JP2002185043A - Method of manufacturing class iii-v compound semiconductor light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a light-emitting element using a class 3-5 compound semiconductor, which is easy to mount electrodes and has an improved light pickup efficiency. SOLUTION: For manufacturing a light-emitting element having a light emitting layer and a substrate, using a class 3-5 compound semiconductor expressed by a general formula InxGayAlzN (x+y+z=1, 0<=x<=1, 0<=y<=1 and 0<=z<=1), the light-emitting layer is sandwiched between two layers having a light- reflecting function, at least one of the two layers is a laminate of repetitions of two kinds of layers which are expressed by a general formula Ga1-aAlaN (0<=a<=1) and different in mixed crystal ratio, the refractive index and the thickness of each of layers involved in a region sandwiched between the two layers having the reflective function are adjusted to meet the equation (1), and the light-emitting layer position is adjusted for a maximum electric field of a light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device using a nitride group III-V compound semiconductor.

[0002]

2. Description of the Related Art Conventionally, a blue light emitting diode (hereinafter referred to as L
Sometimes referred to as ED. ), As a light-emitting element such as a semiconductor laser, the general formula In _x Ga _y Al _z N (provided that, x +
A semiconductor using a Group 3-5 compound semiconductor represented by y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) is used. Since the compound semiconductor is a direct transition type, it has a high luminous efficiency, and depends on the InN mixed crystal ratio x from red to yellow,
Since it can emit light at emission wavelengths in the green, blue, violet, and ultraviolet regions, it is particularly useful as a material for a light emitting element.

In the LED using the compound semiconductor, there are two methods of extracting light, a method of extracting light from a substrate made of sapphire and a method of extracting light from a semiconductor.
In the method of extracting light from the substrate side, high extraction efficiency is obtained because it is extracted through sapphire of the transparent substrate,
Since sapphire is insulative, it is difficult to attach electrodes, the LED assembly process is complicated, and there is a problem that existing LED manufacturing equipment cannot be used. On the other hand, in the method of extracting light from the semiconductor side, although the electrodes can be attached relatively easily, there is a problem that light extraction efficiency is reduced due to reflection and absorption at the electrodes. As a method of avoiding this, there is known a method of increasing the light transmittance by thinning the electrodes and performing heat treatment (Japanese Patent Application Laid-Open No. Hei 6-314822). However, even in this method, the light transmittance at the electrode is not sufficiently high, and the extraction efficiency is still insufficient because the light emitted from the light emitting layer to the substrate side is insufficiently used.

An LED using the compound semiconductor is
Increasing the value of the InN mixed crystal ratio x of the light-emitting layer makes it possible to obtain blue, green, yellow, orange, and red sequentially long-wavelength light from ultraviolet light. As a result, the color purity is deteriorated. Further, when the value of the InN mixed crystal ratio x of the light emitting layer is increased,
Since the crystallinity is also reduced, there has been a problem that the luminous efficiency is rapidly reduced.

[0005]

SUMMARY OF THE INVENTION It is a first object of the present invention to provide a light emitting device using a group III-V compound semiconductor, in which electrodes can be easily attached and light extraction efficiency is improved. Further, a second object of the present invention is to provide a semiconductor device comprising:
Even if the N mixed crystal ratio x increases, the half-width of the emission spectrum is small, the color purity is good, and the luminous efficiency is high.
An object of the present invention is to provide a light-emitting element using a group III compound semiconductor.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies in view of such circumstances, and as a result, have found that two types of mixed crystal ratios in which the thickness of each layer is adjusted to １ ／ of the emission wavelength. Ga
By providing a lamination made of _1-a Al _a N between the substrate and the light emitting layer, light emitted from the light emitting layer to the substrate side is effectively reflected by this laminated structure, and the light extraction efficiency from the semiconductor side is improved. It has been found that it is possible to cause the present invention. Furthermore, a structure having a reflection function is introduced above and below the light-emitting layer, and the refractive index and the layer thickness of each layer included in the region sandwiched by the reflection function structure are adjusted so as to have a specific relationship with the emission wavelength. As a result, the present inventors have found that the half width of the emission spectrum can be made extremely narrower than before, and that a high luminous efficiency can be obtained even when the InN mixed crystal ratio is increased.

