WO2019146478A1 - 半導体レーザおよび電子機器 - Google Patents

半導体レーザおよび電子機器 Download PDF

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Publication number
WO2019146478A1
WO2019146478A1 PCT/JP2019/001192 JP2019001192W WO2019146478A1 WO 2019146478 A1 WO2019146478 A1 WO 2019146478A1 JP 2019001192 W JP2019001192 W JP 2019001192W WO 2019146478 A1 WO2019146478 A1 WO 2019146478A1
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Prior art keywords
layer
semiconductor laser
cladding layer
semiconductor
low concentration
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PCT/JP2019/001192
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English (en)
French (fr)
Japanese (ja)
Inventor
耕太 徳田
秀輝 渡邊
河角　孝行
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Sony Semiconductor Solutions Corp
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Sony Semiconductor Solutions Corp
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Priority to DE112019000483.2T priority Critical patent/DE112019000483T5/de
Priority to US16/960,710 priority patent/US11271368B2/en
Priority to JP2019567021A priority patent/JP7412176B2/ja
Priority to CN201980005918.6A priority patent/CN111386638B/zh
Publication of WO2019146478A1 publication Critical patent/WO2019146478A1/ja
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    • 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
    • H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
    • H01S5/042—Electrical excitation ; Circuits therefor
    • H01S5/0421—Electrical excitation ; Circuits therefor characterised by the semiconducting contacting 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
    • H01S5/22—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
    • 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
    • H01S5/3086—Structure or shape of the active region; Materials used for the active region characterised by the doping materials used in the laser structure doping of the active layer
    • H01S5/309—Structure or shape of the active region; Materials used for the active region characterised by the doping materials used in the laser structure doping of the active layer doping of barrier layers that confine charge carriers in the laser structure, e.g. the barriers in a quantum well 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
    • H01S5/32—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
    • H01S5/3214—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 comprising materials from other groups of the Periodic Table than the materials of the active layer, e.g. ZnSe claddings and GaAs active layer
    • 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
    • H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
    • H01S5/042—Electrical excitation ; Circuits therefor
    • H01S5/0425—Electrodes, e.g. characterised by the structure
    • H01S5/04252—Electrodes, e.g. characterised by the structure characterised by the material
    • H01S5/04253—Electrodes, e.g. characterised by the structure characterised by the material having specific optical properties, e.g. transparent electrodes
    • 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
    • H01S5/30—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
    • 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
    • H01S5/40—Arrangement of two or more semiconductor lasers, not provided for in groups H01S5/02 - H01S5/30
    • H01S5/4025—Array arrangements, e.g. constituted by discrete laser diodes or laser bar
    • H01S5/4031—Edge-emitting structures
    • H01S5/4043—Edge-emitting structures with vertically stacked active 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
    • H01S5/40—Arrangement of two or more semiconductor lasers, not provided for in groups H01S5/02 - H01S5/30
    • H01S5/4025—Array arrangements, e.g. constituted by discrete laser diodes or laser bar
    • H01S5/4087—Array arrangements, e.g. constituted by discrete laser diodes or laser bar emitting more than one wavelength
    • H01S5/4093—Red, green and blue [RGB] generated directly by laser action or by a combination of laser action with nonlinear frequency conversion

Definitions

  • the present disclosure relates to a semiconductor laser and an electronic device provided with the same.
  • the semiconductor laser from the viewpoint of enhancing the luminance, a high output is required. With the increase in power, heat generation becomes a problem.
  • the amount of heat generation is determined by the power conversion efficiency. Therefore, in order to suppress the amount of heat generation, it is important to reduce not only the light output characteristics but also the drive voltage. Therefore, it is desirable to provide a semiconductor laser capable of suppressing the driving voltage and an electronic device provided with the same.
  • a first semiconductor laser includes a semiconductor lamination portion.
  • the semiconductor multilayer portion includes a first cladding layer, an active layer, one or more low concentration impurity layers, a contact layer, and a second cladding layer formed of a transparent conductive material in this order.
  • the semiconductor stacked portion further has a ridge shape extending in one direction in the stacked surface in a portion including the contact layer.
  • the impurity concentration is 5.0 ⁇ 10 17 cm ⁇ 3 or less
  • the total film thickness of the low concentration impurity layer is 250 nm or more and 1000 nm or less.
  • the distance between the low concentration impurity layer closest to the second cladding layer and the second cladding layer is 150 nm or less.
  • a second semiconductor laser includes a semiconductor stack.
  • the semiconductor laminated portion includes a first cladding layer, an active layer, one or a plurality of low concentration impurity layers having an impurity concentration of 5.0 ⁇ 10 17 cm ⁇ 3 or less, a contact layer, and a second transparent conductive material.
  • the cladding layers are included in this order.
  • the semiconductor stacked portion further has a ridge shape extending in one direction in the stacked surface in a portion including the contact layer.
  • the second cladding layer is provided at a position distant from the optical waveguide region generated in the semiconductor multilayer portion when the semiconductor laser is driven.
  • a first electronic device includes the above-described first semiconductor laser as a light source.
  • a second electronic device includes the above-described second semiconductor laser as a light source.
  • the second cladding layer is formed of a transparent conductive material. Furthermore, in one or more low concentration impurity layers provided between the active layer and the contact layer, the impurity concentration is 5.0 ⁇ 10 17 cm ⁇ 3 or less, and the total thickness of the low concentration impurity layers is Is 250 nm or more and 1000 nm or less. Furthermore, the distance between the low concentration impurity layer closest to the second cladding layer and the second cladding layer is 150 nm or less.
  • the second clad layer formed of the transparent conductive material causes light in the stacking direction. Be trapped.
  • a band-like ridge is further formed. Thereby, light is confined also in the lateral direction.
