JP2000058916A - Gallium nitride-based compound semiconductor light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure for a gallium nitride-based compound semiconductor light emitting element whose light emitting efficiency can be enhanced and whose operating voltage can be reduced. SOLUTION: A substrate 1 is provided. An n-type contact layer 3a and an n-type contact layer 3b which are composed of a gallium nitride-based compound semiconductor are provided. An active layer 5 is provided. A semiconductor laminated structure 300 which is composed of a gallium nitride-based compound semiconductor is provided between the n-type contact layer 3a and the substrate 1 and/or between the active layer 5 and the n-type contact layer 3b. The semiconductor laminated structure 300 is constituted in such a way that at least a first n-type layer which is composed of undoped GaN and a second n-type layer which is formed so as to be adjacent to the first n-type layer and which is composed of AlxGa1-xN (where 0<=x<=1) doped with n-type impurities are contained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gallium nitride-based compound semiconductor light emitting device used for an optical device such as a light emitting diode and a laser diode.

[0002]

2. Description of the Related Art Gallium nitride-based compound semiconductors have come to be widely used as semiconductor materials for visible light emitting devices and high-temperature operating electronic devices. Are being developed in the field of laser diodes. In particular, in the field of light-emitting diodes, a luminous efficiency improvement of several tens to about 100 times has been achieved as compared with a conventionally used blue light-emitting element made of SiC, and high-efficiency light emission is required. Since it can be suitably used for outdoor display devices, it has attracted much attention.

[0003] Gallium nitride-based compound semiconductor light emitting devices capable of emitting visible light, including those used in light emitting diodes and laser diodes, basically have an active layer made of InGaN having a band gap larger than that of the active layer. G
The mainstream includes a double heterostructure sandwiched by p-type and n-type cladding layers made of aN, AlGaN, or the like.
A p-type contact layer made of GaN is formed in contact with the p-type cladding layer, and an n-type contact layer made of GaN is formed in contact with the n-type cladding layer. These laminated structures are manufactured using a gallium nitride compound semiconductor thin film grown and formed on a substrate made of sapphire, SiC, or the like by a crystal growth method such as a metal organic chemical vapor deposition method or a molecular beam epitaxy method. It is mainstream in recent years.

A gallium nitride-based compound semiconductor used for light-emitting diodes of blue, green, and the like, which has recently been put to practical use, basically has the above-mentioned laminated structure. Sapphire is used for a substrate, and n The structure is such that a mold contact layer, an n-type clad layer, an active layer, a p-type clad layer, and a p-type contact layer are sequentially laminated. (Hereinafter, the side on which the n-type contact layer and the n-type cladding layer are formed may be referred to as the n-side, and the side on which the p-type cladding layer and the p-type contact layer are formed may be referred to as the p-side. , A p-side electrode is formed on the surface of the p-type contact layer, and a p-type contact layer, a p-type cladding layer, and an active layer are formed on the n-type contact layer in the direction opposite to the stacking direction from the p-type contact layer side. An n-side electrode is formed on a surface where a part of the n-type contact layer is removed and exposed. Then, by applying a voltage to the p-side electrode and the n-side electrode, holes are injected into the active layer from the p-type contact layer side and electrons are injected from the n-type contact layer side. In the active layer, light emission corresponding to the band gap energy of the active layer is basically obtained by the recombination of the injected holes and electrons.

By the way, as typified by the case where insulating sapphire is used for a substrate, a light emitting element having a structure in which a p-side electrode and an n-side electrode are provided on the same surface side of a substrate is known.
When a voltage is applied, electrons injected from the n-side electrode into the n-type contact layer move in the n-type contact layer or the n-type cladding layer in a direction substantially perpendicular to the lamination direction, that is, in a plane direction. Will be included.

[0006] The gallium nitride-based compound semiconductor is characterized in that it has a higher resistivity than other group III-V compound semiconductors, so that current does not easily flow and electrons do not easily move. Therefore, electrons injected from the electrode into the n-type contact layer move from the n-type contact layer to the active layer so that the resistance decreases, and tend to concentrate in a region below the active layer and near the electrode. is there. For this reason, in the active layer, light emission concentrates in a region near the n-type contact layer, and there is a problem that it is difficult to obtain uniform light emission in a plane from the active layer.

Therefore, in order to solve this problem, a layer having a higher electron concentration than the n-type contact layer is formed between the n-type contact layer and the active layer, and electrons are uniformly spread in the plane in this layer. A structure capable of injecting electrons uniformly into the active layer in the plane has been proposed. Such a structure is disclosed in, for example,
No. 23124.

FIG. 8 is a sectional view showing the structure of a conventional gallium nitride-based compound semiconductor light emitting device disclosed in the above publication. 8, an n-type contact layer 43 is formed on a substrate 41 with a buffer layer 42 interposed therebetween. An n-type high concentration layer 403 having an electron concentration higher than that of the n-type contact layer 43 is formed on the n-type contact layer 43. Then, on the n-type high concentration layer 403,
n-type cladding layer 44, active layer 45, p-type cladding layer 4
6. A p-type contact layer 47 is formed. A p-side electrode 49 is formed on the surface of the p-type contact layer 47, and the p-type contact layer 47, the p-type cladding layer 46, the active layer 45,
An n-side electrode 48 is formed on the surface of the n-type contact layer 43 exposed by removing a part of the n-type cladding layer 44 and the n-type high concentration layer 403 in a direction opposite to the laminating direction. Thus, by providing the n-type high concentration layer 403 having an electron concentration higher than that of the n-type contact layer 43 between the n-type contact layer 43 and the n-type cladding layer 44, the n-side electrode 48 is formed.
It is said that the electrons injected into the n-type contact layer 43 from the active layer 45 easily spread uniformly in the n-type high-concentration layer 403, so that a uniform surface emission can be obtained from the active layer 45.

[0009]

In the gallium nitride-based compound semiconductor light-emitting device, including the improvement by the above structure, various improvements have been made to increase the luminous output and reduce the operating voltage. The luminous efficiency has been improved about 100 times compared to the blue light-emitting element made of SiC, and has been put to practical use. However, as developments in many application fields such as large-sized outdoor display devices and various light sources progress, further improvement in luminous efficiency and reduction in operating voltage are desired in order to improve visibility and reduce power consumption. It has come to be.

An object of the present invention is to provide a structure of a gallium nitride-based compound semiconductor light emitting device which can further improve the luminous efficiency and reduce the operating voltage.

