JP2008181928A - Semiconductor laser and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser capable of enhancing the laser output, and to provide a manufacturing method therefor. <P>SOLUTION: In the semiconductor laser, a step difference portion 11 lower than an upper surface 10A is formed on a substrate 10. The step difference portion 11 is formed so as to have side surfaces 11F, 11R each being preferably inclined at an angle not less than 54.7° for the upper surface 10A. A first semiconductor layer 20 including an active layer 23 is formed on this substrate 10. The side surfaces 20F, 20R of the first semiconductor layer 20 are formed into a (1-11) face or (11-1) face, inclined for the upper surface 10A of the substrate 10. Subsequent to this, a second semiconductor layer 30, with a non-absorption region having a larger bandgap than that of the active layer 23, is formed so as to contact at least the inclined side surfaces of the active layer 23 in the first semiconductor layer 20, on the upper surface and the side surfaces 20F, 20R of the first semiconductor layer 20. A portion, formed on the upper surface of the first semiconductor layer 20 of the second semiconductor layer 30, is removed by etching. The second semiconductor layer 30 is cleaved to form a pair of resonator end surfaces. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor laser suitable for a wide output range from low output to high output, and a method for manufacturing the same.

  In a semiconductor laser, when light output increases, non-radiative recombination of electrons and holes occurs due to light absorption at the end face, and heat generation is promoted. Further, when the temperature rises, the semiconductor band gap at the end face is lowered, and therefore, a vicious circle is formed in which light absorption further proceeds, causing damage to the end face, so-called COMD (Catastrophic Optical Mirror Damage). Therefore, the maximum optical output of the semiconductor laser is limited by COMD. When the light output reaches the COMD level, the light output declines with time, or tends to stop suddenly due to COMD.

As a method for avoiding this problem, it is known to provide a window having a band gap larger than that of the active layer around the end face (see, for example, Patent Document 1). With such a window, light absorption at the end face can be suppressed, and reliability in high output operation can be increased.
US Pat. No. 4,581,742

  Another method is to form a passivation film, such as silicon, on the raw end face prior to end face coating (Bookham; E2 process). However, this method requires an expensive apparatus for continuously performing cleavage and passivation film formation in a high vacuum.

  In addition, for example, a technique has been developed in which an end face coating is performed by electron beam evaporation after removing the end face oxide by applying a nitrogen ion beam to the end face in an ultra-high vacuum chamber and sealing the end face with a nitride layer. (Comlace, Inc .; Nitrel technology). However, this technology required additional equipment in addition to standard laser manufacturing equipment, and was therefore very expensive.

  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 increasing optical output and a method for manufacturing the same.

  A semiconductor laser according to the present invention includes a substrate having a flat upper surface, an active layer, a first semiconductor layer having a side surface inclined with respect to the upper surface of the substrate, and an inclined side surface of the first semiconductor layer. A pair of resonances in which at least one of the first semiconductor layers is formed in the second semiconductor layer and has a non-absorption region having a band gap larger than that of the active layer in contact with at least the inclined side surface of the active layer. And a vessel end face.

  According to the semiconductor laser manufacturing method of the present invention, a step having a step lower than the top surface is provided on a substrate having a flat top surface, a first semiconductor layer including an active layer is formed on the top surface of the substrate, Following the step of inclining the side surface of the semiconductor layer with respect to the upper surface of the substrate and the step of forming the first semiconductor layer, at least an active layer of the first semiconductor layer is formed on the upper surface and the inclined side surface of the first semiconductor layer. Forming a second semiconductor layer having a non-absorbing region having a band gap larger than that of the active layer in contact with the inclined side surface, and removing a portion of the second semiconductor layer formed on the upper surface of the first semiconductor layer And a step of cleaving the second semiconductor layer to form at least one of the pair of resonator end faces.

