Abstract:
A semiconductor light emitting device comprises: a stacked body of semiconductor including an active layer; a ridge stripe protruding and extending in a first direction on a first major surface of the stacked body; dummy ridges protruding on the first major surface of the stacked body on both sides of the ridge stripe; and a slit formed on the first major surface of the stacked body. The ridge stripe includes at least a portion of a waveguide that guides light emission generated by injected current. The slit extends along a second direction which crosses the first direction, and divides one of the dummy ridges.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2004-028159, filed on Feb. 4, 2004; the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a semiconductor light emitting device and a semiconductor light emitting apparatus, and more particularly, to a semiconductor light emitting device such as a semiconductor laser with a ridge stripe and a semiconductor light emitting apparatus equipped with the same. 
     In recent years, semiconductor lasers having oscillation wavelengths of 600 to 700 nm have been put to practical use such as in DVD (digital versatile disc). For their further application to writing for DVD-R (recordable) and DVD-RW (rewritable), higher output power is required. One of the device structures of a semiconductor laser that meets such requirements is a “ridge-waveguide type” structure. In a ridge-waveguide type semiconductor laser, lightwave is confined and propagated in a stripe-shaped ridge to control the horizontal transverse mode. Thus it has an advantage that excellent optical output characteristics can be obtained. 
     In such a high-powered semiconductor laser, the amount of heat generated from its active layer is also increased. For this reason, in order to improve heat dissipation from the laser device, it is desirable to use a so-called “junction down” mounting configuration, in which the p-n junction is mounted in the close vicinity of a submount or other packaging member. 
     However, in junction down mounting, there is a problem that stress concentrates on the ridge protruding like a stripe, which makes the ridge prone to break. In this respect, a semiconductor laser comprising “dummy ridges” on both sides of the ridge is disclosed (e.g., Japanese Laid-Open Patent Applications 2000-164986 and 2002-223039). 
       FIG. 30  is a plan view of a semiconductor laser comprising dummy ridges as viewed from its mounting surface. 
       FIG. 31  is a cross-sectional view along line A-A in  FIG. 30 . 
     More specifically, the semiconductor laser  100  shown in these figures has a ridge stripe  112  protruding like a stripe formed on its mounting surface M. Dummy ridges  114  are provided on both sides of the ridge stripe  112 . The dummy ridges  114  are continuously formed along the longitudinal direction of the ridge stripe  112 . 
     Current injected via electrodes (not shown) provided on the upper and lower surfaces of the device is narrowed by the ridge stripe  112  and causes light emission at the p-n junction formed on its bottom. The emitted light propagates in the ridge stripe  112  to cause laser oscillation, which is emitted as laser light L from the end face. 
     When such a laser device is mounted in the junction down configuration, the mounting stress may concentrate on the ridge stripe to cause its breakdown. In this respect, dummy ridges  114  with the same height as the ridge stripe  112  can be provided on both sides of the ridge stripe  112 . This can prevent the breakdown of the ridge stripe  112  by dispersing the stress when the mounting surface M is mounted on the packaging member (not shown). 
     SUMMARY OF THE INVENTION 
     According to an aspect of the invention, there is provided a semiconductor light emitting device comprising: a stacked body of semiconductor including an active layer; a ridge stripe protruding and extending in a first direction on a first major surface of the stacked body, the ridge stripe including at least a portion of a waveguide that guides light emission generated by injected current; dummy ridges protruding on the first major surface of the stacked body on both sides of the ridge stripe; and a slit formed on the first major surface of the stacked body, the slit extending along a second direction which crosses the first direction, and the slit dividing one of the dummy ridges. 
