JP3202864B2 - Light emitting diode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light emitting diode (L)
ED).

[0002]

2. Description of the Related Art Light emitting diodes are GaAs, GaAl.
As, GaP, GaAsP, InP, InGaAsP,
A Group 3-5 compound semiconductor such as InGaAlP or a Group 4 compound semiconductor such as SiC is used as a material. In addition, visible light emitting diodes that emit red to blue light have been put to practical use, and are used in a wide range of applications, such as pilot lamps, numeric displays, outdoor information boards, signal lights, and high-mount stop lamps.

On the other hand, an infrared light emitting diode has a light emitting diode of 0.8.
Wavelengths of μm to 1.5 μm have been put to practical use, and are widely used for controlling remote controllers, autofocus, photo sensors, isolators, and the like, or for optical communication in combination with optical fibers. Incidentally, performances commonly required for these light emitting diodes are high light output and high reliability. In particular, due to the increase in light output, the application of visible light-emitting diodes to outdoor applications has expanded, and the use of infrared light-emitting diodes has increased the controllable distance and the transmission distance of optical communication. It also helps to reduce power consumption.

[0004] Factors that determine the luminous efficiency of the light emitting diode include the internal quantum efficiency, which is the ratio of the number of generated photons to the number of injected carriers in the light emitting region in the semiconductor chip, and the number of photons generated in the light emitting region. There is external takeout efficiency, which is the ratio of the number of photons that can be taken out of the chip. The present invention relates to a structure for improving the luminous efficiency of a light emitting diode, and an outline of a prior art prior to the present invention will be described.

FIG. 6 shows an InGa according to the first prior art.
The upper surface and cross-sectional structure of a semiconductor chip of a yellow light emitting diode having a light emission wavelength of 590 nm using AlP are shown. For the crystal growth, a reduced-pressure metal organic vapor phase epitaxy (reduced pressure MOVPE) method was used. It should be noted that trimethylindium (TMI), triethylgallium (TEG) and trimethylaluminum (TMA) are used as group 3 element raw materials, and arsine (AsH ₃ ) and phosphine (PH ₃ ) are used as group 5 element raw materials. Hydrogen selenide (H ₂ Se) was used as a raw material for Se as an impurity, and Z as a p-type impurity was used.
Diethyl zinc (DEZ) was used as a raw material for n.

The epitaxial layer formed on the semiconductor substrate 1 is formed by first growing a 0.5 μm n-GaAs buffer layer 2 on the (100) plane of a 350 μm thick semiconductor substrate 1 using n-GaAs. n-In _0.5 (Ga _0.3 A
l _0.7 ) _0.5 P clad layer 3 is 1.0 μm, and undoped In _0.5 (Ga _0.6 Al _0.4 ) _0.5 P active layer 4 is 0.5 μm.
The p-In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P cladding layer 5 was grown to 1.0 μm. The compositions of these layers are set so that they are lattice-matched to the semiconductor substrate 1, the active layer 4 has an emission wavelength of 590 nm, and the cladding layers 3, 5 have a larger band gap than the active layer 4. did. As described above, the active layer 4 serving as the light emitting layer is formed by the cladding layers 3 and 5 having a larger band gap than the active layer 4.
The structure sandwiched between the layers is called a double hetero (DH) structure, and plays a role of confining carriers injected from the cladding layers 3 and 5 into the active layer 4. As a result, the density of injected carriers in the active layer 4 is increased, and the probability of radiative recombination is increased. As a result, the internal quantum efficiency is greatly improved.

Following this DH structure, p-Ga _0.3 Al
A window layer 6 of _0.7 As was grown to a thickness of 7 μm. The window layer 6 is substantially transparent to the emission wavelength because the light generated in the active layer 4 is extracted to the outside. Further, by doping Zn at a high concentration to lower the specific resistance and growing it thickly, the current flowing from the p-side electrode 7 can be spread over the entire chip before reaching the active layer 4. The structure of the window layer 6 has a great effect on the above-described external extraction efficiency.

