JP3641403B2 - Semiconductor laser device and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a semiconductor laser device and a manufacturing method thereof.
[0002]
[Prior art]
  In recent years, various types of semiconductor laser elements have been widely used as light sources for optical disk devices. In particular, a high-power 780 nm band AlGaAs semiconductor laser element is used as a light source for writing on a disk such as an MD (Mini Disc) player or a CD-R (Compact Disc-Recordable) drive.
[0003]
  Conventionally, there are semiconductor laser elements as shown in FIGS. 11 (a) and 11 (b). This semiconductor laser device is manufactured as follows.
[0004]
  First, an n-type GaAs buffer layer 102, an n-type AlGaAs first clad layer 103, an n-type AlGaAs second clad layer 104, a light guide layer 105, an n-type GaAs substrate 101 are formed using metal organic vapor phase epitaxy. A multiple quantum well (MQW) active layer 106, a light guide layer 107, a p-type AlGaAs first cladding layer 108, a p-type GaAs etching stop layer 109, a p-type AlGaAs second cladding layer 110, and a p-type GaAs protective layer 111 are sequentially formed. To do.
[0005]
  Next, after forming a stripe-shaped mask on the surface of the p-type GaAs protective layer 111, etching is performed by wet etching until the p-type GaAs etching stop layer 109 appears in a region not covered with the mask. A ridge stripe 150 of a current path composed of the AlGaAs second cladding layer 110 and the p-type GaAs protective layer 111 is formed. After the ridge stripe 150 is formed, the mask formed on the ridge stripe 150 is removed, and then the n-type AlGaAs current confinement layer 112, the n-type GaAs current confinement layer 113, p are used again by metal organic chemical vapor deposition. The type GaAs planarization layer 114 is sequentially formed to provide a current confinement region on the side surface of the ridge stripe 150. At this time, since the unnecessary n-type AlGaAs current confinement layer 112, n-type GaAs current confinement layer 113, and p-type GaAs planarization layer 114 are formed on the ridge stripe 150, a mask is formed on the current confinement region, and the ridge Unnecessary layers on the stripe 150 are removed. After removing the unnecessary layer, the mask formed on the current confinement region is removed, and then the p-type GaAs contact layer 115 is formed again by metal organic vapor phase epitaxy. Thereafter, the p-side electrode 116 and the n-side electrode 117 are formed and divided into a plurality of bars so as to have an arbitrary resonator length.
[0006]
  Immediately after splitting the bars, align multiple bars and place them in an electron beam vapor deposition machine.₂O_ThreeA film 118 is formed and Al is formed on the light emitting end face on the rear surface side.₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeA film 119 is formed. Thereafter, when the bar is divided into chips, the semiconductor laser device shown in FIGS. 11A and 11B is completed.
[0007]
[Problems to be solved by the invention]
  By the way, in a semiconductor laser element, when the drive current is increased and the light output is increased, the light output is suddenly reduced and irreversible destruction occurs. Such a phenomenon is called optical damage (COD) and occurs with an increase in light output density in the active layer region near the light emitting end face.
[0008]
  The cause of the COD is that the active layer region near the light emitting end face is an absorption region for laser light. On the light emitting end face, unlike the inside of the crystal, many of the bonds of the lattice atoms are left behind at the portion facing the crystal surface. That is, there are dangling bonds (dangling bonds) on the light emitting end face, and there are many non-radiative recombination centers called surface states or interface states. Since the carriers injected into the active layer region near the light emitting end face are lost by this non-radiative recombination, the injected carrier density in the active layer region near the light emitting end face is smaller than that in the central portion of the active layer. As a result, the active layer region in the vicinity of the light emitting end face becomes an absorption region with respect to the wavelength of the laser beam produced by the high injected carrier density at the center of the active layer region.
[0009]
  Thus, in the active layer region near the light emitting end face, when the light output density is increased, local heat generation is increased, the temperature is increased, and the band gap is reduced. As a result, a positive feedback that the absorption coefficient further increases and the temperature rises is applied, so that the temperature of the absorption region of the active layer finally reaches the melting point and COD is generated.
[0010]
  In the conventional semiconductor laser device shown in FIG. 11, in order to suppress the generation of COD, Al is used as a light emitting end face protective film.₂O_ThreeFilm 118, Al₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeA dielectric film having a high thermal conductivity such as the film 119 is used to suppress a temperature rise in the region of the MQW active layer 106 near the light emitting end face. However, in the vicinity of the boundary between the light emitting end face protective film and the active layer, there are many point defects and oxygen impurities such as non-radiative recombination centers, so that an absorption region is generated. Therefore, since the critical light output of the COD does not increase, there is a problem that long-term reliability is lowered in a high output operation.
[0011]
  As a result of studying the above problems, the present invention has invented a semiconductor laser device excellent in long-term reliability at a high output operation and a manufacturing method thereof.
[0012]
[Means for Solving the Problems]
  In order to achieve the above object, a semiconductor laser device of the present invention includes a first conductivity type first cladding layer, an active layer, and a second conductivity type second cladding layer on a first conductivity type substrate, Light that protects the region of the active layer is formed by laminating a ridge stripe that is a third clad layer of the second conductivity type and forming a current confinement layer of the first conductivity type so as to sandwich the ridge stripe from both sides. In a semiconductor laser device in which a dielectric film as an emission end face protective film is formed on the light emission end face, the dielectric film in the vicinity of the light emission end face has a region containing a group III atom and a group V atom.And the above area II Group atoms and VI Containing group atoms, above II Group atom is zinc , beryllium , Any one of magnesiumIt is characterized by that.
[0013]
  According to the semiconductor laser device having the above configuration, the dielectric film as the light emitting end face protective film for protecting the active layer region is formed on the light emitting end face, and the group III is formed in the dielectric film near the light emitting end face. By forming a region including atoms and group V atoms, diffusion of group III atoms, group V atoms, and the like from the active layer to the dielectric film side during high output driving is suppressed. That is, it is possible to suppress point defects on the light emitting end face in the active layer region during high output driving. As a result, the active layer region in the vicinity of the light emitting end face is less likely to be an absorption region with respect to the wavelength of the laser light produced by the high injected carrier density in the central portion of the active layer. Therefore, local heat generation is suppressed in the active layer in the vicinity of the light emitting end face, the COD critical light output is high, and a decrease in the COD critical light output during high output driving can be suppressed.
[0014]
[0015]
  UpActivityA dielectric film as a light emitting end face protective film for protecting the region of the light emitting layer is formed on the light emitting end face, and in the dielectric film near the light emitting end face, a group II atom, a group III atom, a group V atom and VI By having a region including group atoms, it is possible to suppress diffusion of group III atoms, group V atoms, and the like from the active layer to the dielectric film side during high-power driving. Further, even if group III atoms and group V atoms diffuse from the active layer to the dielectric film side, vacancies such as group III atoms and group V atoms exist in the dielectric film near the light emitting end face. Since the group II and group VI atoms are complemented, the occurrence of point defects can be suppressed. As a result, the active layer region in the vicinity of the light emitting end face is less likely to be an absorption region with respect to the wavelength of the laser light produced by the high injected carrier density in the central portion of the active layer. Therefore, local heat generation is suppressed in the active layer in the vicinity of the light emitting end face, the COD critical light output is high, and a decrease in the COD critical light output during high output driving can be further suppressed.
