JP2006278458A - LIGHT EMITTING ELEMENT, ITS MANUFACTURING METHOD, AND LIGHTING DEVICE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safe light-emitting element having a simple and inexpensive configuration and utilizing a laser oscillation state with extremely high electro-optical conversion efficiency and preventing leakage of laser light to the outside.
A light emitting device includes an active layer (104) that generates stimulated emission light by current injection, and an optical resonator that confines stimulated emission light by a pair of reflecting mirrors (109, 110) facing each other. At least one of the reflecting mirrors (109) includes a phosphor that absorbs stimulated emission light and emits visible light.
[Selection] Figure 1

Description

  The present invention relates to a light emitting element, a method for manufacturing the same, and an improvement of a lighting device using the light emitting element.

  In recent years, instead of conventional illumination devices such as incandescent bulbs and fluorescent lamps, illumination devices using semiconductor light emitting elements and phosphors have been developed. As an example of a semiconductor light emitting device, a light emitting diode including a light emitting layer of a III-V compound semiconductor can be cited, and an element that emits light from red to blue or white has been put into practical use. A lighting device using a light-emitting diode is small and inexpensive, has low power consumption, has a long lifetime, and has characteristics that are not found in conventional lighting devices. On the other hand, since lighting devices using light emitting diodes cannot have as large light output as incandescent bulbs and fluorescent lamps, they are currently mainly used as display backlights, illuminations, indicators, etc. Yes.

As a semiconductor light emitting device, an illumination device using a semiconductor laser made of a III-V compound semiconductor has been devised. Japanese Patent Application Laid-Open No. 7-282609 of Patent Document 1 includes a semiconductor laser element, a lens that diffuses laser light from the element, and a phosphor that converts the diffused laser light from the element into visible light as excitation light. A lighting device is disclosed. Patent Document 1 discloses a configuration in which white illumination is obtained by superimposing the output lights of three color semiconductor lasers of red, green, and blue. When a semiconductor laser is used as a light source, it is expected that the electro-optical conversion efficiency is extremely high as compared with a light emitting diode, and that a large increase in output is possible.
JP-A-7-282609

  Although an illumination device using a semiconductor laser has an advantage that the electro-optical conversion efficiency is extremely high and high output is possible, there is a problem that the configuration is complicated as compared with a light emitting diode. Since the output light of the semiconductor laser has high directivity and is radiated at a high density in one direction, an optical system for adjusting the spread of light like the diffusion lens and collimator lens disclosed in Patent Document 1 Is required. Even when a lens system is used, the large spontaneous emission component seen when operating a semiconductor laser at a high output is not coupled to the lens, resulting in increased coupling loss with the lens or external stray light. The problem of coming out in can also arise.

  Further, according to the study of the present inventor, when a semiconductor laser is used as an excitation light source for a phosphor, the light intensity of the light source is very strong. It has been found that safety problems can arise. In order to prevent this, it is effective to increase the degree of scattering of the laser light or increase the density of the fluorescent material, but in any case, the amount of fluorescence that can be extracted to the outside is significantly reduced. . If the laser oscillation wavelength shifts due to changes in the ambient temperature even if the degree of absorption by the scattering / phosphor is adjusted so that excitation light does not come out, the absorption line of the phosphor and the laser oscillation In this case, the laser beam may come out as it is.

  In view of the above-described problems, an object of the present invention is to provide a safe light emission that has a simple and inexpensive configuration and does not leak laser light to the outside while utilizing a laser oscillation state with extremely high electro-optical conversion efficiency. It is to provide an element. And such a light emitting element can be preferably utilized as a light source of an illuminating device.

  A light emitting device according to the present invention includes an active layer that generates stimulated emission light by current injection, and an optical resonator that confines stimulated emission light by a pair of reflecting mirrors facing each other, and includes at least one of the pair of reflecting mirrors. The reflecting mirror includes a phosphor that absorbs stimulated emission light and emits visible light.

  The optical resonator may be a Fabry-Perot type, and it is preferable that at least a reflecting mirror on the front end surface includes a phosphor. The reflecting mirror may be of a distributed reflection type, and at least the reflecting mirror on the front end face preferably has a periodic structure of a semiconductor and a phosphor-containing material.

