JP2001036135A - AlGaInP LIGHT-EMITTING DIODE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniform superior for forward voltage and monochromatism of light emission superior by providing a Bragg reflection layer with an undoped region of a specified range from a surface, in contact with a first conductive type of clad layer. SOLUTION: A Bragg reflection layer 109 used for an A1GaInP light-emitting diode is constituted by a III-V compound semiconductor. For example, a first constituent layer 109a is of AlXGa1-XAs, and a second constituent layer 109b consists of AlYGa1-YAs, whose aluminum composition ratio is larger than it, to form the Bragg reflection layer 109. To provide the Bragg reflection layer 109 with an undoped region of a range 10 nm-100 nm from a surface in contact with a clad layer, a constituent layer of the Bragg reflection layer 109 in contact with the clad layer is undoped. If the Bragg reflection layer 109 is placed on a substrate side below a light-emitting part, a constituent layer of the Bragg reflection layer 109 in contact with the clad layer becomes the outermost layer of the Bragg reflection layer 109.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AlGaInP light-emitting diode having a Bragg reflection layer, and more particularly to a light-emitting diode (LED) having a uniform forward voltage, providing high brightness and excellent monochromatic light emission. And a configuration of a Bragg reflection layer.

[0002]

2. Description of the Related Art One of light emitting devices in the green, yellow to red-orange band is aluminum-gallium-indium phosphide (AlGa) having a pn junction type double hetero (DH) junction structure.
There is an AlGaInP light emitting diode (LED) having a light emitting portion made of InP) (Appl. Phys. Le).
tt. , 61 (15) (1992), 1775-177.
See page 7). In particular, aluminum gallium indium phosphide ((Al _α) having an indium composition ratio of about 0.5
Ga _{1- α} ) _0.5 In _0.5 P, where 0 ≦ α ≦ 1) is lattice-matched with gallium arsenide (GaAs) single crystal (App
l. Phys. Lett. , 57 (27) (199
0), pages 2937 to 2939), which are used for a clad layer and a light emitting layer (active layer) constituting a light emitting portion of a DH junction structure of an AlGaInP light emitting diode (Appl. Phys. Lett., 58 ( 10) (1
991), pages 1010 to 1012).

Further, in a conventional AlGaInP light emitting diode, a Bragg reflection layer ( D istri
butted B rag R reflector: DB
R) (Appl. Phy)
s. Lett. , 63 (25) (1993), 3485.
３４3487). The Bragg reflection layer has a periodic structure in which a multilayer unit structure in which two types of constituent layers having different compositions and layer thicknesses of constituent elements are alternately stacked is periodically stacked.

FIG. 2 is a view showing an example of a cross section of a light emitting portion of a conventional AlGaInPLED having a Bragg reflection layer 109. As shown in FIG. The light emitting unit of FIG. 2 is provided on a substrate (not shown).
Direct or aluminum gallium arsenide (Al _C Ga _1-C
As: 0 ≦ C ≦ 1) and the like. The Bragg reflection layer 109 in FIG. 2 is formed by periodically overlapping first and second constituent layers made of, for example, aluminum / gallium arsenide having different aluminum composition ratios and layer thicknesses. Specifically, a conventional example in which the first constituent layer 109a of the Bragg reflection layer is made of Al _0.5 Ga _0.5 As having an aluminum composition ratio of 0.5 and the second constituent layer 109b is made of aluminum arsenide (AlAs) is known. (Appl. Phys. Lett., 60 (15)
(1992), pp. 1830-1832.). In this case, the forbidden band width of the second constituent layer is larger than the forbidden band width of the first constituent layer.

In the case of a Bragg reflection layer made of a group III-V compound semiconductor, the p-type Bragg reflection layer is composed of first and second constituent layers doped with a group II element such as zinc (Zn) as an acceptor impurity. 109a, 109b
(Appl. Phys. Lett., 6
3 (20) (1993), pages 2732 to 2734). The n-type Bragg reflection layer is composed of a constituent layer doped with silicon (Si) or the like as a donor impurity (see above-mentioned Appl. Phys. Lett., 63 (2)
0) (1993)). Regardless of the p-type or the n-type, it is customary to employ means for doping impurities substantially uniformly in the constituent layers of the conventional Bragg reflection layer.

