JP6367590B2 - LIGHT EMITTING ELEMENT AND METHOD FOR MANUFACTURING LIGHT EMITTING ELEMENT STRUCTURE - Google Patents

Description

  The present invention relates to a light emitting device, and more particularly to a multiwavelength light emitting device that emits light of multiple wavelengths.

  A light emitting diode (LED) is configured by arranging an n-type layer, an active layer, and a p-type layer in this order. The light emitting efficiency of the LED can be improved by using a material having a larger band gap than the material for forming the active layer as the material for forming the n-type layer and the p-type layer.

When a group 13 nitride having a composition of In _x Al _y Ga _1-xy N is used for the active layer, the emission wavelength of the LED is changed by appropriately adjusting the composition (values of x and y). be able to.

  Furthermore, by providing the active layer so as to have a quantum well structure by stacking a well layer and a barrier layer having different compositions, the light output of the LED can be increased, and further, the quantum well structure By adopting a multiple quantum well structure (MQW) in which multiple layers are formed, the optical output can be further increased (see, for example, Patent Document 1).

  In addition, it is already known that a multi-wavelength light emitting element that emits light having different wavelengths can be manufactured by stacking a plurality of active layers having different compositions (see, for example, Patent Document 2 and Patent Document 3). In Patent Document 2, an active layer (short wavelength: blue) made of a material having a large band gap is formed on the light emission observation surface side (element upper surface side), thereby forming an active layer (long wavelength: material having a large band gap). An embodiment is disclosed in which light from red and intermediate wavelengths (green) is prevented from being absorbed. Patent Document 3 discloses a multi-wavelength light emitting device in which a plurality of multiple quantum well structures having different compositions of active layers are sequentially stacked so that light emission wavelengths from the respective multiple quantum well structures are different. Has been.

Japanese Patent No. 2917742 Japanese Patent No. 29120023 Japanese Patent No. 3543498

  The multi-wavelength light emitting element disclosed in Patent Document 2 includes active layers having different compositions one by one. Therefore, the light output of light emitted from each active layer (light emission at a light emission wavelength unique to each active layer) is not always sufficient.

  On the other hand, when the configuration disclosed in Patent Document 3 is adopted to increase the light output of the multi-wavelength light emitting element, the light output is increased, but the current applied to the element (energization current) is different. There is a problem in that the chromaticity of the output light varies depending on the energization current.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a multi-wavelength light-emitting element that does not cause a change in chromaticity due to a change in energization current and has high luminous efficiency.

The invention of claim 1 is a light-emitting element which emits light of a plurality of wavelengths, comprising an active layer group including a plurality of active layers composed of the each one well layer and one barrier layer, wherein In the active layer group, the thickness of the one well layer is 4 nm or less, and the plurality of active layers includes a plurality of first well layers including a first well layer made of a first group 13 nitride as the one well layer. a first active layer, and a plurality of second active layers comprises a second well layer comprising a second group 13 nitride having a composition different from said first group 13 nitride as the one of the well layer, of the one A plurality of third active layers each including a third well layer made of a third group 13 nitride having a composition different from that of the first and second group 13 nitrides as the well layer, by the said second active layer third active layer are periodically stacked, three or more of the one well When 3 or more of said and one barrier layer stacked _{alternately, In x1 Ga 1-x1 N} (0.20 ≦ x1 ≦ 0 where the first group 13 nitride to blue light and emitting wavelength. 30), and the second group 13 nitride has a composition of In _x2 Ga _1-x2 N (0.34 ≦ x2 ≦ 0.44) having an emission wavelength of green light. The group 13 nitride is a group 13 nitride having a composition of In _x3 Ga _1-x3 N (0.51 ≦ x3 ≦ 0.65) having a red light emission wavelength. It is characterized by that.

According to a second aspect of the invention, a light-emitting device according to claim 1, the total thickness of the first well layer included in the plurality of first active layer, the second well provided in the plurality of second active layers The total thickness of the layers and the total thickness of the third well layers provided in the plurality of third active layers are both 4 nm or more.

A third aspect of the present invention is the light emitting device according to the first or second aspect , wherein the active layer group includes the first active layer, the third active layer, the second active layer, and the third active layer. It is characterized by being formed by repeating stacking in the order of active layers.

The invention of claim 4 is a method of manufacturing a light emitting device structure capable of producing a light emitting device that emits light of a plurality of wavelengths, and an n type conductive layer forming step of epitaxially forming an n type conductive layer on a substrate; an active layer group forming step of epitaxially forming an active layer group including a plurality of active layers composed of said each on the n-type conductive layer in the one well layer and one barrier layer, the active layer group and a p-type conductive layer forming step of epitaxially forming a p-type conductive layer on top, in the active layer group forming step, the thickness of the one well layer with a 4nm or less, as the one of the well layer A first active layer comprising a first well layer made of a first group 13 nitride and a second group 13 nitride made of a second group 13 nitride having a composition different from that of the first group 13 nitride as the one well layer. a second active layer comprising a second well layer, the one well layer By periodically laminating a third active layer comprising a third well layer made of a third group 13 nitride having a composition different from that of the first and second group 13 nitrides, the activity A layer group is formed so that three or more of the one well layers and three or more of the one barrier layers are alternately stacked, and the first group 13 nitride is formed of In light having blue light emission wavelength. _A group 13 nitride having a composition of _x1 Ga _1-x1 N (0.20 ≦ x1 ≦ 0.30) is used, and the second group 13 nitride has an emission wavelength of In _x2 Ga _1-x2 N ( In _x3 Ga _1-x3 N (0.51 ≦ x3 ≦ 0), wherein the group 13 nitride has a composition of 0.34 ≦ x2 ≦ 0.44), and the third group 13 nitride has red light emission wavelength. .65) a group 13 nitride having a composition of

The invention according to claim 5 is the method for manufacturing the light emitting device structure according to claim 4 , wherein the light emitting device structure is provided in the total thickness of the first well layers provided in the plurality of first active layers and in the plurality of second active layers. The total thickness of the second well layer and the total thickness of the third well layers provided in the plurality of third active layers are both 4 nm or more.

The invention of claim 6 is a method for manufacturing a light emitting device structure according to claim 4 or claim 5 , wherein, in the active layer group formation step, the active layer group is defined as the first active layer, the first active layer. It is formed by repeating stacking in the order of three active layers, the second active layer, and the third active layer.

According to the first to sixth aspects of the invention, a multi-wavelength light emitting device is realized in which the chromaticity of the light emitted to the outside is kept constant regardless of the amount of energization.

In particular, according to the inventions of claims 2 and 5 , the multi-wavelength light-emitting element having excellent luminous efficiency while keeping the chromaticity of the light emitted to the outside constant regardless of the energization amount, Realized.