Further, a p-GaAs contact layer 8 is grown thereon by 0.5 μm. Thereafter, a circular p-side electrode 7 having a diameter of 100 μm was formed near the center of the p-GaAs contact layer 8, and an n-side electrode 9 was formed on the entire back surface of the semiconductor substrate 1 by vacuum evaporation. The p-side electrode 7 has
0.1 μm thick Au and Zn alloy layer and 1 μm thick A
A two-layer structure consisting of a u layer was used. Furthermore, p-GaAs
After selectively removing the portion of the contact layer 8 other than under the p-side electrode 7 by wet etching, the chip was cut into a square chip having a side of 300 μm.

The light emitting diode chip manufactured by the above method is fixed on the stem with an Ag paste.
The u-line was connected to the electrode 7, resin-molded, and energized to check the light output. However, in the structure of the first conventional technique, despite the adoption of the DH structure, the thickening of the window layer, and the high concentration doping of Zn, the light which satisfies about 0.1 mW when the forward current is 20 mA. No output was obtained. The following two points were considered as the cause.

The first point relates to light extraction efficiency. That is, the current flowing from the p-side electrode 7 spreads throughout the chip in the window layer 6 and flows into the active layer 4. Of these, a large proportion flows into the active layer 4 directly below the p-side electrode 7, but light generated in the active layer 4 immediately below the p-side electrode 7 is blocked by the p-side electrode 7 and taken out of the semiconductor chip. Can not. This was a major cause for lowering the external extraction efficiency.

The second point concerns the internal quantum efficiency of the active layer 4. In general, the internal quantum efficiency of an InGaAlP-based material decreases as the Al composition increases. This means that the ratio of indirect transition to injected carrier recombination increases,
This is because the inclusion of a large amount of Al leads to an increase in the amount of oxygen which causes non-radiative recombination centers. As described above, as the material of the active layer 4, In _0.5 (Ga _0.6 Al _0.4 ) _0.5 P having a relatively large Al composition is used, and this causes a decrease in internal quantum efficiency.

FIG. 7 shows an InGa according to a second prior art.
5 shows a cross-sectional structure of a semiconductor chip of a yellow light emitting diode having a light emission wavelength of 590 nm using AlP. For crystal growth,
The same reduced pressure MOVPE method as in the first conventional technique was used. The structure is almost the same as that of the first prior art, but n-In
_0.5 (Ga _0.3 Al _0.7 ) _0.5 P current block layer 10
Is formed in a portion between the p-cladding layer 5 and the p-Ga _0.3 Al _0.7 As window layer 6. Current block layer 1
0 is almost the same as the p-side electrode 11 and has a diameter of 100
It was a circle of μm. The film thickness is 0.5 μm.

In manufacturing this light emitting diode,
Crystal growth was performed twice. That is, after growing up to the n-In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P current block layer 10 in the first crystal growth and leaving only the current block layer 10 selectively wet-etched in the aforementioned circular shape, 2
In the third crystal growth, a p-Ga _0.3 Al _0.7 As window layer 6 and a p-GaAs contact layer 8 were grown.

When the light output of the light emitting diode was measured in the same manner as in the first prior art, the forward current was 20 mA.
At this time, the optical output was about 0.2 mW, which was about twice that of the first conventional technique. This is because n-In _0.5 (Ga
_{This is} because the formation of the _0.3 Al _0.7 ) _0.5 P current blocking layer 10 suppresses the current from flowing into the active layer 4 immediately below the p-side electrode 7, thereby greatly improving the light extraction efficiency.

FIG. 8 shows a third prior art InGa.
5 shows a cross-sectional structure of a semiconductor chip of a yellow light emitting diode having a light emission wavelength of 590 nm using AlP. For crystal growth,
The same decompression M as in the first prior art and the second prior art.
The OVPE method was used. The structure is substantially the same as that of the second conventional technique, except that a semiconductor substrate 15 in which the plane orientation of n-GaAs is inclined by 15 ° from the (100) plane to the (011) plane is used, and The active layer 16 is made of In _0.5
(Ga _0.75 Al _0.25 ) _0.5 P is different.

