JP2002329919A - Optical communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable optical communication system whose power consumption is low by using a surface emitting semiconductor laser element chip capable of lowering an operating voltage, an oscillation threshold current or the like as a light emitting light source, which reduces a change in the characteristic of a semiconductor laser and prevents loss of life. SOLUTION: An n-semiconductor distributed Bragg reflecting mirror 3 is formed on an n-GaAs substrate 2, and an n-Gax In1-x Py As1-y layer 11 in a thickness of λ/4 is laminated on it. An undoped lower-part GaAs spacer 4, three layers of Gax In1-x As quantum well layers (quantum well active layers) 12 and GaAs barrier layers (20 nm) 13, and an undoped upper-part spacer layer 4, are laminated on it. A resonator in a thickness of one wavelength portion (a thickness of λ) of an oscillation wavelength inside a medium is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser used for optical communication and the like and an optical communication system therefor. The present invention relates to an optical communication system in which a plurality of laser elements are formed using a surface emitting laser to enable large-capacity communication.

[0002]

2. Description of the Related Art A surface emitting semiconductor laser emits laser light in a vertical direction from the surface of a substrate, so that two-dimensional parallel integration is possible, and the spread angle of the output light is relatively narrow (about 10 degrees). Therefore, it is easy to couple with an optical fiber and easy to inspect the element.
Therefore, in particular, development as an element suitable for configuring an optical transmission module (optical interconnection device) of a parallel transmission type has been actively conducted. The immediate application of the optical interconnection device is parallel connection between housings of computers and the like and between boards, as well as short-distance optical fiber communication, but large-scale computer networks and long distances are expected applications in the future. There is a trunk system for distance and large-capacity communication. Generally, a surface emitting semiconductor laser is made of GaAs or Ga.
Although it is common to comprise an active layer made of InAs, an upper semiconductor distributed Bragg reflector arranged above and below the active layer, and an optical resonator composed of a lower semiconductor distributed Bragg reflector on the substrate side. Since the length of the optical resonator is significantly shorter than that of the edge emitting semiconductor laser,
By setting the reflectivity of the reflecting mirror to an extremely high value (99% or more), it is necessary to easily cause laser oscillation. For this reason, a semiconductor distributed Bragg reflector formed by alternately laminating a low-refractive-index material made of AlAs and a high-refractive-index material made of GaAs at a period of １ ／ wavelength is usually used.

By the way, as described above, a long wavelength band laser having a laser wavelength of 1.1 μm or more used for optical communication, for example, a long wavelength band having a laser wavelength of 1.3 μm or 1.55 μm. In the laser, InP is used for the production substrate and InGaAsP is used for the active layer. However, the lattice constant of InP of the substrate is large, and a reflective mirror material matching the substrate cannot obtain a large refractive index difference. Must be more than pairs. Another problem with the semiconductor laser formed on the InP substrate is that the characteristics greatly change with temperature. For this reason, it is necessary to add a device for keeping the temperature constant, and it is difficult to use the device for general purposes such as consumer use. Light emitting semiconductors have not yet been put to practical use. As an invention made to solve such a problem, Japanese Patent Application Laid-Open No. 9-237942 has been proposed.
The one disclosed in Japanese Patent Application Laid-Open Publication No. H10-260, 1993 is known. According to this, a GaAs substrate is used as a production substrate, and a semiconductor layer made of AlInP that can be lattice-matched with the substrate is used as a low refractive index layer of at least one of the semiconductor distributed Bragg reflectors in the lower upper portion on the substrate side. G is applied to at least one of the lower and upper semiconductor distributed Bragg reflectors in the high refractive index layer.
The purpose of the present invention is to realize a semiconductor Bragg reflector having a high reflectivity with a small number of layers by using a semiconductor layer made of aInNAs so as to obtain a larger refractive index difference than before. GaInNAs is used as a material for the active layer. This is because the band gap (forbidden band width) can be reduced from 1.4 eV to 0 eV by increasing the N composition, and therefore, it can be used as a material that emits a wavelength longer than 0.85 μm. Because it becomes. In addition, it mentions that a semiconductor layer made of GaInNAs is preferable as a material for a long-wavelength surface emitting semiconductor laser in a 1.3 μm band and a 1.55 μm band because lattice matching with a GaAs substrate is possible.

[0004] However, in the past, only suggesting the possibility of realizing a surface emitting semiconductor laser in a wavelength band longer than 0.85 µm, such a thing has not been actually realized. This is because, although the basic configuration is almost theoretically determined, a more specific configuration for actually obtaining stable laser emission is still unknown. As an example, as described above, Al
A semiconductor distributed Bragg reflector formed by alternately laminating a low-refractive-index material composed of As and a high-refractive-index material composed of GaAs at a period of 1/4 wavelength;
Alternatively, as disclosed in Japanese Unexamined Patent Publication No. 9-237942, a semiconductor distributed Bragg reflector using a low refractive index layer made of a semiconductor layer made of AlInP that can be lattice-matched with the substrate has no laser element. No light was emitted, or even if light was emitted, its luminous efficiency was low, far from a practical level. This is because a material containing Al is chemically very active and crystal defects caused by Al are likely to occur. To solve this problem, Japanese Patent Application Laid-Open Nos. 8-340146 and 7-307 disclose the method.
There is a proposal for forming a semiconductor distributed Bragg reflector from GaInNP and GaAs that do not contain Al as in the invention disclosed in Japanese Patent No. 525. However, GaInNP
The refractive index difference between AlAs and GaAs is about half the refractive index difference between AlAs and GaAs. That is, at present, optical fiber communication is expected in computer networks and the like.
There is no long-wavelength surface-emitting semiconductor laser having a wavelength of 1.7 μm and a communication system using the same. Further, as described below, the long-wavelength band surface emitting laser according to the present invention has a GaInNAs active layer with a high strain. Is done.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has a laser oscillation wavelength of 1.
The present invention relates to a long-wavelength surface emitting semiconductor laser having a wavelength of 1 μm to 1.7 μm and an optical communication system thereof.
The purpose of the present invention is to use a surface-emitting type semiconductor laser device chip capable of lowering an operating voltage, an oscillation threshold current, and the like as a light emitting light source, to reduce power consumption, to reduce fluctuations in semiconductor laser characteristics, and to prevent a reduction in life. To propose a highly reliable optical communication system. The second object is to reduce the life of the semiconductor laser while reducing the fluctuation in characteristics of the semiconductor laser with low power consumption by using a surface-emitting type semiconductor laser element chip capable of lowering the operating voltage, the oscillation threshold current and the like as a light emitting light source. It is to propose a highly reliable optical communication system by preventing the above. A third object is that the laser oscillation wavelength that can be used stably is 1.
A long wavelength surface emitting semiconductor laser device chip of 1 μm to 1.7 μm is used as a light emitting light source, and has high reliability and practicality. It is to propose a high optical communication system. The fourth object is to use a long-wavelength surface emitting semiconductor laser device chip having a laser oscillation wavelength of 1.1 μm to 1.7 μm, which can be used stably, as a light emitting light source, and to have high reliability and practicality. An object of the present invention is to propose a highly reliable optical communication system by preventing a reduction in the life of a laser while reducing fluctuations in laser characteristics. A fifth object of the present invention is to provide a more reliable optical communication system in such an optical communication system by efficiently releasing heat generated by a semiconductor laser, reducing its characteristic fluctuations, and preventing a reduction in life. It is to propose. A sixth object is also provided in such an optical communication system.
It is an object of the present invention to propose a more reliable optical communication system by efficiently dissipating heat generated by a semiconductor laser, reducing its characteristic fluctuation, and preventing a reduction in life. A seventh object is to provide such an optical communication system,
An object of the present invention is to propose a more reliable semiconductor laser package structure of an optical communication system by efficiently dissipating heat generated by a semiconductor laser, reducing its characteristic fluctuation, and preventing a reduction in life.

[0006]

According to the present invention, there is provided a laser chip and an optical communication system connected to the laser chip, wherein the laser chip has an oscillation wavelength of 1.1 μm. To 1.7 μm, and the main elements of the active layer that generates light are Ga, In, N, and As.
Or a layer made of Ga, In, As, and a surface-emitting type semiconductor laser device chip having a resonator structure including reflectors provided above and below the active layer in order to obtain a laser beam. The reflective mirror has a reflection wavelength of 1.1 μm or more, and the refractive index of a material layer constituting the reflective mirror periodically changes to a value different from that of the other, and semiconductor distributed Bragg reflection in which incident light is reflected by light wave interference. with a mirror, the material layer of the refractive index is small is _Al x _{Ga 1-x} as
(0 <x ≦ 1), and the material layer having a large refractive index is Al _{y
Ga 1-y As (0 ≦} y <x ≦ 1) and then, and the the refractive index between the refractive index is small and large material layer has a value between the small and large _Al z _{Ga 1-z} As An optical communication system using a surface-emitting type semiconductor laser device chip as a reflector having a heterospike buffer layer (0 ≦ y <z <x ≦ 1) having a thickness of 20 nm to 50 nm as a light source. The difference between the linear expansion coefficients of the laser chip and the substrate material on which the laser chip is mounted is within 2 × 10 ⁻⁶ / K.

In fields where the laser oscillation wavelength is expected to be 1.1 μm to 1.7 μm for optical fiber communication, such as computer networks and trunk systems for long-distance large-capacity communication, the operating voltage, oscillation threshold current and the like are reduced. Although there was no surface emitting semiconductor laser capable of generating stable laser oscillation with little heat generation from the laser element and a communication system using the same, the operating voltage was improved by devising a semiconductor distributed Bragg reflector as in the present invention. In addition, the oscillation threshold current and the like can be reduced, low power consumption, stable oscillation with little heat generation of the laser element can be achieved, and a low-cost and practical optical communication system can be realized. Further, the difference between the linear expansion coefficient of the laser chip and the substrate material on which the laser chip is mounted is 2 × 10 ⁻⁶ /
K, the high strain GaIn
Since the difference between the linear expansion coefficient of the long-wavelength surface emitting laser having the NAs active layer and the linear expansion coefficient of the mounting substrate can be reduced, the generation of thermal stress is suppressed, and as a result, the characteristic fluctuation of the semiconductor laser caused by the thermal stress , While preventing a reduction in the service life, a highly reliable optical communication system was realized. According to the invention, by devising the semiconductor distributed Bragg reflector, the operating voltage, the oscillation threshold current, and the like can be reduced, the power consumption is low, the laser element generates less heat, and stable oscillation can be performed. Optical communication system was realized. Further, 2 × 10 ^-6 to difference in the linear expansion coefficient of the substrate material that implements the laser chip and the laser chip
/ K, the high strain GaI
Since the difference between the linear expansion coefficient of the long wavelength surface emitting laser having the nNAs active layer and the linear expansion coefficient of the mounting substrate can be reduced,
The generation of thermal stress is suppressed, and as a result, the variation in the characteristics of the semiconductor laser caused by the thermal stress is reduced, the reduction in the life is prevented, and a highly reliable optical communication system is realized.

A second aspect of the present invention is a laser chip and the laser chip.
In an optical communication system connected to a
The oscillation wavelength is 1.1 μm to 1.7 μm.
Whether the main element generated in the active layer is Ga, In, N, or As
A layer made of Ga, In, or As,
Provided above and below the active layer to obtain laser light
-Emitting semi-conductor with resonator structure including a mirrored reflector
Laser chip, wherein the reflection mirror has a reflection wavelength of
When the refractive index of the material layer constituting the reflecting mirror is 1.1 μm or more,
Periodically changes to different values, and the incident light is
Is a semiconductor distributed Bragg reflector that reflects
The material layer having a small refractive index is Al_xGa _1-xAs
(0 <x ≦ 1), and the material layer having a large refractive index is made of Al_y
Ga_1-yAs (0 ≦ y <x ≦ 1), and the refraction is
The refractive index between the small and large material layers has a value between small and large.
Al taken_zGa_1-zFrom As (0 ≦ y <z <x ≦ 1)
A heterospike buffer layer having a thickness of 20 nm to 50 nm
Surface-emitting type semiconductor laser device, such as a reflector provided in a semiconductor device
An optical communication system using a chip as a light source,
The substrate on which the laser chip is mounted is Si, SiC, GaAs
s or AlN.
The backbone of computer networks and long-distance large-capacity communications
Laser oscillation wavelength for optical fiber communication
In the field of 1.1 μm band to 1.7 μm band,
Pressure, oscillation threshold current, etc.
Surface-emitting type semiconductor laser capable of stable oscillation without
Although there was no communication system using it, the present invention
By devising a semiconductor distributed Bragg reflector like
Operating voltage, oscillation threshold current, etc.
As a result, stable oscillation can be achieved with less heat generated by the laser element.
A low-cost and practical optical communication system was realized. Sa
In addition, a long wavelength band surface emitting laser chip is used for Si, SiC,
Mount on a substrate made of either GaAs or AlN
A long wavelength with a high strain GaInNAs active layer
Linear expansion coefficient of band-emission laser and linear expansion coefficient of mounting substrate
Is small, the generation of thermal stress is suppressed, and as a result
Characteristics of semiconductor lasers caused by thermal stress
Highly reliable optical communication that can reduce the lifespan while reducing
The system has been realized. According to the invention, the semiconductor component
By devising a cloth Bragg reflector, the operating voltage and
Low threshold current and low power consumption.
Stable oscillation with less heat generation, and practical at low cost
Optical communication system was realized. In addition, long wavelength band surface
Emitting laser chip using Si, SiC, GaAs, AlN
High distortion by mounting on a substrate made of either
-Wavelength surface-emitting lasers with different GaInNAs active layers
The difference between the linear expansion coefficient of
Therefore, the generation of thermal stress is suppressed, and as a result,
Life while reducing characteristic fluctuations of semiconductor lasers
Optical communication system with high reliability
did it.

