JP2008124168A - Semiconductor light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that semiconductor light emitting elements have a short emission wavelength and some of them emit light in an ultraviolet range and ultraviolet light, when used for illuminating an object, deteriorates the illuminated object. <P>SOLUTION: When a semiconductor light emitting element which emits light in a short wavelength range is used, an ultraviolet light reflection layer is formed on the emission face of the semiconductor light emitting device. When ultraviolet light emitted from the semiconductor light emitting element is used as visible light, a visible light reflection layer is formed closer to the element than to a phosphor layer. When the light emitted from the semiconductor light emitting element is converted into a red-color wavelength region, infrared light is sometimes generated. To cope with this, an infrared light converting phosphor layer is formed outside the ultraviolet light reflection layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor light emitting device and a manufacturing method thereof. More specifically, the present invention relates to a semiconductor light emitting device in which radiation of ultraviolet rays (hereinafter referred to as “UV light”) is reduced.

  Since the semiconductor light emitting device can reduce power consumption, it is expected to be put to practical use for illumination. Currently, semiconductor light-emitting devices are being put into practical use in which the luminous flux per power consumption is more efficient than incandescent bulbs. As a semiconductor light emitting element, a semiconductor light emitting device (hereinafter referred to as UVLED) that emits light in the UV light region having a shorter emission wavelength after blue light emission has been realized has been developed. In addition, semiconductor light emitting devices that emit blue or other colors may include light in the UV light region in the light emission of the semiconductor light emitting element.

  The UV light emitted from these semiconductor light emitting devices may cause an unexpected harmful effect on the object to be illuminated if used without knowing it. That is, since UV light has high radiant energy, for example, when it is used for a long time for illumination of a work of art, color fading may occur.

  In addition, UV light adversely affects not only the object to be illuminated but also the semiconductor light emitting device itself. That is, when a resin in which a phosphor or the like is dispersed is used for the semiconductor light emitting element, the resin may be yellowed and deteriorated. Further, UV light entering the semiconductor light-emitting device from the outside may deteriorate the resin used in the semiconductor light-emitting device and cause yellowing.

  Therefore, for a semiconductor light emitting device, not emitting UV light and not putting UV light into the device is one of the important performances.

In previous reports, there has been an invention in which the periphery of a semiconductor light emitting element is covered with a resin in which a phosphor and a UV light reflecting material are dispersed to reduce the emission of UV light (Patent Document 1).
JP 2004-528714 A

  When the semiconductor light emitting device is used for illumination, there is a problem that not only UV light is not effective but also energy is too large. On the other hand, this can be said to be a problem that a semiconductor light emitting device capable of emitting high energy light with low power cannot be effectively used. Therefore, the present invention has been conceived for the purpose of not only emitting UV light generated by a semiconductor light-emitting element to the outside from the semiconductor light-emitting device but also enabling more effective use of UV light as visible light. .

  In order to solve the above problems, the present invention provides a UV light reflection layer on a light emitting surface of a semiconductor light emitting device, and gradually reduces the refractive index of visible light in each layer from the semiconductor light emitting element to the light emitting surface. .

  In the present invention, a visible light reflecting layer is further provided inside the first phosphor layer. In the present invention, an IR light converting phosphor layer for converting infrared light (hereinafter referred to as “IR light”) into visible light is provided outside the UV light reflecting layer.

  In the present invention, since the UV light reflecting layer is provided on the light emitting surface, it is possible to make it difficult to emit UV light from the semiconductor light emitting device, and the refractive index of visible light gradually decreases from the semiconductor light emitting element toward the light emitting surface. As a result, total reflection between the layers hardly occurs and the light extraction efficiency is improved.

  Further, in the present invention, since the visible light reflecting layer is provided inside the first phosphor layer, the light converted into visible light by the phosphor layer does not return to the semiconductor light emitting element side, and the light utilization efficiency is improved. .

  In addition, since the present invention provides an IR light converting phosphor layer outside the first UV light reflecting layer, the light converted into visible light inside the UV light reflecting layer is wavelength-converted to the IR light region. The light in the IR light region can be returned to visible light, and the utilization efficiency of light in the visible light region is improved.

