JP2000353862A - Manufacture of semiconductor laminated structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a semiconductor laminated structure, in which light rays having a plurality of emission wavelengths are oscillated from the same quantum well layer, and a method for manufacturing the structure. SOLUTION: A semiconductor laminated structure A2 has a layered structure L, in which a quantum well structure 4 is arranged between a lower light confining layer 3a and an upper light confining layer 3b and at least part of the structure 4 becomes a light emitting region B2 which emits a light having a wavelength shorter than that of the other parts. The structure A2 is manufactured by successively growing a lower clad layer 2, the lower light confining layer 3a, the quantum well structure 4, the upper light confining layer 3b, and a first-conductive first semiconductor layer 5 on a semiconductor substrate 1 by the epitaxial crystal growth method, and then an opposite-conductivity second semiconductor layer 6 is laminated upon the entire or partial surface of the first semiconductor layer 5. The second semiconductor layer 6 may be removed after lamination.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laminated structure used for a semiconductor light emitting device and a method of manufacturing the same, and more particularly, to integration of active devices such as semiconductor lasers and photodiodes, and integration of such active devices and optical waveguides. The present invention relates to a novel semiconductor laminated structure capable of realizing the above and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIG. 19 shows an example A0 of a laminated structure used in a semiconductor laser device. In the case of the laminated structure A0 in this semiconductor laser device, a 500 nm thick lower cladding layer made of Se-doped n-type InP (carrier concentration 1 × 10 ¹⁸ cm ⁻³ ) is formed on a substrate 1 made of n-type InP by MOCVD. 2 and a GaInAsP (λ
g = 1.1 μm) and a lower optical confinement layer 3a having a thickness of 40 nm and a thickness 1 comprising GaInAsP (strain: + 1%).
A strained multiple quantum well structure 4 composed of a 0 nm well layer and a 10 nm thick barrier layer composed of GaInAsP (λg = 1.1 μm), and a 40 nm thick upper optical confinement layer 3 b composed of GaInAsP (λg = 1.1 μm). The layers L are sequentially stacked to form a layer structure L, and Zn-doped p-type InP (carrier concentration 1 × 10 ¹⁸ cm ⁻³ ) is formed on the upper optical confinement layer 3a.
It has a laminated structure in which an upper clad layer 5 having a thickness of 2000 nm and made of GaAs is laminated.

[0003] On the upper cladding layer 5, Z
A 300 nm-thick contact layer (not shown) made of n-doped p-type GaInAs is laminated, and a predetermined photolithography and etching process is performed thereon to form, for example, a ridge waveguide, and then an upper electrode (not shown) is formed thereon. A lower electrode (not shown) is formed on the back surface of the substrate 1 to form a semiconductor laser device.

In the case of this semiconductor laser device, a laminated structure A
When 0 adopts the above-described embodiment, the emission wavelength from the quantum well 4 becomes 1300 nm. By the way, in order to enhance the functions and integration of a semiconductor light emitting device, it is common to integrate semiconductor layer structures having various emission wavelength characteristics on the same semiconductor substrate. In this case, for example, a slab-like layer structure such as the laminate structure A0 shown in FIG. 19 is once formed, and a part of the laminate structure is removed by etching to the lower cladding layer 2 so that the laminate structure A0 having an emission wavelength of 1300 nm is obtained.
Is partially left, and then another semiconductor material is re-grown in the portion removed by etching to form a layer structure showing another emission wavelength.

A method of forming a crystal preventing mask made of, for example, SiNx in a predetermined pattern on the surface of the above-mentioned laminated structure exhibiting a certain light emitting characteristic, and selectively growing another semiconductor material on the non-mask surface. Has also been adopted. Thus, in the conventional semiconductor laser device,
Even when a monolithic stacked structure with different light emission characteristics is integrated on the same substrate, the quantum well structure present there is a quantum well structure exhibiting one light emission characteristic and a different quantum well exhibiting another light emission characteristic The structure is a composite of a plurality of structures provided side by side, and is not a single quantum well structure.

[0006]

SUMMARY OF THE INVENTION The present invention is different from the conventional semiconductor multilayer structure in which a plurality of quantum well structures realize different light emission characteristics even if a single quantum well structure is used. It is an object of the present invention to provide a novel laminated structure for a semiconductor light emitting device that can obtain different light emitting characteristics.

[0007]

Means for Solving the Problems By the way, the present inventors have found that the laminated structure A0 shown in FIG.
A Se-doped n-type InP layer was further laminated on the entire upper cladding layer 5 made of nm-type p-type InP, and the photoluminescence (PL) of the layer structure L in the laminated structure was measured.