[0016]
[0017]
  UpRecord IISince the group atom is any one of zinc, beryllium, and magnesium, the increase in non-radiative recombination centers can be more effectively suppressed, thus improving long-term reliability at high output drive. Can be made.
[0018]
  The semiconductor laser device according to an embodiment of the present invention is characterized in that the group VI atom is sulfur.
[0019]
  According to the semiconductor laser device of the embodiment of the present invention, since the group VI atom is sulfur, an increase in non-radiative recombination centers can be more effectively suppressed. The long-term reliability can be further improved.
[0020]
  A semiconductor laser device according to an embodiment of the present invention is characterized by having a current non-injection region formed in the vicinity of the light emitting end face.
[0021]
  According to the semiconductor laser device of one embodiment of the present invention, the non-light-emitting recombination is present in the region of the active layer near the light emitting end surface by having a current non-injection region formed near the light emitting end surface. It is possible to suppress the carrier loss due to the center and the surface leakage current generated by the group II and group VI atoms present on the light exit end face. Can improve long-term reliability.
[0022]
  Further, in the semiconductor laser device of one embodiment of the present invention, a disordered region is formed in the region of the active layer in the vicinity of the light emitting end face, and the band gap of the disordered region is larger than the band gap in the central portion of the active layer. It is also characterized by being large.
[0023]
  According to the semiconductor laser device of one embodiment of the present invention, the disordered region formed in the active layer region near the light emitting end face has a larger band gap than the central portion of the active layer. Laser absorption by group II and group VI atoms present in the active layer region is reduced, and long-term reliability at high output drive can be improved.
[0024]
  The method of manufacturing a semiconductor laser device of the present invention includes a first conductivity type first cladding layer, an active layer, a second conductivity type second cladding layer, and a second conductivity type on a first conductivity type substrate. The third conductive layer is formed into a ridge stripe by wet etching, and the first conductive type current confinement layer is formed so as to sandwich the ridge stripe from both sides. In the method of manufacturing a semiconductor laser device to be formed, a step of removing a surface oxide film formed on a light emitting end face, and a step of covering the light emitting end face from which the surface oxide film has been removed with a group II atom and a group VI atom It is characterized by having.
[0025]
  According to the method of manufacturing a semiconductor laser device having the above configuration, the surface oxide film formed on the light emitting end face is removed, and the light emitting end face from which the surface oxide film has been removed is covered with a group II atom and a group VI atom. As a result, dangling bonds on the light emitting end face are reduced, so that an effect of reducing the surface level of the light emitting end face and suppressing adhesion of oxygen atoms to the light emitting end face is obtained, and a dielectric is formed on the light emitting end face. Until the body film is formed, the effects of group VI atom detachment, suppression of evaporation, and suppression of re-formation of the oxide film on the light emitting end face can be obtained. That is, it is possible to reduce non-radiative recombination centers called surface states or interface states as much as possible, and to suppress proliferation of non-radiative recombination centers during high output driving. As a result, the active layer region in the vicinity of the light emitting end face is less likely to be an absorption region with respect to the wavelength of the laser light produced by the high injected carrier density in the central portion of the active layer. Therefore, it is possible to manufacture a semiconductor laser element that is superior in long-term reliability at high output operation.
[0026]
  According to one embodiment of the present invention, there is provided a semiconductor laser device manufacturing method comprising: a first conductivity type first cladding layer; an active layer; and a second conductivity type second cladding layer on a first conductivity type substrate. The second conductivity type third clad layer is laminated, the second conductivity type third clad layer is formed into a ridge stripe by wet etching, and the first conductivity type is sandwiched from both side surfaces. And a step of removing a surface oxide film formed on the light emitting end face, and the light emitting end face from which the surface oxide film has been removed is divided into a group II atom and a group VI. A step of coating with atoms, a step of forming a dielectric film as a light emitting end face protective film for protecting the active layer region on the light emitting end face, and a group III atom and a group V atom in the dielectric film. A step of diffusing It is characterized.
[0027]
  According to the method of manufacturing the semiconductor laser device of the one embodiment, the surface oxide film formed on the light emitting end face is removed, and the light emitting end face from which the surface oxide film has been removed is replaced with a group II atom and a VI. After covering with a group atom, a dielectric film as a light emitting end face protective film protecting the active layer is formed on the light emitting end face, and a group III atom and a group V atom are diffused in the dielectric film. As a result, a region containing Group II atoms, Group III atoms, Group V atoms, and Group VI atoms is formed in the dielectric film in the vicinity of the light emitting end face, so that the semiconductor has excellent long-term reliability at high output operation. A laser element can be manufactured.
[0028]
  In one embodiment of the method of manufacturing a semiconductor laser device, the dielectric film is formed after heat treatment is performed so that the temperature of the light emitting end face is 150 ° C. or more and 300 ° C. or less. It is a feature.
[0029]
  According to the method of manufacturing a semiconductor laser device of the one embodiment, the light from which the surface oxide film has been removed by performing the heat treatment so that the temperature of the light emitting end face is 150 ° C. or higher and 300 ° C. or lower. Moisture adhering to the light exit end face after the exit end face is coated with a group II atom and a group VI atom can be evaporated, and a group III atom, a group V atom, a group II atom, and a group VI near the light exit end face Re-evaporation of atoms can be suppressed. Therefore, point defects on the light emitting end face in the active layer region do not multiply, and a semiconductor laser device having excellent long-term reliability in high output driving can be stably obtained.
[0030]
  In addition, when the heat treatment is performed so that the temperature of the light emitting end surface is less than 150 ° C., the dielectric film is formed in a state in which moisture attached on the II and VI group atoms coated on the light emitting end surface is not completely evaporated. Therefore, an oxide film is formed on the light emitting end face. As a result, the growth of the oxide film occurs at the time of high output driving, and with the growth of the oxide film, the group III atom and the group VI atom diffuse to the oxide film side, and on the light emitting end face of the active layer region. Concentrate and point defects will multiply.
[0031]
  In addition, when the heat treatment is performed so that the temperature of the light emission end face exceeds 300 ° C., the group II atom, the group III atom, the group V atom, and the group VI atom in the vicinity of the light emission end face are evaporated, and the light emission end face Many point defects are formed.
[0032]
  A method for manufacturing a semiconductor laser device according to an embodiment of the invention is characterized in that the surface oxide film formed on the light emitting end face is removed with an ammonia sulfide solution.
[0033]
  According to the method of manufacturing a semiconductor laser device of the invention of the one embodiment, the surface oxide film is removed with the ammonia sulfide solution in the step of removing the surface oxide film formed on the light emitting end face of the active layer region. The step of removing the surface oxide film formed on the light emission end face of the active layer region and the step of covering the light emission end face from which the surface oxide film has been removed can be performed simultaneously. Therefore, the number of work steps can be reduced and productivity can be improved.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, a semiconductor laser device and a manufacturing method thereof according to the present invention will be described in detail with reference to embodiments shown in the drawings.
[0035]
  (First embodiment)
  FIG. 1A shows the semiconductor laser device according to the first embodiment of the present invention viewed from the light emitting end face side.RefusalFIG. 1B is a sectional view of the semiconductor laser element as viewed from the side. 2 to 5 are views for explaining a method of manufacturing the semiconductor laser device.
[0036]
  A method for manufacturing the semiconductor laser element shown in FIGS. 1A and 1B will be described below.
