JPH08288311A - Semiconductor multilayer structure and fabrication thereof - Google Patents

Abstract

PURPOSE: To improve crystallinity by forming at least one II-VI compound semiconductor layer on a ZnSe layer on a substrate and setting the defect density of a laminate lower than a specified value thereby lowering the defect density of the laminate. CONSTITUTION: The defect density of a laminate is set lower than 104cm<-2> for an n-type ZnSe buffer layer 43 formed on an n-type GaAs substrate 41. In the initial stage until the thickness of about 10 atomic layer is obtained, the n-type ZnSe buffer layer 43 is grown by setting the ratio of intensity between an Se molecular beam and a Zn molecular beam lower than 1, e.g. 0.7. Subsequently, the intensity ratio is set in the range of 1-1.5 thus obtaining an n-type ZnSe buffer layer 43 of required thickness. With such method, a multilayer semiconductor structure including a ZnSe layer having good crystallinity can be fabricated.

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 and a method for manufacturing the same, and is particularly suitable for application to a semiconductor device using a II-VI group compound semiconductor, for example, a semiconductor light emitting element.

[0002]

2. Description of the Related Art In recent years, in order to increase the recording / reproducing density and resolution of optical disks and magneto-optical disks,
There is an increasing demand for semiconductor light emitting devices capable of emitting blue or green light, and research is actively conducted toward the realization thereof. As a material used for such a semiconductor light emitting device capable of emitting blue or green light, Zn is
Se-based II-VI group compound semiconductors have been demonstrated to be the most promising.

As a result of research conducted so far, II-V
A semiconductor laser capable of emitting blue or green light using a group I compound semiconductor has already achieved room temperature continuous oscillation, but this semiconductor laser has a problem that its lifetime is extremely short. The reason why the life is extremely short is that the density of crystal defects, especially stacking faults, is high.

[0004] Therefore, as a result of earnest research for the purpose of extending the life, the present applicant has recently found that ZnCdSe / ZnSS.
e / ZnMgSSe SCH (Separate Confinement H
In a semiconductor laser having an eterostructure), Ga
By using the As buffer layer, the stacking fault density is reduced to 10
^It was reduced to about ⁵ cm ^-2 , and room temperature continuous oscillation of blue or green for several hundred seconds was achieved (Jpn. J. Appl. Phys. 33 (199
4) pp.938-940).

[0005]

However, in the above-mentioned conventional semiconductor laser having a stacking fault density of about 10 ⁵ cm ^-2 , several stacking faults are always present in the stripe, so that there is a problem during operation. There has been a problem that the non-light emitting region due to stacking faults in the active layer increases, and finally no light is emitted.

Therefore, an object of the present invention is to provide a semiconductor laminated structure including a ZnSe layer having a low stacking fault density and good crystallinity, and a manufacturing method thereof.

Another object of the present invention is to provide a method of manufacturing a semiconductor laminated structure capable of manufacturing a semiconductor laminated structure including a II-VI group compound semiconductor layer having a low stacking fault density and good crystallinity. It is in.

[0008]

At present, the II-VI group compound semiconductor is mainly grown by the molecular beam epitaxy (MBE) method. One of the important parameters that influence the crystallinity of the II-VI group compound semiconductor grown by this MBE method is the ratio of the intensity of the group VI element molecular beam to the intensity of the group II element molecular beam during growth ( Hereinafter, simply referred to as "VI / II ratio"). For example,
When growing ZnSe by the MBE method, VI /
The II ratio (= the ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam) is generally set to 1 to 1.5.

As a result of intensive studies to solve the above problems of the conventional technique, the present inventor has found that in order to grow a ZnSe layer having good crystallinity on a substrate by the MBE method, the initial growth of the ZnSe layer is not sufficient. And Se against the intensity of Zn molecular beam
It is effective to grow the ZnSe layer with the ratio of the molecular beam intensities of less than 1 according to this.
The density of stacking faults generated at the interface with the nSe layer is 10 ⁴ c
It was found that it was significantly reduced to less than m ^-2 .

Further, a ZnSe layer is grown on the substrate by the MBE method, and a ZnSSe layer or Z layer is formed on the ZnSe layer by the MBE method.
When growing an nMgSSe layer or the like, in order to improve the crystallinity of the ZnSSe layer, ZnMgSSe layer, or the like,
The intensity of the Se molecular beam during the growth of these mixed crystal semiconductor layers is made higher than the intensity of the Se molecular beam used during the growth of the ZnSe layer so that V that is appropriate for the growth of these mixed crystal semiconductor layers can be obtained.
It has been found that it is effective to grow at an I / II ratio.

The present invention was devised based on the above findings of the present inventor.

In other words, in order to achieve the above object, the semiconductor laminated structure according to the first aspect of the present invention has a ZnSe layer laminated on a substrate and at least one II-VI group laminated on the ZnSe layer. And a compound semiconductor layer,
The stacking fault density is less than 10 ⁴ cm ^-2 .

In an exemplary embodiment of the first invention of the present invention, ZnSS is used as the II-VI compound semiconductor layer.
An e layer and a ZnMgSSe layer are included.

A second invention of the present invention is a method for manufacturing a semiconductor laminated structure, in which a ZnSe layer is grown on a substrate by a molecular beam epitaxy method.
The ratio of the intensity of the Se molecular beam to the intensity of the Molecular beam of Se is made smaller than 1 to grow a ZnSe layer, and then the ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam is set to 1 to 1.5. The feature is that the ZnSe layer is grown.

Here, the initial stage of growth refers to the period immediately after the start of growth until a very thin ZnSe layer, for example, having a thickness of about 10 atomic layers is grown.

In one embodiment of the second aspect of the present invention, the intensity of the Zn molecular beam at the initial stage of growth is increased by repeatedly opening and closing the shutter of the Se molecular beam source while keeping the shutter of the Zn molecular beam source open. The ratio of the effective intensity of the molecular beam of Se to is smaller than 1.

