JP2017157732A - Unit luminescent body, luminescent body, method of manufacturing luminescent body, and method of manufacturing luminescent body powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a luminescent body which is made from nitride of the thirteenth group, and has a small half-value width of luminescence wavelength and superior luminescence efficiency.SOLUTION: On individual crystals present on a principal surface of a c-axially oriented polycrystalline substrate, unit luminescent bodies which are formed of a nitride semiconductor of the thirteenth group, and have a c-axial orientation profiling the c-axial orientation of the crystal and also have a luminescent layer emitting fluorescent light are grown while a groove part is provided between respective unit luminescent bodies so as to form a luminescent body structure consisting of a plurality of unit luminescent bodies. Alternatively, the luminescent bodies have the polycrystalline substrate separated from the luminescent body structure to separate the individual unit luminescent bodies of the luminescent body structure from one another, thereby obtaining luminescent body powder.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fluorescent light emitter that emits light when irradiated with radiation, and more particularly to a light emitter made of a group 13 nitride.

  Group 13 nitrides such as GaN are light emitters (fluorescent emitters) that emit light (fluorescent light emitters) when irradiated with X-rays, electron beams, or other radiation. It is already known that it can be applied to a scintillator in a scintillation detector (see, for example, Patent Document 1). Patent Document 1 discloses that a scintillator having an InGaN / GaN multiple quantum well (MQW) structure is preferable in order to generate strong scintillation.

In addition, a technique for obtaining a light emitter by heteroepitaxially growing a group 13 nitride on the surface of AlN or Al ₂ O ₃ powder particles is also known (see, for example, Patent Document 2).

  On the other hand, when the InGaN / GaN MQW layer is formed on the GaN layer, the In composition in the InGaN differs depending on the plane orientation of the underlying GaN layer, and therefore the emission wavelength varies with the plane orientation of the underlying GaN layer. It is also already known (see, for example, Non-Patent Document 1).

  Further, in the case of growing InGaN or GaN, if a semipolar plane other than the c plane which is a polar plane or a nonpolar plane (for example, m plane) is used as a growth plane, the impurities are larger than when the c plane is used as a growth plane. It is known that oxygen uptake increases as the light emission brightness decreases (for example, see Patent Document 3).

  Furthermore, an oriented alumina substrate in which polycrystalline alumina oriented in the c-axis direction is formed into a substrate shape, and a GaN polycrystalline substrate (oriented GaN substrate) in which gallium nitride is laminated on the substrate and oriented in the c-axis direction are prepared. The method is already known (see, for example, Patent Document 4).

JP 2004-59722 A JP-A-11-279550 Japanese Patent No. 4891462 International Publication No. 2014/192911

K. Nisizuka, M. Funato, Y. Kawakami, and Sg. Fujita, "Efficient radative recombination from <11-22> -oriented InxGa1-xN multiple quantum wells fabricated by the regrowth technique", Applied Physics Letters, vol.85, no.15 (2004), p.3122-3124.

  It is desirable that the light emitter used as the scintillator has a small half-value width of the emission wavelength in the emission spectrum and a high emission luminance (high emission intensity) from the viewpoint of detection accuracy and detection sensitivity. In this regard, since the group 13 nitride semiconductor is difficult to decompose and has high environmental resistance, the InGaN / GaN MQW structure, for example, can be used as a fluorescent light emitter with little luminance deterioration even in a severe environment such as high temperature and high pressure. It is done.

  However, Patent Document 1 only illustrates the film thicknesses of the InGaN layer and the GaN layer with respect to the scintillator having the InGaN / GaN MQW structure, and does not disclose any specific structure and characteristics.

  Further, for example, as disclosed in Patent Document 2, when an InGaN / GaN MQW structure is formed on the surface of the powder particle, crystal planes with various plane orientations appear on the surface of the powder. As disclosed in Non-Patent Document 1, the In composition in InGaN differs depending on the surface orientation of the substrate, resulting in a broad emission spectrum, which is not suitable for use as a scintillator. Further, the fact that the surface orientation of the base is various means that growth with a semipolar surface other than the c-plane which is a polar surface or a nonpolar surface as a growth surface may occur, but it is disclosed in Patent Document 3. As described above, since the growth on the growth surface takes in a large amount of impurities such as oxygen, there is also a problem that high luminous efficiency cannot be expected in the obtained phosphor.

  The present invention has been made in view of the above problems, and an object of the present invention is to realize a light-emitting body that is made of a group 13 nitride and has a small half-value width of light emission wavelength and excellent light emission efficiency.

  In order to solve the above-described problem, a first aspect of the present invention is a flat plate whose unit light-emitting body is made of a group 13 nitride semiconductor and has a light-emitting layer that emits fluorescence, the main surface being a c-plane. It is in the form of particles, and the average size in the in-plane direction of the main surface is 30 μm or more and 100 μm or less.

  A second aspect of the present invention is a unit light emitter according to the first aspect, which is a laminate of a plurality of layers each having a c-axis orientation, and a part of the plurality of layers is the light emitting layer. It is characterized by that.

  According to a third aspect of the present invention, there is provided a unit light emitter according to the second aspect, wherein the light-emitting layer is a multi-layer in which first unit layers and second unit layers having different compositions are alternately and repeatedly stacked. It has a quantum well structure.

  A fourth aspect of the present invention is a unit light emitter according to the third aspect, characterized in that the first unit layer is made of InGaN and the second unit layer is made of GaN.

  A fifth aspect of the present invention is characterized in that the light emitter includes a plurality of unit light emitters, each of which is a unit light emitter according to any one of the second to fourth aspects.

  According to a sixth aspect of the present invention, there is provided a light emitter according to the fifth aspect, wherein the plurality of unit light emitters are provided on a single substrate.

  According to a seventh aspect of the present invention, there is provided the light emitter according to the sixth aspect, wherein the one substrate is a c-axis oriented polycrystalline substrate, and one unit is formed on each crystal of the polycrystalline substrate. A light emitter is provided, the c-axis orientation of the one unit light emitter follows the c-axis orientation of the crystal immediately below, and a groove is provided between the unit light emitters.

  An eighth aspect of the present invention is the light emitter according to the seventh aspect, wherein the groove is provided along a crystal grain boundary of the polycrystalline substrate.

  A ninth aspect of the present invention is the light emitter according to the seventh or eighth aspect, wherein the one substrate is a c-axis oriented polycrystalline alumina substrate, and alumina in the polycrystalline alumina substrate (006) The X-ray rocking curve half-width value of the surface is 2.0 degrees to 6.5 degrees.

  A tenth aspect of the present invention is the light emitter according to the sixth aspect, wherein the plurality of unit light emitters are closely fixed on the one substrate.