     According to other aspect of the invention, there is provided a semiconductor light emitting apparatus comprising: a packaging member; and a semiconductor light emitting device having: a stacked body of semiconductor including an active layer; a ridge stripe protruding and extending in a first direction on a first major surface of the stacked body, the ridge stripe including at least a portion of a waveguide that guides light emission generated by injected current; dummy ridges protruding on the first major surface of the stacked body on both sides of the ridge stripe; and a slit formed on the first major surface of the stacked body, the slit extending along a second direction which crosses the first direction, and the slit dividing one of the dummy ridges, the semiconductor light emitting device being bonded to the packaging member so that the packaging member faces the first major surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing a semiconductor light emitting device according to a first embodiment of the invention; 
         FIG. 2  is a plan view of a semiconductor light emitting device of the first embodiment of the invention as viewed from its mounting surface M; 
         FIG. 3  is a cross-sectional view along line A-A in  FIG. 2 ; 
         FIG. 4  is a cross-sectional view along line B-B in  FIG. 2 ; 
         FIG. 5  is a conceptual view for illustrating the function of the slit  16 ; 
         FIG. 6  is a partial enlarged cross-sectional view showing a semiconductor laser device of the first embodiment of the invention in a mounted state; 
         FIG. 7  is a schematic cross-sectional view showing the semiconductor light emitting device on which a solder layer is formed; 
         FIG. 8  is a partial enlarged cross-sectional view showing a variation of the light emitting device of the first embodiment of the invention; 
         FIG. 9  is a partial enlarged cross-sectional view showing a specific example having a structure of a lowered ridge stripe  12 ; 
         FIG. 10  is a partial enlarged cross-sectional view showing a second specific example having a structure of a lowered ridge stripe  12 ; 
         FIG. 11  is a partial enlarged cross-sectional view showing a third specific example having a structure of a lowered ridge stripe  12 ; 
         FIG. 12  is a plan view of a semiconductor light emitting device according to a second embodiment of the invention as viewed from its mounting surface; 
         FIG. 13  is a cross-sectional view along line A-A in  FIG. 12 ; 
         FIG. 14  is a cross-sectional view along line B-B in  FIG. 12 ; 
         FIG. 15  is a plan view of a semiconductor light emitting device according to a third embodiment of the invention as viewed from its mounting surface; 
         FIG. 16  is a plan view of a semiconductor light emitting device according to a fourth embodiment of the invention as viewed from its mounting surface; 
         FIG. 17  is a plan view of a semiconductor light emitting device according to a fifth embodiment of the invention as viewed from its mounting surface; 
         FIG. 18  is a plan view of a semiconductor light emitting device according to a sixth embodiment of the invention as viewed from its mounting surface; 
         FIG. 19  is a plan view of a semiconductor light emitting device according to a seventh embodiment of the invention as viewed from its mounting surface; 
         FIGS. 20 and 21  are partial enlarged cross-sectional views of a semiconductor light emitting device according to an eighth embodiment of the invention; 
         FIGS. 22 and 23  are partial enlarged cross-sectional views of a semiconductor light emitting device according to a ninth embodiment of the invention; 
         FIG. 24  shows a cross-sectional structure of a relevant part of the semiconductor light emitting device as an example of the invention; 
         FIGS. 25 and 26  are process cross-sectional views showing part of the semiconductor laser of the example of the invention; 
         FIG. 27  is a schematic view showing an example of a semiconductor light emitting apparatus of an embodiment of the invention; 
         FIG. 28  is a schematic view showing a second specific example of the semiconductor light emitting apparatus of an embodiment of the invention; 
         FIG. 29  is a schematic cross-sectional view showing a third specific example of the semiconductor light emitting apparatus of an embodiment of the invention; 
         FIG. 30  is a plan view of a semiconductor laser comprising dummy ridges as viewed from its mounting surface; 
         FIG. 31  is a cross-sectional view along line A-A in  FIG. 30 ; and 
         FIG. 32  is a partial enlarged view showing a cross section after the semiconductor laser shown in  FIGS. 30 and 31  is mounted in the junction down configuration. 
     
    
    
     DETAILED DESCRIPTION 
     The inventor&#39;s independent trial production and investigation has revealed that the semiconductor laser as shown in  FIGS. 30 and 31  mounted on the packaging member in the junction down configuration may have void formed in the solder layer underlying the ridge stripe  112 , which may degrade temperature or other characteristics. 
       FIG. 32  is a partial enlarged view showing a cross section after the semiconductor laser shown in  FIGS. 30 and 31  is mounted in the junction down configuration. 
     When the semiconductor laser  100  was mounted on a submount  200  with gold-tin (Au—Sn)  50 , void V was formed in the solder layer of gold-tin  50  below the ridge stripe  112 . It was observed that the void V extended from directly below the ridge stripe  112  to the dummy ridges  114  formed on its both sides. Formation of such void V significantly decreases the thermal contact between the semiconductor laser  100  and the submount  200 . As a result, heat generated at the p-n junction underlying the ridge stripe  112  may not be dissipated, thereby significantly degrading the thermal characteristics of the semiconductor laser  100 . That is, it may cause decrease of output, maximum operating temperature, and long-term reliability. 
