JP3509260B2 - Group 3-5 compound semiconductor and light emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Group 3-5 compound semiconductor and a light emitting device using the same.

[0002]

BACKGROUND OF THE INVENTION In general formula In _x Ga _y Al _z N (where 0
<X ≦ 1, 0 ≦ y <1, 0 ≦ z <1, x + y + z = 1)
Since the group III-V compound semiconductor represented by the formula (1) has a band gap that can be controlled by the composition of the group III element, it can be used for a light-emitting element that emits light in a visible light region to an ultraviolet region. Further, since the Group 3-5 compound semiconductor has a direct transition band structure, it is expected that a light emitting element with high luminous efficiency can be obtained by using this. In addition, the lattice constant of the group 3-5 compound semiconductor can be controlled by its composition. That is, two or more kinds of semiconductors having the same lattice constant and different band gaps can be manufactured. The junction of semiconductors having different band gaps is called a so-called hetero junction, and is considered to be very effective in realizing a high-luminance semiconductor light emitting device.

Therefore, as a substrate for growing the group III-V compound semiconductor crystal, at present, there is no suitable material whose lattice constant is matched, so that the same hexagonal type III-V compound semiconductor as the hexagonal type III-V compound semiconductor is used. The use of sapphire as a substrate has been studied. However, a high-quality Group III-V compound semiconductor crystal has not yet been obtained. Particularly, in a system containing In at a high concentration to the extent that it can be used for display, a high-quality crystal that can be practically used can be obtained. Not.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an In
It is an object of the present invention to provide a high-quality group III-V compound semiconductor containing, and a light-emitting element having high luminous efficiency using the same.

[0005]

Means for Solving the Problems The present inventors have proposed such a method.
After careful examination of the situation, 3-5
High quality and large area by growing group III compound semiconductor
The present invention has been found that a group 3-5 compound semiconductor of
Reached. That is, the present invention is the following invention. [1] Between a substrate having a light emitting layer and a charge injection layer and a substrate
Has a buffer layer, and the light emitting layer has the general formula In._xGa_yA
l_zN (where 0 <x ≦ 1, 0 ≦ y <1, 0 ≦ z <1,
x + y + z = 1) group 3-5 compound semiconductor
Thus, the charge injection layer has the general formula In_{x '}Ga_{y '}Al_{z '}N (expression
Where 0 <x ′ ≦ 1, 0 ≦ y ′ <1, 0 ≦ z ′ <1, x ′
+ Y '+ z' = 1) and is larger than the light emitting layer.
A group 3-5 compound semiconductor having a gap,
Buffer layer has the general formula In_uGa_vAl _wN (where 0 <
u ≦ 1, 0 ≦ v <1, 0 ≦ w <1, u + v + w = 1)
Represented by at least two layers of different composition,
Includes a laminated structure where w> 0 in at least one layer
A Group 3-5 compound semiconductor characterized by the above-mentioned.

[2] The group 3-5 compound semiconductor according to [1], wherein the buffer layer comprises at least four layers. [3] the buffer _{layer, In u Ga v Al w N} ( where, 0
≦ u <1, 0 ≦ v <1, 0 ≦ w <1, u + v + w = 1)
Layer and In _{u ′} Gav _′ Al _w′N (where 0 ≦ u ′ <1, 0 <
v ′ ≦ 1, 0 ≦ w ′ <1, u ′ + v ′ + w ′ = 1) layer is a laminated structure in which layers are alternately repeated at least twice. Compound semiconductor.

[4] Ga formed on a sapphire substrate
3. The method according to [1], wherein the layer is formed on the N layer.
Group 5 compound semiconductor. [5] A light emitting device using the Group 3-5 compound semiconductor according to any one of [1] to [4].

