JP2006270073A - Light-emitting diode and method of manufacturing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-luminance light-emitting diode which reduces the emission of infrared light in a distributed Bragg reflector to a negligible level and further reduces the absorptivity of light in the distributed Bragg reflector. <P>SOLUTION: A combination of an AlGaAs layer and an AlInP layer is used for the distributed Bragg reflector in an AlGaInP light-emitting diode. The thicknesses of the layers are set as expressed in the following equations: equation (1) (the thickness of the AlGaAs layer [nm])=äλ<SB>0</SB>/(4×n<SB>1</SB>)}×α, equation (2) (the thickness of the AlInP layer [nm])=äλ<SB>0</SB>/(4×n<SB>2</SB>)}×(2-α) (λ<SB>0</SB>represents the wavelength [nm] of light to be reflected, n<SB>1</SB>represents the index of refraction of the AlGaAs layer relative to the wavelength of light to be reflected, and n<SB>2</SB>represents the index of refraction of the AlInP layer relative to the wavelength of light to be reflected), equation (3): 0.5<α<0.9. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high-intensity light-emitting diode in which near-infrared light emission in a distributed Bragg reflector is reduced to a negligible level and malfunction of optical sensors using infrared light is prevented, and a method for manufacturing the same It is about.

  Recently, the demand for high-brightness red to green light-emitting diodes manufactured using AlGaInP-based epitaxial wafers has greatly increased. Main demands are LCD backlights for mobile phones, indicator lights, traffic signal lights, and automobile brake lamps. AlGaInP is a direct transition type semiconductor having the largest band gap among III / V group compound semiconductors excluding nitride, and is compared with a conventional light emitting diode using an indirect transition type semiconductor such as GaP or AlGaAs. High-luminance light emission is possible in the visible wavelength range corresponding to red to green. In addition, the internal quantum efficiency of high-brightness light-emitting diodes that are generally manufactured and sold is extremely high, and in order to achieve higher brightness than before, it is necessary to improve external quantum efficiency rather than improving internal quantum efficiency. As an effective method, there is a light emitting diode having a structure in which a distributed Bragg reflector (DBR) is inserted.

  As a conventional example, FIG. 6 shows the structure of an AlGaInP light emitting diode (see Patent Document 1) having an emission wavelength of 630 nm.

  As shown in FIG. 6, this AlGaInP-based light-emitting diode has a high refractive index film and a low refractive index film formed on an n-type GaAs substrate 22 by metal organic vapor phase epitaxy (hereinafter referred to as “MOVPE method”). A distributed Bragg reflector (DBR) 23 comprising a multilayer film in which layers are alternately stacked, an n-type AlGaInP lower cladding layer 24, an undoped AlGaInP active layer 25, a p-type AlGaInP upper cladding layer 26, and a p-type GaP current diffusion layer 27 are sequentially stacked. The back electrode (n-side common electrode) 21 is provided on the entire back surface of the n-type GaAs substrate 22, and the surface electrode (p-side ohmic contact electrode) 28 is provided on a part of the surface of the p-type current spreading layer 27. Yes. 24 to 26 form an AlGaInP quaternary double heterostructure part (light emitting part).

Distributed Bragg reflector 23, the emission wavelength of the LED lambda, the refractive index is n, alternately laminated lambda / 4n _b membranes lambda / 4n _a film and a low refractive index film of the high refractive index film multilayer It is composed of a film and has a function of improving light extraction efficiency by reflecting light traveling downward (toward the GaAs substrate) from light generated from the active layer upward (toward the light extraction surface). With this effect, it is possible to realize a luminance improvement of 50% or more (in some cases, about 100%) as compared with the case where it is not provided.

In an LED having an AlGaInP mixed crystal as a light emitting layer, the material constituting the distributed Bragg reflector 23 is generally a combination of a GaAs layer and an Al _x Ga _1-x As (0 ≦ x ≦ 1) layer, a GaAs layer, Combinations of Al _x Ga _1-x ) _1-y In _y P (0 ≦ x, y ≦ 1) layers and the like are used. Further, as a material constituting the Bragg reflector 23, a combination of an AlAs layer and an AlGaAs layer having a large refractive index difference and a high reflectance is known.