In another embodiment of the second invention of the present invention, the temperature of the Se molecular beam source at the initial stage of growth is made lower than the temperature of the Se molecular beam source thereafter, so that Zn at the initial stage of growth is S for molecular beam intensity
The ratio of the intensity of the molecular beam of e is made smaller than 1.

A third aspect of the present invention is a multi-element II-containing ZnSe layer and at least one layer containing at least Se.
In a method of manufacturing a semiconductor laminated structure in which a group VI compound semiconductor layer is sequentially grown on a substrate by a molecular beam epitaxy method, the molecular beam intensity of Se used during the growth of the group II-VI compound semiconductor layer is set to the growth of the ZnSe layer. It is characterized in that the intensity of the molecular beam of Se used at times is set to be higher.

In one embodiment of the third invention of the present invention, one molecular beam of Se is used when growing the ZnSe layer, and two molecular beams of Se are used when growing the II-VI compound semiconductor layer. Thus, the intensity of the Se molecular beam used during the growth of the II-VI compound semiconductor layer is made higher than the intensity of the Se molecular beam used during the growth of the ZnSe layer.

In another embodiment of the third aspect of the present invention, the temperature of the Se molecular beam source during the growth of the II-VI compound semiconductor layer is set to that of the Se molecular beam source during the growth of the ZnSe layer. By increasing the temperature above II-
The intensity of the Se molecular beam used during the growth of the Group VI compound semiconductor layer is made higher than the intensity of the Se molecular beam used during the growth of the ZnSe layer.

In a preferred embodiment of the third invention of the present invention, the ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam is made smaller than 1 at the beginning of the growth of the ZnSe layer to form the ZnSe layer. Then, the ZnSe layer is grown with the ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam being 1 to 1.5.

In an exemplary embodiment of the third aspect of the present invention, ZnSS is used as the II-VI compound semiconductor layer.
An e layer and a ZnMgSSe layer are included.

A fourth invention of the present invention is that ZnS is formed on a substrate.
After growing the e layer by molecular beam epitaxy, Zn
In a method for manufacturing a semiconductor laminated structure in which a ZnSSe layer and a ZnMgSSe layer are grown on a Se layer by a molecular beam epitaxy method, in a method for growing a ZnSe layer, the intensity of the group II element molecular beam relative to the intensity of the group VI element molecular beam The intensity ratio is 1.0 to 10.0, the intensity ratio of the group VI element molecular beam to the intensity of the group II element molecular beam during the growth of the ZnSSe layer is 1.0 to 8.2, and ZnMgSS is used.
The ratio of the intensity of the molecular beam of the group VI element to the intensity of the molecular beam of the group II element during the growth of the e layer is set to 1.0 to 8.0.

In an exemplary embodiment of the fourth aspect of the present invention, ZnSS is used as the II-VI compound semiconductor layer.
An e layer and a ZnMgSSe layer are included.

In the present invention, the substrate is typically I
A II-V compound semiconductor substrate, for example, a GaAs substrate. The surface of this GaAs substrate is preferably (2 × 4) A
s stabilization side.

In the present invention, the substrate and the ZnSe layer typically exhibit n-type conductivity.

[0027]

According to the semiconductor laminated structure according to the first aspect of the present invention, since the stacking fault density is as low as less than 10 ⁴ cm ^-2 and the crystallinity is good, the semiconductor laminated structure is used to obtain a longer life. The semiconductor light emitting device can be realized.

According to the method for manufacturing a semiconductor laminated structure according to the second aspect of the present invention, the ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam is made smaller than 1 at the initial stage of growth of the ZnSe layer. This improves the crystallinity of the initial ZnSe growth layer. Then, the initial Z having good crystallinity
The ZnSe layer is grown on the nSe growth layer at a ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam of 1 to 1.5, whereby the initial ZnS layer is grown.
The crystallinity of the ZnSe layer grown on the e-grown layer also becomes good.

According to the method for manufacturing a semiconductor laminated structure according to the third aspect of the present invention, the intensity of the Se molecular beam used during the growth of the II-VI group compound semiconductor layer is the same as that of the Se molecular beam used during the growth of the ZnSe layer. When the ZnSe layer is grown, the ZnSe layer is grown at a proper VI / II ratio, and when the II-VI group compound semiconductor layer is grown thereon, it is used as a raw material of the VI group element.
Compound raw materials containing group II elements in addition to group II elements (for example,
S generated when using ZnS or the like as an S source)
The shortage of the supplied amount of e can be compensated, and thus the II-VI group compound semiconductor layer can be grown at an appropriate VI / II ratio.

According to the method for manufacturing a semiconductor laminated structure in accordance with the fourth aspect of the present invention, I at the time of growing the ZnSe layer is I.
The ratio of the intensity of the molecular beam of the VI group element to that of the group I element is 1.0 to 10.0, and the ratio of the molecular beam of the VI group element to that of the II group element during the growth of the ZnSSe layer is The intensity ratio is 1.0 to 8.2, and V with respect to the intensity of the molecular beam of the II group element during the growth of the ZnMgSSe layer.
By setting the ratio of the intensity of the molecular beam of the group I element to 1.0 to 8.0, it is possible to properly grow VI / I of these ZnSe layer, ZnSSe layer and ZnMgSSe layer respectively.
I ratio can be used.

[0031]

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

First, the MBE apparatus used in the embodiment of the present invention will be described. FIG. 1 shows the configuration of this MBE device.

As shown in FIG. 1, in this MBE apparatus, two vacuum containers 10 and 20 are connected via a vacuum transfer path 30. Here, the vacuum container 10 is III-
It is for growing a group V compound semiconductor, and the vacuum container 20 is II-
For group VI compound semiconductor growth. These vacuum vessels 1
0 and 20 are evacuated to ultrahigh vacuum by an ultrahigh vacuum exhaust device (not shown).

