JP2914330B2 - Method for growing self-pulsating 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 method for growing a self-pulsation type semiconductor laser device.

[0002]

2. Description of the Related Art A self-oscillation type semiconductor laser diode (LD) has been studied to reduce return light noise of a semiconductor laser used as a light source for pickup of an optical disk device. A self-excited laser has already been realized by introducing a saturable absorption layer inside the cladding layer of the laser.

In order to obtain a stable self-sustained pulsation laser having a small threshold, the absorption wavelength of the saturable absorption layer should be substantially equal to the oscillation wavelength of the laser, the lifetime of carriers generated in the saturable absorption layer should be short, It is important that the absorption wavelength of the saturable absorption layer is stable.

In the prior art, the carrier lifetime is shortened by increasing the doping concentration of the saturable absorbing layer to 2 × 10 ¹⁸ cm ⁻³ or more to increase radiative recombination. For example, there is a report entitled "Design of a self-pulsation type red semiconductor laser using a saturable absorption layer" in 26p-ZA-5 on page 1058 of the proceedings of the Joint Lecture Meeting on Applied Physics in the Spring of 1995. It shows that the carrier life must be sufficiently short to maintain the self-sustained pulsation.

On the other hand, when the doping concentration of the saturable absorbing layer is increased, the diffusion of the dopant tends to occur. Especially A
In a semiconductor LD using an lGaInP-based material, Zn is used as a p dopant. When the doping concentration of Zn in the GaInP saturable absorption layer is increased, GaInP
Zn diffuses into the AlGaInP layer in and around the saturable absorption layer. In many cases, a GaInP layer or an AlGaInP layer has a spontaneously formed ordered structure of a group III atom arrangement as a natural superlattice, and the band gap energy of these materials is at most about 60 meV smaller than that of a disordered structure. Has become. Since the diffusion of Zn makes this ordered structure disorder, the energy band gap of the GaInP layer or AlGaInP layer increases, and the absorption wavelength of the saturable absorption layer changes. When the GaInP / AlGaInP quantum well structure is used for the saturable absorption layer, the change in the absorption wavelength due to the diffusion of Zn becomes larger. Since the transition energy of the saturable absorbing layer must be controlled on the order of 10 meV, disordering of the saturable absorbing layer is important for obtaining stable characteristics.

In order to stabilize the absorption wavelength of the saturable absorption layer, Japanese Patent Application Laid-Open No. Hei 7-263794 proposes a self-pulsation type semiconductor laser device using a disordered saturable absorption layer. I have. P proposed in the present invention
The means for disordering the GaInP saturable absorber layer is to set the Zn dopant concentration of the p-type GaInP saturable absorber layer to 3 × 1.
0 ¹⁸ to 1 × 10 ¹⁹ cm ⁻³ . FIG. 9 shows the photoluminescence (P) of GaInP in the prior art.
L) A graph showing the relationship between the peak wavelength (expressed in energy) and the dopant concentration is shown.

[0007]

However, the conventional self-sustained pulsation type semiconductor laser device has problems such as a high threshold value, a short operating life, and poor temperature characteristics. In the prior art, high-concentration p-doping is performed on the saturable absorption layer in order to shorten the carrier lifetime of the saturable absorption layer. This causes the controllability and stability of the absorption wavelength to be impaired.

Also in the above conventional invention, the doping concentration of the saturable absorbing layer is a very high value of 3 × 10 ¹⁸ cm ⁻³ or more, and the difference from the doping concentration of the p-cladding layer adjacent thereto is large. Zn diffuses. As a result, the doping concentration of the saturable absorption layer changes, and the quantum well structure composed of the saturable absorption layer and the p-cladding layer changes. In particular, when the saturable absorption layer has a multiple quantum well structure, the multiple quantum well structure itself may be disordered by Zn diffusion. It is reported that such a phenomenon occurs not only during growth but also during operation as an LD element. For example, the threshold value of the element increases or the self-sustained pulsation disappears. This is considered to be because the absorption wavelength of the saturable absorption layer changes. In addition, since the saturable absorption layer has a high doping concentration, the dopant diffuses into the active layer, which is the light emitting layer, and the crystal quality of the light emitting layer is deteriorated.

