JPH07263745A - Light-emitting diode - Google Patents

Abstract

PURPOSE:To prevent a current from flowing into an active layer located under an electrode by a method wherein a layer concurrently doped with N-type and P-type impurities is provided above or below the active layer. CONSTITUTION:A layer 22 concurrently doped with N-type and P-type impurities is formed inside a P-clad layer 21. By this setup, a layer can be changed in conductivity type by adequately setting a combination of plane orientation and impurity material in supply. In this case, a part of the layer 22 concurrently doped with N-type and P-type impurities located above a first prime surface stripe-like flat 18 becomes a N-type, and the other part of the layer 22 located above a sloping surface 19 becomes a P-type. A current flowing from a P-side electrode 7 is blocked above the stripe-like flat 18 because a part between the doped layer 22 and the P-clad layer 21 below it is inversely biased and made to enable an active layer located above the sloping surface 19 to emit light running into the active layer 20. As mentioned above, a current can be prevented from flowing into the active layer 20 located under an electrode, so that a light emitting diode can be enhanced in light extracting efficiency.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Light emitting diodes are made of GaAs, GaAl.
As, GaP, GaAsP, InP, InGaAsP,
A 3-5 group compound semiconductor such as InGaAlP or a 4 group compound semiconductor such as SiC is used as a material. Further, the light emitting diode for visible light has been put into practical use in a color range from red to blue, and is used in a wide range of applications such as a pilot lamp, a numerical display, an outdoor information board, a signal light, and a high mount stop lamp.

On the other hand, the infrared light emitting diode is 0.8
A wavelength of μm to 1.5 μm has been put to practical use and is widely used for controlling remote controllers, autofocus, photosensors, isolators, etc., or for optical communication in combination with an optical fiber. By the way, the performance commonly required for these light emitting diodes is high light output and high reliability. In particular, due to higher light output, applications such as outdoor applications are expanding for visible light emitting diodes, and infrared light emitting diodes contribute to improving device performance, such as increasing the controllable distance and optical communication transmission distance. It also helps reduce power consumption.

The factors that determine the light emission efficiency of the light emitting diode are the internal quantum efficiency, which is the ratio of the number of photons generated 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 the external extraction efficiency, which is the ratio of the number of photons that can be extracted to the outside of the chip. The present invention relates to a structure for improving the light emission efficiency of a light emitting diode, and the outline of the prior art prior to the present invention will be described.

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

The epitaxial layer formed on the semiconductor substrate 1 is composed of n-GaAs and has a thickness of 350 μm. The (100) plane of the semiconductor substrate 1 is first grown on the n-GaAs buffer layer 2 by 0.5 μm. n-In _0.5 (Ga _0.3 A
l _0.7 ) _0.5 P cladding 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.
μm, p-In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P cladding layer 5 was grown to 1.0 μm. The composition of each of these layers is set so as to be lattice-matched with the semiconductor substrate 1, the active layer 4 has an emission wavelength of 590 nm, and the cladding layers 3 and 5 have a band gap larger than that of the active layer 4. did. As described above, the active layer 4 serving as the light emitting layer is formed into the cladding layers 3 and 5 having a band gap larger than that of the active layer 4.
The structure sandwiched by 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. This increases the density of injected carriers in the active layer 4 and increases the probability of radiative recombination, resulting in a significant improvement in internal quantum efficiency.

Following this DH structure, p-Ga _0.3 Al
_{The 0.7} As window layer 6 was grown to 7 μm. Since the window layer 6 takes out the light generated in the active layer 4 to the outside, it is substantially transparent to the emission wavelength. Further, by doping Zn at a high concentration to reduce the specific resistance and grow thicker, 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 greatly affects the above-mentioned external extraction efficiency.

Further, a p-GaAs contact layer 8 is grown thereon to a thickness of 0.5 μm. After that, a circular p-side electrode 7 having a diameter of 100 μm was formed near the center on 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 a vacuum deposition method. For the p-side electrode 7,
Au / Zn alloy layer with a thickness of 0.1 μm and A with a thickness of 1 μm
A two-layer structure composed of u layers was used. Furthermore, p-GaAs
After selectively removing the contact layer 8 except under the p-side electrode 7 by wet etching, it was cut out 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 Ag paste, and
The u-line was connected to the electrode 7, resin-molded, and then energized to examine the light output. However, in the structure of the first prior art, despite the adoption of the DH structure, the thickening of the window layer, and the high concentration doping of Zn, a light with a forward current of 20 mA, which is about 0.1 mW, should be satisfied. No output was obtained. The following two points were considered as the causes of this.