  In the semiconductor laser of the present invention, the second semiconductor layer having a non-absorption region having a band gap larger than that of the active layer on the inclined side surface of the first semiconductor layer in contact with at least the inclined side surface of the active layer of the first semiconductor layer. Since at least one of the resonator end faces is provided in the second semiconductor layer, light absorption in the second semiconductor layer in the vicinity of the resonator end face is suppressed. Therefore, non-radiative recombination of electrons and holes due to light absorption and heat generation due to this are suppressed. Therefore, a decrease in the band gap of the end face due to heat generation is reduced, and the occurrence of a vicious circle in which light absorption further proceeds is suppressed, and damage to the end face (COMD) is avoided.

  According to the semiconductor laser of the present invention, the second side having the non-absorbing region having a band gap larger than that of the active layer on the inclined side surface of the first semiconductor layer is in contact with at least the inclined side surface of the active layer of the first semiconductor layer. Since the semiconductor layer is formed and at least one of the pair of resonator end faces is formed on the second semiconductor layer, light absorption at the resonator end faces can be suppressed and the COMD level can be increased. Therefore, it is possible to increase the light output and achieve high reliability especially in high output operation.

  According to the method for manufacturing a semiconductor laser of the present invention, the first semiconductor layer is formed on the substrate provided with the stepped portion, the side surface of the first semiconductor layer is inclined with respect to the upper surface of the substrate, and subsequently, A second semiconductor layer having a non-absorbing region having a band gap larger than that of the active layer is formed on the upper surface and the inclined side surface of the first semiconductor layer in contact with at least the inclined side surface of the active layer of the first semiconductor layer. Since the portion of the second semiconductor layer formed on the upper surface of the first semiconductor layer is removed, the first semiconductor layer and the second semiconductor layer can be formed in the same process. Therefore, the conventional ex-situ process such as etching is not required between the semiconductor layer forming process and the non-absorbing layer forming process, and contamination of the resonator end face can be avoided and The performance of the absorption layer can be improved. Therefore, the light absorption suppression effect at the resonator end face can be improved, and a more reliable semiconductor laser can be manufactured.

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

(First embodiment)
FIG. 1 shows the structure of a semiconductor laser according to the first embodiment of the present invention. The semiconductor laser 1 is used, for example, as an excitation light source for a solid-state laser, and has a buffer layer 21, a first cladding layer 22, an active layer 23, a second cladding layer 24, and a cap on a flat upper surface 10A of a substrate 10. The layer 25 has the first semiconductor layer 20 stacked in this order.

  The substrate 10 is made of n-type GaAs to which an n-type impurity such as silicon (Si) or selenium (Se) is added, and its upper surface 10A is a (100) surface.

  The buffer layer 21 has, for example, a thickness in the stacking direction (hereinafter simply referred to as a thickness) of 100 nm and is made of n-type GaAs to which an n-type impurity such as silicon (Si) or selenium (Se) is added. The first cladding layer 22 has a thickness of 1.5 μm, for example, and is composed of an n-type AlGaAs mixed crystal to which an n-type impurity such as silicon (Si) or selenium (Se) is added.

  The active layer 23 has a thickness of 10 nm, for example, and is made of GaAs. The active layer 23 has a smaller band gap than the first cladding layer 22.

  For example, the second cladding layer 24 has a thickness of 1.5 μm and is made of a p-type AlGaAs mixed crystal to which a p-type impurity such as magnesium (Mg) or zinc (Zn) is added. The cap layer 25 has a thickness of, for example, 100 nm and is made of p-type GaAs to which a p-type impurity such as magnesium (Mg) or zinc (Zn) is added. The second cladding layer 24 and the cap layer 25 are formed as thin strips (ridges extending in the in-plane direction of the paper surface in FIG. 1), and the projecting portions of the active layer 23. The portion corresponding to is a current injection region.

  The first semiconductor layer 20 has side surfaces 20F and 20R that are inclined with respect to the upper surface 10A of the substrate 10. The side surfaces 20F and 20R are, for example, the (1-11) plane or the (11-1) plane, and the inclination angle with respect to the upper surface 10A of the substrate 10 is about 54.7 °. The inclined side surfaces 20F and 20R are provided with a second semiconductor layer 30 which is a non-absorbing region having a larger band gap than the active layer 23. The second semiconductor layer 30 has a pair of resonator end faces 40F, 40R is formed. The resonator end faces 40F and 40R are, for example, (0-11) planes or (01-1) planes. Thereby, in this semiconductor laser 1, the light absorption in the resonator end faces 40F and 40R can be suppressed, and the light output can be increased.

