Multi-wavelength light source, method for manufacturing multi-wavelength light source, and display device

Abstract

[Problem] To provide: a multi-wavelength light source exhibiting excellent controllability of emitted light wavelengths; a method of producing a multi-wavelength light source; and a display device. [Solution] A multi-wavelength light source according to the present technology is equipped with a first light-emitting element and a second light-emitting element. The first light-emitting element is provided over a first region having a first in-plane lattice constant, and is formed by layering a first lower semiconductor layer, a first light-emitting layer, and a first upper semiconductor layer in the stated order. The second light-emitting element: is provided over a second region that has a second in-plane lattice constant different from the first in-plane lattice constant; and is formed by layering, in the given order, a second lower semiconductor layer, a second light-emitting layer comprising the same elements as the first light-emitting layer and having a different elemental composition therefrom, and a second upper semiconductor layer.

Description

[Technical field]

[0001] The present technology relates to a multi-wavelength light source including a plurality of light-emitting elements with different emission wavelengths on the same substrate, a method for manufacturing the multi-wavelength light source, and a display device. [Background technology]

[0002] Light-emitting elements using semiconductor materials such as GaN-based materials are being actively developed. Applications of light-emitting elements include display devices using R (red), G (green), and B (blue) light-emitting diodes (LEDs: Light Emitting Diodes) and semiconductor lasers (LDs: Laser Diodes). In such display devices using R, G, and B light-emitting elements, for example, the R, G, and B light-emitting elements are fabricated separately, and then transferred and integrated onto the same substrate, and the R, G, and B light-emitting elements are configured to perform color display as one pixel.

[0003] However, in such a configuration, many manufacturing steps are required to transfer and integrate the light-emitting elements of each color, which increases costs. In response to this, it has been considered to form multiple light-emitting elements with different emission wavelengths on the same substrate (see, for example, Patent Documents 1 to 3).

[0004] Patent Document 1 discloses that a difference in indium incorporation due to differences in growth temperature is utilized to form a plurality of light-emitting layers with different emission wavelengths by applying a temperature gradient to the substrate during crystal growth of the light-emitting layer. Patent Document 2 discloses that a plurality of light-emitting layers with different emission wavelengths are formed by using nanocolumns with different diameters and thicknesses. Patent Document 3 discloses that a plurality of light-emitting layers with different emission wavelengths are formed by growing semiconductor layers in different plane orientations on a substrate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-208544 A [Patent Document 2] JP 2009-49209 A [Patent Document 3] JP 2014-75459 A Summary of the Invention [Problem to be solved by the invention]

[0006] The above-mentioned patent documents each have a problem in that the controllability of the emission wavelength is poor. In view of the above circumstances, an object of the present technology is to provide a multi-wavelength light source with excellent controllability of emission wavelength, a method for manufacturing the multi-wavelength light source, and a display device. [Means for solving the problem]

[0007] In order to achieve the above object, a multi-wavelength light source according to the present technology includes a first light-emitting element and a second light-emitting element. The first light emitting element is provided on a first region having a first in-plane lattice constant, and is formed by laminating a first lower semiconductor layer, a first light emitting layer, and a first upper semiconductor layer in this order. The second light-emitting element is provided on a second region having a second in-plane lattice constant different from the first in-plane lattice constant, and is composed of a second lower semiconductor layer, a second light-emitting layer composed of the same elements as the first light-emitting layer but having a different elemental composition, and a second upper semiconductor layer, which are stacked in this order.

[0008] In order to achieve the above object, a method for manufacturing a multi-wavelength light source according to the present technology includes: forming a first lower semiconductor layer on the first region having a first in-plane lattice constant; forming a first light emitting layer on the first lower semiconductor layer; forming a first upper semiconductor layer on the first light emitting layer; forming a second lower semiconductor layer on a second region having a second in-plane lattice constant different from the first in-plane lattice constant; forming a second light emitting layer on the second lower semiconductor layer; A second upper semiconductor layer is formed on the second light emitting layer.

[0009] In order to achieve the above object, a display device according to the present technology includes a multi-wavelength light source. The multi-wavelength light source includes a first light-emitting element and a second light-emitting element. The first light emitting element is formed by sequentially laminating a first lower semiconductor layer, a first light emitting layer, and a first upper semiconductor layer provided on a first region having a first in-plane lattice constant. The second light-emitting element is formed by sequentially stacking a second lower semiconductor layer, a second light-emitting layer composed of the same elements as the first light-emitting layer but having a different elemental composition, and a second upper semiconductor layer, all of which are provided on a second region having a second in-plane lattice constant different from the first in-plane lattice constant. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic perspective view of a multi-wavelength light source according to a first embodiment of the present technology. [Diagram 2] 1 is a partial schematic cross-sectional view of a multi-wavelength light source according to a first embodiment. [Diagram 3] 1 is a partial schematic cross-sectional view of a multi-wavelength light source according to a first embodiment. [Figure 4] FIG. 1 is a conceptual diagram of an underlayer and a light-emitting element grown on a plurality of regions with different in-plane lattice constants. [Diagram 5] 1A to 1C are process diagrams (part 1) illustrating a method for manufacturing a multi-wavelength light source according to the first embodiment. [Figure 6] 6 is a process diagram (part 2) illustrating the method for manufacturing the multi-wavelength light source following FIG. 5. [Figure 7] FIG. 5 is a partial schematic cross-sectional view of a multi-wavelength light source according to a second embodiment. [Figure 8] FIG. 11 is a partial schematic cross-sectional view of a multi-wavelength light source according to a third embodiment. [Figure 9] 1 is a process diagram (part 1) illustrating the second and third methods of manufacturing multi-wavelength light sources. [Figure 10] 10 is a process diagram (part 2) illustrating the method for manufacturing the multi-wavelength light source following FIG. 9. [Figure 11] 11 is a process diagram (part 3) illustrating the method for manufacturing the multi-wavelength light source following FIG. 10. [Figure 12] FIG. 11 is a partial schematic cross-sectional view of a multi-wavelength light source according to a fourth embodiment. [Figure 13] 13 is a process diagram (part 1) illustrating the fourth method for manufacturing a multi-wavelength light source. [Figure 14] 14 is a process diagram (part 2) illustrating the method for manufacturing the multi-wavelength light source following FIG. 13. [Figure 15] 15 is a process diagram (part 3) illustrating the method for manufacturing the multi-wavelength light source following FIG. 14. [Figure 16] FIG. 11 is a partial schematic cross-sectional view of a multi-wavelength light source according to a fifth embodiment. [Figure 17] FIG. 13 is a partial schematic cross-sectional view of a multi-wavelength light source according to a sixth embodiment. [Figure 18] FIG. 13 is a partial schematic cross-sectional view of a multi-wavelength light source according to a seventh embodiment. [Figure 19] FIG. 2 is a schematic diagram showing an example of an RGB arrangement. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The inventors discovered that, when forming a semiconductor light-emitting device whose main material is a gallium nitride compound semiconductor, the amount of indium incorporated in the crystal grown on the growth surface for growing InGaN crystals, which is a nitride containing gallium and indium, increases with the in-plane lattice constant of the growth surface, and this discovery led to the completion of the present technology. The details are explained below.

[0012] [First embodiment] Fig. 1 is a schematic perspective view of a multi-wavelength light source according to a first embodiment of the present technology. Figs. 2 and 3 are partial schematic cross-sectional views of the multi-wavelength light source. Fig. 2 omits the illustration of electrodes, and Fig. 3 illustrates the electrodes. The multi-wavelength light source according to this embodiment can be applied to, for example, a display device, and constitutes pixels that perform color display in a color image display device.

[0013] (Configuration of Multi-Wavelength Light Source) As shown in Fig. 1, the multi-wavelength light source 1 includes a substrate made of gallium nitride (hereinafter referred to as GaN substrate) 2, a second underlying layer 7G, a third underlying layer 7R, a plurality of blue light-emitting elements 3B as the first light-emitting elements, a plurality of green light-emitting elements 3G as the second light-emitting elements, and a plurality of red light-emitting elements 3R as the third light-emitting elements. One blue light-emitting element 3B, one green light-emitting element 3G, and one red light-emitting element 3R constitute one pixel, and a plurality of pixels are formed in the multi-wavelength light source 1. In the example shown in Fig. 1, the light-emitting elements of each color are arranged in a two-dimensional matrix. The plurality of light-emitting elements 3B, 3G, 3R of each color are arranged linearly, and as a whole, the blue, green, and red light-emitting elements are arranged in a stripe pattern.

[0014] The GaN substrate 2 has a first in-plane lattice constant a1. A partial region of the surface of the GaN substrate 2, more specifically, the region where the blue light-emitting element 3B is formed constitutes the first region 81. The first region 81 serves as the growth surface when growing the blue light-emitting element 3B. In other words, the first region 81 serves as the base when forming the blue light-emitting element 3B.

[0015] The second underlying layer 7G is provided on the GaN substrate 2. The second underlying layer 7G is a nitride containing indium and gallium, Al x2 In y2 Ga (1-x2-y2) N (0 ≤ x2 < 1, 0 < y2 < 1). The surface of the second underlying layer 7G constitutes the second region 82. The second region 82 serves as the growth surface when growing the green light-emitting element 3G. The third underlying layer 7R is provided on the GaN substrate 2. The third underlying layer 7R is a nitride layer containing indium and gallium, Al x3 In y3 Ga (1-x3-y3) N (0 ≤ x3 < 1, 0 < y3 < 1). The third region 83 has a third in-plane lattice constant a3. The third region 83 serves as the growth surface when growing the red light-emitting element 3R. The first in-plane lattice constant a1, the second in-plane lattice constant a2, and the third in-plane lattice constant a3 are different from one another. The second underlayer 7G and the third underlayer 7R are composed of the same elements but have different elemental compositions.