  On the other hand, in the case of Patent Document 1, a distributed Bragg reflector composed of a combination of a GaAs layer and an AlInP layer is used. The reason for this is that, in the distributed Bragg reflector composed of a combination of the AlAs layer and the AlGaAs layer, the AlAs layer preparation conditions are very difficult, oxygen (O) is easily mixed, and the crystallinity of the light emitting layer grown thereon If the method of increasing the supply ratio of the group V raw material and the group III raw material, the so-called V / III ratio, is used in order to prevent the mixing of oxygen. This is because there is a problem that a large load is applied and the exhaust pipe is easily blocked by As waste.

  Therefore, in the case of Patent Document 1, in a distributed Bragg reflector using a combination of a GaAs layer and an AlInP layer, the light absorbed by the GaAs layer is reduced and the reflectance is made higher. Therefore, the GaAs layer is made as thin as possible, and AlInP It has been proposed that the layer be made thick so that it can reflect light of the desired wavelength.

  The film thicknesses of the GaAs layer and the AlInP layer necessary for producing this highly reflective distributed Bragg reflector can be obtained by the following equation.

(Film thickness of GaAs layer [nm]) = {λ ₀ / (4 × n _a )} × α
(AlInP layer thickness [nm]) = {λ ₀ / (4 × n _b )} × (2-α)
λ ₀ : wavelength of light to be reflected [nm]
n _a : refractive index of the GaAs layer with respect to the wavelength of light to be reflected n _b : refractive index of the AlInP layer with respect to the wavelength of light to be reflected 0.5 <α <0.9
A distributed Bragg reflector is produced by alternately combining the GaAs layers and AlInP layers thus obtained several tens of times.

In addition to the above, a material using AlGaAs for both the high refractive index film and the low refractive index film is known as a material constituting the distributed Bragg reflector 23 (see, for example, Patent Document 2).
JP 2003-218386 A JP 2000-174332 A

  However, the LED using the distributed Bragg reflector composed of a combination of the AlInP layer and the GaAs layer in Patent Document 1 has a big problem. It is not only that the light of the wavelength (630 nm) emitted from the active layer is generated as the main light (LED emission) as shown in FIG. 7, but also the light from the active layer toward the distributed Bragg reflector. This is a problem that near infrared light (emission wavelength: 860 nm) is emitted, and the near infrared light is emitted to the outside together with the main light emitted from the active layer with an intensity that cannot be ignored.

  The intensity of near-infrared light (emission wavelength 860 nm) is about 1/10 of the main light (emission wavelength 630 nm). This near-infrared light may cause a malfunction to a sensor using infrared light that is widely used in the world.

  In the distributed Bragg reflector composed of a combination of an AlInP layer and a GaAs layer in Patent Document 1, a part of light is absorbed without being reflected by the GaAs layer, resulting in a darkness.

  Accordingly, an object of the present invention is to reduce the near-infrared light emission in the distributed Bragg reflector to a level that can be ignored, and further to provide a high-intensity light-emitting diode in which the light absorptance in the distributed Bragg reflector is lowered and It is in providing the manufacturing method.

  In order to achieve the above object, the present invention is configured as follows.

  According to a first aspect of the present invention, a light emitting diode is formed on a first conductivity type substrate by forming a light emitting portion sandwiching an active layer between a first conductivity type lower cladding layer and a second conductivity type upper cladding layer. In a light emitting diode having a structure in which a distributed Bragg reflector of the first conductivity type composed of a multilayer film in which a high refractive index film and a low refractive index film are alternately laminated is inserted between an undermold cladding layer and a substrate, the above distributed Bragg An AlGaAs layer and an AlInP layer are used as materials for the high refractive index film and the low refractive index film constituting the reflector.

  According to a second aspect of the present invention, there is provided a light emitting diode comprising: a light emitting portion having an active layer sandwiched between a first conductive type lower cladding layer and a second conductive type upper cladding layer on a first conductive type substrate; A first conductivity type distributed Bragg consisting of a multilayer film in which a second conductivity type current spreading layer is formed and a high refractive index film and a low refractive index film are alternately laminated between the first conductivity type lower cladding layer and the substrate. In a light emitting diode having a structure in which a reflector is inserted, an AlGaAs layer and an AlInP layer are used as materials of the high refractive index film and the low refractive index film constituting the distributed Bragg reflector.

