JP2005332881A - Semiconductor light emitting element, method of manufacturing the same and optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor light emitting element which can raise light emitting characteristics by suppressing the deterioration of crystal quality of an active layer made of a GaInNAs semiconductor material when a p-type clad layer made of an AlGaAs mixed crystal is grown. <P>SOLUTION: A p-type first clad layer 16 or a cap layer 19 is formed by setting the temperature of a substrate 11, for example, to a relatively low temperature of 400°C to 650°C. As group V raw materials, an organic material having a vapor pressure at 300 K of 101324. 72 Pa (760 Torr) or less, that is, an organic metal material is preferred for use. Further, an organic material having a decomposition efficiency at 600°C or lower of 50% or more is preferred to be used. More particularly, TBAs, EAs, TEAs or TMAs, etc., are preferred. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a semiconductor light emitting device suitable as a long wavelength light emitting device, a semiconductor light emitting device by this method, and an optical module using this semiconductor light emitting device.

  Semiconductor light emitting devices that emit light with a long wavelength of 1.2 μm or more have various application fields such as optical communication systems. In particular, semiconductor light-emitting elements having an oscillation wavelength of 1.3 μm or 1.55 μm are mainly used for optical communication applications and are the core of communication technology. Currently, InP-based materials are mainly used for the active layer of such long-wavelength light-emitting elements for communication. Recently, GaInNAs-based semiconductor materials such as GaInNAs mixed crystals, GaInNAsSb mixed crystals, and GaAsNSb mixed crystals have attracted attention. . Since a GaInNAs-based semiconductor contains nitrogen (N), it is easy to increase the wave length, and can be manufactured on a GaAs substrate that can be manufactured at a low cost and with a large diameter. It is considered.

  As a semiconductor laser using such a GaInNAs-based semiconductor material, for example, an n-type cladding layer made of an AlGaAs mixed crystal, an active layer made of a GaInNAs-based semiconductor material, and a p-type cladding made of an AlGaAs mixed crystal on a GaAs substrate. The thing of the structure which laminated | stacked the layer in order is known.

  GaInNAs-based semiconductor materials are also applied to VCSELs (Vertical Cavity Surface Emitting Lasers). For example, AlGaAs mixed crystal layers and GaAs mixed crystal layers are alternately formed on a GaAs substrate. There is a configuration in which a large number of n-type multilayer reflective films, an active layer made of a GaInNAs-based semiconductor material, and a p-type multilayer reflective film in which a large number of AlGaAs mixed crystal layers and GaAs mixed crystal layers are alternately stacked are sequentially stacked.

  As a method for growing a GaInNAs-based semiconductor material, an MBE (Molecular Beam Epitaxy) method, an MOCVD (Metal Organic Chemical Vapor Deposition) method, or the like is used. Among these, the MOCVD method uses TMAl (trimethylaluminum) or TMGa (trimethyl) as a Group 3B element raw material (hereinafter referred to as “Group III raw material”) or a Group 5B element raw material (hereinafter referred to as “Group V raw material”). This is a technique for forming a thin film by using organometallic raw materials such as gallium) and thermally decomposing these raw materials.

When a p-type cladding layer or a p-type multilayer reflective film is formed by MOCVD, arsine (AsH ₃ ) is often used as a group V raw material and is often grown at a high temperature of 650 ° C. or higher (for example, Patent Document 1). reference.). This is because the p-type cladding layer or p-type multilayer reflective film containing aluminum has better crystal quality when grown at as high a temperature as possible. Moreover, since the decomposition efficiency of arsine is extremely high at 650 ° C. or higher, the raw material efficiency can be increased. Arsine is widely used because of its high purity and easy handling.
JP 2002-208755 A JP 2003-282444 A JP-A-8-32181 GB Stringfellow, Fundamental aspects of vapor growth and epitaxy, “Journal of Crystal Growth” (Netherlands), Elsevier, 1991, 115, p. 1-11

  However, it is known that the crystal quality of GaInNAs semiconductor materials changes when annealed. In general, when annealing is performed, the PL (Photo Luminescence) intensity is once recovered, but it is known that the crystal quality is deteriorated and the PL intensity is lowered by annealing for a long time. For this reason, if a long growth process is performed at a high temperature after forming an active layer made of a GaInNAs-based semiconductor, the crystal quality of the active layer may be degraded.

  In order to avoid such a problem, it is conceivable to slightly lower the growth temperature of the p-type cladding layer or the p-type multilayer reflective film. However, as described in Non-Patent Document 1, for example, the decomposition efficiency of arsine decreases rapidly at 650 ° C. or lower, about 50% at 600 ° C., and almost zero at 450 ° C. For this reason, there is a problem that the raw material efficiency is extremely deteriorated in a low temperature region of 650 ° C. or lower.

  Furthermore, in the case of VCSEL, since the total thickness of the p-type multilayer reflective film is as thick as about 3 μm, the growth time is further increased, and the possibility that the crystal quality of the active layer is deteriorated is increased.

  In addition, when a GaInNAs-based semiconductor material is used for the active layer, the oscillation wavelength is shortened when the annealing temperature is increased. For this reason, there was a problem that it would be disadvantageous for longer waves.

