JP6955704B2 - Light emitting device - Google Patents

Description

The present invention relates to a light emitting device.

Conventionally, a light emitting element composed of an LED (Light Emitting Diode) that emits blue light and a phosphor that is excited by receiving the light of this light emitting element and emits yellow light are provided, and white light is obtained by mixing these emission colors. A light emitting device that emits light is known (see, for example, Patent Document 1).

In the light emitting device described in Patent Document 1, a granular phosphor is contained in an epoxy resin and arranged around a light emitting element that emits blue light, and the light emitted from the light emitting element itself and the yellow light emitted by the phosphor are used. It is configured to emit white light by mixing.

Japanese Unexamined Patent Publication No. 2010-155891

With the increase in power of the light emitting device, heat generation of the light emitting element becomes a big problem. Specifically, it is a characteristic variation of the light emitting device caused by mutual influence of the fluctuation of the light emitting characteristic due to the input power to the element and the fluctuation of the characteristic due to the temperature rise of the phosphor.

In general, a phosphor has inherent quantum efficiency (efficiency of converting excitation light into fluorescence) and temperature quenching property (property that quantum efficiency decreases as the temperature rises). If the quantum efficiency is high, a light emitting device having a higher brightness using a phosphor can be obtained, and if the temperature quenching characteristic is excellent, it can be used in a light emitting device having a higher output.

Therefore, one of the objects of the present invention is to provide a light emitting device using a single crystal phosphor that exhibits excellent characteristics even under high temperature conditions.

One aspect of the present invention provides the following light emitting devices [1] to [5] in order to achieve the above object.

[1] A laser element that emits a laser beam having a peak light amount at a wavelength of 380 to 490 nm and a laser element that is arranged apart from the laser element to absorb the laser beam and have a temperature of 514 to 544 nm at 25 ° C. and a plate-shaped single crystal phosphor that emits wavelength-converted light having a peak of light intensity to wavelength, the single crystalline phosphor composition formula _{(Y 1-x-y-} z Lu x Gd y Ce z) 3 + a The _{composition represented by Al 5-a} O ₁₂ (0 ≦ x ≦ 0.9994, 0 ≦ y ≦ 0.0302, 0.0006 ≦ z ≦ 0.0067, −0.010 ≦ a ≦ 0.251) A light emitting device having a value of the ratio of the internal quantum efficiency at 300 ° C. to the internal quantum efficiency at 25 ° C. of 0.82 to 1.00 when the peak wavelength of the laser light is 450 nm .

[ 2 ] The light emitting device according to the above [1] , which is used for any one of a laser projector and a laser headlight.

[ 3 ] The light emitting device according to the above [1] or [2] , wherein x + z = 1 and y = 0 in the composition.

[ 4 ] The flat plate-shaped single crystal phosphor is bonded to the upper surface of the main body surrounding the laser element, which has an opening located on the laser element. [1] to [ 3 ] The light emitting device according to any one of the above items.

[5] The flat plate-shaped single crystal phosphor has a light incident surface of larger area than the light emitting surface of the laser element, the [1] to the light emitting device according to any one of [4].

According to one aspect of the present invention, it is possible to provide a light emitting device using a single crystal phosphor that exhibits excellent characteristics even under high temperature conditions.

FIG. 1 is a cross-sectional view schematically showing pulling up of a single crystal phosphor ingot by the CZ method according to the first embodiment. FIG. 2A is a graph showing the relationship between the peak wavelength of fluorescence (nm) and the internal quantum efficiency η _{int (300 ° C.) of the single crystal phosphor according to the first embodiment.} Further, FIG. 2B shows the value of the ratio of the peak wavelength (nm) of fluorescence and the internal quantum efficiency of the single crystal phosphor according to the present embodiment η _int (300 ° C.) / η _int (25 ° C.). It is a graph showing the relationship with. FIG. 3 shows the relationship between the peak wavelength of fluorescence (nm) of the single crystal phosphor according to the first embodiment and the value of the ratio of the external quantum efficiency η _ext (300 ° C.) / η _ext (25 ° C.). It is a graph showing. FIG. 4A is a vertical cross-sectional view of the light emitting device according to the second embodiment, and FIG. 4B is a vertical cross-sectional view of the light emitting element constituting the light emitting device and its peripheral portion. 5 (a) is a vertical cross-sectional view of a light emitting device according to a third embodiment, FIG. 5 (b) is a vertical cross-sectional view of a light emitting element constituting the light emitting device, and FIG. 5 (c) is a light emitting device. It is a top view of the element. FIG. 6 is a vertical cross-sectional view of the light emitting device according to the fourth embodiment. FIG. 7 is a vertical cross-sectional view of the light emitting device according to the fifth embodiment. FIG. 8A is a vertical cross-sectional view of the light emitting device according to the sixth embodiment, and FIG. 8B is a vertical cross-sectional view of the light emitting element constituting the light emitting device. FIG. 9 is a vertical cross-sectional view of the light emitting device according to the seventh embodiment. FIG. 10A is a vertical cross-sectional view of the light emitting device according to the eighth embodiment, and FIG. 10B is a vertical cross-sectional view of the light emitting element constituting the light emitting device and its peripheral portion. FIG. 11 is a vertical cross-sectional view of the light emitting device according to the ninth embodiment.

[First Embodiment]
[Single crystal phosphor]
The single crystal phosphor according to the first embodiment _{is a YAG-based phosphor having a Y 3} Al ₅ O ₁₂ (YAG) crystal as a mother crystal, and has a composition formula (Y _1-x-y-z Lu _x Gd). _{y Ce z) 3 + a Al} 5-a O 12 (0 ≦ x ≦ 0.9994,0 ≦ y ≦ 0.0669,0.0002 ≦ z ≦ 0.0067, at -0.016 ≦ a ≦ 0.315) Has the composition represented. Here, Lu and Gd are components that do not serve as emission centers that replace Y. Ce is a component (activation agent) that can serve as a light emitting center that replaces Y.

In the composition of the above-mentioned single crystal phosphor, some atoms may occupy different positions in the crystal structure. Further, the O value of the composition ratio in the above composition formula is described as 12, but in the above composition, the O value of the composition ratio is slightly deviated from 12 due to the presence of oxygen inevitably mixed or deficient. Also includes composition. Further, the value of a in the composition formula is a value that inevitably changes in the production of the single crystal phosphor, but the change within the numerical range of about −0.016 ≦ a ≦ 0.315 is a single crystal. It has almost no effect on the physical properties of the phosphor.