(Embodiment 1)
FIG. 1 shows a configuration of a semiconductor light emitting device 10 of the present invention. The semiconductor light emitting device 10 of the present invention includes a cup 9, a semiconductor light emitting element 20, a phosphor layer 40, and a UV light reflecting layer 60.

<Semiconductor light emitting device>
The semiconductor light emitting element 20 is a semiconductor light emitting element that emits light including a wavelength in the UV light region. For example, a semiconductor light emitting device that emits blue light having a wavelength in the UV light region includes a GaN-based semiconductor light emitting device. More specifically, a GaN n-type layer, an InGaN active layer, and a GaN p-type layer are laminated in this order on a GaN substrate, and electrodes are arranged on the n-type layer and the p-type layer.

  Moreover, it is not limited to said example, For example, as an element substrate, SiC may be used and insulating sapphire may be used. Further, for example, as the n-type layer and the p-type layer, AlGaN or InGaN may be used, and a buffer layer made of GaN or InGaN may be used between the n-type layer and the element substrate. . For example, the active layer may have a multilayer structure (quantum well structure) in which InGaN and GaN are alternately stacked.

  As the near-UV light-emitting element, zinc oxide (ZnO), zinc sulfide (ZnS), or aluminum nitride (AlN) can be used. Furthermore, in recent years, a semiconductor light emitting device that emits UV light using artificial diamond has been developed and can be used in the present invention. Note that Ga represents gallium, N represents nitrogen, In represents indium, Si represents silicon, C represents carbon, and Al represents aluminum.

<Electrode>
An electrode is applied to the semiconductor light emitting element, and current is supplied from the outside of the semiconductor light emitting device 10. Conventionally known means such as wire bonding and bumps can be used for the electrodes. The present invention is not particularly limited. Also omitted in the figure.

<Cup>
The cup 9 is also called a housing. A cup shape may be used from the beginning, or the side surface portion 8 may be bonded to the bottom portion 7 or the like. Further, a semiconductor light emitting element may be disposed in a cup having a shallow side surface portion and sealed in a shell type with a resin or the like. Further, the side surface may have a height of zero. In this case, the outer shape is such that the semiconductor light emitting element is sealed at the bottom 7 with resin or the like.

  The material of the cup is a material such as resin or aluminum. Increasing the reflectance of the inner surface can increase the light emission amount of the semiconductor light emitting device 10 itself.

<Phosphor layer>
The phosphor layer 40 is a layer in which a phosphor that converts the emission wavelength from the semiconductor light emitting element 20 into visible light is dispersed in a medium such as resin or glass. For example, when the emission color of the semiconductor light emitting device 10 itself is white, the semiconductor light emitting device 10 only needs to include a material that receives blue light from the semiconductor light emitting element 20 and converts the wavelength to yellow and emits it. As such a material, a rare-earth-doped nitride-based or rare-earth-doped oxide-based phosphor is preferable.

More specifically, (Y · Sm) ₃ (Al · Ga) ₅ O ₁₂ : Ce or (Y _0.39 Gd _0.57 Ce _0.03 Sm _0.01 ) ₃ Al ₅ O ₁₂ of the rare earth doped alkaline earth metal sulfide rare earth doped garnet. Rare earth doped alkaline earth metal orthosilicate, rare earth doped thiogallate, rare earth doped aluminate and the like can be suitably used. Further, silicate phosphor _{(Sr 1-a1-b2-} x Ba a1 Ca b2 Eu x) 2SiO 4 or alpha sialon (α-sialon: Eu) Mx (Si, Al) 12 (O, N) 16 yellow emission It may be used as a phosphor.

In addition, as a fluorescent substance converted from UV light to visible light, SCA (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ C ₁₂ : Eu or BAM (Ba, Mg) Al ₁₀ O ₁₇ is used as a blue fluorescent substance. : There is Eu. As red phosphors, there are casun (CaAlSiN ₃ : Eu), and as green phosphors there are β-sialon (Eu) Si _6-z Al _z O _z N _8-z . This is a crystal in which aluminum and oxygen are dissolved in β-type silicon nitride crystal, and z represents the amount of the solid solution. A white luminescent color can be obtained by combining these blue phosphor, red phosphor, and green phosphor.