  The present invention has been made in view of such problems, and its object is to provide an active material made of a GaInNAs semiconductor material when growing a p-type cladding layer or a p-type multilayer reflective film made of AlGaAs mixed crystal, that is, an aluminum-containing layer. An object of the present invention is to provide a method for manufacturing a semiconductor light-emitting element, a semiconductor light-emitting element, and an optical module that can suppress the deterioration of crystal quality of the layer, that is, the nitrogen-containing layer, and improve the light emission characteristics.

  A method of manufacturing a semiconductor light emitting device according to the present invention includes a GaAs-based material including at least one of gallium (Ga) of group 3B elements and at least arsenic (As) and nitrogen (N) of group 5B elements on one side of a substrate. A step of forming a nitrogen-containing layer made of a III-V compound semiconductor, and at least aluminum (Al) of the group 3B elements and gallium (Ga) and at least arsenic (As) of the group 5B elements on the nitrogen-containing layer. And a step of forming an aluminum-containing layer made of a GaAs-based III-V group compound semiconductor at a temperature of 400 ° C. or higher and 650 ° C. or lower. At this time, it is preferable to use an organic material having a decomposition efficiency of 50% or more at 600 ° C. or lower as a material for the Group 5B element for forming the nitrogen-containing layer and the aluminum-containing layer.

  A semiconductor light-emitting device according to the present invention includes a substrate and a GaAs-based material including at least one of gallium (Ga) of group 3B elements and at least arsenic (As) and nitrogen (N) of group 5B elements on one surface side of the substrate. A nitrogen-containing layer made of a group III-V compound semiconductor, and on the nitrogen-containing layer, at least aluminum (Al) and gallium (Ga) among the group 3B elements and at least arsenic (As) among the group 5B elements are included. And an aluminum-containing layer made of a GaAs III-V group compound semiconductor and formed at a temperature of 400 ° C. or higher and 650 ° C. or lower.

  An optical module according to the present invention includes the above-described semiconductor light emitting device according to the present invention on a substrate.

  According to the method for manufacturing a semiconductor light emitting device of the present invention or the semiconductor light emitting device of the present invention, after forming a nitrogen-containing layer made of a GaAs-based III-V compound semiconductor containing nitrogen (N), In addition, since an aluminum-containing layer made of a GaAs III-V group compound semiconductor containing aluminum (Al) is formed at a relatively low temperature of 400 ° C. or higher and 650 ° C. or lower, nitrogen is grown when the aluminum-containing layer is grown. It is possible to suppress the deterioration of the crystal quality of the containing layer due to a high temperature and improve the light emission characteristics.

  In particular, if an organic material having a decomposition efficiency of 50% or higher at 600 ° C. or lower is used as the 5B group element raw material for forming the aluminum-containing layer, the aluminum-containing layer can be grown efficiently even at low temperatures. it can.

  According to the optical module of the present invention, since the semiconductor light emitting device of the present invention is provided, high performance can be obtained due to its excellent light emission characteristics.

  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 10 is used as a long-wave laser for communication. For example, an n-type cladding layer 12, a first guide layer 13, an active layer 14, a second guide layer 15, and a p-type are formed on the front side of the substrate 11. The first clad layer 16, the etching stop layer 17, the p-type second clad layer 18 and the cap layer 19 are laminated in this order. The etching stop layer 17, the p-type second cladding layer 18 and the cap layer 19 are formed as thin strip-shaped protrusions for current confinement, and limit the light emitting region of the active layer 14.

For example, the substrate 11 has a thickness in the stacking direction (hereinafter simply referred to as a thickness) of 100 μm and is made of n-type GaAs to which an n-type impurity such as silicon (Si) or selenium (Se) is added. The n-type cladding layer 12 has, for example, a thickness of 2 μm and is composed of an n-type Al _0.47 Ga _0.53 As mixed crystal to which an n-type impurity such as silicon or selenium is added.

  For example, the first guide layer 13 has a thickness of 140 nm and is made of GaAs not containing impurities.

  The active layer 14 has, for example, a DQW (Double Quantum Well) structure in which a barrier layer 14B is provided between the well layers 14A and 14C. Each of the well layers 14A and 14C has a thickness of 8 nm and is composed of a GaInNAs mixed crystal. That is, the well layers 14A and 14B of the active layer 14 are nitrogen-containing layers. The barrier layer 14B has a thickness of 18 nm, for example, and is made of GaAs.

  The second guide layer 15 has a thickness of, for example, 140 nm and is made of GaAs that does not contain impurities.