  An eleventh aspect of the present invention is a light emitter comprising a c-axis oriented polycrystalline substrate and a light emitter structure made of a group 13 nitride semiconductor and provided on the polycrystalline substrate. The body structure is formed of a plurality of unit light emitters each provided on an individual crystal of the polycrystalline substrate and having a light emitting layer that emits fluorescence, and the c-axis orientation of each of the plurality of unit light emitters is It follows the c-axis orientation of the crystal immediately below, and a groove is provided between each of the plurality of unit light emitters.

  A twelfth aspect of the present invention is the light emitter according to the eleventh aspect, wherein the groove is provided along a crystal grain boundary of the polycrystalline substrate.

  A thirteenth aspect of the present invention is a light emitter according to the eleventh or twelfth aspect, wherein the polycrystalline substrate is a c-axis oriented polycrystalline alumina substrate, and alumina in the polycrystalline alumina substrate (006) The X-ray rocking curve half-width value of the surface is 2.0 degrees to 6.5 degrees.

  A fourteenth aspect of the present invention is the light emitter according to any one of the eleventh to thirteenth aspects, wherein an average size in an in-plane direction of the polycrystalline alumina substrate is not less than 30 μm and not more than 100 μm. And

  A fifteenth aspect of the present invention is a light emitter according to any one of the eleventh to fourteenth aspects, wherein the plurality of unit light emitters are a laminate of a plurality of layers each having a c-axis orientation, A part of the plurality of layers is the light emitting layer.

  According to a sixteenth aspect of the present invention, there is provided the light emitter according to the fifteenth aspect, wherein the light-emitting layer includes multiple quantum elements in which first unit layers and second unit layers having different compositions are alternately and repeatedly stacked. It has a well structure.

  A seventeenth aspect of the present invention is the light emitter according to the sixteenth aspect, characterized in that the first unit layer is made of InGaN and the second unit layer is made of GaN.

  According to an eighteenth aspect of the present invention, there is provided a method for producing a light emitter, comprising a group 13 nitride semiconductor on each crystal present on a principal surface of a c-axis oriented polycrystalline substrate, wherein c A unit light emitter having a c-axis orientation that follows the axis direction and having a light emitting layer that emits fluorescence is grown while providing a groove between the unit light emitters, thereby comprising a plurality of unit light emitters. Forming a light-emitting body structure;

  According to a nineteenth aspect of the present invention, there is provided the light emitting device manufacturing method according to the eighteenth aspect, wherein the groove is formed along a crystal grain boundary of the polycrystalline substrate.

  According to a twentieth aspect of the present invention, there is provided a method for manufacturing a light emitter according to the eighteenth or nineteenth aspect, wherein the polycrystalline substrate is a c-axis-oriented polycrystalline alumina substrate, the alumina (006) plane. The X-ray rocking curve half-width value of is about 2.0 degrees to 6.5 degrees.

  A twenty-first aspect of the present invention is a method for manufacturing a light emitter according to any of the eighteenth to twentieth aspects, wherein an average size in the in-plane direction of the polycrystalline alumina substrate is 30 μm or more and 100 μm or less. It is characterized by that.

  A twenty-second aspect of the present invention is a method of manufacturing a light emitter according to any of the eighteenth to twenty-first aspects, wherein a plurality of unit light emitters are formed by laminating a plurality of layers each of which is c-axis oriented. And a part of the plurality of layers is formed as the light emitting layer.

  According to a twenty-third aspect of the present invention, there is provided a method of manufacturing a light emitter according to the twenty-second aspect, in which the first unit layer and the second unit layer having different compositions are stacked alternately and repeatedly. Thus, a multi-quantum well structure is formed.

  A twenty-fourth aspect of the present invention is a method of manufacturing a light emitter according to the twenty-third aspect, wherein the first unit layer is formed of InGaN and the second unit layer is formed of GaN. Features.

  According to a twenty-fifth aspect of the present invention, there is provided a method for producing a phosphor powder that emits fluorescence, the phosphor producing step for obtaining a phosphor by the production method according to any of the eighteenth to twenty-fourth aspects, and the light emission. A step of separating the unit light emitters in the light emitter structure by separating the polycrystalline substrate from the light emitter structure in the body, thereby obtaining a light emitter powder. And

  A twenty-sixth aspect of the present invention is a method for manufacturing a phosphor powder according to the twenty-fifth aspect, wherein a release layer is formed between the polycrystalline substrate and the phosphor structure in the phosphor manufacturing step. And in the said powder preparation process, the said polycrystalline substrate is peeled from the said light-emitting body structure in the said peeling layer by irradiating a laser beam to the said polycrystalline substrate side of the said light-emitting body, It is characterized by the above-mentioned.

  According to a twenty-seventh aspect of the present invention, there is provided a method for producing a phosphor powder that emits fluorescence, wherein a phosphor preparation step for preparing a phosphor according to any one of the eleventh to seventeenth aspects; A step of separating the unit light emitters in the light emitter structure by separating the polycrystalline substrate from the light emitter structure, thereby obtaining a light emitter powder. .

  A twenty-eighth aspect of the present invention is a method for producing a phosphor powder according to the twenty-seventh aspect, wherein the phosphor has a release layer between the polycrystalline substrate and the phosphor structure, In the powder preparation step, the polycrystalline substrate is peeled from the light emitter structure at the peeling layer by irradiating the light emitting body with laser light on the polycrystalline substrate side.

  A twenty-ninth aspect of the present invention is a method for producing a phosphor powder according to any one of the twenty-fifth to twenty-eighth aspects, wherein the powder particles of the phosphor powder have a flat plate shape having a c-plane as a main surface. The average size in the in-plane direction of the main surface is 30 μm or more and 100 μm or less.

  According to the first to twenty-ninth aspects of the present invention, it is possible to realize a light-emitting body having a uniform crystal orientation and a small composition variation in the light-emitting layer.

  In particular, according to the sixth to twenty-fourth aspects, it is possible to realize a plate-like light emitter having a small half-value width of the wavelength peak in the emission spectrum.

  In particular, according to the seventh to ninth and eleventh to seventeenth aspects, light can be extracted also from the groove, so that a plate-like light emitting body having excellent luminous efficiency can be realized.

  In particular, according to the ninth and thirteenth aspects, the groove portion is suitably formed, and growth in a growth orientation other than the c-axis is suppressed, so that a plate-like light emitting body having particularly excellent luminous efficiency. Can be realized.

  In particular, according to the twenty-fifth to twenty-ninth aspects, a phosphor powder with uniform crystal orientation in the powder particles and a small composition variation in the phosphor layer can be realized.

