WO2022158301A1 - 面発光レーザ、電子機器及び面発光レーザの製造方法 - Google Patents
面発光レーザ、電子機器及び面発光レーザの製造方法 Download PDFInfo
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Definitions
- this technology relates to surface emitting lasers, electronic devices, and methods of manufacturing surface emitting lasers.
- a surface-emitting laser in which an active layer is arranged between first and second multilayer film reflectors.
- Some surface-emitting lasers have a tunnel junction, an active layer, and a current confinement layer laminated in this order between first and second multilayer reflectors (see, for example, Patent Document 1).
- the main object of the present technology is to provide a surface-emitting laser that can suppress a decrease in luminous efficiency.
- the present technology includes first and second multilayer film reflectors, a plurality of active layers stacked between the first and second multilayer reflectors; a tunnel junction disposed between two active layers adjacent in the stacking direction among the plurality of active layers; an oxidized constricting layer disposed between one of the two adjacent active layers and the tunnel junction;
- a surface-emitting laser comprising: The one active layer may be arranged at a position farther from the emission surface of the surface emitting laser than the other active layer of the two adjacent active layers. The one active layer may be arranged at a position closer to the other of the first and second multilayer film reflectors, which is farther from the exit surface than the one closer to the exit surface.
- the one active layer may be arranged at a position closer to the other of the first and second multilayer film reflectors, which is closer to the exit surface than to the other which is farther from the exit surface.
- the one active layer may be arranged closer to the emission surface of the surface emitting laser than the other active layer of the two adjacent active layers.
- the one active layer may be arranged at a position closer to the other of the first and second multilayer film reflectors, which is farther from the exit surface than the one closer to the exit surface.
- the one active layer may be arranged at a position closer to the other of the first and second multilayer film reflectors, which is closer to the exit surface than to the other which is farther from the exit surface.
- the plurality of active layers is at least three active layers, and the tunnel junction is disposed between two adjacent active layers of each set of at least two sets of two adjacent active layers among the plurality of active layers.
- the oxidized constriction layer may be arranged therebetween.
- the at least three active layers include first, second and third active layers, the first, second and third active layers are stacked in this order between the first and second active layers.
- a first tunnel junction which is the tunnel junction, is arranged; a second tunnel junction, which is the tunnel junction, is arranged between the second and third active layers;
- the oxidized constriction layer may be arranged between and/or between the second active layer and the second tunnel junction.
- the first active layer may be the active layer arranged at the farthest position from the emission surface of the surface emitting laser among the plurality of active layers.
- a first oxidized constricting layer which is the oxidized constricting layer, may be arranged between the first active layer and the first tunnel junction.
- a second oxidized constricting layer which is the oxidized constricting layer, may be arranged between the second active layer and the second tunnel junction.
- the oxidized constriction layer may not be arranged between the second active layer and the second tunnel junction.
- Another oxidized constricting layer may be disposed inside the first and second multilayer film reflectors closer to the emission surface of the surface emitting laser.
- Both the oxidized constricting layer and the another oxidized constricting layer may be formed by selectively oxidizing a layer made of an AlGaAs-based compound semiconductor.
- the oxidized constricting layer and the another oxidized constricting layer may differ from each other in Al composition and/or optical thickness.
- the tunnel junction may have a layered structure in which a p-type semiconductor layer and an n-type semiconductor layer are laminated, and the oxidized constricting layer may be arranged on the p-type semiconductor layer side.
- the one active layer, the tunnel junction and the oxidized constricting layer may be arranged within an optical thickness of 3 ⁇ /4.
- the present technology also provides an electronic device including the surface emitting laser.
- a structure including a laminated structure in which a first active layer, a selectively oxidized layer, a tunnel junction, and a second active layer are laminated in this order is laminated on a first multilayer reflector, and a step of laminating at least the second multilayer film reflector to produce a laminate; forming a mesa by etching the laminate until at least the side surface of the selectively oxidized layer is exposed; a step of selectively oxidizing the selectively oxidized layer from the side surface to form an oxidized constricting layer;
- a method of manufacturing a surface emitting laser is also provided, comprising:
- FIG. 1 is a cross-sectional view showing a configuration of a surface emitting laser according to a first embodiment of the present technology
- FIG. 4 is a flowchart for explaining a method for manufacturing a surface emitting laser according to the first embodiment of the present technology
- FIG. 3 is a flowchart for explaining the first step (laminate production process 1) in FIG. 2
- FIG. FIG. 4 is a first step diagram of FIG. 3
- FIG. 4 is a flow chart for explaining a second step (resonator base forming step 1) of FIG. 3
- FIG. FIG. 6 is a first stacking process diagram of FIG. 5
- FIG. 6 is a second stacking process diagram of FIG. 5
- FIG. 6 is a view of the third lamination step of FIG. 5;
- FIG. 4 is a flowchart for explaining a method for manufacturing a surface emitting laser according to the first embodiment of the present technology
- FIG. 3 is a flowchart for explaining the first step (laminate production process 1) in FIG. 2
- FIG. 6 is a fourth stacking step diagram of FIG. 5;
- FIG. 6 is a view of the fifth lamination step of FIG. 5; It is a 3rd process drawing of FIG. FIG. 3 is a second process diagram of FIG. 2; It is a 3rd process drawing of FIG. FIG. 3 is a fourth process diagram of FIG. 2;
- FIG. 3 is a fifth process diagram of FIG. 2;
- FIG. 3 is a sixth process diagram of FIG. 2;
- FIG. 3 is a seventh process diagram of FIG. 2; It is a sectional view showing composition of a surface emitting laser concerning modification 1 of a 1st embodiment of this art. It is a sectional view showing composition of a surface emitting laser concerning modification 2 of a 1st embodiment of this art.
- FIG. 25 is a flowchart for explaining the first step (laminated body generation process 2) of FIG. 24; FIG. FIG.
- FIG. 26 is a flow chart for explaining a second step (resonator base forming step 2) of FIG. 25;
- FIG. FIG. 27 is a third stacking process diagram of FIG. 26;
- FIG. 27 is a fourth stacking step diagram of FIG. 26;
- FIG. 27 is a view of the fifth lamination process of FIG. 26;
- FIG. 27 is a view of the sixth lamination process of FIG. 26;
- FIG. 27 is a view of the seventh lamination process of FIG. 26;
- FIG. 26 is a third process diagram of FIG. 25;
- FIG. 25 is a second step diagram of FIG. 24; 24. It is a 3rd process drawing of FIG.
- FIG. 25 is a fourth step diagram of FIG. 24;
- FIG. 25 is a fifth step diagram of FIG. 24;
- FIG. 25 is a sixth process diagram of FIG. 24; 24. It is the 7th process drawing of FIG. It is a sectional view showing composition of a surface emitting laser concerning modification 1 of a 2nd embodiment of this art. It is a sectional view showing composition of a surface emitting laser concerning modification 2 of a 2nd embodiment of this art. It is a sectional view showing composition of a surface emitting laser concerning modification 3 of a 2nd embodiment of this art.
- FIG. 12 is a cross-sectional view showing a configuration of a surface-emitting laser according to Modification 4 of the second embodiment of the present technology; 1 is a plan view showing a configuration example of a surface emitting laser to which the present technology can be applied; FIG.
- FIG. 44A is a cross-sectional view taken along the line XX of FIG. 43.
- FIG. 44B is a cross-sectional view taken along the line YY of FIG. 43.
- FIG. It is a figure which shows the application example to the distance measuring device of the surface emitting laser which concerns on each embodiment of this technique, and its modification.
- 1 is a block diagram showing an example of a schematic configuration of a vehicle control system;
- FIG. 4 is an explanatory diagram showing an example of the installation position of the distance measuring device;
- FIG. 1 is a cross-sectional view showing the configuration of a surface-emitting laser 100 according to a first embodiment of the present technology.
- FIG. 1 shows the configuration of a surface-emitting laser 100 according to a first embodiment of the present technology.
- the surface-emitting laser 100 as shown in FIG. 1, 104-2), a tunnel junction 108, and an oxide constriction layer 106.
- FIG. 1 the surface-emitting laser 100, as shown in FIG. 1, 104-2), a tunnel junction 108, and an oxide constriction layer 106.
- Each component of the surface emitting laser 100 is formed on a substrate 101 (semiconductor substrate) as an example.
- the first and second multilayer film reflectors 102 and 112 are stacked on the substrate 101, for example.
- the second multilayer reflector 112 is arranged above the first multilayer reflector 102 .
- the first and second active layers 104-1, 104-2 are stacked together between the first and second multilayer reflectors 102, 112.
- the tunnel junction 108 is arranged between first and second active layers 104-1 and 104-2, which are two adjacent active layers in the stacking direction (vertical direction) of the plurality of active layers.
- the oxidized constricting layer 106 is, for example, the first active layer 104-1, which is one of the two active layers adjacent to each other in the stacking direction, that is, the first and second active layers 104-1 and 104-2, and the tunnel layer. It is arranged between junction 108 .
- the first multilayer reflector 102 on the substrate 101, the first multilayer reflector 102, the first active layer 104-1, the oxidized constricting layer 106, the tunnel junction 108, the second active layer 104-2 and the second multilayer
- the film reflectors 112 are laminated in this order from the substrate 101 side (lower side).
- the resonator R is configured including the first and second active layers 104-1 and 104-2, the tunnel junction 108, and the oxidized constricting layer 106. That is, the surface emitting laser 100 has a resonator structure in which the resonator R is arranged between the first and second multilayer reflectors 102 and 112 .
- the mesa M1 constitutes a resonator structure (excluding the other portion (lower portion) of the first multilayer reflector 102).
- the height direction of the mesa M1 substantially coincides with the stacking direction.
- the mesa M1 has, for example, a substantially cylindrical shape, but may have other shapes such as a substantially elliptical cylindrical shape, a substantially prismatic shape, a substantially truncated pyramid shape, a substantially truncated cone shape, and a substantially truncated elliptical cone shape.
- the surface emitting laser 100 emits light from the emission surface ES at the top of the mesa M1. That is, the surface emitting laser 100 is, for example, a surface emitting surface emitting laser.
- the first active layer 104-1 is located farther from the emission surface ES of the surface emitting laser 100 than the other active layer 104-2 of the two adjacent active layers.
- the first active layer 104-1 is the other of the first and second multilayer reflecting mirrors 102 and 112, which is farther from the output surface ES than the second multilayer reflecting mirror 112, which is closer to the output surface ES. It is arranged at a position close to the multilayer film reflector 102 .
- the first active layer 104-1 is arranged in the lower half of the resonator R, for example. More specifically, the first active layer 104-1 is arranged near the downstream end of the current path in the resonator R, for example.
- the second active layer 104-2 is located closer to the second multilayer reflector 112 than the first multilayer reflector 102 is.
- the second active layer 104-2 is arranged in the upper half of the resonator R, for example. More specifically, the second active layer 104-2 is arranged near the upstream end of the current path in the resonator R, for example.
- the oxidized constricting layer 106 is located closer to the first multilayer reflector 102 than to the second multilayer reflector 112 . That is, the oxidized constricting layer 106 is arranged in the lower half of the resonator R, for example.
- the substrate 101 is, for example, a first conductivity type (eg, n-type) semiconductor substrate (eg, GaAs substrate).
- a cathode electrode 117 that is an n-side electrode is provided on the back surface (lower surface) of the substrate 101 .
- the cathode electrode 117 may have a single-layer structure or a laminated structure.
- the cathode electrode 117 is made of AuGe/Ni/Au, for example.
- the first multilayer film reflector 102 is arranged on the substrate 101 as an example.
- the first multilayer reflector 102 is, for example, a semiconductor multilayer reflector.
- a multilayer reflector is also called a distributed Bragg reflector.
- a semiconductor multilayer reflector which is a type of multilayer reflector (distributed Bragg reflector), absorbs little light and has high reflectance and conductivity.
- the first multilayer reflector 102 is, for example, a semiconductor multilayer reflector of a first conductivity type (for example, n-type), and includes a plurality of types (for example, two types) of semiconductor layers having mutually different refractive indices.
- Each refractive index layer of the first multilayer reflector 102 is made of a first conductivity type (for example, n-type) AlGaAs-based compound semiconductor.
- the first active layer 104-1 is arranged on the first multilayer reflector 102 via the first clad layer 103 made of a non-doped AlGaAs-based compound semiconductor.
- the "cladding layer” is also called a "spacer layer”.
- the first active layer 104-1 includes an active region made of a non-doped InGaAs-based compound semiconductor (eg, In 0.10 GaAs) and a guide region made of a non-doped AlGaAs-based compound semiconductor (eg, Al 0.10 GaAs). It has a laminated structure in which barrier regions (guide regions at both ends in the lamination direction and barrier regions in the middle in the lamination direction) are alternately laminated.
- the first active layer 104 has, for example, two layers of guide regions, two layers of barrier regions and three layers of active regions.
- the thickness of each active region is, for example, 7 nm.
- the thickness of the guide regions at both ends in the stacking direction is, for example, 10 nm.
- the thickness of the intermediate barrier region in the lamination direction is, for example, 8 nm. Since the first active layer 104-1 has the laminated structure, the surface emitting laser 100 can perform laser oscillation with an oscillation wavelength of, for example, the 900 nm band.
- the oxidized constricting layer 106 is arranged on the first active layer 104-1 via a spacer layer 105 made of a non-doped AlGaAs-based compound semiconductor. Note that the spacer layer is also called a "cladding layer”.
- the oxidized constricting layer 106 includes, for example, a non-oxidized region 106a made of an AlGaAs-based compound semiconductor (eg, AlGaAs, AlAs, etc.) and an oxidized region made of an AlGaAs-based compound semiconductor oxide (eg, Al 2 O 3 ) surrounding the non-oxidized region 106a. 106b.
- the base material of the oxidized constricting layer 106 (selectively oxidized layer 106S to be described later), it is preferable to use an AlGaAs film having an Al composition of 90% or more. Assuming that the oscillation wavelength of the surface emitting laser 100 is ⁇ , the first active layer 104-1, the tunnel junction 108 and the oxidized constricting layer 106 are arranged within an optical thickness of 3 ⁇ /4.
- the oxidized constriction layer is also called a "current confinement layer".
- the tunnel junction 108 is arranged on the oxidized constricting layer 106 via a spacer layer 107 made of a non-doped AlGaAs-based compound semiconductor.
- the tunnel junction 108 includes a p-type semiconductor layer 108a and an n-type semiconductor layer 108b stacked together.
- the p-type semiconductor layer 108a is arranged on the substrate 101 side (lower side) of the n-type semiconductor layer 108b. More specifically, as an example, the p-type semiconductor layer 108a is arranged between the oxidized constricting layer 106 and the n-type semiconductor layer 108b so as to be in contact with the n-type semiconductor layer 108b.
- the p-type semiconductor layer 108a is made of, for example, a GaAs-based compound semiconductor, an AlGaAs-based compound semiconductor, an InGaAs-based compound semiconductor, or an AlGaInP-based compound semiconductor having a high carrier concentration.
- a dopant material for the p-type semiconductor layer 108a for example, C, Zn, Mg, or the like can be used.
- a GaAs layer with a thickness of 10 nm doped with C (carbon) at a high concentration for example, 1 ⁇ 10 20 cm ⁇ 3 ) can be used.
- the n-type semiconductor layer 107b is made of, for example, an n-type GaAs-based compound semiconductor, AlGaAs-based compound semiconductor, InGaAs-based compound semiconductor, or AlGaInP-based compound semiconductor having a high carrier concentration.
- a dopant material for the n-type semiconductor layer 108b Si, Te, Se, or the like can be used.
- As the n-type semiconductor layer 108b for example, a 20 nm-thick GaAs layer doped with Si (silicon) at a high concentration (eg, 5 ⁇ 10 19 cm ⁇ 3 ) can be used.
- the second active layer 104-2 is arranged above the tunnel junction 108 via a spacer layer 109 made of a non-doped AlGaAs-based compound semiconductor.
- the second active layer 104-2 has, for example, the same layer configuration as the first active layer 104-1. That is, for example, the second active layer 104-2 consists of an active region made of a non-doped InGaAs-based compound semiconductor (eg, In 0.10 GaAs) and a non-doped AlGaAs-based compound semiconductor (eg, Al 0.10 GaAs).
- the second active layer 104-2 has, for example, two layers of guide regions, two layers of barrier regions, and three layers of active regions.
- the film thickness of each active region is, for example, 7 nm.
- the film thickness of the guide regions at both ends in the stacking direction is, for example, 10 nm.
- the film thickness of the intermediate barrier region in the stacking direction is, for example, 8 nm. Since the second active layer 104-2 has the laminated structure, the surface emitting laser 100 can perform laser oscillation with an oscillation wavelength of, for example, the 900 nm band.
