WO2024070351A1 - 窒化物系半導体発光素子 - Google Patents

窒化物系半導体発光素子 Download PDF

Info

Publication number
WO2024070351A1
WO2024070351A1 PCT/JP2023/030351 JP2023030351W WO2024070351A1 WO 2024070351 A1 WO2024070351 A1 WO 2024070351A1 JP 2023030351 W JP2023030351 W JP 2023030351W WO 2024070351 A1 WO2024070351 A1 WO 2024070351A1
Authority
WO
WIPO (PCT)
Prior art keywords
layer
nitride
intermediate layer
based semiconductor
type intermediate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2023/030351
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
真治 吉田
徹 高山
貴大 岡口
昇 井上
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nuvoton Technology Corp Japan
Original Assignee
Nuvoton Technology Corp Japan
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nuvoton Technology Corp Japan filed Critical Nuvoton Technology Corp Japan
Priority to CN202380068493.XA priority Critical patent/CN119999032A/zh
Priority to EP23871592.4A priority patent/EP4597766A4/en
Priority to JP2024549881A priority patent/JPWO2024070351A1/ja
Publication of WO2024070351A1 publication Critical patent/WO2024070351A1/ja
Priority to US19/083,979 priority patent/US20250239836A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
    • H10H20/80—Constructional details
    • H10H20/81—Bodies
    • H10H20/822—Materials of the light-emitting regions
    • H10H20/824—Materials of the light-emitting regions comprising only Group III-V materials, e.g. GaP
    • H10H20/825—Materials of the light-emitting regions comprising only Group III-V materials, e.g. GaP containing nitrogen, e.g. GaN
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/32—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures
    • H01S5/321—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures having intermediate bandgap layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
    • H01S5/2004—Confining in the direction perpendicular to the layer structure
    • H01S5/2009—Confining in the direction perpendicular to the layer structure by using electron barrier layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
    • H01S5/2004—Confining in the direction perpendicular to the layer structure
    • H01S5/2018—Optical confinement, e.g. absorbing-, reflecting- or waveguide-layers
    • H01S5/2031—Optical confinement, e.g. absorbing-, reflecting- or waveguide-layers characterized by special waveguide layers, e.g. asymmetric waveguide layers or defined bandgap discontinuities
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
    • H01S5/22—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers having a ridge or stripe structure
    • H01S5/2202—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers having a ridge or stripe structure by making a groove in the upper laser structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/305—Structure or shape of the active region; Materials used for the active region characterised by the doping materials used in the laser structure
    • H01S5/3054—Structure or shape of the active region; Materials used for the active region characterised by the doping materials used in the laser structure p-doping
    • H01S5/3063—Structure or shape of the active region; Materials used for the active region characterised by the doping materials used in the laser structure p-doping using Mg
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/32—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures
    • H01S5/3211—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures characterised by special cladding layers, e.g. details on band-discontinuities
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/32—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures
    • H01S5/3211—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures characterised by special cladding layers, e.g. details on band-discontinuities
    • H01S5/3213—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures characterised by special cladding layers, e.g. details on band-discontinuities asymmetric clading layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/32—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures
    • H01S5/323—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser
    • H01S5/32308—Structure or shape of the active region; Materials used for the active region comprising PN junctions, e.g. hetero- or double- heterostructures in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser emitting light at a wavelength less than 900 nm
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
    • H01S5/343—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser
    • H01S5/34333—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
    • H01S5/343—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser
    • H01S5/34346—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser characterised by the materials of the barrier layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
    • H10H20/042—Superluminescent diodes
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
    • H10H20/80—Constructional details
    • H10H20/81—Bodies
    • H10H20/816—Bodies having carrier transport control structures, e.g. highly-doped semiconductor layers or current-blocking structures
    • H10H20/8162—Current-blocking structures
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
    • H10H20/80—Constructional details
    • H10H20/81—Bodies
    • H10H20/822—Materials of the light-emitting regions
    • H10H20/824—Materials of the light-emitting regions comprising only Group III-V materials, e.g. GaP
    • H10H20/825—Materials of the light-emitting regions comprising only Group III-V materials, e.g. GaP containing nitrogen, e.g. GaN
    • H10H20/8252—Materials of the light-emitting regions comprising only Group III-V materials, e.g. GaP containing nitrogen, e.g. GaN characterised by the dopants

