Semiconductor laser device

Abstract

A semiconductor laser device capable of high output is provided. A semiconductor laser diode includes: a substrate; and a semiconductor stacked structure, which is formed on the substrate through crystal growth. The semiconductor stacked structure includes: an n-type (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P cladding layer and a p-type (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P cladding layer; an n-side Al.sub.x2Ga.sub.(1-x2)As guiding layer and a p-side Al.sub.x2Ga.sub.(1-x2)As guiding layer, which are sandwiched between the cladding layers; and an active layer, which is sandwiched between the guiding layers. The active layer is formed of a quantum well layer including an Al.sub.yGa.sub.(1-y)As.sub.(1-x3)P.sub.x3 layer and a barrier layer including an Al.sub.x4Ga.sub.(1-x4)As layer that are alternatively repetitively stacked for a plurality of periods.

Claims

1. A semiconductor laser device, comprising: a p-type cladding layer and an n-type cladding layer; a p-side guiding layer and an n-side guiding layer between the p-type cladding layer and the n-type cladding layer, including an arsenic group compound semiconductor, and having bandgaps narrower than those of the p-type cladding layer and the n-type cladding layer; and an active layer between the p-side guiding layer and the n-side guiding layer, including at least one quantum well layer; the p-type cladding layer and the n-type cladding layer include an AlGaInP layer or a GaInP layer respectively; the quantum well layer includes an AlGaAsP layer.

2. The semiconductor laser device according to claim 1, wherein the p-type cladding layer and the n-type cladding layer respectively include an (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P layer (0x11); the quantum well layer includes an Al.sub.yGa.sub.(1-y)As.sub.(1-x3)P.sub.x3 layer (0x31, 0y33).

3. The semiconductor laser device according to claim 1, further comprising a harmonic oscillator having a length of 200 m to 600 m.

4. The semiconductor laser device according to claim 2, further comprising a harmonic oscillator having a length of 200 m to 600 m.

5. The semiconductor laser device according to claim 1, wherein an oscillation wavelength of the semiconductor laser device is 770 nm to 830 nm, and the quantum well layer has a film thickness of 9 nm to 14 nm.

6. The semiconductor laser device according to claim 2, wherein an oscillation wavelength of the semiconductor laser device is 770 nm to 830 nm, and the quantum well layer has a film thickness of 9 nm to 14 nm.

7. The semiconductor laser device according to claim 3, wherein an oscillation wavelength of the semiconductor laser device is 770 nm to 830 nm, and the quantum well layer has a film thickness of 9 nm to 14 nm.

8. The semiconductor laser device according to claim 1, wherein an end face window structure expanding a bandgap of the active layer is formed on an end face part of a laser harmonic oscillator.

9. The semiconductor laser device according to claim 2, wherein an end face window structure expanding a bandgap of the active layer is formed on an end face part of a laser harmonic oscillator.

10. The semiconductor laser device according to claim 3, wherein an end face window structure expanding a bandgap of the active layer is formed on an end face part of a laser harmonic oscillator.

11. The semiconductor laser device according to claim 5, wherein an end face window structure expanding a bandgap of the active layer is formed on an end face part of a laser harmonic oscillator.

12. The semiconductor laser device according to claim 1, further comprising a GaAs substrate, and the semiconductor laser device oscillates in a Transverse Magnetic (TM) mode.

13. The semiconductor laser device according to claim 2, further comprising a GaAs substrate, and the semiconductor laser device oscillates in a Transverse Magnetic (TM) mode.

14. The semiconductor laser device according to claim 3, further comprising a GaAs substrate, and the semiconductor laser device oscillates in a Transverse Magnetic (TM) mode.

15. The semiconductor laser device according to claim 5, further comprising a GaAs substrate, and the semiconductor laser device oscillates in a Transverse Magnetic (TM) mode.

16. The semiconductor laser device according to claim 8, further comprising a GaAs substrate, and the semiconductor laser device oscillates in a Transverse Magnetic (TM) mode.

