JP2893990B2 - Semiconductor laser and manufacturing method thereof - 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 having high mode stability and excellent reliability.

[0002]

2. Description of the Related Art Semiconductor lasers that emit light by generating laser oscillation in the visible light region have been used as light sources for optical information processing and light sources for optical measurement, and have recently become increasingly important. Above all, (Al _x Ga _{1 -x} ) _0.5 In _0.5 P-based material is lattice-matched to GaAs which is a good quality substrate, and laser oscillation is performed in a wavelength range of 0.68 μm to 0.56 μm by changing the composition x. Is attracting attention because it can be obtained. A double hetero structure is used for a semiconductor laser.

A lateral mode control type red-emitting semiconductor laser having a double hetero structure will be described below using a conventional example. This semiconductor laser, as shown in FIG.
An n-GaAs buffer layer 2 and an n- (A
l _0.7 Ga _0.3 ) _0.5 In _0.5 P clad layer 13, Ga _0.5
In _0.5 P active layer 4, p- (Al _0.7 Ga _0.3 ) _0.5 In _0
.5 P cladding layer 14, p-Ga _0.5 In _0.5 P layer 7, n-
A GaAs current block layer 8 and a p-GaAs contact layer 9 are sequentially formed, and thereafter a p-electrode 10 and an n-electrode 11 are formed.
Is formed. Zinc (Zn) is used for the p-type impurity, and selenium (Se) or silicon (Si) is used for the n-type impurity.

In this semiconductor laser, metal organic chemical vapor deposition (MOVPE) or molecular beam epitaxy (MBE) is used.
) Is used. Using these crystal growth techniques, n-GaAs substrate 1 is formed on n-GaAs substrate 1.
Buffer layer _{2, n- (Al 0.7 Ga 0.3} ) 0.5 In 0.5 P cladding layer 13, Ga _0.5 In _0.5 P active layer 4, p- (Al
_0.7 Ga _0.3 ) _0.5 In _0.5 P clad layer 14 and p-G
sequentially depositing a _0.5 In _0.5 P layer 7, the following photolithographic technique and etching technique, p-Ga _{0. 5} In _0.5
The P layer 7 and the p- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P cladding layer 14 are trapezoidally etched to form a mesa stripe, and then the n-GaAs current blocking layer 8 is selectively formed by MOVPE or the like. And p-GaAs
A contact layer 9 is deposited.

In such a semiconductor laser structure, n-
It can perform narrowing of the current of a GaAs current blocking layer 8, also when etching p- an _{(Al 0.7 Ga 0.3) 0.5 In} 0.5 P cladding layer 14 on the trapezoid to optimize the trapezoid height and width As a result, an effective refractive index difference satisfying the condition of the single transverse mode can be provided, and light can be effectively confined near the active layer below the trapezoid.

[0006]

However, the main constituent material of this semiconductor laser, (Al _0.7 Ga _0.3 ) _0.5 I
n _0.5 P has a problem that, as a material property, impurities such as Zn and Se are easily diffused. For example, when compared with the diffusion speed of AlGaAs, which is a main constituent material of a semiconductor laser having an oscillation wavelength in the 830 nm band, (Al _0.7 Ga
_0.3 ) _0.5 In _0.5 P is one order of magnitude larger, so diffusion occurs easily. In the structure shown in FIG. 8, the crystal growth is performed three times (from the n-GaAs buffer layer 2 to the p-Ga _0.5
A first crystal growth step of growing up to the In _0.5 P layer 7, a second crystal growth step of forming an n-GaAs current block layer 8, and a third crystal growth step of forming a p-GaAs contact layer 9 ) is necessary, Ga _{0. 5} in _0.5 P active layer 4 during heating of the second and third crystal growth step
Abnormal diffusion of Zn and Se, which are impurities, to the semiconductor is likely to occur. It is shown in FIG. FIG. 9 shows a SIMS-based element distribution in the depth direction of the semiconductor laser of FIG. It can be seen from the figure that Zn, which is a p-impurity of the cladding layer 14, diffuses through the active layer to the n-cladding layer 13 by diffusion.
As a result, as shown in FIG. 10, the low-resistance portion 30 and the high-resistance portion 31 are unevenly distributed in the Ga _0.5 In _0.5 P active layer, causing unevenness in current injection and likely to cause instability of the mode of laser light. . In addition, diffusion of intrinsic defects such as vacancies into the Ga _0.5 In _0.5 P active layer 4 is induced simultaneously with the diffusion of impurities such as Zn and Se. The intrinsic defect forms a deep level in the GaInP active layer 4. A deep level becomes a non-emission center and lowers luminous efficiency. Therefore, the driving current of the semiconductor laser required to obtain a desired optical output increases, and the life of the semiconductor laser may be shortened.

