light emitting diode and a plano-concave lens as described above, the light emitting element 20 is constituted by the second reference embodiment shown in FIG.

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

Figure 5 is a sectional view for illustrating a manufacturing process of a light emitting device according to the second reference embodiment shown in FIG. Next, with reference to FIGS. 3-5, the manufacturing process of the light emitting element 20 by a 2nd reference form is demonstrated.

First, as shown in FIG. 5, a semiconductor substrate 21 having a surface made of (111) plane (or Ga plane) such as GaP, GaAs or Si is prepared. Then, a selective growth mask 22 made of SiO ₂ , SiN _x or the like interspersed with stripe-shaped openings or hexagonal or circular openings is formed on the upper surface of the semiconductor substrate 21. Thereafter, selective growth is performed by using a source gas composed of NH ₃ , TMGa, and TMAl and a dopant gas composed of SiH ₄ while maintaining the temperature of the semiconductor substrate 21 at about 400 ° C. to about 700 ° C. On the surface of the semiconductor substrate 21 exposed between the masks 22, an n-type low temperature composed of non-single-crystal n-type GaN, AlGaN or AlN having a thickness of about 10 nm to about 50 nm doped with Si using the MOVPE method. A 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 Further, by using a source gas made of TMGa and a dopant gas made of SiH ₄ , the 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.

Next, the semiconductor substrate 21 is composed of an H ₂ / N ₂ mixed gas containing about 1% to about 3% of H ₂ while maintaining the temperature of the semiconductor substrate 21 at about 1000 ° C. to about 1200 ° C., preferably about 1150 ° C. 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 having a thickness of about 40 nm doped with Si 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 having a film thickness of about 40 nm are alternately laminated in layers of about 10 μm / Grow at a growth rate of h.

Next, the semiconductor substrate 21 is composed of an H ₂ / N ₂ mixed gas containing about 1% to about 3% of H ₂ while maintaining the temperature of the semiconductor substrate 21 at about 1000 ° C. to about 1200 ° C., preferably about 1150 ° C. By using a carrier gas, a source gas made of NH ₃ , TMGa and TMAl, and a dopant gas made of SiH ₄ , the n-type multilayer reflective layer 25 has a film thickness of about 0.15 μm doped with Si. An n-type cladding 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.

Next, the semiconductor substrate 21 is composed of an H ₂ / N ₂ mixed gas containing about 1% to about 5% of H ₂ while maintaining the temperature of the semiconductor substrate 21 at about 700 ° C. to about 1000 ° C., preferably about 850 ° C. 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. The SQW active layer 27 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.

Next, the semiconductor substrate 21 is composed of an H ₂ / N ₂ mixed gas containing about 1% to about 3% of H ₂ while maintaining the temperature of the semiconductor substrate 21 at about 1000 ° C. to about 1200 ° C., preferably about 1150 ° C. A single crystal having a thickness of about 0.15 μm doped with Mg on the protective layer 28 by using a carrier gas, a source gas made of NH ₃ , TMGa and TMAl, and a dopant gas made of Cp ₂ Mg. A 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.

Next, the semiconductor substrate 21 is composed of an H ₂ / N ₂ mixed gas containing about 1% to about 3% of H ₂ while maintaining the temperature of the semiconductor substrate 21 at about 1000 ° C. to about 1200 ° C., preferably about 1150 ° C. A single crystal having a film thickness of about 40 nm doped with Mg on the p-type cladding layer 29 by using a carrier gas, a source gas made of NH ₃ , TMGa and TMAl, and a dopant gas made of Cp ₂ Mg. 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 having a film thickness of about 40 nm are alternately laminated by about 3 μm. Grow at a growth rate of / h.

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 them under conditions where the hydrogen concentration of the carrier gas is low (H ₂ : about 1% to about 3%). Without activation, 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.

Next, the semiconductor substrate 21 is composed of an H ₂ / N ₂ mixed gas containing about 1% to about 5% of H ₂ while maintaining the temperature of the semiconductor substrate 21 at about 700 ° C. to about 1000 ° C., preferably about 850 ° C. 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 resulting contact layer 31 is grown at a growth rate of about 0.4 nm / s.