[0016] 2 and 3, the blue light emitting element 3B is provided in a first region 81 formed from the surface of the GaN substrate 2. The blue light emitting element 3B emits blue light having a peak wavelength of, for example, 460 nm. The blue light emitting element 3B is configured by sequentially stacking a blue n-type semiconductor layer 4B as a first lower semiconductor layer, a blue light emitting layer 5B as a first light emitting layer, and a blue p-type semiconductor layer 6B as a first upper semiconductor layer. Furthermore, as shown in FIG. 3, the blue light-emitting element 3B includes a blue n-electrode 8B serving as a first lower electrode electrically connected to the blue n-type semiconductor layer 4B, and a blue p-electrode 9B serving as a first upper electrode electrically connected to the blue p-type semiconductor layer 6B.

[0017] 2 and 3, the green light emitting element 3G is provided on a second region 82 which is the surface of the second underlayer 7G. The green light emitting element 3G emits green light having a peak wavelength of 530 nm, for example. The green light emitting element 3G is configured by sequentially stacking a green n-type semiconductor layer 4G as a second lower semiconductor layer, a green light emitting layer 5G as a second light emitting layer, and a green p-type semiconductor layer 6G as a second upper semiconductor layer. Furthermore, as shown in FIG. 3, the green light-emitting element 3G includes a green n-electrode 8G as a second lower electrode electrically connected to the green n-type semiconductor layer 4G, and a green p-electrode 9G as a second upper electrode electrically connected to the green p-type semiconductor layer 6G.

[0018] 2 and 3, the red light emitting element 3R is provided on the third underlayer 7R. The red light emitting element 3R emits red light having a peak wavelength of, for example, 630 nm. The red light emitting element 3R is configured by sequentially stacking a red n-type semiconductor layer 4R as a third lower semiconductor layer, a red light emitting layer 5R as a third light emitting layer, and a red p-type semiconductor layer 6R as a third upper semiconductor layer. Furthermore, as shown in FIG. 3, the red light-emitting element 3R includes a red n-electrode 8R serving as a third lower electrode electrically connected to the red n-type semiconductor layer 4R, and a red p-electrode 9R serving as a third upper electrode electrically connected to the red p-type semiconductor layer 6R.

[0019] Hereinafter, when there is no particular distinction between the blue light-emitting element 3B, the green light-emitting element 3G, and the red light-emitting element 3R, they may be referred to as light-emitting element 3. Similarly, when there is no particular distinction between the blue n-type semiconductor layer 4B, the green n-type semiconductor layer 4G, and the red n-type semiconductor layer 4R, they may be referred to as n-type semiconductor layer 4. When there is no particular distinction between the blue p-type semiconductor layer 6B, the green p-type semiconductor layer 6G, and the red p-type semiconductor layer 6R, they may be referred to as p-type semiconductor layer 6. When there is no particular distinction between the blue light-emitting layer 5B, the green light-emitting layer 5G, and the red light-emitting layer 5R, they may be referred to as light-emitting layer 5. When there is no particular distinction between the blue n-electrode 8B, the green n-electrode 8G, and the red n-electrode 8R, they may be referred to as n-electrode 8. When there is no particular distinction between the blue p-electrode 9B, the green p-electrode 9G, and the red p-electrode 9R, they may be referred to as p-electrode 9. The same applies to other embodiments described below.

[0020] 2 and 3, the blue light emitting element 3B, the green light emitting element 3G, and the red light emitting element 3R are configured to be separated from one another. That is, the n-type semiconductor layers 4 of each color are separated from one another, the light emitting layers 5 of each color are separated from one another, and the p-type semiconductor layers 6 of each color are separated from one another. The n-electrodes 8 of each color are separated from one another, and the p-electrodes 9 of each color are separated from one another.

[0021] In a multi-wavelength light source 1, each light-emitting element is individually driven and its light emission is controlled. In the multi-wavelength light source 1, the n electrode of each light-emitting element 3 is electrically connected to an n-side wiring (not shown), the p electrode is electrically connected to a p-side wiring (not shown), a row driving circuit (not shown) is connected to the n-type wiring, and a column driving circuit (not shown) is connected to the p-side wiring. The n-type wiring and the p-type wiring are crossed and wired, and the light-emitting element 3 is provided corresponding to each crossing portion. Then, a signal is supplied from the column driving circuit to the light-emitting element 3 in the row selected by the row driving circuit, and the light-emitting element 3 emits light with a luminance corresponding to this signal. Thus, the multi-wavelength light source 1 constitutes a pixel for performing color display of a display device. Note that the configuration of such a pixel circuit is merely an example, and an active matrix drive may be employed by providing a pixel circuit in which driving thin film transistors and capacitive elements are arranged corresponding to the light-emitting elements of each color of each pixel.

[0022] As described above, the larger the lattice constants of the regions 81 to 83 that become the growth surfaces of the light-emitting element 3, the greater the indium (hereinafter sometimes referred to as In) incorporation amount of the crystal constituting the light-emitting element 3 formed on that region. In the light-emitting element 3, the greater the indium incorporation amount in the light-emitting layer 5, the longer the emission wavelength. Therefore, by providing a plurality of regions having different lattice constants, a multi-wavelength light source in which a plurality of light-emitting elements having different emission wavelengths are provided on the same substrate can be easily obtained.

[0023] In any color, the n-type semiconductor layer 4, the light-emitting layer 5, and the p-type semiconductor layer 6 constituting the light-emitting element 3 are nitrides containing gallium and indium, i.e., Al m In n Ga (1-m-n) N (0 ≦ m < 1, 0 < n < 1). The light-emitting elements 3 of each color are composed of the same elements but have different element compositions. The n-type semiconductor layers 4 of various colors are composed of the same elements, but have different elemental compositions from each other, specifically different In compositions. The light-emitting layers 5 of various colors are composed of the same elements, but have different elemental compositions from each other, specifically different In compositions. The p-type semiconductor layers 6 of various colors are composed of the same elements, but have different elemental compositions from each other, specifically different In compositions.

[0024] In this embodiment, the in-plane lattice constant a1 of the first region 81, that is, the in-plane lattice constant a1 of the a-axis on the surface of the GaN substrate 2, is 3.189 Å. From the viewpoint of forming the blue light-emitting element 3B, the in-plane lattice constant a1 of the first region 81 is preferably 3.184 Å or more and 3.194 Å or less, and more preferably 3.186 Å or more and 3.192 Å or less. Al x2 In y2 Ga (1-x2-y2) The in-plane lattice constant a2 of the second region 82 composed of N(0 ≦ x2 < 1, 0 < y2 < 1), that is, the in-plane lattice constant a2 of the a-axis on the surface of the second underlayer 7G, is 3.200 Å. From the viewpoint of forming the green light-emitting element 3G, the in-plane lattice constant a2 of the second region 82 is preferably 3.190 Å or more and 3.210 Å or less, and more preferably 3.193 Å or more and 3.207 Å or less. Al x3 In y3 Ga (1-x3-y3) The in-plane lattice constant a3 of the third region 83 composed of N(0 ≦ x3 < 1, 0 < y3 < 1), that is, the in-plane lattice constant a3 of the a-axis on the surface of the third underlayer 7R, is 3.218 Å. From the viewpoint of forming the red light-emitting element 3R, the in-plane lattice constant a3 of the third region 83 is preferably 3.211 Å or more and 3.225 Å or less, and more preferably 3.213 Å or more and 3.223 Å or less. Thus, the first region 81, the second region 82, and the third region 83 have different in-plane lattice constants. In addition, at least one of the second underlayer 7G and the third underlayer 7R may have a multilayer structure composed of a plurality of layers with different elemental compositions. From the viewpoint of suppressing the occurrence of defects, each of the second underlayer 7G and the third underlayer 7R preferably has a thickness of 100 nm or more. There is no particular upper limit to the thickness, but from the viewpoint of manufacturing process, a thickness of about 3 μm is sufficient.

[0025] In this embodiment, the blue n-type semiconductor layer 4B of the blue light emitting element 3B has an In composition of 1% (element ratio, the same applies below), the blue light emitting layer 5B has an In composition of 16%, and the blue p-type semiconductor layer 6B has an In composition of 1%. From the viewpoint of suitable blue light emission, the In composition of the blue light emitting layer 5B is preferably 14% or more and 18% or less, and more preferably 15% or more and 17% or less. In the green light emitting element 3G, the green n-type semiconductor layer 4G has an In composition of 2%, the green light emitting layer 5G has an In composition of 23%, and the green p-type semiconductor layer 6G has an In composition of 2%. From the viewpoint of suitable green emission, the In composition of the green light emitting layer 5G is preferably 21% or more and 25% or less, and more preferably 22% or more and 24% or less. The red n-type semiconductor layer 4R of the red light emitting element 3R has an In composition of 3%, the red light emitting layer 5R has an In composition of 33%, and the red p-type semiconductor layer 6R has an In composition of 3%. From the viewpoint of suitable red emission, the In composition of the red light emitting layer 5G is preferably 31% or more and 35% or less, and more preferably 32% or more and 34% or less. Thus, the In composition of each of the n-type semiconductor layer 4, the light-emitting layer 5, and the p-type semiconductor layer 6 is the lowest for the blue light-emitting element 3B and the highest for the red light-emitting element 3R, while the In composition of the green light-emitting element 3G is higher than that of the blue light-emitting element 3B and lower than that of the red light-emitting element 3R.

[0026] The active layer 5 may have a single quantum well structure or a multiple quantum well structure in which well layers and barrier layers are alternately stacked. Furthermore, the n-type semiconductor layer 4 and the p-type semiconductor layer 6 may each have a multi-layer structure. Examples of materials that can be used for the n-electrode 8 include titanium (Ti), platinum (Pt), gold (Au), aluminum (Al), and vanadium (V), and a laminated structure of Ti, Pt, and Au can be used. The p-electrode 9 can be made of a metal such as Au, nickel (Ni), palladium (Pd), Ti, or Pt, or a transparent conductive material such as ITO (Indium Tin Oxide), and can have a layered structure of Ni, Pt, and Au. In addition, in the case of an active matrix driven pixel circuit, either the p-electrode or the n-electrode can be common. When the p-electrode is common, the p-type semiconductor layers 6 of each color may be connected to each other without being separated. When the n-electrode is common, the n-type semiconductor layers 4 of each color may be connected to each other without being separated.