     Embodiments of the invention will now be described with reference to the drawings. 
       FIG. 1  is a perspective view showing a semiconductor light emitting device according to a first embodiment of the invention. 
       FIG. 2  is a plan view of a semiconductor light emitting device of the first embodiment as viewed from its mounting surface M. 
       FIG. 3  is a cross-sectional view along line A-A in  FIG. 2 , and  FIG. 4  is a cross-sectional view along line B-B in  FIG. 2 . 
     More specifically, the semiconductor light emitting device  10  shown in these figures is a ridge-waveguide type semiconductor laser. The laser device  10  is mounted on a packaging member (not shown) in the junction down configuration. Laser light L is emitted from an end face  10 E near the ridge stripe  12 . The ridge stripe  12  protruding like a stripe is formed on the mounting surface M. Dummy ridges  114  are provided on both sides of the ridge stripe  112  with certain spacing. It should be noted that in this embodiment, the dummy ridges are not continuously formed along the longitudinal direction of the ridge stripe  12 , but are separated as appropriate by a slit  16 . 
       FIG. 5  is a conceptual view for illustrating the function of the slit  16 . More specifically, when the laser device  10  is mounted on a submount or other packaging member (not shown) with solder (or adhesive) such as gold-tin, void V may occur in the solder layer as described above with reference to  FIG. 32 . This is because the dummy ridges  14  provided on both sides of the ridge stripe  12  prevent air bubbles from escaping out of the solder layer. On the contrary, according to this embodiment, the slit  16  provided to the dummy ridges  14  can provide an “escape route” for void V. That is, even if void V as shown occurs from air involved in the solder layer below the ridge stripe  12  at the time of mounting, the air can be ejected via the slit  16  as indicated by arrow E by applying weight on the laser device  10  against the packaging member. 
       FIG. 6  is a partial enlarged cross-sectional view showing a semiconductor laser device of the first embodiment in a mounted state. 
     More specifically, the laser device  10  is mounted on the submount  200  with the gold-tin solder layer  50  in the junction down configuration. According to this embodiment, no void is formed in the solder layer  50  as shown in the figure. The bottom of the ridge stripe  12  is bonded to the submount  200  with the continuous solder layer  50 . As a result, the physical bonding strength of the semiconductor laser device  10  can be improved, and at the same time, thermal contact can be significantly improved. That is, heat generated in the light emitting portion of the laser device  10  is efficiently dissipated to the submount  200 , which can improve not only the initial characteristics but also the long-term reliability of the laser. 
     The invention can also be applied to a semiconductor light emitting device in which bonding solder layer  50  made of gold-tin or the like is formed in advance. 
       FIG. 7  is a schematic cross-sectional view showing the semiconductor light emitting device on which a solder layer is formed. That is, this figure corresponds to the line A-A cross section in  FIG. 2 . With respect to  FIG. 7 , elements similar to those described with reference to  FIGS. 1 to 6  are marked with the same numerals and are not described in detail. 
     In the light emitting device of this specific example, a solder layer  50  is formed on the mounting surface M of the device. The solder layer  50  can be formed, for example, by depositing solder material such as gold-tin by vapor deposition or other methods, as described in detail later as an example of the invention. 
     In one method of mounting a light emitting device with solder, a solder chip in the form of preform or the like is placed on the packaging member, and the light emitting device is placed thereon. By applying weight to the device with heating, the solder chip is melted, and thereby the device is bonded. In this case, however, solder preform is required, and its handling is cumbersome. 
     In this respect, as illustrated in  FIG. 7 , the mounting process can be significantly simplified by forming a solder layer  50  on the mounting surface of the light emitting device in advance. However, when a solder layer  50  is formed with uniform thickness, air tends to remain near the center of the light emitting device, that is, in the portion below the ridge stripe  12 , which may cause formation of void V. 
     On the contrary, according to this embodiment, an escape route of air is provided and generation of void V can be prevented by providing a slit  16  as illustrated in  FIG. 5 . As a result, the light emitting device  10  can be firmly bonded to achieve good thermal contact. 