Next, the present invention will be described in detail. 3 of the present invention
The Group-V compound semiconductor has a buffer layer between a substrate having a light emitting layer and a charge injection layer and a substrate. The light emitting layer is
In the general formula In _x Ga _y Al _z N (wherein, 0 <x ≦ 1,0 ≦
y <1, 0 ≦ z <1, x + y + z = 1) 3-
It is a group 5 compound semiconductor. The charge injection layer has the general formula In _{x ′}
Ga _y 'Al _z' N (where 0 <x '≦ 1,0 ≦ y '<1,0
≦ z ′ <1, x ′ + y ′ + z ′ = 1), which is in contact with the light emitting layer and has a larger band gap than the light emitting layer.
It is a group 5 compound semiconductor. Since the charge injection layer has a band gap larger than that of the light emitting layer, the charge injection layer has a function of efficiently injecting charges generated in the semiconductor of the present invention due to light irradiation or charges supplied from an external power supply into the light emitting layer to confine the light emitting layer. Buffer layer has the general formula In _u Ga _v Al _w N (where, 0 <u ≦ 1,0 ≦ v <1,0 ≦ w <1, u + v + w
= 1) and includes a laminated structure composed of at least two layers having different compositions.

In particular, the general formula of the light emitting layer is In _x Ga _y Al _z
In the group III-V compound semiconductor represented by N, when the composition of In is 10 to 80 mol% (0.1 ≦ x ≦ 0.8), the emission wavelength is violet and the visible region longer than that. Therefore, it is preferable for light emitting element use. Specifically, the emission wavelength can be purple, blue, green, yellow, or orange. In particular, it is important for blue and green light emitting elements.

The difference in lattice constant between the light emitting layer and the charge injection layer in the direction parallel to the substrate surface is preferably 0.3% or less. If the difference between the lattice constants exceeds 0.3%, defects tend to occur at the junction interface, which is not preferable. The buffer layer according to the present invention includes a laminated structure composed of at least two layers having different compositions.
It is good to laminate more than 10 layers, More preferably, to laminate more than 10 layers. Further, if the number of layers is too large, the total time required for switching the raw materials becomes longer, and the productivity becomes worse. Therefore, the number of layers included in the layered structure is one.
000 or less is preferable. The total thickness of the laminate is
The range is preferably from 100 ° to 5 μm. If it is less than 100 °, the effect of lamination is not sufficient, and if it exceeds 5 μm, the time required for growth becomes long and productivity is deteriorated, which is not preferable. In a group III-V compound semiconductor containing Ga, Ga is replaced with Al
Although there is no significant change in the lattice constant even when the Ga is replaced with In, a large lattice constant difference occurs when Ga or Al is replaced with In. Therefore, it is preferable that the composition used for the stacked structure does not change the proportion of In so much, but changes the composition of Ga and Al. In particular,
Buffer layer, In _u Ga _v N layer and an In _u Al _v N layer (where, u + v = 1,0 <u <1,0 <v <1) and has a laminated structure repeated at least 2 times alternately Some 3-5
Group semiconductors are preferred.

The semiconductor band gap between the charge injection layer and the light emitting layer is preferably at least 0.1 eV (hereinafter sometimes referred to as "eV"). Further, it is preferably 0.3 eV or more. If it is less than 0.1 eV, electrons or holes are not easily confined at the interface between the charge injection layer and the light emitting layer, and the recombination efficiency of the charges in the light emitting layer is undesirably reduced. In addition, by using a so-called double hetero junction structure in which not only one surface of the light emitting layer but also both surfaces are joined by a charge injection layer, charges can be more efficiently confined, and charge recombination can be performed. Efficiency can be increased. Also in this case, the difference between the width of the forbidden band of the charge injection layer and the light emitting layer is 0.1 eV or more, and more preferably 0.3 eV.
It is preferably at least V.

The group III-V compound semiconductor crystal of the present invention can be obtained by growing it on a substrate. For the substrate to be used, SiC, Si, sapphire, spinel, ZnO or the like can be used. In particular, the group 3-5 compound semiconductor was grown on a GaN layer grown on sapphire.
Group 5 compound semiconductor is preferred, and AlN on sapphire
A Group 3-5 compound semiconductor in which the Group 3-5 compound semiconductor is grown on a GaN layer grown using a thin film such as a buffer layer as a buffer layer is more preferable. The light-emitting element using a Group III-V compound semiconductor of the present invention uses a Group III-V compound semiconductor capable of confining electrons and holes at a high density, so that luminous efficiency is improved.