Definitions

  • This disclosure relates to nitride-based semiconductor light-emitting devices.
  • nitride-based semiconductor light-emitting elements such as nitride-based semiconductor laser elements that emit light in the ultraviolet region are known (for example, Patent Document 1, etc.).
  • Light in the ultraviolet region has greater energy than visible light, and so light absorption is particularly large in light guide layers and the like that have a relatively small band gap energy.
  • the band gap energy is increased by increasing the Al composition ratio of each semiconductor layer, such as the light guide layer and cladding layer. This is intended to suppress light absorption in each semiconductor layer.
  • the present disclosure aims to solve these problems and suppress optical loss while reducing the Al composition ratio in each semiconductor layer in a nitride-based semiconductor light-emitting element that emits light in the ultraviolet range.
  • one aspect of the nitride-based semiconductor light-emitting device is a nitride-based semiconductor light-emitting device that emits light, comprising: a substrate; an N-type cladding layer that is disposed above the substrate and contains Al; an N-side optical guide layer that is disposed above the N-type cladding layer and contains Al; an active layer that is disposed above the N-side optical guide layer and contains a well layer and a barrier layer that contains Al; an electron barrier layer that is disposed above the active layer and contains Al; a P-type intermediate layer that is disposed above the electron barrier layer and contains Al; a P-side optical guide layer that is disposed above the P-type intermediate layer and contains Al; and a P-type cladding layer containing Al, which is disposed above the guide layer, the average band gap energy of the electron barrier layer is greater than the average band gap energy of the P-type cladding layer, the average band gap energy of the P-type intermediate layer
  • a nitride-based semiconductor light-emitting device that emits light, comprising: a substrate; an N-type cladding layer that is disposed above the substrate and contains Al; an N-type intermediate layer that is disposed above the N-type cladding layer and contains Al; an N-side light guide layer that is disposed above the N-type intermediate layer and contains Al; an active layer that is disposed above the N-side light guide layer and contains a well layer and a barrier layer that contains Al; a P-side light guide layer that is disposed above the active layer and contains Al; and a P-type cladding layer that is disposed above the P-side light guide layer and contains Al, wherein the average band gap energy of the N-type intermediate layer is greater than the average band gap energy of the N-side light guide layer and is smaller than the average band gap energy of the N-type cladding layer, the average impurity concentration
  • nitride-based semiconductor light-emitting element that emits light in the ultraviolet region, it is possible to reduce the Al composition ratio in each semiconductor layer while suppressing optical loss.
  • 1 is a schematic plan view showing an overall configuration of a nitride-based semiconductor light-emitting device according to a first embodiment.
  • 1 is a schematic cross-sectional view showing an overall configuration of a nitride-based semiconductor light-emitting device according to a first embodiment.
  • 4 is a schematic graph showing distribution of band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting element according to Comparative Example 1.
  • 2 is a schematic graph showing distribution of band gap energy and impurity concentration in a stacking direction of the nitride-based semiconductor light-emitting element according to the first embodiment.
  • 1 is a graph showing the extinction coefficient spectrum in an AlGaN layer.
  • FIG. 3 is a schematic cross-sectional view showing the shape of a side surface of a ridge according to the first embodiment.
  • FIG. 1 is a graph showing the relationship between the order of the transverse mode of laser light in a nitride-based semiconductor light-emitting element and the waveguide loss.
  • 10 is a schematic graph showing distribution of band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting device according to the second embodiment.
  • FIG. 11 is a schematic cross-sectional view showing an overall configuration of a nitride-based semiconductor light-emitting device according to a third embodiment.
  • FIG. 13 is a schematic graph showing distribution of band gap energy and impurity concentration in the stacking direction of a nitride-based semiconductor light-emitting device according to a fourth embodiment.
  • 13 is a schematic graph showing distribution of band gap energy and impurity concentration in the stacking direction of a nitride-based semiconductor light-emitting device according to the fifth embodiment.
  • 13 is a schematic graph showing distribution of band gap energy and impurity concentration in the stacking direction of a nitride-based semiconductor light-emitting device according to a sixth embodiment.
  • FIG. 13 is a schematic cross-sectional view showing an overall configuration of a nitride-based semiconductor light-emitting device according to a seventh embodiment.
  • 13 is a schematic graph showing distribution of band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting device according to the seventh embodiment. 13 is a schematic graph showing the distribution of band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting device according to the eighth embodiment. 23 is a schematic graph showing the distribution of band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting device according to the ninth embodiment. 23 is a schematic graph showing the distribution of band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting device according to the tenth embodiment.
  • FIG. 13 is a schematic cross-sectional view showing the overall configuration of a nitride-based semiconductor light-emitting device according to an eleventh embodiment.
  • FIG. 23 is a schematic graph showing the distribution of band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting device according to the eleventh embodiment. 23 is a graph showing the relationship between the waveguide loss and the Al composition ratio of the lower P-side optical guide layer in Configuration Example 1 of the nitride-based semiconductor light-emitting device according to the eleventh embodiment.
  • 23 is a graph showing the relationship between the operating current and the Al composition ratio of the lower P-side optical guide layer when the power consumption is 0.5 W, in the first configuration example of the nitride-based semiconductor light-emitting device according to the eleventh embodiment.
  • 23 is a graph showing the relationship between the operating voltage value and the Al composition ratio of the lower P-side optical guide layer when the power consumption is 0.5 W, in Configuration Example 1 of the nitride-based semiconductor light-emitting device according to the eleventh embodiment.
  • 23 is a graph showing the relationship between the optical confinement factor and the Al composition ratio of a lower P-side optical guide layer of Configuration Example 1 of the nitride-based semiconductor light-emitting element according to the eleventh embodiment.
  • 23 is a graph showing the relationship between the effective refractive index difference ⁇ N and the Al composition ratio of the lower P-side optical guide layer of Configuration Example 1 of the nitride-based semiconductor light-emitting device according to the eleventh embodiment.
  • 23 is a graph showing the relationship between WPE and the Al composition ratio of a lower P-side optical guide layer when power consumption is 0.5 W in Configuration Example 1 of the nitride-based semiconductor light-emitting device according to the eleventh embodiment.
  • 13 is a diagram showing the configurations and characteristics of examples 1 to 4 of a nitride-based semiconductor light-emitting element according to an eleventh embodiment.
  • FIG. 23 is a graph showing the relationship between the waveguide loss and the In composition ratio of the lower P-side optical guide layer in Configuration Example 2 of the nitride-based semiconductor light-emitting element according to the eleventh embodiment.
  • 13 is a graph showing the relationship between the operating current and the In composition ratio of the lower P-side optical guide layer when the power consumption is 0.5 W, in Configuration Example 2 of the nitride-based semiconductor light-emitting device according to the eleventh embodiment.
  • 13 is a graph showing the relationship between the operating voltage value and the In composition ratio of the lower P-side optical guide layer when the power consumption is 0.5 W, in Configuration Example 2 of the nitride-based semiconductor light-emitting device according to the eleventh embodiment.
  • 13 is a graph showing the relationship between the optical confinement factor and the In composition ratio of the lower P-side optical guide layer of Configuration Example 2 of the nitride-based semiconductor light-emitting element according to the eleventh embodiment.
  • 13 is a graph showing the relationship between the effective refractive index difference ⁇ N and the In composition ratio of the lower P-side optical guide layer in Configuration Example 2 of the nitride-based semiconductor light-emitting element according to the eleventh embodiment.
  • 13 is a graph showing the relationship between WPE and the In composition ratio of a lower P-side optical guide layer when power consumption is 0.5 W in Configuration Example 2 of the nitride-based semiconductor light-emitting device according to the eleventh embodiment.
  • 13 is a diagram showing the configurations and characteristics of examples 5 to 8 of the nitride-based semiconductor light-emitting element according to the eleventh embodiment.
  • each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, the scales and the like are not necessarily the same in each figure. Furthermore, in each figure, the same reference numerals are used for substantially the same configurations, and duplicate explanations are omitted or simplified.
  • the terms “above” and “below” do not refer to vertically above and below in an absolute spatial sense, but are used as terms defined by a relative positional relationship based on the stacking order in the stacked configuration. Furthermore, the terms “above” and “below” are applied not only to cases where two components are arranged with a gap between them and another component exists between the two components, but also to cases where two components are arranged in contact with each other.
  • Fig. 1 and Fig. 2 each show a nitride-based semiconductor light-emitting device 100 according to the present embodiment.
  • 2 is a schematic plan view and a cross-sectional view showing the overall configuration of the device shown in FIG. 1.
  • X-axis, Y-axis, and The X-axis, Y-axis, and Z-axis are shown in the figure.
  • the X-axis, Y-axis, and Z-axis are in a right-handed Cartesian coordinate system.
  • the lamination direction of the nitride-based semiconductor light-emitting element 100 is parallel to the Z-axis direction.
  • the main emission direction of the light (laser light) is parallel to the Y-axis direction.
  • the nitride-based semiconductor light-emitting element 100 includes a semiconductor laminate 100S including a nitride-based semiconductor layer, and emits light from an end face 100F (see FIG. 1) perpendicular to the stacking direction (i.e., the Z-axis direction) of the semiconductor laminate 100S.
  • the nitride-based semiconductor light-emitting element 100 is a semiconductor laser element having two end faces 100F and 100R that form a resonator.
  • the end face 100F is a front end face that emits laser light
  • the end face 100R is a rear end face that has a higher reflectivity than the end face 100F.
  • the nitride-based semiconductor light-emitting element 100 also has a waveguide formed between the end face 100F and the end face 100R.
  • the reflectivities of the end faces 100F and 100R are not particularly limited, but in this embodiment, they are 16% and 95%, respectively.
  • the cavity length of the nitride-based semiconductor light-emitting element 100 according to this embodiment i.e., the distance between the end face 100F and the end face 100R) is about 800 ⁇ m.
  • the peak wavelength of the light emitted by the nitride-based semiconductor light-emitting element 100 is less than 400 nm.
  • the nitride-based semiconductor light-emitting element 100 emits ultraviolet light having a peak wavelength in the 375 nm band, for example.
  • the nitride-based semiconductor light-emitting element 100 may also emit ultraviolet light having a peak wavelength in a band other than the 375 nm band.
  • the nitride-based semiconductor light-emitting element 100 includes a substrate 101, a semiconductor laminate 100S, a current blocking layer 120, a P-side electrode 131, an adhesion layer 132, a pad electrode 133, and an N-side electrode 140.
  • the semiconductor laminate 100S includes an underlayer 102, a buffer layer 103, an N-type cladding layer 104, an N-side light guide layer 106, an active layer 107, an electron barrier layer 109, a P-type intermediate layer 110, a P-side light guide layer 111, a P-type cladding layer 112, and a contact layer 113.
  • An element isolation groove 10T is formed on the side surface (end surface in the X-axis direction) of the semiconductor laminate 100S.
  • the element isolation groove 10T is a groove for separating the nitride-based semiconductor light-emitting element 100.
  • the substrate 101 is a plate-like member made of a nitride-based semiconductor that serves as a base for the nitride-based semiconductor light-emitting element 100.
  • the substrate 101 has main surfaces 101a and 101b.
  • the substrate 101 is disposed below the N-type cladding layer 104 and is made of N-type GaN. More specifically, the substrate 101 is a GaN substrate with a thickness of 85 ⁇ m that is doped with Si at an average concentration of 1.4 ⁇ 10 18 cm ⁇ 3 .
  • the underlayer 102 is an N-type nitride-based semiconductor layer disposed above the substrate 101.
  • the underlayer 102 may have an average Al composition ratio smaller than that of the N-type cladding layer 104.
  • the underlayer 102 is an N-type Al 0.02 Ga 0.98 N layer with a thickness of 1000 nm that is disposed on the main surface 101a of the substrate 101 and is doped with Si at an average concentration of 1.0 ⁇ 10 18 cm ⁇ 3 .
  • the average impurity concentration of each layer refers to the impurity concentration value at a certain position in the stacking direction of that layer, integrated in the stacking direction from the interface position on the side closer to substrate 101 to the interface position on the side farther from substrate 101 in the stacking direction of that layer, and divided by the film thickness of that layer (the distance between the interface on the side closer to substrate 101 and the interface on the side farther from substrate 101).
  • impurity refers to impurities doped to obtain an N-type conductivity
  • P-type semiconductor layer it refers to impurities doped to obtain a P-type conductivity.
  • the average Al composition ratio of a certain layer is the value of the Al composition ratio at a certain position in the stacking direction of that layer, integrated in the stacking direction from the interface position on the side closest to the substrate 101 in the stacking direction of that layer to the interface position on the side furthest from the substrate 101 in the stacking direction of that layer, and divided by the film thickness of that layer.
  • the buffer layer 103 is an N-type nitride-based semiconductor layer disposed between the substrate 101 and the N-type cladding layer 104. In this embodiment, the buffer layer 103 is disposed on the underlayer 102. In this embodiment, the buffer layer 103 has an N-type GaN layer having a thickness of 10 nm and doped with Si at an average concentration of 1.0 ⁇ 10 18 cm ⁇ 3 , an N-type In 0.04 Ga 0.96 N layer having a thickness of 150 nm and doped with Si at an average concentration of 1.0 ⁇ 10 18 cm ⁇ 3 disposed above the N-type GaN layer, and an N-type In 0.04 Ga 0.96 N layer having a thickness of 10 nm and doped with Si at an average concentration of 1.0 ⁇ 10 18 cm ⁇ 3 disposed above the N-type GaN layer.
