JPH09289190A - Mesa forming method and quantum fine line device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a quantum fine line structure of II-VI semiconductor which can be easily formed by an MBE method without using a V-shaped trench. SOLUTION: An N-type ZnSe layer 102, an active layer 103 of ZnCdSe, a P-type ZnSe layer 104 are laminated on an N-type GaAs substrate 101. This laminated structure is etched and a mesastripe 105 is formed. A quantum fine line structure 106 is formed in the mesastripe 105. The mesastripe 105 and the quantum fine line structure 106 are buried in a buried layer 107. The buried layer 107 is so etched that the mesastripe 105 is exposed, and an aperture 108 is formed. A contact layer 109 doped in a P-type is crystal-grown on the buried layer 107 on which the aperture 108 is formed. By this structure, width and thickness of the quantum fine line are arbitrarily selected in II-VI semiconductor material, and formation is enabled with excellent reproducibility. Then a quantum fine line structure of high performance can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor quantum wire structure, a semiconductor light emitting device using the same, an etching method and a method for manufacturing a light emitting device using the same.
In particular, the present invention relates to a semiconductor laser which is made of a II-VI group compound semiconductor and oscillates in a blue / green region, and a manufacturing method thereof using etching and the MBE method.

[0002]

2. Description of the Related Art Development has been actively conducted to realize ultra-low threshold lasers by forming low-dimensional quantum structures such as quantum wires and quantum boxes by etching or crystal growth on a patterned substrate. . The conventional crystal growth method of quantum wires for GaAs-based semiconductor materials is described in, for example, Applied Physics Letters, Vol. 55, No. 26, pp. 2715 to 2717 (1989) (Applied Physics Lett.
ers 55 (26) (1989) pp.2715-2717).

FIG. 7 shows a part of a fine wire structure forming process at the time of forming a quantum thin wire laser using a MOCVD (Metal Organic Chemical Vapor Deposition) method, which is an example of a conventional GaAs-based quantum wire crystal growth method. , 701 is n + -Ga
As substrate, 702 is n-GaAs buffer layer, 703 is n-Al0.5Ga0.5As clad layer, and 704 is n-Al.
xGa1-xAs (x = 0.5 to 0.2 continuously changing) waveguiding layer, 705 is a GaAs quantum well layer, 706 is a crescent-type GaAs quantum wire layer, and 707 is p-AlxGa1-.
xAs (continuously changing from 0.5 to 0.2) waveguide layer, 70
8 is p-Al0.5Ga0.5As cladding layer, 709 is p +
-GaAs cap layer, 801 is a high resistance layer into which proton (H +) ions have been implanted, and 802 is a p-type electrode of Ti /
It is an Au layer. A quantum wire laser is formed in the following steps (a) to (d).

(A) A pattern is formed on the n + -GaAs substrate 701 along the (0-11) direction by lithography, and a V-shaped groove is formed by etching.

(B) n-GaAs buffer layer 702,
n-Al0.5Ga0.5As cladding layer 703, n-Alx
Ga1-xAs (x = 0.5 to 0.2 continuously changes) Waveguide layer 704, GaAs quantum wire layer 705, Crescent type Ga
As quantum wire layer 706, p-AlxGa1-xAs (x
= Continuously changing from 0.5 to 0.2) Waveguide layer 707, p-Al
The n + -GaAs substrate 7 in which the V-shaped groove is formed by using the 0.5 Ga0.5 As clad layer 708 and the p + -GaAs cap layer 709 by the metal organic chemical vapor deposition method (MOVPE method).
01 crystal is grown.

(C) A mask is placed so as to cover a part of the V-shaped groove, and proton (H +) ions are implanted to obtain 72.
The region 1 is made high in resistance. (D) After removing the mask used for the ion implantation, Ti / Au is vapor-deposited to form a p-type electrode 722.

[0007]

However, in the conventional method, it was difficult to arbitrarily control the thickness and width of the crescent-shaped portion forming the quantum wire. It was also difficult to control the thickness and width of the crescent-shaped part independently.

Further, since it is necessary to fill the V-shaped groove by MOVPE method, it is difficult to apply this method to II-VI group semiconductor materials for which crystal growth and doping control method by MOVPE method has not been established. there were.

