JP2023107148A - Infrared light-emitting device - Google Patents

Abstract

To provide an infrared light-emitting device with a high emission intensity.SOLUTION: An infrared light-emitting device comprises a substrate and a plurality of mesa type semiconductor lamination parts. In each of the plurality of mesa type semiconductor lamination parts, a first semiconductor layer (21), a light-emitting layer, and a second semiconductor layer (23) are sequentially laminated on the substrate. A connection electrode (E) electrically connects the second semiconductor layers of first and second mesa type semiconductor lamination parts (101 and 102) and the first semiconductor layers of third and fourth mesa type semiconductor lamination parts (103 and 104) to each other. The first and second mesa type semiconductor lamination parts are electrically in parallel with each other. The third and fourth mesa type semiconductor lamination parts are electrically in parallel with each other. The connection electrode is formed so as to transverse at least one of the plurality of mesa type semiconductor lamination parts in a plan view.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to infrared light emitting devices.

In general, long-wavelength infrared rays with a wavelength of 2 μm or more are used for human sensors, non-contact temperature sensors, gas sensors, and the like for detecting human bodies due to their thermal effects and infrared absorption effects by gas. For example, gas sensors have been attracting attention in recent years because they can be used to monitor and protect atmospheric environments, as well as early detection of fires. Especially in the region from about 2.5 μm to about 10.0 μm, there are many absorption bands unique to various gases, and this wavelength band is suitable for use in gas sensors.

The principle of the gas sensor using infrared rays is as follows. For example, when a gas is injected into the space between the infrared light source and the light receiving element, a specific gas absorbs infrared rays of a specific wavelength. type and concentration can be measured. Here, for example, an incandescent bulb is used as the infrared light source, and the infrared rays emitted from the incandescent bulb are white light. Therefore, in order to disperse a specific wavelength, it is necessary to provide a filter on the light receiving element side. Such filters are expensive and reduce the sensitivity of the gas sensor by reducing the intensity of the infrared radiation. Furthermore, the light source must be replaced frequently due to the short life of the incandescent bulb.

In order to solve the above problems, it is effective to use a semiconductor light-emitting element that emits infrared rays of a specific wavelength as the light source. A semiconductor light-emitting element that emits infrared rays is, for example, an infrared LED (Light Emitting Diode). Analytical instruments using infrared LEDs can be made smaller, lighter, and consume less power than analytical instruments using other light sources (for example, light bulbs, etc.). Infrared LEDs are effective light sources for portable, space-saving, and low-power analytical instrumentation. Also, the infrared LED may be driven using an IC (Integrated Circuit).

Such an infrared LED has a so-called pn junction diode structure in which a light-emitting layer having a bandgap capable of emitting infrared light with a wavelength of about 2 μm or more is sandwiched between an n-layer and a p-layer. In the infrared light emitting element, when a forward current flows, electrons and holes recombine in the light emitting layer, thereby emitting infrared light corresponding to the bandgap.

However, at present, analytical instruments that use LEDs as light sources, especially in the infrared region, have not spread widely. One of the reasons for this is that a known infrared LED cannot provide a sufficient emission intensity, and therefore a sufficient signal intensity (S/N ratio) cannot be obtained for the entire analytical instrument. Since the S/N ratio improves as the emission intensity increases, sufficient emission intensity of infrared LEDs must be obtained for wide application.

Further, since the infrared light emitting element emits infrared rays having a wavelength of about 2 μm or more, the light emitting layer is often composed of a so-called narrow gap material. Such an infrared light emitting element may have a structure in which multiple stages are connected in series because the voltage applied to each diode stage is low. For example, Patent Literature 1 discloses an infrared light emitting device having a structure in which mesa-shaped LEDs are connected in series in multiple stages.

JP 2019-009438 A

2. Description of the Related Art In order to realize an infrared light emitting device with a higher emission intensity, semiconductor light emitting devices (LEDs) that emit infrared rays are desired to have a further improvement in emission intensity.

An object of the present disclosure, which has been made in view of such circumstances, is to provide an infrared light emitting device with high emission intensity.