  Y represents yttrium, Gd represents gadolinium, Sm represents samarium, Ce represents cerium, Sr represents strontium, Ba represents barium, Ca represents calcium, Eu represents europium, Mg represents magnesium, and P represents phosphorus.

<UV light reflection layer>
The UV light reflection layer 60 is a layer that reflects UV light, and is disposed outside the phosphor layer 40. In the present specification, “outside” refers to a direction away from the semiconductor light emitting element 20. For example, in FIG. 1, the upper direction of the drawing corresponds to “outer side”. The UV light emitted from the semiconductor light emitting device 20 is reflected by this layer and returned to the cup. Due to the presence of this layer, the emission of UV light from the semiconductor light emitting device 10 is zero or very small.

As the UV light reflection layer, a layer in which a UV light reflection material such as titanium oxide (TiO ₂ ) or zinc oxide (ZnO) having a small particle diameter is dispersed in a medium is used. These particle diameters are desirably several tens of nm or less.

  The UV light reflection layer may contain bubbles having a size of about several tens of nanometers, and the UV light reflection layer may be formed of a DBR multilayer film.

<Medium>
A medium such as a resin or glass can be used for the phosphor layer 40 and the UV light reflection layer 60. As the resin, a resin mainly composed of a silicone resin, an epoxy resin, and a fluororesin is preferable. In particular, as the non-silicone resin, a siloxane-based resin, a polyolefin, a silicone / epoxy hybrid resin, or the like is preferable. As the glass, glass that can be produced by a sol-gel method is preferable. This is because a curing process at a relatively low temperature is possible at the time of production, and it is easy to disperse particles such as phosphors.

  This glass will be described more specifically. A metal alkoxide, which is a kind of organometallic compound, is used as a starting material, and the solution is hydrolyzed and subjected to condensation polymerization to form a sol, which is further reacted by moisture in the air. It is a solid metal oxide obtained by gelation.

For example, when making silica glass with tetraethoxysilane (Si (OC ₂ H ₅ ) ₄ ), which is a metal alkoxide of silicon, tetraethoxysilane is dissolved in a solvent such as alcohol, and a catalyst such as acid or base and a small amount of water. Is added and mixed sufficiently to form a liquid polysiloxane sol according to the following reaction formula.

Hydrolysis reaction: Si (OC ₂ H ₅ ) ₄ + 4H ₂ O → Si (OH) ₄ + 4C ₂ H ₅ OH
Dehydration condensation reaction: nSi (OH) ₄ → [SiO ₂ ] _n + 2nH ₂ O
Such silica glass has moisture resistance and weather resistance, and is a suitable material for a semiconductor light emitting device. A material in which a UV light reflecting material or phosphor is dispersed in a medium is called a filler.

<Refractive index>
The refractive index in the visible light region of the phosphor layer 40 and the UV light reflecting layer 60 can be adjusted by the concentration of particles dispersed in each layer, and by making the relationship between these refractive indexes a predetermined relationship, the semiconductor The light extraction efficiency of the light emitting device 10 is improved. That is, if the refractive index of the semiconductor light emitting element is n ₂₀ , the refractive index of the phosphor layer 40 is n _40, and the refractive index of the UV light reflecting layer 60 is n ₆₀ , then n ₂₀ > n ₄₀ > n ₆₀ . Note that the inequality sign includes the case where each is equal.

By adjusting the refractive index of each layer in this way, it is possible to prevent a decrease in light extraction efficiency due to total reflection at the interface between the semiconductor light emitting element and the phosphor layer, and between the phosphor layer and the UV light reflecting layer, and high efficiency. A semiconductor light emitting device can be obtained. These refractive indexes are refractive indexes in the visible light region. Specific materials for adjusting the refractive index include titanium oxide (TiO ₂ ) and zinc oxide (ZnO) having a particle size of several tens of nanometers or less. These materials are transparent to visible light having a long wavelength when compared with UV light, and provide a refractive index corresponding to the concentration of content, while working to diffuse and reflect light in the UV light region. . That is, it is also a material constituting the UV light reflection layer.