  Further, it is preferable that the reflectance and absorption of the reflecting mirror are set so that the stimulated emission light generated from the active layer is not emitted to the outside from the reflecting mirror including the phosphor. It is also preferable that the reflectance of the reflecting mirror is set so that the stimulated emission light generated from the active layer is not emitted to the outside from the reflecting mirror on the rear end face. The rear end reflector may be formed of a metal coating. The metal coating can be formed of aluminum or silver.

  The optical resonator may be a vertical resonator. In this case, it is preferable that a phosphor is included in at least the reflecting mirror on the upper end surface.

  The reflecting mirror may be of a distributed reflection type, and the Bragg wavelength is preferably substantially matched to the absorption line of the phosphor.

  The structure in the active layer and the optical resonator can be formed of a double heterostructure including an AlGaInN material, and the wavelength of stimulated emission light is preferably in the range of 380 nm to 420 nm. The phosphor preferably absorbs stimulated emission light and emits white fluorescence.

  The light-emitting element includes p-type and n-type ohmic electrodes, and these electrodes are preferably made of a metal material that reflects visible light.

  The light emitting element can include a plurality of light emitting points arranged in an array. The light emitting element can also include a plurality of light emitting points arranged in a matrix.

  A method for manufacturing a light emitting device according to the present invention includes a step of forming a semiconductor double hetero stacked structure, a step of periodically performing vertical slit-shaped etching on a part of the stacked structure, and a phosphor-containing substance in the slit portion. And a step of filling. The double hetero stacked structure can be formed of AlGaInN material.

  A preferable lighting device can be obtained by using the light emitting element as described above.

  According to the present invention as described above, it is possible to obtain a light-emitting element that emits visible light fluorescence with high intensity and extremely high electro-optical conversion efficiency. The light-emitting element according to the present invention is safe because it does not leak the light that excites the phosphor to the outside, and can be manufactured in a small and inexpensive manner without alignment. Furthermore, in the light emitting device according to the present invention, linear light emission or planar light emission can be easily obtained. And by using the light emitting element by this invention, the illuminating device with very high electro-optical conversion efficiency can be comprised.

Example 1
In the schematic cross-sectional view of FIG. 1, a light-emitting device according to Example 1 of the present invention is illustrated. In the light emitting device 100, an n-type GaN buffer layer 102 having a thickness of 2 μm, an n-type Al _0.06 Ga _0.94 N lower cladding layer 103 having a thickness of 2 μm, an undoped GaN / InGaN triple quantum well activity on an n-type GaN substrate 101. A layer 104, a p-type Al _0.04 Ga _0.96 N upper cladding layer 105 having a thickness of 1 μm, and a p-type GaN contact layer 106 having a thickness of 0.1 μm are sequentially stacked.

  Although not shown in the cross-sectional view of FIG. 1, the light emitting element 100 includes a current confinement structure, that is, includes a ridge-type waveguide having a wide ridge width (10 μm). The resonator length can be 2 mm. A multilayer reflective film 109 for the front end face is formed on the front end face of the resonator, and a multilayer reflective film 110 for the rear end face is formed on the rear end face thereof. Furthermore, a p-type ohmic electrode 107 is formed on the p-type GaN contact layer 106, and an n-type ohmic electrode 108 is formed on the lower surface of the n-type GaN substrate 101.

The feature of the light-emitting element 1 of Example 1 is the coating film on the cleavage end face. That is, a multilayer reflective film having an extremely high reflectance is applied as the reflective film 109 on the front end surface, which is a silicon oxide (SiO ₂ ) film having a thickness of λ / 4 (λ: resonance wavelength) and a thickness of λ / 4. 15 pairs of titanium oxide (TiO ₂ ) film pairs are included. Here, each of the SiO ₂ film and the TiO ₂ film has red (Y ₂ O ₂ S: Eu ³⁺ ), green (ZnS: Cu, Al), and blue {(Sr, Ca, Ba, Mg) ₁₀ A phosphor emitting fluorescence of (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ } is dispersed. The reflection film 110 on the rear end face is provided with a reflection mirror having an extremely high reflectivity, and includes a SiO ₂ film having a thickness of λ / 4 and an aluminum film sequentially laminated on the cleavage plane.