The p-type first cladding layer 16 has, for example, a thickness of 100 nm and is composed of a p-type Al _0.47 Ga _0.53 As mixed crystal to which a p-type impurity such as carbon (C) is added. That is, the p-type first cladding layer 16 is an aluminum-containing layer. For example, the etching stop layer 17 has a thickness of 100 nm and is made of p-type GaAs to which a p-type impurity such as carbon (C) is added. The p-type second cladding layer 18 has a thickness of 1.4 μm, for example, and is composed of a p-type Al _0.47 Ga _0.53 As mixed crystal to which a p-type impurity such as carbon (C) is added. That is, the p-type second cladding layer 18 is an aluminum-containing layer. The cap layer 19 has a thickness of 300 nm, for example, and is made of p-type GaAs to which a p-type impurity such as carbon (C) is added at a high concentration. The p-type first cladding layer 16, the etching stop layer 17, the p-type second cladding layer 18 and the cap layer 19 are formed at a temperature of 400 ° C. or higher and 650 ° C. or lower as will be described later.

An insulating film 20 made of, for example, silicon dioxide (SiO ₂ ) is formed on the surface and side surfaces of the p-type first cladding layer 16 or the cap layer 19. The insulating film 20 has an opening corresponding to the upper surface of the cap layer 19.

  A p-side electrode 31 is formed on the surface of the insulating film 20. The p-side electrode 31 has a structure in which, for example, a gold (Au) layer, an alloy layer of gold (Au) and germanium (Ge), and a gold (Au) layer are sequentially stacked, and an opening of the insulating film 20 is formed. And is electrically connected to the cap layer 19. An n-side electrode 32 is formed on the back side of the substrate 11. The n-side electrode 32 has a structure in which, for example, a titanium (Ti) layer, a platinum (Pt) layer, and a gold (Au) layer are sequentially laminated and alloyed by heat treatment, and is electrically connected to the substrate 11. Yes.

  Further, in the semiconductor laser 10, a pair of side surfaces facing each other in the resonator direction are resonator end faces, and a pair of reflecting mirror films (not shown) are formed on the pair of resonator end faces. The reflectance is adjusted so that one of the pair of reflecting mirror films has a low reflectance and the other has a high reflectance. Thereby, the light generated in the active layer 14 is amplified by reciprocating between the pair of reflecting mirror films so as to be emitted from the reflecting mirror film on the low reflectance side as a laser beam in a direction perpendicular to the stacking direction. It has become.

  The semiconductor laser 10 can be manufactured as follows, for example.

  First, for example, a substrate 11 made of the above-described thickness and material is prepared, and an n-type cladding layer 12 or a cap layer 19 is sequentially grown on the front side of the substrate 11. The growth process is performed by, for example, the MOCVD method, and the temperature of the substrate 11 (growth temperature) and the V group raw material to be used are varied as follows according to the constituent material of each layer.

  That is, the n-type cladding layer 12 and the first guide layer 13 are sequentially grown on the front side of the substrate 11. At this time, the growth temperature is set to about 750 ° C., for example, and arsine is used as the group V material.

  Next, an active layer 14 that is a nitrogen-containing layer and a second guide layer 15 are sequentially formed on the first guide layer 13. At this time, the growth temperature is, for example, 500 ° C., and, for example, TBAs (tertiary butyl arsine) is used as the group V raw material.

  Subsequently, a p-type first cladding layer 16 that is an aluminum-containing layer, an etching stop layer 17, a p-type second cladding layer 18 that is an aluminum-containing layer, and a cap layer 19 are sequentially formed on the second guide layer 15. . The carrier concentration of the p-type first cladding layer 16 to the cap layer 19 is adjusted by auto-doping of carbon from the organometallic material used.

  The p-type first cladding layer 16 to the cap layer 19 are formed at a relatively low temperature of, for example, 400 ° C. or more and 650 ° C. or less. This is because the decomposition efficiency of the group V raw material is generally insufficient at a temperature lower than 400 ° C., and the crystal quality of the active layer 14 may deteriorate at a temperature higher than 650 ° C. Thereby, in this Embodiment, when growing the p-type 1st clad layer 16 thru | or the cap layer 19, it can suppress that the crystal quality of the active layer 14 deteriorates by high temperature.

  Further, it is more preferably 400 ° C. or more and 600 ° C. or less, more preferably 450 ° C. or more and 600 ° C. or less, and most preferably 550 ° C. to 600 ° C.

  At this time, it is preferable to use an organic material having a vapor pressure of 101324.72 Pa (760 Torr) or less at 300 K, that is, an organic metal material, as the group V raw material. In addition, it is preferable to use an organic material having a decomposition efficiency of 50% or more at 600 ° C. or lower. This is because the raw material efficiency can be improved even at low temperatures. As such an organic material, TBAs, EAs (monoethylarsine), TEAs (triethylarsine), TMAs (trimethylarsine), or the like is preferable. In addition to carbon contained in Group III materials such as TMAl and TMGa, carbon contained in these organic Group V materials is also taken into the crystal, so that the carrier concentration of the p-type first cladding layer 16 or cap layer 19 is further increased. This is because it can be increased (for example, see Patent Document 2). Further, as shown in FIG. 2, the carrier concentration of the p-type first cladding layer 16 to the cap layer 19 can be easily controlled by adjusting the V / III ratio. Furthermore, since nitrogen and hydrogen (H) have a strong bonding force, the amount of hydrogen radicals generated during growth is smaller in the organic group V material than in arsine, and the amount of hydrogen taken into the active layer 14 is reduced. Because it can. Here, the V / III ratio refers to the molar flow rate ratio between the Group V source gas and the Group III source gas.