An object of the present invention is to provide a semiconductor laser having high stability of a mode of a laser beam and a long life.

[0008]

Means for solving the above problems are as follows.

(1) The n-type cladding layer, the active layer, and the p-type cladding layer
Current formed on the formed substrate by MOVPE method
Semiconductor laser having block layer and p-type contact layer
Between the p-type cladding layer and the active layer.
-Containing first semiconductor layer and undoped second semiconductor layer
Semiconductor having a thin-film multilayer structure with a body layer
laser. The thickness of the second semiconductor layer is the diffusion length of majority carriers
It may be thinner. (2) The n-type cladding layer, the active layer, and the p-type cladding layer
Current formed on the formed substrate by MOVPE method
Semiconductor laser having block layer and p-type contact layer
Wherein the p-type cladding layer is
The thickness of the first semiconductor layer and the thickness of the second semiconductor layer to which no impurity is added;
The film has a multilayer structure and the first semiconductor layer is forbidden.
The band width is larger than the forbidden band width of the second semiconductor layer.
Semiconductor laser. When the thickness of the second semiconductor layer is
It may be thinner than the rear diffusion length.

(3) An n-type cladding layer, an active layer, and a p-type cladding layer
After the current blocking layer and the p-type
Forming a contact layer by MOVPE
A method for manufacturing a semiconductor laser, comprising:
An impurity-doped first semiconductor layer and an impurity-free
A thin-film multilayer structure with a second semiconductor layer;
The forbidden band width of the conductor layer is larger than the forbidden band width of the second semiconductor layer
A method for manufacturing a semiconductor laser.

(4) An n-type cladding layer, an active layer, and impurities are present on the substrate.
The doped first semiconductor layer and the doped second semiconductor layer
P-type cladding layer having a thin film multilayer structure with conductor layer
After the formation, the first semiconductor layer transfers impurities to the second semiconductor layer.
Current blocking layer and p-type capacitor at the temperature at which
A step of forming a tact layer, and a first semiconductor layer
The forbidden band width of the second semiconductor layer is larger than that of the second semiconductor layer
A method for manufacturing a semiconductor laser, comprising:

[0012]

According to the semiconductor laser of the present invention, since the semiconductor laser has a thin-film multilayer structure including a semiconductor layer with an impurity and a semiconductor layer with no impurity between the cladding layer and the active layer, the cladding layer and the impurity-doped semiconductor layer have the same structure. Diffusion of impurities added to the semiconductor layer stops at the impurity-free semiconductor layer in the thin-film multilayer structure, so that diffusion of impurities and defects into the active layer can be prevented. Characteristics can be prevented from deteriorating, and a highly reliable laser can be obtained. In addition, the cladding layer is semiconductive
Thin-film multilayer structure consisting of a body layer and an undoped semiconductor layer
By doing so, a similar effect can be achieved.
Wear. Note that when the thickness of the semiconductor layer of undoped thin multi-layer structure is less than the diffusion length of the majority carriers, without interfering with the injection into majority carriers active layer of the cladding layer, it is possible to obtain good characteristics it can.

According to the method of manufacturing a semiconductor laser of the present invention , an n-type cladding layer, an active layer, and a p-type cladding layer are formed on a substrate.
After the formation of the current blocking layer and the p-type
In making a contact layer of the semiconductor laser comprising a step of forming by the MOVPE method, the p-type cladding layer, since the thin-film multilayer structure consisting of the semiconductor layer and the semiconductor layer of undoped impurity addition, crystal growth of the impurities and defects Ru can be prevented from diffusing into the active layer in.

[0014]

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a lateral mode control type red semiconductor laser according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view illustrating a manufacturing process of the semiconductor laser of FIG.

