Light-emitting device

Abstract

To provide an advantageous technology for driving a light emitting apparatus including a plurality of light emitting units, in which a plurality of light emitting elements are arranged, to emit light.SOLUTION: A light emitting apparatus includes a first light emitting unit and a second light emitting unit; and first drive wiring configured to drive the first light emitting unit and second drive wiring configured to drive the second light emitting unit. A plurality of light emitting elements having mesa structure of a compound semiconductor is arranged in the first light emitting unit and the second light emitting unit. The first drive wiring is in electrical contact with an upper surface of the mesa structure of the compound semiconductor in the first light emitting unit, and the second drive wiring is in electrical contact with an upper surface of the mesa structure of the compound semiconductor in the second light emitting unit. The first drive wiring extends above the upper surface of the mesa structure of the compound semiconductor in the second light emitting unit. An insulating film is arranged between the upper surface of the mesa structure of the compound semiconductor in the second light emitting unit and the first drive wiring to electrically insulate therebetween.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a light emitting device. [Background technology]

[0002] There are light-emitting devices, particularly VCSEL array elements, which are surface-emitting lasers (VCSELs: Vertical Cavity Surface Emitting Lasers) arranged two-dimensionally. VCSEL array elements are being developed as light sources for LiDAR (Light Detection and Ranging) and 3D (Dimension) sensors. In particular, there is a demand for higher output from VCSEL array elements to improve ranging performance (sensitivity, resolution, extended ranging range, etc.). There is also a demand for smaller elements. To achieve this, it is effective to arrange VCSELs with a wide light-emitting diameter at high density (narrow pitch).

[0003] One example of using a VCSEL array element as a LiDAR light source is the flash method, in which VCSEL elements are arranged two-dimensionally and all VCSELs constituting the array are simultaneously illuminated to measure distances over a wide area. Another example is the sequential flash method, in which the array is divided into multiple light-emitting elements, each with multiple light-emitting elements, and the multiple light-emitting elements are illuminated in sequence. For example, a VCSEL array element used as a sequential flash light source is divided into 10 light-emitting elements, each with multiple light-emitting elements. If the optical power density of one light-emitting element can be made equal to the optical power density of the entire VCSEL array element, distance measurement performance can be improved. Patent Document 1 describes reducing the size of a light-emitting device by arranging electrodes on the short sides of the substrate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-165805 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to individually illuminate each light-emitting section containing multiple light-emitting elements, drive wiring is required to make each light-emitting section emit light. However, the space available in the light-emitting section for laying the drive wiring is limited. Also, a high current injection value is required to make a light-emitting section containing multiple light-emitting elements emit light. However, to avoid disconnections due to electromigration in the drive wiring, it is necessary to widen the wiring width as much as possible and increase the critical current density.

[0006] An object of the present invention is to provide a technique that is advantageous for driving a light emitting device having a plurality of light emitting sections, each of which has a plurality of light emitting elements arranged therein, to emit light. [Means for solving the problem]

[0007] In view of the above problems, a light emitting device according to one aspect of the present invention is a light emitting device provided with a first light emitting section and a second light emitting section, a first drive wiring for driving the first light emitting section, and a second drive wiring for driving the second light emitting section, wherein a plurality of light emitting elements each having a compound semiconductor mesa structure are arranged in the first light emitting section and the second light emitting section, the first drive wiring is in electrical contact with an upper surface of the compound semiconductor mesa structure of the first light emitting section, the second drive wiring is in electrical contact with an upper surface of the compound semiconductor mesa structure of the second light emitting section, the first drive wiring extends above the upper surface of the compound semiconductor mesa structure of the second light emitting section, and an insulating film is arranged between the upper surface of the compound semiconductor mesa structure of the second light emitting section and the first drive wiring for electrical insulation. the first light-emitting portion includes a plurality of light-emitting openings surrounded by the first drive wiring. It is characterized by: [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a technique that is advantageous for driving a light emitting device having a plurality of light emitting sections, each of which has a plurality of light emitting elements arranged therein, to emit light. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a plan view illustrating the configuration of a light emitting device according to a first embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along the line AA' illustrating the configuration of the light-emitting device according to the first embodiment. [Figure 3] FIG. 2 is a schematic cross-sectional view taken along the line BB′ for explaining the configuration of the light emitting device according to the first embodiment. [Figure 4] 1A to 1C are plan views illustrating a method for manufacturing the light emitting device according to the first embodiment. [Figure 5] FIG. 6 is a cross-sectional view illustrating the configuration of a light-emitting device according to a second embodiment. [Figure 6] FIG. 6 is a plan view illustrating the configuration of a light emitting device according to a second embodiment. [Figure 7] FIG. 10 is a plan view illustrating the configuration of a light emitting device according to a third embodiment. [Figure 8] FIG. 2 is a schematic cross-sectional view taken along the line AA' illustrating the configuration of a light-emitting device according to a third embodiment. [Figure 9] FIG. 10 is a plan view illustrating the configuration of a light emitting device according to a third embodiment. [Figure 10] FIG. 10 is a plan view illustrating the configuration of a light emitting device according to a third embodiment. [Figure 11] FIG. 10 is a plan view illustrating the configuration of a light emitting device according to a fourth embodiment. [Figure 12] FIG. 10 is a plan view illustrating the configuration of a light emitting device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0011] Furthermore, the drawings are merely for the purpose of explaining the structure or configuration, and the dimensions of the illustrated components do not necessarily reflect the actual dimensions.