Next, hydrogen is desorbed from the contact layer 31 by annealing in a N ₂ atmosphere while maintaining the temperature of the semiconductor substrate 21 at about 400 ° C. to about 900 ° C., preferably about 800 ° C. Thereby, the hydrogen concentration in the contact layer 31 is set to about 5 × 10 ¹⁸ cm ⁻³ or less. Thereafter, Mg is implanted into the contact layer 31 at an implantation amount of about 1 × 10 ¹⁸ cm ⁻³ to about 1 × 10 ¹⁹ cm ⁻³ , and then annealed in an N ₂ atmosphere at about 800 ° C. 31 is made p-type.

  Thereafter, 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 on the upper surface of the contact layer 31 from the lower layer to the upper layer using a vacuum deposition method or the like, and about 200 nm. An oxide transparent electrode layer made of an ITO film having a thickness of 1 mm, a metal reflective layer having a thickness of about 1 μm made of an Al layer, an Ag layer or an 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.

  Further, 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 to the upper surface of the p-side electrode 32 via the electrode 37.

  Next, after removing the semiconductor substrate 21 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 made 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 using a vacuum deposition method or the like. Thereafter, using a process similar to the process of forming the through hole 11a of the p-type contact layer 11 of the first reference embodiment, the metal layer 34 has a diameter of about 120 nm as shown in FIG. Circular through-holes 34a arranged symmetrically four times are formed at an interval (D) of about 190 nm which is substantially 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 34 a 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 of the back surface of the n-side electrode 35. In this way, the light emitting diode of the second reference form 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 provided on the back surface of the n-side electrode 35 through the pad electrode 36. , So that the plane side faces the n-side electrode 35. In this way, the light emitting element 20 of the second reference embodiment composed of the light emitting diode and the plano-concave lens 50 shown in FIG. 3 is formed.

In the second reference 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 oxide conductive film constituting the n-side electrode 35 in the hole 34a, the metal layer 34 functions as a two-dimensional photonic crystal whose dielectric constant is periodically modulated in the in-plane direction. Can do. By forming the metal layer 34 having such a structure on a surface parallel to the back surface of the n-side electrode 35 which is the emission surface of the light emitting diode, light emission from the light emitting diode is converted into light perpendicular to the emission surface. Since it is made parallel, light extraction efficiency can be increased. Further, 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 having high light extraction efficiency and capable of emitting diffused light.

(3rd reference form)
Figure 6 is a cross-sectional view illustrating the structure of a lighting device using a light emitting device according to a third referential embodiment of the present invention. With reference to FIG. 6, this 3rd reference form demonstrates the illuminating device 40 containing the light emitting diode 41 which comprises the light emitting element 10 of a 1st reference form.

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

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

In the third reference embodiment, as described above, the phosphor 44 is disposed between the emission surface and the plano-concave lens 55, whereby the emission light collimated in the direction perpendicular to the emission surface from the light emitting diode 41 is scattered. Therefore, diffused light can be easily obtained. Moreover, since the emitted light is diffused also by the plano-concave lens 55, the diffused light can be obtained more easily. Further, by configuring the light emitting diode 41 with a nitride-based semiconductor, the light emitting diode 41 emits high-energy light with a short wavelength in the range of blue to ultraviolet and irradiates the phosphor 44. Thereby, since the wavelength of the emitted light can be efficiently converted to a wavelength different from that of the emitted light using the phosphor 44, white light emission suitable for illumination can be obtained by combining various phosphors. be able to.

(4th reference form)
Figure 7 is a cross-sectional view for illustrating a structure of a light-emitting device according to a fourth reference embodiment of the present invention. Referring to FIG. 7, in the fourth reference embodiment, an example in which a convex mirror is used instead of the plano-concave lens of the second reference embodiment will be described. The remaining structure of the fourth reference embodiment are the same as those of the second reference embodiment.

The light emitting device 60 according to the fourth reference embodiment has a structure in which the plano-concave lens 50 is removed from the light emitting device 20 of the second reference embodiment shown in FIG. That is, the light emitting diode of the fourth reference embodiment includes a 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 disposed at a predetermined interval 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” in the present invention.

