KR100833834B1 - Phosphor and light-emitting diode - Google Patents

Abstract

Provided is a phosphor that is excited by a long wavelength light source in an ultraviolet region or a blue-violet visible region, and mainly emits light in a violet-blue-yellow-red visible region. In addition, a low cost light emitting diode which is easy to mount and has excellent color rendering properties, and provides a light emitting diode having a small change in color tone according to an emission angle. The SiC fluorescent substance of the present invention is excited by an external light source, emits light, and is doped with one or more elements of B and Al and N.

Long wavelength light source, light emitting diode, SiC-made phosphor

Description

Phosphor and Light Emitting Diodes {PHOSPHOR AND LIGHT-EMITTING DIODE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a SiC phosphor, a method for producing the same, and a semiconductor substrate and powder made of such a phosphor, which are excited by electromagnetic waves such as electron beams, X-rays, ultraviolet rays or blue-violet visible light. Moreover, this invention relates to the light emitting diode provided with the group III nitride semiconductor which is expected to spread in the future as a new solid-state lighting device.

The development of the PDP panel which excites fluorescent substance and emits light using the vacuum ultraviolet-ray radiated by a rare gas discharge is active. The PDP panel is formed of a plurality of display cells arranged in a matrix, and discharge electrodes are formed in each display cell. In addition, phosphors are applied therein, and rare gases such as He-Xe or Ne-Xe are sealed. When a voltage is applied to the discharge electrode, vacuum ultraviolet rays are radiated to excite the phosphor, thereby emitting visible light.

In the case of the fluorescent lamp, when the discharge is started in the discharge tube in which the mixed gas of mercury and argon gas is enclosed, electrons in the discharge space are accelerated by the electric field and run toward the anode. During this period, electrons excite mercury atoms in the fluorescent lamp tube, and emit visible light by ultraviolet rays having a wavelength of 253.7 nm emitted from the excited mercury atoms.

Phosphors excited by ultraviolet rays to emit light (hereinafter referred to as "ultraviolet excitation phosphors") have been widely used for decoration by fluorescent lamps, high pressure mercury lamps, fluorescent wall materials and fluorescent tiles used indoors and outdoors, and the like. Fluorescent wall materials or tiles are excited by long-wavelength ultraviolet rays of around 365 nm, especially among ultraviolet rays, and emit light brightly in various colors.

In addition, devices that are excited by light emitted from a semiconductor are known. In this device, the light from the semiconductor is as long as possible and the load on the semiconductor is reduced. Therefore, 360 nm or more is preferable, as for the wavelength of an excitation light, 380 nm or more is more preferable, and 400 nm or more is especially preferable.

Conventionally, examples of phosphors excited by long-wavelength ultraviolet rays include Eu-activated alkaline earth halo phosphate phosphors emitting blue light, Eu-activated alkaline earth aluminate phosphors, Eu-activated LnO phosphors, and the like. In addition, there are green light emitting Zn ₂ GeO ₄ : Mn phosphors, and yellow light emitting YAG: Ce (cerium-added yttrium aluminum garnet) phosphors, and red light emitting Y ₂ O ₂ S: Eu phosphors, YVO ₄ : Eu Phosphors and the like have been put to practical use.

However, with the diversification and high functionality of displays, there is a demand for multicoloring and high luminance of emission colors, improvement of durability, and improvement of weather resistance. In addition, studies on phosphors using II-VI semiconductors such as ZnSe and ZnO have been actively conducted (see Japanese Patent Laid-Open No. 2001-228809 (Patent Document 1)).

On the other hand, a phosphor that adds rare earth elements such as Yb, Er, etc. using SiC as a base material and emits infrared light of 900 nm or more by excitation of the rare earth element itself is known (Japanese Patent Laid-Open No. H10-270807 (Patent Document) 2)). Although the base material is SiC, this phosphor mainly focuses on light emission of the rare earth element, and uses the same mechanism as the light emission by the addition of the rare earth element whose oxide is the base material. SiC crystals can be produced by an improved Rayleigh method in which a SiC single crystal is used as a seed crystal to perform sublimation recrystallization (YM Tairov and VF Tsvctkov, Journal of Crystal Growth, (1981) vol. 52 pp. 146-150 (nonpatent literature 1)).

In recent years, the crystal growth method of nitride semiconductors has advanced rapidly, and high-brightness blue and green light emitting diodes using nitride semiconductors have been put into practical use. By combining the conventional red light emitting diodes with these blue and green light emitting diodes, all three primary colors of light are provided, and a full-color display device can be realized. That is, when all three primary colors of light are mixed, white light can also be obtained, and the application to the device for white illumination is also possible.

Several configurations are proposed as a white light source using a light emitting diode, and some have been put into practical use. 9 shows an example of a white light source using a light emitting diode. As shown in FIG. 9, the white light source uses a red light emitting diode 911, a green light emitting diode 912, and three primary color light emitting diodes of the blue light emitting diode 913 as a metal layer of the conductive heat sink 902. And formed on the stem 905 by the epoxy resin 908.

In this white light source, by connecting the lead wires connected to the respective light emitting diodes to individual terminals to independently control the current flowing through them, it is possible to display not only white but also full color, and the energy conversion efficiency is high. On the other hand, since the device and the driving circuit are complicated and the cost becomes expensive, it is not suitable as a simple lighting device.

Another example of the white light source using a light emitting diode is shown in FIG. As shown in FIG. 10, this white light source forms the blue light emitting diode 101 on the metal layer 103 of the conductive heat sink 102, and is the yellow fluorescent substance which consists of a YAG system material on the blue light emitting diode 101. FIG. Layer 104 is formed and secured on stem 105 by epoxy resin 108.

In this white light source, part of the light having a peak wavelength of about 450 nm emitted from the blue light emitting diode 101 is absorbed by the YAG-based yellow phosphor layer 104, and converted into yellow fluorescence near the wavelength of 570 nm. For this reason, both the blue light which permeate | transmitted the YAG system yellow fluorescent substance layer 104, and the yellow light which light-emits the YAG system yellow phosphor layer 104 are emitted to the exterior of an element. Since yellow has a complementary color relationship with blue, two types of light, yellow and blue, are mixed to obtain white light.

Since the white light source shown in FIG. 10 is comprised by the single light emitting diode 101, it can manufacture at comparatively low cost. In addition, the highest luminous efficiency is realized at present, and at the research level, it is realized that the luminance efficiency is about 701 m / W, which is almost equivalent to a conventional fluorescent lamp.

Patent Document 1: Japanese Patent Application Laid-Open No. 2001-228809

Patent Document 2: Japanese Patent Application Laid-open No. Hei 10-270807

Non-Patent Document 1: Y. M. Tairov and V. F. Tsvctkov, Journal of Crystal Growth, (1981) vol. 52 pp. 146-150

Disclosure of the Invention

Problems to be Solved by the Invention

In the conventional fluorescent substance excited by a long wavelength light source and using an oxide as a base material, the light emission efficiency of fluorescence worsens, so that the light emission rate becomes long wavelength, and especially the red light emission efficiency is bad. Since an oxide generally has a very wide band gap, it is impossible to use excitation of the oxide itself when it is excited by a long wavelength light source. Therefore, the excitation of the rare earth element itself is used, but the luminous efficiency of the fluorescence when the material containing the rare earth element is excited at a long wavelength is very low, and the luminous efficiency is not improved.

Since phosphors using group II to VI semiconductors are easy to form mixed crystals or solid solutions, methods such as band engineering can be used, and the luminous efficiency is also very high. However, since Group II and Group VI also have high electronegativity, the ionic bondability of the Group II to VI semiconductor crystals becomes high, and it is easy to cause a change over time.

The method of adding a rare earth element to SiC and utilizing the light emission of infrared light by excitation of the rare earth element has a very small lattice constant of SiC, whereas the rare earth element has a large atomic radius. Crystallinity is significantly worsened. Therefore, the addition amount of the rare earth element is limited, and it is impossible to increase the luminescence intensity.