That is, the present invention relates to [1] the general formula In _x Ga
_y Al _z N (x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦
1, 0 ≦ z ≦ 1) In a light-emitting element having a light-emitting layer and a substrate using a Group 3-5 compound semiconductor represented by the formula: Ga _1-a Al _a N (0
≦ a ≦ 1) and a stack of two types of layers having different mixed crystal ratios from each other, and the thickness of each layer is λ / 4n ₁ , λ / 4n ₂ (where λ Is the emission wavelength, and n ₁ and n ₂ are the respective refractive indices of the two types of layers at the emission wavelength.)

The present invention also relates to [2] the general formula In _x Ga
_y Al _z N (x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦
1, 0 ≦ z ≦ 1) In a light-emitting element having a light-emitting layer and a substrate, the light-emitting layer is sandwiched between two layers having a light reflecting function. At least one of the two layers has the general formula Ga _1-a Al _a
N (0 ≦ a ≦ 1), a layer composed of a repetition of two types of layers having different mixed crystal ratios, and included in a region sandwiched between the two layers having the reflection function. The present invention relates to a Group 3-5 compound semiconductor light emitting device in which the refractive index and the thickness are adjusted so that the following relationship is established between the emission wavelength and the emission wavelength.

(Equation 1) (Where d is the thickness of each layer, n is the refractive index at the emission wavelength of each layer, λ is the emission wavelength, m is an integer of 1 or more, and the subscript i
Represents the number of the light emitting layer, the subscript j represents the number of the layer other than the light emitting layer included in the region sandwiched between the structures having the upper and lower reflective functions, and Δ represents that the sum of the subscript numbers is taken. )

Further, the present invention relates to [3] the general formula Ga _1-a A
In _a laminate composed of two types of layers represented by laN (0 ≦ a ≦ 1) and having different mixed crystal ratios, all or some of the layers in the laminate are n-type or p-type. [3] The compound semiconductor light-emitting device according to [1] or [2], which has a conductivity of: Further, the present invention provides [4] a light emitting layer having a thickness of 5 ° or more and 90 ° or less, and the light emitting layer is sandwiched on both sides thereof in contact with a layer having a band gap larger than that of the light emitting layer [1],
The present invention relates to the group 3-5 compound semiconductor light-emitting device according to [2] or [3]. Further, according to the present invention, [5] the concentration of each element of Si, Ge, Mg, Zn and Cd contained in the light emitting layer is 10 ¹⁹ cm ⁻³ or less [1],
The present invention relates to the light emitting device according to [2], [3] or [4].

[0010]

Next, the present invention will be described in detail.
The Group 3-5 compound semiconductor in the present invention is represented by the general formula In
_x Ga _y Al _z N (provided that, x + y + z = 1,0 ≦ x ≦
1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) and includes a stack thereof. In particular, p
A light-emitting layer between the compound semiconductor of n-type and n-type;
A light-emitting element having a structure in which the light-emitting layer is sandwiched on both sides by a layer having a band gap larger than that of the light-emitting layer is called a double hetero structure and is particularly important because it can emit light with high luminous efficiency.

The substrate on which the group III-V compound semiconductor is grown is sapphire, SiC, Si, GaAs, Zn.
O, NGO (NdGaO ₃ ), spinel (MgAl ₂ O)
₄ ), GaN or the like can be used. Among them,
Sapphire, spinel (MgAl ₂ O ₄ ), SiC, S
i and GaN are preferable because they can grow a high-quality Group 3-5 compound semiconductor crystal. SiC, Si, and GaN are more preferable in that a conductive substrate can be formed, and Si, S, and S are preferable in that a large-area substrate can be formed.
iC is more preferred. In the compound semiconductor light emitting device of the present invention, light emitted to the substrate side can be effectively reflected by the reflective layer and extracted to the semiconductor side. Therefore, the effect of the present invention is particularly large when the substrate has a large light absorption property. Examples of such a substrate include SiC, Si, and GaAs.

In the present invention, as a method for growing a group 3-5 compound semiconductor, a metal organic chemical vapor deposition (hereinafter referred to as MOVP) method is used.
Sometimes referred to as the E method. ), Molecular beam epitaxy (hereinafter sometimes referred to as MBE), and hydride vapor phase epitaxy (hereinafter sometimes referred to as VPE). As a possible method, the MOVPE method and the MBE method are preferable, and the MOVPE method that can easily form a uniform film over a large area is more preferable.