A sample table 12 which can be heated by a heater 11 is installed in the vacuum container 10. Then, the substrate S to be epitaxially grown is held on the sample table 12. A plurality of molecular beam sources (K cells) 13 are attached to the vacuum container 10 so as to face the sample table 12. In this case, as the molecular beam source 13, Ga, As, and Si molecular beam sources are prepared. Reference numeral 14 indicates a shutter of each molecular beam source 13. The vacuum container 10 further includes a quadrupole mass spectrometer 15 and a reflection high-energy electron diffraction (RHEED) electron gun 1.
6 is attached. A sample exchange chamber 17 is also attached to the vacuum container 10.
Thus, the substrate S can be taken in and out of the vacuum container 10.

On the other hand, a sample table 22 which can be heated by a heater 21 is installed in the vacuum container 20.
Then, the substrate S to be epitaxially grown is held on the sample table 22. Also, the vacuum container 20
A plurality of molecular beam sources 23 facing the sample table 22.
Is attached. In this case, the molecular beam source 23 has one Zn molecular beam source and one Cd molecular beam source.
, 1 Mg molecular beam source, 2 Se molecular beam sources, Z
2 nS molecular beam sources, 1 Te molecular beam source, ZnC
One 1 ₂ molecular beam source is prepared for each. Here, conventionally, only one molecular beam source of Se was prepared, but here it is characteristic that two molecular beam sources are prepared. Reference numeral 24 indicates a shutter of each molecular beam source 23. The vacuum container 20 is further equipped with a quadrupole mass spectrometer 25 and a RHEED electron gun 26. The vacuum container 20 also has an electron cyclotron resonance (EC
R) A plasma cell 27 is attached. Reference numeral 28
Indicates the shutter of this ECR plasma cell 27. The ECR plasma cell 27 can be replaced with a radio frequency (RF) plasma cell.

In this MBE device, the vacuum container 10,
The transfer of the substrate S between the 20 can be performed by placing the substrate S on the transfer table 31 and moving the transfer table 31 in the vacuum transfer path 30 without exposing the substrate S to the atmosphere at all. You can do it.

Next, a first embodiment in which the present invention is applied to manufacture of a semiconductor laser using a II-VI group compound semiconductor will be described.

2 and 3 show this semiconductor laser, FIG. 2 is a sectional view perpendicular to the cavity length direction of this semiconductor laser, and FIG. 3 is a sectional view parallel to the cavity length direction of this semiconductor laser. . This semiconductor laser has an SCH structure.

In the method of manufacturing the semiconductor laser according to the first embodiment, first, the n-type GaAs substrate 41 is placed in the vacuum chamber 10 for growing the III-V group compound semiconductor from the sample exchange chamber 17 of the MBE apparatus shown in FIG. (See FIGS. 2 and 3) is introduced, and this n-type GaAs substrate 41 is mounted on the sample table 12. Next, the sample table 12 is heated by the heater 11 to heat the n-type GaAs substrate 41 to a predetermined growth temperature. Here, as the n-type GaAs substrate 41, for example, a substrate having a (100) plane orientation, or 1 ° or more 10 from the (100) plane in the [01-1] direction is used.
A small angle ε equal to or less than 0 °, for example, one having a main surface turned off by 4 ° is used. Also, this n-type GaAs
The substrate 41 is doped with Si, for example, as a donor impurity. Next, on the n-type GaAs substrate 41, G
As shown in FIGS. 2 and 3, by using each molecular beam source 13 of a, As, and Si, as a donor impurity, for example, Si is used.
The n-type GaAs buffer layer 42 doped with is epitaxially grown. In the epitaxial growth of the n-type GaAs buffer layer 42, the n-type GaAs substrate 41 is heated to a temperature of, for example, about 580 ° C. and the surface thereof is thermally etched to remove the surface oxide film and the like to clean the surface. You may go after it. Furthermore, n-type G
The surface of the aAs buffer layer 42 is preferably a (2 × 4) As stabilizing surface.

Next, the n-type GaAs substrate 41 on which the n-type GaAs buffer layer 42 is epitaxially grown in this manner is transferred from the vacuum container 10 for growing III-V group compound semiconductors II- through the vacuum transfer path 30. The sample table 2 is transferred to a vacuum container 20 for growing a group VI compound semiconductor,
Mount on top of 2. Next, the sample table 22 is attached to the heater 21.
Then, the n-type GaAs substrate 41 is heated to a predetermined growth temperature. Then, as shown in FIGS. 2 and 3, on the n-type GaAs buffer layer 42, the n-type ZnSe buffer layer 4 doped with Cl as a donor impurity.
3, n-type ZnS doped with Cl as a donor impurity
_w Se _1-w buffer layer 44, n-type Zn _1-p Mg _p S _q Se _1-q cladding layer 45 doped with Cl as a donor impurity, n-type Z doped with Cl as a donor impurity
nS _u Se _1-u optical waveguide layer 46, for example i-type Zn _1-z Cd
_An active layer 47 composed of a _z Se quantum well layer, a p-type ZnS _u Se _1-u optical waveguide layer 48 doped with N as an acceptor impurity, and a p-type Zn _1-p Mg _p S _q doped with N as an acceptor impurity. Se _1-q cladding layer 49, p-type ZnS _v Se _1-v doped with N as an acceptor impurity
Layer 50, p-type ZnSe contact layer 51 doped with N as an acceptor impurity, N as an acceptor impurity
P layers in which quantum well layers made of p-type ZnTe and barrier layers made of p-type ZnSe are alternately stacked.
-Type ZnSe / ZnTe multiple quantum well (MQW) layer 52 and p-type Zn doped with N as an acceptor impurity
The Te contact layer 53 is sequentially epitaxially grown.

In this case, in the epitaxial growth of the n-type ZnSe buffer layer 43, Zn, Se and Zn are used.
One Cl ₂ molecular beam source 23 is used. And
The initial growth of the n-type ZnSe buffer layer 43, for example, 1
When the thickness is about 0 atomic layer, the ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam is set to a value smaller than 1, for example, about 0.7, and the growth is performed. The ratio of the intensity of the Se molecular beam to the intensity of the molecular beam is 1 to
The n-type ZnSe buffer layer 43 having a required thickness is obtained by setting the thickness in the range of 1.5 and performing the growth. In this case, n-type ZnS
In order to set the ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam in the initial stage of growth of the e buffer layer 43 to a value smaller than 1, the Se molecular beam source 2 in the initial stage of growth is set.
The temperature of 3 is made lower than the temperature of the molecular beam source 23 of Se after that.