FIG. 2 shows the experimental results of examining the relationship between the V / III ratio and the carrier concentration of the p-type Al _0.47 Ga _0.53 As mixed crystal. The growth temperature is 600 ° C. and the group V material is TBAs. Was used. In FIG. 2, a carrier concentration of 1 × 10 ¹⁸ cm ⁻³ is obtained at a V / III ratio of about 8, and it can be seen that the carrier concentration can be easily reduced by increasing the V / III ratio. Further, if the aluminum composition is increased, the carrier concentration can be further increased.

After forming the p-type first cladding layer 16 to the cap layer 19, annealing is performed at 600 ° C. for 2 minutes, for example, in a nitrogen (N ₂ ) atmosphere to improve the crystal quality of the active layer 14 and remove hydrogen.

  After annealing, a mask (not shown) is formed on the cap layer 19, and the cap layer 19, the p-type second cladding layer 18 and the etching stop layer 17 are selectively removed by using this mask, for example, by etching. Thus, a thin strip-shaped protrusion is formed, and a mask (not shown) is removed.

  After removing the mask, the insulating film 20 made of the above-described material is formed over the entire surface of the substrate 11 by, for example, vapor deposition. The insulating film 20 is selectively removed by, for example, photolithography and etching, and the upper surface of the cap layer 19 is removed. An opening is formed in

  After the opening is formed in the insulating film 20, titanium, platinum and gold are sequentially laminated on the entire upper surface of the substrate 11 by, for example, a vacuum deposition method and alloyed to form the p-side electrode 31. After the p-side electrode 31 is formed, the substrate 11 is ground to a thickness of, for example, about 100 μm. Similarly to the p-side electrode 31, gold, AuGe is formed on the entire surface on the opposite side of the substrate 11 by, for example, vacuum deposition. Then, the n-side electrode 32 is formed by sequentially laminating and alloying them.

  After the n-side electrode 32 and the p-side electrode 31 are formed, the substrate 11 is adjusted to a predetermined size, and a reflecting mirror film (not shown) is formed on a pair of resonator end faces facing in the resonator length direction. Thereby, the semiconductor laser 10 shown in FIG. 1 is completed.

  In this semiconductor laser 10, when a predetermined voltage is applied between the n-side electrode 32 and the p-side electrode 31, a current is injected into the active layer 14 and light emission occurs due to electron-hole recombination. This light is reflected by a pair of reflecting mirror films (not shown), reciprocates between them to generate laser oscillation, and is emitted to the outside as a laser beam. Here, the p-type first cladding layer 16 and the p-type second cladding layer 18, which are aluminum-containing layers, the etching stop layer 17, and the cap layer 19 are formed at a relatively low temperature of 400 ° C. or more and 650 ° C. or less. Therefore, when the p-type first cladding layer 16 to the cap layer 19 are grown, the crystal quality of the well layers 14A and 14C of the active layer 14 is suppressed from deteriorating due to a high temperature. Therefore, the light emission characteristics are improved.

(Optical module)
FIG. 3 schematically shows the configuration of an optical module including such a semiconductor laser 10. The optical module 100 is used as an FEM (front end module) that converts an optical signal and an electric signal in a high-speed optical communication system, and includes a transmission unit 110 and a reception unit 120 on a base 101. Yes. Fibers 130 and 140 are connected to the transmission unit 110 and the reception unit 120 via connectors (not shown), respectively.

  The transmission unit 110 includes, for example, the semiconductor laser 10 described above and a driver 112 that drives the semiconductor laser 10. As the driver 112, a known driver IC (Integrated Circuit) can be used.

  The receiving unit 120 is a general unit including, for example, a photoelectric conversion element (photodiode) 121 and an amplifier 122 such as a TIA (transimpedance amplifier) or LIA (limiting impedance amplifier).

  In the optical module 100, in the transmission unit 110, the semiconductor laser 10 is driven by the driver 112 based on the electric signal S1 supplied from the outside, and the optical signal P1 is transmitted through the fiber 130. In the receiving unit 120, the optical signal P2 supplied via the fiber 140 is incident on the photoelectric conversion element 121 and converted into an electric signal. The electric signal is amplified by the amplifier 122, and necessary conversion processing is applied. And output to the outside as an electrical signal S2. Here, since the optical module 100 includes the semiconductor laser 10 of the present embodiment, high performance can be obtained due to the excellent light emission characteristics of the semiconductor laser 10.

  Thus, in the present embodiment, the p-type first cladding layer 16 and the p-type second cladding layer 18, which are aluminum-containing layers, the etching stop layer 17, and the cap layer 19 are compared at 400 ° C. or more and 650 ° C. or less. Since the p-type first cladding layer 16 to the cap layer 19 are grown, the crystal quality of the well layers 14A and 14C of the active layer 14 is prevented from deteriorating due to a high temperature, so that light emission is achieved. Characteristics can be improved. Therefore, the performance of the optical module 100 using the semiconductor laser 10 is also improved.