The invention of claim 3 is the light-emitting diode according to claim 1 or 2, wherein the film thicknesses of the AlGaAs layer and the AlInP layer used in the distributed Bragg reflector are expressed by the following equations (1), (2), and (3). AlGaAs layer thickness [nm]) = {λ ₀ / (4 × n ₁ )} × α (1)
(AlInP layer thickness [nm]) = {λ ₀ / (4 × n ₂ )} × (2-α) (2)
λ ₀ : wavelength of light to be reflected [nm]
n ₁ : Refractive index of the AlGaAs layer with respect to the wavelength of the light to be reflected n ₂ : Refractive index of the AlInP layer with respect to the wavelength of the light to be reflected 0.5 <α <0.9 (3)
It is characterized by that.

According to a fourth aspect of the present invention, in the light emitting diode according to any one of the first to third aspects, when the material of the high refractive index film is displayed as a general formula Al _x Ga _1-x As layer, the Al mixed crystal ratio x is 0 <x <0.6.

  According to a fifth aspect of the present invention, in the light-emitting diode according to any one of the first to fourth aspects, the substrate is made of GaAs and the light-emitting portion is formed of AlGaInP or GaInP.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a light emitting diode comprising a distributed Bragg by alternately growing a first conductivity type AlGaAs layer and a first conductivity type AlInP layer on a first conductivity type GaAs substrate by a MOVPE method. A reflector is formed, and a first conductivity type AlGaInP clad layer, an undoped AlGaInP active layer, a second conductivity type AlGaInP clad layer, and a second conductivity type AlGaInP current spreading layer are sequentially grown on the reflector. The film thicknesses of the AlGaAs layer and the AlInP layer used in the distributed Bragg reflector are expressed by the following equations (1), (2) and (3) (film thickness [nm] of the AlGaAs layer) = {λ ₀ / (4 × n ₁ )} × α (1)
(AlInP layer thickness [nm]) = {λ ₀ / (4 × n ₂ )} × (2-α) (2)
λ ₀ : wavelength of light to be reflected [nm]
n ₁ : Refractive index of the AlGaAs layer with respect to the wavelength of the light to be reflected n ₂ : Refractive index of the AlInP layer with respect to the wavelength of the light to be reflected 0.5 <α <0.9 (3)
It is characterized by.

<Key points of the invention>
In addition to the main light in the wavelength region corresponding to the band gap of the active layer (emission wavelength 630 nm) (hereinafter referred to as the first radiation), a major problem with the AlInP, GaAs pair distributed Bragg reflector of Patent Document 1 This is to simultaneously emit light in a wavelength region corresponding to the band gap of GaAs, that is, strong near-infrared light (860 nm) (second emitted light) (see FIG. 7). At the same time, the cause of emitting strong near-infrared light (second emitted light) is directed toward the n-type GaAs substrate 22 and the n-type distributed Bragg reflector 23 in the light emitted from the active layer 25 in FIG. Most of the light is reflected by the n-type distributed Bragg reflector 23 to the main light extraction surface on the opposite side. However, a part of the first radiation enters the GaAs layers of AlInP and GaAs constituting the n-type distributed Bragg reflector 23. This is because the first radiant light entering the GaAs layer is photoexcited to emit light corresponding to the band gap of the GaAs layer. That is, a light emitting diode using a GaAs layer for one of the pair of n-type distributed Bragg reflectors 23 inevitably emits strong second radiation. Therefore, when a sensor using infrared light, for example, a general semiconductor photodiode is present around such a light emitting diode, the near infrared light emitted from the light emitting diode ( In response to the second synchrotron radiation, there was a problem of malfunction.

  Therefore, in the present invention (claims 1 and 2), an AlGaAs layer and an AlInP layer are used as materials of the high refractive index film and the low refractive index film constituting the distributed Bragg reflector. That is, an AlGaAs layer is used as the high refractive index film instead of the conventional GaAs layer. Thereby, in this invention, the near-infrared light from a distributed Bragg reflector is reduced to the level which can be disregarded as shown in FIG. Therefore, in the case of the light emitting diode of the present invention, even if there is a sensor using infrared light around it, it reacts to near infrared light (second emitted light) emitted from the light emitting diode. And no malfunction occurs.

  In the present invention (claims 3 to 5), among the pair films constituting the distributed Bragg reflector, one of the AlGaAs layers that absorbs light is made as thin as possible and the other AlInP layer is reflected. Since it is formed thick so as to reflect light having a wavelength, a light-emitting diode with high luminance can be obtained.