  • the second cladding layer is formed of a transparent conductive material. Furthermore, in one or a plurality of low concentration impurity layers provided between the active layer and the contact layer, the impurity concentration is 5.0 ⁇ 10 17 cm ⁇ 3 or less. Furthermore, the second cladding layer is provided at a position distant from the optical waveguide region generated in the semiconductor multilayer portion when the semiconductor laser is driven. Thereby, the light absorption by the transparent conductive material is suppressed, and further, even in the case where the thick clad layer made of Mg-doped AlGaN is not provided, the second clad layer formed of the transparent conductive material causes light in the stacking direction. Be trapped. In the first semiconductor laser and the first electronic device according to an embodiment of the present disclosure, a band-like ridge is further formed. Thereby, light is confined also in the lateral direction.
  • FIG. 1 is a diagram illustrating an example of a cross-sectional configuration of a semiconductor laser according to an embodiment of the present disclosure. It is a figure showing an example of the relationship between the light intensity in the upper clad layer interface, and a light absorption loss.
  • FIG. 7 is a diagram illustrating an example of a cross-sectional configuration of a semiconductor laser according to Comparative Example A.
  • FIG. 18 is a diagram illustrating an example of a cross-sectional configuration of a semiconductor laser according to Comparative Example B.
  • FIG. 18 is a diagram illustrating an example of a cross-sectional configuration of a semiconductor laser according to Comparative Example C.
  • FIG. 6 is a diagram illustrating an example of IV characteristics of the example and the comparative examples A and B.
  • FIG. 7 is a view showing a modified example of the cross-sectional configuration of the semiconductor laser of FIG. 1;
  • FIG. 7 is a view showing a modified example of the cross-sectional configuration of the semiconductor laser of FIG. 1;
  • FIG. 7 is a view showing a modified example of the cross-sectional configuration of the semiconductor laser of FIG. 1;
  • FIG. 7 is a view showing a modified example of the cross-sectional configuration of the semiconductor laser of FIG. 1;
  • It is a figure showing an example of refractive index distribution when a composition block is provided in a carrier block layer. It is a figure showing an example of the relationship between the thickness of the graded layer of FIG.
  • FIG. 7 is a view showing a modified example of the cross-sectional configuration of the semiconductor laser of FIG. 1;
  • FIG. 7 is a view showing a modified example of the cross-sectional configuration of the semiconductor laser of FIG. 1;
  • FIG. 7 is a view showing a modified example of the cross-sectional configuration of the semiconductor laser of FIG. 1;
  • It is a figure showing an example of outline composition of a projector by which the above-mentioned semiconductor laser is applied.
  • It is a figure showing an example of a schematic structure of a display with which the above-mentioned semiconductor laser is applied.
  • It is a figure showing an example of the perspective view composition of the electronic equipment to which the above-mentioned semiconductor laser is applied.
  • FIG. 1 shows an example of the cross-sectional configuration of the semiconductor laser 1 according to the present embodiment.
  • the semiconductor laser 1 has a structure in which a semiconductor laminated portion 20 described later is sandwiched between a pair of resonator end faces from the resonator direction (the extending direction of the ridge portion 20A). Accordingly, the semiconductor laser 1 is a kind of so-called edge-emitting semiconductor laser.
  • the semiconductor laser 1 is provided with a semiconductor lamination portion 20 on a substrate 10.
  • the semiconductor stacked unit 20 includes, for example, the lower cladding layer 21, the lower guide layer 22, the active layer 23, the low concentration impurity layer 24, and the contact layer 25 in this order from the substrate 10 side.
  • the lower cladding layer 21 corresponds to one specific example of the “first cladding layer” of the present disclosure.
  • the semiconductor stacked unit 20 may further be provided with a layer (for example, a buffer layer) other than the above-described layers. Further, in the semiconductor lamination portion 20, the lower guide layer 22 may be omitted.
  • III-V nitride semiconductor refers to at least one of the 3B group elements in the short period periodic table (at least one element of Ga, Al, In, and B) It refers to one containing at least an N element of the 5B group elements in the periodic periodic table.
  • III-V nitride semiconductors include gallium nitride-based compounds containing Ga and N.
  • the gallium nitride-based compound includes, for example, GaN, AlGaN, AlGaInN and the like.
  • p-type impurities are doped.
  • the substrate 10 may be, for example, AlN, Al 2 O 3 (sapphire), SiC, Si, or Zr0.
  • the substrate 10 may be a III-V nitride semiconductor substrate such as a GaN substrate.
  • the crystal plane of the main surface of the GaN substrate may be any of a polar plane, a semipolar plane, and a nonpolar plane.
  • Polar planes are represented, for example, as ⁇ 0, 0, 0, 1 ⁇ or ⁇ 0, 0, 0 -1 ⁇ using plane indices.
  • the semipolar plane is, for example, ⁇ 2, 0, -2, 1 ⁇ , ⁇ 1, 0, -1, 1 ⁇ , ⁇ 2, 0, -2, -1 ⁇ , or ⁇ 1 using an area index.
  • 0, -1, -1 ⁇ is represented, for example, as ⁇ 1, 1, ⁇ 2, 0 ⁇ or ⁇ 1, ⁇ 1, 0, 0 ⁇ using an area index.
  • the lower cladding layer 21 is formed, for example, on the main surface of the substrate 10, and is formed of, for example, a semiconductor layer (n-type semiconductor layer) having n-type conductivity.
  • the lower cladding layer 21 is formed of, for example, one of a GaN layer, an AlGaN layer, and an AlGaInN layer, or at least two of these layers.
  • Si is used as a dopant for obtaining n-type conductivity.
  • the film thickness of the lower cladding layer 21 is, for example, 500 nm to 3000 nm.
  • the lower guide layer 22 is formed, for example, on the lower cladding layer 21 and is formed of, for example, an n-type semiconductor layer.
  • the lower guide layer 22 is formed of, for example, one of a GaN layer, an AlGaN layer, an InGaN layer, and an AlGaInN layer, or at least two of these layers.