It is a figure which shows schematically the structure of the light emitting element 10 which concerns on 1st Embodiment. It is a figure which shows schematically the structure of the light emitting element 10 which concerns on 2nd Embodiment. It is a figure which shows schematically the structure of the light emitting element 10 which concerns on 3rd Embodiment. It is a figure showing the change of the chromaticity coordinate of the sample 9 of Example 1 in an xy chromaticity coordinate system. It is the figure which normalized the light emission intensity profile of the sample 9 of Example 1 by making the maximum value into a peak.

  The group numbers in the periodic table shown in this specification are based on the 1 to 18 group number designations according to the 1989 International Union of Pure Applied Chemistry (IUPAC) revised inorganic chemical nomenclature. , Group 13 refers to aluminum (Al), gallium (Ga), indium (In), and the like, and Group 15 refers to nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), and the like.

<First Embodiment>
<Outline of light emitting element>
FIG. 1 is a diagram schematically showing a configuration of a light-emitting element 10 according to the first embodiment of the present invention. The light-emitting element 10 is a multi-wavelength light-emitting element that has a so-called horizontal structure and emits a plurality of lights having different emission wavelengths.

  The light emitting element 10 includes an underlayer 2, an n-type conductive layer 3, an active layer group 4 formed by stacking a plurality of active layers, and a p-type conductive layer 5 in this order on one main surface of the substrate 1. It has a laminated structure formed adjacent to each other.

  Further, on the p-type conductive layer 5, an anode electrode portion 6 including an anode electrode layer 6 a and an anode electrode pad 6 b is provided. Further, a part of the n-type conductive layer 3 is exposed, and a cathode electrode 7 is provided on the exposed portion. The cathode electrode 7 is also referred to as a cathode electrode pad 7.

  The light emitting element 10 emits excitation light emitted by recombination of carriers in the active layer group 4 generated by applying a predetermined voltage between the cathode electrode pad 7 and the anode electrode pad 6b toward the outside of the element. It is.

  The substrate 1 is made of a single crystal base material such as sapphire, GaN, SiC, ZnO. Although there is no special restriction | limiting in the size of the board | substrate 1, From the point of the ease of handling, the thing of about several hundred micrometers-several mm thickness is suitable.

  A plurality of layers made of a predetermined group 13 nitride are sequentially epitaxially grown on such a substrate 1 by a known epitaxial growth method such as the MOCVD method, thereby forming each layer constituting the above-described stacked structure. .

  The underlayer 2 is a layer provided to improve the crystal quality of the n-type conductive layer 3, the active layer group 4, and the p-type conductive layer 5 that are epitaxially formed thereon. As the underlayer 2, it is a preferable example that a so-called low-temperature buffer layer made of GaN is provided in a thickness of about 10 nm to 50 nm.

The n-type conductive layer 3 is a layer made of GaN doped with an n-type dopant such as Si. The n-type conductive layer 3 is preferably formed to a thickness of about 2 μm to 5 μm. When Si is an n-type dopant, the Si atomic concentration in the n-type conductive layer 3 is preferably about 1 × 10 ¹⁸ / cm ³ to 1 × 10 ¹⁹ / cm ³ .

  The active layer group 4 is a portion formed by laminating a plurality of active layers responsible for light emission in the light emitting element 10. The active layer group 4 has a multiple quantum well (MQW) structure in which two or more well layers and two or more barrier layers are alternately (periodically) stacked. In the present embodiment, As shown in FIG. 1, the active layer group 4 includes a first active layer A composed of a first well layer 4a1 and a barrier layer 4b, and a second active layer B composed of a second well layer 4a2 and a barrier layer 4b. And the first well layer 4a1 and the second well layer 4a2 are formed of group 13 nitrides having different compositions. . Details of the active layer group 4 will be described later. In other words, in the light emitting element 10, the composition of the well layers existing in the adjacent active layers is different. It should be noted that the fact that the composition of adjacent well layers is different means that the emission wavelengths of light emitted from the respective active layers are different. Hereinafter, the first active layer A may be simply represented as A, and the second active layer B may be simply represented as B.

The p-type conductive layer 5 is a layer made of GaN doped with a p-type dopant such as Mg. The p-type conductive layer 5 is preferably formed to a thickness of about 100 nm to 300 nm. When Mg is a p-type dopant, the atomic concentration of Mg in the p-type conductive layer 5 is preferably about 1 × 10 ¹⁹ / cm ³ to 1 × 10 ²⁰ / cm ³ .

  The anode electrode layer 6 a is formed on the upper surface of the p-type conductive layer 5 so as to have translucency. The anode electrode layer 6a is a preferred example formed as a Ni / Au laminated film. The anode electrode pad 6b is preferably formed as a Ni / Au laminated film in a partial region of the upper surface of the anode electrode layer 6a. In such a case, the thicknesses of the Ni film and the Au film constituting the Ni / Au laminated film to be the anode electrode layer 6a are preferably about 5 nm to 10 nm and 10 nm to 30 nm, respectively, and constitute the anode electrode pad 6b. The thicknesses of the Ni film and the Au film constituting the Ni / Au laminated film are preferably about 5 nm to 10 nm and 50 nm to 200 nm, respectively.

  The cathode electrode 7 is preferably formed as a Ti / Al / Ni / Au multilayer film. The thicknesses of the Ti film, Al film, Ni film, and Au film constituting the multilayer film are preferably about 5 nm to 20 nm, 50 nm to 100 nm, 5 nm to 20 nm, and 50 nm to 200 nm, respectively.

<Details of active layer group>
As described above, the active layer group 4 included in the light emitting element 10 according to the present embodiment includes the first active layer A including the first well layer 4a1 and the barrier layer 4b, the second well layer 4a2, and the barrier layer 4b. It has the structure which laminated | stacked alternately the 2nd active layer B which consists of these. In other words, the active layer group 4 has a configuration in which the first well layer 4a1 and the second well layer 4a2 adjacent to each other with the barrier layer 4b interposed therebetween are formed of group 13 nitrides having different emission wavelengths. It has become a thing. Alternatively, if attention is paid only to the well layers, it can be said that in the active layer group 4, the first well layers 4a1 and the second well layers 4a2 are alternately arranged. The lowermost layer and the uppermost layer of the active layer group 4 are both barrier layers 4b.

  When the light emitting element 10 is energized by applying a predetermined voltage between the cathode electrode pad 7 and the anode electrode pad 6b from the active layer group 4 having such a configuration, the first well layer 4a1. And light emitted from the second well layer 4a2.

For example, the first well layer 4a1 is formed of a group 13 nitride having a composition of In _x1 Ga _1-x1 N (0.2 ≦ x1 ≦ 0.3), and the second well layer 4a2 is formed of In _x2 The active layer group 4 is formed of a group 13 nitride having a composition of Ga _1-x2 N (0.34 ≦ x2 ≦ 0.44), and the barrier layer 4b is formed of GaN. This is a preferred example. In this case, the first well layer 4a1 emits blue light having a wavelength of 435 nm to 480 nm, and the second well layer 4a2 emits green light having a wavelength of 500 nm to 560 nm. As a result, the active layer group 4 as a whole (and thus from the light emitting element 10) emits light obtained by combining the blue light and the green light.