An object of the present invention is to solve the above-mentioned problems and to provide a self-sustained pulsation type semiconductor device having a long operating life, a small threshold value, and stable and excellent characteristics.
Another object of the present invention is to provide a self-sustained pulsation type semiconductor element which reduces laser return light noise when used as a light source for pickup of an optical disk device and makes it possible to realize a high-performance optical disk device at low cost.

[0010]

Means for Solving the Problems The present inventor has made various studies in order to achieve the above object, and as a result, completed the present invention.

A first invention has a saturable absorbing layer and an active layer.
In a method of growing a self-pulsation type semiconductor laser device,
Defect formation activates carrier life of saturable absorber layer
At least one such that it is less than the carrier lifetime of the layer.
The growth temperature of at least one semiconductor layer 1 having the minimum forbidden band width among the semiconductor layers constituting the saturable absorbing layer in one of the saturable absorbing layers, and the minimum forbidden band among the semiconductor layers constituting the active layer. At least one semiconductor layer 2 having a width
The growth temperature of the active layer is 30 ° C. or more, and
The growth temperature of the conductor layer 2 depends on the growth of the semiconductor layer 1 of the saturable absorption layer.
The present invention relates to a method for growing a self-pulsation type semiconductor laser device, wherein the temperature is set to a temperature closer to an optimum growth temperature than a long temperature .

The second invention relates to a semiconductor layer 1 and a semiconductor layer 2
The present invention relates to a method of growing a self-pulsation type semiconductor laser device according to a first aspect of the present invention, in which the surface reconstruction structures at the time of each growth are different from each other.

A third aspect of the present invention is to maintain a state in which only the group V source is supplied and the supply of the group III source is interrupted for at least one minute immediately before and immediately after the growth of the semiconductor layer 1. The present invention relates to a method for growing a self-pulsation type semiconductor laser device according to the first or second aspect of the invention, in which the temperature is changed. As a result, when the growth is interrupted,
Small amounts of impurities such as oxygen and carbon existing in the growth chamber are adsorbed and taken in, and impurity levels are formed at the interface. As a result, the carrier life is reduced.

The fourth invention relates to the method of growing a self-pulsation type semiconductor laser device according to the first, second or third invention, wherein the semiconductor laser device is grown by using a molecular beam epitaxial growth apparatus provided with a reflection high-speed electron beam diffraction apparatus.

The fifth invention relates to a method for growing a self-pulsation type semiconductor laser device according to the fourth invention, wherein a difference between a growth temperature of the semiconductor layer 1 and a growth temperature of the semiconductor layer 2 is 40 to 70 ° C.

The sixth invention has a saturable absorbing layer and an active layer.
In a method of growing a self-pulsation type semiconductor laser device,
With respect to the growth conditions including the supply flow rate of the group V source (or the ratio of the group V / group III source) and the growth temperature, the formation of defects may
The carrier life of the saturable absorbing layer is the carrier life of the active layer.
(1 × 1) of the high-speed electron beam diffraction image so as to be smaller
A growth condition region to form a surface reconstruction structure corresponding to the pattern, and the boundary line between the growth condition region to form a surface reconstruction structure corresponding to a different pattern than contact and (1 × 1) pattern in the region, The growth temperature is 20
A saturable absorption layer is grown under conditions in a growth condition region formed by a growth condition region sandwiched between lines having different growth conditions and forming a surface reconstruction structure corresponding to a pattern different from the (1 × 1) pattern. And the active layer is a saturable absorption layer
In the growth condition area with more suitable supply flow rate and growth temperature
The present invention relates to a method for growing a self-sustained pulsation type semiconductor laser device, characterized in that the semiconductor laser device is grown under the following conditions . Here, the growth of the saturable absorbing layer is performed by growing at least one semiconductor layer having a minimum forbidden band width among the semiconductor layers constituting the saturable absorbing layer in the at least one saturable absorbing layer under the condition. I just need.

The seventh invention relates to a method for growing a self-pulsation type semiconductor laser device according to the first, second or third invention, wherein the semiconductor laser device is grown by using a metal organic vapor phase epitaxial growth apparatus provided with a surface photon absorption device.

The eighth invention relates to a method for growing a self-pulsation type semiconductor laser device according to the seventh invention, wherein the difference between the growth temperature of the semiconductor layer 1 and the growth temperature of the semiconductor layer 2 is 100 ° C. or more. Preferably, the temperature difference is from 100 to 300 ° C.