[0011]

Means for Solving the Problems The present inventors have intensively studied a gallium nitride-based compound semiconductor light emitting device, particularly a semiconductor laminated structure composed of an n-type gallium nitride-based compound semiconductor provided between a substrate and an active layer. went. As a result, by providing between the active layer and the substrate a semiconductor laminated structure having a higher mobility than the mobility of electrons in the n-type contact layer forming an electrode for injecting electrons, the luminous efficiency is improved. And the operating voltage can be reduced.

That is, the present invention relates to a gallium nitride-based compound semiconductor light emitting device having at least a substrate, an n-type contact layer made of a gallium nitride-based compound semiconductor and an active layer, wherein the n-type contact layer and the substrate , And / or between the active layer and the n-type contact layer, a semiconductor laminated structure made of a gallium nitride-based compound semiconductor is provided. Is higher than the mobility in the plane direction of electrons in the n-type contact layer. And the semiconductor laminated structure has a first n-type GaN made of undoped GaN.
An Al _x Ga ₁ -xN layer formed in contact with the mold layer and the first n-type layer and doped with an n-type impurity (where 0 ≦ x ≦
1) a second n-type layer (hereinafter referred to as Al _x Ga ₁ -xN in the present specification).
Similarly, a gallium nitride-based compound semiconductor represented by an expression with a subscript may be simply referred to as AlGaN. ).

Further, in the present invention, the semiconductor laminated structure comprises a first n-type layer made of undoped GaN and an n-type layer.
Pair consisting of a second n-type layer doped with
It may include a multilayer structure stacked as described above.

According to such a configuration, the n-side electrode is connected to the n-side electrode.
Uniformity of injection of electrons into the active layer because electrons injected into the mold contact layer easily move in the n-side layer structure and easily spread over the entire surface of the n-side layer structure. Can be improved.

[0015]

The invention according to claim 1 is a gallium nitride-based compound semiconductor light emitting device having at least a substrate, an n-type contact layer and an active layer made of a gallium nitride-based compound semiconductor, a semiconductor stacked structure made of a gallium nitride-based compound semiconductor, provided between the n-type contact layer and the substrate, and / or between the active layer and the n-type contact layer, The planar mobility of electrons in the semiconductor multilayer structure is higher than the planar mobility of electrons in the n-type contact layer,
Improving the spread of electrons in the n-side layer structure by providing, in the n-side layer structure, a semiconductor laminated structure having a higher electron mobility than the planar mobility in the n-type contact layer. It has the effect of being able to.
Here, the n-type contact layer means a layer on which an n-side electrode for electrically injecting electrons by being electrically connected to the light emitting element is formed.

According to a second aspect of the present invention, there is provided a gallium nitride-based compound semiconductor light emitting device having at least a substrate, an n-type contact layer made of a gallium nitride-based compound semiconductor and an active layer, wherein the n-type contact layer And between the active layer and the n-type contact layer, or between the active layer and the n-type contact layer, the semiconductor layered structure includes a gallium nitride-based compound semiconductor. A first n-type layer made of undoped GaN, and formed in contact with the first n-type layer;
Al _x Ga ₁ -xN doped with a type impurity (where 0 ≦ x
≦ 1), a first n-type layer made of undoped GaN and a second n-type layer made of AlGaN doped with n-type impurities. The junction with the n-type layer has an effect that electrons easily move in these semiconductor laminated structures.

According to a third aspect of the present invention, in the second aspect of the present invention, the semiconductor multilayer structure includes a first n-type layer made of undoped GaN and a second n-type layer doped with an n-type impurity. And a multilayer structure in which two or more pairs of mold layers are stacked, and by joining the first n-type layer and the second n-type layer in multiple layers, This has the effect that electrons can be more easily moved in the semiconductor laminated structure.

According to a fourth aspect of the present invention, in the second or third aspect of the present invention, the semiconductor laminated structure is a third layer made of undoped GaN formed in contact with the second n-type layer. By forming a third n-type layer made of undoped GaN in contact with the second n-type layer, which further includes an n-type layer, electrons in these semiconductor stacked structures are more increased. It has the effect of making it easier to move.

The invention according to claim 5 provides the invention according to claims 2 to 4
In the invention described in any one of the above, the second n-type layer has an electron concentration of 4 × 10 ¹⁸ / cm ³ or more and 1 × 10 ²⁰ / c.
m ³ or less, characterized by specifying the electron concentration in the second n-type layer, the second n-type layer and the first n-type In the semiconductor laminated structure formed by bonding with the layer and / or the third n-type layer, electrons can be easily moved, and the crystallinity of the semiconductor laminated structure can be maintained well.

[0020] The invention according to claim 6 is the invention according to claims 2 to 5.
In the invention according to any one of the above, the thickness of the second n-type layer is adjusted to be in a range of 10 nm to 100 nm, and the thickness of the second n-type layer is The specification has an effect that the supply amount of electrons to the first n-type layer can be appropriately secured.

[0021] The invention described in claim 7 is the invention according to claims 2 to 6.
In the invention according to any one of the above, the thickness of the second n-type layer is adjusted to a range of 1 nm to 100 nm, and the thickness of the first n-type layer is By specifying, it is possible to secure the ease of movement of electrons in the semiconductor multilayer structure and to prevent the series resistance of the semiconductor multilayer structure from being excessively increased.

[0022] The invention according to claim 8 is the invention according to claims 1 to 4.
In the invention described in any one of (1) to (4), the second n-type layer has an undoped Al _x Ga ₁ -xN () on a side in contact with the first n-type layer and / or the third n-type layer. Where 0
≦ x ≦ 1), wherein an n-type impurity is diffused from the second n-type layer into the first n-type layer. This has the effect of preventing a decrease in electron mobility in one n-type layer.

According to a ninth aspect of the present invention, in the invention of the eighth aspect, the layer thickness of the impurity diffusion preventing region is 1
The thickness of the impurity diffusion preventing region is adjusted to a specific range to appropriately diffuse the n-type impurity into the first n-type layer. And an increase in series resistance in the second n-type layer can be prevented.

Hereinafter, specific examples of the embodiment of the present invention will be described.
This will be described with reference to FIGS. In these drawings, the same elements and the same members are denoted by the same reference numerals.

(Embodiment 1) FIG. 1 is a sectional view showing a structure of a gallium nitride-based compound semiconductor light emitting device according to a first embodiment of the present invention.

In FIG. 1, an n-type contact layer 3a, a semiconductor laminated structure 300, an n-type contact layer 3b, and an n-type clad layer 4 are formed on a substrate 1 with a buffer layer 2 interposed therebetween.
, An active layer 5, a p-type contact layer 6, and a p-type contact layer 7 are sequentially stacked. p-type contact layer 7
A p-side electrode 9 is formed on the surface of the p-type contact layer 9, the p-type contact layer 7, the p-type cladding layer 6, the active layer 5, and a part of the n-type cladding layer 4 are formed from the surface side of the p-type contact layer 9. An n-side electrode 8 is formed on the surface of the n-type contact layer 3b which has been removed by etching and exposed.

