JP3279308B2 - Nitride semiconductor light emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a nitride semiconductor light emitting device. More specifically, the present invention relates to a nitride semiconductor light emitting device effectively used as a semiconductor laser.

[0002]

2. Description of the Related Art Light-emitting diodes (LEDs) using GaN-based nitride semiconductors have already been commercialized. At present, research on GaN-based nitride semiconductor laser diodes (LDs) has been actively conducted. I have. For example, in the 1996 Japanese Journal of Applied Physics, Vol. 35, page L217, there is a report entitled "InGaN Multiple Quantum Well Structure Laser Diode Having Cleaved Mirror Resonator Surface". FIG. 14 shows a cross-sectional structure of a GaN-based nitride semiconductor LD device described therein. This is because the oscillation wavelength of a GaN-based nitride semiconductor laser is 415n.
This is a report of room temperature pulse oscillation at m. Since the GaN-based nitride semiconductor laser has a shorter wavelength than a conventional red LD, it has attracted much attention as a light source for pickup of a next-generation optical disk device having a high storage density.

[0003]

However, the operating voltage of this laser at the lasing threshold current value is still as high as 30 V. This is mainly because the contact resistance between the p-type GaN contact layer and the p-electrode is large. FIG. 9 is a cross-sectional view schematically showing a band structure at the interface between the metal electrode and the p-type GaN semiconductor layer. There is a large Schottky barrier between GaN and the metal electrode. GaN has a large band gap, and particularly has a large Schottky barrier for holes. In order to achieve continuous room temperature oscillation of a GaN-based nitride semiconductor laser, it is indispensable to reduce the p-side contact resistance, realize ohmic contact, and lower the operating voltage of the laser. The present invention has been made in view of the above problems, and has as its object to provide a nitride semiconductor light emitting device that has low contact resistance, can operate at low voltage, and has high reliability.

[0004]

According to the present invention, there is provided a light-emitting device using a GaN-based nitride semiconductor, wherein a semiconductor layer on a metal electrode side has a p-type or n-type. A GaN _1-X As _X layer (0 <X <0.2) or an InGaN _1-X As _X layer (0 <X <0.2), the thickness of which is the cladding layer of the light emitting device Provided is a nitride semiconductor light-emitting device having a thickness not more than the critical film thickness of the nitride semiconductor light-emitting device.

In a preferred embodiment, the semiconductor layer comprises a plurality of GaN _1-X As _{X having} different As compositions _X.
A layer (0 <X <0.2) or an InGaN _1-X As _X layer (0 <X <0.2) so that the As composition X increases as approaching the electrode. A nitride semiconductor light emitting device is provided.

Further, according to the present invention, in a light emitting device using a nitride semiconductor of GaN-based semiconductor layer of the metal electrode side, p-type or n-type I nGaN _1-Y P Y layer (0 <Y
<0.2), and a layer thickness of the nitride semiconductor light emitting device is not more than a critical thickness with respect to a cladding layer of the light emitting device.

In a preferred embodiment, the semiconductor layer is formed by increasing a plurality of InGaN _1-Y P _Y layers (0 <Y <0.2) having different P compositions Y as the P composition Y approaches the electrode. Provided is a nitride semiconductor light emitting device characterized by being configured in such a manner as to be combined.

In a preferred embodiment, a nitride semiconductor light emitting device is provided, wherein the thickness of the semiconductor layer is 1 nm or more and 100 nm or less.

In a preferred embodiment, an intermetallic compound epitaxial layer is formed between the metal electrode and the semiconductor layer so as to be adjacent to the respective layers. An element is provided.

In a preferred embodiment, the metal
Intermetallic compound epitaxial layer is Ni _0.5 In_0.5 ,Also
Is Ni_0.5 (In_1-W Tl_W )_0.5 (0 <W <1)
Provided is a nitride semiconductor light emitting device,
You.

In a preferred embodiment, a nitride semiconductor light emitting device is provided, wherein the thickness of the semiconductor layer is 2 nm or more and 200 nm or less.

