JP3091655B2 - Semiconductor laser device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device.

[0002]

2. Description of the Related Art Recently, an oscillation wavelength is 630 nm to 680 n.
AlGaInP-based semiconductor laser devices have been actively researched and developed as semiconductor laser devices near the m band.

Since the 630 nm band has high visibility, elements in such an oscillation band are used for laser pointers, line markers, and the like. When used in such products, such devices are generally used on a battery, and low power consumption is desired.

There is also a demand for a semiconductor laser device that oscillates at a wavelength in the visible light region as a light source for an information processing device or a laser printer device for recording, reproducing, or erasing an optical recording medium such as an optical disk. Is growing. In these information processing devices and laser printer devices, it is required to increase the information density, that is, to shorten the wavelength of the semiconductor laser device, and AlGaInP-based semiconductor laser devices have been receiving attention. Even in such applications, a reduction in the oscillation threshold current (I _th ) related to the reduction in power consumption of the semiconductor laser device is required in order to reduce the power consumption of the device.

Incidentally, a tensile-strained AlGaInP-based semiconductor laser device having an active layer in which a quantum well layer having a tensile strain of 630 nm and an unstrained quantum barrier layer are alternately stacked, a quantum well layer having a tensile strain, In a strain-compensated AlGaInP-based semiconductor laser device including an active layer in which quantum barrier layers having compressive strain are alternately stacked, the oscillation threshold current is higher than that of a general device in which the quantum well layer has compressive strain or no strain. It is known to be smaller.

[0006] However, the above-mentioned general device oscillates in the TE mode, whereas the device in which the quantum well layer has tensile strain oscillates in the TM mode. In some cases, it cannot be used in the optical system of the apparatus. Therefore, it is still desired to reduce the oscillation threshold current of a compression-strained AlGaInP-based semiconductor laser device having a compression strain in the quantum well layer.

Needless to say, further reduction in the oscillation threshold current is desired for a semiconductor laser device that oscillates in the TM mode suitable for other uses.

[0008]

The above-mentioned AlGaInP-based semiconductor laser device has a structure in which the cavity length is shortened.
It is also known that the oscillation threshold current can be reduced.
However, the reliability cannot be sufficiently ensured only by shortening the resonator length in this manner. For example, the maximum oscillation temperature (T _max : the maximum oscillation temperature at which oscillation is possible, which is closely related to the reliability,
The required value varies depending on the application).

As a result, even lower power consumption AlGaI
There is a problem that an nP-based semiconductor laser device cannot be put to practical use. For example, if T _max is 50 ° C. or more and I _th is 50
mA following the oscillation wavelength compressive strain type semiconductor laser element of 630nm band, T _max is compressive strain type semiconductor laser device 70 ° C. or more and I _th is the following oscillation wavelength 30 mA 670 nm band, T _max is and 60 ° C. or higher I A strain-compensated semiconductor laser device having a _th of 30 mA or less and an oscillation wavelength of 630 nm has not been put to practical use.

The present invention has been made in view of the above-mentioned problems, and has as its object to provide a semiconductor laser device having high reliability and low power consumption.

[0011]

According to the present invention, there is provided a semiconductor laser device comprising: a first conductivity type GaAs semiconductor substrate; a first conductivity type cladding layer formed on one main surface of the substrate;
An active layer having a quantum well structure formed on a conductive type cladding layer and having a quantum well layer and a quantum barrier layer alternately stacked thereon, and a conductive type opposite to the first conductive type formed on the active layer; AlG comprising a cladding layer of the second conductivity type is a type, the
In the aInP-based semiconductor laser device, the quantum well layer has a compressive strain, and the one main surface of the substrate is # 1.
A plane inclined from 9 degrees to 17 degrees in the <011> direction from the 00 ° plane, and having a cavity length of 150 μm to 300
μm or less.

Further, another semiconductor laser device according to the present invention comprises:
A GaAs semiconductor substrate of a first conductivity type, a cladding layer of the first conductivity type formed on one main surface of the substrate, and a quantum well formed on the cladding layer of the first conductivity type and having opposite strains to each other An active layer having a quantum well structure in which layers and quantum barrier layers are alternately stacked; and a second conductive type clad layer formed on the active layer and having a conductivity type opposite to the first conductivity type. AlGaInP-based semiconductor laser devices with
And one principal surface of the substrate is shifted from the {100} plane to <011>
The surface is inclined from 9 degrees to 17 degrees in the direction, and the cavity length is from 150 μm to 300 μm.

In particular, the one main surface of the substrate is $ 10
It is a surface inclined from 11 ° to 17 ° in the <011> direction from the 0 ° plane.