  More specifically, the first well layer 4a1 and the second well layer 4a2 are each formed to a thickness of about 1 nm to 4 nm. When satisfying such requirements, the light emitting element 10 in which the chromaticity is kept constant regardless of the difference in the energization amount is realized. The barrier layer 4b is preferably formed to a thickness of about 5 nm to 15 nm.

  Furthermore, the first active layer A and the second active layer B are both the total thickness of the first well layer 4a1 in the first active layer A and the total thickness of the second well layer 4a2 in the second active layer B. It is formed to be 4 nm or more. When satisfying such requirements, the light-emitting element 10 in which the chromaticity is kept constant regardless of the amount of energization and the light emission efficiency is excellent is realized. In addition, these requirements mean that the light emitting element 10 having excellent light emission efficiency can be realized by increasing the number of stacked layers even when the first well layer 4a1 and the second well layer 4a2 are thin.

  Here, the chromaticity is kept constant regardless of the difference in the energization amount even if the energization amount to the light emitting element 10 is increased or decreased, the light emission from the first active layer A and the second active layer B. This means that the chromaticity of light emitted from the light emitting element 10 does not change depending on the amount of energization because the light intensity balance with the light emitted from the light source hardly changes.

  In general, when the energization amount is increased in a light emitting element, heat is generated, and carrier recombination is likely to occur in a region near the p-type layer of the active layer. The reason is that the lifetime of holes injected from the p-type layer side into the active layer is shortened by heating the light emitting element, and most of the holes recombine with electrons in the vicinity of the p-type layer of the active layer. It is thought to be because. Therefore, if the composition of the well layer constituting the active layer is different between the vicinity of the p-type layer and the vicinity of the n-type layer, and therefore when the emission wavelength is different, The light emission from the well layer existing in the vicinity of the light becomes dominant, and the chromaticity shift from the emitted light may occur when the energization amount is small (see FIGS. 4 and 5).

  On the other hand, in the light emitting element 10 according to the present embodiment, the p-type conductive layer is formed by alternately laminating the first active layer A and the second active layer B under the above-described requirements. The first active layer A and the second active layer B coexist not only in the vicinity of 5 but also in any region of the active layer group 4. Therefore, in the light emitting element 10, light emission in the first active layer A and light emission in the second active layer B occur equally in the active layer group 4. Thereby, in the light emitting element 10, even when the energization amount is large and carrier recombination is likely to occur in the vicinity of the p-type conductive layer 5, the light emission from the first active layer A and the second active layer B The light intensity balance with the light emission is kept the same as when the energization amount is small. That is, light emission with the same chromaticity as when the energization amount is small can be obtained.

  Although there is no particular limitation on the upper limit of the total thickness of the first well layer 4a1 and the second well layer 4a2, in practice, the saturation of the light output, the increase in the resistance value of the active layer, the increase in the formation time of the active layer, etc. From these viewpoints, the upper limit is preferably about 40 nm.

<Method for Manufacturing Light-Emitting Element>
Next, an example of a method for manufacturing the light-emitting element 10 according to this embodiment will be described. In the following, each layer made of a group 13 nitride is formed by the MOCVD method. In such a case, TMG (trimethylgallium) is used as the Ga source, TMI (trimethylindium) is used as the In source, ammonia gas is used as the N source, silane gas is used as the Si dopant source, and Mg dopant source is used. It is assumed that Cp ₂ Mg (biz (cyclopentadienyl) magnesium) gas is used. Note that the manufacturing method described below is merely an example, and the manufacturing method of the light-emitting element 10 is not necessarily limited thereto.

  First, a substrate 1 which is a single crystal base material having a thickness of about several hundred μm is prepared, and a GaN low-temperature buffer layer is formed thereon as a base layer 2 at a forming temperature of 500 ° C. to 600 ° C.

Subsequently, while doping Si with an atomic concentration of about 1 × 10 ¹⁸ / cm ³ to 1 × 10 ¹⁹ / cm ³ on the underlying layer 2 at a formation temperature of 1000 ° C. to 1100 ° C., n-type Conductive layer 3 is formed epitaxially.

  Subsequently, the active layer group 4 is formed on the n-type conductive layer 3 at a formation temperature of 650 ° C. to 800 ° C. Specifically, the formation of the first well layer 4a1 and the second well layer 4a2 made of a group 13 nitride each having a composition corresponding to a desired emission wavelength and the formation of the barrier layer 4b made of GaN are performed as barriers. It is performed by repeating the order of the layer 4b, the first well layer 4a1, the barrier layer 4b, the second well layer 4a2, the barrier layer 4b (...), the second well layer 4a1, and the barrier layer 4b.

Subsequently, on the active layer group 4, while doping Mg at an atomic concentration of about 1 × 10 ¹⁹ / cm ³ to 1 × 10 ²⁰ / cm ³ at a formation temperature of 950 ° C. to 1050 ° C., p A mold conductive layer 5 is formed.

  A part of the n-type conductive layer 3 is exposed to the laminated structure thus obtained by using a photolithography process and an RIE method.

  Subsequently, a Ti / Al / Ni / Au film to be the cathode electrode pad 7 is patterned to an appropriate thickness on the exposed portion of the n-type conductive layer 3 using a photolithography process and a vacuum deposition method. Thereafter, in order to improve the ohmic contact characteristics, a heat treatment at a temperature of 900 ° C. or higher in a nitrogen atmosphere, preferably a heat treatment at 1000 ° C. is preferably performed for several tens of seconds.

  Further, a Ni / Au film to be the anode electrode layer 6a is patterned on the upper surface of the p-type conductive layer 5 by using a photolithography process and a vacuum deposition method. Thereafter, a heat treatment at 600 ° C. in a nitrogen atmosphere is performed for several minutes in order to improve the ohmic contact characteristics.

  Further, a Ni / Au film to be the anode electrode pad 6b is patterned in a partial region on the upper surface of the anode electrode layer 6a by using a photolithography process and a vacuum deposition method.

  Through the above process, the light emitting element 10 is manufactured. The actual manufacturing process is performed by applying a multi-cavity method in which a single crystal base wafer is used as the substrate 1 in a so-called mother substrate state, so that a large number of light-emitting elements 10 are simultaneously manufactured. Is preferred. That is, after the formation of each layer and the formation of the electrode pattern in which the unit pattern forms the electrode of each element on the single crystal substrate wafer by the above-mentioned procedure, the wafer is subjected to a predetermined element size by a dicer or the like. By dividing into individual pieces (chips), a large number of light emitting elements 10 can be obtained.

  As described above, according to the present embodiment, a plurality of active layers composed of two or more well layers and two or more barrier layers are stacked between the n-type conductive layer and the p-type conductive layer. In a light emitting device having a multiple quantum well structure (active layer group), the thickness of each well layer is 4 nm or less, and the active layers are cycled so that the compositions of the well layers existing in adjacent active layers are different. Therefore, the chromaticity of the combined light of the light emitted from the first active layer and the light emitted from the second active layer, which is emitted from the light emitting element to the outside, does not depend on the energization amount. A light-emitting element kept constant is realized.