[0006] However, zinc (Zn) is a p-type impurity that is easily diffused by heat. Therefore, the bonding interface between the cladding layer 103 (or 105) and the Bragg reflection layer 109 tends to be disordered due to the diffusion of zinc. As a result, the cladding layer 1
03 (or 105) and the Bragg reflection layer 109, the discontinuity of the band becomes uneven, and the LED
Has a problem that the forward voltage becomes uneven.

The diffusion of zinc causes the cladding layer 10
Heterojunction interface 103a between 3 (or 105) and light emitting layer 104 also tends to be disordered. Due to the “disordering” of the heterojunction interface, the steepness of the junction interface between the light emitting layer 104 and the cladding layer 103 (or 105) is disturbed, and the monochromaticity of the emission wavelength is impaired.

[0008] Although a problem is caused at a higher temperature than in the case of zinc, it is also known that in the case of Si, "disorder" of the interface occurs due to thermal diffusion of Si. If the heterojunction interface is "messed", the non-uniformity of the forward voltage and the deterioration of the monochromaticity of the light emission are also caused in the case of the Si-doped Bragg reflection layer as in the case of the zinc-doped Bragg reflection layer. It is inevitable.

[0009]

SUMMARY OF THE INVENTION In an AlGaInPLED having a Bragg reflection layer, in order to stably achieve a high luminance, the amount of diffusion of impurities contained in the Bragg reflection layer into the light emitting portion is reduced. Means are needed. The present invention has been made in view of the above problems of the prior art,
An AlGaInPLED having a Bragg reflection layer composed of two types of constituent layers doped with an impurity, having a uniform forward voltage and high brightness.
An object of the present invention is to provide a configuration of a Bragg reflection layer for providing an ED, which reduces the amount of diffusion of an impurity into a light emitting unit.

[0010]

Means for Solving the Problems That is, the present invention relates to II
A multilayer structure in which a first constituent layer made of an IV compound semiconductor and a second constituent layer made of a III-V compound semiconductor having a larger band gap than the first constituent layer are alternately stacked. A first conductivity type Bragg reflection layer made of, and an aluminum-gallium-indium phosphide mixed crystal ((Al _x Ga _{1 -x} ) _0.5 formed with one main surface in contact with the Bragg reflection layer)
In _0.5 P, where 0 ≦ X ≦ 1), a first conductivity type clad layer, and an aluminum / gallium / indium phosphide mixed crystal formed in contact with the other main surface of the first conductivity type clad layer ((Al _Y Ga _1-Y ) _0.5 In _0.5 P, where 0 ≦
AlG comprising at least a light-emitting layer comprising Y ≦ 1)
In the aInP light emitting diode, the Bragg reflection layer is 10n from a surface in contact with the first conductivity type cladding layer.
It has an undoped region in the range of m to 100 nm.

In the present invention, the undoped region can be formed by undoping the constituent layer of the Bragg reflection layer in contact with the first conductivity type cladding layer. Further, it is preferable that the constituent layer of the Bragg reflection layer in contact with the first conductivity type clad layer is formed of a second constituent layer having a larger band gap than the first constituent layer.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A Bragg reflection layer used in an AlGaInP light emitting diode according to the present invention is made of a III-V compound semiconductor. For example, if the first constituent layer is A
l _X Ga _1-X As (where 0 ≦ X ≦ 1), and the second constituent layer is made of Al _Y Ga _1-Y As having a higher aluminum composition ratio.
(Where X <Y ≦ 1), the Bragg reflection layer of the present invention can be formed. In general, the aluminum composition ratio (= Y) of the second constituent layer is preferably 0.9 or more and 1 or less. The first constituent layer is gallium arsenide (GaAs), and the second constituent layer is aluminum gallium indium phosphide ((Al _α Ga _{1- α} ) _0.5 I).
n _0.5 P: 0 ≦ α ≦ 1) can also constitute the Bragg reflection layer according to the present invention.