  Further, in the present invention (claims 1 to 6), it is possible to obtain a light-emitting diode with higher brightness as compared with a conventional light-emitting diode only by changing the film thickness of the AlGaAs layer and the AlInP layer of the distributed Bragg reflector. .

  In a general distributed Bragg reflector composed of a combination of an AlAs layer and an AlGaAs layer, the fabrication conditions of the AlAs layer are very difficult, oxygen (O) is easily mixed, and the crystallinity of the light-emitting layer grown thereon is remarkably increased. Deteriorates and causes a decrease in brightness. Further, if a method of increasing the supply ratio of the Group V raw material and the Group III raw material, that is, the so-called V / III ratio, is used to prevent oxygen contamination, the manufacturing apparatus is heavily loaded, and the exhaust pipe is easily clogged with As debris. There is a problem to say. However, in the present invention (Claims 1 to 6), a distributed Bragg reflector comprising a combination of an AlGaAs layer and an AlInP layer is used. Therefore, there is no such problem, and a distributed Bragg reflector with higher reflectivity suitable for production. Can be easily produced.

  According to the present invention, the following excellent effects can be obtained.

  In the first and second aspects of the invention, since the AlGaAs layer and the AlInP layer are used as the materials of the high refractive index film and the low refractive index film constituting the distributed Bragg reflector, the near infrared light from the distributed Bragg reflector is ignored. To a possible level. Therefore, even if a general semiconductor photodiode exists around the light emitting diode of the present invention, no malfunction occurs.

  In the inventions of claims 3 to 5, since the light-absorbing AlGaAs layer is made as thin as possible and the AlInP layer is formed thick so as to reflect light having a wavelength desired to be reflected, a high-intensity light-emitting diode is formed. Obtainable.

  According to the first to sixth aspects of the present invention, it is possible to obtain a light-emitting diode with higher brightness as compared with a conventional light-emitting diode by simply changing the film thickness of the AlGaAs layer and the AlInP layer of the distributed Bragg reflector.

  Hereinafter, the present invention will be described based on the illustrated embodiments.

  A structure of a light emitting diode according to an embodiment of the present invention is shown in FIG. Here, the first conductivity type is n-type, and the second conductivity type is p-type. This light emitting diode is an n-type comprising a multilayer film in which an n-type AlGaAs layer of a high refractive index film and an n-type AlInP layer of a low refractive index film are alternately laminated on an n-type GaAs substrate 2 as a first conductivity type substrate. A distributed Bragg reflector 3 is formed. Further thereon, a double heterostructure of an n-type AlGaInP lower cladding layer 4 which is a first conductivity type lower cladding layer, an undoped AlGaInP active layer 5, and a p-type AlGaInP upper cladding layer 6 which is a second conductivity type upper cladding layer. A light emitting portion (light emitting region layer) is formed. An n-type GaAs buffer layer may be provided between the n-type GaAs substrate 2 and the n-type distributed Bragg reflector 3.

  Further, a p-type AlGaInP current spreading layer 7 is formed as a second conductivity type current spreading layer on the above-described light emitting portion, more precisely on the p-type AlGaInP upper cladding layer 6. Furthermore, a surface electrode 8 made of a circular partial electrode is formed at the center of the chip surface, and a back electrode 1 made of an n-side metal electrode is formed on a part or the whole of the back surface.

  The film thicknesses of the AlGaAs layer and the AlInP layer constituting the distributed Bragg reflector 3 are obtained by the following equations (1), (2), and (3).

(AlGaAs layer thickness [nm]) = {λ ₀ / (4 × n ₁ )} × α (1)
(AlInP layer thickness [nm]) = {λ ₀ / (4 × n ₂ )} × (2-α) (2)
λ ₀ : wavelength of light to be reflected [nm]
n ₁ : Refractive index of the AlGaAs layer with respect to the wavelength of the light to be reflected n ₂ : Refractive index of the AlInP layer with respect to the wavelength of the light to be reflected 0.5 <α <0.9 (3)
FIG. 2 shows the relationship between the coefficient α and the spectral area of the distributed Bragg reflector. Compared with a normal distributed Bragg reflector with α = 1 (when the film thickness of the high refractive index film and the low refractive index film is equal to λ / 4n), the range of the coefficient α is 0.5 <α <0. In the case of a distributed Bragg reflector having a. That is, as can be seen from FIG. 2, the coefficient α is in the range of 0.5 <α <0.9, preferably in the range of 0.6 ≦ α ≦ 0.8, and more preferably about 0.7. , Α = 1 (when the film thickness of the high refractive index film and the low refractive index film is equal to λ / 4n), a larger spectral area [a. u. (Arbitrary units)], and therefore a distributed Bragg reflector with high reflectivity can be obtained.

