JP2001291900A - Semiconductor light-emitting device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single-chip semiconductor light-emitting device which is easily manufactured and provides a bright white emission. SOLUTION: Boron and the like is ion-implanted into a surface layer of an n-type SiC substrate 10 in which nitrogen is doped, to form an n-type SiC 11. On the n-type SiC 11, there are sequentially laminated an n-type nitride semiconductor layer 12, an n-type AlGaN layer 13, an InGaN layer 14, a p-type AlGaN layer 15, and a p-type GaN layer 16. An n-type ohmic electrode 20 is formed on the rear surface of the n-type SiC substrate 10 while forming a p-type ohmic electrode 21 on the front surface of the p-type GaN layer 16. With this configuration, if a voltage is applied in forward direction between the p-type ohmic electrode 21 and the n-type ohmic electrode 20, a current flows between both electrodes so that the InGaN layer 14 emits blue light. Excited by the blue light, the n-type SiC 11 emits yellow light. The two colors are combined to allow emission close to white.

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 used as a semiconductor light emitting element and a method for manufacturing the same.

[0002]

2. Description of the Related Art White light emission by a light emitting diode (LED) has the potential to replace commonly used incandescent and fluorescent lamps because of its small size, light weight, long life, and low power consumption. .

[0003] As a method of obtaining white light emission using an LED, a method of obtaining white light by combining red, green, and blue LEDs, and a method of combining white light with a blue LED and a phosphor that emits yellow light by excitation of blue light. There is a way to get it.

[0004] However, the former has a problem that the cost is high because three LEDs are required, and the latter has a high cost due to the use of a phosphor and the efficiency of emission to the outside is poor. Problem.

On the other hand, a method of obtaining white light emission with one LED chip has been devised. One is a blue LED made of ZnSe and Zn emitting yellow light by excitation of blue light.
A method of obtaining white color by combining with a Se substrate (see Nikkei Electronics May 17, 1999, p. 743);
The other is a method of producing an LED structure in which active layers that emit red, green, and blue light are stacked to obtain white light (see Japanese Patent Application Laid-Open No. 9-232627).

[0006]

According to the above-described methods, white light emission can be obtained with only one LED chip.

However, in the former method, ZnSe
Since a light emitting element that emits blue light is manufactured by using
There is a problem that the blue light emission intensity is low and the lifetime is short as compared with the light emitting element of (1). In the latter method, there is a problem that it is difficult to grow a crystal that emits light of three colors and that the driving voltage is high.

An object of the present invention is to provide a semiconductor light emitting device capable of obtaining white light emission of high luminance with a one-chip light emitting device which can be easily manufactured, and a method of manufacturing the same.

[0009]

To achieve the above object, according to the first aspect of the present invention, a silicon carbide substrate (10) is provided.
And a light emitting element (12 to 16) that emits blue light formed on the silicon carbide substrate, and the silicon carbide substrate is excited by the blue light emitted from the light emitting element to emit yellow light. It is characterized by:

[0010] As described above, by causing the silicon carbide substrate to emit yellow light, the blue light from the light emitting element and the yellow light from the substrate are combined, and white light is produced by one chip. A light emission color close to

According to a second aspect of the present invention, the silicon carbide substrate is doped with at least one of boron, nitrogen and boron, nitrogen and gallium, nitrogen and scandium, or nitrogen and beryllium. .

By introducing these impurities, yellow luminescence is obtained from the silicon carbide substrate, and it is possible to obtain strong white luminescence. Note that if impurities are introduced into a wide area of the silicon carbide substrate, yellow light emission can be obtained over a wide area. Further, even if the impurity is introduced only into a part of the silicon carbide substrate, it is possible to obtain sufficient yellow light emission from the part. In this case, there is a region into which impurities are not introduced, and the internal resistance value of this region does not change. Therefore, it is possible to prevent the electric characteristics of the element from being changed due to the change in the resistance value due to the introduction of the impurity.

According to a third aspect of the present invention, the light emitting element is formed of a nitride-based compound semiconductor. As a result, a strong blue light emission intensity is obtained, and as a result, a light color with a strong white color can be emitted.