  Here, (1-11) is originally expressed by drawing an overline on the number as shown in chemical formula 1, but here, for convenience, a “-” is added before the number. To express. The same applies to (11-1), which is originally displayed as shown in Chemical Formula 2. Hereinafter, when similar expressions are used, they are displayed in the same manner.

The second semiconductor layer 30 is made of, for example, an AlGaAs mixed crystal. The composition ratio of aluminum (Al) contained in the second semiconductor layer 30 may be the same as the composition ratio of aluminum (Al) contained in the active layer 23, but is preferably slightly higher. On the other hand, if it is too high, the crystallinity is lowered, so that the aluminum (Al) composition ratio of the first cladding layer 22 or the second cladding layer 24 is preferably equal to or less. For example, when the wavelength λ is 800 nm, it is preferably 0.3 or more and 0.55 or less, and specifically, for example, Al _0.35 Ga _0.65 As mixed crystal is preferable. The thickness of the second semiconductor layer 30 is adjusted so that the distance d between the end of the active layer 23 and the resonator end faces 40F and 40R on the inclined side faces 20F and 20R can be made appropriate.

  A pair of reflecting mirror films 41F and 41R are formed on the resonator end faces 40F and 40R, respectively. The reflectance is adjusted so that the one reflecting mirror film 41F has a low reflectance and the reflecting mirror film 41R has a high reflectance. Thus, the light generated in the active layer 23 is amplified by reciprocating between the pair of reflecting mirror films 41F and 41R, and is emitted as a laser beam from the reflecting mirror film 41F having a low reflectance.

A p-side electrode 51 is formed on the surface of the cap layer 25. The p-side electrode 51 has a structure in which, for example, titanium (Ti), platinum (Pt), and gold (Au) are sequentially stacked, and is electrically connected to the cap layer 25. Note that both sides of the ridge are covered with an insulating layer (not shown) made of, for example, silicon dioxide (SiO ₂ ) or silicon nitride (SiN). An n-side electrode 52 is formed on the back surface 10 </ b> B of the substrate 10. The n-side electrode 52 has a structure in which, for example, AuGe: Ni and gold (Au) are sequentially stacked and alloyed by heat treatment, and is electrically connected to the substrate 10.

  The semiconductor laser 1 can be manufactured, for example, as follows.

  First, as shown in FIGS. 2 and 3, a substrate 10 made of the above-described material and having an upper surface 10A of a (100) surface is prepared. For example, chemical etching or reactive ion etching (RIE; A step portion 11 lower than the upper surface 10A is formed by Reactive Ion Etching. The step portion 11 is continuous with the step portions 11 of the semiconductor lasers 1 adjacent to each other and has a number of parallel concave grooves. The formation position of the stepped portion 11 is preferably set to the formation planned positions 40FA and 40RA of the resonator end faces 40F and 40R or in the vicinity thereof.

  The step portion 11 is formed to have, for example, the (01-1) plane or the (0-11) plane as the side surfaces 11F and 11R perpendicular to the upper surface 10A of the substrate 10. Note that the angle formed between the side surfaces 11F and 11R of the step portion 11 and the bottom surface 11A may be a right angle as shown in FIG. 3 or a rounded corner as shown in FIG.

