JP2010050199A - Semiconductor laser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser capable of improving a COD value without causing a failure caused by diffusing impurities to an end face and the vicinity. <P>SOLUTION: On at least one of a pair of end parts of a substrate 10 facing each other in the extending direction of a ridge part 30, a notch 40 is provided. In the inside of the notch 40, a stress generation part 50 is formed, which is mainly formed of a material having a thermal expansion coefficient larger than the thermal expansion coefficient of an active layer 12 and the substrate 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor laser particularly suitable for high-power applications.

  It is known that when a semiconductor laser is operated at a high output, end face destruction (Catastrophic Optical Damage: COD) is likely to occur due to a temperature rise accompanying recombination at the end face or increased light absorption. In recent years, this COD has become a problem not only in a narrow stripe type semiconductor laser having a waveguide width, that is, a stripe width of about several μm, but also in a broad area type semiconductor laser having a stripe width of 10 μm or more.

  Various methods have been developed for COD countermeasures. For example, in a semiconductor laser having an As-based active layer having an oscillation wavelength in the near-infrared region or a P-based active layer having an oscillation wavelength in the red band, impurities such as Zn are present on the end face (cleaved face) and its vicinity. A diffusion method is generally used (for example, Patent Document 1). In this way, by diffusing impurities in the end face and in the vicinity thereof, the group III atoms are mainly replaced with the impurities to perform the ordering of the active layer, and the band gap of the active layer where the impurities are diffused is activated. The band gap of the region where the impurity is not diffused (gain region) in the layer is made larger, and the laser beam generated in the gain region of the active layer is absorbed at the end face and in the vicinity thereof, and the rate of conversion into heat is reduced. ing.

Japanese Patent Laid-Open No. 7-162086

  By the way, in general, in a region where an impurity such as Zn is diffused, the interband absorption of the laser beam can be suppressed by expanding the band gap. On the other hand, the absorption due to the impurity order increases. Here, since the increase amount due to the temperature rise of the absorption due to the impurity order is sufficiently smaller than that of the interband absorption, it is effective in terms of improving the COD value to diffuse the impurity in the end face and the vicinity thereof. However, when the semiconductor laser is driven below the COD threshold, the absorption loss is merely increased.

  In order to form the window region, it is necessary to diffuse an impurity such as Zn into the light emitting region of the active layer. However, in such a case, the crystallinity in the light emitting region is lowered. In order to diffuse impurities such as Zn into the light emitting region of the active layer, it is necessary to anneal at a high temperature. However, in such a case, the doping profile formed by epitaxial growth is lost.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a semiconductor laser capable of improving the COD value without causing problems caused by impurity diffusion on the end face and in the vicinity thereof. There is to do.

  A semiconductor laser according to the present invention includes a semiconductor substrate, a semiconductor layer formed on one surface of the semiconductor substrate, and a stress generating portion formed on a surface of the semiconductor substrate opposite to the semiconductor layer. Is. The semiconductor layer has an active layer and a band-shaped current confinement structure for confining a current injected into the active layer in order from the semiconductor substrate side, and further, a current confinement structure with the active layer and the current confinement structure in between. Has a pair of end faces opposed to each other in the extending direction. The semiconductor substrate has a notch immediately below and in the vicinity of at least one of the pair of end surfaces in the semiconductor layer. The stress generating part is mainly formed of a material having a thermal expansion coefficient larger than that of the active layer and the semiconductor substrate, and is formed at least inside the notch.

  In the semiconductor laser of the present invention, the thermal expansion coefficient larger than the thermal expansion coefficient of the active layer and the semiconductor substrate is formed in the notch provided in at least one of the pair of ends facing the resonator direction of the semiconductor substrate. The stress generation part mainly formed with the material which has is formed. Thus, in the manufacturing process, a stress generating portion is formed at least inside the notch at a high temperature and then cooled, thereby applying a compressive stress from the stress generating portion outside the semiconductor layer to the end of the active layer. be able to. Since the temperature at the time of driving the semiconductor laser is extremely lower than the temperature at the time of forming the stress generating part, the stress generating part, which is outside the semiconductor layer, is also applied to the end of the active layer even during driving of the semiconductor laser. Compressive stress can be applied. The temperature at which the stress generating portion is formed is sufficiently lower than the temperature at which impurities such as Zn are diffused to the light emitting region of the active layer in order to form the window region.