[0013] Group 3-5 compound of the present invention by MOVPE method
In the manufacture of semiconductors, the following raw materials can be used:
it can. Group 3 raw materials include trimethylgallium [(C
H_Three )_Three Ga may be referred to as TMG hereinafter. ],bird
Ethyl gallium [(C_Two H_Five )_Three Ga, hereinafter referred to as TEG
Sometimes. General formula R such as₁ R_Two R_Three Ga (where
R₁ , R_Two , R_Three Represents a lower alkyl group. )
Trialkyl gallium; trimethyl aluminum
[(CH_Three )_Three Al], triethyl aluminum [(C
_Two H_Five )_Three Al, hereinafter sometimes referred to as TEA. ]
Liisobutyl aluminum [(i-C_Four H₉ ) _Three A
l], etc.₁ R_Two R_Three Al (where R₁ , R
_Two , R_Three Represents a lower alkyl group. ) Represented by)
Alkyl aluminum; trimethylamine alane [(CH
_Three )_Three N: AlH_Three ]; Trimethylindium [(CH
_Three )_Three In, hereafter referred to as TMI. ], Trie
Chillindium [(C_Two H_Five )_Three In] or other general formula R₁ 
R_Two R_Three In (where R₁ , R_Two , R_Three Is lower alkyl
Represents a group. Trialkylindium etc.
I can do it. These may be used alone or as a mixture.

Next, as Group V raw materials, ammonia, hydrazine, methylhydrazine, 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, t-butylamine, ethylenediamine and the like can be mentioned. These may be used alone or as a mixture. Among these raw materials, ammonia and hydrazine do not contain a carbon atom in the molecule, so that the contamination of the semiconductor with carbon is small and suitable.

In the present invention, the p-type group III-V compound semiconductor
Examples of the type dopant include Mg, Cd, Zn, Hg, and Be. Of these, Mg, which is easy to produce a low-resistance p-type dopant, is preferable. As a raw material of the Mg dopant, biscyclopentadienyl magnesium, bismethylcyclopentadienyl magnesium, bisethylcyclopentadienyl magnesium, bis-n-propylcyclopentadienyl magnesium, bis-i-propylcyclopentadienyl The general formula (RC ₅
H ₄ ) ₂ Mg (where R is hydrogen or C 1 or more 4
The following lower alkyl groups are shown. The organic metal compound represented by the formula (1) is preferably used because it has an appropriate vapor pressure.

In the present invention, n of the group III-V compound semiconductor
Si, Ge, and O are used as the type dopant. Among them, Si is preferable, in which a low-resistance n-type is easily formed and a material having a high raw material purity is obtained. The raw materials of the Si dopant include silane (SiH ₄ ) and disilane (Si ₂ H
₆ ) is used.

In the present invention, the general formula Ga _1-a Al _a N
(0 ≦ a ≦ 1) and having different mixed crystal ratios from each other
The lamination composed of the repetition of the different types of layers is characterized in that the thickness of each layer is adjusted to １ ／ n times the emission wavelength λ. At this time, it is preferable that the value is exactly 1 / 4n times, but there may be some error as long as the effect of the present invention is not impaired. As the emission wavelength λ, any wavelength within the emission spectrum width can be used, but in order to obtain high emission efficiency, it is preferable to use the emission peak wavelength. By adjusting the thickness of the layer in this way, the laminated structure portion is
The light-emitting layer can function as a reflective layer for light emitted from the light-emitting layer. By locating the laminated structure portion between the light emitting layer and the substrate, light out of the light emitting layer, which goes to the substrate side, can be reflected and extracted to the semiconductor side, so that the light extraction efficiency can be increased. Becomes possible.

The reflectivity of a laminate composed of repetitions of two types of layers having different mixed crystal ratios represented by the general formula Ga _a Al _1-a N (0 ≦ a ≦ 1) is calculated based on the refractive index of the two types of layers. It depends on the difference and the number of layers in the stack. It is preferable that the difference between the refractive indices of the two types of layers be large because the reflectance can be increased. Ga _a Al
The refractive index of _1- aN decreases as the AlN mixed crystal ratio increases. Therefore, the combination for obtaining the largest difference in refractive index is A
This is a stacked structure of 1N and GaN.

Further, it is preferable that the number of layers in the lamination is large because the reflectance can be increased. AlN and Ga _1-a Al _a N
(0 <a <1), GaN and Ga _1-a Al _a N (0 <a <
1), Ga _1-a Al _a N (0 <a <1) and Ga _1-b Al
_{b N (0 <b <1} , b ≠ a) a combination of, although the difference in the refractive index of the two layers becomes small, it is possible to use so possible to increase the reflectance by increasing the number of layers . The preferred number of layers in the stack is two pairs of layers,
It is 2 pairs or more and 100 pairs or less. If it is smaller than two pairs, a sufficient reflectance cannot be obtained, which is not preferable. Also, 100
If it is larger than the pair, it takes too much time for growth, which is not practical and not preferable.