  • Si is used as a dopant for obtaining n-type conductivity.
  • the film thickness of the lower guide layer 22 is, for example, 10 nm to 500 nm.
  • the lower guide layer 22 may be composed of a non-doped semiconductor layer.
  • the active layer 23 is formed, for example, on the lower guide layer 22.
  • the active layer 23 is provided between the lower guide layer 22 and the low concentration impurity layer 24.
  • the active layer 23 is formed, for example, by alternately stacking barrier layers and well layers, and has a multi-well structure.
  • the active layer 23 may have a multiple quantum well structure.
  • Each well layer is composed of a Ga, III-V nitride semiconductor.
  • Each well layer is formed of, for example, an n-type semiconductor layer.
  • Si is used as a dopant for obtaining n-type conductivity.
  • the film thickness of each well layer is, for example, 1 nm to 100 nm.
  • Each well layer may be constituted by a non-doped semiconductor layer.
  • the photon wavelength generated from each well layer is, for example, 430 nm to 550 nm.
  • Each barrier layer is made of a group III-V nitride semiconductor.
  • Each barrier layer is formed of, for example, an n-type semiconductor layer.
  • In each barrier layer for example, Si is used as a dopant for obtaining n-type conductivity.
  • the film thickness of each barrier layer is, for example, 1 nm to 100 nm.
  • Each barrier layer may be constituted by a non-doped semiconductor layer.
  • the band gap of the barrier layer is, for example, equal to or larger than the band gap which is the maximum in each well layer.
  • the low concentration impurity layer 24 is formed, for example, on the active layer 23, and is formed of, for example, an n-type semiconductor layer.
  • the low concentration impurity layer 24 is formed of, for example, one of a GaN layer, an AlGaN layer, an InGaN layer, and an AlGaInN layer, or at least two of these layers.
  • the low concentration impurity layer 24 contains an impurity.
  • the impurities refer to elements other than the elements constituting the III-V nitride semiconductor (specifically, at least one element of Ga, Al, In, and B and the N element).
  • the impurities are composed of, for example, at least one or more elements of Mg, C, Si, and O.
  • the concentration of the impurities contained in the low concentration impurity layer 24 is 5.0 ⁇ 10 17 cm ⁇ 3 or less, for example, 5.0 ⁇ 10 16 cm ⁇ 3 .
  • the film thickness of the low concentration impurity layer 24 is 250 nm or more and 1000 nm or less, preferably 500 nm or more and 1000 nm or less in a portion facing the ridge portion 20A.
  • the low concentration impurity layer 24 is provided not only at the bottom of the ridge portion 20A, but also at the side portion of the ridge portion 20A. Therefore, the film thickness of the portion immediately below the ridge portion 20A described later is larger than the film thickness of the portion beside the ridge portion 20A.
  • the concentration of the impurities contained in the low concentration impurity layer 24 By setting the concentration of the impurities contained in the low concentration impurity layer 24 to 5.0 ⁇ 10 17 cm -3 or less, it is possible to reduce or avoid the deterioration of the light output characteristics due to the light absorption caused by the impurities. . Further, by setting the film thickness of the low concentration impurity layer 24 to 250 nm or more in the portion facing the ridge portion 20A, deterioration of the light output characteristics due to light absorption of the contact layer 25 and the upper cladding layer 31 is reduced or avoided. can do. Further, by setting the film thickness of the low concentration impurity layer 24 to 1000 nm or less at the portion facing the ridge portion 20A, it is possible to reduce or avoid the deterioration of the electrical characteristics due to the increase of the resistance component of the semiconductor layer.
  • the impurity concentration and the composition ratio of constituent materials do not need to be uniform in the layer, and the low concentration impurity layer 24 may be a plurality of layers having different impurity concentrations and composition ratios of constituent materials. It may be configured. At that time, the total film thickness (total film thickness) is 250 nm or more and 1000 nm or less, preferably 500 nm or more and 1000 nm or less.
  • a layer (for example, a carrier block layer or a cladding layer) different from the low concentration impurity layer 24 and thinner than the low concentration impurity layer 24 may be inserted into the low concentration impurity layer 24.
  • the contact layer 25 is formed, for example, on the low concentration impurity layer 24, and is formed of, for example, a semiconductor layer (p-type semiconductor layer) having p-type conductivity.
  • the contact layer 25 is formed of, for example, one of a GaN layer, an AlGaN layer, and an AlGaInN layer, or at least two of these layers.
  • Mg is used as a dopant for obtaining p-type conductivity.
  • the film thickness of the contact layer 25 is, for example, 1 nm or more and 150 nm or less. At this time, the distance between the low concentration impurity layer 24 and the upper cladding layer 31 is equal to the film thickness of the contact layer 25 and is, for example, 1 nm or more and 150 nm or less.
  • a convex ridge portion 20A is formed in the upper portion of the semiconductor stacked portion 20, specifically, in a part of the low concentration impurity layer 24 and the contact layer 25.
  • the contact layer 25 is formed on the top surface of the ridge portion 20A.
  • the ridge portion 20A has a ridge shape extending in one direction (resonator direction) in the lamination plane of the semiconductor lamination portion 20 in a portion including the contact layer 25.
  • the ridge portion 20A is sandwiched by a pair of resonator end faces in the semiconductor lamination portion 20.
  • the length of the ridge portion 20A is, for example, 50 ⁇ m to 3000 ⁇ m.
  • the width (length in the direction orthogonal to the resonator direction) of the ridge portion 20A is, for example, 0.5 ⁇ m to 100 ⁇ m.
  • the ridge portion 20A is formed, for example, by etching away from the surface of the contact layer 25 to the middle of the low concentration impurity layer 24.
  • the side surface and the bottom portion of the ridge portion 20 ⁇ / b> A in the upper surface of the semiconductor lamination portion 20 are covered with the insulating layer 32.
  • the insulating layer 32 is made of, for example, SiO 2 .
