JPH11340516A - Display device and illuminator thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high luminance, high-resolution, and thin display device which does not consume much electric power, and an illuminator thereof. SOLUTION: In a color display device which is provided with a GaN-based light-emitting diode array on a substrate 1 and a red phosphor 5, a green phosphor 6, and a blue phosphor 7 correspondingly to each GaN-based light-emitting diode 2 and causes the phosphors phosphors 5, 6, and 7 to emit light by exciting the phosphors 5, 6, and 7 with light emitted from each diode 2, the phosphors 5, 6, and 7 are constituted of crystals having crystal grain diameters, which are twice that of the exciton Bohr radius or smaller. It is also possible to use the blue light rays emitted from the diodes as they are without providing the blue phosphor 7. When a white phosphor is used, a white illuminator can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device and a lighting device, and more particularly to a light emitting device using a nitride III-V compound semiconductor and a phosphor excited by light emitted from the light emitting device. It is suitable for application to a display device and a lighting device that have been used.

[0002]

2. Description of the Related Art A GaN-based semiconductor is a direct transition semiconductor, and has a forbidden band ranging from 1.9 eV to 6.2 eV. It is possible to realize a light emitting device capable of emitting light in a visible region to an ultraviolet region. For this reason, it has attracted attention in recent years, and its development is being actively promoted.

As an apparatus using such a GaN-based light-emitting element, an all-color image display apparatus has been proposed (Japanese Patent Laid-Open No. Hei 8 (1996)).
-63119). In this full-color image display device, a phosphor emitting three primary colors of red, green, and blue is excited by a GaN-based light-emitting diode array disposed on a substrate, or red and green are excited by a GaN-based light-emitting diode array, respectively. A green phosphor is excited, and blue light emitted from a GaN-based light emitting diode is used.

On the other hand, a next-generation display device is desired to have high luminance and high resolution. Since the luminance is determined by the output of the light emitting diode and the quantum efficiency of the phosphor, a phosphor having a higher quantum efficiency is desired. In addition, since the resolution is determined by the size of the pixel, when forming a fluorescent screen by applying a fluorescent material, the size of the phosphor crystal particles must be reduced in accordance with the size of the pixel.

[0005]

However, non-radiative recombination due to surface levels is generally dominant in the vicinity of the phosphor crystal surface, and hardly contributes to light emission. For this reason, the quantum efficiency decreases as the size of the phosphor crystal particles decreases. It is said that this decrease is remarkable especially when the particle size is about 1 μm or less.

Further, it is possible to form a fluorescent screen by forming a fluorescent material by epitaxial growth, vacuum deposition, sputtering, or the like.
There is an inconvenience that light propagates in a guided manner in a phosphor surface having a large refractive index, and the light is hardly radiated to the outside.

[0007] For the above reasons, G
It has been difficult to realize a high-luminance and high-resolution display device using an aN-based light-emitting element.

Accordingly, an object of the present invention is to provide a high brightness,
It is to provide a high-resolution, low-power-consumption, thin display device.

Another object of the present invention is to provide a high-luminance, low-power-consumption, thin, all-solid-state lighting device.

[0010]

When the crystal size is reduced to about the exciton Bohr radius (hereinafter, such a crystal is called "nanocrystal"), confinement of excitons and an increase in band gap due to the quantum size effect are observed. (J. Chem. Phys., Vol. 80, No. 9, p. 1984). It has been reported that some semiconductors of such a size have a large quantum efficiency in photoluminescence (Phy
s. Rev. Lett., Vol. 72, No. 3, p. 416, 1994, MRSbulletin V
ol. 23, No. 2, p. 18, 1998 and U.S. Pat. No. 5,455,489.
issue). This effect can be easily compared with Mn-doped ZnS (ZnS: M
This will be described by taking n) as an example. Table 1 shows a comparison of the luminance of light emission when the ZnS: Mn nanocrystal surface-treated with methacrylic acid and bulk ZnS: Mn particles having a particle size of 1 μm or more are excited by the same ultraviolet lamp. From Table 1, it can be seen that bulk ZnS: Mn nanocrystals
It can be seen that a luminance nearly five times higher than that of the S: Mn particles is obtained.