As described above, the reason why the Al composition can be set lower as compared with the first conventional technique and the second conventional technique is that the Al composition is a phenomenon peculiar to the InGaAlP-based material because of the substrate plane orientation. This is because the effect of changing the band gap of the crystal grown in the second step is considered. That is, (10
The band gap of the crystal grown on the 0) plane is about 70 meV smaller than the original value. However, if the substrate orientation is (1)
The value increases as the surface tilts from the (00) plane to the (011) plane, and reaches its original value near the inclination angle of 15 ° and saturates.
This means that the crystal grown on the (100) plane is (111)
Group 3 constituent elements are alternately arranged in the plane direction by one atomic layer,
This is because a so-called natural superlattice is formed, because the growth surface becomes the originally disordered arrangement as the growth surface is inclined from the (100) to the (011) plane. It has also been found that the use of such an inclined substrate reduces the number of non-radiative recombination centers. Note that such a phenomenon is caused by (0
-1-1) The same occurs when the surface is inclined in the plane direction.

When the light output of the light emitting diode was measured in the same manner as in the first prior art and the second prior art, when the forward current was 20 mA, it was about 1.0 mW, which was lower than that of the second prior art. The light output was improved about 5 times as compared with that of the first embodiment. This is because, as described above, the use of the tilted substrate allows the Al composition of the active layer 16 to be set low, and the internal quantum efficiency has been greatly improved.

[0018]

As described above, the light emitting diode according to the first prior art has a disadvantage that the light output is extremely low. On the other hand, by using the second and third techniques, the light output was greatly improved. However, the second conventional technology and the third conventional technology have the following problems. In other words, the second conventional technique requires two crystal growths for one production, which causes a significant cost increase. In particular, the MOVPE apparatus is much more expensive than other growth methods. So its impact is great.

The third prior art uses a substrate inclined by 15 ° from the (100) plane to the (011) plane, but such a substrate has a (100) plane,
Since the surface is special and extremely expensive as compared with a substrate whose surface is inclined by several degrees from the (100) plane, this also causes a significant increase in cost. Accordingly, it is an object of the present invention to provide a light emitting diode which can achieve high light output without using a special substrate, can be manufactured by one crystal growth, and has excellent productivity and can be manufactured at low cost. is there.

[0020]

According to a first aspect of the present invention, there is provided a light emitting diode having the same lattice plane as the (100) plane and the (10) plane.
A first main surface which is one of a surface inclined from the (0) plane to the direction of the (011) plane and the direction of the (0-1-1) plane; A second main surface that is inclined in at least one of the (011) plane direction and the (0-1-1) plane direction and is arranged side by side with the first main surface; A semiconductor substrate in which the angle between the (100) plane and the second principal plane is smaller than the angle between the (100) plane, a light emitting layer having a double hetero structure having a cladding layer sandwiching the active layer, A co-doping layer of both n-type and p-type impurities formed above or below the layer, a window layer formed above the light-emitting layer and taking out light generated in the active layer to the outside, A portion of the window layer facing one of the first main surface and the second main surface and a back surface of the semiconductor substrate A made electrodes, the light-emitting layer,
At least the active layer is made of an InGaAlP-based material or Ga.
The first of the co-doping layers is formed of an AlAs-based material .
As part immediately below the electrode becomes blocking layer with respect to the current flowing from the first electrode, to set the plane direction and the concentration of the impurity of the first major surface and a second major surface, the first major surface
At the boundary of the second main surface and along the boundary above the window layer
And a light-shielding film .

[0021]

[0022]

According to the light emitting diode of the first aspect, the MOVP
In the crystal growth by many methods such as the E method and the molecular beam epitaxy (MBE) method, the impurity doping efficiency greatly differs depending on the plane orientation of the growth substrate.
In a so-called simultaneous doping layer in which both types of impurities are simultaneously doped, the conductivity type can be changed in different plane orientations on the semiconductor substrate by appropriately setting the supply amounts of the impurity raw materials and the plane orientation of the growth substrate. Therefore,
By forming the co-doping layer in the epitaxial layer, for example, the co-doping layer on the first main surface can be
Since it can be a block layer for the current flowing from the electrode, the current can be prevented from flowing into the active layer immediately below the electrode. As a result, the external extraction efficiency can be increased without using a special substrate, so that a light-emitting diode with a high light output can be obtained. Further, since the light-emitting diode can be manufactured by one crystal growth, the productivity is excellent and the cost can be reduced.