An infrared light emitting device according to an embodiment of the present disclosure includes
a substrate;
a plurality of mesa semiconductor laminates including at least a first mesa semiconductor laminate, a second mesa semiconductor laminate, a third mesa semiconductor laminate, and a fourth mesa semiconductor laminate. ,
each of the plurality of mesa-shaped semiconductor lamination portions has a first semiconductor layer, a light emitting layer, and a second semiconductor layer laminated in this order on the substrate;
By connecting electrodes,
the second semiconductor layer of the first mesa-type semiconductor laminate;
the second semiconductor layer of the second mesa-type semiconductor stack;
the first semiconductor layer of the third mesa semiconductor stack;
is electrically connected to the first semiconductor layer of the fourth mesa-shaped semiconductor laminate,
the first mesa semiconductor laminate and the second mesa semiconductor laminate are electrically parallel;
the third mesa-shaped semiconductor lamination portion and the fourth mesa-shaped semiconductor lamination portion are electrically parallel;
The connection electrode is formed so as to cross at least one of the plurality of mesa-type semiconductor lamination parts in plan view.

According to the present disclosure, it is possible to provide an infrared light emitting device with high emission intensity.

FIG. 1 is a diagram illustrating the structure of an infrared light emitting device according to one embodiment. FIG. 2 is a cross-sectional view for explaining the structure of the mesa-type semiconductor lamination. FIG. 3 is a diagram for explaining the shape of the mesa-type semiconductor lamination portion in a plan view. FIG. 4 is an enlarged view for explaining the structure of the infrared light emitting device according to one embodiment. FIG. 5 is an enlarged view for explaining another structure of the infrared light emitting device according to one embodiment. FIG. 6 is an enlarged view for explaining still another structure of the infrared light emitting device according to one embodiment. FIG. 7 is a diagram illustrating the result of comparing luminous efficiencies. FIG. 8 is a diagram illustrating the structure of an infrared light emitting device of a comparative example.

An infrared light emitting device according to an embodiment of the present disclosure will be described below with reference to the drawings. In each figure, the same reference numerals are given to the same or corresponding parts. In the description of this embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate.

<Infrared light emitting device>
Before describing the structure of the infrared light emitting device according to this embodiment, first, an infrared light emitting device of a comparative example will be described. FIG. 8 shows an infrared light emitting device of a comparative example having a general structure in which mesa-type infrared LEDs are connected in series in multiple stages. The infrared light emitting device of the comparative example includes a plurality of mesa-shaped infrared LEDs that are rectangular in plan view. In the infrared light emitting device of the comparative example, the p-layer of the mesa-shaped infrared LED and the n-layer of the adjacent mesa-shaped infrared LED are electrically connected by the connection electrode to form a series multistage connection. For example, the four mesa infrared LEDs included in the area A1 in FIG. 8 have a structure in which four infrared LEDs are connected in series as shown in the circuit diagram shown at the bottom. Here, the connection electrode is a metal layer electrically connected to the p-layer and n-layer of the infrared LED.

For example, as a technique for improving the emission intensity of a mesa-type infrared LED, when the input current density per unit area is constant, the mesa width is increased to increase the emission area of one mesa. However, when the mesa width is simply increased, a biased distribution of current density occurs within the mesa. Therefore, in a structure like the infrared light emitting device of the comparative example, the effective light emitting area that contributes to the improvement of the light emission intensity cannot be effectively increased. However, there is a problem that the emission intensity is not improved. As a result of earnest research into ways to solve this problem, the inventors have arrived at the structure of the infrared light emitting device according to the present embodiment described below.

FIG. 1 is a schematic plan view showing a schematic structure of an infrared light emitting device according to this embodiment. While the infrared light-emitting device of the comparative example has a structure in which mesa-shaped infrared LEDs are connected in series in multiple stages, the infrared light-emitting device according to the present embodiment has a set of electrically parallel mesa-shaped infrared LEDs, and an infrared LED are connected in series. For example, the four mesa-shaped infrared LEDs included in the area A1 of FIG. 1 have a structure in which two sets of infrared LEDs connected in parallel are connected in series as shown in the circuit diagram shown at the bottom. Although the details of the structure will be described later, the effective light emitting area can be increased by electrically parallel mesa-type infrared LEDs so as not to cause a biased distribution of current density. In the following, after the outline of the cross-sectional structure of the infrared light emitting device according to the present embodiment, the substrate, and the elements of the mesa-type semiconductor laminated portion (mesa-type infrared LED), the electrical connection of the plurality of infrared LEDs, etc. will be described. be.