<Total reflection prevention treatment>
In order to improve the light extraction effect, a total antireflection treatment may be performed between the phosphor layer 40 and the UV light reflection layer 60. The total antireflection treatment is a treatment for forming irregularities having a size of about the wavelength of light used at the interface between the phosphor layer 40 and the UV light reflection layer 60. At the interface subjected to such treatment, total reflection that occurs in a mirror state is unlikely to occur, and more light can pass from the incident side to the emission side. The minute irregularities can be formed using, for example, a nanoimprint technique.

  Specifically, it is produced as follows. First, a semiconductor light emitting element is disposed in a cup, and after connecting electrodes, a filler in which a phosphor is dispersed in a medium is poured into the phosphor layer 40. After the phosphor layer 40 is cured, a mold having minute irregularities is pressed against the surface of the phosphor layer 40 to form minute irregularities. Thereafter, a filler that becomes the UV light reflection layer 60 is poured. After the UV light reflecting layer 60 is cured, the surface may be polished, or an external component such as a lens may be bonded to the UV light reflecting layer 60.

  The formation of minute irregularities is not limited to this method, and a chemical treatment such as wet etching may be performed after the phosphor layer 40 is formed, or a dry etching technique such as ion milling may be used. That is, the minute unevenness does not have to be a uniform size controlled, and may be a set of unevenness having an average size having a distribution.

  Since the semiconductor light emitting device 10 of the present embodiment has the UV light reflection layer 60 on the outside, the UV light to be emitted can be extremely reduced, and the refractive index of the UV light reflection layer 60 can be made fluorescent. Since it is smaller than the refractive index of the body layer 40, the light extraction effect of visible light can be enhanced.

  Throughout this specification, the UV light reflecting layer and the phosphor layer are appropriately used for an antistatic agent, a crystal nucleating agent, inorganic particles, organic particles, a thinning agent, a heat stabilizer, a lubricant, an IR light absorber, UV light, and the like. An absorbent or the like may be added. Note that the structure described in each embodiment of the present specification may be applied to other embodiments as they are.

(Embodiment 2)
FIG. 2 shows a configuration of the semiconductor light emitting device 11 of the present embodiment. In the present embodiment, the phosphor layer 40 of the first embodiment has a layer structure using a plurality of phosphors. In the figure, the case of a three-layer structure will be described. The phosphor layer 40 includes three layers of a first phosphor part 45, a second phosphor part 46, and a third phosphor part 47. The first phosphor portion is made of a phosphor that converts UV light into blue, the second phosphor portion is made of a phosphor that converts blue into green, and the third phosphor portion is made of a phosphor that converts green into red. The semiconductor light emitting element 20 uses a semiconductor light emitting element that emits a wavelength in a blue region from UV light.

  With this configuration, the UV light in the light from the semiconductor light emitting element is converted into blue by the first phosphor part, and then the blue color converted by the first phosphor part and the blue light emitted by the semiconductor light emitting element. Is converted to green by the second light emitter, and the green light is converted to red by the third phosphor. Such a conversion process does not convert from blue to red at a stretch, but passes through small wavelength conversion processes of blue, green, and red, so that the conversion efficiency is good.

  By doing so, RGB light can be developed, and white light as a whole can be generated. In addition, these phosphors may be laminated in this order with phosphors that convert UV light to red, UV light to green, and UV light to blue. In addition, although the structure from three fluorescent substance parts was shown here, the fluorescent substance part should just be plural, and is not limited to three layers.

  In the present embodiment, the phosphors constituting the respective light emitter portions are produced by sequentially pouring into a cup provided with semiconductor light emitting elements. Each luminous body portion is poured with a phosphor dispersed in a volatile solvent. It is preferable that the next light emitter is poured after the solvent of the previous light emitter is blown off.

In this way, sealing resin or glass is poured and fixed from above the laminated light-emitting portion. Thereafter, the UV light reflection layer is produced in the same manner as in the first embodiment. In addition, the light extraction efficiency improves by making the glass poured for sealing contain fine particles for adjusting the refractive index and satisfying n ₂₀ > n ₄₀ > n ₆₀ . Note that the inequality sign includes the case where each is equal. Further, a total reflection preventing process may be performed on the interface between the phosphor layer 40 and the UV light reflection layer 60.