     On the other hand, it is particularly advantageous to apply the invention to a light emitting device having a ridge stripe  12  formed lower than dummy ridges  14 . 
       FIG. 8  is a partial enlarged cross-sectional view showing a variation of the light emitting device of the first embodiment. That is, this figure corresponds to the line A-A cross section in  FIG. 2 . 
     In the light emitting device of this specific example, in the mounting surface M, the ridge stripe  12  is formed lower than the dummy ridges  14  by height H. As described in detail later, this height difference may inevitably occur in the structure of concentrating current on the ridge stripe  12 , for example. 
     When the ridge stripe  12  is lower than the surrounding dummy ridges  14  like this, air involved in the solder layer below the ridge stripe  12  is difficult to escape at the time of mounting, and void V tends to be formed as illustrated in  FIG. 32 . 
     On the contrary, according to this embodiment, an escape route of air is provided and generation of void V can be prevented by providing a slit  16  as illustrated in  FIG. 5 . As a result, the light emitting device  10  can be firmly bonded to achieve good thermal contact. 
       FIG. 9  is a partial enlarged cross-sectional view showing a specific example having a structure of a lowered ridge stripe  12 . That is, this figure also corresponds to the line A-A cross section in  FIG. 2 . 
     In the light emitting device of this specific example, an insulating layer  40  is provided in the range from the side surface of the ridge stripe  12  to the top surface of the dummy ridges  14 . The insulating layer  40  may be made of, for example, dielectric material such as silicon oxides and silicon nitrides, or high resistance semiconductors. Provision of such an insulating layer  40  can block injection of current via the dummy ridges  14 . In other words, as shown in  FIG. 9 , in the mounting surface M, current I can be injected only into the ridge stripe  12  to cause light emission only in the close vicinity of the waveguide, which leads to the laser output with high efficiency. 
       FIG. 10  is a partial enlarged cross-sectional view showing a second specific example having a structure of a lowered ridge stripe  12 . That is, this figure also corresponds to the line A-A cross section in  FIG. 2 . 
     In the light emitting device of this specific example, an insulating layer  40  is provided only on the top surface of the dummy ridges  14 . Provision of an insulating layer  40  like this can also cause current I to be injected only into the ridge stripe  12 . That is, light emission is caused only in the close vicinity of the waveguide, and thereby the laser output can be obtained with high efficiency. 
       FIG. 11  is a partial enlarged cross-sectional view showing a third specific example having a structure of a lowered ridge stripe  12 . That is, this figure also corresponds to the line A-A cross section in  FIG. 2 . 
     In the light emitting device of this specific example, a current blocking layer  42  is provided only in the basal portion of the dummy ridges  14 . The current blocking layer  42  can be formed, for example, with high resistance semiconductors, or as a structure including a p-n junction to which reverse bias is applied during laser operation. Provision of a current blocking layer  42  like this can also cause current I to be injected only into the ridge stripe  12 . That is, light emission is caused only in the close vicinity of the waveguide, and thereby the laser output can be obtained with high efficiency. 
     Here, as described above with reference to  FIG. 8 , when the ridge stripe  12  is lowered by an amount of the thickness H of the insulating layer  40  or the current blocking layer  42 , void V tends to be formed in that portion of the solder layer. On the contrary, according to this embodiment, an escape route of air is provided and generation of void V can be prevented by providing a slit  16  as illustrated in  FIG. 5 . As a result, the light emitting device  10  can be firmly bonded to achieve good thermal contact. 
       FIG. 12  is a plan view of a semiconductor light emitting device according to a second embodiment of the invention as viewed from its mounting surface. 
       FIG. 13  is a cross-sectional view along line A-A in  FIG. 12 , and  FIG. 14  is a cross-sectional view along line B-B in  FIG. 12 . With respect to these figures, elements similar to those described with reference to  FIGS. 1 to 11  are marked with the same numerals and are not described in detail. 
     In this specific example, two slits  16  are provided on both sides of the ridge stripe  12 , respectively. That is, two routes for ejecting air out of the solder layer at the time of mounting are provided on both sides of the ridge stripe  12 , respectively. This promotes the “escape” of air from the solder layer and can prevent formation of void V more reliably. 
