JP2011222950A - Light emitting diode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high output and highly efficient light emitting diode and light emitting diode lamp which are excellent in moisture resistance.SOLUTION: The light emitting diode includes a DBR reflection layer and a light emitting part upon a substrate in this order. The light emitting part comprises: an active layer having a lamination structure of a well layer and a barrier layer, consisting of a composition formula (AlGa)As(0≤X1≤1); and first and second cladding layers, consisting of a composition formula (AlGa)InP;0≤X2≤1,0<Y≤1), which sandwich the active layer.

Description

  The present invention relates to a light emitting diode, and more particularly to a high output light emitting diode of 660 nm to 850 nm.

Infrared light emitting diodes (hereinafter referred to as LEDs) are widely used for infrared communication, various sensor light sources, night illumination, and the like.
In recent years, light with a peak wavelength of 660 to 720 nm is a red light source that can be recognized by humans, and because it is an outdoor display and a high output wavelength band, it is desirable to visually recognize the presence of the sensor, It is used in a wide range of applications such as light sources for barcode readers and medical oximeters.
In addition, the effect of infrared light having a peak wavelength of 730 nm has been confirmed as one of emission wavelengths suitable for shape control of physical growth.
Furthermore, light having a peak wavelength of 760 to 850 nm is a wavelength band having a high light emission output, and is therefore an optimum wavelength band for infrared illumination of various sensor light sources, surveillance cameras, video cameras, and the like. The AlGaAs active layer in this wavelength band is suitable for optical communications and high-speed photocouplers because it can respond at high speed. On the other hand, it has begun to be used for light sources such as vein authentication systems and medical fields by utilizing the characteristics of emission wavelength.

In the above applications, high output of LEDs is desired to improve the performance of each device. On the other hand, it is desired to improve reliability in a moisture resistant environment.
For example, in a conventional infrared light emitting diode, an LED made of an AlGaAs multilayer film using a liquid phase epitaxial method on a GaAs substrate has been put into practical use, and various high output studies have been made.

JP-A-6-21507 JP 2001-274454 A Japanese Patent Laid-Open No. 7-38148

  From the viewpoint of further performance improvement, energy saving, and cost as a light source, development of an LED having high luminous efficiency is desired. Not only indoors but also outdoor and semi-outdoor environments are expanding, and moisture resistance is one of the important reliability items. In particular, for practical application of plant-growing LED lighting that has been attracting attention in recent years, reduction of power consumption, improvement of moisture resistance, and higher output are strongly desired. In the case of plant growth, moisture resistance is one of the important characteristics because it is used in a high humidity environment such as watering and hydroponics. Moreover, it is difficult to form a multiple quantum well structure with excellent monochromaticity by a method of growing a compound semiconductor layer by a liquid phase epitaxial method.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a light emitting diode having high output and high efficiency and excellent moisture resistance.

As a result of intensive studies to solve the above problems, the present inventor has made a multiple quantum well structure in which ternary mixed crystal AlGaAs well layers and barrier layers made of AlGaAs or quaternary mixed crystal AlGaInP are alternately stacked. In the light emitting diode using the active layer, the clad layer sandwiching the active layer has a large band gap, is transparent to the emission wavelength, and does not contain As which easily forms a defect. It has been found that the use of the crystal AlGaInP system shows higher output than the case of using the AlGaAs system for the cladding layer. In addition, by using a quaternary mixed crystal AlGaInP system for the cladding, it is possible to reduce the Al concentration compared to a light emitting diode using a ternary mixed crystal AlGaAs system for the cladding, making it less susceptible to corrosion and moisture resistance. Will also improve.
As a result of further research on this knowledge, the present inventor has completed the present invention shown in the following configuration.

(1) A light emitting diode comprising a DBR reflective layer and a light emitting unit in order on a substrate,
The light emitting portion includes an active layer having a stacked structure of a well layer and a barrier layer having a composition formula (Al _X1 Ga _1-X1 ) As (0 ≦ X1 ≦ 1), and a composition formula (Al _{X2 Ga 1-X2) Y in} 1-Y P; 0 ≦ X2 ≦ 1,0 <Y ≦ 1) comprising a first cladding layer and the second light emitting diode; and a cladding layer.
(2) A light emitting diode comprising a DBR reflective layer and a light emitting unit in order on a substrate,
The light emitting part includes a well layer having a composition formula (Al _X1 Ga _1-X1 ) As (0 ≦ X1 ≦ 1) and a composition formula (Al _X3 Ga _1-X3 ) _Y2 In _{1 -Y2} P (0 ≦ X3 ≦ 1). , 0 <Y2 ≦ 1) and an active layer having a multilayer structure, and a composition formula (Al _X2 Ga _1-X2 ) _Y In _1-YP (0 ≦ X2 ≦ 1, sandwiching the active layer) A light emitting diode comprising a first clad layer and a second clad layer of 0 <Y ≦ 1).
(3) In the composition formula of the well layer, the Al composition (X1) is set to 0.20 ≦ X1 ≦ 0.36, the thickness of the well layer is set to 3 to 30 nm, and the emission wavelength is set to 660 to 720 nm. The light-emitting diode according to any one of (1) and (2) above, wherein
(4) In the composition formula of the well layer, the Al composition (X1) is set to 0.1 ≦ X1 ≦ 0.24, the thickness of the well layer is set to 3 to 30 nm, and the emission wavelength is set to 720 to 760 nm. The light-emitting diode according to any one of (1) and (2) above, wherein
(5) In the composition formula of the well layer, the Al composition (X1) is set to 0 ≦ X1 ≦ 0.2, the thickness of the well layer is set to 3 to 30 nm, and the emission wavelength is set to 760 to 850 nm. The light-emitting diode according to any one of (1) and (2) above, which is characterized.
(6) The light-emitting diode according to any one of (1) to (5) above, wherein the DBR reflective layer is formed by alternately stacking 10 to 50 pairs of two types of layers having different refractive indexes.
(7) The two types of layers having different refractive indexes are two types of (Al _Xh Ga _1-Xh ) _{Y 3} In _{1 -Y 3} P (0 <Xh ≦ 1, Y3 = 0.5), (Al _Xl Ga _{1 -Xl} ) _Y3 In _{1 -Y3} P (0 ≦ Xl <1, Y3 = 0.5), and Al composition difference ΔX = xh−xl between the two is greater than or equal to 0.5 The light-emitting diode according to item (6), wherein
(8) The light-emitting diode according to (6), wherein the two types of layers having different refractive indexes are a combination of GaInP and AlInP.
(9) The two types of layers having different refractive indexes are composed of two types of Al _xl Ga _1-xl As (0.1 ≦ xl ≦ 1) and Al _xh Ga _1-xh As (0.1 ≦ xh ≦) having different compositions. The light-emitting diode according to the item (6), which is a combination of 1) and has a composition difference ΔX = xh−xl between the two Al larger than or equal to 0.5.
(10) The light-emitting diode according to any one of (1) to (9), wherein a current diffusion layer is provided on a surface of the light-emitting portion opposite to the DBR reflection layer.

