JP2914256B2 - Semiconductor heterostructure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor heterostructure used for a semiconductor device.

[0002]

2. Description of the Related Art In a semiconductor laser having a quantum well structure as an active layer, an oscillation wavelength changes due to a quantum effect, and a gain spectrum becomes steep. It is possible to improve characteristics such as speeding up, and it is used as a high performance light source in, for example, an optical disk or optical communication.

Further, in order to enhance the confinement of light,
Separate confinement heterostructure that separates light and carriers (light is in the waveguide layer and carrier is in the quantum well layer)
By adopting the (SCH) structure, the characteristics of the semiconductor laser have been greatly improved.

Generally, a semiconductor mixed crystal layer containing two kinds of V-groups, such as InGaAsP, which can freely change the band gap, is used as an optical confinement layer of a semiconductor laser used in optical communication, optical measurement, and the like. .

Further, a semiconductor mixed crystal layer containing two kinds of VI group such as ZnCdSSe is also used as a light confinement layer of a II-VI group semiconductor laser expected as a light source for a next-generation optical disk. Thus, two kinds of V-groups or
The crystal growth of the semiconductor mixed crystal itself including group VI is important in application to a semiconductor light emitting device such as a semiconductor laser.

[0006] These semiconductor lasers are mainly
(Molecular beam epitaxy) method, gas source MBE method, M
It is manufactured using a vapor phase growth method such as an OVPE (organic metal vapor phase epitaxy) method.

However, generally, the V-group and VI-group raw materials have a high vapor pressure, and it is difficult to precisely control the supply amounts of the V-group and VI-group raw materials in these growth methods.

For example, when a group V element is supplied into a growth chamber of an MBE growth apparatus or the like, the pressure of the group V in the growth chamber is significantly increased, and remains in the growth chamber even after the supply is stopped to form a background pressure. I do. When the background pressure is high, group V atoms supplied from the background to the substrate surface cannot be ignored.

Therefore, in order to grow a semiconductor layer having a steep hetero interface having a different Group V composition, it is necessary to sufficiently reduce the residual Group V pressure at the hetero interface.

On the other hand, the gas source MBE method uses AsH ₃ which is a hydride of As and P instead of the solid raw material of As and P.
Or PH ₃ or the like is used, so that it is possible to control the flow rate of the group V raw material having relatively high response.

However, the group V atoms and the group V gas source remain in the growth chamber to form the background pressure.

The characteristics of an optical device using a quantum effect such as a semiconductor laser having a quantum well structure are greatly affected by the quality of the interface. This is an important technique for manufacturing.

For example, Reference ⁽¹⁾ (Autumn 1992, 53rd
Proceedings of the JSCE Lectures, p. 245,
17p-ZF-13, “GSMBE grown InGaAs /
Precise control of InP heterointerface ”) includes InGaAs /
When growing an InP heterostructure, InGaAs is formed at the interface.
If P is supplied to the surface and waiting, InGaP is formed at the interface and the surface becomes rough. To prevent this, after inserting one In atomic layer at the interface, supply P and wait for a few seconds. It has been reported that a steep heterointerface can be obtained by growing InP.

The fact that the switching is performed with the In atomic layer surface taken out indicates that the residual group V pressure can be sufficiently reduced. Furthermore, the P is supplied for several seconds until the supply of P starts.
This is because the In atomic layer functions to protect the InGaAs layer from the P irradiation during the irradiation standby time.

In recent years, many semiconductor lasers use a strained quantum well structure. The use of the strained quantum well structure enhances the confinement of electrons in the quantum well layer and reduces the mass of the holes, so that the holes are uniformly injected into the multiple quantum well (MQW) layer. Therefore, a semiconductor laser having a long wavelength, a high output, and a low threshold can be realized.

In order to improve the characteristics of a semiconductor laser, a semiconductor laser having a highly strained and multiple quantum well structure is expected. As a result, the strain amount of the strained quantum well layer increases to just before the critical film thickness. doing.

As III-V semiconductor lasers, for example, reference ⁽²⁾ (RU Martinelli et al., “Temperature depende”
nce of 2μm strained-quantum-well InGaAs / InGaAsP / I
nP diode lasers ", ELECTRONICS LETTERS (Electronic Letters Magazine), Vol. 30, No. 4, 324
P. 1994) describes an InGaAs well / InGa with an oscillation wavelength of 2 μm manufactured using the MOVPE method.
Characteristics of a semiconductor laser having an AsP barrier / InP cladding structure have been reported. In the InGaAs well layer of this semiconductor laser diode (hereinafter referred to as “LD”),
Strong compressive strain of 1.5% is applied.

As II-VI group semiconductor lasers, for example, reference ⁽³⁾ (Satoshi Itoh et al., “ZnCdSe / ZnSSe / Zn
MgSSe SCH Laser Diode with a GaAs Buffer Layer ”,
Japanese Journal of Applied Physics, Vol. 33, 7
No. A, pages L938-L940, 1994).
9 nm ZnCdSe well / ZnSSe barrier / Z
Room temperature continuous oscillation of an LD having an nMgSSe clad structure has been reported. In the ZnCdSe well layer of this LD,
Strong compressive strain of 1.5 to 2% is applied.

As described above, an optical device having a highly strained heterostructure is expected, but there is an upper limit to the critical film thickness that can be grown while maintaining the quality of the strained layer.

[0020]

SUMMARY OF THE INVENTION The present invention relates to a non-strained semiconductor layer, a strained semiconductor layer, and an InGa having a stable group V composition, as will be more apparent from the following description.
A semiconductor layer containing two or more group V atoms such as AsP or a semiconductor layer containing two or more group VI atoms such as a ZnCdSSe layer having a stable group VI composition has a good crystal quality. It is an object of the present invention to provide a semiconductor light emitting device having the same.

For example, specifically, it is to improve the crystal quality of a semiconductor heterostructure including a semiconductor layer having two or more V group compositions, such as a heterointerface between a strained InGaAs well layer and an InGaAsP barrier layer.

The quaternary mixed crystal of InGaAsP is the V of AsP.
Lattice constants and band gaps vary greatly depending on the composition ratio of group atoms. Also, if there is a lattice mismatch, InGa
The optical crystal quality of AsP bulk is easily degraded.

In particular, when a multiple quantum well structure is grown while the gas phase ratio, which is the ratio of the supply amount of Group V, is not stable during the growth, the interface is roughened and the quality of the quaternary mixed crystal deteriorates remarkably. . For this reason, stable control of the group V composition such as AsP is important.

Actually, when growing an InGaAsP layer containing two kinds of group V atoms of As and P, AsH ₃ or P
It is necessary to control the supply ratio of the H ₃ gaseous raw material with high accuracy.