As described above, the n-type ZnSe buffer layer 43 is grown by setting the ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam at less than 1 at the initial growth stage. A portion of the ZnSe buffer layer 43 near the interface with the n-type GaAs buffer layer 42,
That is, the crystallinity of the initial growth layer can be improved. This indicates that when the growth surface of the n-type ZnSe buffer layer 43 was observed at the initial stage of growth by RHEED, the flatness of the growth surface was good, and two-dimensional growth occurred. It is confirmed from what was observed. Since the crystallinity of the n-type ZnSe buffer layer 43 near the interface with the n-type GaAs buffer layer 42 is good, the voltage drop at this interface portion during operation of the semiconductor laser is reduced, and the characteristics of the semiconductor laser are reduced. Can be improved or the operating voltage can be reduced.

Furthermore, as described above, the crystallinity of the initial growth layer of the n-type ZnSe buffer layer 43 is good, and the subsequent growth is performed by setting the ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam to 1. The n-type ZnSe buffer layer 43 having good crystallinity as a whole can be obtained by setting the thickness in the range of to 1.5.

On the other hand, the n-type ZnS _w Se _1-w buffer layer 4
In the epitaxial growth of the 4 and n-type ZnS _u Se _1-u optical waveguide layers 46, one molecular beam source 23 for Zn and ZnCl ₂ and one molecular beam source 2 for Se and ZnS, respectively.
Two 3 are used respectively. In addition, n-type Zn _1-p Mg _p S
_In the epitaxial growth of the _q Se _{1 -q} clad layer 45, _one molecular beam source 23 of Zn, Mg and ZnCl ₂ is used, and _two molecular beam sources 23 of Se and ZnS are used. In the epitaxial growth of the active layer 47 composed of the i-type Zn _1-z Cd _z Se quantum well layer,
One molecular beam source 23 for Cd and one molecular beam source 23 for Cd are used, and two molecular beam sources 23 for Se are used. In the epitaxial growth of the p-type ZnS _u Se _1-u optical waveguide layer 48 and the p-type ZnS _v Se _1-v layer 50, one Zn molecular beam source 23 and two Se and ZnS molecular beam sources 23 are provided. The N doping is performed by irradiating N ₂ plasma with the ECR plasma cell 27. p-type Zn _1-p Mg _p S _q S
In the epitaxial growth of the e _1-q clad layer 49, one Zn and Mg molecular beam source 23 is used, and S is used.
Two molecular beam sources 23 for e and ZnS are used, and N
Is doped by irradiating N ₂ plasma with the ECR plasma cell 27.

Thus, the n-type ZnS _w Se _1-w buffer layer 44, which is a ternary or quaternary mixed crystal semiconductor layer, and the n-type Z.
n _1-p Mg _p S _q Se _1-q clad layer 45, n-type ZnS
_u Se _1-u optical waveguide layer 46, p-type ZnS _u Se _1-u optical waveguide layer 48, p-type Zn _1-p Mg _p S _q Se _1-q cladding layer 4
9 and the epitaxial growth of the p-type ZnS _v Se _1-v layer 50 use two molecular beam sources 23 of Se, thereby compensating for the shortage of the supply amount of Se generated by using ZnS as the S raw material. As a result, these mixed crystal semiconductor layers can be grown on them at an appropriate VI / II ratio. Therefore, the crystallinity of these mixed crystal semiconductor layers can be improved.

In the epitaxial growth of the p-type ZnSe layers of the p-type ZnSe contact layer 51 and the p-type ZnSe / ZnTe MQW layer 52, one Zn and Se molecular beam source 23 is used, and N is doped by the ECR plasma cell 27. It is performed by irradiating with N ₂ plasma. In addition, the p-type ZnTe contact layer 53 and p
In the epitaxial growth of the p-type ZnTe layer of the n-type ZnSe / ZnTe MQW layer 52, one Zn and Te molecular beam source 23 is used, and N is doped by ECR.
It is performed by irradiating N ₂ plasma with the plasma cell 27.

In the first embodiment, Zn, Cd, M
The molecular beam intensities of the g, Se, ZnS, and Te molecular beam sources 23 are specifically set as follows, for example, in order to obtain an optimum VI / II ratio for growth of each layer. First, n
At the initial growth of the ZnSe buffer layer 43, Zn
The molecular beam intensity of is set to 1.3 × 10 ⁻⁶ Torr, and the molecular beam intensity of Se is set to 9.1 × 10 ⁻⁷ Torr. Next, in the subsequent growth of the n-type ZnSe buffer layer 43, the intensity of the Zn molecular beam is 1.3 ×.
The molecular beam intensity of 10 ^-6 Torr and Se is 1.5 × 10 ^-6
Torr, respectively. In addition, n-type ZnSe
In the growth of the ternary or quaternary mixed crystal semiconductor layer on the buffer layer 43, the intensity of the Zn molecular beam is 1.3 × 10 ⁻⁶ T.
The molecular beam intensity of orr and Cd is 5.0 × 10 ^-7 Tor
The molecular beam intensity of r and Mg is 1.0 × 10 ⁻⁷ Torr, 1
The molecular beam intensity of one Se is 1.5 × 10 ^-6 Torr, and the molecular beam intensity of another Se is 9.0 × 10 ^-7 Torr.
r, the intensity of one ZnS molecular beam is 5.0 × 10 ⁻⁷ To
rr, the intensity of another ZnS molecular beam is 1.2 × 10
^-6 Torr, Te molecular beam intensity is 3.0 × 10 ^-7 To
It is set to rr.