[0023] The light-emitting layer, InG at least the active layer
Since formed by aAlP based material or GaAlAs-based material, it is possible to higher internal quantum efficiency as well as external extraction efficiency, higher optical output can be obtained. In addition, the first main surface and the boundary of the second major surface, to have a light shielding film along the boundary on the upper side of the window layer, excellent monochromatic property.

[0024]

EXAMPLE A first comparative example with respect to the example of the present invention will be described.
Referring to FIGS. 1 and 2 will be described without. FIG.
The upper surface and cross-sectional structure of a semiconductor chip of a yellow light emitting diode of nGaAlP having a light emission wavelength of 590 nm are shown. The method of manufacturing this semiconductor chip is substantially the same as that of the first conventional technique shown in FIG. 6, and the same reference numerals are given to the common parts, and the differences from the first conventional technique will be described below.

As the semiconductor substrate 17, a growth substrate having a (100) n-GaAs surface is used. Prior to the growth, first, photolithography and wet etching using an HF + H2 O2-based etchant are applied to the center of the semiconductor chip to a width of 100 .mu.m. 01-1) The first extending in the direction of the plane
Is left on both sides of the striped flat portion 18 as the second main surface (0%).
11) about 15 in the direction of the plane and in the direction of the (0-1-1) plane
An inclined surface 19 having an inclination of ゜ was formed. Epitaxial growth was performed by the MOVPE method on the semiconductor substrate 17 thus processed.

The structure of the growth layer is different from that of the first prior art in that the active layer 20 has a light emitting layer such that the wavelength of light emitted from the active layer 20 on the inclined surface 19 is 590 nm.
The composition of In _0.5 (Ga _0.75 Al _0.25 ) _0.5 P and In _0.5 (Ga
_The point is that a simultaneous doping layer 22 of both n-type and p-type impurities of _0.3 Al _0.7 ) _0.5 P was formed to a thickness of 0.5 μm. A p-side electrode 7 having a diameter of 100 μm was formed at the center above the stripe-shaped flat portion 18 as the first main surface.

Here, the simultaneous doping layer 22 will be described below. When a Group III-V compound semiconductor is grown by MOVPE, the doping efficiency of impurities greatly changes depending on the plane orientation of the growth substrate used. Now the plane orientation of the growth substrate is from (100) plane to (011) plane or (0-1-1) plane.
Considering the case of tilting in the direction of the plane, the p-type impurity Zn
Doping efficiency rapidly increases with the inclination angle, while the doping efficiency of the n-type impurity Se rapidly decreases. The reason is that Zn substitutes for the group III lattice position, and Se substitutes for the group V lattice position. As the inclination angle increases, the concentration of group III vacancies increases and the concentration of group V vacancies decreases. It is said that it is to decrease.

The co-doping layer 22 of the first comparative example utilizes this phenomenon, and the p-type impurity material D
By simultaneously supplying EZ and H ₂ Se, which is an n-type impurity material, the acceptor made of Zn and the donor made of Se mutually compensate, and the conductivity type changes depending on the tilt angle. (10) of the growth substrate in the simultaneous doping layer 22 at the impurity material supply amount employed in this comparative example.
FIG. 2 shows the relationship between the inclination angle from the (0) plane to the (011) plane and the (0-1-1) plane, and the carrier concentration. FIG. 2 also shows a change in carrier concentration when each impurity raw material is supplied alone. By optimizing the supply amount of the impurity material in this way, the (100) plane has an n-type electron concentration of 1 × 10 ¹⁸ cm ⁻³ ,
On the plane inclined by 15 ° in the direction of the plane and the (0-1-1) plane, a p-type having a hole concentration of 5 × 10 ¹⁷ cm ⁻³ could be obtained.