According to the fourth aspect of the present invention, the color emitted from the light emitting element and the color emitted from the silicon carbide substrate have a complementary color relationship, and the color emitted from the light emitting element and the color emitted from the silicon carbide substrate. It is characterized in that white light is emitted in combination with colors.

As described above, by emitting a complementary color from the light emitting element, white light can be emitted by one chip.

According to a fifth aspect of the present invention, a first conductivity type silicon carbide substrate (10), a first conductivity type semiconductor layer (12) formed on the silicon carbide substrate, A first conductive type clad layer (13) formed thereon, an active layer (14) formed on the first conductive type clad layer and emitting blue light, and a second conductive layer formed on the active layer. A second electrode (20) formed on the back surface of the silicon carbide substrate; a first electrode (21) formed on the second conductivity type clad layer; Wherein the silicon carbide substrate is doped with at least one of boron, nitrogen and boron, nitrogen and gallium, nitrogen and scandium, or nitrogen and beryllium.

With such a configuration, the same effects as those of the first and second aspects can be obtained. In this case, too, the impurity may be introduced into a wide area of the silicon carbide substrate, or the impurity may be introduced into a part of the silicon carbide substrate.

According to a seventh aspect of the present invention, an n-type silicon carbide substrate (10) doped with nitrogen, an n-type semiconductor layer (12) formed on the n-type silicon carbide substrate, and a semiconductor layer An n-type cladding layer (13) formed thereon and an active layer (14) formed on the cladding layer and emitting blue light
And a p-type cladding layer (15, 1
6), a first electrode (21) formed on the p-type cladding layer, and a second electrode (20) formed on the back surface of the semiconductor substrate. At least one of boron, gallium, scandium, and beryllium is doped.

With such a structure, the same effects as those of the first and second aspects can be obtained, and the driving voltage can be further reduced because the n-type silicon carbide substrate having electrons as majority carriers is used. it can. In this case, too, the impurity may be introduced into a wide area of the silicon carbide substrate, or the impurity may be introduced into a part of the silicon carbide substrate.

According to the invention described in claim 8, the active layer is made of a nitride-based compound semiconductor. As a result, a strong blue light emission intensity is obtained, and as a result, a light color with a strong white color can be emitted.

According to the ninth aspect of the present invention, the active layer comprises:
(Al _x Ga _1-x ) _y In _1-y N (0 ≦ x ≦ 1, 0 ≦ y ≦
1). With such a structure, light of a wide range of wavelengths can be obtained from the active layer serving as a light-emitting element. As a result, various white colors (for example, white with slightly different color tones, yellow, and white close to pink) can be obtained. Can emit light.

According to the tenth aspect of the present invention, the color emitted from the active layer and the color emitted from the silicon carbide substrate have a complementary color relationship, and the color emitted from the active layer and the light emitted from the silicon carbide substrate are complementary. It is characterized in that white light is emitted in combination with colors. Thereby, the same effect as the fourth aspect can be obtained.

According to an eleventh aspect of the present invention, the silicon carbide substrate is made of 6H-SiC, 4H-SiC or 15R-SiC. With these substrates,
Yellow luminescence is obtained from the substrate, and as a result, a luminescent color close to white with strong intensity can be emitted.

According to a twelfth aspect of the present invention, boron, nitrogen and boron, nitrogen and gallium, nitrogen and scandium, or nitrogen and beryllium, which are impurities, are introduced into the silicon carbide substrate (10) having conductivity. The process of
A step of epitaxially growing a nitride-based compound semiconductor layer (12 to 16) to be a light emitting section on a silicon carbide substrate; a step of forming a first electrode (21) on the semiconductor layer to be a light emitting section; Forming a second electrode (20) on the back surface of the substrate.

As described above, by introducing any of boron, nitrogen and boron, nitrogen and gallium, nitrogen and scandium, or nitrogen and beryllium into a silicon carbide substrate, yellow light can be emitted, and one chip can emit light. Emission of a light emission color close to white can be emitted.

For example, any one of boron, gallium, scandium, and beryllium which is an impurity may be introduced into an n-type silicon carbide substrate doped with nitrogen.