According to said structure, the following effects are acquired.
It can emit red and infrared light having an emission peak wavelength of 660 nm to 850 nm with high output and high efficiency.
The active layer has a multi-well structure in which a well layer having a composition formula (Al _X1 Ga _{1 -X1} ) As (0 ≦ X1 ≦ 1) and a barrier layer made of AlGaAs or a quaternary mixed crystal AlGaInP are alternately stacked. Therefore, it is excellent in monochromaticity.
Since the clad layer is composed of a quaternary mixed crystal (Al _X2 Ga _1-X2 ) _Y In _1-YP (0 ≦ X2 ≦ 1, 0 <Y ≦ 1), the clad layer is a ternary mixed crystal. Compared to a light emitting diode made of AlGaAs, the Al concentration is lower and the moisture resistance is improved.
In addition, the first clad layer and the second clad layer sandwiching the active layer employ a configuration made of AlGaInP that is transparent to the emission wavelength and has high crystallinity because it does not contain As that easily creates defects. As a result, the probability of non-radiative recombination of electrons and holes through the defect is reduced, and the light emission output is improved.
Since the active layer has a stacked structure of a well layer and a barrier layer having the composition formula (Al _X1 Ga _{1 -X1} ) As (0 ≦ X1 ≦ 1), it is suitable for mass production using the MOCVD method. .
Since the DBR reflective film is provided between the light emitting layer and the substrate, the light emission output is not reduced by light absorption by the GaAs substrate.

It is a cross-sectional schematic diagram of the light emitting diode using the light emitting diode which is one Embodiment of this invention. It is a cross-sectional schematic diagram of the epiwafer used for the light emitting diode which is one Embodiment of this invention.

  Hereinafter, a light emitting diode according to an embodiment to which the present invention is applied will be described in detail with reference to the drawings. In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent.

<Light Emitting Diode (First Embodiment)>
FIG. 1 is a schematic cross-sectional view of a light-emitting diode according to the first embodiment. FIG. 2 is a schematic sectional view of a laminated structure of a well layer and a barrier layer.
The light emitting diode 100 according to the first embodiment is a light emitting diode including a DBR reflection layer 3 and a light emitting unit 20 in this order on a substrate 1, and the light emitting unit 20 has a composition formula (Al _X1 Ga _1-X1). ) An active layer 7 having a stacked structure of a well layer 15 and a barrier layer 16 made of As (0 ≦ X1 ≦ 1), and a composition formula (Al _X2 Ga _1−X2 ) _Y In ₁₋ sandwiching the active layer 7. _{It has} the 1st clad layer 5 and the 2nd clad layer 9 which consist of YP; 0 <= X2 <= 1,0 <Y <= 1).

As shown in FIG. 1, the compound semiconductor layer (also referred to as an epitaxial growth layer) 30 has a structure in which a light emitting unit 20 and a current diffusion layer 10 are sequentially stacked. A known functional layer can be added to the structure of the compound semiconductor layer 30 as appropriate. For example, a contact layer for reducing the contact resistance of an ohmic electrode, a current diffusion layer for planarly diffusing the element driving current over the entire light emitting portion, and conversely, limiting a region through which the element driving current flows. Therefore, a known layer structure such as a current blocking layer or a current confinement layer can be provided.
The compound semiconductor layer 30 is preferably formed by epitaxial growth on the GaAs substrate 1.

  The light emitting unit 20 provided on the n-type substrate 1 includes, for example, an n-type lower clad layer (first clad layer) 5, a lower guide layer 6, and an active layer 7 on the DBR reflective layer 3 as shown in FIG. The upper guide layer 8 and the p-type upper clad layer (second clad layer) 9 are sequentially laminated. That is, the light emitting unit 20 includes a lower clad layer 5 disposed opposite to the upper side and the upper side of the active layer 7 in order to “confine” the carrier (carrier) that causes radiative recombination and light emission in the active layer 7. A so-called double hetero (English abbreviation: DH) structure including the lower guide layer 6, the upper guide layer 8, and the upper cladding layer 9 is preferable in order to obtain high-intensity light emission.

  As shown in FIG. 2, the active layer 7 forms a quantum well structure in order to control the emission wavelength of the light emitting diode (LED). That is, the active layer 7 has a multilayer structure (laminated structure) of a well layer 15 and a barrier layer (also referred to as a barrier layer) 16 having a barrier layer (also referred to as a barrier layer) 16 at both ends.

The layer thickness of the active layer 7 is preferably in the range of 0.02 to 2 μm. In particular, when the thickness is 0.03 μm, the Al composition can be lowered, which is particularly preferable from the viewpoint of reliability. Further, the conductivity type of the active layer 7 is not particularly limited, and any of undoped, p-type and n-type can be selected. In order to increase the luminous efficiency, it is desirable that the crystallinity is undoped or the carrier concentration is less than 3 × 10 ¹⁷ cm ⁻³ .

  The DBR (Distributed Bragg Reflector) reflective layer 3 has two types of refractive indexes having a thickness of λ / (4n) (λ: wavelength of light to be reflected in vacuum, n: refractive index of layer material). It consists of a multilayer film in which layers are alternately stacked. When the difference between the two types of refractive indexes is large, a high reflectance can be obtained with a multilayer film having a relatively small number of layers. Instead of being reflected on a certain surface as in a normal reflective film, the multilayer film as a whole is characterized in that reflection occurs based on the light interference phenomenon.

The DBR (Distributed Bragg Reflector) reflecting layer 3 is preferably formed by alternately laminating 10 to 50 pairs of two types of layers having different refractive indexes. This is because when the number is 10 pairs or less, the reflectance is too low, so that it does not contribute to an increase in output, and even when the number is 50 pairs or more, the increase in reflectance is small.
Two types of layers having different refractive indexes constituting the DBR (Distributed Bragg Reflector) reflecting layer 3 are two types of (Al _Xh Ga _1-Xh ) _{Y 3} In _{1 -Y 3} P (0 <Xh ≦ 1, Y ₃ ) having different compositions. = 0.5), (Al _Xl Ga _1-Xl ) _Y3 In _1-Y3 P; 0 ≦ Xl <1, Y3 = 0.5), and the Al composition difference ΔX = xh−xl A combination of greater than or equal to 0.5, a combination of GaInP and AlInP, or two types of Al _xl Ga _1-xl As (0.1 ≦ xl ≦ 1) and Al _xh Ga _{1 having} different compositions _-Xh As (0.1 ≦ xh ≦ 1) pair, and the high and efficient reflection is selected from any combination in which the composition difference ΔX = xh−xl of both is greater than or equal to 0.5 This is desirable because the rate is obtained.
A combination of AlGaInP having different compositions is preferable because it does not contain As that easily causes crystal defects, and GaInP and AlInP have the largest refractive index difference among them, so that the number of reflective layers can be reduced and the composition can be switched. Is also preferable because it is simple. Moreover, AlGaAs has an advantage that a large difference in refractive index is easily obtained.