In a ninth aspect of the present invention, the semiconductor layer 1 exists in a temperature region lower than the growth temperature of the active layer with respect to the growth conditions including the group V / III raw material ratio and the growth temperature using the metal organic vapor phase epitaxial growth apparatus. The present invention relates to a method for growing a self-pulsation type semiconductor laser device according to the first, second or third invention for growing a saturable absorption layer in a disordered growth condition region.

According to a tenth aspect of the present invention, the semiconductor layer 1 exists in a temperature region higher than the growth temperature of the active layer with respect to the growth conditions consisting of the group V / III source ratio and the growth temperature using the metal organic vapor phase epitaxial growth apparatus. The present invention relates to a method for growing a self-pulsation type semiconductor laser device according to the first, second or third invention for growing a saturable absorption layer in a disordered growth condition region.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order for a semiconductor laser device to perform a stable self-sustained pulsation operation, it is necessary to make the carrier life of the saturable absorbing layer shorter than that of the active layer. The carrier lifetime is determined by the carrier lifetime due to radiative recombination and the carrier lifetime due to non-radiative recombination. The carrier lifetime due to radiative recombination of the saturable absorbing layer depends on the doping concentration, and the carrier lifetime due to non-radiative recombination depends on the density of deep energy levels such as interface levels, impurity levels, and defect levels and the capture cross section. Dependent. In the prior art, the doping concentration of the saturable absorbing layer was controlled to control the carrier lifetime due to radiative recombination. On the other hand, in the present invention, in addition to controlling the doping concentration of the saturable absorbing layer, the carrier life due to non-radiative recombination is reduced by controlling both the defect level and the defect density, thereby reducing the overall carrier lifetime. Is to be reduced.

The present invention, by controlling the saturable absorbing layer growth conditions for the interface, the self-pulsation type semiconductor laser device characterized by introducing a deep order of defects and impurities in the saturable absorbing layer It is a growth method. The growth condition of the saturable absorption layer according to the present invention is characterized in that the growth temperature and the surface reconstructed structure during the growth are set to values and structures different from those of the active layer.

According to the growth method of the present invention, in addition to controlling the dopant concentration of the saturable absorbing layer, the defect level and the defect density are controlled together or , in addition, the natural superlattice structure is disordered, thereby achieving the saturable structure. The carrier lifetime can be controlled without impairing the performance of the device due to the diffusion of the dopant in the absorption layer.

In the growth method of the present invention, the defect level and the defect density are controlled. The carrier lifetime due to non-radiative recombination depends on the density of deep energy levels such as interface levels, impurity levels, and defect levels and the capture cross section. As the density of these deep energy levels increases, PL increases in proportion to carrier lifetime.
The strength also decreases. Therefore, the carrier life is
The PL intensity of the saturable absorbing layer can be evaluated as a guide.

In an AlGaInP-based self-pulsation type semiconductor laser device, GaInP is often used as a saturable absorption layer. FIG. 6 shows the PL peak intensity of the Ga _0.5 In _0.5 P bulk and the growth temperature dependence of the reflection high-energy electron diffraction (RHEED) pattern. The PL measurement was performed at room temperature (RT) at an excitation light density of 5 W / cm ² using an Ar ion laser as an excitation light source. GaInP was grown by lattice matching on a GaAs substrate by a gas source MBE method. The layer thickness of the grown GaInP is 1 μm, the growth rate is 1 μm / h,
The PH ₃ flow rate during growth was 4 sccm. At this time, the growth temperature at which the maximum PL peak intensity is obtained is 540 ° C.,
The RHEED pattern at the growth temperature is (2 ×
1). When the growth temperature was in the range of 460 to 590 ° C., a specular epi layer was obtained. Under these conditions, the growth temperature is 47
If the temperature is lower than 0 ° C., the pattern is (1 × 1), if it is 470 to 530 ° C., it is (2 × 2), and if it is 530 to 580 ° C., it is (2 × 1).
1) A pattern (1 × 1) was observed at a temperature exceeding 580 ° C. The RHEED pattern reflects the periodicity of the surface reconstruction structure. Therefore, it is understood that the surface reconstruction structure changes when the growth temperature changes.

