JP2004200375A - Semiconductor laser device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a quantum cascade laser with the crystal growth controlled at least once in the atom level in a semiconductor laser device which can generate the laser beam of the intermediate infrared wavelength of 5 to 20 μm. <P>SOLUTION: An energy level formed within a potential well of the quantum cascade laser is modulated in the direction parallel to the crystal growth surface, and electrons or holes in the light emitting layer are moved in the direction parallel to the crystal growth surface. Accordingly, the quantum cascade structure which has been perpendicular to the crystal growth surface can then be formed in parallel to the crystal surface. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor laser device that can oscillate a laser beam having a mid-infrared wavelength of 5 to 20 μm.
[0002]
[Prior art]
Semiconductor lasers are frequently used for optical disks and optical communications. The oscillation wavelength of the semiconductor laser used there is 1.55 / 1.3 μm (for optical fiber communication), 0.98 μm (for fiber amplifier), 0.78 μm (for compact disk (CD) / mini disk (MD)), 0.65 μm (for DVD), 0.41 μm (for high-density DVD), etc., and the semiconductor material and laser structure used for these are almost established in mass production. On the other hand, as a wavelength at which a semiconductor laser can oscillate, a so-called mid-infrared region around 3 μm to 20 μm has recently attracted attention. This wavelength band includes absorption wavelengths of various organic substances. The realization of a semiconductor laser in this wavelength band is expected to open a new market including a set in fields such as atmospheric analysis and medical care.
[0003]
As a semiconductor laser in the mid-infrared region, an approach using a material having a narrow band gap as an active layer of the semiconductor laser has been used. For example, studies using III-V group semiconductors (such as InGaAsSb) and IV-VI group semiconductors (such as PbTeSe) have been made. However, III-V semiconductors physically have Auger recombination, and the Auger recombination increases significantly due to the narrowing of the band gap. For this reason, non-radiative recombination increases and a threshold current rapidly increases, making laser oscillation difficult. Further, the IV-VI group semiconductor cannot bring a material having a sufficiently large band gap to the cladding layer, and cannot make the hetero barrier (ΔEc, ΔEv) large at the conduction band (valence band) hetero interface. Therefore, carrier leakage from the active layer to the cladding layer is extremely large. These (narrow band gap) III-V / IV-VI semiconductors have defects in the material, so that laser oscillation becomes extremely difficult when the temperature approaches room temperature. For this reason, oscillation of the semiconductor laser in the 3 to 20 μm band can be obtained only at a low temperature (about 100 to 200 Kelvin), and it has been difficult to use the laser for general industrial applications.
[0004]
On the other hand, in recent years, a quantum cascade laser (hereinafter abbreviated as QC laser) has been realized as a new semiconductor laser emission mechanism (Jerome Faist et al., "Quantum Cascade Laser", Science, vol.264, p.553, 1994). Conventional semiconductor light-emitting devices (semiconductor lasers, light-emitting diodes, and the like) emit light between bands of a semiconductor material constituting an active layer (electrons in a conduction band recombine with holes in a valence band to form a conductor and a valence). (Emission of photons having an electron band energy difference).
[0005]
FIG. 15 shows a typical structure of a QC laser (for example, see Non-Patent Document 1).
[0006]
15, an n-InP first cladding layer 82, InGaAs quantum well layers 83 and 84, an AlInAs quantum barrier layer 85, an n-InP second cladding layer 86, and an InGaAs contact layer 87 are formed on an n-type InP substrate 81. Have been. Except for the light emitting portion, an insulating InP buried layer 88 is formed. Then, AuGe electrodes 89 and 90 are formed. In the QC laser, in a plurality of quantum levels formed in the conduction band of the quantum well layer 84, electrons existing at a high energy level (level A) transition to a low energy level (level B). That is, light is emitted by a so-called sub-band transition. Therefore, the above-described Auger recombination does not occur, and the hetero barrier can be increased by appropriately selecting the material of the semiconductor superlattice. Can be solved. The region where the quantum well emits light is called a light emitting region. On the other hand, the electrons that have emitted light are injected into the quantum well layer 83 at the level A formed in the next-stage light emitting region. The region where electrons move to a higher level in the conduction band is called an injection region.