  • the N-type cladding layer 104 is disposed above the substrate 101 and is an N-type nitride-based semiconductor layer containing Al. In this embodiment, the N-type cladding layer 104 is disposed on the buffer layer 103. The N-type cladding layer 104 has a smaller average refractive index and a larger average band gap energy than the active layer 107. The N-type cladding layer 104 also has a smaller average refractive index and a larger average band gap energy than the N-side optical guide layer 106. The average Al composition ratio of the N-type cladding layer 104 is larger than the average Al composition ratio of the N-side optical guide layer 106. The average Al composition ratio of the N-type cladding layer 104 may be less than 10%. In this embodiment, the N-type cladding layer 104 is an N-type Al 0.065 Ga 0.935 N layer doped with Si at an average concentration of 1.0 ⁇ 10 18 cm ⁇ 3 and having a thickness of 900 nm.
  • the average band gap energy of a layer refers to the value of the band gap energy at a certain position in the stacking direction of the layer, integrated in the stacking direction from the interface position on the side closest to the substrate 101 in the stacking direction of the layer to the interface position on the side furthest from the substrate 101, and divided by the film thickness of the layer.
  • the average refractive index of a layer is the refractive index at a certain position in the stacking direction of the layer, integrated in the stacking direction from the interface position on the side closest to the substrate 101 to the interface position on the side furthest from the substrate 101, and divided by the film thickness of the layer.
  • the N-side light guide layer 106 is disposed above the N-type cladding layer 104 and is a nitride-based semiconductor layer containing Al.
  • the N-side light guide layer 106 has a larger average refractive index and a smaller average band gap energy than the N-type cladding layer 104.
  • the average Al composition ratio of the N-side light guide layer 106 may be less than 10%.
  • the N-side light guide layer 106 has an N-type Al 0.03 Ga 0.97 N layer with a thickness of 127 nm doped with Si at an average concentration of 1.0 ⁇ 10 18 cm ⁇ 3 , and an undoped Al 0.03 Ga 0.97 N layer with a thickness of 80 nm disposed above the N-type Al 0.03 Ga 0.97 N layer.
  • the undoped layer means a semiconductor layer with an impurity concentration less than 1.0 ⁇ 10 18 cm ⁇ 3 .
  • the active layer 107 is disposed above the N-side optical guide layer 106, and is a nitride-based semiconductor layer including a well layer 107b and barrier layers 107a and 107c containing Al.
  • the well layer 107b is disposed between the barrier layer 107a and the barrier layer 107c.
  • the active layer 107 emits ultraviolet light.
  • the configuration of the active layer 107 is not limited to this.
  • the active layer 107 may have a multiple quantum well structure.
  • the active layer 107 may have three or more barrier layers and two or more well layers. In other words, the active layer 107 includes one or more well layers and multiple barrier layers.
  • Each of the barrier layers 107a and 107c is a nitride-based semiconductor layer disposed above the N-side optical guide layer 106 and functions as a barrier of the quantum well structure.
  • the barrier layer 107c is disposed above the barrier layer 107a.
  • the average band gap energy of each of the barrier layers 107a and 107c is larger than the average band gap energy of the well layer 107b.
  • the barrier layer 107a is an undoped Al0.04Ga0.96N layer having a thickness of 14 nm.
  • the barrier layer 107c is an undoped Al0.04Ga0.96N layer having a thickness of 12 nm.
  • the well layer 107b is a nitride-based semiconductor layer disposed above the barrier layer 107a and functioning as a well of the quantum well structure, In this embodiment, the well layer 107b is an undoped In 0.01 Ga 0.99 N layer having a thickness of 17.5 nm.
  • the electron barrier layer 109 is disposed above the active layer 107 and is a P-type nitride-based semiconductor layer containing Al.
  • the average band gap energy of the electron barrier layer 109 is greater than that of the barrier layer 107c. This makes it possible to suppress leakage of electrons from the active layer 107 to the P-type cladding layer 112.
  • the average band gap energy of the electron barrier layer 109 is greater than that of each of the P-type intermediate layer 110 and the P-type cladding layer 112.
  • the average impurity concentration of the electron barrier layer 109 is greater than that of each of the P-type intermediate layer 110 and the P-side light guide layer 111.
  • the electron barrier layer 109 is a P-type Al 0.36 Ga 0.64 N layer doped with Mg at an average concentration of 1.5 ⁇ 10 19 cm ⁇ 3 and having a thickness of 1.6 nm.
  • the P-type intermediate layer 110 is disposed above the electron barrier layer 109 and is a P-type nitride-based semiconductor layer containing Al.
  • the average impurity concentration of the P-type intermediate layer 110 is lower than that of the electron barrier layer 109 and is higher than that of the P-side light guide layer 111.
  • the average Al composition ratio of the P-type intermediate layer 110 may be less than 10%.
  • the film thickness of the P-type intermediate layer 110 may be greater than that of the electron barrier layer 109.
  • the P-type intermediate layer 110 is a P-type Al 0.065 Ga 0.935 N layer doped with Mg at an average concentration of 1.0 ⁇ 10 19 cm ⁇ 3 and having a film thickness of 20 nm.
  • the P-side light guide layer 111 is disposed above the electron barrier layer 109 and is a nitride-based semiconductor layer containing Al. In this embodiment, the P-side light guide layer 111 is disposed above the P-type intermediate layer 110. The P-side light guide layer 111 has a larger average refractive index and a smaller average band gap energy than the P-type cladding layer 112. In this embodiment, the average band gap energy of the P-side light guide layer 111 is smaller than the average band gap energies of the P-type intermediate layer 110 and the P-type cladding layer 112. The average Al composition ratio of the P-side light guide layer 111 may be less than 10%. In this embodiment, the P-side light guide layer 111 is a P-type Al 0.03 Ga 0.97 N layer doped with Mg at an average concentration of 2.0 ⁇ 10 18 cm ⁇ 3 and having a thickness of 110 nm.
  • the P-type cladding layer 112 is disposed above the P-side light guide layer 111 and is a P-type nitride-based semiconductor layer containing Al.
  • the P-type cladding layer 112 is a layer having a smaller average refractive index and a higher average band gap energy than the active layer 107.
  • the average band gap energy of the P-type cladding layer 112 is smaller than the average band gap energy of the electron barrier layer 109.
  • the average Al composition ratio of the P-type cladding layer 112 may be less than 10%.
  • the impurity concentration at the end of the P-type cladding layer 112 closer to the active layer 107 may be lower than the impurity concentration at the end farther from the active layer 107.
  • the P-type cladding layer 112 has a P-type Al0.065Ga0.935N layer doped with Mg to an average concentration of 2.0 ⁇ 1018 cm -3 and having a thickness of 170 nm, and a P-type Al0.065Ga0.935N layer doped with Mg to an average concentration of 1.0 ⁇ 1019 cm -3 and having a thickness of 300 nm disposed on the P-type Al0.065Ga0.935N layer.
  • the contact layer 113 is a P-type nitride-based semiconductor layer disposed above the P-type cladding layer 112 and in ohmic contact with the P-side electrode 131.
  • the contact layer 113 has a P-type GaN layer with a thickness of 50 nm and doped with Mg to an average concentration of 2.0 ⁇ 10 19 cm ⁇ 3 , and a P-type GaN layer with a thickness of 10 nm and doped with Mg to an average concentration of 2.0 ⁇ 10 20 cm ⁇ 3 disposed thereon.
  • a ridge 11R is formed in the contact layer 113 and the P-type cladding layer 112.
  • the ridge 11R is formed in the contact layer 113, the P-type cladding layer 112, and the P-side light guide layer 111.
  • two grooves 11T are formed in the contact layer 113, the P-type cladding layer 112, and the P-side light guide layer 111, arranged along the ridge 11R and extending in the Y-axis direction.
  • the ridge width W is about 15 ⁇ m.
  • the distance between the lower end of the ridge 11R (i.e., the bottom of the groove 11T) and the electron barrier layer 109 is defined as dc.
  • the distance dc is 35 nm.
  • the 20 nm thick P-type intermediate layer 110 and the lower 15 nm thick portion of the 110 nm thick P-side optical guide layer 111 are located between the lower end of the ridge 11R and the electron barrier layer 109, and the upper 95 nm thick portion of the P-side optical guide layer 111 is located on the ridge 11R.
  • the current blocking layer 120 is disposed above the P-type cladding layer 112, and is an insulating layer that is transparent to light from the active layer 107.
  • the current blocking layer 120 is disposed in a region of the upper surface of the semiconductor laminate 100S other than the upper surface of the ridge 11R.
  • the current blocking layer 120 may also be disposed in a partial region of the upper surface of the ridge 11R.
  • the current blocking layer 120 may be disposed in an edge region of the upper surface of the ridge 11R.
  • the current blocking layer 120 is a SiO2 layer having a thickness of 300 nm.
  • the P-side electrode 131 is a conductive layer disposed above the contact layer 113. In this embodiment, the P-side electrode 131 is in contact with the contact layer 113.
  • the P-side electrode 131 is, for example, a single-layer film or a multilayer film formed of at least one of Cr, Ti, Ni, Pd, Pt, Ag, and Au.
  • Ag which has a low refractive index for light in the 375 nm wavelength band, for at least a part of the P-side electrode 131, it is possible to reduce the seepage of light propagating through the waveguide into the P-side electrode 131, thereby reducing the waveguide loss generated in the P-side electrode 131.
  • the refractive index of Ag is 0.5 or less in the wavelength range of 325 nm to 1500 nm, and is 0.2 or less in the wavelength range of 360 nm to 950 nm.
  • the refractive index of Ag is 0.5 or less in the wavelength range of 325 nm to 1500 nm, and is 0.2 or less in the wavelength range of 360 nm to 950 nm.
  • the light loss in the P-side electrode 131 can be reduced in a wide wavelength range of 325 nm to 950 nm.
  • the thickness of the P-type cladding layer 112 is 400 nm or less, the leakage of light propagating through the waveguide into the P-side electrode 131 can be reduced, so that the series resistance of the nitride-based semiconductor light-emitting element 100 can be reduced while suppressing an increase in waveguide loss.
  • the P-side electrode 131 has a Pd layer with a thickness of 40 nm and a Pt layer with a thickness of 100 nm disposed on the Pd layer.
  • the thickness of the P-type cladding layer 112 may be greater than the total thickness of the P-side light guide layer (the thickness of the P-side light guide layer 111 in this embodiment) and the total thickness of the N-side light guide layer (the thickness of the N-side light guide layer 106 in this embodiment). This allows the thickness of the P-type cladding layer 112 to be sufficient to confine light below the P-side electrode 131, thereby suppressing waveguide loss.
  • the thickness of the P-type cladding layer 112 may be 200 nm or more and 400 nm or less. This allows the operating voltage and operating current to be reduced while suppressing waveguide loss.
  • a layer with a large Al composition ratio such as the P-type cladding layer 112 causes a large distortion to the substrate 101 made of N-type GaN.
  • the total Al content in the P-type cladding layer 112 can be reduced, and therefore the distortion of the P-type cladding layer 112 to the substrate 101 can be reduced. Therefore, cracking of the nitride-based semiconductor light-emitting element 100 caused by distortion of the P-type cladding layer 112 can be suppressed.
  • ⁇ N effective refractive index difference
  • SiO 2 having a refractive index lower than that of the P-type cladding layer 112 on the sidewall of the ridge 11R to reduce the effective refractive index of the outer region of the ridge 11R.
  • the thickness of the P-type cladding layer 112 needs to be 0.15 ⁇ m or more.
  • the adhesion layer 132 is a metal layer disposed between the current blocking layer 120 and the pad electrode 133.
  • the adhesion layer 132 has the function of increasing the adhesion of the pad electrode 133.
  • the adhesion layer 132 may be disposed on the P-side electrode 131.
  • the adhesion layer 132 has a Ti layer with a thickness of 10 nm disposed on the current blocking layer 120, and a Pt layer with a thickness of 100 nm disposed on the Ti layer.
  • the pad electrode 133 is a pad-shaped electrode that is disposed above the P-side electrode 131. In this embodiment, the pad electrode 133 is disposed above the P-side electrode 131 and the adhesion layer 132. In this embodiment, the pad electrode 133 is an Au layer with a thickness of 2.0 ⁇ m.
  • the N-side electrode 140 is a conductive layer disposed below the substrate 101 (i.e., on the principal surface 101b opposite the principal surface 101a of the substrate 101 on which the N-type cladding layer 104 and the like are disposed).
  • the N-side electrode 140 is, for example, a single layer or a multilayer film formed of at least one of Cr, Ti, Ni, Pd, Pt, and Au.
  • the N-side electrode 140 has a Ti layer with a thickness of 10 nm, a Pt layer with a thickness of 50 nm, and an Au film with a thickness of 300 nm, which are stacked in this order from the substrate 101 side.
  • Figs. 3 and 4 are schematic graphs showing the distribution of band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting element according to Comparative Example 1 and the present embodiment, respectively. Note that Figs. 3 and 4 also show the intensity distribution of light propagating through the nitride-based semiconductor light-emitting element 100.
  • Fig. 5 is a graph showing the extinction coefficient spectrum in an AlGaN layer. In Fig.
  • the nitride-based semiconductor light-emitting device according to Comparative Example 1 differs from the nitride-based semiconductor light-emitting device 100 according to the present embodiment in that it does not include the P-type intermediate layer 110, but is the same in other respects.
  • the nitride-based semiconductor light-emitting device includes an electron barrier layer 109 having a large band gap energy.
  • the electron barrier layer 109 is doped with a high concentration of impurity (Mg). Accordingly, in the manufacturing process of each nitride-based semiconductor light-emitting device, the layer stacked following the stacking process of the electron barrier layer 109 is doped with impurities remaining in the chamber used for stacking. For this reason, as shown in FIG.
  • the P-side light guide layer 111 stacked on the electron barrier layer 109 is doped with an impurity at a higher concentration than the design impurity concentration of the P-side light guide layer 111.
  • the impurity concentration is high in the region of the P-side light guide layer 111 near the electron barrier layer 109.
  • the optical absorption edge (the long-wavelength end of the optical absorption wavelength band) is shifted to lower energy (i.e., shifted to the longer wavelength side) due to the influence of the impurity levels. Furthermore, the amount of the lower energy shift increases as the impurity concentration increases. For this reason, in an AlGaN layer with a relatively small average Al composition ratio such as the P-side optical guide layer 111, the influence of optical absorption (i.e., optical loss) caused by the increase in the impurity concentration becomes significant.
  • the nitride-based semiconductor light-emitting device 100 has a P-type intermediate layer 110 on the electron barrier layer 109, the P-type intermediate layer 110 having an average band gap energy smaller than that of the electron barrier layer 109 and a larger average band gap energy than that of the P-side optical guide layer 111.
  • the average impurity concentration of the P-type intermediate layer 110 is lower than that of the electron barrier layer 109 and higher than that of the P-side optical guide layer 111.
  • the nitride-based semiconductor light-emitting device 100 includes a P-type intermediate layer 110 having a larger average band gap energy than the P-side light guide layer 111 in the region where the impurity concentration is high on the electron barrier layer 109, and this allows the light absorption edge in this region to be shifted to the higher energy side (shorter wavelength side) than the nitride-based semiconductor light-emitting device according to Comparative Example 1. Therefore, the nitride-based semiconductor light-emitting device 100 according to this embodiment can suppress light absorption in this region more than the nitride-based semiconductor light-emitting device according to Comparative Example 1. In this way, the nitride-based semiconductor light-emitting device 100 according to this embodiment can suppress light loss while reducing the Al composition ratio of each layer, such as the P-side light guide layer 111 and the P-type cladding layer 112.