This semiconductor laser is shown in FIG.
Thus, for example, the n-GaAs substrate 1 is placed on the n-GaAs substrate 1.
Ga through the fa layer 2_0.5In_0.5The P active layer 4 is made n- (A
l_{0. 6}Ga_0.4)_0.5In_0.5P clad layer 3 and p-
(Al_0.6Ga_0.4)_0.5In_0.5D sandwiched between P cladding layers 5
It has a bull hetero structure. p- (Al_0.6Ga_0.4)
_0.5In_0.5P cladding layer 5 and Ga_0.5In_0.5P active layer 4
Has a thin film multilayer structure 6 between them. Thin film multilayer structure
The detailed structure of the structure 6 is shown in FIG. Thin film multilayer structure 6
Is 5 nm p- (Al_0.6Ga_0.4)_0.5In_0.5P layer 1
5 and 5 nm impurity-free (Al_0.6Ga_0.4)_0.5I
n_0.5A structure in which P layers 16 are alternately laminated 10 times each
Has become. The first layer near the active layer of the thin film multilayer structure 6 is
5 nm impurity-free (Al_0.6Ga_0.4)_0.5In_0.5
The P layer 16. As a result, cracks close to the active layer
Defects in the active layer and the interface between the active layer and the cladding layer.
The crystallinity of the cladding layer near the active layer can be improved.
You. p- (Al_0.6Ga_0.4)_{0. Five}In_0.5P clad layer 5
And Zn or the like for the p-type impurity of the thin film
(Al_0.6Ga_0.4)_0.5In_0.5N-type layer of the P cladding layer 3
Se or the like is used as a pure product. p- (Al_0.6Ga_0.4)_0.5
In_0.5Enlargement of holes which are majority carriers of the P clad layer 5
The scattering length is several μm, and the impurity-free (Al_0.6G
a_0.4)_0.5In_0.5The P layer 16 is sufficiently thinner than this diffusion length.
Must. If no impurities are added (Al_0.6G
a_0.4)_0.5In_0.5P layer 16 is thick, close to the diffusion length of holes
If so, Ga_0.5In_0.5Hole injection into the P active layer 4 is a circle
It is not performed smoothly, and the series resistance is high.
It leads to the deterioration of characteristics. Impurity-free (Al_0.6Ga
_0.4)_0.5In_0.5The P layer 16 is preferably about 5 nm. p-
(Al_0.6Ga_0.4)_0.5In_0.5On top of the P cladding layer 5
Is p-Ga_0.5In_0.5P-Ga_0.5In
_0.5P layer 7 and p- (Al_0.6Ga_0.4)_0.5In_0.5P
Part of clad layer 5 processed into trapezoidal mesa stripe
Have been. On both sides of the trapezoid are n-GaAs current blocking layers
8 is deposited. Furthermore, p-Ga_0.5In_0.5P layer 7 and
On top of the n-GaAs current blocking layer 8 is p-GaAs
It has a contact layer 9. The trapezoid is Ga_0.5I
n_0.5Width in which the basic transverse mode is established in the P active layer 4
Set to 5 μm. The n-GaAs contact layer 9 has Cr /
A p-electrode 10 such as Pt / Au is applied to the n-GaAs substrate 1
Has deposited an n-electrode 11 of Au / Ge / Ni or the like.

The n-GaAs current blocking layer 8 and the p-Ga
When forming the As contact layer 9, the temperature becomes high.
In addition, p- (Al_0.6Ga_0.4)_0.5In_0.5P clad layer 5
And p- (Al_0.6Ga_0.4)_0.5In_0.5Not from P layer 15
Pure substance free (Al_0.6Ga_0.4)_0.5In_0.5To P layer 16
The p-type impurity, Zn, may partially diffuse.
Even when the diffusion of n occurs, the diffusion is carried out with no impurity added (A
l_0.6Ga_0.4)_0.5In_{0 .Five}G to stop at P layer 16
a_0.5In_0.5Almost no diffusion of Zn into the P active layer 4
Therefore, the characteristics of the semiconductor laser are not affected. why
Then, impurities such as Zn are p- (Al_0.6Ga_0.4)
_0.5In_0.5In the P layer, pairs with intrinsic defects such as vacancies
Stabilize. On the other hand, the impurity-free (Al_0.6Ga_0.4)
_0.5In_0.5The P layer 16 has few intrinsic defects,
The diffusion of the recesses is performed by the impurity-free (Al_{0. 6}Ga_0.4)_0.5In
_0.5Although a little occurs to the P layer 16, the diffusion is Ga_0.5In
_0.5It can be prevented from reaching the P active layer 4. if
Impurity-free (Al_0.6Ga_0.4)_0.5In_0.5P layer 16
Without G, there is nothing to prevent the diffusion of impurities.
a _0.5In_0.5Not only impurities but also vacancies etc.
Even intrinsic defects are introduced. The impurity-free (Al
_0.6Ga_0.4)_0.5In_0.5The P layer 16 has inherent defects such as vacancies.
If there are few, it does not matter if some impurities are added,
For example, p^-− (Al_{0 .6}Ga_0.4)_0.5In_0.5P layer
I don't know.