As is apparent from FIG. 2, by appropriately setting the combination of the plane orientations and the supply amount of the impurity raw material,
The conductivity type can be changed in other combinations. As described above, the simultaneous doping layer 22 of this comparative example is n-type above the stripe-shaped flat portion 18 as the first main surface, and is p-type on the inclined surface 19. The current flowing from the p-side electrode 7 is blocked above the stripe-shaped flat portion 18 because a reverse bias is applied between the simultaneous doping layer 22 and the p-cladding layer 21 therebelow, and the active layer 20 above the inclined surface 19 is blocked. The current flows into only this, and light is emitted. Since the p-side electrode 7 is formed at a part of the corresponding portion above the stripe-shaped flat portion 18, light generated in the active layer 20 on the inclined surface 19 is not hindered by the p-side electrode 7. It will be taken out. Therefore, an improvement in the external takeout efficiency can be expected.

The light emitting region of the first comparative example is (1
InGaAs grown on the inclined surface 19 inclined by 15 ° from the (00) plane to the (011) plane and the (0-1-1) plane.
Since the active layer 20 is made of an IP-based material, a significant improvement in internal quantum efficiency can be expected as in the second comparative example . Therefore,
When the light output of this light emitting diode was measured in the same manner as in the prior art, when the forward current was 20 mA, about 1.0 mW, which was the same as the third prior art, was obtained. As described above, according to the first comparative example , a light emitting diode with high light output was realized by using the relatively inexpensive (100) GaAs semiconductor substrate 17 and performing crystal growth only once.

A second comparative example of the embodiment of the present invention will be described with reference to FIG. FIG. 3 shows a sectional structure of a semiconductor chip of a yellow light emitting diode having a light emission wavelength of 590 nm using InGaAlP. The structure of the semiconductor chip of the second comparative example is substantially the same as that of the first comparative example , except that the simultaneous doping layer 24 is formed between the p-cladding layer 25 and the active layer 26.

In the second comparative example , as in the first comparative example , the simultaneous doping layer 24 above the stripe-shaped flat portion 18 on the first main surface functions as a current blocking layer.
However, the mechanism is different from the first comparative example . That is, the pn junction is formed at the interface between the n-type co-doping layer 24 and the p-cladding layer 25 on the stripe-shaped flat portion 18, and is co-doped with the undoped active layer 26 (usually n-type) on the inclined surface 19. Formed at the interface of layer 24. Second
In the comparative example, the p-cladding layer 25 and the co-doping layer 24 are In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P and have a band gap of about 2.32 eV. The active layer 26 is In _0.5 (Ga _0.75 Al _0.25 ) _0.5 P,
The band gap is about 2.06 eV. Generally, the lower the band gap of at least one of the PN junctions is, the more current flows when the same voltage is applied.
In the embodiment, the pn junction above the stripe-shaped flat portion 18 substantially functions as a current blocking layer.

The light output of the light emitting diode was measured in the same manner as in the first comparative example.
In this case, about 1.0 mW, an optical output similar to that of the first comparative example was obtained. As described above, as shown in the first comparative example and the second comparative example , when these comparative examples are applied to a light emitting diode using an InGaAlP-based material, the light output is about 10 times as compared with the first conventional technique. Improved and significant effects were observed.

As a modification of this comparative example , GaAlAs
A similar comparison was made for a light emitting diode using a system material. As a result, the light output of the light emitting diode according to this modified example was about twice as large as that of the structure similar to the first conventional technique. Therefore, although the effect is lower than that of the InGaAlP-based material, the same effect as that of the first comparative example was also confirmed for the GaAlAs-based material.

A remarkable effect when applied to a light emitting diode made of an InGaAlP-based material is as described in the third related art, by forming an epitaxial layer on an inclined surface. This is because the internal quantum efficiency of the active layer is significantly improved. However, the first
When comparative example and was measured emission spectrum of the light emitting diodes of InGaAlP-based material by the second comparative example, as shown in FIG. 4, in addition to strong emission band having a peak at 590 nm, weak emission band having a peak at 610nm Was found to exist. The color of the emitted light was slightly reddish.