In addition, the light emission by the donor acceptor pair which adds N and B to SiC simultaneously, makes N a donor, and functions B as an acceptor has a wavelength of 650 nm. Although it has a peak in the vicinity, it is impossible to use it as a phosphor because the emission intensity is very small.

On the other hand, with respect to the white light source using the light emitting diode, for example, in the example shown in Fig. 9, since the driving circuit and the device are complicated, the mounting is difficult, the yield is low, and the color deviation varies depending on the emission angle of the light. There are many challenges to solve.

In addition, in the example shown in FIG. 10, a part of blue light emitted from the blue light emitting diode 101 is converted into yellow light by exciting the yellow phosphor layer 104, and blue light and yellow are emitted to the outside together to obtain white light. . In this case, the color tone changes unless the intensity ratio of blue light and yellow light is appropriately set. Therefore, it is necessary to appropriately and uniformly adjust the film thickness and phosphor concentration of the yellow phosphor layer 104 formed on the blue light emitting diode 101. For this reason, the technique which mixes yellow fluorescent substance powder uniformly in resin binder and apply | coats with uniform film thickness is needed.

In addition, even if the phosphor layer 104 is uniform, the light emitted from the blue light emitting diode 101 has a different path length through the phosphor layer depending on the emission angle. For this reason, the change of white color tone cannot be avoided depending on the emission angle. In addition, in the combination of the blue light emitting diode 101 and the yellow phosphor layer 104 as shown in FIG. 10, since there are very few red components, the color rendering property which is important as an illumination light source deteriorates, and red reproducibility is low. There is also a challenge.

An object of the present invention is to provide a phosphor which is excited by a long wavelength light source in an ultraviolet region or a blue-violet visible region and mainly emits light in a violet-blue-yellow-red visible region. Another object of the present invention is to provide a phosphor that efficiently emits fluorescence having good characteristics by primary light from a light source such as a mercury discharge tube, a high-pressure mercury lamp, a laser emitting diode (LED), a vacuum ultraviolet ray or an electron beam by discharge of a PDP panel, and the like.

In addition, another object of the present invention is to provide a low cost light emitting diode which is easy to mount and has excellent color rendering properties. Moreover, it is providing the light emitting diode with little change of the color tone according to a radiation angle.

Means to solve the problem

The SiC fluorescent substance of the present invention is excited by an external light source, emits light, and is doped with one or more elements of B and Al and N. In such a phosphor, an embodiment in which both the doping concentration by at least one element of B and Al and the doping concentration by N are 10 ¹⁵ / cm 3 to 10 ²⁰ / cm 3 is preferable, and 10 ¹⁶ / cm 3 to 10 ²⁰ / The aspect which is cm <3> is more preferable.

The SiC fluorescent substance of the present invention includes one that emits fluorescence having a wavelength of 500 nm to 750 nm and has a peak wavelength at 500 nm to 650 nm. Such SiC is doped with N and B, and the concentration of either N or B is 10 ¹⁵ / cm 3 to 10 ¹⁸ / cm 3, and the other concentration is preferably 10 ¹⁶ / cm 3 to 10 ¹⁹ / cm 3.

Moreover, the SiC fluorescent substance of this invention includes the thing which fluoresces with a wavelength of 400 nm-750 nm, and has a peak wavelength in 400 nm-550 nm. Such SiC is doped with N and Al, and the concentration of either N or Al is 10 ¹⁵ / cm 3 to 10 ¹⁸ / cm 3, and the other concentration is preferably 10 ¹⁶ / cm 3 to 10 ¹⁹ / cm 3.

The method for producing a SiC phosphor of the present invention is excited by an external light source, emits a fluorescence having a wavelength of 500 nm to 750 nm, has a peak wavelength at 500 nm to 650 nm, and is doped with N and B, and N Or a process for producing a SiC-based phosphor having a concentration of either 10 ¹⁵ / cm 3 to 10 ¹⁸ / cm 3 and another concentration of 10 ¹⁶ / cm 3 to 10 ¹⁹ / cm 3, according to one aspect of the present invention. ₆ , B ₄ C, TaB ₂ , NbB ₂ , ZrB ₂ , HfB ₂ , BN, or B-containing carbon, characterized by forming a SiC crystal by a sublimation recrystallization method.

Further, under a, according to a separate aspect of the invention, B group, LaB _6, B ₄ C, TaB _2, NbB _2, ZrB _2, HfB ₂ or BN to B with circles, and a vacuum or an inert gas atmosphere, 1500 ℃ In the above, it is characterized by thermally diffusing with SiC.

The semiconductor substrate of the present invention is a phosphor which is excited by an external light source and emits light, and is composed of at least one element of B and Al, and a 6H type SiC single crystal phosphor doped with N. Such semiconductor substrates include those consisting of 6H-type SiC single crystal phosphors doped with N and B, emitting fluorescence with a wavelength of 500 nm to 750 nm, and having a peak wavelength at 500 nm to 650 nm. Moreover, the semiconductor substrate which consists of 6H type | mold SiC single crystal fluorescent substance doped with N and Al, fluorescing with a wavelength of 400 nm-750 nm, and having a peak wavelength in 400 nm-550 nm is contained.

The manufacturing method of the board | substrate for semiconductors of this invention is excited by an external light source, emits fluorescence with a wavelength of 500 nm-750 nm, has a peak wavelength at 500 nm-650 nm, is doped with N and B, N Or a substrate manufacturing method of a 6H-type SiC single crystal phosphor having a concentration of either 10 ¹⁵ / cm 3 to 10 ¹⁸ / cm 3 and a concentration of 10 ¹⁶ / cm 3 to 10 ¹⁹ / cm 3 in B; according to the aspect, B group, LaB _6, B ₄ C, TaB _2, NbB _2, ZrB _2, HfB _2, or in the BN under the B source, and a vacuum or an inert gas atmosphere, heat to above 1500 ℃, SiC And a step of diffusing and a step of removing the surface layer.

According to another aspect of the present invention, the atmosphere gas at the time of crystal growth contains 1% to 30% of N ₂ gas by gas partial pressure, and the raw material SiC contains 0.05 mol% to 15 mol% of B source. SiC crystal | crystallization is formed by the sublimation recrystallization method characterized by the above-mentioned.

The semiconductor powder of the present invention is excited by an external light source, emits fluorescence having a wavelength of 500 nm to 750 nm, and consists of a 6H type SiC single crystal phosphor having a peak wavelength at 500 nm to 650 nm, and has a particle size of 2 µm to It is 10 micrometers, It is characterized by the center particle diameters 3 micrometers-6 micrometers.

According to one aspect of the present invention, a light emitting diode according to the present invention is a semiconductor substrate comprising at least one element of B and Al, a 6H type SiC single crystal phosphor doped with N, and a light emitting layer consisting of a nitride semiconductor on the substrate. An element is provided.

According to another aspect of the present invention, there is provided one or two or more layers composed of at least one element of B and Al and a 6H type SiC single crystal phosphor doped with N on a SiC semiconductor substrate. A light emitting element made of a nitride semiconductor is provided on a type SiC single crystal phosphor layer. In such a light emitting diode, it is preferable that the light emission wavelength of the light emitting element which consists of nitride semiconductors is 408 nm or less.

In such a light emitting diode, it is preferable that in the 6H type SiC single crystal phosphor, both the doping concentration by one or more elements of B and Al and the doping concentration by N are 10 ¹⁶ / cm 3 to 10 ¹⁹ / cm 3, 10 ¹⁷ / ㎤~10 is desirable than the ¹⁹ / ㎤.

Effects of the Invention

According to the present invention, it is possible to control the concentration of impurities in SiC and to be excited by long-wavelength light or electron beam in the ultraviolet region or the blue-violet visible region, and the like to efficiently emit light in the violet-blue-yellow-red visible region. Can be provided.

Further, according to the present invention, since the color rendering is easy to adjust and is made of one light emitting diode, it is possible to provide a white light source with simple mounting at low cost. Since this white light source produces white light internally, the change of the color tone with a radiation angle is negligible, and it is excellent in luminous efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows an example of the single crystal growth apparatus used for the manufacturing method of the SiC fluorescent substance of this invention.

It is a schematic diagram explaining the principle of the improved Rayleigh method used in the manufacturing method of this invention.

