JP2003243772A - Semiconductor light emitting device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor light emitting device that can keep a p-side clad layer at such a thickness that is necessary to demonstrate an appropriate optical characteristic. <P>SOLUTION: This semiconductor light emitting device uses a nitride-based III-V group compound semiconductor, and is provided with a structure that an active layer is pinched between an n-side clad layer and a p-side clad layer and a ridge structure formed by selective growth. For example, in a semiconductor laser, the p-side clad layer is comprised of an n-type first layer 9 that is undoped in sequence from the side of an active layer 7, and a p-type second layer 12 that a p-type impurity is doped. When the first layer 9 is provided on a growth boundary between a ridge 18 and a base layer, or an undoped or n-type another layer is provided between the first layer 9 and a second layer 12, the p-side clad layer is included in the first layer 9 or another layer. The first layer 9 is 50 nm or more in thickness. A p-type third layer 11 that is more than 50 nm in band gap is inserted as an electron block layer into the p-type second layer 12. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device and a method for manufacturing the same, and more particularly to a nitride-based III-V.
It is suitable to be applied to a semiconductor laser or a light emitting diode using a group compound semiconductor.

[0002]

2. Description of the Related Art In recent years, as a semiconductor laser capable of emitting light from the blue region to the ultraviolet region, which is required for increasing the density of optical discs, nitride-based III-based materials such as AlGaInN
Research and development of semiconductor lasers using V-group compound semiconductors have been actively conducted and have already been put to practical use.

As a semiconductor laser using this nitride III-V compound semiconductor, a semiconductor laser having a ridge structure formed by selective growth has been proposed (J.
Crystal Growth 144 (1994) 133 and JP 2000-5
8461 publication). The main part of this semiconductor laser is shown in FIG. As shown in FIG. 9, in order to manufacture this semiconductor laser, a p-type GaN contact layer (neither is shown) and an n-type AlGaN cladding layer 101 are provided on a c-plane sapphire substrate via a GaN buffer layer grown at a low temperature. , N-type GaN
Optical waveguide layer 102, active layer 103, p-type GaN optical waveguide layer 1
04 and a p-type AlGaN clad layer 105 are sequentially grown, and a SiO ₂ film 106 is formed thereon.
After forming the stripe-shaped opening 106a in a predetermined portion of the ₂ film 106, p-type AlGaN cladding layer 107 and the p-type GaN on the p-type AlGaN cladding layer 105 in the portion of the opening 106a of the SiO ₂ film 106 as a growth mask The contact layer 108 is sequentially selectively grown to form a ridge.

[0004]

However, according to the study by the present inventor, in the above-mentioned conventional semiconductor laser, p in the portion of the opening 106a of the SiO ₂ film 106 is reduced.
When the p-type AlGaN clad layer 107 is selectively grown on the n-type AlGaN clad layer 105, an n-type impurity (mainly S
i) remains in the growth chamber of the growth apparatus, the growth interface is contaminated by the n-type impurities, and defects that act as donors are generated at the growth interface, so that the vicinity of the growth interface becomes n-type. Therefore, in reality, as shown in FIG. 10, n-type A is formed at the interface between the p-type AlGaN clad layer 105 and the selectively grown p-type AlGaN clad layer 107.
The lGaN layer 109 is formed, and the pnp layers are formed by these layers.
The structure is formed. As a result, the series resistance of the entire p-type clad layer including the p-type AlGaN clad layer 105 and the p-type AlGaN clad layer 107 increases,
There is a problem that the operating voltage of the semiconductor laser is increased.

Therefore, the problem to be solved by the present invention is to reduce the operating voltage while keeping the thickness of the p-side cladding layer at a value necessary and sufficient for obtaining good optical characteristics. It is an object of the present invention to provide a semiconductor light emitting device and a method for manufacturing a semiconductor light emitting device, which can easily manufacture such a semiconductor light emitting device. The above problems and other problems of the present invention will be apparent from the following description of the present specification with reference to the accompanying drawings.

[0006]

In order to solve the above problems, the first invention of the present invention is directed to a structure and selective growth in which an active layer is sandwiched between an n-side cladding layer and a p-side cladding layer. Nitride system II having a ridge structure formed by
In a semiconductor light emitting device using a group IV compound semiconductor, a p-side cladding layer is composed of an undoped or n-type first layer and a p-type second layer doped with p-type impurities in order from the active layer side. And the second layer has a third layer having a bandgap larger than that of the second layer, and the growth interface between the ridge and the underlayer is the first layer or the first layer and the second layer. When an undoped or other n-type layer is provided between the first layer and the second layer in contact with the first layer, it is included in the first layer or this other layer. Here, when an undoped or other n-type layer is provided so that the growth interface between the ridge and the underlayer is in contact with the first layer or between the first layer and the second layer. Is included in the first layer or the other layer means that the growth interface between the ridge and the underlayer is completely included in the first layer or the first layer or the other layer, It also means that the growth interface between the ridge and the underlayer coincides with the surface of the first layer on the second layer side or the surface of the other layer on the second layer side. This is because the distance between the bottom surface (surface of the underlayer) of both sides of the ridge and the active layer is d, and the distance between the p-type layer closest to the active layer and the active layer included in the ridge is L. _{If it is p,} it can be said that L _p ≧ d.

This semiconductor light emitting device is typically a SCH.
(Separate Confinement Heterostructure) structure. That is, an n-side optical waveguide layer is provided between the n-side clad layer and the active layer, and p is provided between the p-side clad layer and the active layer.
A side light guiding layer is provided.

The total thickness of the p-side cladding layer is generally 500 to 600 nm. p of p-side clad layer
The thickness of the second layer of the mold is generally greater than 0 nm and 5
50 nm or less or 450 nm or less, but typically 390 nm or more and 550 nm or less, more typically 4
It is 00 nm or more and 530 nm or less. On the other hand, the thickness of the undoped first layer of the p-side cladding layer (in this case, n ⁻ type is present, and the specific resistance is generally a fraction to one digit lower than that of the p-type layer) is generally Greater than 0 nm and 500
However, it is preferably 50 nm or more, more preferably 70 nm or more, still more preferably 90 nm or more, from the viewpoint of sufficiently reducing the resistance of the p-side cladding layer. The range may be selected to be 400 nm or less, 300 nm or less, or 200 nm or less, and may be a range in which these upper and lower limits are arbitrarily combined. This first
The thickness of the layer is 70 nm or more in one typical example 13
0 nm or less, more typically 90 nm or more 1
It is selected to be 10 nm or less. These undoped or n
The first layer of the p-type and the second layer of the p-type are such that as long as necessary optical characteristics, for example, a sufficiently high optical confinement factor Γ is obtained and a good far field pattern (FFP) is obtained. They may be made of the same material as each other or may be made of different materials. As an example of the former, the material of the first layer and the material of the second layer are both AlGaN.
In the latter case, AlGaN is used as the material of the second layer and AlGaInN, GaN, InGaN, or the like is used as the material of the first layer. The first layer and the second layer may be in direct contact with each other, or may be in indirect contact with each other through another layer having some function. Of these, particularly when an undoped or other n-type layer is provided between the first layer and the second layer in contact with the first layer, the growth of the ridge and the underlayer is performed as described above. The interface is included in the first layer or other layers.

When the n-side optical waveguide layer and the p-side optical waveguide layer are provided, their thickness is generally larger than 0 nm and 50 nm or less.

The undoped or n-type first layer of the p-side cladding layer makes holes that are injected from the p-side electrode side during the operation of the semiconductor light emitting device easily reach the active layer by the tunnel effect to improve the injection efficiency. From the viewpoint of preventing the deterioration of the active layer by suppressing the diffusion of Mg, which is usually used as the p-type impurity of the second layer, toward the active layer by introducing the hetero interface, it is preferable to use a superlattice. The structure. In one typical example, the entire p-side cladding layer has a superlattice structure.

The third layer, which is present in the p-type second layer, is generally a p-type nitride-based III-containing Al and Ga.
It is composed of a group V compound semiconductor, and more specifically, for example, p
Type Al _x Ga _1-x N (where 0 <x <1),
From the viewpoint of effectively suppressing the overflow of electrons injected into the active layer, p-type Al _x Ga _1-x N (where 0.15 ≦ x <1) is preferable.

From the viewpoint of preventing deterioration of the active layer due to diffusion of Mg, which is usually used as a p-type impurity of the p-type second layer, into the active layer, the p-type cladding layer of the active layer and the p-side cladding layer is formed. The distance to the second layer of is preferably 20 nm
As described above, more preferably 50 nm or more, and further preferably 100 nm.
nm or more. Also, according to a recent report, Ga
The diffusion distance of holes in N is about 0.28 μm (280 n
m), and in consideration of this, in order to reduce the probability of recombination with electrons and increase the efficiency of injecting holes into the active layer, the p-type second layer of the active layer and the p-side cladding layer is used. It is desirable that the distance from the layer to be less than this diffusion distance.

On the other hand, from the viewpoint of suppressing the diffusion of p-type impurities such as Mg from the p-type second layer of the p-side cladding layer to the active layer and preventing the deterioration of the active layer, the active layer is preferably used. At least one combination of layers having different band gaps or lattice constants exists between the layer and the second layer of the p-side cladding layer, or a superlattice composed of layers having different atomic composition ratios At least one layer is present in the structure, and this is used as a lattice strain layer to prevent Mg diffusion.

Typically, the nitride-based III-V group compound semiconductor forming the barrier layer of the active layer is In _x Ga _{1 -x} N.
(However, 0 <x <1), and the nitride-based III-V group compound semiconductor forming the well layer of the active layer is In _y Ga.
_1-y N (where 0 <y <1 and y> x).

The nitride-based III-V group compound semiconductor is generally at least one group III element selected from the group consisting of Ga, Al, In and B, and at least N.
And a group V element containing As or P as the case may be, and specific examples thereof include GaN, InN, and Al.
N, AlGaN, InGaN, AlGaInN and the like.

[0016] Typically, a growth mask is formed on the underlayer, and a ridge is selectively grown on the underlayer in the opening of the growth mask. The growth mask is generally formed of an insulating film. Specific examples of the insulating film include a silicon dioxide (SiO ₂ ) film, a silicon nitride (Si ₃ N ₄ ) film,
For example, a silicon oxynitride (SiON) film is used. The underlying layer for the selective growth may be the first layer, or may be an undoped or n-type layer obtained by growing the first layer to an intermediate thickness. When an undoped or other n-type layer is provided in contact with the first layer between the second layer and the second layer, it may be the other layer. Ridge
For example, the upper layer portion of the first layer, the second layer and the third layer are included, and specifically, for example, the upper layer portion of the first layer, the second layer, the third layer and the p-type contact are included. Consists of layers. Alternatively, the ridge is composed of the second layer, the third layer and the p-type contact layer.

A second aspect of the present invention is a nitride-based III-type structure having an active layer sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth. In a semiconductor light emitting device using a group V compound semiconductor, a p-side cladding layer is an undoped or n-type first layer and a p-type impurity-doped p-type impurity layer in order from the active layer side.
A second layer of the mold, the growth interface between the ridge and the underlayer is in contact with the first layer or between the first layer and the second layer and is undoped or n-type other. When the above layer is provided, it is included in the first layer or other layers. In the second invention of the present invention, what has been described in connection with the first invention is established unless it goes against the nature thereof.