A third aspect of the present invention is a laser chip and the laser chip.
In an optical communication system connected to a
The oscillation wavelength is 1.1 μm to 1.7 μm.
Whether the main element of the generated active layer is Ga, In, N, or As
A layer made of Ga, In, or As,
Provided above and below the active layer to obtain laser light
-Emitting semi-conductor with resonator structure including a mirrored reflector
Laser chip, wherein the reflection mirror has a reflection wavelength of
When the refractive index of the material layer constituting the reflecting mirror is 1.1 μm or more,
Periodically changes to different values, and the incident light is
Is a semiconductor distributed Bragg reflector that reflects
The material layer having a small refractive index is Al_xGa _1-xAs
(0 <x ≦ 1), and the material layer having a large refractive index is made of Al_y
Ga_1-yAs (0 ≦ y <x ≦ 1)
The main composition between the active layer and the reflector is Ga_x
In_1-xP_yAs_1-y(0 <x ≦ 1, 0 <y ≦ 1)
Emission type half provided with a non-radiative recombination prevention layer composed of
Optical communication system using a semiconductor laser element chip as a light source
And mounting the laser chip and the laser chip.
The difference between the linear expansion coefficients of the substrate materials is 2 × 10^-6Within / K
There is a feature.

A long wavelength band surface that can be used stably in the field of laser oscillation wavelengths of 1.1 μm to 1.7 μm where optical fiber communication is expected, such as computer networks and trunk lines for long distance and large capacity communication. Although there was no light emitting semiconductor laser and a communication system using the same,
As in the present invention, the surface-emitting type semiconductor laser device chip provided with the non-radiative recombination preventing layer enables stable oscillation, and a practical optical communication system using this as a light-emitting light source was realized. . Further, the difference between the linear expansion coefficient of the laser chip and the substrate material on which the laser chip is mounted is calculated as 2
By setting it within ^10-6 / K, the difference between the linear expansion coefficient of the long-wavelength band surface emitting laser having the GaInNAs active layer with high strain and the linear expansion coefficient of the mounting substrate can be reduced, so that the thermal stress can be reduced. Is suppressed, and as a result, the characteristic fluctuation of the semiconductor laser caused by the thermal stress is reduced, and the life of the semiconductor laser is prevented from being shortened. As a result, a highly reliable optical communication system can be realized. According to the invention, stable oscillation can be achieved by using a surface emitting semiconductor laser device chip provided with a non-radiative recombination preventing layer, and a practical optical communication system using this as a light emitting light source can be realized. . Further, by setting the difference between the linear expansion coefficients of the laser chip and the substrate material on which the laser chip is mounted to be within 2 × 10 ⁻⁶ / K, a long-wavelength surface emission type having a GaInNAs active layer with a high strain is provided. Since the difference between the coefficient of linear expansion of the laser and the coefficient of linear expansion of the mounting board can be reduced, the occurrence of thermal stress is suppressed.As a result, the characteristic fluctuation of the semiconductor laser caused by the thermal stress can be reduced, and the life can be prevented from being shortened. Thus, a highly reliable optical communication system was realized.

A fourth aspect of the present invention provides a laser chip and the laser chip.
In an optical communication system connected to a
The oscillation wavelength is 1.1 μm to 1.7 μm.
Whether the main element of the generated active layer is Ga, In, N, or As
A layer made of Ga, In, or As,
Provided above and below the active layer to obtain laser light
-Emitting semi-conductor with resonator structure including a mirrored reflector
Laser chip, wherein the reflection mirror has a reflection wavelength of
When the refractive index of the material layer constituting the reflecting mirror is 1.1 μm or more,
Periodically changes to different values, and the incident light is
Is a semiconductor distributed Bragg reflector that reflects
The material layer having a small refractive index is Al_xGa _1-xAs
(0 <x ≦ 1), and the material layer having a large refractive index is made of Al_y
Ga_1-yAs (0 ≦ y <x ≦ 1)
The main composition between the active layer and the reflector is Ga_x
In_1-xP_yAs_1-y(0 <x ≦ 1, 0 <y ≦ 1)
Emission type half provided with a non-radiative recombination prevention layer composed of
Optical communication system using a semiconductor laser element chip as a light source
Wherein the substrate on which the laser chip is mounted is Si, S
iC, GaAs, or AlN
Features. Computer network, long distance
Optical fiber communications such as trunk lines for mass communication are expected.
Laser oscillation wavelengths in the 1.1 to 1.7 μm band
-Wavelength surface emitting semiconductor laser that can be used stably
And there was no communication system using it,
As in the present invention, a surface emitting layer provided with a non-radiative recombination preventing layer is provided.
Stable by using optical semiconductor laser chip
Oscillation is possible, and practical light transmission
The communication system was realized. In addition, a long-wavelength surface-emitting laser
Any of Si, SiC, GaAs and AlN
By mounting on a substrate consisting of
Linear expansion of long wavelength surface emitting laser with nNAs active layer
Because the difference between the coefficient and the coefficient of linear expansion of the mounting board is small, thermal stress
Generation is suppressed, resulting in thermal stress
Prevents shortening of service life while reducing characteristic fluctuations of semiconductor lasers
The optical communication system with high reliability was realized. Or
According to the invention, the surface provided with the non-radiative recombination preventing layer
Light emitting semiconductor laser device chip
Oscillation that can be used as a light source
The communication system has been realized. Furthermore, long wavelength band surface emitting type
Laser chip made of any of Si, SiC, GaAs and AlN
By mounting it on a substrate made of
Linear expansion of long wavelength surface emitting laser with InNAs active layer
Since the difference between the tension coefficient and the linear expansion coefficient of the mounting board is small,
The generation of force is suppressed, resulting in thermal stress
To reduce the life of semiconductor lasers while reducing their characteristic fluctuations.
An optical communication system with high reliability can be realized.

According to another aspect of the present invention, the mounting substrate on which the laser chip is mounted is fixed to a heat radiating member, and the heat radiating member is made of a material having a higher thermal conductivity than the laser chip. It is. The laser oscillation wavelength is expected to be 1.1 μm to 1.1 for optical fiber communication such as computer networks and trunk lines for long-distance large-capacity communication.
In the field of the 7 μm band, there has been no surface emitting semiconductor laser capable of lowering the operating voltage, the oscillation threshold current, etc., and generating stable laser with less heat generation of the laser element and a communication system using the same. By devising a semiconductor distributed Bragg reflector or providing a non-radiative recombination prevention layer, the operating voltage, oscillation threshold current, etc. can be reduced, low power consumption, stable oscillation with little heat generation from the laser element. A practical optical communication system using this as a light source was realized. Furthermore, by fixing the mounting board on which the laser chip is mounted to a heat radiating member and using the heat radiating member of a material having a higher thermal conductivity than the laser chip, heat generated by the semiconductor laser can be efficiently released. Became. As a result, the characteristic fluctuation of the laser output can be reduced, the life can be prevented from being shortened, and a more reliable optical communication system can be realized. According to such a technical means, the mounting substrate on which the laser chip is mounted is fixed to a heat radiating member, and the heat radiating member is made of a material having a higher thermal conductivity than the laser chip. I was able to escape efficiently. As a result, the characteristic fluctuation of the laser output can be reduced,
A reduction in the life can be prevented, and a more reliable optical communication system can be realized.

According to a sixth aspect of the present invention, the mounting board on which the laser chip is mounted is fixed to a heat radiating member, and the heat radiating member may be made of any of AlN, Cu / W, W, Mo, and Cu. This is an effective means of the invention. According to such technical means, the heat radiation member to which the mounting substrate is fixed is
Since any one of N, Cu / W, W, and Mo has a large thermal conductivity, heat generated from a semiconductor laser or a laser driving circuit can be efficiently radiated. Since the difference from the coefficient of linear expansion of the mounting board is small, thermal stress does not occur and, consequently, the long-wavelength surface-emitting semiconductor laser is not distorted. And a highly reliable optical communication system was realized. Claim 7
It is also an effective means of the present invention that the heat radiating member also serves as a package of the optical transmission module. According to this technical means, the heat radiation member to which the mounting substrate is fixed is made into the package of the optical transmission module, so that the number of components is small, the heat radiation characteristic is good, and the characteristic fluctuation of the long-wavelength surface emitting semiconductor laser. , The life can be prevented from being shortened, and a highly reliable optical communication system can be realized.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are not merely intended to limit the scope of the present invention but are merely illustrative examples unless otherwise specified. . First, the laser oscillation wavelength with a small transmission loss, which is a light emitting element applied to the optical communication system of the present invention, is as follows.
One example of a long-wavelength band surface emitting semiconductor laser of 1 μm to 1.7 μm will be described with reference to FIG. As described above, conventionally, the laser oscillation wavelength to be applied by the present invention is 1.
With respect to the long-wavelength surface emitting semiconductor laser having a wavelength of 1 μm to 1.7 μm, there is only a suggestion of the possibility, and a material for realizing the laser, and a more specific and detailed configuration were unknown. In the present invention, a material such as GaInNAs is used for the active layer, and a more specific configuration is clarified. The details are described below. In the present invention, n-G of plane orientation (100) is used.
On the aAs substrate 2, n-Al _x Ga having a thickness (thickness of λ / 4) １ ／ times the oscillation wavelength λ in each medium.
_{1-x As (x = 1.0} ) ( low refractive index layer-refractive index small layer) and _{n-Al y Ga 1-y} As (y = 0) ( high refractive index layer-refractive index large layer) alternately 35 cycles laminated n- semiconductor distributed Bragg reflector 3 (AlAs / GaAs lower semiconductor distributed Bragg reflector) is _{formed, n-Ga x in 1-} x P y of the thickness of lambda / 4 on the As _1-y (x = 0.
5, y = 1) Layer 11 was laminated. In this example n-Ga _{x
In 1-x P y As 1} -y (x = 0.5, y = 1) layer are also part of the lower reflecting mirror has a low refractive index layer (a layer having a refractive index is small).

An undoped lower GaAs layer is formed thereon.
Pacer layer 4 and three layers of Ga_xIn_{1 -X}As quantum well layer
Active layer (quantum well active layer) 12 and GaAs barrier
A multiple quantum well active layer comprising a layer (20 nm) 13;
And an upper doped GaAs spacer layer,
Of the thickness of one oscillation wavelength λ (thickness of λ)
A resonator is formed. In addition, C (carbon)
P-Ga_xIn_1-xP_yAs_1-y(X = 0.
5, y = 1) layer and Zn-doped p-Al_xGa_1-xAs
(X = 0) is set to 1 of the oscillation wavelength λ in each medium.
/ 4 times the thickness of the periodic structure (one cycle) laminated alternately
Layer on which C-doped p-Al_xGa_1-xAs
(X = 0.9) and Zn-doped p-Al_xGa_1-xAs
(X = 0) is set to 1 of the oscillation wavelength λ in each medium.
With a periodic structure (25 periods) alternately stacked with a thickness of / 4 times
Semiconductor Bragg reflector 5 (Al_0.9Ga
_0.1As / GaAs upper semiconductor distributed Bragg reflector)
Is formed. In this example, p-Ga_xIn_1-xP _y
As_1-yThe (x = 0.5, y = 1) layer is also a part of the upper reflecting mirror.
And a low refractive index layer (a layer having a low refractive index).
Here, both the upper and lower mirrors have low refractive index layers.
(Low refractive index layer) / high refractive index layer (high refractive index layer) alternately
In the present invention, there is a refraction
Al with a ratio between small and large_zGa_1-zAs (0 ≦
providing a hetero-spike buffer layer consisting of y <z <x ≦ 1)
ing.