Therefore, in the present invention, a V-shaped groove which has been conventionally used for realizing a quantum wire structure is not used, and a manufacturing method of a structure which can be easily formed by the MBE method, a II-VI group semiconductor is provided. It is an object of the present invention to provide a method of manufacturing an applicable structure and a method of manufacturing a structure in which the width and thickness of a quantum wire structure are arbitrarily controlled, and the width and thickness of a quantum wire structure are independently controlled. .

[0010]

In order to achieve the above object, in the mesa forming method and quantum wire structure of the present invention, II-VI is used.
The quantum well structure formed of a group-based semiconductor layer is etched with an etchant containing K ₂ Cr ₂ O ₇ (dichromic acid) to form a sharp mesa structure.

[0011] The composition of the etchant K ₂ Cr ₂ O ₇ solution and aqueous solution _of H ₂ SO ₄ used for etching in the configuration at a volume ratio of 2: has been mixed at a ratio of 1, Part K ₂ Cr ₂ O ₇ The concentration of the aqueous solution is 0.1 to 0.3 mol /
1, and the concentration of the H ₂ SO ₄ aqueous solution is 9 to 18 mol / l.

A quantum wire formed by etching a quantum well structure having a ZnSe semiconductor layer as a quantum well layer and a ZnSe semiconductor layer having a larger bandgap as a barrier layer with the above etchant is used as an active layer. It is characterized by having as.

Further, the above-mentioned etching is characterized in that an inverse mesa shape is formed by selecting the azimuth of the stripe to form a quantum wire structure.

Further, the reverse mesa side surface is a {221} B surface, and the stripe direction is <1-10>.

Further, the width of the quantum wire is 10 nm or less. The width of the upper surface of the mesa is 0.
It is characterized by being 5 μm or more.

Further, a layer having a refractive index lower than that of the active layer is provided as a buried layer on the side surface of the inverted mesa.

The embedding layer is Zn1-xMgxSySe1
-y (0≤x≤1, 0≤y≤1).

A II-VI group compound semiconductor is used as a quantum well layer, and the band gap is larger than that of the quantum well layer.
It is characterized by having a Group VI compound semiconductor layer as a barrier layer.

The active region has an SCH structure including a quantum well layer, an optical guide layer sandwiching the quantum well layer, and a cladding layer sandwiching the optical guide layer.

The quantum well layer and the barrier layer are made of ZnC.
dSe, ZnSe, ZnSSe, ZnS, ZnMgS,
The quantum well layer is selected from ZnMgSSe and has a bandgap smaller than that of the barrier layer.

The quantum wire laser according to claim 2, further comprising an etching stop layer below the quantum well layer.

The etching stop layer is InGaAs,
It is characterized by being selected from GaAs, AlGaAs, and AlAs.

A quantum well layer is formed directly on the etching stop layer.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a semiconductor laser according to the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a diagram showing a manufacturing process of a semiconductor laser according to a first embodiment of the present invention.

As shown in FIG. 1A, an n-type GaAs substrate (which may be an n-type InP substrate or an n-type ZnSe substrate) 101.
N-type ZnSe (n-type ZnSSe, n-type ZnMgS
Se) 102, ZnCdSe (ZnSe, Z
nCdS, ZnSSe, ZnS) active layer 10
3, p-type ZnSe (p-type ZnSSe, p-type ZnMgSS
e may be used) layer 104 is laminated.

Next, a mask having an appropriate width and an appropriate performance is formed in a stripe shape on the p-type ZnSe layer 104, and the laminated structure is etched to form a mesa stripe 105 as shown in FIG. 1B. Form. At this time, the quantum wire structure 106 is formed in the mesa stripe 105 by etching to a depth deeper than the quantum well structure 103.

The etchant used for etching is K
An etchant containing 2Cr2O7 is used. This etchant has a composition in which a K2Cr2O7 aqueous solution and a H2SO4 aqueous solution are mixed at a volume ratio of 2: 1 and the concentration of the K2Cr2O7 aqueous solution is 0.1 to 0.3 mol.
/ L, the concentration of H2SO4 aqueous solution is 9-18 mol / l
It is.