In the reflection layer according to the present invention, which is formed by laminating two types of layers having different mixed crystal ratios, all layers or a part of the laminated structure can be made conductive by doping impurities. When fabricating a laminated structure having n-type or p-type conductivity, Ga _1-a Al _a N (0 ≦ a ≦
A preferred range of the mixed crystal ratio a of AlN in 1) is 0.5 or less, and a more preferred range is 0.3 or less. When a is larger than 0.5, the band gap becomes large, and it becomes very difficult to control the conductivity.

Further, 3-5 group compound semiconductor light-emitting device of the present invention have the general formula _{In x Ga y Al z N (} x + y + z =
In a light-emitting element including a light-emitting layer and a substrate using a Group 3-5 compound semiconductor represented by 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, and 0 ≦ z ≦ 1, the light-emitting layer has a light reflection property. Sandwiched between two layers having a function, at least one of the two layers is represented by _a general formula Ga _1-a Al _a N (0 ≦ a ≦ 1), and two kinds having different mixed crystal ratios from each other And a layer included in a region sandwiched between two layers having the reflection function (hereinafter, this region may be referred to as a light confinement region) having a refractive index and a thickness of , And the emission wavelength are adjusted so that the following relationship is established.

(Equation 2) (Where d is the thickness of each layer, n is the refractive index at the emission wavelength of each layer, λ is the emission wavelength, m is an integer of 1 or more, and the subscript i
Represents the number of the light emitting layer, the subscript j represents the number of the layer other than the light emitting layer included in the region sandwiched between the structures having the upper and lower reflective functions, and Δ represents that the sum of the subscript numbers is taken. )

Hereinafter, the present invention will be further described based on structural examples of the light emitting device of the present invention shown in FIGS. 1 and 2. As shown in FIGS. 1 and 2, a so-called double hetero structure in which layers 4 and 6 having a larger band gap than the light emitting layer are in contact with both sides of the light emitting layer 3 is a structure effective for obtaining high luminous efficiency. In the present invention, when such a double hetero structure is provided, the fact that the light emitting layer is sandwiched between two layers having a light reflection function means that the double hetero structure has two light reflection functions. It means that it is sandwiched between layers.

In the examples shown in FIGS. 1 and 2, the light-emitting layer and the light-emitting layer
The case where there are two layers below the layer and the light emitting layer is shown. The light reflecting function on the lower side of the light emitting layer is provided by a laminated structure including two types of layers having different mixed crystal ratios. Less than,
The stack may be called a reflective film. On the other hand, the light reflecting function on the upper side of the light emitting layer is a metal film or a mixed crystal having a different mixed crystal ratio.
It can be provided by using a laminated reflective film having a repetition of various types of layers. In the example of FIG. 1, the light reflection function of the p-electrode metal 12 is used. A metal film can be suitably used because it is simple to produce, but a sufficient reflectance may not be obtained depending on the type of metal material and the thickness of the film. In this case, a high reflectance can be obtained by using a laminated structure including two types of layers having different mixed crystal ratios also above the light emitting layer as in the example of FIG. Hereinafter, the laminate may be referred to as a reflective film.

By providing a structure having a light reflecting function above and below the light emitting layer, light generated in the light emitting layer is reflected vertically and confined in the light confinement region. At this time, by adjusting the refractive index and the thickness of each layer included in the light confining region so as to satisfy the expression (1), a resonator is formed between the upper and lower reflective layers, and light generated in the light emitting layer is formed. Resonance occurs between the light reflected by the upper and lower reflective layers, and the half-width of the emission spectrum becomes extremely narrow, and the luminous efficiency can be increased. It is considered that the light emission can be obtained.

The value of m may be a positive integer, but is preferably 20 or less, more preferably 10 or less. If it is larger than 20, it takes a long time to grow and it is not practical because it is not practical.

FIG. 3 schematically shows an example of a preferable arrangement of the light emitting layer in the light confining region. It is preferable that the light emitting layer is located at a position where the electric field of light is maximized in order to obtain a large luminous efficiency. A deviation from this position is not preferable because the effect of the present invention is weakened. The preferred number of locations is only m depending on the thickness of the light confinement region. When m is 1, the preferred position of the light emitting layer is 1 at the center of the light confinement region.
If m is 2 or more, there are multiple preferred positions. When there are a plurality of preferable positions, a light emitting layer can be provided on all or a part of the positions. In order to position the light emitting layer at this preferred position, the thickness of the light emitting layer needs to be sufficiently smaller than the emission wavelength,
The preferred thickness ranges discussed above are still valid.