FIG. 2 shows a surface emitting semiconductor device applied to the present invention.
Reflector whose reflection wavelength of body laser is 1.1μm or more
This will be described more specifically. The reflection wavelength applied to the present invention is
In a reflecting mirror of 1.1 μm or more, a low refractive index layer (a low refractive index layer) is used.
Layer) and the high refractive index layer (high refractive index layer)
Hetero spike buffer layer Al with a value between_zGa
_1-zAs (0 ≦ y <z <x ≦ 1) 15 is provided.
Figure 2 shows a part of a semiconductor distributed Bragg reflector.
There is a figure (it is omitted in FIG. 1 because the figure is complicated)
are doing). Conventional semiconductor with laser wavelength 0.85μm band
With respect to the laser, such a heterospike buffer layer 15
It is being considered to establish
The material, its thickness, etc.
It has not been. Also, the laser oscillation wavelength as in the present invention is
1.1 μm to 1.7 μm long wavelength band surface emitting semiconductor laser
Is not considered at all. The reason is this field
(Long wavelength band whose laser oscillation wavelength is 1.1 μm to 1.7 μm
Surface emitting semiconductor lasers) is a new field, and it is still almost
This is because research has not progressed. The inventor is quick
In this field (the laser oscillation wavelength is 1.1 μm to 1.7 μm)
Long wavelength surface emitting semiconductor laser and optical communication using the same
Of the usefulness of shin) and intensive study to realize it
Was done. Such a heterospike buffer layer is formed during formation.
The Al composition is controlled by controlling the gas flow rate.
By changing the material layer continuously or stepwise
Shaped so that the refractive index changes continuously or stepwise
To achieve.

More specifically _0017], Al _{z Ga 1-z} As
(0 ≦ y <z <x ≦ 1) The value of z of the layer is changed from 0 to 1.0, that is, GaAs to AlGaAs to AlA.
It is formed so that the ratio of Al and Ga changes gradually as in s. This is created by controlling the gas flow during layer formation as described above. Also, A
The same effect can be obtained by changing the ratio between 1 and Ga continuously as described above, or by changing the ratio stepwise. The reason for providing such a heterospike buffer layer is to solve the problem that the electrical resistance of the p-semiconductor distributed Bragg reflector, which is one of the problems of the distributed Bragg reflector, is high. This is due to a hetero-barrier generated at the interface between the two types of semiconductor layers constituting the semiconductor distributed Bragg reflector. By making the Al composition gradually change to the other composition and changing the refractive index, it is possible to suppress the generation of the hetero barrier.

[0018] Such a hetero spike buffer layer will be described more specifically. FIG. 3 shows an example of a semiconductor distributed Bragg reflector in which a hetero-spike buffer layer is provided between two types of semiconductor layers constituting the semiconductor distributed Bragg reflector. In the figure, AlGaAs-based semiconductor material as an example of the material of the semiconductor distributed Bragg reflector _{(Al z Ga 1-z} A
s (0 ≦ y <z <x ≦ 1)). The two kinds of semiconductor layers constituting the semiconductor distributed Bragg reflector are A
As a hetero-spike buffer layer of ls and GaAs having a valence band energy between AlAs and GaAs, a composition gradient layer in which the Al composition is changed is provided between them. _{That, Al z Ga 1-z As} (0 ≦ y <z
<X ≦ 1) The value of z of the layer is changed from 0 to 1.0, that is, the ratio of Al to Ga is gradually changed, such as GaAs to AlGaAs to AlAs.
AlGaAs-based semiconductor materials have been developed with increasing Al composition.
The band gap energy increases and the refractive index decreases. At this time, in the conduction band, the energy starts to decrease until the Al composition reaches 0.43, but in the valence band, the valence band energy decreases monotonically in substantially proportion to the increase amount of the Al composition ( Overall, the bandgap energy increases with composition.) In addition to this, taking an AlGaInP-based material as an example, this material is 4
It is an original material, but with the increase of AlInP composition, AlG
It shows the same tendency as the increase in the Al composition in the aAs system.
The conduction band energy begins to decrease after increasing to an AlInP composition of 0.7. However, the valence band energy is Al
Similarly, it decreases monotonously with an increase in the InP composition.

In the example shown in FIG. 3, the composition gradient (band-gap energy increase rate) of the region near the GaAs layer (region I in FIG. 3) is shown in FIG.
In region II), the composition gradient is larger than the composition gradient. For comparison, FIG. 4 shows a structure in which a linear composition gradient layer having a linearly changed Al composition is used as a hetero-spike buffer layer.
FIG. 5 shows the results of estimating the electrical resistance of a 4-pair p-DBR in which the heterospike buffer layer of FIG. In FIG. 5, the carrier density of each layer of the DBR including the hetero-spike buffer layer is a P-type of 1E18 [cm ⁻³ ], and the vertical axis indicates the differential sheet resistance near zero bias. The abscissa indicates the Al composition gradient in the region I, and indicates the thickness of the different region I (shown in the figure). The sum of area I and area II is always 20n
m, and the thickness and the composition gradient of the region II are determined by the thickness and the composition gradient of the region I. Simply GaAs layer and AlA
When the linear composition gradient layer is provided between the s layers, the Al composition gradient is 0.05 [nm ^-1 ], which corresponds to the point A in the figure. As shown in FIG. 5, by increasing the gradient of the Al composition in the region I, the resistance value is reduced as compared with the conventional case where the composition gradient is simply made linear. It can also be seen that there is an optimum Al composition gradient that is minimal. For example, when the thickness of the region I is 10 nm (the same thickness as that of the region II), the Al composition gradient is 0.09 [nm ^-1 ], and the resistance is reduced to about 80% of the conventional resistance. It does not depend on voltage.)

Next, the reason will be described. FIG.
FIG. 3 is a band diagram of a thermal equilibrium state of a DBR hetero interface made of AlAs / GaAs. As shown in the figure, heterospikes caused by band discontinuity mainly appear remarkably on the AlAs layer side having a large band gap, and almost no notch is generated on the GaAs layer side. The notch generated on the GaAs layer side does not originally cause a high resistance, so that the AlA
It is important to lower the resistance efficiently that spikes generated on the s layer side are efficiently flattened with a limited thickness of the hetero spike buffer layer. In the structure of FIG.
This corresponds to the fact that the composition is rapidly increased on the aAs side and the composition gradient on the AlAs side where spikes occur is gradually changed. This makes it possible to reduce the occurrence of spikes as compared with the case where the composition change of the hetero-spike buffer layer is simply linear (accordingly, when the Al composition gradient in the region I is smaller than that in the region II, the resistance value becomes smaller). Increases.). FIG. 7 is a schematic diagram of a band diagram in the thermal equilibrium state of FIG. Compared to the conventional simple composition gradient layer, A
The composition gradient on the lAs side can be reduced. From the above, it is understood that the electric resistance can be reduced as compared with the related art by increasing the composition gradient in the region I.

Next, such a refractive index is set to a value between small and large.
Hetero spike buffer layer Al_zGa_1-zAs (0 ≦
y <z <x ≦ 1)
explain. FIG. 8 shows A having a reflection center wavelength at 1.3 μm.
For a 4-pair DBR with lAs / GaAs,
By changing the thickness of the spike buffer layer,
It is the result of having calculated the partial electrical resistivity. DBR layer dopi
Ring density is 1E18cm^{− 3}And heterospike buffering
The doping density of each layer including the layer is uniform. Ma
The value shown by the broken line is obtained from the bulk resistance of each semiconductor layer.
If the resistivity is assumed to be
It shows the resistivity of the DBR obtained in this case. FIG.
DBR without hetero spike buffer layer
When the spike buffer layer thickness is 0), the resistivity is 1Ωcm²And non
Always high resistance, more than 20 pairs as a practical problem
It is difficult to energize the element through the layered DBR itself.
Requires a very high voltage to further energize
You. Therefore, a surface emitting laser device having such a DBR
Is difficult to actually oscillate. However, 5
When a hetero spike buffer layer of nm
Compared to the case without the spike buffer layer, the resistance is about two digits.
It is possible to reduce the drag coefficient, making it easier to energize the element.
Therefore, it is possible to obtain oscillation. In addition, the electricity required for
Pressure also reduces the reliability of the device,
Problems are greatly improved. In addition, heterospike buffer
As the thickness of the layer increases, the resistivity decreases sharply.
Above 20 nm, the resistivity has a substantially constant value. Figure
8 is a hetero-spike buffer layer and p-type doping of each layer
Density 1E18cm ^-3As a uniform doping
It shows the structure. Note that this doping
The concentration is a standard value usually used for DBR. FIG.
In the structure of DBR, the decrease in resistivity begins to saturate
The thickness of the spike buffer layer is about 20 nm.
The resistivity is very low, about 2.5 times the bulk resistivity.
Has been reduced to a lower value. In other words, the terror spike buffer layer
If the lower limit of the thickness is 20 nm,
The operating voltage of the element can be set to the lowest value,
Heat can also be minimized. Therefore, oscillation can be maintained
Temperature, as well as the resulting light output. However,
On the other hand, the optical characteristics of DBR
It is said that the reflectance decreases as the thickness of the buffer layer increases
There's a problem. FIG. 9 shows the change in the thickness of the heterospike buffer layer.
Details of how the DBR reflectivity decreases with respect to
It is. Compared to the straight line shown in the figure,
Rapid change in reflectivity when the buffer layer thickness exceeds 50 nm
It can be seen that the rate increases. The oscillation threshold current of the device is
It starts to increase rapidly in response. Therefore, hetero spa
The upper limit of the thickness of the buffer layer is suitably 50 nm.
You. As described above, heteros of 20 nm or more and 50 nm or less
In a DBR with a pike buffer layer, the effect of hetero interface
Resistance can be effectively reduced and
The reflectance can be obtained at the same time. Surface emitting laser using this
Low-threshold element under realistic driving conditions.
It is possible to obtain oscillation with a value current.

The laser oscillation wavelength of the present invention is 1.1 μm.
m to 1.7 μm long wavelength band surface emitting semiconductor laser,
The thickness is preferably from 20 nm to 50 nm. If the thickness is smaller than this, there is a problem that the resistance becomes large and current does not easily flow, the element generates heat, and the driving energy increases. When the thickness is large, the resistance becomes small, which is advantageous in terms of heat generation of the element and driving energy. However, there is a problem that the reflectance cannot be obtained this time, and as described above, the optimum range (20 nm to 5 nm) is obtained.
(Thickness of 0 nm). As described above, the provision of such a hetero-spike buffer layer for a conventional semiconductor laser having a laser wavelength in the 0.85 μm band has been studied.
In the case of a long-wavelength surface emitting semiconductor laser of 1 μm to 1.7 μm, it is more effective. This is because, for example, to obtain the same reflectance (for example, 99.5% or more), 0.85
In the case of the 1.1 μm to 1.7 μm band than the μm band, such a material layer can be approximately doubled, so that the resistance value of the semiconductor distributed Bragg reflector can be reduced and the operating voltage can be reduced. In addition, the oscillation threshold current and the like are reduced, which is advantageous in terms of prevention of heat generation of the laser element, stable oscillation, and low energy driving. In other words, providing such a hetero-spike buffer layer on a semiconductor distributed Bragg reflector is particularly effective for a long-wavelength surface emitting semiconductor laser having a laser oscillation wavelength of 1.1 μm to 1.7 μm as in the present invention. It can be called a device.

As an example of a more detailed examination result for obtaining an effective reflectivity, for example, in a 1.3 μm band surface emitting laser device, Al _x Ga _{1 -x} As (x = 1.
0) (low refractive index layer-refractive index small layer) and _{Al y Ga 1-y}
As (y = 0) in the case where the (high refractive index layer-refractive index large layer) 20 period stacking, the reflectance of the semiconductor distributed Bragg reflector is 99.7% or less _Al z _{Ga 1-z} As
The thickness of the (0 ≦ y <z <x ≦ 1) layer is 30 nm. The wavelength band where the reflectance is 99.5% or more is 53 nm.
When the reflectance is designed to be 99.5% or more, ± 2
% Can be controlled. Therefore, when prototypes of 10 nm, 20 nm, and 30 nm which are equivalent to and thinner than this were prototyped, the reflectivity could be kept to a practically acceptable level, and the resistance value of the semiconductor distributed Bragg reflector could be reduced. A 1.3 μm band surface emitting laser device was realized, and laser oscillation was successful. Other configurations of the prototyped laser element are as described below. In the multilayer reflector, there is a band having a high reflectivity including the design wavelength (assuming that the film thickness can be completely controlled). High reflectance band (including areas where the reflectance is greater than the required value for the target wavelength)
Call. This is the region where the reflectance at the design wavelength is the highest and decreases very little as the wavelength increases. It drops off sharply from some area. Originally, it is necessary to completely control the film thickness of the multilayer mirror at the atomic layer level so that the reflectance is higher than the required reflectance for the target wavelength. However, a film thickness error of about ± 1% actually occurs, so that the target wavelength deviates from the wavelength having the highest reflectance. For example, when the target wavelength is 1.3 μm, when the film thickness control is shifted by 1%, the wavelength having the highest reflectance is shifted by 13 nm. Therefore, it is desirable that the band of the high reflectance (here, the region where the reflectance is equal to or more than a required value with respect to a target wavelength) is wide. Thus, the laser oscillation wavelength as in the present invention is 1.
In a long-wavelength surface emitting semiconductor laser of 1 μm to 1.7 μm, by devising and optimizing the configuration of such a semiconductor distributed Bragg reflector, it is possible to reduce the resistance value while maintaining a high reflectance. In addition, the operating voltage, the oscillation threshold current, and the like can be reduced, and the prevention of heat generation of the laser element, stable oscillation, and low-energy driving can be achieved.

