JPH07335940A - Compound semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To obtain a high light emission intensity by a method wherein the smallest difference among energy differences between the acceptor levels and the donor levels of a light emitting layer is so selected as to be smaller than the energy differences between the acceptor levels and the donor levels of first and second current injection layers. CONSTITUTION:An n-type SiC layer 12 doped with Ga and N is built up first on one of the main surfaces of an n-type SiC substrate 11. Then a p-type SiC 13 doped with Al is built up on the layer 12. The n-type SiC substrate 11 and the p-type SiC layer 13 are used as current injection layers and the n-type SiC layer 12 is used as a light emitting layer. The smallest energy difference among energy differences between the acceptor levels and the donor levels of the light emitting layer is so selected as to be smaller than the energy differences between the acceptor levels and the donor levels of the first and second current injection layers. With this constitution, the probability that electron-positive hole pairs are captured by impurity levels is high and, as a result, a high light emission intensity is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to blue or ultraviolet wavelengths such as silicon carbide (SiC) gallium nitride (Ga).
N), aluminum nitride (AlN), boron nitride (B)
N) and a compound semiconductor light emitting device.

[0002]

2. Description of the Related Art A SiC compound semiconductor, which is a semiconductor material, has a band gap of 2.2 to 3.3 eV due to its crystal structure. Further, SiC is extremely stable thermally, chemically, and mechanically, and easily forms p-type and n-type conductivity types more easily than other semiconductor materials having a high band gap. Therefore, a semiconductor element in which electrodes for electrically connecting to an external circuit are formed on a SiC single crystal can be expected to have various applications such as a high temperature operation element, a high power element, a radiation resistant element, and a photoelectric conversion element. .

Among these various types, when applied to a light emitting element, it is produced as follows. As the SiC compound semiconductor, a hexagonal system (6H type) having a period of 6 molecular layers is used. SiC
Aluminum (Al) is added to the compound semiconductor to form a p-type layer, and nitrogen (N) is added to the compound semiconductor to form an n-type layer.
A layer to which Al and N are added is sandwiched between two layers.

In the forbidden band of the SiC compound semiconductor, Al forms an acceptor-level and N forms a donor-level. The acceptor level is formed slightly above the valence band, and the donor level is formed slightly below the conduction band.

Then, electrodes are provided on the p-type layer and the n-type layer, respectively. In the light emitting device thus formed, the layer between Al and N, which is sandwiched between the p-type and n-type layers, becomes the light-emitting layer. The p-type and n-type layers become current injection layers.

When a voltage is applied to the light emitting element in the forward direction, the potential barrier at the junction of the pn junction is lowered, so that electrons in the conduction band of the n-type current injection layer are directed toward the p-type current injection layer and again. Holes in the valence band of the current injection layer move toward the n-type current injection layer. The electrons that have flowed are trapped in the donation position of the light emitting layer. In addition, holes are trapped in the acceptor-deposition position of the light emitting layer.

The moving electrons / holes, that is, the minority carriers are forcibly moved by an electric field applied from the outside, so that they are unstable in an energy state higher than a normal thermal equilibrium state. Unstable electrons and holes in such a high energy state move to a lower energy state in an attempt to become more stable. The lowest state is that electrons and holes recombine and disappear. That is, the donor of the light emitting layer
The electrons trapped in the small position drop to the acceptor-small position of the light emitting layer, and are recombined with the holes captured in the acceptor-small position. At this time, a part of the extra energy emitted by the recombination becomes spontaneous emission light, and the device emits blue light.

In such a light emitting device, since the SiC is an indirect transition, its light emission intensity is small. The forbidden band width of the current injection layer is changed by using different materials for the light emitting layer and the current injection layer, which are used in the light emitting device using a III-V group semiconductor as a means for improving the emission intensity. A method using a so-called double hetero structure, in which carriers are confined in the light emitting layer by making the size smaller than that, is conceivable.

4H-type or 2H-type SiC is a substance having a band gap larger than that of 6H-type SiC. However, it is difficult with the current technology to fabricate a light emitting device having a double hetero structure by stacking 6H-type SiC with these substances sandwiched therebetween. That is, it is difficult to grow crystals of 4H type of 4 molecular layers and 2H type of 2 molecular layers on 6H type of 6 molecular layers.