[0037]
  First, in the first crystal growth by metal organic vapor phase epitaxy, an n-type GaAs buffer layer 2 and a first-conductivity-type first cladding layer are formed on an n-type GaAs substrate 1 as a first-conductivity-type substrate. n-type AlGaAs first cladding layer 3, n-type AlGaAs second cladding layer 4, light guide layer 5, multiple quantum well (MQW) active layer 6 as an active layer, light guide layer 7, second conductivity type second cladding A p-type AlGaAs first cladding layer 8 as a layer, a p-type GaAs etching stop layer 9, a p-type AlGaAs second cladding layer 10 as a second conductivity type third cladding layer, and a p-type GaAs protective layer 11 are sequentially stacked. .
[0038]
  Next, a stripe-shaped mask having a desired width is formed on the p-type GaAs protective layer 11, and the p-type in a region not covered with the stripe-shaped mask with a mixed solution of sulfuric acid and hydrogen peroxide. The GaAs protective layer 11 and a part of the p-type AlGaAs second cladding layer 10 are etched. Subsequently, in order to remove the remaining p-type AlGaAs second cladding layer 10 in the region not covered with the mask, etching is performed until the p-type GaAs etching stop layer 9 is exposed by hydrofluoric acid. A ridge stripe 50 of a current path composed of the p-type AlGaAs second cladding layer 10 and the p-type GaAs protective layer 11 is formed.
[0039]
  After the ridge stripe 50 is formed, the mask formed on the ridge stripe 50 is removed, and an n-type AlGaAs current as a first conductivity type current confinement layer is formed by second crystal growth by metal organic vapor phase epitaxy. A block layer 12, an n-type GaAs current blocking layer 13 as a first conductivity type current confinement layer, and a p-type GaAs planarization layer 14 are sequentially stacked.
[0040]
  Thereafter, in order to remove unnecessary layers 12-14 (n-type AlGaAs current blocking layer 12, n-type GaAs current blocking layer 13, and p-type GaAs planarization layer 14) formed on the ridge stripe 50, the ridge stripe is removed. A mask is formed in 50 outer regions. Then, the n-type GaAs current blocking layer 13 and the p-type GaAs planarizing layer 14 formed on the ridge stripe 50 are removed by etching with a mixed solution of ammonia water and hydrogen peroxide water, and then sulfuric acid and hydrogen peroxide water are used. The n-type AlGaAs current blocking layer 12 formed on the ridge stripe 50 is removed by etching using a mixed solution. After the unnecessary layer on the ridge stripe 50 is removed, the mask formed in the external region of the ridge stripe 50 is removed.
[0041]
  Then, a p-type GaAs contact layer is formed on the surface of the p-type GaAs protective layer 11 and the p-type GaAs planarization layer 14 which are the outermost surfaces after removing the unnecessary layer by third crystal growth by metal organic vapor phase epitaxy. 15 is formed. Thereafter, a p-side metal electrode 16 is deposited on the surface of the p-type GaAs contact layer 15, and an n-side metal electrode 17 is deposited on the surface of the n-type GaAs substrate 1.
[0042]
  When a wafer (substrate) on which a plurality of such semiconductor laser element structures are formed is opened in a direction perpendicular to the direction in which the ridge stripe 50 extends and is divided into bars so that the resonator length is 800 μm. The bar 21 shown in FIG.
[0043]
  The bar 21 is immersed in a mixed solution of sulfuric acid and hydrogen peroxide solution for 10 seconds, and then washed with pure water. By this process, the surface oxide films 20 and 20 formed on the light emitting end face are removed.
[0044]
  Next, the bar 21 from which the surface oxide films 20, 20 have been removed is immersed in an ammonium sulfide solution for 10 seconds, and then washed with pure water. By this processing, the light emitting end face is covered with sulfur (S) atoms 25, 25, and the bar 22 shown in FIG. 3 is obtained.
[0045]
  Next, the bar 22 is immersed in a zinc acetate solution for 30 seconds, washed with pure water, and then dried. By this treatment, the light emitting end face is covered with sulfur (S) atoms 25, 25 and zinc (Zn) atoms 26, 26, resulting in the bar 23 shown in FIG.
[0046]
  After that, the plurality of bars 23 are aligned and placed in an electron beam vapor deposition machine, and heated so that the end face temperature of the bars 23, that is, the temperature of the light emitting end face becomes, for example, 250 ° C., and then a dielectric is formed on the light emitting end face on the front side. Al as film₂O_ThreeWhile the film 18 is formed, Al as a dielectric film is formed on the light emitting end face on the rear side.₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeWhen the film 19 is formed, the bar 24 shown in FIG. 5 is obtained. When this bar 24 is divided into chips, the semiconductor laser device of the present invention shown in FIGS. 1A and 1B is completed.
[0047]
  In addition, for comparison with the semiconductor laser device of the present embodiment, immediately after dividing the bars, a plurality of bars are immediately aligned and placed in an electron beam vapor deposition machine, and the light emitting end face on the front side is made of Al.₂O_ThreeA film 118 is formed and Al is formed on the light emitting end face on the rear surface side.₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeAfter forming the film 119, the conventional semiconductor laser device shown in FIGS. 11A and 11B obtained by dividing the bar into chips was also fabricated at the same time.
[0048]
  MQW active layers 6 and 106 in the semiconductor laser device of FIGS. 1A and 1B obtained by the manufacturing method of the present embodiment and the conventional semiconductor laser device of FIGS. 11A and 11B. Al deposited on the light emitting end face (front face) in the vicinity₂O_ThreeThe depth direction distribution of impurity atoms in the films 18 and 118 was measured with a secondary ion mass spectrometer (SIMS), and the measurement results are shown in FIGS. FIG. 6 shows the measurement results of the semiconductor laser device of this embodiment, and FIG. 7 shows the measurement results of the conventional semiconductor laser device of FIGS. 11 (a) and 11 (b). 6 and 7, the vertical axis represents the number of secondary ions detected per second (c / s), and the horizontal axis represents Al.₂O_ThreeThe depth (Å) from the film surface is shown.
[0049]
  As shown in FIG. 6, Al in the vicinity of the light emitting end face of the semiconductor laser device of the present embodiment described above.₂O_ThreeIn the film 18, the light emitting end face / Al₂O_ThreeIn the range of about 400 mm from the film interface, there is a group III atom Ga and a group V element As. On the other hand, as shown in FIG. 7, Al in the vicinity of the light emitting end face of the conventional semiconductor laser device is used.₂O_ThreeGa and As are not present in the film 118. In the conventional semiconductor laser device, the light emitting end face / Al₂O_ThreeAlthough a peak of oxygen atoms is observed at the film interface, in the semiconductor laser device of this embodiment of the present invention, the light emitting end face / Al₂O_ThreeThere is no peak of oxygen atoms at the film interface.
[0050]
  Further, the characteristics of the present embodiment and the conventional semiconductor laser device were measured.
[0051]
  As a result, the oscillation wavelength of the present embodiment and the conventional semiconductor laser device were both 785 nm, but the maximum output power of the semiconductor laser device of the present embodiment was 270 mW in the result of the maximum output test. The maximum light output of the laser element was 220 mW. That is, the maximum laser output of the semiconductor laser device of the present embodiment is improved by about 20% compared to the conventional case.
[0052]
  Further, in the result of the reliability test at 60 ° C. and 85 mW, the average lifetime of the conventional semiconductor laser element is 190 hours, whereas the semiconductor laser element of this embodiment is about 3000 hours, which is about 15 hours longer than the conventional one. Double the average lifespan.