[0027] In the multi-wavelength light source 1 of the present embodiment, by forming light-emitting elements in regions having different in-plane lattice constants from each other, it is possible to obtain a plurality of light-emitting elements having light-emitting layers having different In compositions from each other, and to provide a multi-wavelength light source in which a plurality of light-emitting elements having different emission wavelengths are provided on the same substrate.

[0028] (Manufacturing method of multi-wavelength light source) A method for manufacturing the multi-wavelength light source 1 will be described with reference to FIGS. Fig. 4 is an image diagram of an underlayer and a light-emitting device grown on multiple regions with different in-plane lattice constants. In Fig. 4, the substrate and each layer are illustrated as blocks separated by dashed vertical lines, and the width of each block in the horizontal direction of the drawing represents the magnitude of the in-plane lattice constant. 5 and 6 are partial schematic cross-sectional views illustrating the manufacturing process of the multi-wavelength light source 1 in the first embodiment.

[0029] 4, in the multi-wavelength light source 1, a second underlayer 7G having a second in-plane lattice constant a2 of 3.200 Å and a third underlayer 7R having a third in-plane lattice constant a3 of 3.218 Å are formed on a GaN substrate 2 having a first in-plane lattice constant a1 of 3.189 Å. The second underlayer 7G and the third underlayer 7R are formed on the GaN substrate 2 by lattice relaxation. A light emitting element is formed in lattice-matched relation with the first region 81 having the first in-plane lattice constant a1 on the surface of the GaN substrate 2, and this light emitting element becomes the blue light emitting element 3B. A light emitting element is formed in a second region 82 having a second in-plane lattice constant a2 on the surface of the second underlayer 7G in lattice matching with the surface of the underlayer 7G, and this light emitting element becomes a green light emitting element 3G. A light emitting element is formed in a third region 83 having a third in-plane lattice constant a3 on the surface of the third underlayer 7R in lattice matching with the surface of the underlayer 7R, and this light emitting element becomes a red light emitting element 3R. The reason why the emission wavelength of the light-emitting element differs due to the difference in the lattice constant of the region serving as the base for forming the light-emitting element is considered to be as follows. That is, as shown in the image diagram of FIG. 4, in the blue light-emitting element 3B, the light-emitting element is formed by matching the lattice to the in-plane lattice constant a1, and in the light-emitting layer 5B, lattice distortion occurs according to the In composition, and this lattice distortion is one of the factors that limit the amount of In taken in. On the other hand, in the green light-emitting element 3G and the red light-emitting element 3R, 7G and 7R are lattice-relaxed in the in-plane direction, and the lattice constant in the in-plane direction is larger than a1, so that in the light-emitting layers 5G and 5R, the restriction on the amount of In taken in due to lattice distortion is smaller than in the blue light-emitting layer 5B, and it is considered that more In can be taken in. That is, the light-emitting element 3G of 7G, which has a larger in-plane lattice constant, and 3R, which has an even larger in-plane lattice constant, can obtain InGaN with a higher In composition than 3B, and the emission wavelength of each light-emitting element can be made different.

[0030] The manufacturing method will be described below. In manufacturing the multi-wavelength light source 1, the n-type semiconductor layer 4, the light-emitting layer 5, and the p-type semiconductor layer 6 of the light-emitting element 3 of each color are manufactured together, and the conditions for forming the light-emitting element 3 of each color are the same except that the in-plane lattice constant of the underlying region is different. The second and third underlayers and each light emitting element can be formed by crystal growth using a method such as Metal Organic Chemical Vapor Deposition (MOCVD) or Molecular Beam Epitaxy (MBE).

[0031] 5(A), an insulating first mask 71 that partially covers a GaN substrate 2 having a first in-plane lattice constant a1 of 3.189 Å is formed on the substrate by photolithography or electron beam lithography. The first mask 71 covers at least the areas corresponding to the first region 81 and the third region 83, and has an opening in the area corresponding to the second region 82. The first mask 71 is made of, for example, silicon dioxide (SiO 2 The first mask 71 can be formed by, for example, the following photolithography method. That is, SiO 2 is deposited to a thickness of several hundred nm by Chemical Vapor Deposition (CVD), and then the SiO 2 A resist film is formed on the SiO 2 film, and the resist film is patterned into a desired shape. 2 After etching with hydrofluoric acid or the like to expose the substrate surface, the resist film is removed, thereby forming a first mask 71.

[0032] Next, as shown in FIG. 5(B), a second underlayer 70G is formed on the GaN substrate 2 via a first mask 71 by MOCVD. The second in-plane lattice constant a2 of the surface of the second underlayer 70G is 3.200 Å. The second underlayer 70G can have a desired second in-plane lattice constant by controlling the element composition such as the In composition and the layered structure. As a specific example, the second underlayer 70G may have a laminated structure in which a low-temperature buffer layer, an InGaN layer which is a nitride containing indium and gallium, an (Al)GaN layer, and an InGaN layer are laminated in this order. The (Al)GaN layer means a GaN layer or an AlGaN layer. The low-temperature buffer layer is made of GaN, AlN, AlGaN, or InGaN. The low-temperature buffer layer realizes lattice relaxation with the GaN substrate 2. By appropriately selecting the In composition and thickness of the InGaN layer, the Al composition and thickness of the (Al)GaN layer, and the In composition and thickness of the InGaN layer above the low-temperature buffer layer, it is possible to obtain the second underlayer 70G having a desired second in-plane lattice constant a2 larger than the first in-plane lattice constant a1. In detail, an InGaN layer having an In composition of 10% is laminated on the GaN substrate 2 via the first mask 71 to a thickness of 5 nm to 50 nm under a temperature condition of 500° C. to 600° C. Then, an InGaN layer having an In composition of 5% is laminated on the InGaN layer to a thickness of several tens to several hundreds of nm under a temperature condition of 700° C. to 900° C. Furthermore, a GaN layer is laminated on the InGaN layer to a thickness of several tens of nm, and then an InGaN layer having an In composition of 5% is laminated to a thickness of several tens to several hundreds of nm, thereby forming a second underlayer 70G having a laminate structure. In this specification, the second underlayer before being separated into each light-emitting element by etching is given the reference symbol 70G, and the second underlayer after being separated into each light-emitting element by etching is given the reference symbol 7G.

[0033] Next, as shown in FIG. 5(C), the first mask 71 is removed with hydrofluoric acid or the like. 5(D), an insulating second mask 72 partially covering the GaN substrate 2 is formed on the GaN substrate 2 by photolithography in the same manner as the first mask 71. The second mask 72 covers at least the area corresponding to the first region 81 and the second underlayer 7G, and has an opening in the area corresponding to the third region 83.

[0034] Next, as shown in FIG. 5(E), a third underlayer 70R is formed on the GaN substrate 2 via a second mask 72. The third underlayer 70R has an in-plane lattice constant of 3.218 Å. Like the second underlayer 70G, the third underlayer 70R can also have a desired third in-plane lattice constant by controlling the element composition such as the In composition and the layered structure. As a specific example, the third underlayer 70R may have a layered structure in which a low-temperature buffer layer, an InGaN layer, an (Al)GaN layer, and an InGaN layer are layered in this order. The low-temperature buffer layer is made of GaN, AlN, AlGaN, or InGaN. The low-temperature buffer layer realizes lattice relaxation with the GaN substrate 2. By appropriately selecting the In composition and thickness of the InGaN layer laminated on the low-temperature buffer layer, the Al composition and thickness of the (Al)GaN layer, and the In composition and thickness of the InGaN layer above, it is possible to obtain the third underlayer 70R having a desired third in-plane lattice constant a3 larger than the first in-plane lattice constant a1 and the second in-plane lattice constant a2. More specifically, an InGaN layer having an In composition of 10% and a thickness of 5 nm to 50 nm is formed on the GaN substrate 2 via the first mask 71 at a temperature condition of 500° C. to 600° C. Then, an InGaN layer having an In composition of 10% and a thickness of several tens to several hundreds of nm is laminated on the InGaN layer at a temperature condition of 700° C. to 900° C. Furthermore, a GaN layer having a thickness of several tens of nm is laminated on the InGaN layer, and then an InGaN layer having an In composition of 10% and a thickness of several tens to several hundreds of nm is laminated to form a third underlayer 70R having a laminate structure. The third underlayer 70R has an In composition in the InGaN layer that is higher than that of the second underlayer 70G. In this specification, the third underlayer before being separated into each light-emitting element by etching is given the reference symbol 70R, and the third underlayer after being separated into each light-emitting element by etching is given the reference symbol 7R.

[0035] 5(F), the second mask 72 is removed with hydrofluoric acid or the like to form a second underlayer 70G and a third underlayer 70R on the GaN substrate 2. This forms a first region 81 having a first in-plane lattice constant a1 and constituting a part of the surface of the GaN substrate 2, a second region 82 having a second in-plane lattice constant a2 and constituting the surface of the second underlayer 70G, and a third region 83 having a third in-plane lattice constant a3 and constituting the surface of the third underlayer 70R.

[0036] 6(A), an InGaN layer is laminated on the GaN substrate 2 including the second underlayer 70G and the third underlayer 70R by MOCVD under a temperature condition of, for example, 700° C. to 1000° C. to a thickness of several tens to several hundreds of nm to form the n-type semiconductor layer 40. As the dopant for the n-type semiconductor layer 40, for example, Si is used. The n-type semiconductor layer 40 may be a multi-layer structure including GaN, AlN, AlGaN, AlInGaN, etc., or a superlattice structure combining these mixed crystals. As for the composition range of the n-type semiconductor layer 40, it is preferable that the average In composition of AlInGaN is less than 20% and the average Al composition is less than 40% for the entire n-type semiconductor layer. As the n-type semiconductor layer 40, for example, InGaN with an In composition of 5% can be formed to a thickness of 300 nm. In this specification, the n-type semiconductor layer before being separated into each light-emitting element by etching is given the reference numeral 40, and the n-type semiconductor layer after being separated into each light-emitting element by etching is given the reference numeral 4.