[0012] In the following embodiments, a vertical cavity surface emitting laser (VCSEL) array element having a plurality of VCSEL elements will be described as an example of a light emitting device to which the present invention can be applied. The present invention can also be applied to a light emitting device having a plurality of light emitting sections in which a plurality of light emitting elements having a mesa structure, such as light emitting diodes (LEDs), are arranged. Hereinafter, embodiments of the technology disclosed herein will be described.

[0013] (Embodiment 1) 1(a) and 1(b) are planar schematic diagrams illustrating the configuration of a light-emitting device 1 according to this embodiment. FIG. 1(a) is a planar schematic diagram of the entire light-emitting device 1, in which VCSEL elements are arranged in an array as light-emitting elements, as viewed from the light-emitting side. The light-emitting device 1 includes a VCSEL element section 10 in which the VCSEL elements are arranged and a terminal pad section 20 in which terminal pads are arranged. In this light-emitting device, multiple VCSEL elements, each with a square compound semiconductor mesa structure, are arranged two-dimensionally at regular intervals. As shown by the lines separating the VCSEL elements in FIG. 1(a), multiple VCSEL elements arranged in a row constitute one light-emitting section. The light-emitting device 1 is vertically divided into 32 light-emitting sections, with the direction from the terminal pad section 20 to the VCSEL element section 10 in FIG. 1(a) being the vertical columns. In the light-emitting sections, the VCSEL elements are arranged in a vertical column direction (first direction).

[0014] FIG. 1(b) is a plan view showing an enlarged schematic view of a portion of the VCSEL element section 10. The VCSEL element section 10 is divided into multiple light-emitting sections as indicated by the dashed lines. In this embodiment, the VCSEL elements are arranged in a row surrounded by the dashed lines, and the VCSEL elements arranged in each light-emitting section can be simultaneously driven by drive wiring to control light emission. The mesa structure of the VCSEL element is the area indicated by the dashed lines. This area corresponds to one VCSEL element. In this embodiment, a light-emitting device will be described as an example, in which 960 VCSEL elements are two-dimensionally arranged at a 30 μm pitch in a 32 × 30 matrix of 32 columns and 30 rows.

[0015] The structures of the first light-emitting section 100 and the second light-emitting section 102 will be described with reference to FIG. 1(b). The location from which light is emitted in the first light-emitting section 100 is a light exit port 118. The light exit port 118 is covered with an insulating film that transmits light. Similarly, a light exit port 118 is also provided in the second light-emitting section 102. A first drive wiring 114 is arranged to supply current to the first light-emitting section 100. The first drive wiring 114 is wiring for driving the first light-emitting section 100. Similarly, the second drive wiring 116 is wiring for driving the second light-emitting section 102.