[0007]
[Non-patent document 1]
Mattias Beck et.al., "Continuous Wave Operation of a Mid-Infrared Semiconductor Laser at Room Temperature", Science vol.295, p.301
[0008]
[Problems to be solved by the invention]
In FIG. 15, the injection region and the light emitting region are drawn as a single quantum well, but in an actual device, both the light emitting region and the injection region are composed of 5 to 10 layers of superlattices (quantum well and quantum barrier). In addition, the QC laser can contribute to light emission again by putting it again into the injection layer and entering a higher level without losing the light-emitted electrons due to recombination with holes. Emit many photons. Therefore, as the number of pairs of the injection region and the emission region increases, the slope efficiency improves (for example, F. Capasso et al., IEEE Journal on Selected Topics in Quantum Electronics, vol. 6, No. 6, p. 931 (2000)). ))
[0009]
For this reason, in a QC laser, 20 to 30 pairs are usually used as pairs of an injection region and a light emitting region. Therefore, the number of layers is (5 to 10 injection layers + 5 to 10 light emitting layers) × (20 to 30 stages) = 200 to 600 layers. It is extremely difficult to fabricate such a number of layers at the atomic level of each layer (several to several tens of nm), even if it is possible experimentally, with good mass productivity and to design each layer. Variations in each layer cause variations in quantum levels, lowering optical gain, in other words, increasing threshold current and causing instability in oscillation wavelength, and there is a problem in terms of mass production.
[0010]
[Means for Solving the Problems]
In order to solve the above problem, a semiconductor laser device according to claim 1 of the present invention emits photons by performing energy transition of electrons or holes between specific energy levels formed in a potential well, In a semiconductor laser in which the energy transition process exists a plurality of times for one electron or hole, the light emitting region has a plurality of potential wells in a direction parallel to a crystal growth surface, and is formed in the potential well. The energy level is modulated in a direction parallel to the crystal growth surface, and electrons or holes in the light emitting layer move in a direction parallel to the crystal growth surface.
[0011]
As a result, a quantum cascade structure can be produced parallel to the crystal plane, instead of the conventional structure having a quantum cascade perpendicular to the crystal growth plane. That is, if there is at least one crystal growth controlled at the atomic level, a QC laser can be manufactured, and the conventional 100-layer or more atomic-level crystal growth is not required.
[0012]
In particular, as shown in the semiconductor laser device according to the second aspect of the present invention, when a quantum wire is used as a potential well of a light emitting region, a quantum level suitable for intersubband transition is formed in the potential well. can do.
[0013]
Furthermore, as shown in the semiconductor laser device according to the third aspect of the present invention, if quantum dots are used as potential wells in the light emitting region, the quantum level becomes larger than the minimum line width of the quantum wires. Can be formed, and the fabrication becomes easy.
[0014]
Further, as shown in a semiconductor laser device according to a fourth aspect of the present invention, it is preferable that, of the semiconductors adjacent to the light emitting layer, a region sandwiching the light emitting layer in parallel with the crystal plane is an insulating semiconductor. This allows electrons (or holes) to flow efficiently parallel to the crystal plane.
[0015]
Furthermore, as shown in the semiconductor laser device according to claim 5 of the present invention, the light emitting layer is composed of two or more layers, and in each of the light emitting layers, electrons or holes move in a direction parallel to the crystal growth surface. It is desirable to do. Thus, at the same voltage value, more photons can be emitted almost in proportion to the number of layers, which is suitable for high output.
[0016]
Next, as shown in a semiconductor laser device according to a sixth aspect of the present invention, such a QC laser can have a positive electrode and a negative electrode on the same surface. This eliminates the need to remove electrodes from the laser back surface by wire bonding or the like, and facilitates the mounting process.
[0017]
Further, as shown in a semiconductor laser device according to a seventh aspect of the present invention, by using an insulating substrate, a parasitic capacitance can be removed, and high-speed operation can be performed.
[0018]
Next, in the method of manufacturing a semiconductor laser device according to claim 8 of the present invention, a step of forming a first conductive cladding layer and a first insulating cladding layer on a substrate; Forming an active layer having a superlattice cascade structure formed by a photolithography process on a conductive cladding layer, and forming a second insulating cladding layer and a second conductive cladding layer on the active layer Which is characterized by having In such a QC laser, a change in the shape of a quantum wire or a quantum dot, that is, modulation of an energy level formed in a potential well can be determined by using photolithography frequently used in a semiconductor process. . Therefore, the modulation of the energy level is determined by one mask, which facilitates fabrication of a QC laser.