The invention according to claim 14 is characterized in that a step of introducing carbon into a region of the silicon carbide substrate into which the impurity is introduced is included before introducing the impurity.

As described above, by introducing carbon into the silicon carbide substrate, the activation rate of impurities is improved, and a strong yellow light can be emitted.

Note that the reference numerals in parentheses of the above-mentioned means indicate the correspondence with specific means described in the embodiments described later.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) The embodiment shown in the drawings will be described below.

FIG. 1 shows a sectional configuration of a semiconductor light emitting device according to the first embodiment of the present invention. Hereinafter, the configuration of the semiconductor light emitting device will be described with reference to FIG.

As shown in FIG. 1, the surface portion of the (0001) plane of the n-type SiC substrate 10 doped with nitrogen is
An n-type SiC 11 is formed. This n-type SiC11
Is formed by ion-implanting boron as an impurity into the surface of the n-type SiC substrate 10.

On the n-type SiC substrate 10, a plurality of nitride-based compound semiconductors constituting a light emitting element are arranged. First, an n-type nitride semiconductor layer 12 and an n-type AlGaN layer 13 are formed on an n-type SiC substrate 10. Of these, the n-type AlGaN layer 13 corresponds to the n-type cladding layer. Further, an InGaN layer 14 as an active layer is provided on the n-type AlGaN layer 13. Further, a p-type AlGaN layer 1 is formed on the InGaN layer 14.
5 and a p-type GaN layer 16 are sequentially stacked. This p-type AlGaN layer 15 corresponds to a p-type cladding layer.

Further, the n-type SiC substrate 10 has n
A type ohmic electrode 20 is formed, and a p-type ohmic electrode 21 is formed on the surface of the p-type GaN layer 16.

Next, the operation of the semiconductor light emitting device having the above configuration will be described with reference to the sectional view shown in FIG.

First, when a voltage is applied in the forward direction between the p-type ohmic electrode 21 and the n-type ohmic electrode 20, a current flows between the two electrodes 21 and 20. At this time, since the active layer is composed of the InGaN layer 14 which is a nitride-based compound semiconductor, the InGaN layer 1
4 emits blue light. Then, part of this blue light emission goes to the front surface, and part goes to the back surface. Then, the light directed to the back surface passes through the n-type SiC 11. Then
When excited by blue light, electron-hole pairs are generated in the n-type SiC 11 and recombine at the level between nitrogen and boron.
As a result, yellow light emission is obtained.

As described above, yellow light is emitted from the n-type SiC 11 and blue light is emitted from the InGaN layer 14 as an active layer. Therefore, when these two complementary colors are combined, from the surface of the semiconductor light emitting device, Light close to white is emitted.

The intensity and wavelength of yellow light emission from the n-type SiC substrate 10 vary depending on the amount and activation rate of nitrogen, boron and the like doped in the SiC substrate, and the thickness of the doped region. Gives an emission spectrum having a peak of about 550 nm to 590 nm. By combining this spectrum with a blue wavelength emitted from the light-emitting element, white or a color close to white can be emitted.

As described above, n-type SiC made of silicon carbide
By using the substrate 10, the blue light from the InGaN layer 14 and the yellow light from the n-type SiC substrate 10 are combined, so that a near-white luminescent color can be emitted with one chip.

Next, a manufacturing process of the semiconductor light emitting device shown in FIG. 1 is shown in FIG. 3, and a method of manufacturing the semiconductor light emitting device will be described with reference to FIG.

First, as shown in FIG. 3A, for example,
An n-type SiC substrate 10 doped with nitrogen is prepared. After the SiC substrate 10 is heated to a high temperature of, for example, 500 ° C. or more, boron is ion-implanted into the surface of the n-type SiC substrate 10, and then activation annealing is performed. Thereby, as shown in FIG. 3B, the n-type SiC 1 having a depth of about 1 μm is formed.
1 is formed.

Here, although boron is a p-type dopant, the n-type carrier concentration due to nitrogen is higher than the p-type carrier concentration due to boron.
Is n-type, but the carrier concentration is lower than that of n-type SiC substrate 10.