[0016] FIG. 1( b ) shows an example in which an opening 119 for electrical contact between the first drive wiring and the top surface of the mesa-structured semiconductor layer 108 is provided around the light-emitting opening 118 located at the intersection of line A-A′ and line B-B′. Here, the top surface of the mesa-structured semiconductor layer 108 is the surface of the mesa-structured semiconductor layer 108 from which light from the first and second light-emitting units 100 and 102 is emitted. The openings 119 are provided on three sides around the light-emitting opening 118. The openings 119 are located below the first drive wiring and are not exposed. Similar openings are also provided around the other light-emitting openings 118, but are not shown. As shown in FIG. 2 , a first insulating film 115 is disposed between the first drive wiring 114 of the first light-emitting unit and the top surface of the mesa-structured semiconductor layer 108 of the second light-emitting unit 102, opposite the side where the common electrode 104 of the compound semiconductor substrate 106 is located. The first insulating film 115 electrically insulates the drive wiring 114 that supplies current to the first light-emitting unit 100 from the second light-emitting unit 102. In this way, the first light-emitting unit 100 and the second light-emitting unit 102 are electrically insulated by the second insulating film 115. Here, for convenience, the two light-emitting units are referred to as the first light-emitting unit 100 and the second light-emitting unit 102. Other light-emitting units that are arranged side by side in a direction intersecting the first direction with the first light-emitting unit 100 and the second light-emitting unit 102 are also similarly provided with light outlets, drive wiring, insulating films, etc., but their description will be omitted here.

[0017] FIG. 2 is a schematic diagram showing the cross section A-A' in FIG. 1. Here, we will explain the first light-emitting section 100 and the second light-emitting section 102, which are arranged side by side among the 32 rows of light-emitting sections. A mesa-structured VCSEL element is arranged in the first light-emitting section 100 and the second light-emitting section 102. A common electrode 104 for supplying current commonly to the multiple light-emitting sections is provided on the compound semiconductor substrate 106, opposite the side on which the first and second drive wirings 114 and 116 are arranged. A mesa-structured semiconductor layer 108 that forms the VCSEL element is formed on the compound semiconductor substrate 106. An oxide confinement structure 110 is provided on the semiconductor layer 108. The area surrounded by the oxide confinement structure 110 corresponds to the light-emitting region that emits light.

[0018] The first insulating film 112 functions as a light exit port for emitting light emitted from the light-emitting region. To function well as a light exit port, the insulating film should have a thickness of λ / 2n (λ: oscillation wavelength, n: refractive index of the insulating film). The first drive wiring 114 is in electrical contact with the upper surface of the mesa-structured semiconductor layer 108 at the opening 119. The first drive wiring 114 can be disposed so as to extend above the upper surface of the mesa structure of the second light-emitting section 102. However, the second insulating film 115 is present between the first drive wiring 114 and the upper surface of the mesa-structured semiconductor layer 108 of the second light-emitting section 102, and the upper surface of the mesa structure of the second light-emitting section 102 and the first drive wiring 114 are electrically insulated by the second insulating film 115. This configuration allows the first drive wiring 114 to be disposed so as to extend across the VCSEL elements of the mesa structure, thereby increasing the cross-sectional area of ​​the drive wiring.

[0019] Furthermore, because opening 119 is disposed around first insulating film 112 of light exit port 118, first drive wiring is in electrical contact with the top surface of the mesa structure around light exit port 118. For example, in the case of a light-emitting device in which VCSEL elements with a mesa structure having a side length of 20 μm and a light-emitting region having a side length of 6 μm are arranged two-dimensionally, carriers injected from first drive wiring 114 spread throughout the entire light-emitting region having a side length of 6 μm. This allows light to be emitted throughout the entire light-emitting region. In this case, as shown in FIG. 2, the tip of first drive wiring 114 (toward the mesa center) is preferably positioned to overlap the tip of oxidation confinement structure 110 (toward the mesa center) in a planar view so as not to block the light emitted from the light-emitting region. Furthermore, the tip of oxidation confinement structure 110 may be approximately 0 to 2 μm longer toward the mesa center than the tip of first drive wiring 114.

[0020] Figure 3 is a diagram schematically showing the BB' cross section in Figure 1. It is a diagram schematically showing a cross section in the direction in which multiple VCSEL elements of the first light-emitting unit 100 in Figure 2 are arranged in a vertical row. The opening 119 formed in the first insulating film 112 shown in Figure 1 is also shown in Figures 2 and 3. The first drive wiring 114 of the first light-emitting unit 100 is in electrical contact with the upper surface of the mesa-structured semiconductor layer 108 via the opening 119 formed in the first insulating film 112, allowing carrier injection.