17. The semiconductor laser device according to claim 1, further comprising a chip, wherein the chip has a width of 50 m to 250 m; and a thickness of 30 m to 150 m.

18. The semiconductor laser device according to claim 2, further comprising a chip, wherein the chip has a width of 50 m to 250 m; and a thickness of 30 m to 150 m.

19. The semiconductor laser device according to claim 3, further comprising a chip, wherein the chip has a width of 50 m to 250 m; and a thickness of 30 m to 150 m.

20. The semiconductor laser device according to claim 5, further comprising a chip, wherein the chip has a width of 50 m to 250 m; and a thickness of 30 m to 150 m.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be described according to the appended drawings in which:

(2) FIG. 1 is a top view used to illustrate a structure of a semiconductor laser diode according to an implementation manner of the present invention;

(3) FIG. 2 is a sectional view along line II-II in FIG. 1;

(4) FIG. 3 is a sectional view along line in FIG. 1;

(5) FIG. 4 is a diagrammatic sectional view used to illustrate a structure of an active layer of the semiconductor laser diode;

(6) FIG. 5A is an energy band diagram denoting the bandgap of this implementation manner;

(7) FIG. 5B is an energy band diagram denoting the bandgap in a situation when the guiding layer includes InGaAlP;

(8) FIG. 6 is an energy band diagram used to illustrate bandgaps of a cladding layer, a guiding layer and an active layer, FIG. 6 (a) is an energy band diagram denoting bandgaps of layers at a central portion between end face portions of a harmonic oscillator, and FIG. 6 (b) is an energy band diagram denoting bandgaps of layers in an end face window structure formed at an end face portion of a harmonic oscillator;

(9) FIG. 7 is a sectional view denoting a manufacturing step of the semiconductor laser diode;

(10) FIG. 8 is a sectional view denoting a manufacturing step of the semiconductor laser diode;

(11) FIG. 9 is a sectional view denoting a manufacturing step of the semiconductor laser diode; and

(12) FIG. 10 is a sectional view denoting a manufacturing step of the semiconductor laser diode.

PREFERRED EMBODIMENT OF THE PRESENT INVENTION

(13) Below, implementation manners of the present invention are illustrated in detail with reference to accompanying drawings.

(14) FIG. 1 is a top view used to illustrate a structure of a semiconductor laser diode according to an implementation manner of the present invention, FIG. 2 is a sectional view along line II-II in FIG. 1, and FIG. 3 is a sectional view along line III-III in FIG. 1.

(15) The semiconductor laser diode 70 is of a Fabry-Perot type that includes: a substrate 1; a semiconductor stacked structure 2, which is formed on the substrate 1 through crystal growth; an n-type electrode 3, which is formed in a manner of contacting the back of the substrate (a surface opposite to the semiconductor stacked structure 2); and a p-type electrode 4, which is formed in a manner of contacting a surface of the semiconductor stacked structure 2.

(16) The substrate 1 is formed of a GaAs monocrystalline substrate in the implementation manner. The face orientation of the surface of the GaAs substrate 1 has an inclination angle of 10 relative to the face 100. Layers forming on the semiconductor stacked structure 2 epitaxially grow on the substrate 1. The epitaxial growth refers to crystal growth in a state of maintaining the continuity of lattice from a base layer. The mismatching of the lattice of the base layer is absorbed through a distortion of the lattice of the layer under crystal growth, thereby maintaining the continuity of lattice on the interface of the base layer.

(17) The semiconductor stacked structure 2 includes an active layer 10, an n-type semiconductor layer 11, a p-type semiconductor layer 12, an n-side guiding layer 15 and a p-side guiding layer 16. The n-type semiconductor layer 11 is configured at a side of the substrate 1 relative to the active layer 10, and the p-type semiconductor layer 12 is configured at a side of the p-type electrode 4 relative to the active layer 10. The n-side guiding layer 15 is configured between the n-type semiconductor layer 11 and the active layer 10, and the p-side guiding layer 16 is configured between the active layer 10 and the p-type semiconductor layer 12. In this way, a double-heterojunction is formed. Electrons are injected from the n-type semiconductor layer 11 to the active layer 10 through the n-side guiding layer 15, and holes are injected from the p-type semiconductor layer 12 to the active layer 10 through the p-side guiding layer 16. These electrons and holes are re-coupled in the active layer 10 to generate light.