[0010] By the way, there is known an example in which silicon (Si) and magnesium (Mg) are added to a light emitting layer also in a light emitting element using a compound semiconductor of III-V group containing nitrogen such as AlN or GaN. In this light emitting element, the light emitting layer is not sandwiched between the current injection layers, but the current injection layer is adjacent to one surface of the light emitting layer.

In such a light emitting element, a mixed crystal with indium (In) is often used in order to emit blue light, but it is difficult to add In, and it is particularly difficult to add In at a high concentration. Met. Therefore, an element having a large emission intensity has not been obtained.

[0012]

As described above, in the conventional light emitting device using the 6H type SiC compound semiconductor,
Since C is an indirect transition, its emission intensity is weak, and in order to improve the emission intensity, 6H type SiC is changed to 4H type and 2H type.
There is a problem in that it is difficult to create a double hetero structure by sandwiching the double hetero structure.

Further, in a light emitting device using AlN or GaN compound semiconductor, it is difficult to add In, which is added for emitting blue light, in a particularly high concentration, and therefore, a device having high emission intensity has not been obtained. There was a problem. Therefore, it is an object of the present invention to solve the above problems and provide a compound semiconductor light emitting device having high emission intensity.

[0014]

In order to solve the above problems, the present invention provides a first current injection layer of the first conductivity type and at least two kinds of impurities adjacent to the first current injection layer. And a second conductive type second layer adjacent to the light emitting layer.
In the compound semiconductor light emitting device comprising the IV-group of silicon carbide or the III-V group containing nitrogen, the narrowest energy difference between the acceptor and the donor level of the light-emitting layer is provided. There is provided a compound semiconductor light emitting device, characterized in that the energy difference is narrower than the energy difference between the acceptor and donor levels of the first and second current injection layers.

Here, the energy difference EΔ between the acceptor and donor levels of the first and second current injection layers is
When the same material is used for the current injection layer and the light emitting layer, the energy difference E ₁ between the acceptor level and the valence band and the donor level and the conduction band are calculated as in the following formula (1). The energy difference E ₂ between and is subtracted from the forbidden band width E _g .

EΔ = E _g − (E ₁ + E ₂ ) (1) This energy difference is the acceptor and the donor of the light emitting layer.
That the energy difference between the levels is wider than the narrowest energy difference means that at least one of the acceptor and the donor level of the light emitting layer has a depth of the first and second current injection layers. -And Donna-means deeper than the depth of the level. Here, the deep level means that the energy difference with the valence band is larger in the case of the acceptor level, and the energy difference with the conduction band is larger in the case of the donor level. Refers to.

The depths of the acceptor and donor levels of the light emitting layer other than those described above are the same as or shallower than the depths of the acceptor and donor levels of the first and second current injection layers. In the present invention, even in the shallow case of these two cases, the narrowest energy difference among the energy differences between the acceptor and the donor level of the light emitting layer is the first and second.
The energy difference between the acceptor level and the donor level of the current injection layer is made narrower.

The number of holes / electrons captured in the acceptor level / donor level is determined by the energy difference between the acceptor level and the valence band and between the donor level and the conduction band. If the acceptor is deep, holes go to the valence band, and if the donor level is deep, electrons are hard to reach the conduction band.
The number of holes / electrons trapped in the donor position increases.

In the light emitting device of the present invention, when the acceptor-level / donor-level depths in the current injection layer are compared with the acceptor-level / donor-level depths in the light-emitting layer, the acceptors in the light-emitting layer are compared. At least one of the level / donor level is deeper than the depth of the acceptor level / donor level of the current injection layer. Therefore, holes and electrons are more likely to be trapped in the deeper acceptor-decay / donor-level light-emitting layer than they are trapped in the shallower acceptor-decay / donor-level current injection layer. .

Therefore, in the light emitting layer, the acceptor-level is filled with holes or the donor-level is filled with electrons. Therefore, the probability of recombination of electrons and holes is increased, and the probability of light emission is increased, as compared with a conventional light emitting device in which the acceptor level and the donor level of the current injection layer and the light emitting layer are the same. As a result, the emission intensity increases.

Either the acceptor level or the donor level of the light emitting layer is the acceptor level or the donor level of the current injection layer.
When shallower than the level, for example, when the acceptor level of the light emitting layer is shallower than the acceptor level of the current injection layer,
Energy of the acceptor level between the light emitting layer and the current injection layer
If the energy difference in the donor level between the light emitting layer and the current injection layer is set to be larger than the difference, the probability that electrons and holes are recombined becomes higher than that in the conventional light emitting element.