  In particular, according to the twenty-ninth aspect, it is possible to realize a phosphor powder that is easy to align the crystal orientation in a processed product produced by processing such as coating or molding, and that provides excellent luminous efficiency.

It is a figure which shows typically the structure of the plate-shaped light-emitting body 10 which concerns on 1st Embodiment. 2 is a laser microscope image of the upper surface of the plate-like light emitter 10. It is a figure for demonstrating the detail of the orientation alumina substrate. It is a figure which shows the mode of the process which obtains a particulate-form light-emitting body.

  The group numbers in the periodic table shown in this specification are based on the 1 to 18 group number designations according to the 1989 International Union of Pure Applied Chemistry (IUPAC) revised inorganic chemical nomenclature. , Group 13 refers to aluminum (Al), gallium (Ga), indium (In), etc., and Group 14 refers to silicon (Si), germanium (Ge), tin (Sn), lead (Pb), etc. , 15 refers to nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), and the like.

<First Embodiment>
<Structure of plate-shaped light emitter>
FIG. 1 is a diagram schematically showing a configuration of a plate-like light emitter 10 according to the first embodiment of the present invention. FIG. 2 is a laser microscope image of the upper surface of the plate-like light emitter 10. FIG. 3 is a diagram for explaining the details of the oriented alumina substrate 1 used as a base substrate in the plate-like light emitter 10.

  The plate-like light emitter 10 according to the present embodiment is a plate-like light emitter (fluorescent light emitter) that emits light (fluoresces) when irradiated with X-rays, electron beams, or other radiation. The plate-like light emitter 10 generally includes a light emitting structure made of a group 13 nitride semiconductor. More specifically, the plate-like light emitter 10 includes a so-called low-temperature buffer layer 2 made of GaN, a first n-type GaN layer 3, a light-emitting layer 4, and a cap on an oriented alumina substrate 1 that is a base substrate. A second n-type GaN layer 5 as a layer is laminated in this order. The lamination from the low-temperature buffer layer 2 to the second n-type GaN layer 5 is preferably performed by MOCVD (metal organic chemical vapor deposition), but other growth methods may be employed. In the following, a laminated portion of the first n-type GaN layer 3, the light emitting layer (active layer) 4, and the second n-type GaN layer 5 will be referred to as a light emitter structure 20. To do.

  The oriented alumina substrate 1 is obtained by polishing a sintered body obtained by joining alumina crystals in the in-plane direction to a predetermined thickness, which is obtained by sintering alumina particles while being c-axis oriented. C It is an axially oriented polycrystalline substrate.

  More specifically, in the oriented alumina substrate 1, the c-axis direction of each alumina crystal partitioned by the crystal grain boundary 1g is the normal direction of the main surface of the oriented alumina substrate 1 (hereinafter, also simply referred to as the normal direction). ) May have a slight deviation (appropriate variation), but the normal direction can be regarded as substantially coincident with the c-axis direction of alumina when viewed as a whole substrate. . The average particle size (average size) in the in-plane direction of each alumina crystal is about 30 μm to 100 μm.

  For example, in the case of the oriented alumina substrate 1 shown in FIG. 3, four alumina crystals 1a, 1b, 1c, and 1d are connected in the left-right direction as viewed in the drawing. In the alumina crystals 1a, 1b, 1c, and 1d, The c-axis direction (shown by arrow c) is an angle with respect to the normal direction of main surface S of oriented alumina substrate 1 (shown by arrow n and coincides with the vertical direction in the drawing of FIG. 3). It is inclined by α1, α2, α3, and α4.

  The degree of variation of the c-axis of each alumina crystal in the oriented alumina substrate 1 (hereinafter referred to as “c-axis orientation degree”) is measured by X-ray rocking curve (XRC) on the (006) plane of alumina with respect to the main surface S (ω scan). ) Can be evaluated according to the degree of the half-value width (hereinafter referred to as RC half-value width) of the (006) plane peak obtained. The smaller the value of the RC half width, the more the c-axis orientation is aligned in the normal direction (the degree of orientation is higher). In the present embodiment, the plate-like light emitter 10 is configured using the oriented alumina substrate 1 having an RC half width value of 2.0 degrees to 6.5 degrees. In this case, the plate-like light emitter 10 having a large emission intensity in the emission spectrum and a small half-value width of the emission wavelength (hereinafter referred to as wavelength half-value width) that can be used as a scintillator is realized.

  The planar size (diameter) and thickness of the oriented alumina substrate 1 are not particularly limited as long as there is no problem in the processing for forming the light emitter structure 20 and the use of the plate-like light emitter 10. Examples are 2 inches to 8 inches and a thickness of about 300 μm to 1800 μm.

  The buffer layer 2 is a layer formed in order to improve the crystal quality of the light emitting structure 20. The buffer layer 2 is formed of GaN with a thickness of about 5 nm to 50 nm.

The first n-type GaN layer 3 is formed by doping n-type dopant (for example, Si) with an atomic concentration of about 8 × 10 ¹⁷ / cm ^{3 to} 3 × 10 ¹⁹ / cm ³ into n-type. Is a layer. The first n-type GaN layer 3 preferably has a thickness of about 100 nm to 10 μm.

The light emitting layer 4 is a part mainly responsible for light emission in the light emitting structure 20. In the plate-like light emitter 10 according to the present embodiment, the light emitting layer 4 is doped with an n-type dopant (for example, Si) at an atomic concentration of about 5 × 10 ¹⁷ / cm ³ to 1 × 10 ¹⁹ / cm ³ , respectively. As a result, the first unit layer 4a having a composition of In _x Ga _1-x N (0 <x <1) exhibiting n-type and the second unit layer 4b made of GaN are repeatedly stacked alternately. Provided with a quantum well (MQW) structure. That is, the plate-like light emitter 10 according to the present embodiment includes the light emitting layer 4 having an InGaN / GaN MQW structure. In such a case, the light emitting layer 4 is configured by selecting the value of the In composition ratio x in the first unit layer 4a so as to emit light (fluorescence) having a desired wavelength. In other words, the plate-like light emitter 10 emits light (fluorescence) having a wavelength corresponding to the In composition ratio x of the first unit layer 4a. For example, when x = 0.15, the light emitting layer 4 having an emission wavelength of 450 nm can be obtained.

  The light emitting layer 4 is configured by laminating a first unit layer 4a having a thickness of about 2 nm to 10 nm and a second unit layer 4b having a thickness of about 2 nm to 10 nm, respectively, one to eight layers. Is preferred.