At this time, the VI / II ratio at the initial growth of the n-type ZnSe buffer layer 43 is 0.7, and the VI / I ratio at the subsequent growth of the n-type ZnSe buffer layer 43 is VI / I.
I ratio is 1.15, n-type ZnS _w Se _1-w buffer layer 4
4, n-type ZnS _u Se _1-u optical waveguide layer 46, p-type ZnS _u
Se _1-u optical waveguide layer 48 and p-type ZnS _v Se _1-v layer 5
VI / II ratio during growth of 0 is 1.11 and n-type Zn
_1-p Mg _p S _q Se _1-q clad layer 45 and p-type Zn
The VI / II ratio during the growth of the _1-p Mg _p S _q Se _1-q cladding layer 49 is 1.44. In addition, i-type Zn _1-z
The VI / II ratio during growth of the active layer 47 made of the Cd _z Se quantum well layer is 1.33.

In the first embodiment, n-type Zn _1-p
Mg _p S _q Se _1-q cladding layer 45 and p-type Zn _1-p
The Mg composition ratio p of the Mg _p S _q Se _1-q cladding layer 49 is, for example, 0.09, and the S composition ratio q is, for example, 0.18. These Mg composition ratio p = 0.09 and S composition ratio q = 0.
The n-type Zn _1-p Mg _p S _q Se _1-q cladding layer 45 and the p-type Zn _1-p Mg _p S _q Se _1-q cladding layer 49 having 18 are lattice-matched with GaAs. The Cd composition ratio z of the i-type Zn _1-z Cd _z Se quantum well layer forming the active layer 47 is selected according to the emission wavelength, but is 0.19, for example. On the other hand, the n-type ZnS _w Se _1-w buffer layer 44, the n-type ZnS _u Se _1-u optical waveguide layer 46, and the p-type ZnS _u Se _1-u.
The S composition ratio u of the optical waveguide layer 48 and the p-type ZnS _v Se _1-v layer 50 is such that the n-type Zn _1-p Mg _p S _q Se _1-q cladding layer 45 and the p-type Zn _1-p Mg _p S _q. From the viewpoint of achieving lattice matching with the Se _1-q cladding layer 49, 0.06 is most preferable.

[0050] In this case, the thickness of the n-type GaAs buffer layer 42 is for example _{0.25μm, N D -N A (N} D: donor concentration, N _A: acceptor concentration), for example 2 × 10 ¹⁸ cm
^-3 . The thickness of the n-type ZnSe buffer layer 43 is Zn
Se selected sufficiently smaller than the critical film thickness (~ 100 nm) of, here, for example 20 nm, N _D -N _A is for example 5
It is × 10 ¹⁷ cm ^-3 . The thickness of the n-type ZnS _w Se _1-w buffer layer 44 is for example 100nm, N _D -N _A is for example 5 × 10 ¹⁷ cm ^-3. n-type Zn _1-p Mg _p S _q Se
_1-q thickness, for example 1μm cladding layer 45, N _D -N _A
Is, for example, 5 × 10 ¹⁷ cm ⁻³ . In addition, n-type ZnS _u
The Se _1-u optical waveguide layer 46 has a thickness of, for example, 90 nm, N _D −
N _A is, for example, 5 × 10 ¹⁷ cm ⁻³ . On the other hand, p-type Zn
S _u Se _1-u thickness of the optical waveguide layer 48 is for example 90 nm, N
_A −N _D is, for example, 1 × 10 ¹⁸ cm ⁻³ . p-type Zn
The thickness of the _{1-p Mg p S q Se} 1-q cladding layer 49 is, for example 1μm, N _A -N _D is, for example, 2 × 10 ¹⁷ cm ^-3.
The p-type ZnS _v Se _1-v layer 50 has a thickness of, for example, 200 n.
m and N _A -N _D are, for example, 1 × 10 ¹⁸ cm ⁻³ . The p-type ZnSe contact layer 51 has a thickness of 100 nm, for example.
N _A -N _D is, for example, 1 × 10 ¹⁸ cm ⁻³ . p-type Zn
The thickness of the Te contact layer 53 is, for example, 40 nm, N _A −
N _D is, for example, 1 × 10 ¹⁹ cm ⁻³ .

Next, after each layer is epitaxially grown by the MBE method as described above, a stripe-shaped resist pattern (not shown) having a predetermined width is formed by lithography on the p-type ZnTe contact layer 53, and this resist is formed. Using the pattern as a mask, the p-type ZnS _v Se _1-v layer 50 is etched halfway in the thickness direction by wet etching. As a result, p-type ZnS _v Se _1-v
The upper layer portion of the layer 50, the p-type ZnSe contact layer 51, the p-type ZnSe / ZnTe MQW layer 52, and the p-type ZnTe contact layer 53 are patterned in a stripe shape.

Next, an Al ₂ O ₃ film was vacuum-deposited on the entire surface while leaving the resist pattern used for the above-mentioned etching, and this resist pattern was formed on top of A.
It is removed together with the l ₂ O ₃ film (lift-off). As a result, p-type ZnS _v Se _{1-v in the} part other than the stripe part
An insulating layer 54 made of an Al ₂ O ₃ film is formed only on the layer 50.

Next, a Pd film, a Pt film, and an Au film are sequentially vacuum-deposited on the entire surfaces of the stripe-shaped p-type ZnTe contact layer 53 and the insulating layer 54 to form a p-side electrode 55 composed of a Pd / Pt / Au electrode. Then, heat treatment is performed as necessary to bring the p-side electrode 55 into ohmic contact with the p-type ZnTe contact layer 53. On the other hand, n-type GaAs
An n-side electrode 56 such as an In electrode is formed on the back surface of the substrate 41.

After that, the n-type GaAs substrate 41 having the laser structure formed as described above is cleaved in a bar shape to form both resonator end faces, and thereafter, Al is formed on the front end face by, for example, a vacuum deposition method. _A multilayer film including a ₂ O ₃ film 57 and a Si film 58 is formed, and Al ₂ is formed on the rear end surface.
A multilayer film is formed by repeating the O ₃ film 57 and the Si film 58 for two cycles. After the end face coating is applied in this manner, the bar is cleaved to form chips, and packaging is performed.
Here, the thickness of the multilayer film composed of the Al ₂ O ₃ film 57 and the Si film 58 is selected so that the optical distance obtained by multiplying the refractive index thereof is equal to 1/4 of the oscillation wavelength of the laser light. . By applying such end face coating, for example, the reflectance of the front end face can be 70% and the reflectance of the rear end face can be 95%.

