JP3139890B2 - Semiconductor light emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device, and more particularly, to a high-brightness light emitting diode (LED) having a structure in which light is prevented from being absorbed by an upper electrode and light can be effectively extracted. Semiconductor light-emitting device.

[0002]

2. Description of the Related Art In recent years, in order to increase the brightness of a surface emitting semiconductor light emitting device such as an LED, a Bragg is provided between a pn junction of a semiconductor light emitting device having a double hetero structure and a substrate.
A semiconductor light emitting device having a configuration in which a light reflecting layer is provided, in which light directed toward the substrate out of light emitted at the pn junction is reflected toward the light extraction surface by the Bragg light reflecting layer, so that light can be efficiently extracted. Devices are known.

FIG. 7 is a sectional view showing the structure of the above-mentioned conventional semiconductor light emitting device. In the figure, H denotes a semiconductor light emitting device, and a flat Br is formed on a semiconductor substrate 1 of the first conductivity type.
agg light reflection layer 2, first conductivity type semiconductor cladding layer 3,
Semiconductor active layer 4 and semiconductor cladding layer 5 of second conductivity type
Are provided with a thickness of the order of 0.01 to several tens μm. In the semiconductor light emitting device H, the first
A pn junction X to be a light emitting layer is formed by the conductive type semiconductor clad layer 3 and the semiconductor active layer 4, and an upper electrode 6 is formed on the surface (light extraction surface) A of the second conductive type semiconductor clad layer 5.
On the other hand, a lower electrode 7 is provided on the back surface of the substrate 1.

According to the above structure, when a driving current flows between the upper electrode 6 and the lower electrode 7, light is emitted at the pn junction X. Of the light emission, light traveling toward the light extraction surface A is emitted from the light extraction surface A. On the other hand, light traveling toward the substrate 1 is reflected by the flat light reflection layer 2 toward the light extraction surface A, and this light is also emitted from the light extraction surface A. Therefore, light emitted at the pn junction X can be extracted to the outside of the device without being absorbed by the substrate 1, and the brightness of the semiconductor light emitting device H can be improved.

[0005]

However, the light traveling toward the light extraction surface A is transmitted to the upper electrode 6 formed on the light extraction surface A.
Is absorbed as an obstacle (shadow portion), so that the amount of light that can be extracted outside the light emitting element is reduced, and there is a problem that the luminance of the semiconductor light emitting element H cannot be sufficiently improved. As described above, the structure of the semiconductor light emitting device in which the light reflecting layer is provided between the substrate and the pn junction also has a limit in increasing the brightness of the semiconductor light emitting device. Development is strongly desired. Therefore, various improvements have been proposed in response to the demands of the market, but at present the light emitting element having such high luminance has not been developed yet.

An object of the present invention is to provide a semiconductor light emitting device such as an LED which can solve the above-mentioned problems and efficiently take out light emitted from a pn junction to the outside of the device and can achieve high luminance. is there.

[0007]

A semiconductor light emitting device that achieves the above object has a pn junction on a semiconductor substrate,
a first light reflection layer on the substrate side as viewed from the n-junction, and an upper electrode
A second light-reflecting layer on the side, and the first and second light
Shape that reflective layer can reduce optical resonance phenomenon by retroreflection
It is characterized by that. Preferably p
A semiconductor layer having a band gap wider than the band gap of the light emitting layer formed on the pn junction is provided between the n junction and the second light reflection layer.

[0008] The semiconductor light emitting device of the present invention comprises
In a semiconductor light emitting device having a configuration in which a light reflection layer is provided between an n-junction and a substrate,
A second light reflection layer is formed. FIG.
FIG. 3 is a schematic cross-sectional view illustrating a structure of the semiconductor light emitting device. In the following description, the same parts as those in FIG. In FIG. 1, a semiconductor light emitting device H1 includes a light reflecting layer 2, a semiconductor cladding layer 3, a semiconductor active layer 4, and a semiconductor cladding layer 5 on a semiconductor substrate 1.
Are sequentially laminated. In the semiconductor light emitting device H1, a pn junction X to be a light emitting layer is formed by the cladding layer 3 and the active layer 4, and the upper electrode 6 is formed on the light extraction surface A of the semiconductor cladding layer 5; A lower electrode 7 is provided on the back surface of the substrate 1. Further, in the present invention, a second light reflection layer 8 is formed immediately below the upper electrode between the light extraction surface A and the upper electrode 6.