A third aspect of the present invention is a semiconductor light emitting device having a structure in which an active layer is sandwiched between an n-side clad layer and a p-side clad layer and a ridge structure formed by selective growth. The side cladding layer is composed of an undoped or n-type first layer and a p-type second layer doped with p-type impurities in order from the active layer side, and the growth interface between the ridge and the underlayer is the first layer. Alternatively, when an undoped or other n-type layer is provided between the first layer and the second layer in contact with the first layer, it is included in the first layer or the other layer. It is what

Here, this semiconductor light emitting device may basically use any semiconductor, and in addition to using a nitride-based III-V group compound semiconductor,
lGaAs type semiconductor, AlGaInP type semiconductor, InG
Various III-V group compound semiconductors such as aAsP-based semiconductors and GaInNAs-based semiconductors, II-VI group compound semiconductors such as ZnSe-based semiconductors, and those using diamond or the like may be used. In the third invention of the present invention, what has been described in relation to the first invention is satisfied unless the property is violated.

A fourth aspect of the present invention has a structure in which an active layer is sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth. Comprises an undoped or n-type first layer and a p-type second layer doped with a p-type impurity in this order from the active layer side, and the second layer has a bandgap smaller than that of the second layer. A method for manufacturing a semiconductor light-emitting device using a nitride-based III-V group compound semiconductor having a large third layer, the method comprising: growing a first layer, and then forming a predetermined opening on the first layer. And a step of growing an undoped or n-type layer, a second layer and a third layer on the first layer in the opening of the growth mask. It is a thing.

A fifth aspect of the present invention has a structure in which an active layer is sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth. Comprises an undoped or n-type first layer and a p-type second layer doped with a p-type impurity in this order from the active layer side, and the second layer has a bandgap smaller than that of the second layer. A method for manufacturing a semiconductor light-emitting device using a nitride-based III-V group compound semiconductor having a large third layer, the method comprising: growing a first layer, and then forming a predetermined opening on the first layer. And a step of growing a second layer and a third layer on the first layer in the opening of the growth mask.

A sixth aspect of the present invention has a structure in which an active layer is sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth. Of a nitride-based III-V group compound semiconductor, which comprises an undoped or n-type first layer and a p-type second layer doped with p-type impurities in order from the active layer side. A method of manufacturing, comprising the steps of forming a growth mask having a predetermined opening on the first layer after growing the first layer, and undoping the growth mask on the first layer in the opening of the growth mask. and a step of growing an n-type layer and a second layer.

A seventh aspect of the present invention has a structure in which an active layer is sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth. Of a nitride-based III-V group compound semiconductor, which comprises an undoped or n-type first layer and a p-type second layer doped with p-type impurities in order from the active layer side. A method of manufacturing, comprising: growing a first layer, then forming a growth mask having a predetermined opening on the first layer; and secondly forming a growth mask on the first layer in the opening of the growth mask. And a step of growing the layer.

An eighth aspect of the present invention has a structure in which an active layer is sandwiched between an n-side clad layer and a p-side clad layer and a ridge structure formed by selective growth. Is a method for manufacturing a semiconductor light-emitting device comprising an undoped or n-type first layer and a p-type second layer doped with a p-type impurity in this order from the active layer side. And then forming a growth mask having a predetermined opening on the first layer, and growing an undoped or n-type layer and a second layer on the first layer in the opening of the growth mask. It is characterized by having.

A ninth aspect of the present invention has a structure in which an active layer is sandwiched between an n-side clad layer and a p-side clad layer and a ridge structure formed by selective growth. Is a method for manufacturing a semiconductor light-emitting device comprising an undoped or n-type first layer and a p-type second layer doped with a p-type impurity in this order from the active layer side. And then forming a growth mask having a predetermined opening on the first layer, and growing a second layer on the first layer in the opening of the growth mask. To do.

In the fourth to ninth aspects of the present invention,
Typically, a p-type contact layer is further grown on the second layer of the p-side cladding layer. In the fourth to ninth inventions of the present invention, what has been described in relation to the first to third inventions is established unless the property is violated.

A tenth aspect of the present invention has a structure in which an active layer is sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth. Comprises an undoped or n-type first layer and a p-type second layer doped with a p-type impurity in this order from the active layer side, and the second layer has a bandgap smaller than that of the second layer. Nitride-based III-V with a large third layer
A method for manufacturing a semiconductor light emitting device using a group compound semiconductor, wherein the growth from the active layer to the third layer is carried out in a carrier gas atmosphere containing nitrogen as a main component and substantially not containing hydrogen. It is characterized by having done.

An eleventh invention of the present invention has a structure in which an active layer is sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth. Of a nitride-based III-V group compound semiconductor, which comprises an undoped or n-type first layer and a p-type second layer doped with p-type impurities in order from the active layer side. The manufacturing method is characterized in that the growth from the active layer to the first layer of the p-side cladding layer is performed in a carrier gas atmosphere containing substantially no hydrogen and nitrogen as a main component. To do.

A twelfth aspect of the present invention is a nitride-based III-type structure having an active layer sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth. In a semiconductor light emitting device using a group V compound semiconductor, a distance between an active layer and a p-type layer doped with a p-type impurity, which is the closest to the active layer, is 50 nm or more. is there.

In the twelfth aspect of the present invention, the distance between the active layer and the p-type layer closest to the active layer is p
From the viewpoint of more effectively preventing the deterioration of the active layer due to the diffusion of the p-type impurity doped in the p-type layer, 60 n is preferable.
m or more, and more preferably 100 nm or more. The distance between the active layer and the p-type layer is preferably as large as possible in order to prevent deterioration of the active layer due to diffusion of p-type impurities, but it is generally 500.
nm or less. The distance between the active layer and the p-type layer is typically 50 nm or more and 500 nm or less, and more typically 100 nm or more and 200 nm or less. The p-type layer closest to the active layer is, for example, a p-type layer having a bandgap larger than that of the p-side cladding layer, and is the same as the third layer in the first invention of the present invention.

A thirteenth invention of the present invention has a structure in which an active layer is sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth. The p-type layer closest to the active layer has a distance of 50 nm or more from the p-type impurity-doped p-type layer, and the p-type layer closest to the active layer has a larger band gap than the p-side cladding layer. A method for manufacturing a semiconductor light emitting device using a nitride-based III-V group compound semiconductor, which is a layer, having a band gap larger than that of a p-side clad layer from an active layer.
It is characterized in that the growth up to the mold layer is carried out in a carrier gas atmosphere containing substantially no hydrogen and having nitrogen as a main component.

In the tenth to thirteenth inventions of the present invention, what has been described in relation to the first invention is established unless the property is violated.

In the twelfth and thirteenth aspects of the present invention, even if the entire p-side cladding layer is a p-type layer,
Like the first to eleventh inventions, it may be composed of an undoped or n-type first layer and a p-type second layer. In the latter case, the matters described in connection with the first to eleventh inventions of the present invention are satisfied unless the property is violated.

In the tenth, eleventh and thirteenth inventions of the present invention, I from a layer containing In, for example, an active layer is used.
From the viewpoint of more effectively preventing the elimination of n, most preferably, an N ₂ gas atmosphere is used as a carrier gas atmosphere containing substantially no hydrogen and having nitrogen as a main component. On the other hand, regarding the growth of the p-type layer that is performed after the growth is performed using a carrier gas atmosphere containing nitrogen as a main component, which does not substantially contain hydrogen, from the viewpoint of reducing the resistance of the p-type layer. More preferably, a carrier gas atmosphere containing nitrogen and hydrogen as main components is used, and most preferably a mixed gas atmosphere of N ₂ and H ₂ is used.

Various substrates can be used as the substrate for growing the nitride-based III-V group compound semiconductor layer. Specifically, sapphire substrate, SiC substrate, Si substrate, GaAs substrate, GaP substrate, InP. In addition to a substrate, a spinel substrate, a silicon oxide substrate, a substrate made of a nitride-based III-V group compound semiconductor layer such as a thick GaN layer may be used.

As a growth method or a selective growth method for a nitride III-V compound semiconductor, for example, metal organic chemical vapor deposition (MOCVD), hydride vapor phase epitaxial growth or halide vapor phase epitaxial growth (H
VPE) or the like can be used. Nitride III-
In addition to these, for example, molecular beam epitaxy (MBE) or the like can be used as a method for growing all compound semiconductors including group V compound semiconductors.

The first to the first aspects of the present invention configured as described above
According to the ninth invention, the p-side cladding layer is composed of the undoped or n-type first layer and the p-type second layer doped with p-type impurities in order from the active layer side, and the ridge and the underlying layer are formed. The first layer or the other of the n-type is provided when the growth interface with the first layer or between the first layer and the second layer is provided in contact with the first layer. Since it is included in another layer, that is, the growth interface between the ridge and the underlayer is included in the n-type layer, the growth interface between the ridge and the underlayer is the surface of the p-type layer. In the case of forming Pd by selective growth, the growth interface is contaminated by n-type impurities, or defects acting as donors are generated at the growth interface, so that the vicinity of the growth interface becomes n-type and pn
There is essentially no problem of forming a p-structure, so that the series resistance of the entire p-side cladding layer can be reduced and the operating voltage can be reduced. In addition, the p-side cladding layer is formed from the active layer side in order from the undoped or n-type first layer and p
And a p-type second layer doped with a p-type impurity, the thickness of the p-side cladding layer that determines the quality of optical characteristics such as the optical confinement coefficient Γ and the p-type second layer that determines the magnitude of the operating voltage. Since the thickness of the second layer can be controlled independently, it has a low operating voltage and good optical characteristics (for example, F
It is possible to easily realize a semiconductor light emitting device (for example, θ ⊥ of FP is small). In other words, while ensuring the thickness of the p-side clad layer necessary to obtain a good optical field for the semiconductor light emitting device and obtain good optical characteristics, it is possible to obtain a high specific resistance p which causes an increase in operating voltage. The operating voltage can be reduced by making the mold layer as thin as possible. Further, since the distance between the active layer and the second layer can be made sufficiently large, diffusion of p-type impurities of the second layer into the active layer can be suppressed, and the deterioration of the active layer. Can be prevented. Furthermore, especially when the second layer has a p-type third layer having a bandgap larger than that of the second layer, the third layer causes electrons injected into the active layer to overflow. On the other hand, the distance between the third layer and the active layer, which have a composition greatly different from that of the active layer, can be freely designed, whereby the strain generated in the active layer can be relaxed. Therefore, deterioration of the active layer can be prevented.

Further, since all of the p-type layers such as the p-type second layer are contained in the ridge, the operating temperature of the semiconductor light emitting device rises, and the p-type second layer and other p-type layers. Even if the activation rate of the p-type impurities in the layer, for example, Mg is increased and the resistance of the p-type layer is lowered, the current leaking to the outside of the ridge can be significantly reduced. This particularly contributes to the improvement of the characteristic temperature T ₀ of the semiconductor laser.

According to the tenth and eleventh inventions of the present invention, in the tenth invention, growth from the active layer to the third layer is carried out, and in the eleventh invention, growth from the active layer to the p-layer is carried out.
Since the growth of the side cladding layer to the first layer is performed in a carrier gas atmosphere containing substantially no hydrogen and nitrogen as a main component, a layer containing In, for example, an In layer from the active layer Desorption can be effectively suppressed, and deterioration of the active layer can be prevented. On the other hand, the subsequent p-type layer can be grown with good crystallinity by growing it in a carrier gas atmosphere containing nitrogen and hydrogen as main components.

According to the twelfth aspect of the present invention,
Since the distance between the active layer and the p-type layer doped with the p-type impurity closest to the active layer is 50 nm or more,
Diffusion of p-type impurities doped in the p-type layer into the active layer can be greatly reduced, and deterioration of the active layer can be prevented.