[0053]
  The lifetime of the semiconductor laser device of the present embodiment is improved from the lifetime of the conventional semiconductor laser device because the group III atoms (Ga) and group V atoms from the MQW active layer 6 to the dielectric film side at the time of high output driving. This is probably because the diffusion of (As) is suppressed, and it becomes possible to suppress point defects on the light emitting end face in the region of the MQW active layer 6 at the time of high output driving.
[0054]
  From the above, as a light emitting end face protective film for protecting the light emitting end face, Al₂O_ThreeFilm 18, Al₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeBy forming a dielectric film of the film 19 and forming a region containing group III atoms (Ga) and group V atoms (As) in the dielectric film in the vicinity of the light emitting end face, long-term reliability at high output drive It can be seen that it can be improved.
[0055]
  In the first embodiment, Al is used to form the dielectric film.₂O_ThreeHowever, the same effect can be obtained by using at least one of AlxOy, SixOy, AlxNy, SixNy (where x and y are 1 or more).
[0056]
  In the first embodiment, the semiconductor laser element including AlGaAs is used. However, the same effect can be obtained by using a semiconductor laser element including at least one of AlGaInP, InGaAs, InGaAsP, and the like.
[0057]
  In the first embodiment, a mixed solution of sulfuric acid and hydrogen peroxide solution is used in the step of removing the surface oxide film formed on the light emitting end face. However, for example, hydrofluoric acid capable of removing the surface oxide film. The same effect can be obtained by using a solution such as
[0058]
  In the first embodiment, the ammonium sulfide solution is used in the step of coating the light emitting end face from which the surface oxide film has been removed with a group VI atom. For example, an ammonium sulfide solution, a gallium sulfide solution, and an aluminum sulfide solution are used. Even if any one of these is used, the same effect can be obtained.
[0059]
  In the first embodiment, Al in the vicinity of the light emitting end face is used.₂O_ThreeFilm, Al₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeAlthough zinc (Zn) atoms are used as group II atoms contained in the film, the same effect can be obtained by using either one of beryllium or magnesium.
[0060]
  In the first embodiment, the zinc acetate solution is used in the step of coating the light emitting end face from which the surface oxide film has been removed with a group II atom. For example, zinc chloride, beryllium chloride, magnesium chloride, zinc sulfate, The same effect can be obtained by using any one of beryllium sulfate and magnesium sulfate.
[0061]
  (Second embodiment)
  The semiconductor laser device according to the second embodiment of the present invention is manufactured as follows.
[0062]
  A wafer (substrate) on which a plurality of semiconductor laser device structures described in the first embodiment are formed is opened in a direction perpendicular to the direction in which the ridge stripe extends so that the resonator length is 800 μm, and the bar Divide into shapes. The following processing is performed on the plurality of bars formed by the bar division. First, it is immersed in an ammonium sulfide solution for 60 seconds, and then washed with pure water. And after immersing in a zinc acetate solution for 30 seconds, it wash | cleans with a pure water and is made to dry.
[0063]
  Thereafter, the plurality of bars are aligned and put into an electron beam vapor deposition machine, heated after the bar end surface temperature, that is, the light emitting end surface temperature is, for example, 250 ° C., and then a dielectric film is formed on the light emitting end surface on the front side. Al₂O_ThreeA film is formed, and a dielectric film is formed on the light emitting end face on the rear side.₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeA film is formed and the bar is divided into chips.
[0064]
  In the semiconductor laser device obtained by the above manufacturing method, Al deposited on the light emitting end face (front surface) in the vicinity of the MQW active layer₂O_ThreeThe depth direction distribution of impurity atoms in the film was measured with a secondary ion mass spectrometer (SIMS), and the measurement results are shown in FIG. In FIG. 8, the vertical axis represents the number of secondary ions detected per second (c / s), and the horizontal axis represents Al.₂O_ThreeThe depth (Å) from the film surface is shown.
[0065]
  As can be seen from FIG. 8, Al in the vicinity of the light emitting end face₂O_ThreeIn the film, the light exit end face / Al₂O_ThreeWithin a range of about 400 mm from the film interface, a high concentration of Ga, which is a group III atom, and As, which is a group V atom, and a group VI atom, S, and a group II atom, Zn are also present. Yes.
[0066]
  Thus, Al in the vicinity of the light emitting end face of the semiconductor laser element.₂O_ThreeS atoms and Zn atoms are present in the film by using an ammonium sulfide solution to remove the surface oxide film formed on the light emitting end face, and the light emitting end face from which the surface oxide film has been removed. As a result of simultaneously performing the step of covering with S atoms, the light emission end face / Al₂O_ThreeThe natural oxide film present at the film interface can be completely removed, and the Al₂O_ThreeAl during film formation₂O_ThreeThe diffusion of Ga and As atoms to the film side becomes active, and accordingly, the light exit end face / Al₂O_ThreeThis is thought to be due to the diffusion of S atoms and Zn atoms present at the film interface.
[0067]
  When the characteristics of the semiconductor laser device were measured, the operating current was 110 mA at an oscillation wavelength of 785 nm and 85 mW, and the maximum optical output of the semiconductor laser device was 300 mW. As can be seen from this result, the maximum output of the semiconductor laser device was improved as compared with the first embodiment.
[0068]
  Further, when a reliability test at 60 ° C. and 85 mW was performed, the semiconductor laser device of this embodiment was about 4000 hours, and the average life was improved compared to the semiconductor laser device of the first embodiment.
[0069]
  As described above, the average lifetime of the semiconductor laser device of the present embodiment is improved as compared with that of the semiconductor laser device of the first embodiment.₂O_ThreeFilm, Al₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeSince a region containing Ga atoms, As atoms, Zn atoms and S atoms is formed in the film, a small number of group III atoms (Ga) and group V diffused from the MQW active layer to the dielectric film side during high output driving. Atomic (As) vacancies are made near Al₂O_ThreeFilm, Al₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeIt is thought that this is because the group II atoms (Zn) and group VI atoms (S) existing in the film are complemented to suppress the generation of point defects.
[0070]
  From the above, Al in the vicinity of the light emitting end face₂O_ThreeFilm, Al₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeSince the region containing Ga atoms, As atoms, Zn atoms and S atoms is formed in the film, it can be seen that the long-term reliability at high output drive can be improved.
[0071]
  Further, as shown in FIG. 8, the light exit end face / Al₂O_ThreeSince no peak of oxygen atoms exists at the film interface, it is clear that the ammonium sulfide solution has an action of removing the surface oxide film formed on the light emitting end face. Therefore, by using the ammonium sulfide solution, the step of removing the surface oxide film formed on the light emitting end face in the MQW active layer region and the step of covering the light emitting end face from which the surface oxide film has been removed with S atoms are simultaneously performed. It is understood that productivity can be improved by reducing the number of work processes.
[0072]
  In the second embodiment, Al is used to form the dielectric film.₂O_ThreeHowever, the same effect can be obtained by using at least one of AlxOy, SixOy, AlxNy, SixNy (where x and y are 1 or more).
[0073]
  In the second embodiment, the semiconductor laser element including AlGaAs is used. However, the same effect can be obtained by using a semiconductor laser element including at least one of AlGaInP, InGaAs, InGaAsP, and the like.