[0011] Table 1 --------------------------- Nanocrystal bulk −−−− Luminance 69 cd / m ² 14.2 cd / m ² −−−−−−−−−−−−−−−−−−−−−−−− Such high quantum effect and quantum size effect are obtained. Although it is not yet clearly explained how they are physically related, increase in oscillator strength due to electron-hole pair formation, decrease in state density that does not contribute to light emission due to quantization of energy levels, It is considered that the influence of the change of the crystal field near the emission center due to the lattice distortion, the crystal surface treatment, and the like are related. It is not clear which of these elements contributes effectively to the luminous efficiency, but an increase in luminous efficiency has been reported for crystals having a size smaller than the exciton Bohr radius described below. Here, the exciton Bohr radius indicates the spread of the existence probability of excitons, and 4πε ₀ h ² / me ² (where ε ₀ is the low-frequency permittivity of the material, h is Planck's constant,
m is the reduced mass obtained from the effective mass of electrons and holes,
e is the electron charge). For example, the exciton Bohr radius of ZnS is about 2 nm.

An example of the most typical quantum size effect is an increase in the band gap. Figure 1 shows LEBr
3 shows the crystal size dependence of the band gap of ZnS calculated based on the theory of Us et al. Since the original band gap of ZnS is about 3.5 eV, it can be predicted that the quantum size effect will increase in a range smaller than about 8 nm in diameter. This diameter value corresponds to a crystal having a radius twice the exciton Bohr radius. Therefore, by using a phosphor made of a crystal having a size equal to or smaller than twice the exciton Bohr radius, the contribution of the quantum size effect to light emission can be utilized.

On the other hand, in a crystal that has not been subjected to surface treatment, electrons excited by dangling bonds of ions present on the surface are captured and non-radiatively recombined, so that the luminous intensity is significantly reduced. For example, as shown in Table 2, in a ZnS: Mn nanocrystal surface-treated with acrylic acid, dangling bonds on the crystal surface are effectively terminated, and the luminescence intensity is significantly increased as compared with a sample not surface-treated. ing. Also, as shown in FIG.
In the CdSe nanocrystal capped by the above, not only the dangling bonds on the crystal surface are similarly terminated but also the electron-
Hole pairs are strongly confined within the nanocrystal and recombine. With this material, luminous efficiency higher by one order of magnitude or more than that of CdSe nanocrystal without capping can be obtained.
% Quantum efficiency can be obtained.

Table 2 Surface treatment Acrylic acid None ----------- −−−−−−−−−−− Luminance 69 cd / m ² 9.4 cd / m ² −−−−−−−−−−−−−−−−−−−−−− ZnSe as a phosphor The case where quantum dots are used will be described. At room temperature, ZnSe originally has a band gap of 2.58 eV, but has a crystal size of 8.5 ± 1.
When the band gap is reduced to about 5 nm, the band gap increases to about 2.8 eV due to the quantum size effect.
Band edge emission is observed around 5 nm (FIG. 3). Zn
Since the exciton Bohr radius of Se is about 4 nm, the crystal grain size of this phosphor is considered to be almost the same. This fluorescent material induces a chemical reaction by ultraviolet irradiation,
A dangling bond on the crystal surface can be terminated, and a reactant generated on the crystal surface serves as a potential barrier, so that an ideal quantum well structure can be formed. For this reason, as shown in FIG. 4, the luminous intensity can be significantly increased by the ultraviolet treatment.

FIG. 3 shows the excitation spectrum (excitation wavelength dependence of emission intensity) of this phosphor. According to FIG.
A peak is observed at nm and a wavelength of 370 nm. Among these, the peak at 370 nm on the long wavelength side is Ga
Since it corresponds to the band gap of N, high luminous efficiency can be obtained by exciting this phosphor with an ultraviolet light emitting diode using GaN or GaInN obtained by adding In to GaN as a material of the active layer. Also, the half width of the emission peak is very narrow, about 20 nm for ZnSe quantum dots, compared to 60 nm of ZnS: Ag having a particle size of several μm used in the conventional blue phosphor, so that a display with good color quality is provided. Can be realized.

On the other hand, as for the green and red phosphors, Zn ₁ -xC obtained by substituting a part of Zn of ZnSe with Cd is used.
The band gap can be reduced by using d _x Se (where 0 <x ≦ 1) quantum dots. Then, in this Zn _1-x Cd _x Se quantum dot, Zn
By changing the composition ratio of Cd and Cd or the crystal size, light emission of a desired wavelength can be obtained. A full-color display can be realized by using light emission of these direct band-to-band transitions.