The method for producing a Group 3-5 compound semiconductor of the present invention includes a molecular beam epitaxy (hereinafter, referred to as “MBE”) method, a metal organic chemical vapor deposition (hereinafter, referred to as “MOVPE”) method, and the like. Is mentioned. When using the MBE method,
Gas source molecular beam epitaxy (hereinafter, referred to as “GSMBE”), which is a method of supplying nitrogen, ammonia, and other nitrogen compounds in a gaseous state as a nitrogen source.
The method is commonly used. In this case, the nitrogen source may be chemically inert and nitrogen atoms may not be easily incorporated into the crystal. In that case, the nitrogen raw material is excited by a microwave or the like and supplied in an activated state, whereby the efficiency of nitrogen uptake can be increased.

[0014] Group 3-5 of the present invention using the MOVPE method
When manufacturing compound semiconductors, use the following raw materials:
Can be. In other words, tri-group materials include birds
Methylgallium [Ga (CH_Three)_Three, And "TMG"
May be noted. ], Triethylgallium [Ga (C_Two
H_Five)_ThreeGeneral formula R such as₁R_TwoR_ThreeGa (where R
₁, R_Two, R_ThreeIs an alkyl group)
Gallium; trimethylaluminum [Al (C
H_Three)_Three, Hereinafter referred to as “TMA”. 〕,bird
Ethyl aluminum [Al (C_TwoH_Five)_Three], Triiso
Butyl aluminum [Al (i-C_FourH₉)_ThreeOne of
General formula R₁R_TwoR_ThreeAl (where R₁, R_Two, R _ThreeIs
Trialkylaluminum represented by the formula:
Methylamine alane [AlH_ThreeN (CH_Three)_Three〕;bird
Methyl indium [In (CH_Three)_Three, Hereafter "TMI"
It is written. ] Triethylindium [In (C
_TwoH_Five)_ThreeGeneral formula R such as₁R_TwoR_ThreeIn (where R
₁, R_Two, R_ThreeIs an alkyl group)
Indium and the like can be mentioned. These can be used alone or mixed
Used.

Next, as Group 5 elements, ammonia, hydrazine, methylhydrazine, 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, t-butylamine,
And ethylenediamine. These are used alone or as a mixture. As the n-type dopant, S
Group 4 elements such as i and Ge, and group 6 elements such as S and Se can be used. As the p-type dopant, Be, M
g, Zn, Cd, Hg, or the like can be used.

In the case of the MOVPE method, Si
Run (SiH_Four), Disilane (Si _TwoH₆Gehara, etc.)
Guerlain (GeH_Four), Etc.
Hydrogen (H_TwoS), dimethyl sulfur [(CH_Three)_TwoS],
Diethyl sulfur [(C_TwoH_Five) _TwoS] and other general formulas R₁R_Two
S (R₁R_TwoIs an alkyl group represented by an alkyl group)
Sulfur and Se raw materials include hydrogen selenide (H_TwoS
e), dimethyl selenium [(CH_Three)_TwoSe], diethyl
Selenium [(C_TwoH_Five)_TwoSe], etc.₁R_TwoS
e (R₁R_TwoIs an alkyl group represented by an alkyl group)
Lucerene and the like.

As a Zn raw material, dimethyl zinc ((CH
_Three)_TwoZn), diethyl zinc ((C _TwoH_Five)_TwoZn)
Of the general formula R₁R_TwoZn (R₁, R_TwoIs an alkyl group)
Alkyl zinc and the like. Mg raw material
The biscyclopentadienyl magnesium ((C_Five
H_Five)_TwoMg), bismethylcyclopentadienyl mag
Nesium ((CH_ThreeC_FiveH_Four)_TwoMg, hereinafter MCp2M
It may be written as g. ), Bisisopropylcyclopen
Tadienyl magnesium ((i-C_ThreeH₇C_FiveH_Four)_Two
Mg).