  In particular, by setting the total thickness of the well layers in each active layer to 4 nm or more, the color of the combined light of the light emitted from the first active layer and the light emitted from the second active layer emitted from the light emitting element The light-emitting element is maintained at a constant level regardless of the amount of energization and is excellent in luminous efficiency.

<Second Embodiment>
FIG. 2 is a diagram schematically showing a configuration of a light emitting device 110 according to the second embodiment of the present invention. The light emitting element 110 is a multi-wavelength light emitting element that has a so-called vertical structure and emits a plurality of lights having different emission wavelengths.

  The light emitting element 110 according to the present embodiment includes an n-type conductive layer 103, an active layer group 104 formed by stacking a plurality of active layers, and a p-type conductive layer 105 on one main surface of a substrate 101. It has a laminated structure formed adjacently in order.

  Further, an anode reflective electrode 106 is provided on the p-type conductive layer 5. A comb-like cathode electrode 107 is provided on the main surface of the substrate 1 opposite to the surface on which the n-type conductive layer 103, the active layer group 104, and the p-type conductive layer 105 are formed. .

  In the light emitting element 110, excitation light emitted by recombination of carriers in the active layer group 104 generated by applying a predetermined voltage between the cathode electrode 107 and the anode reflective electrode 106 is directed toward the outside of the element, in particular, active. The light is emitted in a direction from the layer group 104 toward the side where the cathode electrode 107 is provided.

  The substrate 101 is preferably made of a single crystal base material made of a material that does not substantially have the ability to absorb light emitted from the active layer group 104. For example, a GaN free-standing substrate is a suitable example. Although there is no special restriction | limiting in the size of the board | substrate 1, From the point of the ease of handling, the thing of about several hundred micrometers-several mm thickness is suitable.

  A plurality of layers made of a predetermined group 13 nitride are sequentially epitaxially grown on such a substrate 101 by a known epitaxial growth method such as the MOCVD method, thereby forming each layer constituting the above laminated structure. .

  The detailed configuration and formation mode of the n-type conductive layer 103, the active layer group 104, and the p-type conductive layer 105 (the composition and thickness of each layer, the repeated pattern of lamination, etc.) are related to the first embodiment. The formation mode of the n-type conductive layer 3, the active layer group 4, and the p-type conductive layer 5 of the light emitting element 10 is the same. Therefore, detailed description is omitted. Schematically speaking, the configuration of the active layer group 104 is that the first well layer 104a1 and the barrier layer 104b constitute the first active layer A, and the second well layer 104a2 and the barrier layer 104b constitute the second active layer B. The lowermost layer and the uppermost layer constitute a barrier layer 104b.

  In addition, the anode reflective electrode 106 is preferably formed of an Ag film with a thickness of about 100 nm to 200 nm. The cathode electrode 107 is a Ti / Al / Ni / Au multilayer film, and the Ti film, Al film, Ni film, and Au film constituting the multilayer film are 5 nm to 20 nm, 50 nm to 100 nm, and 5 nm to 20 nm, respectively. It is a suitable example that it is formed to a thickness of about 50 nm to 200 nm. The anode reflection electrode 106 and the cathode electrode 107 can be formed by using a known photolithography process and a vacuum deposition method. Further, an appropriate heat treatment or the like may be performed according to the method of forming each electrode.

  The light emitting element 110 having the above-described configuration is the same as the light emitting element 10 according to the first embodiment, in which the first well layer composition is different between the n-type conductive layer 103 and the p-type conductive layer 105. The active layer A and the second active layer B are alternately stacked. Therefore, the chromaticity of the combined light of the light emitted from the first active layer A and the light emitted from the second active layer B emitted from the light emitting device 110 is kept constant regardless of the amount of current flow. In addition, excellent luminous efficiency is realized.

  As described above, according to the present embodiment, as in the first embodiment, the chromaticity of the light emitted to the outside is kept constant regardless of the energization amount, and the luminous efficiency is improved. An excellent light emitting element is realized.

<Third Embodiment>
FIG. 3 is a diagram schematically showing a configuration of a light emitting device 210 according to the third embodiment of the present invention. The light-emitting element 210 is a multi-wavelength light-emitting element that has a so-called horizontal structure and emits a plurality of lights having different emission wavelengths, like the light-emitting element 10 according to the first embodiment. The configuration is different from that of the light emitting device 10 according to the first embodiment.

  Specifically, as shown in FIG. 3, the active layer of the light emitting device 210 according to the present embodiment includes a first active layer A composed of a first well layer 4a1 and a barrier layer 4b, and a second well layer 4a2. And a second active layer B composed of the barrier layer 4b, and a third active layer C composed of the third well layer 4a3 and the barrier layer 4b, which are repeatedly stacked in this order. That is, the three active layers are periodically stacked, and the compositions of the well layers existing in adjacent active layers are different. In other words, active layers having the same composition of the well layer are not adjacent to each other. Alternatively, focusing only on the well layer, in the active layer group 4, it can be said that the first well layer 4a1, the second well layer 4a2, and the third well layer 4a3 having different compositions are repeatedly arranged in this order. The lowermost layer and the uppermost layer of the active layer group 4 are both barrier layers 4b. In the following description, the first active layer A may be simply expressed as A, the second active layer B may be simply expressed as B, and the third active layer C may be simply expressed as C.

  From the entire active layer group 4 having such a configuration, light emitted from the first well layer 4a1, light emitted from the second well layer 4a2, and light emitted from the third well layer 4a3, which have different wavelengths from each other, The synthesized light is emitted.

For example, the first well layer 4a1 is formed of a group 13 nitride having a composition of In _x1 Ga _1-x1 N (0.20 ≦ x1 ≦ 0.30), and the second well layer 4a2 is formed of In _x2 The third well layer 4a3 is formed of a group 13 nitride having a composition of Ga _1-x2 N (0.34 ≦ x2 ≦ 0.44), and the third well layer 4a3 is formed of In _x3 Ga _1-x3 N (0.51 ≦ x3). A preferred example of the active layer group 4 is formed of a group 13 nitride having a composition of ≦ 0.65), and the barrier layer 4b is formed of GaN. In this case, the first well layer 4a1 emits blue light having a wavelength of 435 nm to 480 nm, and the second well layer 4a2 emits green light having a wavelength of 500 nm to 560 nm. In the third well layer 4a3, red light having a wavelength of 610 nm or more and 750 nm or less emits light. As a result, white light in which the blue light, the green light, and the red light are combined is emitted from the entire active layer group 4 (and hence from the light emitting element 210).

  More specifically, the first well layer 4a1, the second well layer 4a2, and the third well layer 4a3 are each formed to a thickness of about 1 nm to 4 nm. When satisfying such requirements, the light emitting element 210 in which the chromaticity is kept constant regardless of the difference in the energization amount is realized. The barrier layer 4b is preferably formed to a thickness of about 5 nm to 15 nm.