The well layer 15 preferably has a composition of (Al _X1 Ga _1-X1 ) As (0 ≦ X1 ≦ 0.36).
Table 1 shows the relationship between the Al composition X1 and the emission peak wavelength when the thickness of the well layer 15 is 17 nm. It can be seen that the lower the Al composition X1, the longer the emission peak wavelength. Moreover, from the tendency of the change, the Al composition corresponding to the emission peak wavelength not listed in the table can be estimated.

  The thickness of the well layer 15 is preferably in the range of 3 to 30 nm. More preferably, it is the range of 5-20 nm.

以上の発光ピーク波長と、井戸層１５のＡｌ組成Ｘ及び層厚との関係に基づいて、６６０ｎｍ〜７２０ｎｍの範囲内の所望の発光ピーク波長が得られるように、井戸層１５のＡｌ組成Ｘと層厚を決めることができる。 Table 2 shows the relationship between the layer thickness of the well layer 15 and the emission peak wavelength when the Al composition X1 of the well layer 15 is 0.24. As the layer thickness decreases, the wavelength decreases due to the quantum effect. When it is thick, the emission peak wavelength is constant depending on the composition. Further, from the tendency of the change, the layer thickness corresponding to the emission peak wavelength not listed in the table can be estimated.

Based on the relationship between the above emission peak wavelength, the Al composition X of the well layer 15 and the layer thickness, the Al composition X of the well layer 15 can be obtained so that a desired emission peak wavelength in the range of 660 nm to 720 nm is obtained. The layer thickness can be determined.

以上の発光ピーク波長と、井戸層１５のＡｌ組成Ｘ及び層厚との関係に基づいて、７２０ｎｍ〜７６０ｎｍの範囲内の所望の発光ピーク波長が得られるように、井戸層１５のＡｌ組成Ｘと層厚を決めることができる。 Table 3 shows the relationship between the layer thickness of the well layer 15 and the emission peak wavelength when the Al composition X1 of the well layer 15 is 0.18. As the layer thickness decreases, the wavelength decreases due to the quantum effect. When it is thick, the emission peak wavelength is constant depending on the composition. Further, from the tendency of the change, the layer thickness corresponding to the emission peak wavelength not listed in the table can be estimated.

Based on the relationship between the above emission peak wavelength and the Al composition X and the layer thickness of the well layer 15, the Al composition X of the well layer 15 can be obtained so that a desired emission peak wavelength within the range of 720 nm to 760 nm is obtained. The layer thickness can be determined.

以上の発光ピーク波長と、井戸層１５のＡｌ組成Ｘ及び層厚との関係に基づいて、７６０ｎｍ〜８５０ｎｍの範囲内の所望の発光ピーク波長が得られるように、井戸層１５のＡｌ組成Ｘと層厚を決めることができる。 Table 4 shows the relationship between the layer thickness of the well layer 15 and the emission peak wavelength when the Al composition X1 of the well layer 15 is 0.03. As the layer thickness decreases, the wavelength decreases due to the quantum effect. When it is thick, the emission peak wavelength is constant depending on the composition. Further, from the tendency of the change, the layer thickness corresponding to the emission peak wavelength not listed in the table can be estimated.

Based on the relationship between the above emission peak wavelength, the Al composition X of the well layer 15 and the layer thickness, the Al composition X of the well layer 15 can be obtained so that a desired emission peak wavelength within the range of 760 nm to 850 nm is obtained. The layer thickness can be determined.

The barrier layer 16 has a composition of (Al _X3 Ga _{1 -X3} ) As (0 <X3 ≦ 1). X3 is preferably a composition having a band gap larger than that of the well layer 15 in order to increase luminous efficiency. However, from the viewpoint of crystallinity, the Al concentration is preferably lower, and the optimum X3 composition is that of the well layer. Determined by relationship to composition. When the crystallinity is improved to reduce defects, light absorption is suppressed, and as a result, light emission output can be improved.
Specifically, when the Al composition (X1) of the well layer is 0.20 ≦ X1 ≦ 0.36, X3 is preferably in the range of 0.4 to 0.6. When the Al composition (X1) of the well layer is 0 ≦ X1 ≦ 0.2, X3 is preferably in the range of 0.1 to 0.4.

  The thickness of the barrier layer 16 is preferably equal to or thicker than the thickness of the well layer 15. Thereby, the luminous efficiency of the well layer 15 can be increased.

In the multilayer structure of the well layers 15 and the barrier layers 16, the number of pairs in which the well layers 15 and the barrier layers 16 are alternately stacked is not particularly limited, but is preferably 2 to 40 pairs. . That is, the active layer 11 preferably includes 2 to 40 well layers 17. Here, as a preferable range of the luminous efficiency of the active layer 11, it is preferable that the well layer 17 has five or more layers. On the other hand, since the well layer 17 and the barrier layer 18 have a low carrier concentration, the forward voltage (V _F ) increases when the number of pairs is increased. For this reason, it is preferable that it is 40 pairs or less, and it is more preferable that it is 20 pairs or less.

  The lower guide layer 6 and the upper guide layer 8 are provided on the lower surface and the upper surface of the active layer 7, respectively, as shown in FIG. Specifically, the lower guide layer 6 is provided on the lower surface of the active layer 7, and the upper guide layer 8 is provided on the upper surface of the active layer 7.

The lower guide layer 6 and the upper guide layer 8 have a composition of (Al _X4 Ga _{1 -X4} ) As (0 <X4 ≦ 1). X4 is preferably a composition having the same band gap as that of the barrier layer 16 or larger than the barrier layer 16, and the optimum composition of X from the viewpoint of crystallinity is determined by the relationship with the composition of the well layer. When the crystallinity is improved to reduce defects, light absorption is suppressed, and as a result, light emission output can be improved.
Specifically, when the Al composition (X1) of the well layer is in the range of 0.20 ≦ X1 ≦ 0.36 and the Al composition (X3) of the barrier layer is in the range of 0.4 to 0.6, X4 is 0.00. A range of 4 to 0.7 is preferred. When the Al composition (X1) of the well layer is 0 ≦ X1 ≦ 0.2 and the Al composition (X3) of the barrier layer is 0.1 to 0.4, X4 is in the range of 0.2 to 0.6. It is preferable that

  The lower guide layer 6 and the upper guide layer 8 are provided to reduce the propagation of defects between the lower clad layer 5 and the upper clad layer 9 and the active layer 7, respectively. That is, in the present invention, the group V constituent element of the active layer 7 is arsenic (As), whereas the group V constituent element of the lower cladding layer 5 and the upper cladding layer 9 is phosphorus (P). Defects are likely to occur at the interfaces between the lower cladding layer 5 and the upper cladding layer 9. Propagation of defects to the active layer 7 causes a reduction in the performance of the light emitting diode. In order to effectively reduce the propagation of this defect, the thickness of the lower guide layer 6 and the upper guide layer 8 is preferably 10 nm or more, and more preferably 20 nm to 100 nm.