Further, the one main surface of the substrate is $ 10
The surface is characterized by being inclined at approximately 13 degrees in the <011> direction from the 0 ° plane.

Further, the first conductivity type cladding layer may be (A)
l _x1 Ga _1-x1 ) _0.5 In _0.5 P, the second conductivity type cladding layer is made of (Al _x2 Ga _1-x2 ) _0.5 In _0.5 P, and the quantum well layer is made of (Al _x3 Ga _1-x3). ) _Y3 In _1-y3 P
And the quantum barrier layer is composed of (Al _x4 Ga _1-4 ) _y4 In
_1-y4 P and the composition ratios x1, x2, x3,
And x4 are 1 ≧ x1, x2>x4> x3 ≧ 0, and 1>
It is characterized by satisfying the relationship of y3, y4> 0. Ma
Further, the resonator length is not less than 200 μm and not more than 300 μm.
It is characterized by that.

[0016]

According to the structure of the present invention, the quantum well layer of the active layer has a compressive strain, and in addition, one main surface of the GaAs semiconductor substrate has
A plane inclined from 9 degrees to 17 degrees in the <011> direction from the 00 ° plane, and having a cavity length of 150 μm to 300
Since it is not more than μm, the maximum oscillation temperature can be increased and the oscillation threshold current can be decreased.

In another embodiment of the present invention, the quantum well layer and the quantum barrier layer of the active layer have opposite strains to each other,
One main surface of the As semiconductor substrate is changed from the {100} plane to <011>
Since the surface is inclined from 9 degrees to 17 degrees in the direction and the cavity length is from 150 μm to 300 μm, the maximum oscillation temperature can be higher and the oscillation threshold current can be smaller.

In particular, the one main surface of the semiconductor substrate is
When the plane is inclined from 11 ° to 17 ° in the <011> direction from the {100} plane, the maximum oscillation temperature can be further increased and the oscillation threshold current can be further reduced.

Further, the one main surface of the semiconductor substrate is:
When the plane is inclined at approximately 13 degrees in the <011> direction from the {100} plane, the maximum oscillation temperature can be extremely high and the oscillation threshold current can be extremely small.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The oscillation wavelength according to the first embodiment of the present invention is 630.
A compression-strain type AlGaInP-based semiconductor laser device in the nm band will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional structure diagram of the semiconductor laser device, and FIG. 2 is a schematic band structure diagram near an active layer of the semiconductor laser device.

In the figure, reference numeral 1 denotes an n-type GaAs semiconductor substrate whose one main surface has an angle θ from the (100) plane in the [011] direction.
(Θ = 9 to 17 degrees: hereinafter, angle θ is referred to as off-angle θ). An n-type Ga _0.5 In _0.5 P buffer layer 2 having a thickness of 0.3 μm and a thickness of 0.8 to
0.9 μm n-type (Al _xa Ga _1-xa ) _0.5 In _0.5 P (x
a> ya, yb> p ≧ 0: xa = 0.7 in this embodiment)
The cladding layer 3 is formed in this order.

On the n-type cladding layer 3, a layer thickness of 200
Undoped (Al _ya Ga _1-ya ) _0.5 In of ~ 500 °
_0.5 P (ya ≧ r: ya = 0.5 in this embodiment) The light guide layer 4 has a compressive strain of 50 ° (Al _p G).
a _1-p ) _q In _1-q P (q <0.51: p = p in this embodiment)
0.1, q = 0.44) Compressive strain quantum well layers 5a, 5a,
5a, 5a (typically all 10 layers or less, in this embodiment all four layers) with a layer thickness _{40Å (Al r Ga 1-r} ) 0.5 In 0.5 P
(Xa, xb, xc>r> p: In this embodiment, r = 0.
5) Compression strain multiple quantum well structure (compression strain MQW structure) in which quantum barrier layers 5b, 5b, 5b (typically all 9 layers or less, all 3 layers in this embodiment) are alternately stacked. Undoped active layer 5 and undoped (Al _yb Ga _1-yb ) _0.5 In _0.5 P (yb ≧ r) having a thickness of 200 to 500 °:
(In this embodiment, yb = 0.5) The light guide layer 6 is formed in this order. The compression-strain quantum well layer 5 of this embodiment
The amount of distortion Δa / a ₀ (a = a lattice constant of the quantum well layer−a lattice constant a ₀ of the GaAs semiconductor substrate) of a, 5a,.
0.5%, and the quantum barrier layers 5b, 5b, 5b are substantially strain-free.