3 is a view showing the light emission characteristics of the SiC phosphor of the present invention.

4 is a schematic view showing the structure of the light emitting diode of the present invention.

5 is a schematic diagram showing a state in which the light emitting diode of the present invention is mounted.

Fig. 6 shows the light emission characteristics of the SiC fluorescent substance of the present invention.

7 is a schematic view showing the structure of the light emitting diode of the present invention.

8 is a schematic diagram showing a state in which the light emitting diode of the present invention is mounted.

9 is a schematic diagram showing a state in which a conventional light emitting diode is mounted.

10 is a schematic diagram showing a state in which a conventional light emitting diode is mounted.

(Explanation of the sign)

1: substrate 2: raw material

3: crucible 4: lid

5: quartz tube 6: support rod

7: heat shield 8: work coil

9: Introduction tube 401: SiC substrate

402: first impurity-added SiC layer

403: second impurity-added SiC layer

404: AlGaN buffer layer 405: n-GaN first contact layer

406: n-AlGaN first cladding layer

407: GaInN / GaN multi quantum well active layer

408: p-AlGaN electron block layer 409: p-AlGaN second clad layer

410 p-GaN second contact layer 411 p electrode

412: n electrode

Implement the invention  Best form for

(SiC phosphor)

The SiC fluorescent substance of the present invention is doped with at least one element of B and Al and N. Such SiC phosphor is excited by an external light source such as an ultraviolet ray or a long wavelength light source in a blue-violet visible region or an electron beam, and emits light mainly in a violet-blue-yellow-red visible region.

For example, the SiC fluorescent material doped with B and N is excited by an external light source, emits fluorescence with a wavelength of 500 nm to 750 nm, and has a peak wavelength at 500 nm to 650 nm. In addition, the SiC fluorescent material doped with Al and N emits fluorescence with a wavelength of 400 nm to 750 nm, and has a peak wavelength at 400 nm to 550 nm. The SiC phosphor doped with Al, B, and N emits 400 nm to 750 nm of fluorescence, and has a peak wavelength at 400 nm to 650 nm.

In order to increase the luminescence efficiency of fluorescence, a state density of an impurity level sufficient to accept an electron-hole pair relaxed from the band end of SiC is required. In this respect, an embodiment in which the impurity concentration by at least one element of B and Al and the impurity concentration by N are both 10 ¹⁵ / cm 3 or more is preferable, and an embodiment of 10 ¹⁶ / cm 3 or more is more preferable, and 10 ¹⁸ / cm 3 It is especially preferable if it is above. On the other hand, when the impurity concentration is too high, the luminous efficiency of fluorescence tends to be low, so 10 ²⁰ / cm 3 or less is preferable.

In the case of doping with N and B, an embodiment in which the concentration of either N or B is 10 ¹⁵ / cm 3 to 10 ¹⁸ / cm 3 and the other concentration is 10 ¹⁶ / cm 3 to 10 ¹⁹ / cm 3 is preferable. . On the other hand, even when doping with N and Al, an embodiment in which the concentration of either N or Al is 10 ¹⁵ / cm 3 to 10 ¹⁸ / cm 3 and the other concentration is 10 ¹⁶ / cm 3 to 10 ¹⁹ / cm 3 is preferable. . In this specification, light emission shows the light emission at the time of making incident light (purple) of wavelength 404.7 nm into the numerical value measured by PHOTOLUMINOR-S by Horiba Corporation. In addition, the density | concentration of N, Al, or B is shown by the numerical value measured by SIMS (secondary ion mass spectrometer).

The external light source that can be used in the present invention is a light source that emits visible light such as blue-purple, ultraviolet light, X-rays or electron beams, but in particular, visible light such as blue-purple light having a wavelength of 100 nm to 500 nm and ultraviolet light It is preferable because there is a tendency to emit fluorescence having a large emission intensity. SiC semiconductors have a wide metal band width of about 3 eV and can make various ranks in the band by addition of impurities. Particularly, in 6H type SiC, when the band end wavelength is 408 nm, and the SiC band gap is used, excitation can be performed by a wavelength shorter than the wavelength of this band end, so that light having a relatively long wavelength can be used as the excitation source. have.

As a result of intensive studies, the present inventors doped N as a donor under conditions in which 6H-type poly-type SiC crystals sufficiently activated B to be an acceptor, and the concentration of the DA pair was 10 ¹⁵ / cm 3 to 10 ¹⁸ /. When it was cm <3>, it discovered that light emission intensity became high enough. The lower limit is more preferably 5 × 10 ¹⁵ / cm 3 or more, more preferably 10 ¹⁶ / cm 3 or more, and even more preferably 2 × 10 ¹⁶ / cm 3 or more, since the concentration of the DA pair is improved. On the other hand, 8 * 10 <^17> / cm <3> or less is more preferable at the point which raises light emission intensity similarly.

If in this range of concentration of the DA pair, either the concentration of the B or N is, in the sense that a good luminescence is obtained, the lower limit is 10 ¹⁶ / ㎤ over more preferably, 5 × 10 ¹⁶ / ㎤ or more is particularly preferred Do. On the other hand, the upper limit is more preferably 10 ¹⁹ / cm 3 or less, and particularly preferably 5 × 10 ¹⁸ / cm 3 or less, in that favorable light emission can be obtained.

The light emission of the phosphor made of SiC in which the concentrations of B and N are within this range shows a broad spectrum as illustrated in FIG. 3 and emits good red-yellow fluorescence. That is, the SiC fluorescent substance of the present invention emits fluorescence with a wavelength of 500 nm to 750 nm, and has a high luminescence intensity at a wavelength of 550 nm to 680 nm. Moreover, it is preferable to have a peak wavelength in 500 nm-650 nm, and to have a peak wavelength in 570 nm-630 nm. The emission wavelength and its relative intensity differ depending on the doping concentrations of B and N in SiC.

In addition, the present inventors have found a concentration condition in which the luminescence intensity also becomes strong for DA pairs of Al and N. That is, a 6H type poly-type SiC crystal is doped with N as a donor under conditions that sufficiently activate Al as an acceptor, and the emission intensity is sufficient when the concentration of the DA pair is 10 ¹⁵ / cm 3 to 10 ¹⁸ / cm 3. Found higher. The concentration of DA pair, in that the emission intensity is improved, the lower limit is 5 × 10 ¹⁵ / ㎤ and over are more preferable, 10 ¹⁶ / ㎤ and above are particularly preferred and 2 is more preferable × 10 ¹⁶ / ㎤ above. On the other hand, as for an upper limit, 8 * 10 <^17> / cm <3> or less is more preferable at the point which raises luminescence intensity similarly.

When the concentration of the DA pair is within this range, the concentration of either Al or N is preferably at least 10 ¹⁶ / cm 3, and more preferably at least 10 ¹⁶ / cm 3, particularly preferably at least 10 ¹⁶ / cm 3. . On the other hand, the upper limit is more preferably 10 ¹⁹ / cm 3 or less, and particularly preferably 5 × 10 ¹⁸ / cm 3 or less, in that favorable light emission can be obtained.

The light emission of the SiC fluorescent substance in which the concentrations of Al and N are within this range shows a broad spectrum as illustrated in FIG. 6 and emits blue broad fluorescence. That is, the SiC fluorescent substance of the present invention emits fluorescence having a wavelength of 400 nm to 750 nm, and has a high luminescence intensity at a wavelength of 400 nm to 550 nm. Moreover, it is preferable to have a peak wavelength in 400 nm-550 nm, and to have a peak wavelength in 410 nm-470 nm. The emission wavelength and its relative intensity differ depending on the doping concentrations of Al and N in SiC.

(Method for Producing SiC Phosphor)

In the method for producing a SiC-based phosphor of the present invention, LaB ₆ , B ₄ C, TaB ₂ , NbB ₂ , ZrB ₂ , HfB ₂ , BN, or B-containing carbon is used as a B source by a sublimation recrystallization method. SiC crystals are formed. By this method, SiC is doped with N and B, the concentration of either N or B is 10 ¹⁵ / cm 3 to 10 ¹⁸ / cm 3, and the other concentration is 10 ¹⁶ / cm 3 to 10 ¹⁹ / cm 3. The doping concentration can be adjusted so that it can be excited by an external light source, the fluorescent substance of wavelength 500nm -750nm can be emitted, and the SiC fluorescent substance which has a peak wavelength in 500nm-650nm can be manufactured.