  Next, as shown in FIG. 5, for example, MOCVD (Metal Organic Chemical Vapor Deposition) method or MBE (Molecular Beam) is formed on the upper surface 10A of the substrate 10 provided with the stepped portion 11 as described above. The buffer layer 21, the first cladding layer 22, the active layer 23, the second cladding layer 24, and the cap layer 25 made of the above-described thickness and material are sequentially stacked by an epitaxial technique such as Epitaxy (molecular beam epitaxy) method. 1 A semiconductor layer 20 is formed. At that time, the side surfaces 20F and 20R of the first semiconductor layer 20 are the (1-11) plane or the (11-1) plane inclined by about 54.7 ° with respect to the (100) plane which is the upper surface 10A of the substrate 10. Become. Since the growth rate of the (1-11) plane and the (11-1) plane is much slower than the growth rate of the (100) plane, the growth of the buffer layer 21 to the cap layer 25 is performed on the upper surface 10A of the substrate 10 and the step portion 11. Growth proceeds on the bottom surface 11A, and no growth occurs on the inclined side surfaces 20F and 20R. As a result, the first semiconductor layer 20 including the active layer 23 sandwiched between the two inclined side surfaces 20F and 20R is formed on the upper surface 10A of the substrate 10. Although the first semiconductor layer 20 is also formed in the step portion 11, the inclined side surfaces 20F and 20R are generated in a portion of the first semiconductor layer 20 formed on the upper surface 10A of the substrate 10. .

  After the first semiconductor layer 20 is formed, the second semiconductor layer 30 made of the above-described material is formed on the upper surface and the inclined side surfaces 20F and 20R of the first semiconductor layer 20 as shown in FIG. Form.

  Subsequently, as shown in FIG. 6, a portion of the second semiconductor layer 30 formed on the upper surface of the first semiconductor layer 20 is removed by, for example, etching. As a result, the second semiconductor layer 30 is formed on the inclined side surfaces 20F and 20R of the first semiconductor layer 20.

  After that, a part of the cap layer 25 and the p-type cladding layer 24 is selectively removed by, for example, etching to form a thin strip-shaped protrusion. After the protrusions are formed, an insulating layer (not shown) made of the above-described material is formed on both sides thereof by, for example, a CVD (Chemical Vapor Deposition) method.

  After forming the insulating layer, for example, the back side of the substrate 11 is ground to a thickness of the substrate 10 of about 110 μm, and the n-side electrode 52 is formed on the back side of the substrate 11. Further, an opening is provided in the insulating layer corresponding to the cap layer 25 by, for example, etching, and the p-side electrode 51 is formed on the cap layer 25 and the insulating layer.

  After forming the n-side electrode 52 and the p-side electrode 51, the second semiconductor layer 30 is cleaved along the (0-11) plane and the (01-1) plane to form a pair of resonator end faces 40F and 40R. At this time, the resonator end faces 40F and 40R are preferably formed using a high-precision cleavage device in order to control the thickness of the second semiconductor layer 30, that is, the distance d described above.

  After the resonator end surfaces 40F and 40R are formed, a pair of reflecting mirror films 41F and 41R are formed on the resonator end surfaces 40F and 40R, for example, by vapor deposition. Thereby, the semiconductor laser 10 shown in FIG. 1 is formed.

  In this semiconductor laser 1, when a predetermined voltage is applied between the n-side electrode 52 and the p-side electrode 51, a current is injected into the active layer 23 and light emission occurs due to electron-hole recombination. This light is reflected by the pair of reflecting mirror films 41F and 41R, reciprocates between them to generate laser oscillation, and is emitted to the outside as a laser beam. Here, the second semiconductor layer 30, which is a non-absorbing region having a larger band gap than the active layer 23, is formed on the inclined side surfaces 20 </ b> F and 20 </ b> R of the first semiconductor layer 20, and resonance occurs in the second semiconductor layer 30. Since the cavity end faces 40F and 40R are provided, light absorption at the cavity end faces 40F and 40R is suppressed, and the COMD level increases. Therefore, the light output is increased, and the reliability in high output operation is improved.

  Further, the second semiconductor layer 30 is formed by forming the first semiconductor layer 20 having the inclined side surfaces 20F and 20R on the upper surface 10A of the substrate 10 provided with the stepped portion 11, and subsequently performing the same epitaxial growth process. Therefore, contamination of the resonator end faces 40F and 40R is avoided, and the performance of the second semiconductor layer 30 is improved. Therefore, the light absorption suppression effect at the resonator end faces 40F and 40R is improved.

  Thus, in the semiconductor laser 1 of the present embodiment, the second semiconductor layer 30 that is a non-absorbing region having a larger band gap than the active layer 23 is formed on the inclined side surfaces 20F and 20R of the first semiconductor layer 20, Since the resonator end faces 40F and 40R are provided in the second semiconductor layer 30, light absorption at the resonator end faces 40F and 40R can be suppressed, and the COMD level can be increased. Therefore, it is possible to increase the light output and achieve high reliability especially in high output operation.