[0037] Next, as shown in FIG. 6(B), on the n-type semiconductor layer 40, InGaN to be a quantum well layer is formed to a thickness of 3 nm under growth temperature conditions of, for example, 700° C. to 800° C. by MOCVD, and GaN to be a barrier layer is formed to a thickness of 10 nm. This is then repeatedly stacked in multiple layers to form the light-emitting layer 50. In this specification, the light emitting layer before being separated into each light emitting element by etching is given the reference symbol 50, and the light emitting layer after being separated into each light emitting element by etching is given the reference symbol 5.

[0038] 6(C), an InGaN layer is formed on the light emitting layer 50 by MOCVD at a temperature of, for example, 700° C. to 1000° C. to a thickness of several tens to several hundreds of nm to form a p-type semiconductor layer 60. As a dopant for the p-type semiconductor layer 60, for example, Mg is used. Like the n-type semiconductor layer 40, the p-type semiconductor layer 60 may be a multilayer structure including GaN, AlN, AlGaN, AlInGaN, or the like, or a superlattice structure combining these mixed crystals. As for the composition range of the p-type semiconductor layer 60, it is preferable that the average In composition of the AlInGaN is less than 20% and the average Al composition is less than 40% for the entire p-type semiconductor layer. As the p-type semiconductor layer 60, for example, InGaN with an In composition of 5% can be formed to a thickness of 300 nm. In this specification, the p-type semiconductor layer before being separated into each light-emitting element by etching is given the reference symbol 60, and the p-type semiconductor layer after being separated into each light-emitting element by etching is given the reference symbol 6.

[0039] Next, as shown in Fig. 6(D), the light emitting elements 30 are separated by etching. In detail, a resist film or a SiO 2 film having a pattern that exposes only the boundary regions of each light emitting element is formed on the light emitting elements 30 shown in Fig. 6(C). 2 The light emitting element 30, the second underlayer 70G, and the third underlayer 70R are dry etched through a mask made of a material such as a SiO 2 film or the like. This separates the light emitting elements 3 into a plurality of light emitting elements 3. Thereafter, an n-electrode 8 is formed which is electrically connected to the exposed portion of the n-type semiconductor layer 4, and a p-electrode 9 is further formed which is electrically connected to the p-type semiconductor layer 6, thereby obtaining the light emitting element 3. In this manner, a multi-wavelength light source 1 in which a plurality of light emitting elements are formed on the same substrate is manufactured.

[0040] The light emitting layers 5 of the light emitting elements 3 of each color thus manufactured have different In compositions and different emission wavelengths for the first to third regions 81 to 83. In particular, the light emitting layer 5 formed on the first region 81 has the smallest In composition, the light emitting layer 5 formed on the third region 83 has the largest In composition, and the light emitting layer 5 formed on the second region 82 has a larger In composition than the light emitting layer 5 on the first region 81 and a smaller In composition than the light emitting layer 5 on the third region 83. This makes it possible to manufacture a multi-wavelength light source 1 in which a plurality of light emitting elements emitting blue, green, and red light having mutually different wavelengths are provided on the same substrate.

[0041] As described above, in this embodiment, by arbitrarily controlling the in-plane lattice constant of the region that becomes the growth surface of the light-emitting element, the emission wavelength of the light-emitting element that is formed can be easily controlled, and excellent wavelength controllability of the light-emitting elements of each color is achieved. In this embodiment, the size of the region that becomes the growth surface of the light-emitting element, such as the second underlayer 7G and the third underlayer 7R, and the size of each light-emitting element can be arbitrarily selected by a mask formation process using photolithography. Therefore, the light-emitting element size can be highly controllable, and a multi-wavelength light source with high integration can be obtained at low cost. This makes it possible to obtain a display device that can display high-definition images.

[0042] Furthermore, in this embodiment, by providing a second underlayer 7G and a third underlayer 7R that appropriately reduce the amount of lattice distortion in accordance with the In composition of the light-emitting layer of the light-emitting element, the amount of lattice distortion in the light-emitting layer can be reduced, thereby achieving highly efficient light-emitting characteristics in green and red. The red light emitting element 3R in this embodiment has an emission intensity 100 times or more that of a red light emitting element formed on a general GaN template substrate, and can obtain an external quantum efficiency equivalent to that of a green light emitting element formed on a GaN template substrate, and has excellent emission characteristics. Also, the green light emitting element 3G in this embodiment can have emission characteristics equivalent to that of a green light emitting element formed on a general GaN template substrate. The GaN template substrate is a substrate having a structure in which a GaN layer is laminated to a thickness of several μm on a sapphire substrate or a Si substrate via a GaN low-temperature buffer layer.

[0043] In this embodiment, the n-type semiconductor layer 4, the light-emitting layer 5, and the p-type semiconductor layer 6 of the light-emitting element 3 of each color are formed together, but they may be formed separately for each color. However, forming them together as described above is more preferable, and compared to forming them separately for each color, it is possible to shorten the tact time and reduce the manufacturing cost. In addition, it is possible to reduce the thermal history of other light-emitting elements, thereby improving the luminous efficiency of each light-emitting element.

[0044] Other embodiments will be described below, but the same reference numerals will be used to designate the same components as those described above, and the description thereof may be omitted.

[0045] [Second embodiment] FIG. 7 is a partial schematic cross-sectional view of a multi-wavelength light source according to the second embodiment. In the first embodiment, the first region 81 serving as the base for forming the blue light-emitting element 3B was a GaN substrate, but in this embodiment, a first base layer 14 is provided on the substrate, and the surface of the first base layer 14 serves as the first region 81. In the above-described first embodiment, by using a GaN substrate having a first region 81 which serves as a growth surface for growing the blue light-emitting element 3B, the process of forming the first underlayer 14 as in the second embodiment can be omitted, shortening the takt time and reducing the manufacturing cost.

[0046] As shown in Figure 7, the multi-wavelength light source 10 of this embodiment has a substrate 12, a first base layer 14, a second base layer 7G, a third base layer 7R, a blue light-emitting element 3B as a first light-emitting element, a green light-emitting element 3G as a second light-emitting element, and a red light-emitting element 3R as a third light-emitting element. The first underlayer 14, the second underlayer 7G, and the third underlayer 7R are provided on the substrate 12. The surface of the first underlayer 14 constitutes a first region 81 having a first in-plane lattice constant a1, and the blue light-emitting element 3B is provided on the first region 81. The surface of the second underlayer 7G constitutes a second region 82 having a second in-plane lattice constant a2, and the green light-emitting element 3G is provided on the second region 82. The surface of the third underlayer 7R constitutes a third region 83 having a third in-plane lattice constant a3, and the red light-emitting element 3R is provided on the third region 83. In the multi-wavelength light source 10 shown in FIG. 7, the light-emitting elements 3 are separated from each other, similarly to the first embodiment.

[0047] The substrate 12 can be, for example, a GaN template substrate having a structure in which a GaN layer is laminated to a thickness of several μm on a sapphire substrate or a Si substrate via a GaN low-temperature buffer layer, an AlN buffer layer, and an AlGaN layer; an AlN template substrate having a structure in which an AlN layer is laminated to a thickness of several μm on an Al low-temperature buffer layer; a bulk substrate such as a GaN substrate, an AlN substrate, a sapphire substrate, a Si substrate, a GaAs substrate, a ZnO substrate, or a ScAlMgO substrate.

[0048] The materials used for the n-type semiconductor layer 4, the light emitting layer 5, and the p-type semiconductor layer 6 constituting the light emitting element 3 are the same as those in the first embodiment. The In composition of the n-type semiconductor layer 4, the In composition of the light emitting layer 5, and the In composition of the p-type semiconductor layer 6 of each light emitting element 3 of each color are the same as those in the first embodiment.

[0049] The first underlayer 14 is made of GaN. The in-plane lattice constant a1 of the first region 81 made of the surface of the first underlayer 14 is 3.189 Å. The second underlayer 7G and the third underlayer 7R have a configuration similar to that of the second underlayer 7G and the third underlayer 7R of the first embodiment, and the in-plane lattice constant a2 of the second region 82 and the in-plane lattice constant a3 of the third region 83 are the same as those of the first embodiment. In this manner, the first region 81, the second region 82, and the third region 83 each have a different in-plane lattice constant.

[0050] In the multi-wavelength light source 10 of this embodiment, similarly to the first embodiment, a plurality of light-emitting elements with different emission wavelengths can be formed by forming light-emitting elements in a plurality of regions with different in-plane lattice constants. The manufacturing method of the above-mentioned multi-wavelength light source 10 is basically the same as that of the multi-wavelength light source 15 of the third embodiment described later, and therefore will be described later together with the manufacturing method of the multi-wavelength light source 15.

[0051] [Third embodiment] FIG. 8 is a partial schematic cross-sectional view of a multi-wavelength light source according to the third embodiment. In the second embodiment, an example in which GaN is used as the first underlying layer is given, but the present invention is not limited thereto, and it may be configured using InGaN as in the present embodiment.

[0052] (Configuration of Multi-Wavelength Light Source) As shown in FIG. 8, the multi-wavelength light source 15 according to the present embodiment includes a substrate 12, a first underlying layer 17, a second underlying layer 7G, a third underlying layer 7R, a blue light-emitting element 3B as a first light-emitting element, a green light-emitting element 3G as a second light-emitting element, and a red light-emitting element 3R as a third light-emitting element. The first underlying layer 17, the second underlying layer 7G, and the third underlying layer 7R are provided on the substrate 12. The surface of the first underlying layer 17 constitutes a first region 81 having a first in-plane lattice constant a1, and the blue light-emitting element 3B is provided on the first region 81. The surface of the second underlying layer 7G constitutes a second region 82 having a second in-plane lattice constant a2, and the green light-emitting element 3G is provided on the second region 82. The surface of the third underlying layer 7R constitutes a third region 83 having a third in-plane lattice constant a3, and the red light-emitting element 3R is provided on the third region 83. Also in the multi-wavelength light source 15 shown in FIG. 8, the light-emitting elements 3 are separated from each other as in the first embodiment.