In a preferred embodiment, the semiconductor layer is a p-type GaN _1-X1 As _X1 layer (0 <X1 <0.
2) Well layer and p-type GaN _1-X2 As _X2 layer (0 ≦ X2 <
X1 <0.2) There is provided a nitride semiconductor light emitting device having a superlattice structure with a barrier layer.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below.
Will be explained. In the present invention, the portion in contact with the metal electrode
P-type or n-type GaN_1-X As
_X (0 <X <0.2), InGaN_1-X As_X (0 <X
<0.2), GaN_1-Y P_Y (0 <Y <0.2) and
InGaN_1-Y P_Y (0 <Y <0.2) is used.
Hereinafter, p-type GaN will be described. Several percent As in GaN
To make the band gap smaller than GaN
Can be However, when As composition X is increased, G
aN_1-X As_X The layers gradually become lattice mismatched. FIG.
Is GaN_1-XAs_X Between the As composition X and the lattice strain ε
It is a graph which shows a relationship. For example, GaN on GaN_0.96
As_0.04The strain amount of the layer becomes 3.4%. FIG.
_1-X As _X The relationship between the As composition X of the layer and the band gap is shown.
This is a graph. From this figure, GaN_0.96As_0.04Layer of ba
The gap is 2.63 eV, about 0.77 eV
Band gap smaller than Kerutz-type GaN
You can see that Metal electrode and p-type semiconductor layer boundary shown in FIG.
As can be seen from the cross section of the band structure on the
By using a material with a small gap for the contact layer,
Burrs of holes at the interface between semiconductor and semiconductor contact layer
A height can be reduced.

FIG. 12 is a graph showing the relationship between the As composition X of the GaN _1-x As _X layer and the critical film thickness. Since the GaN-based material is very hard, the critical thickness of the GaN-based material is GaAs.
It is larger than the critical thickness of the system material. From FIG. 12, for example, Ga
It can be seen that the critical thickness of the N _0.96 As _0.04 layer is 16 nm. The layer thickness of the GaN _0.96 As _0.04 layer contact layer of the embodiment of the present invention is 15 nm, which is smaller than the critical film thickness. In order to obtain high-quality crystals, it is necessary to control the As composition and make the thickness less than the critical thickness. For example, 1 nm to 100 nm is preferable. The GaN _1-x As _x contact layer of the present invention is a high-quality crystal having a small band gap and a layer thickness equal to or less than the critical film thickness as described above.

High-quality crystals having a small band gap and a critical thickness or less can perform p-doping at a higher concentration. As shown in FIG. 9, a contact layer having a high p doping concentration has an effect of reducing the width of a Schottky barrier of a hole at the interface between a metal electrode and a semiconductor contact layer. As the width of the Schottky barrier decreases, the contact resistance of the element decreases, and the operating voltage of the element decreases. Therefore, the nitride semiconductor light emitting device having the GaN _1-x As _X layer contact layer of the present invention has characteristics of lower resistance and lower operating voltage operation than the device without it. This suppresses heat generation during operation, which is extremely effective in achieving continuous operation of the semiconductor laser at room temperature.