[0074]
  In the second embodiment, Al in the vicinity of the light emitting end face is used.₂O_ThreeFilm, Al₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeAlthough zinc (Zn) atoms are used as group II atoms contained in the film, the same effect can be obtained by using either one of beryllium or magnesium.
[0075]
  In the second embodiment, the zinc acetate solution is used in the step of coating the light emitting end face from which the surface oxide film has been removed with a group II atom. For example, zinc chloride, beryllium chloride, magnesium chloride, zinc sulfate, The same effect can be obtained by using any one of beryllium sulfate and magnesium sulfate.
[0076]
  (Third embodiment)
  In the third embodiment of the present invention, Al is a dielectric film.₂O_ThreeFilm and Al₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeIn the step of forming the film on the light emitting end face, the temperature of the light emitting end face for forming an optimum dielectric film is examined.
[0077]
  The semiconductor laser device of the third embodiment is manufactured as follows.
[0078]
  The wafer (substrate) on which a plurality of the semiconductor laser structures described in the first embodiment are formed is opened in a bar shape in a direction perpendicular to the direction in which the ridge stripe extends so that the resonator length becomes 800 μm. Divide into A plurality of bars formed by the bar division are immersed in an ammonium sulfide solution for 60 seconds, washed with pure water, then immersed in a zinc acetate solution for 30 seconds, washed with pure water, and dried.
[0079]
  Thereafter, the plurality of bars are aligned and placed in an electron beam vapor deposition machine so that the bar end surface temperature, that is, the temperature of the light emitting end surface is 100 ° C., 150 ° C., 200 ° C., 250 ° C., 300 ° C., and 350 ° C., respectively. After heating, Al on the light emitting end face on the front side₂O₂A film is formed and Al is formed on the light emitting end face on the rear side.₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeA film is formed and the bar is divided into chips. As a result, six types of semiconductor laser devices manufactured by heating so that the temperatures of the light emitting end faces are 100 ° C., 150 ° C., 200 ° C., 250 ° C., 300 ° C., and 350 ° C. can be obtained.
[0080]
  As a result of measuring the characteristics of the semiconductor laser device obtained by the above manufacturing method, the oscillation wavelength of the semiconductor laser device is all 785 nm, and the maximum optical output of the semiconductor laser device is 270 mW to 300 mW. There is almost no difference from the embodiment.
[0081]
  Moreover, the result of having performed the reliability test of 60 degreeC85mW is shown in FIG. In FIG. 9, the vertical axis represents the average life (h), and the horizontal axis represents the bar end surface temperature (° C.).
[0082]
  As can be seen from FIG. 9, when the bar end surface temperature is in the range of 150 ° C. to 300 ° C., the average life is 3,000 hours or more, whereas when the temperature is less than 150 ° C. or exceeds 300 ° C., the semiconductor rapidly The average life of the laser element has deteriorated. The reason for this is that after the heat treatment at which the bar end surface temperature is less than 150 ° C., the Al₂O_ThreeWhen the film is formed, the Al adhering to the light emitting end face covered with the II group Zn and the group VI atom S is not completely evaporated.₂O_ThreeBecause the film is formed, the light exit end face / Al₂O_ThreeAn oxide film is formed at the film interface. As a result, the growth of the oxide film occurs at the time of high output driving, and the Ga atom of the group III atom and the As atom of the group V atom diffuse to the oxide film side with the growth of the oxide film. As a result, the point defects are concentrated on the light emitting end face of the active layer region. On the other hand, after the heat treatment at which the bar end surface temperature exceeds 300 ° C., Al₂O_ThreeWhen the film is formed, Zn of group II atoms and S of group VI atoms added to the light emitting end face, and Ga of group III atoms and As of group III atoms in the vicinity of the light emitting end face evaporate to emit light. Al while forming many point defects on the end face₂O_ThreeThe film is formed.
[0083]
  Therefore, in the present embodiment, when the bar end face temperature is less than 150 ° C. or exceeds 300 ° C., the average lifetime of the semiconductor laser element suddenly deteriorates as described above. This is thought to be due to the existence of point defects.
[0084]
  In addition, there is almost no difference in the maximum light output test, but there is a difference in the reliability test. Before the high output drive, the amount of non-radiative recombination centers in the light emitting end face of the active layer region is almost the same. However, the decrease rate of the maximum light output is also different because the increase rate of the non-radiative recombination centers at the time of high output driving is different.
[0085]
  As described above, in the step of forming the dielectric film on the light emitting end face of the active layer region, heating is performed so that the light emitting end face temperature of the active layer region is 150 ° C. or more and 300 ° C. or less, thereby achieving high output drive. It can be seen that it is possible to stably produce a semiconductor laser device having high long-term reliability.
[0086]
  In the third embodiment, Al is used to form the dielectric film.₂O_ThreeHowever, the same effect can be obtained by using at least one of AlxOy, SixOy, AlxNy, SixNy (where x and y are 1 or more).
[0087]
  In the third embodiment, the semiconductor laser element including AlGaAs is used. However, the same effect can be obtained by using a semiconductor laser element including at least one of AlGaInP, InGaAs, InGaAsP, and the like.
[0088]
  In the third embodiment, Al in the vicinity of the light emitting end face is used.₂O_ThreeFilm, Al₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeAlthough zinc (Zn) atoms are used as group II atoms contained in the film, the same effect can be obtained by using either one of beryllium or magnesium.
[0089]
  In the third embodiment, the zinc acetate solution is used in the step of covering the light emitting end face from which the surface oxide film has been removed with a group II atom. For example, zinc chloride, beryllium chloride, magnesium chloride, zinc sulfate, The same effect can be obtained by using any one of beryllium sulfate and magnesium sulfate.
[0090]
  (Fourth embodiment)
  FIG. 10A is a cross-sectional view of the semiconductor laser device according to the fourth embodiment of the present invention viewed from the light emitting end face side, and FIG. 10B is a cross-sectional view viewed from line BB in FIG. FIG.
[0091]
  A method for manufacturing the semiconductor laser device shown in FIGS. 10A and 10B will be described below.
[0092]
  First, in the first crystal growth by metal organic vapor phase epitaxy, an n-type GaAs buffer layer 202 and a first-conductivity-type first cladding layer are formed on an n-type GaAs substrate 201 as a first-conductivity-type substrate. n-type AlGaAs first clad layer 203, n-type AlGaAs second clad layer 204, light guide layer 205, multiple quantum well (MQW) active layer 206 as an active layer, light guide layer 207, second conductivity type second clad A p-type AlGaAs first cladding layer 208 as a layer, a p-type GaAs etching stop layer 209, a p-type AlGaAs second cladding layer 210 as a second conductivity type third cladding layer, and a p-type GaAs protective layer 211 are sequentially stacked. .
[0093]
  Thereafter, a stripe-shaped mask having a desired width is formed on the p-type GaAs protective layer 211, and the p-type GaAs protective layer 211 and p in a region not covered with the mask by a mixed solution of sulfuric acid and hydrogen peroxide. A part of the type AlGaAs second cladding layer 210 is etched. Subsequently, the p-type AlGaAs second clad layer 210 remaining in the region not covered with the mask is etched until hydrofluoric acid exposes the p-type GaAs etching stop layer 209, thereby p-type GaAs. A ridge stripe 250 of a current path composed of the protective layer 211 and the p-type AlGaAs second cladding layer 210 is formed.