[0021] Next, a manufacturing method for the light-emitting device of this embodiment will be described using a VCSEL element emitting light in the 940 nm band as an example. First, an n-type GaAs substrate is prepared as a compound semiconductor substrate. A resonator layer including an n-type GaAs / AlGaAs DBR (Distributed Bragg Reflector) and an MQW (Multi Quantum Well) is formed on the n-type GaAs substrate. Next, a selective oxidation layer p-Al0.98GaAs and a p-type GaAs / AlGaAs DBR are formed. The semiconductor layers are preferably formed by epitaxial growth in the order of the resonator layer and the selective oxidation layer. Next, a mesa structure is formed using photolithography and etching techniques.

[0022] Next, the selective oxidation layer p-Al0.98GaAs is selectively oxidized using water vapor from the mesa sidewall, forming an oxidation confinement structure 110. Next, a first insulating film 112 is formed to cover the mesa structure. Next, an opening 119 is formed in the first insulating film 112 using photolithography and etching techniques. Next, resist is placed in areas where metal should not be placed, metal is evaporated, and the first drive wiring 114 and second drive wiring 116 are formed using lift-off technology to remove the resist. Next, the n-GaAs substrate is polished, and then a common electrode 104 is formed on the back surface of the substrate.

[0023] 4, a light-emitting device will be described in which VCSEL elements are arranged in an array so that the vertical row of the VCSEL elements in the light-emitting section is 300 μm or more and the closest distance between the first drive wiring 114 and the second drive wiring 116 is 10 μm or less. The first drive wiring 114 and the second drive wiring 116 are formed using photolithography, vacuum deposition, and lift-off techniques. In this process, the lift-off resist patterns (412 and 418) formed using photolithography should be formed to have the pattern shape shown in FIG. 4(a). That is, the planar pattern of the lift-off resist is an integrated pattern in which the lift-off resist pattern 418 for forming the light exit aperture 118 and the lift-off resist pattern 412 for separating adjacent drive wirings are connected. This allows the lift-off resist pattern shape to be stably maintained even during the deposition process. By integrating the lift-off resist patterns 412 and 418, the desired exit aperture shape can be stably formed.

[0024] On the other hand, as shown in FIG. 4(b), a planar pattern with a large aspect ratio (10 μm or less in width and 300 μm or more in height) is formed with a resist film thickness of 1 μm or more to separate adjacent drive wirings. The cross-sectional structure of the lift-off resist patterns 412 and 418 in FIG. 4(b) is shown in FIG. 4(c). In this example, the lift-off resist patterns 412 and 418 are not connected. In this case, the heat and stress applied to the resist during the deposition process can cause the planar pattern to fluctuate, collapse, or become disconnected. As a result, drive wiring may be formed over the light exit aperture, blocking the emitted light. On the other hand, as shown in FIG. 4(a), a pattern is formed in which the exposed first insulating film 112 that forms the light exit aperture 118 and the exposed first insulating film 112 that separates adjacent drive wirings are connected. This allows the resist pattern with a large aspect ratio for separating adjacent drive wirings to be integrated and supported by the resist pattern that forms the light exit aperture. Therefore, the drive wiring can be formed stably, so that the light emitting section can be driven and the light exit port can be prevented from being blocked.

[0025] The first insulating film 112 is made of any one of a dielectric insulating film such as silicon oxide, silicon nitride, silicon oxynitride, amorphous silicon, and aluminum oxide.

[0026] The first and second drive wirings 114 and 116 are made of gold and titanium, gold, platinum, and titanium, or gold, titanium, copper, and gold, and titanium. In particular, when a higher limit value for current density is desired, a configuration using mainly copper is preferable. To improve the optical power density of the light-emitting elements, it is preferable to densely arrange the light-emitting elements. To achieve this, the first drive wiring and the second drive wiring should be spaced apart by a distance equal to or less than one-fourth the spacing (pitch) between the light-emitting elements. While this embodiment does not describe a laminated layer that can be formed on the first insulating film 112, a reflectance adjustment layer, an anti-reflection film, or the like may also be formed. In this embodiment, each of the 32 columns of light-emitting elements has one terminal pad portion 20, but a configuration having two or more terminal pads is also possible.

[0027] (Embodiment 2) A second embodiment will be described with reference to Figures 5 and 6. In this embodiment, in order to further increase the optical power density, the mesa structure of the VCSEL element has a side length of 38 μm, and a light-emitting device is described in which VCSEL elements with a side length of 30 μm in the light-emitting region are arranged two-dimensionally. When the side length of the light-emitting region is widened to 30 μm, carriers injected into the light-emitting region tend to concentrate on the outer periphery of the light-emitting region, resulting in a ring-shaped emission pattern concentrated around the light exit. Therefore, in this embodiment, as shown in Figure 5, a transparent conductive film 120 is disposed so as to cover at least the top surface of the mesa structure. This configuration allows injected carriers to diffuse within the transparent conductive film 120, and the diffused carriers spread throughout the light-emitting region surrounded by the oxide confinement structure 110, enabling uniform light emission throughout the entire light-emitting region.