Ni_0.5 In_0.5 And Ni_0.5(In_1-W T
l_W )_0.5 Intermetallic compound layers such as (0 <W <1) are metal
It has the same high electrical conductivity as. Ni_0.5 In_0.5 When
The amount of lattice mismatch strain with ordinary wurtzite GaN is 2%.
Ni, which has a thin film tensile strain on GaN_0.5In_0.5 
Can be epitaxially grown. Ni_0.5 (In
_1-W Tl_W )_0.5 By adjusting the Tl composition W
Can match the in-plane lattice constant of GaN
Therefore, a thick intermetallic compound layer can be formed. Compressive strain Ga
N_1-X As_X GaN layer and Ni contact layer_0.5In
_0.5 And Ni_0.5(In_1-W Tl_W )_0.5 Intermetallic
When the structure is sandwiched between compound epitaxial layers, lattice matching
Layer supports the strained contact layer from both sides.
And the critical thickness is doubled. FIG.
3 is GaN sandwiched from both sides by a lattice matching layer_1-X A
s_X 5 is a graph showing the relationship between the As composition X of a layer and the critical film thickness.
You. The curve shown by the dotted line is the case where
It is a critical film thickness curve. GaN mentioned above_1-X As_X Contact
G having a larger As composition X and a smaller band gap than the G layer
aN_1-X As_X Contact layer is obtained or G
aN_1-X As_X The thickness of the contact layer can be doubled
You can see that. For example, the lattice matching layer
GaN from the side_0.92As_0.08By sandwiching the layers, Ga
N_0.92As_0.08The critical thickness of the layer is from 4.3 nm to 19 nm
To increase. From FIG. 11, GaN_0.92As _0.08Layered van
It can be seen that the gap is 1.917 eV. this
Is the band gap of GaInP lattice-matched to the GaAs substrate.
Equal to the size of the tip. This GaInP is 10¹⁹cm^-3Table
High-concentration p doping is possible. GaN band
Since the gap is 3.4 eV, GaN_0.92As_0.08layer
About 1.5 eV of the contact layer band by using
The gap has been reduced. This is because Ga
N_0.96As_0.04This is twice the amount of reduction in the case of a layer.

After all, as described above, the GaN _1-X A
By sandwiching the s _X contact layer, there is an effect that the contact resistance of the LD element is further reduced and the operating voltage is reduced. In this case, the thickness of the intermetallic compound layer is 5 to 200 n.
m is preferred. The layer thickness of the semiconductor layer when using this intermetallic compound layer is preferably 2 to 200 nm.

[0018]

EXAMPLES The present invention will be described more specifically with reference to the following examples. FIG. 1 is a sectional view of a GaN-based nitride semiconductor light emitting device (LD) according to a first embodiment of the present invention. As shown in FIG. 1, the GaN-based LD includes an A-plane sapphire substrate 101 having a thickness of 350 μm, and a GaN buffer layer 1 having a thickness of 30 nm.
02, n-GaN layer 103 having a layer thickness of 3 μm, layer thickness 100 n
m n-In _0.1 Ga _0.9 N layer 104, layer thickness 400 nm
Of n-Al _0.15 Ga _0.85 N layer 105, n-GaN layer 106 having a thickness of 100nm, InGaN / GaN-MQW active layer 107, the layer thickness _{20nm p-Al 0.2 Ga 0. 8} N cladding layer 108, a layer thickness 100nm P-GaN layer 109,
400 nm thick p-Al _0.15 Ga _0.85 N cladding layer 1
10, a 500 nm-thick p-GaN cladding layer 111,
15-nm-thick p-GaAs _0.04 N _0.96 contact layer 1
12, a p-electrode 113 and an n-electrode 114. InGa
The N-MQW active layer 107 has a thickness of 2.5 nm of In _0.2 Ga.
_{This is} a 20-period multiple quantum well (MQW) layer of a _0.8 N well layer and a 5 nm In _0.05 Ga _0.95 N barrier layer. The p dopant used for each layer is Mg, and the n dopant is Si. Feature of the present invention having a thickness of 15nm p-GaAs _{0. 04}
N _{0.96 has a} contact layer 112.

The above LD is metalorganic vapor phase epitaxial.
(MOVPE) growth method and gas source molecular beam
(GSMBE) It can be manufactured using a growth method. MO below
VPE method of the LD device of the first embodiment of the present invention
The manufacturing method will be described. The following examples are also described below.
Manufacturing method can be used. Group V materials include N
H _Three, AsH_Three , Group III raw materials include trimethylindium
(TMIn), trimethylgallium (TMGa),
Limethylaluminum (TMAl) is used. p-dopa
The raw material is CP_Two Mg, n dopant raw material is SiH
₄ Is used.

