JP6986697B2 - Ultraviolet light emitting element - Google Patents

Description

The present invention relates to an ultraviolet light emitting device in general, and more particularly to an ultraviolet light emitting element that emits ultraviolet rays.

Conventionally, an ultraviolet light emitting device including a substrate, a light emitting unit, and a light receiving unit has been proposed (Patent Document 1). Here, the substrate has a first main surface and a second main surface facing the first main surface. The light emitting unit is arranged on the first main surface of the substrate and emits ultraviolet light (ultraviolet rays).

In the ultraviolet light emitting device described in Patent Document 1, a part of the ultraviolet light emitted by the light emitting portion passes through the inside of the substrate and is emitted from the second main surface to the outside. Further, another part of the ultraviolet light emitted by the light emitting portion passes through the inside of the substrate, is reflected by the second main surface, and is incident on the light receiving portion. The light receiving unit photoelectrically converts the received ultraviolet light and outputs an electric signal. Therefore, the light receiving portion is arranged on the first main surface of the substrate at a position where the ultraviolet light reflected at the interface between the second main surface and the space outside the substrate is incident.

Japanese Unexamined Patent Publication No. 2015-70065

In the ultraviolet light emitting device described in Patent Document 1, since it is necessary to reflect another part of the ultraviolet light emitted by the light emitting portion on the second main surface of the substrate and make it incident on the light receiving portion, the light output tends to decrease. ..

An object of the present invention is to provide an ultraviolet light emitting device capable of monitoring light output while suppressing a decrease in light output.

One aspect of the ultraviolet light emitting device according to the present invention includes a substrate and a laminate. The substrate has first and second surfaces that are opposite to each other in the thickness direction. The laminate is provided on the first surface of the substrate. In the laminate, the n-type semiconductor layer, the active layer, and the p-type semiconductor layer are arranged in this order from the substrate side. The laminate is formed on the surface of the laminate opposite to the substrate and has a groove for separating the laminated structure of the active layer and the p-type semiconductor layer into a first semiconductor portion and a second semiconductor portion. Have. The area of the first semiconductor portion is larger than the area of the second semiconductor portion. The ultraviolet light emitting element further includes a first positive electrode, a second positive electrode, a first negative electrode, and a second negative electrode. The first positive electrode is formed on the first semiconductor portion. The second positive electrode is formed on the second semiconductor portion. The first negative electrode is provided on the surface of the n-type semiconductor layer on the active layer side, and is adjacent to the first positive electrode when viewed from the thickness direction. The second negative electrode is provided on the surface of the n-type semiconductor layer on the active layer side, and is adjacent to the second positive electrode when viewed from the thickness direction. The size of the n-type semiconductor layer when viewed from the thickness direction is the same as the size of the substrate. The first negative electrode, the first positive electrode, the second positive electrode, and the second negative electrode are arranged in this order in one direction orthogonal to the thickness direction when viewed from the thickness direction. .. The outer peripheral line of the first semiconductor portion when viewed from the thickness direction is a portion along the outer peripheral line of the n-type semiconductor layer, a portion bent so as to avoid the first negative electrode, and the second portion. It is composed of a semiconductor portion and a portion that is bent so as to avoid the second negative electrode.

The ultraviolet light emitting device of the present invention has an effect that the light output can be monitored while suppressing the decrease in the light output.

FIG. 1A is a plan view of an ultraviolet light emitting device according to an embodiment of the present invention. FIG. 1B shows the same ultraviolet light emitting element, and is a sectional view taken along line XX of FIG. 1A.

FIGS. 1A and 1B described in the following embodiments and the like are schematic views, and the ratio of the size and the thickness of each component in FIGS. 1A and 1B does not necessarily reflect the actual dimensional ratio. Not necessarily.

(Embodiment)
Hereinafter, the ultraviolet light emitting device 10 of the present embodiment will be described with reference to FIGS. 1A and 1B.

The ultraviolet light emitting element 10 is a light emitting element that emits ultraviolet rays in the wavelength range of UV-C. The "UV-C wavelength range" is, for example, 100 nm to 280 nm according to the classification by the wavelength of ultraviolet rays by the International Commission on Illumination (CIE).