  According to the semiconductor laser of the present invention, the thermal expansion coefficient is larger than the thermal expansion coefficient of the active layer and the semiconductor substrate in the notch provided in at least one of the pair of end portions facing in the resonator direction. Since the stress generating portion mainly formed of the material is formed, a compressive stress can be applied to the end portion of the active layer from the stress generating portion which is outside the semiconductor layer. As a result, the band gap at the end of the active layer can be widened without causing an increase in absorption loss, a decrease in crystallinity, or a decrease in doping profile. Therefore, the COD value can be improved without causing a problem caused by impurity diffusion in the end face and the vicinity thereof.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing a schematic configuration of a semiconductor laser 1 according to an embodiment of the present invention. FIG. 2 illustrates a cross-sectional configuration of the semiconductor laser 1 in FIG. The semiconductor laser 1 of the present embodiment has a structure in which a striped ridge portion 30 is sandwiched between a pair of front end surface 20A and rear end surface 20B from the extending direction of the ridge portion 30, as will be described in detail later. This is a so-called edge emitting semiconductor laser.

  The ridge portion 30 corresponds to a specific example of the “current confinement structure” of the present invention, and the pair of front end surfaces 20A and the rear end surface 20B corresponds to a specific example of the “pair of end surfaces” of the present invention.

  The semiconductor laser 1 includes, for example, a semiconductor layer 20 formed by laminating a lower clad layer 11, an active layer 12, an upper clad layer 13 and a contact layer 14 in this order from the substrate 10 side on a substrate 10. Note that the semiconductor layer 20 may be further provided with a layer (for example, a buffer layer or a guide layer) other than the above-described layers.

  Striped ridge portions 30 are formed on the semiconductor layer 20, specifically, on the upper cladding layer 13 and the contact layer 14. The width W1 of the ridge portion 30 (the width in the direction orthogonal to the extending direction (resonator direction) of the ridge portion 30) is, for example, a value within a range of several μm to several hundred μm. The semiconductor layer 20 is formed with a pair of front end face 20A and rear end face 20B that sandwich the ridge part 30 from the extending direction of the ridge part 30, and the front end face 20A and the rear end face 20B constitute a resonator. . The pair of front end surfaces 20A and rear end surfaces 20B are formed by cleavage, for example, and are arranged to face each other with a predetermined gap. Further, a low reflection film 31 (see FIG. 2) is formed on the front end face 20A, and a high reflection film 32 (see FIG. 2) is formed on the rear end face S2.

  The substrate 10 is made of, for example, n-type GaAs. An example of the n-type impurity is silicon (Si). On the back surface of the substrate 10 (the surface of the substrate 10 opposite to the semiconductor layer 20), a notch 40 is formed immediately below and in the vicinity of at least one of the front end surface 20A and the rear end surface 20B of the semiconductor layer 20. Has been. FIG. 2 illustrates a case where a notch 40 is formed directly below and in the vicinity of both the front end face 20A and the rear end face 20B.

  The notch 40 is formed by etching the substrate 10 from the opposite side of the substrate 10 to the semiconductor layer 20, and has a concave shape when viewed from the back side of the substrate 10.

  Here, the depth D1 of the notch 40 is equal to or less than the thickness D2 of the substrate 10. 1 and 2 exemplify a case where the depth D1 of the notch 40 is shallower than the thickness D2 of the substrate 10. When the depth D1 of the notch 40 is shallower than the thickness D2 of the substrate 10, the substrate 10 is exposed on the bottom surface 40A of the notch 40 as shown in FIGS. On the other hand, when the depth D1 of the notch 40 is equal to the thickness D2 of the substrate 10, the bottom surface 40A of the semiconductor layer 20 is formed on the bottom surface 40A of the notch 40 as shown in FIGS. The (lower clad layer 11) is exposed.

  The width W2 of the notch 40 (the width in the direction orthogonal to the extending direction of the ridge 30) is wider than the width W1 of the ridge 30. 1 and 2 exemplify a case where the width W2 of the notch 40 is wider than the width W2 of the ridge portion 30 and narrower than the width W3 of the substrate 10. FIG. As shown in FIG. 6, the width W2 of the notch 40 may be equal to the width W3 of the substrate 10. At this time, although not shown, the depth D1 of the notch 40 may be equal to the thickness D2 of the substrate 10.