[0028] In this embodiment, too, if the light-emitting portions are formed at a high density and a narrow pitch in order to increase the optical power density, the area for laying the drive wiring is limited. A configuration will be described that allows laying drive wiring with a wider cross-sectional area in order to supply sufficient current even under such circumstances.

[0029] A plan view of this embodiment is shown in FIG. 6. FIG. 6 is a view seen from the light-emitting side. Note that the plan views used to explain other embodiments are also views seen from the light-emitting side. As shown in FIG. 6, in this embodiment, the third insulating film 122 is exposed, not the first insulating film 112 described in embodiment 1. Other than this, the details are the same as those in the plan view 1 of embodiment 1 described above, and therefore will be omitted. In the following explanation, explanations of the same configurations and processes as those in embodiment 1 will be omitted.

[0030] Fig. 5 is a cross-sectional view illustrating the configuration of a light-emitting device in which a VCSEL element according to this embodiment is disposed. As shown in Fig. 5, a transparent conductive film 120 is laminated on the upper surface of each semiconductor layer 108 of the mesa structure, and the transparent conductive film 120 and the upper surface of the semiconductor layer 108 of the mesa structure are in electrical contact with each other through openings formed in the first insulating film 112.

[0031] 5, the first drive wiring 114 is in electrical contact with the transparent conductive film 120, which is in electrical contact with the upper surface of the mesa-structured semiconductor layer 108 of the first light-emitting section 100. Meanwhile, a fourth insulating film 123 is present between the first drive wiring 114 and the transparent conductive film 120, which is in electrical contact with the upper surface of the mesa-structured semiconductor layer 108 of the second light-emitting section 102. For this reason, the first drive wiring 114 is not in electrical contact with the transparent conductive film 120, which is in electrical contact with the upper surface of the mesa-structured semiconductor layer 108. The first drive wiring 114 can be arranged to extend from the first light-emitting section 100 to the second light-emitting section 102.

[0032] By adopting such a configuration, it is possible to increase the cross-sectional area of ​​the first drive wiring 114 (the wiring width in FIG. 5). Note that, when the third and fourth insulating films 122, 123 and the conductive film 120 are formed on the light emitting aperture in order to improve light transmittance, their thicknesses should be determined taking into account the refractive index. That is, the refractive indexes of the insulating film and the conductive film should be taken into account, and the optical path length defined by the thicknesses of the insulating film and the conductive film should be an integer multiple of λ / 2 (λ: oscillation wavelength).

[0033] The manufacturing method will be described. After forming an opening in the first insulating film 112 described in the first embodiment, the transparent conductive film 120 is deposited. Next, the transparent conductive film 120 is formed at least on the mesa structure using photolithography and etching techniques, and is formed so as to be disconnected at the boundary between the first light-emitting section 100 and the second light-emitting section 102. Next, third and fourth insulating films 122 and 123 are deposited to cover the mesa structure. Next, openings are formed in parts of the third and fourth insulating films 122 and 123 using photolithography and etching techniques, exposing the transparent conductive film 120. Next, the first and second drive wirings 114 and 116 are formed using photolithography, vacuum deposition, and lift-off techniques. Next, the n-GaAs substrate, which is a compound semiconductor substrate, is polished, and then the common electrode 104 is formed on the back surface of the substrate.

[0034] The insulating film may be made of any of a dielectric insulating film such as silicon oxide, silicon nitride, silicon oxynitride, amorphous silicon, or aluminum oxide. The first and second drive wiring 114, 116 may be made of any of gold and titanium, gold, platinum, and titanium, or gold, titanium, copper, or gold, and titanium. In particular, when a high limiting current density is desired, a configuration using mainly copper is preferable. The transparent conductive film 120 may be made of any of oxide semiconductors such as indium tin oxide (ITO), indium oxide, tin oxide, zinc oxide, or indium gallium zinc oxide.

[0035] In this embodiment, no description has been given of a laminate formed on the third and fourth insulating films 122 and 123, but a reflectance adjusting layer, an anti-reflection film, etc. may be formed.