Further, a white phosphor mixed with a red phosphor, a green phosphor and a blue phosphor composed of the nanocrystal as described above is used, and the white phosphor is excited by light of a GaN-based light emitting diode. , A white lighting device can be obtained.

As described above, some phosphors composed of microcrystals that exhibit a quantum size effect, that is, nanocrystals, exhibit extremely high quantum efficiency. By exciting,
An efficient display device and lighting device can be realized.

The present invention has been devised based on the above study by the present inventors.

That is, in order to achieve the above object, a first invention of the present invention is to provide a light emitting device using a nitride III-V compound semiconductor, and a phosphor excited by light emitted from the light emitting device. Wherein the phosphor is made of a crystal having a particle size of twice or less the exciton Bohr radius.

The second invention of the present invention relates to a nitride III
A lighting device including a light-emitting element using a group V compound semiconductor and a phosphor excited by light emitted from the light-emitting element, wherein the phosphor has a particle diameter of twice or less the exciton Bohr radius. It is a lighting device characterized by comprising.

In the present invention, preferably, dangling bonds on the surface of the crystal constituting the phosphor are terminated. Also, typically, the crystal constituting the phosphor has a quantum well structure.

In the present invention, the light emitting elements are typically arranged in a one-dimensional or two-dimensional array. In addition, these light-emitting elements are typically provided on a substrate such as a sapphire substrate, a SiC substrate, a ZnO substrate, or the like.
It is formed by growing a II-V compound semiconductor.

In a first embodiment of the present invention, in one typical example, the phosphor is a red phosphor, a green phosphor, and a blue phosphor provided in a red light emitting portion, a green light emitting portion, and a blue light emitting portion, respectively. Consisting of a body, these red phosphors,
A light emitting element is provided corresponding to each of the green phosphor and the blue phosphor, and light emitted from the light emitting element excites the red phosphor, the green phosphor, and the blue phosphor to emit red, green, and blue, respectively. It is configured to emit light. Further, in another typical example, the phosphor includes a red phosphor and a green phosphor provided in a red light emitting portion and a green light emitting portion, respectively, and corresponds to each of the red phosphor and the green phosphor. While the light-emitting element is provided, a light-emitting element is provided in the blue light-emitting portion, these red phosphor and green phosphor are excited by light emitted from the light-emitting element to emit red and green light, respectively, The light-emitting element provided in the blue light-emitting section emits blue light directly.

In the second aspect of the present invention, the phosphor typically comprises a white phosphor in which a red phosphor, a green phosphor and a blue phosphor are mixed, and the white phosphor is emitted by light emitted from the light emitting element. Are excited to excite and emit red, green, and blue, respectively, to emit white light.

In the present invention, the crystals constituting the red phosphor and the green phosphor are made of, for example, Zn _1-x Cd _x Se (where 0 <x ≦ 1), and the crystals constituting the blue phosphor are made of, for example, ZnSe. Become.

In the present invention, the nitride III-V compound semiconductor contains at least one group III element selected from the group consisting of Ga, Al, In and B, and at least N, and optionally further contains As. Or a group V element containing P. Specific examples of the nitride III-V compound semiconductor include GaN, AlGaN, A
1N, GaInN, AlGaInN, InN and the like.

According to the first aspect of the present invention constructed as described above, since the phosphor is made of a crystal having a grain size of twice or less the exciton Bohr radius, the nitride III-V compound By exciting this phosphor by light emitted from a light emitting element using a semiconductor, the quantum efficiency of the phosphor can be increased, and the resolution can be enhanced by the extremely small size of the crystal constituting the phosphor. be able to.

According to the second aspect of the present invention configured as described above, since the phosphor is made of a crystal having a particle size of twice or less the exciton Bohr radius, the nitride III-V compound By exciting this phosphor by light emitted from a light emitting element using a semiconductor, the quantum efficiency of the phosphor can be increased, and the size of the crystal constituting the phosphor is extremely small, so that a more uniform Lighting can be obtained.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. In all the drawings of the embodiments, the same or corresponding portions are denoted by the same reference numerals.