  Furthermore, the first active layer A, the second active layer B, and the third active layer C are composed of the total thickness of the first well layer 4a1 in the first active layer A and the second well layer 4a2 in the second active layer B. Both the total thickness and the total thickness of the third well layer 4a3 in the third active layer C are 4 nm or more. When satisfying such requirements, the light emitting element 210 is realized that has a constant chromaticity regardless of the amount of energization and has excellent light emission efficiency. In addition, these requirements are that even when the thicknesses of the first well layer 4a1, the second well layer 4a2, and the third well layer 4a3 are thin, the light emitting element 210 having excellent luminous efficiency can be realized by increasing the number of stacked layers. Means.

  Specifically, in the light emitting device 210 according to the present embodiment, the first active layer A and the second active layer B are laminated with the third active layer C in this order under the above-described requirements. In this case, the first active layer A, the second active layer B, and the third active layer C coexist not only in the vicinity of the p-type conductive layer 5 but also in any region of the active layer group 4. In such a case, in the light emitting element 210, light emission in the first active layer A, light emission in the second active layer B, and light emission in the third active layer C occur evenly in the active layer group 4. Thereby, in the light emitting element 210, even when the energization amount is large and the carrier recombination is likely to occur in the vicinity of the p-type conductive layer 5, the light emission from the first active layer A and the second active layer B The light intensity balance between the light emission and the light emission from the third active layer C is kept the same as when the energization amount is small. That is, light emission with the same chromaticity as when the energization amount is small can be obtained.

  From the viewpoint of further balancing the blue light, green light, and red light in the white light, instead of the configuration of the active layer group 4 shown in FIG. 3, the first active layer A and the second active layer B More preferably, the active layer group 4 is formed by stacking the third active layer C in the order of ACBCACBC. This is because the intensity of red light tends to be relatively weaker than that of blue light and green light, and the intensity of red light is increased by increasing the arrangement frequency of the third active layer C. Thus, white light with a better balance of the three colors can be obtained. Also in such a case, the stacking mode of the three active layers is periodic, and the composition of the well layers existing in the adjacent active layers is different.

  The light emitting element 210 is manufactured by forming a first well layer 4a1, a second well layer 4a2, and a third well layer 4a made of a group 13 nitride each having a composition corresponding to a desired emission wavelength in forming the active layer group 4. And the formation of the barrier layer 4b made of GaN are divided into the barrier layer 4b, the first well layer 4a1, the barrier layer 4b, the second well layer 4a2, the barrier layer 4b, the third well layer 4a3, the barrier layer 4b,. (Omitted) ··· Other than repeating the third well layer 4a3 and the barrier layer 4b in this order, the same procedure and conditions as those of the light emitting device 10 according to the first embodiment are possible.

  The upper limit of the total thickness of the first well layer 4a1, the second well layer 4a2, and the third well layer 4a3 is not particularly limited, but in practice, the saturation of the optical output and the increase of the resistance value of the active layer In view of increasing the formation time of the active layer and the like, the upper limit thereof is preferably about 40 nm.

  As described above, according to the present embodiment, even when three types of active layers having different emission wavelengths are provided, the composition of the well layers existing in the adjacent active layers as in the first embodiment. By periodically laminating the active layers so that they are different from each other, and by setting the thickness of each well layer to 4 nm or less, the chromaticity of the light emitted to the outside becomes constant regardless of the amount of current flow A light-emitting element that is maintained and has excellent luminous efficiency is realized.

  In particular, by setting the total thickness of the well layers in each active layer to 4 nm or more, a light emitting element that maintains chromaticity even when the amount of energization changes and has excellent light emission efficiency is realized.

Example 1
In the present embodiment, although the active layer group 4 is common in that it includes the first active layer A and the second active layer B, the thickness of the well layer provided in each of them and the repeated pattern of the stacking are different from each other in all 18 types. The light emitting elements (Sample 1 to Sample 18) were prepared, and the change in chromaticity depending on the amount of energization and the evaluation of the luminous efficiency were performed.

  In any sample preparation, a sapphire substrate having a diameter of 2 inches and a thickness of 430 μm is prepared as a mother substrate to be the substrate 1, and the underlayer 2, the n-type conductive layer 3, the active layer group 4, p are formed by MOCVD. A group 13 nitride crystal layer to be the type conductive layer 5 was sequentially epitaxially formed.

Specifically, first, a sapphire substrate is placed on a susceptor in an MOCVD apparatus, and then the sapphire substrate is heated and heated to a substrate temperature of 530 ° C., and a GaN layer (GaN low-temperature buffer layer) serving as the base layer 2 ) To a thickness of 40 nm. Next, the n-GaN layer that becomes the n-type conductive layer 3 is grown by growing the GaN layer while doping Si so that the substrate temperature is 1050 ° C. and the Si atom concentration is 5 × 10 ¹⁸ / cm ^3. It was formed to a thickness of 3 μm.

Subsequently, the substrate temperature was set to 750 ° C., and a plurality of group 13 nitride layers constituting the active layer group 4 were formed. In such a case, the crystal layer that becomes the first well layer 4a1 is formed of In _0.25 Ga _0.75 N that emits blue light, and the crystal layer that becomes the second well layer 4a2 emits green light. _{It is} formed of _0.4 Ga _0.6 N, the crystal layer that becomes the barrier layer 4b is formed of GaN, the thickness of the GaN layer that becomes the barrier layer 4b is 10 nm, and the lowermost layer and the uppermost layer And the barrier layer 4b are common to all samples.

  On the other hand, for Sample 1 to Sample 8, the thicknesses of the first well layer 4a1 and the second well layer 4a2 are constant at 2 nm except for the sample 3, and the first active layer A and the second active layer B are made constant. The number of repetitions when alternately laminating was different for each.

  Specifically, in Sample 1, the first active layer A and the second active layer B were formed once in this order. Hereinafter, the configuration in which the first active layer A and the second active layer B are stacked alternately and in pairs is the formation pattern of the first active layer A and the second active layer B in the active layer group 4 (see FIG. The repetition pattern) may be expressed as AB × k using the number k of the pair (k is a natural number) or may be distinguished using only the value of k. Sample 1 corresponds to the case of AB × 1 where k = 1.

  Samples 2 and 3 have an ABA structure in which only the first active layer A is formed twice. The difference between Sample 2 and Sample 3 is that the thickness of the first well layer 4a1 provided in the first active layer A is 1 nm for the former and 2 nm for the latter.

  Furthermore, samples 4 to 8 were formed with patterns so that k = 2, 4, 6, 10, and 14, respectively. The thicknesses of the first well layer 4a1 and the second well layer 4a2 were all constant at 2 nm.

  For sample 9, active layer group 4 was formed with a configuration of AAAABBBB, in which only A was stacked four times and then only B was stacked four times.