The second n-type GaN layer 5 is a GaN layer exhibiting n-type by doping Si with an atomic concentration of about 8 × 10 ¹⁷ / cm ^{3 to} 3 × 10 ¹⁹ / cm ³ . The second n-type GaN layer 5 is provided as a cap layer. The second n-type GaN layer 5 preferably has a thickness of about 50 nm to 500 nm.

  In the present embodiment, as described above, the light emitting structure 20 composed of the first n-type GaN layer 3, the light emitting layer 4, and the second n-type GaN layer 5 is attached to the oriented alumina substrate 1. Formed on top. Therefore, each layer constituting the light emitting structure 20 is not formed on the oriented alumina substrate 1 with a uniform crystal orientation, but individual alumina crystals constituting the oriented alumina substrate 1 (illustrated in FIG. 3). If so, it grows on the alumina crystals 1a, 1b, 1c, and 1d) in a manner that follows the crystal orientation of each alumina crystal.

  When a laminated structure composed of the first n-type GaN layer 3, the light-emitting layer 4, and the second n-type GaN layer 5 formed on each alumina crystal is referred to as a unit light emitter 20A, The unit light emitter 20A has an excellent crystal quality because it is epitaxially grown following the c-axis, which is the crystal orientation of the alumina crystal serving as the base. This means that the composition variation in each unit light emitter 20A is small, and consequently the variation in the half-value width in the wavelength profile of the light emission generated from each unit light emitter 20A and the light emission is small. Yes. Since the light emission from the light emitting structure 20 is a superposition of the light emission from the individual unit light emitters 20A, the light emission from the light emitting structure 20 has a desired emission wavelength, a high luminance, and a wavelength profile. The wavelength half width at is small. For example, a wavelength half width of 50 nm or less can be realized. The value of the half width of the wavelength is about the same as the half width of the wavelength of light emitted from the light emitter (fluorescent plate) produced by applying P55, BM powder, which is a conventionally known blue fluorescent powder, to a glass plate (glass substrate). is there.

  In the present embodiment, the emission wavelength profile (emission wavelength and half-value width) is evaluated based on the result of cathodoluminescence (CL) measurement.

  Speakingly, the unit light emitter 20A is the total thickness of the first n-type GaN layer 3, the light-emitting layer 4, and the second n-type GaN layer 5, and is about 100 nm to 1000 nm. On the other hand, since the average particle size (average size) in the in-plane direction is about 30 μm to 100 μm, which is about the same as the average particle size (average size) of the individual alumina crystals constituting the oriented alumina substrate 1, I am doing. That is, in FIG. 1, the thickness of each layer is only exaggerated.

  Further, in the present embodiment, by appropriately adjusting the growth conditions of the respective layers constituting the light emitting structure 20, the grooves 6 along the crystal grain boundaries 1g of the oriented alumina substrate 1 are formed as shown in FIG. The light emitting structure 20 is formed. In FIG. 1, the groove 6 is exaggerated for easy understanding. The actual groove 6 is observed, for example, as shown in FIG. 2 and has a width of about 100 nm to 1000 nm. In FIG. 1, the groove 6 passes through the first n-type GaN layer 3 and reaches the buffer layer 2, but not all the grooves 6 reach the buffer layer 2.

  Since the groove portion 6 is provided in this manner, the light emitting structure 20 provided in the plate-like light emitter 10 according to the present embodiment is substantially the same as the underlying alumina crystal constituting the oriented alumina substrate 1 or It can be said that this is an aggregate of unit light emitters 20A having a slightly smaller planar size and grown following the crystal orientation of the underlying alumina crystal. Alternatively, although the light emitting structure 20 may have a slight deviation from the normal direction in the c-axis direction of each unit light emission 20A (appropriate variation), the light emitting structure 20 can be seen as a whole. In other words, the unit light emitter 20A is provided on the oriented alumina substrate 1 which is a common base substrate in such a manner that the normal direction can be regarded as substantially coincident with the c-axis direction. it can.

  In the plate-like light emitter 10 provided with the groove 6, the light (fluorescence) generated in the light emitter 4 is extracted not only in the thickness direction of the plate-like light emitter 10 but also through the groove 6. That is, the light L traveling from the light emitting layer 4 toward the groove 6 proceeds to the outside of the plate-like light emitter 10 while being sequentially reflected by the opposing side surfaces 20 s of the light emitting structure 20 that forms the groove 6. .

  Thereby, the plate-shaped light-emitting body 10 has a high light emission efficiency (light extraction efficiency) as compared with a configuration without the groove 6.

<Manufacturing method of plate-like illuminant>
Next, the manufacturing method of the plate-like light emitter 10 will be described by taking as an example the case of using the MOCVD method for forming each layer on the oriented alumina substrate 1.

  First, an oriented alumina substrate 1 is prepared. The oriented alumina substrate 1 is made of an alumina sintered body produced by various methods and conditions as exemplified in Patent Document 4 using a commercially available plate-like alumina powder having an average particle size of about 30 μm to 100 μm as a raw material. It can be prepared by polishing to a desired thickness by surface polishing (lap polishing) using nanodiamond abrasive grains.

In the present embodiment, as described above, the plate-like light emitter 10 is configured using the oriented alumina substrate 1 in which the RC half-value width of alumina in the XRC measurement (ω scan) is 2.0 degrees to 6.5 degrees. To do. In order to obtain such an oriented alumina substrate 1 suitably (with high yield), it is preferable to appropriately control the above-described conditions for producing the alumina sintered body. Specifically, a commercially available plate-like alumina powder is formed into an oriented molded body formed into a sheet shape by a method using shearing force such as tape molding, extrusion molding, doctor blade method, etc., and a large number of these are stacked. After preparing a desired thickness, a sheet-like molded body subjected to press molding is prepared, and then a firing temperature of 1500 to 1800 ° C. and a firing time of 30 minutes to 5 hours by a pressure sintering method such as a hot press method. In the first baking step of baking at a surface pressure of 100 to 200 kgf / cm ^2, a baking temperature of 1500 to 1800 ° C., a baking time of 2 to 5 hours, and a gas pressure of 1000 by hot isostatic pressing (HIP). It is preferable to obtain an alumina sintered body by performing a second firing step of firing again under a condition of ˜2000 kgf / cm ² . However, if the yield is not taken into consideration, an alumina sintered body manufactured under appropriate conditions may be selected that satisfies the above-mentioned half-value width requirements.

  When imparting translucency to the oriented alumina substrate 1, high-purity plate-like alumina powder is used. Preferably, plate-like alumina powder having a purity of 98% or more is used. More preferably, plate-like alumina powder having a purity of 99% or more is used. Particularly preferably, plate-like alumina powder having a purity of 99.9% or more is used, and most preferably plate-like alumina powder having a purity of 99.99% or more is used.