FIG. 5 shows a color display device according to the first embodiment of the present invention. As shown in FIG. 5, in the color display device according to the first embodiment, GaN-based light emitting diodes 2 are arranged in a two-dimensional array on a sapphire substrate 1 having a size corresponding to a display area. .
The emission wavelength of the GaN-based light emitting diode 2 is, for example, 38
It is about 0 nm. As the sapphire substrate 1, for example, c
A plane orientation is used. These GaN-based light emitting diodes 2 are separated from each other by partition walls 3. An ultraviolet cutoff filter 4 having the same size as the sapphire substrate 1 is provided in parallel with the sapphire substrate 1 so as to face the sapphire substrate 1 with these GaN-based light emitting diodes 2 interposed therebetween. Each of the GaN-based light emitting diodes 2 is provided on the main surface of the ultraviolet cutoff filter 4 on the GaN-based light emitting diode 2 side.
Are provided in correspondence with. Specifically, three GaN-based light-emitting diodes 2 adjacent to each other are formed as a set, and a red phosphor 5, a green phosphor 6, and a blue phosphor 7 are provided for each of these GaN-based light-emitting diodes 2. I have. Then, Ga corresponding to each of the red phosphor 5, the green phosphor 6, and the blue phosphor 7 is used.
The light emitted from the N-based light emitting diode 2 is irradiated and excited to emit red, green and blue light, respectively. In this case, one set of the red phosphor 5, the green phosphor 6, and the blue phosphor 7 and the corresponding set of the GaN-based light emitting diodes 2 corresponds to one set.
Pixels are formed.

FIG. 6 shows an example of the structure of the GaN-based light emitting diode 2. As shown in FIG. 6, this GaN-based light-emitting diode 2 has a GaN buffer layer 2 on a sapphire substrate 1.
1, n-type GaN contact layer 22, n-type AlGaN cladding layer _{23, Ga 1-x In x} N / Ga 1-y In y N multi active layer 24 of quantum well structure, p-type AlGaN cladding layer 25 and p-type GaN It has a structure in which the contact layers 26 are sequentially laminated. n-type AlGaN cladding layer 23, active layer 24, p-type AlGaN cladding layer 25, and p-type GaN
The contact layer 26 has a predetermined mesa shape. And
A p-side electrode 27 made of, for example, a Ti / Au film is in ohmic contact with the p-type GaN contact layer 26, and a Ti / Au film is formed on the n-type GaN contact layer 22.
An n-side electrode 28 made of an Al film is in ohmic contact.

The formation of the GaN-based light emitting diode 2 is performed as follows. That is, a GaN buffer layer 21 is grown on the sapphire substrate 1 at a temperature of, for example, about 560 ° C. by a metal organic chemical vapor deposition (MOCVD) method, and subsequently, an n-type buffer layer is formed on the GaN buffer layer 21 by the MOCVD method. GaN contact layer 22, n-type Al
A GaN cladding layer 23, an active layer 24, a p-type AlGaN cladding layer 25, and a p-type GaN contact layer 26 are sequentially grown. Here, n-type Ga which is a layer not containing In is used.
N contact layer 22, n-type AlGaN cladding layer 23,
The growth temperature of the p-type AlGaN cladding layer 25 and the p-type GaN contact layer 26 is about 1000 ° C., and the active layer having a Ga _1-x In _x N / Ga _1-y In _y N multiple quantum well structure which is an In-containing layer. 24 has a growth temperature of 700 to 800 ° C.
And Thereafter, electrical activation of n-type impurities and p-type impurities doped in these layers, in particular, p-type AlGaN
Heat treatment for electrically activating p-type impurities doped in the cladding layer 25 and the p-type GaN contact layer 26 is performed. This heat treatment is performed, for example, at a temperature of 800 ° C. in a nitrogen gas atmosphere. Next, after a resist pattern (not shown) having a predetermined stripe shape is formed on the p-type GaN contact layer 26, the n-type GaN contact layer 22 is formed by using the resist pattern as a mask, for example, by a reactive ion etching (RIE) method. Until it reaches. Thereafter, the resist pattern is removed. Next, a p-side electrode 27 is formed on the p-type GaN contact layer 26, and an n-side electrode 28 is formed on the n-type GaN contact layer 22. Next, after forming a predetermined stripe-shaped resist pattern (not shown) on the substrate surface,
Using this resist pattern as a mask, a GaN buffer layer 21, an n-type GaN contact layer 22, an n-type AlGaN
Cladding layer 23, Ga _1-x In _x N / Ga _1-y In _y N
The active layer 24 having a multiple quantum well structure, the p-type AlGaN cladding layer 25, and the p-type GaN contact layer 26 are etched. As described above, the GaN-based light emitting diodes 2 are formed in a two-dimensional array in a state of being separated from each other.