  The depth L of the cutout 40 (the length in the direction parallel to the extending direction of the ridge portion 30) is such a size that a wide band gap region 12B described later functions as a window region. Regardless of the distance, it is 10 μm or more and 50 μm or less.

  Here, the window region is a region having a band gap larger than the energy corresponding to the emission wavelength of the active layer 12, and the laser beam generated in the central region (gain region) of the active layer 12 is the front end face 20A. And the vicinity thereof, or the rear end face 20B and the vicinity thereof have a function of reducing the rate of absorption and conversion into heat.

  The lower cladding layer 11 is made of, for example, n-type AlInP. The upper cladding layer 13 is made of, for example, p-type AlInP. The contact layer 14 is made of, for example, p-type GaAs, and is provided on the uppermost portion (upper surface) of the ridge portion 30. Examples of the p-type impurity include magnesium (Mg) and zinc (Zn).

  The active layer 12 is made of, for example, undoped GaInP. In this active layer 12, a region facing the ridge portion 30 becomes a light emitting region 12A. The light emitting region 12A corresponds to a current injection region into which a current confined by the ridge portion 30 is injected. In the active layer 12, a region facing the notch 40 is the above-described wide band gap region 12B. The wide band gap region 12B is a region having a band gap larger than the band gap of the region other than the wide band gap region 12B in the light emitting region 12A, and is compressed by the stress generating unit 50 as will be described later. It is formed by narrowing the lattice spacing by stress. The wide band gap region 12B functions as a window region.

  The insulating layer 15 (FIG. 1) is formed on the upper surface of the semiconductor layer 20 (the upper surface and both side surfaces of the ridge portion 30 and the surface of the upper cladding layer 13 other than the ridge portion 30) other than the upper surface of the ridge portion 30. Reference) is provided. That is, the insulating layer 15 has an opening in a region facing the upper surface of the ridge portion 30.

  An upper electrode 16 is formed from the upper surface of the ridge portion 30 to the surface of the insulating layer 15. For example, as shown in FIGS. 1 and 2, the upper electrode 16 is formed on the entire surface of the semiconductor layer 20 facing at least the ridge portion 30 on the ridge portion 30 side. For example, as shown in FIGS. 7 and 8, the upper electrode 16 may be formed only in a region slightly retracted from the front end surface 20 </ b> A and the rear end surface 20 </ b> B in a region facing the ridge portion 30. . The upper electrode 16 is formed, for example, by laminating titanium (Ti), platinum (Pt), and gold (Au) in this order from the ridge portion 30 side, and is electrically connected to the upper surface (contact layer 14) of the ridge portion. ing.

  A lower electrode 17 is formed on the back surface of the substrate 10. For example, as shown in FIGS. 1 and 2, the lower electrode 17 includes a bottom surface 40 </ b> A and a side surface 40 </ b> B in the notch 40 from a region other than the notch 40 (a region where the notch 40 is not formed) on the back surface of the substrate 10. It is formed over. For example, as illustrated in FIGS. 9 and 10, the lower electrode 17 may be formed only in a region other than the notch 40 (a region where the notch 40 is not formed) on the back surface of the substrate 10. The lower electrode 17 has a structure in which, for example, an alloy of gold (Au) and germanium (Ge), nickel (Ni), and gold (Au) are stacked in this order from the substrate 10 side. It is connected to the.

  By the way, in the present embodiment, the stress generating portion 50 is formed on the back surface of the substrate 10. The stress generating portion 50 applies compressive stress to at least one of the front end face 20A of the active layer 12 and the vicinity thereof, and the rear end face 20B of the active layer 12 and the vicinity thereof, thereby increasing the band gap of the region. The wide band gap region 12B that functions as a region is formed.

  The stress generating part 50 is formed at least inside the notch 40. For example, as illustrated in FIGS. 1 and 2, the stress generating unit 50 is embedded in the notch 40 and is formed on the entire back surface of the substrate 10. At this time, the part formed in the notch 40 in the stress generating part 50 is closest to the active layer 12. In addition, the stress generation part 50 may be formed only in the notch 40 as shown, for example in FIG. 11, FIG.

  When the notch 40 is formed in the front end face 20A of the semiconductor layer 20, the stress generating part 50 is preferably formed immediately below and in the vicinity of the front end face 20A. In the case where it is formed on the rear end surface 20B, it is preferably formed directly below and in the vicinity of the rear end surface 20B. That is, it is preferable that the stress generating portion 50 has an end face in the same plane as the front end face 20A or the rear end face 20B of the semiconductor layer 20.