When impurities such as Zn diffuse into the Ga _0.5 In _0.5 P active layer 4, the following two problems occur. That is, (1) Since the impurity partially diffuses into the Ga _0.5 In _0.5 P active layer 4, as shown in FIG.
1 and a low-resistance portion 30 are generated and distribution of carrier injection into the active layer is formed, which causes instability of the mode of the semiconductor laser. Further, not only impurity Zn but also defects such as vacancies are introduced into the Ga _0.5 In _0.5 P active layer 4 by the diffusion of Zn, so that the diffusion of intrinsic defects such as vacancies is induced. The intrinsic defect forms a deep level in the GaInP active layer 4. A deep level becomes a non-emission center and lowers luminous efficiency. Therefore, the drive current of the semiconductor laser required to obtain a desired optical output becomes large, the life of the semiconductor laser is shortened, and the reliability is hindered. According to the present invention, Ga _0.5 I
Since there is almost no diffusion of Zn into the n _0.5 P active layer 4,
A semiconductor laser having a stable mode and a long life can be obtained.

A voltage is applied to the semiconductor laser having the above structure.
Then, holes from the p-electrode 10 side and electrons from the n-electrode 11 side
Is implanted and Ga_0.5In_0.5Holes and electrons in the P active layer 4
Recombination occurs to emit light. The emitted light resonates at the end face
Then, the laser oscillates. p- (Al_0.6Ga_0.4)_0.5In
_0.5Under the P cladding layer 5, p- (Al_0.6G
a_0.4) _0.5In_0.5P layer 15 and impurity-free (Al_0.6
Ga_0.4)_0.5In_0.5Thin film multilayer structure 6 composed of P layer 16
But with no impurities added (Al_0.6Ga_0.4)_0.5I
n_{0 .Five}Since the P layer 16 is sufficiently thin, the Ga_0.5In_0.5
The injection into the P active layer 4 is not prevented. p-Ga_0.5
In_0.5P layer 7 and p- (Al_0.6Ga_0.4)_0.5In_0
.FiveThe trapezoidal stripe formed on the P clad layer 5
Ga_0.5In_0.5A basic transverse mode is established in the P active layer 4
The width (5 μm) makes the stable single horizontal mode.
Semiconductor laser can be obtained.