According to the semiconductor light emitting device H1 having the above structure,
When the pn junction X emits light, light traveling toward the light extraction surface A is emitted from the light extraction surface A. On the other hand, light traveling toward the substrate 1 is reflected by the flat light reflection layer 2 toward the light extraction surface A, and this light is also emitted from the light extraction surface A. Part of the light traveling toward the light extraction surface A is
It goes to the upper electrode 6 on the light extraction surface A. However, since the second light reflecting layer is formed immediately below the upper electrode 6, light traveling toward the upper electrode 6 is reflected. Thus, the light traveling toward the upper electrode 6 is
Is prevented from being absorbed into the semiconductor light emitting device H, the light emitted from the pn junction X can be extracted to the outside of the device without waste, and the brightness of the semiconductor light emitting device H is improved. become.

[0010] In the semiconductor light emitting device of the present invention, the semiconductor material constituting the substrate is not particularly limited.
Any material used as a substrate material such as ED can be suitably used. Specific examples thereof include InP-based, GaAs
s system, GaP system, AlGaAs system, GaInP system, Ga
Various p-type or n-type semiconductors such as an InAs type are exemplified.

The first light reflection layer 2 formed on the substrate 1 may be any layer that can reflect light emitted at the pn junction X. In many cases, the full width at half maximum of the emission spectrum has a range of about 30 to 80 meV, that is, since the emission wavelength is wide, the reflection wavelength band is desirably as wide as possible.

The light reflecting layer is a Br having a multilayer structure made of two or more materials having different refractive indexes.
There is an agg reflective layer, a reflective layer having a large number of holes for maintaining electrical continuity made of a conductive semiconductor material or an insulating film, and the like, but can be formed during an epitaxial growth process such as MOCVD. It is preferable that the Bragg reflection layer has good controllability of the film thickness.

The Bragg reflection layer is composed of one layer having a specific refractive index n and a thickness d (d = λ / 4n; λ is the center emission wavelength of the light-emitting layer). It is composed of a pair with another layer having a different refractive index.
In order to increase the reflectance, a plurality of the above pairs may be formed. Further, in order to widen the reflection bandwidth, a plurality of pairs having different refractive indices from the above-mentioned pairs or a plurality of pairs having different thicknesses may be formed. Generally Bragg
The reflective layer is composed of 2 to 200 pairs of the above pairs, usually 4 to 60 pairs.
It is formed by laminating a pair. In this case, it is preferable to provide the reflective layer so that the center wavelength λ gradually increases in the direction away from the light emitting unit.

The Bragg reflection layer having the above structure reflects light by wavelength selectivity at which light of a specific wavelength has a maximum reflectance, that is, light interference. Specifically, for example, GaAs having a refractive index of 3.65 and Ga _0.4 having a refractive index of 3.42 _.
5 Al _0.5 As and GaAs (thickness 43 nm) / Ga
If a pair of _0.5 Al _0.5 As (having a thickness of 46 nm) or a plurality of pairs is formed as described above, a light reflection layer in the 630 nm band can be formed.

The cladding layers 3 and 5 and the active layer 4 formed on the first light reflecting layer 2 are specifically made of AlGaIn, for example, when a GaAs substrate is used.
P, GaInP and / or AlGaAs can be used. When a GaP substrate is used, AlGaP can be used. When an InP substrate is used, InGaAs
P can be used. Further, when a GaN substrate is used, AlGaN can be used. In addition, GaP substrates and G
ZnSeS, ZnCdSe, MgZnS on aAs substrate
A structure in which eS is grown by MBE or the like can also be used. In the above configuration, the upper surface of the cladding layer 5 becomes the light extraction surface A of the semiconductor light emitting device.