In the gas source MBE method, in particular, A
Since s is hardly taken in about five times P, the flow rate of AsH ₃ is small, and a high degree of flow controllability is required.

Further, the group V raw material such as N, As, P, and Sb has a high vapor pressure, and even if the cracked group V raw material is introduced into the growth chamber, it takes several tens of minutes to reach the set supply amount. Takes seconds.

Furthermore, depending on the growth apparatus, the rising of the supply amounts of As and P may be significantly different due to a cracking effect of As and P, a difference in vapor pressure, a mutual reaction, and the like. In such a case, it is not rare that it takes about one minute for the group V composition to stabilize.

Therefore, it is necessary to interrupt the growth before the growth of InGaAsP, irradiate AsP, and wait. If the waiting time is not sufficient, the group V composition of InGaAsP grows without being stabilized, so that a metamorphic layer of InGaAsP is formed at the interface.

In the case where the underlying layer is a strained layer, I is particularly affected by the strained layer.
There arises a problem that the quality of the nGaAsP layer is deteriorated and the quality of the strained quantum well structure as the active layer is deteriorated. MOVP
Also in the E method, since a group V raw material having a high vapor pressure remains, it is difficult to grow a semiconductor layer having a steep heterointerface having a different group V composition.

In the MBE method, As group V raw material is As,
Solid raw materials such as P and Sb, and group VI raw materials include S, Se,
A solid material such as Te or a compound material containing them is used. In the MBE method, it is difficult to grow a semiconductor layer having a steep heterointerface having a different group V composition.
Since the vapor pressure is higher than that of the group IV raw material, it is very difficult to grow a semiconductor layer having a steep heterointerface having a different group VI composition.

A II-VI group semiconductor laser manufactured by the MBE method uses a ZnCdS having two or more group VI elements.
Since the Se layer is used for the quantum well active layer, the influence on the characteristics of the laser is large.

Further, since the II-VI group semiconductor material is relatively soft, the strain layer has a great influence on the ZnCdSSe layer. In view of the current control technology of II-VI group material supply, Z
There is room for improvement in the composition stability of Group VI elements in a semiconductor layer containing two or more types of Group VI atoms, such as an nCdSSe layer.

Thus, I having a stable group V composition
It is an important issue to grow a semiconductor layer containing two or more kinds of Group V atoms such as nGaAsP or a semiconductor layer containing two or more kinds of Group VI atoms such as a ZnCdSSe layer having a stable Group VI composition.

InGaAs, a single V-group semiconductor
In order to control the hetero interface between the s layer and the InP layer, in the above-described conventional example, the steepness of the hetero interface is realized by growing one atomic layer of In layer on InGaAs.
Although the In layer of one atomic layer at the interface can withstand the interface standby for several seconds, the layer thickness is too small to withstand the interface standby for several tens of seconds or about one minute before InGaAsP growth.

Accordingly, this method is suitable for growing a semiconductor heterostructure including semiconductor layers having two or more group V compositions.
It cannot be applied as is.

Further, the above conventional example is an example in the case of a semiconductor layer lattice-matched to a substrate.

In growing a strained semiconductor layer and a semiconductor layer containing two or more kinds of group V atoms such as InGaAsP, InG
If the waiting time at the interface is sufficiently long for stabilizing the AsP, not only the interface is roughened by the irradiated AsP,
In the case of a highly strained layer, there is a problem that the strained layer easily becomes a three-dimensional island just by waiting.

Therefore, even if one atomic layer of In is inserted into the surface of the highly strained layer by the above-described conventional method and the growth is suspended, the surface roughness of the strained layer cannot be prevented.

Eventually, In lattice matched with the InP substrate
In the case of a GaAs layer, a steep hetero interface can be obtained by inserting one In atomic layer at the interface. However, in the case of an InGaAsP layer in which the interface standby time is several tens of seconds,
InGaAs not lattice-matched with sP layer and InP substrate
In the case of a layer, in the conventional method, the problem that the heterointerface deteriorates due to the strain-modified layer formed during standby is inevitable.

In order to improve such a hetero interface, the composition of the group V or group VI is stabilized at a set value,
In addition, there is a need for a method for easily optimizing the waiting time for preventing the group V or VI atoms irradiated during the waiting time from being taken in from the surface to form a metamorphic layer. Therefore, the present invention has been made in view of such problems,
Its purpose is as described above.

[0041]

In order to achieve the above object, a semiconductor heterostructure according to the present invention takes a sufficient waiting time immediately before the growth of an InGaAsP layer or a ZnCdSSe layer, and supplies the semiconductor heterostructure to the surface of the grown layer during the waiting time. In order to protect the growth layer surface from the group V or group VI atoms
A semiconductor thin film layer containing one kind of group III atom or group II atom is inserted immediately before the growth of the GaAsP layer or the ZnCdSSe layer.

According to the present invention, there is provided a strain layer and an InGaAsP layer.
Or between the strained layer and the ZnCdSSe layer, the same V group as the strained layer.
Alternatively, it is preferable to insert a lattice matching layer having a group VI composition.
Sign. In addition, a strained layer having a common V or VI composition
The interface between the strain-free layer and the V-group or VI-group composition
It is intended to provide a semiconductor heterostructure characterized in that the semiconductor heterostructure is separated from the interface between the child matching layers .

That is, the present invention relates to a first strained III-V compound semiconductor layer having a lattice constant different from that of a substrate.
An unstrained second semiconductor layer having the same group V composition as the strained semiconductor layer, a third semiconductor layer containing only one type of group III atom,
A semiconductor heterostructure characterized by having a layer structure in which a fourth semiconductor layer containing two or more kinds of group V atoms is epitaxially grown in order.

Further, according to the present invention, there is provided the semiconductor heterostructure according to the first aspect having a lattice constant different from that of the substrate.
As a strained semiconductor layer of a III-V compound, a plurality of strained semiconductor layers having the same group V composition and different amounts of strain are used.

Further, the present invention is characterized in that In is used as the group III atom of the semiconductor layer containing only one type of group III atom in the above-described semiconductor heterostructure.

Further, the present invention provides an unstrained first group II-VI compound semiconductor layer having substantially the same lattice constant as the substrate, and a second layer having a thickness of 1 to 5 molecular layers containing only one kind of group II atom. Provided is a semiconductor heterostructure having a layer structure in which a semiconductor layer and a third semiconductor layer containing two or more kinds of group VI atoms are sequentially epitaxially grown.

The present invention also provides a strained semiconductor layer of a first II-VI compound having a lattice constant different from that of a substrate, and a non-strained second semiconductor layer having the same group VI composition as the first strained semiconductor layer. ,
Provided is a semiconductor heterostructure having a layer structure in which a third semiconductor layer containing only one kind of group II atom and a fourth semiconductor layer containing two or more kinds of group VI atoms are sequentially epitaxially grown. .