As a raw material for Cd, dimethyl cadmium is used.
((CH_Three)_TwoGeneral formula R such as Cd) ₁R_TwoCd (R₁,
R_TwoIs an alkyl cadmium represented by an alkyl group)
And so on. As a raw material for Be, diethyl beryl
Um ((C_TwoH_Five)_TwoBe), bismethylcyclopenta
Dienyl beryllium ((CH_ThreeC_FiveH_Four)_TwoBe) etc.
Is mentioned. Dimethylmercury as a raw material for Hg
((CH_Three)_TwoHg), diethyl mercury ((C_TwoH_Five)_Two
General formula R such as Hg)₁R_TwoHg (R₁, R_TwoIs alkyl
Alkyl mercury represented by the formula:

The volatile raw material can be supplied by an appropriate supply means depending on the state of the state. That is, in the case of liquid, sublimable solid substances, sufficiently purified hydrogen, nitrogen, etc. are passed through these raw materials as a carrier gas,
A carrier gas containing the vapor of these raw materials can be led to the reactor. When the raw material is a gas, the raw material can be held in a compressed state in a cylinder and guided to the reaction furnace by the pressure from the cylinder. Also, to adjust the concentration,
A substance diluted with a gas such as hydrogen or nitrogen which has been sufficiently purified can also be used. The doped compound semiconductor is subjected to electron beam irradiation or thermal annealing as required,
Lower resistance can be obtained. The light-emitting device of the present invention
It uses the Group 3-5 compound semiconductor of the present invention, and can be manufactured by a known method. A specific example is shown in FIG. Here, on a sapphire substrate 22, sequentially AlN buffer layer 24, GaN layer 25, In _{0. 1} Ga
_0.9 N and In _0.1 Ga _0.8 Al _0.1 buffer layer 26 having a laminated structure of N, InGaAlN charge injection layer 27, I
An nGaN light emitting layer 28 and an InGaAlN charge injection layer 29 are grown. Here, from the GaN layer 25 to the charge injection layer 27
Until then, the n-type charge injection layer 29 is doped with a p-type impurity. Next, the compound semiconductor thus manufactured is partially etched in accordance with a conventional method, and further, InGaAlN
An n-electrode 30 is formed on the charge injection layer 27, and
A p-electrode 31 is formed on the 1N charge injection layer 29. FIG.
Although the electrode 30 is provided on the charge injection layer 27, the layer on which the electrode 30 is provided may be any layer provided on the sapphire substrate 22 side with respect to the light emitting layer 28 excluding the AlN layer 24.

[0020]

The present invention will be described in more detail with reference to the following examples. The embodiment is merely an example, and it goes without saying that various changes or improvements can be made without departing from the spirit of the present invention. Example 1 FIG. 1 schematically shows the MOVPE apparatus used here. The raw materials used were ammonia, TMG, TMA, TMI,
A silane gas diluted to 1 ppm with hydrogen was used for doping with Si, and MCp2Mg was used for doping with Mg.
First, a single-crystal sapphire substrate 22 having a C-plane as a main surface cleaned by organic cleaning was mounted on a susceptor 21 placed in a reaction chamber 19 of a MOVPE apparatus. Next, the susceptor was moved to 11 degrees by high-frequency heating while flowing hydrogen into the reaction chamber at normal pressure.
The substrate was heated to 00 ° C., and in this state, the sapphire substrate was held for 10 minutes, and the sapphire substrate was subjected to gas phase cleaning. Next, the temperature was lowered to 600 ° C., and ammonia and TM
G was supplied to form a buffer layer of gallium nitride having a thickness of about 500 °. Next, only the supply of TMG is stopped,
After the temperature of the sapphire substrate was raised to 1100 ° C. and the temperature was stabilized, supply of TMG was started, and a GaN film having a thickness of 3 μm was grown. The sapphire substrate thus obtained and GaN are combined to form a substrate in the present invention.