- the second multilayer reflector 112 is arranged on the second active layer 104-2 via a second cladding layer 111 made of a non-doped AlGaAs-based compound semiconductor.
- the second multilayer reflector 112 is, for example, a semiconductor multilayer reflector.
- a multilayer reflector is also called a distributed Bragg reflector.
- a semiconductor multilayer reflector which is a kind of multilayer reflector (distributed Bragg reflector), absorbs little light and has high reflectance and conductivity.
- the second multilayer reflector 112 is, for example, a semiconductor multilayer reflector of a second conductivity type (for example, p-type), and includes a plurality of types (for example, two types) of semiconductor layers having different refractive indices. It has a structure in which layers are alternately laminated with an optical thickness of 1/4 wavelength of the oscillation wavelength.
- Each refractive index layer of the second multilayer reflector 112 is made of a second conductivity type (for example, p-type) AlGaAs-based compound semiconductor.
- the second multilayer reflecting mirror 112 is set to have a slightly lower reflectance than the first multilayer reflecting mirror 102 .
- An oxidized constricting layer 113 which is another oxidized constricting layer, is arranged inside the second multilayer film reflector 112 .
- the second multilayer reflector 112 is, for example, the one of the first and second multilayer reflectors 102 and 112 closer to the emission surface ES of the surface emitting laser 100 .
- the oxidized constricting layer 113 includes a non-oxidized region 113a made of a second conductivity type (eg, n-type) AlGaAs-based compound semiconductor (eg, AlGaAs, AlAs, etc.) and an AlGaAs-based compound semiconductor oxide ( and an oxidized region 113b made of, for example, Al 2 O 3 ).
- a second conductivity type eg, n-type
- AlGaAs-based compound semiconductor eg, AlGaAs, AlAs, etc.
- AlGaAs-based compound semiconductor oxide eg, AlGaAs, AlAs, etc
- the oxidized constricting layers 106 and 113 are formed, as an example, by selectively oxidizing a selectively oxidized layer made of an AlGaAs-based compound semiconductor.
- the oxidized constricting layers 106 and 113 preferably have different Al compositions and/or optical thicknesses.
- the substrate layer to be selectively oxidized
- the substrate is oxidized differently in the resonator R including the oxidized constricting layer 106 and in the second multilayer reflector 112 including the oxidized constricting layer 113. This is because it is necessary to individually set the oxidation rate in order to obtain a desired oxidized constriction diameter in the oxidized constriction layer.
- the oxidation constriction diameters of the oxidation constriction layers 106 and 113 may be the same or different.
- the selectively oxidized layer tends to have a higher oxidation rate as the Al composition increases, and tends to have a higher oxidation rate as the optical thickness increases.
- a contact layer 114 made of a GaAs layer of the second conductivity type (for example, p-type) is arranged on the second multilayer film reflector 112 .
- the contact layer 114 constitutes the top portion of the mesa M1, and the central portion (part other than the peripheral portion) of the upper surface of the contact layer 114 constitutes the emission surface ES.
- the mesa M1 is covered with an insulating film 115 except for the central portion of the top surface of the contact layer 114 .
- the insulating film 115 is made of dielectric material such as SiO 2 , SiN, and SiON. That is, a contact hole 115a is formed in the insulating film 115 on the top of the mesa M1 (for example, the contact layer 114), and the annular anode electrode 116, which is the p-side electrode, is formed in the contact hole 115a on the top of the mesa M1 (for example, the contact layer 114). For example, it is provided in contact with the contact layer 114).
- the anode electrode 116 is arranged in the contact hole 115a such that its center substantially coincides with the center of the oxidized constricting layer 113 when viewed in the stacking direction.
- the inner side of the anode electrode 116 serves as an exit port for laser light.
- the anode electrode 116 may have a single-layer structure or a laminated structure.
- the anode electrode 116 is made of Ti/Pt/Au, for example.
- FIG. 2 shows a procedure for manufacturing not only the surface-emitting laser 100 but also derivatives of the surface-emitting laser 100 .
- a plurality of surface-emitting laser arrays in which a plurality of surface-emitting lasers 100 are two-dimensionally arranged are simultaneously formed on a single wafer, which is the base material of the substrate 101, by a semiconductor manufacturing method using a semiconductor manufacturing apparatus. Generate.
- a plurality of integrated surface emitting laser arrays are separated by dicing to obtain a plurality of chip-shaped surface emitting laser arrays (surface emitting laser array chips).
- a plurality of surface emitting lasers 100 are simultaneously generated on one wafer which is the base material of the substrate 101, and the plurality of surface emitting lasers 100 are separated by dicing. It is also possible to obtain a chip-shaped surface-emitting laser (surface-emitting laser chip).
- the following series of steps are executed by the CPU of the semiconductor manufacturing equipment.
- a stack generation process 1 is performed.
- the layers constituting the surface-emitting laser 100 are successively laminated in a growth chamber by a chemical vapor deposition (CVD) method, such as a metal organic chemical vapor deposition (MOCVD) method, to form a laminate L1.
- CVD chemical vapor deposition
- MOCVD metal organic chemical vapor deposition
- the first active layer 104-1, the selectively oxidized layer 106S, the tunnel junction 108, and the second active layer 104-2 are formed on the first multilayer reflector 102.
- a structure including a laminated structure laminated in this order is laminated, and a second multilayer reflector 112 including a selectively oxidized layer 113S is laminated on the structure to generate a laminated body L1.
- Laminate generation processing 1 (step S1 in FIG. 2) will be described below with reference to the flowchart in FIG.
- Step S1-1 the first multilayer film reflector 102 is laminated on the substrate 101 (see FIG. 4).
- Step S1-2 Resonator base material production step 1
- a resonator substrate forming step 1 is performed.
- Resonator substrate production step 1 is a step of producing a resonator substrate that will become the resonator R on the first multilayer film reflector 102, as will be described in detail below.
- the resonator base material production step 1 will be described with reference to the flow chart of FIG. 5 and FIGS. 6 to 10 (first to fifth lamination process diagrams).
- step S1-2-1 the first active layer 104-1 is laminated on the first multilayer reflector 102 (see FIG. 6). More specifically, the first active layer 104-1 is laminated on the first multilayer reflector 102 with the first cladding layer 103 interposed therebetween.
- step S1-2-2 1 is set to n.
- step S1-2-3 the n-th selectively oxidized layer 106S-n is laminated on the n-th active layer 104-n (see FIG. 7). More specifically, the nth selectively oxidized layer 106S-n is laminated on the first active layer 104-1 with the spacer layer 105 interposed therebetween.
- the first selectively oxidized layer 106S-1 is the selectively oxidized layer 106S shown in FIG.
- step S1-2-4 the nth tunnel junction 108-n is stacked on the nth selectively oxidized layer 106S-n (see FIG. 8). More specifically, the p-type semiconductor layer 108a and the n-type semiconductor layer 108b that constitute the n-th tunnel junction 108-n are stacked in this order on the n-th selectively oxidized layer 106S with the spacer layer 107 interposed therebetween.
- step S1-2-5 the n+1th active layer 104-(n+1) is stacked on the nth tunnel junction 108-n (see FIG. 9). More specifically, the n+1th active layer 104-(n+1) is stacked on the nth tunnel junction 108-n with the spacer layer 109 interposed therebetween.
- step S1-2-6 it is determined whether or not n ⁇ N. If the determination here is affirmative, the process proceeds to step S1-2-7, and if the determination is negative, the process proceeds to step S1-2-8.
- step S1-2-7 n is incremented. After step S1-2-7 is executed, the process returns to step S1-2-3, and a series of processes from S1-2-3 to S1-2-5 are executed again. As a result, the selectively oxidized layer, the tunnel junction and the active layer are further laminated in this order on the second active layer 104-2 to produce a cavity base material for manufacturing a derived system of the surface emitting laser 100. can be done.
- step S1-2-8 the second clad layer 111 is laminated on the n+1th active layer 104-(n+1) (see FIG. 10). As a result, a resonator base that becomes a resonator is produced.
- Step S1-3 the second multilayer film reflector 112 is stacked on the resonator substrate (see FIG. 11). More specifically, on the second cladding layer 111 of the resonator substrate, the second multilayer reflector 112 including the selectively oxidized layer 113S inside and the contact layer 114 are laminated in this order. As a result, a laminate (for example, laminate L1) is generated. When step S1-3 is executed, the laminate generation process 1 ends.
- step S2 the laminate (eg, laminate L1) is etched to form a mesa (eg, mesa M1) (see FIG. 12).
- a resist pattern is formed by photolithography on the laminate L1 taken out from the growth chamber.
- the laminate L1 is etched by, for example, RIE etching (reactive ion etching) until at least the side surface of the selectively oxidized layer 106S is exposed, thereby forming the mesa M1.
- the etching is performed, for example, until the side surface of the first cladding layer 103 is completely exposed (for example, until the etched bottom surface is positioned within the first multilayer film reflector 102).
- the resist pattern is removed.
- step S3 the peripheral portions of the selectively oxidized layers 106S and 113S (see FIG. 12) are oxidized to form oxidized constricting layers 106 and 113 (see FIG. 13).
- the mesa M1 is exposed to a steam atmosphere to oxidize (selectively oxidize) the layers 106S and 113S to be selectively oxidized from the side surfaces, thereby forming an oxidized constriction in which the non-oxidized region 106a is surrounded by the oxidized region 106b.
- an oxidized constricting layer 113 is formed in which a region 113a to be oxidized is surrounded by an oxidized region 113b.
- step S4 an insulating film 115 is formed (see FIG. 14). Specifically, for example, the insulating film 115 is formed over substantially the entire area of the laminate in which the mesa M1 is formed.
- step S5 contact holes 115a are formed (see FIG. 15). Specifically, for example, a resist pattern is formed by photolithography on the insulating film 115 other than the insulating film 115 formed on the top of the mesa M1. Next, using this resist pattern as a mask, the insulating film 115 formed on the top of the mesa M1 is removed by etching using, for example, a hydrofluoric acid-based etchant. After that, the resist pattern is removed. As a result, a contact hole 115a is formed and the contact layer 114 is exposed.
- step S6 the anode electrode 116 is formed (see FIG. 16). Specifically, for example, a Ti/Pt/Au film is formed on the contact layer 114 through the contact hole 115a by EB vapor deposition, and the resist and the Ti/Pt/Au on the resist are lifted off. Thus, an annular anode electrode 116 is formed in the contact hole 115a.
- step S7 the cathode electrode 117 is formed (see FIG. 17). Specifically, after polishing the back surface (lower surface) of the substrate 101, for example, an AuGe/Ni/Au film is formed on the back surface. After step S7 is executed, the flow of FIG. 2 ends.
- the surface emitting laser 100 includes first and second multilayer film reflectors 102 and 112, and first and second multilayer film reflectors.
- a plurality of active layers (for example, first and second active layers 104-1 and 104-2) laminated between 102 and 112 and two active layers adjacent in the lamination direction among the plurality of active layers
- a tunnel junction 108 arranged between certain first and second active layers 104-1 and 104-2, and the first active layer 104-1 and the tunnel junction 108, which are one active layer of two adjacent active layers.
- an oxidized constricting layer 106 disposed between.
- the current injected into the second active layer 104-2 through the tunnel junction 108 is confined by the oxidized constricting layer 106 and injected into the first active layer 104-1.
- current can be efficiently injected into the first active layer 104-1, and a decrease in light emission efficiency in the first active layer 104-1 can be suppressed.
- the surface emitting laser 100 of the first embodiment it is possible to provide a surface emitting laser capable of suppressing a decrease in luminous efficiency.
- the surface emitting laser 100 when the light generated in each of the first and second active layers 104-1 and 104-2 reciprocates between the first and second multilayer reflectors 102 and 112, Since the oxidized constricting layer 106 increases the light confinement effect, it is also possible to expand the control range of the output angle of the laser light (output light).
- the first active layer 104-1 which is one of the active layers (the active layer sandwiching the oxidized constricting layer 106 with the tunnel junction 108) is the second active layer 104-1 which is the other active layer of the two adjacent active layers. 2 from the emission surface ES of the surface-emitting laser 100 .
- the oxidized constricting layer 106 can be arranged at a position farther from the exit surface ES (at least a position farther from the exit surface ES than the tunnel junction 108), and a current constriction effect can be obtained at this position.
- the resonator R provided between the first and second multilayer film reflectors 102 and 112, it is arranged at a position farther from the output surface ES (at least a position farther from the output surface ES than the oxidized constricting layer 106).
- the current injected into the first active layer 104-1 can be narrowed, and the current injection efficiency into the first active layer 104-1 can be improved. If the oxidized constricting layer 106 were not provided in the resonator, for example, the current supplied to the resonator from the side of the emission surface ES spreads in the resonator and spreads through the second active layer 104-2, The first active layer 104-1 is implanted in this order.
- the first active layer 104-1 is located on the downstream end side of the current path in the resonator than the second active layer 104-2, a wider current is injected.
- the first active layer 104-1 is in a more disadvantageous position than the second active layer 104-2 in terms of current injection efficiency. Therefore, it is of great significance that the current injected into the first active layer 104-1 can be confined.
- the first active layer 104-1 which is one of the active layers (the active layer sandwiching the oxidized constricting layer 106 with the tunnel junction 108), is closer to the exit surface ES than the first and second multilayer reflectors 102 and 112. It is arranged at a position (for example, the lower half of the resonator R) closer to the first multilayer film reflector 102 which is farther from the exit surface ES than the second multilayer film reflector 112 which is one.
- the current injected into the first active layer 104-1 arranged in the lower half of the resonator R can be effectively confined by the oxidized constricting layer 106, for example.
- the first active layer 104-1 which is one of the active layers (the active layer sandwiching the oxidized constricting layer 106 with the tunnel junction 108), is the exit surface ES of the first and second multilayer reflectors 102 and 112. It may be arranged at a position closer to the second multilayer film reflector 112, which is closer to the exit surface ES than the first multilayer film reflector 102, which is the one farther from the exit surface ES (for example, the upper half of the resonator R).
- the oxidized constricting layer 106, the tunnel junction 108, and the second active layer 104-2 are also positioned closer to the second multilayer reflector 112 than the first multilayer reflector 102 (for example, the upper half of the resonator R). may be placed in
- An oxidized constricting layer 113 (another oxidized constricting layer) is arranged inside the first and second multilayer film reflectors 102 and 112 closer to the emission surface ES of the surface emitting laser 100 .
- the first and second active layers 104-1 and 104-2 are positioned closer to the emission surface ES (for example, the upper half of the resonator R (specifically, near the upstream end of the current path in the resonator R)). ), the current injected into the second active layer 104-2 can be effectively constricted.
- Both of the oxidized constricting layers 106 and 113 are preferably formed by selectively oxidizing a layer made of an AlGaAs-based compound semiconductor.
- the oxidized constricting layers 106 and 113 differ from each other in Al composition and/or optical thickness.
- the oxidation confinement diameter of each of the oxidation constriction layers 106 and 113 can be set to a desired size when the selective oxidation process is performed in the same oxidation atmosphere (for example, in the same steam atmosphere).
- the tunnel junction 108 has a layered structure in which a p-type semiconductor layer 108a and an n-type semiconductor layer 108b are laminated, and the oxidized constricting layer 106 is arranged on the p-type semiconductor layer 108a side.
- the oxidized constricting layer 106 can be arranged at a position closer to the first multilayer reflector 102, which is an n-type multilayer reflector (farther from the exit surface ES).
- the first active layer 104-1, the tunnel junction 108, and the oxidized constricting layer 106 are arranged within an optical thickness of 3 ⁇ /4.
- the first active layer 104-1 is arranged at or near the antinode of the standing wave of wavelength ⁇
- each of the tunnel junction 108 and the oxidized constriction layer 106 is arranged at the standing wave.
- the manufacturing method of the surface emitting laser 100 is a lamination in which the first active layer 104-1, the selectively oxidized layer 106S, the tunnel junction 108 and the second active layer 104-2 are laminated in this order on the first multilayer reflector 102. a step of stacking a structure including a structure and stacking at least a second multilayer film reflector 112 on the structure to generate a stack L1; and forming the oxidized constricting layer 106 by selectively oxidizing the selectively oxidized layer 106S from the side surface.
- a refractive index guide type surface emitting laser 100 capable of suppressing a decrease in luminous efficiency.
- a first oxidized constricting layer 106-1 In the surface-emitting laser 100-1 of Modified Example 1, as shown in FIG. In place of the oxidized constricting layer 113, another oxidized constricting layer 106 (referred to as a first oxidized constricting layer 106-1) is provided between the first multilayer reflector 102 and the first active layer 104-1. It has the same configuration as the surface-emitting laser 100 (see FIG. 1) of the first embodiment except that it is provided between and that the conductivity type is opposite.