In the present invention, the Bragg reflection layer has an undoped region in the range of 10 nm to 100 nm from the surface in contact with the cladding layer. For this purpose, in the Bragg reflection layer of the present invention, the constituent layer of the Bragg reflection layer in contact with the cladding layer may be undoped. In the AlGaInP light emitting diode, the thickness of the constituent layer of the Bragg reflection layer is generally 10 nm to 10 nm.
It is in the range of 0 nm. When the Bragg reflection layer is disposed on the substrate side below the light emitting section, the constituent layer of the Bragg reflection layer that is in contact with the cladding layer is the outermost layer of the Bragg reflection layer. Further, when the Bragg reflection layer is disposed above the light emitting section, the layer in contact with the cladding layer is the bottom layer of the Bragg reflection layer. As shown in FIG. 2, a lower Bragg reflection layer 109A having a six-period structure and an upper Bragg reflection layer 10 having a three-period structure are provided below and above the light-emitting layer 104 via a lower cladding layer 103 and an upper cladding layer 105, respectively.
There is also an arrangement method in which 9B is provided. In this arrangement, the constituent layer of the Bragg reflection layer in contact with the lower and upper cladding layers 103 and 105 is the outermost layer 1 of the lower Bragg reflection layer 109A.
09c and the bottom layer 109d of the upper Bragg reflection layer 109B
It becomes both.

The dopant concentration in the undoped constituent layer of the Bragg reflection layer according to the present invention is as-gro
In the wn state, it is desirably smaller than the constituent layers of other Bragg reflection layers doped with impurities. The concentration of the impurity in the undoped constituent layer after film formation increases as the impurity easily diffuses. Therefore, in order to suppress the disorder of the bonding interface between the cladding layer and the Bragg reflection layer from being promoted, the larger the diffusion constant of the dopant, the larger the as-g
The concentration of the dopant in the undoped constituent layer in the row state is reduced in advance. For example, in a p-type Bragg reflection layer doped with zinc (Zn), the atomic concentration of zinc in the as-grown state of the undoped constituent layer is about 1/1 of the constituent layers of the other Bragg reflective layers. It is desirable to set it to 10 or less. For example, if the zinc atom concentration of the zinc-doped constituent layer of the Bragg reflection layer is 1 × 10 ¹⁸ cm ⁻³ , the zinc atom concentration of the undoped constituent layer in the as-grown state is 1 × 10 ¹⁷ cm ^{−3. It} is preferred to be less than ^-3 . Magnesium (Mg) doped p
In the case of a Bragg reflection layer of a shape, the magnesium atom concentration of the undoped constituent layer is preferably about 1/5 or less of the other constituent layers. The dopant is silicon (Si) or carbon (C)
In the case of the Bragg reflection layer which is
It is desirable that the concentration of these atoms in the s-grown state be about 1/2 or less of the constituent layers of the doped Bragg reflection layer. The undoped constituent layer of the Bragg reflection layer can be formed by intentionally stopping the addition of impurities in the constituent layer when forming the Bragg reflection layer. The atomic concentration of the dopant in the Bragg reflection layer can be measured by general secondary ion mass spectrometry (abbreviation: SIMS) or Auger electron spectroscopy (abbreviation: AES).