First, the A-plane sapphire substrate 101 was introduced into a reaction tube as a growth chamber, and H ₂ carrier gas was flowed through the reaction tube. In this state, the substrate was heated to 1150 ° C., heated for 10 minutes, then lowered to 550 ° C., and NH ₃ and TMGa were introduced to grow a GaN buffer layer 102 having a thickness of 30 nm. Thereafter, the substrate temperature was raised to 1000 ° C. while flowing the H ₂ carrier gas through the reaction tube, and NH ₃ , TMGa and Si
By introducing H ₄ , the n-GaN layer 103 having a thickness of 3 μm is grown. Although the sapphire substrate and GaN have a lattice mismatch of as much as 14%, GaN with good crystallinity was obtained by first growing the GaN buffer layer 102 grown at a low temperature and controlling the layer thickness. Next, n-In _0.1 Ga having a thickness of 100 nm was introduced to prevent cracking by introducing TMIn.
_{A 0.9} N layer 104 was grown. In this way, they were sequentially grown. The p-GaAs _0.04 N _0.96 contact layer 112 which is a feature of the present invention is composed of NH ₃ , AsH ₃ , TMGa and CP.
It was grown by introducing ₂ Mg. p-doping concentration is 5
× 10 ¹⁸ cm ^-3 or more. By setting the layer pressure of the p-GaAs _0.04 N _0.96 contact layer 112 to 15 nm, a crystal of good quality within the critical film thickness was obtained. 600 ° C after growth
Was performed for 1 hour to drive out the H atoms taken into the crystal, activate Mg, and improve the p concentration.

After the growth was completed, the temperature was lowered slowly so that the sapphire substrate was not broken. After removing the wafer, p
-P electrode 1 on GaAs _0.04 N _0.96 contact layer 112
13 and etching is performed to form n-GaN layer 103 with n.
The electrode 114 was attached to obtain an LD element. The structure of the main body including the active layer of the GaN-based nitride semiconductor LD of the following examples is common, and only the contact layer and the electrode are different. Therefore, the present invention is applicable to an LD having any structure.

Embodiment 2 FIG. 2 is a sectional view of a GaN-based nitride semiconductor LD according to a second embodiment of the present invention. As shown in FIG. 2, the p-GaAs _0.04 N _0.96 contact layer 11
The LD structure is the same as that of the first embodiment except that only part 2 is different. That is, the second embodiment is different from the first embodiment in the layer thickness 15
The n-type p-GaAs _0.04 N _0.96 contact layer 112 is replaced with the 20-nm-thick p-GaAs _0.01 N _0.99 contact layer 20.
1. A GaN-based nitride semiconductor LD having a structure in which a step contact layer 204 including a p-GaAs _0.02 N _0.98 contact layer 202 with a layer thickness of 5 nm and a p-GaAs _0.04 N _0.96 contact layer 203 with a layer thickness of 10 nm is used. In the step contact layer 204, the size of the band gap of the contact layer gradually decreases due to the increase in the As composition. Thereby, a sharp band gap difference between the p-GaN cladding layer 111 and the p-GaAs _0.04 N _0.96 contact layer 203 can be reduced, so that the resistance of the device can be reduced.

Embodiment 3 FIG. 3 is a sectional view of a GaN-based nitride semiconductor LD according to a third embodiment of the present invention. As shown in FIG. 3, the p-GaAs _0.04 N _0.96 contact layer 11
2 is replaced with a 20 nm-thick p-GaP _0.04 N _0.96 contact layer 301.
This is a GaN-based nitride semiconductor LD having the same structure as that of the embodiment. GaP _X N _{1 -X} also has a property that the band gap is greatly reduced with an increase in the P composition X. GaP _0.04
N _0.96 has an advantage that the thickness of the contact layer can be increased because the amount of strain with respect to GaN is smaller than that of GaAs _0.04 N _0.96 .

Embodiment 4 FIG. 4 is a sectional view of a GaN-based nitride semiconductor LD according to a fourth embodiment of the present invention. As shown in FIG. 4, the step contact layer 204 of the second embodiment
To a 5 nm-thick p-GaP _0.01 N _0.99 contact layer 4
This is a GaN-based nitride semiconductor LD having a structure in which a step contact layer 404 composed of a p-GaP _0.02 N _0.98 contact layer 402 having a thickness of 01, 5 nm and a p-GaP _0.04 N _0.96 contact layer 403 having a thickness of 12 nm is used. The step contact layer 404 allows the p-GaN cladding layer 1
11 and p-GaP _0.04 N _0.96 contact layer 403 can alleviate a sharp band gap difference, so that the resistance of the device can be reduced.