As a result, the emission wavelength from the quantum well structure 4 has shifted to the shorter wavelength side. Specifically, when the carrier concentration of the Se-doped n-type InP layer was 1 × 10 ¹⁸ cm ⁻³ and the thickness was 1000 nm, the emission wavelength from the quantum well structure 4 was 1250 nm. The photoluminescence (PL) was also measured for the layer in which the Se-doped n-type InP layer once laminated was removed by etching and returned to the laminated structure shown in FIG. 19 again. 1250 nm without returning to 1300 nm
nm.

Further, Z located immediately above the quantum well structure 4
It was also found that, even if the thickness of the n-doped p-type InP layer was changed or the carrier concentration was changed, the emission wavelength from the quantum well structure 4 was shifted to the shorter wavelength side. Furthermore, after the above-mentioned Se-doped n-type InP layer was formed, if the heating state was continued at the film formation temperature for about 30 minutes, the shift amount of the emission wavelength from the quantum well structure 4 to the shorter wavelength side increased.

The following is a summary of such experimental results. (1) In the stacked structure A0 shown in FIG.
When the n-type InP layer is stacked on the layer 5, the emission wavelength from the portion of the quantum well structure located immediately below the n-type InP layer is shifted to a shorter wavelength side, although the reason is not clear. (2) The above-mentioned phenomenon appears even after the removal of the n-type InP layer. That is, once the n-type InP layer is laminated on the p-type InP layer, whether the n-type InP layer is present or absent is present.
The portion of the quantum well structure located immediately below the layer is converted to a shorter wavelength emission region compared to the other portions.

(3) The shift amount of the emission wavelength to the short wavelength side is:
It changes depending on the thickness and carrier concentration of the p-type InP layer stacked on the quantum well structure. (4) When an n-type InP layer is formed on the p-type InP layer and heating is continued at the film formation temperature, the shorter wavelength side of the emission wavelength from the quantum well structure located immediately below the n-type InP layer. The shift amount to is promoted.

The present inventors have the following idea based on the above-mentioned new findings. That is, in the stacked structure A0 shown in FIG. 19, if the position where the n-type InP layer is stacked on the p-type InP layer is changed, the portion of the quantum well structure located immediately below the stacked position will have a short wavelength light emitting region. In other words, the portion other than the layered portion remains in the region where light is emitted at the design wavelength of the quantum well structure, so that the same quantum well structure can eventually be planarized into a plurality of types of emission wavelength regions. It is to become.

The present inventors have conducted various further studies on the basis of the above findings (1) to (4) and the above-mentioned idea based on the findings, and as a result, have found that the production of the semiconductor multilayer structure of the present invention has been completed. A method has been developed. That is, in the present invention, a layer structure having a quantum well structure is formed on a semiconductor substrate by an epitaxial crystal growth method, and a first semiconductor layer having at least a first conductivity type is stacked near the layer structure. Further, a second semiconductor layer having a conductivity type opposite to that of the first semiconductor layer is stacked on the entire surface or a partial surface of the first semiconductor layer, and at least a part of the quantum well is shorter than other parts. A method for producing a semiconductor laminated structure characterized by being in a wavelength emission region, and after laminating the second semiconductor layer, removing the second semiconductor layer or after forming the second semiconductor layer. And a method of manufacturing a semiconductor multilayer structure in which heating is continued at the film forming temperature.

Specifically, the layer structure includes a lower cladding layer and a quantum well structure, and the semiconductor substrate is an n-type I
A method for manufacturing a semiconductor multilayer structure comprising nP, the lower cladding layer comprising n-type InP, the first semiconductor layer comprising Zn-doped p-type InP, and the second semiconductor layer comprising n-type InP. You.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example A1 of a basic laminated structure of the present invention. This laminated structure A1 is a semiconductor substrate 1
A lower cladding layer 2 is laminated on the lower cladding layer 2 by, for example, the MOCVD method. On the lower cladding layer 2, a lower light confinement layer 3a and a quantum well designed to emit light at a specific wavelength (λ ₀ ) are formed. Structure 4, upper optical confinement layer 3b
Are sequentially stacked to form a layer structure L, and a first semiconductor layer 5 made of an n-type or p-type semiconductor is formed as an upper cladding layer on the upper light confinement layer 3b of the layer structure L, and It has a structure in which a second semiconductor layer 6 made of a semiconductor having a conductivity type opposite to that of the semiconductor of the first semiconductor layer 5 is sequentially stacked.