It is preferable that the thickness of the light confining region is exactly an integral multiple of 1/2 of the emission wavelength so that the expression (1) is satisfied. There may be errors. The range of the error in which the effect can be obtained is preferably ± 0.2 or less. If the error is larger than this, the effect of the present invention is weakened, which is not preferable.

The direction in which light is extracted is determined by the reflectivities of the upper and lower reflective films, and light can be extracted from the side having the lower reflectivity. The structure that extracts light from the semiconductor side (the opposite side of the substrate)
This is preferable because the LED assembly process is simplified. Therefore, it is preferable that the lower reflectivity is higher than the upper reflectivity.

[0029] As the light-emitting layer used in the light-emitting device of the present invention, the general formula _{In x Ga y Al z N (} x + y + z = 1,
3 represented by 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1)
Group V compound semiconductors having an InN mixed crystal ratio (value of x) of 10% or more are particularly useful for display applications because the band gap can be made visible. Also, InN
The compound semiconductor having a mixed crystal ratio of less than 10% can emit light in the ultraviolet region, and is therefore particularly useful for ultraviolet semiconductor laser applications. Those containing Al tend to take in impurities such as O, and when used as a light emitting layer, the luminous efficiency may be reduced. In such a case, as the light emitting layer, A
Formula In not include l _x Ga _y N (provided that, x + y =
1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1) can be used.

The preferred thickness range of the light emitting layer is 5
It is not less than {not less than 500} and more preferably not less than 5 ° and not more than 90 °. By reducing the thickness of the layer, charges can be confined in the light-emitting layer with high density, so that luminous efficiency can be improved. However, when the thickness of the layer is smaller than 5 °, the luminous efficiency becomes insufficient, which is not preferable. On the other hand, if the angle is larger than 500 °, it is not preferable because charges cannot be confined in the light emitting layer at high density and the efficiency is reduced.

The lattice constant of the compound semiconductor greatly changes depending on the InN mixed crystal ratio. The lattice constant of InN is GaN
Or about 12% or more larger than AlN.
For this reason, depending on the InN mixed crystal ratio of each layer of the compound semiconductor, a large difference may occur in the lattice constant between the layers. If there is a large lattice mismatch, a defect may occur in the crystal, which may cause a decrease in crystal quality. In order to suppress the occurrence of defects due to lattice mismatch, the thickness of the layer containing InN must be reduced according to the magnitude of strain due to lattice mismatch. The preferred thickness range depends on the magnitude of the strain, and the larger the lattice mismatch, the thinner the layer containing InN needs to be. In over Ga _a Al _1-a N
When the compound semiconductor having an N mixed crystal ratio of 10% or more is laminated, the preferable thickness of the layer containing InN is 5 to 500 °.
It is as follows. When the thickness of the layer containing InN is smaller than 5 °, the luminous efficiency becomes insufficient. On the other hand, if it is larger than 500 °, a defect occurs and the luminous efficiency is still insufficient. A more preferable thickness range is 5 ° or more and 90 ° or less.

If the thickness of the light emitting layer is made extremely thin as in the above range and a structure is obtained in which charges are confined at a high density, electrons and holes pass through the light emitting layer without recombination in the light emitting layer. A so-called carrier overflow phenomenon may occur, and the luminous efficiency may rather decrease. To prevent this, it is effective to increase the difference in band gap between the light emitting layer and the layers on both sides thereof. A preferable band gap difference is 0.1 eV or more. More preferably, it is 0.3 eV or more. In order to make such a large band gap difference, the composition of the layers on both sides in contact with the light emitting layer is preferably Ga _1-c Al _c N (0 ≦ c ≦ 1).

The light emitting layer containing InN has a thermal stability of I
It may be inferior to a layer containing no nN. For this reason,
Crystallinity of the light emitting layer may be reduced depending on the growth conditions of the layer grown after the light emitting layer. To prevent this, a layer grown next to the light-emitting layer is made of Ga _1-d Al _d not containing InN.
By using N (0 ≦ d ≦ 1), a function of protecting the light emitting layer can be provided. This protective layer can also have the function of increasing the difference in band gap between the protective layer and the light emitting layer as described above.

