JP5008631B2 - Phosphor, method for producing the same, and light emitting device using the same - Google Patents

Description

  The present invention relates to a crystalline phosphor having a columnar shape, a method for producing the same, and a light emitting device using the same.

  In recent years, phosphors using a semiconductor crystal as a host material have been studied extensively, and the development of nanoparticle phosphors having increased luminous efficiency by the quantum size effect has been progressing. In particular, ZnS and CdSe, which are II-VI group compound semiconductors, can be synthesized at room temperature as shown in Non-Patent Document 1 below, and have a uniform particle size by a synthesis method such as a coprecipitation method or a reverse micelle method. Since nano-particles can be synthesized in large quantities, research into practical use as phosphor materials is progressing.

  However, the nanoparticle phosphor easily aggregates, and the increase in the non-surface area increases the emission killer due to surface defects and decreases the emission characteristics. Therefore, Patent Document 1 below discloses a technique for obtaining the effects of monodispersion and defect capping by modifying the surface of nanoparticles with a surface stabilizer.

  On the other hand, nitride semiconductors such as GaN, InN, and AlN, which are III-V group compound semiconductors, have excellent emission characteristics and are known as high-luminance blue-violet light-emitting element materials. As shown in the following Patent Documents 2 to 4, a technique for manufacturing a phosphor using this nitride semiconductor has been disclosed in recent years.

  However, since a nitride semiconductor is a chemically stable compound, a high reaction temperature is required for synthesis. For this reason, the synthesis method by the reverse micelle method shown in the following non-patent document 1 and the surface modification method by the stabilizer shown in the following patent document 1 are both applied because they use materials that are easily pyrolyzed. I can't.

  On the other hand, according to the methods disclosed in Patent Documents 2 to 4 below, it is impossible to obtain phosphor particles having a quantum size effect (specifically, having a particle size not more than twice the Bohr radius). In particular, in the method of obtaining phosphor particles by heteroepitaxially growing a semiconductor around the core particles, crystals tend to grow in a specific orientation. There is a problem that it must be large. Also, neither physical pulverization of the particles nor surface modification by a post-process can dramatically increase the luminous efficiency, and the manufacturing process is laborious and expensive.

As described above, the conventional nitride phosphor and the manufacturing method thereof cannot efficiently obtain a nanoparticle phosphor excellent in luminous efficiency.
JP 2003-226521 A JP 2000-8035 A JP 2003-34510 A JP 2003-63810 A Tetsuhiko Isobe “High quantum efficiency of light emission by nano-size phosphor material” Applied Physics Vol. 70, No. 9, p. 1087-1091 (2001)

The present invention has been made in order to solve the above-described problems of the prior art, and the object thereof is to use a nitride semiconductor material and to produce a phosphor having excellent light emission characteristics and to produce the phosphor with a high yield. It is an object to provide a method and a light emitting device using the method.

  The present invention is a phosphor composed of a columnar crystal having a diameter of 3 nm or less, wherein a light emitting region and a light absorbing region are defined in the columnar crystal, and the light emitting region and the light absorbing region are formed of the columnar crystal. Provided is a phosphor characterized by being adjacent in the longitudinal direction.

Preferably, the length of the light emitting region is 3 nm or less.
Preferably, the light emitting region is sandwiched between the light absorption regions.

Preferably, there are two or more light emitting regions.
Preferably, the light emitting region includes a light emitting region exhibiting red, a light emitting region exhibiting green, and a light emitting region exhibiting blue, and the red, green, and blue are mixed to exhibit white as a whole.

  Preferably, the columnar crystal includes a group III nitride, and the structure of the crystal is a wurtzite structure.

  Preferably, the plane including the diameter of the columnar crystal is the (0001) plane, and the longitudinal direction is the <0001> direction.

Preferably, a light emission center is added to the light emitting region.
Preferably, the emission center is a rare earth element.

Preferably, an element that controls light absorption is added to the absorption region.
The present invention also includes a step of forming a dielectric thin film on a substrate, a step of growing a columnar crystal phosphor on the dielectric thin film, and a step of detaching the columnar crystal phosphor from the substrate by etching. Provided is a method for producing a phosphor.