Further, the phosphor of the present embodiment is characterized in that it does not contain Group 2 elements such as Ba and Sr and Group 17 elements such as F and Br, and has high purity. With these features, a phosphor with high brightness and long life can be realized.

The range of the numerical value of z in the above composition formula representing the concentration of Ce is 0.0002 ≦ z ≦ 0.0067 because when the numerical value of y is smaller than 0.0002, the Ce concentration is too low. There is a problem that the absorption of excitation light becomes small and the external quantum efficiency becomes too small. If it is larger than 0.0067, cracks and voids occur when growing an ingot of a single crystal phosphor, and the crystal quality is deteriorated. This is because there is a high possibility that it will decrease.

This single crystal phosphor can be obtained by, for example, a liquid phase growth method such as the CZ method (Czochralski Method), the EFG method (Edge Defined Film Fed Growth Method), the Bridgman method, the FZ method (Floating Zone Method), and the Verneuil method. Can be done. By cutting the single crystal phosphor ingot obtained by these liquid phase growth methods and processing it into a flat plate, or by pulverizing it and processing it into a powder, it can be used in a light emitting device described later.

The single crystal phosphor of this embodiment has excellent internal quantum efficiency. For example, the internal quantum efficiency is 0.91 or more when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm.

According to Table A1.3 on page 69 of the literature Solid-State Lighting Research and Development: Multi Year Program Plan March 2011 (Updated May 2011), 2010 of internal quantum efficiency (Quantum Yield (25 ° C) across the visible spectrum) It is stated that the year number is 0.90 and the target value for 2020 is 0.95. From this, it can be seen that the industry is expected to improve the quantum efficiency by about 0.01 in two years, and the phosphor of the present embodiment is close to or exceeds the target value at the time of filing. It can be said that it is an excellent phosphor having quantum efficiency.

Further, at least a part of the single crystal phosphor of the present embodiment (details will be described later) has a fluorescence peak wavelength of 514 nm or more and 544 nm or less when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm. In a certain sample, the internal quantum efficiency is 0.90 or more when the temperature is 300 ° C. and the peak wavelength of the excitation light is 450 nm.

Further, in a sample in which the peak wavelength of fluorescence is larger than 544 nm and 546 nm or less when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm, the inside when the temperature is 300 ° C. and the peak wavelength of the excitation light is 450 nm. The quantum efficiency is 0.80 or more.

Since these single crystal phosphors can maintain high internal quantum efficiency even under a high temperature condition of 300 ° C., for example, such as a laser projector or a laser headlight in which the excitation light is laser light, per unit area. It can exhibit excellent functions as a phosphor used in a light emitting device having extremely high brightness.

Further, the single crystal phosphor exhibiting high internal quantum efficiency when the temperature is 300 ° C. has excellent temperature quenching characteristics. For example, in a sample in which the peak wavelength of fluorescence is 514 nm or more and 544 nm or less when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm, the inside when the temperature is 300 ° C. and the peak wavelength of the excitation light is 450 nm. The value of the ratio of the quantum efficiency to the internal quantum efficiency when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm is 0.90 or more.

Further, in a sample in which the peak wavelength of fluorescence is larger than 544 nm and 546 nm or less when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm, the inside when the temperature is 300 ° C. and the peak wavelength of the excitation light is 450 nm. The value of the ratio of the quantum efficiency to the internal quantum efficiency when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm is 0.80 or more.

Further, for example, in a sample in which the peak wavelength of fluorescence is 514 nm or more and 544 nm or less when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm, when the temperature is 300 ° C. and the peak wavelength of the excitation light is 450 nm. The value of the ratio of the external quantum efficiency to the external quantum efficiency when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm is 0.85 or more.

Further, in a sample in which the peak wavelength of fluorescence is larger than 544 nm and 546 nm or less when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm, the outside when the temperature is 300 ° C. and the peak wavelength of the excitation light is 450 nm. The value of the ratio of the quantum efficiency to the external quantum efficiency when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm is 0.80 or more.

[Comparison with polycrystalline phosphor]
The relationship between the concentration of Ce and the emission color is significantly different between the YAG-based single crystal phosphor activated by Ce and the YAG-based polycrystalline phosphor powder. For example, Patent Document (JP-2010-24278), 0.003 ≦ z ≦ a polycrystalline phosphor powder having a composition represented by the composition formula _{(Y 1-z Ce z)} 3 Al 5 O 12 It is described that it emits light with a constant chromaticity (0.41, 0.56) in the Ce concentration range of 0.2. On the other hand, in the single crystal phosphor of the present embodiment, the chromaticity changes depending on the Ce concentration, and for example, the chromaticity (0.41, 0.56) is the same as that of the polycrystalline phosphor powder of the above patent document. the composition for emitting light is _{(Y 1-z Ce z)} 3 Al 5 O 12 (z = 0.0005).

Further, in Patent Document (Japanese Patent No. 3503139), a polycrystalline phosphor powder having a composition represented by _{the composition formula (Y 1-ab} Lu _a Ce _b ) ₃ Al ₅ O _{12 is a = 0.} When .99 and b = 0.01, the emission chromaticity is (0.339, 0.579), and when a = 0.495 and b = 0.01, the emission chromaticity is (0.377, 0.570). ) Is stated. The concentration of Ce contained in the polycrystalline phosphor powder is also orders of magnitude higher than the concentration of Ce contained in the single crystal phosphor of the present embodiment.

As described above, in the single crystal phosphor, the concentration of Ce added to emit light of a desired color is extremely low as compared with the polycrystalline phosphor, and the amount of expensive Ce used can be reduced. can.

An example of a method for producing a single crystal phosphor according to the present embodiment will be described below. In the following example, the single crystal phosphor is grown by the Czochralski method (CZ method).

[Manufacturing of single crystal phosphor]
First, high-purity (99.99% or more) _{powders of Y 2} O ₃ , Lu ₂ O ₃ , Gd ₂ O ₃ , CeO ₂ , and Al ₂ O ₃ are prepared as starting materials, and dry-mixed and mixed. Get the powder. The raw material powders of Y, Lu, Gd, Ce, and Al are not limited to those described above. Further, when producing a single crystal phosphor containing no Lu or Gd, those raw material powders are not used.