Embodiment 5 FIG. 5 is a sectional view of a GaN-based nitride semiconductor LD according to a fifth embodiment of the present invention. As shown in FIG. 5, except that a 15 nm thick Ni _0.5 In _0.5 intermetallic compound layer 502 is sandwiched between a 15 nm thick p-GaAs _0.04 N _0.96 contact layer 501 and a p electrode 113. This is a GaN-based nitride semiconductor LD having the same structure as in the first embodiment. Ni _0.5 In _0.5 intermetallic compound layer 502
Is a tensile strain, and the p-GaAs _0.04 N _0.96 contact layer 501 is a compressive strain. Therefore, by combining them, the strain is compensated and the entire strain amount is reduced. The crystal structure of these intermetallic compounds is CsCl type, and GaAs and I
Zinc blende type crystal structure of III-V compound semiconductor such as nP and G
This is different from the wurtz crystal structure of aN. However, the lattice constant 3.1 of Ni _0.5 In _0.5 is wurtzian GaN
Is approximately equal to the in-plane lattice constant of 3.16, so that epitaxial growth on GaN is possible. p-GaAs _0.04
The process up to the N _0.96 contact layer 501 is performed under the growth conditions described above. However, since the crystal growth of the intermetallic compound thin film on GaN is heteroepitaxial growth with a heteroatom structure, unusual growth conditions are required.

A method for growing an intermetallic compound layer on GaN used in this embodiment will be described below. When growing an intermetallic compound layer on GaN, the surface of the GaN semiconductor layer is
To sufficiently reduce the amount of the residual group V in the growth chamber, and then grow one atomic layer of Ni, which is a transition metal of the intermetallic compound layer, and then deposit the Ni _0.5 In _0.5 intermetallic compound layer. Grew. The growth temperature of the intermetallic compound layer was low. Migration Enhanced Epitaxy (M
EE) about 350 ° C. for growth, 45 for MBE growth
It is about 0 ° C. However, in the lattice-matched intermetallic compound layer, MEE is grown on InP at a growth temperature of about 250 ° C.
It may be grown.

Embodiment 6 FIG. 6 is a sectional view of a GaN-based nitride semiconductor LD according to a sixth embodiment of the present invention. As shown in FIG. 6, the Ni _0.5 In _0.5 intermetallic compound layer 502 of the fifth embodiment is lattice-matched to GaN and has a thickness of 50 nm.
_This is a GaN-based nitride semiconductor LD having the same structure as that of the fifth embodiment except that the structure is replaced by a _0.5 (Tl _x In _1-x ) _0.5 intermetallic compound layer 602. Ni _0.5 (Tl _X I
n _1-x ) _0.5 p-GaAs _{0.08 in the} intermetallic compound layer 602
By sandwiching the N _0.92 contact layer 501, 1.5e
V band gap can be reduced. Ni _0.5 (T
Since the (l _x In _1-x ) _0.5 intermetallic compound layer 602 is lattice-matched to GaN, a high-quality, thick-film, intermetallic compound epitaxial electrode can be formed.

[Embodiment 7] FIG. 7 is a sectional view of a GaN-based nitride semiconductor LD according to a seventh embodiment of the present invention. As shown in FIG. 7, a p-GaAs _0.08 N _0.92 contact layer 701 having a thickness of 19 nm and a layer thickness of 10 nm lattice-matched to GaN
Ni _0.5 (Tl _x In _1-x ) _0.5 intermetallic compound layer 70
2. Ni _0.5 In _0.5 intermetallic compound layer 7 having a thickness of 10 nm
03, Ni _0.5 lattice-matched to GaN with a layer thickness of 50 nm
(Tl _X In _1-x ) A GaN-based nitride semiconductor LD having a contact layer structure composed of a _0.5 intermetallic compound layer 704. Ni _0.5 with a layer thickness of 10 nm lattice-matched to GaN
(Tl _x In _1-x ) _0.5 intermetallic compound layer 702 is p-G
aAs _0.08 N _0.92 contact layer 701 and Ni _0.5 In
_This is a relaxation layer for improving a rapid change in interfacial strain of the _0.5 intermetallic compound layer 703.