The light guide layer 6 has a thickness of 300 °
p-type (Al_xbGa_1-xb)_0.5In_0.5P (xb> ya, y
b> p ≧ 0: xb = 0.7 in this embodiment) Cladding layer 7
Are formed. On the p-type cladding layer 7, a layer thickness
8Å p-type (Al_tGa_1-t) _uIn_1-uP (t <v: real
(In the example, t = 0, u = 0.5) The quantum well layers 8a, 8a,
... (10 layers in total) and p-type (Al_vG
a_1-v)_wIn_1-wP (desirably v = xb = xc: real
In the embodiment, v = 0.7, w = 0.5) quantum barrier layers 8b, 8
b,... (all 9 layers) are alternately stacked and have a large weight
A child barrier structure (MQB) layer 8 is formed. This MQ
The B layer prevents electrons from overflowing from the active layer due to interference.
Is to prevent

On the multi-quantum barrier structure layer 8, a laser resonator having a thickness of 0.9 μm and a lower surface width of 5 μm ([0
1-1] direction, and a stripe-shaped ridge portion extending in both directions, and a layer thickness of 0.2 to 0.3 μm on both sides of the ridge portion.
(Al _xc Ga _{1 -xc} ) _0.5 In _0.5 P having a flat portion of
(Xc> ya, yb> p ≧ 0: In this embodiment, xc = 0.
7) The cladding layer 9 is formed. In this embodiment, a p-type Ga _0.5 In _0.5 P etching stop layer 9 a having a different thickness from the cladding layer 9 and an etching rate different from that of the cladding layer 9, for example, a layer thickness of 20 ° is formed on the flat portion. Have.

A layer thickness of 1 μm is formed so as to cover both sides of the ridge portion of the p-type cladding layer 9 on the etching stop layer 9a.
N-type GaAs current blocking layers 10 and 10 are formed, and a 0.1 μm-thick p-type Ga _0.5
A contact layer 11 made of In _0.5 P is formed.

On the current blocking layers 10, 10 and the contact layer 11, the thickness of the contact layer 11 is 2 to 5
A p-type GaAs cap layer 12 of μm is formed.

On the upper surface of the cap layer 12, a p-type ohmic electrode 13 made of Au--Cr is provided.
On the lower surface of the semiconductor substrate 1, an n-type ohmic electrode 14 made of Au-Sn-Cr is formed.

In this semiconductor laser device, as can be seen from FIG. 2, the active layer 5 is sandwiched between the light guide layers 4, 6 having the same band gap as the quantum barrier layers 5b, 5b, 5b. The structure is sandwiched between the cladding layers 3 and 7 having a larger band gap than the layers 4 and 6.
Since the refractive index decreases as the band gap increases, the description of the refractive index is omitted.

Next, a method of manufacturing such a semiconductor laser device will be briefly described.

First, layers up to the contact layer 11 are continuously grown on the GaAs semiconductor substrate 1 by MOCVD (metal organic chemical vapor deposition). Next, a mask made of stripe-shaped SiO ₂ or the like is formed on the contact layer 11, and the contact layer 11 and the clad layer 9 are selectively etched to the etching stop layer 9a with the mask interposed therebetween. Subsequently, the current blocking layers 10 and 10 are
After being formed by the CVD method, and then removing the mask to expose the contact layer 11, the current blocking layers 10, 1
0 and the cap layer 12 on the contact layer 11
Formed by Method D. Next, a p-type ohmic electrode 13 is formed on the upper surface of the cap layer 12, and an n-type ohmic electrode 14 is formed on the lower surface of the n-type GaAs semiconductor substrate 1 by vapor deposition and heat treatment.

FIG. 3 shows a case where the principal surface of the semiconductor laser device is inclined at 9 °, 13 °, and 17 ° in the [011] direction from the (100) plane. The relationship between the maximum oscillation temperature T _max (° C.) and the cavity length L (μm) is shown for the case where the surface is inclined at 5 degrees, and the off angle θ = 5 degrees is a white triangle and the off angle θ in FIG. = 9
The degree is a white square, the off angle θ = 13 degrees is a white circle,
The off angle θ = 17 degrees is represented by a black circle. In this measurement, the element was tin-bonded with a junction down on a Si heat sink (thickness: 50 to 500 μm) which was adhesively mounted (fixed) on a good radiator (copper block) of a normal stem with solder or the like. The operation was performed in a continuous oscillation state in a state of being mounted (fixed) by pressure bonding through the substrate. The measured element was coated with a reflective film having a reflectance of 30% and 50%, respectively, on the end face before light emission and the end face after light emission.