  The prepared oriented alumina substrate 1 is placed on a susceptor in a predetermined MOCVD furnace, and the substrate temperature is once raised to a range of 1050 ° C. to 1200 ° C. in a hydrogen atmosphere to perform a cleaning process.

  Subsequently, a GaN layer as the buffer layer 2, a Si-doped GaN layer as the first GaN layer 3, a Si-doped InGaN layer as the first unit layer 4a, and a Si-doped GaN layer as the second unit layer 4b are formed. The light emitting layer 4 having the MQW structure and the Si-doped GaN layer as the second GaN layer 5 are sequentially formed. Each layer may be formed in consideration of the following conditions. The group 15 / group 13 gas ratio is the ratio of the supply amount of ammonia gas, which is a group 15 material, to the total amount of group 13 source gas (TMG, TMI) expressed in molar ratio. In the present embodiment, the formation temperature means the susceptor heating temperature.

Buffer layer 2:
Formation temperature: 500 ° C. to 600 ° C .;
Forming pressure: 20 kPa to 100 kPa;
Carrier gas: hydrogen;
Source gas: TMG (trimethylgallium) and ammonia gas;
Group 15 / Group 13 gas ratio: 500-2000.

First GaN layer 3:
Formation temperature: 1050 ° C to 1200 ° C;
Formation pressure: 10 kPa to 100 kPa;
Carrier gas: nitrogen and hydrogen;
Source gas: TMG (trimethylgallium) and ammonia gas;
Group 15 / Group 13 gas ratio: 1500-3000;
Dopant source: Silane gas.

Light emitting layer 4:
Formation temperature: 800 ° C. to 870 ° C .;
Forming pressure: 20 kPa to 100 kPa;
Carrier gas: nitrogen;
Source gas for first unit layer 4a: TMG (trimethylgallium), TMI (trimethylindium), and ammonia gas;
Dopant source: silane gas;
Source gas for second unit layer 4b: TMG (trimethylgallium) and ammonia gas;
Dopant source: silane gas;
Group 15 / Group 13 gas ratio: 300-800;
Number of repetitions of pairs of the first unit layer 4a and the second unit layer 4b: 1 to 8.

Second GaN layer 5:
Formation temperature: 950 ° C. to 1050 ° C .;
Formation pressure: 10 kPa to 100 kPa;
Carrier gas: nitrogen and hydrogen;
Source gas: TMG (trimethylgallium) and ammonia gas;
Group 15 / Group 13 gas ratio: 500-3000;
Dopant source: Silane gas.

  By satisfying these conditions, the light emitting structure 20 including the groove 6 between the individual unit light emitters 20A can be suitably formed on the oriented alumina substrate 1.

  As described above, according to the present embodiment, a phosphor structure including a light emitting layer having an InGaN / GaN MQW structure on an oriented alumina substrate in which the c-axis orientation of individual alumina crystals varies moderately. By providing the groove portion along the crystal grain boundary of the oriented alumina substrate, the composition variation in individual unit light emitters constituting the light emitter structure is small, and the luminous efficiency applicable to, for example, a scintillator can be reduced. An excellent plate-like light emitter is realized.

<Second Embodiment>
In the first embodiment described above, the plate-like light emitter is described. However, it is desired to use a powder (particulate) as the light emitter that emits light when irradiated with X-rays, electron beams or other radiation. There is also a demand. For example, powder light emitters can be applied to any surface in the form of a paste, and then dried to have a high degree of freedom in processing, such as being closely fixed to the surface or being formed into an arbitrary shape. Therefore, as a result, it contributes to the expansion of the usage phase of the luminous body.

  The formation of such a powdered illuminant may be obtained, for example, by granulation by a technique as disclosed in Patent Document 2, or by pulverization of a bulk illuminant. In this embodiment, By separating the oriented alumina substrate 1 from the plate-like light emitter 10 according to the first embodiment by a laser lift-off technique, a particulate light emitter is obtained. FIG. 4 is a diagram showing a state of processing for obtaining a particulate light emitter.

  Specifically, a plate-like light emitter 10 produced by the procedure shown in the first embodiment is prepared, and as shown in FIG. 4A, the surface of the oriented alumina 1 (light emitting structure 20). The laser beam is irradiated to the non-formation surface. When the laser beam is irradiated in this manner, in the plate-like light emitter 10, separation occurs as shown in FIG. 4B in the buffer layer 2 having a low mechanical strength, as indicated by an arrow AR1. The oriented alumina substrate 1 is separated from the light emitter structure 20. Then, although the light emitter structure 20 is configured as a whole, the groove portions 6 are present, so that the unit light emitters 20A having weak mutual coupling forces are also separated as indicated by the arrow AR2. As a result, a large number of unit light emitters 20A in the form of particles as shown in FIG. 4C are obtained. In other words, a phosphor powder is obtained in which each powder particle is a laminate of the first n-type GaN layer 3, the light-emitting layer 4, and the second n-type GaN layer 5. As described above, the unit light emitter 20A is epitaxially grown along the c-axis along the c-axis of the alumina crystal and growth in other crystal orientations is suppressed, so that the obtained powder particles have a small composition variation. It has become.

  In such a case, the unit light emitter 20A is made of a group 13 nitride semiconductor, has a tabular grain shape with the c-plane as the main surface, and the average size in the in-plane direction of the main surface is not less than 30 μm and not more than 100 μm. It can be said that it is a powder particle.

  In addition, when the plate-like light emitter 10 is captured on the premise that the particulate unit light-emitting body 20A is obtained in the above-described embodiment, the plate-like light emitter 10 is a suitable means for obtaining a tabular particle-like light emitter powder. It can also be said that the buffer layer 2 is formed to act as a release layer.

  In order to obtain light emission at a desired wavelength with excellent luminous efficiency in a processed product produced using a powder phosphor, it is necessary that the crystal orientations of individual phosphor particles after processing are aligned to some extent. As described above, each unit light emitter 20A has a flat plate shape and is c-axis oriented. For example, a phosphor powder having the unit light emitter 20A as powder particles is processed by paste application or molding. In that case, the crystal orientation is easily aligned in the processed product. Therefore, according to the phosphor powder, the degree of freedom of processing is suitably ensured, and high luminous efficiency can be obtained even in processed products. Since the average particle diameter of the unit light emitter 20A is substantially the same as the particle diameter of the oriented alumina substrate 1 used for the production of the plate-like light emitter 10, if the average particle diameter of the oriented alumina substrate 1 is appropriately determined, A light emitter having an average particle size according to the above is obtained.