The second light reflection layer 8 is formed on the light extraction surface A
And the upper electrode 6. The second light reflection layer 8 only needs to have a shape and a size capable of substantially reflecting the light traveling toward the upper electrode 6 out of the light traveling toward the light extraction surface A,
Although it may be slightly larger or smaller than the bottom area of the upper electrode 6, if it is made approximately the same size in plan view as the upper electrode 6 and is provided immediately below the upper electrode 6, light directed to the upper electrode 6 is surely transmitted. It is preferable because it can be reflected. This second
Is formed in the same manner as the first light reflecting layer.

The light reflecting layer and the semiconductor layer are obtained by epitaxially growing each material on a semiconductor substrate. As this epitaxial growth method, for example, MOCVD
A known method such as the MBE method, the LPE method, or the like can be used.

The upper electrode 6 is formed on the second light reflection layer. On the other hand, the lower electrode 7 is formed on the back surface of the semiconductor substrate 1. As the electrode material, AuBe, A
uSn, AuGe, AuZn or the like is used, and the electrodes are formed by a method such as vacuum evaporation or sputtering.
The structure of the semiconductor light emitting device of the present invention is a Homo type,
Single hetero (SH) type, double hetero (DH) type,
And a quantum well structure. In particular, in the DH type, the cladding layers grown above and below the active layer serving as the light emitting portion do not absorb the light, the injected carriers are effectively confined, the luminous efficiency is increased, and the luminance of the light emitting element can be further improved. preferable.

In the present invention, as shown in the schematic cross-sectional view of FIG. 3, between the cladding layer 9 and the second light reflecting layer 8,
Compound semiconductor layer 10 having a band gap wider than that of the light emitting layer so as not to absorb the emitted light
Can be formed as a current spreading layer. As this compound semiconductor, a known III-V group (GaAs, Ga
P, InP, GaAlAs, GaAlP, etc.), IV-IV group (SiC), I-III -VI 2 group (CuInSe _2, Cu
GaSe ₂ , AgGuS ₂ etc.) can be used.
The layer 10 can be formed by a method such as the D method, the LPE method, the MBE method, the ALE method, and the MOVPE method.

According to the structure in which the compound semiconductor layer 10 is formed, the current injected from the upper electrode 6 effectively reduces the pn
Light emission can be obtained at the entire pn junction, extending to the junction X, and the problem that the luminous efficiency is reduced by partial carrier injection into the active layer immediately below the electrode when the cladding layer 9 is thin can be solved.

The semiconductor layer 10 is used as a substitute for a substrate, a pn junction and a first light reflection layer are grown thereon, and a second light reflection layer is grown on the opposite surface. The light-emitting element can also be configured by using The semiconductor layer 10 is particularly preferably GaP, which has characteristics of easy epitaxial growth, easy formation of a thick layer, and wide band gap.

In the present invention, the first and second light reflecting layer, light reflected by the upper Symbol first or second light reflecting layer is retroreflective to the second or first light reflecting layer because it may occur optical resonance Te, it shall be the reflection layer shape light is not retroreflected. As the shape of such a light reflecting layer, in the flat light reflecting layer, unevenness is formed on the surface, and the light reflecting layer is formed, for example, in a gable roof shape shown in FIG. 4, a pyramid shape shown in FIG. What is necessary is just to form in the three-dimensional shape in which the slope part S, such as a dome shape shown, is formed. According to the configuration of the light reflection layer, light is not retroreflected, so that an optical resonance phenomenon can be avoided, and light can be effectively extracted, which is preferable.

The light reflecting layer having a three-dimensional shape having the above-mentioned inclined surface is formed by previously patterning the growth substrate by photolithography and performing anisotropic etching by wet or dry to process the substrate surface into a desired shape. ,
Alternatively, it can be formed by growing an epitaxial layer having a crystal plane different from the crystal plane of the substrate on the substrate surface by selective growth using MBE or MOCVD.