  The stress generating part 50 is mainly formed of a material having a thermal expansion coefficient larger than that of the active layer 12 and the substrate 10. For example, when the substrate 10 is made of GaAs (thermal expansion coefficient 6 ppm / K) and the active layer 12 is made of GaInP (thermal expansion coefficient 6 ppm / K), the stress generator 50 has a thermal expansion coefficient of 6 ppm / K. Are mainly formed of a large material (for example, a metal such as copper (thermal expansion coefficient 17 ppm / K) or aluminum (thermal expansion coefficient 23 ppm / K)). It should be noted that a material having a thermal expansion coefficient that is the same as or smaller than that of the active layer 12 and the substrate 10 may be slightly included in the stress generation unit 50.

  Moreover, although it is preferable that the stress generation | occurrence | production part 50 is formed from the material (for example, metal) with good heat dissipation from a heat dissipation viewpoint, it does not need to be formed with the material with good heat dissipation. Further, when the stress generating part 50 is made of metal, it may be formed integrally with the lower electrode 17 (that is, as a part of the lower electrode 17). Further, the thickness of the stress generating portion 50 (particularly the thickness corresponding to the portion immediately below the front end surface 20A or the rear end surface 20B) is set so that the stress generating portion 50 can be cut cleanly in the manufacturing process. It is preferable to be defined according to the viscosity of the material used for the stress generating unit 50.

  With reference to FIGS. 13A to 13C and FIGS. 14A to 14C, an example of a method for manufacturing the semiconductor laser 1 of the present embodiment will be described. FIGS. 13A to 13C and FIGS. 14A to 14C are cross-sectional configurations corresponding to the cross-sectional configuration in the direction of arrows AA in FIG. It is written together with a cross-sectional view when cut in a direction (A-A line in the figure).

In order to manufacture the semiconductor laser 1 using the compound semiconductor exemplified in the above configuration, the semiconductor layer 20 on the substrate 10 is formed by, for example, MOCVD (Metal Organic Chemical Vapor Deposition) method. At this time, for example, trimethylaluminum (TMAl), trimethylgallium (TMGa), trimethylindium (TMIn), phosphine (PH3), and arsine (AsH3) are used as raw materials for the compound semiconductor. Monosilane (SiH ₄ ) is used, and biscyclopentadienyl magnesium (Cp ₂ Mg) or dimethyl zinc (DMZn) is used as the acceptor impurity raw material, for example.

  First, a semiconductor layer 20D including a lower clad layer 11D, an active layer 12D, an upper clad layer 13D, and a contact layer 14D is laminated in this order on a wafer-like substrate 10D (FIG. 13A). In addition, what attached | subjected D to the end of a code | symbol means that it will be what took D from the end of a code | symbol through the subsequent process, for example, the board | substrate 10D is an etching process mentioned later, The substrate 10 is obtained through the cleavage process and the dicing process.

  Next, a mask layer (not shown) is formed on the contact layer 14D, and the upper portion of the upper cladding layer 13D and the contact layer 14D are selectively removed by wet etching, for example. As a result, a striped ridge portion 30D is formed on the upper clad layer 13D and the contact layer 14D (FIG. 13B). Thereafter, the mask layer is removed.

  Next, after forming an insulating layer 15D (not shown) in a portion other than the upper surface of the ridge portion 30D, an upper electrode 16D is formed from the upper surface of the ridge portion 30D to the surface of the insulating layer 15D (FIG. 13C). .

(Etching process of substrate 10D)
Next, the substrate 10D is selectively removed from the back surface, for example, by wet etching. As a result, a recess 40D (which becomes a notch 40 by a cleavage process described later) is formed at a predetermined position of the substrate 10D (FIG. 14A).

  Next, after the lower electrode 17D is formed on the entire back surface of the substrate 10D, for example, by vapor deposition, the stress generating portion 50D is formed on the entire surface of the lower electrode 17D, for example, by plating, and the recess 40D is further formed by the stress generating portion 50D. Embed (FIG. 14B).

  Next, the portion of the stress generating portion 50D that protrudes from the concave portion 40D is thinned by, for example, lapping, and the thickness of the stress generating portion 50D is adjusted (FIG. 14C).