Preferably, the dielectric is silicon nitride or silicon oxide.
The present invention also provides a light emitting device characterized in that the phosphor described in any one of the above is installed at a predetermined density in parallel on a substrate.

  According to the phosphor of the present invention, good luminous efficiency and luminous intensity can be obtained. Moreover, according to the manufacturing method of the fluorescent substance of this invention, it can manufacture with a high yield. Moreover, according to the light emitting device of the present invention, the light emission efficiency is improved as compared with the case where the light emitter is formed in a planar shape.

  The phosphor of the present invention is composed of a columnar crystal having a diameter of 3 nm or less, and a light emitting region and a light absorbing region are defined in the columnar crystal, and the light emitting region and the light absorbing region are in the longitudinal direction of the columnar crystal. It is characterized by being adjacent. Thus, by setting the diameter of the columnar crystal to 3 nm or less, the light emission efficiency can be remarkably improved by the quantum size effect, and the light emission efficiency can be prevented from being lowered by the internal electric field. Further, when the diameter is 3 nm or less, a fine light emission pattern can be obtained, and color unevenness does not occur even when the phosphor of the present invention is used for a display or white illumination. More preferably, it is 2.5 nm or less.

  In the phosphor of the present invention, the columnar crystal is a columnar crystal grown in a specific direction from a nano-sized microregion having a cross section perpendicular to the longitudinal direction. Further, the columnar crystal is provided with a light absorption region and a light emitting region adjacent thereto. Here, the light absorption region is a region that absorbs light, and the wavelength to be absorbed can be adjusted by appropriately designing the material of the light absorption region. The light emitting region is a region that converts energy moved from the light absorption region into light and emits light to the outside. The color of light emission can be adjusted by the energy moved from the light absorption region and the material constituting the light emission region.

  Hereinafter, the phosphor of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view of the phosphor of the present invention. In FIG. 1, the phosphor 1 is composed of a columnar semiconductor single crystal having a diameter of 3 nm or less as described above. The phosphor 1 is provided with a light absorption region 2 and a light emitting region 3 sandwiched therebetween.

  In the present invention, the semiconductor material constituting the phosphor 1 is preferably a group III nitride semiconductor composed of GaN, AlN, InN, and mixed crystals thereof. This is because these semiconductor materials are direct transition type wide gap semiconductors, and can achieve RGB (red, green, and blue) light emission necessary for developing various light emission colors.

  In the present invention, the light emitting region 3 is preferably 3 nm or less in diameter and length. If it exceeds 3 nm, the quantum size effect is reduced, and the shielding effect by the internal electric field becomes remarkable, resulting in a decrease in light emission efficiency. Since the quantum size effect can be exhibited remarkably by setting it to 3 nm or less, higher luminous efficiency can be achieved. The diameter and length of the light emitting region are obtained by measuring the diameter of the cross section and the length of the columnar crystal in the longitudinal direction. For example, the shape of the columnar crystal is observed from the cross section and the side surface using a scanning electron microscope. Can be measured.

  The excitation light source for exciting the phosphor of the present invention uses a light source that emits blue-violet (here defined as 380 to 450 nm) in addition to the conventionally used ultraviolet light (defined here as 200 to 380 nm). Can do. Among these, a blue-violet semiconductor light emitting element using a group III nitride semiconductor is preferable because it is excellent in luminous efficiency and power saving and can be reduced in size and weight.

In order to absorb such ultraviolet to blue-violet excitation light, the light absorption region 2 is preferably adjusted as a band gap in a range of 2.5 eV to 6.5 eV, and such band gap control is possible. As such a semiconductor material, Al _x Ga _1-x N (0 ≦ x ≦ 1) or In _y Ga _1-y N (0 ≦ y ≦ 0.15) mixed crystal is preferably used.

For example, when an ultraviolet light source having a wavelength of 300 nm is used for the excitation light, if the band gap of the light absorption region 2 is smaller than 4.1 eV, the excitation light of the wavelength can be absorbed. Therefore, the light absorption region 2 has an Al composition ratio x. It is preferably composed of Al _x Ga _1-x N of 0.3 or less.