The conductivity type of the lower guide layer 6 and the upper guide layer 8 is not particularly limited, and any of undoped, p-type, and n-type can be selected. In order to increase the luminous efficiency, it is desirable that the crystallinity is undoped or the carrier concentration is less than 3 × 10 ¹⁷ cm ⁻³ .

  As shown in FIG. 1, the lower cladding layer 5 and the upper cladding layer 9 are provided on the lower surface of the lower guide layer 6 and the upper surface of the upper guide layer 8, respectively.

As the material of the lower cladding layer 5 and the upper cladding layer _9, a semiconductor material _{(Al X2 Ga 1-X2)} Y In 1-Y P (0 ≦ X2 ≦ 1,0 <Y ≦ 1), a barrier layer 15 A material having a larger band gap is preferable, and a material having a larger band gap than the lower guide layer 6 and the upper guide layer 8 is more preferable. As the _material, have a composition X2 is 0.3 to 0.7 of _{(Al X2 Ga 1-X2)} Y In 1-Y P (0 ≦ X4 ≦ 1,0 <Y ≦ 1) preferable. Y is preferably 0.4 to 0.6.

  The lower clad layer 5 and the upper clad layer 9 are configured to have different polarities. The carrier concentration and thickness of the lower clad layer 5 and the upper clad layer 9 can be in a known suitable range, and it is preferable to optimize the conditions so that the luminous efficiency of the active layer 7 is increased. Further, the warpage of the compound semiconductor layer 30 can be reduced by controlling the composition of the lower cladding layer 5 and the upper cladding layer 9.

Specifically, as the lower cladding layer 5, for example, n-type (Al _X4b Ga _1-X4b ) _Yb In _1-Yb P doped with Si (0.3 ≦ X4b ≦ 0.7, 0.4 ≦ Yb) It is desirable to use a semiconductor material composed of ≦ 0.6). The carrier concentration is preferably in the range of 1 × 10 ¹⁷ to 1 × 10 ¹⁸ cm ⁻³ , and the layer thickness is preferably in the range of 0.1 to 1 μm.

On the other hand, as the upper clad layer 9, for example, Mg-doped p-type (Al _X4a Ga _1-X4a ) _Ya In _1- YaP (0.3 ≦ X4a ≦ 0.7, 0.4 ≦ Ya ≦ 0) .6) is preferably used. The carrier concentration is preferably in the range of 2 × 10 ¹⁷ to 2 × 10 ¹⁸ cm ⁻³ , and the layer thickness is preferably in the range of 0.1 to 1 μm.
The polarities of the lower cladding layer 5 and the upper cladding layer 9 can be selected in consideration of the element structure of the compound semiconductor layer 30.

  Further, above the constituent layers of the light emitting unit 20, a contact layer for lowering the contact resistance of the ohmic electrode, a current diffusion layer for planarly diffusing the element driving current throughout the light emitting unit, and conversely A known layer structure such as a current blocking layer or a current confinement layer for limiting the region through which the element driving current flows can be provided.

As shown in FIG. 1, the current spreading layer 10 is provided above the light emitting unit 20. The current spreading layer 10 may be made of a material that is transparent to the emission wavelength from the light emitting unit 20 (active layer 7), such as GaP or GaInP.
The thickness of the current spreading layer 10 is preferably in the range of 0.5 to 20 μm. This is because the current diffusion is insufficient when the thickness is 0.5 μm or less, and the cost for crystal growth to the thickness increases when the thickness is 20 μm or more.

  The p-type ohmic electrode (first electrode) 12 is a low-resistance ohmic contact electrode provided on the main light extraction surface of the light-emitting diode 100, and the n-type ohmic electrode (second electrode) 13 is a substrate of the light-emitting diode 100. It is a low-resistance ohmic contact electrode provided on the side back surface. Here, the p-type ohmic electrode 12 is provided on the surface of the current diffusion layer 10, and for example, an alloy made of AuBe / Au or AuZn / Au can be used. On the other hand, the n-type ohmic electrode 13 can be made of, for example, an alloy made of AuGe or Ni alloy / Au.

<Method for manufacturing light-emitting diode>
Next, the manufacturing method of the light emitting diode 100 of this embodiment is demonstrated using FIG.

(Formation process of compound semiconductor layer)
First, the compound semiconductor layer 30 shown in FIG. 1 is produced. The compound semiconductor layer 30 comprises an n-type GaAs substrate 1 on which a buffer layer 2 made of GaAs, a layer 3a made of GaInP (a layer having a high refractive index) 3a and a layer made of AlInP (a layer having a low refractive index) 3b are alternately arranged. 40 pairs of DBR reflection layers 3, Si-doped n-type lower cladding layer 5, lower guide layer 6, active layer 7, upper guide layer 8, Mg-doped p-type upper cladding layer 9, Mg-doped p A current diffusion layer 10 made of type GaP is sequentially stacked.

As the GaAs substrate 1, a commercially available single crystal substrate manufactured by a known manufacturing method can be used. The surface on which the GaAs substrate 1 is epitaxially grown is preferably smooth. The plane orientation of the surface of the GaAs substrate 1 is easy to epitaxially grow, and a substrate that is turned off within ± 20 ° from the (100) plane and (100) that are mass-produced is desirable from the standpoint of quality stability. Furthermore, the range of the plane orientation of the GaAs substrate 1 is more preferably 15 ° off ± 5 ° from the (100) direction to the (0-1-1) direction.
In this specification, in the notation of Miller index, “-” means a bar attached to the index immediately after that.

The dislocation density of the GaAs substrate 1 is desirably low in order to improve the crystallinity of the compound semiconductor layer 30. Specifically, for example, 10,000 pieces cm ⁻² or less, preferably 1,000 pieces cm ⁻² or less are suitable.