According to the thirteenth invention of the present invention,
Since the growth from the active layer to the p-type layer having a bandgap larger than that of the p-side cladding layer is carried out in a carrier gas atmosphere containing nitrogen as a main component and containing substantially no hydrogen, In is contained. Desorption of In from a layer, for example, an active layer can be suppressed and deterioration of the active layer can be prevented. After that, the p-type layer is grown in a carrier gas atmosphere containing nitrogen and hydrogen as main components,
It can be grown with good crystallinity.

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In all the drawings of the embodiments, the same or corresponding parts are designated by the same reference numerals. FIG. 1 shows a GaN semiconductor laser according to the first embodiment of the present invention. This GaN-based semiconductor laser has a ridge structure and an SCH structure formed by selective growth. FIG. 2 is an enlarged view of the vicinity of the ridge portion of this GaN semiconductor laser. Further, FIG. 3 shows the energy band of this GaN-based semiconductor laser, particularly its conduction band.

As shown in FIG. 1, in the GaN semiconductor laser according to the first embodiment, a lateral crystal growth technique (for example, Appl) is formed on one main surface of the c-plane sapphire substrate 1.
According to iedPhysics Letters vol.75 (1999) pp.196-198), GaN-based semiconductor layers are laminated. Specifically, an undoped GaN buffer layer 2 formed by low temperature growth and an undoped GaN layer 3 thereon are formed on one main surface of the c-plane sapphire substrate 1.
A stripe extending in the <1-100> direction is formed, and an n-type GaN contact layer 4 is grown as a continuous layer using the undoped GaN layer 3 of this stripe as a seed crystal. Here, the surface layer portions of the c-plane sapphire substrate 1 on both sides of this stripe are also removed, and in this portion, the n-type GaN contact layer 4 has a structure floating from the c-plane sapphire substrate 1. Then, on the n-type GaN contact layer 4, an n-type AlGaN cladding layer 5 and undoped InGaN as an n-side optical waveguide layer.
Optical waveguide layer 6, for example undoped In _x Ga _1-x N / I
n _y Ga _1-y N active layer 7 of multiple quantum well structure, undoped InGaN optical waveguide layer 8 as p-side optical waveguide layer, and p
An undoped AlGaN clad layer 9 as a side clad layer is sequentially laminated. The undoped InGaN optical waveguide layer 6, the undoped InGaN optical waveguide layer 8 and the undoped AlGaN cladding layer 9 are all n ⁻ type. In these layers, dislocations 10 propagated from the seed crystal of lateral crystal growth to the upper layer and the association portion 11 of lateral growth from seed crystals adjacent to each other are formed.

The layers from the upper layer of the n-type GaN contact layer 4 to the undoped AlGaN cladding layer 9 have a mesa shape with a predetermined width as a whole. Undo A of this mesa
An insulating film 12 such as a SiO ₂ film, which is a growth mask, is provided on the lGaN cladding layer 9. A stripe-shaped opening 13 extending in the <1-100> direction, for example, is formed in a predetermined portion of the insulating film 12.
Then, in the opening 13, a thin undoped AlG layer is formed on the underlying undoped AlGaN cladding layer 9.
The aN cladding layer 9, the undoped InGaN layer 14, the p-type AlGaN electron blocking layer 15, the p-type AlGaN / GaN superlattice cladding layer 16 as the p-side cladding layer, and the p-type GaN contact layer 17 are sequentially stacked by selective growth. Ridge 18 extending in the <1-100> direction
Are formed. The width of the ridge 18, in other words, the width of the opening 13 of the insulating film 12 is 1.6 μm, for example.
The ridge 18, that is, the laser stripe portion is located above the low defect region between the dislocations 10 propagated from the seed crystal of the lateral crystal growth to the upper layer and the junctions 11 of the lateral growth of the seed crystals adjacent to each other. is doing. Undoped InG
The aN layer 14 is n ⁻ type. The p-type AlGaN / GaN superlattice cladding layer 16 is used as the p-side cladding layer in order to facilitate the passage of holes due to the tunnel effect.

Here, the undoped GaN buffer layer 2 has a thickness of, for example, 30 nm. The undoped GaN layer 3 has a thickness of 2 μm, for example. n-type GaN contact layer 4
Has a thickness of, for example, 4 μm, and is doped with, for example, silicon (Si) as an n-type impurity. n-type AlGaN
The cladding layer 5 has a thickness of, for example, 1.2 μm, is doped with, for example, Si as an n-type impurity, and has an Al composition ratio of, for example, 0.065. Undoped InGaN optical waveguide layer 6
Has a thickness of, for example, 30 nm, and the In composition ratio is, for example, 0.02. In addition, undoped In _x Ga _1-x N /
The active layer 7 of the In _y Ga _1-y N multiple quantum well structure is an In _x Ga _1-x N layer as a barrier layer and an In _y as a well layer.
Ga _1-y N layers are alternately laminated. For example, when the In _x Ga _1-x N layer as a barrier layer has a thickness of 7 nm, x =
0.02, the thickness of the In _y Ga _1-y N layer as a well layer is 3.5 nm, y = 0.08, and the number of wells is 3.

The undoped InGaN optical waveguide layer 8 has a thickness of, for example, 30 nm, and the In composition ratio is, for example, 0.02. The undoped AlGaN cladding layer 9 has a thickness of, for example, 100 nm, and the Al composition ratio is, for example, 0.025. The undoped InGaN layer 14 has a thickness of, for example, 5n.
m, and the In composition ratio is, for example, 0.02. p-type A
The lGaN electron block layer 15 has a thickness of, for example, 10 nm, and the Al composition ratio is, for example, 0.18. p-type AlG
The aN / GaN superlattice cladding layer 16 has, for example, an undoped AlGaN layer having a thickness of 2.5 nm as a barrier layer, and a Mg-doped GaN layer having a thickness of 2.5 nm as a well layer, for example. It has a laminated structure, the average Al composition ratio is, for example, 0.06, and the total thickness is, for example, 4
00 nm. The p-type GaN contact layer 17 has a thickness of, for example, 100 nm, and the p-type impurity is, for example, Mg.
Is doped.

A p-side electrode 19 is provided so as to extend over the insulating film 12 so as to cover the p-type GaN contact layer 17. The p-side electrode 19 has a structure in which a Pd film, a Pt film, and an Au film are sequentially stacked, and includes a Pd film, a Pt film, and an Au film.
The film thicknesses are, for example, 10 nm, 100 nm and 300 nm, respectively. Further, an insulating film 20 such as a SiO ₂ film having a thickness of 200 nm is formed so as to cover the entire mesa portion.
Is provided. This insulating film 20 is for electrical insulation and surface protection. An opening 21 is provided in a portion of the insulating film 20 above the ridge 18, and the p-side electrode 19 is exposed in the opening 21. On the other hand, an opening 22 is formed in a predetermined portion of the insulating film 20 adjacent to the mesa portion.
The n-side electrode 23 is in contact with the n-type GaN contact layer 4 through the opening 22. The n-side electrode 23 has a structure in which a Ti film, a Pt film, and an Au film are sequentially stacked, and the thicknesses of the Ti film, the Pt film, and the Au film are 10 nm, 50 nm, and 100 nm, respectively.

Next, a method of manufacturing the GaN-based semiconductor laser according to the first embodiment will be described. First, metal-organic chemical vapor deposition (M) is performed on a c-plane sapphire substrate 1 whose surface has been previously cleaned by thermal cleaning or the like.
After growing the undoped GaN buffer layer 2 at a temperature of, for example, about 500 ° C. by the OCVD method, the MOC is also performed.
The undoped GaN layer 3 is grown by the VD method at a growth temperature of 1000 ° C., for example.

Next, a SiO ₂ film (not shown) having a thickness of 100 nm, for example, is formed on the entire surface of the undoped GaN layer 3 by, for example, the CVD method, the vacuum deposition method, the sputtering method or the like, and then the SiO ₂ film is formed on the SiO ₂ film. A resist pattern (not shown) having a predetermined shape is formed by lithography, and using this resist pattern as a mask, for example, wet etching using a hydrofluoric acid-based etching solution, or CF
_The SiO ₂ film is etched and patterned by the RIE method using an etching gas containing fluorine such as ₄ or CHF ₃ . Next, using the SiO ₂ film having the predetermined shape as a mask, etching is performed by, eg, RIE until the surface layer portion of the c-plane sapphire substrate 1 is removed. As the etching gas for this RIE, for example, chlorine-based gas is used. By this etching, the stripe-shaped undoped GaN layer 3 serving as a seed crystal is formed. The extending direction of the stripe-shaped undoped GaN layer 3 is <1-100>.
Direction.

Next, Si used as an etching mask
After the O ₂ film is removed by etching, the n-type GaN contact layer 4 is grown by the above-described lateral crystal growth technique using the stripe-shaped undoped GaN layer 3 as a seed crystal. The growth temperature at this time is, eg, 1070 ° C.

Subsequently, on the n-type GaN contact layer 4, the n-type AlGaN cladding layer 5, the undoped InGaN optical waveguide layer 6 and the undoped G layer are formed by MOCVD.
An active layer 7, an undoped InGaN optical waveguide layer 8, and an undoped AlGaN cladding layer 9 having an a _1-x In _x N / Ga _1-y In _y N multiple quantum well structure are sequentially grown.

Next, the undoped AlGaN cladding layer 9
An insulating film 12 such as a SiO ₂ film having a thickness of 0.1 μm is formed on the entire surface of the substrate by, for example, a CVD method, a vacuum vapor deposition method, a sputtering method or the like, and then a mesa shape is formed on the insulating film 12 by lithography. A resist pattern (not shown) having a corresponding predetermined shape is formed, and using this resist pattern as a mask, for example, wet etching using a hydrofluoric acid-based etching solution, or CF ₄ or CHF
_The insulating film 12 is etched by the RIE method using an etching gas containing fluorine such as ₃ to form the opening 13. Next, using the insulating film 12 having the opening 13 as a growth mask, the thin undoped AlGaN cladding layer 9 and the undoped InGaN layer 1 are formed by, for example, the MOCVD method.
4, p-type AlGaN electron blocking layer 15, p-type AlGaN / GaN superlattice cladding layer 1 as p-side cladding layer
6 and p-type GaN contact layer 17 are sequentially grown selectively. Here, the selective growth of the p-type AlGaN / GaN superlattice cladding layer 16 is stopped when the cross-sectional shape becomes trapezoidal by lateral growth on the insulating film 12.

The growth temperature of these GaN-based semiconductor layers is
For example, the n-type AlGaN cladding layer 5 is 900-100.
0 ° C., undoped InGaN optical waveguide layer 6, active layer 7, undoped InGaN optical waveguide layer 8, undoped AlGaN
The clad layer 9, the undoped InGaN layer 14, and the p-type AlGaN electron block layer 15 are 780 ° C. and p-type AlG.
The temperature of the aN / GaN superlattice cladding layer 16 and the p-type GaN contact layer 17 is set to 900 to 1000 ° C.

The raw materials for growing these GaN-based semiconductor layers are
For example, as a Ga raw material, trimethylgallium ((C
H ₃ ) ₃ Ga, TMG), trimethyl aluminum ((CH ₃ ) ₃ Al, TMA) as a raw material for Al, and trimethyl indium ((CH ₃ ) ₃ I as a raw material for In.
n, TMI), and NH ₃ as a raw material of N. Regarding the dopant, for example, silane (SiH ₄ ) is used as the n-type dopant, and bis = methylcyclopentadienyl magnesium ((CH
₃ C ₅ H ₄ ) ₂ Mg) or bis = cyclopentadienyl magnesium ((C ₅ H ₅ ) ₂ Mg) is used.