When the constituent layer of the Bragg reflection layer which is in contact with the cladding layer is constituted by an undoped layer, the dopant in the reflection layer which diffuses into and penetrates the cladding layer and the light emitting layer is efficiently captured and stopped in the undoped layer. There are advantages to be made. The lower the atomic concentration of the dopant species in the undoped layer, the higher the concentration of the trapped and retained dopant. If the atomic concentration of the dopant is kept low,
This is because the permissible catch amount increases. However, the undoped constituent layer is a high-resistance layer as compared with other constituent layers doped with impurities to increase conductivity. Therefore,
If the thickness of the undoped constituent layer is increased, the amount of the diffused impurities that can be trapped increases, but if the thickness is excessively large, the forward voltage increases. The thickness of the undoped region suitable for efficiently capturing the diffused doping impurities and avoiding an unnecessary increase in the forward voltage is 10 nm or more and 100 nm or less. In a Bragg reflection layer having a periodic laminated structure of first and second types of constituent layers,
If the total layer thickness of the first and second constituent layers close to the cladding layer is 100 nm or less, both the first and second constituent layers close to the cladding layer may be undoped. . That is, in the present invention, if the Bragg reflection layer has an undoped region in the range of 10 nm to 100 nm from the surface in contact with the cladding layer, the dopant in the reflection layer that diffuses and enters the cladding layer and the light emitting layer is undoped. Can be efficiently captured and arrested in the area.

The undoped region in contact with the cladding layer in the Bragg reflection layer has an effect of suppressing the amount of impurities flowing into the cladding layer and the light emitting layer. This suppresses "disorder" at the heterojunction interface between the Bragg reflection layer and the cladding layer. In addition, the steepness of the heterojunction interface between the light emitting layer and the cladding layer is maintained. As a result, the forward voltage of the LED becomes uniform, and light emission with high luminance and excellent monochromaticity is provided. Note that, as described above, the “undoped region” to “undoped constituent layer” of the Bragg reflection layer according to the present invention are intended to intentionally add impurities to the region or the constituent layer when the Bragg reflection layer is formed. Stopping, making the concentration of the impurity in the region or the constituent layer smaller than the region or the constituent layer of the other Bragg reflection layer doped with the impurity, and diffusing the impurity into the cladding layer or the light emitting layer.
It refers to a region or a constituent layer capable of capturing and retaining impurities in the reflecting layer that have entered.

Further, in the present invention, the constituent layer of the Bragg reflection layer in contact with the cladding layer is preferably formed of the second constituent layer, that is, a constituent layer having a larger band gap than the first constituent layer. . For example, a GaAs layer and (Al _α G
a _{1- α} ) _0.5 In _0.5 P (0 ≦ α ≦ 1) layer, the (Al _α Ga _{1- α} ) _0.5 I
The n _0.5 P layer is a constituent layer in contact with the cladding layer. Also,
The constituent layers of the Bragg reflection layer are made of different aluminum compositions.
In the case of using AlGaAs layers of different types, an AlGaAs layer having a higher aluminum composition ratio is a constituent layer in contact with the cladding layer.

If the constituent layer having the larger bandgap among the constituent layers of the Bragg reflection layer is disposed in contact with the cladding layer, the difference in the bandgap between the Bragg reflection layer and the cladding layer causes the bandgap to be reduced. The size is reduced as compared with the case where the constituent layers to be small are arranged. For this reason, it is possible to obtain an effect that the forward voltage can be reduced in addition to the uniform forward voltage.

[0019]

When the constituent layer of the Bragg reflection layer in contact with the cladding layer is undoped, impurities doped in other constituent layers of the Bragg reflection layer diffuse into the cladding layer and the light emitting layer.
Has the effect of reducing intrusion.

As a result, it is possible to prevent disorder of the junction interface between the Bragg reflection layer and the cladding layer or between the cladding layer and the light emitting layer due to impurities diffused from the Bragg reflection layer.

Further, when the constituent layer of the Bragg reflection layer in contact with the cladding layer is a constituent layer having a larger band gap, the difference in the band gap at the interface between the Bragg reflection layer and the cladding layer is reduced. This has the effect of making the forward voltage uniform and reducing it.

[0022]

EXAMPLES (Example 1) Hereinafter, the present invention will be described in detail based on examples. FIG. 1 is a schematic sectional view of an LED according to the first embodiment.