(Embodiment 3)
FIG. 3 shows the configuration of the semiconductor light emitting device 12 of the present embodiment. The cup 9 and the semiconductor light emitting element 20 are the same as those in the first embodiment. In the present embodiment, the phosphor layer 42 is prepared by previously dispersing a phosphor in a medium such as glass into a glass plate shape (hereinafter referred to as “plate shape”). The UV light reflection layer 60 is prepared by coating on the upper surface of the phosphor layer 42.

  That is, the phosphor layer 42 and the UV light reflection layer 60 are produced as a unit. By doing in this way, the error at the time of preparation of the fluorescent substance layer 42 and the UV light reflection layer 60 can be made uniform. The relationship between the refractive indexes of the phosphor layer 42 and the UV light reflecting layer 60 is the same as the relationship between the phosphor layer 40 and the UV light reflecting layer 60 in the first embodiment.

  FIG. 4 shows a case where the phosphor layer 42 is composed of a plurality of phosphor parts shown in the second embodiment. In order to produce such a phosphor layer 42, a first phosphor part to a third phosphor part are sequentially laminated on a thin glass substrate 43. This may be achieved by applying a phosphor dispersed in a solvent onto the glass substrate 43 by spraying or the like. Alternatively, the phosphor may be floated on the surface of a liquid having a large surface tension such as water and the glass substrate 43 may be used to rinse the phosphor.

  The space 70 in the cup 9 may be hollow, or resin or glass may be used. When resin or glass is used, it is preferable to adjust the refractive index by inserting a fine material for controlling the refractive index.

In this case, the refractive index of the filling material is n ₇₀ , the refractive index of the plate-like phosphor layer is n ₄₂ , the refractive index of the glass substrate is n _43, and the refractive index of the UV light reflecting layer is n ₆₀ . Then, the _{n 20> n 70> n 43} > n 42> n 60. The inequality sign includes the case where it is equal.

  Further, a glass ball 72 having a particle diameter of about several micrometers to several tens of micrometers may be disposed on the inner surface of the cup 9. By spreading such glass balls, it is possible to reflect UV light and visible light absorbed by the inner wall and bottom surface of the cup.

  This glass ball is laid on the bottom or side by placing a glass ball in a solvent in a cup after the semiconductor light emitting element is disposed and the electrode treatment is performed. The thickness of the glass ball layer is determined by the concentration mixed in the solvent. As the solvent, organic solvents such as acetone and alcohol, which are volatile and have a low surface tension, are suitable.

  Note that, when the plate-like phosphor layer 42 is manufactured, the surface may be provided with minute irregularities by a total reflection preventing process. The minute irregularities may be formed on either side of the phosphor layer 42.

  Since the semiconductor light emitting device 11 of the present embodiment can be manufactured by integrating the phosphor layer and the UV light reflection layer, it is possible to reduce manufacturing variations. Moreover, the reflectance inside a cup can be improved by spreading a glass ball inside a cup.

(Embodiment 4)
FIG. 5 shows a configuration of the semiconductor light emitting device 13 of the present embodiment. In the present embodiment, the second phosphor layer 80 is provided outside the UV light reflection layer 60 of the semiconductor light emitting device 10 of the first embodiment, and the second UV light reflection layer 65 is further provided outside the second phosphor layer 80. Therefore, hereinafter, the phosphor layer 40 close to the semiconductor light emitting element 20 is referred to as a first phosphor layer 40, and the UV light reflection layer outside the phosphor layer 40 is referred to as a first UV light reflection layer 60.

  In this configuration, the second phosphor layer 80 is sandwiched between the UV light reflection layers. That is, the second phosphor layer 80 can avoid exposure to UV light from the outside and the UV light of the semiconductor light emitting element 20. Therefore, a resin that turns yellow by UV light can also be used as a medium. The first phosphor layer 40 may be composed of a plurality of phosphor parts shown in the second embodiment.