     It should be noted that if the number of slits  16  is further increased, the “escape” of air can be further promoted. That is, as long as the stress dispersion effect of the dummy ridges  14  is maintained, the number of slits  16  can be increased to suppress formation of void V more reliably, which leads to a semiconductor laser device with high performance. 
       FIG. 15  is a plan view of a semiconductor light emitting device according to a third embodiment of the invention as viewed from its mounting surface. Here, the line A-A cross section in  FIG. 15  is as shown in  FIG. 3  or  13 . The line B-B cross section in  FIG. 15  is as shown in  FIG. 4  or  14 . 
     In the light emitting device of this specific example, the slits  16  are formed in a fan shape as viewed from the ridge stripe  12 . That is, the slits  16  are provided so as to widen with the distance from the ridge stripe  12 . Accordingly, the dummy ridge  14  is formed in a triangular shape with its base facing the ridge stripe  12 . 
     Also in this specific example, an escape route of air is provided and generation of void V can be prevented by providing the slits  16 . In addition, by forming the slit  16  in a fan shape, the conductance for the “escape” of air is increased, and thereby generation of void V in the solder layer can be suppressed more effectively. 
     Moreover, in this specific example, the ridge stripe  12  is sufficiently protected by forming the dummy ridge  14  in a triangular shape with its base facing the ridge stripe  12 . That is, since the ridge stripe  12  is almost surrounded on its both sides by the dummy ridges  14 , weight applied at the time of mounting is dispersed efficiently, and thereby the ridge stripe  12  can be protected. 
       FIG. 16  is a plan view of a semiconductor light emitting device according to a fourth embodiment of the invention as viewed from its mounting surface. Here, the line A-A cross section in  FIG. 16  is as shown in  FIG. 3  or  13 . The line B-B cross section in  FIG. 16  is as shown in  FIG. 4  or  14 . 
     In the light emitting device of this specific example, the slits  16  are formed in a fan shape as viewed from the ridge stripe  12 , similar to the light emitting device of the third embodiment described above with reference to  FIG. 15 . However, the widening is smaller than that of the third embodiment. Accordingly, the dummy ridge  14  is formed in a trapezoidal shape with its base facing the ridge stripe  12 . 
     Also in this specific example, as with the third embodiment, by forming the slit  16  in a fan shape, the conductance for the “escape” of air is increased, and thereby generation of void V in the solder layer can be suppressed more effectively. Moreover, by forming the dummy ridge  14  in a trapezoidal shape with its base facing the ridge stripe  12 , the ridge stripe  12  is almost covered on its both sides with the dummy ridges  14 . Thus weight applied at the time of mounting is dispersed efficiently, and thereby the ridge stripe  12  can be protected. 
       FIG. 17  is a plan view of a semiconductor light emitting device according to a fifth embodiment of the invention as viewed from its mounting surface. Here, the line A-A cross section in  FIG. 17  is as shown in  FIG. 3  or  13 . The line B-B cross section in  FIG. 17  is as shown in  FIG. 4  or  14 . 
     In the light emitting device of this specific example, the slits  16  are formed in a reverse fan shape as viewed from the ridge stripe  12 . That is, the slits  16  are provided so as to be wide near the ridge stripe  12  and narrowed with the distance from the ridge stripe  12 . Accordingly, the dummy ridge  14  is formed in a triangular shape with its vertex facing the ridge stripe  12 . 
     Also in this specific example, an escape route of air is provided and generation of void V can be prevented by providing the slits  16 . In addition, according to this specific example, by forming the slit  16  in a reverse fan shape, the effect of moving the air layer below the ridge stripe  12  to the slit  16  is promoted. That is, since the protrusion of the dummy ridge  14  is reduced around the ridge stripe  12 , the air layer below the ridge stripe  12  tends to be pushed out toward the slit  16  when weight is applied at the time of mounting. As a result, formation of void V below the ridge stripe  12  can be prevented more reliably. 
       FIG. 18  is a plan view of a semiconductor light emitting device according to a sixth embodiment of the invention as viewed from its mounting surface. Here, the line A-A cross section in  FIG. 18  is as shown in  FIG. 3  or  13 . The line B-B cross section in  FIG. 18  is as shown in  FIG. 4  or  14 . 