The first point relates to the light extraction efficiency. That is, the current flowing from the p-side electrode 7 spreads over the entire chip in the window layer 6 and flows into the active layer 4. Most of them flow into the active layer 4 directly below the p-side electrode 7, but the light generated in the active layer 4 directly below the p-side electrode 7 is shielded by the p-side electrode 7 and taken out of the semiconductor chip. I can't. This is a major cause of lowering the external extraction efficiency.

The second point relates to the internal quantum efficiency of the active layer 4. In general, the internal quantum efficiency of InGaAlP-based materials decreases as the Al composition increases. This means that the ratio of indirect transitions to injected carrier recombination increases.
This is because the inclusion of a large amount of Al increases the amount of oxygen taken in, which causes non-radiative recombination centers. The material of the active layer 4 as described above, relatively high Al composition _{In 0 .5 (Ga 0. 6 Al} 0.4) and using _0.5 P, which has been a cause for lowering the internal quantum efficiency.

FIG. 7 shows InGa according to the second conventional technique.
2 shows a cross-sectional structure of a semiconductor chip of a yellow light emitting diode using AlP and having an emission wavelength of 590 nm. For crystal growth,
The same reduced pressure MOVPE method as the first conventional technique was used. The structure is almost the same as that of the first conventional technique, but n-In
_{0.5 (Ga 0.3 Al 0. 7)} 0.5 P current blocking layer 10
Is formed in a part between the p-clad layer 5 and the p-Ga _0.3 Al _0.7 As window layer 6. Current block layer 1
The shape of 0 is almost the same as that of the p-side electrode 11, and the diameter is 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 the n-In _0.5 (Ga _0.3 Al _0.7 ) _0.5 P current blocking layer 10 was grown in the first crystal growth, and only the current blocking layer 10 was selectively wet-etched into the circular shape described above and left, Two
Was grown p-Ga _0.3 Al _0.7 As window layer 6 and the p-GaAs contact layer 8, at times eye crystal growth.

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

FIG. 8 shows InGa according to the third conventional technique.
2 shows a cross-sectional structure of a semiconductor chip of a yellow light emitting diode using AlP and having an emission wavelength of 590 nm. For crystal growth,
The same reduced pressure M as the first conventional technique and the second conventional technique
The OVPE method was used. The structure is almost the same as that of the second conventional technique, but as the semiconductor substrate 15, n-GaAs whose plane orientation 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 it is a phenomenon unique to the InGaAlP-based material, which is due to the substrate surface orientation. This is because the effect of changing the band gap of the grown crystal was taken into consideration. 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 plane orientation is (1
It becomes larger as it inclines from the (00) plane to the (011) plane, and reaches its original value near an inclination angle of 15 ° and saturates.
This means that the crystal grown on the (100) plane is (111)
Group 3 constituent elements are arranged alternately in the plane direction by one atomic layer,
This is because a so-called natural superlattice is formed, and as the growth plane is inclined from the (100) plane to the (011) plane, the original disordered arrangement is formed. Moreover, it is known that the non-radiative recombination centers are reduced by using such a tilted substrate. Note that such a phenomenon is (0
-1-1) The same occurs when tilted in the plane direction.

Similarly to the first and second prior arts, the light output of this light emitting diode was measured and found to be about 1.0mW at a forward current of 20mA, which is the same as the second prior art. The light output was improved by about 5 times compared with the above. This is because the Al composition of the active layer 16 can be set low and the internal quantum efficiency is significantly improved by using the inclined substrate as described above.

[0018]

As described above, the light emitting diode according to the first conventional technique has a drawback that the light output is extremely low. On the other hand, by using the second and third techniques, the light output was significantly improved. However, the second conventional technique and the third conventional technique have the following problems. That is, the second conventional technique requires a crystal growth twice for one production, which causes a large increase in cost. Especially, the MOVPE apparatus is very expensive as compared with other growth methods. So the impact is great.