(100) inclined by 4 ° in the [110] direction
On a Zn-doped p-type GaAs substrate 101 having a surface,
General reduced-pressure organometallic vapor phase using trimethylaluminum ((CH ₃ ) ₃ Al), trimethylgallium ((CH ₃ ) ₃ Ga) and trimethylindium ((CH ₃ ) ₃ In) as raw materials for group III constituent elements Epitaxy method (MOVP
E method), at 720 ° C., zinc (Zn) -doped p-type G
The aAs buffer layer 102 was laminated. p-type GaAs buffer layer 1
02 has a thickness of about 0.8 μm and a hole concentration of about 3 × 10
¹⁸ cm ^-3 .

Next, a Bragg reflection layer 109 was laminated on the buffer layer 102 at 720 ° C. In forming the Bragg reflection layer 109, Zn with an Al composition ratio of 0.45 was used.
Doped p-type Al _0.45 Ga _0.55 As layer and Zn-doped p-type Al _0.90 Ga _0.10 As with Al composition ratio of 0.90
The layers were first overlaid alternately for four periods. Al _0.45 Ga _0.55 A
The thickness of the first constituent layer 109a of the Bragg reflection layer made of the s layer was about 42 nm, and the thickness of the second constituent layer 109b of the Bragg reflection layer made of the Al _0.90 Ga _0.10 As layer was about 49 nm. The hole concentration of each of the first and second constituent layers 109a and 109b doped with Zn was about 1 × 10 ¹⁸ cm ⁻³ . Further, the above-mentioned constituent layer 109
a, the concentration of zinc atoms in 109b is about 3 × 10 ¹⁸ c
m ^-3 . Then, unintentionally doped zinc, undoped that the layer thickness and 42nm Al _{0. 45} Ga _0.55 As
The first constituent layer made of
It was laminated as c. As in the undoped first constituent layer
According to SIMS analysis, the atomic concentration of zinc in the -grown state was less than 2 × 10 ¹⁷ cm ⁻³ , and the hole concentration was about 9 × 10 ¹⁶ cm ⁻³ .

Mg is doped on the Bragg reflection layer 109.
P-type (Al_0.7Ga_0.3) _0.5In_0.5From P
The lower clad layer 103 thus formed was laminated. Lower cladding layer
103 has a thickness of about 0.8 μm and a hole concentration of about 3 × 1
0¹⁸cm^-3And On the p-type lower cladding layer 103,
Undoped n-type (Al_0.2Ga_0.8)_0.5In_0.5P mixed
The light emitting layer 104 made of a crystal was laminated. Layer of light emitting layer 104
The thickness is about 100 nm, and the electron concentration is about 8 × 10¹⁶cm^-3
 And On the light-emitting layer 104, an Si-doped n-type
(Al_0.7Ga_0.3)_0.5In_0.5Upper cladding made of P
Layer 105 was laminated. Electron concentration of upper cladding layer 105
Is about 3 × 10¹⁷cm^-3And the layer thickness was about 5 μm.

Further, on the upper cladding layer 105,
The electron concentration of highly doped i is about 7 × 10 ¹⁸ c
n ⁻³ (Al _0.7 Ga
_0.3) a laminate of a contact layer 106 made of _{0. 5} In _0.5 P.

On the contact layer 106, aluminum
Window layer 10 made of n-type zinc oxide doped with (Al)
7 was formed. The zinc oxide film forming the window layer 107 is made of Al
Solid molding material consisting of zinc oxide containing 5% by weight of minium
(Pellets) formed by sputtering method
did. The specific resistance of the n-type zinc oxide film is Hal (Hal
1) According to the effect measurement method, about 1.4 × 10^-3Ω · cm,
The electron concentration is about 3.3 × 10 ²⁰cm^-3And move the hall
The degree is 14cm^Two/ V · s. Also, zinc oxide coating
Was about 200 nm.

An aluminum (Al) electrode 108 is formed on the window layer 107, and a p-type ohmic electrode 110 is formed on the entire back surface of the p-type GaAs substrate 101 to form an LED.
Was prepared. When a current of 20 mA was passed through the LED in the forward direction, red-orange light having a wavelength of about 621 nm was transmitted through almost the entire surface of the zinc oxide window layer 107 and emitted. The full width at half maximum (FWHM) of the emission spectrum is about 18 n
m and was excellent in monochromaticity. In addition, the current is 20 mA
The forward voltage in this case was in the range of about 1.98 V to 2.08 V, and a uniform forward voltage was obtained between the LEDs. The light emission intensity of the LED was about 60 mcd.