From FIG. 3, the semiconductor laser device is
When the off angle θ is 9 degrees or more and 17 degrees or less, unlike the conventional phenomenon in which the maximum oscillation temperature gradually decreases as the length of the resonator decreases, the peak has a peak near the resonator length of 200 μm. , The maximum oscillation temperature is greater than 50 ° C. at 150 μm or more and 300 μm or less, and 200 μm or more and 300 μm
It can be seen that the maximum oscillation temperature becomes 60 ° C. or more when the temperature is less than m.

FIG. 4 shows the maximum oscillation temperature T _max (° C.) obtained by performing the same measurement as in FIG. 3, and the off angle θ (degree) of the semiconductor substrate.
Shows the relationship. Note that the resonator length L is 200 μm as an example.
It is.

From FIG. 4, the semiconductor laser device is
The maximum oscillation temperature is 60 when the off angle θ is 9 degrees or more and 17 degrees or less.
° C or more, and particularly when the off-angle θ is 11 ° or more and 17 ° or less, which is better than 60 ° C, it is understood that about 13 ° is more preferable. When the resonator length is 150 μm or more and 300 μm or less, the off angle θ and the maximum oscillation temperature _Tmax have the same tendency.

FIG. 5 shows the maximum oscillation temperature T _max (° C.) and the oscillation threshold current I _th (m) obtained by performing the same measurement as in FIG.
A) and the relationship between the resonator length L (μm) are shown. In the figure, white circles indicate the maximum oscillation temperature, and black circles indicate the threshold current. The off angle is 13 degrees as an example.

It can be seen from FIG. 5 that the threshold current of such a semiconductor laser device gradually decreases as the cavity length becomes shorter, similarly to the conventional device. In particular, when the resonator length is 300 μm or less, the threshold current becomes smaller than 50 mA, and when the resonator length is 200 μm or less, the threshold current becomes 40 m.
It turns out that it is about A or less. Then, reliability of 2000 hours or more was confirmed under the conditions of 50 ° C. and an optical output of 5 mW (continuous oscillation).

Although not shown, the resonator length is 150 μm.
m to 300 μm, and the off angle θ is 9 degrees to 17
If it is lower than the threshold, the threshold current is lower than about 50 mA, and long-term reliability can be obtained.

3 to 5 that the semiconductor laser device has a cavity length of 150 to 300 μm, preferably 200 to 300 μm, and an off angle θ of 9 to 17 degrees, preferably It is understood that the angle is preferably 11 degrees or more and 17 degrees or less, and more preferably about 13 degrees.

The oscillation wavelength according to the second embodiment of the present invention is 67
A 0 nm band compression-strain type AlGaInP-based semiconductor laser device will be described with reference to the drawings. FIG. 6 is a schematic cross-sectional structure diagram of the semiconductor laser device, and FIG. 7 is a schematic band structure diagram near the active layer of the semiconductor laser device.

This embodiment is different from the first embodiment in that there is no MQB layer in the active layer and its vicinity and in the cladding layer, and the same parts as those in the first embodiment or corresponding parts are denoted by the same reference numerals. The description will be simplified.

[0041] On the n-type cladding layer 3, the layer thickness 200Å undoped _{(Al ya Ga 1-ya)} 0. 5 In 0.5 P (ya ≧
r: ya = 0.5 in this embodiment) light guide layer 4, layer thickness 8
(Al _p Ga _1-p ) _q In _1-q P having 0 ° compression strain
(Q <0.51: p = 0 and q = 0.44 in this embodiment)
Compressive strain quantum well layer 5a, 5a, 5a, 5a (typically all 10 layers or less, in this embodiment all four layers) with a layer thickness _{40Å (Al r Ga 1-r} ) 0.5 In 0 .5 P ( xa, xb, xc> r
> P: r = 0.5 in this embodiment) quantum barrier layers 5b, 5
b, 5b (typically all 9 layers or less, in this example all 3 layers)
Undoped active layer 5 having a compression-strained multiple quantum well structure (compression-strained MQW structure) in which
And undoped (Al _yb Ga _1-yb ) with a layer thickness of 200 _°
0.5 In _0.5 P (yb ≧ r: yb = 0.5 in this embodiment)
The light guide layer 6 is formed in this order. Note that the strain amount Δa / a of the compression-strained quantum well layers 5a, 5a,.
₀ is + 0.5%, and the quantum barrier layers 5b, 5b, 5b are substantially strain-free.