FIG. 2 is a cross-sectional view for explaining the structure of the mesa-type semiconductor lamination. The mesa-type semiconductor laminate is a mesa-type infrared LED in this embodiment. Each of the plurality of mesa-shaped semiconductor stacks includes a first semiconductor layer 21 , a light emitting layer 22 and a second semiconductor layer 23 and is formed on the substrate 10 . As shown in FIG. 2, a first semiconductor layer 21, a light-emitting layer 22, and a second semiconductor layer 23 are laminated in this order on a substrate 10 to form a mesa-type semiconductor laminate. A layer of SiO ₂ is formed on the side surface of the mesa-type semiconductor lamination, and a layer of SiN, which is an insulating film, is formed thereon. The insulating film is formed so as to cover the plurality of mesa-type semiconductor laminates. The connection electrode E is formed on the insulating film and electrically connected to the second semiconductor layer 23 (p-layer) and the first semiconductor layer 21 (n-layer) of the infrared LED. Although the details will be described later, the connection of the connection electrode E includes corresponding parallel p-layer-p-layer connection and n-layer-n-layer connection, and corresponding series-n-layer-p layer connection. The connection electrodes E do not have a structure facing each other in the stacking direction via an insulating film. That is, in manufacturing the infrared light emitting device according to this embodiment, the electrode forming process can be performed in one step.

FIG. 3 is a diagram for explaining the shape of the mesa-type semiconductor lamination portion in a plan view. In this embodiment, each of the plurality of mesa-shaped semiconductor lamination parts is rectangular in plan view. In the example of FIG. 3, the shape of the mesa-type semiconductor lamination portion in plan view is shown as a rectangle R1. Rectangle R1 has a long side L11 and a short side L12. In the example of FIG. 3, a rectangle R2 corresponding to the second semiconductor layer 23 in plan view is also shown. Rectangle R2 has a long side L21 and a short side L22. A connection portion between the first semiconductor layer 21 and the connection electrode E may be formed along the long side L11 of the rectangle R1. Also, the connection portion between the second semiconductor layer 23 and the connection electrode E may be formed along the long side L21 of the rectangle R2. By forming the shape of the connection portion between the first semiconductor layer 21 or the second semiconductor layer 23 and the connection electrode E along the long side L11 or the long side L21, the distribution of the current density is biased in the mesa. becomes less likely to occur.

<Substrate>
The substrate 10 is a support substrate for supporting a plurality of semiconductor laminates formed by known film formation techniques, for example. The substrate 10 may be made of a single element semiconductor material or may be made of a compound semiconductor material. Substrate 10 is made of a material that is transparent to emitted infrared radiation. By way of example, the substrate 10 is made of semiconductor materials such as gallium arsenide (GaAs), silicon (Si), indium phosphide (InP), and indium antimonide (InSb), but is not limited thereto. Also, the substrate 10 can typically be a single crystal substrate, but is not limited to this. In this embodiment, the substrate 10 is assumed to be a single crystal GaAs substrate selected from the viewpoint of single crystal growth of compound semiconductors. The plane orientation of the substrate 10 is not particularly limited, but (001), (111), (101), etc. are desirable. Further, a plane orientation inclined by about 1° to 5° with respect to these plane orientations may be used.

There is no doping limitation with donor or acceptor impurities in the substrate 10 . However, from the viewpoint of making it possible to connect each of the plurality of infrared LEDs formed on the substrate 10 in series or in parallel, it is desirable to be electrically isolated (that is, semi-insulated or insulated) from the semiconductor laminate.

Here, in the semiconductor manufacturing process, the surface of the substrate 10 may be heated in a vacuum to remove the oxide film, or after removing contaminants such as organic substances and metals, cleaning treatment with an acid or alkali cleaning agent. may be performed.