  • the film thickness of the insulating layer 32 is, for example, 10 nm to 500 nm.
  • the semiconductor laser 1 further includes an upper cladding layer 31, an insulating layer 32, and an upper electrode layer 33 on the semiconductor multilayer portion 20, and a lower electrode layer 34 on the back surface side of the semiconductor multilayer portion 20.
  • the upper cladding layer 31 corresponds to one specific example of the “second cladding layer” of the present disclosure.
  • the upper cladding layer 31 is formed on the semiconductor lamination portion 20 and in contact with the upper surface of the ridge portion 20A.
  • the upper cladding layer 31 is formed on the contact layer 25.
  • the upper cladding layer 31 is formed of a transparent conductive material.
  • a transparent conductive material which comprises the upper clad layer 31 ITO (Indium Tin Oxide), ITiO (Indium Titanium Oxide), etc. are mentioned.
  • the film thickness of the upper cladding layer 31 is 10 nm or more and 500 nm or less.
  • the upper cladding layer 31 may be electrically connected to the contact layer 25, and the layer configuration is not limited to the above configuration.
  • the upper cladding layer 31 may be in contact with the entire top surface of the contact layer 25 or may be in contact with only a part of the top surface of the contact layer 25.
  • the upper electrode layer 33 is formed on the upper cladding layer 31.
  • the upper electrode layer 33 has, for example, a structure in which a Ti layer, a Pt layer, and an Au layer are stacked in this order from the side closer to the upper cladding layer 31.
  • the film thickness of the Ti layer is, for example, 2 nm to 100 nm.
  • the film thickness of the Pt layer is, for example, 10 nm to 300 nm.
  • the thickness of the Au layer is, for example, 10 nm to 300 nm.
  • the upper electrode layer 33 may be electrically connected to the upper cladding layer 31, and the layer configuration is not limited to the above-described configuration.
  • the upper electrode layer 33 may be in contact with the entire upper surface of the upper cladding layer 31 or may be in contact with only a part of the upper surface of the upper cladding layer 31.
  • the lower electrode layer 34 is formed, for example, in contact with the back surface of the substrate 10.
  • the lower electrode layer 34 has, for example, a structure in which a Ti layer and an Al layer are stacked in this order from the side close to the substrate 10.
  • the film thickness of the Ti layer is, for example, 5 nm to 50 nm.
  • the film thickness of the Al layer is, for example, 10 nm to 300 nm.
  • the lower electrode layer 34 may be electrically connected to the substrate 10, and the layer configuration thereof is not limited to the above configuration.
  • the lower electrode layer 34 may be in contact with the entire back surface of the substrate 10 or may be in contact with only a part of the back surface of the substrate 10.
  • a substrate 10 made of, for example, GaN is prepared.
  • the lower cladding layer 21 and the lower guide layer 22 are epitaxially grown, for example, at a growth temperature of 1050 ° C. on the surface of the substrate 10 by, for example, MOCVD (Metal Organic Chemical Vapor Deposition; metal organic chemical vapor deposition) method.
  • MOCVD Metal Organic Chemical Vapor Deposition; metal organic chemical vapor deposition
  • the active layer 23 is epitaxially grown, for example, at a growth temperature of 700 ° C. by, eg, MOCVD.
  • the low concentration impurity layer 24 and the contact layer 25 are epitaxially grown, for example, at a growth temperature of 1050 ° C. by the MOCVD method.
  • trimethylgallium ((CH 3 ) 3 Ga) is used as a gallium source gas, and trimethyl aluminum ((CH 3 ) 3 Al) and indium are a source gas for aluminum.
  • trimethyl indium ((CH 3 ) 3 In).
  • ammonia (NH 3 ) is used as a nitrogen source gas.
  • monosilane SiH 4
  • a resist coating film is formed on the semiconductor lamination portion 20 with the region where the upper cladding layer 31 is to be formed as an opening, and the upper cladding layer 31 is formed by, for example, vacuum evaporation or sputtering. Subsequently, at least a part of the upper cladding layer 31, the contact layer 25, and the low concentration impurity layer 24 is removed by etching, for example, by the RIE method. Thus, the ridge portion 20A is formed, and the upper cladding layer 31 is formed on the ridge portion 20A.
  • the insulating layer 32 is formed on the surface of the semiconductor multilayer portion 20 exposed by the above-described etching using, for example, a vacuum evaporation method or sputtering method, and the lift-off method is formed on the surfaces of the upper cladding layer 31 and the insulating layer 32.
  • the upper electrode layer 33 is formed.
  • the lower electrode layer 34 is formed on the back surface of the substrate 10 by, for example, a lift-off method.
  • the substrate 10 is cut into a bar shape, and a coating film for controlling the reflectance is formed on the exposed end face portion.
  • the semiconductor laser 1 is manufactured by cutting out the elements from the substrate 10 cut into the bar shape and forming the elements into chips.
  • the optical waveguide region 20B is generated in a region directly below the ridge portion 20A with the active layer 23 at the center.
  • the boundary of the light guiding region 20B (the portion indicated by the broken line in FIG. 1) is a region where the light intensity ratio is 0.007 with respect to the maximum value of the light intensity in the light guiding region 20B.
  • the boundary of the light guiding region 20B is defined by the above definition because the light intensity ratio at the interface of the upper cladding layer 31 and the light absorption loss are in the relationship as shown in FIG. Do.
  • FIG. 2 shows that when the light intensity ratio at the interface of the upper cladding layer 31 becomes larger than 0.007, the light absorption loss rapidly increases and the laser characteristics deteriorate. That is, when the upper cladding layer 31 is in contact with the light guiding region 20B, the light absorption loss is very large, and the laser characteristics are degraded. On the other hand, when the upper cladding layer 31 is at a distance from the light guiding region 20B, the light absorption loss is small, and the deterioration of the laser characteristics can be suppressed.