[Eighth Embodiment] FIG. 8 is a sectional view of a GaN-based nitride semiconductor LD according to an eighth embodiment of the present invention. As shown in FIG. 8, the p-GaAs _0.01 N _0.99 barrier layer 801 having a thickness of 5 nm and the p-GaAs _0.08 N _0.92 well layer 802 having a thickness of 3 nm have five periods of a superlattice contact layer 804 and Ga.
Ni _0.5 (Tl _x In) with a layer thickness of 50 nm lattice-matched to N
_1-X ) A GaN-based nitride semiconductor LD having a contact layer structure composed of a _0.5 intermetallic compound layer 803. The holes can pass through the superlattice contact layer 804 having a thickness of 40 nm through the resonance tunnel and reach the metal electrode, so that the contact resistance is reduced.

[0030]

According to the present invention, the contact layer is made of GaN.
This is a high-quality p-type GaN _1-x As _X crystal having a band gap of half of that of Example 1 and a layer thickness equal to or less than the critical film thickness. Since the band gap is small, p-doping at a high concentration of 5 × 10 ¹⁸ cm ⁻³ or more can be performed. The intermetallic compound layer such as Ni _0.5 In _0.5 or Ni _0.5 (In _1-X Tl _x ) _0.5 used in the present invention contains dislocations to support the GaN _1-X As _X strained contact layer sandwiched between the GaN layers. And the critical film thickness doubles. Therefore, a GaN _1-x As _X layer having a smaller band gap can be used as the contact layer. As a result, the width and height of the Schottky barrier at the hole at the interface between the metal electrode and the semiconductor contact layer can be reduced by half. As a result, the contact resistance of the nitride semiconductor light emitting device is greatly reduced, and an operating voltage close to that of an LD device on a normal GaAs substrate can be obtained. As a result, heat generation during operation is suppressed, so that continuous operation of the nitride semiconductor laser at room temperature can be achieved. In addition, the threshold, temperature characteristics, and reliability of the nitride semiconductor laser can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a GaN-based nitride semiconductor LD according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a GaN-based nitride semiconductor LD according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a GaN-based nitride semiconductor LD according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a GaN-based nitride semiconductor LD according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a GaN-based nitride semiconductor LD according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view of a GaN-based nitride semiconductor LD according to a sixth embodiment of the present invention.

FIG. 7 is a sectional view of a GaN-based nitride semiconductor LD according to a seventh embodiment of the present invention.

FIG. 8 is a sectional view of a GaN-based nitride semiconductor LD according to an eighth embodiment of the present invention.

FIG. 9 is a cross-sectional view schematically showing a band structure at an interface between a metal electrode and a p-type semiconductor layer.

FIG. 10 is a graph showing the relationship between the As composition X of the GaN _1-X As _X layer and the amount of lattice strain ε.

FIG. 11 is a graph showing a relationship between an As composition X of a GaN _1-X As _X layer and a band gap.

FIG. 12 is a graph showing the relationship between the As composition X of the GaN _1-X As _X layer and the critical film thickness.

FIG. 13: As of a GaN _1-X As _X layer sandwiched from both sides
4 is a graph showing a relationship between a composition X and a critical film thickness.

FIG. 14 is a sectional view showing the structure of a conventional GaN-based nitride semiconductor LD device.

[Explanation of symbols]