In a high growth temperature region exceeding 540 ° C.,
Since the re-evaporation rate of P increases as the growth temperature increases, the number of defects at the group V site where P atoms have escaped from the crystal increases. In a growth temperature region lower than 540 ° C., P atoms are excessively supplied, so that surface migration of Group III atoms is inhibited and defects at Group III sites increase. These defects form a deep energy level in the crystal, capture carriers excited in the crystal, and cause non-radiative recombination, so that the PL intensity decreases. Therefore, the graph of the growth temperature dependence of the PL peak intensity becomes a convex graph having the peak at the optimum growth temperature as shown in FIG.

The method of growing a self-pulsation type semiconductor laser device according to the present invention is characterized in that the difference between the growth temperature of the saturable absorption layer and the growth temperature of the active layer is 30 ° C. or more. For example, when the active layer is grown at 540 ° C., which is the optimum growth temperature, and the saturable absorbing layer is grown at 580 ° C. or 480 ° C., FIG.
From this, it can be seen that the PL intensity of the saturable absorption layer with respect to the active layer is reduced by one digit.

Alternatively, the method for growing a self-pulsation type semiconductor laser device according to the present invention is characterized in that the surface reconstruction structures at the time of growing the saturable absorption layer and the active layer are different from each other. For example, at a growth rate of 1 μm / h and a PH ₃ flow rate of 4 sccm during growth, the active layer is grown at 540 ° C., which is the optimum growth temperature, and the saturable absorption layer is grown at 480 ° C. At this time, the RHEED pattern at the time of growing the active layer is (2 × 1), and the RHEED pattern at the time of growing the saturable absorption layer is (2 × 2). In this case, the PL intensity of the saturable absorbing layer with respect to the active layer is reduced by one digit.

The growth conditions under which the PL intensity of the saturable absorbing layer with respect to the active layer is reduced by one digit or by one digit or more are considered including the group V flow rate. FIG. 7 shows RHE during Ga _0.5 In _0.5 P growth.
FIG. 3 is a diagram showing an ED pattern phase diagram and a growth condition region of the present invention. The growth rate of Ga _0.5 In _0.5 P is 1 μm / h.
FIG. 7 shows a pattern of a RHEED diffraction image and a distribution area thereof under growth conditions including a PH ₃ flow rate and a substrate temperature.

The growth condition region where the PL peak intensity is maximum is a band-like region B indicated by oblique lines in the figure.

The surface state corresponding to the (1 × 1) pattern of the RHEED diffraction image is in a state in which a prominent surface structure cannot be seen because the three-dimensional structure is progressing. The growth condition region where the (1 × 1) pattern is observed exists on the high temperature side and the low temperature side. Any of these (1 × 1) pattern regions is in contact with the region and different from the (1 × 1) pattern (2 × 1).
2) Strip-shaped growth sandwiched between a boundary line with a growth condition region forming a surface reconstruction structure corresponding to the (2 × 1) pattern and a line under a growth condition having a growth temperature different from the boundary line by 20 ° C. Condition areas A and C are on the low temperature side and the high temperature side, respectively. In these areas A and C, the area B
, The PL intensity is reduced by one digit or one or more digits.

Therefore, for example, the active layer is grown under the growth conditions of the region B in FIG. 7, and the saturable absorption layer is formed in the region A in FIG.
Alternatively, when the growth is performed under the growth condition of the region C, the PL intensity of the saturable absorption layer with respect to the active layer is reduced by one digit or one or more digits. When the PL peak intensity decreases by one digit, the carrier lifetime also decreases by one digit.

Optimum growth conditions depend on conditions such as the distance between the substrate and the cell as the source material and the group V gas concentration. However, the surface reconstruction structure responds to the growth conditions with good reproducibility, By using the RHEED pattern as a guide,
Growth with excellent controllability and reproducibility can be achieved.

Although the gas source MBE method has been described above, also in the metal organic vapor phase epitaxy (MOVPE) growth method, the growth temperature of the saturable absorber layer is set to a temperature different from the growth temperature of the active layer, preferably the active layer is grown. 1 from the growth temperature
By increasing or decreasing the temperature by 00 ° C. or more, defects inside the crystal can be increased and the carrier lifetime can be reduced.

At this time, if the saturable absorption layer is grown under the growth conditions around the surface reconstructed structure while monitoring the surface reconstructed structure by the surface photon absorption (SPA) apparatus, the controllability suitable for the purpose is obtained. Good growth.