[0024]

As described above, according to the semiconductor light emitting device of the present invention, the light directed toward the upper electrode can be reliably reflected, and the absorption of the light by the upper electrode is greatly suppressed. To be taken out. In addition, since the light reflecting layer has a shape that does not cause retroreflection, light is prevented from resonating in the first and second light reflecting layers, and light can be efficiently extracted outside the element. . Therefore,
In the semiconductor light emitting device of the present invention, light emitted at the pn junction can be effectively extracted outside the device without waste,
The light emitting element has high luminance which is significantly improved in luminance as compared with the conventional light emitting element. Further, when a compound semiconductor layer having a wide band gap is formed between the light extraction surface and the second light reflection layer, the current is effectively diffused, the light emitting area is enlarged, and the luminance is improved. Become.

[0025]

The present invention will be described in more detail with reference to the following examples. Example 1 FIG. 1 is a schematic cross-sectional view showing a configuration of a semiconductor light emitting device according to one example. This semiconductor light emitting device H1 has n-type Ga
On As substrate 1, the GaAs layer and the Al _0.45 Ga _{0. 55} first light reflecting layer 2 of n-type comprising a many-to-laminate of the As layer, n-type on the first light reflecting layer 2 An AlGaInP cladding layer 3, a p-type GaInP active layer 4 on this cladding layer 3, and a p-type AlGaInP cladding layer 5 on this active layer 4 are sequentially laminated. On the surface A, an upper electrode 6 made of AuBe is formed via a p-type second light reflection layer 8 having the same structure as that of the first light reflection layer. On the back surface of the n-type GaAs substrate 1, a lower electrode 7 made of AuSn is formed.

The semiconductor light emitting device H1 was manufactured as follows. That is, an n-type GaAs buffer layer having a thickness of 0.2 μm is epitaxially grown on an n-type GaAs substrate 1 having a thickness of 350 μm.
Each source gas of _0.45 Ga _0.55 As was alternately supplied onto the substrate 1, and 20 pairs of GaAs layers and Al _0.45 Ga _0.55 As layers were alternately laminated to form a reflection layer. In order to widen the reflection bandwidth, the GaAs layer should be 44 to 4
The thickness of the 9 nm Al _0.45 Ga _0.55 As layer was changed in the range of 48 to 53 nm. Then, an n-type AlGaInP cladding layer 3 having a thickness of 3 μm, an n-type GaInP active layer 4 having a thickness of 1 μm, and a p-type AlGaInP cladding layer 5 having a thickness of 10 μm were sequentially grown on the first light reflection layer 2. This composition was prepared so as to lattice match with GaAs and to have a band gap corresponding to 650 nm. Further, on the light extraction surface A of the p-type AlGaInP cladding layer 5, a thickness of 1.9 μm having the same structure as that of the first light reflection layer is provided.
Then, after forming a p-type second light reflection layer, AuBe is vacuum-deposited on the second light reflection layer 8, a patterning process is performed, and further, an etching process is performed on the light extraction surface. A circular second light reflection layer 8 having a diameter of 100 μm and an upper electrode 6 were formed substantially at the center of A. On the other hand, after AuSn is vacuum-deposited on the back surface of the wafer (substrate) to form the lower electrode 7, the wafer is diced into chips,
A semiconductor light emitting device H having a light extraction surface of 350 μm × 350 μm was manufactured.

Comparative Example 1 A semiconductor light emitting device H having the structure shown in FIG. 7 was manufactured in the same manner as in Example 1 except that the second light reflecting layer 8 was not provided.

