JPH11168241A - Iii nitride semiconductor light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a III nitride semiconductor light emitting device which is capable of emitting light of short wavelength such as blue light to green light of excellent monochromaticity and high intensity. SOLUTION: A III nitride semiconductor light emitting device is equipped with a light emitting part 10 composed of an N-type barrier layer 1, a P-type barrier layer 3 both formed of III nitride semiconductor, and an N-type light emitting layer 2 of indium-containing III nitride semiconductor interposed between the layers 1 and 3, wherein an indium atom concentration transition region width in the barrier layer 1 of the same conductivity-type with the light emitting layer 2 is represented by Δtv , an indium atom concentration transition region width in the barrier layer 3 whose conductivity-type is opposite to that of the light emitting layer 3 is represented by Δtw , and the light emitting part 10 has an indium atom concentration distribution C where Δtv and Δtw are so set as to satisfy a formula, Δtv <Δtw .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light emitting layer made of an indium-containing group III nitride semiconductor or an indium-containing group III nitride between an n-type barrier layer made of a group III nitride semiconductor and a p-type barrier layer. The present invention relates to a group III nitride semiconductor light-emitting device including a light-emitting portion sandwiching a quantum well structure including a well layer as a light-emitting layer made of a semiconductor.

[0002]

2. Description of the Related Art III-nitride semiconductor light-emitting device Aluminum belonging to Group III of the periodic table (A
l), a compound of gallium (Ga), indium (In), and the like and nitrogen (N) which is a Group V has a so-called band gap, which is relatively large, but exhibits semiconductor properties. It is called a group III nitride semiconductor. These general formula _{Al x Ga y In z N (} 0 ≦ x, y, z ≦ 1, x +
y + z = 1) In addition to a group III nitride semiconductor containing only nitrogen as a group V element represented by y + z = 1), arsenic (As) and phosphorus (P) which are group V elements other than nitrogen are included as one constituent element. _{al x Ga y In z M 1} -a N a (0 ≦ x, y, z ≦ 1,
x + y + z = 1, 0 <a ≦ 1, M: group V element other than nitrogen) is also generally included in the group III nitride semiconductor. This group III nitride semiconductor is made of silicon carbide (Si
C) and a wide band gap (wide band gap) like II-VI compound semiconductors such as zinc selenide (ZnSe).
nd gap), which is used as a material for forming light-emitting elements such as light-emitting diodes (LEDs) and laser diodes (LDs) that emit short-wavelength visible light or ultraviolet light, and is particularly suitable for emitting visible short-wavelength light. A group III nitride semiconductor having a band gap is widely used as a material for forming a light emitting layer.

[0003] Group III Nitride Semiconductor Material Constituting Light Emitting Layer For example, an LED constituted by using a group III nitride semiconductor has various emission wavelengths ranging from green, blue-green, blue or purple to the ultraviolet band. Short-wavelength LEDs that have been realized. In addition, for example, an LD configured using a group III nitride semiconductor is being actively researched and developed for practical use of a blue LD.

[0004] In such a light emitting element, a functional layer called a light emitting layer or an active layer causes light emission.
A high-brightness pure green LE having a structure called a quantum well structure (Quantum Well: QW) and having a wavelength of 525 nm, which is an LED formed using a group III nitride.
D or blue-green L whose wavelength is about 490 nm
Each light emitting layer of an LED that outputs short-wavelength visible light, such as an ED or a blue LED having a wavelength of about 450 nm,
Gallium indium nitride mixed crystal _{(Ga c In 1-c N} : 0
Group III nitride semiconductors containing indium such as ≤c <1) (indium-containing group III nitride semiconductors) have been used (see Japanese Patent Publication No. 55-3834).

A gallium-indium mixed crystal is particularly preferably used as a light-emitting layer of a short-wavelength light-emitting element because the bandgap that gives short-wavelength light emission can be conveniently obtained by appropriately selecting the composition ratio of indium. Because. For example, a gallium indium nitride layer having an indium composition ratio of about 0.05 (5%) to about 0.10 (10%) is used as a light emitting layer of a light emitting element in a blue band having a wavelength of about 450 nm. (Appl. Phys. Le
tt. , 64 (13) (1994), 1687-168.
See page 9.) The indium composition ratio is about 0.15 to about 0.1.
A zinc (Zn) -doped gallium indium layer with a wavelength of about 490 nm is used as a light-emitting layer of a blue-green band light-emitting element having a wavelength of about 490 nm (J.
Crystal Growth, 145 (1994),
911-917).

C. Structure of Light Emitting Unit of Group III Nitride Light Emitting Element Taking an LED as an example, there are roughly three types of structures of a light emitting unit using gallium indium nitride as a light emitting layer. First, the same material pn between the n-type gallium indium nitride layer and the p-type gallium indium nitride
This is a so-called homojunction light-emitting portion composed of a junction (see Japanese Patent Application Laid-Open No. 3-203388). The second is a light emitting section having a single hetero (SH) structure (Japanese Patent Laid-Open No. 5-63).
No. 236).

The third is a light-emitting portion in which a gallium-indium nitride light-emitting layer is disposed between a p-type and an n-type group III nitride semiconductor layer forming a barrier layer such as a cladding layer (Japanese Patent Laid-Open No. Hei 6-1994). 209120). Here, the barrier layer generally means a thermal kinetic energy of electrons (about 0.26 e) at room temperature with respect to a semiconductor material forming the light emitting layer.
A semiconductor layer that acts as a barrier to the passage of carriers (electrons and holes) in order to generate a band offset exceeding V). A structure in which both sides of the light emitting layer are sandwiched between n-type and p-type group III nitride semiconductor barrier layers such as a cladding layer is called a pn junction type double hetero (DH) structure. The barrier layer composed of a semiconductor having a band gap larger than that of the light emitting layer, which sandwiches the light emitting layer, causes radiative recombination of electrons and holes that cause light emission in a limited region, that is, in the light emitting layer. This results in an operation that can be performed efficiently. The light emitting portion having the DH junction structure has an advantage that higher intensity light emission can be obtained as compared with the case of the above-described SH junction due to the effect of “confinement” of the carriers. For this reason,
Recently, other III materials such as gallium arsenide (GaAs) based materials
Gallium nitride-based L
Even in the ED, a DH structure type LED having a pn junction is predominant (see Japanese Patent Application Laid-Open No. 6-260682).

[0008] By the way, blue, blue-green that has been put to practical use
Taking a short-wavelength LED that emits color or green as an example,
The pad layer is usually made of aluminum nitride / gallium mixed crystal (Al_x
Ga _yN: 0 ≦ x, y ≦ 1, x + y = 1)
(JP-A-6-260283). Special
In addition, the lower cladding layer disposed below the light emitting layer has an n-type nitride layer.
There is an example composed of gallium arsenide (GaN) (Jpn.
J. Appl. Phys. ,32(1993), L8-
See page L11). On the other hand, the p-type upper cladding layer
Luminium-gallium mixed crystal (Al_xGa_yN; 0 ≦ x,
y ≦ 1, x + y = 1)
(See JP-A-6-268259).

The structure of the light-emitting portion can be roughly classified into three types as described above. In addition, a gallium-indium nitride layer provided as a light-emitting layer in a light-emitting portion having a homojunction, SH structure or DH structure is further provided. Quantum well (Q
W) structure (Jpn. J. Appl. Ph)
ys. , 21 (9) (1982), L574-L57
6. Phys. Rev .. , 40 (5) (1989),
3013-3020. reference).

More specifically, a thin layer of gallium nitride / indium mixed crystal is used as a well layer, and gallium nitride (Ga) is used.
N) or mixed crystal of aluminum nitride and gallium (Al _d G
a _1-d N: 0 <d ≦ 1) A single quantum well structure (Single QW: SQW) or a multiple quantum well structure (Multi QW: MQW) using a thin layer as a barrier layer (Japanese Patent Laid-Open No. 9-36430). Reference). The barrier layer in the QW structure has the same electric conductivity as that of the light emitting layer (well layer) in order to form a band structure that enables the formation of quantum levels of electrons in a rectangular (square) potential well (well layer). It is customary for it to consist of a semiconductor layer of the shape. Therefore, if the constitutional unit of the quantum well, that is, the constitution of the single quantum well is omitted from the electric conduction type, for example, the n-type barrier layer /
One example is a stacked configuration of an n-type well layer / n-type barrier layer. The MQW is obtained by repeatedly forming the structural units having such an electric conduction type lamination relationship to form a multilayer.

The present invention is directed to a light emitting layer sandwiched between p-type and n-type barrier layers, or the same electrical conductivity as a light emitting layer (well layer) as seen in a quantum well (QW) structure. Having a light emitting portion including a well layer forming a junction with a barrier layer having a rectangular shape
It is a light emitting element such as D or LD.

In recent years, in order to divert the advantages of a light emitting portion having a quantum well structure which provides an emission spectrum with excellent monochromaticity, a light emitting portion having a quantum well structure having a barrier layer and a well layer made of a group III nitride semiconductor has recently been developed. Many examples of gallium-indium nitride-based light-emitting elements provided have been reported. For example, JP-A-6-164055 and JP-A-6-2682
No. 57, JP-A-7-7223, JP-A-7-94784
No., and Japanese Unexamined Patent Publication No. 7-297476,
J. Vac. Sci. Technol. B, 8 (199
0), 316, Appl. Phys. Lett. ,
56 (1990), p. 1257; Appl. Ph
ys. 74 (1993), p. 3911; Ele
ctron. Mater. , 21 (1992), 437
Page, and the magazine 21 (1992), 609 pp., Jpn.
J. Appl. Phys. , 30 (Part 1) (1
991), p. 1924, Journal 34 (1995), L79
7, p. 34 (Part 2) (1995), L13
32 pages, Journal 34 (Part 2) (1995), L15
Page 17 and the same magazine 35 (1996), page L74, III
An example of a light emitting device having a quantum well structure composed of a group III nitride semiconductor is listed. In these conventional examples, a stacking relation or a bonding relation between a light emitting layer made of an indium-containing group III nitride semiconductor and a barrier layer sandwiching or joining the light emitting layer is exemplified.

D. Light emission mechanism of indium-containing group III nitride semiconductor Light emitting portion having a DH structure in which the light emitting layer is sandwiched by p-type and n-type barrier layers, or between the p-type and n-type barrier layers, the same electrical conductivity as the well layer Of III-nitride semiconductor light-emitting devices with a DH structure including a quantum well structure consisting of a junction with a barrier layer in the shape of a III-nitride semiconductor, and the technical trend for achieving higher output is unclear Is indium-containing II
The mechanism of light emission from group I nitride semiconductors is
This is because it is not always clear in the past. Recently, as an example for explaining the mechanism of light emission, a mechanism via transition of low-dimensional carriers due to generation of quantum dots or the like has been mentioned. In addition, the confinement of the indium-containing group III nitride semiconductor light emitting layer as the light emitting layer
The possibility of light emission through the quantum of the state is suggested. (Preliminary Lecture No. 1, Lecture No. 28a-
D-6, page 178).

However, the actual state of "confinement" of the carrier is unknown, and it is not clear what kind of band configuration is caused. It is unclear what distribution of carriers contributes to recombination causing light emission. Furthermore, light emission via a quantum level at a level lower than the "original" band edge has been proposed (Japanese Patent Laid-Open No. Hei 8-3165).
No. 28). However, it is unreasonable to assume that a quantum level is formed at an energy level lower than the “original” band edge level.

In summary, the conventional indium-containing III
The light emission provided by the light emitting portion having a group III nitride semiconductor as a light emitting layer is presumed to be caused by radiative recombination of localized quantized carriers. A convenient band structure (potential structure) for forming is not shown or specified.
In addition, since the region where carriers are localized according to the potential configuration is not shown or specified, the direction of the technical measure that further improves the light emission output of the group III nitride semiconductor light emitting device is uncertain. That is the current situation.

E. Expression of quantum level in light emitting layer Light emitting portion having a structure in which the light emitting layer is sandwiched by p-type and n-type barrier layers,
Alternatively, in any case of a light emitting portion including a quantum well structure in which a barrier layer of the same conductivity type as the well layer is joined to the well layer, conditions must be developed in order to develop a quantum level inside the light emitting layer. is necessary. One of the conditions is that the semiconductor layer to be bonded to the indium-containing group III nitride semiconductor light emitting layer needs to be selected from semiconductor materials sufficient to provide a potential well. For example, a superlattice categorized as Type I which develops a rectangular (square) potential well with the light-emitting layer as the center of symmetry in a quantum well structure provided in a conventional group III nitride semiconductor light-emitting device (the above-mentioned “semiconductor superlattice”). Lattice physics and applications ”(published by Baifukan Co., Ltd.),
(See page 2), it is necessary to form the barrier layer from a semiconductor material that satisfies the following equations (1) and (2). (Eg) _a <(Eg) _b ... (1) (Eg) _a + χ _a <(Eg) _b + χ _b ... (2) where (Eg) _{a is} a forbidden band of the light emitting layer. Width (Eg) _b : band gap of barrier layer χ _a : electron affinity of light emitting layer χ _b : electron affinity of barrier layer

F. Conditions for Stably Developing Quantum Levels in Symmetrical Rectangular Potential Well Structure As described above, the light emitting layer and the barrier layer are made of a group III nitride semiconductor material satisfying the above equations (1) and (2). The first condition is to form a quantum well structure using
Even if the first condition is satisfied, a quantum level of a desired energy level is not always developed. In forming a potential well sufficient to surely express a quantum level, a constituent element or a composition ratio of a constituent element is formed at a junction interface between a well layer (light emitting layer) and a barrier layer that causes an offset between the well layer and the well layer. Needs to change sharply.