Further, when a blue-violet light source having a wavelength of 405 nm is used as the excitation light, the light absorption region 2 can absorb the excitation light having the wavelength if the band gap of the light absorption region 2 is smaller than 3.0 eV. Is preferably 0.08 or more of In _y Ga _1-y N.

Further, when the phosphor of the present invention is used for the purpose of obtaining white light emission by mixing RGB, it is preferable not to absorb a blue component (450 to 480 nm) for obtaining white light emission excellent in color rendering. The band gap of region 2 is preferably larger than the band gap of 2.75 eV corresponding to a wavelength of 450 nm. That is, when the light absorption region 2 is composed of In _y Ga _1-y N, the In composition ratio y is preferably 0.15 or less.

  The diameter and length of the light absorption region 2 are preferably large in order to increase the amount of light absorption, but the phosphor size increases with volume increase, and fine color development becomes difficult. It is preferable to adjust the length of the light absorption region so that the length of 1 in the longitudinal direction is 1 μm or less. The diameter and length of the light absorption region can be measured in the same manner as the light emitting region.

  In the present invention, the light emitting region 3 is preferably sandwiched by the light absorbing region 2 as shown in FIG. Specifically, the light emitting region 3 is preferably sandwiched between two light absorption regions 2 in the longitudinal direction of the phosphor 1. Since both surfaces of the light emitting region 3 perpendicular to the longitudinal direction are in contact with the light absorbing region 2, energy transport efficiency can be improved, and surface defects can be reduced, thereby improving light emitting efficiency.

  Moreover, in this invention, as shown in FIG. 2, the light emission area | region 3 may exist in two or more places in the columnar crystal which comprises the fluorescent substance 1. As shown in FIG. Further, these two or more light emitting regions 2 can emit light at different light emission wavelengths. In the case of FIG. 2, since there are three light emitting regions 2, there are four light absorbing regions 2 that sandwich the light emitting region 3.

  As described above, by providing two or more light emitting regions 3 in the phosphor 1, the energy of the light absorbing region 2 can be moved to the light emitting region 3 without waste. Further, by providing a plurality of light emitting regions 3, it is possible to emit different light from one phosphor. In particular, by including a light emitting region that emits light of three primary colors, red, green, and blue, these colors are mixed and white light can be emitted from one phosphor 1. Therefore, the trouble of mixing a plurality of phosphors is not required, the manufacturing cost can be reduced, and a white phosphor with high cost performance can be obtained.

  The wavelength of the phosphor having high visibility and excellent color rendering when white light emission is obtained is preferably such that red light emission has a peak wavelength in the range of 600 to 670 nm, and green light emission has a peak wavelength of 500 to 550 nm. It is preferable that the blue light emission has a peak wavelength in the range of 450 to 480 nm.

  When there are a plurality of light emitting regions as described above and these emit light at different wavelengths, several methods can be applied to control the light emission wavelength. For example, the substantial band gap may be changed by controlling the composition ratio of the light emitting region.

The group III nitride semiconductor for obtaining the preferable emission wavelength peak shown above is preferably an In _z Ga _1-z N (0 ≦ z ≦ 1) mixed crystal, and the above-described preferable RGB emission peak wavelengths are arbitrarily controlled. can do.

  Further, by adding an impurity, the wavelength may be controlled by light emission via the impurity. As an impurity used for such a purpose, when a group III nitride semiconductor material is used as the columnar crystal phosphor, Si can be used as a donor, and Zn or Mg can be used as an acceptor.

  Since the level due to the donor impurity is shallower than the band gap, it is possible to finely control the emission peak wavelength from the band gap. On the other hand, since the acceptor level is deeper than the donor level, the emission peak wavelength can be greatly varied.

  Furthermore, when the emission peak wavelength is controlled by adding an emission center that emits light by the inner-shell transition, the emission efficiency is higher than the above-described interband transition and transition through the impurity level, and the emission wavelength depends on the temperature and excitation conditions. It is preferable that there is little fluctuation. Rare earth elements are suitable for such an emission center, and specific examples include Nd, Sm, Eu, Gd, Tb, Dy, and Yb.