[0053] The materials used for the n-type semiconductor layer 4, the light-emitting layer 5, and the p-type semiconductor layer 6 constituting the light-emitting element 3 are the same as those in the first embodiment. The In composition of the n-type semiconductor layer 4, the In composition of the light-emitting layer 5, and the In composition of the p-type semiconductor layer 6 of each light-emitting element 3 of each color are the same as those in the first embodiment.

[0054] The first underlying layer 17 is Al x1 In y1 Ga (1-x1-y1) N (0 ≦ x1 < 1, 0 < y1 < 1). The in-plane lattice constant a1 of the first region 81 formed by the surface of the first underlying layer 17 is 3.191 Å. The second underlying layer 7G and the third underlying layer 7R have the same configuration as the second underlying layer 7G and the third underlying layer 7R of the first embodiment, and the in-plane lattice constant a2 of the second region 82 and the in-plane lattice constant a3 of the third region 83 are the same as those in the first embodiment. In this manner, the first region 81, the second region 82, and the third region 83 each have a different in-plane lattice constant.

[0055] In the multi-wavelength light source 15 of this embodiment, similarly to the first embodiment, light-emitting elements are formed in a plurality of regions having different in-plane lattice constants, thereby making it possible to form light-emitting elements with different emission wavelengths.

[0056] (Method of Manufacturing Multi-Wavelength Light Sources 10 and 15) Hereinafter, a method for manufacturing the multi-wavelength light source 10 of the second embodiment and the multi-wavelength light source 15 of the third embodiment will be described with reference to FIGS. 9 to 11 are partial schematic cross-sectional views illustrating the manufacturing process of the multi-wavelength light source 10 (15) according to the second embodiment (third embodiment).

[0057] Hereinafter, the first, second and third underlayers and each light emitting element can be formed by crystal growth using a Metal Organic Chemical Vapor Deposition (MOCVD) method, a Molecular Beam Epitaxy (MBE) method, etc. Each mask used in the manufacturing process can be a mask formed by the same formation method as in the first embodiment.

[0058] 9(A), an insulating first mask 73 is formed by photolithography on a substrate 12 made of, for example, sapphire, so as to partially cover the substrate 12. The first mask 73 covers at least the areas corresponding to the second region 82 and the third region 83, and has an opening at the area corresponding to the first region 81.

[0059] Next, as shown in FIG. 9B, a first underlayer 140 (170) having a first in-plane lattice constant a1 is formed on the substrate 12 through a first mask 73 by MOCVD. In this embodiment, the first underlayer before being separated into each light-emitting element by etching is denoted by the reference symbol 140 (170), and the first underlayer after being separated into each light-emitting element by etching is denoted by the reference symbol 14 (17).

[0060] The first underlayer 140 made of GaN according to the second embodiment can have a laminated structure in which a low-temperature buffer layer made of GaN and a GaN layer having a thickness of several μm are laminated in this order.

[0061] The first underlayer 170 made of InGaN according to the third embodiment can have a desired first in-plane lattice constant a1 by controlling the element composition, such as the In composition, and the layered structure, similar to the second underlayer 70G and the third underlayer 70R described in the first embodiment. As a specific example, the first underlayer 170 may have a layered structure in which a low-temperature buffer layer, an InGaN layer, an (Al)GaN layer, and an InGaN layer are layered in this order. By appropriately selecting the In composition and thickness of the InGaN layer to be stacked on the low-temperature buffer layer, the Al composition and thickness of the (Al)GaN layer, and the In composition and thickness of the upper InGaN layer, it is possible to form a first underlayer 170 having a desired first in-plane lattice constant a1. More specifically, an InGaN layer having an In composition of 10% and a thickness of 5 nm to 50 nm is formed on the substrate 12 via the first mask 71 at a temperature condition of 500° C. to 600° C. Then, an InGaN layer having an In composition of 1.5% and a thickness of several tens to several hundreds of nm is laminated on the InGaN layer at a temperature condition of 700° C. to 900° C. Furthermore, a GaN layer having a thickness of several tens of nm is laminated on the InGaN layer, and then an InGaN layer having an In composition of 1.5% and a thickness of several tens to several hundreds of nm is laminated to form the first underlayer 170 having a laminate structure.

[0062] Next, as shown in FIG. 9C, the first mask 73 is removed with hydrofluoric acid or the like. 9(D), an insulating second mask 74 is formed by photolithography on the substrate 12 including the first underlayer 140 (170) so as to partially cover the substrate 12. The second mask 74 covers at least the area corresponding to the third region 83 and the first underlayer 140 (170), and has an opening in the area corresponding to the second region 82.

[0063] 9(E), a second underlayer 70G is formed on the substrate 12 via a second mask 74. The second underlayer 70G is similar to the second underlayer 70G in the first embodiment. The second underlayer 70G is formed by making the In composition of the InGaN layer higher than that of the first underlayer (140) 170.

[0064] Next, as shown in FIG. 9(F), the second mask 74 is removed with hydrofluoric acid or the like. 10(A), an insulating third mask 75 is formed by photolithography on the substrate 12 including the first underlayer 140 (170) and the second underlayer 70G, partially covering the substrate 12. The third mask 75 covers at least the first underlayer 140 (170) and the second underlayer 70G, and has an opening in a portion corresponding to the third region 83.

[0065] 10(B), a third underlayer 70R is formed on the substrate 12 via a third mask 75. The third underlayer 70R is similar to the third underlayer 70R in the first embodiment. The third underlayer 70R is formed by making the In composition of the InGaN layer higher than that of the second underlayer 70G.

[0066] 10(C), the third mask 75 is removed by hydrofluoric acid or the like. As a result, the first underlayer 140 (170), the second underlayer 70G, and the third underlayer 70R are formed on the substrate 12. As a result, a first region 81 having a first in-plane lattice constant a1 and consisting of the surface of the first underlayer 140 (170), a second region 82 having a second in-plane lattice constant a2 and consisting of the surface of the second underlayer 70G, and a third region 83 having a third in-plane lattice constant a3 and consisting of the surface of the third underlayer 70R are formed.

[0067] Next, as shown in FIG. 10(D), an n-type semiconductor layer 40 is formed on the substrate 12 including the first underlayer 140 (170), the second underlayer 70G, and the third underlayer 70R by MOCVD in the same manner as in the method for forming the n-type semiconductor layer 40 of the first embodiment. Next, as shown in FIG. 11(A), the light emitting layer 50 is formed on the n-type semiconductor layer 40 by MOCVD in the same manner as in the method of forming the light emitting layer 50 of the first embodiment. Next, as shown in FIG. 11(B), a p-type semiconductor layer 60 is formed on the light emitting layer 50 by MOCVD in the same manner as in the formation of the p-type semiconductor layer 60 of the first embodiment. 11(C), similarly to the first embodiment, the light-emitting element 30 is separated into a plurality of light-emitting elements 3 by etching. Thereafter, an n-electrode 8 is formed which is electrically connected to the exposed portion of the n-type semiconductor layer 4, and a p-electrode 9 is further formed which is electrically connected to the p-type semiconductor layer 6, thereby obtaining the light-emitting element 3. In this manner, a multi-wavelength light source 10 (15) in which a plurality of light-emitting elements are formed on the same substrate is manufactured.

[0068] As in the first embodiment, the light emitting layers 5 of the light emitting elements 3 of each color thus manufactured have different In compositions and different emission wavelengths for the first to third regions 81 to 83. This makes it possible to form a multi-wavelength light source 10 (15) on the same substrate, in which a plurality of light emitting elements emitting blue, green and red light having mutually different wavelengths are provided.

[0069] [Fourth embodiment] 12 is a partial schematic cross-sectional view of a multi-wavelength light source 18 according to a fourth embodiment. In the fourth embodiment, a first base layer is formed on the entire surface of a substrate 12, and second and third base layers are formed on the first base layer.

[0070] (Configuration of multi-wavelength light source) As shown in Figure 12, the multi-wavelength light source 18 of this embodiment has a substrate 12, a first base layer 19, a second base layer 7G, a third base layer 7R, a blue light-emitting element 3B as a first light-emitting element, a green light-emitting element 3G as a second light-emitting element, and a red light-emitting element 3R as a third light-emitting element. The first underlayer 19 is provided on the entire surface of the substrate 12. The second underlayer 7G and the third underlayer 7R are provided on the first underlayer 19. The surface of the first underlayer 19 constitutes a first region 81 having a first in-plane lattice constant a1, and the blue light-emitting element 3B is provided on the first region 81. The surface of the second underlayer 7G constitutes a second region 82 having a second in-plane lattice constant a2, and the green light-emitting element 3G is provided on the second region 82. The surface of the third underlayer 7R constitutes a third region 83 having a third in-plane lattice constant a3, and the red light-emitting element 3R is provided on the third region 83. In the multi-wavelength light source 18 shown in FIG. 12, the light-emitting elements 3 are separated from each other, similarly to the first embodiment.

[0071] The materials used for the n-type semiconductor layer 4, the light emitting layer 5, and the p-type semiconductor layer 6 constituting the light emitting element 3 are the same as those in the first embodiment. The In composition of the n-type semiconductor layer 4, the In composition of the light emitting layer 5, and the In composition of the p-type semiconductor layer 6 of each light emitting element of each color are the same as those in the first embodiment.

[0072] In this embodiment, the first underlayer 19 is made of AlN, AlGaN, AlInGaN, or GaN. In the multi-wavelength light source 18 of this embodiment, the in-plane lattice constant a1 of the first region 81 made of GaN is 3.189 Å. The second underlayer 7G and the third underlayer 7R have a configuration similar to that of the second underlayer 7G and the third underlayer 7R of the first embodiment, and the in-plane lattice constant a2 of the second region 82 and the in-plane lattice constant a3 of the third region 83 are the same as those of the first embodiment. In this manner, the first region 81, the second region 82, and the third region 83 each have a different in-plane lattice constant.