Returning again to FIG. 1, the uppermost p-Al _x G
The a1 _- xAs (x = 0) layer also has a role as a contact layer (p-contact layer) for making contact with an electrode. Here, the In composition x of the quantum well active layer was 39% (Ga _0.61 In _0.39 As). The thickness of the quantum well active layer was 7 nm. The quantum well active layer had a compressive strain of about 2.8% with respect to the GaAs substrate. The entire surface emitting semiconductor laser was grown by MOCVD. In this case, no lattice relaxation was observed. The raw materials constituting each layer of the semiconductor laser include:
TMA (trimethylaluminum), TMG (trimethylgallium), TMI (trimethylindium), As
H ₃ (arsine) and PH ₃ (phosphine) were used.
H ₂ was used as a carrier gas. In the case where the strain is large as in the active layer (quantum well active layer) of the device shown in FIG. Here, Ga
The InAs layer (quantum well active layer) is grown at 550 ° C. The MOCVD method used here has a high degree of supersaturation and is suitable for crystal growth of a high strain active layer. In addition, high vacuum is not required as in the MBE method, and the supply flow rate and supply time of the source gas may be controlled. In this example, a portion outside the current path was irradiated with protons (H ⁺ ) to form an insulating layer (high-resistance portion) to form a current narrowing portion. In this example, a p-side electrode is formed on the p-contact layer which is the uppermost layer of the upper reflector and is a part of the upper reflector, excluding the light emitting portion, and an n-side electrode is formed on the back surface of the substrate. Was formed.

In this example, the active region (in this embodiment, a resonator composed of the upper and lower spacer layers and the multiple quantum well active layer) sandwiched between the upper and lower reflectors and into which carriers are injected and recombined is used. In the material containing Al (II
The ratio of the low refractive index layers of the lower and upper reflectors closest to the active layer is G.
_{a x In 1-x P y} As 1-y (0 <x ≦ 1,0 <y ≦
The non-radiative recombination preventing layer of 1) is used. That is, by appropriately selecting the value of x or y, GaInP, GaInPAs, or GaPAs is used as the non-radiative recombination preventing layer. Although a small amount of material other than Al may be added to this layer in some cases, the main material is Ga _x In.
_{1−x Py} As _1−y (0 <x ≦ 1, 0 <y ≦ 1). Since the carriers are confined between the low-refractive index layers of the upper and lower reflecting mirrors which are closest to the active layer and have a wide gap, only the active region is constituted by a layer containing no Al (the percentage of group III is 1% or less). However, if the low-refractive index layer (wide gap layer) of the reflector in contact with the active region has a structure containing Al, when carriers are injected and recombined, non-radiative recombination occurs at this interface, and luminous efficiency is reduced. Will drop. Therefore, it is desirable that the active region be formed of a layer containing no Al. The main composition is Ga _x In _1-x P
_The non-radiative recombination preventing layer made of _y As _1-y (0 <x ≦ 1, 0 <y ≦ 1) has a smaller lattice constant than the GaAs substrate and has a tensile strain. In the epitaxial growth, the growth is performed by reflecting the information of the base, and if there is a defect on the surface of the substrate, it goes up to the growth layer. However, it is known that the presence of a strained layer is effective in preventing such defects from climbing. When the defects reach the active layer, the luminous efficiency is reduced. In the case of an active layer having a strain, there arises a problem that the critical thickness is reduced and a layer having a required thickness cannot be grown. In particular, when the amount of compressive strain of the active layer is large, for example, 2% or more, or when the thickness of the strained layer is larger than the critical thickness, even if non-equilibrium growth such as low-temperature growth is performed, growth cannot be performed due to the presence of defects. This is particularly problematic. If a strained layer is present, such a defect can be prevented from climbing up, so that the luminous efficiency can be improved, a layer having a compressive strain of 2% or more of the active layer can be grown, or the thickness of the strained layer can be reduced to a critical film. It becomes possible to grow thicker than thick.

This Ga_xIn_1-xP_yAs_1-y(0
<X ≦ 1, 0 <y ≦ 1) layer is in contact with the active region and is active
It also has the role of confining carriers in the region,
_xIn_1-xP_yAs_1-y(0 <x ≦ 1, 0 <y ≦
1) The band gap energy of the layer decreases as the lattice constant decreases.
It can take large amounts of lugi. For example, Ga_xIn_1-xP
In the case of (y = 1), x increases and approaches GaP.
Increase the lattice constant and the band gap.
You. The band gap Eg is Eg (Γ) =
1.351 + 0.643x + 0.786x², Indirect transition
And Eg (X) = 2.24 + 0.02x
You. Therefore, the active region and Ga_xIn_1-xP_yAs _1-y
(0 <x ≦ 1, 0 <y ≦ 1) layer has a large hetero barrier.
As a result, carrier confinement is improved and threshold current is reduced.
This has the effect of reducing the temperature and improving the temperature characteristics. Furthermore, this Ga_x
In_1-xP_yAs_1-y(0 <x ≦ 1, 0 <y ≦ 1)
The non-radiative recombination prevention layer composed of a layer has a lattice constant of Ga.
Larger than the As substrate, having a compressive strain, and
When the lattice constant of the active layer is Ga_xIn_1-xP_yAs_1
-Y(0 <x ≦ 1, 0 <y ≦ 1) Larger compressive strain than layer
have. In addition, this Ga_xIn_1-xP_yAs
_1-y(0 <x ≦ 1, 0 <y ≦ 1) The direction of strain in the layer is active
Substantial compressive strain perceived by the active layer because it is in the same direction as the layer
Work in the direction of reducing The larger the distortion, the more the influence of external factors
The active layer has a compressive strain of 2% or more, for example.
Is particularly effective when the thickness is large or when the thickness exceeds the critical thickness.
You. For example, a surface emitting laser with an oscillation wavelength of 1.3 μm band
It is preferably formed on a GaAs substrate.
In many cases, a conductor multilayer reflector is used, and the total thickness is
Before growing the active layer, 50 to 80 semiconductor layers of 5 to 8 μm are formed.
Need to be grown (while edge-emitting lasers,
The total thickness before growing the active layer is about 2 μm and about 3 layers.
It is only necessary to grow a semiconductor layer). In this case, high quality
Various causes (even once occurred
Defects basically creep up in the crystal growth direction,
Surface defects on the GaAs substrate
What is the defect density of the surface just before the active layer growth compared to the depression density?
Even if it increases. Insertion of strained layer before active layer growth
In addition, when the effective compressive strain perceived by the active layer is reduced,
To reduce the effect of defects on the surface just before the growth of the conductive layer
become. In this example, in the active area and the mirror and the active area
Since the interface with Al does not contain Al, the carrier injection
Non-light emission due to crystal defects caused by Al when entering
There was no recombination and non-radiative recombination was reduced.

As described above, the interface between the reflector and the active region
In which Al does not contain, that is, non-radiative recombination prevention
The provision of a stop layer can be applied to both upper and lower reflectors.
Although preferred, it is effective to apply it to one of the mirrors.
You. In this example, both the upper and lower reflectors are semiconductor distribution black.
Mirror, but one of the mirrors is a semiconductor distributed Bragg
It is also possible to use a reflecting mirror and the other reflecting mirror as a dielectric mirror
No. In the above-described example, the most active layer of the low refractive index layer of the reflecting mirror is used.
Only the layer close to_xIn_1-xP_yAs_1-y(0 <
x ≦ 1, 0 <y ≦ 1)
Has a plurality of layers of Ga _xIn_1-xP_yAs_1-y(0 <x
≦ 1, 0 <y ≦ 1) may be used as the non-radiative recombination preventing layer.
No. Further, in this example, the distance between the GaAs substrate and the active layer is
Applying this idea to the lower reflector, there is a problem when growing the active layer
The crawling of crystal defects caused by Al onto the active layer
The adverse effect of the active layer is suppressed and the active layer is crystallized with high quality.
Can be lengthened. Due to these, luminous efficiency is high,
A surface emitting semiconductor laser with sufficient reliability for practical use can be obtained.
Was. In addition, the low refractive index layer of the semiconductor distributed Bragg reflector is
Not all but at least the part closest to the active area
Ga not containing l_xIn_1-xP_yAs _1-y(0 <x
≦ 1, 0 <y ≦ 1)
The above effect can be obtained without particularly increasing the number.
coming.

The oscillation wavelength of the surface emitting semiconductor laser manufactured as described above was about 1.2 μm. GaInAs on a GaAs substrate has a longer wavelength due to an increase in the In composition, but with an increase in the amount of strain. Conventionally, up to 1.1 μm has been considered to be the limit of a longer wavelength (see “IEEE Photonics. Tec”).
hnol. Lett. Vol. 9 (1997) pp. 1319-1321 "). However, as produced by the inventor of the present invention, a high strain GaI is formed by a high non-equilibrium growth method such as low temperature growth of 600 ° C. or less.
The nAs quantum well active layer can be grown coherently thicker than before, and the wavelength can reach 1.2 μm. This wavelength is transparent to the Si semiconductor substrate. Therefore, light transmission through the Si substrate becomes possible in a circuit chip in which an electronic element and an optical element are integrated on the Si substrate. As is apparent from the above description, by using GaInAs having a large In composition and a high compression strain for the active layer, G
It has been found that a long-wavelength surface emitting semiconductor laser can be formed on an aAs substrate. As described above, such a surface emitting semiconductor laser can be grown by MOCVD, but other growth methods such as MBE can also be used. Although the triple quantum well structure (TQW) has been described as an example of the stacked structure of the active layer, a structure (SQW, MQW) using a quantum well of another number of wells may be used. The structure of the laser may be another structure. Although the length of the resonator is set to the thickness of λ, it can be set to an integral multiple of λ / 2. Desirably, it is an integral multiple of λ. Although the example using GaAs as the semiconductor substrate has been described, the above concept can be applied to a case where another semiconductor substrate such as InP is used. The period of the reflecting mirror may be another period. In this example, an example in which the main element is a layer composed of Ga, In, and As, that is, Ga _x In _1-x As (GaInAs active layer) is shown as an active layer. Means that N is added and the main elements are Ga, In, N, A
s (GaInNAs active layer).
By actually changing the composition of the GaInNAs active layer, it was possible to perform laser oscillation in each of the 1.3 μm band and the 1.55 μm band. By examining the composition, a surface emitting laser having a longer wavelength, for example, in the 1.7 μm band can be obtained. In addition, GaAsS is used for the active layer.
Even if b is used, a 1.3 μm band surface emitting laser can be realized on a GaAs substrate. Thus, the wavelength of 1.1 μm to 1.7 μm
The conventional semiconductor laser has no suitable material, but the active layer has a high strain of GaInAs, GaInNAs, or GaAsS.
b and the provision of the non-radiative recombination preventing layer, wavelengths of 1.1 μm to 1.
In the long wavelength region of the 7 μm band, a high-performance surface emitting laser can be realized.

Next, the present invention is applied to the optical transmitting / receiving system of the present invention.
Other long-wavelength surface-emitting semiconductor lasers
The configuration will be described with reference to FIG. Again, figure
N-GaAs substrate having a plane orientation of (100) as in the case of 1.
21 is used. Oscillation wave in each medium
N-Al with a thickness 1/4 times the length λ (thickness of λ / 4)_xG
a_1-xAs (x = 0.9) and n-Al_xGa_1-xA
n-semiconductor distribution in which s (x = 0) is alternately stacked for 35 periods
Bragg reflector 24 (Al _0.9Ga_0.1As / Ga
As lower reflector), and a λ / 4-thick n is formed thereon.
-Ga_xIn_1-xP_yAs_1-y(X = 0.5, y =
1) Layers were laminated. In this example, n-Ga_xIn_1-xP
_yAs_1-yThe (x = 0.5, y = 1) layer is also the lower reflector
It is a part and is a low refractive index layer. And on top of that,
Undoped lower GaAs spacer layer 23 and three Ga layers
_xIn_1-xN_yAs_1-yActive layer 3 which is a quantum well layer
3 (quantum well active layer) and GaAs barrier layer 34 (15n
m) of the multi-quantum well active layer (3 in this example)
Quantum well (TQW)) and undoped upper GaAs
An oscillation wavelength in the medium is formed by laminating the
A resonator having a thickness of one wavelength (thickness of λ) is formed.
You. In addition, a p-semiconductor distributed Bragg reflector
(Upper reflector) 24 is formed. The upper reflector is
The AlAs layer 27 serving as the selectively oxidized layer is formed as a GaInP layer.
Low refractive index layer having a thickness of 3λ / 4 sandwiched between AlGaAs layers
(C-doped p-Ga having a thickness of (λ / 4-15 nm)_xI
n_1-xP_yAs_1-y(X = 0.5, y = 1) layer, C
Doped p-Al_zGa_1-zAs (z = 1) selective oxidation
Layer (thickness 30 nm), thickness (2λ / 4-15 nm)
C-doped p-Al_xGa_1-xAs layer (x = 0.9)
GaAs layer (one period) having a thickness of λ / 4, and C-doped
P-Al_xGa_{1 -X}As layer (x = 0.9) and pA
l_xGa_1-xAs (x = 0) layer in each medium
Period alternately stacked with a thickness of 1/4 of the oscillation wavelength
Structure (22 periods)
Reflector (Al_0.9Ga_0.1As / GaAs upper part
Reflecting mirror). Note that in this example as well, FIG.
Although illustration is omitted because it is complicated, semiconductor components
The structure of the cloth Bragg reflector has a low refraction as shown in Fig. 2.
Index layer (low refractive index layer) and high refractive index layer (high refractive index layer)
In the meantime, Al whose refractive index takes a value between small and large_zGa_1-z
Heterospike relaxation consisting of As (0 ≦ y <z <x ≦ 1)
An opposing layer is provided. And the topmost p-Al
_xGa_1-xThe As (x = 0) layer connects the electrode and the contact.
Contact layer (p-contact layer)
They also have a role.