The GaAs substrate 1 may be n-type or p-type. The carrier concentration of the GaAs substrate 1 can be appropriately selected from desired electrical conductivity and element structure. For example, when the GaAs substrate 1 is Si-doped n-type, the carrier concentration is preferably in the range of 1 × 10 ^{17 to} 5 × 10 ¹⁸ cm ⁻³ . On the other hand, when the GaAs substrate 1 is a Zn-doped p-type, the carrier concentration is preferably in the range of 2 × 10 ^{18 to} 5 × 10 ¹⁹ cm ⁻³ .

  The thickness of the GaAs substrate 1 has an appropriate range depending on the size of the substrate. If the thickness of the GaAs substrate 1 is thinner than an appropriate range, the compound semiconductor layer 30 may be broken during the manufacturing process. On the other hand, if the thickness of the GaAs substrate 1 is thicker than an appropriate range, the material cost increases. For this reason, when the substrate size of the GaAs substrate 1 is large, for example, when the diameter is 75 mm, a thickness of 250 to 500 μm is desirable to prevent cracking during handling. Similarly, when the diameter is 50 mm, a thickness of 200 to 400 μm is desirable, and when the diameter is 100 mm, a thickness of 350 to 600 μm is desirable.

  Thus, by increasing the thickness of the substrate according to the substrate size of the GaAs substrate 1, it is possible to reduce the warpage of the compound semiconductor layer 30 caused by the light emitting unit 20. As a result, the temperature distribution during epitaxial growth becomes uniform, so that the in-plane wavelength distribution of the active layer 7 can be reduced. The shape of the GaAs substrate 1 is not particularly limited to a circle, and there is no problem even if it is a rectangle or the like.

  The buffer layer 2 is provided to reduce the propagation of defects between the GaAs substrate 1 and the constituent layers of the light emitting unit 20. For this reason, the buffer layer 2 is not necessarily required if the quality of the substrate and the epitaxial growth conditions are selected. The material of the buffer layer 2 is preferably the same as that of the substrate to be epitaxially grown. Therefore, in the present embodiment, it is preferable to use GaAs for the buffer layer 2 in the same manner as the GaAs substrate 1. The buffer layer 2 may be a multilayer film made of a material different from that of the GaAs substrate 1 in order to reduce the propagation of defects. The thickness of the buffer layer 2 is preferably 0.1 μm or more, and more preferably 0.2 μm or more.

The DBR reflection layer 3 is provided to reflect light traveling in the substrate direction. The material of the DBR reflective layer 3 is preferably transparent with respect to the emission wavelength, and is preferably selected so as to be a combination that increases the difference in refractive index between the two types of materials constituting the DBR reflective layer 3. . In this embodiment, the material of the DBR reflective layer 3 is a combination of AlInP and GaInP, but two types of (Al _Xl Ga _1-Xl ) _0.5 In _0.5 P (0 ≦ xl <1) having different compositions are used. , (Al _Xh Ga _1-Xh ) _0.5 In _0.5 P (0 <xh ≦ 1), or two types of different Al _xl Ga _1-xl As (0.1 ≦ xl ≦ 1), Al It is also possible to select from _xh Ga _1-xh As (0.1 ≦ xh ≦ 1).

  In the present embodiment, a known growth method such as a molecular beam epitaxial method (MBE) or a low pressure metal organic chemical vapor deposition method (MOCVD method) can be applied. Among these, it is most desirable to apply the MOCVD method which is excellent in mass productivity. Specifically, the GaAs substrate 1 used for the epitaxial growth of the compound semiconductor layer 30 is preferably subjected to a pretreatment such as a cleaning process or a heat treatment before the growth to remove surface contamination or a natural oxide film. The layers constituting the compound semiconductor layer 30 can be stacked by setting a GaAs substrate 1 having a diameter of 50 to 150 mm in an MOCVD apparatus and simultaneously epitaxially growing the layers. As the MOCVD apparatus, a commercially available large-sized apparatus such as a self-revolving type or a high-speed rotating type can be applied.

When the layers of the compound semiconductor layer 30 are epitaxially grown, examples of the group III constituent material include trimethylaluminum ((CH ₃ ) ₃ Al), trimethylgallium ((CH ₃ ) ₃ Ga), and trimethylindium ((CH ₃ ) ₃ In) can be used. Further, as a Mg doping raw material, for example, biscyclopentadienyl magnesium (bis- (C ₅ H ₅ ) ₂ Mg) or the like can be used. Further, as a Si doping material, for example, disilane (Si ₂ H ₆ ) or the like can be used.
In addition, phosphine (PH ₃ ), arsine (AsH ₃ ), or the like can be used as a raw material for the group V constituent element.
As the growth temperature of each layer, when p-type GaP is used as the current diffusion layer 10, 720 to 770 ° C. can be applied, and for the other layers, 600 to 700 ° C. can be applied.
Further, when p-type GaInP is used as the current diffusion layer 10, 600 to 700 ° C. can be applied.
Furthermore, the carrier concentration, layer thickness, and temperature conditions of each layer can be selected as appropriate.

  The compound semiconductor layer 30 produced in this way has a good surface state with few crystal defects despite having the light emitting portion 20. The compound semiconductor layer 30 may be subjected to surface processing such as polishing corresponding to the element structure.

(First and second electrode forming steps)
Next, a p-type ohmic electrode 12 that is a first electrode and an n-type ohmic electrode 13 that is a second electrode are formed.
<Light Emitting Diode (Second Embodiment)>
In the light emitting diode according to the second embodiment to which the present invention is applied, the AlGaAs barrier layer 16 in the light emitting diode according to the first embodiment is composed of the composition formula (Al _X3 Ga _1-X3 ) _Y2 In _1-Y2 P (0 ≦ X3 ≦ 1, 0 <Y2 ≦ 1).

The barrier layer is made of a compound semiconductor having a composition formula ( _{AlX3Ga1 -X3} ) _{Y2In1 -Y2P} (0≤X3≤1, 0 <Y2≤1).
The Al composition X3 is preferably a composition having a larger band gap than the well layer, and specifically, a range of 0 to 0.2 is preferable.
Y2 is preferably 0.4 to 0.6, and more preferably 0.45 to 0.55 in order to prevent generation of distortion due to lattice mismatch with the substrate.

Hereinafter, the effect of the present invention will be specifically described with reference to examples. The present invention is not limited to these examples.

In this example, an example in which a light-emitting diode according to the present invention is manufactured will be specifically described. In addition, the light emitting diode manufactured in this example includes a light emitting diode having an active layer having a quantum well structure of a well layer made of AlGaAs and a barrier layer made of AlGaAs, and a barrier layer made of AlGaAs and a barrier layer made of AlGainP. And a light emitting diode having an active layer having a quantum well structure. In this example, a light-emitting diode lamp in which a light-emitting diode chip was mounted on a substrate was prepared for characteristic evaluation.