In the case of light emission using inner-shell transition, the emission peak wavelength is determined by the kind of rare earth element and the ionic valence, regardless of the band gap of the base group III nitride semiconductor. In order to obtain the above-mentioned preferable emission peak wavelength, Sm ³⁺ and Eu ³⁺ are particularly preferable for the red phosphor, Tb ³⁺ and Eu ²⁺ are particularly preferable for the green phosphor, and Ce for the blue phosphor. ³⁺ and Tm ³⁺ are particularly preferred.

  In the present invention, the absorption wavelength may be controlled by adding impurities to the light absorption region 2. As such impurities, the above-mentioned donor-acceptor impurities and rare-earth luminescent centers can be used as absorbing impurities.

  When the crystal structure of the phosphor 1 of the present invention is a wurtzite structure and the longitudinal direction is the <0001> direction, the cross section cut by a plane perpendicular to the direction is the (0001) plane of the wurtzite structure. It is preferable that Thereby, since the <0001> direction is an easy orientation axis, it can be easily formed into a columnar crystal, and can be easily manufactured into a columnar phosphor having a uniform diameter.

  That is, the cross-sectional shape of the phosphor 1 is a hexagonal shape reflecting the wurtzite crystal structure, and the crystal plane of the cross section is the (0001) plane. On the other hand, the longitudinal direction is the <0001> direction perpendicular thereto. Any of the above-described semiconductor materials used for the phosphor 1 includes a wurtzite crystal structure, and is oriented and grown stably from the (0001) plane toward the <0001> direction. Therefore, columnar crystals can be easily obtained in the phosphor of the present invention. As a method for confirming the cross-sectional shape, it can be confirmed by observing the shape of the columnar crystal from the cross-section and the side surface using a scanning electron microscope.

  Next, a method for manufacturing the phosphor of the present invention will be described. The phosphor production method of the present invention includes a step of forming a dielectric thin film on a substrate, a step of growing a columnar crystal phosphor on the dielectric thin film, and removing the columnar crystal phosphor from the substrate by etching. Separating.

  Thereby, a columnar crystal having a specific orientation can be epitaxially grown from the crystal nucleus of the dielectric thin film. Further, by using etching as a step of detaching the phosphor from the substrate, a minute phosphor made of a columnar crystal can be easily detached. Hereinafter, the method for producing the phosphor of the present invention will be described with reference to the drawings.

FIG. 3 is a schematic cross-sectional view for explaining each step of the phosphor manufacturing process of the present invention.
First, a substrate 10 is prepared as shown in FIG. 3A, and a dielectric film 11 is formed on the surface of the substrate 10 as shown in FIG. The substrate material is preferably a (111) plane Si substrate, a (0001) plane sapphire substrate, a (0001) plane or a (111) plane SiC substrate. The thickness of the substrate 10 is preferably 100 μm or more and less than 1 mm. If the thickness exceeds 1 mm, the film is too thick so that heat conduction from the back surface of the substrate 10 is impaired, so that there is a possibility that the growth temperature may be difficult to control in the columnar crystal growth step described below, and the thickness is less than 100 μm. If this is the case, there is a possibility that the yield in the manufacturing process is significantly reduced because it is too thin and easily broken.

The dielectric film 11 is preferably silicon oxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ). When a Si or SiC substrate is used as the substrate 10, these dielectric films can also be formed by oxidizing or nitriding the substrate surface. Even when a sapphire substrate is used, these dielectric films can be formed by a known thin film forming method such as a sputtering method, a CVD method, or an EB vapor deposition method. The thickness of the dielectric film 11 is preferably 1 nm or more and less than 100 μm. If it exceeds 100 μm, it is too thick to be easily removed by selective etching, which will be described later. For this reason, there is a possibility that the columnar crystal is easily damaged in the step of removing the columnar crystal from the dielectric film. If it is less than 1, the film is too thin and it is difficult to form the dielectric film uniformly. This may cause a problem that crystal nuclei grown on the dielectric film are difficult to take a desired orientation.