As can be seen from FIG. 7, in this semiconductor laser device, the active layer 5 is sandwiched between the light guide layers 4, 6 having the same band gap as the quantum barrier layers 5b, 5b,. The structure is sandwiched between cladding layers 3 and 9 having a larger band gap than guide layers 4 and 6.

FIG. 8 shows that the principal surface of the semiconductor laser device is 9 degrees, 13 degrees in the [011] direction from the (100) plane.
The relationship between the maximum oscillation temperature T _max (° C.) and the cavity length L (μm) is shown for a case where the surface is inclined at 17 degrees and a case where the surface is inclined at 5 degrees in the same direction as a comparative example. In the figure, the off angle θ = 5 degrees is a white triangle, and the off angle θ = 9.
The degree is a white square, the off angle θ = 13 degrees is a white circle,
The off angle θ = 17 degrees is represented by a black circle. In this measurement, the element was tin-bonded with a junction down on a Si heat sink (thickness: 50 to 500 μm) which was adhesively mounted (fixed) on a good radiator (copper block) of a normal stem with solder or the like. The operation was performed in a continuous oscillation state in a state of being mounted (fixed) by pressure bonding through the substrate. The measured element was coated with a reflective film having a reflectance of 30% and 30%, respectively, on the end face before light emission and the end face after light emission.

As shown in FIG. 8, the semiconductor laser device is
When the off angle θ is 9 degrees or more and 17 degrees or less, unlike the conventional phenomenon in which the maximum oscillation temperature gradually decreases as the length of the resonator decreases, the peak has a peak near the resonator length of 250 μm, , The maximum oscillation temperature is greater than 70 ° C. at 150 μm or more and 300 μm or less, and 200 μm or more and 300 μm
It can be seen that the maximum oscillation temperature is higher than 80 ° C. when the temperature is less than m.

FIG. 9 shows the maximum oscillation temperature T _max (° C.) obtained by performing the same measurement as in FIG. 8 and the off angle θ (degree) of the semiconductor substrate.
Shows the relationship. Note that the resonator length L is 200 μm as an example.
It is.

From FIG. 9, the semiconductor laser device is
The maximum oscillation temperature is 80 when the off angle θ is 9 degrees or more and 17 degrees or less.
It can be seen that the temperature is higher than 100 ° C., particularly 100 ° C. or higher when the off angle θ is 11 ° or more and 17 ° or less, and that the angle is more preferably about 13 °. If the resonator is 150 μm or more and 300 μm or less, the off angle θ and the maximum oscillation temperature _Tmax have the same tendency.

FIG. 10 shows the maximum oscillation temperature T _max (° C.) and the oscillation threshold current I obtained by performing the same measurements as in FIG.
The relationship between _th (mA) and the cavity length L (μm) is shown. In the figure, white circles indicate the maximum oscillation temperature, and black circles indicate the threshold current. The off angle is 13 degrees as an example.

It can be seen from FIG. 10 that the threshold current of such a semiconductor laser device gradually decreases as the cavity length becomes shorter, similarly to the conventional device. In particular, when the resonator length is 300 μm or less, the threshold current becomes 30 mA or less, and when the resonator length is 200 μm or less, the threshold current becomes 25 m
It turns out that it is about A or less. Then, reliability of 2000 hours or more was confirmed under the conditions of 50 ° C. and an optical output of 5 mW (continuous oscillation).

Although not shown, the resonator length is 150 μm.
m to 300 μm, and the off angle θ is 9 degrees to 17
If the temperature is not more than the threshold, the threshold current is not more than about 30 mA, and long-term reliability can be obtained.

8 to 10 that the semiconductor laser device has a cavity length of 150 μm or more and 300 μm or less,
It is found that the thickness is desirably 200 μm or more and 300 μm or less, and the off angle θ is 9 degrees or more and 17 degrees or less, preferably 11 degrees or more and 17 degrees or less, and more preferably about 13 degrees.

In the first and second embodiments, the amount of strain of the quantum well layer of the active layer is set to + 0.5%. However, an effect can be obtained even with a quantum well layer having a different compressive strain from the amount of strain. The quantum well layer is not limited to the above, and is appropriately selected from 10 layers or less and 1 or more layers.

The oscillation wavelength according to the third embodiment of the present invention is 63
A 0 nm band strain-compensating AlGaInP-based semiconductor laser device will be described with reference to the drawings. FIG. 11 is a schematic band structure diagram near the active layer of the semiconductor laser device. The present embodiment is different from the first embodiment only in the active layer. Therefore, the same portions as those in the first embodiment or corresponding portions are denoted by the same reference numerals and the description is simplified.