(18) The n-type semiconductor layer 11 is formed of an n-type GaAs buffer layer 13 (for example, thickness of 100 nm) and an n-type (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P cladding layer (0x11) 14 (for example, thickness of 3000 nm) sequentially stacked from a side of the substrate 1. In another aspect, the p-type semiconductor layer 12 is formed of a p-type (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P cladding layer (0x11) 17 (for example, thickness of 16 00 nm), a p-type InGaP band discontinuous buffer layer 18 (for example, thickness of 50 nm) and a p-type GaAs contact layer 19 (for example, thickness of 300 nm) are stacked on the p-type guiding layer 16.

(19) The n-type GaAs buffer layer 13 is a layer disposed to increase cohesiveness between the GaAs substrate 1 and the n-type (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P cladding layer 14. The n-type GaAs buffer layer 13 forms an n-type semiconductor layer by doping; for example, Si as an n-type dopant in GaAs.

(20) The p-type GaAs contact layer 19 is a low resistance layer used to be in an ohmic contact with the p-type electrode 4. The p-type GaAs contact layer 19 forms a p-type semiconductor layer by doping; for example, Zn as a p-type dopant in GaAs.

(21) The n-type cladding layer 14 and the p-type cladding layer 17 are layers generating the optical closing effect to close the light from the active layer 10 between them. The n-type (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P cladding layer 14 forms an n-type semiconductor layer by doping for example, Si as an n-type dopant in (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P. The p-type (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P cladding layer 17 forms a p-type semiconductor layer by doping for example, Zn as a p-type dopant in (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P. Compared with the n-side guiding layer 15, the n-type (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P cladding layer 14 has a wider bandgap, and compared with the p-side guiding layer 16, the p-type (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P cladding layer 17 has a wider bandgap. Therefore, better optical closing and current carrier closing may be performed, thereby achieving an efficient semiconductor laser diode.

(22) In order to achieve high output, the key is to constrain the optical damage of the end face. Therefore, preferably as described below, by diffusing impurities such as zinc at the end face part of the laser harmonic oscillator, the end face window structure 40 expanding the bandgap of the active layer 10 is created. In order to manufacture the end face window structure 40, in the situation of diffusing impurities such as zinc, if the area where impurities should be diffused does not include phosphorus, the diffusion speed is fast. In the implementation manner, the n-type cladding layer 14 and the p-type cladding layer 17 both include an (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P layer containing phosphorus. Therefore, impurities such as zinc can be easily diffused, so it is easy to manufacture the end face window structure 40. Therefore, the semiconductor laser diode capable of high output may be achieved.

(23) Moreover, in the implementation manner, the n-type cladding layer 14 and the p-type cladding layer 17 make the ratio of the In content to the (Al.sub.x1 Ga.sub.(1-x1)) content be 0.49/0.51, so they match the GaAs substrate 1 for lattice, thereby obtaining crystal of high quality. As a result, the semiconductor laser device with high reliability may be obtained.

(24) The n-side guiding layer 15 includes an Al.sub.x2Ga.sub.(1-x2)As (0x21) layer (for example, thickness of 50 nm), and is formed by stacking on the n-type semiconductor layer 11. The p-side guiding layer 16 includes an Al.sub.x2Ga.sub.(1-x2)As (0x21) layer (for example, thickness of 50 nm), and is formed by being stacked on the active layer 10.

(25) The n-side Al.sub.x2Ga.sub.(1-x2)As guiding layer 15 and the p-side Al.sub.x2Ga.sub.(1-x2)As guiding layer 16 are semiconductor layers generating the optical closing effect in the active layer 10, and form a current carrier closing structure together with the cladding layers 14 and 17 for the active layer 10. Therefore, the efficiency of the re-coupling of the electrons and the holes in the active layer 10 is increased.