By doping the light emitting layer with an impurity, light can be emitted at a wavelength different from the band gap of the light emitting layer. Since this is light emission from an impurity, it is called impurity light emission. In the case of impurity light emission, the emission wavelength is determined by the composition of the Group 3 element and the impurity element in the light emitting layer. in this case,
The InN mixed crystal ratio of the light emitting layer is preferably 5% or more. When the InN mixed crystal ratio is less than 5%, emitted light is almost ultraviolet light, and sufficient brightness cannot be felt. In
The emission wavelength becomes longer as the N mixed crystal ratio is increased, and the emission wavelength can be adjusted from purple to blue, green, yellow, and red.

As an impurity suitable for impurity emission, a Group 2 element is preferable. Among the group II elements, Mg, Zn, C
Doping with d is preferable because of high luminous efficiency.
Particularly, Zn is preferable. The concentration of these elements is 10 ¹⁸
It is preferably from 10 to 10 ²² cm ^-3 . The light emitting layer may be simultaneously doped with Si or Ge together with these Group 2 elements.
Si, the preferred concentration range of Ge is 10 ¹⁸ ~10 ²² cm ^-3
It is.

In the case of impurity light emission, the light emission spectrum generally becomes broad, and the light emission spectrum shifts with an increase in the amount of injected charge, or a peak of band edge light emission appears. It is difficult to increase luminous efficiency. Therefore, when high color purity is required, when it is necessary to concentrate light emission power in a narrow wavelength range, or when an element with high light emission efficiency is required, it is more advantageous to use inter-band light emission. . In order to realize a light-emitting element using inter-band light emission,
The amount of impurities contained in the light emitting layer must be kept low. Specifically, the concentration of each element of Si, Ge, Mg, Cd and Zn is preferably 10 ¹⁹ cm ⁻³ or less.
More preferably, it is 10 ¹⁸ cm ^-3 or less.

In the case of inter-band light emission, the emission color is 3
Determined by the composition of the group elements. When emitting light in the visible part, In
The N mixed crystal ratio is preferably 10% or more. The emission wavelength increases as the InN mixed crystal ratio increases, and the emission wavelength changes from purple to blue,
Adjustable to green, yellow and red. When used for ultraviolet semiconductor laser applications, the InN mixed crystal ratio is preferably 10% or less.

[0038]

The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples. Example 1 A group III-V compound semiconductor shown in FIG. 2 is grown by vapor phase growth using MOVPE, and an LED having an emission wavelength of 4500 ° is manufactured. As the substrate 11, sapphire (0001)
The mirror-polished surface is organically washed and used. The growth is based on a two-stage growth method using a low-temperature growth buffer layer. TMG
And ammonia as a raw material and hydrogen as a carrier gas, the GaN buffer layer
After forming the film at 0 °, an n-type GaN layer 9 is grown at 1100 ° C. with a thickness of 3 μm using TMG, ammonia and silane (SiH ₄ ) as a dopant. Next, TMG, TMA,
Ammonia and silane as dopant (SiH ₄ )
Is used to fabricate a stacked layer 8 (reflection film) having n-type conductivity. The two types of layers constituting the stack are GaN and Ga
_1-a Al _a N (a = 0.2). Since the refractive index of each layer is 2.473 and 2.347 at 4500 °, the thickness of each layer is adjusted to 455 ° and 479 °. A reflection film composed of a stack of 30 pairs is formed by first growing the two types of layers from a GaN layer.

Next, the light confinement region 2 including one light emitting layer
Grow. G having n-type conductivity using TMG, ammonia and silane (SiH ₄ ) as a dopant
After the aN layer 7 was 1100Å grown at 785 ° C., the carrier gas was nitrogen, TEG, TEA, ammonia and dopant as silane (SiH ₄₎ with n-type conductivity having a Ga _1-c Al c N ( c = 0.2) Layer 6 is 2
Then, an In _0.3 Ga _0.7 N layer 3 as a light emitting layer is grown by 50 ° using TEG, TMI, and ammonia, and Ga is further grown by using TEG, TEA, and ammonia.
_{A 1-d} Al _d N (d = 0.2) layer 4 is grown at 250 ° and finally at 1100 ° C., TMG, ammonia and biscyclopentadienyl magnesium ((C ₅ H ₅ ) ₂ Mg, Hereafter, the Mg-doped p-type GaN layer 5 is grown at 1100 ° using Cp ₂ Mg. The emission peak wavelength determined by the composition of the In _0.3 Ga _0.7 N layer, which is the light emitting layer 5, is ₄₅₀₀ °, and the thickness of the light confinement region is adjusted to three times the half wavelength.