     In the light emitting device of this specific example, the slits  16  are formed in a reverse fan shape as viewed from the ridge stripe  12 , similar to the light emitting device of the fifth embodiment described above with reference to  FIG. 17 . However, the widening is smaller than that of the fifth embodiment. Accordingly, the dummy ridge  14  is formed in a trapezoidal shape with its upper side facing the ridge stripe  12 . 
     Also in this specific example, as with the fifth embodiment, by forming the slit  16  in a reverse fan shape, the effect of moving the air layer below the ridge stripe  12  to the slit  16  is promoted. In addition, by forming the dummy ridge  14  in a trapezoidal shape, the area of the dummy ridge  14  can be increased relative to the fifth embodiment to enhance the stress dispersion effect. 
       FIG. 19  is a plan view of a semiconductor light emitting device according to a seventh embodiment of the invention as viewed from its mounting surface. Here, the line A-A cross section in  FIG. 19  is as shown in  FIG. 3  or  13 . The line B-B cross section in  FIG. 19  is as shown in  FIG. 4  or  14 . 
     In the light emitting device of this specific example, the dummy ridge  14  is formed in a plurality of elliptic patterns, and the slit  16  is formed as a gap between the elliptic dummy ridges  14 . When the dummy ridge  14  is formed in an elliptic or circular shape, the escape route of air from the ridge stripe  12  is also formed in a circular shape, which facilitates the “escape” of air. At the same time, a sufficient area of the dummy ridge  14  is provided to achieve the stress dispersion effect easily. 
       FIGS. 20 and 21  are partial enlarged cross-sectional views of a semiconductor light emitting device according to an eighth embodiment of the invention. That is,  FIG. 20  is a cross-sectional view in the vertical direction relative to the ridge stripe  12 , and corresponds to the line A-A cross section in  FIG. 2 ,  12 , or  15 , for example. 
       FIG. 21  is a cross-sectional view in the vertical direction relative to the slit  16 . 
     The semiconductor light emitting device of this embodiment comprises taper portions  14 T partly on the side surface of the dummy ridges  14 . 
     As shown in  FIG. 20 , when such a taper portion  14 T is provided on the side surface of the dummy ridge  14  facing the ridge stripe  12 , that portion is recessed as viewed from the ridge stripe  12 , which can promote movement of air from the ridge stripe  12 . 
     In addition, as shown in  FIG. 21 , when a taper portion  14 T is provided on the side surface of the dummy ridge  14  around the slit  16 , the escape route of air can be virtually expanded, which can promote the “escape” of air. 
       FIGS. 22 and 23  are partial enlarged cross-sectional views of a semiconductor light emitting device according to a ninth embodiment of the invention. That is,  FIG. 22 , as with  FIG. 20 , is a cross-sectional view in the vertical direction relative to the ridge stripe  12 , and corresponds to the line A-A cross section in  FIG. 2 ,  12 , or  15 , for example. 
       FIG. 23 , as with  FIG. 21 , is a cross-sectional view in the vertical direction relative to the slit  16 . 
     The semiconductor light emitting device of this embodiment comprises taper portions  14 T entirely on the side surface of the dummy ridges  14 . Therefore, the function and effect of the eighth embodiment described above with reference to  FIGS. 20 and 21  can be further enhanced. 
     EXAMPLE 
     Embodiments of the invention will now be described in further detail with reference to an example. 
       FIG. 24  shows a cross-sectional structure of a relevant part of the semiconductor light emitting device as an example of the invention. More specifically, this figure shows a cross section near the ridge stripe  12  of a semiconductor laser. 
     The semiconductor laser of this example is a ridge-waveguide type semiconductor laser that can oscillate around a wavelength of 650 nm. On an n-type GaAs substrate  21 , an n-type In 0.5 (Ga 0.3 Al 0.7 ) 0.5 P lower cladding layer  22 , In 0.5 (Ga 0.5 Al 0.5 ) 0.5 P optical guide layer  23 , InGaP/InGaAlP MQW (Multiple Quantum Well) active layer  24 , IN 0.5 (Ga 0.5 Al 0.5 ) 0.5 P optical guide layer  25 , p-type In 0.5 (Ga 0.3 Al 0.7 ) 0.5 P upper first cladding layer  26 , p-type In 0.5 Ga 0.5 P etching stopper layer  27 , p-type In 0.5 (Ga 0.3 Al 0.7 ) 0.5 P upper second cladding layer  28 , p-type In 0.5 Ga 0.5 P intermediate layer  29 , and p-type GaAs contact layer  30  are stacked in this order. 