  • FIG. 3 shows an example of the cross-sectional configuration of a general nitride-based semiconductor laser 100 (semiconductor laser 100 according to comparative example A).
  • semiconductor laser 100 semiconductor laser 100 according to comparative example A.
  • an AlGaN layer is generally used as a cladding layer in order to obtain a step of refractive index required to realize light confinement in the stacking direction.
  • the semiconductor stacked portion 120 is provided on the substrate 10, and the upper guide layer 121 and the upper cladding layer 122 are provided instead of the low concentration impurity layer 24 according to the present embodiment. . Further, in the semiconductor laser 100, an upper electrode layer 131 made of ITO is provided on the ridge portion 120A instead of the upper cladding layer 31.
  • the AlGaN cladding layer needs to carry out carrier transport while being required to have a low refractive index. Therefore, an AlGaN clad layer (lower clad layer 21) having n-type conductivity and an AlGaN clad layer (upper clad layer 122) having p-type conductivity on the other side are formed on both sides of the active layer 23.
  • Mg is often doped into the upper cladding layer 122 as an acceptor in order to realize p-type conductivity.
  • Mg in AlGaN has a large activation energy for ionization, and it is difficult to generate a high concentration of hole carriers. Therefore, the resistance of the upper cladding layer 122 becomes high, which causes the driving voltage of the semiconductor laser 100 to rise, and the power conversion efficiency of the semiconductor laser 100 is lowered.
  • FIG. 4 schematically illustrates the cross-sectional configuration of the semiconductor laser 200 according to the comparative example B.
  • the upper cladding layer 122 and the ridge portion 120A are not provided, the contact layer 123 contacts the upper guide layer 121, and the upper cladding layer 132 made of ITO instead of the upper electrode layer 131 is It is provided.
  • an insulating layer 124 is provided around the upper cladding layer 132.
  • the refractive index of ITO is, for example, about 2.0 for a wavelength of 450 nm, and has a value sufficiently smaller than the refractive index 2.5 of the upper guide layer 121. Therefore, the upper cladding layer 132 functions as a cladding layer that realizes a step of refractive index to realize light confinement in the stacking direction. In the semiconductor laser 200, since it is not necessary to use the p-type conductive AlGaN cladding layer having high resistance, the effect of reducing the driving voltage can be obtained.
  • the ridge portion 120A is formed, and the insulating layer 32 is formed around the ridge portion 120A.
  • the insulating layer 32 is formed of, for example, SiO 2 , and its refractive index is sufficiently smaller than that of the nitride semiconductor, for example, 1.46 for a wavelength of 450 nm. Therefore, it is possible to obtain the step of the refractive index necessary to realize the light confinement in the width direction of the ridge portion 120A, and it is possible to realize the stable laser operation.
  • the upper cladding layer 132 is formed on the contact layer 123, and the insulating layer 124 is formed in the region where the upper cladding layer 132 is not formed.
  • the refractive index of the insulating layer 124 is sufficiently larger than, for example, the refractive index 2.0 for the wavelength of 1.46 and the upper cladding layer 132 for the wavelength 450 nm. Therefore, even if the ridge portion is not formed, light confinement in the in-plane direction can be realized, stable laser operation can be obtained, and cost reduction and a good yield can be obtained.
  • the upper cladding layer 132 has finite light absorption for light with a wavelength of, for example, 430 nm to 550 nm. Therefore, in the semiconductor laser 200, in the optical transverse mode formed in the resonator, the light intensity permeating into the upper cladding layer 132 is large (see the optical waveguide region 220B in FIG. 4). As a result, since the loss due to the light absorption of the upper cladding layer 132 is received, the characteristic improvement as the semiconductor laser 200 can not be sufficiently obtained. In addition, in the structure of the semiconductor lamination portion 220, light confinement in the in-plane direction of the lamination becomes insufficient, and the operation of the semiconductor laser 200 may become unstable.
  • FIG. 5 schematically shows a cross-sectional configuration of a semiconductor laser 300 according to Comparative Example C.
  • a thick upper guide layer 321 is provided instead of the thin upper guide layer 121.
  • the light intensity that leaks into the upper cladding layer 132 can be reduced (see the optical waveguide region 320B in FIG. 5).
  • the upper cladding layer 132 is far away from the active layer 23, the light confinement in the in-plane direction of the laminated layer becomes insufficient, and there is a possibility that a stable laser operation can not be obtained.
  • the upper cladding layer 31 is formed of a transparent conductive material. Furthermore, in the low concentration impurity layer 24 provided between the active layer 23 and the contact layer 25, the impurity concentration is 5.0 ⁇ 10 17 cm ⁇ 3 or less, and the total thickness of the low concentration impurity layer 24 is Is 250 nm or more and 1000 nm or less. Furthermore, the distance between the low concentration impurity layer 24 and the upper cladding layer 31 is 150 nm or less. Thereby, the light absorption by the transparent conductive material is suppressed, and further, even in the case where the thick clad layer made of Mg-doped AlGaN is not provided, the upper clad layer 31 formed of the transparent conductive material Be trapped. In the present embodiment, a band-like ridge portion 20A is further formed. Thereby, light is confined also in the lateral direction. As a result, the drive voltage can be suppressed.
  • the upper cladding layer 31 is formed of a transparent conductive material. Furthermore, in the low concentration impurity layer 24 provided between the active layer 23 and the contact layer 25, the impurity concentration is 5.0 ⁇ 10 17 cm ⁇ 3 or less. Furthermore, the upper cladding layer 31 is provided at a distance from the optical waveguide region 20B generated in the semiconductor multilayer portion 20 when the semiconductor laser 1 is driven. That is, the light intensity ratio to the maximum value of the light intensity at the boundary position on the side closer to the active layer 23 of the upper cladding layer 31 is smaller than 0.007.
  • the light absorption by the transparent conductive material is suppressed, and further, even in the case where the thick clad layer made of Mg-doped AlGaN is not provided, the upper clad layer 31 formed of the transparent conductive material Be trapped.