(Cleaving process / Dicing process)
Next, the substrate 10D and the semiconductor layer 20D are cleaved into a bar shape (not shown) across the recess 40D. Thereby, the front end face 20A and the rear end face 20B are formed. Thereafter, the low reflection film 31 is formed on the front end face 20A, and the high reflection film 32 is formed on the rear end face 20B (not shown). Finally, the ridges 30 are diced along the ridges 30 to form the substrate 10D and the semiconductor layer 20D in a chip shape (not shown). In this way, the semiconductor laser 1 of the present embodiment is manufactured.

  Next, the operation and effect of the semiconductor laser 1 of the present embodiment will be described.

  In the semiconductor laser 1 of the present embodiment, when a predetermined voltage is applied between the upper electrode 16 and the upper electrode 17, the current is confined by the ridge portion 30, and the current injection region (light emitting region 12A) of the active layer 12 An electric current is injected into this, and light is emitted by recombination of electrons and holes. This light is reflected by the pair of front end face 20A and rear end face 20B, causes laser oscillation at a predetermined wavelength, and is emitted to the outside as a laser beam.

  By the way, in this Embodiment, the notch 40 is provided in at least one of a pair of edge parts which oppose the resonator direction of the board | substrate 10, The active layer 12 and the board | substrate 10 are provided in the notch 40 inside. The stress generating part 50 mainly formed of a material having a thermal expansion coefficient larger than the thermal expansion coefficient is formed. Thereby, in the manufacturing process, the stress generating part 50 is formed at least inside the notch 40 at a high temperature, and then cooled, thereby applying a compressive stress from the stress generating part 50 to the end of the active layer 12. it can. Since the temperature at the time of driving the semiconductor laser 1 is extremely lower than the temperature at the time of forming the stress generating part 50, the semiconductor laser 1 is activated from the stress generating part 50 outside the semiconductor layer 20 even when the semiconductor laser 1 is driven. A compressive stress can be applied to the end of the layer 12. As a result, the lattice spacing at the end of the active layer 12 is narrowed by the compressive stress applied from the stress generating unit 50, and the end of the active layer 12 has a larger band gap than the energy corresponding to the emission wavelength of the active layer 12. The wide band gap region 12B is formed. As a result, when the semiconductor laser 1 is driven, a window region is formed at the end of the active layer 12, and the laser light generated in the central region (gain region) of the active layer 12 is emitted from the front end face 20A and its vicinity or the rear end face 20B. And the ratio absorbed in the vicinity and converted into heat can be reduced. Therefore, the COD value can be improved.

  In the present embodiment, since the stress generating portion 50 is formed outside the semiconductor layer 20, absorption as in the case where impurities such as Zn are diffused into the semiconductor layer 20 in order to form the window region. There is no risk of increased loss or decreased crystallinity. In addition, since the temperature at which the stress generating portion 50 is formed is sufficiently lower than the temperature at which impurities such as Zn are diffused into the active layer 12, there is no possibility that the doping profile formed by epitaxial growth will be distorted. Therefore, in this embodiment, the COD value can be improved without causing a problem caused by impurity diffusion in the end face and its vicinity.

  In the present embodiment, when the stress generating portion 50 is formed of a material having good heat dissipation (for example, metal), the temperature of the end portion of the active layer 12 is set to a portion other than the end portion of the active layer 12. It can be lower than the temperature. Here, since the band gap is generally reduced when the temperature of the semiconductor is lowered, the band gap at the end portion of the active layer 12 is decreased by the heat radiation from the stress generating portion 50 and the temperature at the end portion of the active layer 12 is lowered. Can be made smaller than the band gap of the portion other than the end portion of the active layer 12. Therefore, when the temperature of the semiconductor laser 1 rises, thermal runaway can be made difficult and the COD value can be improved.

  Further, in the present embodiment, the depth D1 of the notch 40 is made shallower than the thickness D2 of the substrate 10, and the lower electrode 17 is disposed in a region other than the notch 40 on the back surface of the substrate 10 (the notch 40 is not yet formed). When forming from the formation region) to the bottom surface 40A and the side surface 40B in the notch 40, the lower electrode 17 can be brought into ohmic contact with the portion of the substrate 10 exposed to the bottom surface 40A in the notch 40. . As a result, the resistance at the end portions (end surfaces 20A, 20B) of the semiconductor laser 1 can be reduced, so that current can be injected also into the end portions (end surfaces 20A, 20B) of the active layer 12, and the active layer Light absorption at the end of 12 can be almost eliminated. Even when the lower electrode 17 is not in contact with the bottom surface 40A in the notch 40, the band gap is widened at the end of the active layer 12, so that even if the amount of injected current is small, the light absorption is It doesn't happen very much.