In the third conventional technique, a substrate inclined by 15 ° from the (100) plane to the (011) plane was used. Such a substrate has a (100) plane surface or
Since the surface is special compared to a substrate whose surface is tilted a few degrees from the (100) plane and is very expensive, this also causes a significant cost increase. Therefore, an object of the present invention is to provide a light emitting diode which can be made to have a high light output without using a special substrate, can be manufactured by one-time crystal growth, and is excellent in productivity and can be made inexpensive. is there.

[0020]

According to a first aspect of the present invention, there is provided a light emitting diode having the same plane as (100) plane of a lattice plane and (10) plane.
The surface has a first main surface which is one of the surfaces inclined from the (0) plane to either the (011) plane direction or the (0-1-1) plane direction, and the first main plane. With respect to the (011) plane direction and the (0-1-1) plane direction, having a second main surface inclined in at least one of the first main surface and arranged in parallel with the first main surface. And a (100) plane make an angle smaller than that formed by the second main surface and the (100) plane, a light emitting layer having a double hetero structure having a clad layer sandwiching the active layer, and an active layer. An n-type and p-type impurity co-doping layer formed on the lower side of the layer or on the lower side, and a window layer formed on the upper side of the light emitting layer to take out the light generated in the active layer to the outside, On the portion of the window layer facing one of the first main surface and the second main surface and on the back surface of the semiconductor substrate. And a surface of the first main surface and the second main surface of the co-doping layer so that the portion of the co-doping layer immediately below the first electrode serves as a blocking layer for a current flowing from the first electrode. The orientation and the concentration of impurities are set.

A light emitting diode according to a second aspect is the light emitting diode according to the first aspect, wherein the light emitting layer has at least an active layer of InGaAlP.
It is characterized by being formed of a system material. A light emitting diode according to a third aspect of the present invention is the light emitting diode according to the second aspect, characterized in that a light shielding film is provided along the boundary above the window layer at the boundary between the first main surface and the second main surface.

[0022]

According to the light emitting diode of claim 1, the MOVP
In crystal growth by many methods such as the E method and the molecular beam epitaxy (MBE) method, the impurity doping efficiency greatly varies depending on the plane orientation of the growth substrate.
In a so-called simultaneous doping layer in which both types of impurities are doped at the same time, the conductivity type can be changed in different plane orientations on the semiconductor substrate by appropriately setting the supply amount of both impurities 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 major surface is
Since it can be a blocking layer against the current flowing from the electrode, it is possible to prevent the current from flowing into the active layer immediately below the electrode. As a result, it is possible to improve the external extraction efficiency without using a special substrate, so that a light emitting diode having a high light output can be obtained, and since the light emitting diode can be manufactured by performing the crystal growth once, the productivity is excellent and the cost can be reduced.

According to the light emitting diode of claim 2, in the light emitting layer according to claim 1, at least the active layer is made of InGa.
Since it is formed of an AlP-based material, in addition to the effect of claim 1, not only the external extraction efficiency but also the internal quantum efficiency can be increased, so that a higher light output can be obtained. According to the light emitting diode of claim 3, according to claim 2,
At the boundary between the first main surface and the second main surface, since the light-shielding film is provided along the boundary above the window layer, the monochromaticity is excellent in addition to the effect of the second aspect.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a top surface and a sectional structure of a semiconductor chip of a yellow light emitting diode of InGaAlP having an emission wavelength of 590 nm. The method of manufacturing this semiconductor chip is generally the same as that of the first conventional technique shown in FIG. 6, common parts are denoted by the same reference numerals, and points different from the first conventional technique will be described below.

As the semiconductor substrate 17, an n-GaAs surface having a (100) surface is used as a growth substrate. Prior to the growth, photolithography and wet etching with an HF + H ₂ O ₂ system etchant are performed to a width of 100 μm at the center of the semiconductor chip. First extending in the direction of the (01-1) plane of
The striped flat portions 18 serving as the main surfaces of the striped flat portions 18 are left, and (0
About 15 in the direction of (11) plane and the direction of (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 differs from that of the first prior art in that the active layer 20 is a light emitting layer so that the wavelength of light emitted from the active layer 20 on the inclined surface 19 is 590 nm.
Of In _0.5 (Ga _0.75 Al _0.25 ) _0.5 P and the In _0.5 (Ga
_The point is that the simultaneous doping layer 22 of both n-type and p-type impurities of _0.3 Al _0.7 ) _0.5 P was formed to 0.5 μm. Further, the p-side electrode 7 having a diameter of 100 μm was formed in the center above the striped flat portion 18 which is the first main surface.