Embodiments 2 to 4 In the semiconductor light emitting device of Embodiment 1 described above, the shape of the first light reflection layer 2 was changed to a gable roof shape shown in FIG. 4 (Example 2) and a pyramid shape shown in FIG. Example 3) A semiconductor light emitting device was manufactured in the same manner except that the semiconductor light emitting device was dome-shaped as shown in FIG. 6 (Example 4) and was formed in a three-dimensional shape having a slope S. The first three-dimensional shape having the slope S
The light reflecting layer 2 was manufactured as follows. That is, the growth substrate was previously patterned using photolithography, anisotropically etched by wet or dry, and the substrate surface was processed into a desired shape. Alternatively, it can be formed by growing an epitaxial layer having a crystal plane different from the crystal plane of the substrate on the substrate surface by selective growth using MBE or MOCVD.

(Light Emitting Test) A current of 20 mA was passed between the upper electrode and the lower electrode to cause each of the semiconductor light emitting devices obtained in Examples 1 to 4 and Comparative Example 1 to emit light. The luminance at that time was measured using a luminance meter (Photometer Model 550-1E).
G & G), and the results shown in Table 1 were obtained.

[0030]

[Table 1]

As is evident from Table 1, the semiconductor light-emitting device of the example has a brightness improved by about 50% as compared with that of the comparative example.

Embodiment 5 FIG. 2 is a schematic sectional view showing the structure of a homo-type semiconductor light emitting device according to another embodiment. This homo-type semiconductor light emitting device H
Reference numeral 2 denotes an n-type first reflective layer 2 comprising a GaAs buffer layer (not shown), a multi-layered stack of a GaAs layer and an Al _0.45 Ga _0.55 As layer on an n-type GaAs substrate 1, An n-type AlGaInP layer 3 is laminated on the first reflective layer 2 and a p-type AlGaInP layer 4 is sequentially laminated on this layer 3,
An upper electrode 6 made of AuBe is formed on the surface of the p-type layer 4 as a light extraction surface A via a p-type second reflection layer 8 having the same structure as the first reflection layer. .
On the back surface of the n-type GaAs substrate 1, a lower electrode 7 made of AuSn is formed. The homo-type semiconductor light emitting device H2 was manufactured as follows. That is, the thickness 350
After growing a 0.2 μm thick n-type GaAs buffer layer on a μm n-type GaAs substrate 1 by epitaxial growth, the respective source gases of GaAs and Ga _0.3 Al _0.7 As are alternately supplied onto the substrate 1. , Thickness 37-43n
m-type GaAs layer and n-type Ga having a thickness of 41 to 47 nm
22 pairs of _0.3 Al _0.7 As layers were stacked to form an n-type first light reflection layer 2. On top of this, a 15 μm InGaAlP layer 20 having a pn junction X in the middle
(3,4) was grown. This composition was prepared so as to be lattice-matched with GaAs and to have a band gap corresponding to 590 nm. Further, an upper electrode was formed thereon through a p-type second light reflection layer 8 having the same structure as the first light reflection layer, and a lower electrode was formed on the back surface of the substrate in the same manner as in Example 1. .

Comparative Example 2 A semiconductor light emitting device was manufactured in the same manner as in Example 5 except that the second light reflecting layer 8 was not provided.

Embodiments 6 to 8 In the semiconductor light emitting device of Embodiment 5 described above, the shape of the first light reflecting layer 2 is a gable roof, a pyramid, or a dome as described above, and a three-dimensional structure having a slope S is provided. A semiconductor light emitting device was manufactured in the same manner except that the semiconductor light emitting device was formed in each of the shapes. When the brightness of each of the obtained semiconductor light emitting devices was measured in the same manner as described above, the results shown in Table 2 were obtained.

[0035]

[Table 2]

As is clear from Table 2 above, the semiconductor light emitting device of the example had an approximately 50% higher luminance than that of the comparative example.