  FIG. 3 shows an emission spectrum of the LED having the distributed Bragg reflector having the above configuration. In the case of a distributed Bragg reflector having a pair of a conventional GaAs layer and an AlInP layer, near-infrared light (FIG. 7) from the GaAs layer was generated at a size about 1/10 of the main peak. In the case of the distributed Bragg reflector 3 in which the AlGaAs layer and the AlInP layer of this embodiment are paired, as shown in FIG. 3, the near-infrared light extracted outside is substantially 1/60 or less of the main peak. To a negligible level. Therefore, even if a general semiconductor photodiode exists around the light emitting diode of the present embodiment, the photodiode does not react to the emitted near infrared light, and malfunction is prevented.

  FIG. 5 shows the relationship between the number of pairs of the GaAs layer and the AlInP layer and the LED luminous intensity. The light intensity increases monotonically from 0 to 15 pairs, but tends to be saturated at 15 to 30 pairs. Therefore, the number of pairs of the GaAs layer and the AlInP layer is preferably 30 pairs or less, and more preferably 15 to 25 pairs.

  More specifically, an embodiment of the light emitting diode (LED) of FIG. 1 will be described.

On the n-type GaAs substrate 2 by the MOVPE method, an n-type AlGaAs layer (film thickness: 30.7 nm, carrier concentration: 1 × 10 ¹⁸ cm ⁻³ ) and a low-refractive index film n-type AlInP layer (film) A distributed Bragg reflector 3 consisting of 20 pairs in which two layers having a thickness of 71.2 nm and a carrier concentration of 1 × 10 ¹⁸ cm ⁻³ ) were alternately grown was grown. Furthermore, an n-type AlGaInP lower cladding layer 4 having a thickness of 0.5 μm and a carrier concentration of 1 × 10 ¹⁸ cm ⁻³ , an undoped AlGaInP active layer 5 having a thickness of 0.5 μm, and a thickness of 0.5 μm. The p-type AlGaInP upper cladding layer 6 having a carrier concentration of 5 × 10 ¹⁷ cm ⁻³ was sequentially grown. Further, a p-type AlGaInP current spreading layer 7 having a thickness of 5 μm and a carrier concentration of 1 × 10 ¹⁸ cm ⁻³ was grown thereon.

  The LED chip of FIG. 1 was manufactured from this epitaxial wafer, and the characteristics were evaluated. Compared with the LED chip having the distributed Bragg reflector when α = 1 in the above formula (when the film thickness of the high refractive index film and the low refractive index film is equal to λ / 4n), the light emission output is about 15%. The operating voltage (Vf characteristics) of the device remained unchanged at 1.9 V. That is, the same good results as in Patent Document 1 were maintained for the characteristics of the light emission output and the operating voltage.

  On the other hand, the intensity of near infrared light extracted from the light emitting diode, which is an important point of the present invention, is reduced to a negligible level as shown in FIG. No longer reacts when present.

  In the above embodiment, the structure of the light emitting diode having the current spreading layer 7 has been described. However, the present invention is not limited to this, and the present invention is also applicable to the structure of the light emitting diode in which the current spreading layer 7 is omitted from FIG. be able to. That is, as shown in FIG. 4, an n-type AlGaAs layer of a high refractive index film and an n-type AlInP layer of a low refractive index film are alternately formed on an n-type GaAs substrate 2 according to the above equations (1) and (2). An n-type distributed Bragg reflector 3 composed of laminated multilayer films is formed, and a double heterostructure comprising an n-type AlGaInP lower cladding layer 4, an undoped AlGaInP active layer 5, and a p-type AlGaInP upper cladding layer 6 thereon. A light emitting portion having a structure is provided, a p-type AlGaInP current spreading layer 7 is formed on the upper cladding layer 6, and a front electrode 8 and a back electrode 1 are further formed.

  In addition to AlGaInP, a transparent conductive ITO film, GaAlAs, GaP, or the like can be used for the current spreading layer 7.