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

In the light emitting device 60 according to the fourth reference 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 the 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 the structure of a light emitting device according to the fifth embodiment. FIG. 9 is a cross-sectional view illustrating a structure of a light emitting device according to the fifth embodiment. With reference to FIGS. 8 and 9, in the light emitting device 70 according to the fifth embodiment, an example in which the plano-concave lenses 72 a and the light emitting diodes 71 are arranged in an array (matrix) in a two-dimensional manner (planar) will be described. .

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 a plan view on a lens member 72 made of, for example, polycarbonate. Yes. Specifically, 324 light emitting diodes are arranged in a matrix of 18 × 18. The light emitting diode 71 has a structure in which the planoconcave lens 50 is removed from the light emitting diode according to the first reference form shown in FIG. 1, or a structure in which the planoconcave lens 50 is removed from the light emitting diode of the second reference form shown in FIG. Have That is, the light-emitting diode 71 of the fifth embodiment has a p-type contact layer 11 (see FIG. 1) or a metal layer 34 that 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 includes 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). Each plano-concave lens 72a is arranged at a rate of one for each of a plurality (36) of light emitting diodes 71. Here, a transparent electrode such as ITO is formed on the surface of the plano-concave lens 72a on the plane side. The light emitting diode 71 is energized from the transparent electrode through an ohmic electrode layer made of metal. The plano-concave lens 72a is an example of the “means for diffusing emitted light from the light emitting diode” in the present invention.

  In the fifth embodiment, as described above, by arranging the plano-concave lenses 72a and the light emitting diodes 71 in an array (matrix shape) two-dimensionally (planarly), it is possible to increase the light emission region. . Thereby, it can be easily used as a light source such as illumination.

In the fifth embodiment, similarly to the first or second reference embodiment, the p-type contact layer 11 or the metal layer 34 functioning as a two-dimensional photonic crystal allows light paralleled in the direction perpendicular to the emission surface to be emitted. Therefore, the light extraction efficiency can be improved, and the collimated light can be diffused by the plano-concave lens 72a.

The remaining effects of the fifth embodiment are similar to those of the aforementioned first or second reference embodiment.

(6th reference form)
Figure 10 is a cross-sectional view for illustrating the structure of a light emitting device according to a sixth reference embodiment of the present invention. Referring to FIG. 10, in the light emitting device 80 according to the sixth reference embodiment, as a means for diffusing the light emitted from the light emitting diode 81, it is made of a translucent film in which a diffusing agent 82a made of transparent fine particles is diffused. An example using the diffusion sheet 82 will be described.

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

Here, in the sixth reference embodiment, a light diffusing agent 82 a made of substantially spherical particles having a particle diameter of about 1 μm to about 20 μm is added to the diffusion sheet 82. This light diffusing agent 82a can be 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. For example, the weight ratio of the plastic film and the melamine / benzoguanamine / formaldehyde condensate when the diffusion sheet 82 is composed of a transparent plastic film and the light diffusing agent 82a is composed of melamine / benzoguanamine / formaldehyde condensate is: About 30:70.

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

Further, in the sixth reference embodiment, the light emitting diode 81 is easily emitted from the light emitting diodes 81 arranged in a matrix by attaching the light emitting surface side of the light emitting diode 81 to the surface of the diffusion sheet 82 to which the light diffusing agent 82a is added. Can diffuse light.

The remaining effects of the sixth reference embodiment are similar to those of the aforementioned first or second reference embodiment.

(7th reference form)
Figure 11 is a cross-sectional view for illustrating the structure of a light emitting device according to a seventh reference embodiment of the present invention. Referring to FIG. 11, in the light emitting element 90 according to the seventh reference embodiment, unlike the sixth reference embodiment, as the means for diffusing the light emitted from the light emitting diode 91, fine uneven shapes 93a and 93b are formed on the front and back surfaces. An example in which the diffusion sheet 93 formed with the above is used will be described.