Embodiment 9 A semiconductor light emitting device according to this embodiment has a laminated structure similar to that of FIG. 2, and has an SH type structure. The difference from the fifth embodiment is that the layer 4 is made of p-type AlGaP as a cladding layer and the layer 3 is made of an n-type AlGaInP active layer. The SH type semiconductor light emitting device was manufactured in the same manner as in Example 5 as follows. That is, an n-type GaAs buffer layer having a thickness of 0.2 μm is grown epitaxially on an n-type GaAs substrate 1 having a thickness of 350 μm, and then an n-type GaAs buffer layer having a thickness of 37 to 43 nm is formed.
As layer and n-type Ga _0.3 Al _0.7 A having a thickness of 41 to 47 nm
The n-type first light reflection layer was formed by stacking 18 pairs of the s layer and the s layer. A 5 μm InGaAlP layer was grown thereon. This composition is lattice-matched with GaAs and is 590 nm.
Was prepared so as to have a band gap corresponding to After a p-type AlGaP cladding layer is further formed thereon, an upper electrode is provided via a p-type second light reflecting layer 8 having the same structure as the first light reflecting layer, and a lower electrode is provided on the back surface of the substrate. Were formed in the same manner as in Example 1.
In this light-emitting element, the thickness of the uppermost layer was set to 0.5 μm in order to facilitate the formation of the p-side ohmic contact.
Was formed.

Comparative Example 3 A semiconductor light emitting device was manufactured in the same manner as in Example 9 except that the second light reflecting layer 8 was not provided.

Embodiments 10 to 12 In the semiconductor light emitting device of Embodiment 9 described above, the shape of the first light reflection layer 2 is a gable roof, a pyramid, or a dome as described above, and a three-dimensional structure having a slope S is provided. A semiconductor light emitting device was manufactured in the same manner except that the semiconductor light emitting device was formed in each of the shapes. When the brightness of each of the obtained semiconductor light emitting devices was measured in the same manner as described above, the results shown in Table 3 were obtained.

[0040]

[Table 3]

As is evident from Table 3, the semiconductor light-emitting device of the example had a luminance improved by about 50% as compared with that of the comparative example.

Embodiment 13 A semiconductor light emitting device according to this embodiment has a DH structure shown in FIG. The semiconductor light emitting device H3 includes, on an n-type GaAs substrate 1, an n-type first light reflection layer 2 composed of a GaAs buffer layer (not shown), a multi-layered stack of an InGaP layer and an InAlP layer, An n-type InGaAlP cladding layer 3 on the first light reflection layer 2, a non-doped InGaAlP active layer 4 on the cladding layer 3,
On this active layer 4, a p-type InGaAlP cladding layer 9 is formed.
And a further p-layer formed thereon via a composition gradient layer (not shown).
GaP layers 10 are sequentially stacked, and this p-type GaP layer 10
An upper electrode 6 made of AuBe is formed on the upper side via a p-type second light reflection layer 8 made of a multi-layered stack of a GaP layer and an AlGaP layer. Also, an n-type GaAs substrate 1
A lower electrode 7 made of AuSn is formed on the back surface of the substrate. The DH type semiconductor light emitting device H3 was manufactured as follows. That is, an n-type GaAs substrate 1 having a thickness of 300 μm
On top, 0.5 μm thick nG
After growing the aAs buffer layer, a thickness of 38-44 n
m n-type InGaP layer and 42-47 nm-thick n-type InGaP layer
The n-type first light reflection layer 2 was formed by stacking 25 pairs of the AlP layer and the AlP layer. On top of this, 5 μm n-type InGaAs
The 1P clad layer 3 was grown, and a 0.8 μm non-doped InGaAlP active layer 4 was further formed. 3 on it
growing a μm p-type InGaAlP cladding layer 9;
20 μm p-type GaP through a 0.2 μm composition gradient layer
Layer 10 was formed. Further, an upper electrode is interposed through a p-type second light reflection layer 8 in which 25 pairs of a p-type GaP layer having a thickness of 43 to 48 nm and a p-type AlGaP layer having a thickness of 46 to 51 nm are stacked in pairs. Further, lower electrodes were formed on the back surface of the substrate in the same manner as in Example 1. The composition of each of the above layers is
The light emitting portion is prepared so as to be lattice-matched with GaAs and to have a band gap corresponding to 570 nm.

Comparative Example 4 A semiconductor light emitting device was manufactured in the same manner as in Example 13 except that the second light reflecting layer 8 was not provided.