Next, a method of manufacturing this semiconductor laser will be described.
This will be described with reference to FIG. First, the MOVPE method
By using a crystal growth method, n-GaAs
GaAs buffer layer 2, n- (Al_0.6Ga_0.4)_0.5I
n_0.5P cladding layer 3, Ga_{0. Five}In_0.5P active layers 4, 5
nm p- (Al_0.6Ga_0.4)_0.5In_0.5P layers 15 and 5
nm impurity-free (Al_0.6Ga_0.4)_0.5In_0.5P
The thin film multilayer structure 6 having the layer 16 as one cycle, p- (Al_0.6
Ga_0.4)_0.5In_0.5P clad layer 5, p-Ga_{0. Five}In
_0.5The P layer 7 is epitaxially grown (FIG. 7A). Thin
The first layer near the active layer of the film multilayer structure 6 has no impurities added.
(Al_0.6Ga_0.4)_0.5In_0.5The P layer 16. This thin
The film multilayer structure 6 has ten periods. Photolithography
SiO2 technology and etching technology_Two12 and p-G
a_0.5In_0.5P layer 7 and p- (Al_0.6Ga_0.4)_0.5In
_0.5Part of P cladding layer 5 processed into trapezoidal stripe
(Figure (b)). After processing into trapezoidal shape, MOVPE method
N-GaAs current blocking layer using selective growth technology
8 for SiO_Two12 without trapping on both sides of trapezoid
The crystal is grown (FIG. 3 (c)). After that, the SiO_Two12
Is removed, and the p-GaAs contact layer 9 is crystal-grown.
(Figure (d)). n-GaAs current blocking layer 8
Is a high temperature during the crystal growth of the p-GaAs contact layer 9.
In order to be in a state, p- (Al_0.6Ga_0.4)_0.5In_0.5
P cladding layer 5 and p- (Al_0.6Ga_0.4) _0.5In_0.5
From the P layer 15, the impurity-free (Al_0.6Ga_0.4)_0.5I
n_0.5Zn that is a p-type impurity partially diffuses into the P layer 16
In some cases, the diffusion is carried out by using undoped (Al_0.6G
a_0.4)_0.5In_0.5Since it stops at the P layer 16, Ga_0.5In
_0.5Zn hardly diffuses into the P active layer 4.
Zn as an impurity is p- (Al_0.6Ga_{0 .Four})_0.5In_0.5
In the P layer, it is stabilized in pairs with intrinsic defects such as vacancies.
You. On the other hand, the impurity-free (Al_0.6Ga_0.4)_0.5In
_0.5The P layer 16 has few intrinsic defects and no impurity diffusion.
Pure substance free (Al_0.6Ga_0.4)_0.5In_0.5To P layer 16
Although it occurs to some extent, the diffusion is Ga_0.5In_0.5P active layer 4
Can be prevented. If undoped
(Al_0.6Ga_0.4)_0.5In_0.5If there is no P layer 16,
Since there is no layer to prevent the diffusion of pure substances, Ga_0.5In_0.5P
In the active layer 4, not only impurities but also intrinsic defects such as vacancies
be introduced. p- (Al_0.6Ga_0.4)_0.5In_0.5P layer 1
5 and impurity-free (Al_0.6Ga_0.4)_0.5In_0.5P layer
By providing the thin film multilayer structure 6 composed of_0.5
In_0.5The introduction of defects into the P active layer 4 can be prevented.

The above impurity-free (Al _0.6 Ga _0.4 )
_0.5 an In _0.5 P layer 16, the less unique defects such as vacancies, not may be each other slightly doped, for example, p ^-
- (Al _{0 .6} Ga _0.4) may be _0.5 an In _0.5 P layer.

Finally, C is formed on the p-GaAs contact layer 9.
r / Pt / Au is deposited to form a p-electrode 10 and n-GaAs
Au / Ge / Ni is deposited on the s-substrate 1 to form an n-electrode 11 (FIG. 7E).

By such a manufacturing method, a lateral mode control type red semiconductor laser as shown in FIG. 1 can be manufactured.

(Al_0.6Ga_0.4)_0.5In_0.5P is MOV
When the crystal is grown by the PE method or the like, the group III elements Al and G
It is easy to form a natural superlattice in which a and In are regularly arranged.
When this natural superlattice is formed, (Al_0.6Ga_0.4)_0.5
In_0.5The band gap of the P crystal becomes smaller. Supernatural
In the state where the lattice is formed and the state where it is not formed, the band gap
The difference is about 70 meV. In the first crystal growth, n-
On a GaAs substrate 1, an n-GaAs buffer layer 2, n-
(Al_0.6Ga_0.4)_0.5In_0.5P cladding layer 3, Ga
_0.5In_0.5P active layer 4, 5 nm p- (Al_0.6G
a_0.4)_0.5In_0.5P layer 15 and 5 nm impurity-free
(Al_0.6Ga_0.4)_0.5In_0.5Many thin films composed of P layer 16
Layer structure 6, p- (Al_0.6Ga_0.4)_0.5In_0.5P crack
Layer 5, p-Ga_{0. Five}In_0.5Epitaxial formation of P layer 7
Lengthen. In the second and subsequent crystal growths, p- (Al_0.6Ga
_0.4)_0.5In_0.5P cladding layer 5 and p- (Al_0.6Ga
_0.4)_0.5In_{0 .Five}From the P layer 15, the impurity-free (Al_0.6
Ga_0.4)_0.5In_0.5Zn which is a p-type impurity is added to the P layer 16.
Diffusion occurs. At this time, the diffusion of impurities
Part of the natural superlattice in the layer structure 6 changes to a disordered state.
(Al) in the thin film multilayer structure 6 _0.6Ga_0.4)_0.5In
_0.5The band gap of the P crystal increases. Figure 7
Shown in As a result, Ga_0.5In_0.5P active layer 4 and many thin films
The band gap difference of the layer structure 6 can be increased,
Carriers are easily trapped in the active layer 4,
Reduction of threshold current of body laser, improvement of temperature stability, etc.
Characteristics can be improved.