  Thus, by using silicon nitride or silicon oxide as the dielectric, the columnar phosphor can be easily detached from the epitaxial growth substrate by selective etching, and a minute phosphor composed of columnar crystals can be easily obtained. it can.

  Next, as shown in FIG. 3C, semiconductor crystal nuclei 12 are formed on the dielectric film 11. As a method for forming the crystal nucleus 12, when a means such as a molecular beam epitaxy (MBE) method, a chemical vapor deposition (CVD) method, or a pulsed laser deposition (PLD) method is used, it is formed in a self-forming manner in the initial stage of crystal growth. Crystal nuclei can be obtained.

  Thereafter, as shown in FIG. 3D, crystal nuclei 12 are grown to obtain a light absorption region 12a made of columnar crystals. Dielectric film 11 has a low probability of adhesion of semiconductor raw material, and crystal nuclei 12 are scattered on substrate 10 at a constant density. Further, since the subsequent growth is oriented growth in a specific direction centering on the crystal nucleus 12, a columnar crystal as shown in FIG. 3d can be easily grown.

  Next, as shown in FIG. 3E, the crystal growth conditions are changed, and the light emitting region 13 is grown on the light absorption region 12a. Thereafter, as shown in FIG. 3 (f), the crystal growth conditions are changed again, and the light absorption region 12 b is grown on the light emitting region 13.

  Through the above steps, the columnar crystal phosphor 1 composed of the light absorption region 12 and the light emission region 13 is obtained in a state of being arranged side by side on the substrate 10. As the crystal growth method, a molecular beam epitaxy (MBE) method, a chemical vapor deposition (CVD) method, a pulsed laser deposition (PLD) method, or the like can be used.

  Thereafter, in order to desorb the phosphor 1, the phosphor film 1 is desorbed from the substrate 10 by removing the dielectric film 11 using a solution that selectively etches only the dielectric film 11 (FIG. Not shown). Through such steps, the phosphor 1 of the present invention can be obtained.

  In the case where the dielectric film 11 is made of silicon oxide or silicon nitride, by using a solution containing hydrogen fluoride (HF) as the etching solution, the dielectric material can be used without affecting the substrate 10 and the phosphor 1. This is preferable in that only the film can be removed by etching.

  Moreover, it can be set as a light-emitting device using the fluorescent substance 1 of this invention. The light-emitting device of the present invention is characterized in that the above-described phosphors are installed at a predetermined density in parallel on a substrate. Thus, since the columnar phosphors grown on the substrate are arranged in parallel at a predetermined density, the substrate can be used as an excitation light guide for the columnar phosphor, and the columnar phosphor and the substrate are integrated. Therefore, the coupling loss is low. Therefore, a light emitting device with excellent efficiency can be obtained. A schematic cross-sectional view of the light emitting device of the present invention is shown in FIG.

In the light emitting device 20 of the present invention, the columnar crystal phosphor group 24 grown on the substrate 21 via the dielectric film 22 is not detached from the substrate according to the above-described phosphor manufacturing method, but from the side surface of the substrate. The excitation light source 25 is irradiated and excited. The light-emitting device 20 of the present invention is a brighter and more efficient light-emitting device because the luminous efficiency of the phosphor is higher than that of a surface-emitting light-emitting device having a thin-film light-emitting region. Compared to the conventional case where a phosphor screen in which particulate phosphors are dispersed is provided, the substrate serving as the light guide and the columnar phosphor are integrated, so the coupling loss is small and the surface emission is highly efficient. Type light emitting device can be realized.

  A lens 26 may be interposed between the excitation light source 25 and the side surface of the substrate 21 in order to improve the coupling efficiency. Further, a light reflection plate 23 may be provided on the lower surface of the substrate 21 in order to efficiently guide the excitation light incident on the substrate 21 into the phosphor group 24 of columnar crystals. As the light reflecting plate 23, a material such as aluminum (Al), silver (Ag), platinum (Pt) can be used.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not intending to be limited to this.