FIG. 1 is a cross-sectional view schematically showing the pulling up of a single crystal phosphor ingot by the CZ method. The crystal growing device 80 mainly includes an iridium crucible 81, a ceramic tubular container 82 accommodating the crucible 81, and a high-frequency coil 83 wound around the tubular container 82.

The obtained mixed powder is put into the crucible 81, and a high frequency energy of 30 kW is supplied to the crucible 81 by a high frequency coil 83 in a nitrogen atmosphere to generate an induced current, and the crucible 81 is heated. As a result, the mixed powder is melted to obtain a melt 90.

Next, a seed crystal 91, which is a YAG single crystal, is prepared, and the tip thereof is brought into contact with the melt 90, and then the seed crystal 91 is pulled up at a pulling speed of 1 mm / h or less while rotating at a rotation speed of 10 rpm to 1960 ° C. or higher. The single crystal phosphor ingot 92 is grown in the <111> direction at the raising temperature. The growth of the single crystal phosphor ingot 92 is carried out by pouring nitrogen into a cylindrical container at a flow rate of 2 L / min, under atmospheric pressure, and in a nitrogen atmosphere.

Thus, for example, a single crystal phosphor ingot 92 having a diameter of about 2.5 cm and a length of about 5 cm can be obtained. By cutting out the obtained single crystal phosphor ingot 92 to a desired size, for example, a flat plate-shaped single crystal phosphor used in a light emitting device can be obtained. Further, by pulverizing the single crystal phosphor ingot 92, a particulate single crystal phosphor can be obtained.

[Evaluation of single crystal phosphor]
Single crystal phosphors according to a plurality of first embodiments having different compositions were produced, and the composition was analyzed, the CIE chromaticity, the internal quantum efficiency, and the external quantum efficiency were evaluated.

Composition analysis was performed by radio frequency inductively coupled plasma (ICP) emission spectroscopy. In addition, ICP mass spectrometry (ICP-MS) was used in combination with a single crystal phosphor having an extremely low Ce concentration.

In the evaluation of the CIE chromaticity coordinates, the CIE chromaticity coordinates of the emission spectrum of the single crystal phosphor when the peak wavelength of the excitation light was 450 nm were obtained by using the CIE 1931 color matching function.

Evaluation of internal quantum efficiency and external quantum efficiency was performed using a quantum efficiency measurement system equipped with an integrating hemisphere unit. The specific measurement methods of the internal quantum efficiency and the external quantum efficiency of the single crystal phosphor will be described below.

First, the barium sulfate powder as a standard sample placed in the integrating hemisphere unit is irradiated with excitation light, and the excitation light spectrum is measured. Next, the single crystal phosphor placed on barium sulfate in the integrating hemisphere unit is irradiated with excitation light, and the excitation reflected light spectrum and the fluorescence emission spectrum are measured. Next, the excitation light diffusely reflected in the integrating hemisphere unit is irradiated to the single crystal phosphor placed on barium sulfate, and the re-excitation fluorescence emission spectrum is measured.

Then, the difference between the photon number obtained from the fluorescence emission spectrum and the photon number obtained from the re-excitation fluorescence emission spectrum is divided by the difference between the photon number obtained from the excitation light spectrum and the photon number obtained from the excitation reflected light spectrum. By doing so, the internal quantum efficiency is obtained.

Further, the external quantum efficiency is obtained by dividing the difference between the photon number obtained from the fluorescence emission spectrum and the photon number obtained from the reexcitation fluorescence emission spectrum by the photon number obtained from the excitation light spectrum.

The results of the evaluation are shown in Tables 1 and 2 below. Table 1 shows the evaluation results of the single crystal phosphor samples of sample numbers 1 to 23, and Table 2 shows the evaluation results of the single crystal phosphor samples of sample numbers 24 to 46.

Tables 1 and 2 show the values of x, y, z, and a in the composition formula of the single crystal phosphor according to the present embodiment, the temperature (° C.) of the single crystal phosphor at the time of measurement, and the peak wavelength of the excitation light. _{Internal quantum efficiency (η int} ) at 440, 450, 460 nm, _{η int} (300 ° C) / η _int (25 ° C), which is an index of the temperature characteristics of internal quantum efficiency η _int , and the peak wavelength of excitation light is 440. , 450 nm, external quantum efficiency (η _{ext ), η int} (300 ° C) / η _int (25 ° C), which is an index of the temperature characteristics of the external quantum efficiency η _ext , and the peak wavelength of the excitation light is 450 nm. The peak wavelength λp (nm) of fluorescence at a certain time and the CIE chromaticity coordinates when the peak wavelength of excitation light is 450 nm are shown.

Here, η _int (300 ° C.) has an internal quantum efficiency when the temperature is 300 ° C. and the peak wavelength of the excitation light is 450 nm, and η _int (25 ° C.) has a temperature of 25 ° C. and the peak wavelength of the excitation light is 450 nm. It is the internal quantum efficiency at a certain time, and η _int (300 ° C.) / η _int (25 ° C.) is a value of the ratio of _{η int} (300 ° C.) to η _{int (25 ° C.).} Further, η _ext (300 ° C.) has an external quantum efficiency when the temperature is 300 ° C. and the peak wavelength of the excitation light is 450 nm, and η _ext (25 ° C.) has a temperature of 25 ° C. and the peak wavelength of the excitation light is 450 nm. Η _ext (300 ° C.) / η _ext (25 ° C.) is the value of the ratio of _{η ext} (300 ° C.) to η _{ext (25 ° C.).}

Regarding the shape of the evaluated single crystal phosphor sample, the sample of sample number 2 is a circular plate having a diameter of 10 mm and a thickness of 1.0 mm, and the samples of sample numbers 17 and 23 have a diameter of 10 mm and a thickness of 0. It is a 3 mm circular plate, the sample of sample number 46 is powder, and the other samples are square plates having a side length of 10 mm and a thickness of 0.3 mm. In addition, all the samples except the powdered sample are mirror-polished on both sides.

The shape of the sample affects the measured value of the external quantum efficiency in principle, but the value of the ratio of the external quantum efficiency in the same sample, for example, the value of η _ext (300 ° C) / η _ext (25 ° C) , Does not depend on the shape of the sample. On the other hand, the measured value of internal quantum efficiency is hardly affected by the shape of the sample.