At this time, carbon may be ion-implanted before boron is ion-implanted. By doing so, the activation rate of boron can be improved, and the emission intensity of yellow light can be improved.

Subsequently, FIG.
As shown in FIG. 1, an n-type nitride semiconductor layer 12, an n-type AlGaN layer 13, an InGaN layer 1
4. The p-type AlGaN layer 15 and the p-type GaN layer 16 are sequentially epitaxially grown. Then, as shown in FIG. 3D, an n-type ohmic electrode 20 is formed on the back surface of the n-type SiC substrate 10, and a p-type ohmic electrode 21 is formed on the p-type GaN layer 16. Thus, the semiconductor light emitting device shown in FIG. 1 is completed.

(Second Embodiment) In the first embodiment, boron is ion-implanted into the n-type SiC substrate 10 so that n-type S
Although the iC 11 is formed, a substrate obtained by doping nitrogen and boron and growing crystals from the beginning may be used as the n-type SiC substrate 10.

In this case, directly on the n-type SiC substrate 10,
n-type nitride semiconductor layer 12, n-type AlGaN layer 13, In
GaN layer 14, p-type AlGaN layer 15, p-type GaN layer 1
6 are sequentially laminated. Then, an n-type ohmic electrode 20 is formed on the back surface of the n-type SiC substrate 10 and the p-type GaN layer 16 is formed.
When the p-type ohmic electrode 21 is formed on the surface of the semiconductor light emitting device, the semiconductor light emitting device is completed.

(Other Embodiments) In the first embodiment,
N-type SiC substrate 1 doped with boron
0, but it is not limited to this position.
For example, it may be formed on the back surface of the n-type SiC substrate 10,
Moreover, you may form on both surfaces.

Further, boron is introduced into only a part of the surface of the n-type SiC substrate 10 instead of the entire surface, and the n-type SiC
C11 may be formed. If boron is introduced into the entire surface of the n-type SiC substrate 10, yellow light can be obtained in a wide range. However, even if boron is introduced into only a part, sufficient yellow light can be obtained from a part thereof. It is possible. In this case, since boron is not introduced into the entire surface of the n-type SiC substrate 10, there is a region where boron is not introduced,
In this region, the internal resistance value does not change. That is, the region into which boron is introduced has high resistance because the n-type semiconductor is compensated by boron, but the region into which boron is not introduced does not have high resistance. Therefore, it is possible to prevent the electrical characteristics of the element from changing due to a change in the resistance value.

In each of the above embodiments, boron has been described as an example of the p-type impurity.
Gallium, scandium, or beryllium may be used.

In each of the above embodiments, the active layer is made of In.
Although the GaN layer 14 is used, the active layer is made of (Al _x Ga _1-x )
_y In _1-y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) may be used. With such a configuration, light of a wide range of wavelengths can be obtained from the active layer, and as a result, various kinds of white light (for example, white having slightly different color tones, yellow, and white close to pink) can be emitted. Can be.

Although the substrate is n-type in each of the above embodiments, the substrate may be p-type and the conductivity type of each layer may be reversed. However, in the case of an n-type substrate, the driving voltage can be further reduced because electrons are majority carriers.

Further, the semiconductor light emitting device shown in FIG. 1 may be turned upside down to emit near-white light, which is a combination of blue and yellow, from the substrate side. Furthermore, the MOCVD method was used as the epitaxial growth method.
MBE (molecular beam epitaxial growth) may be used.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a cross-sectional configuration of a semiconductor light emitting device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an operation of the semiconductor light emitting device shown in FIG. 1;

FIG. 3 is a diagram showing a manufacturing process of the semiconductor light emitting device shown in FIG.

[Explanation of symbols]

10 ... n-type SiC substrate, 11 ... n-type SiC, 12 ... n-type nitride semiconductor layer, 13 ... n-type AlGaN layer, 14 ... In
GaN layer, 15 ... p-type AlGaN layer, 16 ... p-type GaN
Layers, 20 ... n-type ohmic electrode, 21 ... p-type ohmic electrode.