The p-type ZnS _v Se _1-v layer 50 functions as a second p-type clad layer in addition to the p-type Zn _1-p Mg _p S _q Se _1-q clad layer 49 in some cases. , A function of achieving lattice matching with the p-type Zn _1-p Mg _p S _q Se _1-q clad layer 49, and preventing a short circuit due to the creeping up of the solder on the chip end face when mounting the laser chip on the heat sink. Has one or more of the functions as a spacer layer.

The p-type ZnSe / ZnTe MQW layer 5
In No. 2, when the p-type ZnSe contact layer 51 and the p-type ZnTe contact layer 53 are directly bonded, a large band discontinuity of about 0.8 eV is generated in the valence band at the bonding interface, which is injected from the p-side electrode 55. The holes are p
This is a barrier for moving from the p-type ZnSe contact layer 51 to the p-type ZnSe contact layer 53, so that this barrier is effectively eliminated. This p-type ZnSe
In the / ZnTe MQW layer 52, for example, p-type Zn
The thickness of the quantum well layer is such that the first quantum level E ₁ formed in each of the quantum well layers made of Te matches the energy at the top of the valence band of p-type ZnSe and p-type ZnTe and is equal to each other. That is, the well width L _W is changed stepwise. In this case, from the p-side electrode 55 to the p-type ZnTe
The holes injected into the contact layer 53 are the p-type ZnT.
After passing through the e-contact layer 53, p-type ZnSe / ZnT
First formed in each quantum well of the eMQW layer 52
Resonant tunneling via the quantum level E ₁ causes p-type Zn
P-type Zn that can flow to the Se contact layer 51 side
Se contact layer 51 and p-type ZnTe contact layer 53
The potential barrier at the interface of the junction with is effectively eliminated.

As described above, according to the first embodiment,
The initial growth of the n-type ZnSe buffer layer 43 is VI / II.
The growth is performed with the ratio, that is, the ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam being less than 1, and in the subsequent growth of the n-type ZnSe buffer layer 43, the Se with respect to the intensity of the Zn molecular beam. The ratio of the molecular beam intensities of 1 to
Since the growth is performed at 1.5, it is possible to grow the n-type ZnSe buffer layer 43 having good crystallinity including the interface with the n-type GaAs buffer layer 42. In addition, n-type Z that is a ternary or quaternary mixed crystal semiconductor layer
nS _w Se _1-w buffer layer 44, n-type Zn _1-p Mg _p S
_q Se _1-q clad layer 45, n-type ZnS _u Se _1-u optical waveguide layer 46, p-type ZnS _u Se _1-u optical waveguide layer 48, p-type Z
n _1-p Mg _p S _q Se _1-q cladding layer 49 and p-type Z
In the growth of the nS _v Se _1-v layer 50, by using two Se molecular beam sources 23, and thus two Se molecular beams at the same time, it is possible to properly grow these mixed crystal semiconductor layers. VI / II ratio, and thereby the crystallinity of these mixed crystal semiconductor layers can be improved. In addition, from the cross-sectional observation with a transmission electron microscope (TEM), it was found that the undulations in the vicinity of the active layer 47, which were conventionally seen, disappeared and the layer surface was flat. As a result, it is possible to reduce the light emission loss due to the undulations near the active layer 47.

As described above, a semiconductor laser having good characteristics and a long life can be realized.

Next, a second embodiment of the present invention will be described.

In the method of manufacturing a semiconductor laser according to the first embodiment described above, in order to grow a ternary or quaternary mixed crystal semiconductor layer with an appropriate VI / II ratio for them, Se is grown during their growth. Two molecular beam sources 23 are used,
In the method of manufacturing the semiconductor laser according to the second embodiment, only one molecular beam source 23 is used during the growth of these mixed crystal semiconductor layers, and Se molecules are used instead during the growth of these mixed crystal semiconductor layers. The temperature of the radiation source 23 is set to n-type ZnS.
The height is made higher than that when the e-buffer layer 43 is grown. And
As a result, the intensity of the Se molecular beam during the growth of these mixed crystal semiconductor layers is increased, and these mixed crystal semiconductor layers are appropriately added to them as in the case of using two Se molecular beam sources 23. Grow at a VI / II ratio.

Since the other parts of the method of manufacturing the semiconductor laser according to the second embodiment are the same as those of the method of manufacturing the semiconductor laser according to the first embodiment, the description thereof will be omitted.

The same advantages as those of the first embodiment can be obtained also by the second embodiment.

Next, a third embodiment of the present invention will be described.

In the method of manufacturing the semiconductor laser according to the third embodiment, the method of initial growth of the n-type ZnSe buffer layer 43 is different from that of the first embodiment. That is, in the method of manufacturing the semiconductor laser according to the first embodiment, the n-type Z
By setting the temperature of the Zn molecular beam source 23 at the beginning of the growth of the nSe buffer layer 43 to be low, the ratio of the intensity of the Se molecular beam to that of the Zn molecular beam at the beginning of the growth of the n-type ZnSe buffer layer 43 is set to 1 or less. However, in the method for manufacturing the semiconductor laser according to the third embodiment, the so-called migration enhanced epitaxy (MEE) growth is performed at the beginning of the growth of the n-type ZnSe buffer layer 43. Achieve something. Specifically, at the initial stage of growth of the n-type ZnSe buffer layer 43, as shown in FIG. 4, the shutter for the molecular beam source of Zn is left open immediately after the growth is started, and the shutter for the molecular beam source of Se is opened. MEE growth is performed by repeatedly opening and closing. The time t _{1 for} which the shutter of the molecular beam source of Se in FIG. 4 is open and the time t ₂ for which the shutter is closed are, for example, 5 seconds each.

Since the other parts of the method of manufacturing the semiconductor laser according to the third embodiment are the same as those of the method of manufacturing the semiconductor laser according to the first embodiment, the description thereof will be omitted.

The same advantages as those of the first embodiment can also be obtained by the third embodiment.