Examples of materials that can be used for the current injection layer and the light emitting layer include SiC, AlN, GaN, BN, and mixed crystals thereof. 2H for SiC
Either 4H or 6H type may be used.

As a method for forming the current injection layer / light emitting layer, for example, when SiC is used, liquid phase growth (LPE)
Method, vapor phase epitaxy (CVD) method, molecular beam epitaxy (MB
The method E) or the like can be used. When using AlN or GaN, metalorganic chemical vapor deposition (MOCVD) method, MB
The E method / organic metal molecular beam epitaxy (MOMBE) method can be used.

When SiC is used as the impurity, for example, Al.gallium (Ga) .Boron (B) or the like can be used as the acceptor, and N.arsenic (As) or phosphorus (P) or the like can be used as the donor. When AlN or GaN is used, Mg.Zinc (Zn) is used as an acceptor.
・ Tellurium (T) as a donor such as cadmium (Cd)
e) -Si or the like can be used.

[0025]

According to the present invention, the narrowest energy difference between the acceptor and donor levels in the light emitting layer is the energy difference between the acceptor and donor levels in the first and second current injection layers. Since it is narrower than the energy difference, the probability that electrons / holes are trapped in the impurity level of the light emitting layer is increased, and as a result, the emission intensity is increased.

[0026]

EXAMPLES Examples will be described below. FIG. 1 shows a sectional view of a light emitting device according to a first embodiment of the present invention. This light emitting element is a pn junction type light emitting element made of 4H type SiC as a material.

In FIG. 1, reference numeral 11 denotes an n-type SiC substrate having a carrier concentration of 2 × 10 ¹⁸ cm ^-3 where N is a main impurity. On the one main surface of the n-type SiC substrate 11, a carrier concentration of Ga and N was first added by the LPE method to 5
An n-type SiC layer 12 having a thickness of × 10 ¹⁷ cm ⁻³ and a thickness of about 10 μm is laminated. Then, a p-type SiC layer 13 having a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ and a thickness of about 10 μm, to which Al is added, is formed.
Are stacked. The n-type SiC substrate 11 and the p-type SiC layer 13 are current injection layers, and the n-type SiC layer 12 is a light emitting layer.

Then, on the other main surface of the n-type SiC substrate 11, the Ni electrode 14 having a thickness of about 0.3 μm and the p-type SiC layer 1 are formed.
An Al electrode 15 having a thickness of about 2 μm is formed on the substrate 3 by sputtering.

Each of the electrodes was treated with an acid to be shaped into a predetermined shape, and then the electrode was subjected to about 1000 in argon gas.
Heat treatment is performed at ℃ for 5 minutes. By this heat treatment, the Ni electrode 14 and the Al electrode 15 react with SiC to a moderate degree to form an ohmic electrode.

Four Ni electrodes 14 and one Al electrode 15 are formed. The reason for such a shape will be described below. Since Ni and Al absorb light, it is preferable that the electrodes are small. However, if it is simply reduced, the current does not spread and the light emitting area becomes small. Therefore, a plurality of one electrodes are provided to spread the current.

In this way, the light emitting device is completed. As a comparative example to this example, FIG. 2 shows a sectional view of a light emitting device using the same 4H-type SiC. Regarding the numbers in the figure, the same parts as those in FIG. 1 are given the same numbers. The present comparative example is different only in that a Ga-added p-type SiC layer is used instead of the Al-added p-type SiC layer 13 of the first embodiment.

In FIG. 2, reference numeral 11 denotes an n-type SiC substrate having a carrier concentration of 2 × 10 ¹⁸ cm ^-3 where N is the main impurity. An n-type S having a carrier concentration of 5 × 10 ¹⁷ cm ⁻³ and a thickness of about 10 μm, to which gallium (Ga) and N are added, is first formed on one main surface of the n-type SiC substrate 11 by the LPE method.
The iC layer 12 is laminated. Then, a p-type SiC layer 21 having a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ and a thickness of about 10 μm, to which Ga has been added, is laminated on this.

Then, similar to the first embodiment, the Ni electrode 14 and the Al electrode 15 are formed to complete the light emitting device. Comparing the light emitting intensity of the light emitting device of the first embodiment with the light emitting intensity of the light emitting device of this comparative example, the light emitting device of the first embodiment shows that the light emitting device of the first embodiment has a forward current of the same magnitude. The luminescence intensity of the luminescent element was about 5 times. The luminescent color was blue.