A good mesa shape can be obtained by etching using this etchant. When the cross section is observed under a scanning electron microscope (SEM), the etched surface is flat, straight and not curved. Further, by selecting the direction of the mesa stripe, the reverse mesa shape and the forward mesa shape can be selected. For example, when <1-10> is selected as the mesa stripe direction, the mesa shape is an inverted mesa. The surface index appearing in the mesa shape obtained with this etchant is the (221) B surface.

Next, as shown in FIG. 1C, a mesa stripe shape is buried with an undoped buried layer 107 having a lower refractive index than the quantum wire structure 106 which is an active layer. Since this buried layer 107 is undoped, it simultaneously functions as an insulating layer. At this time, the material of the buried layer 107 is ZnCdSe, ZnSe, ZnSSe, ZnS, Zn.
MgSSe is selected so as to be lattice-matched to the substrate 101 and have a lower refractive index than the quantum wire structure 106.
For example, the substrate 101 is GaAs, and the quantum wire structure 10
When 6 is composed of ZnCdSe, this buried layer is, for example, ZnSSe.

At this time, the buried layer 107 is, for example, a molecular beam crystal growth method (MBE) method or a metal organic chemical vapor deposition method (MOVP).
Grow according to E). The molecular beam source for this MBE method is, for example, ZnSe, ZnS, CdSe, ZnTe, Mg.
A compound source such as Se or MgS is used.

Next, as shown in FIG. 1C, the buried layer 107 in which the quantum wire structure 105 is buried is etched so that the quantum wire structure 105 is exposed to form an opening 108. For etching, for example, K2Cr2O as described above is used.
An etchant containing 7 or an etchant containing saturated bromine water is used.

Next, as shown in FIG. 1D, a p-type doped contact layer 109 is crystal-grown on the buried layer 107 having the opening 108. This contact layer 109
For example, ZnSe, ZnTe, a multiple quantum well layer of ZnSe and ZnTe, a pseudo-mixed crystal layer, or the like can be considered as the material. Similarly, as shown in FIG. 1D, a p-type electrode is formed on the contact layer 109 by vapor deposition, and an n-type electrode 111 is formed on the surface of the n-type substrate 101 by vapor deposition. At this time, for example, Au is used for the p-type electrode.
/ Ag / Ni, Au / Pt / Ti / Ni, Au / P
t, etc. are conceivable. The last metal written in each electrode layer is in contact with the p-type contact layer. Further, for example, Au / Ge / Ni / Ti / Pt / Au is used for the n-type electrode layer.
And Au / Ge / Au are conceivable. Also at this time, the last written metal in each electrode layer is in contact with the n-type contact layer. In the above structure, the contact layer 10
9 is not necessary.

The structure created in the above process exhibits the quantum effect by forming the quantum wire 106 so that the width thereof is sufficiently narrow, and has a characteristic such as an ultra-low threshold value or a wavelength shortening. It becomes a thin line laser.

The quantum thin line structure laser is used for the quantum thin line 106.
In order for to express the quantum effect, its width must be thin enough. For example, its size is 10n in both width and thickness.
m. In the present invention, the width and thickness of the quantum wire 106 can be arbitrarily controlled.

One of them is to grow crystals to an appropriate thickness when the quantum well layer 103 is first formed in FIG. The thickness of the quantum well layer 103 is equal to the thickness of the quantum wire 106. The other is to form the mesa stripe 105 by etching to narrow the width. The width before mesa etching is equal to the width of the substrate. After forming the mesa by etching, the width of the quantum wire 106 can be arbitrarily determined by the etching depth and the position of the quantum well layer.

FIG. 8 schematically shows the relationship between the position of the quantum well layer and the formation of the mesa by etching and the width of the quantum wire layer.

The width of the stripe mask used when forming the mesa stripe by etching as shown in FIG.
Alternatively, the width of the upper end of the mesa stripe that is slightly smaller than the stripe mask after etching and is left is W. The angle formed by the side surface and the upper surface of the inverted mesa shape formed by etching is θ. The depth from the upper surface of the mesa to the quantum wire structure is h. The width of the obtained quantum wire is ω. In this case, the respective relations are given by the following equation (1).

H = (W−ω) / 2tan (90−θ) (1) (Example 2) Next, a case where an etching stopper layer is used when forming a mesa shape by etching will be described. .

Similar to FIG. 1, FIG. 2 shows a cross section of the layer structure before etching and the structure after completion of the quantum wire laser structure. 2A and 2B correspond to FIGS. 1A and 1D, respectively. 1B and 1C are omitted because they are similar steps.