[0094]
  Then, after the ridge stripe 250 is formed, the mask formed on the ridge stripe 250 is removed, and an n-type AlGaAs current serving as a first conductivity type current confinement layer is formed by second crystal growth by metal organic vapor phase epitaxy. A block layer 212, an n-type GaAs current blocking layer 213 as a first conductivity type current confinement layer, and a p-type GaAs planarization layer 214 are sequentially stacked.
[0095]
  Thereafter, in order to produce a current non-injection region near the light emitting end face, a mask is formed on the outer region of the ridge stripe 250 and on the surface of the p-type GaAs planarization layer 214 on the ridge stripe 250 and in the vicinity of the light emitting end face. The n-type GaAs current blocking layer 213 and the p-type GaAs planarization layer 214 formed on the ridge stripe 250 excluding the vicinity of the light emission end face are etched away with a mixed solution of ammonia water and hydrogen peroxide water, and sulfuric acid and The n-type AlGaAs current blocking layer 212 formed on the ridge stripe 250 excluding the vicinity of the light emitting end face is etched away by a mixed solution with hydrogen peroxide. After removing unnecessary layers formed on the ridge stripe 250 excluding the vicinity of the light emitting end face, the outer region of the ridge stripe 250, the surface of the p-type GaAs planarization layer 214 on the ridge stripe 250, and the vicinity of the light emitting end face When the mask formed in (2) is removed, a current non-injection region 251 composed of the n-type AlGaAs current blocking layer 212 and the n-type GaAs current blocking layer 213 on the ridge stripe 250 is formed.
[0096]
  Then, by third crystal growth by metal organic vapor phase epitaxy, a p-type GaAs contact layer 215 is formed, a p-side metal electrode 216 is deposited on the surface of the p-type GaAs contact layer 215, and an n-type GaAs substrate 201 is formed. An n-side metal electrode 217 is vapor-deposited on the surface.
[0097]
  A wafer (substrate) on which a plurality of such semiconductor laser structures are formed is opened in a direction perpendicular to the direction in which the ridge stripe 250 extends so as to have a resonator length of 800 μm, and is divided into bars.
[0098]
  The plurality of bars formed by the above bar division are immersed in an ammonium sulfide solution for 60 seconds, and then washed with pure water. Next, it is immersed in a zinc acetate solution for 30 seconds, washed with pure water, and then dried.
[0099]
  Then, after aligning the plurality of bars into an electron beam vapor deposition machine and heating the bar end face temperature, that is, the temperature of the light emitting end face to, for example, 250 ° C., Al is placed on the light emitting end face on the front side.₂O_ThreeThe film 218 is made of Al on the light emitting end face on the rear side.₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeWhen the film 219 is formed and the bar is divided into chips, the semiconductor laser device shown in FIGS. 10A and 10B is obtained.
[0100]
  As a result of measuring the characteristics of the semiconductor laser device obtained by the above manufacturing method, the oscillation wavelength of the semiconductor laser device is 785 nm, and the operating current at 85 mW is 105 mA. Further, when a reliability test at 60 ° C. and 85 mW was performed, the average life was improved to about 5000 hours.
[0101]
  The average lifetime was improved by having the current non-injection region 251 in the vicinity of the light emitting end face.₂O_ThreeA semiconductor laser at 60 ° C. and 85 mW is obtained by eliminating the surface leakage current flowing along the light emitting end face generated by the presence of the group II atom (Zn) and the group VI atom (S) in the film 218 and reducing the operating current. This is considered to be because the heat generation of the element could be suppressed.
[0102]
  From the above, it can be seen that the long-term reliability in high output driving can be improved by having the current non-injection region 251 formed in the vicinity of the light emitting end face.
[0103]
  In the fourth embodiment, Al is used to form the dielectric film.₂O_ThreeHowever, the same effect can be obtained by using at least one of AlxOy, SixOy, AlxNy, SixNy (where x and y are 1 or more).
[0104]
  In the fourth embodiment, the semiconductor laser element including AlGaAs is used. However, the same effect can be obtained by using a semiconductor laser element including at least one of AlGaInP, InGaAs, InGaAsP, and the like.
[0105]
  In the fourth embodiment, Al in the vicinity of the light emitting end face is used.₂O_ThreeFilm, Al₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeAlthough zinc (Zn) atoms are used as group II atoms contained in the film, the same effect can be obtained by using either one of beryllium or magnesium.
[0106]
  In the fourth embodiment, the zinc acetate solution is used in the step of coating the light emitting end face from which the surface oxide film has been removed with a group II atom. For example, zinc chloride, beryllium chloride, magnesium chloride, zinc sulfate, The same effect can be obtained by using any one of beryllium sulfate and magnesium sulfate.
[0107]
  In the fourth embodiment, the current non-injection region 251 is formed in the vicinity of the light emission end face by using the unnecessary layer formed on the ridge stripe 250. However, Si atoms are implanted in the vicinity of the light emission end face. The same effect can be obtained even if the current non-injection region is formed by the method described above.
[0108]
  (Fifth embodiment)
  In the semiconductor laser device of the fifth embodiment of the present invention, a disordered region is formed in the active layer near the light emitting end face.
[0109]
  The semiconductor laser device of the fifth embodiment is manufactured as follows.
[0110]
  First, in the first crystal growth by metal organic vapor phase epitaxy, an n-type GaAs buffer layer and an n-type as a first conductivity type first cladding layer are formed on an n-type GaAs substrate as a first conductivity type substrate. AlGaAs first clad layer, n-type AlGaAs second clad layer, light guide layer, multiple quantum well (MQW) active layer as active layer, light guide layer, p-type AlGaAs second clad layer as second conductivity type second clad layer One cladding layer, a p-type GaAs etching stop layer, a p-type AlGaAs second cladding layer as a second conductivity type third cladding layer, and a p-type GaAs protective layer are sequentially stacked.
[0111]
  Next, stripe-like SiO near the light emitting end face of the semiconductor laser element and on the surface of the p-type GaAs protective layer.₂A film is formed. Then, by performing a rapid temperature rise to 900 ° C., the SiO 2₂Ga vacancies are formed in the p-type GaAs protective layer under the film. Thereafter, holding at 900 ° C. for 1 minute, Ga vacancies are diffused to the multiple quantum well (MQW) active layer. As a result, the vicinity of the light emitting end face of the multiple quantum well (MQW) active layer is disordered to form a disordered region. The band gap of the disordered region formed in the vicinity of the light emitting end face of the multiple quantum well (MQW) active layer is larger than the band gap at the center of the multiple quantum well (MQW) active layer.
[0112]
  Thereafter, SiO formed on the surface of the p-type GaAs protective layer.₂The film is removed to form a stripe-shaped mask having a desired width. Then, the p-type GaAs protective layer and a part of the p-type AlGaAs second cladding layer in a region not covered with the mask are etched with a mixed solution of sulfuric acid and hydrogen peroxide.
[0113]
  Subsequently, in order to remove the remaining p-type AlGaAs second cladding layer in the region not covered with the mask, etching is performed until the p-type GaAs etching stop layer is exposed with hydrofluoric acid. A ridge stripe of a current path composed of a second AlGaAs second cladding layer and a p-type GaAs protective layer is formed.
[0114]
  After the ridge stripe is formed, the mask formed on the ridge stripe is removed. Then, in the second crystal growth by metal organic vapor phase epitaxy, an n-type AlGaAs current block layer as a first conductivity type current confinement layer, an n-type GaAs current block layer as a first conductivity type current confinement layer, A p-type GaAs planarization layer is sequentially stacked.