  The light emitting device of FIG. 1 is mounted on a copper heat sink by junction-up and sealed in a package with a cap made of transparent resin. When current is passed through the upper and lower electrodes 107 and 108 to the light emitting device 100, red, green, and blue fluorescence is emitted from the phosphor dispersed in the reflection film 109 on the front end face, and these fluorescences are emitted. As a result, white light emission 111 is obtained.

  The schematic graph of FIG. 2 shows the relationship between the intensity of white light emission (vertical axis) and the injection current (horizontal axis) in the light emitting element 100. As shown in this graph, the fluorescence intensity suddenly increases at a current of 20 mA or more, and strong white fluorescence is emitted with this current value as a threshold current.

  In the light emitting device 100, light having a wavelength of 405 nm is generated from the multiple quantum well active layer 104 by the current injected through the upper and lower electrodes 107 and 108. The emitted light having a wavelength of 405 nm is amplified with stimulated emission in a Fabry-Perot resonator formed by both cleavage end faces, and reaches a laser oscillation state. Since the multilayer reflective films 109 and 110 having extremely high reflectivity are provided on both end faces, the laser light is hardly emitted to the outside and is confined in the resonator. On the other hand, the reflective film 109 on the front end surface contains a plurality of types of phosphors, and part of the stimulated emission light having a wavelength of 405 nm in the resonator that has entered the laser oscillation state is absorbed by these phosphors. Then, the fluorescence from these phosphors is mixed and emitted as white fluorescence 111.

  In the light emitting element 100, light having a wavelength of 405 nm in a laser oscillation state is used as excitation light for the phosphor, so that the electro-optical conversion efficiency is extremely higher than that of the light emitting diode. Further, the excitation light density in the Fabry-Perot resonator in the laser oscillation state is extremely high, and there is almost no loss other than absorption by the phosphor-containing layer 109. Therefore, the obtained white fluorescence 111 also emits light with very high efficiency and very strong intensity.

  Further, the light having a wavelength of 405 nm, which is excitation light, is confined in the Fabry-Perot resonator between the front and rear end faces, and therefore hardly leaks to the outside. Even if it is a multilayer reflective film, it is difficult to obtain 100% reflectivity completely, but phosphor is dispersed in the multilayer reflective film 109 on the front end surface and absorbs part of the stimulated emission light having a wavelength of 405 nm. To do. The stimulated emission light having a wavelength of 405 nm is set so as not to leak to the outside from the front end face due to the effect of absorption and the effect of high reflectance by the multilayer film.

  Furthermore, since the laser oscillation mechanism and the phosphor portion 109 are integrated, an optical system for diffusing or reflecting the laser light as in Patent Document 1 is unnecessary, and the light emitting element 100 is small and inexpensive and alignment free. Can be manufactured.

The rear end reflecting mirror 110 in the first embodiment is a complete reflecting mirror including an aluminum film. However, if an aluminum film is provided directly on the cleavage end face, the upper and lower electrodes 107 and 108 are electrically short-circuited. Therefore, a SiO ₂ film having a thickness of λ / 2 is provided between the cleaved end face and the aluminum film for insulation. Here, as the metal used for the reflecting mirror 110 on the rear end face, it is preferable to use aluminum or silver having a high reflectance with respect to blue light or ultraviolet light. Further, it goes without saying that a dielectric multilayer structure having a sufficiently high reflectivity may be used as the reflecting mirror on the rear end face as in the case of the front end face.

  Although FIG. 1 shows a state in which the fluorescence 111 from the phosphor included in the front mirror unit 109 is emitted to the outside, the fluorescence can be emitted not only to the outside but also to the inside of the element. Therefore, by using a metal material that reflects visible light in the upper and lower electrodes 107 and 108 and the reflective film 110 on the rear end face, it is possible to prevent the fluorescence emitted into the element from being lost. Similarly, the side wall surface of the light emitting element 100 can be configured to reflect visible light. Furthermore, it goes without saying that various known configurations can be introduced in order to efficiently extract the fluorescence emitted into the device to the outside.

(Example 2)
In the schematic cross-sectional view of FIG. 3, a light-emitting device according to Example 2 of the present invention is shown. The light emitting element 200 includes a plurality of layers 201 to 208 corresponding to the plurality of layers 101 to 108 in FIG.