  • the average band gap energy of the P-type intermediate layer 110 may be equal to or greater than the average band gap energy of the P-type cladding layer 112.
  • the thickness of the P-type intermediate layer 110 may be 10 nm or more.
  • the effect of remaining impurities is reduced.
  • the impurity concentration can be reduced by 20% or more compared to the impurity concentration at the interface above the electron barrier layer 109. Therefore, by making the thickness of the P-type intermediate layer 110 10 nm or more, optical loss caused by remaining impurities can be suppressed.
  • the impurity concentration can be reduced to less than half of the impurity concentration at the interface above the electron barrier layer 109.
  • the thickness of the P-type intermediate layer 110 20 nm or more the optical loss caused by remaining impurities can be sufficiently suppressed.
  • the P-type intermediate layer 110 is made of AlGaN.
  • the composition of the P-type intermediate layer 110 is Al x Ga 1-x N (0 ⁇ x ⁇ 1).
  • the average Al composition ratio of the P-type intermediate layer 110 may be greater than 3%.
  • the average band gap energy can be increased to a level that sufficiently suppresses absorption of light in the ultraviolet region.
  • the average Al composition ratio of each of the N-type cladding layer 104, the N-side light guide layer 706, the P-type intermediate layer 110, the P-side light guide layer 111, and the P-type cladding layer 112 may be less than 10%.
  • the nitride-based semiconductor light-emitting element 100 may also have a ridge 11R that extends in the light propagation direction (i.e., a direction parallel to the Y-axis direction in each figure).
  • an optical waveguide can be formed along the ridge 11R.
  • FIG. 6 is a schematic cross-sectional view showing the shape of the side 11Rs of the ridge 11R according to the present embodiment.
  • FIG. 6 shows the outline of the ridge 11R.
  • FIG. 7 is a graph showing the relationship between the order of the transverse mode of the laser light in the nitride-based semiconductor light-emitting device and the waveguide loss.
  • FIG. 7 shows the simulation results of the waveguide loss in a nitride-based semiconductor light-emitting device having a waveguide structure substantially equivalent to that of the nitride-based semiconductor light-emitting device 100 according to the present embodiment.
  • FIG. 7 also shows the waveguide loss when the inclination angle ⁇ r of the side 11Rs of the ridge 11R is set to 50 degrees, 60 degrees, 70 degrees, 80 degrees, and 90 degrees.
  • Figure 7 shows the waveguide loss for angles from 80 degrees to 90 degrees.
  • the inclination angle ⁇ r of the side surface 11Rs of the ridge 11R (the end surface of the ridge 11R in the X-axis direction) with respect to the main surface 101a of the substrate 101 is defined.
  • the XY plane shown in Figure 6 is a plane parallel to the main surface 101a of the substrate 101.
  • the waveguide loss generally tends to increase as the order increases, and in low-order modes (e.g., zero-order mode), the waveguide loss is the same regardless of the tilt angle ⁇ r.
  • the trend is shown with respect to the tilt angle ⁇ r.
  • the waveguide loss does not change significantly with respect to the mode order.
  • the waveguide loss of high-order mode light e.g., 12th-order mode light
  • the waveguide loss of the 12th-order mode light is the largest compared to other tilt angles.
  • the tilt angle ⁇ r is 50 degrees
  • the loss of intermediate-order mode light such as the 4th-order mode light and the 7th-order mode light increases, showing a larger waveguide loss than other angles.
  • the average Al composition ratio of the N-type cladding layer 104 is small (for example, less than 10%) and/or when the film thickness is relatively small, a substrate mode in which light propagates through the substrate 101 is likely to occur. For this reason, in the nitride-based semiconductor light-emitting device 100 according to this embodiment, the waveguide loss as described above becomes significant.
  • high-order mode light such as 12th-order mode light causes a nonlinear bend (a so-called kink) to occur in the graph showing the current-light output (IL) characteristics of the nitride-based semiconductor light-emitting element 100.
  • the waveguide loss of the higher-order mode light can be increased and the waveguide loss of the intermediate-order mode light can be suppressed.
  • the abundance ratio of the higher-order mode light while suppressing the waveguide loss of the lower-order mode light and the intermediate-order mode light, the occurrence of kinks in the current-light output characteristics can be suppressed.
  • the abundance ratio of the higher-order mode light the occurrence of the substrate mode can be suppressed and anti-guided mode light leaking out of the ridge 11R from the side surface 11Rs of the ridge 11R can be suppressed.
  • the horizontal spread angle (spread angle in the XY plane) of the output light of the nitride-based semiconductor light-emitting element 100 can also be reduced.
  • the inclination angle ⁇ r may be greater than or equal to 60 degrees and less than or equal to 75 degrees. This allows the proportion of high-order mode light to be further reduced.
  • the ridge 11R having such an inclination angle ⁇ r can be realized by the following method.
  • nitride semiconductors can be etched with chlorine radicals and ions.
  • a chlorine-containing gas is turned into plasma using the ISM (Inductively Super Magnetron) method or the ICP (Inductively Coupled Plasma) method, and the plasma is irradiated onto the nitride semiconductor.
  • Etching with the chlorine ions contained in the plasma is highly anisotropic. Therefore, etching with chlorine ions allows for highly perpendicular etching.
  • etching with chlorine radicals is highly isotropic.
  • the ratio of chlorine ions and chlorine radicals and the kinetic energy of the chlorine ions can be controlled by changing the pressure and applied voltage. This makes it possible to control the balance between anisotropic etching and isotropic etching and obtain the desired tilt angle ⁇ r.
  • the nitride-based semiconductor light-emitting element 100 additionally has the following effect. If a P-type intermediate layer 110 having a smaller refractive index than the P-side optical guide layer 111 is disposed between the electron barrier layer 109 and the P-side optical guide layer 111, the optical confinement function works even in a location closer to the active layer 107 than the P-type cladding layer 112, so that the center of the optical distribution shifts to the N side (i.e., toward the N-type cladding layer 104) and the effective refractive index difference ⁇ N decreases compared to a case where the P-type intermediate layer 110 is not present.
  • the thickness of the P-type intermediate layer 110 may be made thinner when the Al composition ratio of the P-type cladding layer 112 is large, and the thickness of the P-type intermediate layer 110 may be made thicker when the Al composition ratio of the P-type cladding layer 112 is small.
  • the Al composition ratio of the P-side light guide layer 111 is 0.03 (i.e., 3%) and the Al composition ratio of the P-type cladding layer 112 is 0.065 (i.e., 6.5%)
  • the Al composition ratio of the P-type intermediate layer 110 is 0.050 or more and 0.080 or less (i.e., 5.0% or more and 8.0% or less)
  • the thickness of the P-type intermediate layer 110 may be 5 nm or more and 20 nm or less
  • the Al composition ratio of the P-type intermediate layer 110 is 0.030 or more and 0.050 or less (i.e., 3.0% or more and 5.0% or less)
  • the thickness of the P-type intermediate layer 110 may be 20 nm or more and 40 nm or less.
  • the thickness of the P-type intermediate layer 110 may be 5 nm or more and 10 nm or less.
  • the nitride-based semiconductor light-emitting device according to the present embodiment differs from the nitride-based semiconductor light-emitting device 100 according to the first embodiment in the configuration of the P-type intermediate layer, but is the same in other configurations.
  • the nitride-based semiconductor light-emitting device according to the present embodiment will be described below with reference to FIG. 8, focusing on the differences from the nitride-based semiconductor light-emitting device 100 according to the first embodiment.
  • FIG. 8 is a schematic graph showing the distribution of band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting device according to this embodiment.
  • the nitride-based semiconductor light-emitting device according to this embodiment includes a P-type intermediate layer 210.
  • the P-type intermediate layer 210 differs from the P-type intermediate layer 110 according to the first embodiment in that the average band gap energy of the P-type intermediate layer 210 is smaller than the average band gap energy of the P-type cladding layer 112.
  • the P-type intermediate layer 210 is a P-type Al 0.05 Ga 0.95 N layer doped with Mg at an average concentration of 1.0 ⁇ 10 19 cm -3 and having a thickness of 20 nm.
  • the nitride-based semiconductor light-emitting device according to this embodiment having the above-described configuration also exhibits the same effects as the nitride-based semiconductor light-emitting device 100 according to the first embodiment.
  • the average band gap energy of the P-type intermediate layer 210 is smaller than the average band gap energy of the P-type cladding layer 112.
  • the P-type intermediate layer 210 can also function as a light guide layer. This allows the optical loss in the nitride-based semiconductor light-emitting element 100 to be reduced without reducing the light confinement function in the active layer 107.
  • the average refractive index of the P-type intermediate layer 210 by increasing the average refractive index of the P-type intermediate layer 210, it is possible to suppress the deterioration of the light confinement function in the active layer 107 that occurs with an increase in the film thickness of the P-type intermediate layer 210. Therefore, even when the region with a high impurity concentration is large, it is possible to reduce optical loss while suppressing the deterioration of the light confinement function by increasing the film thickness of the P-type intermediate layer 210.
  • the nitride-based semiconductor light-emitting device according to this embodiment differs from nitride-based semiconductor light-emitting device 100 according to embodiment 1 in the position of the bottom end of the ridge and the relative position with respect to P-type intermediate layer 110, but is the same in other configurations.
  • the nitride-based semiconductor light-emitting device according to this embodiment will be described below with reference to FIG. 9, focusing on the differences from nitride-based semiconductor light-emitting device 100 according to embodiment 1.
  • FIG. 9 is a schematic cross-sectional view showing the overall configuration of a nitride-based semiconductor light-emitting device 300 according to this embodiment.
  • FIG. 9 shows a cross-section of the nitride-based semiconductor light-emitting device 300 at the same position as in FIG. 2.
  • the nitride-based semiconductor light-emitting device 300 includes a substrate 101, a semiconductor laminate 100S, a current blocking layer 120, a P-side electrode 131, an adhesion layer 132, a pad electrode 133, and an N-side electrode 140, similar to the nitride-based semiconductor light-emitting device 100 according to the first embodiment.
  • a ridge 21R is formed in the contact layer 113, the P-type cladding layer 112, the P-side light guide layer 111, and the P-type intermediate layer 110.
  • two grooves 21T are formed in the contact layer 113, the P-type cladding layer 112, the P-side light guide layer 111, and the P-type intermediate layer 110, arranged along the ridge 21R and extending in the Y-axis direction.
  • the lower end of the ridge 21R is located in the P-type intermediate layer 110.
  • at least a part of the P-type intermediate layer 110 is arranged in the ridge 21R.
  • the distance dc between the lower end of the ridge 21R and the electron barrier layer 109 is equal to or greater than 0 and less than 20 nm.
  • the nitride-based semiconductor light-emitting device 300 according to this embodiment which has the above-described configuration, also exhibits the same effects as the nitride-based semiconductor light-emitting device 100 according to the first embodiment.
  • the P-type intermediate layer 110 is disposed on the ridge 21R.
  • the P-side light guide layer 111 located above the P-type intermediate layer 110 is disposed within the ridge 21R. Therefore, the refractive index of the ridge 21R and the current blocking layer 120 located on the side of the ridge 21R is smaller than that of the ridge 21R, thereby improving the light confinement function in the lateral direction (the X-axis direction in each figure). Therefore, stable multi-mode oscillation can be realized in the nitride-based semiconductor light-emitting element 300.
  • a surface state due to dangling bonds is formed on the surface of the P-type intermediate layer 110 corresponding to the bottom and side surfaces of the groove 21T formed by etching. This reduces the band gap of the region of the P-type intermediate layer 110 that contacts the bottom and side surfaces of the groove 21T.
  • doping the P-type intermediate layer 110 with Mg shifts the absorption range in the absorption coefficient spectrum to longer wavelengths.
  • a P-type intermediate layer 110 having an average band gap energy larger than that of the P-side optical guide layer 111 can be provided by using a P-type intermediate layer 110 having an Al composition ratio larger than that of the P-side optical guide layer 111 as in this embodiment. Therefore, even if the lower end of the ridge 21R is disposed in the P-type intermediate layer 110, the absorption loss in the region of the P-type intermediate layer that contacts the groove 21T can be suppressed.
  • FIG. 4 A nitride-based semiconductor light-emitting device according to embodiment 4 will be described.
  • the nitride-based semiconductor light-emitting device according to this embodiment differs from the nitride-based semiconductor light-emitting device 100 according to embodiment 1 in the configuration of the P-type intermediate layer, but is the same in other configurations.
  • the nitride-based semiconductor light-emitting device according to this embodiment will be described below with reference to FIG. 10, focusing on the differences from the nitride-based semiconductor light-emitting device 100 according to embodiment 1.
  • FIG. 10 is a schematic graph showing the distribution of band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting device according to this embodiment.
  • the nitride-based semiconductor light-emitting device according to this embodiment includes a P-type intermediate layer 410.
  • the P-type intermediate layer 410 has a first P-type intermediate layer 410a and a second P-type intermediate layer 410b that is disposed above the first P-type intermediate layer 410a and has a smaller average band gap energy than the first P-type intermediate layer 410a.
  • the average Al composition ratio of the first P-type intermediate layer 410a is greater than the average Al composition ratio of the second P-type intermediate layer 410b.
  • the average band gap energy of the first P-type intermediate layer 410a is larger than the average band gap energy of the P-type cladding layer 112, and the average band gap energy of the P-type intermediate layer 410 is smaller than the average band gap energy of the P-type cladding layer 112.
  • the average impurity concentration (average Mg concentration) of the first P-type intermediate layer 410a is larger than the average impurity concentration of the second P-type intermediate layer 410b.
  • the first P-type intermediate layer 410a is a P-type Al0.08Ga0.92N layer doped with Mg to an average concentration of 1.3 ⁇ 1019 cm -3 and having a thickness of 5 nm
  • the second P-type intermediate layer 410b is a P-type Al0.05Ga0.95N layer doped with Mg to an average concentration of 9.0 ⁇ 1018 cm -3 and having a thickness of 15 nm.
  • the nitride-based semiconductor light-emitting device according to this embodiment having the above-described configuration also exhibits the same effects as the nitride-based semiconductor light-emitting device 100 according to the first embodiment.
  • the P-type intermediate layer 410 has a first P-type intermediate layer 410a and a second P-type intermediate layer 410b that is disposed above the first P-type intermediate layer 410a and has a smaller average band gap energy than the first P-type intermediate layer 410a.