[0115]
  Thereafter, in order to remove the unnecessary layer formed on the ridge stripe, a mask is formed in the outer region of the ridge stripe, and the n solution formed on the ridge stripe by a mixed solution of ammonia water and hydrogen peroxide solution. The p-type GaAs current blocking layer and the p-type GaAs planarization layer are removed by etching. Further, the n-type AlGaAs current blocking layer formed on the ridge stripe is removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide. After removing the unnecessary layer formed on the ridge stripe, the mask formed in the external region of the ridge stripe is removed.
[0116]
  A p-type GaAs contact layer is formed on the p-type GaAs protective layer and the p-type GaAs planarization layer, which are the outermost surfaces after removing the unnecessary layer, by third crystal growth by metal organic chemical vapor deposition. Thereafter, a p-side metal electrode is deposited on the p-type GaAs contact layer, and an n-side metal electrode is deposited on the n-type GaAs substrate.
[0117]
  A wafer (substrate) on which a plurality of such semiconductor laser structures are formed is opened in the direction perpendicular to the ridge stripe and divided into bars so that the resonator length is 800 μm.
[0118]
  Then, the plurality of bars formed by dividing the bars are immersed in an ammonium sulfide solution for 60 seconds, and then washed with pure water to remove the surface oxide film formed on the light emitting end face. .
[0119]
  Next, after the plurality of bars from which the surface oxide film has been removed are immersed in a zinc acetate solution for 30 seconds and washed with pure water, the plurality of bars are dried.
[0120]
  After that, the plurality of bars are aligned and put into an electron beam vapor deposition machine, heated after the bar end surface temperature, that is, the light output end surface becomes, for example, 250 ° C., and then the light output end surface on the front side is made of Al.₂O_ThreeA film is formed and Al is formed on the light emitting end face on the rear side.₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeA film is formed. And the said bar | burr was divided | segmented into the chip | tip and the semiconductor laser element was produced.
[0121]
  As a result of measuring the characteristics of the semiconductor laser device obtained by the above manufacturing method, the oscillation wavelength of the semiconductor laser device was 785 nm. Further, when a reliability test at 60 ° C. and 85 mW was performed, it was found that the average life was improved to about 5000 hours.
[0122]
  From the above, it can be seen that long-term reliability at high output drive can be improved by forming a disordered region in the region of the MQW active layer near the light emitting end face.
[0123]
  In the fifth embodiment, Al is used to form the dielectric film.₂O_ThreeHowever, the same effect can be obtained by using at least one of AlxOy, SixOy, AlxNy, SixNy (x and y are 1 or more).
[0124]
  In the fifth embodiment, the semiconductor laser element including AlGaAs is used. However, the same effect can be obtained by using a semiconductor laser element including at least one of AlGaInP, InGaAs, InGaAsP, and the like.
[0125]
  In the fifth embodiment, Al in the vicinity of the light emitting end face is used.₂O_ThreeFilm, Al₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_ThreeAlthough zinc (Zn) atoms are used as group II atoms contained in the film, the same effect can be obtained by using either one of beryllium or magnesium.
[0126]
  In the fifth embodiment, the zinc acetate solution is used in the step of coating the light emitting end face from which the surface oxide film has been removed with a group II atom. For example, zinc chloride, beryllium chloride, magnesium chloride, zinc sulfate, The same effect can be obtained by using any one of beryllium sulfate and magnesium sulfate.
[0127]
  In the fifth embodiment, the disordered region formed in the active layer region in the vicinity of the light emitting end face is formed by a method by diffusion of Ga vacancies, but is formed by a method by diffusion of impurities such as Zn atoms. The same effect can be obtained.
[0128]
  In the fifth embodiment, only the disordered region is formed in the active layer region near the light emitting end surface. However, the disordered region is formed in the active layer region near the light emitting end surface, and the vicinity of the light emitting end surface. In addition, the same effect can be obtained by forming a current non-injection region on the ridge stripe.
[0129]
【The invention's effect】
  As apparent from the above, the semiconductor laser device of the present invention has a dielectric film as a light emitting end face protective film for protecting the active layer region formed on the light emitting end face, and in the dielectric film near the light emitting end face. In addition, since a region including group III atoms and group V atoms is formed, the occurrence of point defects in the light emitting end surface of the active layer region during high output driving is suppressed, and the active layer region near the light emitting end surface absorbs. The critical light output of the COD is high, and the decrease in the critical light output of the COD during high output driving can be suppressed. Therefore, long-term reliability with high output drive can be improved.
[0130]
  Further, a dielectric film as a light emitting end face protective film for protecting the region of the active layer is formed on the light emitting end face, and in the dielectric film near the light emitting end face, a group II atom, a group III atom, and a group V By forming a region containing atoms and group VI atoms, even if group III atoms and group V atoms diffuse from the active layer to the dielectric film side, vacancies such as group III atoms and group V atoms, Since group II atoms and group VI atoms existing in the dielectric film near the light emitting end face complement each other, it becomes possible to more effectively suppress the occurrence of point defects. As a result, the active layer region in the vicinity of the light emitting end face is less likely to be an absorption region with respect to the wavelength of the laser light produced by the high injected carrier density in the central portion of the active layer, and the critical light output of COD can be further increased. it can. That is, it is possible to further suppress the decrease in the critical light output of the COD during high output driving.
[0131]
  Also,the aboveSince the group II atom is any one of zinc, beryllium, and magnesium, it is possible to more effectively suppress the increase in non-radiative recombination centers, thus improving the long-term reliability at high power drive. Can be improved.
[0132]
  In the semiconductor laser device according to an embodiment of the present invention, since the group VI atom is sulfur, an increase in non-radiative recombination centers can be more effectively suppressed. The sex can be further improved.
[0133]
  Since the semiconductor laser device according to an embodiment of the present invention has a current non-injection region formed in the vicinity of the light emission end face, carrier loss due to a non-radiative recombination center that is very small in the active layer area in the vicinity of the light emission end face. Is suppressed, the surface leakage current generated by the group II atom and the group VI atom existing on the light emitting end face is suppressed, the operating current can be reduced, and the long-term reliability in high output driving can be improved.
[0134]
  In the semiconductor laser device of one embodiment of the present invention, since the band gap of the disordered region formed in the active layer region near the light emitting end surface is larger than the band gap in the central portion of the active layer, Laser absorption by group II atoms and group VI atoms present in the layer region is reduced, and long-term reliability at high output drive can be further improved.
[0135]
  In the method of manufacturing a semiconductor laser device of the present invention, the surface oxide film formed on the light emitting end face is removed, and the light emitting end face from which the surface oxide film has been removed is covered with a group II atom and a group VI atom. As a result, dangling bonds on the light emitting end face are reduced, so that the effect of reducing the surface level of the light emitting end face and suppressing the adhesion of oxygen atoms to the light emitting end face is obtained, and the dielectric film is formed on the light emitting end face. In the meantime, the effects of group VI atom detachment, evaporation suppression, and re-formation of the oxide film on the light emitting end face are obtained. That is, it is possible to reduce non-radiative recombination centers called surface states or interface states as much as possible, and to suppress proliferation of non-radiative recombination centers during high output driving. As a result, the active layer region in the vicinity of the light emitting end face is less likely to be an absorption region with respect to the wavelength of the laser beam produced by the high injected carrier density in the central portion of the active layer, and is superior in long-term reliability at high output operation. A semiconductor laser device can be manufactured.