For the LED of the first embodiment, a general S
When the zinc (Zn) atom concentration distribution in the depth direction was analyzed by IMS analysis, after forming the LED, the zinc in the undoped first constituent layer which is the outermost layer 109c of the Bragg reflection layer 109 was formed. Atomic concentration is about 1 × 10
^An increase to ¹⁸ cm ^-3 was observed. However, the concentration of zinc (Zn) diffused into the light emitting layer 104 was significantly reduced. That is, the atomic concentration of zinc (Zn) in the light emitting layer 104 was about 7 × 10 ¹⁶ cm ⁻³ . Further, as a result of observation by a transmission electron microscope (TEM), the arrangement of the undoped first constituent layer indicates that the junction interface between the Bragg reflection layer 109 and the lower cladding layer 103 and the junction between the lower cladding layer 103 and the light emitting layer 104 The interface was not disordered and flatness was maintained. From these, it is considered that the uniformed forward voltage and high-brightness light emission excellent in monochromaticity as described above were provided.

Example 2 Also in Example 2, an LED having the same structure as the LED shown in FIG. 1 was manufactured. First, a p-type GaAs substrate 10 is formed by MOVPE in the same manner as in the first embodiment.
On top of this, a p-type GaAs buffer layer 102 was deposited, and a Bragg reflection layer 109 was further formed thereon. The Bragg reflection layer 109 includes a Zn-doped p-type Al _0.45 Ga _0.55 As layer 109a having an Al composition ratio of _0.45 and a Zn-doped p-type Al _0.90 Ga _0.10 As having an Al composition ratio of 0.90.
The layer 109b was alternately formed with four layers. Al
The thickness of the first constituent layer 109a made of a _0.45 Ga _0.55 As layer was about 42 nm, and the thickness of the second constituent layer 109b made of an Al _0.90 Ga _0.10 As layer was about 49 nm. Constituent layers 109a and 109b of Bragg reflection layer 109
Was about 1 × 10 ¹⁸ cm ⁻³ in both cases. Further, in the second embodiment, a second component layer made of undoped Al _0.90 Ga _0.10 As having a layer thickness of 49 nm was laminated as the outermost layer 109c of the plug reflection layer. Zinc atomic concentration in as-grown state of the internal second constituent layer of undoped are 8 × less than 10 ¹⁶ cm ^-3 According to SIMS analysis, In addition, the hole concentration is about 5 × 10 ¹⁶ cm ^- Estimated to be ³ .

On the above Bragg reflection layer 109, an
P-type (Al_0.7Ga_0.3) _0.5In_0.5From P
The lower cladding layer 103 made of undoped n-type (Al
_0.2Ga_{0 .8})_0.5In_0.5A light emitting layer 104 made of a P mixed crystal,
And n-type (Al_0.7Ga_0.3)_0.5In_0.5Upper part consisting of P
Cladding layer 105, n-type (Al_0.7Ga_0.3)_0.5In_0.5
The contact layers 106 made of P were sequentially laminated. Ma
In addition, on the contact layer 106, aluminum (Al)
A window layer 107 made of doped n-type zinc oxide was formed.
The zinc oxide film that forms the window layer 107 is made of aluminum in five layers.
Solid molding material (pellet) composed of zinc oxide containing
It was formed by a sputtering method as a raw material. n-type oxidation
According to the Hall effect measurement method, the specific resistance of zinc is
About 1.4 × 10^-3Ω · cm, electron concentration is about 3.3 × 1
0²⁰cm ^-3And the hole mobility is 14 cm^Two/
V · s. The layer thickness was about 200 nm.