Embodiments 14 to 16 In the semiconductor light emitting device of Embodiment 13 described above, the shape of the first light reflection layer 2 is a gable roof, a pyramid, or a dome as described above, and a three-dimensional structure having a slope S is provided. A semiconductor light emitting device was manufactured in the same manner except that the semiconductor light emitting device was formed in each of the shapes. When the brightness of each of the obtained semiconductor light emitting devices was measured in the same manner as described above, the results shown in Table 4 were obtained.

[0045]

[Table 4]

As is evident from Table 4, the semiconductor light emitting device of the example had a luminance improved by about 50% as compared with that of the comparative example.

Embodiment 17 The semiconductor light emitting device according to this embodiment is of the DH type shown in FIG.
It has the same structure as the structure. Difference from Example 13 above
What is required is that the n-type first light reflection layer 2 is made of ZnS
_0.07Se_0.93Layer and Zn_0.87Mg_0.13S_0.07Se_0.93Layers and
And the first light reflecting layer
2 on top of n-type ZnS_0.07Se_0.93Clad layer 3 and this
Non-doped ZnCdSe / ZnSS on the cladding layer 3
e light emitting layer 4 having a multiple quantum well structure;
P-type ZnS_0.07Se_0.93Clad layer 9
A p-type ZnSe layer 10 is successively formed thereon via a composition gradient layer.
It is being laminated. Semiconductor light emitting element of this configuration
The child emits blue light. The above DH type semiconductor
The light emitting device was manufactured as follows. That is, the thickness 35
On a 0 μm n-type GaAs substrate, the thickness is
A 0.1 μm n-GaAs buffer layer was grown
Later, ZnS_0.07Se_0.93And Zn_0.87Mg_0.13S_0.18Se
_0.82Are alternately supplied onto the substrate 1,
N-type ZnS with a thickness of 41 to 47 nm_0.07Se_0.93Layer and thickness
42-49 nm n-type Zn_0.87Mg_0.13S_0.18Se_0.82
N-type first light reflection layer in which 32 pairs of layers are stacked
Was formed. On top of that, 2 μm n-type ZnS_0.07Se_0.93
Grow the cladding layer and add 0.4μm non-doped
Forming a light emitting layer of ZnCdSe / ZnSe multiple quantum well structure
Done. On top of that, 2 μm p-type ZnS_0.07Se_0.93Kula
And a 3 μm thick composition gradient layer through the 0.1 μm composition gradient layer.
A μm p-type ZnSe layer was formed. On top of that,
1 through a p-type second light reflection layer 8 having the same structure as that of the first light reflection layer.
And the lower electrode on the back of the substrate.
It was formed in the same manner as in Example 1.

Comparative Example 5 A semiconductor light emitting device was manufactured in the same manner as in Example 17 except that the second light reflecting layer 8 was not provided.

Embodiments 18 to 20 In the semiconductor light emitting device of Embodiment 17, the first light reflecting layer 2 has a gable roof shape, a pyramid shape, and a dome shape as described above, and a three-dimensional structure having a slope S. A semiconductor light emitting device was manufactured in the same manner except that the semiconductor light emitting device was formed in each of the shapes. When the brightness of each of the obtained semiconductor light emitting devices was measured in the same manner as described above, the results shown in Table 5 were obtained.

[0050]

[Table 5]

As is apparent from Table 5, the semiconductor light-emitting device of the example had an approximately 50% higher luminance than that of the comparative example.