     The second cladding layer  28  is patterned like a stripe to form a ridge stripe  12 . The ridge stripe  12  has a sloped portion  12   a  having sloped side surfaces, and a vertical portion  12   b  having generally vertical side surfaces on the sloped portion  12   a . A p-side electrode  31  is formed above the contact layer  30 , and an n-side electrode  32  is formed on the rear side of the substrate  21 . 
     Next, a method of manufacturing a semiconductor laser of this example will be described. 
       FIGS. 25 and 26  are process cross-sectional views showing part of the semiconductor laser of this example. 
     First, as shown in  FIG. 25A , a layered structure comprising a series of layers from the InGaAlP cladding layer  22  to the GaAs contact layer  30  is formed on the n-type GaAs substrate  21 . 
     Next, a ridge stripe and dummy ridges are formed by known techniques such as dry etching, wet etching, and sidewall techniques. At this time, as illustrated in  FIGS. 2 ,  5 ,  12 , and  15 , the dummy ridges  14  are not continuously formed along the longitudinal direction of the ridge stripe  12 , but slits  16  are provided as appropriate. 
     Subsequently, as shown in  FIG. 25B , silicon oxide film  230  is deposited again on the entire surface of the wafer by CVD method. 
     Subsequently, as shown in  FIG. 25C , the silicon oxide film  230  covering the top surface of the ridge stripe  12  is selectively etched away by known coating film planarization and lithography techniques to expose a contact portion extending to the top of the ridge. 
     After a p-side electrode  31  is formed, the rear side of the GaAs substrate  21  is polished to thin the wafer. 
     Next, as shown in  FIG. 25D , an n-side electrode  32  is formed on the rear surface of the GaAs substrate  21 . 
     Subsequently, as shown in  FIG. 26 , gold-tin  50  is applied as a solder layer, thereby completing the semiconductor laser of this example. 
     As described above, according to this example, a ridge-waveguide type semiconductor laser protected by dummy ridges  14  is obtained. As also shown in  FIG. 25C , in the semiconductor laser of this example, silicon oxide film  230  for blocking current is formed on the top surface of the dummy ridges  14 . Thus the ridge stripe  12  has a smaller height by the thickness of the silicon oxide film  230 . Therefore, when this laser device is mounted in the junction down configuration, void V tends to be formed in the solder layer as described above with reference to  FIG. 32 . In this respect, according to this example, slits  16  are provided as appropriate on both sides of the ridge stripe  12 . Thus, at the time of mounting, the “escape” of air is promoted, and formation of void V can be suppressed. As a result, it is possible to achieve a semiconductor light emitting apparatus that is bonded with physical robustness and simultaneously has a good thermal contact. 
     Next, a semiconductor light emitting apparatus of the embodiment of the invention will be described. 
       FIG. 27  is a schematic view showing an example of a semiconductor light emitting apparatus of an embodiment of the invention. That is,  FIG. 27A  is its plan view, and  FIG. 27B  is its front view. 
     The semiconductor light emitting apparatus of this specific example is referred to as of “chip-carrier type”. More specifically, a semiconductor light emitting device  10  is mounted on a carrier  300  made of insulating material such as aluminum nitride or aluminum oxide, or semiconductors such as silicon, in the junction down configuration with solder such as gold-tin, or conductive adhesive. Laser light L is emitted from the end face near the mounting surface of the semiconductor light emitting device  10 . 
     According to this embodiment, as described above with reference to  FIGS. 1 to 26 , slits  16  are provided as appropriate on the mounting surface of the semiconductor light emitting device  10  to suppress formation of void in the solder layer below the ridge stripe. It is thus possible to achieve a chip-carrier type semiconductor light emitting apparatus that has increased physical bonding strength for the chip carrier  300  and can maintain good thermal contact at the same time. 
       FIG. 28  is a schematic view showing a second specific example of the semiconductor light emitting apparatus of an embodiment of the invention. That is,  FIG. 28A  is its plan view, and  FIG. 28B  is its front view. 