On the n-type cladding layer 3, a layer thickness of 200 to 5
Undoped (Al_yaGa _1-ya)_0.5In_0.5P
(Ya ≧ r: ya = 0.5 in this embodiment) Light guide layer
4. It has a tensile strain of 100 ° in thickness (Al_pG
a_1-p)_qIn_1-qP (q> 0.51: p =
0, q = 0.65) Tensile strain quantum well layers 5a, 5a, 5
a (typically all 10 layers or less, in this example all 3 layers)
(Al) with a layer thickness of 40 ° having compressive strain_rGa_1-r)_sIn
_1-sP (s <0.51, s = 0.44 in this embodiment, r
= 0.5) Compressive strain quantum barrier layers 5b, 5b (typically
9 layers or less, and in this embodiment, all 2 layers) are alternately laminated.
Strain-compensated multiple quantum well structure (strain-compensated MQW structure)
Undoped active layer 5 consisting of
500 ° undoped (Al_ybGa_1-yb)_0.5In_0.5
P (yb ≧ r: yb = 0.5 in this embodiment) Light guide layer
6 are formed in this order. In addition, the tension of this embodiment
Strain amount Δa / a of strained quantum well layers 5a, 5a, 5a₀Is -1
%, And the strain amount Δa / of the compressively-strained quantum barrier layers 5b and 5b.
a₀Is + 0.5%.

FIG. 12 shows that the principal surface of the semiconductor laser device is 9 degrees from the (100) plane in the [011] direction, and is 13 degrees.
The relationship between the maximum oscillation temperature T _max (° C.) and the cavity length L (μm) is shown for a case where the surface is inclined at 17 degrees and 17 degrees and a case where the surface is inclined at 5 degrees in the same direction as a comparative example. . In the figure, the off angle θ = 5 degrees is a white triangle, the off angle θ = 9 degrees is a white square, the off angle θ = 13 degrees is a white circle, and the off angle θ = 17 degrees is a black circle. Indicated by In this measurement, the element was tin-bonded with a junction down on a Si heat sink (thickness: 50 to 500 μm) which was adhesively mounted (fixed) on a good radiator (copper block) of a normal stem with solder or the like. The operation was performed in a continuous oscillation state in a state of being mounted (fixed) by pressure bonding through the substrate. In addition, the measured elements have 30% and 50%, respectively, on the end face before light emission and the end face after light emission.
% Was applied.

FIG. 12 shows that the semiconductor laser device has a conventional phenomenon that the maximum oscillation temperature gradually decreases as the resonator length becomes shorter when the off angle θ is 9 degrees or more and 17 degrees or less. Are different from each other in that the peak has a peak in the vicinity of 250 μm, the maximum oscillation temperature is in the range of about 60 ° C. or more, and
It can be seen that the maximum oscillation temperature becomes about 70 ° C. or more when the thickness is less than 00 μm.

FIG. 13 shows the maximum oscillation temperature T _max (° C.) obtained by performing the same measurement as in FIG. 12 and the off angle θ of the semiconductor substrate.
(Degree). The resonator length L is 20 as an example.
0 μm.

As shown in FIG. 13, the semiconductor laser device has a maximum oscillation temperature of more than 60 ° C. when the off angle θ is 9 degrees or more and 17 degrees or less, and particularly, the off angle θ is 11 degrees or more and 17 degrees or less.
It can be seen that the temperature is better than 70 ° C. below the temperature, and that approximately 13 ° is better. Note that the resonator is 150 μm or more and 300 μm.
If it is below, the off angle θ and the maximum oscillation temperature _Tmax have the same tendency.

FIG. 14 shows the maximum oscillation temperature T _max (° C.) and the oscillation threshold current (m) obtained by performing the same measurement as in FIG.
A) and the relationship between the resonator length L (μm) are shown. In the figure, white circles indicate the maximum oscillation temperature, and black circles indicate the threshold current. The off angle is 13 degrees as an example.

It can be seen from FIG. 14 that the threshold current of such a semiconductor laser device gradually decreases as the cavity length becomes shorter, similarly to the conventional device. In particular, when the resonator length is 300 μm or less, the threshold current becomes 30 mA or less, and when the resonator length is 200 μm or less, the threshold current becomes 25 m
It turns out that it is about A or less. Then, reliability of 2000 hours or more was confirmed under the conditions of 50 ° C. and an optical output of 5 mW (continuous oscillation).

Although not shown, the resonator length is 150 μm.
m to 300 μm, and the off angle θ is 9 degrees to 17
If the temperature is not more than the threshold, the threshold current is not more than about 30 mA, and long-term reliability can be obtained.