In this embodiment, (Al _x Ga _{1 -x} ) _0.5 In
_0.5 P (0 ≦ x ≦ 1)
This has been described using n. However, even in the case of other impurities, for example, Se, the mode is stable and the reliability is improved by forming a thin film multilayer structure including a semiconductor layer doped with impurities and a semiconductor layer doped without impurities between the cladding layer and the active layer. And a semiconductor laser having good characteristics can be manufactured.

In this embodiment, the thin film multilayer structure 6 is
a _0.5 In _0.5 P active layer 4 and p- (Al _0.6 Ga _0.4 ) _0.5
Although placed between the In _0.5 P cladding layers 5, p- (Al
_{If the} entire structure of the _0.6 Ga _0.4 ) _0.5 In _0.5 P clad layer 5 is the same as the thin film multilayer structure 6, the diffusion of the p-type impurity can be further prevented. In the embodiment, the thin film multilayer structure 6 has a thickness of 5n.
m of _{p- (Al 0.6 Ga 0.4) 0.5} In 0.5 P layer 15 and 5n
m has a periodic structure with one cycle of the undoped (Al _0.6 Ga _0.4 ) _0.5 In _0.5 P layer 16. However, the undoped (Al _0.6 Ga _0.4 ) _0.5 I in the thin film multilayer structure 6 has a periodic structure.
If the n _0.5 P layer is thinner than the diffusion length of majority carriers, it is not necessary to form a periodic structure, and the effect of the present invention is great.

In the above embodiment, the material constituting the double hetero structure is specified, but the cladding layer is made of (Al _y Ga _1-y ).
_0.5 In _0.5 P, the active layer is (Al _z Ga _{1 -z} ) _0.5 In _0.5 P
(Where 0 ≦ z ≦ y ≦ 1), a semiconductor laser with stable modes, high reliability, and good characteristics can be manufactured. In addition, although the material of the impurity-added semiconductor layer and the material of the impurity-free semiconductor layer constituting the thin-film multilayer structure 6 are the same, the materials of the two semiconductor layers may be different. The ratio (composition) of Al in the doped semiconductor layer and the doped semiconductor layer may be changed. For example, a p- (Al _0.6 Ga _0.4 ) _0.5 In _0.5 P layer is added to the doped semiconductor layer, The impurity-free (Al
_{Even if a 0.15} Ga _0.85 ) _0.5 In _0.5 P layer is used, the effect of the present invention is great.

[0029]

According to the semiconductor laser of the present invention, (1) in a semiconductor laser having a double heterostructure, a thin film comprising an impurity-doped semiconductor layer and an undoped semiconductor layer between a cladding layer and an active layer. having a multi-layer structure
Added to the cladding layer and the doped semiconductor layer
Diffusion of the impurities indicated in the thin film multilayer structure
Since it stops at an additional semiconductor layer, diffusion of impurities and defects into the active layer can be prevented, and deterioration of semiconductor laser characteristics due to diffusion of impurities and defects can be prevented .
A high laser can be obtained. In addition, if the cladding layer is not
Consisting of pure and doped semiconductor layers
Similar effects can be obtained by adopting a thin film multilayer structure.
Can play. (2) An impurity-free semiconductor layer in a thin film multilayer structure
When the film thickness is smaller than the diffusion length of majority carriers,
Do not prevent the injection of majority carriers in the active layer into the active layer.
And good characteristics can be obtained.

According to the method of manufacturing a semiconductor laser of the present invention, (3) the p-type cladding layer has a thin-film multilayer structure composed of an impurity-added semiconductor layer and an undoped semiconductor layer .
Thus, diffusion of impurities and defects into the active layer during crystal growth can be prevented, and a semiconductor laser having a stable mode and excellent reliability can be manufactured.

(4) The diffusion of impurities from the first semiconductor layer to the second semiconductor layer
Current blocking layer and p-type contact at the temperature where diffusion occurs
Even in the case of forming a layer, diffusion of impurities and defects into the active layer can be prevented by stopping diffusion in the semiconductor layer to which impurities are not added.