[0019]
In this case, as described in the method of manufacturing a semiconductor laser device according to claim 9 of the present invention, it is desirable to use X-rays as a light source for photolithography. Since the X-ray has a wavelength of 0.1 to 1 nm, it is possible to produce a quantum wire / quantum dot shape very precisely.
[0020]
Further, as described in the method of manufacturing a semiconductor device laser device according to claim 10 of the present invention, it is preferable that the superlattice cascade structure is formed by one photolithography process. According to this method, a plurality of portions of the semiconductor forming the potential well are formed at a time, and a plurality of portions of the semiconductor forming the potential barrier surrounding the potential well are formed at the same time. Variations in semiconductor composition between the potential barriers are eliminated, and deviation from the design (such as oscillation wavelength variation) due to the composition variation can be suppressed.
[0021]
Next, a method of manufacturing a semiconductor device laser device according to claim 11 of the present invention includes a step of forming a first insulating cladding layer on a substrate and a step of photolithography on the first insulating cladding layer. Forming an active layer having the superlattice cascade structure formed in the step, forming a second insulating cladding layer on the active layer, forming the first insulating cladding layer and the second insulating cladding layer on the active layer. A step of converting a portion of the insulating cladding layer into or out of the active layer into which electrons or holes flow and into which electrons or holes flow, to conductivity. According to this method, at the stage of crystal growth, the layer that is in contact with the light emitting layer is an insulating semiconductor, and among the insulating semiconductors, the part that flows electrons or holes into the light emitting region and the part that flows out of the insulating semiconductor are made conductive. Electrons can be efficiently injected into and extracted from the active layer.
[0022]
Next, in the method of manufacturing a semiconductor device laser device according to a twelfth aspect of the present invention, it is desirable to use thermal diffusion or ion implantation as a method of changing the conductivity. These methods are widely used semiconductor processes and do not require special manufacturing equipment.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described more specifically with reference to embodiments.
[0024]
FIG. 1A is a sectional view (in a direction perpendicular to the resonator) of the semiconductor laser device according to the first embodiment of the present invention. An insulating InP first cladding layer 2 and a conductive InP first cladding layer 3 are formed on an n-InP substrate 1. An active layer 4 including a superlattice cascade structure composed of an InGaAs well 5 (In composition 60%) and an AlInAs barrier 6 (In composition 40%) is formed on the first cladding layer. (AlInAs (In composition: 40%) except for the well 5 and the barrier 6 in the active layer 4). The widths of the InGaAs well portion 5 and the AlInAs barrier portion 6 differ depending on the location, and form an optimum quantum level in the injection region 12 and the light emitting region 13. On the active layer 4, an insulating InP second cladding layer 7 and a conductive InP second cladding layer 8 are formed. A conductive InGaAs contact layer 9 (In composition 60%) and an AuGe electrode 10 are formed on the second cladding layers 7 and 8. An AuGe electrode 11 is also formed on the back surface of the substrate 1.
[0025]
In the present embodiment, a current flows between the electrodes 10 and 11. For example, when the electrode 11 is negative and the electrode 10 is positive, electrons are injected from the conductive region 3 into the active layer 4, and a sub-band transition is performed in the superlattice cascade structure composed of the injection region 12 and the light emitting region 13 to emit light After that, the active layer 4 is injected into the conductive region 8. FIG. 1B shows the current light output characteristics of this laser. The measurement was performed at 25 ° C. and continuous oscillation. The threshold current is extremely small, about 0.2 mA. This is because the cross-sectional area through which the current flows is extremely small. The light output was 1 mW or more, and the slope efficiency was about 0.2 W / A. The oscillation spectrum is shown in FIG. Laser oscillation occurs at the transition between sub-bands, and the oscillation wavelength is about 9 μm.