In this case, for example, if an n-type semiconductor substrate is used as the substrate 1, the lower cladding layer 2 is also formed of an n-type semiconductor, and the first semiconductor layer 5 is formed of a p-type semiconductor.
The second semiconductor layer 6 is formed of an n-type semiconductor. Substrate 1
When a p-type semiconductor is used as the
Is formed as p-type, the first semiconductor layer 5 is formed as n-type, and the second semiconductor layer 6 is formed as p-type.

As the laminated structure A1, an n-type InP substrate is used as the substrate 1, a lower cladding layer 2 made of n-type InP, a lower light confinement layer 3a made of i-type GaInAsP, a quantum well structure 4, i-type GaInAsP
It is preferable to have a stacked structure of an upper optical confinement layer 3b made of GaAs, an upper clad layer (first semiconductor layer) made of p-type InP, and a second semiconductor layer 6 made of n-type InP.

In the laminated structure A1, since the second semiconductor layer 6 is laminated on the entire upper surface of the quantum well structure 4, the energy band of the quantum well structure 4 is shifted to the higher energy side in all parts. The quantum well structure has a short-wavelength light-emitting region in which all portions emit light having a wavelength shorter than the design wavelength λ ₀ . Then, even if the second semiconductor layer 6 is removed from the laminated structure A1, the quantum well structure 4 still remains as a short wavelength light emitting region.

Further, even when the carrier concentration of the first semiconductor layer 5 is increased, the emission wavelength from the quantum well structure 4 shifts to the shorter wavelength side. Further, even if the carrier concentration of the second semiconductor layer 6 is increased, the shift amount can be increased. Note that the laminated structure A1 shown in FIG.
The first semiconductor layer 5 is made of p-type InP,
Assuming that the semiconductor layer 6 is made of n-type InP, the space between the quantum well structure 4 and the p-type InP layer 5 or between the p-type InP layer 5 and n-InP
Similar effects can be obtained by interposing a thin GaInAsP layer between the P layers 6.

The dopant used when forming the first semiconductor layer 5 and the second semiconductor layer 6 is Se or p for n-type.
It is preferable to use Zn for the mold, but using other dopants does not cause any inconvenience. FIG. 2 shows another laminated structure A2 of the present invention. In manufacturing the laminated structure A2, first, the laminated structure A0 shown in FIG. 19 is formed. Then, a growth prevention mask 7 made of, for example, SiNx is formed on a part of the surface of the upper cladding layer (first semiconductor layer) 5 in a desired pattern, and then the second semiconductor layer 6 is selected on the non-mask surface of the upper cladding layer 5. Let it grow.

In the case of this laminated structure A 2, an emission wavelength of the design wavelength (λ ₀ ) is obtained from the portion B 1 of the quantum well structure located immediately below the growth preventing mask 7, while the emission wavelength is directly below the second semiconductor layer 6. The located portion B2 of the quantum well structure is a short-wavelength light-emitting region, from which a light-emitting wavelength shorter than the design wavelength (λ ₀ ) can be obtained. That is, in the laminated structure A2, two different emission wavelengths can be obtained from the same quantum well structure 4.

In the case of the laminated structure A2, similarly to the case of the above-mentioned laminated structure A1, even if the second semiconductor layer 6 is removed, the portion located immediately below the second semiconductor layer 6 B2 still functions as a short wavelength light emitting region. FIG. 3 shows still another laminated structure A3 of the present invention. In manufacturing the laminated structure A3, first, FIG.
The laminated structure A0 indicated by No. 9 is formed. After forming an etching prevention film (not shown) on a part of the surface of the upper clad layer (first semiconductor layer) 5, the upper clad layer 5 in a non-film-formed portion is removed by etching in the thickness direction to leave a thickness t. Let me know. Next, the etching prevention film is removed, and the second semiconductor layer 6 is laminated on the entire surface of the upper clad layer 5 having the step structure.

In the case of the laminated structure A3, the portion B2 of the quantum well structure located immediately below the portion of the first semiconductor layer 5 which has not been removed by etching becomes a short-wavelength light emitting region, and the portion shown in FIG. The same emission wavelength as in B2 is obtained. A portion B3 of the quantum well structure which is partially removed by etching in the thickness direction to have a thickness t and which is located immediately below the portion of the first semiconductor layer on which the second semiconductor layer is directly laminated is also short. It has been converted to a wavelength emission region.
In the case of the laminated structure A3, by changing the thickness t, the emission wavelength from the portion B3 of the quantum well structure changes.