From FIG. 12 to FIG. 14, the semiconductor laser device has a cavity length of 150 μm or more and 300 μm or less, preferably 200 μm or more and 300 μm or less.
And the off angle θ is 9 degrees or more and 17 degrees or less, and preferably 11 degrees or less.
It is understood that the temperature is preferably from 17 degrees to 17 degrees, and more preferably about 13 degrees.

In the above description, the strain amounts of the quantum well layer and the quantum barrier layer of the active layer are set to -1% and 0.5%, respectively. However, an effect can be obtained even if the strain amounts are different from each other. It is appropriately selected. Also, the number of each of the quantum well layer and the quantum barrier layer is appropriately selected. The effect is also obtained when the strain of the quantum well layer and the strain of the quantum barrier layer are opposite to those described above.

Furthermore, in the above-described embodiment, one main surface of the GaAs semiconductor substrate 1 is a surface inclined in the [011] direction from the (100) plane, but it is preferable that these surfaces have an equivalent relationship. That is, one main surface (crystal growth surface) of the GaAs semiconductor substrate is a surface inclined in the [0-1-1] direction from the (100) surface, and is [101] or [−10-1] from the (010) surface.
The plane may be a plane inclined in the direction, or a plane inclined in the [110] or [-1-10] direction from the (001) plane, that is, {10}
Any surface may be used as long as it is inclined from the 0 ° plane in the <011> direction.

Further, according to the device of the present invention, the second conductivity type clad layer formed on the active layer having the quantum well structure has the stripe-shaped ridge portion as described above. A ridge type in which a current blocking layer of the first conductivity type is provided on the layer so as to cover both sides of the ridge portion is preferable, and the stripe-shaped ridge portion preferably extends in the <01-1> direction. Incidentally, the MQB layer and the etching stop layer may be appropriately provided in the second conductivity type cladding layer as described above,
Further, a saturable light absorbing layer may be provided.

In the above, (Al _z Ga _{1 -z} ) _0.5 In _0.5 P
(Z ≧ 0) indicates a material substantially lattice-matched with the GaAs semiconductor substrate, and is preferably (Al _z Ga _{1 -z} ) _0.51 In _0.49 P
It is.

[0066]

According to the structure of the present invention, the quantum well layer of the active layer has a compressive strain, and one main surface of the GaAs semiconductor substrate is at least 9 degrees and at most 17 degrees in the <011> direction from the {100} plane. And the resonator length is 150 μm or more and 300 μm or less, so that the maximum oscillation temperature can be increased and the oscillation threshold current can be decreased. Therefore, power consumption can be reduced and reliability can be increased.

In another configuration of the present invention, the quantum well layer and the quantum barrier layer of the active layer have opposite strains to each other, and
One main surface of the As semiconductor substrate is changed from the {100} plane to <011>
Since the surface is inclined from 9 degrees to 17 degrees in the direction and the cavity length is from 150 μm to 300 μm, the maximum oscillation temperature can be higher and the oscillation threshold current can be smaller. Therefore, power consumption can be reduced and reliability can be increased.

In particular, the one main surface of the semiconductor substrate is
In the case of a plane inclined from 11 degrees to 17 degrees from the {100} plane in the <011> direction, the maximum oscillation temperature can be further increased and the oscillation threshold current can be further reduced. As a result, power consumption can be further reduced and Higher reliability.

Further, the one main surface of the semiconductor substrate is
When the plane is inclined at approximately 13 degrees in the <011> direction from the {100} plane, the maximum oscillation temperature can be significantly increased and the oscillation threshold current can be significantly reduced, and as a result, the power consumption can be significantly reduced and the reliability can be reduced. Can be significantly higher.

[Brief description of the drawings]

FIG. 1 is a schematic sectional structural view of a semiconductor laser device according to a first embodiment of the present invention.

FIG. 2 is a schematic band structure diagram near an active layer of the semiconductor laser device of the embodiment.

FIG. 3 is a diagram showing the relationship between the maximum oscillation temperature, the cavity length, and the off angle of the GaAs semiconductor substrate of the semiconductor laser devices of the above-described example and the comparative example.

FIG. 4 is a diagram showing the relationship between the maximum oscillation temperature of the semiconductor laser device of the embodiment and the off angle of the GaAs semiconductor substrate.

FIG. 5 is a diagram showing the relationship between the oscillation threshold current, the maximum oscillation temperature, and the resonator length of the semiconductor laser device of the above embodiment.

FIG. 6 is a schematic sectional structural view of a semiconductor laser device according to a second embodiment of the present invention.

FIG. 7 is a schematic band structure diagram near an active layer of the semiconductor laser device of the above embodiment.