The substrate 1 includes sapphire, GaN, Si
C, spinel (MgAl ₂ O) or the like can be used.

GaN, AlN, Al
GaN, AlInN or the like can be used.
A film formed at a temperature of 00 ° C. or less and a thickness of several nm to several tens nm can be preferably used. Here, since the buffer layer 2 has an action of alleviating the lattice mismatch between the substrate 1 and the laminated structure made of the gallium nitride-based compound semiconductor formed thereon, like the GaN, When a substrate having a lattice constant close to that of the gallium nitride-based compound semiconductor formed thereon is used, the formation of the buffer layer 2 can be omitted depending on the growth method and growth conditions.

The n-type contact layers 3a and 3b are formed of a gallium nitride-based compound semiconductor,
In particular, it is preferably formed of GaN or AlGaN.
The gallium nitride-based compound semiconductor tends to exhibit the n-type conductivity even in an undoped state in which the n-type impurity is not doped. In particular, when used as an n-type contact layer for providing the n-side electrode 8, Si or Ge is used. When GaN doped with an n-type impurity such as is used, an n-type layer having a high electron concentration can be obtained, and the contact resistance with the n-side electrode 8 can be reduced.

The n-side electrode 8 formed on the surface of the n-type contact layer 3b is made of a metal such as Al, Ti, Au or the like having a good ohmic property with the n-type contact layer 3b. Can be used in a state.

The n-type cladding layer 4 is formed of a gallium nitride-based compound semiconductor and formed of Al _a Ga _1-a N (where 0 ≦ a ≦ 1) doped with n-type impurities such as Si and Ge. However, in the case of a light emitting element used for a light emitting diode, the formation of the n-type cladding layer 4 can be omitted.

The active layer 5 formed on the n-type cladding layer 4 is formed of a gallium nitride-based compound semiconductor having a band gap smaller than that of the n-type cladding layer 4. In particular, a gallium nitride-based compound containing indium semiconductor, ie _{In p Al q Ga 1-pq} N ( where,
0 <formed by p ≦ 1,0 ≦ q ≦ 1,0 < p + q ≦ 0), among which In _r Ga _1-r N (where, 0 <r <1) is preferably formed of a. (Hereinafter, in this specification, gallium nitride-based compound semiconductors represented by In _r Ga _1-r N or similarly with subscripts are simply referred to as InGa
Sometimes called N. The active layer 5 may be configured to obtain a desired emission wavelength by doping an n-type impurity and a p-type impurity simultaneously or by doping only one of them. It is particularly preferable to form the active layer 5 having good color purity and high luminous efficiency by using a layer having the above structure to form a quantum well structure from the viewpoint of improving luminous efficiency. When the active layer 5 has a quantum well structure, a single quantum well structure in which a well layer made of InGaN is sandwiched between barrier layers having a band gap larger than that of the well layer may be used. And n-type cladding layers formed on both sides of the substrate. Further, a multiple quantum well structure in which well layers and barrier layers are alternately stacked may be used.

On the active layer 5, a p-type cladding layer 6 is formed. The p-type cladding layer 6 is formed of a gallium nitride-based compound semiconductor having a band gap larger than the band gap of the active layer 5, and in particular, Al _b Ga _{1 -b} N doped with a p-type impurity such as Mg (however, 0 ≦ b ≦ 1)
It is preferable to be formed by. Usually, the p-type cladding layer 6
Is often formed at a growth temperature higher than the temperature suitable for growing the active layer 5 in order to form the crystal with good crystallinity.
For this reason, after the growth of the active layer 5, while the temperature is raised to the growth temperature of the p-type cladding layer 6, the active layer 5 is dissociated by constituent elements such as indium and nitrogen constituting the active layer 5.
The crystallinity may be deteriorated. Therefore, a part of the side of the p-type cladding layer 6 which is in contact with the active layer 5 is continuously grown while the temperature of the active layer 5 is raised after the growth, and the remaining part is continuously formed at the growth temperature of the p-type cladding layer 6. When the p-type clad layer 6 is grown, it is possible to effectively prevent the crystallinity of the active layer 5 from deteriorating. At this time, a part of the p-type cladding layer 6 grown while increasing the temperature is made of Al _c G
a _1-c N (where 0 ≦ c <1, c <b), particularly preferably GaN. This is because the function as a cladding layer formed in contact with the active layer 5 can be sufficiently achieved, and at the same time, the effect of preventing deterioration of crystallinity due to dissociation of constituent elements of the active layer 5 can be enhanced.

On the p-type cladding layer 6, a p-type contact layer 7 is formed. The p-type contact layer 7 is formed of a gallium nitride-based compound semiconductor doped with a p-type impurity. In particular, in order to reduce the contact resistance with the p-side electrode 9 formed on the surface of the p-type contact layer 7, In _d Ga _1-d N (0 ≦ d ≦
0).

Here, the semiconductor laminated structure 300 is formed in an n-side laminated structure between the active layer 5 and the substrate 1, and in this embodiment, in particular, the n-side electrode 8 is formed on the surface. The structure is formed between the formed n-type contact layer 3 a and the substrate 1.

FIG. 2 is a sectional view schematically showing a part of the gallium nitride-based compound semiconductor light emitting device according to the first embodiment of the present invention, and shows a layer structure from the n-type contact layer 3a to the active layer 5. Is shown. In the present embodiment, the semiconductor multilayer structure 300 includes the n-type contact layer 3a and the substrate 1
Is formed between.

The semiconductor multilayer structure 300 has an undoped G
AlG formed in contact with a first n-type layer 31 made of aN and a first n-type layer 32 and doped with an n-type impurity
and a second n-type layer made of aN.
In the present invention, the first n-type layer 31 is an undoped G layer.
It is essential that the second n-type layer be made of aN and be made of AlGaN doped with an n-type impurity such as Si or Ge.

By forming a semiconductor multilayer structure 300 in which a first n-type layer 31 made of undoped GaN and AlGaN doped with an n-type impurity are formed in the n-side layer structure, the semiconductor multilayer structure 300 is formed. Although it is not clear why the electrons move easily inside, it can be guessed as follows.

That is, in a gallium nitride-based compound semiconductor doped with an n-type impurity, like other group III-V compound semiconductors, the mobility of electrons in the n-type layer is determined by ionization of n It is considered that it is often greatly affected by scattering by the type impurities.