  In Samples 10 to 14, while k = 4, the thicknesses of the first well layer 4a1 and the second well layer 4a2 were 0.5 nm, 1 nm, 4 nm, 6 nm, and 8 nm, respectively.

  Further, for samples 15 to 18, the first well layer 4 a 1 existing in the active layer group 4 is different from the thickness of the first well layer 4 a 1 and the second well layer 4 a 2 and the value of the number k of AB pairs. The total thickness of the second well layer 4a2 was made constant at 8 nm. Specifically, the thicknesses of the first well layer 4a1 and the second well layer 4a2 are set to 0.5 nm, 1 nm, 4 nm, and 8 nm in order from the sample 14, respectively, while the value of the number k of pairs is 16, 8, 2 in order. 1.

Subsequent to the formation of the plurality of group 13 nitride layer groups as the active layer group 4 in the above-described manner, the substrate temperature is set to 950 ° C., and the Mg atom concentration is set to 1 × 10 ¹⁹ / cm ^3. A p-GaN layer to be the p-type conductive layer 5 was formed to a thickness of 200 nm by growing the GaN layer while doping Mg.

  Thereafter, the obtained laminated structure was taken out from the MOCVD apparatus, and subjected to a heat treatment at 800 ° C. for 10 minutes in a nitrogen atmosphere as an activation treatment of Mg ions in the p-GaN layer.

  Next, the formation part of the cathode electrode 7 was exposed about n-GaN used as the n-type conductive layer 3 using the photolithographic process and RIE method.

  Subsequently, a Ti / Al / Ni / Au multilayer film serving as the cathode electrode 7 was patterned on the exposed portion of the n-GaN layer using a photolithography process and a vacuum deposition method. The thickness of each metal film was set to 15 nm, 70 nm, 12 nm, and 60 nm in this order. Thereafter, in order to improve the ohmic contact characteristics of the cathode electrode 7, a heat treatment at 700 ° C. in a nitrogen atmosphere was performed for 30 seconds.

  Furthermore, the Ni / Au laminated film was patterned as the translucent anode electrode layer 6a on the p-GaN layer to be the p-type conductive layer 5 by using a photolithography process and a vacuum deposition method. The thickness of each metal film was 6 nm and 12 nm in this order. Thereafter, in order to improve the ohmic contact characteristics of the anode electrode layer 6a, a heat treatment at 500 ° C. was performed for 30 seconds in a nitrogen atmosphere.

  Subsequently, a Ni / Au laminated film to be the anode electrode pad 6b was patterned in a partial region on the upper surface of the anode electrode layer 6a by using a photolithography process and a vacuum deposition method. The thickness of each metal film was 5 nm and 60 nm in this order.

  Finally, the laminated structure was cut into chips. Thus, the light emitting element 10 was obtained.

About the obtained light emitting elements of Samples 1 to 18, the chromaticity (coordinate value in the xy chromaticity coordinate system) of light emitted from the element to the outside by energizing between the anode electrode pad 6b and the cathode electrode pad 7 is determined. It was measured. The energization amount was set at two levels of 10 mA and 100 mA. The chromaticity coordinates (x, y) at the respective energization amounts are represented as (x1, y1) and (x2, y2). Note that only the sample 9 was further measured for 50 mA. Chromaticity was measured with a color illuminometer. Further, from the values of the two chromaticity coordinates (x1, y1) and (x2, y2) obtained by the chromaticity measurement, a distance d = {(x2−x1) ² + (y2−y1) ² between the two coordinates. } ^1/2 was calculated, and this was taken as the amount of chromaticity change when the energization amount changed from 10 mA to 100 mA.

  Furthermore, it measured about the luminous efficiency at the time of 100 mA electricity supply. The luminous efficiency was calculated by dividing the light output measured with a photodiode by the power consumption.

  For each sample, the thickness of the well layer, the repeating pattern of the first active layer A and the second active layer B, the total thickness of the well layer for each active layer, the chromaticity coordinates (x1, y1), ( Table 1 shows x2, y2), the chromaticity change d, and the luminous efficiency when 100 mA is energized. The luminous efficiency is shown normalized by setting the value of Sample 1 to 1.00.

  First, regarding the change in chromaticity due to the difference in energization amount, the thicknesses of the first well layer 4a1 and the second well layer 4a2 and the number of stacked first active layers A and B are the same (hence the first When the sample 5 and the sample 9 in which the stacking order of the first active layer A and the second active layer B are different from each other in the total thickness of the well layer 4a1 and the total thickness of the second well layer 4a2), the luminous efficiency is almost equal. Although the degree was the same, the chromaticity was not changed in the sample 5, while the chromaticity was greatly changed in the sample 9. FIG. 4 is a diagram illustrating a change in the chromaticity coordinates of the sample 9 in the xy chromaticity coordinate system. FIG. 5 is a diagram in which the emission intensity profile of the sample 9 is normalized with the maximum value as a peak.

  As shown in FIG. 4, with respect to the sample 9, when the energization amount was increased, a change in chromaticity such that the green color became stronger was generated.

  Further, as shown in FIG. 5, the emission intensity profile of the sample 9 showed that the peak near the wavelength of 465 nm and the peak near the wavelength of 520 nm showed the same intensity when the energization amount was 10 mA. As the amount increased to 50 mA and 100 mA, the former peak relatively decreased. Since the former peak corresponds to light emission from the first active layer A, considering the change in chromaticity coordinates shown in Table 1 and FIG. When the active layer group 4 is configured by providing A at a position farther from the p-type conductive layer 5 than the second active layer B, light emission at a position closer to the p-type conductive layer 5 as the energization amount increases. Means that will be relatively dominant.

  In sample 5, unlike the sample 9, the chromaticity coordinate did not change because the first active layer A and the second active layer B having different compositions of the well layers included therein were alternately stacked. It can be said that the first active layer A is also arranged in the vicinity of the type conductive layer 5.

  In addition, regarding Sample 1 to Sample 8, which are common in that the first active layer A and the second active layer B are alternately stacked, but the number of stacked layers of the first active layer A and the second active layer B is different. No change in chromaticity occurred due to the difference in the amount of electricity applied to the sample. This is understood that the effect that the 1st active layer A was arrange | positioned also in the vicinity of the p-type conductive layer 5 not only in the sample 5 but in all of the samples 1-8.

  Further, when the sample 5 and the samples 10 to 14 in which the values of k are both 4 and the thicknesses of the first well layer 4a1 and the second well layer 4a2 are different are compared, the first well layer 4a1 and the second well layer 4a1 In the sample 5 and the samples 10 to 12 in which the thickness of the well layer 4a2 is 4 nm or less, no change in chromaticity due to the difference in the energization amount occurred. On the other hand, in samples 13 and 14 having a thickness of 6 nm or more, the chromaticity changed. In such a case, the tendency of the chromaticity change (the tendency of the chromaticity change in the xy chromaticity coordinate system) by increasing the energization amount in these samples 13 and 14 was almost the same as that of the sample 9. .