(Example 1)
In the light emitting diode of Example 1, first, an epitaxial wafer was fabricated by sequentially laminating compound semiconductor layers on a GaAs substrate made of an n-type GaAs single crystal doped with Si. In the GaAs substrate, a plane inclined by 15 ° in the (0-1-1) direction from the (100) plane was used as a growth plane, and the carrier concentration was set to 2 × 10 ¹⁸ cm ⁻³ . The layer thickness of the GaAs substrate was about 0.5 μm. The compound semiconductor layer is an n-type buffer layer made of GaAs doped with Si, an n-type DBR reflection layer having a 40-pair repeating structure of AlInP and GaInP doped with Si, and doped with Si (Al _0.7 N-type lower cladding layer made of Ga _0.3 ) _0.5 In _0.5 P, lower guide layer made of Al _0.6 Ga _0.4 As, Al _0.24 Ga _0.76 As / Al _{0. 4} Ga _0.6 well layer / barrier layer made of 22 pairs of _As, Al 0.6 _{Ga 0.4} upper guide layer made of As, doped with _{Mg (Al 0.7 Ga 0.3) 0.5} in _A p-type upper cladding layer made of _0.5 P, a thin intermediate layer made of (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P, and a current diffusion layer made of Mg-doped p-type GaP is there.

In this example, a compound semiconductor layer was epitaxially grown on a GaAs substrate having a diameter of 76 mm and a thickness of 350 μm by using a low pressure metal organic chemical vapor deposition apparatus method (MOCVD apparatus) to form an epitaxial wafer. When growing an epitaxial growth layer, trimethylaluminum ((CH ₃ ) ₃ Al), trimethylgallium ((CH ₃ ) ₃ Ga) and trimethylindium ((CH ₃ ) ₃ In) are used as the raw material for the group III constituent element did. Further, biscyclopentadienyl magnesium (bis- (C ₅ H ₅ ) ₂ Mg) was used as a Mg doping material. Further, disilane (Si ₂ H ₆ ) was used as a Si doping material. Further, phosphine (PH ₃ ) and arsine (AsH ₃ ) were used as raw materials for the group V constituent elements. As the growth temperature of each layer, the current diffusion layer made of p-type GaP was grown at 750 ° C. The other layers were grown at 700 ° C.

The buffer layer made of GaAs has a carrier concentration of about 2 × 10 ¹⁸ cm ⁻³ and a layer thickness of about 0.5 μm. The lower cladding layer had a carrier concentration of about 1 × 10 ¹⁸ cm ⁻³ and a layer thickness of about 0.5 μm. The lower guide layer was undoped and had a thickness of about 50 nm. The well layer was undoped Al _0.24 Ga _0.76 As with a thickness of about 17 nm, and the barrier layer was undoped Al _0.4 Ga _0.6 As with a thickness of about 19 nm. Further, 22 pairs of well layers and barrier layers were alternately laminated. The upper guide layer was undoped and had a thickness of about 50 nm. The upper cladding layer had a carrier concentration of about 8 × 10 ¹⁷ cm ⁻³ and a layer thickness of about 0.5 μm. The intermediate layer had a carrier concentration of about 8 × 10 ¹⁷ cm ⁻³ and a layer thickness of about 0.05 μm. The current diffusion layer made of GaP has a carrier concentration of about 3 × 10 ¹⁸ cm ⁻³ and a layer thickness of about 9 μm.
Alternating addition, DBR reflection layer and the carrier concentration of about 1 × ¹⁰ 18 ^{cm -3,} and AlInP that were about 54nm thickness, carrier concentration of about 1 × ¹⁰ 18 ^{cm -3,} a thickness of about 51nm was GaInP the 40 pairs were stacked.

  Next, a film was formed on the surface of the current diffusion layer by vacuum deposition so that AuBe was 0.2 μm and Au was 1 μm. Thereafter, patterning was performed using a general photolithography means, and a p-type ohmic electrode was formed as the first electrode. Next, a roughening treatment was performed on the light extraction surface which is a surface other than the electrode portion.

  Next, a second electrode is formed on the back surface of the substrate by vacuum deposition so that AuGe and Ni alloy have a thickness of 0.5 μm, Pt of 0.2 μm, and Au of 1 μm, and an n-type ohmic electrode is formed. Formed. Thereafter, heat treatment was performed at 450 ° C. for 10 minutes to form an alloy, and low resistance p-type and n-type ohmic electrodes were formed.

  Next, a dicing saw was used to cut from the compound semiconductor layer side at 350 μm intervals to form chips. The crushing layer and dirt by dicing were removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide to produce a light emitting diode of Example 1.

  100 light emitting diode lamps each having the light emitting diode chip of Example 1 manufactured as described above mounted on a mount substrate were assembled. This light-emitting diode lamp was manufactured by supporting (mounting) a mount with a die bonder, wire-bonding a p-type ohmic electrode and a p-electrode terminal with a gold wire, and sealing with a general epoxy resin.

Table 1 shows the results of evaluating the characteristics of the light emitting diode (light emitting diode lamp).
As shown in Table 1, when a current was passed between the n-type and p-type ohmic electrodes, red light having a peak wavelength of 700 nm was emitted. The forward voltage (Vf) when a current of 20 mA (mA) was passed in the forward direction was about 1.4 volts. The light emission output when the forward current was 20 mA was 6.5 mW.

(Example 2)
The light-emitting diode of Example 2 is an example of the first embodiment, and the Al composition X of the well layer X = 0.18 and the Al composition X of the barrier layer X = 0.4 in order to set the emission peak wavelength to 730 nm. The light emitting portion was changed to a well layer / barrier layer composed of a pair of Al _0.18 Ga _0.82 As / Al _0.4 Ga _0.6 As. Furthermore, the thickness of the DBR reflection layer was changed to AlInP with about 57 nm and GaInP with about 53 nm. Others were produced under the same conditions as in Example 1.
The results of evaluating the characteristics of this light emitting diode (light emitting diode lamp) are as shown in Table 5. Red light having a peak wavelength of 730 nm is emitted, and the light emission output (P ₀ ) and forward voltage (V _F ) are They were 6.7 mW and 1.4 V, respectively.

(Example 3)
The light-emitting diode of Example 3 is an example of the first embodiment, and Al composition X = 0.03 of the well layer and Al composition X = 0.2 of the barrier layer in order to set the emission peak wavelength to 830 nm. The light emitting portion was changed to a well layer / barrier layer composed of a pair of Al _0.03 Ga _0.97 As / Al _0.2 Ga _0.8 As. Furthermore, the thickness of the DBR reflective layer was changed to AlInP with about 64 nm and GaInP with about 60 nm. Others were produced under the same conditions as in Example 1.
The results of evaluating the characteristics of this light emitting diode (light emitting diode lamp) are as shown in Table 5. Red light having a peak wavelength of 830 nm is emitted, and the light emission output (P ₀ ) and forward voltage (V _F ) are They were 7.2 mW and 1.4 V, respectively.