Further, according to the present invention, there is provided the semiconductor heterostructure according to the first aspect having a lattice constant different from that of the substrate.
As a strained semiconductor layer of a II-VI compound, a plurality of strained semiconductor layers having the same group VI composition and different strain amounts are used.

[0049]

The principle and operation of the present invention will be described below. InG
The growth is interrupted immediately before the growth of the aAsP layer or the ZnCdSSe layer, and the irradiation and irradiation of AsP or SSe is stopped until the pressure occupying the growth chamber of the AsP or SSe reaches a steady state. InGaAsP layer with stable group V composition or stable VI
A ZnCdSSe layer having a group composition can be grown.

[0050] In the semiconductor heterostructure according to the present invention as defined in claim 4, InGaAsP layer or ZnCdS
Before growing the Se layer, a semiconductor layer having a thickness of 1 to 5 molecular layers containing only Group III or Group II atoms is grown. For example,
As a semiconductor layer containing only group III atoms, InP or InA
s is used, and C is used as a semiconductor layer containing only group II atoms.
dSe or CdS is used.

InGaAsP layer or ZnCdSSe
AsP atoms or SSe atoms supplied to the growth surface during the interface waiting time immediately before the growth of the layer are absorbed by these semiconductor layers, so that an InAsP layer or a CdSSe layer having a thickness of 1 to 5 molecular layers is formed.

The interface waiting time is about 20 seconds to 80 seconds under normal growth conditions, and the group V atoms or group VI atoms supplied to the growth surface during the interface waiting time are II seconds.
In order to prevent the semiconductor layer containing only group I or group II atoms from diffusing into the quantum well layer to form a metamorphic layer, the thickness of the semiconductor layer containing only group III or group II atoms is 1 to 5 molecules. The layer thickness is appropriate.

The semiconductor heterostructure according to the present invention comprises a semiconductor layer in which an InAsP layer or a CdSSe layer having a thickness of 1 to 5 molecular layers is lattice-matched with an InGaAsP layer or a ZnCd layer.
Because of the feature inserted between the SSe layers, the lattice matched semiconductor layer and the InGaAsP layer or ZnCdSS
A high-quality semiconductor heterostructure that does not include a metamorphic layer whose composition has changed in both semiconductor layers of the e layer can be obtained.

In the semiconductor heterostructure according to the first aspect of the present invention, when the strained semiconductor layer is a strained InGaAs layer, a strained InGaAs layer and an InGaAsP layer are interposed between the strained InGaAs layer and the InGaAsP layer.
Lattice-matched In having the same group V composition as the strained InGaAs layer
By inserting the GaAs layer, the interface between the strained InGaAs layer and the unstrained InGaAs layer having the same V group composition, and the unstrained InGaAs layer and the InGaAsP layer having different V group compositions are different.
Since it can be separated from the interface of the layer, the surface roughness due to the standby for the growth interruption on the surface of the strained InGaAs layer can be avoided.

Further, the surface of the strain-free InGaAs layer is
By covering with a protective layer of an InAs layer of a molecular layer or an InP layer having a thickness of 1 to 3 nm, deterioration of the surface during standby can be prevented.

When P is supplied directly to the surface of InGaAs, Ga atoms are more easily bonded to P than As, so that InP
InGaP having a smaller lattice constant than the substrate is formed,
After several tens of seconds, the surface becomes rough, and the InGaAsP layer grown thereon deteriorates. However, InG
By covering the aAs surface with an InAs layer or an InP layer, which is a semiconductor layer containing only In, the change in lattice constant is small even when As and P are taken into the surface, so that surface roughness can be prevented.

The protective layer of the InP layer having a thickness of 1 to 3 nm can withstand the irradiation of AsP for several tens of seconds to about 1 minute, and is on the InGaAs lattice matching insertion layer. It is possible to sufficiently wait for group V irradiation while maintaining the flatness of the surface. In addition, R at the time of interface standby or during growth
By observing the HEED image, it is possible to relatively easily optimize the thickness of the protective layer and the insertion layer in a range where the surface is not deteriorated.

The semiconductor heterostructure according to the present invention has a strained InG
When applied to the semiconductor heterostructure of the aAs layer and the InGaAsP layer, the strain-free InGaAs insertion layer and the InAsP protective layer have a feature of being inserted between the strained InGaAs layer and the InGaAsP layer. A high-quality semiconductor heterostructure having a flat interface without a metamorphic layer having a changed composition in the semiconductor layer of the insertion layer and the InGaAsP layer is obtained.

The II-VI compound semiconductor heterostructure according to the present invention according to the fifth aspect also provides the III-VI compound semiconductor heterostructure according to the second aspect.
A high-quality semiconductor having a flat interface without including a metamorphic layer whose composition has been changed in the strained ZnCdSe semiconductor layer, the unstrained ZnCdSe insertion layer, and the ZnCdSSe layer, which have the same function and effect as the group V semiconductor heterostructure. A heterostructure is obtained.

[0060]

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

[Embodiment 1] As a first embodiment of the present invention, a heterostructure characterized by having an InAs (P) layer having a thickness of one molecular layer between a strain-free InGaAs well layer and an InGaAsP layer. Laser diode (L
D) will be described below. FIG. 1 shows a sectional layer structure of an LD according to the first embodiment of the present invention.

Referring to FIG. 1, LD according to the present embodiment
Is an n-InP cladding layer 3 on an n-InP substrate 2,
N-InGaAs having a layer thickness of 150 nm and a wavelength of 1.2 μm
The sP light confinement layer 4 and a layer thickness of 50 nm and a wavelength of 1.2 μm
An InGaAsP barrier layer 5 having a composition, a strain-free InGaAs well layer 6 having a thickness of 6 nm, and InAs having a thickness of one molecular layer.
(P) The protective layer 7 and the I layer having a layer thickness of 4 nm and a wavelength of 1.2 μm
a multi-quantum well active layer in which nGaAsP barrier layers 8 are alternately laminated for four periods;
m InGaAsP barrier layer 5 having a thickness of 150 nm
A p-InGaAsP light confinement layer 9 having a wavelength of 1.2 μm and a p-InP cladding layer 10 having a thickness of 1.5 μm;
A 0.2 μm thick p-InGaAs contact layer 11,
It comprises a p-electrode 12 and an n-electrode 1. The n-type and p-type doping concentrations are about 7 × 10 ¹⁷ cm ⁻³ .

For example, when this LD is manufactured by the gas source MBE method, a strain-free InGaAs well layer 6 is grown, the supply of As and Ga is stopped, In is supplied for one atomic layer, and the residual As is removed. After forming the InAs layer 7 with In,
As and P for growing the InGaAsP barrier layer 8 having a composition of 2 μm are continuously supplied for about 20 to 70 seconds until their pressure is stabilized.