[0032]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a lateral mode control type red semiconductor laser according to an embodiment of the present invention.

FIG. 2 is a first step-by-step cross-sectional view illustrating a step of manufacturing the semiconductor laser of the present invention.

FIG. 3 is a sectional view in a second process order showing a manufacturing process of the semiconductor laser of the present invention.

FIG. 4 is a third step-by-step cross-sectional view illustrating a step of manufacturing the semiconductor laser of the present invention.

FIG. 5 is a fourth step-by-step cross-sectional view illustrating a step of manufacturing the semiconductor laser of the present invention.

FIG. 6 is a fifth process order sectional view illustrating a manufacturing process of the semiconductor laser of the present invention.

FIG. 7 is an energy band diagram before and after disordering of a thin film multilayer structure.

FIG. 8 is a sectional view of a configuration of a red semiconductor laser.

FIG. 9 is a diagram for explaining diffusion of a P-type impurity Zn by SIMS.

FIG. 10 is a diagram showing a distribution of resistance formed in an active layer by diffusion of a P-type impurity Zn.

[Explanation of symbols]

Reference Signs List 1 n-GaAs substrate 2 n-GaAs buffer layer 3 n- (Al _0.6 Ga _0.4 ) _0.5 In _0.5 P cladding layer 4 Ga _0.5 In _0.5 P active layer 5 p- (Al _0.6 Ga _0.4 ) _0.5 In _0.5 P cladding layer 6 Thin film multilayer structure 7 p-Ga _0.5 In _0.5 P layer 8 n-GaAs current blocking layer 9 p-GaAs contact layer 10 p electrode 11 n electrode 12 SiO ₂ 13 n- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P cladding layer 14 p- (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P clad layer 15 p- (Al _0.6 Ga _0.4 ) _0.5 In _0.5 P layer 16 Undoped (Al _0.6 Ga _0.4 ) _0.5 In _0.5 P
layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-82286 (JP, A) JP-A-63-116483 (JP, A) JP-A-3-62584 (JP, A) JP-A-2- 33990 (JP, A) JP-A-64-90576 (JP, A) JP-A-1-189188 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01S 3/18

Claims (5)

(57) [Claims] 1. An n-type cladding layer, an active layer, and a p-type cladding layer.
Formed by MOVPE on the substrate on which
Having broken current blocking layer and p-type contact layer
Body laser, between the p-type cladding layer and the active layer,
A first semiconductor layer containing impurities and a second semiconductor layer containing no impurities;
A semiconductor laser having a thin-film multilayer structure with a semiconductor layer . 2. An n-type cladding layer, an active layer, and a p-type cladding layer.
Formed by MOVPE on the substrate on which
Having broken current blocking layer and p-type contact layer
The p-type cladding layer is doped with impurities.
A doped first semiconductor layer and a doped second semiconductor layer.
A thin-film multilayer structure with a semiconductor layer, and
The forbidden band width of the first semiconductor layer is equal to the forbidden band of the second semiconductor layer.
A semiconductor laser characterized by being larger than a width . 3. The method according to claim 1 , wherein the thickness of the second semiconductor layer is such that the majority carrier is expanded.
3. The method according to claim 1, wherein the thickness is thinner than the length.
Semiconductor laser. 4. An n-type clad layer, an active layer and a p-type
After sequentially forming the mold cladding layer, the current blocking layer and
Step of forming p-type contact layer by MOVPE method
A method of manufacturing a semiconductor laser having
The first semiconductor layer to which impurities are added is
A thin film multilayer structure with a pure semiconductor-free second semiconductor layer,
The forbidden band width of the first semiconductor layer is equal to the second semiconductor layer.
A method for manufacturing a semiconductor laser, wherein the semiconductor laser is larger than a forbidden band width of a body layer . 5. An n-type clad layer, an active layer, and a non-conductive layer on a substrate.
The first semiconductor layer to which a pure substance is added and the impurity is not added.
P-type cladding having a thin film multilayer structure with a second semiconductor layer
After sequentially forming the semiconductor layers, the first semiconductor layer
At a temperature at which the diffusion of the impurity into the second semiconductor layer occurs.
Step of forming lock layer and p-type contact layer
And the forbidden band width of the first semiconductor layer is the second bandgap.
A method for manufacturing a semiconductor laser, which is larger than a forbidden band width of a semiconductor layer .