However, in the first embodiment, the front end mirror is formed by cleavage and multilayer coating, whereas in the second embodiment, the semiconductor 211 and the phosphor 212 are alternately arranged over 10 cycles, which is extremely high. The difference is that a DBR (distributed Bragg reflector) mirror 209 of reflectivity is provided. As the phosphor 212, red (Y ₂ O ₂ S: Eu ³⁺ ), green (ZnS: Cu, Al), and blue {(Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ } can be used, and these phosphors absorb light having a wavelength of 405 nm and emit fluorescence. However, the phosphor 212 here may of course be the phosphor itself, but may be a resin, glass, or dielectric containing the phosphor.

  Although the current confinement structure is not shown in the cross-sectional view of FIG. 3, a ridge structure similar to that in the first embodiment can also be adopted in the second embodiment. The resonator length of the light emitting element 200 can be set to 3 mm, for example. The light-emitting element of FIG. 3 is mounted on a copper heat sink by junction-up, and is enclosed in a package with a cap made of transparent resin. When current is passed from the upper and lower electrodes 207 and 208 to the light emitting element 200, strong white fluorescence 213 is emitted from the front end face.

  The principle that the light emitting element 200 emits white light is the same as in the first embodiment. That is, stimulated emission light having a wavelength of 405 nm is emitted from the multiple quantum well active layer 204 by the injected current, and a part of the emission light is absorbed by the phosphor 212 included in the reflection film 209 on the front end face in the laser oscillation state. White fluorescence 213 is emitted. The excitation light for the phosphor 212 is in a laser oscillation state with a high light density, and the stimulated emission light is not lost except for absorption by the phosphor 212 in the reflection film 209, so that high electro-optical conversion efficiency and Very strong white fluorescence is obtained. In addition, light having a wavelength of 405 nm that serves as excitation light for the phosphor does not leak outside the device, and the light emitting device 200 can be manufactured in a small size and at low cost without alignment. Further, in the second embodiment, as the front end face structure 209, a DBR mirror structure using a pair of a semiconductor 211 and a phosphor 212 having a large refractive index difference (the rear end face structure 210 is a semiconductor / air layer pair) is employed. Therefore, the reflectance can be almost 100%.

  The semiconductor / phosphor structure 209 on the front end face portion can be manufactured by a process as shown in the schematic cross-sectional view of FIG. 4, (a) formation of a double hetero semiconductor stacked structure 201-206, (b) formation of Mo mask 214 using Mo deposition and photolithography, and (c) selective dry etching of the semiconductor stacked structure. And (d) removal of the Mo mask and filling of the phosphor 212 into the plurality of slits on the front end face DBR. By using such a method, it is possible to easily manufacture an end face reflecting mirror filled with a phosphor at a high concentration on the front end face. In this case, the cleavage step is not necessary, and the light emitting element 200 can be formed monolithically.

  In Example 1, since the phosphor is dispersed in the dielectric end face coating film, the density of the phosphor cannot be increased so much. In Example 2, however, the phosphor is densely inserted into the slit formed by dry etching. It can be filled and stronger fluorescence is obtained. Further, when the end face is a DBR mirror, the stimulated emission light can be efficiently absorbed by the phosphor by matching the Bragg wavelength with the absorption line of the phosphor. Furthermore, the wavelength change of the stimulated emission light due to the temperature change of the light emitting element 200 can be reduced, and stable white fluorescence can be obtained even when the environmental temperature changes.

  In the example of FIGS. 3 and 4, the case where a plurality of types of phosphors emitting blue, green, and red light are mixed and filled in the slit as the phosphor 212 has been described. As shown in the sectional view, it goes without saying that the phosphor 215 that emits red light, the phosphor 216 that emits green light, and the phosphor 217 that emits blue light may be separated and filled into different slits. This is the same in other embodiments. In FIG. 5, two slits are prepared for each color phosphor and phosphors are embedded in a total of six slits, but the number of slits for embedding phosphors can be arbitrarily set. Further, a distribution ratio of the number of slits provided for each color may be assigned in accordance with the luminous efficiency of the phosphors of each color.