- the conductivity type of the first multilayer film reflector 102 is p-type
- the conductivity type of the second multilayer film reflector 112 is n-type
- the anode electrode 116 is connected to the substrate 101.
- the cathode electrode 117 is arranged on the top of the mesa, and the n-type semiconductor layer 108b is arranged on the substrate 101 side of the p-type semiconductor layer 108a at the tunnel junction 108 .
- the second active layer 104-2 which is an active layer sandwiching the second oxidized constricting layer 106-2 with the tunnel junction 108, is stronger in the surface-emitting laser 100 than the first active layer 104-1. It is arranged at a position close to the exit surface ES.
- the second oxidized confinement layer 106-2 can be arranged at a position closer to the exit surface ES (at least a position closer to the exit surface ES than the tunnel junction 108), and a current confinement effect can be obtained at this position. can be done. That is, in the resonator provided between the first and second multilayer film reflectors 102 and 112, a position closer to the output surface ES (at least a position closer to the output surface ES than the oxidized constricting layer 106, for example, above the resonator) A current constriction effect can be obtained in the second active layer 104-2, and the efficiency of current injection into the second active layer 104-2 can be improved.
- the second active layer 104-2 which is an active layer sandwiching the second oxidized constricting layer 106-2 with the tunnel junction 108, is one of the first and second multilayer reflectors 102 and 112. It is arranged at a position closer to the second multilayer reflecting mirror 112, which is the other multilayer reflecting mirror closer to the exit surface ES than the first multilayer reflecting mirror 102, which is the other multilayer reflecting mirror farther from the exit surface ES. .
- the current flowing from the anode electrode 116 passes through the substrate 101 and the first multilayer reflector 102, is confined by the first constricting oxide layer 106-1, and is injected into the first active layer 104-2. be done.
- the second active layer 104-2 which is the active layer sandwiching the oxidized constricting layer 106-2 with the tunnel junction 108, is one of the first and second multilayer mirrors 102 and 112 closer to the exit surface ES. It may be arranged at a position closer to the first multilayer reflecting mirror 102 , which is farther from the exit surface ES than the second multilayer reflecting mirror 112 (for example, the lower half of the resonator).
- the oxidized constricting layer 106, the tunnel junction 108, and the first active layer 104-1 are also positioned closer to the first multilayer reflector 102 than the second multilayer reflector 112 (for example, the lower half of the resonator). may be placed.
- the surface-emitting laser 100-1 of Modification 1 is the same as the first embodiment, except that another oxidized constricting layer 106 is formed in place of the oxidized constricting layer 113 and that the stacking order is partially different in the laminate production process. It can be manufactured by a manufacturing method similar to the manufacturing method of the surface emitting laser 100 (see FIG. 1) of one embodiment.
- the surface-emitting laser 100-3 of Modification 2 has an active layer and an oxidized constriction layer between the first and second multilayer reflectors 102 and 112 from the first multilayer reflector 102 side. It has the same configuration as the surface-emitting laser 100 (see FIG. 1) of the first embodiment, except that it has a plurality of (for example, two) laminated structures in which the tunnel junction and the tunnel junction are laminated in this order. More specifically, the surface emitting laser 100-3 has a first active layer 104-1, a first oxidized confinement layer 106-1 and a first tunnel junction 108-1 stacked in this order from the first multilayer reflector 102 side. and a first laminated structure.
- the surface-emitting laser 100-3 has a second active layer 104-2, a second oxidized constriction layer 106-2, and a second tunnel junction 108- on the first laminated structure from the first multilayer reflector 102 side. 2 are laminated in this order to form a second laminated structure.
- the first and second tunnel junctions 108-1, 108-2 have substantially the same configuration and function as the tunnel junction 108.
- the surface emitting laser 100-3 has a third active layer 104-3 on the second laminated structure.
- the plurality of active layers are three active layers (first to third active layers 104-1 to 104-3), and at least Two sets of two adjacent active layers (first and second active layers 104-1, 104-2, second and third active layers 104-2, 104-3)
- a first tunnel junction 108-1 is disposed between the layers, first and second active layers 104-1, 104-2, and a second set of two adjacent active layers, the second and third active layers.
- a second tunnel junction 108-2 is located between the active layers 104-2, 104-3.
- the first active layer 104-1 which is one of the first and second active layers 104-1 and 104-2, which are two adjacent active layers in the first set, and the two adjacent active layers A first oxidized constriction layer 106-1 is located between the first tunnel junction 108-1 located between the layers first and second active layers 104-1, 104-2.
- the second active layer 104-2 which is one of the second and third active layers 104-2 and 104-3, which are two adjacent active layers in the second set, and the two adjacent active layers A second oxidized constriction layer 106-2 is located between the second tunnel junction 108-2 located between the layers second and third active layers 104-2, 104-3.
- the surface emitting laser 100-3 includes first, second and third active layers 104-1 to 104-3, and the first, second and third active layers 104-1 to 104-3 are laminated in this order.
- a first tunnel junction 108-1 is arranged between the first and second active layers 104-1, 104-2
- a second tunnel junction 108-1 is arranged between the second and third active layers 104-2, 104-3.
- Junction 108-2 is located.
- a first oxidized constricting layer 106-1 is disposed between the first active layer 104-1 and the first tunnel junction 108-1, and a second active layer 104-2 and the second tunnel junction 108-2 are connected.
- a second oxidized constricting layer 106-2 is disposed therebetween.
- the first active layer 104-1 is positioned farthest from the emission surface ES of the surface emitting laser 100-3 among the three active layers 104-1 to 104-3.
- the active layer is placed in the vicinity of the downstream end of the current path of the .
- the surface emitting laser 100-4 of Modification 3 has a tunnel junction and an oxidized constriction layer between the first and second multilayer reflectors 102 and 112 from the first multilayer reflector 102 side. and a plurality (for example, two) of laminated structures in which the active layers are laminated in this order, and instead of the oxidized constricting layer 113, another oxidized constricting layer 106 includes the first multilayer reflector 102 and the first active layer 104-. 1 and that the conductivity type is opposite, the configuration is similar to that of the surface emitting laser 100-3 (see FIG. 19) of the second modification.
- the surface-emitting laser 100-4 has a configuration in which the surface-emitting laser 100-3 is turned upside down.
- the conductivity type of the first multilayer film reflector 102 is p-type
- the conductivity type of the second multilayer film reflector 112 is n-type
- the anode electrode 116 is connected to the substrate 101.
- the cathode electrode 117 is arranged on the top of the mesa
- the n-type semiconductor layer 108b (the gray layer in FIG. 20) is located on the substrate 101 side of the p-type semiconductor layer 108a at each tunnel junction. are placed.
- the surface emitting laser 100-4 has a first tunnel junction 108-1, a first oxidized constriction layer 106-1 and a second active layer 104-2 stacked in this order from the first multilayer reflector 102 side. and a first laminated structure. Further, the surface-emitting laser 100-4 has a second tunnel junction 108-2, a second oxidized constriction layer 106-2, and a third active layer 104-2 on the first laminated structure from the first multilayer reflector 102 side. 3 are laminated in this order to form a second laminated structure. Furthermore, the surface emitting laser 100-4 has a first active layer 104-1 under the first laminated structure.
- the surface-emitting laser 100-4 even in the case of a multi-active layer having three active layers, it is possible to efficiently inject a current into each active layer and suppress a decrease in the luminous efficiency of the active layer.
- the surface-emitting laser 100-4 is the same as the surface-emitting laser 100-3 of Modified Example 2, except that an oxidized constricting layer 106 is formed in place of the oxidized constricting layer 113 and that the order of lamination is different in the laminate production process. (See FIG. 19).
- Modification 4 In the surface emitting laser 100-5 of Modification 4, as shown in FIG. It has the same configuration as the surface emitting laser 100 (see FIG. 1) of the first embodiment except that it has a plurality of (for example, three) laminated structures laminated in this order from the mirror 102 side. More specifically, the surface emitting laser 100-5 has a first active layer 104-1, a first oxidized confinement layer 106-1 and a first tunnel junction 108-1 stacked in this order from the first multilayer reflector 102 side. and a first laminated structure.
- the surface-emitting laser 100-5 has a second active layer 104-2, a second oxidized constriction layer 106-2, and a second tunnel junction 108- on the first laminated structure from the first multilayer reflector 102 side. 2 are laminated in this order to form a second laminated structure. Furthermore, the surface-emitting laser 100-5 has a third active layer 104-3, a third oxidized constriction layer 106-3, and a third tunnel junction 108- on the second laminated structure from the first multilayer reflector 102 side. 3 are laminated in this order to form a third laminated structure. Third tunnel junction 108-3 has substantially the same configuration and function as tunnel junction 108. FIG.
- the surface emitting laser 100-5 has a fourth active layer 104-4 on the third laminated structure. According to the surface-emitting laser 100-5, even in the case of a multi-active layer having four active layers, it is possible to efficiently inject a current into each active layer and suppress a decrease in the luminous efficiency of the active layer. According to the surface-emitting laser (derivative system of the surface-emitting laser 100) having four or more of the above laminated structures and the oxidized constricting layer 113, in the case of a multi-active layer having five or more active layers, However, current can be efficiently injected into each active layer, and a decrease in the luminous efficiency of the active layer can be suppressed.
- a surface emitting laser having four or more of the above laminated structures can be manufactured by a similar manufacturing method (however, N ⁇ 4 in step S1-2-6 of FIG. 5).
- the surface emitting laser 100-6 of Modification 5 has a tunnel junction, an oxidized constriction layer, and an active layer between the first and second multilayer reflectors 102 and 112, which form the first multilayer reflector.
- the oxidized constricting layer 113 instead of the oxidized constricting layer 113, another oxidized constricting layer 106 includes the first multilayer reflector 102 and the first active layer 104-. 1 and that the conductivity type is opposite, the configuration is the same as that of the surface emitting laser 100-5 (see FIG. 21) of the fourth modification.
- the surface emitting laser 100-6 has a configuration in which the surface emitting laser 100-5 is turned upside down.
- the conductivity type of the first multilayer film reflector 102 is p-type
- the conductivity type of the second multilayer film reflector 112 is n-type
- the anode electrode 116 is connected to the substrate 101.
- the cathode electrode 117 is arranged on the top of the mesa
- the n-type semiconductor layer 108b (the gray layer in FIG. 22) is located on the substrate 101 side of the p-type semiconductor layer 108a at each tunnel junction. are placed.
- the surface emitting laser 100-6 has a first tunnel junction 108-1, a first oxidized constriction layer 106-1 and a second active layer 104-2 stacked in this order from the first multilayer reflector 102 side. and a first laminated structure. Further, the surface-emitting laser 100-6 has a second tunnel junction 108-2, a second oxidized constriction layer 106-2, and a third active layer 104-2 on the first laminated structure from the first multilayer reflector 102 side. 3 are laminated in this order to form a second laminated structure.
- the surface-emitting laser 100-6 has a third tunnel junction 108-3, a third oxidized constriction layer 106-3, and a fourth active layer 104- on the second laminated structure from the first multilayer reflector 102 side. 4 are laminated in this order to form a third laminated structure. Further, the surface emitting laser 100-6 has a first active layer 104-1 under the first laminated structure. According to the surface-emitting laser 100-6, even in the case of a multi-active layer having four active layers, it is possible to efficiently inject a current into each active layer and suppress a decrease in the luminous efficiency of the active layer.
- the surface-emitting laser 100-6 is the same as the surface-emitting laser of Modification 3, except that another oxidized constricting layer 106 is formed in place of the oxidized constricting layer 113 and that the number of steps for lamination is increased in the laminate production process. It can be manufactured by a manufacturing method similar to that of 100-4 (see FIG. 20). A surface emitting laser having four or more of the above laminated structures can be manufactured by a similar manufacturing method.
- a surface emitting laser 200 according to the second embodiment includes a second tunnel junction 108-2 and a third active layer 104- 3 are stacked in this order, the configuration is similar to that of the surface emitting laser 100 (see FIG. 1) of the first embodiment. That is, the surface emitting laser 200 has one tunnel junction/active layer pair on the second active layer 104-2.
- the surface emitting laser 200 is similar to the surface emitting laser 100- of the modified example 2 in that no oxidized constricting layer is arranged between the second active layer 104-2 and the second tunnel junction 108-2. 3 (see FIG. 19).
- a current having substantially the same current value as the current injected into the second active layer 104-2 is confined by the oxidized constricting layer 106 due to the tunneling effect of the first tunnel junction 108-1, and the first active layer 104-2 is confined. 1 is injected.
- the first to third active layers 104-1, 104-2, and 104-3 emit light with substantially the same emission intensity, and the light is emitted between the first and second multilayer film reflectors 102 and 112, respectively.
- the light reciprocates while being amplified in the active layer and satisfies the oscillation conditions, it is emitted as laser light from the top of the mesa M2.
- FIG. 24 shows a procedure for manufacturing not only the surface-emitting laser 200 but also surface-emitting lasers derived from the surface-emitting laser 200 .
- a plurality of surface-emitting laser arrays in which a plurality of surface-emitting lasers 200 are two-dimensionally arranged are simultaneously formed on a single wafer, which is the base material of the substrate 101, by a semiconductor manufacturing method using a semiconductor manufacturing apparatus. Generate.
- a plurality of integrated surface emitting laser arrays are separated by dicing to obtain a plurality of chip-shaped surface emitting laser arrays (surface emitting laser array chips).
- a plurality of surface emitting lasers 200 are simultaneously generated on one wafer which is the base material of the substrate 101, and the plurality of surface emitting lasers 200 are separated by dicing. It is also possible to obtain a chip-shaped surface-emitting laser (surface-emitting laser chip).
- the following series of steps are executed by the CPU of the semiconductor manufacturing equipment.
- a laminate generation process 2 is performed.
- the layers constituting the surface-emitting laser 200 are successively laminated in a growth chamber by a chemical vapor deposition (CVD) method, such as a metal-organic chemical vapor deposition (MOCVD) method, to form a laminate L2. (see FIG. 32).
- CVD chemical vapor deposition
- MOCVD metal-organic chemical vapor deposition
- the active layer 104-1, the selectively oxidized layer 106S, and the first tunnel junction 108 are formed on the first multilayer reflector 102, as described in detail below.
- the second active layer 104-2, the second tunnel junction 108-2, and the third active layer 104-3 are laminated in this order from the first multilayer film reflector 102 side.
- the second multilayer film reflector 112 including the selectively oxidized layer 113S inside is laminated on the structure to generate the laminated body L2 (see FIG. 32).
- Laminate generation processing 2 (step S11 in FIG. 24) will be described below with reference to the flowchart in FIG.
- Step S11-1 the first multilayer film reflector 102 is stacked on the substrate 101 (see FIG. 4).
- Step S11-2 Resonator base material production step 2
- a resonator base material forming step 2 is performed.
- the resonator substrate production step 2 is a step of laminating each layer constituting the resonator on the first multilayer film reflector 102 to produce a resonator substrate that will become the resonator. . 26, 6, 7, and 27 to 31 (first lamination process diagram to seventh lamination process diagram), the resonator base material production process 2 will be described below.
- the first active layer 104-1 is laminated on the first multilayer reflector 102 (see FIG. 6). More specifically, the first active layer 104-1 is laminated on the first multilayer reflector 102 with the first cladding layer 103 interposed therebetween.
- the n-th selectively oxidized layer 106S-n is stacked on the n-th active layer 104-n (see FIG. 7). More specifically, the nth selectively oxidized layer 106S-n is laminated on the first active layer 104-1 with the spacer layer 105 interposed therebetween.
- the first selectively oxidized layer 106S-1 is the selectively oxidized layer 106S.
- the nth tunnel junction 108-n is stacked on the nth selectively oxidized layer 106S-n (see FIG. 27).
- the p-type semiconductor layer 108a and the n-type semiconductor layer 108b constituting the n-th tunnel junction 108-n are laminated in this order on the n-th selectively oxidized layer 106S via the spacer layer 107. .
- the n+1th active layer 104-(n+1) is laminated on the nth tunnel junction 108-n (see FIG. 28). More specifically, the n+1th active layer 104-(n+1) is stacked on the nth tunnel junction 108-n with the spacer layer 109 interposed therebetween.
- step S11-2-6 it is determined whether or not n ⁇ N. If the determination here is affirmative, the process proceeds to step S11-2-7, and if the determination is negative, the process proceeds to step S11-2-8.