(Second Embodiment)
FIG. 4 shows the structure of a semiconductor laser 40 according to the second embodiment of the present invention. The semiconductor laser 40 is a VCSEL. For example, an n-type multilayer reflective film 42, a first guide layer 43, an active layer 44, a second guide layer 45, a current confinement layer 46, and a p-type multilayer reflective are provided on the front side of the substrate 41. The film 47 and the cap layer 48 are stacked in this order. The first GaAs layer 43 or the cap layer 48 is a substantially cylindrical mesa region, and the light emission region of the active layer 44 is limited by the current confinement layer 46.

The substrate 41 has, for example, a thickness of about 150 μm and is made of n-type GaAs to which an n-type impurity such as silicon or selenium is added. The n-type multilayer reflective film 42 has, for example, a thickness of about 90 nm, an n-type Al _0.9 Ga _0.1 As mixed crystal layer to which an n-type impurity such as silicon or selenium is added, and a thickness of about 80 nm. Alternatively, it is a DBR (Distributed Bragg Reflector) mirror having a structure in which, for example, 35 pairs of n-type GaAs layers doped with an n-type impurity such as selenium are alternately stacked. A graded layer (not shown) having a thickness of about 20 nm and a linearly changing composition is inserted at the interface of the n-type multilayer reflective film 42 to reduce resistance.

  The first guide layer 43 has a thickness of, for example, about 170 nm and is made of GaAs that does not contain impurities.

  The active layer 44 has, for example, a TQW (Triple Quantum Well) structure in which a barrier layer is provided between well layers. Each well layer has, for example, a thickness of 8 nm and is composed of a GaInNAs mixed crystal. That is, the well layer of the active layer 14 is a nitrogen-containing layer. Each barrier layer has a thickness of 10 nm, for example, and is made of GaAs.

  The second guide layer 45 has a thickness of, for example, about 170 nm and is made of GaAs that does not contain impurities. Note that the thickness of the active region (the region where light resonates) including the active layer 44 is controlled based on the oscillation wavelength λ.

  The current confinement layer 46 has, for example, an annular high resistance region 46B obtained by oxidizing aluminum arsenide around a low resistance region 46A made of aluminum arsenide (AlAs), and the current is confined only in the low resistance region 46A. It has come to be. A region of the active layer 44 corresponding to the low resistance region 46A is a light emitting region.

The p-type multilayer reflective film 47 has a thickness of about 90 nm, for example, a p-type Al _0.9 Ga _0.1 As mixed crystal layer to which a p-type impurity such as carbon is added, and a thickness of about 80 nm. The DBR mirror has a structure in which, for example, 30 pairs of p-type GaAs layers doped with p-type impurities are alternately stacked. That is, the p-type multilayer reflective film 45 is an aluminum-containing layer. The cap layer 48 has a thickness of 80 nm, for example, and is made of p-type GaAs to which a p-type impurity such as carbon is added at a high concentration. The p-type multilayer reflective film 47 and the cap layer 48 are formed at a temperature of 400 ° C. or higher and 650 ° C. or lower, as will be described later.

An insulating film 49 made of, for example, silicon dioxide (SiO ₂ ) is formed on the surface and side surfaces of the n-type multilayer reflective film 42 or the cap layer 48. The insulating film 49 is provided with an opening corresponding to the upper surface of the cap layer 48. A p-side electrode 51 is formed on the surface of the insulating film 49, and an n-side electrode 52 is provided on the back side of the substrate 41. The p-side electrode 51 and the n-side electrode 52 are the same as the p-side electrode 31 and n in the semiconductor laser 10 of the first embodiment except that the p-side electrode 51 is provided with an opening for extracting light. The configuration is the same as that of the side electrode 32.

  The semiconductor laser 40 can be manufactured as follows, for example.

  First, for example, a substrate 41 made of the above-described thickness and material is prepared, and an n-type multilayer reflective film 42 or a cap layer 48 is sequentially grown on the front side of the substrate 41. The growth process is performed by, for example, the MOCVD method, and the temperature of the substrate 41 and the V group raw material to be used are varied as follows according to the constituent material of each layer.

  That is, the n-type multilayer reflective film 42 and the first guide layer 43 are sequentially grown on the front side of the substrate 41. At this time, the temperature of the substrate 41 is about 750 ° C., for example, and arsine is used as the V group material. The above-described graded layer (not shown) is inserted at the interface of the n-type multilayer reflective film 42 in order to reduce the resistance.

  Next, an active layer 44 that is a nitrogen-containing layer, a second guide layer 45, and an AlAs layer (not shown) for forming the current confinement layer 46 are sequentially formed on the first guide layer 43. At this time, the temperature of the substrate 41 is, for example, 500 ° C., and, for example, TBAs is used as the group V material.

  Subsequently, a p-type multilayer reflective film 47 that is an aluminum-containing layer and a cap layer 48 are sequentially formed on the AlAs layer for forming the current confinement layer 46. The carrier concentrations of the p-type multilayer reflective film 47 and the cap layer 48 are adjusted by auto-doping carbon from the organometallic material used.