Here, as in the present invention, the first n-type GaN made of undoped GaN without doping n-type impurities is used.
When the semiconductor multilayer structure 300 is formed by joining the mold layer 31 and a second n-type layer 32 made of AlGaN doped with an n-type impurity, the second n-type layer 32 doped with the n-type impurity is formed. It is considered that the electrons generated by the ionization of the n-type impurity in the first N-type layer 31 are accumulated and also exist in the first n-type layer 31 having a smaller band gap than the second n-type layer 32. In undoped GaN, the number of ionized impurities that affect the mobility of electrons is much smaller than that of an n-type layer doped with an n-type impurity. It is much higher than the mold layer.

Accordingly, the second n-type layer 32 which is originally undoped and has a low electron concentration, is joined to the first n-type layer 31 and is doped with an n-type impurity and has a high electron concentration. It is considered that the number of electrons whose mobility has been increased by the supply of electrons from the substrate becomes very large, so that the electrons can easily move in the semiconductor multilayer structure 300 as a whole.

By these actions, the electrons injected from the n-side electrode 8 into the n-type contact layer 3b pass through the n-type contact layer 3b immediately below the n-side electrode 8 to form the semiconductor multilayer structure 30.
0 in the stacked structure of the first n-type layer 31 in which the mobility of electrons is increased and the second n-type layer 32 doped with n-type impurities, And injected into the active layer 5 from the semiconductor multilayer structure 300 via the n-type contact layer 3 b and the n-type cladding layer 4. As a result, in-plane uniform light emission is obtained from the active layer 5,
The luminous efficiency is improved, and electrons are easily moved in the n-side layer structure including the semiconductor multilayer structure 300, so that the series resistance in the n-side layer structure is reduced and the operating voltage can be reduced. Becomes

Here, when the n-side electrode is formed on the exposed n-type contact layer by removing a part of the p-type layer from the p-side by etching, the active layer is injected from the n-side electrode. The flow of electrons up to the injection into the n-side electrode tends to concentrate in a narrow region near the n-side electrode, and the electrons flow from directly below the n-side electrode through an n-type contact layer having a relatively high resistance in a plane. It proceeds in a direction perpendicular to the stacking direction and reaches a lower portion of the active layer that has not been removed by etching. For this reason, the series resistance in the plane direction of the n-type contact layer tends to increase. In addition, it tends to be difficult to reduce the series resistance when electrons injected from the n-side electrode move in the plane direction.

On the other hand, as in the present embodiment, by forming the semiconductor multilayer structure 300 below the n-type contact layer 3b, that is, between the n-type contact layer 3b and the substrate 1, the n-side electrode is formed. Electrons injected from 8 easily spread throughout the plane of the layer structure in the semiconductor multilayer structure 300, so that series resistance in the plane direction can be reduced. In this case, the distance between the surface of the n-type contact layer 3a where the n-side electrode 8 is formed and the semiconductor layer structure 300 is set to 0.0 by appropriately adjusting the etching depth from the p-side.
When the thickness is in the range of 1 μm to 0.3 μm, electrons can be easily supplied from the n-side electrode 8 to the semiconductor layer structure 300, so that the above-described effects can be easily obtained.

In the present embodiment, the semiconductor multilayer structure 300 is sequentially formed from the side in contact with the n-type contact layer 3a.
Although the first n-type layer 31 and the second n-type layer 32 are repeatedly laminated twice, the number of repetitions depends on the first n-type layer 31 and the second n-type layer 32. Although it depends on the film thickness, it is preferable that the thickness be in the range of 1 to 300 times. When the number of repetitions is increased to form a multilayer, it is preferable to appropriately reduce the film thickness and prevent defects or cracks from occurring in the layer structure, in that the production yield can be increased.

In this embodiment, the pair of the second n-type layer 32 and the first n-type layer 31 is laminated twice from the side closer to the substrate 1. Is a second n-type layer 32 doped with an n-type impurity, and further forms a third n-type layer made of undoped GaN in contact with the second n-type layer 32, The second n-type layer 32 and the n-type contact layer 3 on the side close to the substrate 1
The third n-type layer may be formed in contact with a. Electrons generated in the first second n-type layer 32 of the stack also exist in the third n-type layer formed in contact with the second n-type layer 32, and by the same effect as described above, this semiconductor stacked structure has This is because electrons are more likely to move inside.

In the present embodiment, the n-type contact layer 3a is preferably made of the same gallium nitride-based compound semiconductor as the n-type contact layer 3b, that is, GaN doped with Si to increase the electron concentration. However, in the case where the n-side electrode 8 does not contact the n-type contact layer 3a, the undoped G
It is also possible to use an aN or AlGaN layer as a base layer of a laminated structure of a gallium nitride-based compound semiconductor formed thereon.

(Embodiment 2) FIG. 3 is a sectional view showing the structure of a gallium nitride based compound semiconductor light emitting device according to a second embodiment of the present invention. The same members are shown.

In FIG. 3, an n-type contact layer 3a, a semiconductor multilayer structure 300, an n-type contact layer 3b, and an n-type clad layer 4 are formed on a substrate 1 with a buffer layer 2 interposed therebetween.
, An active layer 5, a p-type cladding layer 6, and a p-type contact layer 7 are sequentially stacked in the same manner as in the gallium nitride-based compound semiconductor light emitting device shown in FIG. On the surface of the p-type contact layer 7, a p-side electrode 9 is provided.
An n-side electrode 8 is provided on the exposed surface of the mold contact layer 3a.
Are formed.

The substrate 1, buffer layer 2, n-type contact layer 3a, semiconductor laminated structure 300, n-type contact layer 3b, n-type cladding layer 4, active layer 5, p-type cladding layer 6, p-type contact shown in FIG. The configurations of the layer 7, the p-side electrode 9, and the n-side electrode 8 are the same as those described with reference to FIG. 1 in the first embodiment, but the gallium nitride-based compound semiconductor light emitting device of the present embodiment The difference from the first embodiment is that the semiconductor multilayer structure 300 is formed between the active layer 5 and the n-type contact layer 3a on which the n-side electrode 8 is formed.

FIG. 4 is a sectional view showing a partial structure of a gallium nitride-based compound semiconductor light emitting device according to a second embodiment of the present invention, and shows a layer structure from an n-type contact layer 3a to an active layer 5. Is shown. As described above, the semiconductor multilayer structure 300 is formed between the n-type contact layer 3a and the active layer 5.

The semiconductor multilayer structure 300 is formed in contact with the first n-type layer 31 made of undoped GaN and the first n-type layer 32 from the side near the n-type contact layer 3a,
And a second n-type layer made of AlGaN doped with an n-type impurity. In the present invention,
The first n-type layer 31 is made of undoped GaN, and the second n-type layer is made of Al doped with an n-type impurity such as Si or Ge.
Indispensable to be made of GaN is described in the first embodiment.
The configuration is the same as that described above.