  • a band-like ridge portion 20A is further formed. Thereby, light is confined also in the lateral direction. As a result, the drive voltage can be suppressed.
  • FIG. 6 shows an example of the IV characteristics of the semiconductor laser 100 according to Comparative Example A, the semiconductor laser 200 according to Comparative Example B, and the semiconductor laser 1 according to the example.
  • the results of FIG. 6 are derived by a semiconductor simulator.
  • the impurity concentration of the low concentration impurity layer 24 is set to 2.0 ⁇ 10 16 cm ⁇ 3 and the film thickness of the low concentration impurity layer 24 is set to 500 nm.
  • the impurity concentration of the upper guide layer 121 is 2.0 ⁇ 10 16 cm ⁇ 3 and the film thickness of the upper guide layer 121 is 200 nm. It can be seen from FIG. 6 that in the example, the drive voltage is lower than in Comparative Examples A and B.
  • FIG. 7 shows an example of the IL characteristics of the semiconductor laser 100 according to Comparative Example A, the semiconductor laser 200 according to Comparative Example B, and the semiconductor laser 1 according to the example. It can be seen from FIG. 7 that in the example, higher light output is obtained as compared with Comparative Examples A and B.
  • FIG. 8 shows an example of the L-WPE (power conversion efficiency) characteristics of the semiconductor laser 100 according to the comparative example A, the semiconductor laser 200 according to the comparative example B, and the semiconductor laser 1 according to the example. It can be seen from FIG. 8 that in the example, higher power conversion efficiency is obtained as compared with Comparative Examples A and B.
  • the semiconductor stacked portion 20 (the lower cladding layer 21, the active layer 23, the low concentration impurity layer 24 and the contact layer 25) is formed of a nitride semiconductor.
  • the upper cladding layer 31 is formed of ITO or ITiO.
  • the driving voltage can be suppressed as compared with the case where a thick film cladding layer made of Mg-doped AlGaN is provided.
  • FIGS. 9 to 14 show a modification of the cross-sectional configuration of the semiconductor laser 1.
  • the contact layer 25 may be formed of a thick film, for example, as shown in FIG.
  • the ridge portion 20A may be formed, for example, by etching a part of the contact layer 25.
  • the film thickness of the portion immediately below the ridge portion 20A may be larger than the film thickness of the portion beside the ridge portion 20A.
  • the light absorption by the transparent conductive material is suppressed, and, for example, the upper clad layer formed of the transparent conductive material without providing a thick clad layer made of Mg-doped AlGaN.
  • Light 31 is confined in the stacking direction by 31. Furthermore, the light is confined also in the lateral direction by the ridge portion 20A. As a result, the drive voltage can be suppressed.
  • the semiconductor laser 1 has, for example, the carrier block layer 26 which is a layer different from the low concentration impurity layer 24 with respect to the low concentration impurity layer 24 as shown in FIG. It may be inserted. At this time, the carrier block layer 26 is inserted between the active layer 23 and the contact layer 25. At this time, in the low concentration impurity layer 24, the film thickness of the portion immediately below the ridge portion 20A is thicker than the film thickness of the portion beside the ridge portion 20A. The carrier block layer 26 prevents carriers injected from the substrate 10 side from penetrating the active layer 23 into the ridge portion 20A. By providing the carrier block layer 26, the utilization efficiency of carriers can be improved, and the power conversion efficiency of the semiconductor laser 1 can be improved.
  • the carrier block layer 26 is configured of, for example, a p-type semiconductor layer.
  • the carrier block layer 26 is formed of, for example, one of a GaN layer, an AlGaN layer, an InGaN layer, and an AlGaInN layer, or at least two of these layers.
  • Mg is used as a dopant for obtaining p-type conductivity.
  • the film thickness of the carrier block layer 26 is, for example, 3 nm to 50 nm.
  • a carrier block layer 26 which is a layer different from the low concentration impurity layer 24 is inserted into the low concentration impurity layer 24.
  • the light absorption by the transparent conductive material is suppressed, and, for example, the upper clad layer formed of the transparent conductive material without providing a thick clad layer made of Mg-doped AlGaN.
  • Light 31 is confined in the stacking direction by 31. Furthermore, the light is confined also in the lateral direction by the ridge portion 20A. As a result, the drive voltage can be suppressed.
  • the ridge portion 20A may be formed by etching a part of the contact layer 25, the carrier block layer 26, and the low concentration impurity layer 24. .
  • the film thickness of the portion immediately below the ridge portion 20A is thicker than the film thickness of the portion beside the ridge portion 20A. There is. With such a configuration, the light confinement in the lateral direction by the ridge portion 20A is further strengthened, and good light output characteristics can be obtained.
  • the transparent conductive material is suppressed, and furthermore, light is confined in the stacking direction by the upper cladding layer 31 formed of the transparent conductive material, even without providing a thick cladding layer made of Mg-doped AlGaN, for example. .
  • the drive voltage can be suppressed.
  • the composition of the carrier block layer 25 may be inclined so that the band gap energy of the carrier block layer 26 decreases toward the contact layer 25 side.
  • the carrier block layer 26 is formed of the graded layer 26A in which the composition of the carrier block layer 25 is inclined so that the band gap energy decreases toward the contact layer 25 side.
  • the composition gradient (graded layer 26A) of the carrier block layer 26 suppresses electron overflow. it can.
  • the concentration of holes collected at the interface between the carrier block layer 26 and the contact layer 25 can also be reduced by the composition gradient of the carrier block layer 25 (graded layer 26A).
  • graded layer 26A the composition gradient of the carrier block layer 25
  • the graded layer 26A is made thicker, the amount of decrease in the hole concentration at the interface between the carrier block layer 26 and the contact layer 25 increases.
  • the ridge portion 20A is formed by etching the carrier block layer 26.