  The p-type multilayer reflective film 47 and the cap layer 48 have a relatively low temperature of the substrate 41 of, for example, 400 ° C. or more and 650 ° C. or less, as with the p-type first cladding layer 16 to the cap layer 19 in the first embodiment. Form as temperature. This is because the decomposition efficiency of the group V raw material is generally insufficient at a temperature lower than 400 ° C., and the crystal quality of the active layer 44 may be deteriorated at a temperature higher than 650 ° C. Thereby, in this Embodiment, when growing the p-type multilayer reflective film 47 and the cap layer 48, it can suppress that the crystal quality of the active layer 44 deteriorates by high temperature.

  Further, similarly to the p-type first cladding layer 16 or the cap layer 19 in the first embodiment, it is more preferably 400 ° C. or more and 600 ° C. or less, more preferably 450 ° C. or more and 600 ° C. or less, and further preferably 550 ° C. It is most preferable if it is set to about 600 ° C.

At this time, as the group V raw material, an organic material having a vapor pressure of 101324.72 Pa (760 Torr) or less at 300 K, that is, an organic metal, as in the p-type first cladding layer 16 to the cap layer 19 in the first embodiment. It is preferable to use a material. Moreover, it is preferable to use an organic material having a decomposition efficiency of 50% or more at 600 ° C. or lower. This is because the raw material efficiency can be improved even at low temperatures. As such an organic material, TBAs, EAs, TEAs, TMAs and the like are preferable. In addition to carbon contained in Group III materials such as TMAl and TMGa, carbon contained in these organic Group V materials is also taken into the crystal, so that the carrier concentration of the p-type multilayer reflective film 47 and the cap layer 48 is further increased. It is because it can do (for example, refer patent document 3). Further, as described with reference to FIG. 2 in the first embodiment, the carrier concentration of the p-type multilayer reflective film 47 and the cap layer 48 can be easily controlled by adjusting the V / III ratio. Because. In particular, in the p-type multilayer reflective film 47, an increase in resistance due to band discontinuity at the heterointerface becomes a serious problem, and it is necessary to reduce the resistance by inserting a high doping layer having a high carrier concentration of 10 ¹⁹ cm ^−3. However, by using an organic group V raw material, a layer having a high aluminum composition can be doped at a high concentration of 10 ¹⁹ cm ⁻³ by controlling the V / III ratio. Furthermore, since nitrogen and hydrogen (H) have a strong binding force, the amount of hydrogen radicals generated during growth is smaller in the organic group V material than in arsine, and the amount of hydrogen taken into the active layer 44 is reduced. be able to.

After the p-type multilayer reflective film 47 and the cap layer 48 are formed, annealing is performed at 600 ° C. for 2 minutes, for example, in a nitrogen (N ₂ ) atmosphere to improve the crystal quality of the active layer 44 and remove hydrogen.

  After the annealing, a mask (not shown) is formed on the cap layer 48, and AlAs for forming the cap layer 48, the p-type multilayer reflective film 47, and the current confinement layer 46 by using this mask, for example, by etching. The layer, the second guide layer 45, the active layer 44, and the first guide layer 43 are selectively removed to form a substantially cylindrical mesa region, and a mask (not shown) is removed.

  After removing the mask, the current confinement layer having the low resistance region 46A and the high resistance region 46B is obtained by, for example, heating in water vapor to oxidize the AlAs layer exposed in the mesa region in a ring shape from the periphery toward the center. 46 is formed.

  After forming the current confinement layer 46, the insulating film 49 made of the above-described material is formed over the entire surface of the substrate 41 by, for example, vapor deposition, and the insulating film 49 is selectively removed by, for example, photolithography and etching, and the cap An opening is formed on layer 48.

  After the opening is formed in the insulating film 49, the p-side electrode 51 and the n-side electrode 52 are formed in the same manner as the p-side electrode 31 and the n-side electrode 32 of the first embodiment. Thereby, the semiconductor laser 40 shown in FIG. 4 is completed.

  In this semiconductor laser 40, when a predetermined voltage is applied between the n-side electrode 52 and the p-side electrode 51, the drive current supplied from the p-side electrode 51 is activated after the current confinement is confined by the current confinement layer 46. Light is emitted by being injected into the layer 44 and electron-hole recombination. This light is reflected by the n-type multilayer reflective film 42 and the p-type multilayer reflective film 47, reciprocates between them to generate laser oscillation, and is emitted from the opening of the p-side electrode 51 to the outside as a laser beam. Here, the p-type multilayer reflective film 47, which is an aluminum-containing layer, and the cap layer 48 are formed at a relatively low temperature of 400 ° C. or higher and 650 ° C. or lower. It is suppressed that the crystal quality of the well layer of the active layer 44 deteriorates due to a high temperature during the growth. Therefore, the light emission characteristics are improved.

  This semiconductor laser 40 can constitute the optical module 100 in the same manner as the semiconductor laser 10 of the first embodiment.