FIG. 8 shows an MOV on a (001) GaAs substrate.
It is a diagram showing the growth temperature and the V / III ratio dependent grown Ga _0.5 In _0.5 P of ordered phase and disordered phase PE method. Eg in FIG. 8 indicates the band gap energy of Ga _0.5 In _0.5 P and was measured at 300K. Ga in the ordered layer
The band gap energy of _0.5 In _0.5 P is smaller than that of the disordered layer. In the range shown in FIG. 8, the region where the growth temperature is 550 ° C. or lower (region I in the diagram) or 750 ° C. or higher (region IV in the diagram) is a disordered phase.

The GaInP layer grown under the growth conditions of the region II or III has spontaneously formed an ordered structure of a group III atom arrangement as a natural superlattice, and the band gap energy of these materials has a disordered structure. It is smaller. The boundary line between the region II and the region III indicates a growth condition under which the band gap energy of the GaInP layer is minimized, and since the crystallinity in the vicinity is excellent, it is used for growing the active layer.

According to the method of growing a self-pulsation type semiconductor laser device of the present invention, a saturable absorbing layer is grown under a disordered growth condition in a temperature region lower than or higher than a growth temperature of an active layer. In addition, the saturable absorbing layer is disordered. Since the GaInP saturable absorption layer grown under these conditions has a low or high growth temperature, the defect density increases as compared with the active layer, and the carrier lifetime decreases.

The method for growing a self-pulsation type semiconductor laser device of the present invention can be applied irrespective of the structure of the active layer, the cladding layer, and the saturable absorption layer of the semiconductor laser device, and the structure of the entire semiconductor laser device. . The growth method of the present invention further comprises
The invention can be applied not only to the lGaInP-based material but also to a self-pulsation type semiconductor laser device made of an AlGaInN-based material or a II-VI group compound semiconductor material.

[0040]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited to these examples.

Embodiment 1 FIG. 1 shows a self-excited AlGaInP system according to the method of the present invention.
1 shows a cross-sectional configuration diagram of a vibration type semiconductor laser device. This element
Represents an n-electrode (101), an n-GaAs substrate (102), and a layer thickness of 100.
nm-GaInP buffer layer (103), layer thickness 800n
m (Al_0.7Ga _0.3)_0.5In_0.5Has the composition P
n-AlGaInP cladding layer (104), 50 nm thick
(Al_0.5Ga_0.5)_0.5In_0.5N- having a composition of P
AlGaInP optical confinement layer (105), 10 nm thick G
a_0.58In_0.42P well layer and 4 nm thick (Al_0.7G
a_0.3)_0.48In_0.52Four quantum wells composed of P barrier layers
GaInP / AlGaInP multiple quantum well active with door
Layer (106), 50 nm thick (Al_0.5Ga_0.5)_0.5In
_0.5P-AlGaInP light confinement with composition P
Layer (107), 100 nm thick (Al_0.7Ga_0.3)_0.5In
_0.5P-AlGaInP cladding layer having composition P
(108), Ga having a thickness of 10 nm_0.58In_0.42With the P-well layer
4 nm thick (Al_0.7Ga_0.3)_0.48In_0.52P barrier
GaInP / AlG with two quantum wells consisting of layers
a saturable absorption layer (10
9), layer thickness 1000 nm (inner mesa side cladding layer thickness 300 n
m) (Al_{0 .7}Ga_0.3)_0.5In_0.5Has the composition P
P-AlGaInP cladding layer (110) (mesa width of about 5 μm)
m), a 700 nm-thick n-GaAs block layer (11
1), 100-nm-thick Ga_0.5In_0.5Has the composition P
P-GaInP contact layer (112), layer thickness 200 nm
From the p-GaAs contact layer (113) and the p-electrode (114)
The lattice defect density of the GaInP saturable absorption layer (109)
Is the GaInP / AlGaInP multiple quantum well active layer (1
06) 10 times or more the lattice defect density of the GaInP well layer
A self-pulsating semiconductor laser device characterized by
is there. n-GaInP buffer layer (103), n-AlGa
InP cladding layer (104), n-AlGaInP optical confinement
Layer (105) and n-GaAs blocking layer (111)
5 × 10¹⁷cm^-3It is. p-AlGaInP
The doping concentration of the light confinement layer (107) is 5 × 10¹⁷cm
^-3, The doping concentration of the p-cladding layer and the saturable absorbing layer is 8
× 10¹⁷cm ^-3It is. p-GaInP contact layer (1
12) Doping concentration is 1 × 10¹⁸cm^-3, P-GaAs
The doping concentration of the s-contact layer (113) is 5 × 10¹⁸c
m^-3It is.