[0036] (Embodiment 3) In the third embodiment, two vertical rows of VCSEL elements are treated as one light-emitting section, and each light-emitting section is driven individually. In the following description, the same configurations and processes as those in the first and second embodiments will not be described.

[0037] 7 and 8, the first light-emitting unit 100 of the third embodiment has a plurality of light-emitting openings 717 surrounded by a ring shape by the first drive wiring 114, and a plurality of light-emitting openings 718 where a portion of the first drive wiring 114 is interrupted and the plurality of light-emitting openings 718 are connected by an insulating film. In the present embodiment, the two rows of light-emitting units included in the first light-emitting unit 100 are referred to as first light-emitting unit 100-1 and first light-emitting unit 100-2. The first light-emitting unit 100-1 and first light-emitting unit 100-2 are driven by the first drive wiring 114.

[0038] FIG. 8 shows the A-A' cross section of FIG. 7. In this embodiment, a transparent conductive film 120 is laminated on the top surface of the mesa-structured semiconductor layer 108, and the transparent conductive film 120 is in electrical contact with the top surface of the semiconductor layer 108 of the first light-emitting unit 100-1 through an opening formed in the first insulating film 112. A third insulating film 122 is laminated on the transparent conductive film 120, and the first drive wiring 114-1 is in electrical contact with the transparent conductive film 120 through an opening formed in the third insulating film 122. The first drive wiring 114-1 is also in electrical contact with the top surface of the semiconductor layer 108 of the first light-emitting unit 100-2 through the openings formed in the third insulating film 122 and the first insulating film 112. The first drive wiring 114-2 is also in electrical contact with the top surface of the mesa-structured semiconductor layer 108 of the first light-emitting unit 100-2 through the openings formed in the third insulating film 122 and the first insulating film 112.

[0039] Note that openings may be provided around the light output port as in the first embodiment to electrically connect the drive wiring to the upper surface of the semiconductor layer 108 having a mesa structure. In this case, an opening is provided around the light output port 718 connected by an insulating film, excluding a portion of the periphery of the light output port. As shown in FIG. 1(b), an opening 119 may be provided so as to surround a portion of the light output port. For a light output port 717 whose periphery is surrounded by drive wiring, an opening may be provided around the entire periphery to electrically connect the drive wiring to the upper surface of the semiconductor layer 108 having a mesa structure.

[0040] A third insulating film 122 is provided between the second drive wiring 116 and the upper surface of the semiconductor layer 108 of the first light-emitting unit 100-1, providing electrical insulation, so the first light-emitting unit 100 is not driven by the second drive wiring 116. Furthermore, the insulating film 122 is provided between the first drive wiring 114-2 and the upper surface of the semiconductor layer 108 of an adjacent light-emitting unit (not shown), so the first drive wiring 114-2 does not drive the adjacent light-emitting unit. The two columns of first light-emitting units 100-1 and 100-2 of the first light-emitting unit 100 are thus driven by the two first drive wirings 114-1 and 114-2. The two first drive wirings 114-1 and 114-2 shown in FIG. 8 are electrically connected.

[0041] FIG. 9 shows another example of wiring for individually driving two columns of vertically arranged light-emitting elements. In the example shown in FIG. 9, a transparent conductive film 120 is laminated on the upper surface of the mesa-structured semiconductor layer 108 of the first light-emitting section 100 and the upper surface of the mesa-structured semiconductor layer 108 of the second light-emitting section 102. The transparent conductive film 120 between the first light-emitting section 100 and the second light-emitting section 102 is removed, resulting in a structure in which the first light-emitting section 100 and the second light-emitting section 102 are electrically isolated. The first drive wiring 114 does not have an annular shape but surrounds the periphery of the light output port 721 and the periphery of the light output port 722 on three sides. Similar to the configuration shown in FIG. 7, the first drive wiring 114 is in electrical contact with the upper surface of the semiconductor layer 108 of the first light-emitting section 100 through an opening formed in the third insulating film 122 and an opening formed in the first insulating film 112. Note that an opening may be provided around the light outlet as in the first embodiment to electrically connect the drive wiring to the upper surface of the mesa-structured semiconductor layer 108. In this case, an opening is provided around the light outlet 718 connected by an insulating film, except for a portion of the periphery of the light outlet. An opening 119 may be provided so as to surround a portion of the light outlet, as shown in FIG. 1(b).