The refractive index in the visible light region of each layer is set so that the refractive index decreases in order from the semiconductor light emitting element as in the previous embodiments. Specifically, the refractive index of the semiconductor light emitting element is n ₂₀ , the refractive index of the phosphor layer 40 is n ₄₀ , the refractive index of the UV light reflecting layer 60 is n _60, and the second phosphor layer 80 is refracted. If the rate is n ₈₀ and the refractive index of the second UV light reflection layer 65 is n ₆₅ , then n ₂₀ > n ₄₀ > n ₆₀ > n ₈₀ > n ₆₅ . Note that the inequality sign includes the case where each is equal.

  In addition, when the medium of the 2nd fluorescent substance layer 80 is made into glass, the 2nd UV light reflection layer 65 does not need to be. This is because, when the medium is made of glass, the second phosphor layer is hardly yellowed by UV light from the outside. In addition, since the fine particles to be mixed for adjusting the refractive index of the second phosphor layer also have a UV light reflection function, when the amount of fine particles to be mixed can sufficiently reflect UV light from the inside and outside The second UV light reflecting layer can be omitted.

  In the semiconductor light emitting device 13, as in the third embodiment, the first phosphor layer is formed in a plate shape, and the UV light reflection layer, the second phosphor layer, and the second UV light reflection layer are formed thereon. It is also possible to prepare an overcoated one in advance and use it. FIG. 6 shows a configuration when the first phosphor layer is plate-shaped. This plate-like phosphor layer may be composed of a plurality of phosphor parts shown in the third embodiment.

  Further, in both the case of FIG. 5 and the case of FIG. 6, the glass balls shown in the third embodiment may be spread around the semiconductor light emitting element 20. Further, a total reflection preventing process may be performed on the boundary between the phosphor layers 40 and 42 and the UV light reflection layer 60, the second phosphor layer 80, and the second UV light reflection layer 65.

(Embodiment 5)
FIG. 7 shows a semiconductor light emitting device 15 of the present embodiment. In the present embodiment, the visible light reflecting layer 90 is provided on the side closer to the semiconductor light emitting element 20 than the first phosphor layer 40. In this configuration, the UV light from the semiconductor light emitting element 20 is converted into visible light by the first phosphor layer 40. Since the conversion to visible light is performed by the phosphor, the light emission direction is light emission to the entire periphery.

  However, the visible light that attempts to return to the semiconductor light emitting element side is reflected by the visible light reflecting layer 90, and thus does not return to the semiconductor light emitting element side. Further, the UV light that has not been converted into visible light by the first phosphor layer 40 is returned to the phosphor layer 40 by the UV light reflection layer 60. That is, the configuration of the present embodiment realizes the technical idea that the UV light from the semiconductor light emitting element is not emitted outside the apparatus and the converted visible light is not returned to the inside of the apparatus. Such an apparatus is very effective in obtaining a light emitting device with high wavelength conversion efficiency when a semiconductor light emitting element that emits UV light is used as a visible light emitting device.

Examples of materials that can be used as the visible light reflection layer include indium tin oxide (ITO), tin oxide (SnO ₂ ), zinc oxide (ZnO ₂ ), zirconium oxide (ZrO ₂ ), and titanium oxide having relatively high refractive index characteristics. A material in which a material such as (TiO ₂ ), hafnium oxide (HfO ₂ ), tantalum oxide (Ta ₂ O ₃ , Ta ₂ O ₅ ) or niobium oxide (Nb ₂ O ₅ ) is dispersed in a medium can be used.

The refractive index of each layer is set in the same manner as in the above embodiment. That is, the refractive index of the semiconductor light emitting element is n ₂₀ , the refractive index of the visible light reflecting layer 90 is n ₉₀ , the refractive index of the phosphor layer 40 is n _40, and the refractive index of the UV light reflecting layer 60 is n ₆₀ . Then, the _{n 20> n 90> n 40} > n 60. Note that the inequality sign includes the case where each is equal.

Further, as shown in FIG. 8, the first phosphor layer may be formed into a plate shape 42. In this case, the visible light reflecting layer 90 may be formed by alternately depositing a thin film of a high refractive index material and a low refractive index material on one of the first phosphor layers 42 by a method such as sputtering or vapor deposition. Here, the high refractive index material includes the above materials including indium tin oxide (ITO), and the low refractive index material includes magnesium fluoride (MgF ₂ ), calcium fluoride (CaF ₂ ), and silicon oxide (SiO ₂ ). ₂ ) etc. can be used. This plate-like phosphor layer may be composed of a plurality of phosphor parts shown in the third embodiment.