  In the present embodiment, when the width W2 of the notch 40 (the width in the direction orthogonal to the extending direction of the ridge portion 30) is narrower than the width W3 of the substrate 10, the stress generating portion 50 The thickness at the lateral end of the semiconductor laser 1 can be reduced. Thereby, the cutting | disconnection of the stress generation | occurrence | production part 50 can be made easy at the time of dicing.

  Although the present invention has been described with reference to the embodiment and its modifications, the present invention is not limited to the above-described embodiment and the like, and various modifications can be made.

  For example, in the above-described embodiment and the like, the semiconductor laser 1 includes only one ridge portion 30; For example, as shown in FIG. 15, it is possible to form the semiconductor laser array 2 by forming a plurality of ridge portions 30 monolithically on the common substrate 10.

  At this time, as shown in FIG. 16, the semiconductor laser array 2 is joined to a submount 60 having high thermal conductivity such as SiC by junction down via solder (not shown). It is preferable to join the heat sink 70 made of solder via solder (not shown). However, when the ridge portion 30 (emitter) is monolithically formed on the common substrate 10 as in the semiconductor laser array 2, thermal interaction is likely to occur between adjacent emitters, so that the emitter spacing is increased to some extent. It is preferable to keep it. FIG. 16 illustrates a case where an electrode member 72 electrically connected to the lower electrode 17 via a wire 71 is provided on the side opposite to the light emission side of the semiconductor laser array 2. . The electrode member 72 is fixed by screws 74 on an insulating plate 73 that is insulated from and separated from the heat sink 70, and a protective member 75 that protects the wire 71 from the outside is fixed on the electrode member 72 by screws 74. Has been.

  Here, under the same driving conditions, the output from each emitter of the semiconductor laser array 2 becomes larger than the output from each emitter of the conventional type laser array in which the window structure is not formed at the end of the active layer. Therefore, when the laser beams from the respective emitters are combined to increase the output, the number of emitters can be reduced as compared with the conventional case. As a result, it is possible to reduce the size of the optical element that is optically coupled to the semiconductor laser array and to reduce the number of optical elements. In addition, the laser light from each emitter is collimated with a lens or the like, and a two-dimensional image is obtained with an optical element (for example, a liquid crystal or an optical MEMS (Micro Electro Mechanical Systems) such as DLP (Digital Light Processing) or GLV (Grating Light Valve)). In a laser display that modulates spatially according to information and irradiates the screen, the luminance of each pixel can be increased.

  When the semiconductor laser array 2 is joined to the submount 60 via solder, the end surface (end surface 20A) on the light emission side of the semiconductor laser array 2 may be inclined toward the submount 60 due to the surface tension of the solder. Many. When the end surface 20A is inclined to the submount 60 side, the end surface 20B side is farther from the submount 60 than the end surface 20A side, and the solder between the end surface 20B and the submount 60 becomes thicker. Tends to be higher than the temperature on the end face 20A side, and COD tends to occur on the end face 20B side. Therefore, in such a case, the notch 40 may be provided in the substrate 10 only on the end face 20B side, and the stress generating portion 50 may be provided inside the notch.

  In the above-described embodiments, the present invention has been described by taking an AlGaInP-based compound semiconductor laser as an example. However, other compound semiconductor lasers, for example, a red semiconductor laser such as a GaInAsP-based semiconductor, a nitride such as a GaInN-based and AlGaInN-based semiconductor The present invention is also applicable to II-VI group semiconductor lasers such as gallium semiconductor lasers and ZnCdMgSSeTe. The present invention is also applicable to semiconductor lasers whose oscillation wavelength is not always in the visible range, such as AlGaAs, InGaAs, InP, and GaInAsNP.

  In the above-described embodiments, the present invention has been described by taking the semiconductor laser having an index guide structure as an example. However, the present invention is not limited to this, and other structures, for example, gain guide structures. The present invention can also be applied to a semiconductor laser.