According to Table 1, the composition of the sample of the evaluated single crystal phosphor, the composition formula _{(Y 1-x-y-} z Lu x Gd y Ce z) 3 + a Al 5-a O 12 (0 ≦ x ≦ 0 It is included in the composition represented by .9994, 0 ≦ y ≦ 0.0669, 0.0002 ≦ z ≦ 0.0067, −0.016 ≦ a ≦ 0.315).

According to Table 1, the internal quantum efficiency of all the evaluated single crystal phosphor samples at a temperature of 25 ° C. and a peak wavelength of excitation light of 450 nm is 0.91 or more.

FIG. 2A shows the peak wavelength (nm) of fluorescence of the single crystal phosphor according to the present embodiment when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm, and the internal quantum efficiency η _int ( It is a graph showing the relationship with (300 ° C.). Further, FIG. 2B shows the peak wavelength (nm) of fluorescence of the single crystal phosphor according to the present embodiment when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm, and the internal quantum efficiency. It is a graph which shows the relationship with the ratio value η _int (300 ° C.) / η _{int (25 ° C.).}

The marks "○" in FIGS. 2 (a) and 2 (b) are the measured values of the flat plate-shaped single crystal phosphors (sample numbers 4, 7, 8, 30, 45) according to the present embodiment, and the marks "◇" are The measured value of the powdered single crystal phosphor (Sample No. 46), the mark “◆” is the measured value of the YAG-based polycrystalline phosphor powder activated by Ce as a comparative example.

According to FIG. 2A, the internal quantum efficiency η _int (300 ° C.) of the single crystal phosphor according to the present embodiment is the fluorescence peak when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm. In the sample having a wavelength of 514 nm or more and 544 nm or less, the fluorescence peak wavelength is greater than 544 nm and 546 nm or less when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm. 80 or more.

Further, according to FIG. 2A, the internal quantum efficiency η _int (300 ° C.) of the polycrystalline phosphor _{is smaller than the internal quantum efficiency η int} (300 ° C.) of the single crystal phosphor according to the present embodiment. When the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm, the peak wavelength of fluorescence is less than 0.85 in the sample of 514 nm or more and 544 nm or less, the temperature is 25 ° C., and the peak wavelength of the excitation light is 450 nm. When the peak wavelength of fluorescence is greater than 544 nm and less than 0.75 in a sample of 546 nm or less.

According to FIG. 2 (b), the value of the ratio of the internal quantum efficiencies of the single crystal phosphor according to the present embodiment, η _int (300 ° C.) / η _int (25 ° C.), has a temperature of 25 ° C. and the excitation light. In a sample in which the peak wavelength of fluorescence is 514 nm or more and 544 nm or less when the peak wavelength is 450 nm, the peak wavelength of fluorescence is 0.90 or more, the temperature is 25 ° C., and the peak wavelength of excitation light is 450 nm. It is 0.80 or more in a sample larger than 544 nm and 546 nm or less.

Further, according to FIG. 2B, the value of the ratio of the internal quantum efficiency of the polycrystalline phosphor, η _int (300 ° C.) / η _int (25 ° C.), is the inside of the single crystal phosphor according to the present embodiment. The peak wavelength of fluorescence is 514 nm or more and 544 nm or less when the ratio value of quantum efficiency _{is smaller than η int} (300 ° C.) / η _int (25 ° C.), the temperature is 25 ° C., and the peak wavelength of excitation light is 450 nm. In the sample, it is less than 0.90, and in the sample where the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm, the peak wavelength of fluorescence is larger than 544 nm and 546 nm or less, it is less than 0.80.

_{FIG. 3 shows the value η ext} of the ratio of the peak wavelength (nm) of fluorescence of the single crystal phosphor according to the present embodiment when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm to the external quantum efficiency. It is a graph which _shows the relationship with (300 degreeC) / η ext (25 degreeC).

The mark "○" in FIG. 3 is the measured value of the flat plate-shaped single crystal phosphor (sample numbers 4, 7, 8, 30, 45) according to the present embodiment, and the mark "◇" is the powdered single crystal phosphor. The measured value of (Sample No. 46), the mark “◆”, is the measured value of the YAG-based polycrystalline phosphor powder activated by Ce as a comparative example.

According to FIG. 3, the value of the ratio of the external quantum efficiency of the single crystal phosphor according to the present embodiment, η _ext (300 ° C.) / η _ext (25 ° C.), has a temperature of 25 ° C. and a peak wavelength of excitation light. In a sample in which the peak wavelength of fluorescence at 450 nm is 514 nm or more and 544 nm or less, the peak wavelength of fluorescence is 0.85 or more, the temperature is 25 ° C., and the peak wavelength of excitation light is 450 nm, which is larger than 544 nm. It is 0.80 or more in a sample having a wavelength of 546 nm or less.

According to FIG. 3, the value of the ratio of the external quantum efficiency of the polycrystalline phosphor is η _ext (300 ° C.) / η _ext (25 ° C.), which is the ratio of the external quantum efficiency of the single crystal phosphor according to the present embodiment. 0.85 in a sample with a fluorescence peak wavelength of 514 nm or more and 544 nm or less when the value _{is smaller than η ext} (300 ° C.) / η _ext (25 ° C.), the temperature is 25 ° C., and the peak wavelength of the excitation light is 450 nm. The peak wavelength of fluorescence is greater than 544 nm and less than 0.75 in a sample of 546 nm or less when the temperature is 25 ° C. and the peak wavelength of the excitation light is 450 nm.

[Second Embodiment]
The second embodiment of the present invention is a light emitting device using the single crystal phosphor according to the first embodiment. The second embodiment will be described below with reference to FIG. FIG. 4A is a vertical cross-sectional view of the light emitting device 1 according to the second embodiment, and FIG. 4B is a vertical cross-sectional view of the light emitting element 10 constituting the light emitting device 1 and its peripheral portion. be.

As shown in FIG. 4A, the light emitting device 1 is provided so as to cover the light emitting element 10 which is a light emitting element such as an LED and the light emitting surface of the light emitting element 10. A fluorescent substance 2 made of a crystalline phosphor, _{a ceramic substrate 3 made of Al 2} O ₃ or the like that supports the light emitting element 10, a main body 4 made of a white resin, and a transparent resin that seals the light emitting element 10 and the phosphor 2. Has 8 and.

The ceramic substrate 3 has wiring portions 31 and 32 that are patterned from a metal such as tungsten. The wiring portions 31 and 32 are electrically connected to the n-side electrode 15A and the p-side electrode 15B of the light emitting element 10.