As described above, in any of the first, second and third embodiments, n-type Zn is used.
Se buffer layer 43, n-type ZnS _w Se _1-w buffer layer 44 which is a ternary or quaternary mixed crystal semiconductor layer, n-type Zn
_1-p Mg _p S _q Se _1-q cladding layer 45, n-type ZnS _u
Se _1-u optical waveguide layer 46, p-type ZnS _u Se _1-u optical waveguide layer 48, p-type _{Zn 1-p Mg p S q} Se 1-q cladding layer 49
And, the crystallinity of the p-type ZnS _v Se _1-v layer 50 can be improved, but here, an example of the measurement result of the stacking fault density that confirms that the crystallinity is good will be described. To do.

The sample used for measuring the stacking fault density is
It was produced as follows. First, the n-type GaAs is formed on the n-type GaAs substrate 41 by the same process as in the first embodiment.
The semiconductor layered structure is manufactured by sequentially epitaxially growing the buffer layer 42 to the p-type ZnTe contact layer 53. Here, the MEE growth described in the third embodiment was used for the growth of the n-type ZnSe buffer layer 43. Next, n-type Ga
An In electrode is formed as an n-side electrode 56 on the back surface of the As substrate 41, and an Au electrode having a thickness of 5 nm and having a window partially opened is formed as a p-side electrode 55 on the p-type ZnTe contact layer 53. Thereby, the sample is prepared.

The stacking fault density is measured by energizing the sample manufactured as described above between the p-side electrode 55 and the n-side electrode 56 and measuring the number of black dots observed in the window of the Au electrode. Went by. As a result, the stacking fault density was 1.3.
It was extremely low at × 10 ³ cm ^-2 .

The embodiments of the present invention have been specifically described above, but the present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the technical idea of the present invention.

For example, in the above-mentioned embodiments, the i-type Zn _1-z Cd _z Se quantum well layer is used as the active layer 47, but the active layer 47 is, for example, ZnCdSe.
An MQW layer such as / ZnSe may be used.

Although the n-type GaAs substrate 41 is used as the substrate in the above-mentioned embodiment, another III-V group compound semiconductor substrate or II-VI substrate may be used as this substrate. Group compound semiconductor substrate, eg Zn
An Se substrate may be used.

Further, in the above embodiment, the SCH
The case where the present invention is applied to the manufacture of a semiconductor laser having a structure has been described.
It is of course possible to apply not only a semiconductor laser having a structure (Double Heterostructure) but also, for example, to manufacturing a light emitting diode.

Further, in the above-described embodiment, each layer is grown using the MBE apparatus shown in FIG. 1. However, the MBE apparatus shown in FIG. 1 is merely an example, and an MBE apparatus having a different structure from this is used. May be used for growth.

[0075]

As described above, according to the semiconductor laminated structure according to the first aspect of the present invention, the stacking fault density is 1 or less.
When it is as low as less than 0 ⁴ cm ^-2 , it is possible to realize a semiconductor laminated structure having good crystallinity including a ZnSe layer.

According to the method for manufacturing a semiconductor laminated structure according to the second aspect of the present invention, the ZnSe layer is grown with the ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam being smaller than 1 at the initial stage of growth. Then, the ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam is set to 1 to 1.5 and Z
Since the nSe layer is grown, a semiconductor laminated structure including a ZnSe layer having good crystallinity can be manufactured.

According to the method for manufacturing a semiconductor laminated structure according to the third aspect of the present invention, the intensity of the Se molecular beam used during the growth of the II-VI compound semiconductor layer is the same as that of the Se molecular beam used during the growth of the ZnSe layer. Since the strength is higher than the strength, it is possible to manufacture a semiconductor laminated structure including a II-VI group compound semiconductor layer having good crystallinity.

According to the method for manufacturing a semiconductor laminated structure in accordance with the fourth aspect of the present invention, I at the time of growing the ZnSe layer is I.
The ratio of the intensity of the molecular beam of the VI group element to that of the group I element is 1.0 to 10.0, and the ratio of the molecular beam of the VI group element to that of the II group element during the growth of the ZnSSe layer is The intensity ratio is 1.0 to 8.2, and V with respect to the intensity of the molecular beam of the II group element during the growth of the ZnMgSSe layer.
Since the ratio of the intensity of the molecular beam of the group I element is set to 1.0 to 8.0, it is possible to manufacture a semiconductor laminated structure including a II-VI group compound semiconductor layer having good crystallinity.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an MBE device used in an embodiment of the present invention.

FIG. 2 is a sectional view perpendicular to the cavity length direction of the semiconductor laser manufactured according to the first embodiment of the present invention.

FIG. 3 is a sectional view parallel to the cavity length direction of the semiconductor laser manufactured according to the first embodiment of the present invention.

FIG. 4 is a sequence diagram of opening and closing of a shutter of a molecular beam source of Zn and a shutter of a molecular beam source of Se in an initial stage of growth of an n-type ZnSe buffer layer in a method for manufacturing a semiconductor laser according to a third embodiment of the present invention.

[Explanation of symbols]

10, 20 Vacuum container 30 Vacuum transfer path 41 n-type GaAs substrate 42 n-type GaAs buffer layer 43 n-type ZnSe buffer layer 44 n-type ZnS _w Se _1-w buffer layer 45 n-type Zn _1-p Mg _p S _q Se _{1 -q} clad layer 46 n-type ZnS _u Se _1-u optical waveguide layer 47 active layer 48 p-type ZnS _u Se _1-u optical waveguide layer 49 p-type Zn _1-p Mg _p S _q Se _1-q clad layer 50 p ZnS _v Se _1-v layer 51 p-type ZnSe contact layer 52 p-type ZnSe / ZnTe MQW layer 53 p-type ZnTe contact layer 54 insulating layer 55 p-side electrode 56 n-side electrode

Claims (27)