  On the other hand, for example, in the case of a light-emitting body manufactured by the method disclosed in Patent Document 2, it is difficult to control the shape, and the growth orientation differs depending on the crystal plane of the base crystal. Therefore, it is difficult to control the crystal orientation in the processed product, and high luminous efficiency cannot be expected.

  As described above, according to the present embodiment, by separating the aligned alumina substrate by the laser lift-off method from the plate-like light emitter formed by the method according to the first embodiment, By separating the unit light emitters, a particulate light emitter having a small composition variation can be obtained. In addition, since the light-emitting body has a flat plate shape and is c-axis-oriented, the crystal orientation is easily aligned even in a processed product obtained by processing such as coating or molding, and high luminous efficiency can be obtained. It becomes possible.

<Modification>
In the above-described embodiment, the light emitting layer 4 is provided in the InGaN / GaN MQW structure in which the first unit layers 4a and the second unit layers 4b are alternately and repeatedly stacked. In addition to this, the light emitting layer 4 contains rare earth elements such as Pr (praseodymium), Eu (europium), Er (erbium), Tm (thulium), Ce (cerium), Nd (neodymium), and Gd (gadolinium). Thus, the emission intensity may be increased. For example, the rare earth element may be contained by doping during crystal growth, or may be a quantum dot. Alternatively, an ion implantation may be performed after crystal growth.

Example 1
In this example, eight kinds of oriented alumina substrates 1 having different c-axis orientation degrees in alumina crystals were prepared, and each of them was used to form a plate-like light emitter 10 (No. 1-a to No. 1-a to 1-h) was produced. And about seven types of obtained plate-like light-emitting bodies 10, the light emission characteristic was evaluated.

  In obtaining the oriented alumina substrate 1, first, an alumina powder having an average particle diameter of 35 μm is used as a raw material, and the alumina particles are sintered under various conditions while being oriented in the c-axis to form a wafer shape having a diameter of 2 inches and a thickness of 400 μm. Eight types of c-axis oriented sintered bodies were prepared. And the surface of each sintered compact was smoothed by grind | polishing using a nano diamond abrasive grain, and eight types of orientation alumina substrates 1 with surface roughness Rms = about 0.5 nm were obtained.

  In order to evaluate the degree of c-axis orientation of the obtained eight types of oriented alumina substrates 1, XRC measurement of the alumina (006) plane was performed to obtain the RC half width. The RC half-value widths of the eight kinds of oriented alumina substrates 1 were different in the range of 1.5 degrees to 7.1 degrees. At this time, the slit was adjusted so that the beam diameter of incident X-rays was about φ1.5 mm on the substrate. Further, when observed with a laser microscope, the average particle diameter of the alumina crystals in the substrate in-plane direction was different in each oriented alumina substrate 1, but all were in the range of 30 μm to 100 μm.

  About each oriented alumina substrate 1, it mounted on the susceptor in a MOCVD furnace, after raising the substrate temperature to 1200 degreeC in hydrogen atmosphere and performing a cleaning process, lowering the substrate temperature to 520 degreeC, using hydrogen as a carrier gas, Using TMG (trimethylgallium) and ammonia as raw materials, a GaN layer as the buffer layer 2 was formed to a thickness of 10 nm.

  Next, the substrate temperature is raised to 1100 ° C. using nitrogen and hydrogen as carrier gases, TMG (trimethylgallium) and ammonia are used as source gases, silane gas is used as a dopant source, and the first n-type GaN layer 3 is formed to a thickness of 100 nm. Formed.

Subsequently, the substrate temperature is lowered to 750 ° C., nitrogen alone is used as a carrier gas, TMG, TMI (trimethylindium), and ammonia are used as source gases, and silane gas is used as a dopant source, and In _0. The formation of the ₁₅ Ga _0.85 N layer and the formation of the GaN layer as the second unit layer 4b were alternately performed five times to form the light emitting layer 4 having the MQW structure. The thickness of the In _0.15 Ga _0.85 N layer was 4 nm, and the thickness of the GaN layer was 10 nm.

  Finally, the substrate temperature is raised again to 1100 ° C., and the second n-type GaN layer 5 is formed to a thickness of 100 nm using nitrogen and hydrogen as carrier gases, TMG and ammonia as source gases, and silane gas as a dopant source. And a cap layer. Thereby, the plate-like light emitter 10 was obtained.

  Thereafter, the susceptor temperature was lowered to room temperature while keeping the inside of the furnace in a nitrogen atmosphere, and the obtained laminated structure was taken out.

  Each laminated structure was observed with a laser microscope from the surface (upper surface of the second n-type GaN layer 5) side. As a result, the groove 6 was formed and the grain size in the crystal plane was an oriented alumina substrate. It was confirmed that the particle size was almost the same. In addition, No. A laser microscope image of 1-e is shown in FIG. Furthermore, as a result of observing the crystal orientation of the laminated structure by EBSD (Electron Back Scatter Diffraction), the crystal orientation of the nitride layer formed on the oriented alumina substrate 1 is the alumina of the oriented alumina substrate 1. It was confirmed to follow the crystal orientation of the crystal.

  That is, it was confirmed that all of the obtained eight types of laminated structures had a configuration as the plate-like light emitter 10.

  CL measurement was performed for each plate-like light emitter 10. Specifically, the plate-like light-emitting body 10 to be measured placed in a scanning electron microscope (JSM-6300 (manufactured by JEOL)) is irradiated with an electron beam at an acceleration voltage of 15 kV, and obtained by such irradiation. The spectral spectrum of the luminescence (fluorescence) from the plate-like illuminant 10 was measured with a CL measurement system (MP-18MS type (manufactured by Horiba Joban Yvon)) installed in an electron microscope.

(Example 2)
In this example, three types of phosphor powders according to the second embodiment were produced, and phosphor plates (No. 2-a to 2-c) were produced using each of them to evaluate the emission characteristics.

  Specifically, first, in the same procedure as in Example 1, three kinds of oriented alumina substrates 1 having different degrees of c-axis orientation in alumina crystals were prepared, and a plate-like light emitter 10 was produced using them.

  In this process, in order to evaluate the degree of c-axis orientation of the three types of oriented alumina substrates 1 obtained, XRC measurement of the alumina (006) plane was performed and the RC half width was determined. The RC half-value widths in the range of 2.2 degrees to 6.0 degrees were different. Further, when observed with a laser microscope, the average particle diameter of the alumina crystals in the substrate in-plane direction was different in each oriented alumina substrate 1, but all were in the range of 30 μm to 100 μm.

  Further, when the obtained plate-like light emitter 10 was observed with a laser microscope, the particle size in the crystal plane was almost the same as the particle size of the oriented alumina substrate.