Next, only the supply of TMG is stopped and the temperature is lowered to 800 ° C., and then the carrier gas is changed from hydrogen to nitrogen.
The supply of TMG and TMI was started, and In _0.1 Ga _0.9 N
Was grown 100 °. Then, TMG, TMI, T
MA was supplied to form a layer of In _0.1 Ga _0.8 Al _0.1 N into one layer.
00 grew. This operation is alternately repeated 20 times,
20 In _0.1 Ga _0.9 N layers, In _0.1 Ga _0.8 Al
_A laminated structure consisting of 20 _0.1 N layers was grown. next,
In _0.1 Ga having an Si concentration of 1 × 10 ¹⁹ / cm ³ using TMG, TMA, TMI, silane gas, and MCp2Mg.
The charge injection layer of _0.8 Al _0.1 N is 1800 ° and the light emitting layer of In _0.1 Ga _0.9 N having a Si concentration of 1 × 10 ¹⁹ / cm ³ is 5
A GaN layer having a thickness of 00 ° and a Mg concentration of 1 × 10 ²⁰ / cm ³ was grown at 1800 °. After growth, 800 ° C in nitrogen
To reduce the resistance of the Mg-doped GaN layer. Using the group III-V compound semiconductor substrate thus obtained, a light emitting device having the structure shown in FIG. 2 was manufactured by a normal semiconductor process. When a p-electrode was connected to the positive side of the power supply and an n-electrode was connected to the negative side and 5 V was applied, a current of 10 mA flowed. At this time, blue-violet light emission was observed. In this state, the luminance of the light-emitting portion was measured with a luminance meter, and as a result, it was 17 mcd.

COMPARATIVE EXAMPLE 1 After growing a GaN layer, In _0.1 Ga _0.9 N and In _0.1 Ga
_A light-emitting device was manufactured in the same manner as in Example 1 except that the laminated structure made of _0.8 Al _0.1 N was not grown. When a current of 10 mA was passed in the same manner as in Example 1 and the state of the element was observed from the substrate side, blue-violet light emission was also seen from the vicinity of the p-electrode. As a result of measuring the luminance with a luminance meter, the luminance was 6 mcd.

Example 2 In the same manner as in Example 1, In was used as the buffer layer of the present invention.
30% of _0.17 Ga _0.83 N and In _0.17 Ga _0.75 Al _0.08 N
Are alternately grown 20 times, ie, 30 °, for a total of 40 layers. Further, the first charge injection layer In _0.17 Ga _0.83 N is 30 °, the light emitting layer is In _0.25 Ga _0.75 N 50 °, and the second charge injection layer is GaN. Has grown 200Å. The difference in band gap between the first charge injection layer and the light emitting layer is about 0.16 eV,
The difference in band gap between the charge injection layer and the light emitting layer is about 0.5
eV.

A photoluminescence spectrum (hereinafter, sometimes referred to as “PL”) of the thus obtained sample was measured at a liquid nitrogen temperature using a He—Cd laser (wavelength: 325 nm, output: 10 mW) as an excitation light source.
It shows clear blue light emission derived from the light emitting layer, and the center wavelength is 4
315 °, peak intensity (output of detector at peak wavelength)
Was 4.15 mV.

COMPARATIVE EXAMPLE 2 In _0.25 Ga _0.75 N was used as a light emitting layer directly on GaN.
The growth was carried out in the same manner as in Example 2 except that the growth was 0 °. In the case of this embodiment, the first charge injection layer is GaN
It is. Evaluation by PL was performed in the same manner as in Example 1. As a result, clear blue light was emitted, but the peak intensity was only 1.6 mV. Comparing this result with Example 2, it can be seen that the crystallinity of the light emitting layer in the Group 3-5 compound semiconductor of the present invention is greatly improved as compared with Comparative Example 2.