1 is a perspective view of a semiconductor laser according to an embodiment of the present invention. It is sectional drawing of the AA arrow direction of the semiconductor laser of FIG. It is a perspective view of a semiconductor laser when the depth of a notch is made equal to the thickness of a substrate. It is sectional drawing of the AA arrow direction of the semiconductor laser of FIG. It is a perspective view of a semiconductor laser when the width of a notch is made equal to the width of a substrate. It is sectional drawing of the AA arrow direction of the semiconductor laser of FIG. It is a perspective view of a semiconductor laser when an upper electrode is slightly retracted from a front end face and a rear end face. It is sectional drawing of the AA arrow direction of the semiconductor laser of FIG. It is a perspective view of a semiconductor laser when a lower electrode is formed only in a region other than a notch in a back surface of a substrate. It is sectional drawing of the AA arrow direction of the semiconductor laser of FIG. It is a perspective view of a semiconductor laser when a stress generation part is provided only in a notch. It is sectional drawing of the AA arrow direction of the semiconductor laser of FIG. It is sectional drawing for demonstrating an example of the manufacturing method of the semiconductor laser of FIG. It is sectional drawing for demonstrating the process following FIG. FIG. 2 is a perspective view of a semiconductor laser array formed by arraying the semiconductor lasers of FIG. 1. FIG. 16 is a perspective view of a semiconductor laser device in which the semiconductor laser array of FIG. 15 is mounted on a heat sink.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser, 2 ... Semiconductor laser array, 10 ... Substrate, 11 ... Lower clad layer, 12 ... Active layer, 12A ... Light emission area, 13 ... Upper guide layer, 14 ... Contact layer, 15 ... Insulating layer, 16 ... Upper Electrode, 17 ... lower electrode, 20 ... semiconductor layer, 30 ... ridge, 31 ... low reflection film, 32 ... high reflection film, 40 ..., 50 ..., 60 ... submount, 70 ... heat sink, 71 ... wire, 72 ... Electrode member, 73 ... insulating plate, 74 ... screw, 75 ... protective member.

Claims (12)

A semiconductor substrate;
A semiconductor layer formed on one surface of the semiconductor substrate;
A stress generating part formed on a surface of the semiconductor substrate opposite to the semiconductor layer;
The semiconductor layer has an active layer and a band-shaped current confinement structure for confining a current injected into the active layer in order from the semiconductor substrate side, and the current is interposed between the active layer and the current confinement structure. Having a pair of end faces facing the extending direction of the constriction structure;
The semiconductor substrate has a notch directly below and in the vicinity of at least one of the pair of end surfaces,
The stress generation part is a semiconductor laser mainly formed of a material having a thermal expansion coefficient larger than that of the active layer and the semiconductor substrate, and at least inside the notch.   2. The semiconductor laser according to claim 1, wherein the notch is formed by etching the semiconductor substrate from a side opposite to the semiconductor layer in the semiconductor substrate.   The semiconductor laser according to claim 2, wherein the stress generating portion is formed so as to fill at least the notch.   3. The semiconductor laser according to claim 2, wherein the stress generating portion is formed on the entire surface of the semiconductor substrate opposite to the semiconductor layer while filling the notch. A lower electrode on the surface of the semiconductor substrate opposite to the semiconductor layer;
The semiconductor laser according to claim 2, wherein the lower electrode is formed from a surface other than the notch to a side surface and a bottom surface in the notch.   6. The semiconductor laser according to claim 5, wherein the stress generating part and the lower electrode are made of metal and are integrally formed with each other.   2. The semiconductor laser according to claim 1, wherein a lower electrode is provided in a region other than the notch on a surface of the semiconductor substrate opposite to the semiconductor layer.   The semiconductor laser according to claim 1, wherein the stress generating portion is made of a metal.   9. The semiconductor laser according to claim 8, wherein the metal is copper or aluminum.   2. The width of the notch in a direction orthogonal to the extending direction of the current confinement structure is wider than a width of the current confinement structure in a direction orthogonal to the extending direction of the current confinement structure. Semiconductor laser.   The semiconductor laser according to claim 1, wherein a depth of the notch is equal to or shallower than a thickness of the semiconductor substrate.   2. The semiconductor laser according to claim 1, wherein the semiconductor layer has an upper electrode over at least the entire region facing the current confinement structure in the surface of the semiconductor layer on the current confinement structure side.

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