[0073] In the multi-wavelength light source 18 of this embodiment, similarly to the first embodiment, light emitting elements are formed in a plurality of regions having different in-plane lattice constants, thereby making it possible to form light emitting elements with different emission wavelengths.

[0074] (Manufacturing method of multi-wavelength light source) A method for manufacturing the multi-wavelength light source 18 will be described with reference to FIGS. 13 to 15 are partial schematic cross-sectional views illustrating the manufacturing process of the multi-wavelength light source 18.

[0075] Hereinafter, the first, second and third underlayers and each light emitting element can be formed by crystal growth using a Metal Organic Chemical Vapor Deposition (MOCVD) method, a Molecular Beam Epitaxy (MBE) method, etc. Each mask used in the manufacturing process can be a mask formed by the same formation method as in the first embodiment.

[0076] 13(A), a first underlayer 19 made of GaN having a first in-plane lattice constant a1 is formed by MOCVD on the entire surface of a substrate 12 made of, for example, sapphire. The first underlayer 19 can have a layered structure in which a low-temperature buffer layer made of GaN and a GaN layer having a thickness of several μm are sequentially layered.

[0077] 13(B), an insulating first mask 76 is formed by photolithography on the first underlayer 19 so as to partially cover the first underlayer 19. The first mask 76 covers the first underlayer 19 at least in areas corresponding to the first region 81 and the third region 83, and has an opening in an area corresponding to the second region 82.

[0078] 13(C), a second underlayer 70G is formed on the first underlayer 19 through a first mask 76. The second underlayer 70G is similar to the second underlayer 70G in the first embodiment.

[0079] Next, as shown in FIG. 13(D), the first mask 76 is removed with hydrofluoric acid or the like. 13(E), an insulating second mask 77 is formed by photolithography on the first underlayer 19 to partially cover the first underlayer 19. The second mask 77 covers at least a portion corresponding to the first region 81 and the second underlayer 70G, and has an opening at a portion corresponding to the third region 83.

[0080] 14(A), a third underlayer 70R is formed on the first underlayer 19 via a second mask 77. The third underlayer 70R is similar to the third underlayer 70R in the first embodiment. The third underlayer 70R is formed such that the In composition of the InGaN layer is higher than that of the second underlayer 70G.

[0081] 14(B), the second mask 77 is removed by hydrofluoric acid or the like. As a result, a second underlayer 70G and a third underlayer 70R are formed on the first underlayer 19. As a result, a first region 81 having a first in-plane lattice constant a1 and constituting a part of the surface of the first underlayer 19, a second region 82 having a second in-plane lattice constant a2 and constituting the surface of the second underlayer 70G, and a third region 83 having a third in-plane lattice constant a3 and constituting the surface of the third underlayer 70R are formed.

[0082] Next, as shown in FIG. 14(C), an n-type semiconductor layer 40 is formed on the first underlayer 19, the second underlayer 70G, and the third underlayer 70R by MOCVD in the same manner as in the method of forming the n-type semiconductor layer 40 in the first embodiment. Next, as shown in FIG. 14(D), the light emitting layer 50 is formed on the n-type semiconductor layer 40 by MOCVD in the same manner as in the method of forming the light emitting layer 50 of the first embodiment. Next, as shown in FIG. 15(A), a p-type semiconductor layer 60 is formed on the light emitting layer 50 by MOCVD in the same manner as in the formation of the p-type semiconductor layer 60 of the first embodiment. 15(B), each light-emitting element 3 is separated by etching. Thereafter, an n-electrode 8 is formed which is electrically connected to the exposed portion of the n-type semiconductor layer 4, and a p-electrode 9 is further formed which is electrically connected to the p-type semiconductor layer 6, thereby obtaining a light-emitting element 3 for each color. In this manner, a multi-wavelength light source 18 in which a plurality of light-emitting elements are formed on the same substrate is manufactured.

[0083] As in the first embodiment, the light emitting layer 5 of the light emitting element 3 manufactured in this manner has a different In composition for each of the first to third regions 81 to 83. This makes it possible to manufacture a multi-wavelength light source 18 in which a plurality of light emitting elements emitting blue, green and red light having different wavelengths are provided on the same substrate. In the fourth embodiment, compared to the second embodiment, the step of patterning the first underlayer can be omitted, and the manufacturing cost can be reduced.

[0084] In each of the multi-wavelength light sources of the second to fourth embodiments described above, similarly to the first embodiment, the emission wavelength of the light-emitting element formed can be easily controlled by arbitrarily controlling the in-plane lattice constant of the region that becomes the growth surface of the light-emitting element, and thus the wavelength controllability of the light-emitting elements of each color is excellent. Moreover, each of the multi-wavelength light sources of the second to fourth embodiments can be applied to color display of a display device in the same manner as in the first embodiment. In these embodiments, the size of the region that becomes the growth surface of the light-emitting element of each color and the size of each light-emitting element can be arbitrarily selected by a mask formation process using photolithography. Therefore, it is possible to obtain a multi-wavelength light source with high controllability of the light-emitting element size and high integration at low cost. As a result, it is possible to obtain a display device capable of displaying high-definition images. Furthermore, in each of the multi-wavelength light sources of the second to fourth embodiments, by providing a second underlayer 7G and a third underlayer 7R that appropriately reduce the amount of lattice distortion depending on the In composition of the light-emitting layer of the light-emitting element, the amount of lattice distortion in the light-emitting layer can be reduced, and highly efficient light-emitting characteristics in green and red can be obtained.

[0085] [Fifth embodiment] In the above-described embodiment, an example has been given in which a multi-wavelength light source is applied to a color display of a display device, but the present invention is not limited to this. For example, the multi-wavelength light source in the first to fourth embodiments can be used as a white light source for illumination that emits white light as a whole. In this case, the configuration may be such that each light-emitting element is not individually driven and controlled, and each light-emitting element may not be individually separated. For example, the light-emitting element 30 may be in a state in which the n-type semiconductor layer 4, the light-emitting layer 5, and the p-type semiconductor layer 6 of each color are not separated and are connected to each other before being separated into individual light-emitting elements 3 by etching, and the n-electrode 8 and the p-electrode 9 may also be made common. In addition, a white light source of a desired color can be obtained by adjusting the area occupied by the light-emitting elements in the substrate surface for each color. In this technology, as described above, the size of the region that becomes the growth surface of the light-emitting elements of each color and the size of each light-emitting element can be arbitrarily selected by a mask formation process using photolithography, so that illumination that emits white light of a desired color can be easily obtained. In addition, such a white light source can be used as a backlight for a liquid crystal display device in addition to being used for illumination. In addition, the emitted illumination light is not limited to white, and may be of a desired color.

[0086] As the white light source, in addition to using red, blue and green light emitting elements, it is also possible to use blue and yellow light emitting elements and use a mixture of these two colors to form a multi-wavelength light source that emits white light as shown in Fig. 16. In the multi-wavelength light sources of the above-mentioned first to fourth embodiments, examples have been given in which light emitting elements that emit three colors of light, red, blue and green, respectively, are provided, but light emitting elements of two colors, blue and yellow, may also be provided as in the fifth embodiment shown in Fig. 16. FIG. 16 is a partial schematic cross-sectional view of a multi-wavelength light source according to the fifth embodiment. As shown in FIG. 16, the multi-wavelength light source 20 has a GaN substrate 2, a second underlayer 7Y, a blue light-emitting element 3B as a first light-emitting element, and a yellow light-emitting element 3Y as a second light-emitting element.

[0087] The GaN substrate 2 has a first in-plane lattice constant a1. Among the surfaces of the GaN substrate 2, the region where the blue light-emitting element 3B is formed constitutes a first region 81, which serves as a growth surface when growing the blue light-emitting element 3B. The blue light-emitting element 3B is provided on the first region 81 of the GaN substrate 2. A second underlayer 7Y is provided on the GaN substrate 2, and the surface of the second underlayer 7Y constitutes a second region 82. The surface of the second underlayer 7Y has a second in-plane lattice constant a2. The second in-plane lattice constant a2 is larger than the first in-plane lattice constant a1. The second region 82 serves as a growth surface when growing the yellow light-emitting element 3Y. The yellow light-emitting element 3Y is provided on the second region 82.

[0088] Also in this embodiment, similar to the above-described embodiment, by varying the lattice constant of the region where the light-emitting element is formed, the emission wavelength of the light-emitting element formed on the region can be varied. In the multi-wavelength light source 20 of this embodiment, the in-plane lattice constant a1 of the first region 81 is 3.189 Å. The second underlayer 7Y is Al x4 In y4 Ga (1-x4-y4) N (0 ≦ x4 < 1, 0 < y4 < 1). The in-plane lattice constant a2 of the second region 82 formed from the surface of the second underlayer 7Y is 3.208 Å. From the viewpoint of forming the yellow light-emitting element 3Y, the in-plane lattice constant of the second region 82 is preferably 3.198 Å or more and 3.218 Å or less, more preferably 3.201 Å or more and 3.215 Å or less.