Example 3 A semiconductor of the present invention was produced in the same manner as in Example 2 except that a light emitting layer was grown directly on the buffer layer of the present invention. In addition, the buffer layer was repeated 10 times (20 layers in total) and 4 times.
A similar sample was repeated 0 times (total of 80 layers).
In the case of the present embodiment, the last layer of the buffer layer functions as the first charge injection layer. The difference in band gap between the first charge injection layer and the light emitting layer is about 0.3 eV. These samples and the sample of Comparative Example 2 were evaluated by PL at room temperature in the same manner as in Example 2. FIG. 3 shows the relationship between the number of buffer layers and the peak intensity. The peak intensity of the comparative example is also shown at the position of the layer number 0 in this figure. From this figure, it can be seen that the crystallinity of the semiconductor according to the present invention is improved as compared with Comparative Example 2.

[0027]

According to the present invention, the group 3-5 compound semiconductor is In
Is a high-quality, large-area Group 3-5 compound semiconductor containing
A light-emitting element using this has high luminous efficiency. In particular,
The light-emitting device of the present invention provides a light-emitting device having a group III-V
When the composition of n is 10 to 80 mol%, the emission wavelength is violet and a visible region having a longer wavelength, that is, blue, green,
Can be yellow, orange, etc. In particular, the light emitting device of the present invention is industrially important for blue and green light.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus for manufacturing a Group 3-5 compound semiconductor used in a semiconductor light emitting device of the present invention.

FIG. 2 is a schematic view illustrating an example of a structure of a light emitting element of the present invention.

FIG. 3 is a diagram showing a correlation between the number of buffer layers and a PL peak intensity.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Mass flow controller 2 ... Constant temperature layer 3 ... TMG bubbler 4 ... Mass flow controller 5 ... Constant temperature layer 6 ... TMA bubbler 7 ... Mass flow controller 8 ... Constant temperature layer 9 ... TMI bubbler 10 Mass flow controller 11 Constant temperature layer 12 MCp2 Mg bubbler 13 Silane cylinder 14 Pressure regulating valve 15 Mass flow controller 16 Ammonia cylinder 17 Pressure valve 18 Mass flow controller 19 Reactor 20 High frequency coil 21 Susceptor 22 Sapphire substrate 23 Exhaust hole 24 AlN buffer layer 25 GaN layer 26 ... In _0.1 Ga _0.9 N and In _0.1 Ga _0.8 Al
Buffer layer 27 having a laminated structure of _0.1 N InGaAlN charge injection layer 28 InGaN light emitting layer 29 InGaAlN charge injection layer 30 n electrode 31 p electrode

Continuation of the front page (56) References JP-A-6-164055 (JP, A) JP-A-5-335622 (JP, A) JP-A-5-275745 (JP, A) JP-A-5-206513 (JP) JP-A-6-53549 (JP, A) JP-A-6-326415 (JP, A) JP-A-64-17484 (JP, A) JP-A-7-249795 (JP, A) 8-228048 (JP, A) JP-A-6-232451 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 33/00 H01S 5/00-5/50 H01L 21 / 205

Claims (8)