101 A-plane sapphire substrate 102 GaN buffer layer 103 n-GaN layer 104 n-In _0.1 Ga _0.9 N layer 105 n-Al _0.15 Ga _0.85 N layer 106 n-GaN layer 107 InGaN / GaN-MQW active layer 108 p-Al _0.2 Ga _0.8 N cladding layer 109 p-GaN layer 110 p-Al _0.15 Ga _0.85 N cladding layer 111 p-GaN cladding layer 112 p-GaAs _0.04 N _0.96 contact layer 113 p electrode 114 n electrode 201 p-GaAs _0.01 N _0.99 contact layer 202 p-GaAs _0.02 N _0.98 contact layer 203 p-GaAs _0.04 N _0.96 contact layer 204 step contact layer 301 p-GaP _0.04 N _0.96 contact layer 401 p-GaP _0.01 N _0.99 contact layer 402 p-GaP _0.02 N _0.98 contact layer 403 p-GaP _{0.04 0.96} contact layer 404 Step contact layer 501 p-GaAs _0.04 N _0.96 contact layer 502 Ni _0.5 In _0.5 intermetallic compound layer _{602 Ni 0.5 (Tl X In 1} -X) 0.5 intermetallic compound layer 701 p-GaAs _0.08 N _0.92 contact layer 702 Ni _0.5 (Tl _x In ₁ -x) _0.5 intermetallic compound layer 703 Ni _0.5 In _0.5 intermetallic compound layer 704 Ni _0.5 (Tl _x In ₁ -x) _0.5 intermetallic compound layer 801 p-GaAs _0.01 N _0.99 barrier layer 802 p-GaAs _0.08 N _0.92 well layer 803 Ni _0.5 (Tl _x In ₁ -x) _0.5 intermetallic compound layer 804 superlattice contact layer 901 conduction band 902 Fermi level 903 valence band 904 Schottky barrier width 905 Schottky barrier Height 906 hole 907 metal electrode 908 p-type semiconductor layer

Continuation of the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01S 5/00-5/50 H01L 33/00 JICST file (JOIS)

Claims (9)

(57) [Claims] In a light emitting device using a GaN-based nitride semiconductor, a semiconductor layer on a metal electrode side is a p-type or n-type GaN _1-x As _X layer (0 <X <0.2) or In
A nitride semiconductor light emitting device, wherein the GaN _1-X As _X layer (0 <X <0.2) has a thickness less than or equal to a critical film thickness for the cladding layer of the light emitting device. . 2. The semiconductor layer comprising a plurality of GaN _1-x As _X layers (0 <X <0.2) or I
The nGaN _1-x As _X layer (0 <X <0.2) is
2. The nitride semiconductor light emitting device according to claim 1, wherein the composition is combined so that the composition X increases as approaching the electrode. 3. A light-emitting element using a GaN-based nitride semiconductor, wherein the semiconductor layer on the metal electrode side is a p-type or n-type InGaN _1-Y P _Y layer (0 <Y <0.2). hand,
A nitride semiconductor light-emitting device having a layer thickness equal to or less than a critical film thickness of the light-emitting device with respect to a cladding layer. 4. The semiconductor layer according to claim 3, wherein the plurality of InGaN _1-Y P _Y layers having different P compositions Y (0 <Y <0.2)
4. The nitride semiconductor light emitting device according to claim 3, wherein the P composition Y is combined so that the P composition Y increases as approaching the electrode. 5. The semiconductor layer according to claim 1, wherein said semiconductor layer has a thickness of 1 nm or more.
The nitride semiconductor light emitting device according to any one of claims 1 to 4, wherein the thickness is not more than 00 nm. 6. Between the metal electrode and the semiconductor layer,
6. An intermetallic compound epitaxial layer is formed adjacent to each layer.
The nitride semiconductor light emitting device according to any one of the above. 7. The intermetallic compound epitaxial layer,
Ni _0.5 In _0.5 or Ni _0.5 (In _1-W Tl
7. The nitride semiconductor light emitting device according to claim 6, wherein _W ) _0.5 (0 <W <1). 8. The semiconductor layer having a thickness of 2 nm or more and having a thickness of 2 nm or more.
8. The structure according to claim 6, wherein the thickness is not more than 00 nm.
The nitride semiconductor light-emitting device according to any of the preceding claims. 9. The method according to claim 1, wherein the semiconductor layer is a p-type GaN _1-X1 As.
_X1 layer (0 <X1 <0.2) well layer and p-type GaN _1-X2
3. The nitride semiconductor light emitting device according to claim 1, wherein the nitride semiconductor light emitting device has a superlattice structure with an As _X2 layer (0 ≦ X2 <X1 <0.2) barrier layer.