  In the method of manufacturing the semiconductor laser 1 according to the present embodiment, the first semiconductor layer 20 having the side surfaces 20F and 20R inclined with respect to the upper surface 10A is formed on the upper surface 10A of the substrate 10 provided with the stepped portion 11. After the formation, the second semiconductor layer 30 is formed on the upper surface of the first semiconductor layer 20 and the inclined side surfaces 20F and 20R, and the second semiconductor layer 30 is formed on the upper surface of the first semiconductor layer 20. Therefore, the first semiconductor layer 20 and the second semiconductor layer 30 can be formed in the same process. Therefore, the conventional ex-situ process such as etching is not required between the process of forming the first semiconductor layer 20 and the process of forming the second semiconductor layer 30, and contamination of the resonator end faces 40F and 40R is eliminated. This can be avoided and the performance of the second semiconductor layer 30 can be improved. Therefore, the light absorption suppression effect at the resonator end faces 40F and 40R can be improved, and the semiconductor laser 1 with higher reliability can be manufactured. Further, high-cost additional equipment such as an ultra-high vacuum apparatus for cleaving and end face processing is not required, and the manufacturing can be performed only with a normal semiconductor laser manufacturing equipment, so that the cost can be reduced.

  In the above embodiment, the case where the side surfaces 11F and 11R of the step portion 11 are the (01-1) plane or the (0-11) plane perpendicular to the upper surface 10A of the substrate 10 has been described. The side surfaces 11F and 11R of the part 11 may be inclined with respect to the upper surface 10A of the substrate 10 as shown in FIG. In that case, it is preferable that the side surfaces 11F and 11R of the step portion 11 form an angle of, for example, 54.7 ° or more with respect to the upper surface 10A of the substrate 10. 54.7 ° is an angle formed by the (1-11) plane or the (11-1) plane with respect to the (100) plane. Further, the side surfaces 11F and 11R of the step portion 11 may be the (1-11) plane or the (11-1) plane having the same plane index as the side surfaces 20F and 20R of the first semiconductor layer 20, but the side surfaces 11F and 11R are In the initial state (the state before the first semiconductor layer 20 is formed), it is not always necessary to have the same plane index as the side surfaces 20F and 20R of the first semiconductor layer 20. Even when the side surfaces 11F and 11R of the step portion 11 are surfaces having different plane indices from the side surfaces 20F and 20R of the first semiconductor layer 20, the side surfaces 20F of the first semiconductor layer 20 are grown during the growth of the first semiconductor layer 20. 20R, the (1-11) plane or the (11-1) plane, which is a non-growth plane, appears, and the second semiconductor layer 30 is formed there.

  In the above-described embodiment, the case where the stepped portion 11 described in the manufacturing process is not included in the completed semiconductor laser 1 has been described. However, as illustrated in FIG. The semiconductor laser 1 may have a step portion 11 depending on the formation position.

(Second Embodiment)
FIG. 9 shows the configuration of the semiconductor laser 2 according to the second embodiment of the present invention. In this semiconductor laser 2, a current blocking layer 60 made of an insulating material such as silicon dioxide (SiO ₂ ) is provided on the upper surface of the second semiconductor layer 30 in order to suppress current injection from the p-side electrode 51. . Thereby, in the present embodiment, current crowding (current concentration) around the resonator end faces 40F and 40R can be avoided. Except for this, the semiconductor laser 2 has the same configuration, operation and effect as the semiconductor laser 1 described in the first embodiment.

  In the semiconductor laser 2, after the second semiconductor layer 30 is formed, the current blocking layer 60 is formed on the upper surface of the second semiconductor layer 30 by, for example, a CVD (Chemical Vapor Deposition) method. Except for this, it can be manufactured in the same manner as in the first embodiment.