  Further, in the second embodiment, an example in which the DBR mirror 210 having a multilayer structure of a semiconductor and air is provided on the rear end face has been described. However, as in the first embodiment, a complete reflecting mirror made of a metal film such as aluminum is provided. Needless to say.

(Example 3)
In the schematic perspective view of FIG. 6, the light emitting element by Example 3 of this invention is shown. The stacked body 301 in the light emitting element 300 includes a plurality of layers corresponding to the plurality of layers 101 to 108 in FIG. 1, that is, includes a semiconductor double heterostructure. FIG. 6 shows a plurality of ridge portions 302 and a plurality of current confinement layers 303 with respect to the current confinement structure. Those current confinement layers 303 can be easily formed of polyimide, for example.

  In the light emitting device 300 of the third embodiment, similar to the second embodiment, a DBR mirror 304 having an extremely high reflectance is provided by a structure in which semiconductor layers and phosphor layers are alternately arranged on the front end surface thereof. The rear end face is provided with a DBR mirror 305 having a very high reflectance with a structure in which semiconductor layers and air layers are alternately arranged. As shown in FIG. 6, a plurality of ridges (six in FIG. 6) having a width a3 of 5 .mu.m are arranged at intervals b3 of 5 .mu.m. That is, the light emitting element 300 is an array type light emitting element. The phosphor filled in the mirror portion 304 on the front end surface can be the same as that in the second embodiment. The resonator length of the light emitting element 300 can be set to 3 mm, for example. The light-emitting element of FIG. 6 is mounted on a copper heat sink by junction-up, and is enclosed in a package with a cap made of transparent resin. When current is passed from the upper and lower electrodes to the light emitting element 300, extremely strong white fluorescence 306 is emitted from the front end face.

  The principle that the light emitting element 300 emits white light is the same as in the first and second embodiments. On the other hand, in Example 3, since a plurality of ridges are arranged in an array, light is emitted in a wide line in the width direction, and a larger amount of light can be obtained. Note that the number of ridges is not limited, and by increasing the number of ridges, light can be emitted linearly over a wider range.

  In Examples 1-3 above, an example in which the phosphor is dispersed or filled only on the front end face of the light emitting element is shown. However, the phosphor is also arranged on the rear end face, and fluorescence is emitted from both end faces. May be. Further, although an example of a semiconductor laser structure including a wide ridge type waveguide has been shown, the semiconductor laser structure is not limited to the ridge type, and may be an arbitrary structure such as a buried hetero type or an electrode stripe type.

Example 4
In the schematic cross-sectional view of FIG. 7, a light emitting device according to Example 4 of the present invention is shown. FIG. 7 shows a cross section passing through the centers of a cylindrical semiconductor mesa and a donut-shaped upper electrode 409 thereon in order to explain the internal structure of the light emitting element 400. The layer structure of the light emitting element 400 is set based on the design rule of the surface emitting semiconductor laser.

That is, on the n-type GaN substrate 401, each of the multi-layer DBR mirror 402, the GaN light guide layer 403, the GaN / InGaN multiple quantum well active layer 404, and the GaN light guide layer 405 with 28 pairs of n-type AlN / GaN pairs. They are sequentially stacked in a circular shape. A circular SiO ₂ / TiO ₂ multilayer DBR mirror 406 is formed on the GaN light guide layer 405, and a donut-shaped p-type GaN contact layer 407 is formed around it. A doughnut-shaped p-type electrode 409 is formed on the p-type contact layer 407.

  The periphery of the columnar semiconductor mesa and the doughnut-shaped upper electrode 409 formed in this way is embedded with a polyimide embedded layer 408. On the other hand, an n-type electrode 410 is formed on the bottom surface of the n-type GaN substrate 410.

  Here, the upper and lower multilayer DBR mirrors 406 and 402 made of a dielectric film are set so that the reflectance thereof is almost 100%. In the upper multilayer DBR mirror 406, phosphors are dispersed in each dielectric layer. The phosphor in the fourth embodiment may be the same material as in the other embodiments, and absorbs light having a wavelength of 405 nm and emits fluorescence.

  The light emitting element of FIG. 7 is mounted so that its back electrode 410 contacts a heat sink made of copper, and is enclosed in a package with a cap made of transparent resin. In that state, if current is passed from the upper and lower electrodes 409 and 410 to the light emitting element 400, strong white fluorescence 411 is obtained from the upper part of the element.