In the first embodiment, as the red phosphor 5, for example, x = 0.
Nanocrystals composed of 90 Zn _1-x Cd _x Se or those composed of Zn _1-x Cd _x Se quantum dots are used. Further, as the green phosphor 6, for example, a particle size of 6 to
For example, a 10 nm nanocrystal made of Zn _1-x Cd _x Se with x = 0.38 or _{one made of} Zn _1-x Cd _x Se quantum dots is used. In addition, the blue phosphor 6
A nanocrystal made of ZnSe having a particle diameter of about 6 to 10 nm or a material made of ZnSe quantum dots is used.

In the color display device according to the first embodiment configured as described above, a current corresponding to an input signal is injected into each GaN-based light emitting diode 2, and each GaN-based light emitting diode 2
By exciting the red phosphor 5, the green phosphor 6, and the blue phosphor 7 with the light generated from the system light emitting diode 2, full-color display can be performed.

As described above, according to the first embodiment, each of the red phosphor 5, the green phosphor 6 and the blue phosphor 7 is made of a crystal having a particle size smaller than the exciton Bohr radius, ie, a nanocrystal. Accordingly, a full-color flat display with high luminance, high resolution, and low power consumption can be realized.

FIG. 7 shows a color display device according to a second embodiment of the present invention. As shown in FIG. 7, in the color display device according to the second embodiment, the blue phosphor 7
Is not provided. In addition, a GaN-based light emitting diode 2
Has an emission wavelength of about 460 nm. In this case, in the blue light emitting section, the blue light emitted from the GaN-based light emitting diode 2 is directly emitted to the outside through the ultraviolet cutoff filter 4. The other points are the same as those of the color display device according to the first embodiment, and the description is omitted.

According to the second embodiment, there are the same advantages as the first embodiment.

FIG. 8 shows a lighting device according to a third embodiment of the present invention. As shown in FIG. 8, in the lighting device according to the third embodiment, GaN-based light emitting diodes 2 are arranged in a two-dimensional array on a sapphire substrate 1 having a predetermined size. The emission wavelength of the GaN-based light emitting diode 2 is, for example, about 380 nm. As the sapphire substrate 1, for example, a c-plane substrate is used. These GaN-based light emitting diodes 2 are separated from each other by partition walls 3. An ultraviolet cutoff filter 4 having the same size as the sapphire substrate 1 is provided in parallel with the sapphire substrate 1 so as to face the sapphire substrate 1 with these GaN-based light emitting diodes 2 interposed therebetween. The main surface of the ultraviolet blocking filter 4 on the GaN-based light emitting diode 2 side is provided with each G
A white phosphor 8 is provided corresponding to the aN-based light emitting diode 2. G corresponding to the white phosphor 8
The light emitted from the aN-based light emitting diode 2 is irradiated and excited to emit white light.

The structure and forming method of the GaN-based light emitting diode 2 are the same as those of the first embodiment, and the description is omitted.

In the third embodiment, as the white phosphor 8, three types of nanocrystals constituting the red phosphor 5, the green phosphor 6, and the blue phosphor 7 used in the first embodiment are used. What consists of what mixed is used.

According to the third embodiment, it is possible to realize a flat illuminating device with high luminance and low power consumption, and, unlike the conventional illuminating device, an illumination having an all-solid and extremely high mechanical strength. The device can be realized.

Although the embodiment of the present invention has been specifically described above, the present invention is not limited to the above embodiment, and various modifications based on the technical idea of the present invention are possible.

For example, the numerical values, structures, substrates, processes, and the like described in the first, second, and third embodiments are merely examples, and different numerical values, structures, substrates, and the like may be used as necessary. A process or the like may be used.