The ultraviolet light emitting element 10 includes a substrate 1 and a laminated body 2. The substrate 1 has a first surface 11 and a second surface 12 which are opposite to each other in the thickness direction D1. The laminate 2 is provided on the first surface 11 of the substrate 1.

In the laminated body 2, the n-type semiconductor layer 4, the active layer 5, and the p-type semiconductor layer 6 are arranged in this order from the substrate 1 side. The laminated body 2 has a groove 23 formed on the surface 21 of the laminated body 2 opposite to the substrate 1. The groove 23 is formed so as to separate the laminated structure 7 of the active layer 5 and the p-type semiconductor layer 6 into the first semiconductor portion 71 and the second semiconductor portion 72. Here, the first semiconductor portion 71 and the second semiconductor portion 72 are located inside the outer peripheral line of the n-type semiconductor layer 4 when viewed from the thickness direction D1 of the substrate 1. The size of the n-type semiconductor layer 4 is the same as the size of the substrate 1 when viewed from the thickness direction D1 of the substrate 1. In other words, in the ultraviolet light emitting element 10, the outer peripheral line of the n-type semiconductor layer 4 and the outer peripheral line of the substrate 1 overlap each other when viewed from the thickness direction D1 of the substrate 1.

The ultraviolet light emitting element 10 has a step between the surface 61 of the p-type semiconductor layer 6 and the portion 411 of the surface 41 of the n-type semiconductor layer 4 where the laminated structure 7 is not laminated. Each of the first semiconductor portion 71 and the second semiconductor portion 72 has a mesa structure.

Further, the ultraviolet light emitting element 10 includes a first positive electrode 81 and a second positive electrode 82 electrically connected to the p-type semiconductor layer 6, and a first negative electrode 91 electrically connected to the n-type semiconductor layer 4. And a second negative electrode 92 are further provided.

In the ultraviolet light emitting element 10, the second surface 12 of the substrate 1 constitutes a light extraction surface for emitting ultraviolet rays.

In the ultraviolet light emitting element 10, the laminated body 2 further includes a buffer layer 3 interposed between the substrate 1 and the n-type semiconductor layer 4. Further, the ultraviolet light emitting element 10 further includes a protective film that covers a part of the laminated body 2.

The ultraviolet light emitting element 10 is an LED chip (light emitting diode chip). The shape of the ultraviolet light emitting element 10 in a plan view is, for example, a square shape. The "planar view shape of the ultraviolet light emitting element 10" is the outer peripheral shape of the ultraviolet light emitting element 10 as seen from the thickness direction D1 of the ultraviolet light emitting element 10. The chip size of the ultraviolet light emitting element 10 in a plan view is, for example, 400 μm □ (400 μm × 400 μm).

Each component of the ultraviolet light emitting element 10 will be described in more detail below.

The substrate 1 supports the laminated body 2. In the ultraviolet light emitting element 10, AlGaN is adopted as the material of the active layer 5, and the substrate 1 is, for example, a sapphire substrate. The first surface 11 of the substrate 1 has an off angle from the (0001) surface (that is, the c surface), for example, 0.31 °. Here, the "off angle" is the inclination angle of the first surface 11 with respect to the (0001) surface. Therefore, if the off angle is 0 °, the first surface 11 is the (0001) surface. The thickness of the substrate 1 is, for example, 150 μm. The outer peripheral shape of the substrate 1 is a square shape.

In the laminate 2 provided on the first surface 11 of the substrate 1, the buffer layer 3, the n-type semiconductor layer 4, the active layer 5 and the p-type semiconductor layer 6 are arranged in this order from the substrate 1 side. The laminate 2 is formed by using, for example, the MOVPE method (metal organic vapor phase epitaxy) or the like.

In the present specification, the composition ratio described later is a value obtained by composition analysis by the EDX method (energy dispersive X-ray spectroscopy). In discussing the relative magnitude relationship of the composition ratio, the composition ratio is not limited to the EDX method, and may be, for example, a value obtained by composition analysis by Auger electron spectroscopy.

The active layer 5 is configured to be able to radiate ultraviolet rays in the wavelength range of UV-C. The active layer 5 between the n-type semiconductor layer 4 and the p-type semiconductor layer 6 emits ultraviolet rays by recombination of two types of injected carriers (electrons and holes). The emission peak wavelength of the ultraviolet light emitting element 10 is, for example, 275 nm. The "emission peak wavelength" here is the main emission peak wavelength at room temperature (27 ° C.). The "emission peak wavelength of the ultraviolet light emitting element 10" is the emission peak wavelength of the ultraviolet rays emitted from the active layer 5 and emitted from the ultraviolet light emitting element 10.