[0026]
2 to 6 show a method for manufacturing the present semiconductor laser. A Fe-doped insulating InP first cladding layer 2 is grown to a thickness of 3 μm on the n-InP substrate 1 by metal organic chemical vapor deposition (MOCVD) (FIG. 2A). Then, after covering the part to be left as the insulating InP using photolithography, Si is ion-implanted using an ion implantation method to form a conductive InP first cladding layer 3 (FIG. 2B). Next, a crystal of InGaAs5 (In composition: 60%) is grown to a thickness of 5 nm by MOCVD (FIG. 3C). After forming the SiO ₂ on the surface thereof, using photolithography, only the portion corresponding to the well portion in a cascade structure leaving SiO ₂ stripe 21 (FIG. 3 (d)). As a light source for photolithography that leaves the well portion, an X-ray (wavelength: 0.1 nm) using emitted light of electrons was used. In this figure, for the sake of simplicity, five lines of SiO ₂ stripes are formed as portions where InGaAs is left, but in actual devices, SiO ₂ stripes are left as follows.
[0027]
Injection area: (unit: nm, interval in ())
2.1+ (1.2) +6.5+ (1.2) +5.3+ (2.3)
Emission area: (unit: nm, interval in ())
4.0+ (1.1) +3.6+ (1.2) +3.0+ (1.6)
That is, six SiO ₂ stripes 21 remain for each pair of the injection region and the light emitting region. In this case, 30 sets of the injection / emission regions are sequentially arranged, so that 180 SiO ₂ stripes 21 remain. Since the width of this cascade structure is determined using photolithography, it can be formed extremely easily and freely. That is, conventionally, the cascade direction in which the electrons of the QC laser sequentially emit light is perpendicular to the crystal growth surface, so that the QC laser structure is determined by crystal growth, but the QC laser structure of this time can be determined by photolithography. .
[0028]
Thereafter, InGaAs not masked by the SiO ₂ stripes 21 was selectively removed by citric acid wet etching (FIG. 4E). Next, the active layer 4 (except the well 5) and the AlInAs barrier 6 are formed only at locations where the SiO ₂ stripes 21 are not masked, using selective growth by MOCVD (FIG. 4F).
[0029]
Since these In compositions are formed by the same crystal growth, the In composition is 40% for both the active layer 4 (excluding the well part 5) and the barrier part 6. Thereafter, the SiO ₂ stripe 21 is removed with a hydrofluoric acid-based etchant (FIG. 5G). Next, an insulating InP second cladding layer 7 is formed by MOCVD (FIG. 5H). Then, similarly to FIG. 3C, a conductive InP second cladding layer 8 is formed using photolithography and ion implantation (FIG. 6I) (this conductive second cladding layer is formed by InGaAs (It may be after forming the contact layer 9).
[0030]
Finally, after forming an InGaAs contact layer 9 (In composition 60%) by MOCVD, AuGe electrodes 10 and 11 are formed. Then, the wafer is cleaved to complete the laser. The resonator length is 1 mm and the width is 300 μm.
[0031]
FIG. 7 is a sectional view (in a direction perpendicular to the resonator) of a semiconductor laser device according to a second embodiment of the present invention. An insulating InP first cladding layer 2 is formed on an insulating InP substrate 30. An active layer 4 including a superlattice cascade structure composed of an InGaAs well 5 (In composition 60%) and an AlInAs barrier 6 (In composition 40%) is formed on the first cladding layer.
[0032]
The widths of the InGaAs well portion 5 and the AlInAs barrier portion 6 differ depending on the location, and form an optimum quantum level in the injection region 12 and the light emitting region 13.
[0033]
The material other than the superlattice cascade structure in the light emitting region is AlInAs (In composition: 40%) as in the barrier portion 6. On the active layer 4, an insulating InP second cladding layer 7 is formed. An insulating InGaAs contact layer 31 (In composition: 60%) is formed on the second cladding layer 7.
[0034]
Conductive regions 35 and 36 obtained by thermally diffusing Si are formed on both sides of the injection region 12 and the light emitting region 13 in the cladding layer and the contact layer. AuGe electrodes 32 and 33 are formed separately on the surfaces of the conductive regions 35 and 36. No electrode is formed on the back surface of the substrate 1.