- step S11-2-7 n is incremented. After step S11-2-7 is executed, the process returns to step S11-2-3 and the series of processes from S11-2-3 to S11-2-5 is executed again. As a result, a selectively oxidized layer, a tunnel junction and an active layer are further laminated in this order on the second active layer 104-2 to produce a resonator base material for manufacturing a derived system of the surface emitting laser 200. can be done.
- step S11-2-8 1 is set to m.
- the n+mth tunnel junction 108-(n+m) is stacked on the n+mth active layer 104-(n+m) (see FIG. 29). More specifically, the n+mth tunnel junction 108-(n+m) is stacked on the n+mth active layer 104-(n+m) with the spacer layer 109 interposed therebetween.
- step S11-2-10 the n+m+1-th active layer 104-(n+m+1) is stacked on the n+m-th tunnel junction 108-(n+m) (see FIG. 30). More specifically, the n+m+1-th active layer 104-(n+m+1) is stacked on the n+m-th tunnel junction 108-(n+m) with the spacer layer 109 interposed therebetween.
- step S11-2-11 it is determined whether or not m ⁇ M. If the determination here is affirmative, the process proceeds to step S11-2-12, and if the determination is negative, the process proceeds to step S11-2-13.
- step S11-2-12 m is incremented. After step S11-2-12 is executed, the process returns to step S11-2-9, and the series of processes of S11-2-9 and S11-2-10 are executed again. As a result, a pair of a tunnel junction and an active layer can be laminated on the second active layer 104-2 to produce a cavity base material for manufacturing a derived system of the surface emitting laser 200.
- FIG. 1
- step S11-2-13 the second clad layer 111 is stacked on the n+m+1th active layer 104-(n+m+1) (see FIG. 31). This produces a resonator substrate.
- step S11-2-13 the flow of the resonator base material forming step 2 shown in FIG. 26 ends.
- step S11-3 the second multilayer reflector 112 is stacked on the resonator (see FIG. 32). More specifically, on the cladding layer 111 of the resonator, the second multilayer reflector 112 including the selectively oxidized layer 113S inside and the contact layer 114 are stacked in this order. As a result, a laminate (for example, laminate L2) is generated.
- step S11-3 the flow of the laminate generation process 2 shown in FIG. 25 ends.
- step S12 the laminate (eg, laminate L2) is etched to form a mesa (eg, mesa M1) (see FIG. 33--).
- a resist pattern is formed by photolithography on the laminate L2 taken out from the growth chamber.
- the laminate L2 is etched by, for example, RIE etching (reactive ion etching) until at least the side surface of the selectively oxidized layer 106S is exposed, thereby forming the mesa M2.
- the etching here is performed, for example, until the side surface of the first cladding layer 103 is completely exposed (for example, until the etched bottom surface is positioned within the first multilayer film reflector 102). After that, the resist pattern is removed.
- step S13 for example, the peripheral portions of the selectively oxidized layers 106S and 113S (see FIG. 33) are oxidized to form oxidized constricting layers 106 and 113 (see FIG. 34).
- the mesa M2 is exposed to a steam atmosphere to oxidize (selectively oxidize) the layers 106S and 113S to be selectively oxidized from the side surfaces, thereby forming an oxidized constriction in which the non-oxidized region 106a is surrounded by the oxidized region 106b.
- an oxidized constricting layer 113 is formed in which a region 113a to be oxidized is surrounded by an oxidized region 113b.
- step S14 an insulating film 115 is formed (see FIG. 35). Specifically, for example, the insulating film 115 is formed over substantially the entire area of the laminate on which the mesa M2 is formed.
- step S15 contact holes 115a are formed (see FIG. 36). Specifically, for example, a resist pattern is formed by photolithography on the insulating film 115 other than the insulating film 115 formed on the top of the mesa M2. Next, using this resist pattern as a mask, the insulating film 115 formed on the top of the mesa M2 is removed by etching using, for example, a hydrofluoric acid-based etchant. After that, the resist pattern is removed. As a result, a contact hole 115a is formed and the contact layer 114 is exposed.
- step S16 the anode electrode 116 is formed (see FIG. 37). Specifically, for example, a Ti/Pt/Au film is formed on the contact layer 114 through the contact hole 115a by EB vapor deposition, and the resist and the Ti/Pt/Au on the resist are lifted off. Thus, an annular anode electrode 116 is formed in the contact hole 115a.
- step S17 the cathode electrode 117 is formed (see FIG. 38). Specifically, after polishing the back surface (lower surface) of the substrate 101, for example, an AuGe/Ni/Au film is formed on the back surface. After step S17 is executed, the flow of FIG. 24 ends.
- the oxidized constriction layer 106 reduces the current in the cavity. Current can be efficiently injected into the first active layer 104-1, which is the active layer located near the downstream end of the path (for example, the active layer farthest from the emission surface ES).
- the surface emitting laser 200-1 of the modified example 1 is the same as the second embodiment except that it has two pairs of tunnel junction and active layer on the second active layer 104-2. It has a configuration similar to that of the surface emitting laser 200 (FIG. 23).
- the surface emitting laser 200-1 has a structure in which a third tunnel junction 108-3 and a fourth active layer 104-4 are stacked in this order on a third active layer 104-3 in the cavity of the surface emitting laser 200. ing. More specifically, in the surface-emitting laser 200-1, the third tunnel junction 108-3 is stacked on the third active layer 104-3 via the spacer layer 109, and the spacer layer is stacked on the third tunnel junction 108-3.
- a fourth active layer 104-4 is stacked with 109 interposed therebetween.
- the surface-emitting laser 200-1 of Modification 1 can be located near the downstream end of the current path in the cavity due to the oxidized constricting layer 106, even if the active layer has four multi-active layers and the cavity length is long. Current can also be efficiently injected into the first active layer 104-1, which is the active layer (for example, the active layer farthest from the emission surface ES).
- the surface emitting laser 200-2 of Modification 2 is provided with a first oxidized constricting layer 106-1 between the first active layer 104-1 and the first tunnel junction 108-1.
- the surface emitting laser 200-1 (see FIG. 39).
- the cavity is The current can be efficiently injected into the first active layer 104-1, which is the active layer located near the downstream end of the current path in the inside (for example, the active layer farthest from the emission surface ES), and the second oxidation A current can be efficiently injected into the second active layer 104-2 by the constriction layer 106-2.
- the surface emitting laser 200-3 of Modification 3 is provided with a first oxidized constricting layer 106-1 between the first active layer 104-1 and the first tunnel junction 108-1.
- the surface emitting laser 200-1 (see FIG. 39).
- the cavity is The current can be efficiently injected into the first active layer 104-1, which is the active layer located near the downstream end of the current path in the inside (for example, the active layer farthest from the emission surface ES), and the second oxidation A current can be efficiently injected into the second active layer 104-2 by the constriction layer 106-2.
- the provision of an oxidized constriction layer near the middle part in the vertical direction (height direction) of the cavity prevents the current from spreading near the middle part. It is effective in that it can be suppressed. Since the surface-emitting laser 200-3 needs to be provided with the second oxidized constricting layer 106-2, the manufacturing process for the surface-emitting laser 200-1 (see FIG. 39) of Modification 1 is followed, although the number of lamination steps increases accordingly. It can be manufactured by the manufacturing method.
- the surface emitting laser 200-4 of Modification 4 is provided with a first oxidized constricting layer 106-1 between the first active layer 104-1 and the first tunnel junction 108-1.
- the surface emitting laser 200 of the second embodiment Fig. 23.
- the first and second oxidized constriction layers 106-1 and 106-2 allow the downstream current path in the cavity to be reduced.
- the surface emitting laser 200-4 can be provided with the second oxidized constricting layer 106-2, the number of lamination steps increases accordingly, but the surface emitting laser 200-4 can be manufactured by a manufacturing method according to the manufacturing method of the surface emitting laser 200 of the second embodiment. can be done.
- FIG. 43 is a plan view showing a surface emitting laser 2000 as a configuration example of a surface emitting laser to which the present technology can be applied.
- 44A is a cross-sectional view taken along the line XX of FIG. 43.
- FIG. 44B is a cross-sectional view taken along the line YY of FIG. 43.
- the substrate 2001 can be composed of a semiconductor such as GaAs, InGaAs, InP, InAsP, or the like.
- a surface emitting laser 2000 includes a protected region 2002 (transmissive gray region in FIGS. 44A and 44B). As shown in FIG. 43, the protection area 2002 has a circular shape in a plan view, but may have another shape such as an elliptical shape or a polygonal shape, and is not limited to a specific shape.
- Protected region 2002 includes a material that provides electrical isolation, for example an ion-implanted region.
- the surface emitting laser 2000 includes a first electrode 2003 and a second electrode 2004, as shown in FIGS. 44A and 44B.
- the first electrode 2003 has a ring shape with discontinuous portions (intermittent portions), that is, a split ring shape in plan view, but is not limited to a specific shape.
- the second electrode 2004 is in contact with the substrate 2001 as shown in FIG. 44A or 44B.
- the first electrode 2003 and the second electrode 2004 are composed of a conductive material such as Ti, Pt, Au, AuGeNi, PdGeAu.
- the first electrode 2003 and the second electrode 2004 may have a single-layer structure or a laminated structure.
- surface emitting laser 2000 includes a trench 2005 provided around protected region 2002 .
- FIG. 43 shows, as an example, a structure in which six rectangular trenches 2005 are provided in plan view, but the number and shape in plan view are not limited to a specific one.
- Trench 2005 is an opening for forming oxidized constricting layer 2006 (including oxidized region 2006a and non-oxidized region 2006b).
- high-temperature steam is supplied through the trench 2005 to form an oxidized region 2006a of the oxidized constricting layer 2006.
- oxidized region 2006a is Al 2 O 3 formed as a result of oxidation of an AlAs or AlGaAs layer.
- Trench 2005 may be filled with an optional dielectric after the step of forming oxide constriction layer 2006 . In some cases, the surface is coated with a dielectric film.
- the surface emitting laser 2000 includes a dielectric opening 2008 (contact hole) provided in the dielectric layer 2007 on the first electrode 2003 .
- the dielectric layer 2007 may have a laminated structure as shown in FIGS. 44A and 44B, or may have a single layer structure.
- Dielectric layer 2007 includes, for example, silicon oxide or silicon nitride.
- dielectric opening 2008 is formed in the same shape as first electrode 2003 .
- the shape of dielectric opening 2008 is not limited to the shape of first electrode 2003 and may be partially formed on first electrode 2003 .
- the dielectric opening 2008 is filled with a conductive material (not shown), and the conductive material contacts the first electrode 2003 .
- the surface emitting laser 2000 includes an optical aperture 2009 inside the first electrode 2003, as shown in FIGS. 44A and 44B.
- Surface emitting laser 2000 emits light through optical aperture 2009 .
- the oxidized region 2006a of the oxidized constricting layer 2006 functions as a current/light confinement region for confining current and light.
- a non-oxidized region 2006b of the oxidized constricting layer 2006 is located below the optical aperture 2009 and functions as a current/light passing region for passing current and light.
- the surface emitting laser 2000 includes a first multilayer reflector 2011 and a second multilayer reflector 2012 .
- An example of the multilayer reflector is a semiconductor multilayer reflector, which is also called a distributed Bragg reflector.
- the surface emitting laser 2000 includes an active layer 2013.
- the active layer 2013 is arranged between the first multilayer reflector 2011 and the second multilayer reflector 2012 , confines injected carriers, and defines the emission wavelength of the surface emitting laser 2000 .
- the surface emitting laser 2000 is a surface emitting surface emitting laser, but the surface emitting laser 2000 can also be a back emitting surface emitting laser.
- the substantial diameter of the surface emitting laser 2000 of this configuration example is the diameter d of the virtual circle defined by the trench 2005. As shown in FIGS. 43 and 44A, the substantial diameter of the surface emitting laser 2000 of this configuration example is the diameter d of the virtual circle defined by the trench 2005. As shown in FIGS. 43 and 44A, the substantial diameter of the surface emitting laser 2000 of this configuration example is the diameter d of the virtual circle defined by the trench 2005. As shown in FIGS.
- the surface emitting laser 2000 of this configuration example is manufactured by the following steps 1 to 8.
- Step 1 On the surface of the substrate 2001, a first multilayer reflector 2011, an active layer 2013, a selectively oxidized layer to be the oxidized constricting layer 2006, and a second multilayer reflector 2012 are epitaxially grown.
- Step 2 A first electrode 2003 is formed on the second multilayer reflective mirror 2012 using, for example, a lift-off method.
- Step 3 A trench 2005 is formed by photolithography, for example.
- An oxidized constricting layer 2006 is formed by exposing the side surface of the selectively oxidized layer and selectively oxidizing the selectively oxidized layer from the side surface.
- Step 5 A protective region 2002 is formed by ion implantation or the like.
- Step 6 A dielectric layer 2007 is formed by vapor deposition, sputtering, or the like.
- Step 7) A dielectric opening 2008 is formed in the dielectric layer 2007 by photolithography, for example, to expose the contact of the first electrode 2003 .
- Step 8) After polishing the back surface of the substrate 2001 to thin it, the second electrode 2004 is formed on the back surface of the substrate 2001 .
- surface-emitting laser 2000 may include more layers, fewer layers, different layers, different structures, or different arrangements of layers than shown in FIGS. 43, 44A, and 44B.
- the present technology can be applied to the surface emitting laser 2000 described above and its modification.
- the n-type semiconductor layer of the tunnel junction may be a GaAs-based compound semiconductor, eg, a GaAs layer doped with Si at a high concentration (1 ⁇ 19 cm ⁇ 3 ) and having a thickness of 20 nm, for example.
- the guide/barrier region of the active layer may be composed of a GaAsP-based compound semiconductor (eg, GaAsP 0.10 ).
- the oxidized constricting layer 113 may not necessarily be provided in the surface emitting lasers of the above embodiments and modifications.
- the contact layer 114 may not necessarily be provided in the surface emitting lasers of the above embodiments and modifications.
- each spacer layer and each clad layer may be omitted as appropriate.
- the active layer may have a single-layer structure.
- the conductivity types (first and second conductivity types) may be interchanged.
- both the first and second multilayer reflectors 102 and 112 are semiconductor multilayer reflectors, but are not limited to this.
- the first multilayer reflector 102 may be a semiconductor multilayer reflector
- the second multilayer reflector 112 may be a dielectric multilayer reflector.
- a dielectric multilayer reflector is also a kind of distributed Bragg reflector.
- the first multilayer reflector 102 may be a dielectric multilayer reflector
- the second multilayer reflector 112 may be a semiconductor multilayer reflector.
- both the first and second multilayer reflectors 102 and 112 may be dielectric multilayer reflectors.
- a semiconductor multilayer reflector has little light absorption and is electrically conductive.
- the semiconductor multilayer reflector 112 is suitable for the second multilayer reflector 112 located on the emission side (surface side) and on the current path from the anode electrode 116 to each active layer.
- the dielectric multilayer reflector has very little light absorption.
- the dielectric multilayer film reflector is suitable for the second multilayer film reflector 112 on the output side (surface side).
- a surface-emitting surface-emitting laser that emits laser light from the top of the mesa has been described as an example. It is also applicable to a back emission type surface emitting laser. In this case, it is preferable to use a substrate that is transparent with respect to the oscillation wavelength, or to provide an opening serving as an emission port in the substrate.
- the surface emitting laser 10 using an AlGaAs-based compound semiconductor has been described as an example, but the present technology can also be applied to a surface emitting laser using a GaN-based compound semiconductor, for example.
- at least one of the first and second multilayer reflectors 102 and 112 may be a GaN-based semiconductor multilayer reflector, or at least one of the first and second multilayer reflectors 102 and 112 may be used.
- a GaN-based dielectric multilayer film reflector may also be used.
- Examples of the GaN-based compound semiconductor used for at least one of the first and second multilayer reflectors 102 and 112 include GaN/AlGaN.
- the technology (the present technology) according to the present disclosure can be applied to various products (electronic devices).
- the technology according to the present disclosure can be realized as a device mounted on any type of moving body such as automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility, airplanes, drones, ships, and robots. may
- a surface-emitting laser according to the present technology can be applied, for example, as a light source for devices that form or display images using laser light (for example, laser printers, laser copiers, projectors, head-mounted displays, head-up displays, etc.).
- FIG. 45 illustrates an example of a schematic configuration of a distance measuring device 1000 including a surface emitting laser 100 as an example of electronic equipment according to the present technology.
- the distance measuring device 1000 measures the distance to the subject S by a TOF (Time Of Flight) method.
- a distance measuring device 1000 includes a surface emitting laser 100 as a light source.
- Distance measuring device 1000 includes surface emitting laser 100, light receiving device 120, lenses 119 and 130, signal processing section 140, control section 150, display section 160 and storage section 170, for example.
- the light receiving device 120 detects the light reflected by the subject S.