The co-doping layer 22 will be described below. When a Group 3-5 compound semiconductor is grown by the MOVPE method, the doping efficiency of impurities largely 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)
Considering the case of tilting in the direction of the plane, Zn which is a p-type impurity
The doping efficiency of n increases sharply with its inclination angle, while the doping efficiency of n-type impurity Se decreases sharply. The reason is that Zn replaces the group 3 lattice position and Se replaces the group 5 lattice position, but the concentration of group 3 vacancies increases as the tilt angle increases, and the concentration of group 5 vacancies increases. It is said that the reason is to decrease.

The co-doping layer 22 of the first embodiment utilizes this phenomenon and is a p-type impurity source D.
By simultaneously supplying EZ and H ₂ Se as an n-type impurity material, the Zn acceptor and the Se donor compensate each other, and the conductivity type changes depending on the tilt angle. In the co-doping layer 22, the amount of the impurity source material used in this embodiment is set to (10) of the growth substrate.
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. Note that FIG. 2 also shows changes in carrier concentration when each of the impurity raw materials is supplied alone. By optimizing the supply amount of the impurity raw material in this way, the electron concentration on the (100) plane is n-type with 1 × 10 ¹⁸ cm ⁻³ , and from the (100) plane to (011)
In the planes and the plane inclined by 15 ° in the direction of the (0-1-1) plane, the hole concentration could be set to 5 × 10 ¹⁷ cm ^{−3 and} the p-type could be obtained.

Further, as is apparent from FIG. 2, by appropriately setting the combination of plane orientations and the amount of impurity raw material supply,
The conductivity type can be changed in other combinations. As described above, the co-doping layer 22 of this embodiment is n-type above the striped flat portion 18 which is the first main surface and p-type on the inclined surface 19. The current flowing from the p-side electrode 7 is blocked above the striped 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. Only the current will flow into it and it will emit light. Since the p-side electrode 7 is formed at a part of the upper portion of the striped flat portion 18 corresponding thereto, the light generated in the active layer 20 on the inclined surface 19 is not disturbed by the p-side electrode 7. It will be taken out. Therefore, improvement in external extraction efficiency can be expected.

The light emitting region of the first embodiment is (1
InGaA grown on the inclined surface 19 inclined by 15 ° from the (00) plane toward the (011) plane and the (0-1-1) plane.
Since it is the active layer 20 made of the 1P-based material, a great improvement in the internal quantum efficiency can be expected as in the second embodiment. Therefore,
When the light output of this light emitting diode was measured in the same manner as the conventional technique, it was about 1.0 mW at a forward current of 20 mA, which was similar to the third conventional technique. As described above, according to the first embodiment, the light emitting diode having a high light output can be realized by using the relatively inexpensive semiconductor substrate 17 of the (100) plane GaAs substrate and performing the crystal growth only once.

A second embodiment of the present invention will be described with reference to FIG. FIG. 3 shows the emission wavelength 5 using InGaAlP.
The cross-sectional structure of the semiconductor chip of a 90-nm yellow light emitting diode is shown. The structure of the semiconductor chip of the second embodiment is substantially the same as that of the first embodiment, except that the co-doping layer 24 is formed between the p-clad layer 25 and the active layer 26.