In the case of the laminated structure A3, as in the case of the laminated structure A1 and the laminated structure A2, even if the second semiconductor layer 6 is removed, the portion B of the quantum well structure 4 is removed.
2 and B3 still function as a short-wavelength light emitting region as described above. As described above, in the stacked structure of the present invention, by changing the position where the second semiconductor layer is stacked on the first semiconductor layer or by changing the thickness of the first semiconductor layer, the same quantum well structure differs from the same quantum well structure. Different emission wavelengths can be obtained.

The manufacture of, for example, a semiconductor laser device using the above-described laminated structure is performed as follows. This will be described using the laminated structure A1 as an example. First, the laminated structure A
First, the entire surface of the p-type first semiconductor layer 5 is exposed by removing all the second semiconductor layer (n-type) 6 by etching. Next, an n-type semiconductor layer is formed on a surface portion other than the position where the upper electrode is to be formed to form a current blocking layer, and then a p-type semiconductor is formed at a position where the upper electrode is to be formed to form a contact layer. Form. Finally, an upper electrode (p-type electrode) is formed on the contact layer, and a lower electrode (n-type electrode) is formed on the back surface of the substrate 1.

In this semiconductor laser device, since the entire region of the quantum well structure 4 has already been converted into the short wavelength light emitting region, the design wavelength (from the quantum well structure located immediately below the upper electrode) is obtained. λ ₀ ) can oscillate laser light having a shorter wavelength. Further, by using this laminated structure, a SAS type semiconductor laser device can be manufactured as follows.

First, for example, on an n-type InP substrate, FIG.
The layer structure up to the p-type first semiconductor layer 5 is formed. Next, as shown in FIG. 4, for example, in the surface of the first semiconductor layer 5 where a current injection region is to be formed, S
A stripe mask 7 made of iNx for crystal growth prevention is formed, and Se-doped n-type InP
Is selectively selected to form the second semiconductor layer 6.

Then, the stripe mask 7 is removed and the first
After the semiconductor layer (p-type) 5 is exposed, an upper cladding layer made of, for example, p-type InP, for example, p-type GaI
A contact layer made of nAs is sequentially formed (FIG. 5).
Finally, an upper electrode (p-type electrode) is formed on the contact layer, and a lower electrode (n-type electrode) is formed on the back surface of the substrate 1.
To form

In this semiconductor laser device, the second semiconductor layer 6 itself functions as a current blocking layer,
The portion of the quantum well structure 4 located immediately below is a short wavelength light emitting region. Therefore, the portion of the quantum well structure has a low refractive index, and therefore, the portion of the quantum well structure 4 located immediately below the current injection region exerts the effect of confining the injected current and light in the lateral direction. . As a result, this semiconductor laser device exhibits excellent laser characteristics such as a reduction in oscillation threshold value and an increase in kink generation current.

In the semiconductor laser device, when the second semiconductor layer is formed to a desired film thickness and then continuously heated by the film formation temperature, a position immediately below the second semiconductor layer can be obtained. Since the amount of shift to the short wavelength side in the portion of the quantum well structure to be performed can be increased, that is, the refractive index can be further reduced, the above-described effect is more remarkably exhibited.

In other words, conversely, even if the thickness of the second semiconductor layer (current blocking layer) is reduced, the above-described effect of confining the injection current and light in the lateral direction can be effectively realized. It is possible. By the way, in the case of the conventional semiconductor laser device, it is necessary to make the current blocking film sufficiently thick in order to exert the above-described lateral confinement effect. However, as the thickness of the current blocking layer is increased, defects and deterioration in surface morphology of the upper clad layer are liable to occur in the subsequent film formation process, especially in the film formation process of the upper clad layer, and the produced semiconductor laser device The reliability may be reduced. Conversely, when the thickness of the current blocking layer is reduced, the kink generation current of the manufactured semiconductor laser device is reduced.

In the case of the above-described semiconductor laser device of the present invention, when the second semiconductor layer, which is the current blocking layer, is formed, the heating at the film forming temperature is continued even if the film thickness is reduced. Since a lateral confinement effect can be exerted, it is not necessary to form a thick current blocking layer as in the related art. That is to reduce the amount of expensive organometallic raw materials used, which also lowers the manufacturing cost of the device.