Claims (14)

[Claims] 1. A silicon carbide substrate (10) and a light emitting element (12 to 1) emitting blue light formed on the silicon carbide substrate.
6), wherein the silicon carbide substrate emits yellow light when excited by the blue light emitted from the light emitting element. 2. The silicon carbide substrate according to claim 1, wherein at least one of boron, nitrogen and boron, nitrogen and gallium, nitrogen and scandium, or nitrogen and beryllium is doped. Semiconductor light emitting device. 3. The semiconductor light emitting device according to claim 1, wherein the light emitting element is formed of a nitride-based compound semiconductor. 4. A color emitted from the light emitting element and a color emitted from the silicon carbide substrate have a complementary color relationship, and a color emitted from the light emitting element and a color emitted from the silicon carbide substrate are different from each other. 4. The light source according to claim 1, wherein white light is emitted in combination.
4. The semiconductor light emitting device according to any one of the above. 5. A first conductivity type silicon carbide substrate (10), a first conductivity type semiconductor layer (12) formed on the silicon carbide substrate, and a first conductivity type semiconductor layer formed on the semiconductor layer. A conductive clad layer (13), an active layer (14) formed on the clad layer and emitting blue light, and a second conductive clad layer (1) formed on the active layer.
5, 16), a first electrode (21) formed on the second conductivity type cladding layer, and a second electrode (2) formed on the back surface of the silicon carbide substrate.
0), wherein the silicon carbide substrate is doped with at least one of boron, nitrogen and boron, nitrogen and gallium, nitrogen and scandium, or nitrogen and beryllium. 6. The silicon carbide substrate, wherein a region doped with any of boron, nitrogen and boron, nitrogen and gallium, nitrogen and scandium, or nitrogen and beryllium has a first conductivity type. Claim 5
The semiconductor light emitting device according to claim 1. 7. An n-type silicon carbide substrate (10) doped with nitrogen, and an n-type semiconductor layer (1) formed on the n-type silicon carbide substrate.
2), an n-type cladding layer (13) formed on the semiconductor layer
An active layer (14) formed on the cladding layer and emitting blue light; and a p-type cladding layer (15, 1) formed on the active layer.
6), and a first electrode (2) formed on the p-type cladding layer.
1) and a second electrode (20) formed on the back surface of the semiconductor substrate
Wherein the n-type silicon carbide substrate is doped with at least one of boron, gallium, scandium, and beryllium. 8. The semiconductor light emitting device according to claim 5, wherein said active layer is a nitride-based compound semiconductor. 9. The active layer is composed of (Al _x Ga _{1 -x} ) _y In.
9. The semiconductor light emitting device according to claim 5, wherein _1-y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1). 10. A color emitted from the active layer and a color emitted from the silicon carbide substrate have a complementary color relationship, and a color emitted from the active layer and a color emitted from the silicon carbide substrate are different from each other. 10. The semiconductor light emitting device according to claim 5, wherein white light is emitted in combination. 11. The silicon carbide substrate is 6H—SiC,
The semiconductor light emitting device according to any one of claims 1 to 10, wherein the device is H-SiC or 15R-SiC. 12. A silicon carbide substrate having electrical conductivity.
Introducing boron, nitrogen and boron, nitrogen and gallium, nitrogen and scandium, or nitrogen and beryllium into the silicon carbide substrate; and a nitride-based compound semiconductor layer (12 To 16), a step of forming a first electrode (21) on the semiconductor layer to be the light emitting section, and a step of forming a second electrode (20) on the back surface of the silicon carbide substrate. And a method for manufacturing a semiconductor light emitting device. 13. A step of introducing one of boron, gallium, scandium, or beryllium as an impurity into an n-type silicon carbide substrate (10) doped with nitrogen, and forming a light emitting portion on the silicon carbide substrate. A step of epitaxially growing a nitride-based compound semiconductor layer (12 to 16); a step of forming a first electrode (21) on the semiconductor layer to be the light emitting portion; and a second electrode on the back surface of the silicon carbide substrate Forming a semiconductor light emitting device. 14. The method according to claim 1, further comprising a step of introducing carbon into a region of the silicon carbide substrate into which the impurity is introduced, before introducing the impurity.
14. The method for manufacturing a semiconductor light emitting device according to 2 or 13.