[0035]
In the present embodiment, a current flows between the electrodes 32 and 33. For example, when the electrode 32 is negative and the electrode 33 is positive, electrons are injected into the active layer 4 from the region 35 where Si ions are thermally diffused and become conductive, and the cascade portions 12 and 13 perform sub-band transition to emit light. Thereafter, the active layer 4 is implanted into the conductive region 36.
[0036]
Unlike the first embodiment, this structure is easy to mount because electrical connection can be made from the electrodes 32 and 33 on the same surface.
[0037]
The threshold current of this laser was 0.2 mA, and the maximum output was 10 mW at room temperature pulse operation. The oscillation wavelength is about 9 μm. In the case of the second embodiment, since the electrodes are only on the surface, mounting is easy (wire bonding is unnecessary).
[0038]
In addition, the use of the insulating substrate 30 reduced the parasitic capacitance and allowed modulation up to 10 GHz or more.
[0039]
8 to 11 show a method for manufacturing the present semiconductor laser. Using an organometallic vapor phase epitaxy (MOCVD) method, the insulating InP first cladding layer 2 is grown to a thickness of 3 μm and InGaAs5 (In composition: 60%) is grown to a thickness of 5 nm on the insulating InP substrate 30 (FIG. 8 ( a)).
[0040]
After forming the SiO ₂ on the surface thereof, using a photolithography, only the portion corresponding to the well portion in a cascade structure leaving SiO ₂ stripe 21 (Figure 8 (b)).
[0041]
In this figure, for the sake of simplicity, five lines of SiO ₂ stripes are formed as portions where InGaAs is left, but in actual devices, SiO ₂ stripes are left as follows.
[0042]
Injection area: (unit: nm, interval in ())
2.1+ (1.2) +6.5+ (1.2) +5.3+ (2.3)
Emission area: (unit: nm, interval in ())
4.0+ (1.1) +3.6+ (1.2) +3.0+ (1.6)
That is, six SiO ₂ stripes 21 remain for each pair of the injection region and the light emitting region. In this case, 30 sets of the injection / emission regions are sequentially arranged, so that 180 SiO ₂ stripes 21 remain. Since the width of this cascade structure is determined using photolithography, it can be formed extremely easily and freely.
[0043]
That is, conventionally, the cascade direction in which the electrons of the QC laser sequentially emit light is perpendicular to the epi-plane, so that the QC laser structure is determined by crystal growth, but the QC laser structure of this time can be determined by photolithography.
[0044]
Thereafter, InGaAs not masked by the SiO ₂ stripes 21 was selectively removed by citric acid wet etching (FIG. 9C).
[0045]
Next, the active layer 4 (excluding the well 5) and the AlInAs barrier 6 are formed only at locations where the SiO ₂ stripes 21 are not masked by using selective growth by MOCVD (FIG. 9D). Since these In compositions are formed by the same crystal growth, the In compositions are both 40%.
[0046]
Thereafter, the SiO ₂ stripe 21 is removed with a hydrofluoric acid-based etchant (FIG. 10E).
[0047]
Next, the insulating InP second cladding layer 7 and the insulating InGaAs contact layer 31 (In composition: 60%) are formed by MOCVD (FIG. 10F).
[0048]
Next, using photolithography, conductive portions 35 and 36 are formed by thermal diffusion of Si (FIG. 11G). Further, AuGe electrodes 32 and 33 are formed using photolithography (FIG. 11H). Then, the wafer is cleaved to complete the laser.
[0049]
The second embodiment is characterized in that the number of times of crystal growth is small and the process is easy as compared with the first embodiment.
[0050]
FIG. 12 shows a third embodiment of the present invention. The basic structure (such as the path through which current flows) is the same as that of FIG. 7, but a quantum dot 41 is used instead of a quantum wire (in the figure, a large number of formed quantum dots are simplified). .
[0051]
The length of the quantum dot 41 changes in the direction parallel to the cleavage plane (the length direction in which the current in each dot flows). Injection area as width: (unit: nm, interval in ())
4.1+ (2.2) +8.5+ (2.2) +7.3+ (4.3)
Emission area: (unit: nm, interval in ())
6.0+ (3.1) +5.6+ (3.2) +5.0+ (3.6)
Was used.
[0052]
The width of the quantum dots in the direction perpendicular to the cleavage plane (the width of the current flowing in each dot) was 5 nm.