  The principle that the light emitting element 400 emits white light is the same as in the other embodiments described above. In the fourth embodiment, since the resonator is a vertical resonator similar to the surface emitting laser, the laser can be formed monolithically, and the threshold current at which fluorescence starts to be emitted can be extremely reduced. . Further, by making the Bragg wavelength of the DBR mirror coincide with the absorption spectrum of the phosphor, the stimulated emission light can be efficiently absorbed by the phosphor. Furthermore, since the wavelength change of the stimulated emission light due to the temperature change of the light emitting element 400 can be reduced, stable white fluorescence can be obtained even when the environmental temperature changes.

  7 has been described as including a cylindrical semiconductor mesa, it is needless to say that a prismatic semiconductor mesa may be included. Further, in Examples 1-4 described above, the simplest structure is exemplified as the layer structure of the light-emitting element. For example, a carrier block layer is provided between the active layer and the p-type cladding layer, or the cladding layer is formed in multiple layers. It goes without saying that various modifications such as a structure are possible.

(Example 5)
In Example 5 of the present invention, light emitting elements having vertical resonators similar to the surface emitting laser of FIG. 7 are arranged in a matrix of 5 × 5 at intervals of 10 μm. Thus, a surface-emitting light source that emits white light over a wide area can be obtained.

(Example 6)
In Example 6 of the present invention, the light-emitting elements of FIG. 1 are arranged in a matrix of 25 × 25 × 25 mm intervals. As a result, it is possible to configure a lighting device with extremely high electrical-light conversion efficiency. The light-emitting element according to the present invention can be used for illumination, a backlight of a display, and the like in addition to an illumination device that replaces an incandescent lamp and a fluorescent lamp.

  In the present invention, the phosphor-containing layer is not limited to the phosphor material exemplified in each example and the base material in which the phosphor is dispersed, and can be replaced with any material. Needless to say. Further, the fluorescence that becomes the output light does not necessarily have to be white, and an arbitrary color of fluorescence may be output by an arbitrary phosphor according to the purpose.

  In the above-described embodiment, the phosphor is included only in the multilayer reflector on the front end surface or only the multilayer reflector on the upper surface of the surface emitting type, and the phosphor on the multilayer reflector on the rear end surface or the lower end surface is not included. However, it goes without saying that phosphors may be included in both the front and rear end mirrors or the upper and lower end mirrors.

  The oscillation wavelength of the semiconductor laser used as the excitation light source is not necessarily 405 nm and may be adjusted according to the absorption line of the phosphor. The laser oscillation wavelength may be adjusted to the phosphor absorption line having a shorter wavelength than the fluorescence wavelength emitted from the phosphor, but as a result of considering the light emission efficiency and the conversion efficiency to visible light, the AlGaInN-based material It is preferable to use a laser oscillation state with a wavelength of 380 nm to 420 nm.

  In the semiconductor laser device of the present invention, the nitride compound semiconductor mixed crystal used in each semiconductor layer is a group III element (such as boron) or a group V element (arsenic, phosphorus, etc.) other than those exemplified in the examples. (Such as bismuth) may be mixed as appropriate, and impurity elements (Zn, Be, Mg, Te, S, Se, Si, etc.) may be included as appropriate. Further, the substrate of the light emitting element is not limited to those exemplified in the embodiments, and the effects of the present invention can be obtained even when other substrates are used. For example, a single crystal substrate such as a sapphire substrate, a silicon carbide substrate, a silicon substrate, or a gallium arsenide substrate can be used. Needless to say, when these substrates are produced by crystal growth, they can be produced by any known crystal growth method using any known raw material. In addition, regarding the quantum well structure of the active layer in the above embodiments, there are no particular limitations on the number of well layers, the amount of strain, the thickness of the well layer, and the like. For example, a compressive or tensile strain may be introduced into the barrier layer included in the quantum well structure.

  As described above, according to the present invention, it is possible to provide a light emitting element that emits visible light fluorescence with high intensity and extremely high electro-optical conversion efficiency. The light-emitting element of the present invention is safe because it does not leak the light that excites the phosphor to the outside, and can be manufactured in a small, inexpensive and alignment-free manner. In addition, according to the present invention, it is possible to easily provide a light emitting element capable of linear light emission or planar light emission. And by using the light emitting element of this invention, the illuminating device with very high electro-optical conversion efficiency can be provided.