As a result of studying the cause, 610n
The wavelength of m is In _0.5 (Ga _0.75 A) of the active layers 20 and 26.
l _0.25 ) _0.5 P corresponds to the band gap when the P is formed on the (100) plane.
0) The active layer 20 on the stripe-shaped flat portion 18 which is the plane,
It was considered that light flowed into 26 and emitted light. When the light emission pattern of the semiconductor chip was actually observed with a microscope, it was found that the periphery of the stripe-shaped flat portion 18 glowed slightly red. This is because p on the inclined surface 19
A part of the current of the cladding layers 21 and 25 flows into the p-cladding layers 21 and 25 on the stripe-shaped flat portion 18 and the carrier injected into the active layers 20 and 26 on the inclined surface 19; It is conceivable that a part of the diffusion diffuses into the active layers 20 and 26 on the stripe-shaped flat portion 18 and then recombines.

An embodiment of the present invention will be described with reference to FIG. That is, FIG. 5 shows a top surface and a sectional structure of a semiconductor chip of a yellow light emitting diode having a light emission wavelength of 590 nm using InGaAlP. Its structure is almost the same as that of the first comparative example , except that the striped flat portion 18 is formed.
On the surface of the epitaxial layer above the boundary between
The difference is that the light shielding film 31 having a width of 10 μm is formed of the same material as the p-side electrode along the boundary.

As in the first comparative example and the second comparative example ,
When the light output of the light emitting diode of this embodiment was measured, it was found that when the forward current was 20 mA, it was about 1.0 mW, which was the first ratio.
Similar light output and Comparative Examples and a second comparative example was obtained. When the emission spectrum was measured, no emission band having a peak at 610 nm, which was observed in the first comparative example and the second comparative example , was observed. Pure yellow emission was also observed when observed with the naked eye.

As described above, by forming the light-shielding film 31 on the surface of the epitaxial layer above the region including all or a part of the boundary between the stripe-shaped flat portion 18 and the inclined surface 19, that is, on the window layer 6 or the contact layer 8. , InGaAl
The light emitting diode made of a P-based material was excellent in monochromaticity, and a high light output was realized. In the above embodiment, the active layer 20 or the like of InGaAlP or GaAlAs-based material is formed on the GaAs semiconductor substrate 1, and the simultaneous doping layer 22 uses Se as the n-type impurity and Zn as the p-type impurity. However, other substrates and materials, such as when the InGaAsP active layer 20 is formed on the InP semiconductor substrate 1, and other materials whose doping efficiency changes depending on the plane orientation of the substrate, such as S, Mg, Be, etc. Similar effects can be obtained by using impurities.

A (100) plane is used as the first principal plane, and a plane inclined by 15 ° from the (100) plane to the (011) plane and the (0-1-1) plane is used as the second principal plane. However, for example, as the first main surface, from the (100) plane to (01)
1) A plane inclined by 3 ° in the plane direction, and (10
Another surface may be used, such as a surface inclined by 20 ° from the (0) plane to the (011) plane and the (0-1-1) plane, and the angle formed by the first main surface and the (100) plane. Should be smaller than the angle between the second main surface and the (100) plane.

Under such restrictions on each main surface, as described in the above embodiment, when the simultaneous doping layer is provided on the P side with respect to the active layer, the simultaneous doping on the first main surface is performed. Since the layer becomes a current blocking layer, the electrode 7 may be formed above the current blocking layer. On the other hand, when a simultaneous doping layer is provided on the n-side of the active layer, the simultaneous doping layer on the second main surface is a current blocking layer. So that the electrode 7
May be formed.

In the above-described embodiment, the second main surface is provided on both sides of the first main surface, but it may be provided only on one side, that is, only on one side of the first main surface. Further, the MOVPE method is used as the crystal growth method, but another growth method may be used.
Needless to say, a material other than the p-side electrode 7 may be used for the light-shielding layer 31. In addition, various modifications can be made without departing from the spirit of the present invention.

[0043]

According to the light emitting diode of the first aspect, M
In the crystal growth by many methods such as the OVPE method and the molecular beam epitaxy (MBE) method, the impurity doping efficiency greatly differs depending on the plane orientation of the growth substrate. Therefore, a so-called simultaneous doping layer in which both n-type and p-type impurities are simultaneously doped. By appropriately setting the supply amounts of the impurity materials and the plane orientation of the growth substrate, the conductivity type can be changed in different plane orientations on the semiconductor substrate. Therefore, by forming the co-doping layer in the epitaxial layer, for example, the co-doping layer on the first main surface can be used as a blocking layer for a current flowing from the electrode, and the Current can be prevented from flowing.