As the carrier gas atmosphere during the growth of these GaN-based semiconductor layers, the n-type GaN contact layer 4 and the n-type AlGaN cladding layer 5 are mixed gas of N ₂ and H ₂ , undoped InGaN optical waveguide layer. 6 to the p-type AlGaN electron block layer 15 in an N ₂ gas atmosphere,
p-type AlGaN / GaN superlattice cladding layer 16 and p
The type GaN contact layer 17 uses a mixed gas of N ₂ and H ₂ . In this case, in the growth from the undoped InGaN optical waveguide layer 6 to the p-type AlGaN electron block layer 15, the carrier gas atmosphere is N ₂ atmosphere, and since H ₂ is not included in the carrier gas atmosphere, undoped InGa
Desorption of In from the N optical waveguide layer 6, the active layer 7, the undoped InGaN optical waveguide layer 8 and the undoped InGaN layer 14 can be suppressed, and deterioration of these layers can be prevented. Further, since the carrier gas atmosphere is a mixed gas atmosphere of N ₂ and H ₂ when the p-type AlGaN / GaN superlattice cladding layer 16 and the p-type GaN contact layer 17 are grown, these p-type layers have good crystallinity. Can be grown in.

Next, the c-plane sapphire substrate 1 on which the GaN-based semiconductor layer has been grown as described above is taken out from the MOCVD apparatus. Then, a Pd film, a Pt film, and an Au film are formed on the entire surfaces of the ridge 18 and the insulating film 12 by, for example, a vacuum evaporation method.
The films are sequentially formed to form the p-side electrode 19.

Next, for example, CVD is performed on the entire surface of the p-side electrode 19.
Method, vacuum deposition method, sputtering method, etc., a SiO ₂ film (not shown) having a thickness of 0.1 μm is formed, and then a resist having a predetermined shape corresponding to the shape of the mesa portion is formed on the SiO ₂ film by lithography. A pattern (not shown) is formed, and this resist pattern is used as a mask.
For example, the SiO ₂ film is etched and patterned by wet etching using a hydrofluoric acid-based etching solution or RIE using an etching gas containing fluorine such as CF ₄ or CHF ₃ . Next, S of this predetermined shape
Using the iO ₂ film as a mask, for example, n-type Ga is formed by the RIE method.
Etching is performed until the N contact layer 4 is reached. For example, chlorine-based gas is used as the etching gas for this RIE. By this etching, the upper layer portion of the n-type GaN contact layer 4, the n-type AlGaN cladding layer 5, the undoped InGaN optical waveguide layer 6, the active layer 7, and the undoped InGa.
The N optical waveguide layer 8, the undoped AlGaN cladding layer 9, the insulating film 12 and the p-side electrode 19 are patterned into a mesa shape.

Next, Si used as an etching mask
After removing the O ₂ film by etching, a CV
SiO by D method, vacuum deposition method, sputtering method, etc.
An insulating film 20 such as _two films is formed.

Next, a resist pattern (not shown) is formed by lithography to cover the surface of the insulating film 20 in the region excluding the n-side electrode formation region. Next, the opening 22 is formed by etching the insulating film 20 using this resist pattern as a mask.

Next, a Ti film, a Pt film, and an Au film are sequentially formed on the entire surface of the substrate with the resist pattern left, for example, by a vacuum deposition method, and then the resist pattern is formed on the Ti film, Pt. The film and the Au film are removed together (lift-off). As a result, the n-side electrode 23 contacting the n-type GaN contact layer 4 through the opening 22 of the insulating film 20 is formed. Next, the n-side electrode 23
Alloy treatment for making ohmic contact with.

Next, the ridge 18 is formed by lithography.
A resist pattern (not shown) having an opening for exposing the p-side electrode 19 near the upper part of is formed. Next, the opening 21 is formed by etching the insulating film 20 using this resist pattern as a mask, and the p-side electrode 19 is exposed in the opening 21.

After that, the substrate on which the laser structure is formed as described above is processed into a bar shape by cleaving or the like to form both resonator end faces, and after further applying end face coating to these resonator end faces, This bar is made into chips by cleavage or the like. From the above, the target ridge structure and SCH
A GaN-based semiconductor laser having a structure is manufactured.

In this GaN semiconductor laser, the undoped AlGaN cladding layer 9 and the p-type AlGaN / Ga are used.
The thickness t of the undoped AlGaN cladding layer 9 in the p-side cladding layer including the N superlattice cladding layer 16 was changed, and the operating voltage and aging deterioration rate at that time were obtained. Further, a graph of Table 1 is shown in FIGS. 4 and 5. Here, the operating voltage is 25 ° C. and the light output is 30 mW. The aging deterioration rate is at 60 ° C. and the light output is 30 mW.
Immediately after the start of aging, the increase rate of the operating current I _OP is high, so the I _OP increase rate in 10 to 100 hours was used. The initial operating current I _OP was set to 55 mA. Undoped AlGaN
The specific resistance of the clad layer 9 is about a fraction of ΩΩ, p-type Al
The resistivity of the GaN / GaN superlattice cladding layer 16 is 2Ωc
It is about m. The resonator length is 600 μm (0.06
cm), the width of the ridge 18 is 1.6 μm, and the total thickness of the p-side cladding layer is 500 nm.

[0064]                                   Table 1       −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−           t (nm) Operating voltage (V) Aging deterioration rate                                                   (%)       −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−               0 5.13 5.30             20 5.08 3.40             50 4.99 2.00           100 4.85 1.50           150 4.70 1.40           200 4.56 1.00           250 4.42 0.80           300 4.27 0.90           350 4.13 0.80           400 3.99 0.70       −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

Considering that the operating voltage at 30 mW (25 ° C.) is preferably 5 V or less and the aging deterioration rate is a practical level when the operating current increase rate is 20% or less after 5000 hours of operation, Table 1, FIG. From FIG. 5, it is understood that the thickness of the undoped AlGaN cladding layer 9 needs to be 50 nm or more in order to satisfy these conditions. Further, it can be seen that the operating voltage and the aging deterioration rate are reduced by increasing the thickness of the undoped AlGaN cladding layer 9.

According to this first embodiment, the following various advantages can be obtained. That is, the p-side clad layer has an undoped AlGaN clad layer 9 having a thickness of, for example, 105 nm and a thickness of, for example, 40 from the active layer 7 side.
0 nm p-type AlGaN / GaN superlattice cladding layer 12
And the growth interface between the ridge 18 formed by selective growth in the opening 13 of the insulating film 12 and the underlying layer is n ^−.
When the ridge is formed by selective growth as in the prior art in which the growth interface between the ridge and the underlying layer is the surface of the p-type layer, the growth interface between the ridge and the underlayer is formed by the n-type impurity. There is essentially no problem that the vicinity of the growth interface becomes n-type and a pnp structure is formed due to contamination or generation of defects that act as donors at the growth interface. Therefore, the series resistance of the entire p-side cladding layer can be reduced, and the operating voltage can be reduced. In addition, since the p-side clad layer is composed of the undoped AlGaN clad layer 9 and the p-type AlGaN / GaN superlattice clad layer 16 as described above, the thickness of the p-type AlGaN / GaN superlattice clad layer 16 having a high specific resistance by that amount Since the thickness of the p-side cladding layer can be reduced, the entire p-side clad layer can be made to have a total thickness of p-type AlGaN / G.
Compared to the case where the aN superlattice cladding layer 16 is used, G
The operating voltage of the aN semiconductor laser can be reduced by, for example, about 0.16V. Moreover, since the total thickness of the p-side cladding layer is about 500 nm, which is sufficiently large, the p-side light can be sufficiently confined and a good FFP can be obtained. That is, while maintaining the thickness of the p-side cladding layer necessary to obtain good optical characteristics, p-type AlGaN / GaN having a high specific resistance that causes an increase in operating voltage.
The operating voltage can be reduced by reducing the thickness of the superlattice cladding layer 16 by about 100 nm.

In addition, the active layer 7 and the p-type layer doped with Mg, that is, the p-type AlGaN electron blocking layer 15, the p-type AlGaN / GaN superlattice cladding layer 16 and the p-type G.
The distance from the aN contact layer 17 is undoped In
GaN optical waveguide layer 8 and undoped AlGaN cladding layer 9
Since the total thickness of the undoped InGaN layer 14 is 30 nm + 100 nm + 5 nm = 135 nm, it is possible to effectively suppress the diffusion of Mg in the p-type layer into the active layer 7 during crystal growth or aging. As a result, the deterioration of the active layer 7 due to the diffusion of Mg can be prevented, the aging deterioration rate of the GaN-based semiconductor laser can be reduced, and the reliability and the yield can be improved.

Since the undoped AlGaN clad layer 9 which is a lattice strain layer is provided between the active layer 7 and the Mg-doped p-type layer, Mg in the p-type layer diffuses into the active layer 7 as a result. This can be suppressed, and the deterioration of the active layer 7 can be prevented more effectively.

In addition, since the Mg-doped p-type layer generally has poorer crystallinity than the n-type layer and easily absorbs light, if the p-type layer is near the active layer 7, the light absorption coefficient α However, as described above, the active layer 7 and the p-type layer have 135
Since they are also separated by nm, α in the vicinity of the active layer 7 can be suppressed sufficiently low. This makes it possible to reduce the threshold current density J _th of the GaN-based semiconductor laser, and thus the threshold current I _th, and improve the slope efficiency. Further, since the p-type layer doped with Mg having poor crystallinity is sufficiently distant from the vicinity of the active layer 7 having high light density as described above, the active layer 7 exposed to light is
It is possible to improve the life and reliability of the GaN-based semiconductor laser, since the crystal in the vicinity of is unlikely to deteriorate.

Further, although there is a large difference in lattice constant between the p-type AlGaN electron block layer 15 having a large Al composition ratio of 0.18 and the active layer 7 formed of an InGaN layer, they have a large lattice constant of 135 nm as described above. Since they are separated from each other, strain generated in the active layer 7 due to this difference in lattice constant can be relaxed, and the luminous efficiency can be improved. Therefore, the threshold current density J _th and hence the threshold current I _th can be reduced by improving the quantum efficiency, and
The slope efficiency can be improved.

Further, the undoped AlGaN cladding layer 9
And the p-type AlGaN electron blocking layer 11 between the active layer 7 and
And the p-type AlGaN electron blocking layer 15 and the p-type AlGaN / GaN superlattice cladding layer 16 have a large difference in lattice constant. Also, these p-type AlGaN electron blocking layer 15 and p-type Al
The GaN / GaN superlattice cladding layer 16 can alleviate the strain generated in the active layer 7. Therefore, the threshold current density J _th of the GaN-based semiconductor laser and thus the threshold current I _th can be reduced, and the slope efficiency can be improved.

Further, by reducing the above-mentioned threshold current I _th , it is possible to improve the noise characteristics of the GaN semiconductor laser.

When the electrons injected into the active layer 7 pass through the active layer 7 and reach the undoped AlGaN cladding layer 9, the energy of the conduction band between the undoped InGaN optical waveguide layer 8 and the undoped AlGaN cladding layer 9 is increased. Electrons having an energy larger than the difference ΔE _C (FIG. 3) are reduced in energy by ΔE _C when jumping over the undoped AlGaN cladding layer 9. On the other hand, ΔE
Electrons having an energy smaller than that of _C cannot jump over the undoped AlGaN cladding layer 9, and therefore remain in the undoped InGaN optical waveguide layer 8. In this way, the energy and the number of electrons that jump over the undoped AlGaN cladding layer 9 are reduced, so that the slope efficiency of the GaN-based semiconductor laser can be improved. Further, it is possible to prevent electrons from overflowing when the GaN-based semiconductor laser is driven at high temperature and high output, and it is possible to reduce the operating current, the operating voltage, and the characteristic temperature T ₀ of the GaN-based semiconductor laser. .