- the lens 119 is a lens for collimating the light emitted from the surface emitting laser 100, and is a collimating lens.
- the lens 130 is a lens for condensing the light reflected by the subject S and guiding it to the light receiving device 120, and is a condensing lens.
- the signal processing section 140 is a circuit for generating a signal corresponding to the difference between the signal input from the light receiving device 120 and the reference signal input from the control section 150 .
- the control unit 150 includes, for example, a Time to Digital Converter (TDC).
- the reference signal may be a signal input from the control section 150 or an output signal of a detection section that directly detects the output of the surface emitting laser 100 .
- the control unit 150 is a processor that controls the surface emitting laser 100, the light receiving device 120, the signal processing unit 140, the display unit 160, and the storage unit 170, for example.
- the control unit 150 is a circuit that measures the distance to the subject S based on the signal generated by the signal processing unit 140 .
- the control unit 150 generates a video signal for displaying information about the distance to the subject S and outputs it to the display unit 160 .
- the display unit 160 displays information about the distance to the subject S based on the video signal input from the control unit 150 .
- the control unit 150 stores information about the distance to the subject S in the storage unit 170 .
- any one of the surface emitting lasers 100-1 to 100-6, 200, and 200-1 to 4 can be applied to the distance measuring device 1000 instead of the surface emitting laser 100.
- FIG. 9. Example of mounting a distance measuring device on a moving body>
- FIG. 46 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which the technology according to the present disclosure can be applied.
- a vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001.
- vehicle control system 12000 includes drive system control unit 12010 , body system control unit 12020 , vehicle exterior information detection unit 12030 , vehicle interior information detection unit 12040 , and integrated control unit 12050 .
- integrated control unit 12050 As the functional configuration of the integrated control unit 12050, a microcomputer 12051, an audio/image output unit 12052, and an in-vehicle network I/F (interface) 12053 are illustrated.
- the drive system control unit 12010 controls the operation of devices related to the drive system of the vehicle according to various programs.
- the driving system control unit 12010 includes a driving force generator for generating driving force of the vehicle such as an internal combustion engine or a driving motor, a driving force transmission mechanism for transmitting the driving force to the wheels, and a steering angle of the vehicle. It functions as a control device such as a steering mechanism to adjust and a brake device to generate braking force of the vehicle.
- the body system control unit 12020 controls the operation of various devices equipped on the vehicle body according to various programs.
- the body system control unit 12020 functions as a keyless entry system, a smart key system, a power window device, or a control device for various lamps such as headlamps, back lamps, brake lamps, winkers or fog lamps.
- the body system control unit 12020 can receive radio waves transmitted from a portable device that substitutes for a key or signals from various switches.
- the body system control unit 12020 receives the input of these radio waves or signals and controls the door lock device, power window device, lamps, etc. of the vehicle.
- the vehicle exterior information detection unit 12030 detects information outside the vehicle in which the vehicle control system 12000 is installed.
- a distance measuring device 12031 is connected to the vehicle exterior information detection unit 12030 .
- Distance measuring device 12031 includes distance measuring device 1000 described above.
- the vehicle exterior information detection unit 12030 causes the distance measuring device 12031 to measure the distance to an object (subject S) outside the vehicle, and acquires the distance data thus obtained.
- the vehicle exterior information detection unit 12030 may perform object detection processing such as people, vehicles, obstacles, and signs based on the acquired distance data.
- the in-vehicle information detection unit 12040 detects in-vehicle information.
- the in-vehicle information detection unit 12040 is connected to, for example, a driver state detection section 12041 that detects the state of the driver.
- the driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 detects the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041. It may be calculated, or it may be determined whether the driver is dozing off.
- the microcomputer 12051 calculates control target values for the driving force generator, the steering mechanism, or the braking device based on information on the inside and outside of the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040, and controls the drive system control unit.
- a control command can be output to 12010 .
- the microcomputer 12051 realizes the functions of ADAS (Advanced Driver Assistance System) including collision avoidance or shock mitigation, follow-up driving based on inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane deviation warning, etc. Cooperative control can be performed for the purpose of ADAS (Advanced Driver Assistance System) including collision avoidance or shock mitigation, follow-up driving based on inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane deviation warning, etc. Cooperative control can be performed for the purpose of ADAS (Advanced Driver Assistance System) including collision avoidance or shock mitigation, follow-up driving based on inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning
- the microcomputer 12051 controls the driving force generator, the steering mechanism, the braking device, etc. based on the information about the vehicle surroundings acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040, so that the driver's Cooperative control can be performed for the purpose of autonomous driving, etc., in which vehicles autonomously travel without depending on operation.
- the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the information detection unit 12030 outside the vehicle.
- the microcomputer 12051 controls the headlamps according to the position of the preceding vehicle or the oncoming vehicle detected by the vehicle exterior information detection unit 12030, and performs coordinated control aimed at anti-glare such as switching from high beam to low beam. It can be carried out.
- the audio/image output unit 12052 transmits at least one of audio and/or image output signals to an output device capable of visually or audibly notifying the passengers of the vehicle or the outside of the vehicle.
- an audio speaker 12061, a display unit 12062 and an instrument panel 12063 are illustrated as output devices.
- the display unit 12062 may include at least one of an on-board display and a head-up display, for example.
- FIG. 47 is a diagram showing an example of the installation position of the distance measuring device 12031.
- the vehicle 12100 has distance measuring devices 12101, 12102, 12103, 12104, and 12105 as the distance measuring device 12031.
- the distance measuring devices 12101, 12102, 12103, 12104, and 12105 are provided at positions such as the front nose, side mirrors, rear bumper, back door, and windshield of the vehicle 12100, for example.
- a distance measuring device 12101 provided on the front nose and a distance measuring device 12105 provided on the upper part of the windshield inside the vehicle mainly acquire data in front of the vehicle 12100 .
- Distance measuring devices 12102 and 12103 provided in the side mirrors mainly acquire side data of the vehicle 12100 .
- a distance measuring device 12104 provided on the rear bumper or back door mainly acquires data behind the vehicle 12100 .
- the forward data acquired by the distance measurement devices 12101 and 12105 are mainly used for detecting preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, and the like.
- FIG. 47 shows an example of the detection ranges of the distance measuring devices 12101 to 12104.
- a detection range 12111 indicates the detection range of the distance measuring device 12101 provided on the front nose
- detection ranges 12112 and 12113 indicate the detection ranges of the distance measuring devices 12102 and 12103 provided on the side mirrors, respectively
- a detection range 12114 indicates the detection range of the distance measuring device 12104 provided on the rear bumper or back door.
- the microcomputer 12051 determines the distance to each three-dimensional object within the detection ranges 12111 to 12114 and changes in this distance over time (relative velocity to the vehicle 12100). ), the closest three-dimensional object on the course of the vehicle 12100, which is traveling at a predetermined speed (e.g., 0 km/h or more) in substantially the same direction as the vehicle 12100, is extracted as the preceding vehicle. can be done. Furthermore, the microcomputer 12051 can set the inter-vehicle distance to be secured in advance in front of the preceding vehicle, and can perform automatic braking control (including following stop control) and automatic acceleration control (including following start control). In this way, cooperative control can be performed for the purpose of automatic driving in which the vehicle autonomously travels without depending on the operation of the driver.
- automatic braking control including following stop control
- automatic acceleration control including following start control