[0033]

EXAMPLE 1 A laminated structure A1 was formed by MOCVD as follows.
Done. On the n-type InP substrate 1, Se-doped n-type InP
P (carrier concentration 1 × 10¹⁸cm ^-3500)
nm lower cladding layer 2, and an i-type Ga
40 nm thick InAsP (λg = 1.1 μm)
Lower light confinement layer 3a, GaInAsP (strain: + 1%)
And a 10 nm-thick well layer of GaInAsP (λg =
1.1 μm) and a barrier layer having a thickness of 10 nm.
Emission wavelength (λ₀) Is designed to be 1300nm
Strained multiple quantum well structure 4, i-type GaInAsP (λg
= 1.1 μm) and an upper optical confinement layer with a thickness of 40 nm
3b are sequentially laminated to form a layer structure L,
Zn-doped p-type InP (carrier concentration)
Degree 5 × 10¹⁷cm^-3) Upper cladding layer (first semiconductor)
19) to form a layer structure A0 shown in FIG.
Was. Further, a Se-doped n-type InP (carrier
1 × 10¹⁸cm^-3) Second semiconductor having a thickness of 1000 nm
Layer 6 was deposited.

The photoluminescence (PL) of the laminated structure A1 was measured. The emission wavelength from the quantum well structure 4 was 1250 nm, which was shifted by 50 nm shorter than the design wavelength. Further, the emission wavelength of the laminated structure after removing the Se-doped n-type InP layer 6 by etching was not changed to 1250 nm.

Example 2 A laminated structure A2 was manufactured by the MOCVD method as follows. The layer structure A0 shown in FIG. 19 was formed in the same manner as in Example 1. Next, after forming a growth preventing mask 7 by forming a film of SiNx on a half of the surface of the p-type InP layer 5 by a plasma CVD method, Se-doped n-type InP (carrier concentration) is formed on the non-mask surface in the same manner as in the first embodiment. 1 × 10 ¹⁸
cm ^-3) was a film of the second semiconductor layer 6 having a thickness of 1000nm to form a laminated structure A2 consisting of.

When the laminated structure A2 was measured by the photoluminescence method, the emission wavelength from the portion B1 of the quantum well structure located immediately below the growth preventing mask 7 was 1300 nm.
The emission wavelength from the portion B2 of the quantum well structure located immediately below the second semiconductor layer 6 was 1250 nm, and this portion B2 became a short-wavelength emission region. That is, in the case of this laminated structure B2, two kinds of emission wavelengths could be obtained from one quantum well structure 4. Note that Se-doped n-type In
Photoluminescence was also measured on the laminated structure after the P layer 6 was removed by etching, and the emission wavelength from the portion B2 of the quantum well 4 was unchanged at 1250 nm.

Example 3 A laminated structure A3 was manufactured by MOCVD as follows. First, the laminated structure A0 shown in FIG. 19 was formed in the same manner as in Example 1. Then, Zn-doped p-type In
An etching prevention film was formed on a part of the surface of the P layer 5, and an etching process was performed on a non-film-forming portion. At this time, by changing the etching time, the etching depth of the non-film-forming portion was changed, and the remaining thickness t was variously changed.

Thereafter, the Se-doped n-type InP layer 5 is formed on the entire surface of the Zn-doped p-type InP layer 5 in the same manner as in the first embodiment.
(Carrier concentration: 1 × 10 ¹⁸ cm ⁻³ ) Thickness 1000
A second semiconductor layer 6 having a thickness of nm was formed to form a laminated structure A3. Portion B3 of the quantum well structure in the laminated structure A3
The emission wavelength from was measured by the photoluminescence method.
FIG. 6 shows the relationship between the result and the thickness t of the Zn-doped p-type InP layer.

As is apparent from FIG. 6, as the thickness of the Zn-doped p-type InP layer decreases, the emission wavelength from the portion B3 of the quantum well structure 4 shifts to shorter wavelengths. Further, the effect becomes smaller as the thickness becomes thinner. This means
When etching the Zn-doped p-type InP layer,
This shows that by controlling the etching depth, it is possible to appropriately control the length of the emission wavelength from the quantum well structure immediately below the portion removed by etching.

Embodiment 4 As shown in FIG. 7, a 500 nm thick lower cladding layer 2 made of Se-doped n-type InP (carrier concentration 1 × 10 ¹⁸ cm ⁻³ ) is laminated on an n-type InP substrate 1. On top of this, a lower optical confinement layer 3a made of i-type GaInAsP (λg = 1.1 μm) and having a thickness of 40 nm, GaInAsP (strain:
+ 1%) and a 10 nm thick well layer and GaInAsP
(Λg = 1.1 μm), a strained multiple quantum well structure 4, i-type GaInAsP (λg) composed of a barrier layer having a thickness of 10 nm and designed to emit light at a wavelength of 1340 nm.
= 1.1 μm) and a 40 nm-thick upper optical confinement layer 3b is sequentially laminated to form a layer structure L, on which a Zn-doped p-type InP (carrier concentration of 5 × 10 ¹⁷ cm ⁻³ ) having a thickness of 10 nm is formed. Of the upper cladding layer (first semiconductor layer) 5a.