  With respect to each plate-like light emitter 10, the oriented alumina substrate 1 side is irradiated with laser light, and the oriented alumina substrate 1 is separated at the buffer layer 2 by a laser lift-off method, and a light emitter comprising a large number of unit light emitters 20A. A powder was obtained.

  Further, the obtained phosphor powder and a nitrocellulose solution were mixed to form a paste and applied to a glass plate (glass substrate) with an ITO film. By heating for a minute, fluorescent plates (No. 2-a to 2-c) in which the phosphor powders are closely adhered were produced.

  CL measurement was performed on each fluorescent plate in the same manner as in Example 1.

(Comparative Example 1)
A plate-like light emitter (No. 3-a) was prepared in the same procedure as in Example 1 except that a c-axis oriented single crystal sapphire substrate was used instead of the oriented alumina substrate 1, and CL measurement was performed in the same manner as in Example 1. Went. Note that the c-axis oriented single crystal sapphire substrate is a substrate that can be regarded as having virtually no c-axis variation with respect to the normal direction (the angle between the normal direction and the c-axis direction is 0 degree). Therefore, RC half width measurement is not performed on the c-axis oriented single crystal sapphire substrate. Also, no groove was formed on the surface of the plate-like light emitter.

(Comparative Example 2)
A phosphor plate (No. 3-b) was prepared in the same procedure as in Example 2 except that P55, BM powder, which is a known blue fluorescent powder, was used instead of the phosphor powder composed of the unit phosphor 20A. In the same manner as in Example 1, light emission evaluation by the CL method was performed.

(Contrast between Example and Comparative Example)
All eight types of plate-like light emitters 10 (No. 1-a to 1-h) of Example 1, all three types of fluorescent plates (No. 2-a to 2-c) of Example 2, and Comparative Example 1 CL measurement results (emission wavelength (peak wavelength in emission spectrum), emission intensity, wavelength half-width) of the plate-like light emitter (No. 3-a) and the fluorescent plate (No. 3-b) of Comparative Example 2 Is shown in Table 1. About Example 1 and Example 2, the measured value of RC half value width of oriented alumina substrate 1 is also shown collectively. The value of the RC half width in Comparative Example 1 is not an actual measurement value but an assumed value.

  In addition, No. The plate-like light emitters 10 of 1-a to 1-h are ordered in ascending order of the RC half value width of the oriented alumina substrate 1, and the emission intensity is all No. The emission intensity in the 1-c plate-like light emitter 10 is normalized as 100.

  As can be seen from Table 1, in all the plate-like light emitters 10 of Examples and Comparative Examples, light emission having an emission wavelength (peak wavelength in the emission spectrum) of 450 nm was obtained. However, the emission intensity and the half width of the wavelength were different from each other.

  As for the wavelength half width, in both Example 1 and Example 2, the value tends to increase as the RC half width of the oriented alumina substrate 1 increases.

  On the other hand, as for the emission intensity, in Example 1, the RC half width value of the oriented alumina substrate 1 falls within the range of 2.0 degrees to 6.5 degrees. In 1-c to 1-g plate-like light emitters 10 and all the three types of fluorescent plates of Example 2, good values were obtained as compared with Comparative Example 1 and Comparative Example 2. In Example 1, the RC half width value was 4.3 degrees. The light emission intensity was maximized with the plate-shaped light emitter 10 of 1-e, and in Example 2, the value of RC half width was 3.5 degrees. The emission intensity was maximized with the 2-b plate-like light emitter 10. On the other hand, in Comparative Example 1, the emission intensity was the lowest.

  In Example 1, the reason why the light emission intensity is low in the plate-like light emitter 10 having an RC half-width value of less than 2.0 degrees in the oriented alumina substrate 1 is that the light emission intensity in Comparative Example 1 is low. In the oriented alumina substrate 1 having a smaller RC half width and a higher c-axis orientation, the groove 6 is less likely to be formed in the process of forming the light emitting structure 20, and the surface of the plate-like light emitter 10 tends to be flattened. Therefore, it is considered that the light extraction efficiency was lowered.

  On the other hand, when the value of the half width of RC in the oriented alumina substrate 1 exceeds 6.5 degrees, the fact that the emission intensity decreases is also considered that the wavelength half width increases, the InGaN constituting the MQW structure in the light emitting layer 4. This is because growth in a growth direction other than the c-axis is likely to occur during the growth of the layer, and as a result, the variation in In concentration between the individual unit light emitters 20A increases, and as a result, the variation in emission wavelength increases. Conceivable.

  In addition, the fact that high emission intensity was obtained in the phosphor plate of Example 2 means that the crystal orientations of the individual phosphor powder particles are sufficiently aligned in the phosphor plate.

  The reason why the emission intensity of Example 2 is higher than that of Example 1 is that the particulate light emitter separated from the oriented alumina substrate 1 is used, and therefore the light extraction efficiency from the inside of the particles is high. Conceivable.

  Furthermore, No. 1 of Example 1 with high luminescence intensity. When the measurement results of 1-c to 1-g plate-like illuminant 10 and all three types of phosphor plates of Example 2 are compared with the measurement results of the phosphor plate of Comparative Example 2 prepared using a conventionally known illuminant, Although the half-wave widths are about the same, the emission intensity in the example is significantly higher than that of Comparative Example 2. Such a result is obtained by using a plate-like light emitter manufactured using the oriented alumina substrate 1 having an RC half-width value of 2.0 degrees or more and 6.5 degrees or less, or powder-like light emission prepared from the plate-like light emitter. This means that the body has a wavelength half-value width comparable to that of the prior art and has a luminous efficiency superior to that of the prior art.