In this embodiment and the following embodiments, the strict composition and thickness of the saturable absorbing layer (109) are set so that the undoped absorption wavelength becomes substantially equal to the LD oscillation wavelength. Further, a p-AlGaInP cladding layer (108)
And the composition and thickness of the saturable absorbing layer (109) were set so that the light confinement coefficient of the saturable absorbing layer satisfied the value required for self-pulsation.

The growth was performed by a gas source MBE method, and the cladding layer was grown on a GaAs substrate by lattice matching.
The GaAs contact layer was grown at 600 ° C.

FIG. 2 is a diagram showing a band structure and a growth temperature profile of a conduction band near an active layer of an AlGaInP-based self-pulsation type semiconductor laser device. The feature of the growth method of the self-pulsation type semiconductor laser device of this embodiment is that the gas source M
Using the BE method, a growth rate of about 1 μm / h, and a PH ₃ flow rate during growth of 4 sccm, GaInP / AlGa was used.
Growing the InP multiple quantum well active layer (106) at a growth temperature of 540 ° C. where the maximum PL peak intensity is obtained and growing the GaInP well layer of the saturable absorber layer (109) at a low growth temperature of 480 ° C .; Immediately before the growth of the GaInP well layer, only P was supplied to the substrate surface, and the supply of Ga and In was interrupted for 3 minutes.
° C, and immediately after the growth of the GaInP well layer, the state where only P was supplied to the substrate surface and the supply of Ga and In was suspended for 3 minutes, during which the substrate temperature was raised by 60 ° C,
To grow an AlGaInP barrier layer or a p-cladding layer (110) of the saturable absorbing layer (109) at 540 ° C.

Further, in this embodiment, R
HEED pattern is (2 × 1), GaI of saturable absorption layer
The RHEED pattern during the growth of the nP well layer is (2 ×
2), each having a feature that the surface reconstruction structure at the time of growth is different.

Embodiment 2 FIG. 3 is a diagram showing a band structure and a growth temperature profile of a conduction band near an active layer of an AlGaInP-based self-pulsation type semiconductor laser device having the same configuration as that of Embodiment 1. The feature of the growth method of the self-pulsation type semiconductor laser device of the present embodiment is that the gas source MBE method is used and the growth rate is about 1 μm /
h, under the condition that the PH ₃ flow rate during growth is 4 sccm, GaInP
/ AlGaInP multiple quantum well active layer (106)
The GaInP well layer of the saturable absorbing layer (109) was grown at a growth temperature of 540 ° C. where L peak intensity was obtained.
C., only P is supplied to the substrate surface just before growing the GaInP well layer, and Ga,
The state in which the supply of In was interrupted was maintained for 3 minutes, during which the substrate temperature was increased by 40 ° C., and immediately after the growth of the GaInP well layer, the state in which only P was supplied to the substrate surface and the supply of Ga and In was interrupted was changed to 3. Hold the substrate temperature for 40 minutes
At 540 ° C, the AlGaI of the saturable absorbing layer (109)
This is to grow an nP barrier layer or a p-cladding layer (110).

Embodiment 3 The saturable absorption layer of the self-pulsation type semiconductor laser device of the present embodiment is replaced with the saturable absorption layer (109) having the double quantum well structure of Example 1 except that the layer thickness is 10 nm. Ga _0.58 In _0.42
A GaInP saturable absorption layer (201) as a P single layer was formed.

FIG. 4 is a diagram showing the band structure of the conduction band near the active layer of this AlGaInP-based self-pulsation type semiconductor laser device, and the profile of the growth temperature and the V / III ratio.
The feature of the growth method of the self-pulsation type semiconductor laser device of this embodiment is that the MOVPE method is used and the pressure during the growth is 70%.
torr, the growth rate was about 1 μm / h, and GaInP / Al
The GaInP multiple quantum well active layer (106) has a V / III ratio of 60.
0, grown at a substrate temperature of 650 ° C. and GaInP
The saturable absorption layer (201) is V / III ratio 100, substrate temperature 500
The p-cladding layer (110) is grown at a V / III ratio of 6
That is, the growth is performed at a substrate temperature of 650 ° C. GaInP saturable absorption layer grown under these conditions (201)
Has a disordered structure and a low growth temperature, so that the defect density increases as compared with the active layer, and the carrier lifetime decreases.