When the visible light reflecting layer 90 is manufactured as shown in FIG. 8, the refractive index of the filler filling the space 70 is n ₇₀ , the refractive index of the first phosphor layer 42 is n _42, and n ₂₀ > By making n ₇₀ > n ₉₀ > n ₄₂ > n ₆₀ , the light extraction efficiency is improved. The inequality sign includes the case where they are equal.

  Further, the glass balls shown in the third embodiment may be spread over the first phosphor layer 40 in FIG. 7 and the space 70 in FIG. The semiconductor phosphor device according to the present embodiment may be provided with the second phosphor layer and the second UV light reflection layer described in the fourth embodiment. Moreover, you may perform a total reflection prevention process between each layer.

(Embodiment 6)
FIG. 9 shows the configuration of the semiconductor light emitting device 16 of the present embodiment. The semiconductor light emitting device of the present embodiment includes a semiconductor light emitting element 20, a first phosphor layer 40, a UV light reflecting layer 60, and an IR light converting phosphor layer 95. The semiconductor light emitting device 16 of the present embodiment has an IR light conversion phosphor layer that reconverts light converted to the IR light region into visible light after wavelength conversion by the first phosphor layer. By doing in this way, the semiconductor light emitting element which generate | occur | produces UV light can be utilized efficiently.

As a material that can be used for such an IR light converting phosphor layer, lanthanum fluoride (LaF ₃ ), gadolinium fluoride (GdF ₃ ), yttrium fluoride (YF ₃ ), yttrium chlorate (YOCl, One or more of Y ₃ OCl ₇ ), yttrium aluminum oxide (YAlO ₃ ), and yttrium barium fluoride (BaYF ₅ ) are selected, and ytterbium-erbium (Yb-Er), ytterbium-thulium (Yb) are used as the activator. -Tm) and phosphors selected from one or more of ytterbium-holmium (Yb-Ho). Such a phosphor is dispersed in a medium and used as a filler.

The refractive index of each layer is set in the same manner as in the above embodiment. That is, the refractive index of the semiconductor light emitting element and n _20, the refractive index of the phosphor layer 40 and n _40, the refractive index of the UV light reflecting layer 60 and n _60, n ₉₅ the refractive index of the IR light conversion phosphor layer Then, n ₂₀ > n ₄₀ > n ₆₀ > n ₉₅ . Note that the inequality sign includes the case where each is equal.

  FIG. 10 shows a configuration when the first phosphor layer is plate-shaped. By manufacturing the phosphor layer 40, the UV light reflection layer 60, and the IR light conversion phosphor layer 95 as one body, errors for each product can be reduced. This plate-like phosphor layer may be composed of a plurality of phosphor parts shown in the third embodiment.

In addition, the light extraction efficiency is improved by setting n ₂₀ > n ₇₀ > n ₄₀ > n ₆₀ > n ₉₅ so that the refractive index of the filler filling the space 70 is n ₇₀ . The inequality sign includes equal cases.

  Further, the glass balls shown in the third embodiment may be spread over the first phosphor layer 40 in FIG. 9 and the space 70 in FIG.

  In the semiconductor light emitting device of the present embodiment, the second phosphor layer shown in the fourth embodiment may be disposed inside the IR light conversion phosphor layer. Further, a second UV light reflecting layer may be provided outside the IR light converting phosphor layer. Moreover, you may perform a total reflection prevention process between each layer.

  The present invention does not emit UV light emitted by a semiconductor light emitting element, and can be used for a semiconductor light emitting device that effectively uses such UV light as visible light.