In the active layer 5, a plurality of (for example, four) barrier layers and a plurality of (for example, four) well layers are alternately arranged in the thickness direction D1 of the substrate 1. As a result, the active layer 5 has a multiple quantum well structure. Each of the plurality of well layers is composed of a first AlGaN layer. Each of the plurality of barrier layers is composed of a second AlGaN layer having a composition ratio of Al larger than that of the first AlGaN layer. The well layer (first AlGaN layer) is, for example, an Al _0.45 Ga _0.55 N layer having a thickness of 2 nm. The barrier layer (second AlGaN layer) is, for example, an Al _0.60 Ga _0.40 N layer having a thickness of 10 nm. The thickness of each of the plurality of well layers is, for example, 2 nm. The thickness of each of the plurality of barrier layers is, for example, 10 nm.

The buffer layer 3 is, for example, an AlN layer. The buffer layer 3 is a layer provided for the purpose of improving the crystallinity of the n-type semiconductor layer 4, the active layer 5, and the p-type semiconductor layer 6. In the ultraviolet light emitting element 10, the bandgap energy of the buffer layer 3 is larger than the bandgap energy of each of the plurality of well layers in the active layer 5. The buffer layer 3 is formed on the entire surface of the first surface 11 of the substrate 1.

The n-type semiconductor layer 4 is, for example, an n-type AlGaN layer. The Al composition ratio of the n-type AlGaN layer is set so that the absorption of ultraviolet rays emitted by the active layer 5 in the n-type AlGaN layer is suppressed. More specifically, the n-type semiconductor layer 4 is, for example, an n-type Al _0.60 Ga _0.40 N layer. The thickness of the n-type semiconductor layer 4 is, for example, 2 μm. The n-type semiconductor layer 4 is formed on the entire surface of the buffer layer 3 on the opposite side of the substrate 1. Therefore, the outer peripheral shape of the n-type semiconductor layer 4 is the same as the outer peripheral shape of the substrate 1.

The p-type semiconductor layer 6 includes, for example, a p-type AlGaN layer and a p-type GaN layer. In the p-type semiconductor layer 6, the p-type AlGaN layer is in contact with the active layer 5. Further, in the p-type semiconductor layer 6, the p-type GaN layer is located on the opposite side of the active layer 5 of the p-type AlGaN layer. The Al composition ratio of the p-type AlGaN layer is set so as to prevent electrons injected from the n-type semiconductor layer 4 into the active layer 5 from leaking to the p-type semiconductor layer 6 side. More specifically, the p-type AlGaN layer is, for example, a p-type Al _0.80 Ga _0.20 N layer. The thickness of the p-type AlGaN layer is, for example, 50 nm. The thickness of the p-type GaN layer is, for example, 200 nm.

In the ultraviolet light emitting element 10, the laminated structure 7 of the active layer 5 and the p-type semiconductor layer 6 is formed with the first semiconductor portion 71 by the groove 23 formed on the surface 21 of the laminated body 2 opposite to the substrate 1. It is separated from the second semiconductor unit 72. As a result, the ultraviolet light emitting element 10 is one of the first functional portion 51, which is a portion of the active layer 5 that constitutes a part of the first semiconductor portion 71 of the laminated structure 7, and the second semiconductor portion 72 of the laminated structure 7. It has a second functional unit 52, which is a portion constituting the unit. Each of the end faces 513 and 523 of the first functional portion 51 and the second functional portion 52 facing each other is formed along the thickness direction D1 of the substrate 1. In the ultraviolet light emitting element 10, it is preferable that the end faces 513 and 523 of the first functional unit 51 and the second functional unit 52 facing each other are parallel to each other. Here, "parallel" is not limited to the case of being strictly parallel, and may be substantially parallel (the angle formed by the end faces 513 and 523 facing each other is, for example, 0 ° ± 10 °).