One specific example in which a steep change of the constituent elements is required is a potential well system in which a light emitting layer (well layer) is formed from gallium indium nitride and a barrier layer is formed from a mixed crystal of aluminum nitride and gallium. Therefore, it is necessary to change the material at the atomic level from gallium indium nitride to aluminum gallium nitride mixed crystal at the junction interface between the well layer and the barrier layer. That is, indium (I
n) atoms are present only in the well layer, and aluminum (Al)
Ideally, atoms are present only in the barrier layer. However, in practice, elements constituting the light emitting layer invade into the barrier layer bonded thereto due to mutual diffusion of atoms through the bonding interface.

A simple problem when a steep concentration change of constituent elements cannot be obtained at the junction interface between the light emitting layer and the barrier layer is that the band change at the junction interface between the well layer and the barrier layer becomes slow. . The slow change of the band at the junction interface between the light emitting layer (well layer) and the barrier layer or the like causes an inadvertent expansion of the potential well width, and the quantum level formed therefrom is lower than the desired level. It will be reduced. This is a phenomenon generally recognized as "fluctuation" of the quantum level (see "Physics and Application of Semiconductor Superlattice" (published by Baifukan Co., Ltd., p. 227)). The "fluctuation" of the quantum level occurs not only when the potential changes slowly but also when the thickness of the well layer slightly changes from the intended value. In a light-emitting device having a quantum well structure that obtains light emission based on the transition between quantum levels in a cell, a change in the transition energy between the quantized carriers, that is, a “shift” from the intended wavelength of the light emission wavelength. It causes a consequent failure. Therefore,
In forming a quantum well structure having a symmetrical rectangular potential well structure as in the related art, it is necessary to make the concentration change of the constituent elements of the light emitting layer sharp at the junction interface with the barrier layers bonded on both sides of the light emitting layer. Required.

G. Conditions for Stably Developing Quantum Levels in Asymmetric Potential Well Configuration Examples of devices using quantum structures other than rectangular potential wells are not light-emitting elements, but include high mobility transistors (MODFET, TEGFET). Electronic devices (Appl. Phys. Lett., 69 (2
5) (1996), pp. 3872-3874). The carriers used for the operation of the MODFET are mainly electrons, and are low-dimensional electrons that behave two-dimensionally and are quantized in the potential well. However, the configuration of the potential well that provides the presence of quantized electrons that imparts high-speed operation to the MODFET is different from that of a symmetrical rectangular (square) potential well used in conventional light emitting device applications (Appl. Phys. Lett., 69 (23) (1
996), pages 3456-3458).

FIG. 15 is a diagram schematically showing a potential well structure in a laminated structure for MODFET use.
In the figure, the MODFET has an asymmetric potential well structure in a laminated portion composed of an electron transit layer (channel layer) S1 / spacer layer S2 / electron supply layer S3 (Appl. Phys. Lett., 69 ( 6)
(1996), pages 794-796).

In the region inside the electron transit layer S3 near the junction interface 510 with the spacer layer S2, portions 501 and 502 where the band sharply changes occur at the conduction band edge and the valence band edge. It has an asymmetric and non-rectangular potential configuration. In particular, the drop at the bent portion 503 of the band at the conduction band end is remarkable, and in the region near the junction interface 510, the level of the conduction band drops below the Fermi level F. In the low potential region where the conduction band is below the Fermi level F, the quantum levels 505a,
505b, 505c, 505d... Are formed, and carriers (electrons) are accumulated in the quantum levels 505a. These quantum levels 505a are formed in a region where the original conduction band of the semiconductor constituting the light emitting layer is bent. However, the quantum levels 505a are higher than the original conduction band. It is formed on the energy side.

The carrier distribution in the conventional symmetric rectangular potential well is compared with that in the conventional symmetric rectangular potential well structure provided in the light-emitting element. Is not distributed unevenly at one of the junction interfaces, but is distributed almost uniformly in the potential well as a whole, whereas in the asymmetric potential structure, the region near the specific interface in the junction interface That is, they are unevenly distributed in a specific region of the active layer, and both are clearly different in this point. And like the asymmetric potential well structure in the stacked structure for MODFET use,
In order to form a potential well at one junction interface, the change in the concentration of the constituent elements at the junction interface should be particularly sharp.

As described above, in a light emitting portion having a quantum well structure which causes radiative recombination of quantized carriers, regardless of a symmetric or asymmetric potential structure.
In forming a potential well for localizing or unevenly distributing carriers, the quantum level is obtained stably by acquiring the steepness of the constituent elements at the junction interface, rather than simply forming a laminated structure. Needs to be created in a specific area. In contrast, even in the light emitting portion of the conventional simple pn junction type DH structure, if the steepness at the junction interface between the light emitting layer and the p-type and n-type barrier layers is impaired, light In addition, "bleeding out" to another layer of the carrier occurs, which causes a problem that sufficient light and "confinement" of the carrier cannot be obtained.

[0025]

However, as described above, in order to more efficiently perform light emission based on radiative recombination of quantized carriers, the concentration of constituent elements at the junction interface with the light emitting layer is increased. Even if the change is to be steep, a group III nitride semiconductor light-emitting device must have a region where the carriers are unevenly distributed in the light-emitting layer, which is suitable for improving the light emission output and the color purity. Whether or not they should live has not yet been specified. Even better, if it is intended to obtain excellent monochromaticity with high light output, it is best to distribute carriers in any region depending on the electrical properties of the light emitting layer and to give any change to that region. Maybe it's not clear.

In other words, in the prior art, the mechanism of light emission from the indium-containing group III nitride semiconductor has not been sufficiently elucidated. The region in which carriers are to be unevenly distributed, which should be formed with the steepness of the concentration, is unclear. Therefore, when the light emitting device is configured, the emission intensity characteristics and the color purity (monochromaticity) characteristics cannot be sufficiently exhibited. Had problems.

The present invention has been proposed in view of the above,
It is an object of the present invention to provide a group III nitride semiconductor light emitting device capable of emitting short-wavelength light from a blue band to a green band with high intensity and excellent color purity (monochromaticity).

[0028]

In order to achieve the above-mentioned object, the present inventor has proposed a method for increasing the emission output, improving the color purity (monochromaticity), or improving the high-speed response by using electrons as carriers. The present inventors have found that it is effective to impart a change in the distribution mode with the degree of steepness of the concentration of indium atom, which is a constituent element of the light-emitting layer, depending on the electric conductivity type of the light-emitting layer. It is.

That is, in the present invention, the invention according to claim 1 is a light emitting layer comprising an indium-containing group III nitride semiconductor between a n-type barrier layer comprising a group III nitride semiconductor and a p-type barrier layer. With a light-emitting part holding the
In the group nitride semiconductor light emitting device, the transition region width Δt _V of the indium atom concentration on the side of the same electric conduction type barrier layer as that of the light emitting layer, and the indium atom on the side of the electric conduction type barrier layer opposite to the above light emitting layer Concentration transition area width Δ
The relationship between t _w and a light emitting unit having the concentration distribution of the indium atoms to Δt _w <Δt _V, characterized in that.

Further, according to a third aspect of the present invention, a light emitting layer made of an indium-containing group III nitride semiconductor is sandwiched between an n-type barrier layer made of a group III nitride semiconductor and a p-type barrier layer. A III-nitride semiconductor light-emitting device having a light-emitting portion comprising a light-emitting layer and an electrically conductive barrier layer of the same conductivity type as the light-emitting layer. A composition transition layer ΔS _V for reducing the indium atom concentration is disposed, and the light emitting layer is disposed between the light emitting layer and the barrier layer of an electric conductivity type opposite to the light emitting layer. It is characterized in that a composition transition layer ΔS _W for reducing the indium atom concentration is arranged, and the layer thickness of the composition transition layer ΔS _V is larger than the layer thickness of the composition transition layer ΔS _W.

Further, according to a fourth aspect of the present invention, a well layer as a light emitting layer made of an indium-containing group III nitride semiconductor is provided between an n-type barrier layer made of a group III nitride semiconductor and a p-type barrier layer. And a barrier layer made of an indium-containing group-III nitride semiconductor having a larger forbidden band width than the well layer, and a barrier layer having the same electrical conductivity type as the well layer. In the group III nitride semiconductor light emitting device provided with the light emitting portion sandwiching the above, the transition region width Δt _Va of the indium atom concentration on the barrier layer side of the same electric conductivity type as the quantum well structure, and the quantum well structure The relationship between the transition region width Δt _wa of the indium atom concentration on the side of the electric conduction type barrier layer opposite to the body is Δt _wa <Δt _Va
A light emitting portion having a concentration distribution of indium atoms.

According to a sixth aspect of the present invention, a well layer as a light emitting layer made of an indium-containing group III nitride semiconductor is provided between an n-type barrier layer made of a group III nitride semiconductor and a p-type barrier layer; Make the bandgap wider than the well layer
A group III nitride semiconductor light emitting device comprising a light emitting portion formed by sandwiching a quantum well structure composed of a group III nitride semiconductor and laminating a barrier layer having the same electric conductivity type as the well layer, When each of the termination layers of the quantum well structure is a well layer, the transition region width Δt of the indium atom concentration on the barrier layer side of the same electrical conductivity type as the quantum well structure.
And _Vb, a light emitting unit having the concentration distribution of the indium atoms and the relationship between the transition region width Delta] t _wb indium atomic concentration in the barrier layer side of the opposite electrical conductivity type Δt _wb <Δt _Vb and the quantum well structure When each of the termination layers of the quantum well structure is a barrier layer containing no indium, the transition region width Δt _Vc of the indium atom concentration on the termination layer side in contact with the barrier layer having the same electrical conductivity type as the well layer; The relationship between the transition region width Δt _wc of the indium atom concentration and the transition region width Δt _wc on the side of the termination layer in contact with the barrier layer of the opposite conductivity type is represented by Δt _wc <Δt _Vc
Wherein the light emitting section has a concentration distribution of indium atoms.

[0033]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram conceptually showing a light emitting portion in a group III nitride semiconductor light emitting device of the present invention. FIG. 1 (A) shows a laminated structure thereof, and FIG. 1 (B) shows a change in indium atom concentration. ing. In the figure, the light emitting portion 10 of the group III nitride semiconductor light emitting device of the present invention is shown.
Is configured such that a light emitting layer 2 made of an indium-containing group III nitride semiconductor is sandwiched between an n-type barrier layer 1 made of a group III nitride semiconductor and a p-type barrier layer 3. Light emitting layer 2
Is not particularly limited, but is described here as an n-type.

The light emitting layer 2 contains indium.
The group III nitride semiconductor, the general formula Al _x Ga _y In _z N
There is an aluminum-gallium-indium mixed crystal represented by (x + y + z = 1, 0 ≦ x, y <1, z ≠ 0). Also, phosphorus (P) or arsenic (As) formula containing nitrogen (N) except the Periodic Table of the Elements of Group V element (indicated by the symbol M.) As an element, such as Al _x Ga _y In _z N _a M _1-a
(X + y + z = 1, 0 ≦ x, y <1, z ≠ 0, 0 <a ≦
The mixed crystal represented by 1) is also an indium-containing group III nitride semiconductor.

As a configuration example of the light emitting layer 2, the layer thickness is 0.5
Some use an undoped gallium indium nitride layer having a thickness of μm as a single light emitting layer. In the light emitting layer 2 composed of such an undoped gallium / indium nitride thin layer, the half width of the emission spectrum can be narrowed, and the monochromaticity (color purity of light emission) can be improved. For this reason, recently, the thickness of the light emitting layer 2 made of undoped gallium indium nitride has been reduced to about 1 /
In some cases, it may be as thin as less than 10. Specifically, the layer thickness is set to about 10 nm, and the half width of the emission spectrum is set to about 1/2 or less (about 15 to 30 nm) of the related art.

On the other hand, the light emitting layer 2 doped with impurities is
The thickness of the layer doped with both zinc and silicon is
(Angstrom) gallium indium nitride
(Ga_0.85In_0.15N) may be used as the light emitting layer.
Specifically, the thickness of the silicon-doped layer is set to 10 ° to 0.
Gallium indium nitride (In)_xGa
_{1 -x}N: 0 <x <0.5) layer as a light-emitting layer, and zinc
Gas nitride having a doped layer thickness of 10 ° to 0.5 μm
Lium and indium (In_xGa_1-xN: 0 <x <0.
5) The layer is a light emitting layer.