FIG. 5 shows a configuration of the semiconductor light emitting device of the first embodiment. The figure which shows the structure of the semiconductor light-emitting device of Embodiment 2. FIG. 5 shows a configuration of a semiconductor light-emitting device according to a third embodiment. The figure which shows the structure of the semiconductor light-emitting device of Embodiment 3 which made the fluorescent substance layer into plate shape. FIG. 5 is a diagram illustrating a configuration of a semiconductor light emitting device according to a fourth embodiment. The figure which shows the structure of the semiconductor light-emitting device of Embodiment 4 which made the fluorescent substance layer into plate shape. FIG. 6 shows a configuration of a semiconductor light-emitting device according to a fifth embodiment. The figure which shows the structure of the semiconductor light-emitting device of Embodiment 5 which made the fluorescent substance layer into plate shape. FIG. 6 shows a configuration of a semiconductor light-emitting device according to a sixth embodiment. The figure which shows the structure of the semiconductor light-emitting device of Embodiment 6 which made the fluorescent substance layer into plate shape.

Explanation of symbols

20 Semiconductor Light Emitting Element 40 Phosphor Layer 60 UV Light Reflective Layer 65 Second UV Light Reflective Layer 80 Second Phosphor Layer 90 Visible Light Reflective Layer 95 IR Light Conversion Phosphor Layer

Claims (20)

A semiconductor light emitting element that emits at least UV light;
A phosphor layer that is disposed outside the semiconductor light emitting element and contains a phosphor that converts the UV light into visible light;
A UV light reflection layer disposed outside the phosphor layer,
A semiconductor light emitting device in which a refractive index of the phosphor layer is greater than or equal to a refractive index of the UV light reflection layer. The semiconductor light emitting device according to claim 1, further comprising a second phosphor layer outside the UV light reflection layer. The semiconductor light emitting device according to claim 2, wherein the second phosphor layer includes a UV light reflecting material. The semiconductor light-emitting device according to claim 2, further comprising a second UV light reflecting layer outside the second phosphor layer. The semiconductor light-emitting device according to claim 1, wherein a glass ball is disposed around the semiconductor light-emitting element. The semiconductor light emitting device according to claim 1, wherein the phosphor layer includes a plurality of phosphor portions. The semiconductor light emitting device according to claim 1, wherein the phosphor layer has a phosphor dispersed in a glass plate. A semiconductor light emitting element that emits at least UV light;
A visible light reflecting layer disposed outside the semiconductor light emitting device;
A first phosphor layer disposed outside the visible light reflecting layer;
A UV light reflecting layer disposed outside the first phosphor layer;
The refractive index of the visible light reflecting layer is equal to or greater than the refractive index of the first phosphor layer,
The semiconductor light emitting device wherein the refractive index of the first phosphor layer is equal to or greater than the refractive index of the UV light reflecting layer. The semiconductor light-emitting device according to claim 8, further comprising a second phosphor layer outside the UV light reflection layer. The semiconductor light emitting device according to claim 9, wherein the second phosphor layer includes a UV light reflecting material. The semiconductor light emitting device according to claim 9, further comprising a second UV light reflection layer outside the second phosphor layer. The semiconductor light-emitting device according to claim 9, wherein a glass ball is disposed around the semiconductor light-emitting element. The semiconductor light emitting device according to claim 9, wherein the phosphor layer includes a plurality of phosphor portions. The semiconductor light emitting device according to claim 9, wherein the phosphor layer has a phosphor dispersed in a glass plate. A semiconductor light emitting element that emits at least UV light;
A first phosphor layer disposed outside the semiconductor light emitting device;
A UV light reflecting layer disposed outside the first phosphor layer;
An IR light converting phosphor layer disposed outside the UV light reflecting layer;
The refractive index of the first phosphor layer is equal to or greater than the refractive index of the UV light reflection layer,
A semiconductor light emitting device in which a refractive index of the UV light reflecting layer is equal to or larger than a refractive index of the IR light converting phosphor layer. The semiconductor light emitting device according to claim 15, further comprising a second phosphor layer inside the IR light converting phosphor layer. 16. The semiconductor light emitting device according to claim 15, further comprising a second UV light reflecting layer outside the IR light converting phosphor layer. The semiconductor light-emitting device according to claim 15, wherein a glass ball is disposed around the semiconductor light-emitting element. The semiconductor light-emitting device according to claim 15, wherein the phosphor layer includes a plurality of phosphor portions. The semiconductor light-emitting device according to claim 15, wherein the phosphor layer has a phosphor dispersed in a glass plate.

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