During this growth interruption standby, the InAs layer 7
Incorporation of atoms, InAs (P) protective layer 7 with one molecular layer thickness
To form

In the LD according to the present embodiment, the thickness of each layer, the composition of the InGaAsP layer, the number of quantum wells, or the doping concentration is not limited to the above values. By appropriately changing those elements, an LD having different characteristics such as an oscillation wavelength can be obtained.

[Embodiment 2] Next, a second embodiment of the present invention will be described. A second embodiment of the present invention is different from the LD according to the first embodiment described with reference to FIG. (As) An LD having a heterostructure provided with a protective layer. Except for this, the structure is the same as that of the first embodiment. However, since the InP layer is a lattice matching layer and does not cause crystal deterioration even if the layer thickness is increased, the layer thickness of the InP (As) protective layer 7 in the LD of this embodiment is limited to two molecular layers. Instead, an InP (As) protective layer having an appropriate thickness is formed according to the length of the standby time.

For example, when this LD is manufactured by a gas source MBE method, a strain-free InGaAs well layer 6 is grown, supply of As, Ga, and In is stopped, P is introduced, and In for two atomic layers is introduced. After supplying and forming the InP layer, 1.2
As and P for growing the InGaAsP barrier layer 8 having a composition of μm are increased by 20 until their beam intensity becomes stable.
The supply is continued for about seconds to 70 seconds. During the interruption of the growth, the InP layer takes in As atoms to form the InP (As) protective layer 7.

The LD of the present embodiment is made of unstrained InGaAs.
InP (A) is placed between the well layer 6 and the InGaAsP layer 8.
s) An LD characterized by having a layer, and the other elements such as the thickness of each layer, the composition of the InGaAsP layer, the number of quantum wells, and the doping concentration are not particularly limited. By changing those factors, an LD having different characteristics such as an oscillation wavelength can be obtained.

The following describes the waiting time at the hetero interface immediately before growing the semiconductor layer containing two or more kinds of upper group V atoms while only two or more kinds of V group atoms are supplied. The layer thickness of the semiconductor layer containing only group III atoms
Quadrupole mass spectrometer and reflection high energy electron diffraction (RHE)
An optimization method using an ED) device will be described in detail.

In the MBE apparatus, a semiconductor layer such as InGaAsP containing two or more kinds of V group atoms used for LD is grown, and As introduced into the growth chamber by a quadrupole mass spectrometer.
And the quadrature mass spectrometers P and P are used to measure the temporal change in the measured signal intensity.

After the introduction of As and P into the growth chamber, the group V composition stabilization time from when the measured signal intensity of As and P reaches a steady state is measured. Usually, the group V composition stabilization time is 2
The time is about 0 to 70 seconds. However, the experiment is performed while keeping the substrate temperature constant.

Next, before growing InGaAsP, a lattice-matched InGaAs is grown, and then one molecular layer of IGaAs is grown.
An nAs protective layer or a several nm InP protective layer is grown, growth is interrupted on the InAs or InP surface, AsP is supplied to the surface and irradiation is waited. InAs or I
Observation of the nP surface with a RHEED device reveals a RHEED pattern suggesting a 2 × 4 group V stabilized surface.

The group V irradiation standby time is determined with reference to the group V composition stabilization time obtained above. And a predetermined V
After elapse of the group irradiation standby time, an InGaAsP layer is grown.

When the RHEED pattern starts to change from a streak pattern to a potty pattern showing three-dimensional growth, growth of InGaAsP is stopped, and InP is grown to recover the interface.

When the intensity of the RHEED specular beam is observed and RHEED oscillation is obtained, two-dimensional growth is realized, which is a measure of recovery of the growth surface. When the growth surface recovers, the lattice-matched InGaAs is grown again, and the above experiment is repeated. In this way, RHEE
V such that the D pattern maintains the streak pattern
Calculate the waiting time for tribal irradiation.

The V-group irradiation standby time obtained is determined by the fact that the growth start surface is made three-dimensional during the standby, and the In
This is a time during which the GaAsP layer does not grow three-dimensionally.

If the optimum V group irradiation standby time cannot be obtained, the optimum V group irradiation standby time is obtained by changing the thickness of the InP protective layer. The layer thickness of the strain-free InGaAs insertion layer described in the following embodiments is also optimized.

In the case of hetero-growth of a II-VI semiconductor layer containing two or more kinds of VI atoms, the waiting time can be optimized in the same manner.

[Embodiment 3] FIG. 2 is a diagram showing a sectional layer structure of an LD according to a third embodiment of the present invention. The present embodiment has a heterostructure characterized by having an unstrained InGaAs well layer and a one-molecule-thick InAs (P) layer between a strained InGaAs well layer and an InGaAsP barrier layer. Oscillation wavelength 1.8 to 2.1 μm
This is the LD of the band.

Referring to FIG. 2, LD according to the present embodiment
Is the n-InP cladding layer 23 on the n-InP substrate 22
And n-InG having a layer thickness of 150 nm and a wavelength of 1.3 μm.
aAsP light confinement layer 24 and a wavelength of 1.
InGaAsP barrier layer 25 having a composition of 3 μm and a thickness of 7 n
m, an InGaAs well layer 26 having a compressive strain of 1.5%, a non-strained InGaAs spacer layer 27 having a layer thickness of 2 nm, an InAs (P) protective layer 28 having a thickness of one molecular layer, and InGaAsP having a layer thickness of 10 nm and a composition of 1.3 μm. A multiple quantum well active layer in which barrier layers 29 are alternately stacked for three periods;
InGaAsP barrier layer 2 having a composition of 1.3 μm wavelength in nm
5 and p-In having a layer thickness of 150 nm and a wavelength of 1.3 μm.
GaAsP light confinement layer 30 and 1.8 μm thick p-I
nP cladding layer 31 and 0.2 μm thick p-InGaAs
an s-contact layer 32, a p-electrode 33, an n-electrode 21,
Consists of

For example, when this LD is manufactured by the gas source MBE method, a 1.5% compressive strained InGaAs well layer 26 is grown, and a non-strained InGaAs spacer layer 27 is grown without an interface standby, and the As Stop supplying Ga
After supplying In for an atomic layer and forming an InAs layer with residual As and In, As and P for growing an InGaAsP barrier layer 29 having a composition of 1.3 μm are reduced from 20 seconds until their pressure is stabilized. Supply is continued for about 70 seconds. During this growth interruption standby, the InAs layer takes in P atoms,
An InAs (P) protective layer 28 having a thickness of one molecular layer is formed.

[Fourth Embodiment] An LD according to a fourth embodiment of the present invention is different from the LD according to the third embodiment in that an InP (A) protective layer 28 having a thickness of one molecular layer is replaced with an InP (A).
s) A heterostructure having a protective layer is provided, and the other structure is the same as that of the third embodiment.