Further, since all the p-type layers in the ridge 18 are contained inside the ridge 18, the operating temperature of the GaN semiconductor laser rises and Mg in these p-type layers is activated and p Even if the resistance of the mold layer is reduced, the current leaking to both sides of the ridge 18 can be suppressed to an extremely small value. Therefore, the characteristic temperature T ₀ of the GaN-based semiconductor laser can be made significantly higher than that of the conventional GaN-based semiconductor laser. Specifically, the characteristic temperature T _{0 is set} to, for example, 2
It can be increased to about 30K, which is about 90K higher than the characteristic temperature T ₀ of the conventional GaN-based semiconductor laser. The characteristic temperature T _{0 of} about 230K is a remarkably high value that has never been obtained even when compared with semiconductor lasers of other material systems. Furthermore, the slope of the optical output-current characteristic,
That is, the slope efficiency of this GaN-based semiconductor laser can be made considerably larger than that of the conventional GaN-based semiconductor laser.

Further, the distance between the active layer 7 and the surface of the undoped AlGaN cladding layer 9 (interface between the insulating film 12 and the undoped AlGaN cladding layer 9) on both sides of the ridge 18 is equal to the optical distance of the GaN semiconductor laser. Characteristic,
In particular, it affects the lateral refractive index difference Δn in the ridge portion 18 and influences the manufacturing yield of the GaN-based semiconductor laser, but since this distance can be controlled accurately by crystal growth, there are variations in manufacturing. Therefore, the manufacturing yield of GaN-based semiconductor lasers can be improved.

Further, the ridge width is determined by the width of the opening 13 of the insulating film 12. Since the width of the opening 13 can be controlled accurately and easily by wet etching of the insulating film 12, RIE is performed. The productivity is higher than in the case where the ridge is formed by dry etching such as, and the manufacturing cost of the GaN-based semiconductor laser can be reduced.

In addition, the p-type AlGaN electron block layer 15
Since the activation energy of holes is high, most of the holes are inactive at room temperature. However, as the temperature increases, holes are activated and the electron blocking effect of the p-type AlGaN electron block layer 15 increases. However, in the conventional GaN-based semiconductor laser, since the amount of current leakage to both sides of the ridge is large, it can be inferred that the above effect was hard to see. On the other hand, according to this GaN-based semiconductor laser, the amount of current leakage to both sides of the ridge 18 is extremely small as described above, which results in p-type AlGa.
The electron blocking effect of the N electron blocking layer 15 is high,
Electron overflow can be effectively prevented even at high temperature and high output driving.

As described above, the leakage current during high temperature driving, that is, the reactive current is reduced, so that the threshold current I _th can be reduced and the characteristic temperature T ₀ can be improved. Ga that can be done and has low noise even at high temperature
It is possible to realize an N-based semiconductor laser.

Further, as described above, the so-called droop characteristic can be improved by remarkably improving the characteristic temperature T ₀ . This droop characteristic is an important parameter when applying a GaN-based semiconductor laser to a light source such as a laser beam printer. In addition, even when a plurality of GaN-based semiconductor lasers are integrated adjacent to each other on the same substrate, the characteristic temperature T ₀ of the GaN-based semiconductor lasers is remarkably high, which results in thermal crossing between these GaN-based semiconductor lasers. Since the talk can be kept low, it is also suitable for applications such as multi-beam lasers.

Since a part of the p-side clad layer is composed of the undoped AlGaN clad layer 9, the p-type layer existing in the part on the p-side of the active layer 7 is small as a whole, so that the active layer 7 overflows. The probability that the generated electrons are trapped by recombination centers in the p-type layer and non-radiative recombination is small. Assuming that the higher the temperature, the higher the probability that electrons will be trapped in the p-type layer.
The structure of the semiconductor laser is considered to be effective in reducing the reactive current.

Further, due to the improvement of the slope efficiency and the improvement of the temperature characteristic described above, electrons are less likely to be injected into the Mg-doped p-type layer having poor crystallinity due to overflow to break the crystal. The reliability and the life of the semiconductor laser can be improved.

Further, in the growth from the undoped InGaN optical waveguide layer 6 to the p-type AlGaN electron block layer 11, the carrier gas atmosphere is N ₂ atmosphere, and since H ₂ is not contained in the carrier gas atmosphere, especially from the active layer 7. I
Desorption of n can be suppressed, its deterioration can be prevented, and the reliability and life of the GaN-based semiconductor laser can be improved.

As described above, GaN having a low operating voltage and a low threshold current, good temperature characteristics, long life and high reliability.
System semiconductor laser can be realized. The GaN-based semiconductor laser according to the first embodiment can reduce the operating current and the operating voltage at the time of driving at high temperature and high output, and has a long life, so that it is particularly used as a high-output semiconductor laser for writing on an optical disc. It is suitable for use.

Next, G according to the second embodiment of the present invention
The aN semiconductor laser will be described. Figure 6 shows this Ga
The energy band figure of a N type semiconductor laser is shown. As shown in FIG. 6, in the GaN-based semiconductor laser according to the second embodiment, the undoped AlGaN / GaN superlattice cladding layer 24 is used instead of the undoped AlGaN cladding layer 9 in the GaN-based semiconductor laser according to the first embodiment. Is provided. Where this undoped A
The lGaN / GaN superlattice cladding layer 24 uses, for example, an undoped AlGaN layer having a thickness of 2.5 nm as a barrier layer,
For example, it has a structure in which a GaN layer having a thickness of 2.5 nm is used as a well layer and these are alternately laminated, the average Al composition ratio is 0.025 to 0.10, and the total thickness is 100, for example.
~ 500 nm. The other configurations are similar to those of the GaN-based semiconductor laser according to the first embodiment, and thus the description thereof will be omitted. The method for manufacturing the GaN-based semiconductor laser is the same as the method for manufacturing the GaN-based semiconductor laser according to the first embodiment, and therefore description thereof will be omitted.

According to the second embodiment, the undoped layer in the p-side cladding layer is undoped AlGaN / G.
Since it is composed of the aN superlattice cladding layer 24,
This undoped AlGa is injected from the p-side electrode 19 side.
The holes that have reached the N / GaN superlattice clad layer 24 easily pass through the undoped AlGaN / GaN superlattice clad layer 24 by the tunnel effect and are injected into the active layer 7, so that the holes are injected into the active layer 7. Becomes easier and Ga
The operating voltage of the N-based semiconductor laser can be further reduced. Further, the hetero interface existing in the undoped AlGaN / GaN superlattice clad layer 24 can more effectively prevent the Mg in the p-type layer from diffusing into the active layer 7, and further prevent the deterioration of the active layer 7. It can be effectively prevented. Other advantages are similar to those of the first embodiment.

Next, G according to the third embodiment of the present invention
The aN semiconductor laser will be described. The GaN-based semiconductor laser according to the third embodiment has a structure basically similar to that of the GaN-based semiconductor laser according to the first embodiment, except that an undoped InGaN optical waveguide layer 8 and a p-type A laser are provided.
The thickness of the lGaN / GaN superlattice cladding layer 16 is different from that of the GaN-based semiconductor laser according to the first embodiment. Specifically, in the GaN-based semiconductor laser according to the first embodiment, the undoped InGaN optical waveguide layer 8 has a thickness of, for example, 30 nm, and the p-type AlGaN / GaN superlattice cladding layer 16 has a thickness of, for example, 400 nm. On the other hand, in the GaN semiconductor laser according to the third embodiment,
The thickness of the undoped InGaN optical waveguide layer 8 is, for example, 24.
5 nm, p-type AlGaN / GaN superlattice cladding layer 16
Has a thickness of 500 nm, for example. Other configurations are similar to those of the GaN-based semiconductor laser according to the first embodiment. The method of manufacturing the GaN-based semiconductor laser is the same as the method of manufacturing the GaN-based semiconductor laser according to the first embodiment, and thus the description thereof will be omitted.

According to the third embodiment, the same advantages as those of the first embodiment can be obtained.

Next, G according to the fourth embodiment of the present invention.
The aN semiconductor laser will be described. Figure 7 shows this Ga
The energy band of an N-based semiconductor laser, particularly its conduction band, is shown. As shown in FIG. 7, in the GaN-based semiconductor laser according to the fourth embodiment, p-type AlGaN / G is used.
The p-type AlGaN electron block layer 15 is provided in the aN superlattice cladding layer 16. That is, in the GaN-based semiconductor laser according to the first embodiment, p-type AlG
The aN electron block layer 15 is the undoped InGaN layer 14.
The p-type AlGaN electron blocking layer 15 is provided at the interface between the p-type AlGaN / GaN superlattice clad layer 16 and the p-type AlGaN / GaN superlattice clad layer 16 in the fourth embodiment. It is provided apart from the undoped InGaN layer 14 in the superlattice cladding layer 16. Here, the p-type AlGaN / GaN superlattice cladding layer 16 existing between the undoped AlGaN cladding layer 9 and the p-type AlGaN electron blocking layer 15 has a thickness of, for example, about 10 to 50 nm. Other configurations are similar to those of the GaN-based semiconductor laser according to the first embodiment. The method of manufacturing the GaN-based semiconductor laser is the same as the method of manufacturing the GaN-based semiconductor laser according to the first embodiment, and thus the description thereof will be omitted. According to the fourth embodiment, the same advantages as those of the first embodiment can be obtained.

Next, G according to the fifth embodiment of the present invention
1 shows an aN semiconductor laser. This GaN-based semiconductor laser has a ridge structure and SCH formed by selective growth.
Although it has a structure, it differs from the first to fourth embodiments in that an n-type GaN substrate is used as the substrate. This G in Figure 8
1 shows an aN semiconductor laser.

As shown in FIG. 8, in the GaN-based semiconductor laser according to the fifth embodiment, for example, S as an n-type impurity is formed on the n-type GaN substrate 25 having a c-plane orientation.
An i-doped n-type GaN layer 26 is provided as a buffer layer (different from the buffer layer formed by low-temperature growth), on which an n-type AlGaN cladding layer 5 and an undoped InGaN optical waveguide layer as an n-side optical waveguide layer are provided. 6, for example, an undoped In _x Ga _1-x N / In _y Ga _1-y N multiple quantum well structure active layer 7, and undoped I as a p-side optical waveguide layer
An nGaN optical waveguide layer 8 and an undoped AlGaN cladding layer 9 as a p-side cladding layer are sequentially laminated.

On the undoped AlGaN cladding layer 9, an insulating film 12 such as a SiO ₂ film, which is a growth mask, is provided. A stripe-shaped opening 13 extending in the <1-100> direction, for example, is formed in a predetermined portion of the insulating film 12. Then, in the opening 13, on the underlying undoped AlGaN cladding layer 9, a thin undoped AlGaN cladding layer 9, an undoped InGaN layer 14, a p-type AlGaN electron block layer 15, and a p-type AlGaN / Ga as a p-side cladding layer.
The N superlattice cladding layer 16 and the p-type GaN contact layer 17 are sequentially stacked by selective growth, and for example, <1-10
A ridge 18 extending in the 0> direction is formed.