Also in this embodiment, undoped G
By forming a semiconductor multilayer structure 300 in which a first n-type layer 31 made of aN and AlGaN doped with an n-type impurity are stacked in the n-side layer structure, the semiconductor multilayer structure 300 is formed.
It is considered that the reason why electrons easily move among them is almost the same as the guess explained in the first embodiment.

Therefore, in the present embodiment, n
The electrons injected from the side electrode 8 into the n-type contact layer 3a are supplied to the semiconductor laminated structure 300 formed on the n-type contact layer 3a, and the first n-type layer 31 with increased electron mobility is provided. And a second n-type layer 32 doped with an n-type impurity, the layer structure is uniformly spread over the entire surface of the layer structure, and the n-type contact layer 3 b and the n-type It is implanted into the active layer 5 via the layer 4. As a result, in-plane uniform light emission is obtained from the active layer 5, the luminous efficiency is improved, and the semiconductor laminated structure 30
Since electrons easily move in the n-type layer including 0, the direct resistance in the n-type layer is reduced, and the operating voltage can be reduced.

The first n-type layer 31 and the second n-type layer 3
The number of repetitions and the film thickness of the lamination of No. 2 can be the same as the configuration of the first embodiment.

Also in the present embodiment, the first n
The last layer of the repetition of the lamination of the mold layer 31 and the second n-type layer 32, that is, the layer in contact with the n-type contact layer 3b is a second n-type layer 32 doped with an n-type impurity. However, a third n-type layer made of undoped GaN may be formed in contact with the second n-type layer 32.

Further, in this embodiment, similarly to FIG. 1 in the first embodiment, the n-type contact layer 3a is doped with the same gallium nitride-based compound semiconductor as the n-type contact layer 3b, that is, doped with Si to form an electron. Although GaN having a high concentration is used, n-type contact layer 3b has n
In the case where the side electrode 8 does not contact, the formation of the n-type contact layer 3b can be omitted.

(Embodiment 3) FIG. 5 is a sectional view showing the structure of a gallium nitride-based compound semiconductor light emitting device according to a third embodiment of the present invention. The same members are shown.

In FIG. 5, an n-type contact layer 3a, a semiconductor multilayer structure 300, an n-type contact layer 3b, and a semiconductor multilayer structure 3 are formed on a substrate 1 with a buffer layer 2 interposed therebetween.
01, n-type contact layer 3c, and n-type cladding layer 4
, An active layer 5, a p-type cladding layer 6, and a p-type contact layer 7 are sequentially stacked. A p-side electrode 9 is formed on the surface of the p-type contact layer 7, and an n-side electrode 8 is formed on the exposed surface of the n-type contact layer 3b. Here, the semiconductor multilayer structure 301 formed on the n-type contact layer 3b has the same configuration as the semiconductor multilayer structure 300 formed below the n-type contact layer 3b in the second embodiment.

The substrate 1, buffer layer 2, n-type contact layer 3a, semiconductor laminated structures 300 and 301 shown in FIG.
n-type contact layer 3b, n-type cladding layer 4, active layer 5,
The configurations of the p-type cladding layer 6, the p-type contact layer 7, the p-side electrode 9, and the n-side electrode 8 are the same as those described with reference to FIG. 1 or 2 in the first or second embodiment. However, the gallium nitride-based compound semiconductor light emitting device of the present embodiment is different from that of the first or second embodiment in that the semiconductor lamination structure 300
And 301 are formed between the n-type contact layer 3b on which the n-side electrode 8 is formed and the substrate 1 and between the n-type contact layer 3b and the active layer 5, respectively.

FIG. 6 is a sectional view showing a partial structure of a gallium nitride-based compound semiconductor light emitting device according to a third embodiment of the present invention, and shows a layer structure from an n-type contact layer 3a to an active layer 5. Is shown. As described above, the semiconductor stacked structures 300 and 301 are formed between the n-type contact layer 3b and the substrate 1 and between the n-type contact layer 3b and the active layer 5, respectively.

Each of the semiconductor stacked structures 300 and 301 has a first n-type layer 31 made of undoped GaN and a first n-type layer 3 from the side close to the n-type contact layer 3b.
2 and is doped with an n-type impurity.
and a second n-type layer made of lGaN. In the present invention, it is essential that the first n-type layer 31 be made of undoped GaN and the second n-type layer be made of AlGaN doped with an n-type impurity such as Si or Ge. The configuration is the same as that of the first embodiment.

Also in this embodiment, undoped G
By forming the semiconductor stacked structures 300 and 301 in which the first n-type layer 31 made of aN and AlGaN doped with the n-type impurity are stacked in the n-side layered structure, the semiconductor stacked structures 300 and 301 are formed. It is considered that the reason why electrons can easily move is almost the same as the guess explained in the first embodiment.

Therefore, in the present embodiment, n
Among the electrons injected from the side electrode 8 into the n-type contact layer 3b, the electrons going downward via the n-type contact layer 3b are supplied to the semiconductor laminated structure 300 formed below the n-type contact layer 3b, The n-type contact layer 3 is uniformly spread over the entire surface of the layer structure,
b, and is injected into the semiconductor multilayer structure 301 and upward through the n-type contact layer 3b.
01 together with the electrons injected into the semiconductor multilayer structure 3
01, the n-type contact layer 3
The active layer 5 is injected through the c-type and n-type cladding layers 4. As a result, uniform in-plane light emission is obtained from the active layer 5, the luminous efficiency is improved, and electrons easily move in the n-type layer including the semiconductor stacked structures 300 and 301, so that the n-side layer structure is formed. , The series resistance is reduced, and the operating voltage can be reduced.

The first n-type layer 31 and the second n-type layer 3
The number of repetitions and the film thickness of the lamination of No. 2 can be the same as the configuration of the first embodiment.

Also in this embodiment, the last layer in the repeated stacking of the first n-type layer 31 and the second n-type layer 32 from the side near the n-type contact layer 3b is an n-type impurity. The second n-type layer 32 doped with
Further, a third n-type layer made of undoped GaN may be formed in contact with the second n-type layer 32.

Further, in the present embodiment, n-type contact layer 3a and n-type contact layer 3c are formed of the same gallium nitride compound semiconductor as n-type contact layer 3b,
That is, GaN is doped with Si to increase the electron concentration. However, in the case where the n-side electrode 8 does not come into contact with the n-type contact layer 3a, as described in the first embodiment, Alternatively, the n-type contact layer 3a may be formed of undoped GaN or AlGaN, and may be used as a base layer of a laminated structure of a gallium nitride-based compound semiconductor formed thereon. In the case of a configuration in which 8 does not come into contact with each other, the formation of n-type contact layer 3c can be omitted as described in the second embodiment.