The main body 4 is formed on a ceramic substrate 3, and an opening 4A is formed in a central portion thereof. The opening 4A is formed in a tapered shape in which the opening width gradually increases from the ceramic substrate 3 side toward the outside. The inner surface of the opening 4A is a reflecting surface 40 that reflects the light emitted by the light emitting element 10 toward the outside.

As shown in FIG. 4B, the n-side electrode 15A and the p-side electrode 15B of the light emitting element 10 are connected to the wiring portions 31 and 32 of the ceramic substrate 3 via bumps 16, respectively.

The light emitting device 10 is, for example, a flip-chip type device using a GaN-based semiconductor compound, and emits blue-based light having a light amount peak at a wavelength of, for example, 380 to 490 nm. In the light emitting element 10, an n-type GaN layer 12, a light emitting layer 13, and a p-type GaN layer 14 are formed in this order on a first main surface 11a of an element substrate 11 made of sapphire or the like. An n-side electrode 15A is formed on the exposed portion of the n-type GaN layer 12, and a p-side electrode 15B is formed on the surface of the p-type GaN layer 14.

The light emitting layer 13 emits blue light by injecting carriers from the n-type GaN layer 12 and the p-type GaN layer 14. This emitted light passes through the n-type GaN layer 12 and the element substrate 11 and is emitted from the second main surface 11b of the element substrate 11. That is, the second main surface 11b of the element substrate 11 is the light emitting surface of the light emitting element 10.

On the second main surface 11b side of the element substrate 11, the phosphor 2 is installed so as to cover the entire second main surface 11b. For example, when the phosphor 2 and the element substrate 11 are in direct contact with each other, the first surface 2a of the phosphor 2 facing the element substrate 11 and the second main surface 11b of the element substrate 11 are joined by an intramolecular force. Will be done.

The phosphor 2 is a flat plate-shaped single crystal phosphor. Since the flat plate-shaped single crystal phosphor does not need to be dispersed in the resin unlike the particulate phosphor, problems such as a change in emission color due to deterioration of the resin due to light or heat do not occur. Therefore, a light emitting device using a flat plate-shaped single crystal phosphor such as the light emitting device 1 has extremely high long-term reliability under conditions such as high brightness, high output, and high temperature. The phosphor 2 has a size equal to or larger than that of the second main surface 11b.

When the light emitting element 10 configured as described above is energized, electrons are injected into the light emitting layer 13 via the wiring portion 31, the n-side electrode 15A, and the n-type GaN layer 12, and the wiring portion 32 and the p-side electrode 15B are also energized. , And holes are injected into the light emitting layer 13 via the p-type GaN layer 14, and the light emitting layer 13 emits light. The blue emitted light of the light emitting layer 13 passes through the n-type GaN layer 12 and the element substrate 11 and is emitted from the second main surface 11b of the element substrate 11 and incident on the first surface 2a of the phosphor 2.

A part of the light incident from the first surface 2a excites the electrons in the phosphor 2 as excitation light. The phosphor 2 absorbs a part of the bluish light from the light emitting element 10 and converts the wavelength into a yellowish light having a light amount peak at a wavelength of 514 to 546 nm, for example.

A part of the bluish light incident on the phosphor 2 is absorbed by the phosphor 2 and wavelength-converted, and is emitted from the second surface 2b of the phosphor 2 as yellowish light. Further, the remaining part of the light incident on the phosphor 2 is not absorbed by the phosphor 2 and is emitted from the second surface 2b of the phosphor 2. Since blue and yellow have a complementary color relationship, the light emitting device 1 emits white light, which is a mixture of blue light and yellow light.

Further, the color temperature of the white light emitted by the light emitting device 1 can be set to 4500 K or higher. The color temperature of the white light can be adjusted by the concentration of Lu or Gd of the phosphor 2, the concentration of Ce which is an activator, or the like. Further, by adding a second phosphor having a fluorescence spectrum longer than that of the phosphor 2, the color temperature of the white light emitted by the light emitting device 1 can be adjusted to less than 4500 K.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. 5 (a) is a vertical cross-sectional view of the light emitting device 1A according to the third embodiment, FIG. 5 (b) is a vertical cross-sectional view of the light emitting element 10A constituting the light emitting device 1A, and FIG. 5 (c) is a vertical cross-sectional view. , Is a plan view of the light emitting element 10A.

The light emitting device 1A according to the present embodiment has the same configuration as the light emitting device 1 according to the second embodiment in that the light emitted from the light emitting element is incident on the single crystal phosphor and the wavelength is converted. The configuration and the arrangement position of the phosphor with respect to the light emitting element are different from those of the second embodiment. Hereinafter, the components of the light emitting device 1A having the same functions and configurations as those of the second embodiment are designated by common reference numerals and the description thereof will be omitted.

As shown in FIGS. 5A and 5B, the light emitting device 1A is arranged so that the element substrate 11 of the light emitting element 10A faces the ceramic substrate 3 side. Further, the phosphor 21 is bonded to the opening 4A side of the light emitting element 10A. The phosphor 21 is composed of the single crystal phosphor according to the first embodiment, similarly to the phosphor 2 according to the second embodiment.

As shown in FIGS. 5 (b) and 5 (c), the light emitting element 10A has an element substrate 11, an n-type GaN layer 12, a light emitting layer 13, and a p-type GaN layer 14, and further includes a p-type GaN layer 14. It has a transparent electrode 140 made of ITO (Indium Tin Oxide) on the top. A p-side electrode 15B is formed on the transparent electrode 140. The transparent electrode 140 diffuses the carriers injected from the p-side electrode 15B and injects them into the p-type GaN layer 14.

As shown in FIG. 5C, the phosphor 21 is formed in a substantially quadrangular shape having a notch in a portion corresponding to the p-side electrode 15B and the n-side electrode 15A formed on the n-type GaN layer 12. ing. Further, in the phosphor 21, the first surface 21a on the transparent electrode 140 side is bonded to the surface 140b of the transparent electrode 140 by an intramolecular force.

As shown in FIG. 5A, the n-side electrode 15A of the light emitting element 10A is connected to the wiring portion 31 of the ceramic substrate 3 by the bonding wire 311. Further, the p-side electrode 15B of the light emitting element 10A is connected to the wiring portion 32 of the ceramic substrate 3 by the bonding wire 321.