As described above, the ultraviolet light emitting element 10 includes a first positive electrode 81, a second positive electrode 82, a first negative electrode 91, and a second negative electrode 92. In the ultraviolet light emitting element 10, a first positive electrode 81, a second positive electrode 82, a first negative electrode 91, and a second negative electrode 92 are arranged on one surface side of the ultraviolet light emitting element 10 in the thickness direction. Here, "one surface in the thickness direction of the ultraviolet light emitting element 10" means the surface of the portion 411 and the p-type semiconductor layer 6 on the surface 41 of the n-type semiconductor layer 4 on the active layer 5 side, which is not covered by the active layer 5. Includes 61.

The first positive electrode 81 is formed on the first semiconductor portion 71 of the laminated structure 7 of the active layer 5 and the p-type semiconductor layer 6. As a result, the first positive electrode 81 is electrically connected to the p-type semiconductor layer 6 in the first semiconductor portion 71. The second positive electrode 82 is formed on the second semiconductor portion 72 of the laminated structure 7. As a result, the second positive electrode 82 is electrically connected to the p-type semiconductor layer 6 in the second semiconductor portion 72. The first negative electrode 91 is provided at a portion 411 of the surface 41 on the active layer 5 side of the n-type semiconductor layer 4 where the laminated structure 7 is not laminated. As a result, the first negative electrode 91 is electrically connected to the n-type semiconductor layer 4. The second negative electrode 92 is provided at the portion 411 of the surface 41 on the active layer 5 side of the n-type semiconductor layer 4 where the laminated structure 7 is not laminated. As a result, the second negative electrode 92 is electrically connected to the n-type semiconductor layer 4.

In the ultraviolet light emitting element 10, the first negative electrode 91, the first positive electrode 81, the second positive electrode 82, and the second negative electrode are in one direction orthogonal to the thickness direction D1 when viewed from the thickness direction D1 of the substrate 1. The electrodes 92 are arranged in this order. Therefore, the first negative electrode 91 is adjacent to the first positive electrode 81 when viewed from the thickness direction D1 of the substrate 1. Further, the second negative electrode 92 is adjacent to the second positive electrode 82 when viewed from the thickness direction of the substrate 1.

In the ultraviolet light emitting element 10, ultraviolet rays are radiated from the first functional unit 51 of the active layer 5 by passing a current between the first positive electrode 81 and the first negative electrode 91. In the ultraviolet light emitting element 10, ultraviolet rays radiated from the first functional unit 51 and incident on the first surface 11 of the substrate 1 are emitted from the second surface 12 of the substrate 1. Here, in the ultraviolet light emitting element 10, the ultraviolet rays emitted from the end surface 513 of the first functional unit 51 of the active layer 5 are incident on the end surface 523 of the second functional unit 52 of the active layer 5, and are received by the second functional unit 52. Be (absorbed). Therefore, in the ultraviolet light emitting element 10, for example, the second positive electrode 82 and the second negative electrode 92 are generated by emitting ultraviolet rays from the first functional unit 51 and receiving a part of the ultraviolet rays by the second functional unit 52. It is possible to monitor the light output of the ultraviolet light emitting element 10 by the current (light current) generated during the period. In short, the ultraviolet light emitting element 10 can be operated with the first functional unit 51 as the light emitting unit and the second functional unit 52 as the light receiving unit.

In the ultraviolet light emitting element 10, the area of the first semiconductor portion 71 is larger than the area of the second semiconductor portion 72. Here, the area of each of the first semiconductor portion 71 and the second semiconductor portion 72 is the area seen from the thickness direction D1 of the substrate 1. In the ultraviolet light emitting element 10, the area of the first positive electrode 81 is larger than the area of the second positive electrode 82, and the area of the first negative electrode 91 is larger than the area of the second negative electrode 92. The area of each of the first positive electrode 81, the second positive electrode 82, the first negative electrode 91, and the second negative electrode 92 is the area seen from the thickness direction D1 of the substrate 1.

The plan view shape of the first semiconductor portion 71 is a shape in which the intermediate portions of the two sides of the square along the outer peripheral line of the substrate 1 are recessed inward. Here, in the ultraviolet light emitting element 10, the outer peripheral line of the first semiconductor portion 71 is along the outer peripheral line of the n-type semiconductor layer 4 and the second semiconductor portion 72 is viewed from the thickness direction D1 of the substrate 1. And the first negative electrode 91 and the second negative electrode 92 are bent so as to avoid them. As a result, in the ultraviolet light emitting element 10, the area of the first semiconductor portion 71 can be made larger than that in the case where the plan view shape of the first semiconductor portion 71 is rectangular.