[0136]
  According to one embodiment of the present invention, there is provided a method of manufacturing a semiconductor laser device, wherein the surface oxide film formed on the light emitting end face is removed, and the light emitting end face from which the surface oxide film has been removed is made of a group II atom and a group VI atom. After coating, a dielectric film as a light emitting end face protective film for protecting the active layer is formed on the light emitting end face, and the group III atom and the V group atom are diffused in the dielectric film, thereby A region containing Group II, Group III, Group V, and Group VI atoms is formed in the dielectric film in the vicinity of the emitting end face, so that a semiconductor laser device that is superior in long-term reliability at high output operation can be obtained. Can be manufactured.
[0137]
  According to the method for manufacturing a semiconductor laser device of an embodiment of the present invention, the light emission from which the surface oxide film is removed by performing the heat treatment so that the temperature of the light emission end face is 150 ° C. or more and 300 ° C. or less. Moisture adhering to the light exit end face after the end face is coated with a group II atom and a group VI atom can be evaporated, and a group III atom, group V atom, group II atom, group VI atom in the vicinity of the light exit end face Re-evaporation can be suppressed. Therefore, point defects on the light emitting end face in the active layer region do not multiply, and a semiconductor laser device having excellent long-term reliability in high output driving can be stably obtained.
[0138]
  In the method of manufacturing a semiconductor laser device according to an embodiment of the present invention, in the step of removing the surface oxide film formed on the light emitting end face of the active layer region, the surface oxide film is removed with an ammonia sulfide solution. The process of removing the surface oxide film formed on the light emitting end face of the region and the process of covering the light emitting end face from which the surface oxide film has been removed can be performed simultaneously, reducing productivity and reducing productivity. Can be improved.
[Brief description of the drawings]
FIG. 1A is a cross-sectional view of a semiconductor laser device according to a first embodiment of the present invention as viewed from a light emitting end surface side, and FIG. 1B is a view of the semiconductor laser device as viewed from a side surface side. It is sectional drawing.
FIG. 2 is a drawing for explaining the method for manufacturing the semiconductor laser element of the first embodiment.
FIG. 3 is a drawing for explaining the method for manufacturing the semiconductor laser element of the first embodiment.
FIG. 4 is a drawing for explaining the method for manufacturing the semiconductor laser element of the first embodiment.
FIG. 5 is a drawing for explaining the method for manufacturing the semiconductor laser element of the first embodiment.
FIG. 6 is a view showing a depth direction distribution of impurity atoms of the semiconductor laser device of the first embodiment.
FIG. 7 is a diagram showing a depth direction distribution of impurity atoms of a conventional semiconductor laser device.
FIG. 8 is a diagram showing a depth direction distribution of impurity atoms of a semiconductor laser device according to a second embodiment of the present invention.
FIG. 9 is a graph showing the relationship between bar end face temperature and average life in a semiconductor laser device according to a third embodiment of the present invention.
10A is a cross-sectional view of a semiconductor laser device according to a fourth embodiment of the present invention as viewed from the light emitting end face side, and FIG. 10B is a BB line in FIG. 10A. It is sectional drawing seen from.
FIG. 11A is a cross-sectional view of a conventional semiconductor laser device as seen from the light emitting end face side, and FIG. 11B is a cross-sectional view of the conventional semiconductor laser device as seen from a side surface side. .
[Explanation of symbols]
1,101,201 n-type GaAs substrate
2,102,202 n-type GaAs buffer layer
3,203,103 n-type AlGaAs first cladding layer
4,104,204 n-type AlGaAs second cladding layer
5, 7, 105, 107, 205, 207 Light guide layer
6,106,206 Multiple quantum well (MQW) active layer
8,108,208 p-type AlGaAs first cladding layer
9,109,209 p-type GaAs etching stop layer
10,110,210 p-type AlGaAs second cladding layer
11, 111, 211 p-type GaAs protective layer
12,112,212 n-type AlGaAs current blocking layer
13,113,213 n-type GaAs current blocking layer
14,114,214 p-type GaAs planarization layer
15,115,215 p-type GaAs contact layer
16,116,216 p-side metal electrode
17,117,217 n-side metal electrode
18,218 Al with regions containing group III, group V atoms₂O_Threefilm
19,219 Al with regions containing III and V atoms₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_Threefilm
118 Al₂O_Threefilm
119 Al₂O_Three/ Si / Al₂O_Three/ Si / Al₂O_Threefilm
50,150,250 Ridge stripe
251 Current non-injection region

Claims (8)

On the substrate of the first conductivity type, a first cladding layer of the first conductivity type, an active layer, a second cladding layer of the second conductivity type, and a ridge stripe which is a second cladding layer of the second conductivity type. A first conductive type current confinement layer is formed so as to sandwich the ridge stripe from both side surfaces, and a dielectric film is formed on the light emitting end face as a light emitting end face protective film for protecting the active layer region. In the manufactured semiconductor laser device,
During the dielectric film in the vicinity of the light-emitting end face, we have a region that contains the group III atoms and group V atoms,
The region includes group II and group VI atoms,
The semiconductor laser device above group II atoms to zinc, beryllium, wherein any one Tsudea Rukoto of magnesium. The semiconductor laser device according to claim 1,
A semiconductor laser device, wherein the group VI atom is sulfur. The semiconductor laser device according to claim 1 or 2 ,
A semiconductor laser device having a current non-injection region formed in the vicinity of the light emitting end face. In the semiconductor laser device according to any one of claims 1 to 3 ,
A semiconductor laser device, wherein a disordered region is formed in a region of the active layer in the vicinity of the light emitting end face, and a band gap of the disordered region is larger than a band gap of a central portion of the active layer. A first conductivity type first clad layer, an active layer, a second conductivity type second clad layer, and a second conductivity type third clad layer are laminated on the first conductivity type substrate and wet. In the method of manufacturing a semiconductor laser device, the second conductivity type third cladding layer is formed into a ridge stripe by etching, and the first conductivity type current confinement layer is formed so as to sandwich the ridge stripe from both sides.
Removing the surface oxide film formed on the light emitting end face;
And a step of coating the light emitting end face from which the surface oxide film has been removed with a group II atom and a group VI atom. A first conductivity type first clad layer, an active layer, a second conductivity type second clad layer, and a second conductivity type third clad layer are laminated on the first conductivity type substrate and wet. In the method of manufacturing a semiconductor laser device, the second conductivity type third cladding layer is formed into a ridge stripe by etching, and the first conductivity type current confinement layer is formed so as to sandwich the ridge stripe from both sides.
Removing the surface oxide film formed on the light emitting end face;
Coating the light emitting end face from which the surface oxide film has been removed with a group II atom and a group VI atom;
Forming a dielectric film as a light emitting end face protective film for protecting the region of the active layer on the light emitting end face;
And a step of diffusing group III atoms and group V atoms in the dielectric film. In the manufacturing method of the semiconductor laser device according to claim 6 ,
A method of manufacturing a semiconductor laser device, comprising: performing a heat treatment so that the temperature of the light emitting end face is 150 ° C. or higher and 300 ° C. or lower, and then forming the dielectric film. In the manufacturing method of the semiconductor laser device according to claim 5 or 6 ,
A method of manufacturing a semiconductor laser device, comprising removing a surface oxide film formed on the light emitting end face with an ammonia sulfide solution.

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