  • holes accumulated at the interface between the carrier block layer 26 and the contact layer 25 disappear due to non-radiative recombination that occurs on the surface of the etched ridge portion 20A.
  • Holes accumulated at the interface between the carrier block layer 26 and the contact layer 25 can easily move in the ridge portion 20A as a two-dimensional electron gas. Therefore, as the concentration of holes collected at the interface between the carrier block layer 26 and the contact layer 25 increases, the number of holes eliminated in the non-emission recombination process increases, and the light emission efficiency decreases.
  • the composition of the carrier block layer 26 is inclined so that the band gap energy of the carrier block layer 26 decreases toward the contact layer 25.
  • the concentration of holes collected at the interface decreases.
  • the carrier block layer 26 may be inserted between the active layer 23 and the low concentration impurity layer 24. Even in this case, the light absorption by the transparent conductive material is suppressed, and, for example, the upper clad layer formed of the transparent conductive material without providing a thick clad layer made of Mg-doped AlGaN.
  • Light 31 is confined in the stacking direction by 31. Furthermore, the light is confined also in the lateral direction by the ridge portion 20A. As a result, the drive voltage can be suppressed.
  • the carrier block layer 26 may be inserted between the low concentration impurity layer 24 and the contact layer 25.
  • the contact layer 25 may be a thick film, and a part of the contact layer 25 may be etched to form the ridge portion 20A, and the carrier block layer 26 may be formed in contact with the contact layer 25. .
  • the light absorption by the transparent conductive material is suppressed, and, for example, the upper clad layer formed of the transparent conductive material without providing a thick clad layer made of Mg-doped AlGaN.
  • Light 31 is confined in the stacking direction by 31. Furthermore, the light is confined also in the lateral direction by the ridge portion 20A. As a result, the drive voltage can be suppressed.
  • the semiconductor laser 1 may have the upper cladding layer 27 between the contact layer 25 and the low concentration impurity layer 24 as shown in FIG. 16, for example.
  • the upper cladding layer 27 is, for example, a Mg-doped AlGaN layer, and has a thickness smaller than that of the low concentration impurity layer 24 in a portion facing the ridge portion 20A.
  • the total film thickness of the contact layer 25 and the upper cladding layer 31 is, for example, 150 nm or less.
  • the light absorption by the transparent conductive material is suppressed, and, for example, the upper clad layer formed of the transparent conductive material without providing a thick clad layer made of Mg-doped AlGaN.
  • Light 31 is confined in the stacking direction by 31. Furthermore, the light is confined also in the lateral direction by the ridge portion 20A. As a result, the drive voltage can be suppressed.
  • the semiconductor stacked unit 20 is made of a III-V group semiconductor including any one of As, B, Sb, and P, or at least two of them. It may be Even in this case, the light is confined in the stacking direction by the upper cladding layer 31, and the light is confined in the lateral direction by the ridge portion 20A. As a result, the drive voltage can be suppressed.
  • a metal layer or a resin layer may be provided instead of the insulating layer 32.
  • the insulating layer 32 is omitted, and further, the portion around the ridge portion 20A and the bottom portion of the semiconductor laminated portion 20 (that is, the portion in contact with the insulating layer 32). ) May be exposed to the atmosphere. Even in this case, the light is confined in the stacking direction by the upper cladding layer 31, and the light is confined in the lateral direction by the ridge portion 20A. As a result, the drive voltage can be suppressed.
  • FIG. 17 illustrates an example of a schematic configuration of the projector 2.
  • the projector 2 is an apparatus for projecting an image based on an image signal Din input from the outside on a screen or the like.
  • the projector 2 includes a video signal processing circuit 41, a laser drive circuit 42, a light source unit 43, a scanner unit 44 and a scanner drive circuit 45.
  • the video signal processing circuit 41 generates a projection video signal for each color based on the video signal Din.
  • the laser drive circuit 42 controls the peak value of the current pulse applied to the light sources 43R, 43G, 43B described later based on the projection video signal for each color.
  • the light source unit 43 has a plurality of light sources, for example, three light sources 43R, 43G, and 43B.
  • the three light sources 43R, 43G, and 43B are used, for example, as laser light sources that emit laser light of red (R), green (G), and blue (B) wavelengths.
  • At least one of the light sources 43B and 43G includes the semiconductor laser 1 according to the above-described embodiment and the modification thereof.
  • the laser beams emitted from the three light sources 43R, 43G, and 43B for example, are collimated into substantially parallel beams by a collimator lens, and then bundled into one laser beam by beam splitters 43sR, 43sG, and 43sB.
  • the beam splitter 43sR reflects, for example, red light.
  • the beam splitter 43sG reflects, for example, green light and transmits red light.
  • the beam splitter 43sB reflects, for example, blue light and transmits red light and green light.
  • the scanner unit 44 is configured using, for example, one two-axis scanner.
  • the incident laser light is modulated to the irradiation angle in the horizontal and vertical directions by the two-axis scanner and then projected onto the screen.
  • the scanner unit 44 may be configured to scan horizontally and vertically using two single-axis scanners.
  • the scanner unit 44 has a sensor for detecting an irradiation angle such as a two-axis scanner, and the sensor outputs angle signals of horizontal and vertical respectively. These angle signals are input to the scanner drive circuit 45.
  • the scanner drive circuit 45 drives the scanner unit 44 to a desired irradiation angle based on, for example, the horizontal angle signal and the vertical angle signal input from the scanner unit 44.
  • the semiconductor laser 1 according to the above-described embodiment and its modification is used. Thereby, high emission intensity can be obtained with low power consumption.
  • FIG. 18 illustrates a schematic configuration example of the display device 3.
  • the display device 3 includes, for example, a pixel array unit 40, a controller 50, and a driver 60.
  • the pixel array unit 40 includes a plurality of display pixels 40A arranged in a matrix.