  • the impurity concentration tends to increase as it approaches the electron barrier layer 109.
  • the higher the impurity concentration the greater the light absorption.
  • by providing a first P-type intermediate layer 410a with a large average band gap energy in a region close to the electron barrier layer 109 and with a high impurity concentration light loss in the P-type intermediate layer 410 can be further suppressed.
  • the average band gap energy of the first P-type intermediate layer 410a may be greater than the average band gap energy of the P-type cladding layer 112, and the average band gap energy of the P-type intermediate layer 410 may be smaller than the average band gap energy of the P-type cladding layer 112.
  • the optical loss in the first P-type intermediate layer 410a can be suppressed.
  • a part of the P-type intermediate layer 410 can function as an optical guide layer, as in the second embodiment.
  • the average Al composition ratio of the entire P-type intermediate layer 410 can be reduced. This makes it possible to increase the proportion of impurities that function as acceptors among the impurities doped into the P-type intermediate layer 410, thereby suppressing the electrical resistance in the P-type intermediate layer 410.
  • the P-type intermediate layer 410 has two layers, a first P-type intermediate layer 410a and a second P-type intermediate layer 410b, but the P-type intermediate layer 410 may have three or more layers.
  • the P-type intermediate layer 410 may further have a third P-type intermediate layer that is disposed above the second P-type intermediate layer 410b and has a smaller average band gap energy than the second P-type intermediate layer 410b.
  • FIG. 5 A nitride-based semiconductor light-emitting device according to embodiment 5 will be described.
  • the nitride-based semiconductor light-emitting device according to this embodiment differs from nitride-based semiconductor light-emitting device 100 according to embodiment 1 in the configuration of the P-type intermediate layer, but is the same in other configurations.
  • the nitride-based semiconductor light-emitting device according to this embodiment will be described below with reference to FIG. 11, focusing on the differences from nitride-based semiconductor light-emitting device 100 according to embodiment 1.
  • FIG. 11 is a schematic graph showing the distribution of band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting device according to this embodiment.
  • the nitride-based semiconductor light-emitting device according to this embodiment includes a P-type intermediate layer 510.
  • the P-type intermediate layer 510 has a P-type gradient region in which the Al composition ratio decreases with increasing distance from the electron barrier layer 109.
  • the entire P-type intermediate layer 510 is a P-type gradient region.
  • the average band gap energy of the P-type intermediate layer 510 is smaller than the average band gap energy of the P-type cladding layer 112.
  • the P-type intermediate layer 510 has an impurity concentration gradient region in which the impurity concentration decreases with increasing distance from the electron barrier layer 109.
  • the entire P-type intermediate layer 510 is an impurity concentration gradient region.
  • the P-type intermediate layer 510 is a P-type AlGaN layer doped with Mg at an average concentration of 1.0 ⁇ 10 19 cm -3 and having a thickness of 20 nm.
  • the composition of the P-type intermediate layer 510 at the interface with the electron barrier layer 109 is Al 0.08 Ga 0.92 N
  • the composition of the P-type intermediate layer 510 at the interface with the P-side light guide layer 111 is Al 0.05 Ga 0.95 N.
  • the Al composition ratio of the P-type intermediate layer 510 decreases continuously with increasing distance from the electron barrier layer 109.
  • the impurity concentration of the P-type intermediate layer 510 decreases continuously from 1.5 ⁇ 10 19 cm -3 to 2.0 ⁇ 10 18 cm -3 .
  • the nitride-based semiconductor light-emitting device according to this embodiment having the above-described configuration also exhibits the same effects as the nitride-based semiconductor light-emitting device 100 according to the first embodiment.
  • the P-type intermediate layer 510 has a P-type gradient region in which the Al composition ratio decreases with increasing distance from the electron barrier layer 109.
  • the impurity concentration tends to decrease with increasing distance from the electron barrier layer 109.
  • the higher the impurity concentration the greater the light absorption.
  • by having a P-type gradient region in which the Al composition ratio decreases with increasing distance from the electron barrier layer 109 it is possible to reduce the band gap energy with increasing distance from the electron barrier layer 109. This makes it possible to reduce the Al composition ratio while suppressing light loss in the P-type intermediate layer 510.
  • the average band gap energy of the P-type intermediate layer 510 may be smaller than the average band gap energy of the P-type cladding layer 112.
  • a part of the P-type intermediate layer 510 can function as a light guide layer. Furthermore, by reducing the band gap energy of the P-type intermediate layer 510, the average Al composition ratio of the entire P-type intermediate layer 510 can be reduced. Therefore, the proportion of impurities that function as acceptors among the impurities doped into the P-type intermediate layer 410 can be increased, thereby suppressing the electrical resistance in the P-type intermediate layer 410.
  • FIG. 6 A nitride-based semiconductor light-emitting device according to embodiment 6 will be described.
  • the nitride-based semiconductor light-emitting device according to this embodiment differs from the nitride-based semiconductor light-emitting device 100 according to embodiment 1 in the configuration of the P-type intermediate layer, but is the same in other configurations.
  • the nitride-based semiconductor light-emitting device according to this embodiment will be described below with reference to FIG. 12, focusing on the differences from the nitride-based semiconductor light-emitting device 100 according to embodiment 1.
  • FIG. 12 is a schematic graph showing the distribution of band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting device according to this embodiment.
  • the nitride-based semiconductor light-emitting device according to this embodiment includes a P-type intermediate layer 610.
  • the P-type intermediate layer 610 has a first P-type intermediate layer 610a having an average band gap energy smaller than that of the P-type cladding layer 112, and a second P-type intermediate layer 610b arranged above the first P-type intermediate layer 610a and having an average band gap energy larger than that of the first P-type intermediate layer 610a.
  • the second P-type intermediate layer 610b has an average band gap energy smaller than that of the P-type cladding layer 112.
  • the average Al composition ratio of the first P-type intermediate layer 610a is smaller than the average Al composition ratio of the second P-type intermediate layer 610b.
  • the average impurity concentration (average Mg concentration) of the first P-type intermediate layer 610a is smaller than the average impurity concentration of the second P-type intermediate layer 610b.
  • the first P-type intermediate layer 610a is a P-type Al0.04Ga0.96N layer doped with Mg to an average concentration of 5.0 ⁇ 1018 cm -3 and having a thickness of 10 nm
  • the second P-type intermediate layer 610b is a P-type Al0.05Ga0.95N layer doped with Mg to an average concentration of 1.0 ⁇ 1019 cm -3 and having a thickness of 15 nm.
  • the Mg concentration is low in the region of the P-type intermediate layer 610 close to the active layer 107, i.e., in the region where the light intensity is greater, so that the effect of suppressing light loss is greater than that of the nitride-based semiconductor light-emitting device 100 according to the first embodiment.
  • the P-type intermediate layer 610 has a first P-type intermediate layer 610a that has a smaller average band gap energy than the P-type cladding layer 112, and a second P-type intermediate layer 610b that is disposed above the first P-type intermediate layer 610a and has a larger average band gap energy than the first P-type intermediate layer 610a.
  • the residual impurities tend to cause the impurity concentration in the layer stacked on the electron barrier layer 109 to become high. This effect can occur over a film thickness of about 80 nm or more and about 100 nm or less.
  • a P-type intermediate layer By disposing a P-type intermediate layer in most of this region where the impurity concentration is likely to become high, light loss can be suppressed.
  • the refractive index of the P-type intermediate layer is high and the film thickness of the P-type intermediate layer is large, the light confinement function in the active layer 107 can be significantly reduced.
  • the average band gap energy of the first P-type intermediate layer 610a is made smaller than the average band gap energy of the P-type cladding layer 112, thereby making the average refractive index of the first P-type intermediate layer 610a larger than the average refractive index of the P-type cladding layer 112.
  • the first P-type intermediate layer 610a which functions as a light guide layer, is disposed in a region of the P-type intermediate layer 610 close to the active layer 107. Therefore, it is possible to suppress a decrease in the light confinement function in the active layer 107 in the nitride-based semiconductor light-emitting device according to this embodiment.
  • the average impurity concentration in the first P-type intermediate layer 610a may be lower than the average impurity concentration in the second P-type intermediate layer 610b. This makes it possible to suppress a shift in the optical absorption edge to the long wavelength side caused by impurities in the first P-type intermediate layer 610a, thereby suppressing optical loss in the first P-type intermediate layer 610a.
  • the film thickness of the first P-type intermediate layer 610a may be less than 15 nm. This makes it possible to suppress optical loss in the first P-type intermediate layer 610a.
  • the P-type intermediate layer 610 has two layers, a first P-type intermediate layer 610a and a second P-type intermediate layer 610b, but the P-type intermediate layer 610 may have three or more layers.
  • the P-type intermediate layer 610 may further have a third P-type intermediate layer that is disposed above the second P-type intermediate layer 610b and has a smaller average band gap energy than the second P-type intermediate layer 610b.
  • a nitride-based semiconductor light-emitting device (Seventh embodiment) A nitride-based semiconductor light-emitting device according to the seventh embodiment will be described.
  • the nitride-based semiconductor light-emitting device according to the present embodiment differs from the nitride-based semiconductor light-emitting device 100 according to the first embodiment in that it includes an N-type intermediate layer, but is the same in other respects.
  • the nitride-based semiconductor light-emitting device according to the present embodiment will be described below with reference to FIGS. 13 and 14, focusing on the differences from the nitride-based semiconductor light-emitting device 100 according to the first embodiment.
  • FIG. 13 is a schematic cross-sectional view showing the overall configuration of a nitride-based semiconductor light-emitting element 700 according to this embodiment.
  • FIG. 13 shows a cross-section of the nitride-based semiconductor light-emitting element 700 at the same position as in FIG. 2.
  • FIG. 14 is a schematic graph showing the distribution of the band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting element 700 according to this embodiment.
  • the nitride-based semiconductor light-emitting element 700 includes a substrate 101, a semiconductor laminate 700S, a current blocking layer 120, a P-side electrode 131, an adhesion layer 132, a pad electrode 133, and an N-side electrode 140.
  • the semiconductor laminate 700S has a base layer 102, a buffer layer 103, an N-type cladding layer 104, an N-type intermediate layer 705, an N-side optical guide layer 706, an active layer 107, an electron barrier layer 109, a P-type intermediate layer 110, a P-side optical guide layer 111, a P-type cladding layer 112, and a contact layer 113.
  • the N-type intermediate layer 705 is disposed above the N-type cladding layer 104 and is a nitride-based semiconductor layer containing Al.
  • the average band gap energy of the N-type intermediate layer 705 is larger than that of the N-side optical guide layer 706 and smaller than that of the N-type cladding layer 104.
  • the average Al composition ratio of the N-type intermediate layer 705 may be less than 10%.
  • the average impurity concentration of the N-type intermediate layer 705 is equal to or lower than that of the N-type cladding layer 104 and is higher than that of the N-side optical guide layer 706.
  • the N-type intermediate layer 705 is an N-type Al 0.05 Ga 0.95 N layer doped with Si at an average concentration of 1.0 ⁇ 10 18 cm ⁇ 3 and having a thickness of 20 nm.
  • the N-side optical guide layer 706 is disposed above the N-type intermediate layer 705 and is a nitride-based semiconductor layer containing Al.
  • the N-side optical guide layer 706 has a larger average refractive index and a smaller average band gap energy than the N-type cladding layer 104 and the N-type intermediate layer 705.
  • the N-side optical guide layer 706 is an undoped Al0.03Ga0.97N layer having a film thickness of 187 nm.
  • the film thickness of the N-type intermediate layer 705 is 20 nm or more.
  • the N-side optical guide layer 706, which is an undoped AlGaN layer, is directly stacked on the N-type cladding layer 104, which is an AlGaN layer doped with Si as an N-type impurity there may be an effect of residual impurities, although this effect is smaller than that of residual P-type impurities.
  • the impurity concentration in the N-side optical guide layer 706, particularly in the region near the N-type cladding layer 104 may be higher than the design value.
  • the N-type AlGaN layer, as in the P-type AlGaN layer a shift in the optical absorption edge to the long wavelength side may occur depending on the impurity concentration. For this reason, the optical loss in the N-side optical guide layer 706 may increase.
  • the nitride-based semiconductor light-emitting device 700 according to this embodiment is provided with an N-type intermediate layer 705 having a larger average band gap energy than the N-side optical guide layer 706 in an area on the N-type cladding layer 104 where the impurity concentration is likely to be high, and thus can suppress optical absorption in the same manner as the P-type intermediate layer 110.
  • the nitride-based semiconductor light-emitting device 700 according to this embodiment can suppress optical loss while reducing the Al composition ratio of each layer, such as the N-side optical guide layer 706 and the N-type cladding layer 104.
  • the thickness of the N-type intermediate layer 705 may be 20 nm or more.
  • the effect of remaining impurities is reduced.
  • the impurity concentration can be reduced to less than half of the impurity concentration at the upper interface of the N-type cladding layer 104. Therefore, by making the film thickness of the N-type intermediate layer 705 20 nm or more, optical loss caused by remaining impurities can be sufficiently suppressed.
  • the N-type intermediate layer 705 is made of AlGaN.
  • the composition of the N-type intermediate layer 705 is Al y Ga 1-y N (0 ⁇ y ⁇ 1).
  • the average Al composition ratio of the N-type intermediate layer 705 may be greater than 3%.
  • the average band gap energy can be increased to a level that sufficiently suppresses absorption of light in the ultraviolet region.
  • the average Al composition ratio of each of the N-type cladding layer 104, the N-side optical guide layer 706, the N-type intermediate layer 705, the P-side optical guide layer 111, and the P-type cladding layer 112 may be less than 10%.
  • breakage and cracks in the wafer on which the semiconductor stack 700S is formed are reduced.
  • defects generated inside the nitride-based semiconductor light-emitting device 700 are reduced. Therefore, the yield of the nitride-based semiconductor light-emitting device 700 can be improved.
  • the nitride-based semiconductor light-emitting device according to the present embodiment differs from the nitride-based semiconductor light-emitting device 700 according to the seventh embodiment in the configuration of the N-type intermediate layer, but is the same in other configurations.