It is a figure which shows the structure of the light emitting diode which concerns on embodiment of this invention. It is a figure which shows the relationship between the coefficient (alpha) in the type | formula used by this invention, and the spectrum area of a distributed Bragg reflecting film. It is the figure which showed the emission spectrum of the light emitting diode which concerns on embodiment of this invention. It is a figure which shows the structure of the light emitting diode which concerns on other embodiment of this invention. It is the figure which showed the relationship between the number of pairs of the GaAs layer and AlInP layer of the light emitting diode which concerns on embodiment of this invention, and LED luminous intensity. It is a figure which shows the structure of the conventional light emitting diode. It is the figure which showed the emission spectrum of the conventional light emitting diode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Back electrode 2 GaAs substrate 3 Bragg reflector 4 AlGaInP lower clad layer 5 AlGaInP active layer 6 AlGaInP upper clad layer 7 AlGaInP current dispersion layer 8 Surface electrode

Claims (6)

On the first conductivity type substrate, a light emitting portion is formed in which the active layer is sandwiched between the first conductivity type lower cladding layer and the second conductivity type upper cladding layer, and between the first conductivity type lower cladding layer and the substrate, In a light emitting diode having a structure in which a distributed Bragg reflector of the first conductivity type composed of a multilayer film in which a high refractive index film and a low refractive index film are alternately laminated is inserted,
A light emitting diode using an AlGaAs layer and an AlInP layer as materials of a high refractive index film and a low refractive index film constituting the distributed Bragg reflector. On the first conductivity type substrate, a light emitting part sandwiching the active layer between the first conductivity type lower clad layer and the second conductivity type upper clad layer is formed, and a second conductivity type current spreading layer is formed thereon, In a light emitting diode having a structure in which a first conductivity type distributed Bragg reflector composed of a multilayer film in which a high refractive index film and a low refractive index film are alternately laminated is inserted between a first conductivity type lower cladding layer and a substrate,
A light emitting diode using an AlGaAs layer and an AlInP layer as materials of a high refractive index film and a low refractive index film constituting the distributed Bragg reflector. The light-emitting diode according to claim 1 or 2,
The film thicknesses of the AlGaAs layer and the AlInP layer used in the distributed Bragg reflector are expressed by the following equations (1), (2), and (3) (the film thickness [nm] of the AlGaAs layer) = {λ ₀ / (4 × n ₁ )} × α (1)
(AlInP layer thickness [nm]) = {λ ₀ / (4 × n ₂ )} × (2-α) (2)
λ ₀ : Wavelength of light to be reflected [nm]
n ₁ : Refractive index of the AlGaAs layer with respect to the wavelength of the light to be reflected n ₂ : Refractive index of the AlInP layer with respect to the wavelength of the light to be reflected 0.5 <α <0.9 (3)
A light emitting diode characterized by that. In the light emitting diode in any one of Claims 1-3,
A light emitting diode characterized in that when the material of the high refractive index film is expressed as an Al _x Ga _1-x As layer, the Al mixed crystal ratio x is 0 <x <0.6. In the light emitting diode in any one of Claims 1-4,
A light-emitting diode, wherein the substrate is made of GaAs and the light-emitting portion is formed of AlGaInP or GaInP. A distributed Bragg reflector is formed by alternately growing a first conductivity type AlGaAs layer and a first conductivity type AlInP layer on a first conductivity type GaAs substrate by MOVPE, and the first conductivity type AlGaAs layer is formed thereon. An AlGaInP cladding layer, an undoped AlGaInP active layer, a second conductivity type AlGaInP cladding layer, and a second conductivity type AlGaInP current spreading layer are sequentially grown,
At that time, the thicknesses of the AlGaAs layer and the AlInP layer used in the distributed Bragg reflector are expressed by the following equations (1), (2), and (3) (the thickness of the AlGaAs layer [nm]) = {λ ₀ / ( 4 × n ₁ )} × α (1)
(AlInP layer thickness [nm]) = {λ ₀ / (4 × n ₂ )} × (2-α) (2)
λ ₀ : wavelength of light to be reflected [nm]
n ₁ : Refractive index of the AlGaAs layer with respect to the wavelength of the light to be reflected n ₂ : Refractive index of the AlInP layer with respect to the wavelength of the light to be reflected 0.5 <α <0.9 (3)
A method for producing a light-emitting diode, characterized by:

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