As a result, the external extraction efficiency can be increased without using a special substrate, so that a light-emitting diode with a high light output can be obtained. Further, since the light-emitting diode can be manufactured by a single crystal growth, the productivity is excellent and the cost can be reduced. This has the effect. In the light emitting layer, at least the active layer is made of InGaAs.
Since formed by lP based material or GaAlAs-based material, it is possible to higher internal quantum efficiency as well as external extraction efficiency, higher optical output can be obtained.

Further, at the boundary between the first main surface and the second main surface, a light shielding film is provided along the boundary above the window layer .
Excellent single color resistance.

[Brief description of the drawings]

FIG. 1 is a top view and a cross-sectional view of a semiconductor chip of a yellow light emitting diode of InGaAlP in a first comparative example .

FIG. 2 shows the relationship between the inclination angle and the carrier concentration of the growth substrate from the (100) plane to the (011) plane and the (0-1-1) plane in the supply amount of the impurity material used in the first comparative example . It is a graph which shows a relationship.

FIG. 3 is a cross-sectional view of a semiconductor chip of a yellow light emitting diode of InGaAlP in a second comparative example .

FIG. 4 is an emission spectrum of a yellow light emitting diode of InGaAlP.

FIG. 5 is a top view and a cross-sectional view of a semiconductor chip of an InGaAlP yellow light emitting diode according to an embodiment of the present invention .

FIG. 6 shows an emission wavelength of 590 nm in the first conventional technique.
3A and 3B are a top view and a cross-sectional view of a semiconductor chip of a yellow light emitting diode of InGaAlP.

FIG. 7 is a sectional view of a semiconductor chip of an InGaAlP yellow light emitting diode having a light emission wavelength of 590 nm according to a second conventional technique.

FIG. 8 is a sectional view of a semiconductor chip of an InGaAlP yellow light emitting diode having a light emission wavelength of 590 nm according to a third conventional technique.

[Explanation of symbols]

 Reference Signs List 17 semiconductor substrate 3 clad layer 6 window layer 7, 9 electrode 18 striped flat portion as first main surface 19 inclined surface as second main surface 20, 26 active layer 21, 25 clad layer 22, 24 simultaneous doping layer

Continuation of front page (56) References JP-A-4-229665 (JP, A) JP-A-1-295469 (JP, A) JP-A-5-259566 (JP, A) JP-A-5-63304 (JP) (A) Special table Hei 5-502331 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB name) H01L 33/00 H01S 5/00-5/50 H01L 21/20

Claims (1)

(57) [Claims] 1. The same plane as the (100) plane of the lattice plane, the direction from the (100) plane to the (011) plane, and (0-1)
-1) The surface has a first main surface which is one of surfaces inclined in any of the directions of the surface, and has a (011) plane direction and a (0-1-) surface with respect to the first main surface. 1) having a second main surface inclined in at least one of the plane directions and juxtaposed to the first main surface, wherein the angle formed by the first main surface and the (100) plane is the 2 main surface and (10
0) a semiconductor substrate smaller than the angle formed by the plane, a light emitting layer of a double hetero structure having a cladding layer sandwiching the active layer, and n-type and p-type light emitting layers formed above or below the active layer. A co-doping layer of both impurities; a window layer formed above the light emitting layer to take out light generated in the active layer to the outside; a first main surface and a second main surface on the window layer And an electrode formed on the back surface of the semiconductor substrate, wherein the light emitting layer has at least an active layer formed of an InGaAlP-based material.
Fee or formed by GaAlAs-based material, wherein as the site immediately below the first electrode of the co-doped layer is blocking layer with respect to the current flowing from the first electrode, the first main surface and a second The plane orientation of the main surface and the concentration of the impurity are set, and at the boundary between the first main surface and the second main surface,
It has a light shielding film along the boundary on the upper side of the window layer.
Light-emitting diode to be.