[0042] Comparing the configuration shown in Fig. 7 with the configuration shown in Fig. 9, in the configuration shown in Fig. 9, current is supplied to all VCSEL elements through only one wiring laid between the light-emitting elements of the mesa structure. In the configuration shown in Fig. 9, the maximum current density that can be passed through the first drive wiring 114 is lower than in the case of Fig. 7. When the configuration shown in Fig. 7 is adopted, it becomes possible to pass a larger current, and as a result, it becomes possible to increase the optical power density.

[0043] FIG. 10 shows a case where the number of columns of simultaneously driven VCSEL elements is four. When the number of columns is increased like this, the first light-emitting unit 100 may be configured to have a plurality of light-emitting apertures 717 surrounded by a ring shape by the first drive wiring 114, and a light-emitting aperture in which a portion of the first drive wiring 114 is interrupted and a plurality of light-emitting apertures 718 are connected. In this case, as in the example of FIG. 7 , the transparent conductive film 120 between the adjacent first light-emitting unit 100 and second light-emitting unit 102 is removed, resulting in an electrically isolated structure. By adopting this configuration, the first drive wiring 114 can drive the light-emitting elements arranged in four columns of the first light-emitting unit 100. Furthermore, because the drive wiring is arranged to extend across the mesa structure, the cross-sectional area of ​​the drive wiring can be increased, potentially improving the optical power density.

[0044] (Embodiment 4) Although the light-emitting elements with a mesa structure described in Embodiments 1 to 3 have a rectangular light-emitting region, the light-emitting region may also have a circular light-emitting region as shown in FIG. 11. A circular light-emitting region allows light-emitting elements with a mesa structure to be arranged more densely, as shown in FIG. 12, and is suitable for increasing the optical power density. Note that even in the circular mesa structure described in FIGS. 11 and 12, the cross-sectional area of ​​the drive wiring can be increased by adopting the configurations described in Embodiments 1 to 3 as the drive wiring structure, and the optical power density can be improved. Furthermore, although a circular mesa structure has been described in this embodiment, a polygonal mesa structure may also be used.

[0045] (Other embodiments) The disclosure of this specification includes the following light emitting devices. (Item 1) A light emitting device including a first light emitting unit, a second light emitting unit, a first drive wiring for driving the first light emitting unit, and a second drive wiring for driving the second light emitting unit, a plurality of light-emitting elements each having a compound semiconductor mesa structure are disposed in the first light-emitting section and the second light-emitting section; the first drive wiring is electrically connected to an upper surface of the compound semiconductor mesa structure of the first light-emitting unit, and the second drive wiring is in electrical contact with an upper surface of the compound semiconductor mesa structure of the second light-emitting unit; a light-emitting device characterized in that the first drive wiring extends over an upper surface of the compound semiconductor mesa structure of the second light-emitting section, and an insulating film is disposed between the upper surface of the compound semiconductor mesa structure of the second light-emitting section and the first drive wiring, thereby providing electrical insulation. (Item 2) A light emitting device including a first light emitting unit, a second light emitting unit, a first drive wiring for driving the first light emitting unit, and a second drive wiring for driving the second light emitting unit, a plurality of light-emitting elements each having a compound semiconductor mesa structure are disposed in the first light-emitting section and the second light-emitting section; a transparent conductive film is disposed on an upper surface of the compound semiconductor mesa structure that constitutes the mesa structure; the first drive wiring is in electrical contact with the transparent conductive film of the first light-emitting portion, and the second drive wiring is in electrical contact with the transparent conductive film of the second light-emitting portion; a light-emitting device characterized in that the first drive wiring extends over the transparent conductive film of the second light-emitting section, and an insulating film is disposed between the transparent conductive film of the second light-emitting section and the first drive wiring, thereby providing electrical insulation. (Item 3) 3. The light emitting device according to item 2, wherein there is a light emitting section between the first light emitting section and the second light emitting section where no transparent conductive film is disposed. (Item 4) 4. The light-emitting device according to item 2 or 3, wherein the transparent conductive film is made of ITO (indium tin oxide). (Item 5) 5. The light emitting device according to any one of items 1 to 4, wherein the first light emitting section has a plurality of light emitting openings partially surrounded by the first drive wiring. (Item 6) 6. The light emitting device according to any one of items 1 to 5, wherein the first light emitting section includes a plurality of light emitting openings surrounded by the first drive wiring. (Item 7) 7. The light emitting device according to any one of items 1 to 6, wherein the first drive wiring and the second drive wiring are insulated from each other by the insulating film. (Item 8) 8. The light emitting device according to any one of items 1 to 7, wherein the first drive wiring is arranged across the first light emitting section and the second light emitting section. (Item 9) Item 9. The light-emitting device according to any one of items 1 to 8, characterized in that the first drive wiring and the second drive wiring are spaced apart by a distance equal to or less than one-fourth of the spacing at which the plurality of light-emitting elements are respectively arranged. (Item 10) 10. The light emitting device according to item 9, wherein the distance is 10 μm or less. (Item 11) 11. The light emitting device according to any one of items 1 to 10, wherein a terminal pad is disposed on the light emitting device. (Item 12) 12. The light emitting device according to any one of items 1 to 11, wherein the plurality of light emitting elements are arranged at regular intervals. (Item 13) 13. The light emitting device according to any one of items 1 to 12, wherein the first light emitting section and the second light emitting section are arranged side by side.