Next, TMG, TMA, ammonia and p
Biscyclopentadienyl mag
Nesium ((C_Five H_Five )_Two Mg, Cp_Two Notated as Mg
Sometimes. ) Using Mg-doped GaN and G
a_1-a Al_a Reflective film made of N (a = 0.2) laminate 1
Grow. The thickness of each layer is 455 ° for the GaN layer and Ga
_1-a Al_a The N (a = 0.2) layer is adjusted to 479 °.
The two types of layers constitute one pair and a 20-layer laminated reflective film
And Ga_1-a Al_a Growing from N (a = 0.2) layer
I do. After the growth is completed, the substrate is taken out and placed in nitrogen at 800 ° C.
Heat-treated and doped with Mg_1-a Al_a N
(A = 0.2) and a reflection film composed of GaN laminate 1;
The GaN layer doped with Mg in the light confinement region
An anti-p-type GaN layer 5 is used.

Using a group III-V compound semiconductor grown by the above method, a Ni-Au alloy is used as a p-electrode according to a conventional method.
An LED is manufactured using Al as the n-electrode. 20mA
When a forward current was passed, clear blue light emission was mainly observed from the p-electrode side, and light emission from the substrate side was very weak.

Example 2 The structure 3 shown in FIG.
-Group 5 compound semiconductor is grown, and L at an emission wavelength of 5200 °
Fabricate ED. The composition of the light emitting layer 3 is In _0.53 Ga _0.47 N
In accordance with this, GaN and Ga under the light emitting layer 3 are
The thickness of each layer in the reflection film composed of the laminated layer 5 of _1-a Al _a N (a = 0.2) is 536 ° and 560 °, respectively, and the thickness of the GaN layers 5 and 7 in the light confinement region is 1340 °.
GaN and Ga _1-a Al _a N (a
= 0.2), except that a reflective film composed of a stack of (= 0.2) is not grown. However, the light emitting layer 3 and the upper and lower Ga _1-d Al _d N layers 4 (d = 0.2) in contact with the light emitting layer 3 and Ga
The growth temperature of the _1-c Al _c N layer 6 (c = 0.2) is 750 ° C.
And An LED is manufactured using a Ni-Au alloy as a p-electrode and Al as an n-electrode according to a conventional method. The p-electrode is made thicker than usual to obtain a high reflectance, and is deposited at 5000 °. When a forward current of 20 mA was passed, clear green light emission was observed mainly from the p-electrode side, and light emission from the substrate side was very weak.

Embodiment 3 The structure 3 shown in FIG.
A -5 group compound semiconductor is grown to produce a violet emission laser having an emission wavelength of 4060 °. (0001) Si of 6H-SiC having n-type conductivity instead of the sapphire substrate
Using a surface substrate, an SiO ₂ film is deposited on the entire surface of the SiC substrate at 3000 ° by a vacuum evaporation method. Next, after forming a photoresist pattern using a normal photolithography method, a hydrofluoric acid treatment is performed to produce a SiO ₂ mask pattern. On a substrate with a SiO ₂ mask pattern,
The composition of the light emitting layer 3 is In _0.15 Ga _0.85 N, and accordingly, GaN and Ga _1-a Al _a N (a
= 0.2) and the lower Ga layer
The thickness of the GaN layer and the thickness of the Ga _1-a Al _a N layer in the reflective film composed of the stacked layer 8 of N and Ga _1-a Al _a N (a = 0.2) are set to 400 ° and 426 °, respectively. The thickness of the GaN layer 5 and the GaN layer 7 in the confinement region is set to 134
A Group III-V compound semiconductor is grown almost in the same manner as in Example 1 except that the angle is set to 0 °. At this time, SiO ₂
The group III-V compound semiconductor grows selectively only in the part without the mask. However, the light emitting layer 3 and the upper and lower Ga _1-d Al _d N layers 4 (d = 0.2) in contact with the light emitting layer 3 and the Ga
The growth temperature of the _1-c Al _c N layer 6 (c = 0.2) is 815 ° C.
And

Next, etching is performed to the n-type layer by dry etching using Cl ₂ gas so that the p-type layer portion remains in a stripe shape. Next, a stripe-shaped Ni-Au alloy is formed as the p-electrode 12, a Ni electrode is formed on the entire back surface of the substrate as the n-electrode 13, and Al is formed to form a current path between the n-type substrate and the n-type layer. And N
The electrode 14 is formed using i. Next, the SiC substrate is
Divide into laser chips by dicing and cleavage. A reflection film is formed using Al on the side surfaces obtained by cleavage to form a resonator structure. Thus, a semiconductor laser is manufactured. When a forward pulse current was applied, a clear purple stimulated emission was observed.