As described above, either undoped or impurity-doped semiconductor material can be selected as the semiconductor material constituting the light-emitting layer 2. However, in the case where the layer doped with impurities is used as the light-emitting layer, at least uneven distribution of carriers is expected. In the region in the light emitting layer on the junction interface side, a high-purity crystal layer such as an undoped layer that does not intentionally add impurities that do not undergo impurity scattering is arranged. It is preferable that the light emitting layer is made of This is because the carrier travels in the light emitting layer toward a specific bonding interface and is selectively localized at the specific bonding interface. According to the gist of the present invention, the carrier travels in the light emitting layer due to scattering action or the like. This is because it is preferable to form a high-purity layer containing a small amount of unimpeded total impurities.

The internal crystal structure of the crystal layer constituting the light emitting layer 2 is not particularly limited. The above general formula Al _x Ga
In the case of a gallium-indium nitride mixed crystal included in the mixed crystal system represented by _y In _z N, even if the mixed crystal has a single-phase structure in which the indium composition is uniform, it is difficult to heat the mixed crystal. May have a multiphase structure composed of a plurality of phases having "fluctuations" in the indium composition (concentration). A typical example of a multi-phase structure includes a gallium nitride or a gallium indium nitride mixed crystal in which the indium concentration is relatively dilute, and a gallium indium nitride in which the indium concentration is higher than the constituent material of the mother phase. A multiphase structure composed of a plurality of phases having a dot-like microcrystal composed of a mixed crystal as a subordinate phase is exemplified. In the present invention, in particular, from the viewpoint of the intensity of emitted light, it is recommended that the light-emitting layer 2 be formed of an indium-containing group III nitride semiconductor material having a multiphase structure that results in stronger light emission. In the multi-phase structure, when the dependent phase exists in the light-emitting layer 2 at a spatially substantially uniform density, the dependent phase exists at the junction interface between the light-emitting layer 2 and another layer or in a region in the vicinity thereof. May be. For example, at an interface 4 between the indium-containing group III nitride semiconductor light-emitting layer 2 and the n-type barrier layer 1 such as a cladding layer, an island-like structure which seems to have developed with indium condensed in a specific region of the interface 4 as a nucleus. Alternatively, the spherical indium-containing dependent phase may exist in a concentrated manner. In the present invention, regardless of the distribution state of the dependent phases in the light emitting layer, any of them is regarded as a multi-phase structure.

The n-type barrier layer 1 and the p-type barrier layer 3 make the band offset on the conduction band side of the indium-containing group III nitride semiconductor material constituting the light emitting layer 2 by the thermal kinetic energy of electrons at room temperature. At least about 0.26 electron volts (eV) or more to make the band gap wider than the light emitting layer.
It is composed of a group III nitride semiconductor material. In particular, the band offset between the n-type light-emitting layer 2 and the electrically conductive p-type barrier layer 3 opposite to the n-type light-emitting layer 2 is caused by the thermal kinetic energy of electrons at room temperature (about 0.2
6 eV) and preferably about 0.3 eV or more.

In order to prevent sublimation, volatilization, or thermal deterioration of the light-emitting layer made of gallium indium nitride, which is easily sublimable, at a high temperature, a layer called an "evaporation preventing layer" may be provided on the light-emitting layer. However, such a layer is also treated as a kind of a barrier layer that functions as an “evaporation preventing layer”. For example, silicon (S) having an indium composition ratio of 0.2
i) Doped gallium indium nitride (Ga _0.8 In
Aluminum nitride / gallium mixed crystal (Al _0.4 Ga) with an aluminum composition ratio of 0.4 for the _0.2 N) light emitting layer
_0.6 If N) consisting bears "evaporation-preventing layer", Ga
_The band gap of _0.8 In _0.2 N at room temperature is about 2.9 eV,
That of Al _0.4 Ga _0.6 N is about 4.4 eV. Therefore, the difference between the band gaps is as large as about 1.5 eV. Even if the band offset ratio on the conduction band side in the gallium nitride / indium nitride heterojunction system is 69%, the offset amount on the conduction band side is 1%. It exceeds 0.0 eV, and such an “evaporation preventing layer” is also treated as a barrier layer.

In addition, if a conduction band band can be bent such that the conduction band edge of the light emitting layer falls below the Fermi level in a region near the junction interface with the electric conduction type barrier layer opposite to the light emitting layer, Still more preferred. Such band bending is observed in the stacked structure for MODFET application as shown in FIG. 15 described above, but the band bending in FIG. 15 is caused by the same electric conduction between the electron transit layer S1 and the spacer S2. At the n / n heterojunction interface of the n-type (actually n-type) semiconductor layer. On the other hand, in this embodiment, the bending of the band is developed at the p / n junction interface of the semiconductor having different electric conduction types.

The reason for this will be described with reference to FIG. 1 of this embodiment. In FIG. 1, the bending of the band is caused by bonding with the p-type barrier layer 3 having an electric conductivity type opposite to that of the n-type light emitting layer 2. The carrier (electrons) are formed at the interface 5 and accumulate carriers (electrons) in the portions. The accumulated electrons and holes are more supplied from the p-type barrier layer 3 by forward current injection (current injection). This is because it is convenient to cause recombination. In a light emitting layer in which a band bending that causes localization of electrons is generated at a junction interface 4 with the n-type barrier layer 1 side,
It is irrational that holes from the p-type barrier layer 3 reach the region where electrons are accumulated, even if the diffusion length of holes is considered. In other words, the emphasis on the steepness of the pn junction interface is that carriers that are unevenly distributed, for example, electrons, are present adjacent to holes whose diffusion length is extremely small as compared with electrons, thereby improving the coupling efficiency of radiative recombination. That is the aim.

As described above, the steepness of the bonding interface 5 needs to be particularly excellent in order to generate a band bending that causes the localization of electrons at the bonding interface 5. That is, in order to surely create a band offset at the junction interface 5 between the n-type light emitting layer 2 and the p-type barrier layer 3, the steepness of the junction interface 5 with the n-type barrier layer 3 must be good. It needs to be done.

Therefore, according to the present invention, as shown in FIG. 1B, the same electric conduction type barrier layer as the n-type light emitting layer 2 is used.
That is, the indium atom concentration N on the n-type barrier layer 1 side
A transition region width Delta] t _V of I, n-type light-emitting layer 2 opposite electrical conductivity type barrier layer side of the, i.e. the relationship between the transition region width Delta] t _w indium atomic concentration NI in the p-type barrier layer 3 side Δ
It is defined as t _w <Δt _V. The description is given below.

The indium present as a constituent element in the light emitting layer 2 is heated during the process of forming the light emitting layer 2 or in the process of laminating the p-type barrier layer 3 on the light emitting layer 2 so that the p-type barrier layer is heated. 3 or a transition diffuse into 1 internal n-type barrier layer to form a transition region width Δt _V, Δt _w. The transition region width Δt _V , Δ
_tw is the indium atom concentration NI indicated by the concentration distribution curve C, for example, 2 from the concentration Ro in the light emitting layer 2.
It refers to the distance from the starting point D1, D2 where the digit starts decreasing. The origins D1 and D2 correspond to the light emitting layer 2 and the barrier layers 1,
In the case where they correspond to the bonding interfaces 4 and 5 respectively, the distance from these bonding interfaces 4 and 5 indicates the transition region width. The transition region width Δt _V is the width at which the indium atom concentration NI transitions on the junction side with the n-type barrier layer 1, and the transition region width Δt _W transitions with the indium atom concentration NI on the junction side with the p-type barrier layer 3. Width. Further, the transition region widths Δt _V1 and Δt _W1 are such that the indium atom concentration NI is 2 times higher than the internal concentration Ro of the light emitting layer 2.
This is the depth (distance) required to reduce the order of magnitude. The reason _why Δt _V1 and Δtw ₁ are defined as the depth (distance) at which the indium concentration NI is reduced by two orders of magnitude from the average concentration Ro inside the light emitting layer 2 is that the indium concentration NI is lower than that in the light emitting layer 2. This is because if the concentration is reduced to about 1%, the concentration which no longer affects the physical properties of the layer in which it is present as a constituent element will hardly be reached.

In the present invention, as described above, the steepness at the junction interfaces 4 and 5 is represented by the diffusion distance of indium, which is a constituent element of the light emitting layer 2, into the n-type and p-type barrier layers. Then, the relationship of the composition steepness (transition region width of the indium atom concentration NI) at the junction interfaces 4 and 5 between the light emitting layer 2 and the barrier layers 1 and 3 is defined based on the electric conduction type of the light emitting layer 2, and p transition region width Δt _w (Δt _w1) at a joint interface 5 of the form barrier layer 3, it is an less than the transition region width Δt _V (Δt _V1) at a joint interface 4 between the n-type barrier layer 1.

In general, in order to achieve localization or uneven distribution of carriers at the junction interface with the light emitting layer, it is necessary to create a “clear” potential well structure effective for unevenly distributing carriers at the junction interface. The “clear” potential well structure refers to a structure having a potential configuration in which a band offset occurs rapidly at a junction interface. As described above, a sharp change in the concentration of a constituent element at the junction interface is required in order to develop a sharp band offset.

In the present invention, the steepness of the junction interfaces 4 and 5 between the light-emitting layer 2 and the barrier layers 1 and 3 is added because the junction interface 5 with the p-type barrier layer 3 having more excellent steepness is selectively provided. This is because the purpose is to make the carrier unevenly and preferentially distributed. In order to more efficiently achieve the uneven distribution of the carriers in the specific region, the present invention adopts a configuration in which the steepness of the indium concentration on the side of the junction interface 4 with the other n-type barrier layer 1 is deteriorated. From the viewpoint of the band configuration, the band offset at the junction interface 4 between the light emitting layer 2 and the n-type barrier layer 1 should be smaller than the band offset between the light emitting layer 2 and the p-type barrier layer 3. Features. This suppresses the situation in which carriers are trapped in a region near the junction interface 4 between the light emitting layer 2 and the n-type barrier layer 1, and at the same time, transports the carriers to the junction interface 5 between the light emitting layer 2 and the p-type barrier layer 3. This is to create a band (potential) configuration that can be selectively and preferentially unevenly distributed.

In this embodiment, the junction with the p-type barrier layer 3
Transition region width Δt at interface 5_V1To 250 nanometers (n
m) Then, the junction interface 4 with the n-type barrier layer 1
Transition region width at_w1And Δt_V1Δt_V1> Δ
t_w1Δt_w1Is also set to 250 nm or less. did
Therefore, regardless of the electrical conductivity type of the light emitting layer 2, the light emitting layer 2 is in contact with the light emitting layer 2.
Bonding interfaces 4 and 5 with n-type and p-type barrier layers 1 and 3 forming a combination
(Transition region width) is 250 nm or less in both cases.
I do. Transition region width Δt of indium concentration_V1, Δt _w1But
If the width (250 nm) is exceeded in the first place, even if the light emitting layer
Even if the band offset with 2 is sufficient for the barrier,
Bandwidth change at the junction interface due to slow change of the
Is not steep and therefore has a "clear" boundary
Offset does not appear sufficiently,
Has a "clear" energy boundary that provides a great barrier
This is because a rectangular potential structure cannot be created. I
Therefore, in the present invention, the contact between the light emitting layer 2 and the barrier layers 1 and 3 is made.
In the joint interfaces 4 and 5, an index indicating an interface steepness
The width of the transition region of the
Of the band that provides sufficient barrier action
We are trying to generate a fset.

Further, according to the present invention, under the condition that the steepness of the indium concentration at the junction interfaces 4 and 5 of both the light emitting layer 2 and the n-type and p-type barrier layers 1 and 3 is 250 nm or less,
steepness at the bonding interface 5 between the p-type barrier layer 3 (Δt _w, Δt
per _w1), 20 nm of Δt _V> Δt _w or Delta] t _V1> while maintaining the relationship between Delta] t _w1, besides the transition region width Delta] t _w1
It is preferable to define the following. The reason is that the light emitting layer 2
In addition, instead of forming a semiconductor layer having a larger band gap than the light emitting layer 2 to form a rectangular potential structure having a "clear" boundary, which is a barrier, a potential structure that enables uneven distribution of carriers is formed. This is because the carrier is selectively and preferentially localized in a region having a steep composition and having a steep composition at the junction interface 5 with the p-type barrier layer 3.

For example, according to the inventor's insight, the inflection of the band that causes the uneven distribution of carriers can be achieved by setting the transition region width Δtw ₁ to about 100 nm or less. However, for example, in order to develop band bending that causes the conduction band edge to fall below the Fermi level, further interface steepness is required, and the value is approximately 50%.
nm or less. Ideally, the transition region width Δtw ₁ is 0 (zero). The state where the transition region width Δtw ₁ = 0 means that the concentration of indium atoms is reduced by two digits at once at the junction interface 5 with the p-type barrier layer 3 without requiring a transition distance. At first glance, depending on the analysis method or the analysis conditions of the indium concentration, an analysis result that can be seen as being in a state close to Δt _w = 0 may be obtained. The case where Δt _w1 = 0 is rare. Even with a method of forming a junction interface that is excellent in obtaining steepness in the indium concentration at the interface, the best Δtw ₁ stably provided is about 10 nm in actual conditions. In consideration of such a point, the transition region width _{Δtw1 is set} to 20 nm or less.