Here, the In composition x of the quantum well active layer is 37
%, And the N (nitrogen) composition was 0.5%. Also the quantum well activity
The thickness of the conductive layer was 7 nm. In addition, this surface-emitting type semiconductor laser
The laser was grown by MOCVD. Semiconductor laser
The raw material for each layer is TMA (trimethylaluminum).
), TMG (trimethylgallium), TMI (g)
Limethylindium), AsH₃(Arsine), PH₃
(Phosphine), and DMHy
Methylhydrazine) was used. DMHy decomposes at low temperature
Therefore, it is suitable for low-temperature growth below 600 ° C.
A highly strained quantum well layer that requires low temperature growth
Preferred in the case. The carrier gas is H₂Was used.
In this example, a GaInNAs layer (quantum well active layer) is used.
Grew at 540 ° C. MOCVD has a high degree of supersaturation
Suitable for crystal growth of materials containing N and other V-groups at the same time
You. Also, high vacuum is not required unlike the MBE method,
Control the supply flow rate and supply time of
Is also excellent. Furthermore, in this example, a mesa
Part is p-Ga_xIn_1-xP_yAs _1-y(X = 0.
5, y = 1) p-Al until the layer is reached_zGa_1-zA
s (z = 1) is formed by exposing the side surface of the selective oxidation layer,
Al that appeared on the side_zGa_1-zAs (z = 1) layer is steamed
Oxidized from the side with air_xO_yForming a current narrowing layer
ing. Finally, mesa etching with polyimide (insulating film)
Embed the part removed in step and flatten it.
Remove the polyimide and place the light emitting part on the p-contact layer.
Excluding the p-side electrode, and the n-side electrode on the back of the GaAs substrate.
The pole was formed.

In this example, the lower part of the selectively oxidized layer
Ga as part of the top reflector_xIn _1-xP_yAs
_1-y(0 <x ≦ 1, 0 <y ≦ 1) layers are inserted.
For example, in the case of wet etching, a sulfuric acid etcher
By using a component, GaInPA can be used for the AlGaAs system.
The s-system can be used as an etch stop layer
, Ga_xIn_1-xP_yAs_1-y(0 <x ≦ 1, 0
<Y ≦ 1) Insertion of layer allows selective oxidation
Can be strictly controlled. others
Therefore, uniformity and reproducibility can be improved, and cost can be reduced.
In addition, the surface emitting semiconductor laser (element) of this example is reduced to one dimension.
Or two-dimensional integration, controllability during device fabrication
Improves the characteristics of each element in the array.
The effect is that the uniformity and reproducibility of
You. In this example, G serving as an etching stop layer is also used.
a_xIn_1-xP_yAs_{1 -Y}(0 <x ≦ 1, 0 <y ≦
1) The layer is provided on the upper reflector side, but is provided on the lower reflector side
May be. In this example, too,
In addition, the active region where carriers are injected and recombine (this embodiment)
Then, the upper and lower spacer layers and the multiple quantum well active layer
Including the Al in the active region.
Low refractive index layers of lower and upper reflectors without using materials
The layer closest to the active layer of_xIn_1-xP_yAs
_1-yNon-radiative recombination prevention (0 <x ≦ 1, 0 <y ≦ 1)
And layers. That is, in this example, the
The interface between the mirror and the active region should not contain Al
Therefore, at the time of carrier injection, crystal defects caused by Al
Can reduce non-radiative recombination due to entrapment
You. It should be noted that the interface between the reflector and the active region does not contain Al.
It is preferable to apply the configuration to the upper and lower reflectors as in this example.
It is effective even if applied to only one of the reflectors
There is. In this example, both the upper and lower reflecting mirrors have a semiconductor distribution block.
Rag reflector was used, but one reflector was
And the other reflector as a dielectric reflector
good. Further, also in this example, between the GaAs substrate and the active layer.
The same idea as in the example of FIG. 1 was applied to the lower reflector of
Therefore, a crystal caused by Al, which is a problem when growing the active layer,
Negative effects due to crawling of defects into active layer are suppressed
As a result, the active layer can be grown with high quality crystals. What
In addition, such a non-radiative recombination preventing layer is provided in FIG. 1 and FIG.
In either configuration, a semiconductor distributed Bragg reflector
The thickness of the oscillating wave in the medium.
The thickness is set to １ ／ of the length λ (thickness of λ / 4). Ah
Alternatively, a plurality of layers may be provided.

Although an example in which the non-radiative recombination preventing layer is provided on a part of the semiconductor Bragg reflector has been described above, the non-radiative recombination preventing layer may be provided in the resonator. For example,
The resonator section is composed of an active layer composed of a GaInNAs quantum well layer and a GaAs barrier layer, and GaAs is a first barrier layer.
A structure in which a non-radiative recombination preventing layer made of nPAs, GaAsP, and GaInP is used as the second barrier layer is exemplified. The thickness of the resonator section can be one wavelength. Since the band gap of the non-radiative recombination prevention layer is larger than that of the GaAs first barrier layer, the active region into which carriers are injected substantially extends to the GaAs barrier layer. Also, the remaining Al raw material,
In the case where a step of removing an Al reactant, an Al compound, or Al is provided, the step may be provided in the middle of the non-radiative recombination preventing layer, or a GaAs layer may be provided between the non-radiative recombination preventing layer and the layer containing Al. And can be performed in the middle of the layer. As is clear from the above description, a surface-emitting type semiconductor laser having high luminous efficiency and sufficient reliability for practical use was obtained with such a configuration. Also, not all of the low refractive index layers of the semiconductor distributed Bragg reflector, but at least the portion closest to the active region is Ga _x In containing no Al.
_{1-x Py} As _1-y (0 <x ≦ 1, 0 <y ≦ 1) is used as the non-radiative recombination preventing layer, so that the above-described effect can be obtained without particularly increasing the number of stacked reflectors. I was able to. In addition, even with such a configuration, since the polyimide can be easily embedded, the wiring (the p-side electrode in this example) is hardly disconnected, and a device having high reliability can be obtained. The oscillation wavelength of the surface emitting semiconductor laser manufactured in this manner was about 1.3 μm. In this example, the main element is Ga,
A layer composed of In, N, and As was used for the active layer (GaIn
(NAs active layer), a long-wavelength surface emitting semiconductor laser could be formed on the GaAs substrate. Also, the current was narrowed by selective oxidation of the selectively oxidized layer mainly composed of Al and As, so that the threshold current was low. According to the current narrowing structure using the current narrowing layer made of the Al oxide film in which the selective oxidation layer is selectively oxidized, the current spreading can be suppressed by forming the current narrowing layer close to the active layer, so that the current narrowing can be prevented from being exposed to the atmosphere. Carriers can be efficiently confined in the region. Further, by oxidizing to form an Al oxide film, the refractive index is reduced, light can be efficiently confined in a minute region in which carriers are confined by the effect of a convex lens, the efficiency is extremely improved, and the threshold current can be reduced. . In addition, since the current narrowing structure can be easily formed, the manufacturing cost can be reduced.

As is clear from the above description, a 1.3 μm band surface emitting semiconductor laser can be realized in the configuration as shown in FIG. 10 as in the case of FIG. Is obtained. The surface-emitting type semiconductor laser shown in FIG. 10 can be grown by MOCVD as in the case of FIG. 1, but other growth methods such as MBE can also be used. Although DMHy is used as a nitrogen source, activated nitrogen and other nitrogen compounds such as NH ₃ may be used. Furthermore, although an example of a triple quantum well structure (TQW) has been shown as the stacked structure of the active layer, a structure (SQW, DQW, MQW) using a quantum well of another number of wells may be used. The structure of the laser may be another structure. In the surface-emitting type semiconductor laser shown in FIG. 10, the composition of the GaInNAs active layer is changed to 1.
A surface emitting semiconductor laser in the 55 μm band, and even in the longer wavelength 1.7 μm band, is also possible. The GaInNAs active layer may contain other III-V elements such as Tl, Sb, and P. Also, even if GaAsSb is used for the active layer, a 1.3 μm band surface emitting semiconductor laser can be realized on a GaAs substrate. In the present invention, as an active layer, a main element is a layer made of Ga, In, or As (GaInAs active layer), or a main element added with N is Ga, In, or
Although the description has been given using the layer composed of N and As (GaInNAs active layer), other than GaNAs, GaPN, GaN
PAs, GaInNP, GaNAsSb, GaInNA
sSb and the like can also be suitably used. Particularly in the case of an active layer containing nitrogen as in these examples, the non-radiative recombination preventing layer of the present invention is particularly effective. This will be described below.

FIG. 11 shows a room-temperature photoluminescence spectrum of an active layer having a GaInNAs / GaAs double quantum well structure comprising a GaInNAs quantum well layer and a GaAs barrier layer manufactured by our MOCVD apparatus. FIG. 12 shows a sample structure. 20 on GaAs substrate
1, a lower cladding layer 202, an intermediate layer 203, an active layer 204 containing nitrogen, an intermediate layer 203, and an upper cladding layer 205.
Are sequentially laminated. In FIG. 11, A is AlGa
A sample in which a double quantum well structure is formed on an As clad layer with a GaAs intermediate layer interposed therebetween, and a sample B in which a double quantum well structure is continuously formed with a GaAs intermediate layer interposed on a GaInP clad layer. It is. As shown in FIG. 11, the photoluminescence intensity of Sample A is lower than that of Sample B by less than half. Therefore, when an active layer containing nitrogen such as GaInNAs is continuously formed on a semiconductor layer containing Al as a constituent element such as AlGaAs using one MOCVD apparatus, the emission intensity of the active layer is deteriorated. A problem arose. Therefore, the threshold current density of the GaInNAs-based laser formed on the AlGaAs cladding layer is 2 times smaller than that formed on the GaInP cladding layer.
More than twice as high. The elucidation of this cause was examined. FIG. 13 shows the nitrogen and oxygen concentrations when an element having a cladding layer of AlGaAs, an intermediate layer of GaAs, and an active layer of a GaInNAs / GaAs double quantum well structure was formed using a single epitaxial growth apparatus (MOCVD). FIG. 5 is a diagram showing a distribution in a depth direction. The measurement was performed by SIMS. Table 1 shows the measurement conditions.

[Table 1] In FIG. 13, two nitrogen peaks are observed in the active layer corresponding to the GaInNAs / GaAs double quantum well structure. Then, an oxygen peak is detected in the active layer. However, the oxygen concentration in the intermediate layer containing neither N nor Al is about one digit lower than the oxygen concentration in the active layer. On the other hand, the cladding layer is made of GaInP, the intermediate layer is made of GaAs, and the active layer is made of GaInNAs / GaAs2.
When the distribution of the oxygen concentration in the depth direction was measured for the element configured as the quantum well structure, the oxygen concentration in the active layer was at the background level. That is, when a semiconductor light emitting device having a semiconductor layer containing Al between a substrate and an active layer containing nitrogen is continuously grown by a single epitaxial growth apparatus using a nitrogen compound raw material and an organic metal Al raw material, Our experiments revealed that oxygen was incorporated into the active layer containing nitrogen. Oxygen incorporated in the active layer forms a non-radiative recombination level,
The luminous efficiency of the active layer is reduced. Oxygen incorporated in this active layer causes A between the substrate and the active layer containing nitrogen.
It has been newly found that this is a cause of lowering the luminous efficiency of a semiconductor light emitting element provided with a semiconductor layer containing l. The origin of this oxygen is considered to be a substance containing oxygen remaining in the apparatus or a substance containing oxygen contained as an impurity in the nitrogen compound raw material.

Next, the cause of the incorporation of oxygen was examined. FIG. 14 is a diagram illustrating the distribution of Al concentration in the depth direction of the same sample as in FIG. 13. The measurement was performed by SIMS. Table 2 shows the measurement conditions.