That is, in the seventh reference embodiment, as shown in FIG. 11, fine uneven portions 93a and 93b are formed on the front and back surfaces of a translucent diffusion sheet 93 made of a glass sheet or a transparent plastic film. Yes. In the fine uneven-shaped portions 93a and 93b, the pitch (interval) between adjacent recesses 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 interval is equivalent to the emission wavelength or several times the emission wavelength, so that light is diffused by the diffraction effect. In addition, when the pitch (interval) between the adjacent concave portions is about 2 μm to about 100 μm, the light is refracted by the concave and convex portions 93 a and 93 b to diffuse the light.

  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 reflectivity such as Al and good heat dissipation. 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 disposed at a predetermined interval from the light emitting diode 91 so as to face the light emitting surface of the light emitting diode 91 attached to the surface of the support plate 92.

The light emitting diode 91 has a structure in which the plano-concave lens 50 is removed from the light emitting diode according to the first reference form shown in FIG. 1, or a structure in which the plano-concave lens 50 is removed from the light emitting diode of the second reference form shown in FIG. Have That is, the light emitting diode 91 of the seventh reference embodiment, (see FIG. 1) p-type contact layer 11 which functions as a periodic dielectric constant two-dimensional photonic crystal that has been modulated with respect to the in-plane direction or the metal layer 34 (See FIG. 3). Thereby, since the light collimated in the direction perpendicular to the emission surface is emitted from the light emitting diode 91, the light extraction efficiency is improved.

In the light emitting device 90 according to the seventh reference embodiment, as described above, the light emitting diodes 91 are two-dimensionally (planarly) arranged in an array form (matrix form), so that a region where light is emitted can be increased. . Thereby, it can be easily used as a light source such as illumination.

Further, in the seventh reference 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 uneven shapes 93a and 93b on the front and back surfaces. Can do.

The remaining effects of the seventh reference embodiment are similar to those of the aforementioned first or second reference embodiment.

(Eighth embodiment)
FIG. 12 is a cross-sectional view illustrating the structure of a lighting device using a light emitting device according to an eighth embodiment of the present invention. With reference to FIG. 12, this 8th Embodiment demonstrates the illuminating device 100 using the light emitting element 70 by the said 5th Embodiment.

  In the illumination device 100 according to the eighth embodiment, as shown in FIG. 12, the plano-concave lens 72a and the light emitting diode 71 of the fifth embodiment are arranged in an array on the surface of the reflection plate 101 made of Al that also serves as a heat sink. Light emitting elements 70 arranged in a two-dimensional (planar) manner in a matrix form 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 reflecting plate 101. A concave glass plate 102 is mounted so as to surround the light emitting element 70. Inside the concave glass plate 102, a white light phosphor layer 103 for white illumination is formed.

The white light phosphor layer 103 for white illumination is formed, for example, by 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. Further, 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. The reflector 101 is provided with a terminal (not shown) for energizing the light emitting element 70.

  In the illumination 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 that functions as a two-dimensional photonic crystal, the light emitting diode 71 is perpendicular to the emission surface. Since collimated light can be obtained, the light extraction efficiency of the light emitting diode 71 can be improved. In addition, 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 two-dimensionally (planarly) arranged in an array (matrix shape), the light emission area can be increased, so that it is easy. In addition, the brightness required for the lighting device can be obtained.

In addition, it should be thought that the reference form and embodiment disclosed this time are examples in all points, and are not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

For example, in the above Reference Embodiment and the embodiment, as a means for diffusing the light emitted from the light-emitting diodes, a plano-concave lens, a convex mirror, a diffusion sheet including a diffusing agent, and has used the diffusion sheet having fine irregularities The present 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 outgoing light.

In the reference embodiment and the embodiment described above, an example in which a photonic crystal is used as a portion where the dielectric constant is periodically modulated according to the present invention is shown. However, the present invention is not limited thereto, and the dielectric constant is periodically generated. A structure other than the photonic crystal may be used as the portion where is modulated.

Further, in the light emitting element of the fourth reference form, one convex mirror is arranged for one light emitting diode, but this reference form is not limited to this, and the convex mirror is provided for each of the plurality of light emitting diodes. They may be arranged at a rate of one by one, or a plurality of convex mirrors and light emitting diodes may be arranged in an array (matrix).