As shown in FIG. 2A, an n-type GaAs substrate (which may be an n-type InP substrate or an n-type ZnSe substrate) 201.
N-type ZnSe cladding (n-type ZnSSe, n-type Z
nMgSSe layer 202, GaAs etching stopper layer (AlAs, AlGaAs, InGaAs)
203), a second n-type ZnSe clad (which may be n-type ZnSSe or n-type ZnMgSSe) layer 204,
ZnCdSe (ZnSe, ZnCdS, ZnSSe, Z
nS) active layer 205, p-type ZnSe cladding (p-type ZnSSe, p-type ZnMgSSe may be) layer 2
06 are stacked.

Next, a mask having an appropriate width and an appropriate performance is formed in a stripe shape on the p-type ZnSe clad layer 206, and this laminated structure is etched to form a mesa stripe 207 as in FIG. 1B. To form. At this time, by performing etching to a depth deeper than the quantum well structure 205, the quantum wire structure 2 is formed in the mesa stripe 207.
08 is formed. Further, the etching depth is automatically stopped because of the etching stopper layer 203. Therefore, it is easy to control the etching depth with high precision, which greatly contributes to the improvement of the yield.

Therefore, the depth of the mesa is p-type clad layer 2
06, quantum well layer 205, second n-type cladding layer 204
It is the sum of the thickness of.

At this time, an etchant containing K2Cr2O7 was used as the etchant used in the etching in Example 1.
Similar to that of. The mesa shape obtained by etching using this etchant is also good. The selectivity of the obtained mesa shape is also the same, and the surface index appearing in the obtained mesa shape is also the (221) B surface. The steps from the embedding to the electrode formation are the same as those shown in the first embodiment.

(Embodiment 3) Next, a case will be described in which an etching stopper layer is used when forming a mesa shape and a quantum wire structure is formed immediately above the etching stopper.

Similar to FIG. 1, FIG. 3 shows a cross section of the layer structure before etching and the structure after completion of the quantum wire laser structure. 3A and 3B correspond to FIGS. 1A and 1D, respectively. 1B and 1C are omitted because they are similar steps.

As shown in FIG. 3A, an n-type GaAs substrate (which may be an n-type InP substrate or an n-type ZnSe substrate) 301.
N-type ZnSe cladding (n-type ZnSSe, n-type Z
nMgSSe layer 302, GaAs etching stopper layer (AlAs, AlGaAs, InGaAs)
303, ZnCdSe (ZnSe, ZnCd
S, ZnSSe, ZnS) active layer 304, p
Type ZnSe cladding (p type ZnSSe, p type ZnMgS
Se may be used) layer 305 is stacked.

Next, a mask having an appropriate width and an appropriate performance is formed in a stripe shape on the p-type ZnSe clad layer 305, and the laminated structure is etched to form a mesa stripe 306 as in FIG. 1B. To form. At this time, the quantum wire structure 307 is formed in the mesa stripe 306 by etching the quantum well structure 304. Further, the etching depth is automatically stopped because of the etching stopper layer 203. Therefore, it is easy to control the etching depth with high precision, which greatly contributes to the improvement of the yield.

Therefore, the depth of the mesa is determined by the p-type cladding layer 3
05 and the thickness of the quantum well layer 304. In addition, since the etching stop layer 303 is located immediately below the quantum well layer 304, it is not necessary to dig a mesa deeper than for the purpose of forming a quantum wire structure, and the mechanical strength of the mesa shape can be suppressed to a minimum. .

Hereinafter, the etchant used for etching, the etching shape, and the steps from filling to forming an electrode are the same as those shown in the first embodiment.

(Embodiment 4) Next, a case where a similar mesa shape is applied to the formation of a quantum wire structure will be described.