FIG. 8 is a diagram showing a relationship among the maximum oscillation temperature, the cavity length, and the off angle of the GaAs semiconductor substrate of the semiconductor laser devices of the above-described example and the comparative example.

FIG. 9 is a diagram showing the maximum oscillation temperature of the semiconductor laser device of the embodiment and the off angle of the GaAs semiconductor substrate.

FIG. 10 is a diagram showing the relationship between the oscillation threshold current, the maximum oscillation temperature, and the resonator length of the semiconductor laser device of the above embodiment.

FIG. 11 is a schematic band structure diagram near an active layer of a semiconductor laser device according to a third embodiment of the present invention.

FIG. 12 is a diagram showing the relationship between the maximum oscillation temperature, the resonator length, and the off angle of the GaAs semiconductor substrate of the semiconductor laser devices of the above example and the comparative example.

FIG. 13 is a diagram showing the relationship between the maximum oscillation temperature of the semiconductor laser device of the embodiment and the off angle of the GaAs semiconductor substrate.

FIG. 14 is a diagram showing the relationship between the oscillation threshold current, the maximum oscillation temperature, and the resonator length of the semiconductor laser device of the above embodiment.

[Explanation of symbols]

_{Reference Signs List} 1 n-type GaAs semiconductor substrate 3 n-type (Al _xa Ga _1-xa ) _0.5 In _0.5 P clad layer 5 a quantum well layer 5 b quantum barrier layer 5 active layer 9 p-type (Al _xb Ga _1-xb ) _0.5 In _0.5 P clad layer

Continuation of the front page (72) Inventor Yasuyuki Bessho 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Inside Sanyo Electric Co., Ltd. (72) Inventor ▲ Hiro ▼ Ryoharu Yama 2-5-2 Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd. (72) Inventor Hiroyuki Kase 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-6-77592 (JP, A) JP-A-63-288808 (JP, A) JP-A-60-91692 (JP, A) JP-A-1-166588 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01S5 / 00-5/50

Claims (6)

(57) [Claims] A first conductivity type GaAs semiconductor substrate; a first conductivity type cladding layer formed on one main surface of the substrate; and a quantum well layer formed on the first conductivity type cladding layer. And an active layer having a quantum well structure in which quantum barrier layers are alternately stacked, a second conductivity type clad layer formed on the active layer and having a conductivity type opposite to the first conductivity type, In the AlGaInP-based semiconductor laser device provided with , the quantum well layer has a compressive strain, and the one main surface of the substrate is at least 9 degrees in the <011> direction from the {100} plane.
The surface is inclined to less than 10 degrees, and the cavity length is 150 μm
A semiconductor laser device having a thickness of at least 300 μm. 2. A GaAs semiconductor substrate of a first conductivity type, a cladding layer of a first conductivity type formed on one main surface of the substrate, and a reverse cladding layer formed on the cladding layer of the first conductivity type. An active layer having a quantum well structure in which quantum well layers having strain and quantum barrier layers are alternately stacked, and a second conductive layer formed on the active layer and having a conductivity type opposite to the first conductivity type AlGaInP-based semiconductor having a mold-type cladding layer
In the laser device, one main surface of the substrate is a surface inclined from 9 ° to 17 ° in a <011> direction from a {100} plane, and a cavity length is from 150 μm to 300 μm. Semiconductor laser device. 3. The semiconductor laser according to claim 1, wherein the one main surface of the substrate is a surface inclined from 11 degrees to 17 degrees in a <011> direction from a {100} plane. element. 4. The semiconductor laser device according to claim 3, wherein the one main surface of the substrate is a surface inclined at about 13 degrees in a <011> direction from a {100} plane. 5. The method according to claim 1, wherein the first conductivity type cladding layer is (Al _{x 1}
Ga _1-x1 ) _0.5 In _0.5 P, and the second conductivity type cladding layer is made of (Al _x2 Ga _1-x2 ) _0.5 In _0.5 P;
The quantum well layer is made of _{(Al x3 Ga 1-x3)} y3 In 1-y3 P, the quantum barrier layer _{(Al x4 Ga 1-4) y4 In} 1-y4
P, and the composition ratios x1, x2, x3, and x4 are 1 ≧ x1, x2>x4> x3 ≧ 0, and 1> y
5. The semiconductor laser device according to claim 1, wherein a relationship of 3, y4> 0 is satisfied. 6. The resonator according to claim 1, wherein said resonator length is not less than 200 μm and not more than 300 μm.
m, or less than m.
Is a semiconductor laser device according to 5.