(57) [Claims] A buffer layer is provided between a substrate having a light emitting layer and a charge injection layer and a substrate, wherein the light emitting layer has a general formula of In _x G
a _y Al _z N (where 0 <x ≦ 1, 0 ≦ y <1, 0 ≦ z
<1, x + y + z = 1) in a 3-5 group compound semiconductor represented, the charge injection layer is the general formula _{In x 'Ga y' Al z} 'N
(Where 0 <x ′ ≦ 1, 0 ≦ y ′ <1, 0 ≦ z ′ <1, x ′
+ Y '+ z' = 1 ) is represented by, a 3-5 group compound semiconductor having a larger band gap than the light-emitting layer, the buffer layer is of the general formula In _u Ga _v Al _w N (wherein, 0 <u
≦ 1, 0 ≦ v is represented by the <1,0 ≦ w <1, u + v + w = 1), seen including a laminated structure composed of different layers of at least two compositions, and, formed on a sapphire substrate GaN
A group 3-5 compound semiconductor formed on a layer . 2. A layer having a light emitting layer and a charge injection layer, and a substrate
And a light emitting layer having a general formula In _x G
a _y Al _z N (where 0 <x ≦ 1, 0 ≦ y <1, 0 ≦ z
<1, x + y + z = 1) semiconductor of group 3-5 compound represented by 1)
A body, the charge injection layer is the general formula _{In x 'Ga y' Al z} 'N
( Where 0 <x ′ ≦ 1, 0 ≦ y ′ <1, 0 ≦ z ′ <1, x ′
+ Y '+ z' = 1 ) is represented by, a 3-5 group compound semiconductor having a larger band gap than the light emitting layer, a buffer _{layer, In u Ga v Al w N} ( where, 0 ≦ u <1 ,
0 ≦ v <1, 0 ≦ w <1, u + v + w = 1) Layer and In _{u ′}
Ga _v 'Al _w' N (in the formula, 0 ≦ u '<1,0 <v' ≦ 1,0
≦ w ′ <1, u ′ + v ′ + w ′ = 1) including a laminated structure alternately repeated at least twice , and sapphire
On the GaN layer formed on the substrate, it you said formed 3-V compound semiconductor. 3. A layer having a light emitting layer and a charge injection layer, and a substrate
And a light emitting layer having a general formula In _x G
a _y Al _z N (where 0 <x ≦ 1, 0 ≦ y <1, 0 ≦ z
<1, x + y + z = 1) semiconductor of group 3-5 compound represented by 1)
Wherein the charge injection layer is 0.1 eV or less than the light emitting layer.
Group 3-5 compound semiconductor with large band gap
A is, the buffer layer has the general formula In _u Ga _v Al _w N
( Where 0 <u ≦ 1, 0 ≦ v <1, 0 ≦ w <1, u + v
+ W = 1), and at least two layers having different compositions
Including a laminated structure consisting of sapphire substrate
Formed on the formed GaN layer.
Group 3-5 compound semiconductor. 4. A layer having a light emitting layer and a charge injection layer, and a substrate
And a light emitting layer having a general formula In _x G
a _y Al _z N (where 0 <x ≦ 1, 0 ≦ y <1, 0 ≦ z
<1, x + y + z = 1) semiconductor of group 3-5 compound represented by 1)
Wherein the charge injection layer is 0.1 eV or less than the light emitting layer.
Group 3-5 compound semiconductor with large band gap
A is, the buffer _{layer, In u Ga v Al w N} ( wherein
Where 0 ≦ u <1, 0 ≦ v <1, 0 ≦ w <1, u + v + w
= 1) layer and In _{u ′} Gav _′ Al _{w ′} N (where 0 ≦ u ′ <
1, 0 <v ′ ≦ 1, 0 ≦ w ′ <1, u ′ + v ′ + w ′ = 1)
And a layered structure in which the layers are alternately repeated at least twice.
On the GaN layer formed on the sapphire substrate
A half-group 3-5 compound characterized by being formed
conductor. 5. The method according to claim 1, wherein the charge injection layer has a general formula of In _{x '} Gay _' Al _{z '} N.
( Where 0 <x ′ ≦ 1, 0 ≦ y ′ <1, 0 ≦ z ′ <1, x ′
+ Y ′ + z ′ = 1).
5. A Group 3-5 compound semiconductor according to any one of (1) to (4). 6. A GaN layer is grown at a low temperature on a sapphire substrate.
A buffer formed through a buffer layer.
6. A Group 3-5 compound semiconductor according to any one of claims 1 to 5. 7. A buffer layer according to any one of claims 1-6, characterized in that it consists of at least four layers 3
Group 5 compound semiconductor. 8. claim 1, characterized in that it comprises a laminated structure which is w> 0 at least one layer of the buffer layer
8. A Group 3-5 compound semiconductor according to any one of Items 1 to 7.