  • the nitride-based semiconductor light-emitting device according to the present embodiment will be described below with reference to FIG. 15, focusing on the differences from the nitride-based semiconductor light-emitting device 700 according to the seventh embodiment.
  • FIG. 15 is a schematic graph showing the distribution of band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting device according to this embodiment.
  • the nitride-based semiconductor light-emitting device according to this embodiment includes an N-type intermediate layer 805.
  • the N-type intermediate layer 805 has a first N-type intermediate layer 805a and a second N-type intermediate layer 805b that is disposed above the first N-type intermediate layer 805a and has a smaller average band gap energy than the first N-type intermediate layer 805a.
  • the average Al composition ratio of the first N-type intermediate layer 805a is greater than the average Al composition ratio of the second N-type intermediate layer 805b.
  • the average impurity concentration (average Si concentration) of the first N-type intermediate layer 805a is greater than the average impurity concentration of the second N-type intermediate layer 805b.
  • the first N-type intermediate layer 805a is an N-type Al0.06Ga0.94N layer doped with Si at an average concentration of 1.0 ⁇ 1018 cm -3 and having a thickness of 10 nm
  • the second N-type intermediate layer 805b is an N-type Al0.05Ga0.95N layer doped with Si at an average concentration of 8.0 ⁇ 1017 cm -3 and having a thickness of 10 nm.
  • the nitride-based semiconductor light-emitting device according to this embodiment having the above-described configuration also exhibits the same effects as the nitride-based semiconductor light-emitting device 700 according to embodiment 7.
  • the N-type intermediate layer 805 has a first N-type intermediate layer 805a and a second N-type intermediate layer 805b that is disposed above the first N-type intermediate layer 805a and has a smaller average band gap energy than the first N-type intermediate layer 805a.
  • the impurity concentration in the N-type intermediate layer 805 tends to increase as it approaches the N-type cladding layer 104.
  • an AlGaN layer such as the N-type intermediate layer 805
  • the higher the impurity concentration the greater the light absorption.
  • by providing a first N-type intermediate layer 805a with a large average band gap energy in a region close to the N-type cladding layer 104 and with a high impurity concentration light loss in the N-type intermediate layer 805 can be further suppressed.
  • the N-type intermediate layer 805 has two layers, a first N-type intermediate layer 805a and a second N-type intermediate layer 805b, but the N-type intermediate layer 805 may have three or more layers.
  • the N-type intermediate layer 805 may further have a third N-type intermediate layer that is disposed above the second N-type intermediate layer 805b and has a smaller average band gap energy than the second N-type intermediate layer 805b.
  • FIG. 9 A nitride-based semiconductor light-emitting device according to embodiment 9 will be described.
  • the nitride-based semiconductor light-emitting device according to this embodiment differs from nitride-based semiconductor light-emitting device 700 according to embodiment 7 in the configuration of the N-type intermediate layer, but is the same in other configurations.
  • the nitride-based semiconductor light-emitting device according to this embodiment will be described below with reference to FIG. 16, focusing on the differences from nitride-based semiconductor light-emitting device 700 according to embodiment 7.
  • FIG. 16 is a schematic graph showing the distribution of band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting device according to this embodiment.
  • the nitride-based semiconductor light-emitting device according to this embodiment includes an N-type intermediate layer 905.
  • the N-type intermediate layer 905 has an N-type gradient region in which the Al composition ratio decreases with increasing distance from the N-type cladding layer 104.
  • the entire N-type intermediate layer 905 is an N-type gradient region.
  • the average band gap energy of the N-type intermediate layer 905 is smaller than the average band gap energy of the N-type cladding layer 104.
  • the N-type intermediate layer 905 has an impurity concentration gradient region in which the impurity concentration decreases with increasing distance from the N-type cladding layer 104.
  • the entire N-type intermediate layer 905 is an impurity concentration gradient region.
  • the N-type intermediate layer 905 is an N-type AlGaN layer doped with Si at an average concentration of 8.0 ⁇ 10 17 cm ⁇ 3 and having a thickness of 20 nm.
  • the composition of the N-type intermediate layer 905 at the interface with the N-type cladding layer 104 is Al 0.065 Ga 0.935 N
  • the composition of the N-type intermediate layer 905 at the interface with the N-side optical guide layer 706 is Al 0.05 Ga 0.95 N.
  • the Al composition ratio of the N-type intermediate layer 905 decreases continuously with increasing distance from the N-type cladding layer 104.
  • the impurity concentration of the N-type intermediate layer 905 also decreases continuously with increasing distance from the N-type cladding layer 104.
  • the nitride-based semiconductor light-emitting device according to this embodiment having the above-described configuration also exhibits the same effects as the nitride-based semiconductor light-emitting device 700 according to embodiment 7.
  • the N-type intermediate layer 905 has an N-type gradient region in which the Al composition ratio decreases with increasing distance from the N-type cladding layer 104.
  • the impurity concentration tends to decrease with increasing distance from the N-type cladding layer 104.
  • the higher the impurity concentration the greater the light absorption.
  • by having an N-type gradient region in which the Al composition ratio decreases with increasing distance from the N-type cladding layer 104 it is possible to reduce the band gap energy with increasing distance from the N-type cladding layer 104. This makes it possible to reduce the Al composition ratio while suppressing light loss in the N-type intermediate layer 905.
  • FIG. 10 A nitride-based semiconductor light-emitting device according to embodiment 10 will be described.
  • the nitride-based semiconductor light-emitting device according to this embodiment differs from the nitride-based semiconductor light-emitting device 700 according to embodiment 7 in the configuration of the N-type intermediate layer, but is the same in other configurations.
  • the nitride-based semiconductor light-emitting device according to this embodiment will be described below with reference to FIG. 17, focusing on the differences from the nitride-based semiconductor light-emitting device 700 according to embodiment 7.
  • FIG. 17 is a schematic graph showing the distribution of band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting device according to this embodiment.
  • the nitride-based semiconductor light-emitting device according to this embodiment includes an N-type intermediate layer 1005.
  • the N-type intermediate layer 1005 has a first N-type intermediate layer 1005a having an average band gap energy smaller than that of the N-type cladding layer 104, and a second N-type intermediate layer 1005b arranged above the first N-type intermediate layer 1005a and having an average band gap energy larger than that of the first N-type intermediate layer 1005a.
  • the second N-type intermediate layer 1005b has an average band gap energy smaller than that of the N-type cladding layer 104.
  • the average Al composition ratio of the first N-type intermediate layer 1005a is smaller than the average Al composition ratio of the second N-type intermediate layer 1005b.
  • the average impurity concentration (average Si concentration) of the first N-type intermediate layer 1005a is smaller than the average impurity concentration of the second N-type intermediate layer 1005b.
  • the first N-type intermediate layer 1005a is an N-type Al0.05Ga0.95N layer doped with Si to an average concentration of 8.0 ⁇ 1017cm -3 and having a thickness of 10 nm
  • the second N-type intermediate layer 1005b is an N-type Al0.06Ga0.94N layer doped with Si to an average concentration of 1.0 ⁇ 1018cm -3 and having a thickness of 10 nm .
  • the nitride-based semiconductor light-emitting device according to this embodiment having the above-described configuration also exhibits the same effects as the nitride-based semiconductor light-emitting device 700 according to embodiment 7.
  • the N-type intermediate layer 1005 has a first N-type intermediate layer 1005a that has a smaller average band gap energy than the N-type cladding layer 104, and a second N-type intermediate layer 1005b that is disposed above the first N-type intermediate layer 1005a and has a larger average band gap energy than the first N-type intermediate layer 1005a.
  • the residual impurities tend to cause the impurity concentration in the layer stacked on the N-type cladding layer 104 to become high. This effect can occur over a film thickness of about 20 nm or more.
  • optical loss can be suppressed.
  • the refractive index of the N-type intermediate layer is high and the film thickness of the N-type intermediate layer is large, the optical confinement function in the active layer 107 can be significantly reduced.
  • the average band gap energy of the first N-type intermediate layer 1005a is made smaller than the average band gap energy of the N-type cladding layer 104, so that the average refractive index of the first N-type intermediate layer 1005a is made larger than the average refractive index of the N-type cladding layer 104.
  • the first N-type intermediate layer 1005a functioning as a light guide layer is disposed in the N-type intermediate layer 1005. Therefore, it is possible to suppress a decrease in the light confinement function in the active layer 107 in the nitride-based semiconductor light-emitting device according to this embodiment.
  • the average impurity concentration in the first N-type intermediate layer 1005a may be lower than the average impurity concentration in the second N-type intermediate layer 1005b. This makes it possible to suppress a shift in the optical absorption edge to the long wavelength side caused by impurities in the first N-type intermediate layer 1005a, thereby suppressing optical loss in the first N-type intermediate layer 1005a.
  • the film thickness of the first N-type intermediate layer 1005a may be less than 15 nm. This makes it possible to suppress optical loss in the first N-type intermediate layer 1005a.
  • the N-type intermediate layer 1005 has two layers, a first N-type intermediate layer 1005a and a second N-type intermediate layer 1005b, but the N-type intermediate layer 1005 may have three or more layers.
  • the N-type intermediate layer 1005 may further have a third N-type intermediate layer disposed above the second N-type intermediate layer 1005b and having a smaller average band gap energy than the second N-type intermediate layer 1005b.
  • nitride-based semiconductor light-emitting device (Embodiment 11) A nitride-based semiconductor light-emitting device according to embodiment 11 will be described.
  • the nitride-based semiconductor light-emitting device according to this embodiment differs from nitride-based semiconductor light-emitting device 100 according to embodiment 1 mainly in the layer structure between the active layer and the electron barrier layer.
  • the nitride-based semiconductor light-emitting device according to this embodiment will be described below, focusing on the differences from nitride-based semiconductor light-emitting device 100 according to embodiment 1.
  • FIG. 18 shows the overall configuration of a nitride-based semiconductor light-emitting device 1100 according to this embodiment.
  • FIG. 19 shows the nitride-based semiconductor light-emitting device according to the present embodiment.
  • 11 is a schematic graph showing the distribution of band gap energy and impurity concentration in the stacking direction of the element 1100.
  • the nitride-based semiconductor light-emitting device 1100 includes a substrate 101, a semiconductor laminate 1100S, a current blocking layer 120, a P-side electrode 131, an adhesion layer 132, a pad electrode 133, and an N-side electrode 140.
  • the semiconductor laminate 1100S has a base layer 102, a buffer layer 103, an N-type cladding layer 1104, an N-side light guide layer 106, an active layer 1107, a lower P-side light guide layer 1111a, a lower P-side intermediate layer 1110a, an electron barrier layer 109, a P-type intermediate layer 1110, a P-side light guide layer 111, a P-type cladding layer 112, and a contact layer 113.
  • the N-type cladding layer 1104 is an Al-containing N-type nitride-based semiconductor layer disposed above the substrate 101.
  • the N-type cladding layer 1104 is an N-type Al 0.065 Ga 0.935 N layer doped with Si at an average concentration of 1.0 ⁇ 10 18 cm ⁇ 3 and having a thickness of 1500 nm.
  • the active layer 1107 is disposed above the N-side optical guide layer 106 and is a nitride-based semiconductor layer including a well layer 107b and barrier layers 107a and 1107c containing Al.
  • the well layer 107b is disposed between the barrier layer 107a and the barrier layer 1107c.
  • the barrier layer 1107c is a nitride-based semiconductor layer disposed above the N-side optical guide layer 106 and functions as a barrier of the quantum well structure.
  • the barrier layer 1107c is disposed above the barrier layer 107a.
  • the average band gap energy of the barrier layer 1107c is larger than the average band gap energy of the well layer 107b.
  • the barrier layer 1107c is an undoped Al0.04Ga0.96N layer having a thickness of 10 nm.
  • the lower P-side light guide layer 1111a is disposed between the active layer 1107 and the electron barrier layer 109, and is a nitride-based semiconductor layer containing Al. In this embodiment, the lower P-side light guide layer 1111a is disposed below the lower P-side intermediate layer 1110a.
  • the lower P-side light guide layer 1111a has a larger average refractive index and a smaller average band gap energy than the P-type cladding layer 112.
  • the average band gap energy of the lower P-side light guide layer 1111a is smaller than the average band gap energy of the P-type intermediate layer 1110 and the average band gap energy of the barrier layer 1107c disposed at the top of the multiple barrier layers in the active layer 1107 (i.e., closest to the electron barrier layer 109). This facilitates the electrical conduction of holes from the P-type cladding layer 112 through the electron barrier layer 109 to the active layer 1107. Therefore, the operating voltage of the nitride-based semiconductor light emitting device 1100 can be reduced.
  • the average band gap energy of the lower P-side optical guide layer 1111a is smaller than the average band gap energy of the lower P-side intermediate layer 1110a.
  • an AlGaN layer or an AlGaInN layer can be used as the lower P-side optical guide layer 1111a.
  • a detailed configuration example of the lower P-side optical guide layer 1111a will be described later.
  • the lower P-side intermediate layer 1110a is disposed between the lower P-side light guide layer 1111a and the electron barrier layer 109, and is a nitride-based semiconductor layer containing Al.
  • the average band gap energy of the lower P-side intermediate layer 1110a is larger than that of the lower P-side light guide layer 1111a and smaller than that of the electron barrier layer 109.
  • the lower P-side intermediate layer 1110a may be doped with a P-type impurity having an average concentration of, for example, 2.0 ⁇ 10 18 cm ⁇ 3 or less (the lower P-side intermediate layer 1110a may be undoped).
  • the average concentration of the P-type impurity in the lower P-side intermediate layer 1110a may be lower than that of the P-type impurity in the P-type intermediate layer 1110.
  • the lower P-side intermediate layer 1110a is an Al 0.04 Ga 0.96 N layer having a thickness of 3 nm, which is thin and undoped, thereby achieving both a reduction in free carrier loss and suppression of an increase in voltage.
  • the P-type intermediate layer 1110 is disposed above the electron barrier layer 109 and is a P-type nitride-based semiconductor layer containing Al.
  • the P-type intermediate layer 1110 is a P-type Al 0.05 Ga 0.95 N layer doped with Mg at an average concentration of 1.0 ⁇ 10 19 cm ⁇ 3 and having a thickness of 56 nm.
  • the lower end of the ridge 21R is located in the P-type intermediate layer 1110, and the distance dc between the lower end of the ridge 21R and the electron barrier layer 109 is 55 nm.