[0089] The second underlayer 7Y can have a desired second in-plane lattice constant by controlling the element composition such as the In composition and the stacking structure. As a specific example, the second underlayer 7Y can have a stacked structure in which a low-temperature buffer layer, an InGaN layer, an (Al)GaN layer, and an InGaN layer are stacked in this order. The low-temperature buffer layer is made of GaN, aluminum nitride (AlN), AlGaN, or InGaN. The low-temperature buffer layer realizes lattice relaxation with the GaN substrate 2. By appropriately selecting the thickness and In composition of the InGaN layer laminated on the low-temperature buffer layer, the Al composition and thickness of the (Al)GaN layer, and the thickness and In composition of the InGaN layer above, it is possible to obtain the second underlayer 7Y having a desired second in-plane lattice constant a2 larger than the first in-plane lattice constant a1 of the GaN substrate 2 constituting the first region 81. In detail, an InGaN layer having an In composition of 10% and a thickness of 5 nm to 50 nm is formed on the GaN substrate 2 at a temperature condition of 500° C. to 600° C. Then, an InGaN layer having an In composition of 8% and a thickness of several tens to several hundreds of nm is laminated on the InGaN layer at a temperature condition of 700° C. to 900° C. Furthermore, a GaN layer having a thickness of several tens of nm is laminated on the InGaN layer, and then an InGaN layer having an In composition of 8% and a thickness of several tens to several hundreds of nm is laminated to form a second underlayer 7Y having a laminate structure.

[0090] The configuration of the blue light emitting element 3B is similar to that of the blue light emitting element 3B of the first embodiment. The yellow light emitting element 3Y emits yellow light having a peak wavelength of, for example, 570 nm. The yellow light emitting element 3Y is configured by sequentially stacking a yellow n-type semiconductor layer 4Y as a second lower semiconductor layer, a yellow light emitting layer 5Y as a second light emitting layer, and a yellow p-type semiconductor layer 6Y as a second upper semiconductor layer. Furthermore, the yellow light emitting element 3Y includes a yellow n-electrode (not shown) electrically connected to the yellow n-type semiconductor layer 4Y and a yellow p-electrode (not shown) electrically connected to the yellow p-type semiconductor layer 6Y, and light emission can be controlled individually for each light emitting element.

[0091] Regardless of the color, the n-type semiconductor layer 4, the light-emitting layer 5, and the p-type semiconductor layer 6 that constitute the light-emitting element 3 are made of Al. m In n Ga (1-m-n)It consists of N (0≦m<1, 0<n<1). The light-emitting elements 3 of each color are composed of the same elements, but have different element compositions. The n-type semiconductor layers 4 of each color are composed of the same elements but have different element compositions, specifically different In compositions. The light-emitting layers 5 of each color are composed of the same elements but have different element compositions, specifically different In compositions. The p-type semiconductor layers 6 of each color are composed of the same elements but have different element compositions, specifically different In compositions.

[0092] The In composition of the n-type semiconductor layer 4Y for yellow of the yellow light-emitting element 3Y is 2.5%, the In composition of the light-emitting layer 5Y for yellow is 27%, and the In composition of the p-type semiconductor layer 6Y for yellow is 2.5%. From the viewpoint of suitable yellow light emission, the In composition of the light-emitting layer 5Y for yellow is preferably 25% or more and 29% or less, more preferably 26% or more and 28% or less.

[0093] Also in the manufacturing process of the multi-wavelength light source 20 of the present embodiment, similar to the above embodiment, the n-type semiconductor layer 4B for blue and the n-type semiconductor layer 4Y for yellow can be formed together. Similarly, the light-emitting layer 5B for blue and the light-emitting layer 5Y for yellow can be formed together, and the p-type semiconductor layer 6B for blue and the p-type semiconductor layer 6Y for yellow can be formed together.

[0094] Thus, also in the present embodiment, by arbitrarily controlling the in-plane lattice constant of the region that becomes the growth surface of the light-emitting element, the emission wavelength of the formed light-emitting element can be easily controlled, and the wavelength controllability of the light-emitting elements of each color is excellent. Further, also in the present embodiment, the size of the region that becomes the growth surface of the light-emitting element and the size of each light-emitting element can be arbitrarily selected by a mask formation process using photolithography. Therefore, the controllability of the light-emitting element size is high, and a multi-wavelength light source having a desired size and emission intensity can be obtained.

[0095] [Sixth Embodiment] The multi-wavelength light source of each of the first to fourth embodiments is provided with three-color light-emitting elements that emit red, blue, and green light, and the multi-wavelength light source of the fifth embodiment is provided with two-color light-emitting elements that emit blue and yellow light, but is not limited thereto. The number of light-emitting elements with different emission wavelengths provided in the multi-wavelength light source can be two or more colors, and for example, four-color light-emitting elements may be used as in the present embodiment. Hereinafter, a multi-wavelength light source 21 provided with four color light-emitting elements will be described with reference to Fig. 17. The multi-wavelength light source 21 can be used, for example, for color display or illumination of a display device. In this embodiment, in addition to blue, green, and red light-emitting elements, yellow light-emitting elements are further provided, and the light source can be applied, for example, to an illumination device with high color rendering properties or a display device with a wide color gamut.

[0096] FIG. 17 is a partial schematic cross-sectional view of a multi-wavelength light source according to the sixth embodiment. As shown in Figure 17, the multi-wavelength light source 21 has a GaN substrate 2, a second underlying layer 7G, a third underlying layer 7Y, a fourth underlying layer 7R, a blue light-emitting element 3B as a first light-emitting element, a green light-emitting element 3G as a second light-emitting element, a yellow light-emitting element 3Y as a third light-emitting element, and a red light-emitting element 3R as a fourth light-emitting element.

[0097] The GaN substrate 2 has a first in-plane lattice constant a1. A part of the surface of the GaN substrate 2 constitutes a first region 81, which serves as a growth surface for growing the blue light emitting element 3B. The blue light emitting element 3B is provided on the first region 81 of the GaN substrate 2. The second underlayer 7G is provided on the GaN substrate 2, and the surface of the second underlayer 7G constitutes a second region 82. The surface of the second underlayer 7G has a second in-plane lattice constant a2. The second region 82 serves as a growth surface for growing the green light-emitting element 3G. The green light-emitting element 3G is provided on the second region 82. The third underlayer 7Y is provided on the GaN substrate 2, and the surface of the third underlayer 7Y constitutes a third region 83. The surface of the third underlayer 7Y has a third in-plane lattice constant a3. The third region 83 serves as a growth surface for growing the yellow light-emitting element 3Y. The yellow light-emitting element 3Y is provided on the third region 83. The fourth underlayer 7R is provided on the GaN substrate 2, and the surface of the fourth underlayer 7R constitutes a fourth region 84. The surface of the fourth underlayer 7R has a fourth in-plane lattice constant a4. The fourth region 84 serves as a growth surface for growing the red light emitting element 3R. The red light emitting element 3R is provided on the fourth region 84.

[0098] The configurations of the n-type semiconductor layer 4, light emitting layer 5, and p-type semiconductor layer 6 constituting the blue, green, and red light emitting elements 3 are similar to those of the blue, green, and red light emitting elements 3 of the first embodiment. The yellow light emitting element 3Y is similar to the yellow light emitting element 3Y in the fourth embodiment. The elemental composition and in-plane lattice constant of the second underlayer 7G are the same as those of the second underlayer 7G of the first embodiment. The elemental composition and in-plane lattice constant of the third underlayer 7Y of the present embodiment are the same as those of the second underlayer 7Y of the fourth embodiment. The elemental composition and in-plane lattice constant of the fourth underlayer 7R of the present embodiment are the same as those of the third underlayer 7R of the first embodiment.

[0099] In this embodiment, similarly to the above-described embodiment, by varying the lattice constant of the region in which the light emitting element is formed, the emission wavelength of the light emitting element formed on that region can be varied. In the multi-wavelength light source 21 of the present embodiment, the in-plane lattice constants of the regions corresponding to the light-emitting elements of each color increase in the order of the first region 81 for the blue light-emitting element 3B, the second region 82 for the green light-emitting element 3G, the third region 83 for the yellow light-emitting element 3Y, and the fourth region 84 for the red light-emitting element 3R. The In composition in the light-emitting layers of the light-emitting elements of each color increases in the order of the blue light-emitting layer 5B, the green light-emitting layer 5G, the yellow light-emitting layer 5Y, and the red light-emitting layer 5R.

[0100] In the configuration of this embodiment, similarly to the above embodiment, the n-type semiconductor layer 4, the light emitting layer 5, and the p-type semiconductor layer 6 for each color can be formed simultaneously.

[0101] In this manner, also in this embodiment, the emission wavelength of the light-emitting element formed can be easily controlled by arbitrarily controlling the in-plane lattice constant of the region that becomes the growth surface of the light-emitting element, and the wavelength controllability of the light-emitting elements of each color is excellent. Also in this embodiment, the size of the light emitting elements is highly controllable.

[0102] [Seventh embodiment] Hereinafter, a multi-wavelength light source 22 provided with light-emitting elements of four colors will be described with reference to FIG. 18. In this embodiment, in addition to blue, green, and red, the light-emitting element further includes a light-emitting element that emits infrared light (hereinafter, sometimes referred to as IR). In this way, a multi-wavelength light source including a light-emitting element that emits visible light and a light-emitting element that emits light other than visible light may be used. Here, infrared light is given as an example of invisible light, but is not limited to this and may be, for example, ultraviolet light, etc.

[0103] FIG. 18 is a partial schematic cross-sectional view of a multi-wavelength light source according to the seventh embodiment. As shown in Figure 18, the multi-wavelength light source 22 has a GaN substrate 2, a second underlayer 7G, a third underlayer 7R, a fourth underlayer 7IR, a blue light-emitting element 3B as a first light-emitting element, a green light-emitting element 3G as a second light-emitting element, a red light-emitting element 3R as a third light-emitting element, and an infrared light-emitting element 3IR as a fourth light-emitting element.

[0104] The GaN substrate 2 has a first in-plane lattice constant a1. A part of the surface of the GaN substrate 2 constitutes a first region 81, which serves as a growth surface for growing the blue light emitting element 3B. The blue light emitting element 3B is provided on the first region 81 of the GaN substrate 2. The second underlayer 7G is provided on the GaN substrate 2, and the surface of the second underlayer 7G constitutes a second region 82. The surface of the second underlayer 7G has a second in-plane lattice constant a2. The second region 82 serves as a growth surface for growing the green light-emitting element 3G. The green light-emitting element 3G is provided on the second region 82. The third underlayer 7R is provided on the GaN substrate 2, and the surface of the third underlayer 7R constitutes a third region 83. The surface of the third underlayer 7R has a third in-plane lattice constant a3. The third region 83 serves as a growth surface for growing the red light emitting element 3R. The red light emitting element 3R is provided on the third region 83. The fourth underlayer 7IR is provided on the GaN substrate 2, and the surface of the fourth underlayer 7IR constitutes a fourth region 84. The surface of the fourth underlayer 7IR has a fourth in-plane lattice constant a4. The fourth region 84 serves as a growth surface when growing the infrared light-emitting element 3IR. The infrared light-emitting element 3IR is provided on the fourth region 84.