[Claims] 1. A ZnSe layer laminated on a substrate, and at least one II-layer laminated on the ZnSe layer.
A Group VI compound semiconductor layer, and a stacking fault density of less than 10 ⁴ cm ^-2 . 2. The semiconductor laminated structure according to claim 1, wherein the substrate is a III-V group compound semiconductor substrate. 3. The III-V compound semiconductor substrate is G
The semiconductor laminated structure according to claim 2, wherein the semiconductor laminated structure is an aAs substrate. 4. The surface of the GaAs substrate is (2 × 4) A
The semiconductor laminated structure according to claim 3, wherein the semiconductor laminated structure is an s-stabilized surface. 5. Z is formed in the II-VI compound semiconductor layer.
The semiconductor multilayer structure according to claim 1, further comprising an nSSe layer and a ZnMgSSe layer. 6. The semiconductor laminated structure according to claim 1, wherein the substrate and the ZnSe layer exhibit n-type conductivity. 7. A method for manufacturing a semiconductor laminated structure in which a ZnSe layer is grown on a substrate by a molecular beam epitaxy method, wherein the ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam is set to 1 at the initial stage of growth. And a ZnSe layer is grown to a small value, and then the ZnSe layer is grown with a ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam of 1 to 1.5. Method of manufacturing structure. 8. The S relative to the intensity of the Zn molecular beam at the initial stage of growth by repeatedly opening and closing the shutter of the Se molecular beam source with the shutter of the Zn molecular beam source open.
8. The method for manufacturing a semiconductor laminated structure according to claim 7, wherein the ratio of the effective intensity of the molecular beam of e is smaller than 1. 9. The ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam at the initial stage of growth is set by lowering the temperature of the Se molecular beam source at the initial stage of growth below the temperature of the Se molecular beam source thereafter. The method for manufacturing a semiconductor laminated structure according to claim 7, wherein the method is smaller than 1. 10. The method for manufacturing a semiconductor laminated structure according to claim 7, wherein the substrate is a III-V group compound semiconductor substrate. 11. The method according to claim 10, wherein the III-V compound semiconductor substrate is a GaAs substrate. 12. The surface of the GaAs substrate is (2 × 4)
The method for manufacturing a semiconductor laminated structure according to claim 11, wherein the method is an As stabilizing surface. 13. The method for manufacturing a semiconductor multilayer structure according to claim 7, wherein the substrate and the ZnSe layer have n-type conductivity. 14. A method for producing a semiconductor laminated structure, wherein a ZnSe layer and at least one multi-element II-VI compound semiconductor layer containing at least Se are sequentially grown on a substrate by a molecular beam epitaxy method. Se used during growth of Group VI compound semiconductor layer
The intensity of the molecular beam of Se used for growing the above ZnSe layer
The method for producing a semiconductor laminated structure is characterized in that the strength of the molecular beam is higher than that of the molecular beam. 15. The Se layer is grown when the ZnSe layer is grown.
The molecular beam of Se used for the growth of the II-VI group compound semiconductor layer is increased by using one molecular beam of the above and two molecular beams of the Se for growth of the II-VI group compound semiconductor layer. 15. The method for manufacturing a semiconductor laminated structure according to claim 14, wherein the intensity is higher than the molecular beam intensity of Se used during the growth of the ZnSe layer. 16. The II-VI group by increasing the temperature of the Se molecular beam source during the growth of the II-VI group compound semiconductor layer above the temperature of the Se molecular beam source during the growth of the ZnSe layer. 15. The method of manufacturing a semiconductor laminated structure according to claim 14, wherein the intensity of the Se molecular beam used during the growth of the compound semiconductor layer is made higher than the intensity of the Se molecular beam used during the growth of the ZnSe layer. 17. The ZnSe layer is grown with the ratio of the intensity of the Se molecular beam to the intensity of the Zn molecular beam being less than 1 at the initial stage of growth of the ZnSe layer, and then the Se relative to the Zn molecular beam intensity. 15. The method for manufacturing a semiconductor laminated structure according to claim 14, wherein the ZnSe layer is grown with a ratio of the intensity of the molecular beam of 1 to 1.5. 18. The method for manufacturing a semiconductor laminated structure according to claim 14, wherein the II-VI group compound semiconductor layer includes a ZnSSe layer and a ZnMgSSe layer. 19. The method of manufacturing a semiconductor laminated structure according to claim 14, wherein the substrate is a III-V compound semiconductor substrate. 20. The method of manufacturing a semiconductor multilayer structure according to claim 14, wherein the III-V compound semiconductor substrate is a GaAs substrate. 21. The surface of the GaAs substrate is (2 × 4)
21. The method for manufacturing a semiconductor laminated structure according to claim 20, which is an As stabilizing surface. 22. The method of manufacturing a semiconductor laminated structure according to claim 14, wherein the substrate and the ZnSe layer have n-type conductivity. 23. A ZnSe layer is grown on a substrate by a molecular beam epitaxy method, and then ZnS is grown on the ZnSe layer.
In a method for manufacturing a semiconductor laminated structure in which a Se layer and a ZnMgSSe layer are grown by a molecular beam epitaxy method, a ratio of the intensity of the group VI element molecular beam to the intensity of the group II element molecular beam during the growth of the ZnSe layer is described. 1.0 to
10.0, the ratio of the intensity of the molecular beam of the VI group element to the intensity of the molecular beam of the II group element during the growth of the ZnSSe layer is 1.0 to 8.2, and the intensity of the II group element during the growth of the ZnMgSSe layer is 1.0 to 8.2. A method for manufacturing a semiconductor laminated structure, wherein the ratio of the intensity of the molecular beam of the VI group element to the intensity of the molecular beam is 1.0 to 8.0. 24. The method of manufacturing a semiconductor laminated structure according to claim 23, wherein the substrate is a III-V compound semiconductor substrate. 25. The method for manufacturing a semiconductor laminated structure according to claim 24, wherein the III-V compound semiconductor substrate is a GaAs substrate. 26. The surface of the GaAs substrate is (2 × 4)
26. The method for manufacturing a semiconductor laminated structure according to claim 25, which is an As-stabilized surface. 27. The method of manufacturing a semiconductor laminated structure according to claim 23, wherein the substrate and the ZnSe layer have n-type conductivity.