- the microcomputer 12051 based on the distance data obtained from the distance measuring devices 12101 to 12104, converts three-dimensional object data to other three-dimensional objects such as two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, etc. can be used for automatic avoidance of obstacles.
- microcomputer 12051 distinguishes obstacles around vehicle 12100 into obstacles visible to the driver of vehicle 12100 and obstacles difficult to see. Then, the microcomputer 12051 judges the collision risk indicating the degree of danger of collision with each obstacle, and when the collision risk is equal to or higher than the set value and there is a possibility of collision, the obstacle is detected through the audio speaker 12061 and the display unit 12062. By outputting an alarm to the driver via the drive system control unit 12010 and performing forced deceleration and avoidance steering via the drive system control unit 12010, driving assistance for collision avoidance can be performed.
- this technique can also take the following structures.
- first and second multilayer film reflectors a plurality of active layers stacked between the first and second multilayer reflectors; a tunnel junction disposed between two active layers adjacent in the stacking direction among the plurality of active layers; an oxidized constricting layer disposed between one of the two adjacent active layers and the tunnel junction; A surface-emitting laser.
- the one active layer is arranged at a position closer to the other of the first and second multilayer film reflectors, which is farther from the emission surface than the one closer to the emission surface of the surface-emitting laser, ( The surface emitting laser according to 1) or (2).
- the one active layer is arranged at a position closer to the other of the first and second multilayer film reflectors, which is closer to the emission surface than the one farther from the emission surface of the surface-emitting laser, ( The surface emitting laser according to 1) or (2).
- the one active layer is arranged at a position closer to the other of the first and second multilayer film reflectors, which is farther from the emission surface than the one closer to the emission surface of the surface-emitting laser, ( The surface emitting laser according to 1) or (5).
- the one active layer is arranged at a position closer to the other of the first and second multilayer mirrors that is closer to the exit surface than to the other that is farther from the exit surface; (1) or ( 5) The surface emitting laser described in 5).
- the plurality of active layers are at least three active layers;
- the tunnel junction is disposed between two adjacent active layers of each set of at least two sets of two adjacent active layers among the plurality of active layers; between one active layer of at least one set of two adjacent active layers out of the at least two sets of two adjacent active layers and the tunnel junction disposed between the two adjacent active layers;
- the surface emitting laser according to any one of (1) to (7), wherein the oxidized constricting layer is arranged.
- said at least three active layers comprise first, second and third active layers, said first, second and third active layers being stacked in this order, said first and second active layers
- a first tunnel junction, which is the tunnel junction, is arranged between the tunnel junction
- a second tunnel junction, which is the tunnel junction is arranged between the second and third active layers, the first active layer and the first tunnel (8), wherein the oxidized constriction layer is arranged between the junction and/or between the second active layer and the second tunnel junction.
- the tunnel junction has a layered structure in which a p-type semiconductor layer and an n-type semiconductor layer are stacked, and the oxidized constricting layer is disposed on the p-type semiconductor layer side.
- the surface emitting laser according to any one of (16).
- the oscillation wavelength of the surface-emitting laser is ⁇
- the one active layer, the tunnel junction, and the oxidized constricting layer are arranged within an optical thickness of 3 ⁇ /4, (1) to (17) ).
- An electronic device comprising the surface emitting laser according to any one of (1) to (18).
- a method of manufacturing a surface emitting laser comprising: (21) A surface emitting laser array comprising a plurality of surface emitting lasers according to any one of (1) to (20). (22) An electronic device comprising the surface emitting laser according to any one of (1) to (20). (23) An electronic device comprising the surface emitting laser array according to (21).
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Abstract
Description
前記第1及び第2多層膜反射鏡の間に互いに積層された複数の活性層と、
前記複数の活性層のうち積層方向に隣り合う2つの活性層の間に配置されたトンネルジャンクションと、
前記隣り合う2つの活性層の一方の活性層と前記トンネルジャンクションとの間に配置された酸化狭窄層と、
を備える、面発光レーザを提供する。
前記一方の活性層は、前記隣り合う2つの活性層の他方の活性層よりも前記面発光レーザの出射面から遠い位置に配置されていてもよい。
前記一方の活性層は、前記第1及び第2多層膜反射鏡のうち前記出射面から近い一方よりも前記出射面から遠い他方に近い位置に配置されていてもよい。
前記一方の活性層は、前記第1及び第2多層膜反射鏡のうち前記出射面から遠い一方よりも前記出射面から近い他方に近い位置に配置されてもよい。
前記一方の活性層は、前記隣り合う2つの活性層の他方の活性層よりも前記面発光レーザの出射面から近い位置に配置されていてもよい。
前記一方の活性層は、前記第1及び第2多層膜反射鏡のうち前記出射面から近い一方よりも前記出射面から遠い他方に近い位置に配置されていてもよい。
前記一方の活性層は、前記第1及び第2多層膜反射鏡のうち前記出射面から遠い一方よりも前記出射面から近い他方に近い位置に配置されていてもよい。
前記複数の活性層は、少なくとも3つの活性層であり、前記複数の活性層のうち少なくとも2組の隣り合う2つの活性層の各組の隣り合う2つの活性層の間に前記トンネルジャンクションが配置され、前記少なくとも2組の隣り合う2つの活性層のうち少なくとも1組の隣り合う2つの活性層の一方の活性層と、該隣り合う2つの活性層の間に配置された前記トンネルジャンクションとの間に前記酸化狭窄層が配置されていてもよい。
前記少なくとも3つの活性層は、第1、第2及び第3活性層を含み、前記第1、第2及び第3活性層は、この順に積層され、前記第1及び第2活性層の間に前記トンネルジャンクションである第1トンネルジャンクションが配置され、前記第2及び第3活性層の間に前記トンネルジャンクションである第2トンネルジャンクションが配置され、前記第1活性層と前記第1トンネルジャンクションとの間及び/又は前記第2活性層と前記第2トンネルジャンクションとの間に前記酸化狭窄層が配置されていてもよい。
前記第1活性層は、前記複数の活性層の中で前記面発光レーザの出射面から最も遠い位置に配置された活性層であってもよい。
前記第1活性層と前記第1トンネルジャンクションとの間に前記酸化狭窄層である第1酸化狭窄層が配置されていてもよい。
前記第2活性層と前記第2トンネルジャンクションとの間に前記酸化狭窄層である第2酸化狭窄層が配置されていてもよい。
前記第2活性層と前記第2トンネルジャンクションとの間に前記酸化狭窄層が配置されていなくてもよい。
前記第1及び第2多層膜反射鏡のうち前記面発光レーザの出射面に近い方の内部に別の酸化狭窄層が配置されていてもよい。
前記酸化狭窄層及び前記別の酸化狭窄層は、いずれもAlGaAs系化合物半導体からなる層を選択酸化して形成されていてもよい。
前記酸化狭窄層及び前記別の酸化狭窄層は、Al組成及び/又は光学厚さが互いに異なっていてもよい。
前記トンネルジャンクションは、p型半導体層及びn型半導体層が互いに積層された層構造を有し、前記酸化狭窄層は、前記p型半導体層側に配置されていてもよい。
前記面発光レーザの発振波長をλとすると、前記一方の活性層と前記トンネルジャンクションと前記酸化狭窄層とが光学厚さ3λ/4内に配置されていてもよい。
本技術は、前記面発光レーザを備える電子機器も提供する。
本技術は、第1多層膜反射鏡上に第1活性層、被選択酸化層、トンネルジャンクション及び第2活性層がこの順に積層された積層構造を含む構造体を積層し、該構造体上に少なくとも第2多層膜反射鏡を積層して積層体を生成する工程と、
前記積層体を少なくとも前記被選択酸化層の側面が露出するまでエッチングしてメサを形成する工程と、
前記被選択酸化層を側面側から選択的に酸化して酸化狭窄層を形成する工程と、
を含む、面発光レーザの製造方法も提供する。
1.本技術の第1実施形態に係る面発光レーザ
(1)面発光レーザの構成
(2)面発光レーザの動作
(3)面発光レーザの製造方法
(4)面発光レーザ及びその製造方法の効果
2.本技術の第1実施形態の変形例1~5に係る面発光レーザ
3.本技術の第2実施形態に係る面発光レーザ
(1)面発光レーザの構成
(2)面発光レーザの動作
(3)面発光レーザの製造方法
(4)面発光レーザの効果
4.本技術の第2実施形態の変形例1~4に係る面発光レーザ
5.本技術を適用し得る面発光レーザの構成例
6.本技術の変形例
7.電子機器への応用例
8.面発光レーザを距離測定装置に適用した例
9.距離測定装置を移動体に搭載した例
(1)面発光レーザの構成
図1は、本技術の第1実施形態に係る面発光レーザ100の構成を示す断面図である。以下では、便宜上、図1等の断面図における上方を上、下方を下として説明する。
第1及び第2活性層104-1、104-2は、第1及び第2多層膜反射鏡102、112の間に互いに積層されている。
トンネルジャンクション108は、複数の活性層のうち積層方向(上下方向)に隣り合う2つの活性層である第1及び第2活性層104-1、104-2の間に配置されている。
酸化狭窄層106は、一例として、積層方向に隣り合う2つの活性層である第1及び第2活性層104-1、104-2の一方の活性層である第1活性層104-1とトンネルジャンクション108との間に配置されている。
基板101は、一例として、第1導電型(例えばn型)の半導体基板(例えばGaAs基板)である。基板101の裏面(下面)には、n側電極であるカソード電極117が設けられている。
カソード電極117は、例えばAuGe/Ni/Auからなる。
第1多層膜反射鏡102は、一例として、基板101上に配置されている。
第1多層膜反射鏡102は、一例として、半導体多層膜反射鏡である。多層膜反射鏡は、分布型ブラッグ反射鏡(Distributed Bragg Reflector)とも呼ばれる。多層膜反射鏡(分布型ブラッグ反射鏡)の一種である半導体多層膜反射鏡は、光吸収が少なく、高反射率及び導電性を有する。
詳述すると、第1多層膜反射鏡102は、一例として、第1導電型(例えばn型)の半導体多層膜反射鏡であり、屈折率が互いに異なる複数種類(例えば2種類)の半導体層が発振波長の1/4波長の光学厚さで交互に積層された構造を有する。第1多層膜反射鏡102の各屈折率層は、第1導電型(例えばn型)のAlGaAs系化合物半導体からなる。
第1活性層104-1は、一例として、ノンドープのAlGaAs系化合物半導体からなる第1クラッド層103を介して第1多層膜反射鏡102上に配置されている。なお、「クラッド層」は「スペーサ層」とも呼ばれる。
第1活性層104-1は、一例として、ノンドープのInGaAs系化合物半導体(例えばIn0.10GaAs)からなる活性領域と、ノンドープのAlGaAs系化合物半導体(例えばAl0.10GaAs)からなるガイド・バリア領域(但し、積層方向の両端がガイド領域、積層方向の中間がバリア領域)とが交互に積層された積層構造を有している。ここでは、第1活性層104は、例えば2層のガイド領域、2層のバリア領域及び3層の活性領域を有している。
各活性領域の厚さは、例えば7nmとされている。積層方向の両端のガイド領域の厚さは、例えば10nmとされている。積層方向の中間のバリア領域の厚さは、例えば8nmとされている。
面発光レーザ100は、第1活性層104-1が当該積層構造を有することにより、例えば900nm帯を発振波長としたレーザ発振を行うことが可能である。
酸化狭窄層106は、一例として、ノンドープのAlGaAs系化合物半導体からなるスペーサ層105を介して第1活性層104-1上に配置されている。なお、スペーサ層は「クラッド層」とも呼ばれる。
酸化狭窄層106は、一例として、AlGaAs系化合物半導体(例えばAlGaAs、AlAs等)からなる非酸化領域106aと、その周囲を取り囲むAlGaAs系化合物半導体の酸化物(例えばAl2O3)からなる酸化領域106bとを有する。酸化狭窄層106の基材(後述する被選択酸化層106S)としては、Al組成が90%以上のAlGaAs膜を用いることが好ましい。
面発光レーザ100の発振波長をλとすると、第1活性層104-1とトンネルジャンクション108と酸化狭窄層106とが光学厚さ3λ/4内に配置されている。
酸化狭窄層は「電流狭窄層」とも呼ばれる。
トンネルジャンクション108は、一例として、ノンドープのAlGaAs系化合物半導体からなるスペーサ層107を介して酸化狭窄層106上に配置されている。
トンネルジャンクション108は、互いに積層されたp型半導体層108a及びn型半導体層108bを含む。p型半導体層108aは、一例として、n型半導体層108bの基板101側(下側)に配置されている。より詳細には、p型半導体層108aは、一例として、酸化狭窄層106とn型半導体層108bとの間にn型半導体層108bと接するように配置されている。
p型半導体層108aは、一例として、キャリア濃度が高いGaAs系化合物半導体、AlGaAs系化合物半導体、InGaAs系化合物半導体又はAlGaInP系化合物半導体からなる。p型半導体層108aのドーパント材料としては、例えばC、Zn、Mg等を用いることができる。p型半導体層108aとして、例えばC(炭素)が高濃度(例えば1x1020cm-3)にドープされた厚さ10nmのGaAs層を用いることができる。
n型半導体層107bは、一例として、キャリア濃度が高いn型のGaAs系化合物半導体、AlGaAs系化合物半導体、InGaAs系化合物半導体又はAlGaInP系化合物半導体からなる。n型半導体層108bのドーパント材料としては、Si、Te、Se等を用いることができる。n型半導体層108bとして、例えばSi(シリコン)が高濃度(例えば5x1019cm-3)にドープされた厚さ20nmのGaAs層を用いることができる。
第2活性層104-2は、一例として、ノンドープのAlGaAs系化合物半導体からなるスペーサ層109を介してトンネルジャンクション108上に配置されている。
第2活性層104-2は、一例として、第1活性層104-1と同様の層構成を有する。すなわち、第2活性層104-2は、一例として、ノンドープのInGaAs系化合物半導体(例えばIn0.10GaAs)からなる活性領域と、ノンドープのAlGaAs系化合物半導体(例えばAl0.10GaAs)からなるガイド・バリア領域(但し、積層方向の両端がガイド領域、積層方向の中間がバリア領域)とが交互に積層された積層構造を有している。ここでは、第2活性層104-2は、例えば2層のガイド領域、2層のバリア領域及び3層の活性領域を有している。
各活性領域の膜厚は、例えば7nmとされている。積層方向の両端のガイド領域の膜厚は、例えば10nmとされている。積層方向の中間のバリア領域の膜厚は、例えば8nmとされている。
面発光レーザ100は、第2活性層104-2が当該積層構造を有することにより、例えば900nm帯を発振波長としたレーザ発振を行うことが可能である。
第2多層膜反射鏡112は、一例として、ノンドープのAlGaAs系化合物半導体からなる第2クラッド層111を介して第2活性層104-2上に配置されている。
第2多層膜反射鏡112は、一例として、半導体多層膜反射鏡である。多層膜反射鏡は、分布型ブラッグ反射鏡(Distributed Bragg Reflector)とも呼ばれる。多層膜反射鏡(分布型ブラッグ反射鏡)の一種である半導体多層膜反射鏡は、光吸収が少なく、高反射率及び導電性を有する。