Example 4
The light emitting diode of Example 4 was manufactured under the same conditions as Example 1 except that the configuration of the DBR reflective layer was changed.
Specifically, the DBR reflective layer has (Al _0.9 Ga _0.1 ) _0.5 In _0.5 P with a carrier concentration of about 1 × 10 ¹⁸ cm ^{−3 and a} layer thickness of about 54 nm, and a carrier concentration. (Al _0.2 Ga _0.8 ) _0.5 In _0.5 P were alternately stacked in a pair of about 1 × 10 ¹⁸ cm ⁻³ and a layer thickness of about 51 nm.
The results of evaluating the characteristics of this light emitting diode (light emitting diode lamp) are as shown in Table 5. Red light having a peak wavelength of 700 nm is emitted, and the light emission output (P ₀ ) and forward voltage (V _F ) are They were 6.3 mW and 1.4 V, respectively.

(Example 5)
The light-emitting diode of Example 5 was manufactured under the same conditions as Example 1 except that the configuration of the DBR reflective layer was changed.
Specifically, DBR reflective layer was about 1 × ¹⁰ 18 carrier concentration ^{cm -3,} and _Al 0.9 _{Ga 0.1} As that were about 54nm thickness, a carrier concentration of about 1 × ¹⁰ 18 ^{cm -3} 40 pairs of Al _0.3 Ga _0.7 As having a layer thickness of about 50 nm were alternately stacked.
The results of evaluating the characteristics of this light emitting diode (light emitting diode lamp) are as shown in Table 5. Red light having a peak wavelength of 700 nm is emitted, and the light emission output (P ₀ ) and forward voltage (V _F ) are They were 6.4 mW and 1.3 V, respectively.

(Example 6)
The light emitting diode of Example 6 is an example of the second embodiment, and was manufactured as follows.
First, an epitaxial wafer was fabricated by sequentially laminating compound semiconductor layers on a GaAs substrate made of an n-type GaAs single crystal doped with Si. In the GaAs substrate, a plane inclined by 15 ° in the (0-1-1) direction from the (100) plane was used as a growth plane, and the carrier concentration was set to 2 × 10 ¹⁸ cm ⁻³ . The layer thickness of the GaAs substrate was about 0.5 μm. As the compound semiconductor layer, an n-type buffer layer made of GaAs doped with Si, an n-type DBR reflective layer having a 40-pair repeating structure of Si-doped AlInP and GaInP, and Si-doped (Al _0.7 N-type lower cladding layer made of Ga _0.3 ) _0.5 In _0.5 P, lower guide layer made of Al _0.4 Ga _0.6 As, Al _0.17 Ga _0.83 As / (Al _{0 .1} Ga _0.9 ) _0.5 In _0.5 P well layer / barrier layer, Al _0.4 Ga _0.6 As upper guide layer, Mg doped (Al _0.7 Ga _0.3) p-type upper cladding layer composed of _0.5 in _{0.5 P,} an intermediate layer of a thin film made of _{(Al 0.5 Ga 0.5) 0.5 in} 0.5 P, p which is Mg-doped A current spreading layer made of type GaP It was.
The buffer layer made of GaAs has a carrier concentration of about 2 × 10 ¹⁸ cm ⁻³ and a layer thickness of about 0.5 μm. The contact layer had a carrier concentration of about 2 × 10 ¹⁸ cm ⁻³ and a layer thickness of about 3.5 μm. The upper cladding layer had a carrier concentration of about 1 × 10 ¹⁸ cm ⁻³ and a layer thickness of about 0.5 μm. The upper guide layer was undoped and had a thickness of about 50 nm. The well layer is undoped Al _0.17 Ga _0.83 As with a layer thickness of about 7 nm, and the barrier layer is undoped (Al _0.1 Ga _0.9 ) _0.5 In _{0. 5} P. The number of pairs of well layers and barrier layers was set to 5. The lower guide layer was undoped and had a thickness of about 50 nm. The lower cladding layer had a carrier concentration of about 8 × 10 ¹⁷ cm ⁻³ and a layer thickness of about 0.5 μm. The intermediate layer had a carrier concentration of about 8 × 10 ¹⁷ cm ⁻³ and a layer thickness of about 0.05 μm. The current diffusion layer made of GaP has a carrier concentration of about 3 × 10 ¹⁸ cm ⁻³ and a layer thickness of about 9 μm.
The results of evaluating the characteristics of this light emitting diode (light emitting diode lamp) are as shown in Table 5. Red light having a peak wavelength of 700 nm is emitted, and the light emission output (P ₀ ) and forward voltage (V _F ) are They were 6.4 mW and 1.5 V, respectively.

(Example 7)
The light-emitting diode of Example 7 is an example of the second embodiment, and the Al composition X of the well layer is 0.03 and the Al composition X of the barrier layer is 0.2 so that the emission peak wavelength is 830 nm. The light emitting portion was changed to a well layer / barrier layer composed of Al _0.03 Ga _0.97 As / (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P. Furthermore, the thickness of the DBR reflective layer was changed to AlInP with about 64 nm and GaInP with about 60 nm. Others were produced under the same conditions as in Example 6.
The results of evaluating the characteristics of this light emitting diode (light emitting diode lamp) are as shown in Table 5. Red light having a peak wavelength of 830 nm is emitted, and the light emission output (P ₀ ) and forward voltage (V _F ) are They were 7.0 mW and 1.5 V, respectively.

(Comparative Example 1)
An example of a light-emitting diode having a wavelength of 760 nm having a structure in which a thick film is grown and a substrate is removed by a liquid phase epitaxial method is shown.
An AlGaAs layer was grown on a GaAs substrate using a slide boat type growth apparatus.
A p-type GaAs substrate was set in a substrate storage groove of a slide boat type growth apparatus, and Ga metal, GaAs polycrystal, metal Al, and a dopant were put in a crucible prepared for growth of each layer. The growing layer has a four-layer structure of a transparent thick film layer (first p-type layer), a lower clad layer (p-type clad layer), an active layer, and an upper clad layer (n-type clad layer). did.
A slide boat type growth apparatus in which these raw materials are set is set in a quartz reaction tube, heated to 950 ° C. in a hydrogen stream, dissolved, and then the ambient temperature is lowered to 910 ° C. After pressing and bringing into contact with the raw material solution (melt), the temperature is lowered at a rate of 0.5 ° C./min. After reaching the predetermined temperature, the operation of repeatedly touching each raw material solution after pressing the slider is repeated repeatedly. Specifically, after contact with the melt, the atmospheric temperature was lowered to 703 ° C. to grow the n-clad layer, and then the slider was pushed to separate the raw material solution from the wafer to complete the epitaxial growth.