Example 1
In this example, an example of a phosphor having a columnar crystal using a group III nitride semiconductor and a method for manufacturing the phosphor will be described.

In FIG. 3, a Si wafer material having a (111) plane as the main surface was used as the substrate 10 and thermally oxidized at 900 ° C. for 3 hours in an oxygen atmosphere to form a 10 nm thick SiO ₂ film on the substrate surface. This SiO ₂ film corresponds to the dielectric film 11.

Thereafter, the substrate 10 is introduced into a molecular beam epitaxy apparatus (not shown), and the substrate 10 is irradiated with metal Ga, metal In and plasma-activated active atomic N beam as raw materials, so that In _0.1 Ga _0.9 N Crystal nuclei 12 made up of were formed. When the crystal nucleus 12 was observed with a scanning electron microscope, the surface thereof had a hexagonal shape and the diameter was 2.5 nm.

By continuing the growth, the crystal nucleus 12 became a columnar crystal made of In _0.1 Ga _0.9 N having a length of 20 nm. This columnar crystal region corresponds to the light absorption region 12a.

Next, the molecular beam intensity of metal Ga and metal In was adjusted, and a light emitting region 13 made of In _0.2 Ga _0.8 N was grown on the light absorption region 12a with a length of 2 nm.

Next, the molecular beam intensity of metal Ga and metal In was adjusted again, and a columnar crystal made of In _0.1 Ga _0.9 N having the same composition as that of the light absorption region 12a was grown on the light emitting region 13 to a length of 20 nm. . This columnar crystal region corresponds to the light absorption region 12b.

The phosphor 1 was formed by the above crystal growth. Thereafter, the substrate 10 formed with the phosphor 1 is taken out from the molecular beam epitaxy apparatus, immersed in an aqueous solution containing HF, the dielectric film 11 made of SiO ₂ film is removed by etching, and the phosphor 1 is detached from the substrate 10. I let you.

  When the phosphor 1 was irradiated with a blue LD light source having a wavelength of 405 nm, light absorption occurred in the absorption regions 12a and 12b, energy was transferred to the light emission region 13, and blue light emission having a wavelength of 430 nm was obtained.

(Example 2)
In Example 1 above, the phosphor 1 of the present invention was produced in the same manner as Example 1 except that Si was added as an impurity when the light emitting region 13 was grown.

  When the phosphor 1 was irradiated with a blue LD light source having a wavelength of 405 nm, the energy transitioned from the absorption region 12a to the light emission region 13 was emitted through the Si impurity level, and blue light emission having a wavelength of 450 nm was obtained. Further, the luminous efficiency increased by 40% compared to the case of Example 1.

(Example 3)
In Example 1 above, the phosphor 1 of the present invention was produced in the same manner as Example 1 except that Tb was added as an impurity when the light emitting region 13 was grown.

  Next, as in Example 1, when the phosphor 1 was irradiated with a blue LD light source having a wavelength of 405 nm, the energy transitioned from the absorption region 12a to the light emission region 13 was emitted by the inner shell transition corresponding to the f orbit of Tb. A green light emission having a wavelength of 543 nm was obtained.

Example 4
In Example 1, the phosphor 1 of the present invention was produced in the same manner as Example 3 except that Sm was added together with Tb as an impurity when growing the light absorption regions 12a and 12b.

  Next, as in Example 1, when the phosphor 1 was irradiated with a blue LD light source having a wavelength of 405 nm, the light absorption was promoted by Sm added to the absorption regions 12a and 12b, and the energy transitioned from Sm to the light emission region 13 was achieved. Emitted light by the inner shell transition corresponding to the f orbital of Tb, and green light emission with a wavelength of 543 nm was obtained.

  In addition, the emission intensity of the phosphor 1 of this example increased by 1.4 times compared to the phosphor of Example 3 in which Sm was not added to the light absorption region.

(Example 5)
In Example 1 described above, the phosphor 1 having a plurality of light emitting regions as shown in FIG. 2 was produced by alternately repeating the growth in the light emitting regions 13 and the light absorbing regions 12b. Otherwise, the phosphor 1 of the present invention was produced in the same manner as in Example 1.