When the light emitting element 10A configured as described above is energized, electrons are injected into the light emitting layer 13 via the wiring portion 31, the n-side electrode 15A, and the n-type GaN layer 12, and the wiring portion 32 and the p-side electrode 15B are also energized. Holes are injected into the light emitting layer 13 via the transparent electrode 140 and the p-type GaN layer 14, and the light emitting layer 13 emits light.

The blue light emitted from the light emitting layer 13 passes through the p-type GaN layer 14 and the transparent electrode 140 and is emitted from the surface 140b of the transparent electrode 140. That is, the surface 140b of the transparent electrode 140 is the light emitting surface of the light emitting element 10A. The light emitted from the surface 140b of the transparent electrode 140 is incident on the first surface 21a of the phosphor 21.

A part of the light incident on the phosphor 21 from the first surface 21a excites the electrons in the phosphor 21 as excitation light. The phosphor 21 absorbs a part of the blue light from the light emitting element 10A and converts the wavelength into yellow light. More specifically, the phosphor 21 absorbs bluish light from the light emitting element 10A and emits yellowish light having an emission peak at a wavelength of, for example, 514 to 546 nm.

In this way, a part of the blue light incident on the phosphor 21 is absorbed by the phosphor 21 and wavelength-converted, and is emitted as yellow light from the second surface 21b of the phosphor 21. Further, the remaining part of the blue light incident on the phosphor 21 is not absorbed by the phosphor 21, but is emitted as it is from the second surface 21b of the phosphor 21. Since blue and yellow have a complementary color relationship, the light emitting device 1A emits white light, which is a mixture of blue light and yellow light.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 6 is a vertical cross-sectional view of the light emitting device 1B according to the fourth embodiment.

The light emitting device 1B according to the present embodiment has the same configuration as the light emitting device 1 according to the second embodiment in that the light emitted from the light emitting element is incident on the single crystal phosphor and the wavelength is converted. The placement position is different from that of the second embodiment. Hereinafter, the components of the light emitting device 1B having the same functions and configurations as those of the second or third embodiment are designated by common reference numerals and the description thereof will be omitted.

As shown in FIG. 6, the light emitting device 1B includes a light emitting element 10 having the same configuration as that of the second embodiment on the ceramic substrate 3. The light emitting element 10 emits blue light from the second main surface 11b of the element substrate 11 (see FIG. 4B) located on the opening 4A side of the main body 4 toward the opening 4A side of the main body 4.

A phosphor 22 is bonded to the main body 4 so as to cover the opening 4A. The phosphor 22 is formed in a flat plate shape, and is bonded to the upper surface 4b of the main body 4 with an adhesive or the like. The phosphor 22 is composed of the single crystal phosphor according to the first embodiment, similarly to the phosphor 2 according to the second embodiment. Further, the phosphor 22 is larger than the light emitting element 10.

When the light emitting device 1B configured as described above is energized, the light emitting element 10 emits light, and blue light is emitted from the second main surface 11b toward the phosphor 22. The phosphor 22 absorbs the blue emitted light of the light emitting element 10 from the first surface 22a facing the exit surface of the light emitting element 10, and radiates yellow fluorescence from the second surface 22b to the outside.

In this way, a part of the blue light incident on the phosphor 22 is absorbed by the phosphor 22 and wavelength-converted, and is emitted as yellow light from the second surface 22b of the phosphor 22. Further, the remaining part of the blue light incident on the phosphor 22 is not absorbed by the phosphor 22 and is emitted from the second surface 22b of the phosphor 22. Since blue and yellow have a complementary color relationship, the light emitting device 1B emits white light, which is a mixture of blue light and yellow light.

In the present embodiment, since the light emitting element 10 and the phosphor 22 are separated from each other, a large phosphor 22 can be used as compared with the case where the phosphor is bonded to the emission surface of the light emitting element 10. The ease of assembling the light emitting device 1B is enhanced.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a cross-sectional view of the light emitting device 1C according to the fifth embodiment. As shown in FIG. 7, in the present embodiment, the positional relationship between the light emitting element, the substrate on which the light emitting element is mounted, and the phosphor is different from that in the fourth embodiment. Hereinafter, the components of the light emitting device 1C having the same functions and configurations as those of the second, third, or fourth embodiment are designated by common reference numerals and the description thereof will be omitted.

The light emitting device 1C according to the present embodiment covers the main body 5 made of white resin, the transparent substrate 6 held by the slit-shaped holding portion 51 formed in the main body 5, and the opening 5A of the main body 5. It has a phosphor 22 arranged in the transparent substrate 6, a light emitting element 10A mounted on a surface of the transparent substrate 6 opposite to the surface on the phosphor 22 side, and wiring portions 61 and 62 for energizing the light emitting element 10A. .. The phosphor 22 is composed of the single crystal phosphor according to the first embodiment, similarly to the phosphor 11 according to the second embodiment.

The main body 5 has a hemispherical concave portion formed in the center thereof, and the surface of the concave portion serves as a reflecting surface 50 that reflects the emitted light of the light emitting element 10A toward the phosphor 22 side.

The transparent substrate 6 is made of a translucent resin such as a silicone resin, an acrylic resin, or PET, or a translucent member made of a glassy substance, sapphire, ceramics, quartz, or the like, and is a light emitting element. It has translucency and insulation that allows the emitted light of 10A to pass through. Further, a part of the wiring portions 61 and 62 is joined to the transparent substrate 6. The p-side electrode and the n-side electrode of the light emitting element 10A are electrically connected to one end of the wiring portions 61 and 62, respectively, via the bonding wires 611 and 621. The other ends of the wiring portions 61 and 62 are pulled out to the outside of the main body 5.

When the light emitting device 1C configured as described above is energized, the light emitting element 10A emits light, and a part of the emitted light is transmitted through the transparent substrate 6 and incident on the first surface 22a of the phosphor 22. Further, the other part of the light emitting element 10A is reflected by the reflecting surface 50 of the main body 5, passes through the transparent substrate 6, and is incident on the first surface 22a of the phosphor 22.

A part of the light incident on the phosphor 22 is absorbed by the phosphor 22 to convert the wavelength, and the remaining part is not absorbed by the phosphor 22 and is emitted from the second surface 22b of the phosphor 22. .. As described above, the light emitting device 1C emits white light which is a mixture of the blue light emitted by the light emitting element 10A and the yellow light whose wavelength is converted by the phosphor 22.