The growth method of each group III nitride semiconductor layer constituting the light emitting section 10 includes an organic compound pyrolysis vapor deposition method (M
OCVD), molecular beam epitaxial growth (MBE)
Method) or a vapor phase growth method (VPE method) using a halide or hydride (hydride) as a raw material. The MOCVD method or the MBE method is often used from the conventional empirical insight on the basic achievement ability regarding the steepness of the interface.

When the pressures at the time of film formation in both methods are compared, MB
Gas source (gas-source) M using gaseous raw material (vaporized raw material) which is the method E or a combined method thereof
In the BE (GS-MBE) method and the like, film formation is performed in a high vacuum, whereas in the MOCVD method, atmospheric pressure (atmospheric pressure) is used.
Film formation can also be performed underneath. The convenience that the growth can be carried out at about atmospheric pressure, not in a vacuum where the progress of evaporation is promoted,
At present, the MOCVD method is exclusively used as a means for forming a group III nitride semiconductor film because it has an effect of suppressing the sublimation of an easily sublimable substance such as gallium indium or indium.

However, taking a commonly used MOCVD method as an example, a heterojunction interface having a desired steepness is not always formed by using the MOCVD method. It is necessary to create a device configuration and a growth environment of a part such as a growth reactor which takes into consideration various factors that hinder the steepening of the bonding interface. Causes of the so-called "flagging" of the interface, which impair the steepness of the heterojunction interface, include the configuration of piping systems such as valves, thermal convection of raw material gas in the growth reactor, and tubes of the growth reactor. There are mentioned adsorption and desorption of a raw material gas to a wall.
In particular, the formation of a group III nitride semiconductor layer is performed using gallium arsenide (G
aAs) and other III-V compound semiconductors,
It is usually carried out at a higher temperature, from about 800C to about 1200C. For this reason, thermal convection such as a source gas is generated more vigorously in the growth reactor, and a part of the retained gas remains as a deposit on the tube wall of the growth reactor. It is already known that such deposits hinder stable growth of the gallium nitride layer. In the case of a heterojunction made of a group III nitride semiconductor, where the steepness of the junction interface is required, suppression of the deposition of the deposit is an important factor.

FIG. 2 is a view showing an example of the configuration of a growth reactor which is devised for achieving steepness of a junction interface made of a group III nitride semiconductor. In the figure, a growth reactor 90 is a system in which a source gas or the like flows substantially parallel to the surface (deposited surface) of a substrate 100, and belongs to the category of a horizontal type reactor. Conventionally, a carrier (transport) gas composed of a source gas and an inert gas or the like is individually supplied to the surface of the substrate 100 from two directions, substantially vertical and substantially horizontal, in the vertical (vertical) direction and the horizontal (horizontal) direction. It is not a distribution system. The feature is that, in addition to the first flow path 91 and the second flow path 92 for introducing the source gas to the surface of the substrate 100, the inner wall 94 of the growth reaction furnace 90, particularly the region where the substrate 100 is placed and its This is because a dedicated sweep gas flow passage 93 for circulating a sweep gas for suppressing the deposition of deposits on the inner wall 94 located in the front area is provided. That is, as seen in a conventional horizontal growth reactor, a source gas of a Group V element such as nitrogen (N), gallium (Ga), aluminum (A
l) In addition to two flow paths 91 and 92 for separating and isolating the source gas of a group III element such as indium (In) from each other and introducing them into the furnace, supply of the sweep gas to the vicinity of the inner wall 94 is performed. The present invention is based on a three-channel system in which a desired sweep gas channel 93 is provided. By providing a sweep gas flow path 93 which is separated from the flow paths 91 and 92 of the raw material gas and having a flow path structure capable of introducing a sweep gas, an exceptional case for preventing the deposition of decomposition products due to the reaction on the inner wall 94 of the reactor is prevented. Effective. This has a remarkable effect in stably obtaining the steepness of the heterojunction interface.

It is desirable that the sweep gas flow channel 93 has a shape in which the sweep gas selectively flows so as to cover the inner wall 94 in the region above the substrate 100. That is, the substrate 100
It is preferred that the most remote channel be the sweep gas channel with the surface as the horizontal reference. Further, the raw material gas is surrounded in the center so as to suppress the diffusion of the raw material gas to the periphery, and the raw material gas or a decomposition product of the raw material gas is directly formed on the inner wall 94 of the reaction furnace in the region around the substrate 100. It is preferable to flow a sweep gas so that contact can be suppressed.

The gas species constituting the sweep gas is MO
In addition to hydrogen gas (H ₂ ) and nitrogen gas (N ₂ ) which are generally used as carrier gas in the CVD method, argon (A)
r) or another inert gas. Further, it is decomposed at a general film forming temperature of a group III nitride semiconductor, and is not likely to generate a metallic decomposition product such as gallium, aluminum or indium by the decomposition. Ammonia (NH
A mixed gas of H ₂ , N ₂ and Ar mixed with ₃ ) can also be used. In the growth reactor 90 having the configuration shown in FIG.
Various conditions such as the type, flow rate, composition, and mixing ratio of the gas flowing through each of the flow paths 91, 92, and 93 are compared with basic conditions such as a film forming temperature and a reaction pressure, and the resulting film uniformity is obtained. It may be appropriately determined in view of the above.

As can be understood from the above description, the steepness of the interface is affected by the growth operation method and growth conditions, and also by the structure of the growth apparatus itself. Of course, the temperature dependence of the diffusion characteristics of indium also affects the steepness of the interface. Against this background, there are the following three examples of techniques for controlling the steepness of the interface.

(1) A difference is generated in the resulting steepness of the interface.
Δt using a tricky growth system_V1> Δt _w1Achieve a relationship
Technique. Use a growth system that results in inferior interface steepness compared to the other.
To form an interface 4 with the n-type barrier layer 1. Afterwards
After growing the optical layer 2, the growth system is made to have better interface steepness.
Change to a growth system that gives Depending on the system, on the light emitting layer 2
P-type barrier layer 3 and Δt_V1> Δt_w1The world that holds the relationship
It is deposited with surface steepness.

(2) A method of achieving the relationship of Δt _V1 > Δtw ₁ by utilizing the thermal behavior of indium, particularly the temperature dependence of the amount of indium incorporated into the gallium nitride crystal. Gallium nitride based crystal, for example, gallium nitride (GaN)
This method utilizes the characteristic that the amount of indium incorporated into the crystal decreases when the temperature is high, and increases when the amount is low. When depositing the light emitting layer 2 on the n-type barrier layer 1,
At the initial stage of the growth of the light emitting layer 2, the interface is formed while the growth temperature is gradually lowered over time. After the n-type barrier layer 1 formed at a growth temperature higher than that of the light-emitting layer 2 is first formed, the growth temperature is lowered to a temperature suitable for that of the light-emitting layer 2. Is allowed to flow into the growth system, and the formation of the junction interface 4 with the n-type barrier layer 1 is completed when the temperature reaches the appropriate temperature or layer thickness. As a result, a junction interface 4 where the indium atom concentration is gradually increased from the n-type barrier layer 1 toward the inside of the light emitting layer 2 is obtained.

(3) A method of separately supplying an indium raw material through a piping system exhibiting different performances with respect to the required steepness of the interface, thereby achieving the relationship of Δt _V1 > Δtw ₁ . For example, there is a method of using a growth system including a piping system that provides excellent steepness with respect to a supply system of an indium raw material, and a piping system that includes a large amount of dead space in the piping system. When growing the light emitting layer 2 on the n-type barrier layer 1, an indium raw material is supplied to the growth system through a piping system including many dead spaces (residence spaces). Conversely, when depositing the p-type barrier layer 3 on the light emitting layer 2, an indium raw material is supplied via a piping system that provides steepness. As a result, a relationship of Δt _V1 > Δtw ₁ is obtained.

In order to ensure the steepness of the junction interfaces 4 and 5 of the light emitting layer 2 with the barrier layers 1 and 3, the transition region width Δt _{V1 is set} to 250 nm or less and the transition region width Δt _Even when the condition for surely providing the interface steepness to set _w1 to 20 nm or less is set, Δt _V1 and Δt _w1 should be kept within a range satisfying the specification of the present invention due to an unexpected situation.
May fluctuate. As a simple example, the light emitting unit 1
The liquid material or the sublimable material of the Group III element is bubbling (foaming) or the flow rate of the accompanying gas is temporarily fluctuated when the raw material type is changed due to the difference in the constituent elements of each layer constituting 0. Alternatively, the steepness (transition region width) of the bonding interfaces 4 and 5 may fluctuate due to unexpected circumstances such as the fluctuation amount is not constant. As one means for avoiding such instability, Δt _V1 and Δt _w1
A method for arranging a composition transition layer having a gradient in indium concentration that satisfies the above requirement is presented.

For example, the transition region width Δt _V1 at the junction interface 4 between the light emitting layer 2 and the n-type barrier layer 1 is set to be substantially constant at 100 nm, and if a stable composition gradient is desired, 100
What is necessary is just to provide a composition transition layer with a layer thickness of nm and a gradient that reduces the indium atom concentration by two orders of magnitude. in this case,
The indium concentration has a gradient so as to increase from the n-type barrier layer 1 toward the light emitting layer 2 side. When such a composition gradient is intentionally applied, an operation for gradually changing the flow rate of the raw material of the group III element over time is performed, so that a prominent or reverse distribution of the indium concentration distribution occurs. Can be suppressed.

On the other hand, stabilization of the steepness at the junction interface 5 with the p-type barrier layer 3 is also achieved by the same means. That is, a composition transition layer having a layer thickness of 20 nm and reducing the concentration of indium atoms by two digits may be provided between the light emitting layer 2 and the p-type barrier layer. The indium concentration is determined from the light emitting layer 2 side to the p-type barrier layer 3.
It shall be graded so as to decrease towards the side. The preferred range of the transition region width Δtw ₁ is 20 nm in the first place. When such a composition gradient is provided, an operation of instantaneously changing the flow rate of the group III element raw material in a pulsed manner is performed.

The mechanical thickness of the composition transition layer and the width of the transition region
Δt_V(Δt_V1) Or Δt_w(Δt_w1) Is exactly one
It is common not to do it. Usually, the thickness of the composition transition layer
Is the transition region width Δt_V(Δt_V1) Or Δt_w(Δt
_w1It is exclusively larger. Indium
By the time it reaches a certain concentration, even if it has excellent steepness,
Even if the piping system is connected, indium atoms are
For reasons related to the crystal growth mechanism such as the rate of crystal growth,
The mechanical thickness of the composition transition layer is the transition region width Δt _V(Δt
_V1) Or Δt_w(Δt_w1) Is usually larger
You.

FIG. 3 is a diagram showing a case where a composition transition layer is provided in the light emitting section. In the figure, the composition transition layers 7 and 8 are formed in the light emitting portion 10s by using the above-described method. That is, the composition transition layer 7 for reducing the indium atom concentration in the light emitting layer 2 from the light emitting layer 2 toward the barrier layer 1 is formed between the light emitting layer 2 and the n-type barrier layer 1 in the light emitting section 10 s. And
Between the light emitting layer 2 and the p-type barrier layer 3, a composition transition layer 8 for reducing the indium atom concentration in the light emitting layer 2 is formed from the light emitting layer 2 toward the barrier layer 3. In the light emitting section 10s, the layer thickness of the composition transition layer 7 is formed to be larger than the layer thickness of the composition transition layer 8, and, for example, the light emitting layer 2 to the n-type barrier layer 1
The thickness of the composition transition layer 7 for reducing the indium atom concentration in the light emitting layer 2 by two orders of magnitude toward 250 nm or less, and the indium atom concentration in the light emitting layer 2 from the light emitting layer 2 toward the p-type barrier layer 3 by two orders of magnitude The thickness of the composition transition layer 8 to be reduced is formed to be 20 nm or less.

In determining the steepness of the junction interface based on the distribution state of the indium atom concentration, the steepness is determined, for example, by the concentration distribution of indium atoms in the depth direction by secondary ion mass spectrometry, a so-called depth profile (depth profile).
th profile), and is constantly measured. In addition, steepness can also be evaluated from elemental analysis in the depth direction by physical analysis such as Auger electron spectroscopy.

Other constituent elements than indium, for example,
In principle, the steepness of the interface can be measured from the distribution of the concentration of gallium (Ga) or aluminum (Al) atoms. However, in a group III nitride semiconductor light emitting device,
Since each layer of the light emitting portion is usually composed of a group III nitride semiconductor layer containing gallium as a constituent element, a sharp concentration change is clearly observed on the gallium depth profile at the junction interface. In some cases, the method of evaluating the steepness of the interface based on the atomic concentration distribution of gallium lacks accuracy. On the other hand, for example, in a light emitting portion having a structure in which gallium indium nitride is used as a light emitting layer and aluminum nitride / gallium mixed crystals are arranged as barrier layers on both sides of the light emitting layer, a steep junction interface is formed from the concentration distribution of aluminum atoms. You can also know the gender. The steepness of the interface determined from the concentration distribution of aluminum atoms is usually
It is almost the same as compared with that measured from the distribution state of the indium atom concentration. That is, the transition region width of the indium atom concentration can be examined instead of the aluminum atom concentration.