A p-side electrode 19 is provided to extend over the insulating film 12 so as to cover the p-type GaN contact layer 17. On the other hand, the n-side electrode 23 is in contact with the back surface of the n-type GaN substrate 25. Except for the above, the description is omitted because it is the same as the first embodiment.

Next, a method of manufacturing the GaN semiconductor laser according to the fifth embodiment will be described. First, n-type Al is formed by MOCVD on the n-type GaN substrate 25 whose surface is previously cleaned by thermal cleaning or the like.
GaN cladding layer 5, undoped InGaN optical waveguide layer 6, undoped Ga _1-x In _x N / Ga _1-y In _y N
An active layer 7, an undoped InGaN optical waveguide layer 8 and an undoped AlGaN cladding layer 9 having a multiple quantum well structure are sequentially grown.

Next, the undoped AlGaN cladding layer 9
After the insulating film 12 is formed on the entire surface of, the opening 13 is formed in the insulating film 12 by etching. Next, this opening 1
3 is used as a growth mask, for example, MO
The thin undoped AlGaN cladding layer 9, the undoped InGaN layer 14, the p-type AlGaN electron blocking layer 15, and the p-type AlGa as the p-side cladding layer are formed by the CVD method.
The N / GaN superlattice cladding layer 16 and the p-type GaN contact layer 17 are sequentially grown selectively.

Next, the c-plane sapphire substrate 1 on which the GaN-based semiconductor layer has been grown as described above is taken out from the MOCVD apparatus. Then, the p-side electrode 19 is formed on the entire surfaces of the ridge 18 and the insulating film 12. Next, the n-type GaN substrate 2
An n-side electrode 23 is formed on the back surface of No. 5.

After that, the substrate on which the laser structure is formed as described above is processed into a bar shape by cleaving or the like to form both resonator end faces, and after further applying end face coating to these resonator end faces, This bar is made into chips by cleavage or the like. From the above, the target ridge structure and SCH
A GaN-based semiconductor laser having a structure is manufactured. Other than the above, the method of manufacturing the GaN-based semiconductor laser is the same as that of the first embodiment.

According to the fifth embodiment, the same advantages as those of the first embodiment can be obtained, and, for example, Ga
Similar to the As semiconductor laser, the p-side electrode 19 and the n-side electrode 23 can be formed on the front surface and the back surface of the substrate, respectively, so that a bonding apparatus used for assembling a GaAs semiconductor laser is used. Therefore, it is not necessary to introduce an assembling device such as a special bonding device, and the manufacturing cost of the GaN-based semiconductor laser can be reduced accordingly. Furthermore, since the chip size can be reduced, the manufacturing cost of the GaN-based semiconductor laser can also be reduced accordingly.

The embodiments of the present invention have been specifically described above, but the present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the technical idea of the present invention.

For example, the numerical values, structures, shapes, substrates, raw materials, processes, etc. mentioned in the above-mentioned first to fifth embodiments are merely examples, and if necessary, different numerical values, structures, shapes. , Substrates, raw materials, processes, etc. may be used.

Specifically, for example, in the above-described first to fifth embodiments, the n-type layer forming the laser structure is first laminated on the substrate, and the p-type layer is laminated thereon. However, the stacking order may be reversed, and the p-type layer may be first stacked on the substrate, and the n-type layer may be stacked thereon.

In the first to fifth embodiments described above, the undoped InGaN optical waveguide layer 6 as the n-side optical waveguide layer and the undoped InGa as the p-side optical waveguide layer.
Although the N optical waveguide layer 8 has the same composition as each other, these undoped InGaN optical waveguide layer 6 and undoped InGa
The composition of the N optical waveguide layer 8 may be different from each other as long as good optical characteristics are obtained. For example, undoped In
The In composition of the GaN optical waveguide layer 8 may be lower than that of the undoped InGaN optical waveguide layer 6. Furthermore, if necessary,
InGa as a material for the n-side optical waveguide layer and the p-side optical waveguide layer
You may use the thing of composition different from N, for example, GaN.

Further, although the c-plane sapphire substrate is used in the above-mentioned first to fourth embodiments, a SiC substrate, a Si substrate, a spinel substrate or the like may be used if necessary. Further, an AlN buffer layer or an AlGaN buffer layer may be used instead of the GaN buffer layer.

Further, in the above-mentioned first to fifth embodiments, the case where the present invention is applied to the SCH semiconductor laser of the SCH structure has been described. However, the present invention is applicable to, for example, a DH (Double Heterostructure) structure. It may be applied not only to a GaN-based semiconductor laser but also to a GaN-based light emitting diode.

Further, in the above-mentioned first to fifth embodiments, in the p-type AlGaN / GaN superlattice cladding layer 12, the AlGaN layer is not doped with Mg.
If necessary, the AlGaN layer may also be doped with Mg, or the GaN layer may be undoped with Mg.
Mg may be doped only in the lGaN layer.

[0105]

As described above, according to the present invention, the p-side cladding layer is the undoped or n-type first layer and the p-type second layer in which p-type impurities are doped in this order from the active layer side. Layer, and the growth interface between the ridge and the underlying layer is the first
Layer, or when an undoped or n-type other layer is provided between the first layer and the second layer in contact with the first layer, the layer is included in the first layer or this other layer. As a result, there is essentially no problem that the vicinity of the growth interface becomes n-type and a pnp structure is formed. Therefore, the series resistance of the entire p-side cladding layer can be reduced and the operating voltage can be reduced. Further, since the p-side cladding layer is composed of the undoped or n-type first layer and the p-type second layer doped with p-type impurities in this order from the active layer side, The thickness of the p-type clad layer having a high specific resistance, which causes an increase in operating voltage, can be obtained while securing the thickness of the p-side cladding layer necessary for obtaining a good optical field and good optical characteristics. The operating voltage of the semiconductor light emitting element can be reduced by making it as thin as possible. In addition, since the distance between the active layer and the second layer can be made sufficiently large, the p-type impurity of the second layer can be prevented from diffusing into the active layer and the deterioration of the active layer can be prevented. . Furthermore, especially when the second layer has a p-type third layer having a bandgap larger than that of the second layer, the third layer causes the electrons injected into the active layer to overflow. Can be suppressed.

Further, since the p-type layer in the ridge portion is entirely contained within the ridge, it is possible to effectively prevent the current injected during the operation of the semiconductor light emitting element from leaking to the outside of the ridge. As a result, it is possible to obtain a remarkably high characteristic temperature as compared with the conventional one, and it is possible to obtain an extremely good temperature characteristic.

Since the growth of the specific layer including the In-containing layer is carried out in a carrier gas atmosphere containing substantially no hydrogen and nitrogen as the main component, the In-containing layer, For example, desorption of In from the active layer can be effectively suppressed, deterioration of the active layer can be prevented, and reliability and life of the semiconductor light emitting device can be improved.

Further, p, which is the closest to the active layer,
The distance from the p-type layer doped with the type impurities is 50 n
Since it is m or more, the diffusion of the p-type impurity doped in the p-type layer into the active layer can be significantly reduced,
The deterioration of the active layer can be prevented, and the reliability and life of the semiconductor light emitting device can be improved.

[Brief description of drawings]

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

FIG. 2 is an enlarged cross-sectional view of a main part of the GaN-based semiconductor laser according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram showing an energy band structure of a GaN-based semiconductor laser according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram showing a change in operating voltage according to the thickness of an undoped layer of the p-side cladding layer in the GaN-based semiconductor laser according to the first embodiment of the present invention.

FIG. 5 is a schematic diagram showing changes in the aging deterioration rate depending on the thickness of the undoped layer of the p-side cladding layer in the GaN-based semiconductor laser according to the first embodiment of the present invention.

FIG. 6 is a schematic diagram showing an energy band structure of a GaN-based semiconductor laser according to a second embodiment of the present invention.

FIG. 7 is a schematic diagram showing an energy band structure of a GaN-based semiconductor laser according to a fourth embodiment of the present invention.

FIG. 8 is a sectional view showing a GaN semiconductor laser according to a fifth embodiment of the present invention.

FIG. 9 is a conventional G in which a ridge structure is formed by selective growth.
It is a sectional view showing the important section of an aN system semiconductor laser.

FIG. 10 is a cross-sectional view for explaining a problem of a conventional GaN-based semiconductor laser that forms a ridge structure by selective growth.

[Explanation of symbols]

1 ... c-plane sapphire substrate, 4 ... n-type GaN contact layer, 5 ... n-type AlGaN cladding layer, 6 ...
-Undoped InGaN optical waveguide layer, 7 ... Active layer, 8
... Undoped InGaN optical waveguide layer, 9 ... Undoped AlGaN cladding layer, 12 ... Insulating film, 13 ...
..Aperture, 14 ... Undoped InGaN layer, 15.
..P-type AlGaN electron blocking layer, 16 ... P-type A
lGaN / GaN superlattice cladding layer, 17 ... p-type G
aN contact layer, 18 ... ridge, 19 ... p-side electrode, 20 ... insulating film, 23 ... n-side electrode, 24 ...
..Undoped AlGaN / GaN superlattice cladding layers,
25 ... n-type GaN substrate

Claims (143)