According to the present embodiment, the light emitted from the light emitting element 10A to the side opposite to the phosphor 22 side is reflected by the reflecting surface 50, transmitted through the transparent substrate 6, and is incident on the phosphor 22. Therefore, the light emitting device 1C Light extraction efficiency is increased.

[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described with reference to FIG. FIG. 8A is a vertical cross-sectional view of the light emitting device 1D according to the sixth embodiment, and FIG. 8B is a vertical cross-sectional view of the light emitting element 7 constituting the light emitting device 1D. As shown in FIG. 8A, in the present embodiment, the configuration and arrangement of the light emitting elements are different from those in the fourth embodiment. Hereinafter, the components of the light emitting device 1D having the same functions and configurations as those of the second, third, or fourth embodiment are designated by common reference numerals and the description thereof will be omitted.

In the light emitting device 1D, the light emitting element 7 is arranged on the wiring portion 32 provided on the ceramic substrate 3. As shown in FIG. 8B, the light emitting element 7 includes a Ga ₂ O ₃ substrate 70, a buffer layer 71, a Si-doped n ⁺ -GaN layer 72, a Si-doped n-AlGaN layer 73, and an MQW (Multiple-Quantum). Well) layer 74, Mg-doped p-AlGaN layer 75, Mg-doped p ⁺ -GaN layer 76, and p electrode 77 are laminated in this order. Further, an n electrode 78 is provided on the surface of the Ga ₂ O _{3 substrate 70 opposite to the buffer layer 71.}

The Ga ₂ O ₃ substrate 70 is made of β-Ga ₂ O ₃ which is an n-type conductive type. The MQW layer 74 is a light emitting layer having an InGaN / GaN multiple quantum well structure. The p-electrode 77 is a transparent electrode made of ITO (Indium Tin Oxide) and is electrically connected to the wiring portion 32. The n electrode 78 is connected to the wiring portion 31 of the ceramic substrate 3 by the bonding wire 321. As the element substrate, SiC may be used instead of _{β-Ga 2} O _3.

When the light emitting element 7 configured as described above is energized, _{electrons pass through the n electrode 78, the Ga 2} O ₃ substrate 70, the buffer layer 71, the n ⁺ -GaN layer 72, and the n-AlGaN layer 73, and the electrons are transferred to the MQW layer 74. Also, holes are injected into the MQW layer 74 via the p electrode 77, the p ⁺ -GaN layer 76, and the p-AlGaN layer 75 to emit blue light. This blue-based emitted light _{passes through the Ga 2} O ₃ substrate 70 and the like, is emitted from the emitting surface 7a of the light emitting element 7, and is incident on the first surface 22a of the phosphor 22.

The phosphor 22 absorbs the bluish emission light of the light emitting element 10 from the first surface 22a facing the emission surface of the light emitting element 7, and radiates yellow fluorescence from the second surface 22b to the outside.

In this way, a part of the blue light incident on the phosphor 22 is absorbed by the phosphor 22 and wavelength-converted, and is emitted as yellow light from the second surface 22b of the phosphor 22. Further, the remaining part of the blue light incident on the phosphor 22 is not absorbed by the phosphor 22 and is emitted from the second surface 22b of the phosphor 22. Since blue and yellow have a complementary color relationship, the light emitting device 1D emits white light, which is a mixture of blue light and yellow light.

[7th Embodiment]
Next, a seventh embodiment of the present invention will be described with reference to FIG. FIG. 9 is a vertical cross-sectional view of the light emitting device 1E according to the seventh embodiment. As shown in FIG. 9, in the present embodiment, the state of the phosphor and its arrangement are different from those in the second embodiment. Hereinafter, the components of the light emitting device 1E having the same functions and configurations as those of the second embodiment are designated by common reference numerals and the description thereof will be omitted.

As shown in FIG. 9, the light emitting device 1E seals a light emitting element 10 which is a light emitting element such as an LED, a ceramic substrate 3 which supports the light emitting element 10, a main body 4 made of white resin, and a light emitting element 10. It has a transparent member 101 to be formed.

Granular phosphors 102 are dispersed in the transparent member 101. The phosphor 102 comprises the single crystal phosphor of the first embodiment, and is obtained, for example, by pulverizing the single crystal phosphor ingot 92 produced in the first embodiment.

The transparent member 101 is, for example, a transparent resin such as a silicone resin or an epoxy resin, or a transparent inorganic material such as glass.

The phosphor 102 dispersed in the transparent member 101 absorbs a part of the bluish light emitted from the light emitting element 10, and emits yellowish fluorescence having an emission peak at a wavelength of 514 to 546 nm, for example. The bluish light that was not absorbed by the phosphor 102 and the yellowish fluorescence emitted from the phosphor 102 are mixed, and white light is emitted from the light emitting device 1E.

The transparent member 101 and the phosphor 102 of the present embodiment may be applied to other embodiments. That is, the transparent member 101 and the phosphor 102 of the present embodiment may be used in place of the transparent resin 8 and the phosphor 21 of the third embodiment.

[Eighth Embodiment]
Next, an eighth embodiment of the present invention will be described with reference to FIG. FIG. 10A is a vertical cross-sectional view of the light emitting device 1F according to the eighth embodiment, and FIG. 10B is a vertical cross-sectional view of the light emitting element 10 constituting the light emitting device 1F and its peripheral portion. be. As shown in FIG. 10, in the present embodiment, the state of the phosphor and its arrangement are different from those in the second embodiment. Hereinafter, the components of the light emitting device 1F having the same functions and configurations as those of the second embodiment are designated by common reference numerals and the description thereof will be omitted.

As shown in FIG. 10A, the light emitting device 1F includes a light emitting element 10 which is a light emitting element such as an LED, a transparent member 103 provided so as to cover the light emitting surface of the light emitting element 10, and the light emitting element 10. It has a ceramic substrate 3 to support, a main body 4 made of white resin, and a transparent resin 8 for sealing the light emitting element 10 and the transparent member 103.

Particulate phosphors 104 are dispersed in the transparent member 103. The phosphor 104 comprises the single crystal phosphor of the first embodiment, and is obtained, for example, by pulverizing the single crystal phosphor ingot 92 produced in the first embodiment.

The transparent member 103 is, for example, a transparent resin such as a silicone resin or an epoxy resin, or a transparent inorganic material such as glass. The transparent member 103 has, for example, the same shape and size as the phosphor 2 of the second embodiment.