FIG. 4 is a diagram showing a manufacturing process of the quantum wire structure of the fourth embodiment of the present invention. As shown in FIG. 4A, a p or n type GaAs substrate (or p or n type InP substrate, or p or n type ZnSe substrate) 4
01 or p or n type ZnSe (or p or n type ZnSSe, or p or n type ZnMgS
Se) layer 402, ZnCdSe (or ZnSe, ZnCdS, ZnSSe, Zn)
An S active layer 403 and a p or n-type ZnSe (or p or n-type ZnSSe or p or n-type ZnMgSSe) layer 404 are laminated. Next, a mask having a proper width and a proper performance is formed in a stripe shape on the p or n-type ZnSe layer 404, and the laminated structure is etched to form a mesa stripe 405 as shown in FIG. 1B. To do. At this time, the quantum well structure 4 is etched.
By carrying out deeper than 03, the quantum wire structure 406 is formed in the mesa stripe 405.

Since the etching at this time is the same as that shown in the first conventional example, the description thereof will be omitted. Next, as shown in FIG. 4C, the mesa stripe shape is buried with a p or n type buried layer 407. At this time, the material of the buried layer 107 is ZnCd.
Se, ZnSe, ZnSSe, ZnS, ZnMgSS
e, which is lattice-matched to the substrate 401 and has a quantum wire structure 4
It is chosen to have a refractive index lower than 06. For example, the substrate 401 is GaAs, and the quantum wire structure 406 is Zn.
When it is composed of CdSe, this buried layer is, for example, ZnSSe.

At this time, the buried layer 407 is formed by, for example, a molecular beam crystal growth method (MBE) method or a metal organic chemical vapor deposition method (MOVP).
Grow according to E). The molecular beam source for this MBE method is, for example, ZnSe, ZnS, CdSe, ZnTe, Mg.
A compound source such as Se or MgS is used.

Next, as shown in FIG. 4C, the buried layer 407 in which the quantum wire structure 405 is buried is etched so that the quantum wire structure 405 is exposed, and an opening 408 is formed.
To form For etching, for example, K2C as described above
An etchant containing r2O7 or an etchant containing saturated bromine water is used.

Next, as shown in FIG. 4D, a contact layer 409 doped with p-type or n-type is crystal-grown on the buried layer 407 having the opening 408. The material of the contact layer 409 is, for example, ZnSe or ZnT.
e, a multiple quantum well layer of ZnSe and ZnTe, a pseudo mixed crystal layer, and the like are conceivable.

In the above structure, the contact layer 409
May not be required. Further, in the above constitution, the most suitable combination can be arbitrarily selected for the doping of each constituent element depending on the characteristics to be obtained.

The structure created in the above process exhibits the quantum effect by forming the quantum wire 106 so that the width thereof is sufficiently thin, and the quantum wire has features such as ultra-low operating voltage and ultra-high-speed operation. Become a device.

Also in the above quantum wire structure, the width of the quantum wire 406 can be arbitrarily determined by the etching depth and the position of the quantum well layer.

(Embodiment 5) Next, a case where an etching stopper layer is used at the time of forming a mesa when applying a similar mesa shape to the formation of a quantum wire structure will be described.

FIG. 5 is a view showing a manufacturing process of the quantum wire structure of the fifth embodiment of the present invention. As shown in FIG. 5A, p or n type GaAs substrate (or p or n type InP substrate, or p or n type ZnSe substrate) 5
01 or p or n type ZnSe (or p or n type ZnSSe, or p or n type ZnMgS
Se) layer 502, GaAs etching stopper layer (A
lAs, or AlGaAs, InGaAs) 50
3, second p-type or n-type ZnSe (or n-type ZnSe
SSe, or n-type ZnMgSSe) layer 504, Zn
An active layer 505 of CdSe (or ZnSe, ZnCdS, ZnSSe, or ZnS),
p or n type ZnSe (or p or n type ZnSe
SSe, or p or n type ZnMgSSe) layer 5
06 are stacked.

Next, this p-type or n-type ZnSe layer 506 is formed.
A mask having an appropriate width and an appropriate performance is formed in a stripe shape on the upper surface, and the laminated structure is etched to obtain a structure shown in FIG.
The mesa stripe 407 is formed as shown in FIG. At this time, by performing etching to a depth deeper than the quantum well structure 505, the quantum wire structure 5 is formed in the mesa stripe 507.
08 is formed. The etching depth is automatically stopped because of the etching stopper layer 503. Therefore, it is easy to control the etching depth with high precision, which greatly contributes to the improvement of the yield.

Therefore, the depth of the mesa is the sum of the thicknesses of the p-type or n-type layer 506, the quantum well layer 505, and the second p-type or n-type layer 504.