<First semiconductor layer>
The first semiconductor layer 21 is a first conductivity type semiconductor layer formed on the substrate 10 . The first semiconductor layer 21 is, for example, aluminum arsenide (AlAs), gallium arsenide (GaAs), indium arsenide (InAs), aluminum antimonide (AlSb), gallium antimonide (GaSb), indium antimonide (InSb). ) and indium phosphide (InP).

Also, for the first semiconductor layer 21 , a semiconductor material whose bandgap is larger than that of the light emitting layer 22 can be selected. This is expected to improve the effect of confining carriers in the light-emitting layer 22 .

Here, when the first semiconductor layer 21 has a laminated structure, at least a layer in the first semiconductor layer 21 that is in direct contact with the light-emitting layer 22 has a bandgap greater than that of the light-emitting layer 22 . preferable.

The first semiconductor layer 21 has a first conductivity type and has a conductivity type opposite to the second conductivity type of the second semiconductor layer 23 .

In the present disclosure, conductivity type refers to either so-called n-type or p-type according to the type of carrier. Typically, the n-type semiconductor is an impurity semiconductor doped with a donor impurity such as phosphorus (P). A p-type semiconductor is an impurity semiconductor doped with an acceptor impurity such as boron (B). However, the first semiconductor layer 21 only needs to function as a conductive semiconductor, and does not necessarily have to be doped with such impurities. In the present disclosure, from the viewpoint of improving the infrared transmittance due to the Burstein-Moss effect, the first conductivity type is n-type, and the second conductivity type is p-type. However, the combination is not limited to this, and the first conductivity type may be p-type and the second conductivity type may be n-type. Here, the dopant concentration (impurity density) of the first semiconductor layer 21 when impurities are doped is preferably 1×10 ¹⁸ cm ⁻³ or more from the viewpoint of reducing the contact resistance with metal. Also, from the viewpoint of ensuring crystallinity, it is preferably 1×10 ¹⁹ cm ⁻³ or less.

<Light emitting layer>
The light-emitting layer 22 is a semiconductor layer formed on the first semiconductor layer 21 and emitting infrared light having a predetermined wavelength. In this embodiment, the light-emitting layer 22 is composed of a compound semiconductor having a bandgap corresponding to the emission of infrared light having a wavelength of approximately 2 μm or greater. As an example, the light emitting layer 22 is made of a mixed crystal semiconductor material of AlAs, GaAs, InAs, AlSb, GaSb, InSb, and InP, or any one of them.

The light-emitting layer 22 may have a single-layer structure or a laminated structure. In this embodiment, the light-emitting layer 22 is assumed to have a multiple quantum well structure with semiconductor layers having different bandgaps, but is not limited to this.

The light emitting layer 22 may be a conductive (n-type or p-type) semiconductor, or may be an intrinsic (i-type) semiconductor containing no or almost no impurities.

<Second semiconductor layer>
The second semiconductor layer 23 is a semiconductor layer of the second conductivity type formed on the light emitting layer 22 . In this embodiment, the second conductivity type is p-type. The second semiconductor layer 23 is made of, for example, one or a mixed crystal compound semiconductor material of AlAs, GaAs, InAs, AlSb, GaSb, InSb, and InP. In this embodiment, the second semiconductor layer 23 is made of a compound semiconductor material selected in consideration of the double heterojunction with the first semiconductor layer 21 and the light emitting layer 22 .

The second semiconductor layer 23 may have a single layer structure or a laminated structure. When the second semiconductor layer 23 has a laminated structure, it is preferable that at least a layer of the second semiconductor layer 23 that is in direct contact with the light emitting layer 22 has a bandgap larger than that of the light emitting layer 22 .

The dopant concentration (impurity density) of the second semiconductor layer 23 when doped with impurities is preferably 1×10 ¹⁸ cm ⁻³ or more from the viewpoint of reducing the contact resistance with metal. From the viewpoint of ensuring properties, it is preferably 1×10 ¹⁹ cm ⁻³ or less.