  • the controller 50 and the driver 60 drive each display pixel 40A based on the video signal Din and the synchronization signal Tin input from the outside.
  • the pixel array unit 40 displays an image based on the externally input video signal Din and the synchronization signal Tin by active matrix driving of each display pixel 40A by the controller 50 and the driver 60.
  • the pixel array unit 40 includes a plurality of scanning lines extending in the row direction, a plurality of signal lines extending in the column direction, and a plurality of scanning lines and signal lines crossing each other. And the display pixel 40A.
  • the scanning line is used to select each display pixel 40A, and supplies a selection pulse for selecting each display pixel 40A for each predetermined unit (for example, pixel row) to each display pixel 40A.
  • the signal line is used to supply a signal voltage corresponding to the video signal Din to each display pixel 40A, and supplies a data pulse including the signal voltage to each display pixel 40A.
  • Each display pixel 40A has a plurality of sub-pixels each including a semiconductor laser.
  • at least one of the semiconductor lasers emitting blue light and green light among the plurality of sub-pixels is the semiconductor laser 1 according to the above-described embodiment and its modification.
  • the driver 60 includes, for example, a horizontal selector 61 and a light scanner 62.
  • the horizontal selector 61 applies an analog signal voltage input from the video signal processing circuit 51 to each signal line, for example, in response to (in synchronization with) an input of a control signal from the controller 50.
  • the light scanner 62 scans the plurality of display pixels 40A in predetermined units. Specifically, the write scanner 62 sequentially outputs selection pulses to each scanning line in one frame period.
  • the write scanner 62 executes the writing of the signal voltages in a desired order by, for example, selecting (in synchronization with) a plurality of scanning lines in a predetermined sequence in response to (in synchronization with) input of a control signal from the controller 50.
  • the controller 50 includes, for example, a video signal processing circuit 51, a timing generation circuit 52, and a power supply circuit 53.
  • the video signal processing circuit 51 performs predetermined correction on the digital video signal Din input from the outside, and generates a signal voltage based on the video signal obtained thereby.
  • the video signal processing circuit 51 outputs, for example, the generated signal voltage to the horizontal selector 61.
  • the timing generation circuit 52 controls each circuit in the driver 60 to operate in conjunction.
  • the timing generation circuit 52 outputs a control signal to each circuit in the driver 60, for example, according to (in synchronization with) the synchronization signal Tin input from the outside.
  • the power supply circuit 53 generates and supplies various fixed voltages required for various circuits such as the horizontal selector 61, the write scanner 62, the video signal processing circuit 51, the timing generation circuit 52, and the power supply circuit 53.
  • the semiconductor laser 1 according to the above-described embodiment or the variation thereof is used in each display pixel 40A. Thereby, high emission intensity can be obtained with low power consumption.
  • FIG. 19 illustrates an example of a perspective view of the electronic device 4.
  • the electronic device 4 is, for example, a portable terminal provided with a display surface on the main surface of a plate-like casing.
  • the electronic device 4 includes, for example, the display device 3 according to the third embodiment at the position of the display surface.
  • the pixel array unit 40 of the display device 3 is disposed on the display surface of the electronic device 4.
  • the semiconductor laser 1 according to the above-described embodiment or the variation thereof is used in each display pixel 40A. Thereby, high emission intensity can be obtained with low power consumption.
  • the display device 3 is a video signal input from the outside, such as a television device, a digital camera, a notebook personal computer, a portable terminal device such as a mobile phone or a video camera, or
  • the generated video signal can be applied to a display device of an electronic device in any field that displays as an image or a video.
  • the present disclosure can have the following configurations.
  • the semiconductor laser according to (1) wherein the first cladding layer, the active layer, the low concentration impurity layer, and the contact layer are all formed of a nitride-based semiconductor material.
  • the transparent conductive material is ITO or ITiO.
  • a carrier block layer interposed between the active layer and the contact layer, In the low concentration impurity layer, the film thickness of the portion directly below the ridge shape is thicker than the film thickness of the side portion of the ridge shape according to any one of (1) to (4) Semiconductor laser.
  • a semiconductor laser wherein a light intensity ratio to a maximum value of light intensity is smaller than 0.007 at a boundary position on the side closer to the active layer of the second cladding layer.
  • the semiconductor laser has a semiconductor laser as a light source,
  • the semiconductor laser is A first cladding layer, an active layer, one or more lightly doped impurity layers, a contact layer, and a second cladding layer formed of a transparent conductive material in this order, and in a portion including the contact layer
  • An electronic device wherein a distance between the low concentration impurity layer closest to the second cladding layer and the second cladding layer is 150 nm or less.
  • the semiconductor laser is A first cladding layer, an active layer, one or a plurality of low concentration impurity layers having an impurity concentration of 5.0 ⁇ 10 17 cm ⁇ 3 or less, a contact layer, and a second cladding layer formed of a transparent conductive material in this order
  • a semiconductor laser including a semiconductor laminated portion having a ridge shape extending in one direction in the laminated plane in a portion including the contact layer,
  • the second cladding layer is provided at a distance from an optical waveguide region generated in the semiconductor multilayer portion when the semiconductor laser is driven.
  • the electronic device whose light intensity ratio with respect to the maximum value of the light intensity in the boundary position by the side near the said active layer of a said 2nd cladding layer is smaller than 0.007.
  • the first semiconductor laser, the second semiconductor laser, the first electronic device, and the second electronic device According to the first semiconductor laser, the second semiconductor laser, the first electronic device, and the second electronic device according to an embodiment of the present disclosure, light absorption by the transparent conductive material is suppressed, and further, for example, Mg doped Even without providing a thick film cladding layer of AlGaN, light can be confined in the stacking direction by the second cladding layer formed of a transparent conductive material, and light can be confined also in the lateral direction by the strip ridge. Therefore, the drive voltage can be suppressed.
  • the effects of the present disclosure are not necessarily limited to the effects described herein, but may be any of the effects described herein.

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