Hereinafter, from etching to embedding, Example 1
It is omitted because it is the same as. (Embodiment 6) Next, in applying a similar mesa shape to the formation of the quantum wire structure, an etching stopper layer is used at the time of forming the mesa, and the quantum wire structure is formed immediately above the etching stopper.

FIG. 6 is a diagram showing a manufacturing process of a quantum wire structure according to a sixth embodiment of the present invention. FIG. 6 shows a p or n type GaAs substrate (or p or n) as shown in FIG.
Type InP substrate, or p or n type ZnSe substrate)
P or n-type ZnSe (or p or n-type ZnSSe, or p or n-type ZnMg
SSe) layer 602, GaAs etching stopper layer (AlAs, or AlGaAs, InGaAs) 6
03, ZnCdSe (or ZnSe, or Zn
CdS or ZnSSe or ZnS active layer 604, p or n-type ZnSe (or p or n-type ZnSSe, or p or n-type ZnMgS)
Se) layer 605 is stacked.

Next, this p-type or n-type ZnSe layer 605 is formed.
A mask with an appropriate performance having an appropriate width is formed in a stripe shape on the upper side, and this laminated structure is etched to obtain a structure shown in FIG.
The mesa stripe 607 is formed as shown in FIG. At this time, by performing etching to a depth deeper than the quantum well structure 604, the quantum wire structure 6 is formed in the mesa stripe 607.
08 is formed. The etching depth is automatically stopped because of the etching stopper layer 603. Therefore, it is easy to control the etching depth with high precision, which greatly contributes to the improvement of the yield.

Accordingly, the depth of the mesa is the sum of the thicknesses of the p-type or n-type layer 605 and the quantum well layer 604.

Hereinafter, from etching to embedding, Example 4
Is the same as

[0069]

According to the present invention, a quantum wire structure and a quantum wire laser can be realized by forming an inverted mesa shape by etching with an etchant containing an appropriate composition of dichromic acid.

The mesa structure formed on the II-VI crystal layer by the etchant of the present invention is an inverted mesa in the <1-10> direction, and the (221) B plane can be formed on the side surface with good reproducibility. The semiconductor quantum wire laser and quantum wire structure of the present invention are
It can be applied to II-VI group semiconductors, and crystal growth using the MBE method can also be used.

In the semiconductor quantum wire laser and quantum wire structure of the present invention, the width and thickness of the quantum wire can be arbitrarily controlled by crystal growth and etching, and the flexibility of forming the quantum wire structure is high.

The semiconductor quantum wire laser and quantum wire structure of the present invention can improve etching accuracy and yield by adopting a structure using an etching stopper layer.

In the semiconductor quantum wire laser and the quantum wire structure of the present invention, the structure having excellent mechanical strength can be formed by forming the quantum wire directly on the etching stopper layer.

[Brief description of drawings]

FIG. 1 is a process sectional view of a quantum wire laser according to a first embodiment of the present invention.

FIG. 2 is a process sectional view of a quantum wire laser according to a second embodiment of the present invention.

FIG. 3 is a process sectional view of a quantum wire laser according to a third embodiment of the present invention.

FIG. 4 is a process sectional view of a quantum wire structure according to a fourth embodiment of the present invention.

FIG. 5 is a process sectional view of a quantum wire structure according to a fifth embodiment of the present invention.

FIG. 6 is a process sectional view of a quantum wire structure according to a sixth embodiment of the present invention.

FIG. 7 is a process sectional view of a conventional quantum wire laser.

FIG. 8 is a mask width described in the first embodiment of the present invention,
Diagram explaining the relationship between quantum wire width and mesa depth

[Explanation of symbols]