For example, when this LD is manufactured by the gas source MBE method, an InGaAs well layer 26 having a 1.5% compressive strain is grown, and a non-strained InGaAs spacer layer 27 is grown without an interface standby, and the As and Al layers are grown. Stop supply of Ga, P
Is introduced, one atomic layer of In is supplied, and an InP layer is formed, and then an InGaAsP barrier layer 29 having a composition of 1.3 μm is formed.
Are continued to be supplied for about 20 to 70 seconds until the pressure stabilizes.

During the standby for the interruption of the growth, the InP layer takes in As atoms to form an InP (As) protective layer having a thickness of one molecular layer. However, since the InP layer is a lattice matching layer and does not cause crystal deterioration even if the layer thickness is increased, the thickness of the InP (As) protective layer in the LD of the fourth embodiment is:
An InP (As) protective layer having an appropriate thickness is formed according to the size of the waiting time, not limited to one molecular layer.

[Fifth Embodiment] FIG. 3 is a diagram showing a sectional layer structure of an LD according to a fifth embodiment of the present invention. The LD according to the present embodiment has a strained quantum well layer composed of an InAs layer and a strained InGaAs layer.
It has a heterostructure characterized by having a strain-free InGaAs spacer layer and a one-molecule-thick InAs (P) layer between an AsP barrier layer and an oscillation wavelength band of 1.8 to 2.1 μm. LD.

Referring to FIG. 3, LD according to the present embodiment
Represents an n-InP cladding layer 42 on an n-InP substrate 41.
And n-InG having a layer thickness of 150 nm and a wavelength of 1.3 μm.
aAsP light confinement layer 43, layer thickness 50 nm and wavelength 1.
An InGaAsP barrier layer 44 having a composition of 3 μm, a strained InGaAs layer 45 having a thickness of 0.8 and a thickness of 2 molecular layers, an InAs well layer 46 having a thickness of 6 molecular layers, and an In composition having a thickness of 2 molecular layers of 0.1 μm
8 strained InGaAs layer 47 and 2 nm thick strain-free InG
aAs spacer layer 48, InAs (P) protective layer 49 having a thickness of one molecular layer, and InG having a thickness of 10 nm and a composition of 1.3 μm.
a multiple quantum well active layer formed by alternately laminating an aAsP barrier layer 50 for two periods, an InGaAsP barrier layer 44 having a layer thickness of 50 nm and a composition of 1.3 μm, and a p-InGaAsP layer having a layer thickness of 150 nm and a composition of 1.3 μm. A light confinement layer 51, a 2.0 μm thick p-InP cladding layer 52,
A 0.2 μm thick p-InGaAs contact layer 53;
It comprises a p-electrode 54 and an n-electrode 40.

The method of manufacturing an LD according to the present embodiment is the same as that of the LD according to the third embodiment. Where In
As is sensitive to growth conditions, for example, As is grown under growth conditions of a growth rate of 1 μm / h, a growth temperature of 440 ° C., and a V / III ratio of 20.

A strained InGaAs layer 45 having an In composition of 0.8
Is a 2.5% compressive strained InAs layer and an unstrained InGaAs layer.
By relieving a sudden change in lattice constant with InAs,
Has the effect of preventing three-dimensional growth.

[Embodiment 6] An LD according to a sixth embodiment of the present invention is different from the LD according to the fifth embodiment in that an InAs (P) protective layer 49 having a thickness of one molecular layer is replaced with InP (A).
s) It has a heterostructure provided with a protective layer, and otherwise has the same structure as the fifth embodiment. The LD according to this embodiment can be manufactured in the same manner as the LD according to the fourth and fifth embodiments.

In the above, an embodiment in which the present invention is applied to a III-V compound semiconductor laser has been described. Hereinafter, an embodiment in which the present invention is applied to a II-VI compound semiconductor laser will be described. explain.

III-V compound semiconductor InGaAsP
The material of the II-VI group compound semiconductor corresponding to
SeS. In a compound semiconductor laser on an InP substrate, In which forms a III-V group compound semiconductor laser,
By replacing In with Cd, Ga with Zn, As with Se, and P with S in each of the GaAsP-based materials, II-VI having a structure corresponding to the III-V compound LD can be obtained.
Compound LD can be constituted.

[Embodiment 7] A seventh embodiment of the present invention is based on an InP substrate having a heterostructure having a one-molecule-thick CdSe (S) protective layer between an unstrained ZnCdSe layer and a ZnCdSeS layer. LD. FIG. 4 shows a sectional layer structure of an LD according to a seventh embodiment of the present invention.

Referring to FIG. 4, LD according to the present embodiment
Is the n-InP buffer layer 6 on the n-InP substrate 61.
2, n-InGaAs buffer layer 63, n-Mg
A ZnCdSe cladding layer 64, a 50 nm thick non-strained n-ZnCdSSe light confinement layer 65, and a 10 nm thick layer
Strain-free n-ZnSSe barrier layer 66, a 6-nm-thick strain-free ZnCdSe well layer 67 and a one-molecule-thick CdS
e (S) protective layer 68 and 4 nm thick non-strained n-ZnCd
A multiple quantum well active layer in which four SSe barrier layers 69 are alternately stacked, and a non-strained n-ZnCdSS having a thickness of 10 nm
e barrier layer 66 and a 50-nm-thick strain-free p-ZnCd
It comprises an SSe light confinement layer 70, a p-MgZnCdSe cladding layer 71, a 0.2 μm thick p-ZnCdSe contact layer 72, a p-electrode 73, and an n-electrode 60.

The n-type and p-type doping concentrations are about 7 ×
10 ¹⁷ cm ^-3 . Unstrained ZnCdSe well layer 67
Is a composition corresponding to a wavelength of 640 nm of Zn _0.48 Cd _0.52 Se. The composition of the unconfined ZnCdSSe light confinement layers 65 and 70 and the barrier layers 66 and 69 is Z
The composition corresponds to a wavelength of 590 nm of n _0.10 Cd _0.9 S _0.66 Se _0.34 . Further, n- and p-type MgZnCdS
The composition of the e-cladding layers 64 and 71 is Mg _0.27 Zn _0.37
This is a composition corresponding to a wavelength of 500 nm of Cd _0.36 Se.