Such concentration adjustment can be achieved by actively adding N and B during crystal growth of SiC. SiC crystals can be produced by the improved Rayleigh method. Since this method uses seed crystals, it is possible to control the nucleation process of the crystals and to control the growth of the crystals by inert gas at about 100 Pa to 15 kPa, thereby growing the crystals. Speed and the like can be controlled with good reproducibility.

In the improved Rayleigh method, as shown in FIG. 2, first, a SiC single crystal serving as the seed crystal 21 is attached to the lid 24 of the crucible 23, and the SiC crystal powder, which is the raw material 22 of the sublimation recrystallization, is graphite. It is added to the crucible 23 and heated to 133 Pa-13.3 kPa and 2000 degreeC-2400 degreeC in inert gas atmosphere, such as Ar. At the time of heating, as shown by the arrow of FIG. 2, the temperature gradient is set so that SiC crystalline powder which is the raw material 22 will be made into high temperature H a little, and the seed crystal 21 will be a little low temperature L. . After sublimation, the raw material 22 is diffused in the direction of the seed crystal 21 and transported by the concentration gradient formed based on the temperature gradient. The growth of the SiC single crystal 20 is realized by recrystallization of the source gas arriving at the seed crystal 21 on the seed crystal.

The doping concentration of the SiC crystal can be controlled by adding an impurity gas into the atmosphere gas at the time of crystal growth and adding an impurity element or a compound thereof to the raw material powder. In particular, sublimation recrystallization by adding N ₂ gas is preferred in that the control of an N concentration of 5 × 10 ¹⁸ / cm 3 or more is easy. In addition, in order to stabilize density control of DA pairs of 1 × 10 ¹⁸ / cm 3 or less, improve reproducibility, and improve luminescence intensity, N is set to be actively added, and B is stably added in crystals. It is desirable to set the conditions.

For example, a SiC fluorescent substance having an N concentration of 10 ¹⁵ / cm 3 -10 ¹⁸ / cm 3 can be produced by setting the partial pressure of the N ₂ gas in the atmosphere gas at the time of crystal growth. In this case, the viewpoint of increasing the light intensity of the fluorescent light, the partial pressure of N ₂ gas is 5-10% is preferred.

Although the addition of B has a method of mixing single element B (metal boron) into a raw material, this method has a drawback that the concentration of B is high at the beginning of crystallization, the concentration of B is lowered in the second half of crystallization, and the concentration of B is not stable. There is this. For this reason, when M is used as a metal containing at least one of Ta, Nb, Zr, or Hf, and added as a B compound represented by MB ₂ , the change in B concentration during crystal growth can be reduced. Do. Further, even if added as LaB ₆ or B ₄ C is preferred because it similarly possible to suppress the change of the B concentration. By this method, it is possible to easily and reliably added to the B in the 10 ¹⁷ / ㎤~ 10 ¹⁸ / ㎤ versus concentration.

Since carbon easily impregnates B (metal boron) and gradually releases B even at a sublimation recrystallization temperature of 2000 ° C. or higher, the method of sublimation recrystallization using carbon containing B as a B source It is excellent as a method of forming the SiC crystal which added and B. By adding carbon impregnated with B element at a high temperature of 1500 ° C. or higher to the raw material in advance, it is possible to almost eliminate the change in the B concentration in the crystal.

In the raw material of SiC, powdery or solid BN is added, it is maintained at a relatively low temperature of about 2000 ° C, and sublimated and recrystallized, so that both N and B can be added to SiC simultaneously without adding N ₂ gas. In this case, since the amount of B added tends to decrease relatively, it is preferable to actively add B by using any one of the above methods. By the sublimation recrystallization method using the BN, the concentration of the DA pair of 1 × 10 ¹⁸ / ㎤~8 × to 10 ¹⁸ / ㎤ the SiC first phosphor can be obtained stably.

After the sublimation recrystallization, heat annealing at 1300 ° C or more for 1 hour or more is preferable in that the luminescence intensity of fluorescence can be enhanced. It is considered that the concentration of the DA pair is increased as a result of the heat treatment, as a result of B and N incorporated in the energy inert embodiment being fixed at the position of Si or C and being activated.

The amount of agent B, also as a raw material by a mixture such that the different, 0.05㏖% ~15㏖% with respect to the SiC powder in accordance with other conditions such as the type of the original B, 10 ¹⁶ / ㎤~10 a concentration of ¹⁹ / ㎤ B can be easily and stably added to the SiC crystals. In this case, when the formulation other than the original MB as B _2, BN or LaB _6, etc., groups B (metallic boron), and the amount in terms of the B contained in the circle B in amount. Since the compounding quantity of B source raises the luminescence intensity of fluorescence, 2.5 mol%-5 mol% are preferable with respect to SiC powder.

In another method for producing a SiC-based phosphor of the present invention, a single B, LaB ₆ , B ₄ C, TaB ₂ , NbB ₂ , ZrB ₂ , HfB _2, or BN is a B source, under vacuum or in an inert gas atmosphere, It is characterized by thermal diffusion with SiC above 1500 ° C. By this method, SiC is doped with N and B so that the concentration of either N or B is 10 ¹⁵ / cm 3-10 ¹⁸ / cm 3, and the other concentration is 10 ¹⁶ / cm 3 -10 ¹⁹ / cm 3. The doping concentration can be adjusted, is excited by an external light source, and emits light to emit fluorescence having a wavelength of 500 nm to 750 nm, thereby producing a SiC phosphor having a peak wavelength at 500 nm to 650 nm.

The concentration adjustment of B and N can also be achieved by controlling the conditions of thermal diffusion. SiC to conduct heat diffusion, for example, the N by the sublimation recrystallization method can be used by doping about 10 ¹⁷ / ㎤. In the thermal diffusion, when the B source is in direct contact with the SiC crystal, the B source and the SiC crystal may react to erode the SiC crystal. Therefore, the amount of the B source is separated from the SiC crystal by about 0.1 mm and thermally diffused. Pregnancy is preferred.

In thermal diffusion, an inert gas such as an Ar gas can be used, and heated to 1500 ° C. or higher, preferably 1700 ° C. to 2000 ° C., and maintained for 3 to 5 hours, whereby a B having a thickness of about 3 μm is formed on the surface of the SiC crystal. The diffusion layer by this is formed. For example, when irradiated with the output 30W and the ultraviolet-ray of wavelength 250nm, it fluoresces that can be seen visually.

Depending on the conditions of thermal diffusion, a diffusion layer in which B is present at a high concentration of 10 ¹⁹ / cm 3 or more may be formed on the surface of the SiC crystal. Since the region which emits strong fluorescence is 2 µm to 4 µm from the surface of the SiC crystal, it is preferable to remove the high concentration B layer on the surface by about 2 µm in thickness to increase the emission intensity. For example, after thermal diffusion, an acidic film is heated under an acidic atmosphere at 1000 ° C. or higher, preferably at 1200 ° C. to 1400 ° C. for 2 hours to 4 hours, and then chemically treated with, for example, fluoric acid or the like. It is preferable to remove the surface of the oxide film. In addition, the surface layer can be preferably removed by polishing or by reactive ion etching (RIE). In the same manner as in the case of sublimation recrystallization, heat annealing for 1 hour or more at 1300 ° C. or more after heat diffusion is preferable in that the luminescence intensity of fluorescence can be enhanced.