(26) The refractive index of Al.sub.x2Ga.sub.(1-x2)As changes corresponding to the Al content x2. For example, when energy of incident light (photon energy) is 1.38 eV, the refractive index in the situation of x2=0 (the refractive index of GaAs) becomes 3.590, and the refractive index in the situation of x2=1 (the refractive index of AlAs) becomes 2.971 (with reference to the non-patent document 1). Therefore, in Al.sub.xGa.sub.(1-x1)As, the adjustment extent of the refractive index is wide.

(27) Al.sub.x2Ga.sub.(1-x2)As (0x21) of the n-side guiding layer 15 and the p-side guiding layer 17 is formed; as described above, because the adjustment extent of the bandgap (refractive index) is large, the design of the emerging beam is easy to achieve. For example, a beam whose transverse section has an aspect ratio close to 1 can be outputted, which in other words, the beam whose transverse section is approximately circular.

(28) The Al.sub.x2Ga.sub.(1-x2)As layer of the guiding layers 15 and 16 is formed, preferably having a content satisfying x20.4. The reason for this preference lies in that when x2 is smaller than 0.4, even if the end face window structure is manufactured at the end face part of the laser harmonic oscillator, the bandgap of the active layer on the end face part cannot be fully expanded. Details about this are described below.

(29) The active layer 10 has a multiple-quantum well (MQW) structure, for example AlGaAsP, which is a layer used to generate light through the re-coupling of electrons and holes and to enlarge the generated light.

(30) In the implementation manner, as shown in FIG. 4, the active layer 10 has the following MQW structure: the MQW structure is formed of a quantum well layer (for example, thickness of 13 nm) 221 including an undoped Al.sub.yGa.sub.(1-y)As.sub.1-x3)P.sub.x3 layer (0x31, 0y0.3) and a barrier layer (for example, thickness of 7 nm) 222 including an undoped Al.sub.x4Ga.sub.(1-x4)As layer (0x41) layer which are alternatively repetitively stacked for a plurality of periods. In a distortion-free state, the AlGaAsP layer has a lattice constant smaller than that of the GaAs substrate 1, so a stretching stress (stretching distortion) is generated in the quantum well layer 221 including the Al.sub.yGa.sub.(1-y)As.sub.x3P.sub.(1-x3) layer. Therefore, the semiconductor laser diode 70 may oscillate in the TM mode. Furthermore, the output light in the TM mode becomes TM wave whose magnetic field direction is perpendicular to the light transmission direction (the electric field direction is parallel to the light transmission direction).

(31) The film thickness of the quantum well layer 221 is preferably no less than 9 nm and no more than 14 nm. The reason for this preference lies in that in order to oscillate in the TM mode, the active layer is thickened to reduce the relative oscillation threshold current of the TE mode and the TM mode.

(32) When making the semiconductor laser diode 70 oscillate in the TE mode, the P content in the quantum well layer 221 is reduced. In this situation, the P content is preferably zero during the manufacturing process.

(33) Compared with other materials used as the quantum well layer, for example InGaP, the bandgap of Al.sub.yGa.sub.(1-y)As.sub.(1-x3)P.sub.x3 forming the quantum well layer 221 is smaller. Therefore, the difference between the bandgap of the cladding layers 14 and 17 and the active layer 10 may be increased. Consequently, a semiconductor laser diode, which has good temperature characteristics, i.e. the threshold current or action current changes less while the temperature is changed, can be realized.

(34) The A.sub.yGa.sub.(1-y)As.sub.(1-x3)P.sub.x3 layer of the quantum well layer 221 is formed, which preferably the contents of P and As in the Al.sub.yGa.sub.(1-y)As.sub.(1-x3)P.sub.x3 layer are x3 and (1x3), respectively, and a ratio of x3/(1x3) is no more than . The reason for this preference lies in that if the ratio is larger than , the stretching distortion generated in the quantum well layer 221 is increased due to the increase of the P content, so there exists the concern that a crack or leakage may be generated.