Embodiment 21 The semiconductor light-emitting device according to this embodiment emits blue light in the same manner as in Embodiment 17 described above. The difference from Example 17 is that the n-type first light reflection layer 2 is made of Z-type.
A multi-layered stack of nSe and MgS is being used. The DH type semiconductor light emitting device was manufactured as follows. That is, on an n-type GaAs substrate having a thickness of 350 μm,
After growing an n-type GaAs buffer layer having a thickness of 0.5 μm by MBE, an n-type Zn layer having a thickness of 37 to 44 nm is formed.
Fifteen pairs of the Se layer and the n-type MgS layer having a thickness of 39 to 46 nm were stacked to form an n-type first light reflection layer 2. A 2 μm n-type ZnS _0.07 Se _0.93 cladding layer 3 is grown thereon, and a 0.4 μm non-doped ZnC
The light emitting layer 4 having a dSe / ZnSSe multiple quantum well structure was formed. A 2 μm p-type ZnS _0.07 Se _0.93 cladding layer 9 was grown thereon, and a 5 μm p-type ZnSe layer 10 was formed via a 0.05 μm composition gradient layer. Further, an upper electrode is formed thereon through a p-type second light reflecting layer 8 having the same structure as the first light reflecting layer, and a lower electrode is formed on the back surface of the substrate in the same manner as in Example 1. did.

Comparative Example 6 A semiconductor light emitting device was manufactured in the same manner as in Example 21 except that the second light reflecting layer 8 was not provided.

Embodiments 22 to 24 In the semiconductor light emitting device of Embodiment 21 described above, the shape of the first light reflection layer 2 is a gable roof, a pyramid, or a dome as described above, and a three-dimensional structure having a slope S is provided. A semiconductor light emitting device was manufactured in the same manner except that the semiconductor light emitting device was formed in each of the shapes. When the luminance of each of the obtained semiconductor light emitting devices was measured in the same manner as described above, the results shown in Table 6 were obtained.

[0055]

[Table 6]

As is clear from Table 6, the semiconductor light-emitting device of the example had an approximately 50% higher luminance than that of the comparative example.

[0057]

According to the semiconductor light emitting device of the present invention, the amount of light absorbed by the upper electrode can be greatly reduced, and light directed toward the upper electrode can be effectively extracted to the outside of the device. The emitted light can be effectively extracted to the outside of the element without waste, and the luminance becomes higher by about 50% than the conventional light emitting element.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a structure of a semiconductor light emitting device according to one embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a structure of a semiconductor light emitting device according to another embodiment of the present invention.

FIG. 3 is a schematic sectional view showing a structure of a semiconductor light emitting device according to another embodiment of the present invention.

FIG. 4 is a partially cut-away schematic side sectional view showing a shape of a first light reflection layer in the semiconductor light emitting device of the present invention.

FIG. 5 is a partially cut-away schematic side sectional view showing another shape of the first light reflection layer in the semiconductor light emitting device of the present invention.

FIG. 6 is a partially cut-away schematic side sectional view showing another shape of the first light reflection layer in the semiconductor light emitting device of the present invention.

FIG. 7 is a schematic sectional view showing the structure of a conventional semiconductor light emitting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 1st light reflection layer 3 Cladding layer 4 Active layer 5 Cladding layer 6 Upper electrode 7 Lower electrode 8 2nd light reflection layer A Light extraction surface X pn junction H1 Semiconductor light emitting element

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-361572 (JP, A) JP-A-4-296082 (JP, A) JP-A-3-229480 (JP, A) 186679 (JP, A) JP-A-3-163883 (JP, A) JP-A-3-85774 (JP, A) JP-A-1-137679 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) H01L 33/00 H01S 5/00-5/50

Claims (5)

(57) [Claims] A pn junction on a semiconductor substrate;
a first light reflection layer on the substrate side as viewed from the n-junction, and an upper electrode
A second light-reflecting layer on the side, and the first and second light
Shape that reflective layer can reduce optical resonance phenomenon by retroreflection
A semiconductor light emitting device characterized by the following . 2. A three-dimensional structure in which the first light reflecting layer has a slope.
2. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device has a shape. 3. The three-dimensional shape is a gable roof shape.
Item 3. A semiconductor light emitting device according to item 2. 4. The three-dimensional shape is a pyramid shape.
The semiconductor light emitting device according to claim 2. 5. The three-dimensional shape is a dome shape.
Item 3. A semiconductor light emitting device according to item 2.