[0069] Further, the wedge using a transmission electron microscope (TEM) (wedge) TEM, or CAT method (C omposition A nalysis by
T hickness-fringe) (Akira Tonomura ed.,
"Electron microscope technology" (August 31, 1989, Maruzen Co., Ltd.)
Issue), page 83), it is possible to judge "slack" at the joint interface although it is semi-quantitative. In the CAT method, it is required that the end face of a sample to be provided is particularly flat, and it is desirable that the sample has a flat and smooth end face exposed by opening a wall or the like. According to the wedge TEM, it is possible to know the pattern of the change in the composition at the interface from the lattice image of the region near the thinned bonding interface. For example, a change in the composition in the vicinity of the interface can be known from a change in the lattice spacing as the distance from the bonding interface increases. In the case of a TEM provided with an EPMA device capable of identifying an element from the characteristic X-ray wavelength and intensity and analyzing the concentration of the element, it depends on the diameter of an electron beam (beam) irradiating the subject, but the vicinity of the bonding interface The distribution of element concentration in a small region of several nm to several tens nm can be investigated.

The presence or absence of unevenly distributed carriers is determined by the method of Shubnikov-de Haas:
It can be investigated from the measurement of the oscillation of the magnetoresistance due to the SdH) effect. In particular, from the appearance of the Landau level in the SdH oscillation of the magnetoresistance when the direction of the magnetic field is perpendicular to the bonding interface (test object), it is possible to know the presence of localized low-dimensional (two-dimensional) carriers from the appearance of the Landau level. it can. Therefore, whether or not the carrier concentration is appropriate may be determined based on the carrier surface density of the light emitting layer, that is, the sheet carrier concentration. The sheet carrier concentration of the indium-containing group III nitride semiconductor layer to be used as the light emitting layer is preferably about 1 × 10 ¹¹ cm ⁻² or more and about 5 × 10 ¹³ cm ⁻² or less. The reason is as follows.

There is a limit to the amount of carriers that can accumulate in a given “depth” potential well. When a state in which a large amount of carriers exceeds the density of states allowed in the formed quantum level is present, the amount of carriers that deviate from the potential well and exhibit normal three-dimensional behavior also increases. . That is, the carriers having a quantized low-dimensional behavior that provides a high-speed operation of the element are the other three.
The proportion occupying the amount of dimensional carriers is reduced. Therefore, carriers that behave three-dimensionally predominantly exist inside the light emitting layer, which hinders clear manifestation of excellent device characteristics based on the quantum effect. On the other hand, if the amount of carriers accumulated in the potential well is not enough to satisfy the formed quantum level, the ratio of the quantized low-dimensional carriers to the three-dimensional carriers is small. Become. Therefore, it becomes difficult to express the features of the quantum device. And the above 1 × 10 ¹¹ cm ^-2
As described above, in the light emitting layer having a low sheet carrier concentration outside the range of 5 × 10 ¹³ cm ⁻² or less, although quantized carriers exist, the quantized carriers are three-dimensional bulk non-quantum. However, since the ratio of the carrier to the reduced carrier decreases, the excellent emission characteristics due to the recombination of the quantized carrier cannot be sufficiently exhibited. Since the specific carriers are dominant, the unique excellent light-emitting characteristics provided by the low-dimensional carriers such as the high-speed response of light emission are not sufficiently exhibited.

[0072] referred to the present invention the transition region width Δt _w (Δt _w1)
Not more than the transition region width Δt _V (Δt _V1 ) is applied not only to a light emitting portion having a DH structure in which one light emitting layer is sandwiched between p-type and n-type barrier layers, but also to a light emitting layer formed as a well layer. The present invention is also applied to a light emitting portion having a so-called DH structure including a single or multiple quantum well structure including a junction between the well layer and a barrier layer of the same electrical conductivity type as the light emitting layer. Even when the light-emitting portion includes a single or multiple quantum well structure, the present invention provides a steep interface between the quantum well structure and the p-type and n-type barrier layers sandwiching the structure. Follow the prescribed relationship. The details will be described below with reference to FIGS.
This will be described with reference to FIG.

FIG. 4 is a diagram showing a first configuration example in which the present invention is applied to a multiple quantum well structure. FIG. 4A shows the laminated structure, and FIG. Changes are shown respectively. In the figure, the same components as those of the above-described embodiment (FIG. 1) are denoted by the same reference numerals, and description thereof will be omitted.

The light emitting section 11 in the first configuration example includes:
A quantum well structure 21 is sandwiched between an n-type barrier layer 1 and a p-type barrier layer 3 made of a group III nitride semiconductor. This quantum well structure 21 has an indium-containing II
Group I nitride semiconductors (eg undoped gallium nitride
N-type well layer 21 as a light emitting layer made of indium)
2 and two barrier layers 21 sandwiching the well layer 212
1 and 213. Barrier layers 211 and 21
Numeral 3 is made of an indium-containing group III nitride semiconductor having a larger band gap than the well layer 212 and has the same n-type conductivity as the well layer 212.

As described above, the termination layers of the quantum well structure 21 are the barrier layers 211 and 213
In the configuration example 1 in which 1,213 contains indium, the difference in the composition steepness at the bonding interface according to the present invention is as follows.
As shown in FIG. 4B, it is established between the barrier layers 211 and 213 and the barrier layers 1 and 3. That is, transition region width Δt _va of indium atom concentration NI at junction interface 41 between n-type barrier layer 1 and barrier layer 211 and transition of indium atom concentration NI at junction interface 51 between p-type barrier layer 3 and barrier layer 213. The relationship with the region width Δt _wa is defined as Δt _wa <Δ
Defined as t _Va . Thereby, the carrier is made to have p conductivity opposite to that of the quantum structure 21 (well layer 212).
It can be localized at the junction interface 51 with the shaped barrier layer 3.

FIG. 5 is a diagram showing a second configuration example in which the present invention is applied to a multiple quantum well structure. FIG. 5 (A) shows the laminated structure, and FIG. Changes are shown respectively. In the figure, the same components as those of the above-described embodiment (FIG. 1) are denoted by the same reference numerals, and description thereof will be omitted.

The light emitting section 12 in the second configuration example includes:
A quantum well structure 22 is sandwiched between an n-type barrier layer 1 and a p-type barrier layer 3 made of a group III nitride semiconductor. This quantum well structure 22 has an indium-containing II
Group I nitride semiconductors (eg undoped gallium nitride
Two n-type well layers 221 and 223 as light emitting layers made of indium) are used as termination layers, and the two well layers 22
A barrier layer 222 is arranged between the first and second 223. The barrier layer 222 is made of a group III nitride semiconductor having a larger band gap than the well layers 221 and 223, and has the same n-type conductivity as the well layers 221 and 223. I have.

As described above, in the configuration example 2 in which the termination layers of the quantum well structure 22 are the well layers 221 and 223, the difference in the composition steepness at the junction interface according to the present invention is as shown in FIG.
As shown in FIG. 2B, it is established between the well layers 221 and 223 and the barrier layers 1 and 3. That is, the transition region width Δt _vb of the indium atom concentration NI at the junction interface 42 between the n-type barrier layer 1 and the well layer 221 and the indium atom concentration _Nt at the junction interface 52 between the p-type barrier layer 3 and the well layer 223.
The relationship between the transition region width Delta] t _wb of I, is defined as Δt _wb <Δt _Vb. Thereby, the carrier is connected to the p-barrier layer 3, which has an electric conductivity type opposite to that of the quantum structure 22 in particular, at the junction interface 52.
Can be unevenly distributed.

FIG. 6 is a diagram showing a third configuration example in which the present invention is applied to a multiple quantum well structure. FIG. 6 (A) shows the laminated structure, and FIG. Changes are shown respectively. In the figure, the same components as those of the above-described embodiment (FIG. 1) are denoted by the same reference numerals, and description thereof will be omitted.

The light emitting section 13 in the third configuration example includes:
A quantum well structure 23 is sandwiched between an n-type barrier layer 1 and a p-type barrier layer 3 made of a group III nitride semiconductor. This quantum well structure 23 has an indium-containing II
Group I nitride semiconductors (eg undoped gallium nitride
N-type well layer 23 as a light emitting layer made of indium)
2 and two barrier layers 23 sandwiching the well layer 232
1,233. Barrier layers 231 and 23
Numeral 3 is made of a group III nitride semiconductor containing no indium and having a larger band gap than the well layer 232, and has the same n-type conductivity as the well layer 232.

As described above, the termination layers of the quantum well structure 23 are the barrier layers 231 and 233,
In this configuration example 3 in which 1,233 does not contain indium,
The difference in the composition steepness at the bonding interface according to the present invention is shown in FIG.
As shown in (B), the well layer 232 and the barrier layers 231 and 231 are formed.
233. That is, the transition region width Δt _vc of the indium atom concentration NI at the junction interface 43 between the termination layer (barrier layer) 231 in contact with the n-type barrier layer 1 and the well layer 232, and the termination layer (barrier layer) in contact with the p-type barrier layer 3 )
The relationship between the transition region width Δt _wc of the indium atom concentration NI at the junction interface 53 between the 233 and the well layer 232 is represented by Δt
_{Define wc} <Δt _Vc . Thereby, the carriers can be localized at the junction interface 53 with the barrier layer 233 which is in contact with the p-type barrier layer 3 whose electric conductivity type is opposite to that of the well layer 232.

As described above, according to the present invention, the mechanism of light emission from the indium-containing group III nitride semiconductor is sufficiently elucidated, and the indium atom concentration at the junction interface between the light emitting layer in the light emitting portion and the barrier layer joined thereto is reduced. By providing a difference in the steepening, carriers can be selectively and preferentially localized on the barrier layer side having the opposite electrical conductivity type to the light emitting layer. Therefore, it is possible to promote the flow and traveling of the carrier toward one of the bonding interfaces, and it is possible to effectively perform the recombination of holes and electrons. The color purity (monochromaticity) characteristics can be sufficiently exhibited, and short-wavelength light from the blue band to the green band can be emitted with high intensity and excellent color purity (monochromaticity).

In the above embodiment, the electric conduction type of each light-emitting layer (2, 212, 221, 223, 232) is n-type, and the steep transition region width is set closer to the junction interface with the p-type barrier layer. Although the carrier is unevenly distributed on the junction interface side, the electric conduction type of the light emitting layer does not need to be particularly limited. For example, the light emitting layer is p-type and the junction interface with the n-type barrier layer is steeper. It is also possible to form such that the transition region has an appropriate width and carriers are localized on the bonding interface side.

Next, the group III nitride semiconductor light emitting device of the present invention will be described with reference to more specific examples.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) The present invention relates to a method of forming an n-type light emitting layer made of undoped gallium indium nitride by using a p-type barrier layer made of a mixed crystal of aluminum gallium nitride and an n-type barrier layer made of gallium nitride. A light emitting diode (LE) having a heterojunction structure including a pn junction and sandwiched between
The case where the method is applied to D) will be described. Each constituent layer of the laminated structure for LED use is a general normal pressure (atmospheric pressure)
Utilizing a MOCVD growth apparatus of the type, the layers were sequentially formed on the substrate by the following procedure.

FIG. 7 is a view showing a laminated structure according to the first embodiment of the present invention. In the figure, a laminated structure 10a is
It is configured to be laminated on the substrate 100. The substrate 100 has a diameter of about 2 inches (about 50 mm in diameter) and a thickness of about 90
(0001) (c-plane) -sapphire (α)
-Al ₂ O ₃ single crystal) was used. The above-described MOC is used for depositing each constituent layer of the laminated structure 10a on the substrate 100.
A VD growth reactor 90 (FIG. 2) was utilized. The crystal substrate 100 was placed substantially horizontally on a high-purity graphite susceptor 99 in a reaction furnace 90.

The specific configuration example of the reaction furnace 90 is as follows. The reaction furnace 90 was made of high-purity quartz for industrial use having a low content of alkali metals. The vertical cross section of the reaction furnace 90 is rectangular, and the cross section at the center is about 20 cm ² . The feature of this reactor 90 is that, as described above, the source gases (more precisely, the gas accompanying the raw materials) of the group III element and the group V element of the periodic table of the element are introduced into the reactor. First, isolated from each other for
In addition to the second flow paths 91 and 92, a dedicated sweep gas flow path 93 for flowing a sweep gas for preventing the decomposition products generated by decomposition of the raw material gas from adhering to the inner wall 94 of the reaction furnace 90.
Is provided. Therefore, the furnace is provided with a total of three flow paths 91, 92, and 93.

The substrate 100 was placed on the susceptor 99
Then, a normal oil rotary vacuum pump is provided inside the reaction furnace 90.
It was evacuated through a vacuum evacuation path (not shown).
About 10 ^-3After reaching the degree of vacuum of Torr
After holding for 10 minutes, 1 liter per minute from each of the three channels
And a total of about 3 liters / minute of purified argon
The gas (Ar) is passed through the reaction furnace 90 to reduce the pressure in the furnace.
It was returned to almost atmospheric pressure.