  Further, the total thickness of the first well layer 4a1 and the total thickness of the second well layer 4a2 are set while the thicknesses of the first well layer 4a1 and the second well layer 4a2 are different from the value of the number k of AB pairs. When the sample 5 having a thickness of 8 nm and the samples 15 to 18 are compared, in the sample 5 and the samples 15 to 17 in which the thicknesses of the first well layer 4a1 and the second well layer 4a2 are 4 nm or less, the color due to the difference in energization amount Although the degree of change did not occur, the chromaticity changed in Sample 18 having a thickness of 8 nm.

  From the above results, it was confirmed that the chromaticity was kept constant regardless of the amount of energization only in the samples in which the thicknesses of the first well layer 4a1 and the second well layer 4a2 were 4 nm or less.

  Note that the chromaticity change occurred in Sample 13, Sample 14, and Sample 18 when the thickness of the second well layer 4a2 closest to the p-type conductive layer 5 is large, and when light is recombined in the layer when 100 mA is applied. This is considered to be because light emission from the second active layer B is relatively stronger than light emission from the first active layer A.

  Next, regarding the luminous efficiency, there was a difference between Sample 1 and Sample 3 to Sample 8 in which the thickness of the well layers was all 2 nm. Specifically, the luminous efficiency of the sample 1 in which the number k of pairs of the first active layer A and the second active layer B is 1 is the lowest, and by setting k to 2 or more, the total thickness of the first well layer 4a1. In Sample 4 to Sample 8, in which the total thickness of each of the second well layer 4a2 is 4 nm or more, high luminous efficiency twice or more that of Sample 1 was realized. The realization of such high luminous efficiency is understood to be an effect of adopting a multiple quantum well structure. In particular, when k is 4 to 6, high luminous efficiency that is three times or more that of sample 1 was realized.

  In addition, when the value of k is larger than 4, the light emission efficiency tends to decrease. This is because the number of stacked layers of the first active layer A and the second active layer B is increased to increase the region of light emission recombination. It is considered that this is because the resistance component increases due to saturation and an increase in the total thickness of the active layer group 4.

  The luminous efficiencies of Sample 5 and Sample 10 to Sample 14 in which the values of k are the same and the thicknesses of the first well layer 4a1 and the second well layer 4a2 are different are the total of the first well layer 4a1 and the second well layer 4a2. Except for the sample 10 having a thickness of 2 nm, the thickness was about twice that of the sample 1 or more. Further, all the luminous efficiencies of Sample 5 and Sample 15 to Sample 18 in which the total thickness of the well layers of each active layer is the same 8 nm while the thickness of the well layer and the number k of AB pairs are different are all. , Greater than twice that of sample 1.

  However, the value was maximum in the sample 5 in which the thicknesses of the first well layer 4a1 and the second well layer 4a2 were 2 nm. This is because, as the thicknesses of the first well layer 4a1 and the second well layer 4a2 are increased, the total thickness of each of the first well layer 4a1 and the second well layer 4a2 is increased. If it becomes too much, it is thought that the reason is that the decrease in crystallinity due to lattice mismatch between the first well layer 4a1 and second well layer 4a2 made of InGaN and the barrier layer 4b made of GaN becomes remarkable. This indicates that the optimum film thickness for carrier confinement was 2 nm.

  As a result of the above samples 1 to 18, a plurality of active layers each composed of a well layer and a barrier layer are stacked so that two or more well layers and two or more barrier layers are alternately arranged. Thus, in a light emitting device having a multiple quantum well structure, the requirement that the active layers be periodically stacked so that the composition of the well layers existing in the adjacent active layers is different, and each well When the requirement that the thickness of each layer is 4 nm or less is observed, it is shown that a light-emitting element that can maintain chromaticity even when the amount of energization is changed is obtained, and the total number of well layers in each active layer When the requirement that the thickness is 4 nm or more is observed, it indicates that a light-emitting element that maintains chromaticity and has excellent light emission efficiency can be obtained even when the amount of energization changes.

(Example 2)
In this example, the vertical light emitting element 110 according to the second embodiment was manufactured.

  Specifically, a GaN free-standing substrate having a diameter of 2 inches and a thickness of 400 μm is prepared as the substrate 101, and the n-type conductive layer 103, the active layer group 104, and the p-type conductive layer 105 are implemented by MOCVD. It was produced under the same conditions as Sample 5 of Example 1.

  Further, a Ti / Al / Ni / Au multilayer film serving as the cathode electrode 107 is formed on the opposite surface side of the substrate 101 (the surface on which the crystal growth by the MOCVD method is not performed) using a photolithography process and a vacuum deposition method. Was patterned in a comb shape. The thickness of each metal film was set to 15 nm, 70 nm, 12 nm, and 60 nm in this order. Thereafter, in order to improve the ohmic contact characteristics of the cathode electrode 7, a heat treatment at 700 ° C. in a nitrogen atmosphere was performed for 30 seconds.

  Further, an Ag electrode as the anode reflective electrode 106 was formed to a thickness of 200 nm on the p-GaN layer to be the p-type conductive layer 5 by using a photolithography process and a vacuum evaporation method.

  Finally, the obtained laminated structure was cut into chips. Thus, the light emitting element 110 was obtained.

  For the obtained light-emitting element 110, chromaticity was measured in the same manner as in Example 1. As a result, the chromaticity coordinates (x1, y1) at the time of 10 mA energization and the chromaticity coordinates (x2, y2) at the time of 100 mA energization were both (0.14, 0.34). Naturally, the value of the chromaticity change d was 0. That is, in the light emitting element 101, the chromaticity did not change even when the energization amount was changed.

  Further, the luminous efficiency at 100 mA energization was measured in the same manner as in Example 1. As a result, the value of Sample 1 normalized to 1.00 was 3.76. That is, higher luminous efficiency than any sample of Example 1 was obtained. This is because the light-emitting element of Example 2 using a GaN free-standing substrate was formed using a heterogeneous substrate having a composition and structure different from those of an n-type conductive layer, an active layer, and a p-type conductive layer called a sapphire substrate. This is thought to be because lattice defects are reduced compared to

(Example 3)
In this embodiment, although the active layer group 4 is common in that the first active layer A, the second active layer B, and the third active layer C are included, the thickness of the well layer provided in each of them and the repeated pattern of the stacking are as follows. Four different types of light-emitting elements (Sample 19 to Sample 22) were produced, and the change in chromaticity depending on the amount of energization and the evaluation of luminous efficiency were performed. Components other than the active layer group 4 were formed in the same procedure as in Example 1.

As in the first embodiment, the active layer group 4 is formed by forming a plurality of group 13 nitrides constituting the active layer group 4 at a substrate temperature of 750 ° C. following the formation of the n-GaN layer to be the n-type conductive layer 3. In this case, the crystal layer to be the first well layer 4a1 is formed of In _0.25 Ga _0.75 N that emits blue light, and the second well layer 4a2 is formed. The crystal layer to be formed is In _0.4 Ga _0.6 N that emits green light, and the crystal layer that is to be the third well layer 4a3 is formed from In _0.55 Ga _0.45 N that emits red light. And forming a crystal layer to be the barrier layer 4b with GaN, a point to make all the well layers have a thickness of 2 nm, a point to make the thickness of the GaN layer to be the barrier layer 4b 10 nm, and the bottom layer The point that the top layer is the barrier layer 4b is common to all samples. .