[Table 2] FIG. 14 shows that Al was detected in the active layer into which the Al material was not originally introduced. However, in the intermediate layer (GaAs layer) adjacent to the semiconductor layer containing Al (cladding layer), the Al concentration is about one digit lower than that of the active layer. This indicates that Al in the active layer is not diffused, replaced or mixed in from the semiconductor layer (cladding layer) containing Al. On the other hand, like GaInP, Al
When an active layer containing nitrogen was grown on a semiconductor layer containing no, Al was not detected in the active layer. Therefore,
The Al detected in the active layer is the Al source remaining in the growth chamber or in the gas supply line, or an Al reactant, or an Al compound, or Al reacts with the nitrogen compound source or impurities (such as moisture) in the nitrogen compound source. It is bonded and taken into the active layer. That is, when a semiconductor light emitting device having a semiconductor layer containing Al between a substrate and an active layer containing nitrogen is continuously crystal-grown by a single epitaxial growth apparatus using a nitrogen compound raw material and an organic metal Al raw material. It was newly found that Al was naturally taken into the active layer containing nitrogen.

Compared with the depth distribution of nitrogen and oxygen concentrations in the same device shown in FIG. 14, the two oxygen peak profiles in the double quantum well active layer do not correspond to the nitrogen concentration peak profiles. 14 corresponds to the Al concentration profile of FIG. From this, GaIn
Oxygen impurities in the NAs well layer are more likely to be introduced into the well layer than to be taken in with the nitrogen source.
It was clarified that they were incorporated together with l. That is, the Al raw material remaining in the growth chamber or Al
When the reactant, or Al compound, or Al comes into contact with the nitrogen compound raw material, Al is combined with a substance containing oxygen such as water contained in the nitrogen compound raw material or water remaining in the gas line or the reaction chamber. Then, Al and oxygen are taken into the active layer. Our experiments have clarified for the first time that oxygen taken into the active layer has reduced the luminous efficiency of the active layer. So to improve this,
At least the Al source material, the Al reactant, or the Al compound, or the Al remaining in the growth chamber in a place where the nitrogen compound source material or the impurities contained in the nitrogen compound source material touch.
It has been found that it is necessary to provide a step of removing.

If this step is provided between the growth of the semiconductor layer containing Al and the start of the growth of the active layer containing nitrogen, when a nitrogen compound material is supplied to the growth chamber for growing the active layer containing nitrogen, Residual Al raw material or Al reactant,
Alternatively, an Al compound or Al reacts with a nitrogen compound raw material or an impurity contained in the nitrogen compound raw material and a substance containing oxygen remaining in the device to reduce the concentration of Al and oxygen impurities taken into the active layer. We were able to. Further, it is preferable to remove the non-radiative recombination preventing layer after the growth thereof, since the adverse effect on non-radiative recombination in the active layer can be suppressed when carriers are injected into the active layer by current injection. For example, by reducing the Al concentration in the active layer containing nitrogen to 1 × 10 ¹⁹ cm ⁻³ or less,
Room temperature continuous oscillation became possible. Further, by reducing the Al concentration in the nitrogen-containing active layer to 2 × 10 ¹⁸ cm ⁻³ or less, light emission characteristics equivalent to those formed on a semiconductor layer containing no Al were obtained. Al source or Al reactant or Al remaining in the growth chamber where the nitrogen compound source or impurities contained in the nitrogen compound source touch.
The step of removing the compound or Al includes, for example, providing a step of purging with a carrier gas. Here, the time of the purge step is set after the growth of the Al-containing semiconductor layer is completed and the supply of the Al raw material to the growth chamber is stopped.
It refers to an interval until a nitrogen compound raw material is supplied to a growth chamber to start growth of a semiconductor layer containing nitrogen. As a method of the purging, there is a method of interrupting the growth in an intermediate layer containing neither Al nor nitrogen and purging with a carrier gas. In the case where the growth is interrupted and the purge is performed, the place where the growth is interrupted can be provided between the growth of the Al-containing semiconductor layer and the middle of the non-radiative recombination preventing layer.

FIG. 15 shows an example of a sectional structural view of a semiconductor light emitting device for explaining that a step of purging with a carrier gas in the present invention is provided. 15, a first semiconductor layer 202 containing Al as a constituent element, a first lower intermediate layer 601, a second lower intermediate layer 602, an active layer 204 containing nitrogen, and an upper intermediate layer 20 are formed on a substrate 201.
Third, the second semiconductor layer 205 is sequentially stacked. For crystal growth, an epitaxial growth apparatus using an organic metal Al raw material and an organic nitrogen raw material is used. A growth interruption step is provided between after the growth of the first lower intermediate layer and the start of the growth of the second lower intermediate layer. During the growth interruption, the Al source material, the Al reactant, or the Al compound, or the Al remaining in the growth chamber where the nitrogen compound source material or the impurities contained in the nitrogen compound source material touch is purged with hydrogen as a carrier gas. Has been removed. FIG.
6 is a first lower intermediate layer 601 and a second lower intermediate layer 60
2 shows a measurement result of the distribution of the Al concentration in the depth direction in a semiconductor light emitting device in which the growth was interrupted between 2 and the purge time was set to 60 minutes. As shown in FIG. 16, the Al concentration in the active layer is 3 ×
It could be reduced to 10 ¹⁷ cm ⁻³ or less. This value is about the same as the Al concentration in the intermediate layer. FIG.
FIG. 7 shows the result of measuring the distribution of the nitrogen and oxygen concentrations in the depth direction for the same device. As shown in FIG. 17, the oxygen concentration in the active layer was reduced to a background level of 1 × 10 ¹⁷ cm ⁻³ . The reason why a peak appears in the oxygen concentration in the lower intermediate layer is that oxygen segregates at the growth interruption interface. Therefore, in the case of purging after interrupting the growth, it is preferable that the place where the growth is interrupted be provided after the growth of the Al-containing semiconductor layer until the end of the growth of the non-radiative recombination preventing layer. The non-radiative recombination prevention layer can increase the bandgap energy compared to the quantum well active layer and the barrier layer. This is because adverse effects due to the above can be suppressed. When an active layer containing nitrogen is used as described above, providing a non-radiative recombination preventing layer is particularly effective.

In this semiconductor light emitting device, the growth is interrupted between the first lower intermediate layer and the second lower intermediate layer, and the purge time is reduced to 6 hours.
By providing for 0 minutes, Al and O in the active layer containing nitrogen are removed.
, Etc. could be reduced. This allows
The luminous efficiency of the active layer containing nitrogen could be improved.
In the step of purging the growth chamber with a carrier gas, by purging the susceptor while heating it,
The Al raw materials and reaction products adsorbed on the susceptor or around the susceptor can be degassed and removed efficiently. However, when the substrates are heated simultaneously, it is necessary to keep supplying a group V source gas such as AsH ₃ or PH ₃ to the growth chamber even during the interruption of the growth, in order to prevent the semiconductor layer on the outermost surface from being thermally decomposed. is there. Further, when purging the growth chamber with a carrier gas, the substrate can be transferred from the growth chamber to another chamber. By transporting the substrate from the growth chamber to another chamber, there is no need to supply a group V source gas such as AsH ₃ or PH ₃ to the growth chamber when purging while heating the susceptor. Therefore, the thermal decomposition of the reaction product containing Al deposited around the susceptor or the susceptor can be further promoted. Thereby, the Al concentration in the growth chamber can be efficiently reduced. Also,
There is a method of purging while growing the intermediate layer. Since the non-radiative recombination preventing layer is provided between the AlGaAs-based reflecting mirror containing Al and the active layer containing nitrogen,
Since the distance between the layer containing Al and the active layer containing nitrogen becomes longer, there is an advantage that the purge time can be lengthened even when purging is performed while growing. In this case, it is better to slow down the growth rate and lengthen the time. In addition, Al containing Al
There is also a method in which a GaAs-based reflecting mirror and an active layer containing nitrogen are formed by different apparatuses. Even in this case, if the regrowth interface is provided below the non-radiative recombination preventing layer, the concentration of impurities such as Al and O in the active layer containing nitrogen can be reduced.

When a crystal growth method is used without using an organic metal Al raw material and a nitrogen compound raw material as in a normal MBE method, a semiconductor layer containing Al is provided between a substrate and an active layer containing nitrogen. No report has been made on the decrease in luminous efficiency of the semiconductor light emitting device. On the other hand, in the MOCVD method, it has been reported that the luminous efficiency of a GaInNAs active layer formed on a semiconductor layer containing Al decreases. Electron.Let
t., 2000, 36 (21), pp1776-1777, the same MOC
Even when an intermediate layer made of GaAs is provided on the AlGaAs cladding layer in the VD growth chamber, GaInNAs is continuously formed.
It has been reported that when a quantum well layer is grown, the photoluminescence intensity is significantly deteriorated. In the above report, in order to improve the photoluminescence intensity, A
An lGaAs cladding layer and a GaInNAs active layer are grown in different MOCVD growth chambers. Therefore, MOCV
In the case of a crystal growth method using an organic metal Al raw material and a nitrogen compound raw material as in the method D, this is a problem that occurs at least.

In the MBE method, crystal growth is performed under ultra-low pressure (in a high vacuum), whereas in the MOCVD method, several tens of To
Since the pressure in the reaction chamber is higher than that of the MBE method from rr to about atmospheric pressure, the mean free path is extremely short, and the supplied raw material and carrier gas come into contact with and react with others in a gas line, a reaction chamber, or the like. It is thought to be. Therefore, in the case of a growth method in which the pressure in the reaction chamber or gas line is high, such as the MOCVD method, it is more preferable to prevent non-radiative recombination after the growth of the semiconductor layer containing Al and before the growth of the active layer containing nitrogen. Until the end of the layer growth, an Al source or an Al reactant, or an Al compound remaining in a place where the nitrogen compound source or an impurity contained in the nitrogen compound source touches in the growth chamber.
Alternatively, when a step of removing Al is provided, the effect of preventing oxygen from being taken into the active layer containing nitrogen is high.
For example, there is a method in which a gas line or a growth chamber is evacuated after growing a semiconductor layer containing Al and before growing an active layer containing nitrogen. In this case, the effect is high if heating is performed. There is also a method of removing the semiconductor layer containing Al by flowing an etching gas after growing the semiconductor layer before growing the active layer containing nitrogen. An example of a gas that can react with and remove an Al-based residue is an organic-based compound gas. As described above, when a DMHy gas, which is one of the organic compound gases, is supplied using a DMHy cylinder during the growth of the active layer containing nitrogen, it is apparent that the gas reacts with the Al-based residue. Therefore, when the organic compound gas is supplied using the organic compound gas cylinder after the growth of the semiconductor layer containing Al and before the growth of the active layer containing nitrogen, a jig for holding the reaction chamber side wall, the heating zone, and the substrate is used. And the like, can be removed by reacting with the Al-based residue remaining in the active layer, etc., so that the incorporation of oxygen into the active layer can be suppressed. Furthermore, it is preferable to use the same gas as the nitrogen material of the active layer containing nitrogen, since it is not necessary to add a special gas line. This step may be performed by interrupting the growth, and includes GaNAs, GaInNAs, Ga
A layer containing nitrogen such as an InNP layer may be formed by crystal growth as a dummy layer separately from the active layer. It is preferable to perform the Al removal step by crystal growth as compared with the case where the growth is interrupted, because there is no time loss. When GaInAs is used for the active layer, up to 1.1 μm has conventionally been considered to be the limit of increasing the wavelength.
The aInAs quantum well active layer can be grown thicker than before, and the wavelength can reach up to 1.2 μm. As described above, a semiconductor laser having a wavelength of 1.1 μm to 1.7 μm has not conventionally been available with a suitable material.
By using nAs, GaInNAs, and GaAsSb, and by providing a non-radiative recombination prevention layer, a high-performance surface emitting laser can be realized in a long wavelength region of a wavelength of 1.1 μm to 1.7 μm where stable oscillation has conventionally been difficult. It is now possible to apply it to optical communication systems.

FIG. 18 shows an example in which such a long wavelength band surface emitting semiconductor laser device is formed as a large number of chips on an n-GaAs wafer 40 having a (100) plane orientation, and a laser device chip. In the laser element chip shown here, 1 to n laser elements 41 are formed, and the number n and the arrangement method are determined according to the application. As described above, in order to realize a long-wavelength surface emitting laser of 1.1 μm to 1.7 μm in the present invention, GaInAs, GaInNAs, and GaAs having high strain are required.
The sSb active layer is important, and therefore, it is necessary to minimize mechanical stress. As the mechanical stress, there is a thermal stress generated between the semiconductor laser and the mounting substrate due to the environment, heat generated by the semiconductor laser itself, and a driving circuit in the operating temperature range of the system. This thermal stress is generated by trying to maintain the shape by being fixed and bound to each other because the coefficient of linear expansion differs depending on the material with respect to the temperature change. It depends on the coefficient of linear expansion, Young's modulus, and the like. In order to prevent such thermal stress from occurring, it is conceivable to keep the temperature of the module including the semiconductor laser constant. However, it is also costly and it is difficult to keep the temperature completely constant in practical use. is there. Therefore, in order to provide a low-cost and highly reliable system, it is desirable to use a member having a similar linear expansion coefficient to that of the semiconductor laser to be used, and to reduce the influence of the thermal stress on the semiconductor laser.