After purging the inside of the reaction furnace 90 with purified high-purity argon gas for about 5 minutes, the supply of the argon gas to the reaction furnace 90 was stopped. Instead, purified hydrogen gas (H ₂ ) having a dew point of about minus (−) 90 ° C. is supplied to the reactor 9.
0 was supplied. The flow rate of the hydrogen gas is determined by the flow paths 91, 92,
It was maintained at 3 liters / minute evenly with an electronic mass controller (mass flow controller (MFC)). That is, the flow paths 91, 92, and 93 were previously set in a state where hydrogen gas at a rate of 3 liters / minute was circulated.

Thereafter, a high-frequency power supply was applied to a high-frequency heating coil wound around a circle provided on the outer periphery of the reaction furnace 90. As a result, the temperature of the substrate 100 is raised from room temperature (about 25 ° C.) to 45 °.
Increased to 0 ° C. The temperature of the substrate 100 is controlled by a molybdenum (Mo) sheath-type platinum (Pt) -platinum-rhodium (Pt.Rh) alloy thermocouple (Japanese Industrial Standard) JIS-
(Thermocouple conforming to R standard). Substrate 100
Was precisely controlled within ± 1 ° C. by a commercially available PID-type temperature controller that inputs a thermoelectromotive force signal generated from a thermocouple. Approximately 20 minutes have passed since the temperature of the substrate 100 reached 450 ° C., and when the temperature fluctuation was surely controlled to 450 ° C. ± 1 ° C., the liquefied ammonia gas used as a nitrogen source was vaporized. The supply of the generated ammonia gas (NH ₃ ) to the reaction furnace 90 at a rate of 1 liter per minute was started. Ammonia was supplied into the reaction furnace 90 through the central second flow path 92 for the purpose of distribution of ammonia, which is a raw material gas of the group V element, among the three flow paths stacked three-fold. That is, 1 liter per minute of ammonia gas was flown through the central second flow path 92 together with the previously circulated 3 liter / minute of hydrogen.

At the same time as the supply of ammonia gas,
Trimethylaluminum ((CH ₃ ) ₃ Al) as a source of aluminum (Al) is supplied to the first lowermost stage in the three flow paths.
It was supplied from the flow path 91. The bubbler container made of 316 stainless steel containing trimethylaluminum was kept at 20 ° C. in an electronic thermostat using the Peltier effect. Trimethylaluminum in this container is bubbled with hydrogen gas at a flow rate of 20 cc / min.
And 3 liters per minute of hydrogen gas flowing into the reactor 90. Hydrogen gas accompanied by trimethylaluminum via respective first and second flow paths 91 and 92;
The supply of the ammonia gas to the reaction furnace 90 was continued for exactly 6 minutes. Thus, a buffer layer 100a made of aluminum nitride (AlN) having a thickness of 20 nm was formed.
The growth of the buffer layer 100a was terminated when the supply of hydrogen gas accompanied by the vapor of trimethylaluminum to the reaction furnace 90 was stopped.

Thereafter, the supply of hydrogen gas to the reaction furnace 90 via the flow paths 91, 92, and 93 is stopped, and the flow rate is changed to 2 liters / minute for each flow path, for a total of 6 liters / minute. The supply of argon gas at a flow rate of 1 minute was started. The amount of electric power applied to the high-frequency heating coil was increased, and the temperature of the substrate 100 was increased from 450 ° C. to 1050 ° C. at an average rate of about 100 ° C./min. On the way, when the temperature of the substrate 100 passed about 500 ° C., the supply of ammonia gas at a flow rate of 1 liter / min was started via the above-mentioned second flow path 92 at the center. The temperature of the substrate 100 measured by the thermocouple is 1050
When the temperature reached ° C, the supply amount of ammonia to the reaction furnace 90 was increased from 1 liter per minute to 3.5 liters per minute using an electronic mass flow meter. At the same time, the supply of argon gas from the lowermost and central first and second flow paths 91 and 92 is stopped while 2 liters of argon per minute is supplied only from the uppermost sweep gas flow path 93. did. At the same time, the supply of argon is stopped from the first and second flow paths 91 and 92 at the bottom and the center, and at the same time, 1
2 L / min of hydrogen gas per minute was passed through the first flow path 91 at the lowermost stage. As a result, a total of 8.5 liters / minute of hydrogen, argon, and ammonia flowed into the reaction furnace 90 including the high-purity quartz tube.

After the temperature of the substrate 100 reaches 1050 ° C. and waits for 5 minutes, the n-type barrier layer 10 is formed on the buffer layer 100a.
As No. 1, an n-type gallium nitride layer doped with silicon (Si) was grown. During the growth of the n-type gallium nitride layer,
Keep at 0 ° C and liquefy trimethylgallium at 30 c / min
C., a bubbling operation is performed with hydrogen gas at a flow rate of c, and hydrogen bubbling gas accompanied by trimethylgallium is supplied to the reaction furnace 90.
Supplied within. For silicon, disilane (Si ₂ H ₆ ) diluted to about 1 ppm by volume with high-purity hydrogen was added as a doping source. The flow rate of the disilane doping gas was set to 20 cc / min by an electronic mass flow meter, and the disilane doping gas was circulated together with ammonia gas from the second flow path 92 at the center.
An n-type barrier composed of a Si-doped n-type gallium nitride layer having a thickness of 3 μm by continuously supplying hydrogen bubbling gas accompanied by a gallium source and a silicon doping source gas to the reactor 90 for exactly 60 minutes. Layer 101 was obtained. The carrier concentration of the n-type barrier layer 101 was about 1 × 10 ¹⁸ cm ⁻³ .

After the growth of the n-type barrier layer 101 as the lower cladding layer was completed, the gas flowing through each of the flow paths 91, 92, and 93 was converted to argon, and the flow rate was all 2 liters per minute. Ammonia gas at a flow rate of 3.0 liters per minute was added to the center second flow path 92 and allowed to flow. After that, substrate 1
Average temperature of 00 from 1050 ° C to 870 ° C, 60 ° C
/ Min. In the course of this temperature lowering process, the substrate 10
When the temperature of 0 became 950 ° C., the supply of the gallium source and the indium source together with argon was started from the lowermost first channel 91 for the Group III element material. Gallium (G
a) The above-mentioned trimethylgallium was used as a source. The temperature of the bubbler vessel of the gallium source was 0 ° C. The source of indium is trimethylindium ((CH ₃ ) ₃ In)
It was used. Trimethylindium has an internal volume of about 100
cc in a stainless steel cylinder container,
The cylinder container was maintained at exactly 35 ° C. using an electronic thermostat. The flow rate of bubbling hydrogen gas to accompany trimethylgallium vapor in the initial stage of growth was controlled at 10 cc / min by an electronic mass flow meter.

Further, the flow rate of hydrogen gas for entraining the vapor of trimethylindium sublimated in the cylinder container accommodating the indium source into the reaction furnace 90 is 6 / min.
2.0 cc. After the temperature of the substrate 100 has dropped to 870 ° C., the flow rate of the hydrogen gas accompanying the raw materials of both Group III elements is kept constant for 7.5 minutes,
Undoped n-type light emitting layer 10 of gallium indium nitride having a constant indium composition ratio of about 0.15
2 was formed. Through the above series of growth operations, the light emitting layer 102 made of gallium indium nitride having a total layer thickness of about 50 nm including the thickness grown during the cooling was obtained.

After the supply of the gallium source and the indium source to the reaction furnace 90 was interrupted to complete the formation of the light emitting layer 102, the supply of argon and ammonia gas into the reaction furnace 90 was continued. The temperature of the substrate 100 was increased from 870 ° C. to 1050 ° C. by automatically adjusting the amount of power from the high-frequency power supply applied to the high-frequency heating coil based on the thermoelectromotive force signal from the thermocouple. In order to suppress volatilization of the indium-containing light-emitting layer 102 due to a carelessly gradual rise in temperature during the heating process, the temperature is increased from 870 ° C. to 1050 ° C. by 1.5%.
The temperature rose in minutes.

Dead space:
There is also a growth means which is small in stagnation space and relies on the operation of the valve having good high-speed response, and immediately shifts to the growth of the p-type junction layer after the growth of the light emitting layer 102. However, in the present embodiment, the MOC was reduced due to the effect of flowing the sweep gas during the temperature rise.
Only a brownish thin film is adhered to the inner wall 94 of the VD reactor 90, and after confirming that there is no visually visible droplets of metal such as gallium, the flow rate of argon as a scavenging gas is changed every time. The amount was increased from 2 liters to 5 liters, and this state was continued for 5 minutes and waited. By increasing the flow rate of argon and continuing for 5 minutes, undecomposed raw material gas or the like that is not likely to remain or remain in the reaction furnace 90 is reliably discharged to the outside of the furnace, and joined to the next layer (p-type barrier layer) 103. Interface 10
5 steepened. As described above, in the present embodiment, the piping system having components such as valves having a small dead space is used for steepening the interface, and further, the film formation of the next layer (p-type barrier layer) 103 is started. In addition, the above-mentioned heating time (1.5 minutes) and the waiting time (5 minutes) are combined for a total of 6.5.
A growth interruption time (interval time) over a period of one minute was provided.

After the temperature of the substrate 100 reached 1050 ° C., the flow rates of argon, ammonia and hydrogen flowing through the respective flow paths 91, 92 and 93 were the same as in the case of forming the n-type barrier layer 101. In addition to the accompanying gas containing the gallium source, a hydrogen gas accompanying the steam of the aluminum source was added to the lowermost first flow path 91. Hydrogen gas containing a magnesium source was also added. Trimethylgallium was used as the gallium source. The bubbler container made of 316 stainless steel containing trimethylgallium was maintained at exactly 0 ° C. in an electronic thermostat. The flow rate of hydrogen gas for bubbling and entrainment of trimethylgallium vapor was 30 cc / min. The aluminum source was trimethyl aluminum used when forming the buffer layer 100a. The supply amount of the aluminum source is aluminum nitride with an aluminum composition ratio of 0.1.
It was set so that gallium mixed crystal could be obtained. The doping source magnesium bis - using cyclopentadienyl magnesium _{(bis- (CH 3 C 5 H} 4) 2 Mg). The stainless steel cylinder container containing the magnesium doping source is heated to 45 ° C by an electronic thermostat.
Was kept at a constant temperature. In the bis-methylcyclopentadienyl magnesium liquefied at the same temperature, a hydrogen gas controlled as a bubbling gas with a flow rate precisely controlled to 20 cc / min by an electronic mass flow meter is passed. Was. The supply of the hydrogen gas accompanied by the vapors of the gallium source, the aluminum source and the magnesium source to the reaction furnace 90 is performed simultaneously and instantaneously via the high-speed switching valve in order to steepen the junction interface 105 with the light emitting layer 102. I went to. Raw materials are continuously supplied to the reaction furnace 90 for 5 minutes,
Aluminum-gallium nitride mixed crystal doped with magnesium having a layer thickness of 0.2 μm (Al _0.1 Ga
_A p-type barrier layer 103 made of _0.9 N) mixed crystal was formed. The supply of the hydrogen gas accompanying the vapor of the aluminum source was stopped, and the formation of the p-type barrier layer 103 was completed.

Thus, the n-type barrier layer 101 made of gallium nitride (GaN) doped with silicon, the light emitting layer 102 made of gallium indium nitride (Ga _0.85 In _0.15 N), and the aluminum nitride doped with magnesium A heterojunction structure including the p-type barrier layer 103 made of gallium mixed crystal (Al _0.1 Ga _0.9 N) was formed. And at the time of construction of this heterojunction structure,
When stacking the light emitting layer 102 on the n-type barrier layer 101,
By changing the growth temperature over time and changing the flow rate of the source gas gradually over time to form a film, the bonding interface 1
04, the steepness of the composition is relatively moderate, and when the p-type barrier layer 103 is laminated on the light emitting layer 102, a piping system having a valve or the like with a small dead space is used. The steepness of the composition at the junction interface 105 is remarkable by providing an interval time during the transition to the formation of the barrier layer 103 and by instantaneously changing the flow rate of the source gas in a pulsed manner.

Subsequently, the temperature of the substrate 100 is set to 1050 ° C.
While the supply flow rates of the ammonia, the gallium source and the magnesium source are kept unchanged, the outermost layer 11 is formed on the p-type barrier layer 103 made of aluminum nitride-gallium mixed crystal.
0 was deposited. During the growth of the outermost layer 110, a gas containing diethyl zinc ((C ₂ H ₅ ) ₂ Zn) is supplied with zinc (Zn).
Was added as a doping source. A high-purity hydrogen gas containing 100 ppm by volume of diethyl zinc was used as a zinc doping source. The supply of the source gas and the doping gas was continued for 3 minutes to form a top layer 110 of gallium nitride doped with both magnesium and zinc having a layer thickness of 0.1 μm. The formation of the outermost layer 110 made of gallium nitride was terminated by stopping the flow of the gallium source into the reaction furnace 90. At the same time, the supply of the doping gas of magnesium and zinc and the supply of hydrogen gas into the reactor 90 were also stopped.