  That is, the phosphor 1 of this example has three light emitting regions 3a, 3b, and 3c, and Tb, Eu, and Si are added as impurities, respectively.

  Next, when the phosphor 1 of this example was irradiated with a blue LD light source having a wavelength of 405 nm, the light emitting regions 3a, 3b and 3c emitted light of green, red and blue, respectively, and these were mixed to give white light emission. Moreover, even if the formation order of the light emitting regions 3a to 3c was changed, the light emission intensity and the light emission color did not change.

(Example 6)
In Example 5, the step of detaching the phosphor 1 from the substrate 10 was omitted, and the columnar phosphor 1 was fixed to the substrate 10 vertically. On the surface of the substrate 10 opposite to the surface to which the phosphor 1 is fixed, an Al film having a thickness of 500 nm is deposited to form a light reflecting plate 23.

  Next, as shown in FIG. 4, the laser beam of the blue semiconductor laser element 25 having a wavelength of 405 nm was incident from the side surface of the substrate 10 through the coupling lens 26.

  The laser light was guided in the horizontal direction through the substrate 10 and reflected in the vertical direction by the light reflecting plate 23, and was incident on the phosphor 1 to emit white light.

  Since the light emitting device of this example emits light from a nano-sized columnar phosphor having a remarkable quantum size effect, the light emission efficiency is improved as compared with the case where the light emitter is formed in a planar shape.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic perspective view of the phosphor of the present invention. It is a schematic perspective view of the phosphor of the present invention. It is a schematic sectional drawing explaining each process of the manufacturing process of the fluorescent substance of this invention. It is a schematic sectional drawing of the light-emitting device of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Phosphor, 2,12a, 12b Light absorption area | region, 3,3a, 3b, 3c, 13 Light emission area | region 10,21 Substrate, 11,22 Dielectric body, 12 Crystal nucleus, 20 Light emitting device, 23 Light reflector, 24 Phosphor group, 25 excitation light source, 26 lens.

Claims (12)

A phosphor composed of a columnar crystal having a diameter of 3 nm or less, wherein a light emitting region having a composition of In _0.2 Ga _0.8 N and light having a composition of In _0.1 Ga _0.9 N are formed in the columnar crystal. and a absorption region, light emitting region and the light absorption region is adjacent in the longitudinal direction of the columnar crystals,
The light emitting region is sandwiched between two light absorption regions in the longitudinal direction of the phosphor,
The emission wavelength exhibited by the emission region is longer than 430 nm,
The wavelength of the excitation light of the phosphor Ru 380 450nm der,
Phosphor.   The phosphor according to claim 1, wherein a length of the light emitting region is 3 nm or less.   The phosphor according to claim 1, wherein there are two or more light emitting regions.   The light emitting region includes a light emitting region exhibiting red, a light emitting region exhibiting green, and a light emitting region exhibiting blue, and the red, green, and blue are mixed to exhibit white as a whole. 4. The phosphor according to any one of 3.   The phosphor according to any one of claims 1 to 4, wherein the columnar crystal includes a group III nitride, and the structure of the crystal is a wurtzite structure.   6. The phosphor according to claim 1, wherein a plane including a diameter of the columnar crystal is a (0001) plane, and a longitudinal direction is a <0001> direction.   The phosphor according to claim 1, wherein a light emission center is added to the light emitting region.   The phosphor according to claim 7, wherein the emission center is a rare earth element.   The phosphor according to claim 1, wherein an element that controls light absorption is added to the absorption region. A method for producing the phosphor according to any one of claims 1 to 9,
A phosphor comprising: a step of forming a dielectric thin film on a substrate; a step of growing a columnar crystal phosphor on the dielectric thin film; and a step of detaching the columnar crystal phosphor from the substrate by etching. Production method.   The method of manufacturing a phosphor according to claim 10, wherein the dielectric is silicon nitride or silicon oxide.   A light-emitting device, wherein the phosphor according to any one of claims 1 to 9 is installed at a predetermined density in parallel on a substrate.

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