The above embodiment illustrates a method for producing a SiC phosphor having a concentration of N of 10 ¹⁵ / cm 3 to 10 ¹⁸ / cm 3 and a concentration of B of 10 ¹⁶ / cm 3 to 10 ¹⁹ / cm 3. However, the present invention has a remarkable effect in the SiC phosphor having a pair concentration of B and N of 10 ¹⁵ / cm 3 to 10 ¹⁸ / cm 3, and either of B or N having a concentration of 10 ¹⁶ / cm 3 to 10 ¹⁹ / cm 3. Since the concentration of N is 10 ¹⁶ / cm 3 to 10 ¹⁹ / cm 3, and the concentration of B is 10 ¹⁵ / cm 3 to 10 ¹⁸ / cm 3, the SiC phosphor and its manufacturing method are also included in the present invention.

(Substrate and Powder for Semiconductor)

The substrate and powder for semiconductors of the present invention are phosphors which are excited by an external light source and emit light, and are composed of at least one element of B and Al and a 6H type SiC single crystal phosphor doped with N.

For example, the semiconductor substrate and powder which consist of 6H type | mold SiC single crystal fluorescent substance doped with B and N are excited by an external light source, fluoresce with a wavelength of 500 nm-750 nm, and peak wavelength in 500 nm-650 nm. Has In addition, the semiconductor substrate and powder which consist of 6H type | mold SiC single crystal fluorescent substance doped with Al and N emit | emit fluorescence with a wavelength of 400 nm-750 nm, and have a peak wavelength in 400 nm-550 nm. Moreover, the semiconductor substrate and powder which consist of a 6H type | mold SiC single crystal fluorescent substance doped with Al, B, and N luminesce at 400 nm-750 nm, and have a peak wavelength in 400 nm-650 nm.

When the SiC fluorescent substance of the present invention is used for a substrate or powder used for a semiconductor such as a GaN-based compound semiconductor that emits light in a blue-ultraviolet light region, the resulting light-emitting device is obtained by primary light of blue-ultraviolet light from the semiconductor. Since the 6H type SiC single crystal phosphor is excited to emit secondary light in the purple-blue-yellow-red visible region, the mixed light of the direct light from the semiconductor and the secondary light from the SiC phosphor or mixed light of the secondary light By this, excellent white light can be obtained.

The semiconductor substrate and the powder composed of 6H type SiC single crystal phosphor doped with B and N have B element, LaB ₆ , B ₄ C, TaB ₂ , NbB ₂ , ZrB ₂ , HfB ₂ or BN as source B and under vacuum Or it can manufacture by the method provided with the process of thermally diffusing into SiC and the process of removing a surface layer in 1500 degreeC or more in inert gas atmosphere. As described above, the surface layer is removed by forming an oxide film in an oxidizing atmosphere of 1000 ° C. or higher, and removing the surface of the formed oxide film by fluoric acid or the like, or by polishing, or by reactive ion etching. The method of removal is preferred.

A semiconductor substrate, and a powder made of a 6H-type SiC single crystal phosphor doped with B and N, the atmosphere gas at the time of crystal growth, and the gas partial pressure of N ₂ containing gas of 1-30%, the raw material SiC 0.05㏖% It can also manufacture by the sublimation recrystallization method characterized by containing a -15 mol% B source. In such an aspect, it is preferable to perform a thermal annealing treatment at 1300 ° C or more after sublimation recrystallization or heat diffusion.

In a SiC powder containing N at a concentration of 10 ¹⁶ / cm 3 to 10 ¹⁷ / cm 3, MB ₂ , BN, B ₄ C or LaB ₆ or the like is encapsulated in a carbon capsule and mixed in a carbon crucible. Is heated to 1300 ° C to 2000 ° C under vacuum and held for 3 to 5 hours. Since the SiC powder obtained has a high concentration of B on the surface, the SiC powder is kept at 1000 ° C to 1400 ° C for 2 to 4 hours in an oxidizing atmosphere, and then chemically treated with, for example, fluoric acid or the like, and the surface By removing the oxide film, strong fluorescence can be observed.

When BN is used as the B source, predetermined doping is also possible by using a BN crucible instead of a carbon crucible, placing a raw material SiC powder in the BN crucible, and heating and calcining. As for the SiC powder which is a raw material, if a purity is 98% or more, a manufacturing method is not limited, It is not necessary to necessarily use single-crystal SiC.

Moreover, under such diffusion conditions, since the layer which emits good fluorescence is 1 µm to 4 µm from the surface, the lower limit of the particle size of the SiC powder is 2 µm, preferably 2.5 µm or more. In addition, since the layer which emits good fluorescence is 1 µm to 4 µm from the surface, and a portion deeper than 4 µm from the surface weakens the luminescence intensity, the upper limit of the particle diameter of the SiC powder is 10 µm, preferably 8 µm or less. For the same reason, the central particle size is preferably 3 µm to 6 µm, and more preferably 4 µm to 5 µm.

(Light emitting diode)

The light emitting diode of the present invention comprises a semiconductor substrate comprising at least one element of B and Al, a 6H type SiC single crystal phosphor doped with N, and a light emitting element comprising a nitride semiconductor on the substrate. .

By using the blue light-ultraviolet light emitted from the nitride semiconductor on the SiC substrate as excitation light, the SiC substrate emits fluorescence and is mixed with the light from the nitride semiconductor to realize a solid white light source. In addition, it is possible to provide a light source having high color temperature reproducibility of white light and excellent color rendering properties without requiring a difficult mounting technique.

For example, a light emitting diode having a GaN-based semiconductor that emits purple light having a wavelength of about 400 nm on a substrate made of a 6H type SiC single crystal phosphor doped with B and N, excites the violet light from the GaN-based semiconductor. Since the SiC substrate emits yellow fluorescence, white light having high reproducibility and good color rendering can be obtained by using yellow fluorescence from SiC and violet light from a GaN semiconductor.

Furthermore, one or two or more layers composed of at least one element of B and Al and a 6H type SiC single crystal phosphor doped with N are provided on a semiconductor substrate made of SiC, and a nitride semiconductor is placed on the 6H type SiC single crystal phosphor layer. The light emitting diode of the aspect provided with the light emitting element which consists of these is made into blue light or purple light by a nitride semiconductor as excitation light, and since 1 or 2 or more phosphor layers on a SiC substrate emit light according to the added impurity, An excellent solid white light source can be provided by mixing fluorescence or by mixing light and fluorescence from a nitride semiconductor.

For example, a first SiC layer doped with Al and N is formed on an n-SiC substrate doped with N, a second SiC layer doped with B and N is formed on the first SiC layer, and A light emitting diode having a GaN-based semiconductor that emits purple light having a wavelength of about 400 nm on a 2 SiC layer is characterized in that the second SiC layer emits yellow fluorescent light by using the violet light from the GaN-based semiconductor as an excitation light source. Since one SiC layer emits blue fluorescence, white light having high reproducibility and good color rendering property can be obtained by using yellow and blue fluorescence from the SiC layer.

As the SiC semiconductor substrate, a 6H type single crystal is used and doped with B, Al, and N, whereby white light can be obtained using the SiC substrate as the phosphor of the present invention. On the other hand, good white light can be obtained using the SiC phosphor layer and the nitride semiconductor layer formed on the substrate without using the SiC substrate as the phosphor. The doping concentration of at least one element of B and Al and the doping concentration with N of the 6H type SiC single crystal phosphor in the light emitting diode of the present invention are 10 ¹⁶ in terms of increasing the luminous efficiency. preferably a / ㎤~10 ¹⁹ / ㎤, more preferably 10 ¹⁷ / ㎤~10 ¹⁹ / ㎤.

One typical structure of the light emitting diode of the present invention is illustrated in FIG. In this example, the first impurity-added SiC layer 402 to which Al and N are added and the second impurity-added SiC layer 403 to which B and N are added are formed on the SiC substrate 401, for example, by the CVD method. By epitaxial growth. Further, for example, the AlGaN buffer layer 404, the n-GaN first contact layer 405, and the n-AlGaN first cladding are grown epitaxially on the SiC layer 403 by, for example, an organometallic compound vapor phase growth method. Forms layer 406, GaInN / GaN multi quantum well active layer 407, p-AlGaN electron block layer 408, p-AlGaN second cladding layer 409, and p-GaN second contact layer 410 do. Subsequently, after forming a p electrode 411 made of Ni / Au on the p-GaN second contact layer 410, as shown in FIG. 4, when the n-GaN first contact layer 405 is exposed. By etching to form the n-electrode 412 on the n-GaN first contact layer 405, the light emitting diode of the present invention is obtained. In this example, a light emitting element made of a nitride semiconductor refers to each layer on the second impurity-added SiC layer 403.