On the other hand, the flow rate of ammonia gas was 3.5 per minute.
Liters. The amount of high-frequency power applied to the high-frequency heating coil was reduced, and the temperature of the substrate 100 was reduced from 1050 ° C. to 950 ° C. in about 2 minutes. 950 ° C to 65
The temperature was lowered to 0 ° C at a rate of 15 ° C per minute for 20 minutes. When the temperature was lowered to 650 ° C., the supply of the ammonia gas into the reaction furnace 90 was stopped, and only the gas flowing through the reaction furnace 90 was argon. In this state, the system was cooled down to room temperature.

With the above growth operation, the n-type barrier layer 10
, An n-type light emitting layer 102, and a p-type barrier layer 103, and a p-type outermost layer 11 of gallium nitride doped with both magnesium and zinc.
By laminating 0, the formation of the laminated structure 10a was completed.

One piece (about 5 mm × about 5 mm × t (thickness)) was cut out from the laminated structure 10 a and provided as a sample for analysis of the constituent elements in the depth direction. Outermost layer 11 of laminated structure 10a
The matrix element concentration distribution (depth profile) in the depth direction from 0 is obtained using a commercially available SIMS analyzer (CA of France).
(IMCA-6F secondary ion mass spectrometer manufactured by MECA)
Quantified. For the concentration analysis of indium and aluminum, a cesium (Cs) ion beam was used as a primary ion beam for both. Beam acceleration voltage is 5.5KV
And The concentration distributions of indium and aluminum at the bonding interfaces 104 and 105 with the light-emitting layer 102 measured using this SIMS analyzer were as follows.

FIG. 8 is a diagram showing the concentration distribution of indium and aluminum at the junction interface with the light emitting layer. The horizontal axis indicates the depth from the surface of the multilayer structure, and the vertical axis indicates the atomic concentration. As shown by the concentration distribution curve C1 of indium atoms, when comparing the transition region widths Δtwi and Δtvi required for reducing the concentration of indium atoms from the average concentration RoI inside the light emitting layer 102 to a concentration two orders of magnitude lower, n Interface 10 between p-type gallium indium nitride indium light emitting layer 102 and p-type barrier layer 103 made of aluminum nitride / gallium mixed crystal
The transition region width Δtwi on the 5th side is about 18% from the starting point D4 due to the instantaneous change of the source gas as described above.
It was extremely narrow as nm. Here, the starting point D4 coincides with the bonding interface 105. Transition region width Δt vi on the junction interface 104 side with one n-type gallium nitride barrier layer 101
Was about 30 nm from the starting point D3, which was wider than Δtwi, due to the fact that the growth temperature was changed over time as described above. Here, the starting point D3 is set at the bonding interface 1
04 and is located inside the light emitting layer 102.

On the other hand, regarding the concentration of aluminum atoms, as shown by the concentration distribution curve C2 of aluminum atoms,
Transition region width Δ required to reduce the average aluminum atom concentration Roa inside the light emitting layer 102 to a concentration two orders of magnitude lower.
twa is smaller than the transition region width Δtwi of indium of 18 nm. Thus, the bonding interface 105
The indium atom and the aluminum atom in Example 1 all dropped sharply after passing over the junction interface 105, and it was found that the requirement for the remarkable steepness at the junction interface 105 was sufficiently satisfied.

(Second Embodiment) FIG. 9 is a view showing a laminated structure according to a second embodiment of the present invention. In the figure, the same components as those of the laminated structure 10a of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the second embodiment, a stacked structure 100b is formed by sandwiching a quantum well structure 200 between an n-type barrier layer 101 and a p-type barrier layer 103. In order to form the laminated structure 100b, in the second embodiment, an atmospheric pressure MOCVD growth apparatus having two piping systems capable of supplying an indium raw material individually and independently was used as a film forming apparatus. The piping system has a different ability to achieve the steepness of the joint interface.

As shown in FIG. 9, a barrier layer made of n-type gallium nitride is formed on the aluminum nitride buffer layer 100a and the n-type barrier layer 101 deposited on the sapphire substrate 100 described in the first embodiment by the above growth apparatus. 201 was formed as a termination layer. The barrier layer 201 was made of n-type undoped gallium nitride, and the layer thickness was set to 30 nm. The barrier layer 201 is the same as the n-type barrier layer 101 described in the first embodiment.
Was grown at 1050 ° C. After the growth of the barrier layer 201 is completed, the growth temperature is lowered to 870 ° C., and the undoped n-type gallium indium nitride (Ga _0.85
An In _0.15 N) well layer 202 was grown. Well layer 202
Was formed under the flow conditions for the gallium source and the indium source described in the first embodiment. However, in order to make the layer thickness sufficient to express the quantum level, the layer thickness was changed to 6 nm by shortening the growth time with respect to the first embodiment. This n
In order to form the well layer 202 closest to the shape barrier layer 101, an indium piping system, which is inferior in steepness, was used. Thereafter, the substrate temperature was raised to 1000 ° C. to observe the temperature stability, and then a barrier layer 203 made of undoped n-type gallium nitride was deposited.

After the growth of the second barrier layer 203 was completed, the temperature of the substrate 100 was lowered to 870 ° C. to grow the n-type undoped gallium indium nitride well layer 204. In this case, the well layer 202 on the n-type barrier layer side
Unlike the indium piping system used to form the indium, the occurrence of "slack" on the indium concentration distribution at the joint interface can be suppressed as much as possible, and another indium that has been found in advance to give a steep interface A piping system was used. After the growth of the well layer 204, which is to be positioned on the p-type barrier layer 103 side, is completed, the substrate temperature is again set to 1000 ° C., and the n-type nitride layer to be joined to the p-type barrier layer 103 is formed. Gallium barrier layer 205 was grown. As a result, both terminal layers are made of barrier layers 201 and 205 made of undoped n-type gallium nitride, and two well layers 202 and 204 and three barrier layers 201, 203 and Thus, a quantum well structure 200 having a multiple quantum well structure consisting of S.205 and S.205 was formed. The electrical conductivity type of the quantum well structure 200 is an n-type.

N which is one end of the above multiple quantum well structure
Quantum well structure 20 on the gallium nitride barrier layer 205
P-type barrier layer 103 whose electric conductivity type is opposite (reverse) to 0
Was joined. In this case, too, an indium piping system known to give a steep interface was used. The p-type barrier layer 103 bonded on the n-type gallium nitride barrier layer 205 and the outermost gallium nitride layer 110 on the p-type barrier layer 103 were grown under the same conditions as in the first embodiment. As described above, the n-type barrier layer 101 and the gallium-indium nitride /
Gallium nitride multiple quantum well structure quantum well structure 200
Then, a laminated structure 10b having a pn junction type DH structure including a light emitting portion composed of the p-type barrier layer 103 and the p-type barrier layer 103 was formed.

The interface steepness measured from the result of SIMS analysis of the concentration distribution of the constituent elements in the depth direction of the laminated structure 10b is as follows. It was about 45 nm at the junction interface 211 with the indium barrier layer 201. On the other hand, the undoped n disposed on the p-type barrier layer 103 side
The transition region width of the indium atom concentration at the junction interface 214 between the gallium nitride indium well layer 204 and the undoped n-type gallium nitride barrier layer 205 was about 14 nm. Further, both barrier layers 203 and 20 of the gallium-indium indium well layer 204 disposed on the p-type barrier layer 103 are formed.
The sharpness of the indium atom concentration at the junction interfaces 213 and 214 of No. 5 is due to the junction interfaces 211 and 212 of the well layer 202 disposed on the n-type barrier layer side with both the barrier layers 201 and 203.
It was characterized by having less "slack" than that of.

(Third Embodiment) FIG. 10 is a view showing a laminated structure according to a third embodiment of the present invention. In the figure, the first
The same components as those of the laminated structure 10a of the embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the third embodiment, between the n-type barrier layer 101 and the light emitting layer 102, the first composition transition layer 71 relating to the indium concentration which stabilizes the change of the indium concentration.
Is provided. The first composition transition layer 71 has a thickness of 50
It was composed of an undoped n-type gallium indium nitride layer having a thickness of nm. The first composition transition layer 71 has a thickness of 5
In this case, the atomic concentration of indium is increased by two orders of magnitude while reaching 0 nm, so that the average indium concentration in the light emitting layer 102 is obtained.

First, as described in the first embodiment, the barrier layer 101 made of n-type gallium nitride was formed by a 10-layer process.
After forming the film at 50 ° C., the temperature of the substrate 100 was lowered to 870 ° C. Next, after waiting at the same temperature for 3 minutes until the temperature of the substrate 100 stabilizes at 870 ° C., when forming the n-type undoped gallium nitride-indium light emitting layer 102, the indium sources of gallium source and indium are used. The first composition transition layer 71 of indium was formed by changing the supply ratio (the gas phase composition ratio of the indium raw material) to the group III element source, which is the sum of the supply amounts of the sources, with time.

More specifically, in the initial stage of the growth of the light emitting layer 102, hydrogen gas is passed through a container containing trimethylindium as an indium source maintained at a constant temperature of 35 ° C., and sublimated trimethylindium is added. The flow rate of the generated hydrogen gas was uniformly increased in time from 0 (zero) to 62.0 cc / min for 15 minutes. During this time, the flow rate of hydrogen gas for bubbling trimethylgallium as a gallium source kept at a constant temperature of 0 ° C. was kept constant at 10 cc / min, and the first composition transition layer 71 of indium was formed. Thereafter, the flow rate of the hydrogen gas accompanying the indium source was finally set to 62.0 cc / min, and the flow rate of the hydrogen gas accompanying the gallium source was set to 10 cc / min. An undoped n-type gallium indium nitride (Ga) layer having a thickness of 5 nm and a constant indium composition of 0.15 in the depth direction by continuously supplying the group III element material is provided.
_A light emitting layer 102 of _0.85 In _0.15 N) was grown.
On the light emitting layer 102, a p-type barrier layer 103 and an outermost layer 110 made of p-type gallium nitride were sequentially deposited. In this manner, the first composition transition for providing a stable change in the concentration of indium atoms at the junction interface of the n-type light-emitting layer / n-type barrier layer between the n-type light-emitting layer 102 and the n-type barrier layer 101. The laminated structure 10c including the configuration in which the layer 71 was arranged was formed.

From the result of the analysis of the concentration of indium atoms in the depth direction by SIMS analysis, it can be seen that the n-type barrier layer 1
The transition region width of the atomic concentration of indium on the bonding interface side between 01 and the n-type light emitting layer 102 was about 30 nm. That is, in the first composition transition layer 71 relating to the indium concentration where the layer thickness is 50 nm, the width (distance) required for the indium atom concentration to actually increase by two orders to reach the average concentration inside the light emitting layer 2 ) Was about 30 nm. In the first composition transition layer 71, the indium atom concentration monotonically increased from the n-type barrier layer 101 side to the n-type light emitting layer 102 side. On the other hand, the n-type light emitting layer 102 and the p-type barrier layer 10
The transition region width of the indium atom concentration on the bonding interface side with No. 3 was about 15 nm.

(Fourth Embodiment) FIG. 11 is a view showing a laminated structure according to a fourth embodiment of the present invention. In the figure, the third
The same components as those of the laminated structure 10c of the embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the fourth embodiment, a second composition transition layer 81 for indium composition is provided between the n-type light emitting layer 102 and the p-type barrier layer 103. After growing up to the n-type light emitting layer 102 according to the procedure described in the third embodiment,
The substrate 10 was heated to 870 ° C., which was the growth temperature of the n-type light emitting layer 102.
While maintaining the temperature of 0, a second composition transition layer 81 having a layer thickness of 20 nm was formed using an indium supply piping system that provides excellent interface steepness. This second composition transition layer 8
In the early stage of the formation of No. 1, the supply rate of hydrogen gas accompanying the sublimated indium raw material was 62.0 cc / min.
The flow rate of the hydrogen gas accompanying the indium source is uniformly set to 0c during the growth time of the second composition transition layer 81 over 10 minutes.
c / min. During this time, the flow rate of the bubbling hydrogen gas accompanying the vapor of the gallium source (trimethylgallium) maintained at 0 ° C. was fixed at 10 cc / min. On the second composition transition layer 81 thus formed, the p-type barrier layer 103 and the p-type outermost layer 110 were sequentially laminated according to the conditions and operations described in the first embodiment. As a result, a laminated structure 10d including a configuration in which the second composition transition layer 81 that causes a stable change in the indium atom concentration is disposed on both sides of the light emitting layer 102 was obtained.

FIG. 12 is a diagram showing the concentration distribution of indium atoms at the junction interface with the light emitting layer in the fourth embodiment. The horizontal axis represents the depth from the surface of the multilayer structure, and the vertical axis represents the concentration of indium atoms. The distribution of the indium atom concentration was measured by SIMS analysis.