Also in this second embodiment, the first embodiment
Similarly to above, above the striped flat portion 18 of the first main surface.
The co-doped layer 24 serves as a current blocking layer.
However, the mechanism is different from that of the first embodiment. That is, strike
On the ridge-shaped flat portion 18, the pn junction is an n-type simultaneous dope.
Is formed at the interface between the sealing layer 24 and the p-clad layer 25,
On the slope 19, the undoped active layer 26 (normally n-type) is used.
Is formed at the interface of the co-doping layer 24. Second
P-cladding layer 25 and simultaneous dope in the example of FIG.
The ring layer 24 is In_0.5(Ga _0.3Al_0.7)_0.5At P
The band gap is about 2.32 eV. Also active
Layer 26 is In_0.5(Ga_0.75Al_0.25)_0.5P,
The band gap is about 2.06 eV. Generally PN connection
The lower the band gap of at least one of the
Since a large amount of current flows when a voltage is applied, this second
In the case of the above embodiment, the pn junction above the striped flat portion 18 is used.
In that case, it substantially acts as a current blocking layer.

Then, when the light output of this light emitting diode was measured in the same manner as in the first embodiment, the forward current was 20 mA.
At that time, about 1.0 mW, the same optical output as that of the first embodiment was obtained. As described above, as shown in the first and second embodiments, when these embodiments are applied to the light emitting diode made of the InGaAlP-based material, the light output is about 10 times that of the first conventional technique. It was improved and a remarkable effect was recognized.

As a modification of this embodiment, GaAlAs
A similar comparison was made for light emitting diodes based on materials. As a result, the light output of the light emitting diode according to this modification is about twice as high as that of the structure similar to that of the first conventional technique. Therefore, although the effect is lower than that of the InGaAlP-based material, it was confirmed that the GaAlAs-based material has the same operational effect as that of the first embodiment.

As described in the third prior art, the remarkable effect when applied to the light emitting diode made of the InGaAlP material is that the epitaxial layer is formed on the inclined surface. This is because the internal quantum efficiency of the active layer is significantly improved. However, the first
The emission spectra of the light emitting diodes made of the InGaAlP-based material according to Example 1 and Example 2 were measured, and as shown in FIG. 4, in addition to the strong emission band having a peak at 590 nm, a weak emission band having a peak at 610 nm was obtained. Was found to exist. The visual emission color was also slightly reddish.

As a result of examining the cause, 610n
The wavelength of m is In _0.5 (Ga _0.75 A of the active layers 20 and 26).
Since l _0.25 ) _0.5 P corresponds to the bandgap when (100) plane is formed, a part of the current is (10
The active layer 20 on the stripe-shaped flat portion 18, which is the (0) plane,
It was considered that the light had flowed into No. 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 shined slightly red. As a cause of this, p on the inclined surface 19
-Part of the current in the clad layers 21 and 25 flows into the p-clad layers 21 and 25 on the striped flat portion 18, and the carriers injected into the active layers 20 and 26 on the inclined surface 19 are absorbed. It is conceivable that some of them diffuse into the active layers 20 and 26 on the striped flat portion 18 and then recombine.

A third embodiment of the present invention will be described with reference to FIG. That is, FIG. 5 shows the upper surface and cross-sectional structure of a semiconductor chip of a yellow light emitting diode using InGaAlP and having an emission wavelength of 590 nm. Its structure is almost first
Although the same as the embodiment described above, a light-shielding film 31 having a width of 10 μm is formed on the surface of the epitaxial layer above the boundary between the striped flat portion 18 and the inclined surface 19 using the same material as the p-side electrode. Is different.

When the light output of the light emitting diode of the third embodiment was measured in the same manner as in the first and second embodiments, it was about 1.0 mW when the forward current was 20 mA, and the first embodiment was measured. A light output similar to that of the second embodiment was obtained. When the emission spectrum was measured, the emission band having a peak at 610 nm observed in the first and second examples was not observed. Even when observed with the naked eye, pure yellow luminescence was observed.

As described above, by forming the light shielding film 31 on the surface of the epitaxial layer above the region including all or part of the boundary between the striped flat portion 18 and the inclined surface 19, that is, the window layer 6 or the contact layer 8. , InGaAl
The light emitting diode made of the P-based material has excellent monochromaticity, and high light output can be 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 Se is used as the n-type impurity of the simultaneous doping layer 22 and Zn is used as the p-type impurity. However, other substrates and materials such as the case where the InGaAsP active layer 20 is formed on the InP semiconductor substrate 1 and other materials such as S, Mg, and Be whose doping efficiency changes depending on the plane orientation of the substrate. The same effect can be obtained by using impurities.