In the first embodiment, the n-type SiC layer 1
2 is preferably about 5 to 30 μm, and the p-type SiC layer 13 is preferably about 10 to 30 μm. This is because if it is made too thick, it will absorb light, and if it is made too thin, the current will not spread.

The n-type SiC substrate 11 and the n-type SiC layer 1
The carrier concentration of impurities in the 2 · p-type SiC layer 13 is 10 ¹⁷
It is preferably about 10 ¹⁹ cm ^-3 . This is because when the carrier concentration is high, the current spreads but the light is easily absorbed, and when the carrier concentration is low, the opposite occurs.

In addition to the sputtering method, a vacuum vapor deposition method or the like can be used as a method for forming the electrodes. Here, FIG. 3 shows a cross-sectional view of a light emitting device obtained by improving the first embodiment. Regarding the numbers in the figure, the same parts as those in FIG. 1 are given the same numbers. This light emitting device has a p-type SiC layer 13
A p-type SiC layer 31 having a carrier concentration of approximately 2 × 10 ¹⁹ cm ⁻³ , which is a high concentration of Al added as a current diffusion layer, is stacked on top of the above. 10
The emission intensity was doubled.

Next, FIG. 4 shows a sectional view of a light emitting device according to a second embodiment of the present invention. This light emitting element is a 2H type Si
It is a light emitting element using C. In FIG. 4, 41 is an n-type S with a carrier concentration of 3 × 10 ¹⁷ cm ^-3 where N is a main impurity.
It is an iC substrate. 2H type SiC layers 42 to 44 are sequentially laminated on one main surface of this n type SiC substrate 41 by a CVD method. 42 is an n-type SiC layer having a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ , which is N as a main impurity, and a thickness of about 10 μm, 4
3 is a carrier concentration of 1 × 10 ¹⁷ c with Ga and N added.
m ⁻³ , an n-type SiC layer having a thickness of about 5 μm, and 44 is a p-type SiC layer having a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ and a thickness of about 10 μm, to which Al is added.

Then, a Ni electrode 45 having a thickness of about 1 μm and a p-type SiC layer 44 are formed on the other main surface of the n-type SiC substrate 41.
Then, a Ti electrode 46 having a thickness of about 1 μm is formed. The formation method is similar to that of the first embodiment, one Ni electrode 45, Ti
Three electrodes 46 are formed.

This light emitting device also showed the same light emission intensity as the light emitting device of the first embodiment. Although it depends on the current value, it has a peak of its emission spectrum at a wavelength of about 430 nm at a forward current of about 20 mA and exhibits a purple to blue emission color. Since 2H-type SiC has a larger forbidden band width than 4H-type SiC, when the carrier concentration is the same, the peak of the emission spectrum moves to the shorter wavelength side.

Next, FIG. 5 shows a sectional view of a light emitting device according to a third embodiment of the present invention. This light emitting element is a light emitting element using AlN. In FIG. 5, reference numeral 51 is a sapphire substrate. MOC is formed on one main surface of the sapphire substrate 51.
The AlN layers 52 to 54 are sequentially stacked by using the VD method. 5
2 is a p-type AlN layer having a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ with Cd added and a thickness of about 1 μm, and 53 is a carrier concentration of 1 × 10 ¹⁷ cm ⁻³ with Mg and Te added and a thickness of about 1 μm n. Type AlN layer, 54 is Te-added carrier concentration 2 × 10
The n-type AlN layer has a thickness of ¹⁸ cm ⁻³ and a thickness of about 3 μm.

After that, by etching, the p-type AlN layer 5 is formed.
2 is exposed, and a gold (Au) electrode 55 having a thickness of about 1 μm is formed on the p-type AlN layer 52, and an Au electrode 56 having a thickness of about 1 μm is formed on the n-type AlN layer 54 using a vacuum deposition method. After that, heat treatment is performed at a temperature of about 500 ° C. for about 5 minutes to form an ohmic electrode.

This light emitting device showed the same emission intensity as the light emitting device of Example 1, and had a peak of the emission spectrum at a wavelength of about 420 nm. FIG. 6 shows a sectional view of a light emitting device according to a fourth embodiment of the present invention. This light emitting element is a 2H type S
It is a light emitting element using iC.