When the LD according to this embodiment is manufactured by the MBE method, an unstrained ZnCdSe well layer 67 is grown,
After stopping the supply of e and Zn, supplying Cd for one atomic layer, forming a CdSe layer with residual Se and Cd,
Se and S for growing the dSSe barrier layer 69 are:
Supply is continued for about 30 to 90 seconds until the pressure is stabilized. At the time of standby for the growth interruption, the CdSe layer takes in S atoms and the CdSe (S) protective layer 68 having a thickness of one molecular layer.
To form

However, in this embodiment or the embodiment described below in which the present invention is applied to a II-VI compound semiconductor laser, the layer thickness and composition of each semiconductor layer constituting the LD, for example, a strain-free ZnCdSSe layer Composition or Mg
Numerical values defining constituents such as the composition of the cladding layer of the ZnCdSe layer or the number of quantum wells and the doping concentration are as follows:
It is not limited to the above numerical values. Then, by changing the numerical values defining these components, an LD of visible light such as red, orange, yellow, green, and blue can be obtained.

In this embodiment and the embodiments described below, the light confinement layer or barrier layer of the LD is a strain-free ZnCdSS lattice-matched to the InP substrate.
e layer, not limited to CdSSe layer or ZnSeT
An e layer or a ZnCdSeTe layer may be used instead. Also, the cladding layer of the LD is not limited to the unstrained MgZnCdSe layer lattice-matched to the InP substrate, but is also an unstrained MgCdSSe layer or an unstrained MgZnCdSSe layer.
Alternatively, a layer composed of a layer, a MgZnSeTe layer, or a combination thereof may be used.

For example, Se lattice-matched to an InP substrate,
The composition of a typical ternary semiconductor layer containing S is Zn _0.48 Cd
_0.52 Se, CdS _0.83 Se _0.17 , Mg _0.9 Zn _0.1 Se,
An unstrained quaternary composition of MgS _0.08 Se _0.92 lattice-matched to the InP substrate is obtained by combining these ternary compositions.

That is, the composition of the strain-free ZnCdSSe layer used for the light confinement layer or the barrier layer of the LD is as follows:
(Zn _0.48 Cd _0.52 Se) _X (CdS _0.83 Se _0.17 ) _1-X
And the unstrained MgZ used for the LD cladding layer
The composition of the nCdSw layer is (Mg _0.9 Zn _0.1 Se) _x (Z
The composition of the non-strained MgCdSSe layer with n _0.48 Cd _0.52 Se) _1-X is (MgS _0.08 Se _0.92 ) _X (CdS _0.83 Se
_0.17 ) The composition of the _1-X , unstrained MgZnCdSSe layer is:
(MgS _0.08 Se _0.92 ) _X (Zn _0.48 Cd _0.52 S
e) _1-X or (Mg _0.9 Zn _0.1 Se) _x (CdS
_0.83 Se _0.17 ) _{Represented by 1-X} .

[Eighth Embodiment] An LD according to an eighth embodiment of the present invention is different from the LD according to the seventh embodiment in that a CdSe (S) protective layer 68 having a thickness of one molecular layer is replaced by CdS (S).
e) It has a heterostructure provided with a protective layer, and otherwise has the same structure as the seventh embodiment. However, since the CdS layer has relatively good lattice matching with the InP substrate,
In the LD of the embodiment, the thickness of the CdS (Se) protective layer is not limited to one molecular layer, but may be determined according to the magnitude of the waiting time.
A CdS (Se) protective layer having an appropriate thickness is to be formed.

When the LD according to the present embodiment is manufactured by the MBE method, an unstrained ZnCdSe well layer 67 is grown,
After stopping the supply of n and Cd, switching from Se to S, supplying Cd for one atomic layer, forming a CdS layer, suspending the growth, and growing Se for growing the strain-free ZnCdSSe barrier layer 69. And S until the pressure stabilizes
Supply is continued for about 90 to 90 seconds. During this growth interruption standby, the CdS layer takes in Se atoms and the CdS layer has a thickness of one molecular layer.
An S (Se) protective layer is formed.

Since S alone has a very high vapor pressure and is difficult to control with a normal Knudsen cell, for example, a raw material of a compound such as ZnS is used to supply S at a reduced vapor pressure. It is not possible to supply only S without doing so.

As in the present embodiment, stable supply control of only S is performed by using a needle valve cracking cell filled with S solid raw material, or by cracking a gas raw material such as H ₂ S, It can be realized by controlling the supply of.

[Embodiment 9] An LD according to a ninth embodiment of the present invention comprises a strained ZnCdSe well layer and a ZnCdSSe.
A non-strained ZnCdSe spacer layer and 1
An LD on an InP substrate having a heterostructure characterized by having a CdSe (S) layer with a molecular layer thickness. In FIG.
14 shows a sectional layer structure of an LD according to a ninth embodiment of the present invention.

Referring to FIG. 5, LD according to the present embodiment
Represents an n-InP buffer layer 82 on an n-InP group 81.
, N-InGaAs buffer layer 83 and n-MgZ
An nCdSe cladding layer 84 and a 50-nm thick non-strained n
A ZnCdSSe optical confinement layer 85, a 10 nm thick unstrained n-ZnCdSSe barrier layer 86, and a 6 nm thick
1.5% compressive strain Zn _0.25 Cd _0.75 Se strain Zn
CdSe well layers 87 and 2 nm thick strain-free ZnCdSe
Spacer layer 88 and CdSe (S) protective layer 8 having a thickness of one molecular layer
9 and a 5 nm thick non-strained n-ZnCdSSe barrier layer 9
0 is alternately stacked for three periods, an unstrained n-ZnCdSSe barrier layer 86 having a thickness of 10 nm, an unstrained p-ZnCdSSe light confinement layer 91 having a thickness of 50 nm, and p -MgZnCdSe cladding layer 92
And a 0.2 μm thick p-ZnCdSe contact layer 93
, A p-electrode 94, and an n-electrode 80. The n-type and p-type doping concentrations are about 7 × 10 ¹⁷ cm ⁻³ .

When the LD having the heterostructure according to the present embodiment is manufactured by the MBE method, the strain ZnCd having a compressive strain of 1.5% is obtained.
A Se well layer 87 is grown, and no Z
After growing the nCdSe spacer layer 88, Zn and Se
Is stopped, Cd for one atomic layer is supplied, and a CdSe layer is formed from residual Se and Cd.
Se and S for growing the barrier layer 90 are continuously supplied for about 30 to 90 seconds until their pressure is stabilized.

At the time of waiting for the interruption of the growth, the CdSe layer takes in S atoms, and the CdSe (S) protective layer 89 having a thickness of one molecular layer.
Is formed.

[Embodiment 10] An LD according to a tenth embodiment of the present invention is different from the LD of the ninth embodiment in that a CdSe (S) protective layer 89 having a thickness of one molecular layer is replaced by CdS (S).
e) It has a hetero structure provided with a protective layer, and otherwise has the same structure as the ninth embodiment. However, since the CdS layer has relatively good lattice matching with the InP substrate, the CdS (S
e) The thickness of the protective layer is not limited to one molecular layer, and a CdS (Se) protective layer having an appropriate thickness is formed according to the size of the waiting time.