In the first to third embodiments, the surface of the n-type contact layer forming the n-side electrode 8 is
Although it is configured to be substantially parallel to the plane direction of the layer, the surface of the n-type contact layer is inclined, for example, from the n-type contact layer 3c to the n-type contact layer 3a in the third embodiment. Then, the p-type layer is removed by etching from the p-side, and an n-side electrode 8 is formed from the exposed n-type contact layer 3c to the n-type contact layer 3a. Electrons are directly injected from the n-side electrode 8 into the n-type contact layer 301, the n-type contact layer 3b, the semiconductor multilayer structure 300, and the n-type contact layer 3a. It is possible to increase.

According to the knowledge of the present inventors, the second n-type layer 32 constituting the semiconductor multilayer structures 300 and 301 is
It has been found that the electron concentration is desirably adjusted so as to be in the range of 4 × 10 ¹⁸ / cm ³ or more and 1 × 10 ²⁰ / cm ³ or less. If the electron concentration is lower than 4 × 10 ¹⁸ / cm ^3, it tends to be difficult to obtain a sufficient spread of electrons in the semiconductor multilayer structures 300 and 301. It is considered that this is because the amount of electrons accumulated in the first n-type layer 31 formed in contact with the second n-type layer 32 is reduced. On the other hand, if it exceeds 1 × 10 ²⁰ / cm ³ , the crystallinity of the second n-type layer 32 tends to deteriorate,
The crystallinity of the layered structure formed thereon also tends to deteriorate.

Further, the second n-type layer 32 has a thickness of 10
It is preferable that the particle diameter is adjusted in the range of nm to 100 nm. This is because when the thickness of the second n-type layer 32 is smaller than 10 nm, the amount of electrons that can be supplied to the first n-type layer 31 decreases. On the other hand, the thickness of the second n-type layer 32 that contributes to the supply of electrons to the first n-type layer 31 is generally considered to be up to 100 nm. It is not preferable because a portion not contributing to the supply of electrons to 31 increases.

Further, the first n-type layer 31 has a thickness of 1n.
Preferably, it is adjusted in the range of m to 100 nm. If the thickness of the first n-type layer 31 is smaller than 1 nm, it tends to be difficult to obtain a sufficient spread of electrons in the semiconductor multilayer structures 300 and 301. this is,
This is considered to be because it becomes difficult to accumulate the electrons supplied from the second n-type layer 32. On the other hand, the electrons supplied from the second n-type layer 32 are considered to be concentrated in the vicinity of the first n-type layer 31 in contact with the second n-type layer 32. It is considered that even if the thickness of the film 31 is excessively increased, it does not contribute to the spread of electrons. According to the findings of the present inventors, when the thickness is larger than 100 nm, the mobility of electrons increases and electrons easily spread in the layer structure, thereby reducing the in-plane series resistance in the n-side layer structure. Than the first n-type layer 31
Tend to increase as the series resistance increases when moving vertically across the.

(Embodiment 4) The structure of a gallium nitride-based compound semiconductor light emitting device according to the present embodiment is substantially the same as that of the first embodiment shown in FIG.
The gallium nitride based compound semiconductor light emitting device of the present embodiment is different from that of the above embodiment in that the semiconductor laminated structure 3
00, the second n-type layer 3 doped with an n-type impurity
No. 2 is that an impurity diffusion preventing region which is not doped with an n-type impurity and is undoped is provided in a layer on the side in contact with the first n-type layer 31. Hereinafter, the present embodiment will be described with reference to FIG.

FIG. 7 is a sectional view showing a partial structure of a gallium nitride-based compound semiconductor light emitting device according to a fourth embodiment of the present invention. The same reference numerals as in FIG. 1 denote the same members. Is shown.

In FIG. 7, a first n-type layer 31 made of undoped GaN is formed on one or both sides of a second n-type layer 32 made of Al _x Ga ₁ -xN doped with an n-type impurity. And in the second n-type layer 32,
A part of the side in contact with the first n-type layer 31 has undoped A
An impurity diffusion prevention region 34 of l _x Ga ₁ -xN is provided.

Here, the second n-type doped n-type impurity
The electrons generated by the ionization of the n-type impurity in the mold layer 32 form the first n-type layer formed in contact with the second n-type layer 32.
In the first n-type layer 31 in which the number of ionized impurities affecting the mobility of electrons is very small, the mobility of electrons is n-type. As described in the first embodiment, it is much higher than the n-type layer doped with impurities.

Therefore, in order to maintain high electron mobility in the first n-type layer 31, the second n-type layer 32
It is important to prevent the n-type impurity doped into the first n-type layer 31 from being mixed into the first n-type layer 31 by diffusion or the like.

Therefore, as shown in FIG. 7, in the second n-type layer 32 doped with the n-type impurity, a portion of the side in contact with the first n-type layer 31 has an impurity not doped with the n-type impurity. The provision of the diffusion prevention region 34 prevents a decrease in mobility due to the incorporation of an n-type impurity into the first n-type layer 31, and can maintain a high electron mobility in the first n-type layer 31. Become like This configuration corresponds to the second n-type layer 32
This is particularly useful when the n-type impurity is highly doped.

The layer thickness of the impurity diffusion prevention region 34 is 1 nm.
Preferably, it is adjusted to a range of 5 nm to 5 nm. 1n
When the thickness is smaller than m, the effect of preventing the n-type impurity from being mixed into the first n-type layer 31 is reduced. This is because supply of electrons to the layer 31 tends to be difficult.

The structure of the present embodiment is different from the semiconductor laminated structures 300 and 30 in the first to third embodiments.
1 can also be applied.

[0080]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific example of a method for manufacturing a gallium nitride based compound semiconductor light emitting device of the present invention will be described with reference to the drawings. The following examples mainly show a method for growing a gallium nitride-based compound semiconductor using a metal organic chemical vapor deposition method, but the growth method is not limited to this, and the molecular beam epitaxy method and the organic metal It is also possible to use a molecular beam epitaxy method or the like.

Example 1 In this example, a gallium nitride-based compound semiconductor light emitting device shown in FIG. 1 was manufactured.

First, a sapphire substrate 1 having a mirror-finished surface is placed on a substrate holder in a reaction tube, and then the surface temperature of the substrate 1 is maintained at 1100 ° C. for 10 minutes, and the substrate is heated while flowing hydrogen gas. As a result, cleaning was performed to remove dirt and moisture such as organic substances attached to the surface of the substrate 1.