It is sectional drawing which shows typically the light emitting element by one Example of this invention. 2 is a schematic graph showing the relationship between the fluorescence intensity and the injection current of the light emitting device of FIG. 1. It is sectional drawing which shows typically the light emitting element by the other Example of this invention. FIG. 4 is a cross-sectional view schematically showing a manufacturing process of the light emitting element of FIG. 3. It is sectional drawing which shows typically the front-end surface part of the light emitting element by the other Example of this invention. It is a perspective view which shows typically the light emitting element by the other Example of this invention. It is sectional drawing which shows typically the light emitting element by the other Example of this invention.

Explanation of symbols

100, 200, 300, 400 Light emitting device, 101, 201, 401 Substrate, 102, 202 n-type buffer layer, 103, 203 n-type lower cladding layer, 104, 204, 404 Undoped multiple quantum well active layer, 105, 205 p Cladding layer on mold, 106, 206 p-type contact layer, 107, 108, 207, 208, 409, 410 electrode, 109, 209, 304 Multi-layer reflective structure for front end surface, 110, 210, 305 Multi-layer reflective structure for rear end surface, 111, 213, 306, 411 White fluorescent light, 211 Semiconductor layer, 212, 215, 216, 217 Phosphor, 214 Etching mask, 301 Double heterostructure with semiconductor stack, 302 Ridge part, 303, 408 Current constriction part, 402 Lower multilayer Reflector, 403, 405 Light guide layer, 406 Upper multilayer reflector, 407 contact layer.

Claims (17)

An active layer that generates stimulated emission light by current injection;
An optical resonator for confining the stimulated emission light by a pair of reflecting mirrors facing each other;
At least one of the pair of reflecting mirrors includes a phosphor that absorbs stimulated emission light and emits visible light.   2. The light emitting device according to claim 1, wherein the optical resonator is a Fabry-Perot type, and at least the reflecting mirror on the front end surface includes a phosphor.   2. The light emitting device according to claim 1, wherein the reflecting mirror is a distributed reflection type, and at least the reflecting mirror on the front end surface has a periodic structure of a semiconductor and a phosphor-containing material.   4. The reflectivity and absorption of the reflecting mirror are set so that the stimulated emission light generated from the active layer is not emitted to the outside from the reflecting mirror including the phosphor. A light emitting device according to any one of the above.   The reflectivity of the reflecting mirror is set so that the stimulated emission light generated from the active layer is not emitted to the outside from the reflecting mirror on the rear surface. Light emitting element.   6. The light emitting device according to claim 5, wherein the reflecting mirror on the rear surface is metal-coated.   The light emitting device according to claim 6, wherein the metal coating is made of aluminum or silver.   The light emitting device according to claim 1, wherein the optical resonator is a vertical resonator, and a phosphor is included in at least an upper reflecting mirror.   9. The light emitting device according to claim 3, wherein the reflecting mirror is a distributed reflection type, and a Bragg wavelength thereof is substantially matched with an absorption line of the phosphor.   The structure of the active layer and the optical resonator is a double heterostructure including an AlGaInN material, and the wavelength of the stimulated emission light is in the range of 380 nm to 420 nm. The light emitting element as described in.   The light emitting device according to claim 10, wherein the phosphor emits white fluorescence by absorbing the stimulated emission light.   The light-emitting element according to claim 1, wherein the light-emitting element further includes ohmic electrodes for p-type and n-type, and the electrode is made of a metal material that reflects visible light.   The light emitting element according to claim 1, comprising a plurality of light emitting points arranged in an array.   The light emitting device according to claim 1, comprising a plurality of light emitting points arranged in a matrix.   A step of forming a semiconductor double hetero layered structure, a step of performing periodic slit-like vertical etching on a part of the layered structure, and a step of filling the slit part with a phosphor-containing substance. A method for manufacturing a light emitting device.   The manufacturing method according to claim 15, wherein the double hetero stacked structure is formed of an AlGaInN material.   An illumination device comprising the light emitting element according to claim 1.

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