In view of this point, in the present invention, mounting substrates were manufactured from various materials having different linear expansion coefficients, and the thermal stress generated during actual laser oscillation and the output characteristics of the laser accompanying the stress were examined. The surface emitting laser used is that shown in FIG. 1 and has an oscillation wavelength of 1.3 μm. The chip size is 5mm × 10
A laser device having 20 mm in thickness (0.6 mm in thickness) and 20 laser elements formed in one row at a pitch of 300 μm was used. On the other hand, the size of the mounting substrate was 10 mm × 20 mm (2 mm thick). The results are shown below. In the table, ○ indicates that a stable output was obtained in a use environment of 0 to 70 ° C., and X indicates that a stable output was not obtained and was not practically used. Material Linear expansion coefficient Laser output characteristics Quartz glass 0.3 × 10 ^-6 / K × Sumicrystal 2 × 10 ^-6 / K × CVD diamond 2 × 10 ^-6 / K × Si 4 × 10 ^-6 / K ○ SiC 4 × 10 ^-6 / K ○ AlN 5 × 10 ^-6 / K ○ GaAs 6 × 10 ^-6 / K ○ Al-Si (60Al-40Si) 15 × 10 ^-6 / K × Cu 17 × 10 ^-6 / K × book The linear expansion coefficient of the semiconductor laser of the present invention is 6 × 10 ⁻⁶ / K
It is. Therefore, from the above results, if the difference between the linear expansion coefficients of the semiconductor laser and the mounting substrate is within about 2 × 10 ⁻⁶ / K, the thermal stress generated during laser oscillation and the output characteristics of the laser accompanying it are stable. It turns out that it is practical. Among them, Si, SiC, GaAs, AlN
Is a material that can be particularly preferably used in terms of material availability, fabrication as a mounting substrate, and ease of processing.

Also, by selecting a heat dissipating member that fixes the mounting substrate to a material having a coefficient of linear expansion close to that of the semiconductor laser, distortion to the mounting substrate is reduced, and mechanical stress applied to the semiconductor laser is reduced. Is done.
Furthermore, since it is used as a heat radiating member, it is required to have high thermal conductivity. In view of this point, in the present invention, a heat radiating member was manufactured from various materials having different thermal conductivity, and the output characteristics of the laser due to heat generated during actual laser oscillation were examined. The surface emitting laser used was the same as that used in the study of the mounting substrate, and SiC was used here as the mounting substrate. The size is also the same as in the above study. The results are shown below. In the table, ○ indicates that a stable output was obtained in a use environment of 0 to 70 ° C., and X indicates that a stable output was not obtained and was not practically used. Material Thermal conductivity Laser output characteristics SiO ₂ 〜8 W / mK × alumina (Al ₂ O ₃ ) 1717 W / mK × Kohal 1717 W / mK × AlN 200200 W / mK ○ Cu / W 180∼200 W / mK ○ W 〜 170 W / mK Mo-160 W / mK Cu-390 W / mK The semiconductor laser of the present invention has a thermal conductivity of 55 W / mK. Therefore, it can be seen from the above results that good results are obtained when the heat conductivity of the heat radiation member is larger than the heat conductivity of the semiconductor laser of the present invention. In other words, when the heat conductivity of the heat radiating member is larger than the heat conductivity of the semiconductor laser of the present invention, heat generated during laser oscillation is transmitted to the mounting substrate, and then transmitted to the heat radiating member without returning to the semiconductor laser side. Can be escaped efficiently. Therefore, it can be seen that the output characteristics of the laser do not fluctuate due to heat storage, and stable and practical characteristics can be obtained. Among them, AlN, Cu
/ W, W, Mo, and Cu are materials that can be particularly suitably used from the viewpoint of availability of materials, production as a heat radiation member, and ease of processing. Particularly, Cu / W in which the composition ratio is controlled and the heat conduction is in the above range is very preferable because it can be used also as a package substrate as shown in FIG. 20 described later.

An example of an optical communication system using such members will be described below. The communication system is composed of a light emitting unit having a surface emitting semiconductor laser and its driving circuit, a light receiving unit having a surface light receiving element and its driving circuit, and an optical fiber or an optical waveguide acting as a transmission path between them. I have. The drive circuits for the semiconductor laser and the surface-type light receiving element are mounted on the same mounting substrate as the respective elements, or are formed on the semiconductor laser element formation substrate by a wafer process in the same manner as the laser element formation. In addition, by providing an optical transmitting unit and an optical receiving unit on both sides of the optical transmission path, an optical communication system that performs bidirectional communication can be realized. FIG. 19 shows an example of an optical transmission unit of such an optical communication system. The light transmitting unit includes a surface-emitting type semiconductor laser 50, a driving circuit 51 for driving the semiconductor laser, a mounting substrate 52 for mounting these components, a heat radiating member 53 for adjusting the position and radiating heat of the semiconductor laser, and holding a heat radiating member. And a metal package 54 used as a radiation fin and an optical fiber 55 as an optical transmission path. The metal package 54, the heat radiating member 53, and the mounting board 52 are mechanically and thermally connected by solder or resin. The semiconductor laser 50 and the drive circuit 51 are electrically connected by wire bonding or the like. Here, as a semiconductor laser, the configuration shown in FIG. 1 has an oscillation wavelength of 1.2 μm.
Was used. Linear expansion coefficient 4 × 1 as mounting board
A Si substrate of 0 ^-6 / K, AuSn a semiconductor laser
Die bonding was performed with solder, and the electrodes were electrically and mechanically connected. A 200 nm SiO ₂ film is formed on the surface of the Si substrate. Here, thermal oxidation was used, but CV
An SiO ₂ film formed of D or SOG may be used. Although the oxide film is used for insulation, since the heat radiation property is inferior to that of Si, it is desirable that the oxide film be as thin as possible within a sufficient range of insulation. Similarly, a drive circuit for driving the semiconductor laser was fixed on the same mounting substrate. As a heat-dissipating member fixing this mounting board, A having high thermal conductivity and matching of linear expansion coefficient
1N (linear expansion coefficient 5 × 10 ⁻⁶ / K, thermal conductivity 200 W
/ MK), and a powder molded product of Cu / W was used for the metal package. The composition ratio is 89W-11Cu,
The linear expansion integer is 6.5 × 10 ⁻⁶ / K, and the thermal conductivity is 1
It was 80 W / mK. Such a powder molded product can obtain high dimensional accuracy at low cost, and can be easily formed such as a radiation fin or a shape, and can efficiently radiate heat. Here, a multimode optical fiber having a core diameter of 50 μm was used and optically connected to the semiconductor laser. Examination of such an optical communication system in a use environment of 0 to 70 ° C. has revealed that the laser output is stable, the characteristics do not change, the life is not deteriorated, and an excellent optical communication system is possible.

Instead of the Si substrate, GaAs (linear expansion coefficient 6 × 10 ⁻⁶ / K) or AlN (linear expansion coefficient 5 × 10
⁻⁶ / K) or SiC (linear expansion coefficient: 4 × 10 ⁻⁶ / K) substrate was used as a mounting substrate, and good results were obtained.
In the case of an AlN or SiC substrate, since it is an insulating substrate,
No oxide film was formed. Otherwise, it has the same structure as above. In terms of handling and cost, Si and AlN
Is preferable as a mounting substrate. In addition, as a heat dissipation member,
89W-11Cu or 85W-15C instead of AlN
u, Cu / W of 80W-20Cu (their coefficient of linear expansion is 6 to 8 × 10 ⁻⁶ / K, and the thermal conductivity is 180 to 200
W / mK), W, Mo and Cu. Here, although the semiconductor laser of the transmission unit is used alone, a mounting substrate material and a heat radiation member as in the present invention are particularly suitably used in a large-capacity optical communication system in which a plurality of the semiconductor lasers are arrayed. For example, in the case of a multi-laser array chip in which a plurality of laser elements are formed on one chip by utilizing the features of the surface emitting semiconductor laser of the present invention, since a plurality of laser elements are formed in close proximity,
Heat generation due to laser oscillation, thermal stress due to heat storage, and fluctuations in laser output characteristics due to heat generation are particularly problematic. Further, a laser element driving circuit may be formed on such a chip at the same time, and the heat generated from the driving circuit is also superimposed, which causes a further problem. Even in that case, by appropriately selecting the mounting board material and the heat dissipation member as in the present invention, without any problem,
A stable laser output is obtained.

Conventionally, the oscillation wavelength as in the present invention is 1.
Since there was no surface emitting semiconductor laser device having a thickness of 1 μm to 1.7 μm, technical problems in mounting a communication system using such a device and mounting a surface emitting semiconductor laser chip in such a long wavelength band were clarified. I didn't. However, for the first time, specific technical problems have been recognized by the present invention, and the solution has been clarified.
Further, the optical transmission line for optical coupling with the semiconductor laser is also a multimode fiber, but may be an optical waveguide, a single mode optical fiber, a plastic optical fiber, or the like. The semiconductor laser of the present invention does not need to use a high-cost heat radiation member such as a Peltier device module, but does not prevent the use thereof. Next, another embodiment of the present invention is shown in FIG. 19 shows an optical transmission unit of the optical communication system as in FIG. In this embodiment, the heat radiation member also functions as a metal package. The optical transmitter includes a laser array chip 56 in which a plurality of laser elements are arrayed on a single chip, a drive circuit for driving a semiconductor laser, a mounting board 57 on which these are mounted, and a heat sink and a radiation fin. And an optical fiber 59 as an optical transmission line and a ferrule 60 fixing the same. The metal package 58 and the mounting board 57 are mechanically and thermally connected by solder or resin. The semiconductor laser and a drive circuit (not shown) are electrically connected by wire bonding or the like.

Here, the semiconductor laser shown in FIG. 8 was used, and an element having an oscillation wavelength of 1.3 μm and being arrayed in four at the same pitch of 250 μm as the opposing optical fiber was used. As in the previous embodiment, an Si substrate was used as a mounting substrate, and a semiconductor laser was die-bonded with AuSn solder to be electrically and mechanically connected to electrodes. A 200 nm SiO ₂ film is formed on the surface of the Si substrate. Here, thermal oxidation is used, but CVD or SOG may be used. Although the oxide film is used for insulation, the heat dissipation characteristic is S
Since it is inferior to i, it is desirable that the insulating property is as thin as possible within a sufficient range. Similarly, a drive circuit (not shown) for driving the semiconductor laser was fixed on the same mounting substrate. The metal package for fixing the mounting substrate and also serving as a heat dissipation member includes Cu /
A powder molded product of W was used. Its composition ratio is 89W-11.
The coefficient of linear expansion of Cu was 6.5 × 10 ⁻⁶ / K, a value close to the linear expansion coefficients of the semiconductor laser and the mounting substrate, and the thermal conductivity was 180 W / mK. Such a powder molded product can obtain high dimensional accuracy at low cost, and can be easily formed such as a radiation fin or a shape, and can efficiently radiate heat. A multi-mode optical fiber having a core diameter of 50 μm is used as an optical transmission line.
Four of them were arranged at a pitch of 50 μm and optically connected to a semiconductor laser. Such an optical communication system is set at 0 to 70 ° C.
Investigations have been made in the use environment, and the laser output is stable, there is no change in characteristics, and there is no deterioration in the life, and a good optical communication system has become possible. Since the metal package also functions as a heat radiating member, a system with a small number of components and high heat radiating efficiency could be constructed.

Similarly, when a GaAs, AlN or SiC substrate was used as the mounting substrate instead of the Si substrate, good results were obtained. In the case of an AlN or SiC substrate, an oxide film is not formed because the substrate is an insulating substrate. Otherwise, it has the same structure as above. Here, four semiconductor lasers and four optical fibers are used; In particular, in the case of a multi-laser array chip in which a plurality of laser elements are formed on one chip by taking advantage of the features of the surface-emitting type semiconductor laser of the present invention, a large number of laser elements can be easily formed. Although the problem of heat is important, stable laser output can be obtained without any problem by properly selecting the mounting substrate material and the heat radiation member as in the present invention. Further, the optical transmission line for optical coupling with the semiconductor laser is also a multimode fiber, but may be an optical waveguide, a single mode optical fiber, a plastic optical fiber, or the like.