Next, the surface temperature of the substrate 1 is lowered to 600 ° C., and a nitrogen gas as a main carrier gas, ammonia, and a TM containing trimethylaluminum (TMA) are used.
While flowing the carrier gas for A, the buffer layer 2 made of AlN was grown to a thickness of 25 nm.

Next, after stopping the carrier gas of TMA only and raising the temperature to 1050 ° C., while flowing nitrogen gas and hydrogen gas as the main carrier gas, a carrier gas for TMG containing trimethylgallium (TMG) was newly added. And Si
The n-type contact layer 3a made of Si-doped GaN was grown to a thickness of 1.5 μm by growing the substrate while flowing SiH4 (monosilane) gas as a source.

After growing and forming n-type contact layer 3a,
Next, the substrate temperature is maintained at 1050 ° C., and the semiconductor laminated structure
300 were grown. In forming the semiconductor multilayer structure 300,
First, nitrogen gas and hydrogen gas are used as main carrier gases.
While a new carrier gas for TMG and T
While flowing the carrier gas for MA and the SiH4 gas
Grown from Si and doped with Si_0.1Ga_0.9From N
A second n-type layer 32 was grown to a thickness of 30 nm.
The electron concentration of the second n-type layer 32 is about 6 × 10 ¹⁸/ Cm
^ThreeMet. Next, at the same substrate temperature, a new T
Growth while flowing a carrier gas for MG, and
The first n-type layer 31 made of GaN having a thickness of 20 nm
Grew up. Then, after this, the second n
The mold layer 32 and the first n-type layer 31 were repeatedly laminated. This
And the second n-type layer 32 and the first n-type layer 31
Semiconductor laminated structure 300 in which a pair of
Was completed.

After forming the semiconductor multilayer structure 300, the TM
The carrier gas for A is stopped, and the substrate temperature is kept at 105
At 0 ° C., a new carrier gas for TMG and S
The n-type contact layer 3b made of GaN doped with Si is grown to 0.5 μm
Grown in thickness.

After growing the n-type contact layer 3b, the carrier gas for TMG is stopped, and the substrate temperature is kept at 1050 ° C.
And a new carrier gas for TMG and TMA
An n-type cladding layer 4 made of Al _0.01 Ga _0.99 N doped with Si was grown to a thickness of 0.05 μm by flowing a carrier gas and a SiH 4 gas.

After growing the n-type cladding layer 4, the carrier gas for TMG, the carrier gas for TMA, and the SiH4 gas are stopped, and the substrate temperature is lowered to 750 ° C.
In the above method, a nitrogen gas is flowed as a main carrier gas, and a new carrier gas for TMG and a carrier gas for TMI are flowed while the active layer 5 having a single quantum well structure made of undoped In _0.4 Ga _0.6 N is formed to a thickness of 5 nm. Grown in thickness.

After the active layer 5 is grown, the carrier gas for TMI is stopped, and while the substrate temperature is raised to 1050 ° C. while flowing the carrier gas for TMG, undoped GaN is continuously grown to a thickness of 4 nm. When the substrate temperature reaches 1050 ° C., nitrogen gas and hydrogen gas as main carrier gases, a carrier gas for TMA, and M
A carrier gas for Cp ₂ Mg, which is a g source, is grown while flowing, and Mg-doped Al _0.15 Ga _0.85 N
Was grown to a thickness of 0.1 μm. Thereafter, the carrier gas for TMG and the carrier gas for TMG are stopped, the substrate temperature is kept at 1050 ° C., and the Mg-doped Al
Mg is _added to undoped GaN from _0.15 Ga _0.85 N.
Was diffused. Thus, Mg-doped G
A p-type cladding layer 6 made of aN and AlGaN doped with Mg was formed with a thickness of about 0.1 μm.

After forming the p-type cladding layer 6, the substrate temperature is set to 1
050 ° C. and a new carrier gas for TMG,
The p-type contact layer 7 made of GaN doped with Mg was grown to a thickness of 0.1 μm by flowing the carrier gas for Cp ₂ Mg while flowing the carrier gas.

After growing the p-type contact layer 7, the carrier gas for TMG and the carrier gas for Cp ₂ Mg are stopped.
The wafer was taken out of the reaction tube by cooling to about room temperature while flowing the main carrier gas and ammonia as they were.

Next, CV is applied on the surface of the p-type contact layer 7.
After depositing the SiO ₂ film by the method D, the film was patterned into a predetermined shape by photolithography to form an etching mask. Then, the p-type contact layer 7 and the p-type clad layer 6 are formed by a reactive ion etching method.
And a part of the active layer 5 and the n-type cladding layer 4 are about 0.55 μm
At a depth of n in the direction opposite to the stacking direction, and n
The surface of the mold contact layer 3b was exposed. Then, an n-side electrode 8 made of Al was formed by vapor deposition on the surface of the n-type contact layer 3b exposed by photolithography and vapor deposition. Further, a p-side electrode 9 made of Ni and Au was formed by vapor deposition on the surface of the p-type contact layer 7 in the same manner.

Thereafter, the back surface of the sapphire substrate 1 was polished to a thickness of about 100 μm, and separated into chips by scribing. Thus, the gallium nitride based compound semiconductor light emitting device shown in FIG. 1 was obtained.

After bonding the chip to the stem with the electrode forming side facing upward, the n-side electrode and the p-side electrode of the chip are connected to the respective electrodes on the stem with wires, and then resin-molded to produce a light emitting diode. did. When this light emitting diode was driven with a forward current of 20 mA, it emitted blue light with a peak emission wavelength of 480 nm. At this time, the light emission output was 1210 μW, and the forward operation voltage was 3.4 V.
Met.

(Embodiment 2) In this embodiment, the n-type contact layer 3a is 1.95 μm, and the n-type contact layer 3b is
Is formed with a thickness of 0.05 μm, and the semiconductor laminated structure 300 is formed.
The gallium nitride-based compound semiconductor light-emitting device shown in FIG. 3 was manufactured in the same manner as in Example 1 except that the order of lamination of the first n-type layer 31 and the second n-type layer 32 was reversed. did. Further, after that, a light emitting diode was manufactured in the same manner as in Example 1 and was driven with a forward current of 20 mA, and emitted blue light with a peak wavelength of 480 nm.
The light emission output at this time was 1180 μW, and the forward operating voltage was 3.5 V.