The ultraviolet light emitting element 10 preferably includes a protective film. The protective film has electrical insulation. The material of the protective film is, for example, silicon oxide or the like. The protective film includes a portion and a side surface of the surface of the first semiconductor portion 71 that is not covered by the first positive electrode 81, and a portion and a side surface of the surface of the second semiconductor portion 72 that is not covered by the second positive electrode 82. The surface 41 of the n-type semiconductor layer 4 is formed so as to straddle the region of the portion 411 not covered by the active layer 5 and not covered by the first negative electrode 91 and the second negative electrode 92. Is preferable.

In the ultraviolet light emitting device 10 of the present embodiment described above, the laminated body 2 has a groove 23 that separates the laminated structure 7 of the active layer 5 and the p-type semiconductor layer 6 into the first semiconductor portion 71 and the second semiconductor portion 72. The area of the first semiconductor portion 71 is larger than the area of the second semiconductor portion 72. Therefore, the ultraviolet light emitting element 10 emits ultraviolet rays radiated laterally from the first semiconductor unit 71, which has a relatively large area among the first semiconductor unit 71 and the second semiconductor unit 72, and has a relatively small area. 2 The semiconductor unit 72 can receive light. As a result, in the ultraviolet light emitting element 10, it is not necessary to reflect the ultraviolet rays radiated from the first semiconductor portion 71 to the substrate 1 side on the second surface 12 of the substrate 1, so that the light output can be suppressed while suppressing the decrease in the optical output. Monitoring becomes possible.

Further, in the ultraviolet light emitting element 10, it is possible to increase the light output while reducing the chip size as compared with the above ultraviolet light emitting device. Further, in the ultraviolet light emitting element 10, the center of the first functional unit 51 (light emitting unit) and the intersection of the first functional unit 51 with respect to the center line of the substrate 1 along the thickness direction D1 of the substrate 1 are aligned. , The optical axis of the ultraviolet light emitting element 10 tends to be aligned with the center line along the thickness direction D1 of the substrate 1. As a result, the ultraviolet light emitting element 10 is advantageous in terms of light distribution control by a lens, a reflecting member, or the like, as compared with the above ultraviolet light emitting device.

Hereinafter, an example of a method for manufacturing the ultraviolet light emitting element 10 will be briefly described.

In the method for manufacturing the ultraviolet light emitting element 10, first, a wafer (sapphire wafer) that is the basis of the substrate 1 of each of the plurality of ultraviolet light emitting elements 10 is prepared.

In the method for manufacturing the ultraviolet light emitting element 10, after preparing the wafer, the wafer is pretreated, the wafer is introduced into the epitaxial growth apparatus, and then the laminate 2 is laminated on the first surface of the wafer by the epitaxial growth method. .. The first surface of the wafer is a surface corresponding to the first surface 11 of the substrate 1. When a MOVPE device is used as the epitaxial growth device, it is preferable to use trimethylaluminum (TMAl) as the raw material gas for Al. Further, it is preferable to use trimethylgallium (TMGa) as the raw material gas for Ga. It is preferable to use _{NH 3} as the raw material gas for N. It is preferable to use tetraethylsilane (TESi) as the raw material gas for Si, which is an impurity that imparts n-type conductivity. It is preferable to use _{biscyclopentadienyl magnesium (Cp 2} Mg) as the raw material gas for Mg, which is an impurity that contributes to p-type conductivity. As the carrier gas for each raw material gas, for example, it is preferable to use _{H 2 gas.} The raw material gas is not particularly limited, and for example, triethyl gallium (TEGa) _{may be used as the raw material gas for Ga, a hydrazine derivative may be used as the raw material gas for N, and monosilane (SiH 4} ) may be used as the raw material gas for Si. The growth conditions of the laminated body 2 are appropriately set to the substrate temperature, V / III ratio, supply amount of each raw material gas, growth pressure, etc. for each of the buffer layer 3, the n-type semiconductor layer 4, the active layer 5, and the p-type semiconductor layer 6. Just set it. "Substrate temperature" means the temperature of the wafer. When a MOVPE device is adopted as the epitaxial growth device, the "substrate temperature" can be, for example, the temperature of a susceptor supporting the wafer. For example, the substrate temperature can be substituted with the temperature of the susceptor measured by the thermocouple.