(Third embodiment)
FIG. 10 shows the configuration of the semiconductor laser 3 according to the third embodiment of the present invention. In the semiconductor laser 3, the second semiconductor layer 30 includes a current blocking unit 31 that forms a PNP junction by disposing an n-type layer 31 </ b> C between two p-type layers 31 </ b> A and 31 </ b> B. Further, the current blocking unit 31 may be configured by forming an NPN junction by disposing a p-type layer between two n-type layers. Thereby, in this embodiment, current crowding around the resonator end faces 40F and 40R can be avoided. Except for this, the semiconductor laser 3 has the same configuration, operation, and effects as the semiconductor laser 1 described in the first embodiment.

  The semiconductor laser 3 is the first except that an impurity is added to the AlGaAs mixed crystal during the growth of the second semiconductor layer 30 to form a current blocking portion 31 having a PNP junction or an NPN junction. It can be manufactured in the same manner as in the embodiment.

  Note that the current blocking portion 31 does not necessarily have to be a non-absorbing region having a larger band gap than the active layer 23. However, when the current blocking portion 31 is not a non-absorbing region, the current blocking portion 31 is preferably provided in contact with the second cladding layer 24 other than the active layer 23 in the first semiconductor layer 20. .

(Fourth embodiment)
FIG. 11 shows a configuration of a semiconductor laser 4 according to the fourth embodiment of the present invention. The semiconductor laser 4 does not use the entire second semiconductor layer 30 as a non-absorbing region as in the first embodiment, but partially contacts the inclined side surfaces 20F and 20R of the active layer 23 as a non-absorbing region. 30A, and light confinement layers 32A and 32B having a refractive index smaller than that of the non-absorbing region 30A are provided above and below the non-absorbing region 30A. Thereby, in this semiconductor laser 4, the non-absorption region 30A also has a function as a waveguide, and the laser beam generated in the active layer 23 is guided into the non-absorption region 30A. The optical confinement layers 32 </ b> A and 32 </ b> B do not necessarily have a band gap larger than that of the active layer 23. Except for this, the semiconductor laser 4 has the same configuration, operation, and effect as the semiconductor laser 1 described in the first embodiment.

  The semiconductor laser 4 forms, for example, the non-absorption region 30A and the light confinement layers 32A and 32B by adjusting the aluminum (Al) composition ratio contained in the AlGaAs mixed crystal during the growth of the second semiconductor layer 30. Except for this, it can be manufactured in the same manner as in the first embodiment. The aluminum (Al) composition ratio of the non-absorbing region 30A is slightly higher than that of the active layer 23, for example, about 0.3, and the aluminum (Al) composition ratio of the light confinement layers 32A, 32B is, for example, the first cladding layer 22 and The second cladding layer 24 is desirably about 0.55, which is the same as the second cladding layer 24.

  While the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above embodiment, the case where both the pair of resonator end faces 40F and 40R are formed in the second semiconductor layer 30 has been described. However, at least one of the resonator end faces 40F and 40R is the second semiconductor layer. 30 should just be formed.

  Further, for example, the material and thickness of each layer described in the above embodiment, the film formation method and the film formation conditions are not limited, and other materials and thicknesses may be used, or other film formation methods and Film forming conditions may be used. For example, in the above-described embodiment, the n-type buffer layer 21, the n-type first cladding layer 22, the active layer 23, the p-type second cladding layer 24 and the p-type second layer are formed on the upper surface 10 A of the n-type substrate 10. Although the case where the cap layer 25 is sequentially stacked has been described, a p-type substrate is used, a p-type buffer layer, a p-type first cladding layer, an active layer, an n-type second cladding layer, and an n-type cap layer. May be laminated in order.

  Further, for example, in the above-described embodiment, the configuration of the semiconductor laser 1 has been specifically described, but it is not necessary to include all layers, and other layers such as a buffer layer may be further included. Furthermore, the present invention can be applied not only to the refractive index waveguide type described in the above embodiment, but also to the gain waveguide type. In addition, the semiconductor laser 1 according to the present invention can improve the reliability particularly in the high output operation, but is not limited to the high output laser but is effective in a wide output range from low output to high output.