(35) Further, the contents of P and As in the A.sub.yGa.sub.(1-y)As.sub.(1-x3)P.sub.x3 layer are x3 and (1x3), respectively, and a ratio of x3/(1x3) is no less than 1/9. The reason for this preference lies in that compared with the TE mode, the ratio (strength ratio) in the TM mode is increased. In order to make the semiconductor laser device 70 oscillate in the TM mode, the stretching distortion must be generated in the quantum well layer 221. The smaller the lattice constant of the quantum well layer 221 is, the larger the stretching distortion generated at the quantum well layer 221 is. The larger the ratio of the P content to the As content is, the smaller the lattice constant of the Al.sub.yGa.sub.(1-y)As.sub.(1-x3)P.sub.x3 layer forming in the quantum well layer 221 is.

(36) As shown in FIG. 3, a p-type cladding layer 17, a p-type band discontinuous buffer layer 18 and a p-type contact layer 19 in a p-type semiconductor layer 12 form a carinate stripe 30 by removing a part thereof. More specifically, a part of the p-type cladding layer 17, the p-type band discontinuous buffer layer 18 and the p-type contact layer 19 are etched away to form the carinate stripe 30, which is rather rectangular when observing its transverse cross section.

(37) A side of the p-type contact layer 19, an exposed face of the p-type band discontinuous buffer layer 18 and an exposed face of the (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P cladding layer 17 are covered by a current barrier layer 6.

(38) A semiconductor stacked structure 2 includes a pair of end faces (cleavage planes) 31 and 32 formed of cleavage planes at two ends in the length direction of the carinate stripe 30. The pair of end faces 31 and 32 are parallel to each other. In this way, a Fabry-Perot harmonic oscillator in which the pair of end faces 31 and 32 are set to the end faces of the harmonic oscillator is formed through an n-side guiding layer 15, an active layer 10 and a p-side guiding layer 16. That is, light is generated in the active layer 10 goes back and forth between the end faces 31 and 32 of the harmonic oscillator on one hand, and is enlarged through sensing release on the other hand. Then, a part of the enlarged light emerges as laser light from the end faces 31 and 32 of the harmonic oscillator to the outside of the device.

(39) The length of the harmonic oscillator, for example, is no less than 200 m and no more than 600 m, and in the implementation manner is 300 m. Moreover, the chip width of the semiconductor laser diode 70, for example, is no less than 50 m and no more than 250 m, and in the implementation manner is 120 m. Moreover, the chip thickness, for example, is no less than 30 m and no more than 150 m, and in the implementation manner is 50 m.

(40) An n-type electrode 3 includes for example, AuGe/Ni/Ti/Au alloy, and is in an ohmic bond with the substrate 1 in a manner in which the AuGe side is configured at a side of the substrate 1. The p-type electrode 4 is formed in a manner that covers the exposed faces of the p-type contact layer 19 and the current barrier layer 6. The p-type electrode 4 includes for example, Ti/Au alloy, and is in an ohmic bond with the p-type contact layer 19 in a manner in which the Ti side is configured on the p-type contact layer 19. As shown in FIG. 1 and FIG. 2, the end face window structure 40 expanding the bandgap of the active layer 10 is formed at the end face part of the harmonic oscillator. The end face window structure 40 is formed by, for example, diffusing zinc (Zn) at the end face part of the harmonic oscillator.

(41) According to the structure, the n-type electrode 3 and the p-type electrode 4 are connected to a power source, and inject electrons and holes to the active layer 10 from the n-type semiconductor layer 11 and the p-type semiconductor layer 12; therefore, the re-coupling of the electrons and the holes may be generated in the active layer 10, thereby generating, for example, light with the oscillation wavelength of no less than 770 nm and no more than 830 nm. The light goes back and forth between the end faces 31 and 32 of the harmonic oscillator along the guiding layers 15 and 16, and is enlarged through sensing release on the other hand. Then, more emerging laser is output outside from the end face 31 of the harmonic oscillator as a laser emerging end face.