Embodiment 4 FIG. 5 is a diagram showing a band structure of a conduction band near an active layer of an AlGaInP-based self-pulsation type semiconductor laser device having the same structure as in Embodiment 3, and a profile of a growth temperature and a V / III ratio. It is. The feature of the growth method of the self-pulsation type semiconductor laser device of this embodiment is that the MOVPE method is used, the pressure during the growth is 70 torr, the growth rate is about 1 μm / h, and the GaInP
/ AlGaInP multiple quantum well active layer (106) is grown under conditions of V / III ratio of 600, substrate temperature of 650 ° C.
The nP saturable absorption layer (201) has a V / III ratio of 100 and a substrate temperature of 7
The p-cladding layer (110) was grown at 60 ° C.
The growth is performed under the conditions of a ratio of 600 and a substrate temperature of 650 ° C. The GaInP saturable absorption layer (20
1) has a disordered structure and has a high growth temperature, so that the defect density increases compared to the active layer, and the carrier lifetime decreases.

In the MOVPE growth method, the reconstructed structure of the semiconductor surface during growth is observed using SPA, and the growth conditions of the active layer and the saturable absorption layer are controlled.
Growed with different surface reconstructions. It was more effective in controlling the crystal quality of both.

[0051]

As is apparent from the above description, the present invention controls the growth conditions to increase the defect density of the saturable absorbing layer, or additionally, to disorder the natural superlattice structure of the saturable absorbing layer. By doing so, the carrier life of the saturable absorption layer can be shortened and the transition energy can be stabilized without doping the saturable absorption layer with high concentration. As a result, the characteristics of the laser element are not degraded by the diffusion of the dopant from the saturable absorption layer, so that a self-pulsation type laser element having a long operating life, a small threshold value, and stable and excellent characteristics can be obtained. .

Further, by using the self-pulsation type laser element as a light source for pickup of an optical disk device, a high-performance optical disk device with reduced return light noise of a semiconductor laser can be realized at low cost.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of an AlGaInP-based self-pulsation type semiconductor laser device according to a method of the present invention.

FIG. 2 is a diagram showing a band structure and a growth temperature profile of a conduction band near an active layer of the self-pulsation type semiconductor laser device in Example 1.

FIG. 3 is a diagram showing a band structure and a growth temperature profile of a conduction band near an active layer of a self-pulsation type semiconductor laser device in Example 2.

FIG. 4 shows a band structure of a conduction band near an active layer, a growth temperature, and V / II of a self-pulsation type semiconductor laser device in Example 3.
It is a figure which shows the profile of an I ratio.

FIG. 5 shows a band structure, a growth temperature, and V / II of a conduction band near an active layer of a self-pulsation type semiconductor laser device in Example 4.
It is a figure which shows the profile of an I ratio.

FIG. 6 shows PL peak intensity and R of Ga _0.5 In _0.5 P bulk.
It is a graph which shows the growth temperature persistence of a HEED pattern.

FIG. 7 is a diagram showing a RHEED pattern phase diagram during Ga _0.5 In _0.5 P growth and a growth condition region of the present invention.

FIG. 8 is a diagram showing the growth temperature of an ordered phase and a disordered phase of Ga _0.5 In _0.5 P grown on a (001) GaAs substrate by the MOVPE method and the dependence on the group V / III group material ratio.

FIG. 9 is a graph showing a relationship between a PL peak wavelength (energy display) of GaInP and a dopant concentration in the conventional technique.

[Explanation of symbols]

 Reference Signs List 101 n electrode 102 n-GaAs substrate 103 n-GaInP buffer layer 104 n-AlGaInP cladding layer 105 n-AlGaInP light confinement layer 106 GaInP / AGaInP multiple quantum well active layer 107 p-AlGaInP light confinement layer 108 p-AlGaInP cladding layer 109 , 201 Saturable absorption layer 110 p-AlGaInP cladding layer 111 n-GaAs block layer 112 p-GaInP contact layer 113 p-GaAs contact layer 114 p electrode