[Claims] 1. A nitride-based III-V group compound semiconductor having a structure in which an active layer is sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth is used. In the semiconductor light emitting device, the p-side cladding layer is composed of an undoped or n-type first layer and a p-type second layer doped with p-type impurities in order from the active layer side, and the second layer The second layer
A third layer having a bandgap larger than that of the first layer, and the growth interface between the ridge and the underlayer is the first layer or the first layer between the first layer and the second layer. A semiconductor light emitting device, characterized in that when an undoped or other n-type layer is provided in contact with the layer, it is included in the first layer or the other layer. 2. An n-side optical waveguide layer is provided between the n-side cladding layer and the active layer, and a p-side optical waveguide layer is provided between the p-side cladding layer and the active layer. The semiconductor light emitting device according to claim 1, wherein: 3. The semiconductor light emitting device according to claim 1, wherein the thickness of the second layer of the p-side cladding layer is greater than 0 nm and 550 nm or less. 4. The semiconductor light emitting device according to claim 1, wherein the thickness of the second layer of the p-side cladding layer is greater than 0 nm and 450 nm or less. 5. The semiconductor light emitting device according to claim 1, wherein the thickness of the second layer of the p-side cladding layer is 390 nm or more and 550 nm or less. 6. The semiconductor light emitting device according to claim 1, wherein the thickness of the second layer of the p-side cladding layer is 400 nm or more and 530 nm or less. 7. The semiconductor light emitting device according to claim 1, wherein the thickness of the first layer of the p-side cladding layer is greater than 0 nm and 500 nm or less. 8. The semiconductor light emitting device according to claim 1, wherein the thickness of the first layer of the p-side cladding layer is 50 nm or more. 9. The semiconductor light emitting device according to claim 1, wherein the thickness of the first layer of the p-side cladding layer is 50 nm or more and 400 nm or less. 10. The semiconductor light emitting device according to claim 1, wherein the thickness of the first layer of the p-side cladding layer is 70 nm or more and 400 nm or less. 11. The semiconductor light emitting device according to claim 1, wherein the thickness of the first layer of the p-side cladding layer is 90 nm or more and 400 nm or less. 12. The semiconductor light emitting device according to claim 1, wherein the thickness of the first layer of the p-side cladding layer is 50 nm or more and 300 nm or less. 13. The semiconductor light emitting device according to claim 1, wherein the thickness of the first layer of the p-side cladding layer is 70 nm or more and 300 nm or less. 14. The semiconductor light emitting device according to claim 1, wherein the thickness of the first layer of the p-side cladding layer is 90 nm or more and 300 nm or less. 15. The semiconductor light emitting device according to claim 1, wherein the thickness of the first layer of the p-side cladding layer is 50 nm or more and 200 nm or less. 16. The semiconductor light emitting device according to claim 1, wherein the thickness of the first layer of the p-side cladding layer is 70 nm or more and 200 nm or less. 17. The semiconductor light emitting device according to claim 1, wherein the thickness of the first layer of the p-side cladding layer is 90 nm or more and 200 nm or less. 18. The semiconductor light emitting device according to claim 1, wherein the thickness of the first layer of the p-side cladding layer is 70 nm or more and 130 nm or less. 19. The semiconductor light emitting device according to claim 1, wherein the thickness of the first layer of the p-side cladding layer is 90 nm or more and 110 nm or less. 20. The semiconductor light emitting device according to claim 1, wherein the n-side optical waveguide layer and the p-side optical waveguide layer have a thickness of more than 0 nm and 50 nm or less. 21. The semiconductor light emitting device according to claim 1, wherein the first layer of the p-side cladding layer has a superlattice structure. 22. The semiconductor light emitting device according to claim 1, wherein the p-side cladding layer has a superlattice structure. 23. The semiconductor light emitting device according to claim 1, wherein the third layer is made of a p-type nitride-based III-V group compound semiconductor containing Al and Ga. 24. The third layer is p-type Al _x Ga _{1 -x} N
(However, 0 <x <1), The semiconductor light emitting element of Claim 1 characterized by the above-mentioned. 25. The third layer is p-type Al _x Ga _{1 -x} N
(However, 0.15 ≦ x <1). 3. The semiconductor light emitting device according to claim 1, wherein 26. The semiconductor light emitting device according to claim 1, wherein a distance between the active layer and the second layer of the p-side cladding layer is 20 nm or more. 27. The semiconductor light emitting device according to claim 1, wherein a distance between the active layer and the second layer of the p-side cladding layer is 50 nm or more. 28. The semiconductor light emitting device according to claim 1, wherein the distance between the active layer and the second layer of the p-side cladding layer is 100 nm or more. 29. The semiconductor light emitting device according to claim 1, wherein a distance between the active layer and the second layer of the p-side cladding layer is 280 nm or less. 30. The semiconductor light emitting device according to claim 1, wherein a distance between the active layer and the second layer of the p-side cladding layer is 100 nm or more and 180 nm or less. 31. The semiconductor light emitting device according to claim 1, wherein a distance between the active layer and the second layer of the p-side cladding layer is 120 nm or more and 160 nm or less. 32. The semiconductor light emitting device according to claim 1, wherein a distance between the active layer and the second layer of the p-side cladding layer is 130 nm or more and 150 nm or less. 33. At least one combination of layers having different band gaps or lattice constants exists between the active layer and the second layer of the p-side cladding layer. The semiconductor light-emitting device as described above. 34. At least one superlattice structure consisting of layers having different atomic composition ratios is present between the active layer and the second layer of the p-side cladding layer. 1. The semiconductor light emitting device according to 1. 35. The semiconductor light emitting device according to claim 1, wherein a growth mask is formed on the underlayer, and the ridge is selectively grown on the underlayer in the opening of the growth mask. 36. The semiconductor light emitting device according to claim 35, wherein the growth mask is an insulating film. 37. The semiconductor light emitting device according to claim 1, wherein the underlayer is the first layer. 38. The ridge is an upper portion of the first layer,
The semiconductor light emitting device according to claim 1, comprising the second layer and the third layer. 39. The ridge is an upper layer portion of the first layer,
The semiconductor light emitting device according to claim 1, comprising the second layer, the third layer and a p-type contact layer. 40. The ridge comprises the second layer and the third layer.
2. The semiconductor light emitting device according to claim 1, wherein the semiconductor light emitting device and the p-type contact layer. 41. A nitride-based III-V group compound semiconductor having a structure in which an active layer is sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth is used. In the semiconductor light emitting device, the p-side cladding layer is composed of an undoped or n-type first layer and a p-type second layer doped with a p-type impurity in this order from the active layer side, and the ridge and the underlying layer. If an undoped or n-type other layer is provided in contact with the first layer between the first layer and the first layer and the second layer, the growth interface with A semiconductor light-emitting device characterized by being contained in one layer or another layer. 42. An n-side optical waveguide layer is provided between the n-side cladding layer and the active layer, and a p-side optical waveguide layer is provided between the p-side cladding layer and the active layer. The semiconductor light emitting device according to claim 41, wherein: 43. The semiconductor light emitting device according to claim 41, wherein the thickness of the second layer of the p-side cladding layer is greater than 0 nm and 550 nm or less. 44. The semiconductor light emitting device according to claim 41, wherein the thickness of the second layer of the p-side cladding layer is greater than 0 nm and 450 nm or less. 45. The semiconductor light emitting device according to claim 41, wherein the thickness of the second layer of the p-side cladding layer is 390 nm or more and 550 nm or less. 46. The semiconductor light emitting device according to claim 41, wherein the thickness of the second layer of the p-side cladding layer is 400 nm or more and 530 nm or less. 47. The semiconductor light emitting device according to claim 41, wherein the thickness of the first layer is 50 nm or more. 48. The semiconductor light emitting device according to claim 41, wherein the thickness of the first layer of the p-side cladding layer is 50 nm or more and 500 nm or less. 49. The semiconductor light emitting device according to claim 41, wherein the thickness of the first layer of the p-side cladding layer is 50 nm or more and 400 nm or less. 50. The semiconductor light emitting device according to claim 41, wherein the thickness of the first layer of the p-side cladding layer is 70 nm or more and 400 nm or less. 51. The semiconductor light emitting device according to claim 41, wherein the thickness of the first layer of the p-side cladding layer is 90 nm or more and 400 nm or less. 52. The semiconductor light emitting device according to claim 41, wherein the thickness of the first layer of the p-side cladding layer is 50 nm or more and 300 nm or less. 53. The semiconductor light emitting device according to claim 41, wherein the thickness of the first layer of the p-side cladding layer is 70 nm or more and 300 nm or less. 54. The semiconductor light emitting device according to claim 41, wherein the thickness of the first layer of the p-side cladding layer is 90 nm or more and 300 nm or less. 55. The semiconductor light emitting device according to claim 41, wherein the thickness of the first layer of the p-side cladding layer is 50 nm or more and 200 nm or less. 56. The semiconductor light emitting device according to claim 41, wherein the thickness of the first layer of the p-side cladding layer is 70 nm or more and 200 nm or less. 57. The semiconductor light-emitting device according to claim 41, wherein the thickness of the first layer of the p-side cladding layer is 90 nm or more and 200 nm or less. 58. The semiconductor light emitting device according to claim 41, wherein the thickness of the first layer of the p-side cladding layer is 70 nm or more and 130 nm or less. 59. The semiconductor light emitting device according to claim 41, wherein the thickness of the first layer of the p-side cladding layer is 90 nm or more and 110 nm or less. 60. The semiconductor light emitting device according to claim 41, wherein the thickness of the n-side optical waveguide layer and the p-side optical waveguide layer is more than 0 nm and 50 nm or less. 61. The semiconductor light emitting device according to claim 41, wherein the first layer of the p-side cladding layer has a superlattice structure. 62. The semiconductor light emitting device according to claim 41, wherein the p-side cladding layer has a superlattice structure. 63. The semiconductor light emitting device according to claim 41, wherein the second layer of the p-side cladding layer has a third layer having a bandgap larger than that of the second layer. 64. The semiconductor light emitting device according to claim 63, wherein the third layer is made of a p-type nitride-based III-V group compound semiconductor containing Al and Ga. 65. The third layer is p-type Al _x Ga _{1 -x} N
64. The semiconductor light emitting device according to claim 63, wherein (0 <x <1). 66. The third layer is p-type Al _x Ga _1-x N.
64. The semiconductor light emitting device according to claim 63, wherein (wherein 0.15 ≦ x <1). 67. The semiconductor light emitting device according to claim 41, wherein a distance between the active layer and the second layer of the p-side cladding layer is 20 nm or more. 68. The semiconductor light emitting device according to claim 41, wherein a distance between the active layer and the second layer of the p-side cladding layer is 50 nm or more. 69. The semiconductor light emitting device according to claim 41, wherein a distance between the active layer and the second layer of the p-side cladding layer is 100 nm or more. 70. The semiconductor light emitting device according to claim 41, wherein a distance between the active layer and the second layer of the p-side cladding layer is 280 nm or less. 71. The semiconductor light emitting device according to claim 41, wherein a distance between the active layer and the second layer of the p-side cladding layer is 100 nm or more and 180 nm or less. 72. The semiconductor light emitting device according to claim 41, wherein a distance between the active layer and the second layer of the p-side cladding layer is 120 nm or more and 160 nm or less. 73. The semiconductor light emitting device according to claim 41, wherein a distance between the active layer and the second layer of the p-side cladding layer is 130 nm or more and 150 nm or less. 74. At least one combination of layers having different band gaps or lattice constants is present between the active layer and the second layer of the p-side cladding layer. The semiconductor light-emitting device as described above. 75. At least one superlattice structure composed of layers having different atomic composition ratios exists between the active layer and the second layer of the p-side cladding layer. 41. The semiconductor light emitting device according to item 41. 76. The semiconductor light emitting device according to claim 41, wherein a growth mask is formed on the underlayer, and the ridge is selectively grown on the underlayer in the opening of the growth mask. 77. The semiconductor light emitting device according to claim 76, wherein the growth mask is an insulating film. 78. The semiconductor light emitting device according to claim 41, wherein the underlayer is the first layer. 79. The semiconductor light emitting device according to claim 41, wherein the ridge includes an upper layer portion of the first layer and the second layer. 80. The ridge is an upper layer portion of the first layer,