The excitation light from the nitride semiconductor is absorbed at the absorption end of SiC once, and the electron-hole pair is relaxed to the impurity level. Therefore, an aspect in which the SiC layer doped with an impurity is disposed between the SiC substrate 401 and the AlGaN buffer layer 404 is preferable. Although nitride semiconductor can be suitably selected from group III nitride semiconductors, such as GaN, it is preferable to select a semiconductor so that the light emission wavelength in the light emitting element used as an excitation wavelength may be a wavelength below 408 nm which is an absorption edge wavelength of 6H type SiC. Do.

The SiC layer to which Al, B, and N are added can be formed by epitaxial growth, but can also be formed by diffusion. For example, before epitaxially growing a nitride semiconductor, B or Al is diffused locally using a sputtered carbon as a mask on an N-added SiC substrate, partially divided into a yellow part and a blue part, thereby rendering the color rendering property in a single process. It is also possible to obtain a composite diode capable of controlling. In addition, the same effect is obtained even if B, Al, and N are added to one layer at the same time, in addition to the aspect which forms an impurity addition layer of two or more layers.

(Example 1)

The SiC fluorescent substance was produced by the improved Rayleigh method as shown in FIG. First, the board | substrate 1 which consists of SiC single crystal which is a seed crystal is attached to the inner surface of the lid 4 of the graphite crucible 3. In addition, the graphite crucible 3 was filled with a SiC powder (JIS particle size # 250) and a B source of high purity to be the raw material 2 and then mixed.

Subsequently, the graphite crucible 3 filled with the raw material 2 is covered with a lid 4, and the graphite crucible 3 is provided inside the quartz tube 5 by the support rod 6 made of graphite. The periphery of was covered with a black tin heat shield 7. As the atmospheric gas, Ar gas and N ₂ gas are caused to flow into the quartz tube 5 through the introduction tube 9 through the flowmeter 10 (flow rate of Ar gas 1 liter / minute). Subsequently, a high frequency current was made to flow through the work coil 8, and the temperature of the raw material 2 was 2300 degreeC, and it adjusted so that the temperature of the board | substrate 1 might be 2200 degreeC.

Subsequently, while adjusting the flow rates of Ar gas and N ₂ gas, the inside of the quartz tube 5 was decompressed using the vacuum pump 11. Decompression was gradually carried out from atmospheric pressure to 133 Pa over 20 minutes, and it hold | maintained at 133 Pa for 5 hours, and obtained the SiC crystal of diameter 55mm and thickness 10mm.

N ₂ in the atmospheric gas at the time of crystal growth The partial pressure of gas was 1%. As the B source, carbon impregnated with 5 mol% of B alone (metal boron) was used, and the SiC powder was mixed with the SiC powder so as to be 0.05 mol% with respect to the SiC powder to obtain a raw material powder.

When the density | concentration of B and N of the obtained SiC crystal was measured by SIMS, N was 5 * 10 <^17> / cm <3>, and B was 3 * 10 <^16> / cm <3>. In addition, after the crystal | crystallization of diameter 55mm and thickness 0.3mm was cut out from the obtained SiC single crystal, one surface was polished and fluorescence was measured with respect to the flat surface. As a result of the measurement, the peak wavelength was 620 nm, fluoresced with a wavelength of 500 nm to 750 nm, and showed a broad spectrum as shown in FIG.

Subsequently, the crystal after measurement was kept at 1850 ° C. for 4 hours and subjected to thermal annealing. As a result, the shape of the spectrum was substantially the same, but the relative intensity of light emission was improved by two or more times compared with that before the thermal annealing treatment.

(Example 2)

N ₂ in the atmospheric gas at the time of crystal growth SiC crystals were produced in the same manner as in Example 1 except that the partial pressure of the gas was 5% and the concentration for the SiC powder of the B single substance was 0.5 mol%. In the concentrations of N and B of the obtained SiC crystals, N was 3 × 10 ¹⁸ / cm 3 and B was 1 × 10 ¹⁷ / cm 3. In addition, although the shape of the fluorescence spectrum was the same as that of Example 1, the relative intensity of light emission improved almost three times as compared with the crystal before the thermal annealing treatment in Example 1.

(Example 3)

N ₂ in the atmospheric gas at the time of crystal growth SiC crystals were produced in the same manner as in Example 1 except that the partial pressure of the gas was set at 10% and the concentration with respect to the SiC powder of the B single substance was set at 5 mol%. In the concentrations of N and B of the obtained SiC crystals, N was 8 × 10 ¹⁸ / cm 3 and B was 5 × 10 ¹⁷ / cm 3. In addition, although the shape of the fluorescence spectrum was the same as in Example 1, the relative intensity of luminescence was improved by almost five times as compared with the crystal before the thermal annealing treatment in Example 1.

(Example 4)

N ₂ in the atmospheric gas at the time of crystal growth SiC crystals were produced in the same manner as in Example 1 except that the partial pressure of the gas was set at 30% and the concentration with respect to the SiC powder of the B single substance was set at 15 mol%. In the concentrations of N and B of the obtained SiC crystals, N was 1 × 10 ¹⁹ / cm 3 and B was 1 × 10 ¹⁸ / cm 3. In addition, although the shape of the fluorescence spectrum was the same as that of Example 1, the relative intensity of light emission fell to almost 1/10 compared with the crystal | crystallization before the thermal annealing process in Example 1.

From the results of Examples 1 to 4, N ₂ in the atmospheric gas at the time of crystal growth When the partial pressure of the gas is set to 1% to 30%, and the concentration of the Si B powder of B single substance is set to 0.05 mol% to 15 mol%, N is 5 × 10 ¹⁷ / cm 3 to 1 × 10 ¹⁹ / cm 3, and B is A SiC phosphor having a size of 3 × 10 ¹⁶ / cm 3 to 1 × 10 ¹⁸ / cm 3 was obtained, and it was found that such a phosphor emits fluorescence with a wavelength of 500 nm to 750 nm and has a peak wavelength at 500 nm to 650 nm. .

(Example 5)

A SiC single crystal having a diameter of 55 mm and a thickness of 10 mm was obtained in the same manner as in Example 1 except that the raw material powder was not blended with B source. From the obtained SiC single crystal, the crystal | crystallization of diameter 55mm and thickness 0.3mm was cut out similarly to Example 1, and one side was polished. Subsequently, TaB _{2 was made} into B source, 3 mol% of TaB ₂ was mixed with SiC powder with respect to SiC powder, and it fixed to the jig | tool. Mounting the grinding process described above a SiC crystal on a jig, and a flat surface and distance between the TaB ₂ of the SiC crystal was prepared so that the 0.1㎜.

Subsequently, this jig was placed in a carbon crucible, heated to 1800 ° C. under an atmosphere of Ar gas, and held for 4 hours. As a result of measuring fluorescence with respect to the obtained crystal, the peak wavelength was 620 nm, the fluorescence with a wavelength of 500 nm to 750 nm was emitted in the same manner as in Example 1, and the broad spectrum as shown in Fig. 3 was shown. In addition, when the density | concentration of B and N of the obtained SiC crystal | crystallization was measured by SIMS, N was 5 * 10 <^17> / cm <3>, B was 5 * 10 <^16> / cm <3> -8 * 10 <^18> cm <3>.

Moreover, when heat-annealing was performed at 1800 degreeC for 4 hours, although the shape of the fluorescence spectrum did not change, the relative intensity of light emission improved by 2 times. Subsequently, when the surface of the crystal was shaved by 2 m by RIE, the shape of the fluorescence spectrum was the same, and the relative intensity of light emission was improved by 1.5 times as compared with before shaping.