 101 n-type GaAs substrate 102 n-type ZnSe clad layer 103 ZnCdSe quantum well layer 104 p-type ZnSe clad layer 105 mesa stripe 106 quantum wire 107 undoped buried layer 108 opening 109 p-type contact layer 110 p-type electrode 111 n-type electrode 201 n Type GaAs substrate 202 n type ZnSe clad layer 203 etching stopper layer 204 second n type ZnSe clad layer 205 ZnCdSe quantum well layer 206 p type ZnSe clad layer 207 mesa stripe 208 quantum wire 209 opening 210 buried layer 211 p type contact layer 212 p-type electrode 213 n-type electrode 301 n-type GaAs substrate 302 n-type ZnSe clad layer 303 etching stopper layer 304 ZnCdSe quantum well layer 305 p-type ZnSe layer Add layer 306 Mesa stripe 307 Quantum wire 308 Opening 309 Buried layer 310 p-type contact layer 311 p-type electrode 312 n-type electrode 401 p-type or n-type GaAs substrate 402 p-type or n-type ZnSe clad layer 403 ZnCdSe quantum well layer 404 n-type or p-type ZnSe clad layer 405 mesa stripe 406 quantum wire 407 n-type or p-type or buried layer 408 opening 409 n-type or p-type contact layer 501 p-type or n-type GaAs substrate 502 p-type or n-type ZnSe clad layer 503 Etching stopper layer 504 Second p-type or n-type ZnSe clad layer 505 ZnCdSe quantum well layer 506 n-type or p-type ZnSe clad layer 507 Mesa stripe 508 Quantum wire 509 Opening 510 n-type or p-type or buried layer 511 n-type or p-type contact layer 601 p-type or n-type GaAs substrate 602 p-type or n-type ZnSe cladding layer 603 etching stopper layer 604 ZnCdSe quantum well layer 605 n-type or p-type ZnSe clad layer 606 Mesa stripe 607 Quantum wire 608 Opening 609 n-type or p-type buried layer 610 n-type or p-type contact layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01S 3/18 H01S 3/18

Claims (15)

[Claims] 1. A mesa forming method for forming a mesa in a II-VI group compound semiconductor layer by an etchant in which a K ₂ Cr ₂ O ₇ aqueous solution and a H ₂ SO ₄ aqueous solution are mixed. 2. An etchant in which an aqueous K ₂ Cr ₂ O ₇ solution and an aqueous H ₂ SO ₄ solution are mixed, the concentration of the aqueous K ₂ Cr ₂ O ₇ solution being 0.1 to 0.3 mol / l, and an aqueous H ₂ SO ₄ solution. Forming a mesa in the II-VI group compound semiconductor layer by etching with an etchant having a concentration of 9 to 18 mol / l. 3. A quantum well structure in which a ZnSe based semiconductor layer is used as a quantum well layer and a ZnSe based semiconductor layer having a band gap larger than that is used as a barrier layer is formed by etching with the etchant according to claim 1. A quantum wire device having a quantum wire as an active layer. 4. The quantum wire device according to claim 3, wherein an inverted mesa is formed by the etching. 5. The reverse mesa side surface is a {221} B surface,
The quantum wire device according to claim 3, wherein the stripe direction is <1-10>. 6. The quantum wire device according to claim 3, wherein the width of the quantum wire is 10 nm or less. 7. The quantum wire device according to claim 3, wherein the width of the upper surface of the mesa is 0.5 μm or more. 8. The quantum wire device according to claim 3, wherein a layer having a refractive index lower than that of the active layer is provided as a buried layer on a side surface of the inverted mesa. 9. The embedding layer is Zn1-xMgxSySe1-y.
9. The quantum wire device according to claim 8, wherein (0 ≦ x ≦ 1, 0 ≦ y ≦ 1). 10. A II-VI group compound semiconductor is used as a quantum well layer and has a band gap larger than that of the quantum well layer.
The quantum wire device according to claim 3, wherein the quantum wire device has a Group VI compound semiconductor layer as a barrier layer. 11. The SCH structure having an active region, comprising a quantum well layer, an optical guide layer sandwiching the quantum well layer, and a cladding layer sandwiching the optical guide layer. The described quantum wire device. 12. The quantum well layer and the barrier layer are made of ZnCd.
Se, ZnSe, ZnSSe, ZnS, ZnMgS, Z
12. The quantum wire device according to claim 11, wherein the quantum well layer is selected from nMgSSe, and the quantum well layer has a bandgap smaller than that of the barrier layer. 13. The quantum wire device according to claim 3, further comprising an etching stop layer below the quantum well layer. 14. The etching stopper layer is InGaAs, G
The quantum wire device according to claim 3, wherein the quantum wire device is selected from aAs, AlGaAs, and AlAs. 15. The quantum wire device according to claim 3, wherein a quantum well layer is formed immediately above the etching stop layer.