DESCRIPTION OF SYMBOLS 1 Oriented alumina substrate 1a, 1b, 1c, 1d Alumina crystal 1g Grain boundary (of oriented alumina substrate) 2 Buffer layer 3 First n-type GaN layer 4 Light emitting layer 4a First unit layer 4b Second unit layer 5 Second N-type buffer layer 6 groove 10 plate-like light emitter 20 light emitter structure 20A unit light emitter 20s (light emitter structure) side surface

Claims (29)

A light emitter made of a group 13 nitride semiconductor and having a light emitting layer that emits fluorescence,
It has a tabular grain shape with the c-plane as the main surface,
The average size in the in-plane direction of the main surface is 30 μm or more and 100 μm or less,
A unit luminous body characterized by the above. The unit light emitter according to claim 1,
Each is a laminate of a plurality of layers with c-axis orientation,
A part of the plurality of layers is the light emitting layer,
A unit luminous body characterized by the above. The unit light emitter according to claim 2, wherein
The light emitting layer has a multiple quantum well structure in which first unit layers and second unit layers having different compositions are repeatedly and alternately stacked;
A unit luminous body characterized by the above. The unit light emitter according to claim 3,
The first unit layer is made of InGaN, and the second unit layer is made of GaN;
A unit luminous body characterized by the above.   A light emitter comprising a plurality of unit light emitters, each of which is the unit light emitter according to any one of claims 2 to 4. The light emitter according to claim 5,
The plurality of unit light emitters are provided on one substrate.
A light emitter characterized by that. The light emitter according to claim 6,
The one substrate is a c-axis oriented polycrystalline substrate;
One unit light emitter is provided on each crystal of the polycrystalline substrate,
The c-axis orientation of the one unit light emitter follows the c-axis orientation of the crystal immediately below,
A groove is provided between the unit light emitters.
A light emitter characterized by that. The light emitter according to claim 7,
The groove is provided along a grain boundary of the polycrystalline substrate;
A light emitter characterized by that. The light emitter according to claim 7 or claim 8,
The one substrate is a c-axis oriented polycrystalline alumina substrate;
The value of the X-ray rocking curve half-value width for the alumina (006) plane in the polycrystalline alumina substrate is 2.0 degrees to 6.5 degrees.
A light emitter characterized by that. The light emitter according to claim 6,
The plurality of unit light emitters are closely fixed on the one substrate.
A light emitter characterized by that. a c-axis oriented polycrystalline substrate;
A light-emitting structure made of a group 13 nitride semiconductor and provided on the polycrystalline substrate;
With
The light emitter structure is formed of a plurality of unit light emitters each provided on an individual crystal of the polycrystalline substrate and having a light emitting layer that emits fluorescence;
The c-axis orientation of each of the plurality of unit light emitters follows the c-axis orientation of the crystal immediately below,
A groove is provided between each of the plurality of unit light emitters.
A light emitter characterized by that. The light emitter according to claim 11,
The groove is provided along a grain boundary of the polycrystalline substrate;
A light emitter characterized by that. The light emitter according to claim 11 or 12,
The polycrystalline substrate is a c-axis oriented polycrystalline alumina substrate;
The value of the X-ray rocking curve half-value width for the alumina (006) plane in the polycrystalline alumina substrate is 2.0 degrees to 6.5 degrees.
A light emitter characterized by that. The light emitter according to any one of claims 11 to 13,
The average size in the in-plane direction of the polycrystalline alumina substrate is 30 μm or more and 100 μm or less,
A light emitter characterized by that. The light emitter according to any one of claims 11 to 14,
The plurality of unit light emitters is a laminate of a plurality of layers each having a c-axis orientation,
A part of the plurality of layers is the light emitting layer,
A light emitter characterized by that. The light emitter according to claim 15,
The light emitting layer has a multiple quantum well structure in which first unit layers and second unit layers having different compositions are repeatedly and alternately stacked;
A light emitter characterized by that. The light emitter according to claim 16, wherein
The first unit layer is made of InGaN, and the second unit layer is made of GaN;
A light emitter characterized by that. A method of manufacturing a light emitter, comprising:
Each crystal present on the principal surface of the c-axis oriented polycrystalline substrate is made of a group 13 nitride semiconductor, has a c-axis orientation that follows the c-axis orientation of the crystal, and has a light emitting layer that emits fluorescence. A unit light emitter is grown while providing a groove between the unit light emitters to form a light emitter structure composed of a plurality of the unit light emitters.
A method of manufacturing a luminescent material characterized by the above. A method of manufacturing a light emitter according to claim 18,
Forming the groove along a crystal grain boundary of the polycrystalline substrate;
A method of manufacturing a luminescent material characterized by the above. A method of manufacturing a light emitter according to claim 18 or claim 19,
As the polycrystalline substrate, a c-axis oriented polycrystalline alumina substrate having an X-ray rocking curve half-width value of 2.0 degrees to 6.5 degrees with respect to the alumina (006) plane is used.
A method of manufacturing a luminescent material characterized by the above. A method of manufacturing a light emitter according to any one of claims 18 to 20,
The average size in the in-plane direction of the polycrystalline alumina substrate is 30 μm or more and 100 μm or less,
A method of manufacturing a luminescent material characterized by the above. A method of manufacturing a light emitter according to any one of claims 18 to 21,
A plurality of unit light emitters are formed by laminating a plurality of layers each of which is c-axis oriented, and a part of the plurality of layers is formed as the light emitting layer.
A method of manufacturing a luminescent material characterized by the above. A method of manufacturing a light emitter according to claim 22,
The light emitting layer is formed as a multiple quantum well structure by repeatedly laminating first unit layers and second unit layers having different compositions.
A method of manufacturing a luminescent material characterized by the above. A method for producing a light emitter according to claim 23, wherein
Forming the first unit layer with InGaN and forming the second unit layer with GaN;
A method of manufacturing a luminescent material characterized by the above. A method for producing a phosphor powder that emits fluorescence, comprising:
A light emitter manufacturing step for obtaining a light emitter by the manufacturing method according to any one of claims 18 to 24,
In the light emitter, by separating the polycrystalline substrate from the light emitter structure, the individual light emitter units are separated from each other in the light emitter structure, thereby obtaining a phosphor powder,
A method for producing a phosphor powder, comprising: A method for producing a phosphor powder according to claim 25,
In the luminous body manufacturing step, a release layer is formed between the polycrystalline substrate and the luminous body structure,
In the powder production step, the polycrystalline substrate is peeled from the light emitter structure at the release layer by irradiating the light emitting body with laser light on the polycrystalline substrate side.
A method for producing a phosphor powder characterized by the above. A method for producing a phosphor powder that emits fluorescence, comprising:
A light emitter preparation step for preparing the light emitter according to any one of claims 11 to 17,
In the light emitter, by separating the polycrystalline substrate from the light emitter structure, the individual light emitter units are separated from each other in the light emitter structure, thereby obtaining a phosphor powder,
A method for producing a phosphor powder, comprising: A method for producing a phosphor powder according to claim 27,
The phosphor has a release layer between the polycrystalline substrate and the phosphor structure;
In the powder production step, the polycrystalline substrate is peeled from the light emitter structure at the release layer by irradiating the light emitting body with laser light on the polycrystalline substrate side.
A method for producing a phosphor powder characterized by the above. A method for producing a phosphor powder according to any one of claims 25 to 28, comprising:
Powder particles of the phosphor powder,
It has a flat plate shape with the c-plane as the main surface,
The average size in the in-plane direction of the main surface is 30 μm or more and 100 μm or less,
A method for producing a phosphor powder characterized by the above.