Example 3 In this example, the n-type contact layer 3a was formed to a thickness of 1.50 μm, the n-type contact layer 3b was formed to a thickness of 0.35 μm, and the n-type contact layer 3c was formed to a thickness of 0.05. The laminated structure 300 is the same as that of the first embodiment, the semiconductor laminated structure 301 is the same condition as the semiconductor laminated structure 300 of the second embodiment, and between the n-type contact layer 3a and the n-type contact layer 3b and the n-type. A gallium nitride-based compound semiconductor light emitting device shown in FIG. 5 was manufactured in the same manner as in Example 1 except that the light emitting device was formed between the contact layer 3b and the n-type contact layer 3c. Further, after that, a light emitting diode was manufactured in the same manner as in Example 1 and was driven with a forward current of 20 mA, and emitted blue light with a peak wavelength of 480 nm. At this time, the light emission output was 1290 μW, and the forward operation voltage was 3.3 V.

Comparative Example For comparison, a gallium nitride-based compound semiconductor light emitting device shown in FIG. 8 was manufactured.

Specifically, the n-type contact layer 43 is formed under the same conditions as those of the n-type contact layer 3a of
The n-type high-concentration layer 403 is formed of GaN doped with Si so as to have an electron concentration higher than that of the n-type contact layer 43, and the n-type cladding layer 44 is formed in the first embodiment. The n-type cladding layer 4 was formed under the same conditions. Then, the buffer layer 42, the active layer 45, the p-type clad layer 4
6, the formation of the p-type contact layer 47, the n-side electrode 48, and the p-side electrode 49 is performed by using the buffer layer 2,
Active layer 5, p-type cladding layer 6, p-type contact layer 7, n
The formation was performed under the same conditions as the formation of the side electrode 8 and the p-side electrode 9.
Using the gallium nitride-based compound semiconductor light-emitting device thus obtained, a light-emitting diode was fabricated in the same manner as in Example 1 and was driven with a forward current of 20 mA, and emitted blue light with a peak emission wavelength of 480 nm. However, the emission output at this time tended to decrease to 1020 μW, and the forward operating voltage was 3.7 V, which was higher than that of the light emitting diode of the above example.

[0099]

As described above, according to the present invention, since the luminous efficiency can be further improved and the operating voltage can be further reduced as compared with a gallium nitride-based compound semiconductor light emitting device having a conventional structure, Has an advantageous effect that it can be suitably applied to an outdoor display device and various light sources where improvement in visibility and reduction in power consumption are desired. Further, also in the case of using a laser diode, the efficiency of injecting electrons into the active layer is improved, so that there is obtained an advantageous effect that the luminous efficiency can be increased and the operating voltage can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a gallium nitride-based compound semiconductor light emitting device according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a partial structure of a gallium nitride-based compound semiconductor light emitting device according to the first embodiment of the present invention;

FIG. 3 is a sectional view showing the structure of a gallium nitride-based compound semiconductor light emitting device according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a partial structure of a gallium nitride-based compound semiconductor light emitting device according to a second embodiment of the present invention;

FIG. 5 is a sectional view showing the structure of a gallium nitride based compound semiconductor light emitting device according to a third embodiment of the present invention.

FIG. 6 is a sectional view showing a partial structure of a gallium nitride-based compound semiconductor light emitting device according to a third embodiment of the present invention;

FIG. 7 is a sectional view showing a partial structure of a gallium nitride based compound semiconductor light emitting device according to a fourth embodiment of the present invention.

FIG. 8 is a sectional view showing the structure of a conventional gallium nitride-based compound semiconductor light emitting device.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 buffer layer 3a, 3b, 3c n-type contact layer 4 n-type cladding layer 5 active layer 6 p-type cladding layer 7 p-type contact layer 8 n-side electrode 9 p-side electrode 31 first n-type layer 32 second N-type layer 33 Third n-type layer 34 Impurity diffusion prevention region 300, 301 Semiconductor laminated structure

Continued on the front page F term (reference) 5F041 CA34 CA40 CA58 CA91 CA99 CB36 5F073 AA51 AA52 AA61 AA89 CA02 CA07

Claims (9)

[Claims] 1. A gallium nitride-based compound semiconductor light emitting device having at least a substrate, an n-type contact layer made of a gallium nitride-based compound semiconductor, and an active layer, wherein a light-emitting device is provided between the n-type contact layer and the substrate. One or both of the active layer and the n-type contact layer includes a semiconductor multilayer structure made of a gallium nitride-based compound semiconductor; A gallium nitride-based compound semiconductor light emitting device, wherein the mobility is higher than the mobility of electrons in the plane direction in the n-type contact layer. 2. A gallium nitride-based compound semiconductor light emitting device having at least a substrate, an n-type contact layer made of a gallium nitride-based compound semiconductor, and an active layer, wherein a light-emitting device is provided between the n-type contact layer and the substrate. One or both of the active layer and the n-type contact layer includes a semiconductor multilayer structure made of a gallium nitride-based compound semiconductor, and the semiconductor multilayer structure is made of undoped GaN. An n-type layer and an A-type layer formed in contact with the first n-type layer and doped with an n-type impurity;
A gallium nitride-based compound semiconductor light emitting device comprising at least a second n-type layer made of l _x Ga _1-x N (where 0 ≦ x ≦ 1). 3. The semiconductor laminated structure according to claim 1, wherein said undoped Ga is
3. The gallium nitride according to claim 2, wherein the gallium nitride has a multilayer structure in which two or more pairs of a first n-type layer made of N and a second n-type layer doped with an n-type impurity are stacked. Based compound semiconductor light emitting device. 4. The semiconductor laminated structure according to claim 2, further comprising a third n-type layer made of undoped GaN formed in contact with said second n-type layer.
The gallium nitride-based compound semiconductor light-emitting device according to the above. 5. The second n-type layer has an electron concentration of 4 × 10
¹⁸ / cm ³ or more 1 × 10 ²⁰ / cm ³ or less in the range become so tuned gallium nitride according to any one of claims 2 4, characterized in that that compound semiconductor light-emitting device. 6. The second n-type layer has a thickness of 10 nm to 1 nm.
6. The gallium nitride-based compound semiconductor light emitting device according to claim 2, wherein the gallium nitride based compound semiconductor light emitting device is adjusted to a range of 00 nm. 7. The first n-type layer has a thickness of 1 nm to 10 nm.
7. The gallium nitride based compound semiconductor light emitting device according to claim 2, wherein the gallium nitride based compound semiconductor light emitting device is adjusted to a range of 0 nm. 8. An undoped Al _x Ga ₁ -xN (0 ≦ 0) layer on the side in contact with the first n-type layer and / or the third n-type layer. The gallium nitride-based compound semiconductor light emitting device according to any one of claims 2 to 7, wherein an impurity diffusion prevention region (x≤1) is provided in a layer shape. 9. The thickness of the impurity diffusion preventing region is 1 nm.
The gallium nitride-based compound semiconductor light emitting device according to claim 9, wherein the gallium nitride-based compound semiconductor light emitting device is adjusted to a range of from 5 to 5 nm.