(Example 6)

The SiC single crystal obtained in Example 5 was ground by pulverization and classified to obtain a powder having a particle size of 2 µm to 3 µm, and the powder was placed in a crucible made of a white BN sintered compact and calcined by heating. Firing is N ₂ It carried out under reduced pressure at 300 Pa in the atmosphere of gas, and hold | maintained at 1800 degreeC for 4 hours. After firing, the SiC powder was ground by induction, and heated at 1200 ° C. for 3 hours under an atmospheric atmosphere (oxidative atmosphere) to form an oxide film on the surface. The obtained sintered compact was processed with 70% of fluoric acid, the surface was removed about 1 micrometer in thickness, it dried, and powder was obtained.

When the fluorescence was measured about the obtained powder, the peak wavelength was 640 nm, the fluorescence of 500 nm-750 nm of wavelength was emitted, and the broad spectrum like Example 5 was shown. In addition, when the density | concentration of B and N of the obtained powder was measured by SIMS, N was 7 * 10 <^17> / cm <3>, and B was 9 * 10 <^17> / cm <3>.

(Example 7)

4 shows the structure of the light emitting diode of this embodiment. The first impurity-added SiC layer 402 to which Al and N were added, and the second impurity-added SiC layer 403 to which B and N were added are epitaxially grown, for example, by the CVD method. To form. The AlGaN buffer layer 404, the n-GaN first contact layer 405, the n-AlGaN first cladding layer 406, for example, on the SiC layer 403 by an organic metal compound vapor phase growth method. GaInN / GaN multiple quantum well active layer 407, p-AlGaN electron block layer 408, p-AlGaN second cladding layer 409, and p-GaN second contact layer 410 were formed. Subsequently, after forming the p electrode 411 made of Ni / Au on the p-GaN second contact layer 410, as shown in FIG. 4, the n-GaN first contact layer 405 is exposed. It etched until it, and the n electrode 412 was formed on the n-GaN 1st contact layer 405, and the light emitting diode was obtained.

Subsequently, as shown in FIG. 5, this light emitting diode 501 was mounted on the stem 505. The mounting was performed in an episide down manner on the metal layers 503a and 503b of the insulating heat sink 502 formed on the stem 505 through the gold bumps 504. Then, the metal layer 503a and the wiring lead 506 were connected with the gold wire 507a, the gold wire 507b was connected to the metal layer 503b, and it fixed with the epoxy resin 508.

When voltage was applied to the light emitting diode 501 via the gold wires 507a and 507b, a current was injected into the light emitting diode. As a result, purple light having a wavelength of 400 nm was emitted from the GaInN / GaN multi-quantum well active layer 407 of FIG. 4. Of the violet light, the light emitted in the direction of the SiC substrate 401 enters the second impurity-added SiC layer 403 and the first impurity-added SiC layer 402, and almost all of them are absorbed by these layers. Fluorescence was generated according to the impurity level of each layer.

In the second impurity-added SiC layer 403, when B and N were added at a concentration of about 10 ¹⁸ / cm 3, and excited with 400 nm violet light, fluorescence having a spectrum as shown in FIG. 3 was emitted. . As can be seen from FIG. 3, the fluorescence has a wavelength of 500 nm to 750 nm, a peak wavelength of about 600 nm, and yellow fluorescence, but also contains a relatively large amount of red components exceeding 600 nm. In addition, the thickness of the 2nd impurity addition SiC layer 403 was 20 micrometers.

On the other hand, in the first impurity-added SiC layer 402, Al and N were added at a concentration of about 10 ¹⁸ / cm 3, and when excited with light of 400 nm, fluorescence having a spectrum as shown in FIG. 6 was emitted. . As can be seen from FIG. 6, the fluorescence was blue light having a wavelength of 400 nm to 750 nm and a peak wavelength of around 460 nm. In addition, the thickness of the 1st impurity addition SiC layer 402 was 20 micrometers.

By mixing the fluorescence by these two impurity-added SiC layers 402 and 403, white light excellent in color rendering property was obtained. The adjustment of the mixing ratio was possible by changing the doping concentration and the film thicknesses of the SiC layers 402 and 403 described above. From this fact, it turned out that the color temperature of white light is easy to adjust. In addition, since white light is generated inside the light emitting diode, the angle dependence of the color tone of the emitted white light is negligibly small.

(Example 8)

Fig. 7 shows the structure of the light emitting diode of this embodiment. As shown in FIG. 7, the light emitting diode includes a first impurity-added SiC layer 702 in which Al and N are added, and a second in which B and N are added, on the N-doped n-SiC substrate 701. The impurity-added SiC layer 703 was epitaxially grown by the CVD method. On the SiC layer 703, the n-AlGaN buffer layer 704, the n-GaN first contact layer 705, the n-AlGaN first cladding layer 706, and GaInN by the organometallic compound vapor phase growth method. / GaN multiple quantum well active layer 707, p-AlGaN electron block layer 708, p-AlGaN second cladding layer 709, and p-GaN second contact layer 710 were stacked. Subsequently, a p electrode 711 made of Ni / Au is formed on the surface of the p-GaN second contact layer 710, and an n electrode 712 is partially formed on the surface of the SiC substrate 701 to emit light. Got.

Subsequently, as shown in FIG. 8, this light emitting diode 801 was mounted on the stem 805. The mounting was performed on the metal layer 803 of the insulating heat sink 802 formed on the stem 805 in an episide down manner. Thereafter, the metal layer 803 and the wiring lead 806 were connected to the gold wire 807, and fixed with an epoxy resin 808.

When voltage was applied to the light emitting diode 801, a current was injected into the light emitting diode. As a result, purple light having a wavelength of 400 nm was emitted from the GaInN / GaN multi-quantum well active layer 707 of FIG. 7. Of the violet light, the light emitted in the direction of the SiC substrate 701 enters the second impurity-added SiC layer 703 and the first impurity-added SiC layer 702, and almost all of them are absorbed by these two layers. In addition, fluorescence was generated according to the impurity level of each SiC layer.

In the second impurity-added SiC layer 703, B and N were added at a concentration of about 10 ¹⁸ / cm 3, and when excited with 400 nm of light, fluorescence having a spectrum as shown in FIG. 3 was emitted. . As can be seen from FIG. 3, the fluorescence has a wavelength of 500 nm to 750 nm, a peak wavelength of about 600 nm, and yellow fluorescence, but also contains a relatively large amount of red components exceeding 600 nm. In addition, the thickness of the 2nd impurity addition SiC layer 703 was 30 micrometers.

On the other hand, in the first impurity-added SiC layer 702, Al and N were added at a concentration of about 10 ¹⁸ / cm 3, and when excited with light of 400 nm, fluorescence having a spectrum as shown in FIG. 6 was emitted. . As can be seen from FIG. 6, the fluorescence was blue light having a wavelength of 400 nm to 750 nm and a peak wavelength of around 460 nm. In addition, the thickness of the 1st impurity addition SiC layer 702 was 30 micrometers.

By mixing the fluorescence by these two impurity-added SiC layers 702 and 703, white light excellent in color rendering property was obtained. The mixing ratio was controlled by changing the impurity concentration to be doped and the film thicknesses of the SiC layers 702 and 703. From this, it turned out that adjustment of the color tone of white light is easy. In addition, since white light is generated inside the light emitting diode, the angle dependence of the color tone of the emitted white light is negligibly small.

(Example 9)

In this embodiment, white light is synthesized by combining a conventional nitride semiconductor light emitting diode having a light emission wavelength of 440 nm to 480 nm with the light emitting diode of the present invention. The light emitting diode of the present invention is a light emitting diode that emits yellow fluorescence by using violet light by a nitride semiconductor as excitation light.

A light emitting diode as in Example 8, except that the first impurity-added SiC layer doped with Al and N was not formed, and only the second impurity-added SiC layer doped with B and N was formed as the impurity-added SiC layer. Was produced and mounted similarly to Example 8 as shown in FIG.

When a current is injected into the light emitting diode, violet light having a wavelength of 400 nm is emitted in the GaInN / GaN multi-quantum well active layer, and the violet light emitted in the direction of the SiC substrate enters the impurity-added SiC layer, and the impurity-added SiC layer. Almost all of them were absorbed and fluoresced.