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

Due to such restrictions on each main surface, when the co-doping layer is provided on the P side with respect to the active layer as described in the above embodiment, the co-doping on the first main surface is performed. Since the layer serves as a current blocking layer, the electrode 7 may be formed thereabove. On the other hand, when the co-doping layer is provided on the n side of the active layer, the co-doping layer on the second main surface is the current blocking layer. Therefore, the electrode 7 is placed above it.
Should be formed.

Although the second main surface is provided on both sides of the first main surface in the above embodiment, it may be provided on only one side, that is, on one side of the first main surface. Furthermore, although the MOVPE method was used as the crystal growth method, other growth methods may be used.
Needless to say, a material other than the p-side electrode 7 may be used as the light shielding layer 31. Other various modifications can be made without departing from the scope of the present invention.

[0043]

According to the light emitting diode of claim 1, M
In 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, so that a so-called simultaneous doping layer in which both n-type and p-type impurities are simultaneously doped is formed. Then, 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 used as a blocking layer for the current flowing from the electrode, and thus the active layer immediately below the electrode can be formed. Inflow of current can be prevented.

As a result, the external extraction efficiency can be increased without using a special substrate, so that a light emitting diode having a high light output can be obtained, and since it can be manufactured by one crystal growth, it is excellent in productivity and can be made inexpensive. There is an effect. According to the light emitting diode of claim 2, claim 1
In the light emitting layer, at least the active layer is made of InGaAl.
Since it is formed of a P-based material, in addition to the effect of claim 1,
Since not only the external extraction efficiency but also the internal quantum efficiency can be increased, a higher light output can be obtained.

According to the third aspect of the present invention, in the light emitting diode according to the second aspect, the light shielding film is provided along the boundary above the window layer at the boundary between the first main surface and the second main surface. In addition to the effect of 2, it has excellent monochromaticity.

[Brief description of drawings]

FIG. 1 shows InGaAl in the first embodiment of the present invention.
It is a top view and sectional drawing of the semiconductor chip of the yellow light emitting diode of P.

FIG. 2 is a graph showing the tilt angle from the (100) plane to the (011) plane and the (0-1-1) plane of the growth substrate and the carrier concentration at the supply amount of the impurity raw material adopted in the first embodiment. It is a graph which shows a relationship.

FIG. 3 is a cross-sectional view of a semiconductor chip of an InGaAlP yellow light emitting diode according to a second embodiment.

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

5A and 5B are a top view and a sectional view of a semiconductor chip of an InGaAlP yellow light emitting diode according to a third embodiment.

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

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

[Explanation of symbols]

 17 semiconductor substrate 3 clad layer 6 window layer 7 and 9 electrode 18 striped flat part which is the first main surface 19 inclined surface which is the second main surface 20 and 26 active layer 21 and 25 clad layer 22 and 24 simultaneous doping layer

Claims (3)

[Claims] 1. The same plane as the (100) plane of the lattice plane, the direction from the (100) plane to the (011) plane, and the (0-1) plane.
-1) having a first main surface which is one of the surfaces inclined in any of the directions of the (1) plane on the surface, and has a (011) plane direction and a (0-1-) direction with respect to the first main plane. 1) It has a second main surface that is inclined in at least one of the surface directions and is arranged in parallel with the first main surface, and the angle formed by the first main surface and the (100) surface is 2 main surface and (10
The semiconductor substrate is made smaller than the angle formed by the (0) plane, a light emitting layer having a double hetero structure having a clad layer sandwiching the active layer, and n-type and p-type light emitting layers formed above or below the active layer. A simultaneous doping layer of both impurities, a window layer formed above the light emitting layer to take out the light generated in the active layer to the outside, the first main surface and the second main surface on the window layer A portion opposite to one side and an electrode formed on the back surface of the semiconductor substrate, and a portion of the co-doping layer immediately below the first electrode is a block layer for a current flowing from the first electrode. So that the plane orientations of the first main surface and the second main surface and the concentration of the impurities are set. 2. The light emitting layer comprises at least an active layer of InGa.
It is formed of an AlP-based material.
The light emitting diode described. 3. The light emitting diode according to claim 2, further comprising a light-shielding film on the upper side of the window layer along the boundary at the boundary between the first main surface and the second main surface.