In FIG. 6, reference numeral 61 denotes n-type SiC having a carrier concentration of 2 × 10 ¹⁸ cm ^-3 with N added as a main impurity.
The substrate. 2H type SiC layers 62 and 63 are sequentially laminated on one main surface of the n type SiC substrate 61 by the LPE method. 62 is a carrier concentration of 1 × with Al and As added.
An n-type SiC layer having a thickness of 10 ¹⁷ cm ⁻³ and a thickness of about 10 μm, and 63 is a p-type SiC layer having an Al-added carrier concentration of 2 × 10 ¹⁸ cm ⁻³ and a thickness of about 10 μm.

A Ni electrode 64 having a thickness of about 1 μm is formed on the other main surface of the n-type SiC substrate 61, and an Al electrode 65 having a thickness of about 3 μm is formed on the p-type SiC layer 63 in the same manner as in the first embodiment. This light emitting device also showed the same light emission intensity as in Example 1. The emission color was bluish green to blue.

FIG. 7 shows a sectional view of a light emitting device according to a fifth embodiment of the present invention. This light emitting element is a light emitting element using 2H type SiC. In FIG. 7, reference numeral 71 denotes n with a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ with N added as a main impurity.
Type SiC substrate. Carrier concentration of 1 × 1 in which B and oxygen (O) are added on one main surface of the n-type SiC substrate 71.
0 ¹⁷ cm ⁻³ , n-type SiC layer 72 with a thickness of about 5 μm, carrier concentration 2 × 10 ¹⁸ with Al added, and p with a thickness of about 10 μm.
The type SiC layers 73 are sequentially laminated using the LPE method.

Thereafter, a Ni electrode 74 is formed on the other main surface of the n-type SiC substrate 71 and an Al electrode 74 is formed on the p-type SiC layer 73 in the same manner as in the first embodiment. This light emitting device also showed the same light emission intensity as that of the light emitting device of Example 1. Although it depends on the current value, the emission color is generally green to yellow.

FIG. 8 shows a sectional view of a light emitting device according to a sixth embodiment of the present invention. This light emitting element is a light emitting element using 4H type SiC. In FIG. 8, 81 is an n having a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ with N added as a main impurity.
Type SiC substrate. An n-type SiC layer 8 having a carrier concentration of 1 × 10 ¹⁷ cm ⁻³ and a thickness of about 5 μm in which beryllium (Be) and As are added on one main surface of the n-type SiC substrate 81.
2. A p-type SiC layer 83 having a carrier concentration of 2 × 10 ¹⁸ cm and a thickness of about 10 μm to which Al is added is sequentially laminated by the LPE method.

After that, the Ni electrode 8 was formed in the same manner as in Example 1.
4. Al electrode 85 is formed. This light emitting device is also the first embodiment.
The same luminescence intensity as that of the light emitting device of No. Wavelength 400
~ Purple with peak of emission spectrum at about 450nm ~
It exhibited a blue emission color.

FIG. 9 is a sectional view of a light emitting device according to the seventh embodiment of the present invention. This light emitting element is a light emitting element using 2H type SiC. In FIG. 9, 91 is n with a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ with N added as a main impurity.
Type SiC substrate. Carrier concentration of 1 × 10 5 with B, Ga and N added on one main surface of the n-type SiC substrate 91.
¹⁷ cm ^-3 , n-type SiC layer 92 with a thickness of about 5 μm, carrier concentration 2 × 10 ¹⁸ cm ^-3 with Al added, thickness of about 10 μm
The p-type SiC layer 93 is sequentially laminated by the LPE method.

Thereafter, the Ni electrode 9 is formed in the same manner as in Example 1.
4. Form the Al electrode 95. This light emitting device is also the first embodiment.
The same luminescence intensity as that of the light emitting device of No. Further, since the light emitting layer contains impurities that are the origin of different emission colors, various colors from ultraviolet to blue can be exhibited depending on the current value.

FIG. 10 is a sectional view of a light emitting device according to the eighth embodiment of the present invention. This light emitting device is a light emitting device using a nitride semiconductor. In FIG. 10, 101 is a sapphire substrate, and 102 is a buffer layer for alleviating the lattice mismatch between the substrate and the upper nitride semiconductor layer.

On the buffer layer 102, an n-type GaN layer 103 having a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ and a thickness of about 3 μm added with Si, and Si and zinc (Zn) are formed by MOCVD.
Carrier concentration with addition of 1 × 10 ¹⁷ and thickness of about 0.5 μm
N-type InGaN layer 104, a p-type GaN layer 10 having a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ and a thickness of about 1 μm, to which Mg is added.
5 are sequentially laminated.