(42) FIG. 5A is an energy band diagram used to illustrate the bandgaps of the cladding layers 14 and 17, the guiding layers 15 and 16, and the active layer 10. FIG. 5B is an energy band diagram used to illustrate the bandgaps of the layers in a situation that InGaAlP as a phosphorus group compound semiconductor forms a guiding layer.

(43) In the semiconductor laser diode 70 of the implementation manner, the quantum well layer 221 in the active layer 10 includes an Al.sub.yGa.sub.(1-y)As.sub.(1-x3)P.sub.x3 layer (0x31, 0y0.3) as an arsenic group compound semiconductor. In the semiconductor laser diode 70 of the implementation manner, the cladding layers 14 and 17 are formed of a phosphorus group compound semiconductor (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P (0.5x11), and in another aspect, the guiding layers 15 and 16 are formed of an arsenic group compound semiconductor (Al.sub.x2Ga.sub.(1-x2)As (0x21)) instead of a phosphorus group compound semiconductor.

(44) As shown by comparing FIG. 5A and FIG. 5B, when the situation that Al.sub.x2Ga.sub.(1-x2)As as an arsenic group compound semiconductor forms the guiding layers 15 and 16 (FIG. 5A) is compared with the situation that InGaAlP as a phosphorus group compound semiconductor forms the guiding layer (FIG. 5B), the bandgap Eu of the guiding layers 15 and 16 can be reduced. Therefore, in the semiconductor laser diode 70 of this implementation manner, the difference (EuEg) between the bandgap Eu of the guiding layers 15 and 16 and the bandgap Eg of the quantum well layer 221 may be reduced.

(45) Generally, in a situation regarding semiconductor, the smaller the bandgap difference is, the smaller the refractive index difference is, so the optical closing effect may be prevented from becoming excessively large, thereby buffering the optical density on the end face part of the laser harmonic oscillator. Therefore, the optical damage of the end face may be constrained, thereby achieving high output. Moreover, compared with the guiding layer including InGaAlP, the Al.sub.x2Ga.sub.(1-x2)As guiding layers 15 and 16 have higher heat conductivity, and therefore may also have the advantage of efficiently diffusing heat. Therefore, it is helpful that the semiconductor laser diode 70 may be controlled stably, and the optical damage of the end face can be constrained.

(46) FIG. 6 (a) is an energy band diagram denoting bandgaps of layers at a central portion between end face portions of a harmonic oscillator. FIG. 6 (b) is an energy band diagram denoting bandgaps of layers in an end face window structure formed at an end face portion of a harmonic oscillator.

(47) In the foregoing implementation manner, the end face part of the harmonic oscillator is formed with the end face window structure 40 expanding the bandgap of the active layer 10. Therefore, as shown in FIG. 6 (b), in the end face part of the harmonic oscillator, the bandgap Eg of the active layer 10 becomes an average value of the bandgap Eg (with reference to FIG. 6 (a)) of the active layer 10 in the middle of the harmonic oscillator and the bandgap Eu (with reference to FIG. 6 (a)) of the guiding layers 15 and 16 (barrier layer 222). That is, in the end face part of the harmonic oscillator, compared with these middle parts, the bandgap Eg of the active layer 10 becomes larger. Therefore, it is difficult for the sensing released light generated through the re-coupling of internal electrons and holes to be absorbed at the end face part of the harmonic oscillator, thereby constraining heat generation. Therefore, generation of the optical damage of the end face may be constrained, thereby achieving high output.