The impurity-added SiC layer was added at a concentration of about 10 ¹⁸ / cm 3 of both B and N, and when excited with 400 nm light, yellow fluorescence having a spectrum as shown in FIG. 3 was emitted. As can be seen from FIG. 3, the yellow fluorescence had a wavelength of 500 nm to 750 nm, a peak wavelength of about 600 nm, and a relatively large amount of red components exceeding 600 nm. In addition, the thickness of the impurity addition SiC layer was 30 micrometers.

The yellow light emitting diode is disposed in combination with a conventional light emitting diode (not shown) made of a nitride semiconductor having a light emission wavelength of 440 nm to 480 nm, and emits light from a diode emitting yellow light and emits light from a conventional diode. By mixing 3: 1, white light excellent in color rendering property could be synthesized.

As a diode emitting yellow light, an AlGaInP quaternary high-brightness diode has been put into practical use, but the light emitting diode produced in this embodiment shows a broad spectrum as shown in Fig. 3, so it is combined with a blue light emitting diode. By doing this, it was found that white with high color rendering property can be obtained more easily.

(Example 10)

SiC crystals were grown in the same manner as in Example 1 except that instead of the B source at the time of crystal growth, Al was mixed with the SiC powder so as to be 0.1 mol% with respect to the SiC powder to form a raw material powder. In the concentrations of Al and N of the obtained SiC crystals, N was 5 × 10 ¹⁷ / cm 3 and Al was 2 × 10 ¹⁶ / cm 3. In addition, the fluorescence spectrum exhibited a broad spectrum as shown in Fig. 6, with a peak wavelength of 430 nm, fluorescence with a wavelength of 400 nm to 750 nm.

Subsequently, the crystal after measurement was kept at 1850 ° C. for 4 hours and subjected to thermal annealing. As a result, the shape of the spectrum was approximately the same, but the relative intensity of light emission was improved by twice or more compared with that before the thermal annealing treatment.

(Example 11)

N ₂ in the atmospheric gas at the time of crystal growth SiC crystals were produced in the same manner as in Example 10 except that the partial pressure of the gas was 5% and the concentration of the Al single SiC powder was 1 mol%. N and Al of the obtained SiC crystals had concentrations of 5 × 10 ¹⁸ / cm 3 and Al of 1 × 10 ¹⁷ / cm 3. In addition, although the shape of the fluorescence spectrum was the same as in Example 10, the relative intensity of light emission was almost doubled as compared with the crystal before the thermal annealing treatment in Example 10.

(Example 12)

N ₂ in the atmospheric gas at the time of crystal growth SiC crystals were produced in the same manner as in Example 10 except that the partial pressure of the gas was set to 10% and the concentration of the Al-based SiC powder was set to 10 mol%. N and Al of the obtained SiC crystals had concentrations of 8 × 10 ¹⁸ / cm 3 and Al of 4 × 10 ¹⁷ / cm 3. In addition, although the shape of the fluorescence spectrum was the same as in Example 10, the relative intensity of light emission was improved almost three times as compared with the crystal before the thermal annealing treatment in Example 10.

(Example 13)

N ₂ in the atmospheric gas at the time of crystal growth SiC crystals were produced in the same manner as in Example 10 except that the partial pressure of the gas was set to 30% and the concentration with respect to the SiC powder of Al alone was set to 20 mol%. N and Al of the obtained SiC crystals had concentrations of 1 × 10 ¹⁹ / cm 3 and Al of 1 × 10 ¹⁸ / cm 3. In addition, although the shape of the fluorescence spectrum was the same as in Example 10, the relative intensity of light emission decreased to almost 1/3 or less as compared with the crystal before the thermal annealing treatment in Example 10.

The embodiments and examples disclosed herein are examples in all respects and should not be considered as limiting. It is intended that the scope of the invention be defined by the claims rather than the foregoing description, and include equivalent modifications and all variations within the scope.

Since the SiC fluorescent substance of the present invention emits fluorescence with good efficiency even when relatively long wavelength blue-purple light is used as primary light, a mixed color of excitation light and fluorescence can be obtained, and the semiconductor element or the like emits light. It is possible to manufacture a light emitting diode using relatively long wavelength excitation light. This light emitting diode is useful as a white light source which is excellent in color rendering property, low in cost, and high in light emission efficiency. In addition, since SiC is a material having high covalent bonds, it is difficult to deteriorate and has conductivity, so it can withstand strong electron beams and can be used for discharge tubes and PDPs.

Claims (23)

delete delete delete delete delete delete delete Excited by an external light source, fluorescing at a wavelength of 500 nm to 750 nm, having a peak wavelength at 500 nm to 650 nm, doped with N and B, and the concentration of either N or B is 10 ¹⁵ / As a method for producing a SiC-based phosphor having a cm 3 to 10 ¹⁸ / cm 3 and the other concentration of 10 ¹⁶ / cm 3 to 10 ¹⁹ / cm 3, SiC crystals formed by a sublimation recrystallization method using carbon containing LaB ₆ , B ₄ C, TaB ₂ , NbB ₂ , ZrB ₂ , HfB ₂ , BN, or B as a B source; Method of producing phosphors. Excited by an external light source, fluorescing at a wavelength of 500 nm to 750 nm, having a peak wavelength at 500 nm to 650 nm, doped with N and B, and the concentration of either N or B is 10 ¹⁵ / As a method for producing a SiC-based phosphor having a cm 3 to 10 ¹⁸ / cm 3 and the other concentration of 10 ¹⁶ / cm 3 to 10 ¹⁹ / cm 3, A single B, LaB ₆ , B ₄ C, TaB ₂ , NbB ₂ , ZrB ₂ , HfB ₂ or BN is a B source, and is thermally diffused into SiC at 1500 ° C. or higher under vacuum or an inert gas atmosphere. The manufacturing method of the fluorescent substance made by SiC. The method according to claim 8 or 9, A sublimation recrystallization or heat diffusion, followed by a thermal annealing treatment for 1 hour or more at 1300 ℃ or more, characterized in that the manufacturing method of the SiC phosphor. The method of claim 9, The surface layer is removed after thermal diffusion, The manufacturing method of the SiC fluorescent substance characterized by the above-mentioned. delete delete delete Excited by an external light source, fluorescing at a wavelength of 500 nm to 750 nm, having a peak wavelength at 500 nm to 650 nm, doped with N and B, and the concentration of either N or B is 10 ¹⁵ / As a method for manufacturing a substrate made of a 6H type SiC single crystal phosphor having a cm 3 to 10 ¹⁸ / cm 3 and the other concentration of 10 ¹⁶ / cm 3 to 10 ¹⁹ / cm 3, B single group, LaB ₆ , B ₄ C, TaB ₂ , NbB ₂ , ZrB ₂ , HfB ₂ or BN as a source B and thermally diffusing SiC at 1500 ° C. or higher under vacuum or an inert gas atmosphere; , The manufacturing method of the board | substrate for semiconductors characterized by including the process of removing a surface layer. Excited by an external light source, fluorescing at a wavelength of 500 nm to 750 nm, having a peak wavelength at 500 nm to 650 nm, doped with N and B, and the concentration of either N or B is 10 ¹⁵ / As a method for manufacturing a substrate made of a 6H type SiC single crystal phosphor having a cm 3 to 10 ¹⁸ / cm 3 and the other concentration of 10 ¹⁶ / cm 3 to 10 ¹⁹ / cm 3, Atmosphere during crystal growth gas, the gas partial pressure of 1% including a N ₂ gas to 30%, and the raw material SiC SiC by sublimation recrystallization method which is characterized in that it contains a source of B 0.05㏖% ~15㏖% The manufacturing method of the board | substrate for semiconductors which forms a crystal | crystallization. The method according to claim 15 or 16, After the sublimation recrystallization or heat diffusion, a thermal annealing treatment is performed at 1300 ° C or higher. It is excited by an external light source, emits fluorescence with a wavelength of 500 nm to 750 nm, and consists of a 6H type SiC single crystal phosphor having a peak wavelength at 500 nm to 650 nm, having a particle diameter of 2 µm to 10 µm, and a central particle diameter of 3 Powder for semiconductors which is a micrometer-6 micrometers. delete delete delete delete delete

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