<Electrode>
As materials for the electrode (upper electrode layer) provided on the second semiconductor layer 23 and the electrode (lower electrode layer) provided on the first semiconductor layer 21, materials with high reflectance in the mid-infrared region are preferred. Au and Al can be used. Also, the upper electrode layer and the lower electrode layer may be laminated with different electrode materials in order to reduce contact resistance, improve adhesion, and prevent mutual diffusion between the electrode material and the semiconductor material. For example, Ti, Pt, Ni, Cr, etc. can also be used. The film thickness of each layer is designed so as not to hinder the reflectance of the upper electrode layer. Materials for the electrodes are not limited to these. The upper electrode layer and the lower electrode layer may be different materials or the same material. The upper electrode layer and the lower electrode layer may be formed simultaneously in one step.

(details of structure)
FIG. 4 is an enlarged view for explaining the structure of the infrared light emitting device according to this embodiment. In the example of FIG. 4, as the plurality of mesa-type semiconductor lamination portions of the infrared light emitting device, a first mesa-type semiconductor lamination portion 101, a second mesa-type semiconductor lamination portion 102, a third mesa-type semiconductor lamination portion 103, and a third mesa-type semiconductor lamination portion 103 are shown. 4 mesa semiconductor stacks 104 are shown. FIG. 4 corresponds to an enlarged view of part of area A1 in FIG. Therefore, the plurality of mesa semiconductor laminates of the infrared light emitting device includes at least these four mesa semiconductor laminates. The structures of the four mesa-type semiconductor laminates described below are the same for the other mesa-type semiconductor laminates of the infrared light emitting device.

By the connection electrode E, the second semiconductor layer 23 of the first mesa semiconductor laminate 101, the second semiconductor layer 23 of the second mesa semiconductor laminate 102, and the third mesa semiconductor laminate 103 are connected. and the first semiconductor layer 21 of the fourth mesa-shaped semiconductor lamination portion 104 are electrically connected. The first mesa-type semiconductor lamination portion 101 and the second mesa-type semiconductor lamination portion 102 are electrically parallel to form a first set. In addition, the third mesa-type semiconductor lamination portion 103 and the fourth mesa-type semiconductor lamination portion 104 are electrically parallel to form a second set. Moreover, the connection electrode E connects the first set and the second set in series.

As shown in FIG. 4, the connection electrode E includes a group of first extensions, which are a plurality of extensions B electrically connected to the second semiconductor layer 23 of the first mesa-shaped semiconductor laminate 101; and a group of second extending portions, which are a plurality of extending portions B electrically connected to the first semiconductor layer 21 of the fourth mesa-shaped semiconductor lamination portion 104 . In FIG. 4, the extension B belonging to the group of the first extensions is indicated as "B1". Further, the extending portion B belonging to the group of the second extending portions is indicated as "B2". Such a configuration of the connection electrodes E determines the interval D between the connection portions in a plan view. The connection portion is a portion where the first semiconductor layer 21 or the second semiconductor layer 23 and the connection electrode E are connected, and is indicated by a dashed square in FIG. It is desirable that the distance D between the connecting portions is equal to or less than a predetermined length in order to prevent uneven distribution of current density in the mesa. The predetermined length is, for example, 50 μm, but is not limited to this. Also, it is desirable that the short side L22 of the rectangle R2 shown in FIG. 3 is equal to or shorter than the predetermined length.

Moreover, the connection electrode E is formed so as to cross at least one of the plurality of mesa-type semiconductor lamination parts in a plan view. In the example of FIG. 4, the connection electrode E crosses the third mesa-type semiconductor laminate 103 by means of the second extending portion (see area A2). In addition, the connection electrode E also crosses the second mesa-type semiconductor lamination part 102 by means of the second extension part, the first extension part, and their connection region. That is, the connection electrode E in the example of FIG. 4 is formed so as to cross at least two of the plurality of mesa-type semiconductor lamination parts in plan view.

Here, the connection electrode E corresponds to the first mesa semiconductor lamination portion 101, the second mesa semiconductor lamination portion 102, the third mesa semiconductor lamination portion 103, and the fourth mesa semiconductor lamination portion in plan view. For the smallest square that encloses 104, it is formed to be contained inside the smallest square. The smallest square corresponds to, for example, area A1 in FIG. The connection electrode E does not use a region outside the plurality of mesa-type semiconductor laminates for wiring. In other words, the connection electrode E does not protrude from the range of the plurality of mesa-type semiconductor lamination parts in plan view. Therefore, the infrared light emitting device according to this embodiment can be miniaturized.