When the LD having the heterostructure according to the present embodiment is manufactured by the MBE method, the strain ZnCd having a compressive strain of 1.5% is obtained.
A Se well layer 87 is grown, and no Z
The nCdSe spacer layer 88 is grown, the supply of Zn and Cd is stopped, and Se is switched to S, so that one atomic layer of Cd
Is supplied to form a CdS layer, and then the growth is interrupted and Se for growing the unstrained ZnCdSSe barrier layer 69 is formed.
And S are continuously supplied for about 30 to 90 seconds until their pressure is stabilized.

During the standby for the growth interruption, the CdS layer takes in Se atoms to form a CdS (Se) protective layer having a thickness of one molecular layer.

[Embodiment 11] An LD according to an eleventh embodiment of the present invention has a strained quantum well layer composed of a CdSe layer and a strained ZnCdSe layer.
An LD on an InP substrate having a heterostructure characterized by having an unstrained ZnCdSe spacer layer and a CdSe (S) protective layer having a thickness of one molecule between a CdSSe barrier layer. FIG. 6 shows a sectional layer structure of an LD according to an eleventh embodiment of the present invention.

Referring to FIG. 6, LD according to the present embodiment will be described.
Is the n-InP buffer layer 1 on the n-InP group 101
02, n-InGaAs buffer layer 103, and n-
MgZnCdSe cladding layer 104, non-strained n-ZnCdSSe optical confinement layer 105 having a thickness of 50 nm, and non-strained n-ZnCdSSe barrier layer 106 having a thickness of 10 nm
And 1.8% compressive strain of Zn _0.2 Cd _0.8 Se with a bilayer thickness
Strained CdSe layer 107 and CdSe having a thickness of 6 molecular layers
Well layer 108 and a bilayer thickness of 1.8% compressive strain Zn
_0.2 Cd _0.8 Se strained ZnCdSe layer 109 and layer thickness 2
a multi-quantum well active layer formed by alternately stacking two cycles of a non-strained ZnCdSe spacer layer 110 having a thickness of 1 nm, a CdSe (S) protective layer 111 having a thickness of one molecular layer, and a non-strained ZnCdSSe barrier layer 112 having a thickness of 5 nm. A non-strained n with a layer thickness of 10 nm
A ZnCdSSe barrier layer 106, a 50-nm-thick unstrained p-ZnCdSSe light confinement layer 113, and a p-M
gZnCdSe cladding layer 114 and 0.2 μm thick p
A ZnCdSe contact layer 115 and a p-electrode 116
And an n-electrode 100. The n-type and p-type doping concentrations are about 7 × 10 ¹⁷ cm ⁻³ .

The method of manufacturing an LD according to the present embodiment is the same as that of the LD according to the ninth embodiment. However, CdS
Since e is sensitive to the growth conditions, for example, the growth rate is 1
The growth is performed under a growth condition of 200 μm / h, a growth temperature of 200 to 250 ° C., and a low VI / II ratio. 1.8% Zn _0.2 Cd with compressive strain
_{The 0.8} Se layer 107 has an effect of preventing a three-dimensional growth of CdSe by relaxing a sudden change in lattice constant between the CdSe well layer having a compressive strain of 2.5% and the ZnCdSe layer having no strain.

[Embodiment 12] The LD according to the twelfth embodiment of the present invention is the same as the LD according to the eleventh embodiment.
Instead of the CdSe (S) protective layer 111 having a molecular layer thickness,
This is an LD having a dS (Se) protective layer, and has the same structure as the LD according to the eleventh embodiment except for this.
The LD according to this embodiment can be manufactured in the same manner as the LD having the heterostructure according to the tenth and eleventh embodiments.

[0115]

As described above, the semiconductor heterostructure of the present invention takes into account the practical limitations of the performance of the manufacturing apparatus, avoids damage to the semiconductor layer due to AsP or SSe irradiation, and reduces InGaAsP. Layer or Z
This has the effect of providing a high quality heterostructure without a compositionally modified layer of the nCdSSe layer.

According to the present invention, the strained semiconductor layer and the In
Even in a heterostructure including a GaAsP layer or a ZnCdSSe layer, a heterostructure having a flat interface without a composition change layer can be realized.

Then, the semiconductor heterostructure according to the present invention is formed by combining a lattice-matched InGaAs well layer with an InGaAs well layer.
When applied to a quantum well structure composed of a P barrier layer, a quantum well structure in which an InAsP layer having a thickness of 1 to 5 molecular layers is inserted between an unstrained InGaAs well layer and an InGaAsP barrier layer is obtained. Because the thickness is small,
Effective electron confinement and hole injection can be achieved, and a high-quality quantum well structure that does not include a composition alteration layer can be obtained in both the InGaAs well layer and the InGaAsP barrier layer.

Further, the semiconductor heterostructure according to the present invention is formed by combining a lattice-matched ZnCdSe well layer with a ZnCdSS.
When applied to a quantum well structure composed of an e-barrier layer, a quantum well structure in which a CdSSe layer having a thickness of 1 to 5 molecular layers is inserted between an unstrained ZnCdSe well layer and a ZnCdSSe barrier layer is obtained. Because the thickness is small,
Effective electron confinement and hole injection are enabled, and a high-quality quantum well structure that does not include a compositionally modified layer is obtained in both the ZnCdSe well layer and the ZnCdSSe barrier layer.

Further, when the semiconductor heterostructure of the present invention is applied to a strained quantum well structure of a strained InGaAs well layer and an InGaAsP barrier layer, the strainless InGaAs insertion layer and the InAsP protective layer are formed of the strained InGaAs well layer and the IAs.
Although a strained quantum well structure inserted between the nGaAsP barrier layers is obtained, the band gap of the unstrained InGaAs insertion layer is intermediate between the strained InGaAs well layer and the InGaAsP barrier layer, and the InAsP protective layer has a small thickness. It is possible to confine electrons and inject holes, and to obtain a high-quality strained quantum well structure that does not include a compositionally modified layer in all semiconductor layers constituting the quantum well structure.

Further, according to the present invention described in claim 5 , II-
The group VI semiconductor heterostructure also has the same function and effect as the III-V semiconductor heterostructure according to the present invention described in claim 1 , and as a result, a ZnCdSSe layer having a stable group VI composition can be obtained. The resulting strained quantum well structure is obtained.

As described in the above embodiment of the present invention,
When the semiconductor heterostructure according to the present invention is applied to a multiple quantum well semiconductor laser having an InGaAsP layer or a ZnCdSSe layer as a barrier layer or an optical confinement layer of a quantum well layer, it is caused by a compositionally modified layer or a non-flat strain interface. Since there is no non-radiative recombination of carriers, an active layer having a multiple quantum well structure with excellent optical quality can be obtained.
Therefore, there is an advantage that the threshold, output, temperature characteristics, and reliability of the semiconductor laser can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a sectional layer structure of an LD according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a sectional layer structure of an LD according to a third embodiment of the present invention.