Next, as shown in FIG. 8, masks 7, 7 each having a width of Wm and an interval of Wg are formed on the surface of the upper cladding layer 5a with SiNx.
Type InP (carrier concentration 5 × 10 ¹⁷ cm ⁻³ ) is selectively grown, and subsequently Se-doped n-InP (carrier concentration 1
× 10 ¹⁸ cm ^-3 ) was selectively grown to form the laminated structure shown in FIG. As a result, an upper cladding layer 5b having a thickness of 40 nm and a second semiconductor layer 6 having a thickness of 300 nm were formed on the upper cladding layer 5a exposed between the masks 7,7.

At this time, the interval Wg between the masks 7, 7 is 15
μm and the width Wm of the mask is 50 μm, 10 μm
Was formed, and the photoluminescence thereof was measured. The results are shown in FIG. As is apparent from FIG. 10, the pattern of the mask was changed to Wm1
When 0 μm and Wg 15 μm are used, the Se-doped n-type InP
The emission wavelength from the portion B4 of the quantum well structure located immediately below the layer 6 shifts to a shorter wavelength side than the design wavelength, and
nm, and when Wm is 50 μm and Wg is 15 μm, the wavelength is further shifted to the shorter wavelength side to 1280 nm.

That is, by forming the first semiconductor layer and the second semiconductor layer by selective growth while controlling the dimensions of the mask pattern, the wavelength of light emitted from the quantum well located immediately below the first semiconductor layer and the second semiconductor layer can be controlled. In the laminated structure shown in FIG. 9, the emission wavelength from the portion B4 did not change even after the Se-doped n-type InP layer 6 was removed by etching.

Embodiment 5 An S in which the laminated structure of the present invention is incorporated as follows.
An AS type semiconductor laser device was manufactured by applying the MOCVD method. First, as shown in FIG.
On top of Se-doped n-type InP (carrier concentration 1 × 10
¹⁸ cm ^-3 ) of the lower cladding layer 2 having a thickness of 500 nm, and an i-type GaInAsP (λg = 1.1 μm) is formed thereon.
m), the lower optical confinement layer 3a of 40 nm, GaIn
A 10 nm thick well layer made of AsP (strain: + 1%) and G
a 10 nm thick made of aInAsP (λg = 1.1 μm)
Strained multiple quantum well structure 4, i-type GaInAs designed to have an emission wavelength of 1300 nm
An upper optical confinement layer 3b of P (λ = 1.1 μm) having a thickness of 40 nm is sequentially laminated to form a layer structure L, on which Zn-doped p-type InP (carrier concentration: 5 × 10 ¹⁷ cm ⁻³ ).
After laminating an upper cladding layer (first semiconductor layer) 5a of 100 nm in thickness, a 5 μm-wide stripe mask 7 of SiNx was formed on the upper cladding layer 5a.

Then, Se-doped n-type InP (carrier concentration 1 × 10 ¹⁸ c) is formed on the non-mask surface of the upper cladding layer 5a.
A current blocking layer (second semiconductor layer) 6 of m- ³ ) having a thickness of 300 nm was formed (FIG. 12). After removing the stripe mask 7, a Zn-doped p-type InP
(Carrier concentration 1 × 10 ¹⁸ cm ^-3 ) thickness 2000
nm upper cladding layer 5b and Zn-doped p-type GaInAs
The contact layer 8 made of was sequentially formed (FIG. 13).

Finally, an upper electrode (not shown) is formed on the contact layer 8, and a lower electrode (not shown) is formed on the back surface of the n-type InP substrate 1. The device was manufactured. This SA
In the case of the S-type semiconductor laser device, the portions on both sides located directly below the second semiconductor layer 6 in the quantum well structure 4 are located at the center located immediately below the second semiconductor layer stacked on the portion where the stripe mask is formed. The band gap is larger than that of the portion, and accordingly, the refractive index is low.

Therefore, in the case of the SAS type semiconductor laser device having this structure, the conventional semiconductor laser device is capable of guiding the refractive index while the conventional device is of the gain waveguide type. Therefore, the SAS type semiconductor laser device having this structure has an advantage that the kink current level at the time of high output is also high. At the time of manufacturing the above-described laser element, the first semiconductor layer 5a is formed to a thickness of 500 nm at a growth temperature of 650 ° C.
After film formation, heating was continued at the same temperature (650 ° C.), and thereafter, a semiconductor laser device was manufactured in the same manner as in Example 5.