  On the other hand, for the sample 19, the first active layer A, the second active layer B, and the third active layer C were formed only once in this order. For the sample 20, the formation of the first active layer A, the second active layer B, and the third active layer C in this order was repeated three times.

  For sample 21, active layer group 4 was formed in a configuration of AAABBCCC in which only A was stacked three times, then only B was stacked three times, and only C was stacked three times.

  Finally, for the sample 22, the active layer group 4 was formed with a configuration of ACBCACBCCABC.

  With respect to the obtained light emitting elements of Samples 19 to 22, the chromaticity and the luminous efficiency were measured in the same manner as in Example 1.

  For each sample, the repeating pattern of the first active layer A, the second active layer B, and the third active layer C, the total thickness of the well layer for each active layer, the chromaticity coordinates (x1, y1), ( Table 2 shows x2, y2), the chromaticity change d, and the luminous efficiency when 100 mA is applied. The luminous efficiency is shown normalized by setting the value of the sample 19 to 1.00.

  As shown in Table 2, in Sample 20 and Sample 22, no change in chromaticity due to the difference in the amount of energization occurred, and a high luminous efficiency of twice or more that of Sample 19 was realized. On the other hand, in the case of the sample 21 in which the same active layer was continuously laminated as in the case of the sample 9, high luminescence efficiency was obtained in the same manner, but the chromaticity changed depending on the energization amount.

  In both sample 20 and sample 22, the active layers are periodically stacked so that the compositions of the well layers existing in the adjacent active layers are different, and the thickness of each well layer is 4 nm or less, respectively. The requirement that the total thickness of the well layers in each active layer be 4 nm or more is satisfied. This means that even when three types of active layers having different emission wavelengths are provided, by satisfying these requirements, the chromaticity is maintained even when the energization amount is changed, and the luminous efficiency is excellent. It indicates that a light emitting element is obtained.

  When the chromaticity coordinates of the sample 20 and the sample 22 were compared, the chromaticity coordinate of the sample 22 was closer to the point E in FIG. 4 representing white. This means that the sample 22 produces white light emission in which blue, green, and red are more balanced.

DESCRIPTION OF SYMBOLS 1,101 Substrate 2 Underlayer 3, 103 n-type conductive layer 4, 104 active layer group 4a1, 104a1 first well layer 4a2, 104a2 second well layer 4a3 third well layer 4b, 104b barrier layer 5, 105 p-type conductivity Layer 6 Anode electrode portion 6a Anode electrode layer 6b Anode electrode pad 7, 107 Cathode electrode 10, 110, 210 Light emitting element 106 Anode reflective electrode A First active layer B Second active layer C Third active layer

Claims (6)

A light emitting device that emits light of a plurality of wavelengths,
Each comprising an active layer group including a plurality of active layers composed of the first well layer and one barrier layer,
In the active layer group,
The thickness of the one well layer is 4 nm or less;
Wherein the plurality of active layers, and a plurality of first active layer comprising a first well layer comprising a first group 13 nitride as the one of the well layer, the first group 13 nitride as the one of the well layer of different composition than the second group 13 and a plurality of second active layers comprises a second well layer of a nitride, said first and second group 13 nitride as the one well layer having a composition different from the A plurality of third active layers comprising a third well layer made of a third group 13 nitride,
Since the first active layer, the second active layer, and the third active layer are periodically stacked, three or more of the one well layers and three or more of the one barrier layers are alternately arranged. Laminated,
The first group 13 nitride is a group 13 nitride having a composition of In _x1 Ga _1-x1 N (0.20 ≦ x1 ≦ 0.30) having a blue light emission wavelength;
The second group 13 nitride is a group 13 nitride having a composition of In _x2 Ga _1-x2 N (0.34 ≦ x2 ≦ 0.44) having an emission wavelength of green light,
The third group 13 nitride is a group 13 nitride having a composition of In _x3 Ga _1-x3 N (0.51 ≦ x3 ≦ 0.65) having an emission wavelength of red light.
A light emitting element characterized by the above. The light emitting device according to claim 1 ,
The total thickness of the first well layer provided in the plurality of first active layers, the total thickness of the second well layer provided in the plurality of second active layers, and the third thickness provided in the plurality of third active layers. The total thickness of the well layers is 4 nm or more,
A light emitting element characterized by the above. The light-emitting device according to claim 1 or 2 ,
The active layer group is configured by repeating stacking in the order of the first active layer, the third active layer, the second active layer, and the third active layer.
A light emitting element characterized by the above. A method of manufacturing a light emitting element structure capable of producing a light emitting element that emits light of a plurality of wavelengths,
An n-type conductive layer forming step of epitaxially forming an n-type conductive layer on the substrate;
And the active layer group forming step of epitaxially forming an active layer group including a plurality of active layers composed of said each on the n-type conductive layer in the one well layer and one barrier layer,
A p-type conductive layer forming step of epitaxially forming a p-type conductive layer on the active layer group;
With
In the active layer group forming step,
While the thickness of the one well layer is 4 nm or less,
The one and the first active layer comprising a first well layer comprising a first group 13 nitride as a well layer, the one of the the well layer first group 13 second 13 of composition different from the nitride a second active layer comprising a second well layer consisting of nitride, third consisting of the third group 13 nitride having a composition different from said first and second group 13 nitride as the one of the well layer By periodically laminating a third active layer having a well layer, three or more of the one well layers and three or more of the one barrier layers are alternately laminated in the active layer group. Formed into
The first group 13 nitride is a group 13 nitride having a composition of In _x1 Ga _1-x1 N (0.20 ≦ x1 ≦ 0.30) using blue light as an emission wavelength,
The second group 13 nitride is a group 13 nitride having a composition of In _x2 Ga _1-x2 N (0.34 ≦ x2 ≦ 0.44) having an emission wavelength of green light,
The third group 13 nitride is a group 13 nitride having a composition of In _x3 Ga _1-x3 N (0.51 ≦ x3 ≦ 0.65) using red light as an emission wavelength.
A method for manufacturing a light-emitting element structure. A method of manufacturing a light emitting device structure according to claim 4 ,
The total thickness of the first well layer provided in the plurality of first active layers, the total thickness of the second well layer provided in the plurality of second active layers, and the third thickness provided in the plurality of third active layers. The total thickness of the well layers is 4 nm or more,
A method for manufacturing a light-emitting element structure. A method of manufacturing a light emitting device structure according to claim 4 or 5 ,
In the active layer group forming step, the active layer group is formed by repeating stacking in the order of the first active layer, the third active layer, the second active layer, and the third active layer.
A method for manufacturing a light-emitting element structure.