FIG. 3 is a diagram showing a sectional layer structure of an LD according to a fifth embodiment of the present invention.

FIG. 4 is a diagram showing a sectional layer structure of an LD according to a seventh embodiment of the present invention.

FIG. 5 is a diagram showing a sectional layer structure of an LD according to a ninth embodiment of the present invention.

FIG. 6 is a diagram showing a sectional layer structure of an LD according to an eleventh embodiment of the present invention.

[Explanation of symbols]

 1, 21, 40, 60, 80, 100 n electrode 2, 22, 41, 61 n-InP substrate 3, 23, 42 n-InP cladding layer 4 n-InGaAsP light confinement layer 5 InGaAsP barrier layer 6 InGaAs well layer 7 InAs (P) protective layer 8 InGaAsP barrier layer 9 p-InGaAsP light confinement layer 10 p-InP clad layer 11 p-InGaAs contact layer 12, 33, 54, 73, 94, 116 p electrode 24 n-InGaAsP light confinement layer 25 InGaAsP barrier layer 26 Strained InGaAs well layer 27 Non-strained InGaAs spacer layer 28 InAs (P) protective layer 29 InGaAsP barrier layer 30 p-InGaAsP light confinement layer 31, 52 p-InP cladding layer 32 p-InGaAs contact layer 43 n- In GaAsP light confinement layer 44 InGaAsP barrier layer 45 Strained InGaAs layer 46 InAs well layer 47 Strained InGaAs layer 48 Unstrained InGaAs spacer layer 49 InAs (P) protection layer 50 InGaAsP barrier layer 51 p-InGaAsP light confinement layer 53 p-In Layer 62 n-InP buffer layer 63 InGaAs buffer layer 64 n-MgZnCdSe cladding layer 65 unstrained n-ZnCdSSe light confinement layer 66 n-ZnSSe barrier layer 67 unstrained ZnCdSe well layer 68 CdSe (S) protection layer 69 unstrained N-ZnCdSSe barrier layer 70 Non-strained p-ZnCdSSe light confinement layer 71 p-MgZnCdSe cladding layer 72 p-ZnCdSe contact layer 81 n-InP group 82 n-InP Buffer layer 83 n-InGaAs buffer layer 84 n-MgZnCdSe cladding layer 85 n-ZnCdSSe light confinement layer 86 n-ZnCdSSe barrier layer 87 strained ZnCdSe well layer 88 strain-free ZnCdSe spacer layer 89 CdSe (P) protection layer 90 n-ZnCdSS barrier Layer 91 p-ZnCdSSe light confinement layer 92 p-MgZnCdSe cladding layer 93 p-ZnCdSe contact layer 101 n-InP base 102 n-InP buffer layer 103 n-InGaAs buffer layer 104 n-MgZnCdSe cladding layer 105 n-ZnSSe light confinement layer 106 n-ZnCdSSe barrier layer 107 strained ZnCdSe layer 108 CdSe well layer 109 strained ZnCdSe layer 110 non-strained ZnCdSe spacer layer 111 C Se (S) protective layer 112 ZnCdSSe barrier layer 113 p-ZnCdSSe light confining layer 114 p-MgZnCdSe cladding layer 115 p-ZnCdSe contact layer

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-7053 (JP, A) JP-A-5-275680 (JP, A) JP-A-6-132236 (JP, A) JP-A-3-3 116796 (JP, A) Appl. Phys. Lett. 53 [21] (1988) p. 2019-2020 1992 (Heisei Era) Fall Meeting, 17p-ZF-13 p. 245 1995 (Heisei 7) Autumn Proceedings of the Society of Applied Biology 29a-W-2 p. 301 (58) Field surveyed (Int.Cl. ⁶ , DB name) H01S 3/18

Claims (11)

(57) [Claims] A first strained semiconductor layer of a group III-V compound having a lattice constant different from that of a substrate; a non-strained second semiconductor layer having the same group V composition as the first strained semiconductor layer; And a fourth semiconductor layer containing a plurality of V-group elements. Construction. Wherein said first strained semiconductor layer, the semiconductor heterostructure according to claim 1, wherein the group V composition is in common, and strain amount, characterized in that it consists of a plurality of different strained semiconductor layer. 3. The semiconductor device according to claim 1, wherein the third semiconductor layer is a group atom of In.
The semiconductor heterostructure of claim 1 or 2, characterized in that it comprises a. 4. A strain-free II having substantially the same lattice constant as a substrate.
A first semiconductor layer of a Group VI compound, a second semiconductor layer having a predetermined molecular layer thickness containing one kind of Group II element (atom), a third semiconductor layer containing plural kinds of Group VI elements, A semiconductor heterostructure having a layer structure formed by sequentially forming 5. A first strained semiconductor layer of a II-VI compound having a lattice constant different from that of a substrate, a non-strained second semiconductor layer having the same group VI composition as the first strained semiconductor layer, A third semiconductor layer containing one kind of group II element (atom) and a fourth semiconductor layer containing a plurality of kinds of group VI atoms; Construction. 6. The semiconductor heterostructure according to claim 5, wherein said first strained semiconductor layer comprises a plurality of strained semiconductor layers having a common group VI composition and different amounts of strain. 7. The semiconductor device according to claim 7, wherein said third semiconductor layer comprises Cd as a group II atom.
The semiconductor heterostructure according to claim 4 , wherein the semiconductor heterostructure comprises: 8. The semiconductor heterostructure according to claim 4, wherein said predetermined molecular layer thickness is 1 to 5. 9. A strain-free ZnCd provided on an InP substrate.
Between the Se layer and the ZnCdSSe barrier layer, the unstrained Z
At least Cd of a predetermined layer thickness formed on the nCdSe layer
And a protective layer that incorporates Se and / or S for forming the ZnCdSSe barrier layer. 10. A strained InGa provided on an InP substrate.
Between the As layer and the InGaAsP barrier layer, the strain In
Unstrained InGaAs having the same V-group (As) composition as the GaAs layer
A layer containing at least In with a predetermined layer thickness formed on the unstrained InGaAs layer is formed of the InGaAs layer.
A heterostructure of a semiconductor laser, comprising a protective layer incorporating As and / or P for forming a P barrier layer. 11. A strained ZnCd provided on an InP substrate.
Between the Se layer and the ZnCdSSe barrier layer, the strain Zn
An unstrained ZnCdSe layer having the same group VI composition as the CdSe layer is inserted, and a layer containing at least Cd having a predetermined thickness formed on the unstrained ZnCdSe layer is formed of Se and / or for forming the ZnCdSSe barrier layer. A heterostructure of a semiconductor laser, comprising a protective layer incorporating S.