Further, on the window layer 107, aluminum (A
1) forming an electrode 108 and a p-type ohmic electrode 110 on the entire back surface of the p-type GaAs substrate 101 to form an LED
Was prepared. When a current of 20 mA was passed through the LED in the forward direction, red-orange light having a wavelength of about 620 nm was transmitted through almost the entire surface of the zinc oxide window layer 107 and emitted. Further, the full width at half maximum (FWHM) of the emission spectrum was about 18 nm, and light emission excellent in monochromaticity was provided.
The forward voltage when the current was 20 mA was in the range of about 1.91 V to 1.98 V, and a lower forward voltage than in Example 1 was obtained. Further, the light emission intensity reached about 65 mcd.

For the LED of the second embodiment, a general S
When the distribution of zinc (Zn) atom concentration in the depth direction was analyzed by IMS analysis, after the LED was formed, the zinc atom in the undoped second constituent layer which was the outermost layer 109c of the Bragg reflection layer was formed. Concentration is about 8 × 10 ¹⁷ cm
Increased to ^-3 . However, the light emitting layer 10
The concentration of zinc (Zn) diffusing into No. 4 was significantly reduced.
That is, the atomic concentration of zinc (Zn) in the light emitting layer 104 was about 5 × 10 ¹⁶ cm ⁻³ . In addition, as a result of observation by a transmission electron microscope (TEM), the bonding interface between the Bragg reflective layer 109 and the lower cladding layer 103 and the bonding interface between the lower cladding layer 103 and the light emitting layer 104 are determined by the arrangement of the undoped second constituent layer. Was not cluttered and flatness was maintained. From these, it is considered that the uniformed forward voltage and high-luminance light emission excellent in the above monochromaticity were provided.

[0034]

According to the present invention, it is possible to prevent the junction interface of the light emitting portion from being disordered due to the diffusion of the dopant impurity.
A high-luminance AlGaInP light-emitting diode having excellent forward voltage uniformity and excellent monochromaticity of light emission can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an LED according to Examples 1 and 2 of the present invention.

FIG. 2 shows a conventional AlGaIn having a Bragg reflection layer.
It is a schematic diagram which shows the cross section of the light emitting part of P light emitting diode.

[Explanation of symbols]

 Reference Signs List 101 GaAs substrate 102 GaAs buffer layer 103 Lower cladding layer 103a Heterojunction interface between cladding layer and light emitting layer 104 Light emitting layer 105 Upper cladding layer 106 Contact layer 107 Window layer 108 Aluminum electrode 109 Bragg reflection layer 109A Lower Bragg reflection layer 109B Upper Bragg Reflective layer 109a First constituent layer of Bragg reflective layer 109b Second constituent layer of Bragg reflective layer 109c Top layer of Bragg reflective layer 109d Bottom layer of Bragg reflective layer 110 p-type ohmic electrode

Claims (3)

[Claims] 1. A first constituent layer made of a group III-V compound semiconductor, and II having a larger band gap than the first constituent layer.
A first-conductivity-type Bragg reflection layer having a multilayer structure in which second constituent layers made of an IV group compound semiconductor are alternately stacked, and a phosphide formed with one main surface in contact with the Bragg reflection layer Aluminum-gallium-indium mixed crystal ((A
l _X Ga _1-x ) _0.5 In _0.5 P, where 0 ≦ X ≦ 1), and a phosphorus formed in contact with the other main surface of the first conductivity type cladding layer. Aluminum chloride
Gallium-Indium mixed crystal ((Al _Y Ga _1-Y ) _0.5 In
_0.5 P, where in 0 ≦ Y ≦ 1) a light emitting layer and at least including for AlGaInP light emitting diode, the Bragg reflection layer, wherein the first conductivity type from the surface in contact with the cladding layer 10nm to 100nm range undoped in An AlGaInP light-emitting diode having a region. 2. The AlGaInP light-emitting diode according to claim 1, wherein the constituent layer of the Bragg reflection layer in contact with the first conductivity type cladding layer is undoped. 3. The AlGaInP light-emitting diode according to claim 2, wherein a constituent layer of a Bragg reflection layer in contact with said first conductivity type cladding layer comprises said second constituent layer.