[0046] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0047] 1: light emitting device, 10: VCSEL element section, 20: terminal pad section, 100: first light emitting section, 102: second light emitting section, 114: first drive wiring, 116: second drive wiring, 118: light emitting aperture

Claims

1. A light emitting device including a first light emitting unit, a second light emitting unit, a first drive wiring for driving the first light emitting unit, and a second drive wiring for driving the second light emitting unit, a plurality of light-emitting elements each having a compound semiconductor mesa structure are disposed in the first light-emitting section and the second light-emitting section; the first drive wiring is in electrical contact with an upper surface of the compound semiconductor mesa structure of the first light-emitting section, and the second drive wiring is in electrical contact with an upper surface of the compound semiconductor mesa structure of the second light-emitting section; a light-emitting device characterized in that the first drive wiring extends over an upper surface of the compound semiconductor mesa structure of the second light-emitting section, an insulating film is disposed between the upper surface of the compound semiconductor mesa structure of the second light-emitting section and the first drive wiring, thereby providing electrical insulation, and the first light-emitting section includes a plurality of light emission ports surrounded by the first drive wiring.

2. A light emitting device including a first light emitting unit, a second light emitting unit, a first drive wiring for driving the first light emitting unit, and a second drive wiring for driving the second light emitting unit, a plurality of light-emitting elements each having a compound semiconductor mesa structure are disposed in the first light-emitting section and the second light-emitting section; a transparent conductive film is disposed on an upper surface of the compound semiconductor mesa structure that constitutes the mesa structure; the first drive wiring is in electrical contact with the transparent conductive film of the first light-emitting portion, and the second drive wiring is in electrical contact with the transparent conductive film of the second light-emitting portion; a first driving wiring extending over the transparent conductive film of the second light-emitting section, an insulating film being disposed between the transparent conductive film of the second light-emitting section and the first driving wiring to provide electrical insulation, and the first light-emitting section including a plurality of light-emitting openings surrounded by the first driving wiring.

3. 3. The light emitting device according to claim 2, wherein there is a portion between the first light emitting section and the second light emitting section where no transparent conductive film is disposed.

4. 3. The light emitting device according to claim 2, wherein the transparent conductive film is made of indium tin oxide (ITO).

5. 5. The light emitting device according to claim 1, wherein the first light emitting portion has a plurality of light emitting openings partially surrounded by the first drive wiring.

6. 5. The light emitting device according to claim 1, wherein the first drive wiring and the second drive wiring are insulated from each other by the insulating film.

7. The light emitting device according to claim 1 , wherein the first drive wiring is arranged across the first light emitting section and the second light emitting section.

8. 5. The light-emitting device according to claim 1, wherein the first drive wiring and the second drive wiring are spaced apart by a distance equal to or less than one-fourth of the spacing between the plurality of light-emitting elements.

9. 9. The light emitting device according to claim 8, wherein the distance is 10 [mu]m or less.

10. 5. The light emitting device according to claim 1, wherein a terminal pad is disposed on the light emitting device.

11. 5. The light emitting device according to claim 1, wherein the plurality of light emitting elements are arranged at regular intervals.

12. 5. The light emitting device according to claim 1, wherein the first light emitting portion and the second light emitting portion are arranged side by side.

13. A light-emitting device described in any one of claims 1 to 4, characterized in that, in a planar view, the outer edge of each of the plurality of light-emitting outlets is contained within the outer edge of each of the mesa structures of the corresponding plurality of light-emitting elements.

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