In the method for manufacturing the ultraviolet light emitting element 10, the laminated body 2 is laminated on the first surface of the wafer, and then the wafer on which the laminated body 2 is laminated is taken out from the epitaxial growth apparatus. In the following, a structure including at least a wafer and a laminated body 2 will be referred to as an epitaxial wafer.

In the method for manufacturing the ultraviolet light emitting device 10, the epitaxial wafer taken out from the epitaxial growth device is introduced into the annealing device, and annealing is performed to activate the p-type impurities in the p-type semiconductor layer. As the annealing device for annealing, for example, a lamp annealing device, an electric furnace annealing device, or the like can be adopted. The p-type impurity means an acceptor impurity and is Mg.

In the method for manufacturing the ultraviolet light emitting element 10, after taking out the epitaxial wafer from the annealing device, the laminated structure 7 of the active layer 5 and the p-type semiconductor layer 6 in the laminated body 2 is patterned by using a photolithography technique, an etching technique, or the like. By doing so, the groove 23, the first semiconductor portion 71, and the second semiconductor portion 72 are formed.

In the method for manufacturing the ultraviolet light emitting element 10, the groove 23, the first semiconductor portion 71, and the second semiconductor portion 72 are formed, and then the above-mentioned protective film is formed. The protective film can be formed by using a thin film forming technique such as a CVD method (chemical vapor deposition), a photolithography technique, and an etching technique.

In the method for manufacturing the ultraviolet light emitting element 10, after forming the protective film, the first negative electrode 91 and the second negative electrode 92 are formed, and then the first positive electrode 81 and the second positive electrode 82 are formed.

In the method for manufacturing the ultraviolet light emitting element 10, an epitaxial wafer in which a plurality of ultraviolet light emitting elements 10 are formed can be obtained.

In the method for manufacturing the ultraviolet light emitting element 10, a plurality of ultraviolet light emitting elements 10 can be obtained from one epitaxial wafer by cutting the epitaxial wafer with a dicing saw or the like. In the method for manufacturing the ultraviolet light emitting element 10, before cutting the epitaxial wafer, the wafer is polished from the second surface opposite to the first surface so that the thickness of the wafer is the desired thickness of the substrate 1. preferable. As a result, the method for manufacturing the ultraviolet light emitting element 10 can improve the manufacturing yield.

According to the method for manufacturing the ultraviolet light emitting element 10 described above, the first semiconductor unit 71 and the second semiconductor unit 72 can have the same configuration. Here, "same composition" means that the materials, composition ratios and thicknesses are the same. Further, according to the method for manufacturing the ultraviolet light emitting element 10 described above, the relative positions of the end surface 513 of the first functional unit 51 in the first semiconductor unit 71 and the end surface 523 of the second functional unit 52 in the second semiconductor unit 72. The accuracy can be improved.

The above embodiment is just one of various embodiments of the present invention. The above embodiment can be variously modified according to the design and the like as long as the object of the present invention can be achieved.

For example, the ultraviolet light emitting element 10 is not limited to the case where it is configured to emit ultraviolet rays in the wavelength range of UV-C, and may be configured to emit ultraviolet rays in the wavelength range of UV-B, for example. .. The "UV-B wavelength range" is, for example, 280 nm to 315 nm according to the classification by the wavelength of ultraviolet rays by the International Commission on Illumination.

Further, the shape of the ultraviolet light emitting element 10 in a plan view is not limited to a square shape, and may be, for example, a rectangular shape.

Further, the off angle of the first surface 11 of the substrate 1 from the (0001) surface (c surface) is preferably, for example, 0 ° to 0.4 °, preferably 0.1 ° to 0.31 °. Is more preferable, and 0.21 ° to 0.31 ° is even more preferable. Further, the first surface 11 of the substrate 1 is not limited to the c surface, but may be, for example, an m surface, an a surface, an R surface, or the like. Further, the substrate 1 is not limited to the sapphire substrate, and may be, for example, a single crystal AlN substrate or the like.