[0053]
By making the quantum dots, the size required to form the same quantum level can be made larger than that of the quantum wire (for example, the minimum value of the shape and size is 1.1 nm for the quantum wire (first, In the second embodiment), the quantum dot achieves the same function at 2.2 nm), which facilitates fabrication.
[0054]
Fabrication of the quantum dots is the same as that shown in basically the second embodiment (FIGS. 8-11), a photolithographic pattern in the SiO ₂ mask 42 of the well portion to angular, SiO Instead of FIG. 9C in which _two stripes are formed, the SiO ₂ mask pattern is changed to a dot shape as shown in FIG. 13A.
[0055]
As a result, after burying the active layer 43 including the barrier portion and removing the SiO ₂ , the result is as shown in FIG. Thereafter, the same steps as those in FIGS. 10F to 11H are performed.
[0056]
FIG. 14 shows a fourth embodiment of the present invention. A second active layer 52 is formed via an insulating InP intermediate layer 51, and a second InGaAs well 53 and a second AlInAs barrier 54 are formed inside the second active layer 52, both of which are quantum wires perpendicular to the plane of the paper. ). By thus forming the cascade structure in two layers, more electrons can contribute to light emission, and high output can be achieved. Specifically, in the present laser structure, a current twice as large as the same applied voltage value can be made to flow and an optical output about twice as large as that in the first embodiment. In the present embodiment, the cascade structure has two layers, but may have three or more layers.
[0057]
【The invention's effect】
The common features of the above-described first to fourth embodiments will be described together. Conventionally, a cascade structure was created by depositing an epi film. For this reason, the crystal growth is not only troublesome, but also the compositions of the respective films during the crystal growth are slightly different from each other, resulting in a variation in the oscillation wavelength.
[0058]
In the structure of the present invention, the crystal composition of each of the well portion / barrier portion is the same in any two of the portions. For this reason, it is possible to suppress wavelength fluctuation and the like in the cascade operation, and to obtain excellent laser characteristics. For example, in a conventional QC laser, multi-longitudinal mode oscillation is often performed due to variation in composition. The structure of the present invention has many advantages, such as a single longitudinal mode, because there is no composition change in the superlattice in any of the first to fourth embodiments.
[Brief description of the drawings]
FIG. 1A is a sectional view of a semiconductor laser device according to a first embodiment of the present invention; FIG. 1B is a current light output characteristic diagram of the semiconductor laser device according to the first embodiment of the present invention; FIG. 2A is a diagram illustrating a method of manufacturing a semiconductor laser according to a first embodiment of the present invention; FIG. 2B is a diagram illustrating a method of manufacturing the semiconductor laser according to the first embodiment of the present invention; FIG. 3C is a diagram illustrating a method of manufacturing a semiconductor laser according to an embodiment. FIG. 3C is a diagram illustrating a method of manufacturing a semiconductor laser according to a first embodiment of the present invention. FIG. 3D is a diagram illustrating a method of manufacturing the semiconductor laser according to the first embodiment of the present invention. FIG. 4E shows a method of manufacturing a semiconductor laser according to the first embodiment of the present invention; FIG. 4F shows a method of manufacturing the semiconductor laser according to the first embodiment of the present invention; Diagram showing the method [Fig. 5] (g) Books (H) A diagram showing a method of manufacturing a semiconductor laser according to the first embodiment of the present invention. (H) A diagram showing a method of manufacturing a semiconductor laser according to the first embodiment of the present invention. (J) showing a method for manufacturing a semiconductor laser according to the embodiment of the present invention (j) Drawing showing a method for manufacturing a semiconductor laser according to the first embodiment of the present invention [FIG. 7] Semiconductor laser according to the second embodiment of the present invention FIG. 8A is a view showing a method for manufacturing a semiconductor laser device according to a second embodiment of the present invention. FIG. 8B is a view showing a method for manufacturing a semiconductor laser device according to the second embodiment of the present invention. FIG. 9C is a diagram showing a method for manufacturing a semiconductor laser device according to the second embodiment of the present invention. FIG. 9D is a diagram showing a method for manufacturing a semiconductor laser device according to the second embodiment of the present invention. FIG. 10 (e) shows a second embodiment of the present invention. (F) shows a method of manufacturing a semiconductor laser device according to the second embodiment of the present invention. (F) shows a method of manufacturing a semiconductor laser device according to the second embodiment of the present invention. (FIG. 11) (g) shows a second embodiment of the present invention. (H) is a diagram illustrating a method of manufacturing a semiconductor laser device according to the second embodiment of the present invention. (H) is a diagram illustrating a method of manufacturing a semiconductor laser device according to the second embodiment of the present invention. FIG. 13A is a view showing a method of manufacturing a semiconductor laser device according to a third embodiment of the present invention. FIG. 13B is a view showing a method of manufacturing the semiconductor laser device according to the third embodiment of the present invention. FIG. 14 is a sectional view of a semiconductor laser device according to a fourth embodiment of the present invention. FIG. 15 is a sectional view of a conventional semiconductor laser device.