  • the lower end of the ridge 21R may be located in the P-side optical guide layer 111 above the P-type intermediate layer 1110.
  • the distance dc between the lower end of the ridge 21R and the electron barrier layer 109 may be 58 nm.
  • FIG. 20 is a graph showing the relationship between the waveguide loss and the Al composition ratio of the lower P-side light guide layer 1111a of the first configuration example of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment.
  • FIG. 21 is a graph showing the relationship between the operating current and the Al composition ratio of the lower P-side light guide layer 1111a when the power consumption is 0.5 W of the first configuration example of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment.
  • FIG. 21 is a graph showing the relationship between the operating current and the Al composition ratio of the lower P-side light guide layer 1111a when the power consumption is 0.5 W of the first configuration example of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment.
  • Fig. 22 is a graph showing the relationship between the operating voltage value and the Al composition ratio of the lower P-side light guide layer 1111a when the power consumption is 0.5 W of the first configuration example of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment.
  • Fig. 23 is a graph showing the relationship between the optical confinement coefficient and the Al composition ratio of the lower P-side light guide layer 1111a of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment in the configuration example 1.
  • Fig. 23 is a graph showing the relationship between the optical confinement coefficient and the Al composition ratio of the lower P-side light guide layer 1111a of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment in the configuration example 1.
  • Fig. 24 is a graph showing the relationship between the effective refractive index difference ⁇ N and the Al composition ratio of the lower P-side light guide layer 1111a of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment in the configuration example 1.
  • Fig. 25 is a graph showing the relationship between the WPE (Wall-Plug Efficiency) and the Al composition ratio of the lower P-side light guide layer 1111a when the power consumption is 0.5 W in the nitride-based semiconductor light-emitting device 1100 according to the present embodiment in the configuration example 1.
  • Figs. 20 to 25 show the relationships when the thickness T1 of the lower P-side light guide layer 1111a is 9 nm, 20 nm, 40 nm, and 60 nm.
  • the Al composition ratio of the lower P-side optical guide layer 1111a which is an AlGaN layer, decreases, the operating voltage and operating current decrease, and the optical confinement coefficient, effective refractive index difference ⁇ N, and WPE increase.
  • the Al composition ratio of the lower P-side optical guide layer 1111a may be set to 4% or less.
  • the thickness T1 of the lower P-side light guide layer 1111a may be set to 9 nm or more.
  • the thickness T1 of the lower P-side light guide layer 1111a may be set to 9 nm or more.
  • the thickness T1 of the lower P-side light guide layer 1111a may be set to 60 nm or less.
  • the waveguide loss is almost independent of the Al composition ratio of the lower P-side light guide layer 1111a, but in order to reduce the occurrence of light absorption loss in the lower P-side light guide layer 1111a, the Al composition ratio of the lower P-side light guide layer 1111a may be greater than 0. This allows the band gap energy of the lower P-side light guide layer 1111a to be greater than the band gap energy of GaN, thereby reducing the light absorption loss in the lower P-side light guide layer 1111a. In addition, in order to further reduce the light absorption loss in the lower P-side light guide layer 1111a, the Al composition ratio of the lower P-side light guide layer 1111a may be 1% or more.
  • the band gap energy of the lower P-side light guide layer 1111a may be equal to or lower than the band gap energy of the adjacent barrier layer 1107c.
  • the barrier layer 1107c is an Al0.04Ga0.96N layer
  • the Al composition ratio of the lower P-side light guide layer 1111a may be 4% or less in order to make the band gap energy of the lower P-side light guide layer 1111a equal to or lower than the band gap energy of the barrier layer 1107c.
  • the Al composition ratio of the lower P-side light guide layer 1111a may be equal to or less than the Al composition ratio of the P-side light guide layer 111.
  • the Al composition ratio of the P-side light guide layer 111 is 3%, so the Al composition ratio of the lower P-side light guide layer 1111a may be equal to or less than 3%. This allows the refractive index of the lower P-side light guide layer 1111a to be equal to or greater than the refractive index of the P-side light guide layer 111, thereby reducing the operating voltage and operating current and increasing the optical confinement coefficient, effective refractive index difference ⁇ N, and WPE.
  • the lower P-side optical guide layer 1111a may be an undoped AlGaN layer. This can suppress the optical absorption caused by the increase in impurity concentration described above.
  • FIG. 26 is a diagram showing the configurations and characteristics of examples 1 to 4 of the nitride-based semiconductor light-emitting device 1100 according to this embodiment.
  • FIG. 26 also shows the configuration and characteristics of a nitride-based semiconductor light-emitting device according to comparative example 2.
  • the nitride-based semiconductor light-emitting device according to comparative example 2 differs from the nitride-based semiconductor light-emitting device 1100 according to this embodiment in that it does not include a lower P-side light guide layer 1111a, but is the same in other respects.
  • Example 1 the Al composition ratio of the lower P-side light guide layer 1111a is 1.0% and the thickness T1 is 9.0 nm
  • Example 2 the Al composition ratio of the lower P-side light guide layer 1111a is 2.0% and the thickness T1 is 20.0 nm
  • Example 3 the Al composition ratio of the lower P-side light guide layer 1111a is 3.0% and the thickness T1 is 40.0 nm
  • Example 4 the Al composition ratio of the lower P-side light guide layer 1111a is 1.0% and the thickness T1 is 60.0 nm.
  • Example 26 in Examples 1 to 4, the operating voltage and operating current are reduced, and the optical confinement factor and WPE are increased, compared to Comparative Example 2 that does not include the lower P-side optical guide layer 1111a. Also, in Examples 1 to 4, an effective refractive index difference ⁇ N of 10 ⁇ 10 ⁇ 3 or more can be realized. Thus, in Examples 1 to 4, by including the lower P-side optical guide layer 1111a, it is possible to reduce the operating voltage and operating current, and increase the optical confinement factor and WPE while realizing an effective refractive index difference ⁇ N of 10 ⁇ 10 ⁇ 3 or more.
  • FIG. 27 is a graph showing the relationship between the waveguide loss and the In composition ratio of the lower P-side light guide layer 1111a of the second configuration example of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment.
  • FIG. 28 is a graph showing the relationship between the operating current and the In composition ratio of the lower P-side light guide layer 1111a when the power consumption is 0.5 W of the second configuration example of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment.
  • FIG. 28 is a graph showing the relationship between the operating current and the In composition ratio of the lower P-side light guide layer 1111a when the power consumption is 0.5 W of the second configuration example of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment.
  • FIG. 29 is a graph showing the relationship between the operating voltage value and the In composition ratio of the lower P-side light guide layer 1111a when the power consumption is 0.5 W of the second configuration example of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment.
  • 30 is a graph showing the relationship between the optical confinement coefficient and the In composition ratio of the lower P-side light guide layer 1111a in the configuration example 2 of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment.
  • FIG. 31 is a graph showing the relationship between the effective refractive index difference ⁇ N and the In composition ratio of the lower P-side light guide layer 1111a in the configuration example 2 of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment.
  • FIG. 32 is a graph showing the relationship between the WPE and the In composition ratio of the lower P-side light guide layer 1111a when the power consumption is 0.5 W in the configuration example 2 of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment.
  • FIG. 27 to FIG. 32 show the relationship in each case where the film thickness T1 of the lower P-side light guide layer 1111a is 9 nm, 20 nm, 40 nm, and 60 nm.
  • the Al composition ratio of the lower P-side light guide layer 1111a is 4.0% in all cases.
  • the In composition ratio of the lower P-side optical guide layer 1111a which is an AlGaInN layer
  • the operating voltage and operating current decrease, and the optical confinement coefficient, effective refractive index difference ⁇ N, and WPE increase.
  • the In composition ratio of the lower P-side optical guide layer 1111a may be set to a value greater than 0%.
  • the thickness T1 of the lower P-side light guide layer 1111a may be set to 9 nm or more.
  • the thickness T1 of the lower P-side light guide layer 1111a may be set to 9 nm or more.
  • the thickness T1 of the lower P-side light guide layer 1111a may be set to 60 nm or less.
  • the waveguide loss is almost independent of the In composition ratio of the lower P-side light guide layer 1111a.
  • the composition of the lower P-side light guide layer 1111a may be set so that the band gap energy of the lower P-side light guide layer 1111a is greater than the band gap energy of GaN.
  • the Al composition ratio of the lower P-side light guide layer 1111a may be 3% or more and 6% or less, and the In composition ratio may be greater than 0% and 2% or less.
  • the Al composition ratio and the In composition ratio of the lower P-side light guide layer 1111a may be set so that the band gap energy of the lower P-side light guide layer 1111a is equal to or less than the band gap energy of the adjacent barrier layer 1107c.
  • the band gap energy of the lower P-side light guide layer 1111a may be equal to or lower than the band gap energy of the P-side light guide layer 111. This allows the refractive index of the lower P-side light guide layer 1111a to be equal to or higher than the refractive index of the P-side light guide layer 111, thereby reducing the operating voltage and operating current and increasing the optical confinement coefficient, effective refractive index difference ⁇ N, and WPE.
  • the lower P-side optical guide layer 1111a may be an undoped AlGaInN layer. This can suppress the optical absorption caused by the increase in impurity concentration described above.
  • the AlGaInN layer which is a compressive strained layer with respect to the substrate 101, can be disposed below and near the ridge 21R. This reduces the shear stress at the bottom end of the ridge 21R caused by the AlGaN layer, which is a tensile strained layer with respect to the substrate 101.
  • warping of the wafer which is the base material used in manufacturing the nitride-based semiconductor light emitting device 1100, can be suppressed, and the occurrence of wafer cracking in the subsequent process of laminating the lower P-side light guide layer 1111a can be suppressed.
  • the Al composition ratio of the lower P-side light guide layer 1111a may be equal to the Al composition ratio of the adjacent barrier layer 1107c.
  • the barrier layer 1107c and the lower P-side light guide layer 1111a are formed continuously, in the formation process of the lower P-side light guide layer 1111a, only the In composition ratio needs to be changed relative to the formation process of the barrier layer 1107c. Therefore, the controllability of the atomic composition in the formation process of the lower P-side light guide layer 1111a can be improved, and the in-plane distribution (distribution in a plane perpendicular to the stacking direction) of the composition of the lower P-side light guide layer 1111a can be made uniform.
  • the In composition ratio of the lower P-side light guide layer 1111a may also change depending on the position in the stacking direction. For example, the In composition ratio in the region of the lower P-side light guide layer 1111a close to the active layer 1107 may be greater than the In composition ratio in the region far from the active layer 1107. This reduces the band gap energy in the region of the lower P-side light guide layer 1111a close to the active layer 1107, thereby increasing the hole conductivity in that region. Therefore, the operating voltage of the nitride-based semiconductor light-emitting device 1100 can be further reduced.
  • FIG. 33 is a diagram showing the configurations and characteristics of examples 5 to 8 of the nitride-based semiconductor light-emitting device 1100 according to this embodiment.
  • FIG. 33 also shows the configuration and characteristics of the nitride-based semiconductor light-emitting device according to comparative example 2.
  • the Al composition ratio of the lower P-side optical guide layer 1111a is 4.0%, and the In composition ratio is 1.3%.
  • the film thickness T1 is 9.0 nm
  • the film thickness T1 is 20.0 nm
  • the film thickness T1 is 40.0 nm
  • the film thickness T1 is 60.0 nm.
  • Example 5 to 8 the operating voltage and operating current are reduced, and the optical confinement factor and WPE are increased, compared to Comparative Example 2, which does not include the lower P-side optical guide layer 1111a. Also, in Examples 5 to 8, an effective refractive index difference ⁇ N of 10 ⁇ 10 ⁇ 3 or more can be realized. Thus, in Examples 5 to 8, by including the lower P-side optical guide layer 1111a, it is possible to reduce the operating voltage and operating current, and increase the optical confinement factor and WPE while realizing an effective refractive index difference ⁇ N of 10 ⁇ 10 ⁇ 3 or more.
  • the nitride-based semiconductor light-emitting element was a semiconductor laser element, but the nitride-based semiconductor light-emitting element is not limited to a semiconductor laser element.
  • the nitride-based semiconductor light-emitting element may be a superluminescent diode.
  • the reflectance of the end face of the semiconductor laminate included in the nitride-based semiconductor light-emitting element with respect to the output light from the semiconductor laminate may be 0.1% or less.
  • Such a reflectance can be achieved, for example, by forming an anti-reflection film made of a dielectric multilayer film or the like on the end face.
  • the proportion of the component of the guided light reflected at the front end face that recombines with the waveguide to become guided light can be set to a small value of 0.1% or less.
  • the impurity concentration in the P-type intermediate layer decreases with increasing distance from the electron barrier layer 109, but the impurity concentration may increase with increasing distance from the electron barrier layer 109 in at least a portion of the P-type intermediate layer.
  • each of the nitride-based semiconductor light-emitting devices according to the seventh to ninth embodiments includes a P-type intermediate layer, the P-type intermediate layer may not be included.
  • the P-type cladding layer 112 is a layer with a uniform Al composition ratio
  • the configuration of the P-type cladding layer 112 is not limited to this.
  • the P-type cladding layer 112 may have a superlattice structure in which multiple AlGaN layers and multiple GaN layers are alternately stacked.
  • the P-side electrode 131 contains Ag
  • the P-side electrode 131 may also contain Ag.
  • the same effect as that achieved by the P-side electrode 131 containing Ag in embodiment 1 can also be achieved in the other embodiments.
  • each of the configurations according to embodiments 2 to 6 may be combined with each of the configurations according to embodiments 7 to 9.
  • the P-type graded region according to the fourth embodiment may be included in the P-type intermediate layer according to other embodiments.
  • the N-type intermediate layer according to the seventh or eighth embodiment may include the N-type gradient region according to the ninth embodiment.
  • the nitride-based semiconductor light-emitting device disclosed herein can be used, for example, as a high-output, highly efficient light source for exposure devices and processing machines.