Further, the n-type semiconductor layer 4 is not limited to a single-layer structure but may have a multi-layer structure. For example, the n-type semiconductor layer 4 may have a laminated structure of a plurality of n-type AlGaN layers having different Al composition ratios from each other. Further, the p-type AlGaN layer and the p-type GaN layer in the p-type semiconductor layer 6 are not limited to a single-layer structure, but may be a multilayer structure. For example, the p-type AlGaN layer may have a laminated structure of a plurality of p-type AlGaN layers having different Al composition ratios from each other. Further, the p-type GaN layer may have a laminated structure of a plurality of p-type GaN layers having different concentrations of p-type impurities.

Further, the active layer 5 is not limited to an example having a multiple quantum well structure, and may be, for example, a single quantum well structure or a single layer structure. Further, the material of the active layer 5 is not limited to AlGaN, and other nitride semiconductor materials may be used, for example, InAlGaN or the like. Further, the material of the active layer 5 may be a material other than the nitride semiconductor material.

Further, the usage example of the ultraviolet light emitting element 10 is not limited to the example in which the first functional unit 51 is used as a light emitting unit and the second functional unit 52 is operated as a light receiving unit. For example, in the ultraviolet light emitting element 10, both the first functional unit 51 and the second functional unit 52 may be operated as a light emitting unit, the second functional unit 52 may be a light emitting unit, and the first functional unit 51 may be a light receiving unit. It may be operated as.

Further, the plan view shape, layout, etc. of the first semiconductor unit 71, the second semiconductor unit 72, the first positive electrode 81, the second positive electrode 82, the first negative electrode 91, and the second negative electrode 92 are shown in the example of FIG. 1A. Not limited to this, it can be changed as appropriate.

Further, the number of each of the first positive electrode 81 and the first negative electrode 91 is not limited to one, and may be plural. Further, the number of the first positive electrodes 81 and the number of the first negative electrodes 91 may be different.

Further, the number of each of the second positive electrode 82 and the second negative electrode 92 is not limited to one, and may be plural. Further, the number of the second positive electrodes 82 and the number of the second negative electrodes 92 may be different.

Further, in the ultraviolet light emitting element 10, it is not necessary to reflect the ultraviolet rays from the active layer 5 on the second surface 12 of the substrate 1, so that, for example, the second surface 12 of the substrate 1 is made of a single layer or a multilayer dielectric film. An anti-reflection coat may be provided.

Further, in the ultraviolet light emitting element 10, the second surface 12 of the substrate 1 may be provided with a light extraction structure portion that suppresses reflection of the light radiated from the active layer 5 on the second surface 12. Examples of the light extraction structure portion include a concave-convex structure portion having a two-dimensional periodic structure. The concavo-convex structure portion is, for example, a configuration in which a plurality of quadrangular pyramid-shaped convex portions are arranged in a two-dimensional array. The period of the two-dimensional periodic structure may be appropriately determined according to the wavelength of the ultraviolet rays emitted by the active layer 5.

As is clear from the embodiments described above, the ultraviolet light emitting device (10) according to the first aspect includes a substrate (1) and a laminated body (2). The substrate (1) has a first surface (11) and a second surface (12) that are opposite to each other in the thickness direction (D1). The laminate (2) is provided on the first surface (11) of the substrate (1). In the laminate (2), the n-type semiconductor layer (4), the active layer (5), and the p-type semiconductor layer (6) are arranged in this order from the substrate (1) side. The laminated body (2) is formed on the surface (21) of the laminated body (2) opposite to the substrate (1), and has a laminated structure (7) of the active layer (5) and the p-type semiconductor layer (6). Has a groove (23) for separating the first semiconductor portion (71) and the second semiconductor portion (72). The area of the first semiconductor portion (71) is larger than the area of the second semiconductor portion (72). The ultraviolet light emitting element (10) further includes a first positive electrode (81), a second positive electrode (82), a first negative electrode (91), and a second negative electrode (92). The first positive electrode (81) is formed on the first semiconductor portion (71). The second positive electrode (82) is formed on the second semiconductor portion (72). The first negative electrode (91) is provided on the surface (41) of the n-type semiconductor layer (4) on the active layer (5) side, and is adjacent to the first positive electrode (81) when viewed from the thickness direction (D1). Fit. The second negative electrode (92) is provided on the surface (41) of the n-type semiconductor layer (4) on the active layer (5) side, and is adjacent to the second positive electrode (82) when viewed from the thickness direction (D1). Fit.