Continuation of front page (56) References JP-A-7-263794 (JP, A) JP-A-5-259079 (JP, A) JP-A-4-229685 (JP, A) JP-A-3-50181 (JP) JP-A-7-6967 (JP, A) JP-A-3-174739 (JP, A) JP-A-7-153805 (JP, A) JP-A-63-42114 (JP, A) 4-283980 (JP, A) Applied Physics, Vol. 56, No. 8, (1987), p. 990-999 Jpn. J. Appl. Phys. 34 [4B] (1995) p. L469-L472 Semicon. Sci. Technology. 8 [1S] (1993) p. S9-S15 (58) Field surveyed (Int. Cl. ⁶ , DB name) H01S 3/18 H01L 21/203 H01L 21/205 JICST file (JOIS)

Claims (10)

(57) [Claims] In a method of growing a self-pulsation type semiconductor laser device having a saturable absorption layer and an active layer, the carrier lifetime of the saturable absorption layer is activated by the formation of defects.
A growth temperature of at least one semiconductor layer 1 having a minimum forbidden band width among semiconductor layers constituting the saturable absorption layer in the at least one saturable absorption layer so as to be shorter than a carrier lifetime of the active layer; The difference from the growth temperature of at least one semiconductor layer 2 having the smallest forbidden band width in the semiconductor layers constituting the semiconductor layer is 30 ° C. or more, and
One the growth temperature of the semiconductor layer 2 of the active layer, a half of the saturable absorber layer
A method of growing a self-pulsation type semiconductor laser device, wherein the temperature is set closer to the optimum growth temperature than the growth temperature of the conductor layer 1 . 2. The method for growing a self-pulsation type semiconductor laser device according to claim 1, wherein the semiconductor layer 1 and the semiconductor layer 2 are grown so that their surface reconstruction structures are different from each other. 3. A state in which only the group V raw material is supplied and the supply of the group III raw material is interrupted for 1 minute or more immediately before and immediately after the growth of the semiconductor layer 1, respectively.
3. The method according to claim 1, wherein the substrate temperature is changed during the period. 4. The method according to claim 1, wherein the growth is performed using a molecular beam epitaxial growth apparatus equipped with a reflection high-speed electron diffraction apparatus.
4. The method for growing a self-pulsation type semiconductor laser device according to 2 or 3. 5. The method according to claim 4, wherein the difference between the growth temperature of the semiconductor layer 1 and the growth temperature of the semiconductor layer 2 is 40 to 70 ° C. 6. A method for growing a self-pulsation type semiconductor laser device having a saturable absorbing layer and an active layer, wherein a growth condition comprising a supply flow rate of a group V source (or a ratio of a group V / group III source) and a growth temperature. Due to the formation of defects
The carrier life of the saturable absorbing layer is the carrier life of the active layer.
As becomes smaller, corresponding to different patterns and growth condition region to form a (1 × 1) corresponding surface reconstruction structure in a pattern of high energy electron diffraction image, a contact and (1 × 1) pattern in the area A boundary with a growth condition region forming a surface reconstruction structure
A condition in a growth condition region which is a growth condition region sandwiched between lines having different growth conditions by a growth temperature of 20 ° C. from the boundary line and forms a surface reconstruction structure corresponding to a pattern different from the (1 × 1) pattern. To grow a saturable absorber layer and to make the active layer a more suitable supply flow rate than the saturable absorber layer.
A method for growing a self-sustained pulsation type semiconductor laser device, wherein the semiconductor laser is grown under conditions in a growth condition region of a growth temperature . 7. A growth method using a metal organic vapor phase epitaxy apparatus having a surface photon absorption apparatus.
4. A method for growing a self-pulsation type semiconductor laser device according to item 3. 8. The method according to claim 7, wherein a difference between a growth temperature of the semiconductor layer 1 and a growth temperature of the semiconductor layer 2 is 100 ° C. or more. 9. Using a metal-organic vapor phase epitaxial growth apparatus, the semiconductor layer 1 is grown under a disordered growth condition in a temperature range lower than the growth temperature of the active layer with respect to the growth conditions comprising the group V / III source ratio and the growth temperature. 4. The method according to claim 1, wherein the saturable absorption layer is grown in the region. 10. Using a metal-organic vapor phase epitaxial growth apparatus, a semiconductor layer 1 is grown in a disordered growth condition in a temperature range higher than the growth temperature of an active layer with respect to a growth condition comprising a group V / III source ratio and a growth temperature. 4. The method according to claim 1, wherein the saturable absorption layer is grown in the region.