In the figure, the concentration distribution C of indium atoms is shown.
As shown in FIG. 3, the film thickness on the n-type barrier layer 101 side is 50 nm.
The transition region width Δt _vM of the indium atom concentration in the composition transition layer 71 is substantially the same as that of the third embodiment and is about 30 nm.
Met. That is, in the first composition transition layer 71, the width (distance) required for the indium atom concentration to actually increase by two digits and reach the average concentration inside the light emitting layer 2 is about 30.
nm. On the other hand, the transition region width Δt _WM of the indium atom concentration of the composition transition layer 81 on the p-type barrier layer 103 side is about 18
nm. That is, in the second composition transition layer 81 relating to the indium concentration where the layer thickness is 20 nm, the width (distance) required for actually reducing the average indium atom concentration inside the light emitting layer 2 by two digits is about 18 nm. there were.

An LED was manufactured using the laminated structure 10d of the fourth embodiment as a base material. FIG. 13 is a diagram schematically showing a cross-sectional structure of the LED, and is a cross-sectional view taken along line AA of FIG.
4 is a schematic plan view of the LED. In order to construct the LED 60 shown in FIGS. 13 and 14, first, in the laminated structure 10d of FIG. , The p-type barrier layer 103 and the outermost layer 110 were removed by etching using a microwave plasma etching technique using an argon-methane (CH ₄ ) -hydrogen mixed gas. This etching removes the surface of the n-type barrier layer 101 by about 150 nm.
Continued until removal. Thereafter, on the surface of the n-type barrier layer 101 exposed by etching, a pad electrode 61 having no translucent or transmissive electrode was formed. The pad electrode 61 was made of aluminum (Al) alone.

On the other hand, on the outermost layer 110, a pad electrode 62 composed of a multilayer of gold-beryllium (Au-Be) alloy and gold (Au) and a transmissive layer composed of two layers having a total film thickness of about 20 nm. (Light transmitting) electrode 63 was applied. The transparent electrode 63 was formed on almost the entire surface of the outermost layer 110 left in a mesa shape by the above-described etching. Although there is a method of forming a pad electrode directly on the surface of the transparent electrode 63, in this embodiment, only the metal oxide film forming the surface layer of the transparent electrode 63 is selectively removed, and the remaining lower layer is removed. The pad electrode 62 was formed on the gold (Au) thin film electrode.

In the LED 60 thus formed, a DC voltage was applied between the adjacent electrodes 61 and 62. Blue light emission was already obtained by applying a DC voltage of less than 5 volts (V), for example, 3.5 V. The intensity of blue light emission increased as the applied voltage increased. In the measurement using an integrating sphere, the forward current was set to 20 milliamperes (mA).
The light output when flowing was 17.0 microwatts (μ
W). Incidentally, without paying attention to the required difference in steepness regarding the indium atom concentration at the junction interface between the light emitting layer and the barrier layer, the light emission output of the conventional DH structure LED which is simply mechanically joined is about 11 μW or more. About 14
μW. As a result, it has become clear that a light-emitting element having excellent emission intensity is provided by providing an interface steepness satisfying the conditions defined by the present invention. In the measurement of the emission spectrum using a normal photoluminescence photometer using helium (He) -cadmium (Cd) laser light as the excitation light, it was found that the emission wavelength of the main emission spectrum was about 445 to 462 nm. Also,
The half-value width of the main emission spectrum is approximately 12 to 15 nm.
Therefore, it was also found that the light emission from the LED 60 was excellent in monochromaticity (color purity).

With respect to the laminated structure formed in each of the other examples, an LED was manufactured from the laminated structure, and the light emission output, the light emission wavelength of the light emission spectrum, and the half width of the light emission spectrum were measured in the same manner as described above. A quality result almost equivalent to that of the above LED 60 was obtained.

In each of the above embodiments, the case where the present invention is applied to a light emitting diode (LED) has been described.
The same can be applied to D).

[0125]

As described above, according to the group III nitride semiconductor light emitting device of the present invention, the gradient of the indium atom concentration at the junction interface between the light emitting layer in the light emitting portion and the barrier layer joined thereto is increased. , Carriers can be selectively and preferentially localized on the side of the barrier layer having the opposite electrical conductivity type to the light emitting layer, and recombination of holes and electrons can be achieved. Can be performed effectively. Therefore, when configured as a light emitting element, it is possible to sufficiently exhibit emission intensity characteristics and color purity (monochromaticity) characteristics, and to convert short-wavelength light from a blue band to a green band into high intensity and excellent color purity ( (Monochromatic).

[Brief description of the drawings]

FIG. 1 is a diagram conceptually showing a light emitting portion in a group III nitride semiconductor light emitting device of the present invention.

FIG. 2 is a diagram showing an example of the configuration of a growth reaction furnace invented for achieving steepness of a junction interface made of a group III nitride semiconductor.

FIG. 3 is a diagram illustrating a case where a composition transition layer is provided in a light emitting unit.

FIG. 4 is a diagram showing a first configuration example when the present invention is applied to a multiple quantum well structure.

FIG. 5 is a diagram showing a second configuration example when the present invention is applied to a multiple quantum well structure.

FIG. 6 is a diagram showing a third configuration example when the present invention is applied to a multiple quantum well structure.

FIG. 7 is a view showing a laminated structure according to the first embodiment of the present invention.

FIG. 8 is a diagram showing a concentration distribution of indium and aluminum at a bonding interface with a light emitting layer in the first embodiment.

FIG. 9 is a view showing a laminated structure according to a second embodiment of the present invention.

FIG. 10 is a view showing a laminated structure according to a third embodiment of the present invention.

FIG. 11 is a view showing a laminated structure according to a fourth embodiment of the present invention.

FIG. 12 is a diagram showing a concentration distribution of indium atoms at a junction interface with a light emitting layer in a fourth embodiment.

FIG. 13 is a diagram schematically showing a cross-sectional structure of an LED.

FIG. 14 is a schematic plan view of an LED.

FIG. 15 is a diagram schematically showing a potential well structure in a laminated structure for MODFET use.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 n-type barrier layer 2 n-type light-emitting layer 3 p-type barrier layer 4 junction interface between n-type barrier layer and light-emitting layer 5 junction interface between p-type barrier layer and light-emitting layer 6 anti-scattering layer (thin layer) 7 composition transition Layer 8 Composition transition layer 10, 10s, 11, 12 Light emitting portion 10a, 10b, 10c, 10d Laminated structure 41, 42, 43, 51, 52, 53 Bonding interface 60 LED 61 Pad electrode (negative electrode) 62 Pad electrode ( (Positive electrode) 63 Transmissive electrode 71 First composition transition layer 81 Second composition transition layer 90 Growth reaction furnace 91 First passage 92 Second passage 93 Sweep gas passage 94 Inner wall 99 Susceptor 100 Substrate 101 N-type barrier layer 102 Light-emitting layer 103 p-type barrier layer 104 junction interface between n-type barrier layer and light-emitting layer 105 junction interface between p-type barrier layer and light-emitting layer 110 outermost layer 200 quantum well structure 201, 203, 205 barrier C, C1, C3 concentration distribution curve of the density distribution curve C2 aluminum atoms indium atoms D1, D2, D3, origin concentrations of D4 indium atoms decreases _{Δt v, Δt v1, Δt va} , Δt vb, Δt vc, Δt vM , Δ
transition region widths Δt _W , Δt _W1 , Δt _Wa , Δt _Wb , Δt _Wc , Δt _WM , and Δt _W , Δt _W1 , Δt _Wa , Δt _Wb between the t _vi , Δt _vZ light-emitting layer and the barrier layer having the same electrical conductivity type as the light-emitting layer.
transition region width between the t _Wi , Δt _WZ light emitting layer and the barrier layer having the opposite conductivity type to the light emitting layer

Claims (7)

[Claims] 1. A light-emitting section comprising a light-emitting portion formed by sandwiching a light-emitting layer made of an indium-containing group-III nitride semiconductor between a n-type barrier layer made of a group III nitride semiconductor and a p-type barrier layer.
In the group I nitride semiconductor light emitting device, the transition region width Δt _V of the indium atom concentration on the side of the same electric conduction type barrier layer as that of the light emitting layer, and the indium on the side of the electric conduction type barrier layer opposite to the above light emitting layer. III-nitride semiconductor light emitting device of the relationship between the transition region width Delta] t _w of the atomic density and a light emitting unit having the concentration distribution of the indium atoms to Δt _w <Δt _V, that said. Wherein said transition region width Delta] t _V, the Delta] t _w, expressed from the light-emitting layer is an indium atomic concentration reduced by two orders of magnitude than the indium atom concentration in the light emitting layer at a distance towards the barrier layers, each of the light-emitting layer transition region width Delta] t _V of the distance to two orders of magnitude decrease toward the barrier layer, hereinafter 250 nanometers to Delta] t _V in Delta] t _w (nm), a Delta] t _W 20 nanometers (n
m): The group III nitride semiconductor light-emitting device according to claim 1, wherein 3. A light-emitting element comprising a light-emitting portion formed by sandwiching a light-emitting layer made of an indium-containing group-III nitride semiconductor between a n-type barrier layer made of a group III nitride semiconductor and a p-type barrier layer.
In the group I nitride semiconductor light emitting device, a composition for reducing the concentration of indium atoms in the light emitting layer from the light emitting layer toward the barrier layer between the light emitting layer and the barrier layer of the same electrical conductivity type as the light emitting layer. A composition in which a transition layer ΔS _V is disposed, and a concentration of indium atoms in the light emitting layer is reduced from the light emitting layer toward the barrier layer between the light emitting layer and the electrically conductive barrier layer opposite to the light emitting layer. A group III nitride semiconductor light-emitting device, wherein a transition layer ΔS _W is disposed, and a layer thickness of the composition transition layer ΔS _V is larger than a layer thickness of the composition transition layer ΔS _W. 4. A well layer as a light emitting layer made of an indium-containing group III nitride semiconductor, which is located between an n-type barrier layer made of a group III nitride semiconductor and a p-type barrier layer. A light-emitting portion comprising a quantum well structure sandwiched between the well layer and a barrier layer having the same electrical conductivity type and made of an indium-containing group III nitride semiconductor having a larger band gap; In the group III nitride semiconductor light emitting device, the transition region width Δt _Va of the indium atom concentration on the barrier layer side of the same electrical conductivity type as the quantum well structure, and the electrical conductivity type opposite to the quantum well structure. The relationship between the transition region width Δt _wa of the indium atom concentration on the barrier layer side and Δt _wa
A group III nitride semiconductor light emitting device, comprising: a light emitting portion having a concentration distribution of indium atoms satisfying _wa <Δt _Va . 5. The transition region widths Δt _Va and Δt _wa are represented by distances from the quantum well structure in which the indium atom concentration is reduced by two orders of magnitude from the indium atom concentration in the quantum well structure toward each barrier layer. Transition region widths Δt _Va and Δt _wa as distances reduced by two digits from the well structure toward each barrier layer
At 250 nm or less, Δt _Va
The group III nitride semiconductor light emitting device according to claim 4, wherein _{Wa is set} to 20 nanometers (nm) or less. 6. A well layer as a light emitting layer made of an indium-containing group III nitride semiconductor, which is located between an n-type barrier layer made of a group III nitride semiconductor and a p-type barrier layer. A light-emitting portion comprising a quantum well structure sandwiched between a well layer and a barrier layer having the same electrical conductivity type and made of a group III nitride semiconductor having a larger forbidden band width. In the group nitride semiconductor light-emitting device, when each of the termination layers of the quantum well structure is a well layer, the transition region width Δt _Vb of the indium atom concentration on the barrier layer side of the same electrical conductivity type as the quantum well structure; The relationship between the transition region width Δt _wb of the indium atom concentration on the side of the electric conduction type barrier layer opposite to the quantum well structure is represented by Δt _wb <Δt _Vb
In the case where each of the terminal layers of the quantum well structure is a barrier layer containing no indium, the indium on the terminal layer side in contact with the barrier layer of the same electrical conductivity type as the well layer is used. indium atoms and a transition region width Delta] t _Vc of atomic concentration, and relationship Δt _wc <Δt _Vc of the transition region width Delta] t _wc indium atomic concentration at the end layer side in contact with the barrier layer of opposite electrical conductivity type is the well layer A group III nitride semiconductor light-emitting device, characterized in that the light-emitting portion has a concentration distribution of: 7. The transition region widths Δt _Vb and Δt _wb are represented by a distance from a well layer in which the indium atom concentration is reduced by two orders of magnitude from the indium atom concentration in the well layer toward each barrier layer. At the transition region width Δt _Vb , Δt _wb as a distance reduced by two digits toward the barrier layer, Δt _Vb is 250 nm or less, and Δt _Wb is 20 nm (n).
m) or less, and the transition region widths Δt _Vc and _Δtwc are represented by distances from the well layer in which the indium atom concentration is reduced by two orders of magnitude from the indium atom concentration in the well layer to each termination layer. Transition region width Δ as distance reduced by two digits toward termination layer
At t _Vc and Δt _wc , Δt _{Vc is set} to 250 nanometers (n
The group III nitride semiconductor light-emitting device according to claim 6, wherein Δt _Wc is not more than 20 nanometers (nm) or less.