[0045]

According to the present invention, by providing a reflective film having a specific structure between the light emitting layer and the substrate,
Since the light emitted from the light emitting layer to the substrate side is effectively reflected to the semiconductor side, the light extraction efficiency from the semiconductor side (the side opposite to the substrate) can be increased, and the light emission efficiency can be improved. Further, according to the present invention, a structure having a light reflection function is provided above and below the light emitting layer, and the thickness of the light confinement region is adjusted to an integral multiple of half the emission wavelength, thereby improving the light emission efficiency. Since the emission spectrum can be narrowed, it is extremely useful and has great industrial value.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of the structure of a compound semiconductor light emitting device of the present invention.

FIG. 2 is a sectional view showing another example of the structure of the compound semiconductor light emitting device of the present invention.

FIG. 3 is a schematic view showing an example of a preferable arrangement of a light emitting layer in a light confinement region in the compound semiconductor light emitting device of the present invention.

FIG. 4 is a cross-sectional view illustrating a structure of a compound semiconductor light emitting device according to a third embodiment.

[Explanation of symbols]

1 ... Lamination of p-type GaN and Ga _1-a Al _a N 1-1 ... p-type Ga _1-a Al _a N layer 1-2 ... p-type GaN layer 2 ... light confinement Region 3 Light-emitting layer 4 Ga _1-d Al _d N layer 5 p-type GaN layer 6 Ga _1-c Al _c N layer 7 n-type GaN layer 8 ... n-type GaN and Ga _1-a Al a stack of n 8-1 · · n-type GaN layer 8-2 · · n-type Ga _1-a Al a n layer 9 ... n-type GaN layer 10 buffer layer 11 substrate 12 p-electrode 13 n-electrode 14 electrode for forming a current path

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomoyuki Takada 6 Kitahara, Tsukuba, Ibaraki Prefecture Sumitomo Chemical Co., Ltd. (72) Inventor Katsumi Inui 6 Kitahara, Tsukuba City, Ibaraki Prefecture Sumitomo Chemical Co., Ltd. F-term (reference) 5F041 CA04 CA34 CA40 CA58 CB15 5F073 AA89 CA02 CA07 CB14

Claims (5)

[Claims] 1. A general formula _{In x Ga y Al z N (} x + y + z
= 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) When manufacturing a light-emitting element having a light-emitting layer and a substrate using a Group 3-5 compound semiconductor represented by Is sandwiched between two layers having a light reflecting function, and at least one of the two layers
One of the layers is represented by the general formula _{Ga 1-a Al a N (} 0 ≦ a ≦ 1), and a laminated comprising repeating the two different types of layers from each other mixed crystal ratio, and two layers having the reflection function Between the refractive index and the thickness of the layer included in the region sandwiched by (Where d is the thickness of each layer, n is the refractive index at the emission wavelength of each layer, λ is the emission wavelength, m is an integer of 1 or more, and the subscript i
Represents the number of the light emitting layer, the subscript j represents the number of the layer other than the light emitting layer included in the region sandwiched between the structures having the upper and lower reflective functions, and Δ represents that the sum of the subscript numbers is taken. ) Is established, and the position of the light emitting layer is adjusted so that the electric field of light becomes maximum.
A method for manufacturing a Group V compound semiconductor light emitting device. 2. When the position of the light emitting layer is represented by the distance from one end of a region sandwiched between the two layers having the reflecting function, the position s of the light emitting layer is expressed by the following equation (2): s = (2k−1) 3. The group 3-5 compound semiconductor light-emitting device according to claim 1, wherein the position is adjusted to at least one position where λ / 4 (2) (where k represents an integer of 1 to m). Manufacturing method. 3. A laminate comprising two types of layers represented by the general formula Ga _1-a Al _a N (0 ≦ a ≦ 1) and having different mixed crystal ratios. 3. The method for manufacturing a Group 3-5 compound semiconductor light emitting device according to claim 1, wherein some of the layers impart n-type or p-type conductivity. 4. The light-emitting layer has a thickness of 5 ° or more and 90 ° or less,
4. The method for manufacturing a Group 3-5 compound semiconductor light emitting device according to claim 1, wherein the light emitting layer is sandwiched on both sides thereof in contact with a layer having a larger band gap than the light emitting layer. 5. The method according to claim 1, wherein the light emitting layer contains Si, Ge, Mg, and Z.
5. The method according to claim 1, wherein the concentration of each of n and Cd is adjusted to 10 ¹⁹ cm ^-3 or less.