[0050]

As described above, according to the first aspect of the present invention, by devising a semiconductor distributed Bragg reflector,
The operating voltage, oscillation threshold current, etc. can be reduced, with low power consumption.
Stable oscillation was achieved with little heat generation of the laser element, and a practical optical communication system at low cost was realized. Further, by setting the difference between the linear expansion coefficients of the laser chip and the substrate material on which the laser chip is mounted to be within 2 × 10 ⁻⁶ / K, a long-wavelength surface emission type having a GaInNAs active layer with a high strain is provided. Since the difference between the coefficient of linear expansion of the laser and the coefficient of linear expansion of the mounting board can be reduced, the occurrence of thermal stress is suppressed.As a result, the characteristic fluctuation of the semiconductor laser caused by the thermal stress can be reduced, and the life can be prevented from being shortened. Thus, a highly reliable optical communication system was realized. Further, in the second aspect, by devising a semiconductor distributed Bragg reflector,
The operating voltage, oscillation threshold current, etc. can be reduced, with low power consumption.
Stable oscillation was achieved with little heat generation of the laser element, and a practical optical communication system at low cost was realized. Further, a long-wavelength band surface emitting laser chip is made of Si, SiC, G
By mounting on a substrate made of either aAs or AlN, the difference between the linear expansion coefficient of the long wavelength band surface emitting laser having the GaInNAs active layer with high strain and the linear expansion coefficient of the mounting substrate is small, so that thermal stress is reduced. The generation is suppressed, and as a result, the fluctuation in the characteristics of the semiconductor laser caused by the thermal stress is reduced, the reduction in the life is prevented, and a highly reliable optical communication system can be realized. According to the third aspect of the present invention, a surface-emitting type semiconductor laser device chip provided with a non-radiative recombination preventing layer enables stable oscillation and realizes a practical optical communication system using this as a light emitting light source. . Further, by setting the difference between the linear expansion coefficients of the laser chip and the substrate material on which the laser chip is mounted to be within 2 × 10 ⁻⁶ / K, a long-wavelength surface emission type having a GaInNAs active layer with a high strain is provided. Since the difference between the coefficient of linear expansion of the laser and the coefficient of linear expansion of the mounting board can be reduced, the occurrence of thermal stress is suppressed.As a result, the characteristic fluctuation of the semiconductor laser caused by the thermal stress can be reduced, and the life can be prevented from being shortened. Thus, a highly reliable optical communication system was realized.

According to a fourth aspect of the present invention, a surface emitting type semiconductor laser device chip provided with a non-radiative recombination preventing layer enables stable oscillation, and a practical optical communication system using this as a light emitting light source. I realized it. Further, a long wavelength band surface emitting laser chip is used for Si, SiC, GaAs,
By mounting on a substrate made of any of AlN, the difference between the linear expansion coefficient of the long-wavelength band surface emitting laser having a GaInNAs active layer with high strain and the linear expansion coefficient of the mounting substrate is small, so that thermal stress is generated. As a result, the variation in characteristics of the semiconductor laser caused by thermal stress can be reduced, and the life of the semiconductor laser can be prevented from being reduced. Thus, a highly reliable optical communication system can be realized. According to claim 5, the mounting board on which the laser chip is mounted is fixed to a heat radiating member, and the heat radiating member is made of a material having a higher thermal conductivity than the laser chip. I was able to escape better. As a result, the characteristic fluctuation of the laser output can be reduced, the life can be prevented from being shortened, and a more reliable optical communication system can be realized. In a sixth aspect, the heat radiation member to which the mounting substrate is fixed is AlN,
By being made of any of Cu / W, W, and Mo,
High thermal conductivity enables efficient heat dissipation from semiconductor lasers and laser drive circuits. Also, the difference between the coefficient of thermal expansion of the heat dissipating member and the coefficient of linear expansion of the mounting board is small, causing thermal stress. As a result, the long-wavelength surface emitting semiconductor laser is not distorted, so that the characteristic fluctuation of the semiconductor laser can be reduced, the life can be prevented from being shortened, and a highly reliable optical communication system can be realized. According to a seventh aspect of the present invention, the heat radiation member to which the mounting substrate is fixed is formed into a package of the optical transmission module, so that the number of components is small, the heat radiation characteristic is good, and the characteristic fluctuation of the long wavelength band surface emitting semiconductor laser is reduced. A reduction in the life can be prevented, and a highly reliable optical communication system can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view of an element part of a long-wavelength band surface emitting semiconductor laser according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a configuration of a semiconductor distributed Bragg reflector of a long wavelength band surface emitting semiconductor laser according to an embodiment of the present invention.

FIG. 3 is a diagram showing an example in which the composition gradient of the hetero-spike buffer layer of the semiconductor distributed Bragg reflector applied to the present invention is larger near the GaAs layer than the AlAs layer.

FIG. 4 is a diagram showing an example in which the Al composition of the hetero-spike buffer layer is changed linearly.

FIG. 5 is a diagram showing a result of estimating a differential sheet resistance of the hetero-spike buffer layer of FIG. 3;

FIG. 6 is a band diagram showing a thermal equilibrium state of a DBR heterointerface of a semiconductor distributed Bragg reflector made of AlAs / GaAs.

FIG. 7 is a band diagram of the hetero-spike buffer layer of FIG. 3 in a thermal equilibrium state.

FIG. 8: AlAs / GaAs (p = 1E18 cm ⁻³ )
It is a figure which shows the resistivity of 4 pairs.

FIG. 9 is a graph showing the rate of change of the reflectance of an AlAs / GaAs semiconductor distributed Bragg reflector.

FIG. 10 is a sectional view of an element portion of another configuration of a long-wavelength band surface emitting semiconductor laser according to an embodiment of the present invention.

FIG. 11 shows GaInNAs / according to an embodiment of the present invention.
FIG. 3 is a room-temperature photoluminescence spectrum diagram of an active layer having a GaAs double quantum well structure.

FIG. 12 is a structural diagram of a sample.

FIG. 13 is a diagram showing a depth direction distribution of nitrogen and oxygen concentrations.

FIG. 14 is a diagram showing the distribution of the Al concentration in the depth direction.

FIG. 15 is an explanatory structural view in the case where growth is interrupted by carrier gas purge.

FIG. 16 is a diagram showing the distribution of the Al concentration in the depth direction in a case where a growth interruption step is provided and purged with hydrogen.

FIG. 17 is a diagram showing a depth direction distribution of nitrogen and oxygen concentrations when a growth interruption step is provided and purged with hydrogen.

FIG. 18 is a plan view showing a wafer substrate and a laser element chip on which a long wavelength band surface emitting semiconductor laser element according to one embodiment of the present invention is formed.

FIG. 19 is a schematic diagram showing an optical transmission unit of a communication system using a long-wavelength surface emitting semiconductor laser device according to one embodiment of the present invention.

FIG. 20 is a schematic diagram showing an optical transmission unit of a communication system using a long-wavelength band surface emitting semiconductor laser device according to one embodiment of the present invention.

[Explanation of symbols]

1 n-side electrode, 2 n-GaAs substrate, 3 lower distributed Bragg reflector, 4 GaAs spacer layer, 5 upper distributed Bragg reflector, 6 p-contact layer,
12 TQW active layer, 13 GaAs barrier layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Teruyuki Furuta 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Kazuya Miyagaki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Ken Kanai 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Atsushi Watada 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Shunichi Sato 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Yukie Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Invention Person Satoru Sugawara 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Shinji Sato 1-3-6, Nakamagome, Ota-ku, Tokyo Stock Company Inside Ricoh (72) Inventor Shuichi Hikichi 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Naoto Shakuya 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. 72) Inventor Takashi Takahashi 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. 5F073 AA74 AB04 AB28 BA02 CA07 CA17 CB02 DA05 FA13 FA15 FA22 GA38

Claims (7)

[Claims] In a laser chip and an optical communication system connected to the laser chip, the laser chip has an oscillation wavelength of 1.1 μm to 1.7 μm, and a main element of an active layer for generating light is Ga, In. , N, As
Alternatively, a surface emitting semiconductor laser device chip having a resonator structure including a reflecting mirror provided on an upper portion and a lower portion of the active layer to obtain a laser beam as a layer made of Ga, In, and As, The reflecting mirror has a reflection wavelength of 1.1 μm
The semiconductor distributed Bragg reflector in which the refractive index of the material layer constituting the reflecting mirror periodically changes to a value different from the above, reflects incident light by light wave interference, and the material layer having the small refractive index Is Al _x Ga _1-x As (0 <x ≦ 1)
And then, the material layer of the refractive index is large is _Al y _{Ga 1-} y As
(0 ≦ y <x ≦ 1), and Al _z Ga having a value between the small and large refractive index between the material layers having the small and large refractive index.
Light emitted from a surface-emitting type semiconductor laser device chip such as a reflector having a hetero-spike buffer layer of _1-z As (0 ≦ y <z <x ≦ 1) having a thickness of 20 nm to 50 nm. An optical communication system, wherein a difference between linear expansion coefficients of the laser chip and a substrate material on which the laser chip is mounted is within 2 × 10 ⁻⁶ / K. 2. In a laser chip and an optical communication system connected to the laser chip, the laser chip has an oscillation wavelength of 1.1 μm to 1.7 μm, and an active layer that generates light is mainly Ga or In. , N, As
Alternatively, a surface emitting semiconductor laser device chip having a resonator structure including a reflecting mirror provided on an upper portion and a lower portion of the active layer to obtain a laser beam as a layer made of Ga, In, and As, The reflecting mirror has a reflection wavelength of 1.1 μm
The semiconductor distributed Bragg reflector in which the refractive index of the material layer constituting the reflecting mirror periodically changes to a value different from the above, reflects incident light by light wave interference, and the material layer having the small refractive index Is Al _x Ga _1-x As (0 <x ≦ 1)
And then, the material layer of the refractive index is large is _Al y _{Ga 1-} y As
(0 ≦ y <x ≦ 1), and Al _z Ga having a value between the small and large refractive index between the material layers having the small and large refractive index.
Light emitted from a surface-emitting type semiconductor laser device chip such as a reflector having a hetero-spike buffer layer of _1-z As (0 ≦ y <z <x ≦ 1) having a thickness of 20 nm to 50 nm. An optical communication system, wherein a substrate on which the laser chip is mounted is made of one of Si, SiC, GaAs, and AlN. 3. In a laser chip and an optical communication system connected to the laser chip, the laser chip has an oscillation wavelength of 1.1 μm to 1.7 μm, and a main element of an active layer for generating light is Ga, In. , N, As
Alternatively, a surface emitting semiconductor laser device chip having a resonator structure including a reflecting mirror provided on an upper portion and a lower portion of the active layer to obtain a laser beam as a layer made of Ga, In, and As, The reflecting mirror has a reflection wavelength of 1.1 μm
The semiconductor distributed Bragg reflector in which the refractive index of the material layer constituting the reflecting mirror periodically changes to a value different from the above, reflects incident light by light wave interference, and the material layer having the small refractive index Is Al _x Ga _1-x As (0 <x ≦ 1)
And then, the material layer of the refractive index is large is _Al y _{Ga 1-} y As
(0 ≦ y <x ≦ 1 ) is the the reflecting mirror, main composition between said reflector and said active layer is _{Ga x In 1-x P y} A
An optical communication system in which a surface-emitting type semiconductor laser device chip provided with a non-radiative recombination prevention layer composed of s _1-y (0 <x ≦ 1, 0 <y ≦ 1) layers is used as a light emitting source, An optical communication system, wherein a difference between linear expansion coefficients of a laser chip and a substrate material on which the laser chip is mounted is within 2 × 10 ⁻⁶ / K. 4. In a laser chip and an optical communication system connected to the laser chip, the laser chip has an oscillation wavelength of 1.1 μm to 1.7 μm, and a main element of an active layer for generating light is Ga, In. , N, As
Alternatively, a surface emitting semiconductor laser device chip having a resonator structure including a reflecting mirror provided on an upper portion and a lower portion of the active layer to obtain a laser beam as a layer made of Ga, In, and As, The reflecting mirror has a reflection wavelength of 1.1 μm
The semiconductor distributed Bragg reflector in which the refractive index of the material layer constituting the reflecting mirror periodically changes to a value different from the above, reflects incident light by light wave interference, and the material layer having the small refractive index Is Al _x Ga _1-x As (0 <x ≦ 1)
And then, the material layer of the refractive index is large is _Al y _{Ga 1-} y As
(0 ≦ y <x ≦ 1 ) is the the reflecting mirror, main composition between said reflector and said active layer is _{Ga x In 1-x P y} A
An optical communication system in which a surface-emitting type semiconductor laser device chip provided with a non-radiative recombination prevention layer composed of s _1-y (0 <x ≦ 1, 0 <y ≦ 1) layers is used as a light emitting source, The substrate on which the laser chip is mounted is Si, SiC, GaAs,
An optical communication system comprising any one of AlN. 5. The mounting board according to claim 1, wherein the mounting board on which the laser chip is mounted is fixed to a heat radiating member, and the heat radiating member is made of a material having a higher thermal conductivity than the laser chip. The optical communication system according to claim 1. 6. A mounting board on which the laser chip is mounted is fixed to a heat radiating member, and the heat radiating member is made of Al.
The optical communication system according to any one of claims 1 to 5, comprising one of N, Cu / W, W, Mo, and Cu. 7. The heat radiating member also serves as a package of an optical transmission module.
The optical communication system according to claim 1.