Here, the shape of the connection electrode E is not limited to the example in FIG. FIG. 5 is an enlarged view for explaining another structure of the infrared light emitting device according to this embodiment. Unlike the case of FIG. 4, the connection electrode E has a connecting region between the first extending portion and the second extending portion, which is formed by the second semiconductor layer 23 of the second mesa-shaped semiconductor lamination portion 102 and the third It is wide enough to cover the first semiconductor layer 21 of the mesa-type semiconductor lamination portion 103 . In the example of FIG. 5, the connection portion (C in FIG. 5) between the first semiconductor layer 21 and the connection electrode E is formed along the long side L11 (see FIG. 3) of the rectangle R1. Also, the connection portion between the second semiconductor layer 23 and the connection electrode E is formed along the long side L21 (see FIG. 3) of the rectangle R2. Such a shape of the connecting portion makes it difficult for the uneven distribution of current density to occur in the mesa. Here, also in the example of FIG. 5, the connection electrode E traverses the third mesa-type semiconductor lamination portion 103 by means of the second extending portion (see region A2).

FIG. 6 is an enlarged view for explaining still another structure of the infrared light emitting device according to this embodiment. Unlike the case of FIGS. 4 and 5, the connection electrode E in the example of FIG. 6 is configured such that portions corresponding to the first extending portion, the second extending portion, and the connecting region are separated from each other. The connection electrode E corresponding to the first extending portion is indicated as "E1" in FIG. 6, and provides p-layer-p-layer connection. Further, the connection electrode E corresponding to the second extending portion is indicated as "E2" in FIG. 6, and performs n-layer-n-layer connection. Also, the connection electrode E corresponding to the connection region is shown as "E3" in FIG. 6, and connects the n-layer and the p-layer. That is, the connection electrode E may be configured including three metal layers "E1", "E2" and "E3".

(Example)
Using examples, the effects of the infrared light emitting device according to the above embodiment were verified. The infrared light emitting device of the example was manufactured by a known manufacturing method so as to have the structure of the infrared light emitting device according to the above embodiment. On the other hand, the comparative example had a general structure in which mesa-type infrared LEDs were connected in series in multiple stages as shown in FIG. 8, and was manufactured by a known manufacturing method.

FIG. 7 is a diagram showing the results of comparing the luminous efficiencies of the infrared light emitting devices of Example and Comparative Example when operated at a constant current (100 mA). When the luminous efficiency was measured at a wavelength of 2.5 μm to 5 μm, it was shown that the luminous efficiency of the example is higher than that of the comparative example, especially in the emission of infrared light having a wavelength of 3 μm to 4 μm. Here, the solid-line curve in FIG. 7 indicates a comparative example (conventional structure), and the dashed-line curve indicates an example (this embodiment). Further, when the dependence of the luminous efficiency on the current density was measured for the same example and comparative example, it was found that the luminous efficiency decreased as the current density increased in the comparative example. In other words, it was found that the improvement in the luminous efficiency of the example was due to the suppression of the biased current density distribution.

For example, referring to FIG. 4, in the infrared light emitting device of the embodiment, the diode formed by the first mesa-shaped semiconductor lamination section 101 and the diode formed by the second mesa-shaped semiconductor lamination section 102 connected in parallel emit infrared light. It behaves similarly depending on the voltage applied to the light emitting device. Therefore, these two diodes behave as a diode having one stage in series as a whole. At this time, the effective mesa width per step is the sum of the mesa width of the first mesa-type semiconductor lamination portion 101 and the mesa width of the second mesa-type semiconductor lamination portion 102 . This corresponds to twice the mesa width per stage of the infrared light emitting device of the comparative example. However, the mesa width of one diode does not change in the infrared light emitting device of the example. Therefore, in the infrared light emitting device of the embodiment, the mesa width of one diode can be designed to be a predetermined length or less at which current density distribution does not occur while widening the effective mesa width per one series stage. Emission intensity is improved.

As is clear from the comparison between the example and the comparative example, the infrared light emitting device according to this embodiment can increase the emission intensity.