With the above configuration, the ultraviolet light emitting element (10) can monitor the light output while suppressing the decrease in the light output.

In the ultraviolet light emitting element (10) according to the second aspect, in the first aspect, the first functional part (51) which is a part forming a part of the first semiconductor part (71) in the active layer (5). The end faces (513, 523) facing each other with the second functional portion (52), which is a portion constituting a part of the second semiconductor portion (72), are parallel to each other. This makes it possible to improve the monitoring accuracy of the light output in the ultraviolet light emitting element (10).

In the ultraviolet light emitting device (10) according to the third aspect, in the first or second aspect, the size of the n-type semiconductor layer (4) as viewed from the thickness direction (D1) is the size of the substrate (1). It is the same. As a result, the ultraviolet light emitting element (10) can further suppress the decrease in light output.

In the ultraviolet light emitting element (10) according to the fourth aspect, in any one of the first to third aspects, the area of the first positive electrode (81) is larger than the area of the second positive electrode (82). The area of the first negative electrode (91) is larger than the area of the second negative electrode (92). As a result, the ultraviolet light emitting element (10) can further suppress the decrease in light output.

In the ultraviolet light emitting device (10) according to the fifth aspect, in the fourth aspect, the outer peripheral line of the first semiconductor portion (71) as viewed from the thickness direction (D1) is the outer peripheral line of the n-type semiconductor layer (4). It is bent along the line and so as to avoid the second semiconductor portion (72), the first negative electrode (91), and the second negative electrode (92). As a result, the ultraviolet light emitting element (10) can further suppress the decrease in light output.

1 Substrate 2 Laminated body 21 Surface 23 Groove 11 First surface 12 Second surface 4 n-type semiconductor layer 41 Surface 5 Active layer 51 First functional part 513 End surface 52 Second functional part 523 End surface 6 p-type semiconductor layer 7 Laminated structure 71 1st semiconductor part 72 2nd semiconductor part 81 1st positive electrode 82 2nd positive electrode 91 1st negative electrode 92 2nd negative electrode 10 Ultraviolet light emitting element D1 Thickness direction

Claims (3)

A substrate having a first surface and a second surface opposite to each other in the thickness direction,
A laminate provided on the first surface of the substrate, in which an n-type semiconductor layer, an active layer, and a p-type semiconductor layer are arranged in this order from the substrate side, is provided.
The laminate has a groove formed on the surface opposite to the substrate and separating the laminated structure of the active layer and the p-type semiconductor layer into a first semiconductor portion and a second semiconductor portion.
The area of the first semiconductor part is larger than the area of the second semiconductor part,
The first positive electrode formed on the first semiconductor portion and
The second positive electrode formed on the second semiconductor portion and
A first negative electrode provided on the surface of the n-type semiconductor layer on the active layer side and adjacent to the first positive electrode when viewed from the thickness direction,
A second negative electrode provided on the surface of the n-type semiconductor layer on the active layer side and adjacent to the second positive electrode when viewed from the thickness direction is further provided .
The size of the n-type semiconductor layer when viewed from the thickness direction is the same as the size of the substrate.
The first negative electrode, the first positive electrode, the second positive electrode, and the second negative electrode are arranged in this order in one direction orthogonal to the thickness direction when viewed from the thickness direction. ,
The outer peripheral line of the first semiconductor portion when viewed from the thickness direction is a portion along the outer peripheral line of the n-type semiconductor layer, a portion bent so as to avoid the first negative electrode, and the second portion. An ultraviolet light emitting element characterized by being composed of a semiconductor portion and a portion bent so as to avoid the second negative electrode. Of the active layer, the end faces of the first functional portion, which is a part constituting a part of the first semiconductor portion, and the second functional portion, which is a portion constituting a part of the second semiconductor portion, are opposed to each other. The ultraviolet light emitting element according to claim 1, wherein the ultraviolet light emitting elements are parallel to each other. The area of the first positive electrode is larger than the area of the second positive electrode,
The area of the first negative electrode is larger than the area of the second negative electrode.
The ultraviolet light emitting device according to claim 1 or 2.

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