     The semiconductor light emitting apparatus of this specific example is also a “chip-carrier type” apparatus. It differs from that shown in  FIG. 27  in that a submount  310  is provided between the carrier  300  and the semiconductor light emitting device  10 . The submount  310  serves to reduce thermal stress applied to the semiconductor light emitting device  10  by, for example, enhancing heat dissipation from the semiconductor light emitting device  10  and alleviating the difference of expansivity between the semiconductor light emitting device  10  and the carrier  300 . 
     Also in this embodiment, as described above with reference to  FIGS. 1 to 26 , slits  16  are provided as appropriate on the mounting surface of the semiconductor light emitting device  10  to suppress formation of void in the solder layer below the ridge stripe. It is thus possible to achieve a chip-carrier type semiconductor light emitting apparatus that has increased physical bonding strength for the submount  310  and can maintain good thermal contact at the same time. 
       FIG. 29  is a schematic cross-sectional view showing a third specific example of the semiconductor light emitting apparatus of an embodiment of the invention. More specifically, this figure shows a so-called can-seal type semiconductor light emitting apparatus. 
     The semiconductor light emitting apparatus  400  comprises a stem  410 , a stem mount  430 , and a sealing can  450 . The stem  410  is provided with lead pins  420 , enabling external electrical connection. The stem mount  430  is secured to the stem  410 . A semiconductor light emitting device  10  is mounted at the tip of the stem mount  430  in the junction down configuration via a submount  440 . Above the stem  410 , a monitoring light-receiving device  470  is provided for monitoring output from the semiconductor light emitting device  10  and performing appropriate feedback control. 
     The semiconductor light emitting device  10  is sealed with the sealing can  450 . Laser light emitted from the semiconductor light emitting device  10  is picked up externally via a window  460  made of translucent material such as glass, provided in the sealing can  450 . 
     Also in this embodiment, as described above with reference to  FIGS. 1 to 26 , slits  16  are provided as appropriate on the mounting surface of the semiconductor light emitting device  10  to suppress formation of void in the solder layer below the ridge stripe. It is thus possible to achieve a can-seal type semiconductor light emitting apparatus that has increased physical bonding strength for the submount  440  and can maintain good thermal contact at the same time. 
     The embodiments of the invention have been described with reference to specific examples. However, the invention is not limited to these specific examples. For example, any details of the layered structure constituting the semiconductor light emitting device modified as appropriate by those skilled in the art are also encompassed within the scope of the invention, as long as they comprise the feature of the invention. For example, the active layer may be made of various materials in addition to InGaAlP-based material, including Ga x In 1−x As y N 1−y -based (0≦x≦1, 0≦y&lt;1), AlGaAs-based, and InGaAsP-based materials. Similarly, the cladding layers and optical guide layer may also be made of various materials. 
     Any shape and size of the semiconductor light emitting device modified as appropriate by those skilled in the art are also encompassed within the scope of the invention, as long as they comprise the feature of the invention. Moreover, the shape and size of the ridge stripe, the shape and arrangement relationship of the dummy ridges, and the shape and number of the slits may also be modified in various ways, any of which is encompassed within the scope of the invention. 
     On the other hand, also with respect to the semiconductor light emitting apparatus of the invention, various apparatuses other than those described above as the specific examples are encompassed within the scope of the invention. They include, for example, a semiconductor light emitting apparatus having a receptacle for coupling an optical fiber in which the semiconductor light emitting device of the invention is incorporated, and a semiconductor light emitting apparatus having a packaging substrate on which the semiconductor light emitting device of the invention is mounted. In effect, any semiconductor light emitting apparatus in which a semiconductor light emitting device of the invention is mounted in the junction down configuration belongs to the scope of the semiconductor light emitting apparatus of the invention. 
     Any other semiconductor light emitting devices and semiconductor light emitting apparatuses that can be modified and implemented as appropriate by those skilled in the art on the basis of the semiconductor light emitting devices and semiconductor light emitting apparatuses described above as the embodiments of the invention also belong to the scope of the invention. 
     While the present invention has been disclosed in terms of the embodiment in order to facilitate better understanding thereof, it should be appreciated that the invention can be embodied in various ways without departing from the principle of the invention. Therefore, the invention should be understood to include all possible embodiments and modification to the shown embodiments which can be embodied without departing from the principle of the invention as set forth in the appended claims.