42. The semiconductor light emitting device according to claim 41, comprising the second layer and a p-type contact layer. 81. The semiconductor light emitting device according to claim 41, wherein the ridge is composed of the second layer and a p-type contact layer. 82. In a semiconductor light emitting device having a structure in which an active layer is sandwiched between an n-side clad layer and a p-side clad layer and a ridge structure formed by selective growth, the p-side clad layer is the active layer. It is composed of an undoped or n-type first layer and a p-type second layer doped with a p-type impurity in this order from the layer side, and the growth interface between the ridge and the underlayer is the first layer or the first layer. When an undoped or other n-type layer is provided between the first layer and the second layer in contact with the first layer, it is included in the first layer or the other layer. A characteristic semiconductor light emitting device. 83. An n-side optical waveguide layer is provided between the n-side cladding layer and the active layer, and a p-side optical waveguide layer is provided between the p-side cladding layer and the active layer. 83. The semiconductor light emitting device according to claim 82. 84. The semiconductor light emitting device according to claim 82, wherein the thickness of the second layer of the p-side cladding layer is greater than 0 nm and not more than 550 nm. 85. The semiconductor light emitting device according to claim 82, wherein the thickness of the second layer of the p-side cladding layer is greater than 0 nm and 450 nm or less. 86. The semiconductor light emitting device according to claim 82, wherein the thickness of the second layer of the p-side cladding layer is 390 nm or more and 550 nm or less. 87. The semiconductor light emitting device according to claim 82, wherein the thickness of the second layer of the p-side cladding layer is 400 nm or more and 530 nm or less. 88. The semiconductor light emitting device according to claim 82, wherein the thickness of the first layer is 50 nm or more. 89. The semiconductor light emitting device according to claim 82, wherein the thickness of the first layer of the p-side cladding layer is 50 nm or more and 500 nm or less. 90. The semiconductor light emitting device according to claim 82, wherein the thickness of the first layer of the p-side cladding layer is 50 nm or more and 400 nm or less. 91. The semiconductor light emitting device according to claim 82, wherein the thickness of the first layer of the p-side cladding layer is 70 nm or more and 400 nm or less. 92. The semiconductor light emitting device according to claim 82, wherein the thickness of the first layer of the p-side cladding layer is 90 nm or more and 400 nm or less. 93. The semiconductor light emitting device according to claim 82, wherein the thickness of the first layer of the p-side cladding layer is 50 nm or more and 300 nm or less. 94. The semiconductor light emitting device according to claim 82, wherein the thickness of the first layer of the p-side cladding layer is 70 nm or more and 300 nm or less. 95. The semiconductor light-emitting element according to claim 82, wherein the thickness of the first layer of the p-side cladding layer is 90 nm or more and 300 nm or less. 96. The semiconductor light-emitting device according to claim 82, wherein the thickness of the first layer of the p-side cladding layer is 50 nm or more and 200 nm or less. 97. The semiconductor light-emitting device according to claim 82, wherein the thickness of the first layer of the p-side cladding layer is 70 nm or more and 200 nm or less. 98. The semiconductor light-emitting device according to claim 82, wherein the thickness of the first layer of the p-side cladding layer is 90 nm or more and 200 nm or less. 99. The semiconductor light-emitting device according to claim 82, wherein the thickness of the first layer of the p-side cladding layer is 70 nm or more and 130 nm or less. 100. The semiconductor light emitting device according to claim 82, wherein the thickness of the first layer of the p-side cladding layer is 90 nm or more and 110 nm or less. 101. The semiconductor light emitting device according to claim 82, wherein the thickness of the n-side optical waveguide layer and the p-side optical waveguide layer is greater than 0 nm and 50 nm or less. 102. The semiconductor light emitting device according to claim 82, wherein the first layer of the p-side cladding layer has a superlattice structure. 103. The semiconductor light emitting device according to claim 82, wherein the p-side cladding layer has a superlattice structure. 104. The semiconductor light emitting device according to claim 82, wherein the second layer of the p-side cladding layer has a third layer having a bandgap larger than that of the second layer. 105. The semiconductor light emitting device according to claim 82, wherein a distance between the active layer and the second layer of the p-side cladding layer is 20 nm or more. 106. The semiconductor light emitting device according to claim 82, wherein a distance between the active layer and the second layer of the p-side cladding layer is 50 nm or more. 107. The semiconductor light emitting device according to claim 82, wherein a distance between the active layer and the second layer of the p-side cladding layer is 100 nm or more. 108. The semiconductor light-emitting device according to claim 82, wherein the distance between the active layer and the second layer of the p-side cladding layer is 280 nm or less. 109. The distance between the active layer and the second layer of the p-side cladding layer is 100 nm or more and 180 nm.
83. The semiconductor light emitting device according to claim 82, wherein: 110. The distance between the active layer and the second layer of the p-side cladding layer is 120 nm or more and 160 nm.
83. The semiconductor light emitting device according to claim 82, wherein: 111. The distance between the active layer and the second layer of the p-side cladding layer is 130 nm or more and 150 nm.
83. The semiconductor light emitting device according to claim 82, wherein: 112. At least one combination of layers having different band gaps or lattice constants is present between the active layer and the second layer of the p-side cladding layer. The semiconductor light-emitting device as described above. 113. At least one superlattice structure composed of layers having different atomic composition ratios exists between the active layer and the second layer of the p-side cladding layer. 82. The semiconductor light emitting device according to 82. 114. The semiconductor light emitting device according to claim 82, wherein a growth mask is formed on the underlayer, and the ridge is selectively grown on the underlayer in the opening of the growth mask. 115. The semiconductor light emitting device according to claim 114, wherein the growth mask is an insulating film. 116. The semiconductor light-emitting element according to claim 82, wherein the underlayer is the first layer. 117. The ridge of claim 82, wherein the ridge includes an upper portion of the first layer and the second layer.
The semiconductor light-emitting device as described above. 118. The semiconductor light emitting device according to claim 82, wherein the ridge comprises an upper layer portion of the first layer, the second layer and a p-type contact layer. 119. The ridge comprises the second layer and p.
83. The semiconductor light emitting device according to claim 82, comprising a mold contact layer. 120. A structure having an active layer sandwiched between an n-side clad layer and a p-side clad layer and a ridge structure formed by selective growth, wherein the p-side clad layer is formed from the active layer side. Undoped or n-type first layer and p
And a p-type second layer doped with type impurities, and the second layer has a third layer having a bandgap larger than that of the second layer. A method of manufacturing a semiconductor light emitting device using a semiconductor, comprising the steps of: after growing the first layer, forming a growth mask having a predetermined opening on the first layer; A step of growing an undoped or n-type layer, the second layer, and the third layer on the first layer in the opening, the method for manufacturing a semiconductor light emitting device. 121. The method for manufacturing a semiconductor light emitting device according to claim 120, further comprising the step of growing a p-type contact layer on the second layer. 122. A structure in which an active layer is sandwiched between an n-side clad layer and a p-side clad layer and a ridge structure formed by selective growth, wherein the p-side clad layer is formed from the active layer side. Undoped or n-type first layer and p
And a p-type second layer doped with type impurities, and the second layer has a third layer having a bandgap larger than that of the second layer. A method of manufacturing a semiconductor light emitting device using a semiconductor, comprising the steps of: after growing the first layer, forming a growth mask having a predetermined opening on the first layer; A step of growing the second layer and the third layer on the first layer in the opening, the method for manufacturing a semiconductor light emitting device. 123. The method for manufacturing a semiconductor light emitting device according to claim 122, further comprising the step of growing a p-type contact layer on the second layer. 124. A structure in which an active layer is sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth are provided, and the p-side cladding layer is formed from the active layer side. Undoped or n-type first layer and p
A method for manufacturing a semiconductor light emitting device using a nitride-based III-V group compound semiconductor, which comprises a p-type second layer doped with a type impurity, comprising: growing the first layer; Forming a growth mask having a predetermined opening on the first layer; growing an undoped or n-type layer and the second layer on the first layer in the opening of the growth mask. A method of manufacturing a semiconductor light emitting device, comprising: 125. The method for manufacturing a semiconductor light emitting device according to claim 124, further comprising the step of growing a p-type contact layer on the second layer. 126. A structure having an active layer sandwiched between an n-side clad layer and a p-side clad layer and a ridge structure formed by selective growth, wherein the p-side clad layer is formed from the active layer side. Undoped or n-type first layer and p
A method for manufacturing a semiconductor light emitting device using a nitride-based III-V group compound semiconductor, which comprises a p-type second layer doped with a type impurity, comprising: growing the first layer; Forming a growth mask having a predetermined opening on the first layer, and growing the second layer on the first layer in the opening of the growth mask. A method for manufacturing a semiconductor light emitting device characterized by the above. 127. The method for manufacturing a semiconductor light emitting device according to claim 126, further comprising the step of growing a p-type contact layer on the second layer. 128. A structure in which an active layer is sandwiched between an n-side clad layer and a p-side clad layer and a ridge structure formed by selective growth, wherein the p-side clad layer is formed from the active layer side. Undoped or n-type first layer and p
A method for manufacturing a semiconductor light emitting device, comprising a p-type second layer doped with a type impurity, wherein a predetermined opening is formed on the first layer after growing the first layer. A semiconductor light emitting device comprising: a step of forming a growth mask; and a step of growing an undoped or n-type layer and the second layer on the first layer in the opening of the growth mask. Manufacturing method. 129. The method for manufacturing a semiconductor light emitting device according to claim 128, further comprising the step of growing a p-type contact layer on the second layer. 130. A structure having an active layer sandwiched between an n-side clad layer and a p-side clad layer and a ridge structure formed by selective growth, wherein the p-side clad layer is formed from the active layer side. Undoped or n-type first layer and p
A method for manufacturing a semiconductor light emitting device, comprising a p-type second layer doped with a type impurity, wherein a predetermined opening is formed on the first layer after growing the first layer. A method for manufacturing a semiconductor light emitting device, comprising: a step of forming a growth mask; and a step of growing the second layer on the first layer in the opening of the growth mask. 131. The method of manufacturing a semiconductor light emitting device according to claim 130, further comprising the step of growing a p-type contact layer on the second layer. 132. A structure in which an active layer is sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth are provided, and the p-side cladding layer is formed from the active layer side. Undoped or n-type first layer and p
And a p-type second layer doped with type impurities, and the second layer has a third layer having a bandgap larger than that of the second layer. A method for manufacturing a semiconductor light emitting device using a semiconductor, wherein the growth from the active layer to the third layer is performed in a carrier gas atmosphere containing substantially no hydrogen and nitrogen as a main component. A method for manufacturing a semiconductor light emitting device, comprising: 133. The method of manufacturing a semiconductor light emitting device according to claim 132, wherein the carrier gas atmosphere containing substantially no hydrogen and having nitrogen as a main component is an N ₂ gas atmosphere. 134. A structure in which an active layer is sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth are provided, and the p-side cladding layer is formed from the active layer side. Undoped or n-type first layer and p
A method for manufacturing a semiconductor light emitting device using a nitride-based III-V group compound semiconductor, comprising: a p-type second layer doped with a type impurity; A method for manufacturing a semiconductor light emitting device, wherein the growth up to the first layer is performed in a carrier gas atmosphere containing substantially no hydrogen and nitrogen as a main component. 135. The method of manufacturing a semiconductor light emitting device according to claim 134, wherein the carrier gas atmosphere containing substantially no hydrogen and having nitrogen as a main component is an N ₂ gas atmosphere. 136. A nitride III-V compound semiconductor having a structure in which an active layer is sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth is used. In the semiconductor light emitting device, the distance between the active layer and a p-type layer doped with a p-type impurity, which is the closest to the active layer, is 50 nm or more. 137. The distance between the active layer and the p-type layer is 60 nm or more.
6. The semiconductor light emitting device according to 6. 138. The distance between the active layer and the p-type layer is 100 nm or more.
36. The semiconductor light emitting device according to 36. 139. The semiconductor light emitting device according to claim 136, wherein the distance between the active layer and the p-type layer is 50 nm or more and 500 nm or less. 140. The semiconductor light-emitting device according to claim 136, wherein a distance between the active layer and the p-type layer is 100 nm or more and 200 nm or less. 141. The semiconductor light emitting device according to claim 136, wherein the p-type layer closest to the active layer is a p-type layer having a bandgap larger than that of the p-side cladding layer. 142. A structure in which an active layer is sandwiched between an n-side cladding layer and a p-side cladding layer and a ridge structure formed by selective growth are provided, and the active layer is closest to the active layer. The distance from the p-type layer doped with p-type impurities is 50 nm or more, and the p-type layer closest to the active layer is a p-type layer having a band gap larger than that of the p-side cladding layer. A method for manufacturing a semiconductor light emitting device using a nitride-based III-V group compound semiconductor, wherein hydrogen is substantially grown during growth from the active layer to a p-type layer having a bandgap larger than that of the p-side cladding layer. A method for manufacturing a semiconductor light emitting device, characterized in that the process is carried out in a carrier gas atmosphere containing nitrogen as a main component without being included. 143. The method for manufacturing a semiconductor light emitting device according to claim 142, wherein the carrier gas atmosphere containing substantially no hydrogen and having nitrogen as a main component is an N ₂ gas atmosphere.