[0045]

As described above, according to the first aspect of the present invention, since the phosphor is made of a crystal having a particle size of twice or less the exciton Bohr radius, high brightness, high resolution, A low power consumption and thin display device can be realized.

According to the second aspect of the present invention, a high-luminance, low-power-consumption, and low-profile illumination device is realized by using a phosphor having a grain diameter smaller than twice the exciton Bohr radius. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the crystal size dependence of the band gap energy of ZnS.

FIG. 2 is a cross-sectional view and an energy band diagram showing a CdSe quantum dot.

FIG. 3 is a schematic diagram showing a photoluminescence spectrum and an excitation spectrum measured at room temperature.

FIG. 4 is a schematic diagram showing the photoluminescence intensity of ZnSe quantum dots as a function of ultraviolet irradiation time.

FIG. 5 is a sectional view showing the color display device according to the first embodiment of the present invention.

FIG. 6 is a sectional view showing a structural example of a GaN-based light emitting diode in the color display device according to the first embodiment of the present invention.

FIG. 7 is a sectional view showing a color display device according to a second embodiment of the present invention.

FIG. 8 is a cross-sectional view illustrating a lighting device according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sapphire board, 2 ... GaN light emitting diode, 3 ... Partition wall, 4 ... UV cutoff filter,
5 red phosphor, 6 green phosphor, 7 blue phosphor, 8 white phosphor

Claims (14)

[Claims] 1. A display device comprising a light emitting device using a nitride III-V compound semiconductor and a phosphor excited by light emitted from the light emitting device, wherein the phosphor has an exciton Bohr radius. A display device comprising a crystal having a grain size of twice or less. 2. The display device according to claim 1, wherein dangling bonds on the surface of the crystal are terminated. 3. The display device according to claim 1, wherein said crystal has a quantum well structure. 4. The display device according to claim 1, wherein said light-emitting elements are arranged in an array. 5. The phosphor comprises a red phosphor, a green phosphor, and a blue phosphor provided in a red light-emitting portion, a green light-emitting portion, and a blue light-emitting portion, respectively. The light emitting elements are provided corresponding to the respective phosphors, and the red, green, and blue phosphors are excited by light emitted from the light emitting elements to emit red, green, and blue light, respectively. The display device according to claim 1, wherein the display device is configured as follows. 6. The phosphor comprises a red phosphor and a green phosphor provided in a red light emitting portion and a green light emitting portion, respectively, and the light emitting element corresponds to each of the red phosphor and the green phosphor. Is provided,
The blue light emitting section is provided with the light emitting element, and the red and green phosphors are excited by light emitted from the light emitting element to emit red and green light, respectively, and the blue light emitting section is provided in the blue light emitting section. The display device according to claim 1, wherein the display device is configured to emit blue light directly from the light emitting element. 7. A crystal constituting the red phosphor and the green phosphor is Zn _{1 -x} Cd _x Se (where 0 <x ≦
1), and the crystal constituting the blue phosphor is ZnS
The display device according to claim 5, comprising e. 8. A crystal constituting the red phosphor and the green phosphor is Zn _{1 -x} Cd _x Se (where 0 <x ≦
7. The display device according to claim 6, wherein the display device comprises: 9. An illuminating device comprising: a light emitting device using a nitride III-V compound semiconductor; and a phosphor excited by light emitted from the light emitting device, wherein the phosphor is an exciton Bohr. An illuminating device comprising a crystal having a particle size of twice or less the radius. 10. The lighting device according to claim 9, wherein dangling bonds on the surface of the crystal are terminated. 11. The lighting device according to claim 9, wherein the crystal has a quantum well structure. 12. The lighting device according to claim 9, wherein the light-emitting elements are arranged in an array. 13. The phosphor according to claim 1, wherein the phosphor is a white phosphor in which a red phosphor, a green phosphor and a blue phosphor are mixed, and the red phosphor constituting the white phosphor by light emitted from the light emitting element; 10. The lighting device according to claim 9, wherein the green phosphor and the blue phosphor are excited to emit red, green, and blue light, respectively, to emit white light. 14. A crystal constituting the red phosphor and the green phosphor is Zn _1-x Cd _x Se (where 0 <x
≦ 1), and the crystal constituting the blue phosphor is Zn
The lighting device according to claim 13, wherein the lighting device is made of Se.