At this time, the heating time for the first semiconductor layer 5a after the film formation was changed. For each of the obtained laser devices, the amount of shift of the emission energy in the portion of the quantum well structure located immediately below the first semiconductor layer 5a was measured. The result is shown in FIG. 14 as a relationship diagram with the heating duration. As is clear from FIG. 14, after the first semiconductor layer (current blocking layer) 5a is formed, if the heating is further continued at the film formation temperature at that time, the quantum well structure located immediately below the first semiconductor layer 5a is formed. The amount of energy shift in the portion of FIG. When heating is continued for 30 minutes or more, the shift amount becomes about 100 meV. This shift amount is
This is a value that exhibits the same lateral confinement effect as when a 2000 nm thick current blocking layer is formed of n-type InP.

Example 6 A multi-wavelength semiconductor laser device was manufactured as follows. First, as shown in FIG. 7, on the n-type InP substrate 1, S
A 500 nm-thick lower cladding layer 2 made of e-doped n-type InP (carrier concentration 1 × 10 ¹⁸ cm ⁻³ ) is laminated, and a 40 nm-thick lower optical confinement made of i-type GaInAsP (λg = 1.1 μm) is formed thereon. Layer 3a, GaInAsP
(Strain: + 1%) and a 10 nm-thick well layer and GaIn
A strained multiple quantum well structure 4, i-type GaInAsP (λ) composed of a 10 nm-thick barrier layer made of AsP (λg = 1.1 μm) and designed to have an emission wavelength of 1340 nm.
g = 1.1 μm) and a 40 nm-thick upper optical confinement layer 3b is sequentially laminated to form a layer structure L, on which Zn
An upper cladding layer 5a made of doped p-type InP (carrier concentration 5 × 10 ¹⁷ cm ⁻³ ) with a thickness of 10 nm was laminated.

Then, as shown in FIG. 8, on the upper cladding layer 5a, the interval Wg is 15 μm, and the width Wm is 10 to 10.
The pattern of the mask 7 for selective growth of 50 μm is
A film was formed with Nx. Then, a thickness 3 of Zn-doped p-type InP (carrier concentration 5 × 10 ¹⁷ cm ⁻³ ) is formed thereon.
0 nm upper cladding layer 5b, GaInAsP (λg =
1.2 μm) etching stop layer 1 having a thickness of 5 nm
0, Se-doped n-type InP (carrier concentration 1 × 10 ¹⁸ cm
³ ) The layer (second semiconductor layer) 6 having a thickness of 300 nm composed of ³ ) was sequentially and selectively grown to form a laminated structure as shown in FIG.

At this point, the portion B2 of the quantum well structure located immediately below the Se-doped n-type InP layer 6 has been converted to a short wavelength light emitting region. Then, Se-doped n-type InP
After the layer 6, the etching stop layer 10, and the selective growth mask 7 are removed by etching, respectively, a stripe mask having a width of 4 μm is formed on the exposed central portion of the surface of the Zn-doped p-type InP layer 5b as shown in FIG. 7 ′ was formed with SiNx. Then, etching was performed on the entire structure up to the lower clad layer 2 to form the mesa structure shown in FIG.

Next, both sides of the mesa structure are sequentially buried with a Zn-doped p-type InP layer 9a and a Se-doped n-type InP layer 9b to form a current blocking layer 9, and then the stripe mask 7 'is removed. Of Zn-doped p-type InP (carrier concentration 1 × 10 ¹⁸ cm ⁻³ ) 2
000 nm upper cladding layer 5c, Zn-doped p-type GaAs
The contact layers 8 made of 1As were sequentially laminated (FIG. 1).
8).

Finally, an upper electrode was formed on the contact layer 8, and a lower electrode was formed on the back surface of the substrate 1 to obtain a target semiconductor laser device. In the case of this laser device, for example, the width of the selective growth mask 7 in FIG.
If it is set to 0 μm, the emission wavelength becomes 1295 nm as apparent from FIG. 10, and if the mask width is set to 50 μm, the emission wavelength becomes 1280 nm. Then, set the mask width to 10
If it is set to an appropriate value between 50 μm, the emission wavelength at that time will be an appropriate value in the middle of the above emission wavelength, and the emission wavelength from the portion of the quantum well structure not affected by the mask 7 will be the design wavelength. (Λ ₀ ) of 1300 nm, and the emission wavelength from the quantum well structure located immediately below the mask is 1
320 nm. That is, this laser element functions as an array having an emission wavelength region from 1290 to 1320 nm on the same substrate.