1, 81 n-InP substrate 2 Insulating InP first cladding layer 3 Conductive InP first cladding layer 4 AlInAs active layer (including InGaAs well 5 and AlInAs barrier 6)
Reference Signs List 5 InGaAs well portion 6 AlInAs barrier portion 7 Insulating InP second cladding layer 8 Conductive InP second cladding layer 9 Conductive InGaAs contact layers 10, 11, 32, 33, 89, 90 AuGe electrode 12 Injection region 13 Light emitting region 21 , 42 SiO ₂ mask 30 Insulating InP substrate 31 Insulating InGaAs contact layer 35, 36 Si thermal diffusion conductive part 41 Quantum dot 43 Active layer 51 including barrier part Insulating InP intermediate layer 52 Second active layer 53 Second InGaAs well part 54 Second AlInAs barrier portion 82 n-InP first cladding layer 83, 84 InGaAs quantum well layer 85 AlInAs quantum barrier layer 86 n-InP second cladding layer 87 n-InGaAs contact layer 88 Insulating InP buried layer

Claims (12)

A semiconductor in which electrons or holes make energy transitions between specific energy levels formed in a potential well and emit photons, and wherein the energy transition process exists multiple times for one electron or hole. In the laser, the light emitting region has a plurality of potential wells in a direction parallel to the crystal growth surface, and an energy level formed in the potential well is modulated in a direction parallel to the crystal growth surface. A semiconductor laser device wherein electrons or holes in a layer move in a direction parallel to the crystal growth surface. 2. The semiconductor laser device according to claim 1, wherein a quantum wire is used as said potential well. 2. The semiconductor laser device according to claim 1, wherein quantum dots are used as said potential well. 2. The semiconductor laser device according to claim 1, wherein, of the semiconductor adjacent to the light emitting layer, a region sandwiching the light emitting layer in parallel with a crystal plane is an insulating semiconductor. 2. The semiconductor laser device according to claim 1, wherein said light emitting layer is composed of two or more layers. A semiconductor in which electrons or holes make energy transitions between specific energy levels formed in a potential well and emit photons, and wherein the energy transition process exists multiple times for one electron or hole. A semiconductor laser device comprising a laser having a positive electrode and a negative electrode on the same surface. A semiconductor in which electrons or holes make energy transitions between specific energy levels formed in a potential well and emit photons, and wherein the energy transition process exists multiple times for one electron or hole. A semiconductor laser device using an insulating substrate in a laser. Forming a first conductive cladding layer and a first insulating cladding layer on a substrate; and an active layer having a superlattice cascade structure formed on the first insulating cladding layer by a photolithography process. And a step of forming a second insulating cladding layer and a second conductive cladding layer on the active layer. 9. The method according to claim 8, wherein an X-ray is used as a light source for the photolithography. The method of manufacturing a semiconductor laser, wherein the superlattice cascade structure is formed by one photolithography process. Forming a first insulating cladding layer on a substrate, forming an active layer having a superlattice cascade structure formed by a photolithography step on the first insulating cladding layer, Forming a second insulating cladding layer on the layer; and forming electrons or holes in a light emitting region of the active layer, which is a part of the first insulating cladding layer and the second insulating cladding layer. Converting the part into which the semiconductor flows into and the part into which the semiconductor flows out into conductivity. The method of manufacturing a semiconductor laser according to claim 11, wherein the method for changing the conductivity is thermal diffusion or ion implantation.

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