It is sectional drawing showing the structure of the semiconductor laser which concerns on the 1st Embodiment of this invention. FIG. 2 is a perspective view illustrating a manufacturing method of the semiconductor laser illustrated in FIG. 1 in order of steps. It is sectional drawing along the III-III line of FIG. It is sectional drawing showing the modification of the level | step-difference part shown in FIG. FIG. 4 is a cross-sectional view illustrating a process following FIG. 3. FIG. 5 is a cross-sectional view illustrating a process following FIG. 4. It is sectional drawing showing the other modification of the level | step-difference part shown in FIG. It is a figure showing the modification of the semiconductor laser shown in FIG. It is sectional drawing showing the structure of the semiconductor laser which concerns on the 2nd Embodiment of this invention. It is sectional drawing showing the structure of the semiconductor laser which concerns on the 3rd Embodiment of this invention. It is sectional drawing showing the structure of the semiconductor laser which concerns on the 4th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser, 10 ... Board | substrate, 10A ... Upper surface, 11 ... Step part, 11A ... Bottom surface, 11F, 11R ... Side surface, 20 ... 1st semiconductor layer, 21 ... Buffer layer, 22 ... 1st clad layer, 23 ... Active Layer, 24 ... second cladding layer, 25 ... cap layer, 26 ... non-absorbing layer, 30 ... second semiconductor layer, 30A ... non-absorbing region, 31 ... current blocking portion, 31A, 31B ... n (p) type layer, 31C ... p (n) type layer, 32A, 32B ... light confinement layer, 40F, 40R ... resonator end face, 41F, 41R ... reflecting mirror film, 51 ... p-side electrode, 52 ... n-side electrode, 60 ... current blocking layer

Claims (11)

A substrate having a flat top surface;
A first semiconductor layer including an active layer and having a side surface inclined with respect to the upper surface of the substrate;
A second semiconductor layer provided on an inclined side surface of the first semiconductor layer and having a non-absorbing region having a larger band gap than the active layer in contact with at least the inclined side surface of the active layer of the first semiconductor layer When,
A semiconductor laser comprising: a pair of resonator end faces formed on at least one of the second semiconductor layers. The semiconductor laser according to claim 1, wherein the substrate is made of GaAs. 2. The semiconductor laser according to claim 1, wherein an upper surface of the substrate is a (100) plane, and an inclined side surface of the first semiconductor layer is a (1-11) plane or a (11-1) plane. The semiconductor laser according to claim 1, wherein the substrate has a step portion having a side surface inclined with respect to the upper surface. 5. The semiconductor laser according to claim 4, wherein the side surface of the stepped portion forms an angle of 54.7 ° or more with respect to the upper surface of the substrate. 2. The semiconductor laser according to claim 1, wherein an electrode is provided on an upper surface of the first semiconductor layer, and a current blocking layer for suppressing current injection from the electrode is provided on the upper surface of the second semiconductor layer. . The semiconductor laser according to claim 1, wherein the second semiconductor layer includes a current blocking portion in which a second conductivity type layer is provided between two layers of the first conductivity type. The semiconductor laser according to claim 1, wherein the second semiconductor layer has light confinement layers having a refractive index smaller than that of the non-absorbing region above and below the non-absorbing region. Providing a step portion lower than the upper surface on a substrate having a flat upper surface;
Forming a first semiconductor layer including an active layer on an upper surface of the substrate, and inclining a side surface of the first semiconductor layer with respect to the upper surface of the substrate;
Following the step of forming the first semiconductor layer, the upper surface and the inclined side surface of the first semiconductor layer are in contact with at least the inclined side surface of the active layer of the first semiconductor layer and more band than the active layer. Forming a second semiconductor layer having a non-absorbing region with a large gap;
Removing a portion of the second semiconductor layer formed on the upper surface of the first semiconductor layer;
And cleaving the second semiconductor layer to form at least one of a pair of resonator end faces. The method of manufacturing a semiconductor laser according to claim 9, wherein the step portion is formed to have a side surface inclined with respect to the upper surface of the substrate. The method for manufacturing a semiconductor laser according to claim 9, wherein the side surface of the stepped portion is formed so as to form an angle of 54.7 ° or more with respect to the upper surface of the substrate.

Images