Landscapes

  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Geometry (AREA)
  • Semiconductor Lasers (AREA)
PCT/JP2023/030351 2022-09-27 2023-08-23 窒化物系半導体発光素子 Ceased WO2024070351A1 (ja)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CN202380068493.XA CN119999032A (zh) 2022-09-27 2023-08-23 氮化物系半导体发光元件
EP23871592.4A EP4597766A4 (en) 2022-09-27 2023-08-23 NITRID-BASED SEMICONDUCTOR ELECTROLUMINOUS DEVICE
JP2024549881A JPWO2024070351A1 (https=) 2022-09-27 2023-08-23
US19/083,979 US20250239836A1 (en) 2022-09-27 2025-03-19 Nitride semiconductor light-emitting element

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2022153433 2022-09-27
JP2022-153433 2022-09-27

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US19/083,979 Continuation US20250239836A1 (en) 2022-09-27 2025-03-19 Nitride semiconductor light-emitting element

Publications (1)

Publication Number Publication Date
WO2024070351A1 true WO2024070351A1 (ja) 2024-04-04

Family

ID=90477306

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2023/030351 Ceased WO2024070351A1 (ja) 2022-09-27 2023-08-23 窒化物系半導体発光素子

Country Status (5)

Country Link
US (1) US20250239836A1 (https=)
EP (1) EP4597766A4 (https=)
JP (1) JPWO2024070351A1 (https=)
CN (1) CN119999032A (https=)
WO (1) WO2024070351A1 (https=)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2025258310A1 (ja) * 2024-06-10 2025-12-18 ヌヴォトンテクノロジージャパン株式会社 半導体レーザ素子
WO2025258311A1 (ja) * 2024-06-10 2025-12-18 ヌヴォトンテクノロジージャパン株式会社 半導体レーザ素子

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000091705A (ja) * 1998-09-11 2000-03-31 Nec Corp 窒化ガリウム系半導体発光素子
JP2002335052A (ja) * 2001-05-10 2002-11-22 Nichia Chem Ind Ltd 窒化物半導体素子
JP2008047688A (ja) * 2006-08-15 2008-02-28 Toshiba Corp 窒化物系半導体レーザ装置
JP2009158955A (ja) * 2007-12-06 2009-07-16 Rohm Co Ltd 窒化物半導体レーザダイオード
JP2010258363A (ja) 2009-04-28 2010-11-11 Nichia Corp 窒化物半導体レーザ素子
US20120076165A1 (en) * 2009-06-05 2012-03-29 The Regents Of The University Of California Asymmetrically cladded laser diode
WO2020158254A1 (ja) * 2019-01-30 2020-08-06 パナソニックセミコンダクターソリューションズ株式会社 半導体発光素子
JP2021002575A (ja) * 2019-06-21 2021-01-07 古河機械金属株式会社 構造体、光デバイス、光デバイスの製造方法、構造体の製造方法

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8144743B2 (en) * 2008-03-05 2012-03-27 Rohm Co., Ltd. Nitride based semiconductor device and fabrication method for the same
JP2011238678A (ja) * 2010-05-07 2011-11-24 Panasonic Corp 半導体発光装置
US8897329B2 (en) * 2010-09-20 2014-11-25 Corning Incorporated Group III nitride-based green-laser diodes and waveguide structures thereof
DE102013017275B4 (de) * 2013-10-17 2022-01-27 OSRAM Opto Semiconductors Gesellschaft mit beschränkter Haftung Optoelektronisches Halbleiterbauelement

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000091705A (ja) * 1998-09-11 2000-03-31 Nec Corp 窒化ガリウム系半導体発光素子
JP2002335052A (ja) * 2001-05-10 2002-11-22 Nichia Chem Ind Ltd 窒化物半導体素子
JP2008047688A (ja) * 2006-08-15 2008-02-28 Toshiba Corp 窒化物系半導体レーザ装置
JP2009158955A (ja) * 2007-12-06 2009-07-16 Rohm Co Ltd 窒化物半導体レーザダイオード
JP2010258363A (ja) 2009-04-28 2010-11-11 Nichia Corp 窒化物半導体レーザ素子
US20120076165A1 (en) * 2009-06-05 2012-03-29 The Regents Of The University Of California Asymmetrically cladded laser diode
WO2020158254A1 (ja) * 2019-01-30 2020-08-06 パナソニックセミコンダクターソリューションズ株式会社 半導体発光素子
JP2021002575A (ja) * 2019-06-21 2021-01-07 古河機械金属株式会社 構造体、光デバイス、光デバイスの製造方法、構造体の製造方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP4597766A4

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2025258310A1 (ja) * 2024-06-10 2025-12-18 ヌヴォトンテクノロジージャパン株式会社 半導体レーザ素子
WO2025258311A1 (ja) * 2024-06-10 2025-12-18 ヌヴォトンテクノロジージャパン株式会社 半導体レーザ素子

Also Published As

Publication number Publication date
EP4597766A4 (en) 2026-01-07
US20250239836A1 (en) 2025-07-24
EP4597766A1 (en) 2025-08-06
JPWO2024070351A1 (https=) 2024-04-04
CN119999032A (zh) 2025-05-13

Similar Documents

Publication Publication Date Title
JP6941771B2 (ja) 半導体発光素子
US20250239836A1 (en) Nitride semiconductor light-emitting element
US11710941B2 (en) Semiconductor laser element
JP7820180B2 (ja) 窒化物系半導体発光素子
JPWO2024070351A5 (https=)
CN1305192C (zh) 具有高阶模式吸收层的半导体激光二极管
US20240396306A1 (en) Nitride semiconductor light-emitting element
US20250113669A1 (en) Nitride semiconductor light-emitting element
JP2019041102A (ja) レーザダイオード
US8077753B2 (en) Semiconductor laser device
JP2009076640A (ja) 半導体発光素子
US20230402821A1 (en) Nitride semiconductor light-emitting element
JP7736723B2 (ja) 窒化物系半導体発光素子
WO2025033368A1 (ja) 半導体レーザ素子
JP2026071392A (ja) 窒化物系半導体発光素子
WO2025258311A1 (ja) 半導体レーザ素子
JP2020017681A (ja) 半導体レーザ素子
CN121942101A (zh) 氮化物系半导体发光元件
WO2022270054A1 (ja) 窒化物半導体発光素子
WO2025258310A1 (ja) 半導体レーザ素子
WO2026053904A1 (ja) 半導体レーザ素子、及び半導体レーザ素子の製造方法
WO2015011858A1 (ja) 窒化物半導体レーザ素子
KR20060136260A (ko) 비대칭 광도파층을 지닌 반도체 레이저 다이오드
JP2007081017A (ja) モノリシック型半導体レーザ

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 23871592

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 2024549881

Country of ref document: JP

WWE Wipo information: entry into national phase

Ref document number: 202380068493.X

Country of ref document: CN

WWE Wipo information: entry into national phase

Ref document number: 2023871592

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 2023871592

Country of ref document: EP

Effective date: 20250428

WWP Wipo information: published in national office

Ref document number: 202380068493.X

Country of ref document: CN

WWP Wipo information: published in national office

Ref document number: 2023871592

Country of ref document: EP