(48) The reason why the Al.sub.x2Ga.sub.(1-x2)As layer forming the guiding layers 15 and 16 is preferably to have contents satisfying x20.4 is detailed below. When the end face window structure 40 is created at the end face part of the laser harmonic oscillator, the bandgap of the active layer 10 on the end face part becomes the average value of the bandgap of the guiding layers 15 and 16 and the bandgap of the quantum well layer 221. Therefore, in order to fully expand the bandgap of the active layer 10 at the end face part by creating the end face window structure 40, the bandgap of the guiding layers 15 and 16 must become a value that is no less than a particular value (specifically, about 1.8 eV). In another aspect, as far as the bandgap of the Al.sub.x2Ga.sub.(1-x2)As layer forming the guiding layers 15 and 16 is concerned, the more the Al content contained therein, that is, the larger x2 is, the larger the bandgap thereof is. Also, the bandgap of the guiding layers 15 and 16 may be no less than the particular value by enabling x2 to be no less than 0.4.

(49) FIG. 7 to FIG. 10 are transverse cross section diagrams denoting a manufacturing method for the semiconductor laser diode 70 shown in FIG. 1 to FIG. 3.

(50) Firstly, as shown in FIG. 7, an n-type GaAs buffer layer 13, an n-type (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P cladding layer 14, an n-side Al.sub.x2Ga.sub.(1-x2)As guiding layer 15, an active layer 10, a p-side Al.sub.x2Ga.sub.(1-x2)As guiding layer 16, a p-type (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P cladding layer 17, a p-type InGaP band discontinuous buffer layer 18 and a p-type GaAs contact layer 19 sequentially grows on a GaAs substrate 1 through Metal Organic Chemical Vapor Deposition (MOCVD). Furthermore, the active layer 10 is formed through growth of a quantum well layer 221 including an Al.sub.yGa.sub.(1-y)As.sub.(1-x3)P.sub.x3 layer and a barrier layer 222, which includes an Al.sub.x4Ga.sub.(1-x4)As layer, alternatively repetitively stacked for a plurality of periods.

(51) Secondly, referring to FIG. 1, at an area close to the end face of the semiconductor laser diode 70, ZnO (zinc oxide) is patterned. Then, annealing processing is performed for about 8 hours at 500 to 650 C., for example, and therefore Zn is diffused at the area close to the end face of the semiconductor laser diode 70. In this case, annealing processing is performed in a manner to make Zn be diffused across the active layer 10 and the n-side guiding layer 15 and reach the n-type cladding layer 14. Therefore, the end face window structure 40 is formed at the area close to the end face of the semiconductor laser diode 70.

(52) Subsequently, the ZnO layer is removed. Then, as shown in FIG. 8, a stripe-shaped insulating film as a mask 54 is etched, and therefore a part of the p-type GaAs contact layer 19, the InGaP band discontinuous buffer layer 18 and the p-type (Al.sub.x1Ga.sub.(1-x1)).sub.0.51In.sub.0.49P cladding layer 17 are removed. In this way, as shown in FIG. 9, the carinate stripe 30 stacked with the mask layer 54 on the top face is formed.

(53) Then, as shown in FIG. 10, the current barrier layer 6 is enabled to form a film on a surface. In this case, the mask layer 54 functions as a mask. Therefore, the top face of the carinate stripe 30 is not covered by the current barrier layer 6.

(54) Afterward, the mask layer 54 is removed. Subsequently, in a manner of covering the exposed faces of the current barrier layer 6 and the p-type GaAs contact layer 19, the p-type electrode 4 in an ohmic contact with the p-type GaAs contact layer 19 is formed. Moreover, the n-type electrode 3 in an ohmic contact with the GaAs substrate 1 is formed.

(55) Above, an implementation manner of the present invention is illustrated, but the present invention may be further implemented in other manners. For example, a semiconductor laser diode in which P is not added in the quantum well layer and in which oscillate in the TE mode may also be configured.

(56) While several embodiments of the present invention have been illustrated and described, various modifications and improvements can be made by those skilled in the art. The embodiments of the present invention are therefore described in an illustrative but not in a restrictive sense. It is intended that the present invention should not be limited to the particular forms as illustrated and that all modifications which maintain the spirit and scope of the present invention are within the scope defined in the appended claims.