In the first and second reference 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 the plane side.

It is sectional drawing for demonstrating the structure of the light emitting element by the 1st reference form of this invention. It is a top view for demonstrating the planar structure of the p-type contact layer by the 1st reference form of this invention. It is sectional drawing for demonstrating the structure of the light emitting element by the 2nd reference form of this invention. It is a top view for demonstrating the planar structure of the metal layer by the 2nd reference form of this invention. It is sectional drawing for demonstrating the manufacturing process of the light emitting element by the 2nd reference form shown in FIG. It is sectional drawing for demonstrating the structure of the illuminating device using the light emitting element by the 3rd reference form of this invention. It is sectional drawing for demonstrating the structure of the light emitting element by the 4th reference form of this invention. It is a top view for demonstrating the structure of the light emitting element by 5th Embodiment of this invention. FIG. 10 is a cross-sectional view illustrating a structure of a light emitting device according to a fifth embodiment of the present invention. It is sectional drawing for demonstrating the structure of the light emitting element by the 6th reference form of this invention. It is sectional drawing for demonstrating the structure of the light emitting element by the 7th reference form of this invention. It is sectional drawing for demonstrating the structure of the illuminating device using the light emitting element by 8th Embodiment of this invention. It is sectional drawing for demonstrating the structure of the light emitting diode (light emitting element) which attached the conventional photonic crystal on the output surface.

Explanation of symbols

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 11a, 34a through-hole 12 , 32 p-type electrode 16, 35 n-side electrode 50, 72 Plano-concave lens (means for diffusing light emitted from the light-emitting diode)
65 Convex mirror (means for diffusing the light emitted from the light emitting diode)
82, 93 Diffusion sheet (means for diffusing the light emitted from the light emitting diode)

Claims (13)

A light emitting surface in which a plurality of light emitting diodes are arranged in a plane in a matrix;
A portion that is formed on a surface substantially parallel to the light exit surface and whose dielectric constant is periodically modulated with respect to an in-plane direction of the surface substantially parallel to the light exit surface;
Is provided on the emission side of the light from the light emitting surface, and means for diffusing the light emitted from the light emitting surface,
The means for diffusing the light is a light emitting element comprising a lens disposed at a ratio of one to a plurality of light emitting diodes disposed on the light emitting surface .   The light emitting device according to claim 1, wherein the portion whose dielectric constant is periodically modulated is configured by periodically arranging materials having different dielectric constants.   The light emitting device according to claim 1, wherein the portion whose permittivity is periodically modulated is made of a photonic crystal.   The light emitting element according to claim 1, wherein the light diffusing means has conductivity. The light-emitting element according to claim 1, wherein the lens includes a concave lens . The light-emitting element according to claim 5 , wherein the concave lens includes a plano-concave lens having a flat first surface and a concave second surface. Further comprising a phosphor provided between the means for spreading the light and the light emitting surface, the light emitting device according to any one of claims 1-6. The light emitting diode includes a light emitting layer,
The light emitting layer is made of a nitride semiconductor light emitting device according to any one of claims 1-7. The lens is in a plane, and a plurality arranged in a matrix, light emitting device according to any one of claims 1-8. A light emitting surface in which a plurality of light emitting diodes are arranged in a plane in a matrix;
A portion that is formed on a surface substantially parallel to the light exit surface, and whose dielectric constant is periodically modulated with respect to an in-plane direction of the surface substantially parallel to the light exit surface;
Provided on the light emission side from the light emission surface, and means for diffusing the light emitted from the light emission surface ,
The illuminating apparatus comprising a light emitting element , wherein the means for diffusing the light includes a lens disposed at a ratio of one to a plurality of light emitting diodes disposed on the light emitting surface . The lighting device according to claim 10 , further comprising a white light phosphor that is disposed at a predetermined interval from the light emitting element and converts light emitted from the light emitting element into white light. The lighting device according to claim 11 , wherein the white light phosphor is formed by mixing phosphor materials of a plurality of colors. The lighting device according to claim 10, wherein a plurality of the lenses are arranged in a matrix in a planar manner.

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