  Thus, in the present embodiment, the p-type multilayer reflective film 47 that is an aluminum-containing layer and the cap layer 48 are formed at a relatively low temperature of 400 ° C. or higher and 650 ° C. or lower. When the film 47 and the cap layer 48 are grown, the crystal quality of the well layer of the active layer 44 can be prevented from deteriorating due to high temperature, and the light emission characteristics can be improved. Therefore, the performance of the optical module 100 using the semiconductor laser 40 is also improved.

  Furthermore, specific examples of the present invention will be described.

(Example 1)
A semiconductor laser was fabricated in the same manner as in the first embodiment. At that time, the p-type first cladding layer 16 to the cap layer 19 were formed using TBAs as a group V material at a growth temperature of 600 ° C., and then annealed at 600 ° C. for 2 minutes in a nitrogen atmosphere. . About the obtained semiconductor laser, PL wavelength and PL intensity were measured. The results are shown in FIGS. 5 and 6, respectively.

(Example 2)
A semiconductor laser was fabricated in the same manner as in Example 1 except that the growth temperature of the p-type first cladding layer or cap layer was 650 ° C. and arsine was used as the group V material. For the obtained semiconductor laser of Example 2, the PL wavelength and PL intensity were measured in the same manner as in Example 1. The results are also shown in FIGS.

(Comparative example)
A semiconductor laser was fabricated in the same manner as in Example 1 except that the growth temperature of the p-type first cladding layer or cap layer was 700 ° C. and arsine was used as the group V material. With respect to the obtained semiconductor laser of the comparative example, the PL wavelength and the PL intensity were measured in the same manner as in Example 1. The results are also shown in FIGS.

  As can be seen from FIGS. 5 and 6, according to Examples 1 and 2, both PL wavelength and PL intensity were better than those of the comparative example. On the other hand, in the comparative example, the PL wavelength was significantly shortened, and the PL intensity was also reduced. This is presumably because in the comparative example, the growth temperature in the growth process of the p-type first cladding layer or cap layer was as high as 700 ° C., so that the PL wavelength was shortened due to the annealing effect on the active layer. As for the PL intensity, it is necessary to increase the nitrogen (N) composition in order to increase the normal wave length. That is, when the PL wavelength of Example 1 is matched with the comparative example, the PL wavelength of Example 1 becomes strong. This is considered to indicate that the crystal quality of the GaInNAs mixed crystal constituting the well layer deteriorated in the comparative example.

  That is, the p-type first cladding layer 16 and the p-type second cladding layer 18, which are aluminum-containing layers, the etching stop layer 17, and the cap layer 19 are formed at a relatively low growth temperature of 600 ° C. to 650 ° C. Then, when growing the p-type first cladding layer 16 to the cap layer 19, the crystal quality of the well layers 14A and 14C of the active layer 14 is suppressed from being deteriorated by a high temperature, and the shortening of the PL wavelength is prevented. It was found that the PL intensity can be improved.

  Furthermore, in Example 2, the PL wavelength was slightly shorter than that in Example 1. This is considered to be because in Example 2, the growth temperature of the p-type first cladding layer 16 to cap layer 19 was slightly high at 650 ° C., so that the PL wavelength was shortened by the annealing effect on the active layer 14. It is done. That is, if the p-type first cladding layer 16 to the cap layer 19 are formed at a low growth temperature around 600 ° C., the shortening of the PL wavelength can be more effectively suppressed, which is advantageous for the longer wave. I found out.

  The present invention has been described with reference to the embodiments and examples. However, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, the material and thickness of each layer described in the above embodiments and examples, or the film formation method and film formation conditions are not limited, and other materials and thicknesses may be used. It is good also as a film | membrane method and film-forming conditions.

  Further, for example, in the above-described embodiments and examples, the configuration of the semiconductor laser has been specifically described, but it is not necessary to include all layers, and other layers may be further included.

  The semiconductor light emitting device and the manufacturing method thereof according to the present invention are suitable for, for example, a communication laser used as a light source for optical fiber communication or optical wiring and the manufacture thereof. Moreover, since the optical module according to the present invention can constitute a low-cost system, it can be expected to be applied to consumer equipment.

It is sectional drawing showing the structure of the semiconductor laser which concerns on the 1st Embodiment of this invention. Is a diagram illustrating an experimental result of examining the relationship between the V / III ratio and the p-type Al _0.47 Ga _0.53 As the carrier concentration of the mixed crystal. It is a figure which represents typically the structure of the optical module provided with 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 a figure showing the result of the Example and comparative example of this invention. It is a figure showing the result of the Example and comparative example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,40 ... Semiconductor laser, 11, 41 ... Substrate, 12 ... N-type cladding layer, 13 ... First guide layer, 14, 44 ... Active layer (nitrogen-containing layer), 15 ... Second guide layer, 16 ... p-type First cladding layer (aluminum-containing layer), 17 ... etching stop layer, 18 ... p-type second cladding layer (aluminum-containing layer), 19,48 ... cap layer, 20,49 ... insulating film, 31,51 ... p side Electrode, 32, 52 ... n-side electrode, 42 ... n-type multilayer reflective film, 43 ... first guide layer, 45 ... second guide layer, 46 ... current confinement layer, 47 ... p-type multilayer reflective film (aluminum-containing layer)