詳述すると、第2多層膜反射鏡112は、一例として、第2導電型(例えばp型)の半導体多層膜反射鏡であり、屈折率が互いに異なる複数種類(例えば2種類)の半導体層が発振波長の1/4波長の光学厚さで交互に積層された構造を有する。第2多層膜反射鏡112の各屈折率層は、第2導電型(例えばp型)のAlGaAs系化合物半導体からなる。第2多層膜反射鏡112は、一例として、第1多層膜反射鏡102よりも反射率が僅かに低く設定されている。
すなわち、メサM1の頂部(例えばコンタクト層114)上の絶縁膜115にはコンタクトホール115aが形成されており、該コンタクトホール115a内にp側電極である環状のアノード電極116がメサM1の頂部(例えばコンタクト層114)に接触するように設けられている。アノード電極116は、一例として、積層方向から見て中心が酸化狭窄層113の中心に略一致するようにコンタクトホール115a内に配置されている。アノード電極116の内側がレーザ光の出射口となっている。
アノード電極116は、単層構造であってもよいし、積層構造であってもよい。
アノード電極116は、例えばTi/Pt/Auからなる。
図1に示す面発光レーザ100では、アノード電極116とカソード電極117との間に電圧が印加されアノード電極116からメサM1を含む共振器構造体に電流が流入されると、該電流が酸化狭窄層113で狭窄されて第2活性層104-2に注入されるとともに、トンネルジャンクション108によるトンネル効果によりその注入された電流と略同一の電流値の電流が酸化狭窄層106で狭窄されて第1活性層104-1に注入される。これにより、第1及び第2活性層104-1、104-2が略同一の発光強度で発光し、それらの光が第1及び第2多層膜反射鏡102、112の間において各活性層で増幅されながら往復して発振条件を満たしたときに、メサM1の頂部からレーザ光として出射される。
以下、面発光レーザ100の製造方法について、図2のフローチャート(ステップS1~S7)を参照して説明する。図2は、面発光レーザ100のみならず面発光レーザ100の派生系も製造可能な手順を示す。ここでは、一例として、半導体製造装置を用いた半導体製造方法により、基板101の基材である1枚のウェハ上に、複数の面発光レーザ100が2次元配置された面発光レーザアレイを複数同時に生成する。次いで、一連一体の複数の面発光レーザアレイをダイシングにより分離して、チップ状の複数の面発光レーザアレイ(面発光レーザアレイチップ)を得る。なお、以下に説明する製造方法により、基板101の基材である1枚のウェハ上に複数の面発光レーザ100を複数同時に生成し、一連一体の複数の面発光レーザ100をダイシングにより分離して、チップ状の面発光レーザ(面発光レーザチップ)を得ることも可能である。以下の一連の工程は、半導体製造装置のCPUにより実行される。
最初のステップS1では、積層体生成処理1を実施する。積層体生成処理1では、一例として、化学気層成長(CVD)法、例えば有機金属気層成長(MOCVD)法により、成長室において面発光レーザ100を構成する各層を順次積層して積層体L1(図11参照)を生成する。具体的には、以下に詳述するように、例えば、第1多層膜反射鏡102上に第1活性層104-1、被選択酸化層106S、トンネルジャンクション108及び第2活性層104-2がこの順に積層された積層構造を含む構造体を積層し、該構造体上に被選択酸化層113Sを内部に含む第2多層膜反射鏡112を積層して積層体L1を生成する。
ステップS1-1では、基板101上に第1多層膜反射鏡102を積層する(図4参照)。
ステップS1-2では、共振器基材生成工程1を実施する。共振器基材生成工程1は、以下に詳述するように、第1多層膜反射鏡102上に共振器Rとなる共振器基材を生成する工程である。
以下、共振器基材生成工程1について、図5のフローチャート、図6~図10(第1積層工程図~第5積層工程図)を参照して説明する。
ステップS1-3では、共振器基材上に第2多層膜反射鏡112を積層する(図11参照)。より詳細には、共振器基材の第2クラッド層111上に、被選択酸化層113Sを内部に含む第2多層膜反射鏡112及びコンタクト層114をこの順に積層する。この結果、積層体(例えば積層体L1)が生成される。ステップS1-3が実行されると、積層体生成処理1が終了する。
ステップS2では、積層体(例えば積層体L1)をエッチングしてメサ(例えばメサM1)を形成する(図12参照)。
具体的には、例えば、成長室から取り出した積層体L1上にフォトリソグラフィによりレジストパターンを形成する。次いで、このレジストパターンをマスクとして、例えばRIEエッチング(反応性イオンエッチング)により、積層体L1を少なくとも被選択酸化層106Sの側面が露出するまでエッチングして、メサM1を形成する。ここでのエッチングは、一例として、第1クラッド層103の側面が完全に露出するまで(例えばエッチング底面が第1多層膜反射鏡102内に位置するまで)行う。その後、該レジストパターンを除去する。
ステップS3では、被選択酸化層106S、113S(図12参照)の周囲部を酸化して酸化狭窄層106、113を生成する(図13参照)。
具体的には、例えば、メサM1を水蒸気雰囲気中にさらし、被選択酸化層106S、113Sを側面から酸化(選択酸化)して、非酸化領域106aの周りが酸化領域106bで取り囲まれた酸化狭窄層106を形成するとともに、被酸化領域113aの周りが酸化領域113bで取り囲まれた酸化狭窄層113を形成する。
ステップS4では、絶縁膜115を形成する(図14参照)。具体的には、例えば、メサM1が形成された積層体の略全域に絶縁膜115を成膜する。
ステップS5では、コンタクトホール115aを形成する(図15参照)。具体的には、例えば、メサM1の頂部上に形成された絶縁膜115以外の絶縁膜115上にフォトリソグラフィによりレジストパターンを形成する。次いで、このレジストパターンをマスクとして、メサM1の頂部上に形成された絶縁膜115を例えばフッ酸系のエッチャントを用いてエッチングにより除去する。その後、該レジストパターンを除去する。この結果、コンタクトホール115aが形成され、コンタクト層114が露出する。
ステップS6では、アノード電極116を形成する(図16参照)。具体的には、例えば、EB蒸着法により、コンタクトホール115aを介してコンタクト層114上に例えばTi/Pt/Au膜を成膜し、レジスト及びレジスト上の例えばTi/Pt/Auをリフトオフすることにより、コンタクトホール115a内に環状のアノード電極116を形成する。
ステップS7では、カソード電極117を形成する(図17参照)。具体的には、基板101の裏面(下面)を研磨した後、該裏面に例えばAuGe/Ni/Au膜を成膜する。ステップS7が実行されると、図2のフローは終了する。
本技術の第1実施形態に係る面発光レーザ100は、第1及び第2多層膜反射鏡102、112と、第1及び第2多層膜反射鏡102、112の間に互いに積層された複数の活性層(例えば第1及び第2活性層104-1、104-2)と、該複数の活性層のうち積層方向に隣り合う2つの活性層である第1及び第2活性層104-1、104-2の間に配置されたトンネルジャンクション108と、隣り合う2つの活性層の一方の活性層である第1活性層104-1とトンネルジャンクション108との間に配置された酸化狭窄層106と、を備える、面発光レーザである。
この場合、例えば、第2活性層104-2に注入されトンネルジャンクション108を介した電流は、酸化狭窄層106で狭窄されて第1活性層104-1に注入される。これにより、第1活性層104-1に効率良く電流を注入することができ、第1活性層104-1での発光効率の低下を抑制できる。
結果として、第1実施形態の面発光レーザ100によれば、発光効率の低下を抑制できる面発光レーザを提供できる。
なお、仮に共振器内に酸化狭窄層106が設けられていない場合には、例えば出射面ES側から共振器に供給された電流は、共振器内において広がりながら、第2活性層104-2、第1活性層104-1にこの順に注入されることになる。この場合、第1活性層104-1は第2活性層104-2よりも共振器内における電流経路の下流端側に位置するため、より広がった電流が注入されることになる。すなわち、第1活性層104-1の方が第2活性層104-2よりも電流注入効率に関して不利な位置にある。このため、第1活性層104-1に注入される電流を狭窄できることの意義は大きい。
なお、上記一方の活性層(トンネルジャンクション108とで酸化狭窄層106を挟む活性層)である第1活性層104-1は、第1及び第2多層膜反射鏡102、112のうち出射面ESから遠い一方である第1多層膜反射鏡102よりも出射面ESから近い他方である第2多層膜反射鏡112に近い位置(例えば共振器Rの上半部)に配置されていてもよい。この場合、酸化狭窄層106、トンネルジャンクション108及び第2活性層104-2も、第1多層膜反射鏡102よりも第2多層膜反射鏡112に近い位置(例えば共振器Rの上半部)に配置されてもよい。
これにより、発光効率の低下を抑制可能な屈折率ガイド型の面発光レーザ100を製造することができる。
以下、本技術の第1実施形態の変形例1~5に係る面発光レーザについて説明する。
面発光レーザ100-1では、トンネルジャンクション108とで第2酸化狭窄層106-2を挟む活性層である第2活性層104-2は、第1活性層104-1よりも面発光レーザ100の出射面ESから近い位置に配置されている。これにより、第2酸化狭窄層106-2を出射面ESからより近い位置(少なくともトンネルジャンクション108よりも出射面ESから近い位置)に配置することができ、該位置での電流狭窄効果を得ることができる。すなわち、第1及び第2多層膜反射鏡102、112の間に設けられた共振器において出射面ESからより近い位置(少なくとも酸化狭窄層106よりも出射面ESから近い位置、例えば共振器の上半部)での電流狭窄効果を得ることができ、第2活性層104-2への電流注入効率を向上することができる。
面発光レーザ100-1では、アノード電極116から流入された電流は、基板101及び第1多層膜反射鏡102を経て第1酸化狭窄層106-1で狭窄され第1活性層104-2に注入される。第1活性層104-1を介した電流は、トンネルジャンクション108を経て酸化狭窄層106-2により狭窄され第2活性層104-2に注入される。これにより、各活性層に効率良く電流を注入することができる。
なお、トンネルジャンクション108とで酸化狭窄層106-2を挟む活性層である第2活性層104-2は、第1及び第2多層膜反射鏡102、112のうち出射面ESから近い一方である第2多層膜反射鏡112よりも出射面ESから遠い他方である第1多層膜反射鏡102に近い位置(例えば共振器の下半部)に配置されていてもよい。この場合、酸化狭窄層106、トンネルジャンクション108及び第1活性層104-1も、第2多層膜反射鏡112よりも第1多層膜反射鏡102に近い位置(例えば共振器の下半部)に配置されてもよい。
変形例1の面発光レーザ100-1は、積層体生成処理において、酸化狭窄層113に代えてもう1つの酸化狭窄層106が形成される点及び積層順が一部異なる点を除いて、第1実施形態の面発光レーザ100(図1参照)の製造方法と同様の製造方法により製造できる。
変形例2の面発光レーザ100-3は、図19に示すように、第1及び第2多層膜反射鏡102、112の間に、第1多層膜反射鏡102側から活性層、酸化狭窄層及びトンネルジャンクションがこの順に積層された積層構造を複数(例えば2つ)有する点を除いて、第1実施形態の面発光レーザ100(図1参照)と同様の構成を有する。
詳述すると、面発光レーザ100-3は、第1多層膜反射鏡102側から第1活性層104-1、第1酸化狭窄層106-1及び第1トンネルジャンクション108-1がこの順に積層された第1積層構造を有する。さらに、面発光レーザ100-3は、該第1積層構造上に、第1多層膜反射鏡102側から第2活性層104-2、第2酸化狭窄層106-2及び第2トンネルジャンクション108-2がこの順に積層された第2積層構造を有する。第1及び第2トンネルジャンクション108-1、108-2は、トンネルジャンクション108と実質的に同一の構成及び機能を有する。さらに、面発光レーザ100-3は、該第2積層構造上に第3活性層104-3を有する。
面発光レーザ100-3は、面発光レーザ100の派生系であり、図5のフローチャートの手順(但し、ステップS1-2-6においてN=2とする)で製造することができる。
変形例3の面発光レーザ100-4は、図20に示すように、第1及び第2多層膜反射鏡102、112の間に、第1多層膜反射鏡102側からトンネルジャンクション、酸化狭窄層及び活性層がこの順に積層された積層構造を複数(例えば2つ)有する点、酸化狭窄層113に代えてもう1つの酸化狭窄層106が第1多層膜反射鏡102と第1活性層104-1との間に設けられている点及び導電型が逆な点を除いて、変形例2の面発光レーザ100-3(図19参照)と同様の構成を有する。
すなわち、面発光レーザ100-4は、面発光レーザ100-3を上下逆さにしたような構成を有する。面発光レーザ100-4では、第1多層膜反射鏡102の導電型がp型であり、且つ、第2多層膜反射鏡112の導電型がn型であり、且つ、アノード電極116が基板101の裏面側に配置され、且つ、カソード電極117がメサの頂部に配置され、且つ、各トンネルジャンクションにおいてn型半導体層108b(図20において灰色の層)がp型半導体層108aの基板101側に配置されている。
詳述すると、面発光レーザ100-4は、第1多層膜反射鏡102側から第1トンネルジャンクション108-1、第1酸化狭窄層106-1及び第2活性層104-2がこの順に積層された第1積層構造を有する。さらに、面発光レーザ100-4は、該第1積層構造上に、第1多層膜反射鏡102側から第2トンネルジャンクション108-2、第2酸化狭窄層106-2及び第3活性層104-3がこの順に積層された第2積層構造を有する。さらに、面発光レーザ100-4は、該第1積層構造下に第1活性層104-1を有する。
面発光レーザ100-4によれば、活性層の数が3つのマルチ活性層の場合でも、各活性層に効率良く電流を注入でき、該活性層の発光効率の低下を抑制できる。
面発光レーザ100-4は、積層体生成処理において、酸化狭窄層113に代えて酸化狭窄層106が形成される点及び積層順が異なる点を除いて、変形例2の面発光レーザ100-3(図19参照)の製造方法と同様の製造方法により製造できる。
変形例4の面発光レーザ100-5は、図21に示すように、第1及び第2多層膜反射鏡102、112の間に、活性層、酸化狭窄層及びトンネルジャンクションが第1多層膜反射鏡102側からこの順に積層された積層構造を複数(例えば3つ)有する点を除いて、第1実施形態の面発光レーザ100(図1参照)と同様の構成を有する。
詳述すると、面発光レーザ100-5は、第1多層膜反射鏡102側から第1活性層104-1、第1酸化狭窄層106-1及び第1トンネルジャンクション108-1がこの順に積層された第1積層構造を有する。さらに、面発光レーザ100-5は、該第1積層構造上に、第1多層膜反射鏡102側から第2活性層104-2、第2酸化狭窄層106-2及び第2トンネルジャンクション108-2がこの順に積層された第2積層構造を有する。さらに、面発光レーザ100-5は、該第2積層構造上に、第1多層膜反射鏡102側から第3活性層104-3、第3酸化狭窄層106-3及び第3トンネルジャンクション108-3がこの順に積層された第3積層構造を有する。第3トンネルジャンクション108-3は、トンネルジャンクション108と実質的に同一の構成及び機能を有する。さらに、面発光レーザ100-5は、該第3積層構造上に第4活性層104-4を有する。
面発光レーザ100-5によれば、活性層の数が4つのマルチ活性層の場合でも、各活性層に効率良く電流を注入でき、該活性層の発光効率の低下を抑制できる。なお、上記積層構造を4つ以上有し、且つ、酸化狭窄層113を有する面発光レーザ(面発光レーザ100の派生系)によれば、活性層の数が5つ以上のマルチ活性層の場合でも、各活性層に効率良く電流を注入でき、該活性層の発光効率の低下を抑制できる。
面発光レーザ100-5は、面発光レーザ100の派生系であり、面発光レーザ図5のフローチャートの手順(但し、ステップS1-2-6においてN=3とする)で製造することができる。なお、同様の製法(但し、図5のステップS1-2-6においてN≧4とする)により、上記積層構造を4つ以上有する面発光レーザを製造することができる。
変形例5の面発光レーザ100-6は、図22に示すように、第1及び第2多層膜反射鏡102、112の間に、トンネルジャンクション、酸化狭窄層及び活性層が第1多層膜反射鏡102側からこの順に積層された積層構造を複数(例えば3つ)有する点、酸化狭窄層113に代えてもう1つの酸化狭窄層106が第1多層膜反射鏡102と第1活性層104-1との間に設けられている点及び導電型が逆な点を除いて、変形例4の面発光レーザ100-5(図21参照)と同様の構成を有する。すなわち、面発光レーザ100-6は、面発光レーザ100-5を上下逆さにしたような構成を有する。面発光レーザ100-6では、第1多層膜反射鏡102の導電型がp型であり、且つ、第2多層膜反射鏡112の導電型がn型であり、且つ、アノード電極116が基板101の裏面側に配置され、且つ、カソード電極117がメサの頂部に配置され、且つ、各トンネルジャンクションにおいてn型半導体層108b(図22において灰色の層)がp型半導体層108aの基板101側に配置されている。
詳述すると、面発光レーザ100-6は、第1多層膜反射鏡102側から第1トンネルジャンクション108-1、第1酸化狭窄層106-1及び第2活性層104-2がこの順に積層された第1積層構造を有する。さらに、面発光レーザ100-6は、該第1積層構造上に、第1多層膜反射鏡102側から第2トンネルジャンクション108-2、第2酸化狭窄層106-2及び第3活性層104-3がこの順に積層された第2積層構造を有する。さらに、面発光レーザ100-6は、該第2積層構造上に、第1多層膜反射鏡102側から第3トンネルジャンクション108-3、第3酸化狭窄層106-3及び第4活性層104-4がこの順に積層された第3積層構造を有する。さらに、面発光レーザ100-6は、該第1積層構造下に第1活性層104-1を有する。
面発光レーザ100-6によれば、活性層の数が4つのマルチ活性層の場合でも、各活性層に効率良く電流を注入でき、該活性層の発光効率の低下を抑制できる。なお、上記積層構造を4つ以上有し、且つ、酸化狭窄層113を有する面発光レーザによれば、活性層の数が5つ以上のマルチ活性層の場合でも、各活性層に効率良く電流を注入でき、該活性層の発光効率の低下を抑制できる。
面発光レーザ100-6は、積層体生成処理において、酸化狭窄層113に代えてもう1つの酸化狭窄層106が形成される点及び積層工数が増える点を除いて、変形例3の面発光レーザ100-4(図20参照)の製造方法と同様の製造方法により製造できる。なお、同様の製法により、上記積層構造を4つ以上有する面発光レーザを製造することができる。
以下、本技術の第2実施形態に係る面発光レーザ200について説明する。
(1)面発光レーザの構成
第2実施形態に係る面発光レーザ200は、図23に示すように、第2活性層104-2上に第2トンネルジャンクション108-2及び第3活性層104-3がこの順に積層されている点を除いて、第1実施形態の面発光レーザ100(図1参照)と同様の構成を有する。すなわち、面発光レーザ200は、第2活性層104-2上にトンネルジャンクションと活性層のペアを1つ有する。
別の観点からすると、面発光レーザ200は、第2活性層104-2と第2トンネルジャンクション108-2との間に酸化狭窄層が配置されていない点が変形例2の面発光レーザ100-3(図19参照)と異なる。
図23に示す面発光レーザ200では、アノード電極116とカソード電極117との間に電圧が印加されアノード電極116からメサM2を含む共振器構造体に電流が流入されると、該電流が酸化狭窄層113で狭窄されて第3活性層104-3に注入され、第2トンネルジャンクション108-2によるトンネル効果によりその注入された電流と略同一の電流値の電流が第2活性層104-2に注入され、第1トンネルジャンクション108-1によるトンネル効果によりその注入された電流と略同一の電流値の電流が酸化狭窄層106で狭窄されて第1活性層104-1に注入される。これにより、第1~第3活性層104-1、104-2、104-3が略同一の発光強度で発光し、それらの光が第1及び第2多層膜反射鏡102、112間において各活性層で増幅されながら往復して発振条件を満たしたときに、メサM2の頂部からレーザ光として出射される。
以下、面発光レーザ200の製造方法について、図24のフローチャート(ステップS11~S17)を参照して説明する。図24は、面発光レーザ200のみならず面発光レーザ200の派生系の面発光レーザも製造可能な手順を示す。ここでは、一例として、半導体製造装置を用いた半導体製造方法により、基板101の基材である1枚のウェハ上に、複数の面発光レーザ200が2次元配置された面発光レーザアレイを複数同時に生成する。次いで、一連一体の複数の面発光レーザアレイをダイシングにより分離して、チップ状の複数の面発光レーザアレイ(面発光レーザアレイチップ)を得る。なお、以下に説明する製造方法により、基板101の基材である1枚のウェハ上に複数の面発光レーザ200を複数同時に生成し、一連一体の複数の面発光レーザ200をダイシングにより分離して、チップ状の面発光レーザ(面発光レーザチップ)を得ることも可能である。以下の一連の工程は、半導体製造装置のCPUにより実行される。
最初のステップS11では、積層体生成処理2を実施する。積層体生成処理2では、一例として、化学気層成長(CVD)法、例えば有機金属気層成長(MOCVD)法により、成長室において面発光レーザ200を構成する各層を順次積層して積層体L2(図32参照)を生成する。具体的には、面発光レーザ200を製造する場合には、以下に詳述するように、第1多層膜反射鏡102上に活性層104-1、被選択酸化層106S、第1トンネルジャンクション108-1、第2活性層104-2、第2トンネルジャンクション108-2及び第3活性層104-3が第1多層膜反射鏡102側からこの順に積層された積層構造を含む構造体を積層し、該構造体上に被選択酸化層113Sを内部に含む第2多層膜反射鏡112を積層して積層体L2(図32参照)を生成する。
ステップS11-1では、基板101上に第1多層膜反射鏡102を積層する(図4参照)。