The phosphor 104 dispersed in the transparent member 103 absorbs a part of the bluish light emitted from the light emitting element 10, and emits yellowish fluorescence having an emission peak at a wavelength of 514 to 546 nm, for example. The bluish light that was not absorbed by the phosphor 104 and the yellowish fluorescence emitted from the phosphor 104 are mixed, and white light is emitted from the light emitting device 1F.

The transparent member 103 and the phosphor 104 of the present embodiment may be applied to other embodiments. For example, the transparent member 103 and the phosphor 104 of the present embodiment may be used in place of the phosphor 21 of the third embodiment or the phosphor 22 of the fourth, fifth, and sixth embodiments.

[9th Embodiment]
Next, a ninth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a vertical cross-sectional view of the light emitting device 1G according to the ninth embodiment. As shown in FIG. 11, in the present embodiment, the shape of the transparent member including the particulate single crystal phosphor is different from that in the eighth embodiment. Hereinafter, the components of the light emitting device 1G having the same functions and configurations as those of the eighth embodiment are designated by common reference numerals and the description thereof will be omitted.

As shown in FIG. 11, the light emitting device 1G covers the light emitting element 10 which is a light emitting element such as an LED, the ceramic substrate 3 which supports the light emitting element 10, the surface of the light emitting element 10, and the upper surface of the ceramic substrate 3. It has a transparent member 103 provided.

Particulate phosphors 104 are dispersed in the transparent member 103. The phosphor 104 comprises the single crystal phosphor of the first embodiment, and is obtained, for example, by pulverizing the single crystal phosphor ingot 92 produced in the first embodiment.

The transparent member 103 is, for example, a transparent resin such as a silicone resin or an epoxy resin, or a transparent inorganic material such as glass. The transparent member 103 of the present embodiment may be formed not only on the surface of the light emitting element 10 but also on the ceramic substrate 3 in the manufacturing process using the coating method or the like, but on the ceramic substrate 3 It does not have to be formed.

The phosphor 104 dispersed in the transparent member 103 absorbs a part of the bluish light emitted from the light emitting element 10, and emits yellowish fluorescence having an emission peak at a wavelength of 514 to 546 nm, for example. The bluish light that was not absorbed by the phosphor 104 and the yellowish fluorescence emitted from the phosphor 104 are mixed, and white light is emitted from the light emitting device 1G.

(Effect of embodiment)
According to the above embodiment, it is possible to obtain a phosphor having excellent quantum efficiency and temperature quenching characteristics. Further, by using a phosphor having excellent quantum efficiency and temperature quenching characteristics, it is possible to obtain a light emitting device having excellent features such as high brightness, high output, and long life.

As is clear from the above description, the present invention is not limited to the above-described embodiments and illustrated examples, and various design changes can be made within the scope described in each claim. For example, an example of a method for producing a fluorescent substance has been shown, but the fluorescent substance of the present invention is not limited to the one produced by this example. Further, the light emitting element and the phosphor may be sealed with a so-called bullet-shaped resin. Further, one light emitting device may have a plurality of light emitting elements. Furthermore, a plurality of singles such as a single crystal phosphor that emits yellowish light by using the light of a light emitting element that emits blueish light as excitation light and a single crystal phosphor that emits light having a color tone different from that of the single crystal phosphor. A light emitting device may be configured by combining phosphors made of a single crystal of the above.

Further, the above-described embodiment has an energy saving effect because it is a light emitting device such as an LED light emitting device capable of realizing high energy efficiency and energy saving, or a single crystal phosphor used in the light emitting device.

1, 1A, 1B, 1C, 1D, 1E, 1F, 1G ... light emitting device, 2, 21, 22, 102, 104 ... phosphor, 3 ... ceramic substrate, 2a, 21a, 22a ... first surface, 2b, 21b, 22b ... Second surface, 4, 5 ... Main body, 51 ... Holding part, 4A, 5A ... Opening, 4b ... Top surface, 6 ... Transparent substrate, 10, 10A, 7 ... Light emitting element, 11 ... Element substrate, 11a ... 1st main surface, 11b ... 2nd main surface, 12 ... n-type GaN layer, 13 ... light emitting layer, 14 ... p-type GaN layer, 15A ... n-side electrode, 15B ... p-side electrode, 16 ... bump , 31, 32, 61, 62 ... Wiring part, 311, 321, 611, 621 ... Bonding wire, 40, 50 ... Reflective surface, 140 ... Transparent electrode, 140b ... Surface, 70 ... Ga ₂ O ₃ substrate, 71 ... Buffer Layer, 72 ... n ⁺ -GaN layer, 73 ... n-AlGaN layer, 74 ... MQW layer, 75 ... p-AlGaN layer, 76 ... p ⁺ -GaN layer, 77 ... p electrode, 78 ... n electrode, 80 ... crystal Growing device, 81 ... Rutsubo, 82 ... Cylindrical container, 83 ... High frequency coil, 90 ... Melt, 91 ... Seed crystal, 92 ... Single crystal phosphor ingot, 101, 103 ... Transparent member

Claims (5)

A laser element that emits laser light having a peak light intensity at a wavelength of 380 to 490 nm,
Includes a flat plate-shaped single crystal phosphor that is arranged apart from the laser element, absorbs the laser light, and emits wavelength-converted light having a wavelength peak at a wavelength of 514 to 544 nm at 25 ° C. ,
The single crystal phosphor, the composition formula _{(Y 1-x-y-} z Lu x Gd y Ce z) 3 + a Al 5-a O 12 (0 ≦ x ≦ 0.9994,0 ≦ y ≦ 0.0302,0 It has a composition represented by 0006 ≦ z ≦ 0.0067, −0.010 ≦ a ≦ 0.251).
When the peak wavelength of the laser light is 450 nm, the value of the ratio of the internal quantum efficiency at 300 ° C. to the internal quantum efficiency at 25 ° C. is 0.82 to 1.00.
Light emitting device. Used for any one of laser projectors and laser headlights,
The light emitting device according to claim 1. In the above composition, x + z = 1 and y = 0.
The light emitting device according to claim 1 or 2. The flat plate-shaped single crystal phosphor is coupled to the upper surface of the main body surrounding the laser element, which has an opening located on the laser element.
The light emitting device according to any one of claims 1 to 3. It said plate-shaped single crystal phosphor has a light incident surface of larger area than the light emitting surface of the laser element,
The light emitting device according to any one of claims 1 to 4.

Images