[0054]

As is clear from the above description, the semiconductor multilayer structure of the present invention can obtain a plurality of emission wavelengths from the same quantum well structure. Therefore, by incorporating this laminated structure, it is possible to integrate portions having various emission wavelengths on the same substrate, and to integrate a semiconductor laser device and an active device such as a photodiode, or to integrate an active device and an optical waveguide. Can be realized and its industrial value is great.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a laminated structure example A1 of the present invention.

FIG. 2 is a sectional view showing another laminated structure A2.

FIG. 3 is a sectional view showing still another laminated structure A3.

FIG. 4 is a cross-sectional view showing a state where a second semiconductor layer is stacked on the first semiconductor layer.

FIG. 5 is a sectional view showing an example of a SAS type semiconductor laser device.

FIG. 6 is a graph showing the relationship between the thickness of a Zn-doped p-type InP layer and the emission wavelength from a quantum well structure.

FIG. 7 is a cross-sectional view showing a state where a semiconductor layer is stacked on a substrate.

FIG. 8 is a cross-sectional view showing a state where a mask for selective growth is formed on the laminated structure of FIG. 7;

FIG. 9 is a cross-sectional view showing a state where an upper cladding layer and a second semiconductor layer are formed.

FIG. 10 is a graph showing a relationship between a width of a selective growth mask and an emission wavelength from a quantum well structure.

FIG. 11 is a cross-sectional view showing a state in which a selective growth mask is formed on a first semiconductor layer in a manufacturing process of the SAS semiconductor laser device.

FIG. 12 is a cross-sectional view showing a state where a current blocking layer is formed.

FIG. 13 is a cross-sectional view showing a state where an upper cladding layer and a contact layer are formed.

FIG. 14 is a graph showing the relationship between the duration of heating after the formation of the first semiconductor layer and the amount of energy shift of the quantum well structure.

FIG. 15 shows a first step in the process of manufacturing the multi-wavelength semiconductor laser device.
FIG. 4 is a cross-sectional view showing a state where a semiconductor layer and a second semiconductor layer are selectively grown.

FIG. 16 is a cross-sectional view showing a state where an etching stop film is formed after removing a second semiconductor layer and a selective growth mask.

FIG. 17 is a cross-sectional view showing a state where a mesa structure is formed.

18 is a cross-sectional view showing a state in which the mesa structure of FIG. 17 is embedded with an upper clad layer and a contact layer.

FIG. 19 is a cross-sectional view showing a state in which a laminated structure including a layer structure L is formed on an n-type InP substrate.

[Explanation of symbols]

Reference Signs List 1 semiconductor substrate (n-type InP) 2 lower cladding layer (Se-doped n-type InP)
Layer 3a Lower optical confinement layer (i-type GaInAsP)
Layer 3b Upper light confinement layer (i-type GaInAsP)
4) quantum well 5, 5a, 5b, 5c first semiconductor layer (Zn-doped p-type InP layer) 6 second semiconductor layer (Se-doped n-type InP layer) 7 mask for selective growth 7 'etching prevention film 8 contact layer Reference Signs List 9 current blocking layer 9a Zn-doped p-type InP layer 9b Se-doped n-type InP layer 10 etching stop layer

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Nobumitsu Yamanaka 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Inventor Akihiko Kasukawa 2-6-1 Marunouchi, Chiyoda-ku, Tokyo F term in Furukawa Electric Co., Ltd. (reference) 5F041 AA12 CA05 CA34 CA53 CA57 CA65 CA74 CB02 CB05 FF16 5F049 MA03 MB07 MB12 PA04 PA14 QA16 RA07 SS04 5F073 AA13 AA45 AA74 CA12 CB02 CB19 DA05 EA04

Claims (4)

[Claims] A layer structure having a quantum well structure is formed on a semiconductor substrate by an epitaxial crystal growth method,
A first semiconductor layer having at least a first conductivity type is laminated near the layer structure, and a second semiconductor of a conductivity type opposite to that of the first semiconductor layer is formed on the entire surface or a partial surface of the first semiconductor layer. A method of manufacturing a semiconductor multilayer structure, comprising stacking layers so that at least a part of the quantum well structure has a shorter wavelength light emission region than other parts. 2. The method according to claim 1, further comprising removing the second semiconductor layer after stacking the second semiconductor layer. 3. The method according to claim 1, wherein after the second semiconductor layer is formed, heating at the film formation temperature is continued. 4. The semiconductor device according to claim 1, wherein the layer structure includes a lower cladding layer and a quantum well structure, the semiconductor substrate is made of n-type InP, the lower cladding layer is made of n-type InP, and the first semiconductor layer is Zn-doped p-type. 4. The method according to claim 1, wherein the second semiconductor layer is made of n-type InP, and the second semiconductor layer is made of n-type InP.