Although the embodiments of the present disclosure have been described with reference to drawings and examples, it should be noted that various variations or modifications can be easily made by those skilled in the art based on the present disclosure. Therefore, it should be noted that these variations or modifications are included within the scope of this disclosure. For example, functions included in each component can be rearranged so as not to be logically inconsistent, and multiple components can be combined into one or divided.

In the above embodiment, the number of parallel mesa-type semiconductor lamination parts is two, but it may be three or more.

Moreover, although the number of parallel connections before and after the series connection is the same (two) in the above embodiment, the number of parallel connections before and after the series connection may be different. In other words, the number of parallel connections before and after the series connection may be asymmetrical.

Also, in the examples such as FIG. 4, the connection electrode E has a group of first extensions, but may have only one first extension. Similarly, the connection electrode E had a group of second extensions, but may have only one second extension.

In addition, in the example of FIG. 4 and the like, the number of groups of the first extending portions and the number of groups of the second extending portions provided in the connection electrode E are the same, but the numbers are different, that is, they are asymmetrical. you can

In addition, in the example of FIG. 4 and the like, the first extending portion and the second extending portion extend with a uniform width. It may have a shape with a width different from that of other portions. For example, in order to reduce the contact resistance, the width of the connection portion with the first semiconductor layer 21 or the second semiconductor layer 23 may be wide, and the width of the other wiring portion may be narrow.

10 substrate 21 first semiconductor layer 22 light emitting layer 23 second semiconductor layer 101 first mesa semiconductor laminate 102 second mesa semiconductor laminate 103 third mesa semiconductor laminate 104 fourth mesa Semiconductor lamination part B Extension part E Connection electrode

Claims (7)

a substrate;
a plurality of mesa semiconductor laminates including at least a first mesa semiconductor laminate, a second mesa semiconductor laminate, a third mesa semiconductor laminate, and a fourth mesa semiconductor laminate. ,
each of the plurality of mesa-shaped semiconductor lamination portions has a first semiconductor layer, a light emitting layer, and a second semiconductor layer laminated in this order on the substrate;
By connecting electrodes,
the second semiconductor layer of the first mesa-type semiconductor laminate;
the second semiconductor layer of the second mesa-type semiconductor stack;
the first semiconductor layer of the third mesa semiconductor stack;
is electrically connected to the first semiconductor layer of the fourth mesa-shaped semiconductor laminate,
the first mesa semiconductor laminate and the second mesa semiconductor laminate are electrically parallel;
the third mesa-shaped semiconductor lamination portion and the fourth mesa-shaped semiconductor lamination portion are electrically parallel;
The infrared light emitting device, wherein the connection electrode is formed so as to cross at least one of the plurality of mesa-type semiconductor lamination parts in a plan view. 2. The infrared light emitting device according to claim 1, wherein said connection electrode is formed so as to cross at least two of said plurality of mesa-type semiconductor lamination parts in plan view. The connection electrode is
a group of first extensions, which are a plurality of extensions electrically connected to the second semiconductor layer of the first mesa-shaped semiconductor laminate;
3. The infrared rays according to claim 1, further comprising: a group of second extensions, which are a plurality of extensions electrically connected to the first semiconductor layer of the fourth mesa-shaped semiconductor laminate. Luminescent device. each of the plurality of mesa-shaped semiconductor lamination parts is rectangular in plan view,
The infrared light emitting device according to any one of claims 1 to 3, wherein a connection portion between said first semiconductor layer and said connection electrode is formed along a long side of said rectangle. The infrared light emitting device according to any one of claims 1 to 4, wherein said connection electrodes do not have a structure facing each other via an insulating film. 6. The infrared light emitting device according to any one of claims 1 to 5, wherein said connection electrode is formed on an insulating film formed to cover said plurality of mesa-type semiconductor laminates. The connection electrode includes the first mesa semiconductor laminate, the second mesa semiconductor laminate, the third mesa semiconductor laminate, and the fourth mesa semiconductor laminate in plan view. 7. The infrared light emitting device according to any one of claims 1 to 6, formed so as to be contained inside said minimum square with respect to a minimum square.

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