The structure of the obtained epitaxial layer is as follows: the first p-type layer has an Al composition X1 = 0.3 to 0.4, the layer thickness is 64 μm, the carrier concentration is 3 × 10 ¹⁷ cm ⁻³ , and the p-type cladding layer is Al Composition X2 = 0.4 to 0.5, layer thickness 79 μm, carrier concentration 5 × 10 ¹⁷ cm ⁻³ , p-type active layer has a composition with an emission wavelength of 760 nm, layer thickness 1 μm, carrier concentration 1 × 10 ¹⁸ cm ⁻³ , the n-type cladding layer had an Al composition X4 = 0.4 to 0.5, a layer thickness of 25 μm, and a carrier concentration of 5 × 10 ¹⁷ cm ⁻³ .

  After the epitaxial growth was completed, the epitaxial substrate was taken out, the n-type GaAlAs cladding layer surface was protected, and the p-type GaAs substrate was selectively removed with an ammonia-hydrogen peroxide etchant. Thereafter, gold electrodes were formed on both sides of the epitaxial wafer, and a surface electrode in which a wire bonding pad having a diameter of 100 μm was arranged at the center was formed using an electrode mask having a long side of 350 μm. On the back electrode, ohmic electrodes having a diameter of 20 μm were formed at intervals of 80 μm. Thereafter, separation and etching were performed by dicing, so that a 350 μm square light-emitting diode in which the n-type GaAlAs layer was on the surface side was produced.

Table 5 shows the results of mounting the light emitting diode of Comparative Example 1 and evaluating the characteristics of the light emitting diode lamp.
As shown in Table 5, when current was passed between the n-type and p-type ohmic electrodes, infrared light having a peak wavelength of 760 nm was emitted. The forward voltage (V _F ) when a current of 20 mA (mA) was passed in the forward direction was 1.9 volts (V). Further, the light emission output when the forward current was 20 mA was 5.0 mW, which was lower than that of the example of the present invention.

(Comparative Example 2)
Table 5 shows the evaluation results of the light emitting diode in which the active layer was adjusted so that the emission wavelength was 830 nm by the same method as in Comparative Example 2.
As a result of the characteristic evaluation, the light emission output (P ₀ ) and the forward voltage (V _F ) were 6.0 mW and 1.9 V, respectively.

  The light-emitting diode of the present invention emits light with high efficiency, has high reliability, and can be used as a high-power light-emitting diode product that cannot be obtained with an AlGaAs LED manufactured by a conventional liquid phase epitaxial method.

DESCRIPTION OF SYMBOLS 1 ... GaAs substrate 2 ... Buffer layer 3 ... DBR reflection layer 3a ... 1st component layer of DBR reflection layer 3b ... 2nd component layer of DBR reflection layer 5 ... Lower part Cladding layer (first cladding layer)
6 ... Lower guide layer
7 ... Active layer 8 ... Upper guide layer 9 ... Upper clad layer (second clad layer)
10 ... current diffusion layer 12 ... p-type ohmic electrode (first electrode)
13 ... n-type ohmic electrode (second electrode)
DESCRIPTION OF SYMBOLS 20 ... Light emission part 30 ... Compound semiconductor layer 100 ... Light emitting diode

Claims (10)

A light-emitting diode comprising a DBR reflective layer and a light-emitting unit on a substrate in order,
The light emitting portion includes an active layer having a stacked structure of a well layer and a barrier layer having a composition formula (Al _X1 Ga _1-X1 ) As (0 ≦ X1 ≦ 1), and a composition formula (Al _{X2 Ga 1-X2) Y in} 1-Y P; 0 ≦ X2 ≦ 1,0 <Y ≦ 1) comprising a first cladding layer and the second light emitting diode; and a cladding layer. A light-emitting diode comprising a DBR reflective layer and a light-emitting unit on a substrate in order,
The light emitting part includes a well layer having a composition formula (Al _X1 Ga _1-X1 ) As (0 ≦ X1 ≦ 1) and a composition formula (Al _X3 Ga _1-X3 ) _Y2 In _{1 -Y2} P (0 ≦ X3 ≦ 1). , 0 <Y2 ≦ 1) and an active layer having a laminated structure and a composition formula (Al _X2 Ga _1−X2 ) _Y In ₁₋ YP sandwiching the active layer; 0 ≦ X2 ≦ 1, A light emitting diode comprising a first clad layer and a second clad layer of 0 <Y ≦ 1).   In the composition formula of the well layer, the Al composition (X1) is set to 0.20 ≦ X1 ≦ 0.36, the thickness of the well layer is set to 3 to 30 nm, and the emission wavelength is set to 660 to 720 nm. The light-emitting diode according to claim 1 or 2.   In the composition formula of the well layer, the Al composition (X1) is set to 0.1 ≦ X1 ≦ 0.24, the thickness of the well layer is set to 3 to 30 nm, and the emission wavelength is set to 720 to 760 nm. The light-emitting diode according to claim 1 or 2.   In the composition formula of the well layer, the Al composition (X1) is set to 0 ≦ X1 ≦ 0.2, the thickness of the well layer is set to 3 to 30 nm, and the emission wavelength is set to 760 to 850 nm. The light emitting diode according to claim 1.   6. The light emitting diode according to claim 1, wherein the DBR reflective layer is formed by alternately laminating 10 to 50 pairs of two kinds of layers having different refractive indexes. The two types of layers having different refractive indices are composed of two types of (Al _Xh Ga _1-Xh ) _{Y 3} In _{1 -Y 3} P (0 <Xh ≦ 1, Y 3 = 0.5), (Al _Xl Ga _{1− Xl} ) _{Y3In1 -Y3P} ; 0 ≦ Xl <1, Y3 = 0.5), and the difference between the two Al compositions ΔX = xh−xl is greater than or equal to 0.5, The light emitting diode according to claim 6.   The light emitting diode according to claim 6, wherein the two types of layers having different refractive indexes are a combination of GaInP and AlInP. The two types of layers having different refractive indexes are composed of two types of Al _xl Ga _1-xl As (0.1 ≦ xl ≦ 1) and Al _xh Ga _1-xh As (0.1 ≦ xh ≦ 1) having different compositions. The light-emitting diode according to claim 6, wherein the light-emitting diode is a combination, and the difference in composition ΔX = xh−xl between the two Al is greater than or equal to 0.5. 10. The light-emitting diode according to claim 1, further comprising a current diffusion layer on a surface of the light-emitting portion opposite to the DBR reflection layer.

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