After that, the Au electrode 1 was formed in the same manner as in Example 3.
The 06.Au electrode 107 is formed. This light emitting device also showed the same light emission intensity as that of the light emitting device of Example 1. The wavelength of emitted light can be changed by changing the ratio between In and Ga in the light emitting layer. For example, In / (G
a + In) is set to 0 to 0.3, the wavelength is 455 to
It is possible to obtain light emission having a peak of about 540 nm,
If this ratio is 0.1 to 0.25, the wavelength is 480 to 520.
It is possible to obtain green emission of about nm.

FIG. 11 is a sectional view of a light emitting device according to the ninth embodiment of the present invention. This light emitting device is a light emitting device using a nitride semiconductor. In FIG. 11, 111 is a sapphire substrate, and 112 is a buffer layer for alleviating the lattice mismatch between the substrate and the upper nitride semiconductor layer.

A carrier concentration of 2 × 10 ¹⁸ cm ⁻³ containing Si and an n-type AlGaN layer 113 having a thickness of about 3 μm and a carrier concentration of 1 × 10 containing Si and Zn are formed on the buffer layer 112 by MOCVD. ¹⁷ cm ^-3 , thickness about 0.5μ
m n-type GaN layer 114, Mg-added p-type AlGaN layer 1 having a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ and a thickness of about 1 μm.
15 are sequentially laminated.

After that, the Au electrode 1 was formed in the same manner as in Example 3.
16 · Au electrode 117 is formed. This light emitting device also showed the same light emission intensity as that of the light emitting device of Example 1. The emission color was bluish purple to blue.

Here, the emission intensity varies depending on the added impurities, but also varies depending on the composition ratio of the AlGaN layers 113 and 115. For example, Al / (Al + G
When the ratio of a) is 0.1 to 0.4, electrons and holes are efficiently injected, but in a region exceeding this range,
In particular, it becomes very difficult to make an ohmic contact with the p-type AlGaN layer 115. For this reason, the electric resistance in the electrode portion increases, and the luminous efficiency decreases. From this point, the ratio of Al / (Al + Ga) is preferably 0.2 to 0.3 in order to improve the luminous efficiency.

[0058]

As described above, according to the present invention, it is possible to provide a light emitting device having a high emission intensity.

[Brief description of drawings]

FIG. 1 is a sectional view of a light emitting device according to a first embodiment of the invention.

FIG. 2 is a cross-sectional view of a light emitting device according to a comparative example with respect to Example 1 of the present invention.

FIG. 3 is a sectional view of a light emitting device according to a first embodiment of the invention.

FIG. 4 is a sectional view of a light emitting device according to a second embodiment of the invention.

FIG. 5 is a sectional view of a light emitting device according to a third embodiment of the invention.

FIG. 6 is a sectional view of a light emitting device according to a fourth embodiment of the invention.

FIG. 7 is a sectional view of a light emitting device according to a fifth embodiment of the invention.

FIG. 8 is a sectional view of a light emitting device according to Example 6 of the present invention.

FIG. 9 is a sectional view of a light emitting device according to Example 7 of the present invention.

FIG. 10 is a sectional view of a light emitting device according to Example 8 of the present invention.

FIG. 11 is a sectional view of a light emitting device according to Example 9 of the present invention.

[Explanation of symbols]

 11, 41 ... N-type SiC substrate 12, 42, 43 ... N-type SiC layer 13, 44 ... P-type SiC layer 51, 101, 111 ... Sapphire substrate 52 ... P-type AlN layer 53, 54 ... N-type AlN layer 102, 112 ... Buffer layer 103, 114 ... N-type GaN layer 104 ... N-type InGaN layer 105 ... P-type GaN layer 113 ... N-type AlGaN layer 115 ... P-type AlGaN layer

Claims (1)

[Claims] 1. A first current injection layer of a first conductivity type, a light emitting layer adjacent to the first current injection layer and containing at least two kinds of impurities, and a second current conductivity type adjacent to the light emission layer. Second
In the compound semiconductor light emitting device comprising the group IV of silicon carbide or the group III-V containing nitrogen, the narrowest energy difference among the energy difference between the acceptor and the donor level of the light emitting layer is provided. A compound semiconductor light emitting device, characterized in that the difference is narrower than the energy difference between the acceptor and donor levels of the first and second current injection layers.