ステップS11-2では、共振器基材生成工程2を実施する。共振器基材生成工程2は、以下に詳述するように、第1多層膜反射鏡102上に共振器を構成する各層を積層して共振器となる共振器基材を生成する工程である。
以下、共振器基材生成工程2について、図26のフローチャート、図6、図7、図27~図31(第1積層工程図~第7積層工程図)を参照して説明する。
(ステップS11-3)
ステップS11-3では、共振器上に第2多層膜反射鏡112を積層する(図32参照)。より詳細には、共振器のクラッド層111上に、被選択酸化層113Sを内部に含む第2多層膜反射鏡112及びコンタクト層114をこの順に積層する。この結果、積層体(例えば積層体L2)が生成される。ステップS11-3が実行されると、図25に示す積層体生成処理2のフローが終了する。
ステップS12では、積層体(例えば積層体L2)をエッチングしてメサ(例えばメサM1)を形成する(図33--参照)。
具体的には、例えば、成長室から取り出した積層体L2上にフォトリソグラフィによりレジストパターンを形成する。次いで、このレジストパターンをマスクとして、例えばRIEエッチング(反応性イオンエッチング)により、積層体L2(図32参照)を少なくとも被選択酸化層106Sの側面が露出するまでエッチングして、メサM2を形成する。ここでのエッチングは、一例として、第1クラッド層103の側面が完全に露出するまで(例えばエッチング底面が第1多層膜反射鏡102内に位置するまで)行う。その後、該レジストパターンを除去する。
ステップS13では、例えば、被選択酸化層106S、113S(図33参照)の周囲部を酸化して酸化狭窄層106、113を生成する(図34参照)。
具体的には、例えば、メサM2を水蒸気雰囲気中にさらし、被選択酸化層106S、113Sを側面から酸化(選択酸化)して、非酸化領域106aの周りが酸化領域106bで取り囲まれた酸化狭窄層106を形成するとともに、被酸化領域113aの周りが酸化領域113bで取り囲まれた酸化狭窄層113を形成する。
ステップS14では、絶縁膜115を形成する(図35参照)。具体的には、例えば、メサM2が形成された積層体の略全域に絶縁膜115を成膜する。
ステップS15では、コンタクトホール115aを形成する(図36参照)。具体的には、例えば、メサM2の頂部上に形成された絶縁膜115以外の絶縁膜115上にフォトリソグラフィによりレジストパターンを形成する。次いで、このレジストパターンをマスクとして、メサM2の頂部上に形成された絶縁膜115を例えばフッ酸系のエッチャントを用いてエッチングにより除去する。その後、該レジストパターンを除去する。この結果、コンタクトホール115aが形成され、コンタクト層114が露出する。
ステップS16では、アノード電極116を形成する(図37参照)。具体的には、例えば、EB蒸着法により、コンタクトホール115aを介してコンタクト層114上に例えばTi/Pt/Au膜を成膜し、レジスト及びレジスト上の例えばTi/Pt/Auをリフトオフすることにより、コンタクトホール115a内に環状のアノード電極116を形成する。
ステップS17では、カソード電極117を形成する(図38参照)。具体的には、基板101の裏面(下面)を研磨した後、該裏面に例えばAuGe/Ni/Au膜を成膜する。ステップS17が実行されると、図24のフローは終了する。
第2実施形態の面発光レーザ200は、例えば活性層が3つのマルチ活性層を有し共振器長が長い場合でも、酸化狭窄層106により、共振器内の電流経路の下流端近傍に位置する活性層(例えば出射面ESから最も遠い活性層)である第1活性層104-1に効率良く電流を注入することができる。
以下、本技術の第2実施形態の変形例1~4に係る面発光レーザについて説明する。
変形例1の面発光レーザ200-1は、図39に示すように、第2活性層104-2上にトンネルジャンクションと活性層のペアを2つ有している点を除いて、第2実施形態の面発光レーザ200(図23)と同様の構成を有する。
面発光レーザ200-1は、面発光レーザ200の共振器において第3活性層104-3上に第3トンネルジャンクション108-3及び第4活性層104-4がこの順に積層された構成を有している。
詳述すると、面発光レーザ200-1では、第3活性層104-3上にスペーサ層109を介して第3トンネルジャンクション108-3が積層され、該第3トンネルジャンクション108-3上にスペーサ層109を介して第4活性層104-4が積層されている。
変形例1の面発光レーザ200-1は、例えば活性層が4つのマルチ活性層を有し共振器長が長い場合でも、酸化狭窄層106により、共振器内の電流経路の下流端近傍に位置する活性層(例えば出射面ESから最も遠い活性層)である第1活性層104-1にも効率良く電流を注入することができる。
面発光レーザ200-1は、面発光レーザ200の派生系であり、図26のフローチャートの手順で(但し、N=1、M=2とする)で製造することができる。
変形例2の面発光レーザ200-2は、図40に示すように、第1活性層104-1と第1トンネルジャンクション108-1との間に第1酸化狭窄層106-1が設けられ、且つ、第2活性層104-2と第2トンネルジャンクション108-2との間に第2酸化狭窄層106-2が設けられている点を除いて、変形例1の面発光レーザ200-1(図39参照)と同様の構成を有する。
変形例2の面発光レーザ200-2は、例えば活性層が4つのマルチ活性層を有し共振器長が長い場合でも、第1及び第2酸化狭窄層106-1、106-2により共振器内の電流経路の下流端近傍に位置する活性層(例えば出射面ESから最も遠い活性層)である第1活性層104-1にも効率良く電流を注入することができ、且つ、第2酸化狭窄層106-2により第2活性層104-2にも効率良く電流を注入することができる。例えば共振器長が長い面発光レーザ200-2のように、共振器の上下方向(高さ方向)の中間部付近に酸化狭窄層が設けられることは、該中間部付近での電流の広がりを抑えることができる点で有効である。
面発光レーザ200-2は、面発光レーザ200の派生系であり、図26のフローチャートの手順で(但し、N=2、M=1とする)で製造することができる。
変形例3の面発光レーザ200-3は、図41に示すように、第1活性層104-1と第1トンネルジャンクション108-1との間に第1酸化狭窄層106-1が設けられ、且つ、第2トンネルジャンクション108-1と第3活性層104-3との間に第2酸化狭窄層106-2が設けられている点を除いて、変形例1の面発光レーザ200-1(図39参照)と同様の構成を有する。
変形例3の面発光レーザ200-3は、例えば活性層が4つのマルチ活性層を有し共振器長が長い場合でも、第1及び第2酸化狭窄層106-1、106-2により共振器内の電流経路の下流端近傍に位置する活性層(例えば出射面ESから最も遠い活性層)である第1活性層104-1にも効率良く電流を注入することができ、且つ、第2酸化狭窄層106-2により第2活性層104-2にも効率良く電流を注入することができる。例えば共振器長が長い面発光レーザ200-3のように、共振器の上下方向(高さ方向)の中間部付近に酸化狭窄層が設けられることは、該中間部付近での電流の広がりを抑えることができる点で有効である。
面発光レーザ200-3は、第2酸化狭窄層106-2を設ける必要があるため、その分積層工数は増えるが、変形例1の面発光レーザ200-1(図39参照)の製法に準じた製法により製造することができる。
変形例4の面発光レーザ200-4は、図42に示すように、第1活性層104-1と第1トンネルジャンクション108-1との間に第1酸化狭窄層106-1が設けられ、且つ、第2トンネルジャンクション108-1と第3活性層104-3との間に第2酸化狭窄層106-2が設けられている点を除いて、第2実施形態の面発光レーザ200(図23参照)と同様の構成を有する。
変形例4の面発光レーザ200-4は、例えば活性層が3つのマルチ活性層を有する場合でも、第1及び第2酸化狭窄層106-1、106-2により共振器内の電流経路の下流端近傍に位置する活性層(例えば出射面ESから最も遠い活性層)である第1活性層104-1にも効率良く電流を注入することができ、且つ、第2酸化狭窄層106-2により第2活性層104-2にも効率良く電流を注入することができる。
面発光レーザ200-4は、第2酸化狭窄層106-2を設ける必要があるため、その分積層工数は増えるが、第2実施形態の面発光レーザ200の製法に準じた製法により製造することができる。
図43は、本技術を適用し得る面発光レーザの構成例である面発光レーザ2000を示す平面図である。図44Aは、図43のX-X線断面図である。図44Bは、図43のY-Y線断面図である。
(工程1)基板2001の表面に第1多層反射鏡2011、活性層2013、酸化狭窄層2006となる被選択酸化層、及び第2多層反射鏡2012をエピタキシャル成長させる。
(工程2)例えばリフトオフ法を用いて、第1電極2003を第2多層反射鏡2012上に形成する。
(工程3)例えばフォトリソグラフィによりトレンチ2005を形成する。
(工程4)被選択酸化層の側面を露出させ、該被選択酸化層を側面から選択酸化することにより酸化狭窄層2006を形成する。
(工程5)保護領域2002をイオン注入などによって形成する。
(工程6)誘電体層2007を例えば蒸着、スパッタ等により成膜する。
(工程7)例えばフォトリソグラフィにより誘電体層2007に誘電体開口2008を形成して第1電極2003の接点を露出させる。
(工程8)基板2001の裏面を研磨して薄膜化した後、第2電極2004を基板2001の裏面に形成する。
本技術は、上記各実施形態及び各変形例に限定されることなく、種々の変形が可能である。
例えば、第1多層膜反射鏡102が半導体多層膜反射鏡であり、且つ、第2多層膜反射鏡112が誘電体多層膜反射鏡であってもよい。誘電体多層膜反射鏡も、分布ブラッグ反射鏡の一種である。
例えば、第1多層膜反射鏡102が誘電体多層膜反射鏡であり、且つ、第2多層膜反射鏡112が半導体多層膜反射鏡であってもよい。
例えば、第1及び第2多層膜反射鏡102、112のいずれも誘電体多層膜反射鏡であってもよい。
半導体多層膜反射鏡は、光吸収が少なく、且つ、導電性を有する。この観点からは、半導体多層膜反射鏡は、出射側(表面側)にあり、且つ、アノード電極116から各活性層までの電流経路上にある第2多層膜反射鏡112に好適である。
一方、誘電体多層膜反射鏡は、光吸収が極めて少ない。この観点からは、誘電体多層膜反射鏡は、出射側(表面側)にある第2多層膜反射鏡112に好適である。
この場合には、基板として発振波長に対して透明なものを用いるか、基板に出射口となる開口部を設けることが好ましい。
具体的には、第1及び第2多層膜反射鏡102、112の少なくとも一方にGaN系半導体多層膜反射鏡を用いてもよいし、第1及び第2多層膜反射鏡102、112の少なくとも一方にGaN系誘電体多層膜反射鏡を用いてもよい。
第1及び第2多層膜反射鏡102、112の少なくとも一方に用いられるGaN系化合物半導体としては、例えばGaN/AlGaN等が挙げられる。
本開示に係る技術(本技術)は、様々な製品(電子機器)へ応用することができる。例えば、本開示に係る技術は、自動車、電気自動車、ハイブリッド電気自動車、自動二輪車、自転車、パーソナルモビリティ、飛行機、ドローン、船舶、ロボット等のいずれかの種類の移動体に搭載される装置として実現されてもよい。
以下に、上記各実施形態及び各変形例に係る面発光レーザの適用例について説明する。
9.<距離測定装置を移動体に搭載した例>
(1)第1及び第2多層膜反射鏡と、
前記第1及び第2多層膜反射鏡の間に互いに積層された複数の活性層と、
前記複数の活性層のうち積層方向に隣り合う2つの活性層の間に配置されたトンネルジャンクションと、
前記隣り合う2つの活性層の一方の活性層と前記トンネルジャンクションとの間に配置された酸化狭窄層と、
を備える、面発光レーザ。
(2)前記一方の活性層は、前記隣り合う2つの活性層の他方の活性層よりも前記面発光レーザの出射面から遠い位置に配置されている、(1)に記載の面発光レーザ。
(3)前記一方の活性層は、前記第1及び第2多層膜反射鏡のうち前記面発光レーザの出射面から近い一方よりも前記出射面から遠い他方に近い位置に配置されている、(1)又は(2)に記載の面発光レーザ。
(4)前記一方の活性層は、前記第1及び第2多層膜反射鏡のうち前記面発光レーザの出射面から遠い一方よりも前記出射面から近い他方に近い位置に配置されている、(1)又は(2)に記載の面発光レーザ。
(5)前記一方の活性層は、前記隣り合う2つの活性層の他方の活性層よりも前記面発光レーザの出射面から近い位置に配置されている、(1)に記載の面発光レーザ。
(6)前記一方の活性層は、前記第1及び第2多層膜反射鏡のうち前記面発光レーザの出射面から近い一方よりも前記出射面から遠い他方に近い位置に配置されている、(1)又は(5)に記載の面発光レーザ。
(7)前記一方の活性層は、前記第1及び第2多層膜反射鏡のうち前記出射面から遠い一方よりも前記出射面から近い他方に近い位置に配置されている、(1)又は(5)に記載の面発光レーザ。
(8)前記複数の活性層は、少なくとも3つの活性層であり、
前記複数の活性層のうち少なくとも2組の隣り合う2つの活性層の各組の隣り合う2つの活性層の間に前記トンネルジャンクションが配置され、
前記少なくとも2組の隣り合う2つの活性層のうち少なくとも1組の隣り合う2つの活性層の一方の活性層と、該隣り合う2つの活性層の間に配置された前記トンネルジャンクションとの間に前記酸化狭窄層が配置されている、(1)~(7)のいずれか1つに記載の面発光レーザ。
(9)前記少なくとも3つの活性層は、第1、第2及び第3活性層を含み、前記第1、第2及び第3活性層は、この順に積層され、前記第1及び第2活性層の間に前記トンネルジャンクションである第1トンネルジャンクションが配置され、前記第2及び第3活性層の間に前記トンネルジャンクションである第2トンネルジャンクションが配置され、前記第1活性層と前記第1トンネルジャンクションとの間及び/又は前記第2活性層と前記第2トンネルジャンクションとの間に前記酸化狭窄層が配置されている、(8)に記載の面発光レーザ。
(10)前記第1活性層は、前記複数の活性層の中で前記面発光レーザの出射面から最も遠い位置に配置された活性層である、(9)に記載の面発光レーザ。
(11)前記第1活性層と前記第1トンネルジャンクションとの間に前記酸化狭窄層である第1酸化狭窄層が配置されている、(9)又は(10)に記載の面発光レーザ。
(12)前記第2活性層と前記第2トンネルジャンクションとの間に前記酸化狭窄層である第2酸化狭窄層が配置されている、(9)~(11)のいずれか1つに記載の面発光レーザ。
(13)前記第2活性層と前記第2トンネルジャンクションとの間に前記酸化狭窄層が配置されていない、(9)~(11)に記載の面発光レーザ。
(14)前記第1及び第2多層膜反射鏡のうち前記面発光レーザの出射面に近い方の内部に別の酸化狭窄層が配置されている、(1)~(13)のいずれか1つに記載の面発光レーザ。
(15)前記酸化狭窄層及び前記別の酸化狭窄層は、いずれもAlGaAs系化合物半導体からなる層を選択酸化して形成されている、(14)に記載の面発光レーザ。
(16)前記酸化狭窄層及び前記別の酸化狭窄層は、Al組成及び/又は光学厚さが互いに異なる、(14)又は(15)に記載の面発光レーザ。
(17)前記トンネルジャンクションは、p型半導体層及びn型半導体層が互いに積層された層構造を有し、前記酸化狭窄層は、前記p型半導体層側に配置されている、(1)~(16)のいずれか1つに記載の面発光レーザ。
(18)前記面発光レーザの発振波長をλとすると、前記一方の活性層と前記トンネルジャンクションと前記酸化狭窄層とが光学厚さ3λ/4内に配置されている、(1)~(17)のいずれか1つに記載の面発光レーザ。
(19)(1)~(18)のいずれか1つに記載の面発光レーザを備える電子機器。
(20)第1多層膜反射鏡上に第1活性層、被選択酸化層、トンネルジャンクション及び第2活性層がこの順に積層された積層構造を含む構造体を積層し、該構造体上に第2多層膜反射鏡を積層して積層体を生成する工程と、
前記積層体を少なくとも前記被選択酸化層の側面が露出するまでエッチングしてメサを形成する工程と、
前記被選択酸化層を側面側から選択的に酸化して酸化狭窄層を形成する工程と、
を含む、面発光レーザの製造方法。
(21)(1)~(20)のいずれか1つに記載の面発光レーザを複数備える面発光レーザアレイ。
(22)(1)~(20)のいずれか1つに記載の面発光レーザを備える電子機器。
(23)(21)に記載の面発光レーザアレイを備える電子機器。
Claims (20)
- 第1及び第2多層膜反射鏡と、
前記第1及び第2多層膜反射鏡の間に互いに積層された複数の活性層と、
前記複数の活性層のうち積層方向に隣り合う2つの活性層の間に配置されたトンネルジャンクションと、
前記隣り合う2つの活性層の一方の活性層と前記トンネルジャンクションとの間に配置された酸化狭窄層と、
を備える、面発光レーザ。 - 前記一方の活性層は、前記隣り合う2つの活性層の他方の活性層よりも前記面発光レーザの出射面から遠い位置に配置されている、請求項1に記載の面発光レーザ。
- 前記一方の活性層は、前記第1及び第2多層膜反射鏡のうち前記出射面から近い一方よりも前記出射面から遠い他方に近い位置に配置されている、請求項2に記載の面発光レーザ。
- 前記一方の活性層は、前記第1及び第2多層膜反射鏡のうち前記出射面から遠い一方よりも前記出射面から近い他方に近い位置に配置されている、請求項2に記載の面発光レーザ。
- 前記一方の活性層は、前記隣り合う2つの活性層の他方の活性層よりも前記面発光レーザの出射面から近い位置に配置されている、請求項1に記載の面発光レーザ。
- 前記一方の活性層は、前記第1及び第2多層膜反射鏡のうち前記出射面から近い一方よりも前記出射面から遠い他方に近い位置に配置されている、請求項5に記載の面発光レーザ。
- 前記一方の活性層は、前記第1及び第2多層膜反射鏡のうち前記出射面から遠い一方よりも前記出射面から近い他方に近い位置に配置されている、請求項5に記載の面発光レーザ。
- 前記複数の活性層は、少なくとも3つの活性層であり、
前記複数の活性層のうち少なくとも2組の隣り合う2つの活性層の各組の隣り合う2つの活性層の間に前記トンネルジャンクションが配置され、
前記少なくとも2組の隣り合う2つの活性層のうち少なくとも1組の隣り合う2つの活性層の一方の活性層と、該隣り合う2つの活性層の間に配置された前記トンネルジャンクションとの間に前記酸化狭窄層が配置されている、請求項1に記載の面発光レーザ。 - 前記少なくとも3つの活性層は、第1、第2及び第3活性層を含み、
前記第1、第2及び第3活性層は、この順に積層され、
前記第1及び第2活性層の間に前記トンネルジャンクションである第1トンネルジャンクションが配置され、
前記第2及び第3活性層の間に前記トンネルジャンクションである第2トンネルジャンクションが配置され、
前記第1活性層と前記第1トンネルジャンクションとの間及び/又は前記第2活性層と前記第2トンネルジャンクションとの間に前記酸化狭窄層が配置されている、請求項8に記載の面発光レーザ。 - 前記第1活性層は、前記複数の活性層の中で前記面発光レーザの出射面から最も遠い位置に配置された活性層である、請求項9に記載の面発光レーザ。
- 前記第1活性層と前記第1トンネルジャンクションとの間に前記酸化狭窄層である第1酸化狭窄層が配置されている、請求項10に記載の面発光レーザ。
- 前記第2活性層と前記第2トンネルジャンクションとの間に前記酸化狭窄層である第2酸化狭窄層が配置されている、請求項11に記載の面発光レーザ。
- 前記第2活性層と前記第2トンネルジャンクションとの間に前記酸化狭窄層が配置されていない、請求項11に記載の面発光レーザ。
- 前記第1及び第2多層膜反射鏡のうち前記面発光レーザの出射面に近い方の内部に別の酸化狭窄層が配置されている、請求項1に記載の面発光レーザ。
- 前記酸化狭窄層及び前記別の酸化狭窄層は、いずれもAlGaAs系化合物半導体からなる層を選択酸化して形成されている、請求項14に記載の面発光レーザ。
- 前記酸化狭窄層及び前記別の酸化狭窄層は、Al組成及び/又は光学厚さが互いに異なる、請求項15に記載の面発光レーザ。
- 前記トンネルジャンクションは、p型半導体層及びn型半導体層が互いに積層された層構造を有し、
前記酸化狭窄層は、前記p型半導体層側に配置されている、請求項1に記載の面発光レーザ。 - 前記面発光レーザの発振波長をλとすると、
前記一方の活性層と前記トンネルジャンクションと前記酸化狭窄層とが光学厚さ3λ/4内に配置されている、請求項1に記載の面発光レーザ。 - 請求項1に記載の面発光レーザを備える電子機器。
- 第1多層膜反射鏡上に第1活性層、被選択酸化層、トンネルジャンクション及び第2活性層がこの順に積層された積層構造を含む構造体を積層し、該構造体上に少なくとも第2多層膜反射鏡を積層して積層体を生成する工程と、
前記積層体を少なくとも前記被選択酸化層の側面が露出するまでエッチングしてメサを形成する工程と、
前記被選択酸化層を側面側から選択的に酸化して酸化狭窄層を形成する工程と、
を含む、面発光レーザの製造方法。
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JP2013175712A (ja) * | 2012-01-24 | 2013-09-05 | Fuji Xerox Co Ltd | 面発光型半導体レーザ、面発光型半導体レーザ装置、光伝送装置および情報処理装置 |
JP2019016628A (ja) * | 2017-07-03 | 2019-01-31 | 富士ゼロックス株式会社 | 光半導体素子 |
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JP2024056929A (ja) | 2024-04-23 |
US20240055833A1 (en) | 2024-02-15 |
CN116762246A (zh) | 2023-09-15 |
JP2024056925A (ja) | 2024-04-23 |
JPWO2022158301A1 (ja) | 2022-07-28 |
DE112022000703T5 (de) | 2023-11-16 |
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