Claims (19)

A nitrogen-containing layer made of a GaAs III-V compound semiconductor containing at least gallium (Ga) of 3B group elements and at least arsenic (As) and nitrogen (N) of 5B group elements on one surface side of the substrate Forming a step;
Aluminum containing a GaAs-based III-V compound semiconductor containing at least aluminum (Al) and gallium (Ga) of 3B group elements and at least arsenic (As) of 5B group elements on the nitrogen-containing layer. Forming the layer at a temperature of 400 ° C. or higher and 650 ° C. or lower. The substrate has a laminated structure of a first conductive type multilayer reflective film, an active layer and a second conductive type multilayer reflective film, the active layer is the nitrogen-containing layer, and the second conductive type multilayer reflective film is The method for producing a semiconductor light-emitting element according to claim 1, wherein the layer is an aluminum-containing layer. The substrate has a laminated structure of a first conductivity type cladding layer, an active layer, and a second conductivity type cladding layer, the active layer is the nitrogen-containing layer, and the second conductivity type cladding layer contains the aluminum. It is a layer. The manufacturing method of the semiconductor light-emitting device of Claim 1 characterized by the above-mentioned. The method for manufacturing a semiconductor light-emitting element according to claim 1, wherein an organic material having a decomposition efficiency of 50% or higher at 600 ° C or lower is used as a material for a Group 5B element for forming the aluminum-containing layer. 2. The method of manufacturing a semiconductor light emitting element according to claim 1, wherein an organic material having a vapor pressure of 101324.72 Pa (760 Torr) or less at 300 K is used as a Group 5B element material for forming the aluminum-containing layer. The method for manufacturing a semiconductor light-emitting element according to claim 1, wherein carbon (C) is contained as an impurity in the aluminum-containing layer. The method for manufacturing a semiconductor light-emitting element according to claim 1, wherein the nitrogen-containing layer is made of a GaInNAs mixed crystal. The method for manufacturing a semiconductor light-emitting element according to claim 1, wherein the nitrogen-containing layer is made of a GaInNAsSb mixed crystal. The method for manufacturing a semiconductor light-emitting element according to claim 1, wherein the nitrogen-containing layer is made of a GaAsSbN mixed crystal. A substrate,
Nitrogen containing a GaAs III-V compound semiconductor containing at least gallium (Ga) of 3B group elements and at least arsenic (As) and nitrogen (N) of 5B group elements on one surface side of the substrate Layers,
The nitrogen-containing layer is composed of a GaAs-based III-V group compound semiconductor containing at least aluminum (Al) and gallium (Ga) among the group 3B elements and at least arsenic (As) among the group 5B elements, And an aluminum-containing layer formed at a temperature of 400 ° C. or higher and 650 ° C. or lower. The substrate has a laminated structure of a first conductive type multilayer reflective film, an active layer and a second conductive type multilayer reflective film, the active layer is the nitrogen-containing layer, and the second conductive type multilayer reflective film is The semiconductor light emitting device according to claim 10, wherein the semiconductor layer is the aluminum-containing layer. The substrate has a laminated structure of a first conductivity type cladding layer, an active layer, and a second conductivity type cladding layer, the active layer is the nitrogen-containing layer, and the second conductivity type cladding layer contains the aluminum. The semiconductor light emitting device according to claim 10, wherein the semiconductor light emitting device is a layer. The semiconductor light-emitting element according to claim 10, wherein the aluminum-containing layer contains carbon (C) as an impurity. The semiconductor light-emitting element according to claim 10, wherein the nitrogen-containing layer is made of a GaInNAs mixed crystal. The semiconductor light-emitting element according to claim 10, wherein the nitrogen-containing layer is composed of a GaInNAsSb mixed crystal. The semiconductor light-emitting element according to claim 10, wherein the nitrogen-containing layer is composed of a GaAsSbN mixed crystal. An optical module comprising a semiconductor light emitting element on a substrate,
The semiconductor light emitting element is
A substrate,
Nitrogen containing a GaAs III-V compound semiconductor containing at least gallium (Ga) of 3B group elements and at least arsenic (As) and nitrogen (N) of 5B group elements on one surface side of the substrate Layers,
The nitrogen-containing layer is composed of a GaAs-based III-V group compound semiconductor containing at least aluminum (Al) and gallium (Ga) among the group 3B elements and at least arsenic (As) among the group 5B elements, And an aluminum-containing layer formed at a temperature of 400 ° C. or higher and 650 ° C. or lower. The semiconductor light emitting device has a laminated structure of a first conductive type multilayer reflective film, an active layer, and a second conductive type multilayer reflective film on the substrate, wherein the active layer is the nitrogen-containing layer, The optical module according to claim 17, wherein the conductive multilayer reflective film is the aluminum-containing layer. The semiconductor light emitting device has a laminated structure of a first conductivity type cladding layer, an active layer and a second conductivity type cladding layer on the substrate, the active layer is the nitrogen-containing layer, and the second conductivity type. The optical module according to claim 17, wherein the clad layer is the aluminum-containing layer.

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