[0105] The infrared light emitting element 3IR emits infrared light having a peak wavelength of, for example, 850 nm. The infrared light emitting element 3IR is configured by sequentially stacking an infrared n-type semiconductor layer 4IR as a fourth lower semiconductor layer, an infrared light emitting layer 5IR as a fourth light emitting layer, and an infrared p-type semiconductor layer 6IR as a fourth upper semiconductor layer. Furthermore, the infrared light emitting element 3IR includes an infrared n-electrode (not shown) electrically connected to the infrared n-type semiconductor layer 4IR, and an infrared p-electrode (not shown) electrically connected to the infrared p-type semiconductor layer 6IR, and light emission can be controlled individually for each light emitting element.

[0106] In the example shown in FIG. 18, the blue light emitting element 3B, the green light emitting element 3G, the red light emitting element 3R and the infrared light emitting element 3IR are configured separately from one another.

[0107] In this embodiment, similarly to the above-described embodiment, by varying the lattice constant of the region in which the light emitting element is formed, the emission wavelength of the light emitting element formed on that region can be varied. In the multi-wavelength light source 22 of the present embodiment, the in-plane lattice constant a1 of the first region 81 is the same as the in-plane lattice constant a1 of the first region in the first embodiment. The element composition and in-plane lattice constant of each of the second underlying layer 7G and the third underlying layer 7R are the same as those of the second underlying layer 7G and the third underlying layer 7R in the first embodiment. The fourth underlying layer 7IR is composed of Al x5 In y5 Ga (1-x5-y5) N (0 ≦ x5 < 1, 0 < y5 < 1). The in-plane lattice constant a4 of the fourth region 84 formed from the surface of the fourth underlying layer 7IR is 3.245 Å. From the viewpoint of forming the infrared light-emitting element 3IR, the in-plane lattice constant a4 of the fourth region 84 is preferably 3.235 Å or more and 3.255 Å or less, more preferably 3.238 Å or more and 3.252 Å or less.

[0108] The fourth underlying layer 7IR can have a desired fourth in-plane lattice constant by controlling the element composition such as the In composition and the stacking structure. As a specific example, the fourth underlying layer 7IR can have a stacked structure in which a low-temperature buffer layer, an InGaN layer, an (Al)GaN layer, and an InGaN layer are stacked in this order. The low-temperature buffer layer is GaN, aluminum nitride (AlN), AlGaN, or InGaN. The low-temperature buffer layer realizes lattice relaxation with the GaN substrate 2. By appropriately selecting the thickness and In composition of the InGaN layer stacked on the low-temperature buffer layer, the Al composition and thickness of the (Al)GaN layer, and the thickness and In composition of the upper InGaN layer, a fourth underlying layer 7IR having a desired fourth in-plane lattice constant a4 larger than the first, second, and third in-plane lattice constants can be obtained. Specifically, an InGaN layer with an In composition of 10% and a thickness of 5 nm to 50 nm is formed on the GaN substrate 2 under a temperature condition of 500°C to 600°C. Then, an InGaN layer with an In composition of 16% and a thickness of several tens of nm to several hundreds of nm is stacked on the InGaN layer under a temperature condition of 700°C to 900°C. Further, after stacking a GaN layer with a thickness of several tens of nm on the InGaN layer, an InGaN layer with an In composition of 16% and a thickness of several tens of nm to several hundreds of nm is stacked to form the fourth underlying layer 7IR of the stacked structure.

[0109] The elemental compositions of the n-type semiconductor layer 4, light-emitting layer 5, and p-type semiconductor layer 6 constituting the blue, green, and red light-emitting elements 3 are the same as those of the blue, green, and red light-emitting elements 3 of the first embodiment.

[0110] In this embodiment, similarly to the above-described embodiment, by varying the lattice constant of the region in which the light emitting element is formed, the emission wavelength of the light emitting element formed on that region can be varied. In the multi-wavelength light source 22 of the present embodiment, the in-plane lattice constants of the regions corresponding to the light-emitting elements of each color increase in the order of the first region 81 for the blue light-emitting element 3B, the second region 82 for the green light-emitting element 3G, the third region 83 for the red light-emitting element 3R, and the fourth region 84 for the infrared light-emitting element 3IR. The In composition in the light-emitting layers of the light-emitting elements of each color increases in the order of the blue light-emitting layer 5B, the green light-emitting layer 5G, the red light-emitting layer 5R, and the infrared light-emitting layer 5IR.

[0111] In the configuration of this embodiment, similarly to the above embodiment, the n-type semiconductor layers 4 of each color can be formed collectively. Similarly, the light-emitting layers 5 of each color can be formed collectively, and the p-type semiconductor layers 6 of each color can be formed collectively.

[0112] In this manner, also in this embodiment, the emission wavelength of the light-emitting element formed can be easily controlled by arbitrarily controlling the in-plane lattice constant of the region that becomes the growth surface of the light-emitting element, and the wavelength controllability of the light-emitting elements of each color is excellent. Also in this embodiment, the size of the light emitting elements is highly controllable.

[0113] [Other configuration examples] The embodiments of the present technology are not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present technology.

[0114] For example, in the above-described first to fourth embodiments, one pixel is composed of one blue light emitting element, one green light emitting element, and one red light emitting element, but the present invention is not limited to this. For example, when the light emission intensity from the red light emitting element is lower than that of the other colors, one pixel may be configured from one blue light emitting element 3B, one green light emitting element 3G, and two red light emitting elements 3R, as shown in Figures 19(A) and (B), and the arrangement is not limited. Also, as shown in Figure 19(C), one pixel may be configured from one blue light emitting element, one green light emitting element, and one red light emitting element, with the area of ​​the red light emitting element 3R being larger than that of the blue light emitting element 3B and the green light emitting element 3G. The size of the region that becomes the growth surface of the light emitting element, the size of each light emitting element, and the arrangement of the light emitting elements can be arbitrarily selected by a mask formation process using photolithography.

[0115] The present technology can also be configured as follows. (1) a first light emitting element provided on a first region having a first in-plane lattice constant, the first light emitting element being formed by sequentially stacking a first lower semiconductor layer, a first light emitting layer, and a first upper semiconductor layer; a second lower semiconductor layer provided on a second region having a second in-plane lattice constant different from the first in-plane lattice constant; a second light emitting layer composed of the same elements as the first light emitting layer but having a different elemental composition; and a second upper semiconductor layer laminated in this order; A multi-wavelength light source comprising: (2) The multi-wavelength light source according to (1) above, the first region is made of gallium nitride or a nitride containing gallium and indium, and the second region is made of a nitride containing gallium and indium, The first light emitting element and the second light emitting element are each made of a nitride containing gallium and indium. Multi-wavelength light source. (3) The multi-wavelength light source according to (2) above, The first light-emitting layer and the second light-emitting layer have different indium compositions. Multi-wavelength light source. (4) The multi-wavelength light source according to any one of (1) to (3) above, a substrate having the first in-plane lattice constant constituting the first region; a second underlayer that is provided on a portion of the substrate and that constitutes the second region; A multi-wavelength light source comprising: (5) The multi-wavelength light source according to (4) above, the substrate is made of gallium nitride; The second underlayer is made of a nitride containing gallium and indium. Multi-wavelength light source. (6) The multi-wavelength light source according to any one of (1) to (3) above, A substrate; a first underlayer provided on a portion of the substrate and constituting the first region; a second underlayer provided on another portion of the substrate and constituting the second region; A multi-wavelength light source comprising: (7) The multi-wavelength light source according to (6) above, the first underlayer is made of gallium nitride or a nitride containing gallium and indium; The second underlayer is made of a nitride containing gallium and indium. Multi-wavelength light source. (8) The multi-wavelength light source according to any one of (1) to (3) above, A substrate; a first underlayer provided on the substrate, a portion of which constitutes the first region; a second undercoat layer that is provided on the first undercoat layer in a region other than the first region and that constitutes the second region; A multi-wavelength light source comprising: (9) The multi-wavelength light source according to (8) above, the first underlayer is made of gallium nitride; The second underlayer is made of a nitride containing gallium and indium. Multi-wavelength light source. (10) A multi-wavelength light source according to any one of (1) to (9), the first lower semiconductor layer and the second lower semiconductor layer are composed of the same elements but have different elemental compositions; the first upper semiconductor layer and the second upper semiconductor layer are composed of the same elements but have different elemental compositions; The first light emitting layer and the second light emitting layer are separated, and the first upper semiconductor layer and the second upper semiconductor layer are separated. Multi-wavelength light source. (11) A multi-wavelength light source according to any one of (1) to (10) above, the first light emitting element includes a first lower electrode electrically connected to the first lower semiconductor layer and a first upper electrode electrically connected to the first upper semiconductor layer; the second light emitting element includes a second lower electrode electrically connected to the second lower semiconductor layer and a second upper electrode electrically connected to the second upper semiconductor layer; The first upper electrode and the second upper electrode are separated from each other. Multi-wavelength light source. (12) A multi-wavelength light source according to any one of (1) to (11), The elemental composition of the first region is different from that of the second region. Multi-wavelength light source. (13) A multi-wavelength light source according to any one of (1) to (12) above, At least one of the first region and the second region is constituted by a surface of a layer having a multilayer structure composed of a plurality of layers having different elemental compositions. Multi-wavelength light source. (14) A multi-wavelength light source according to any one of (1) to (13), a third lower semiconductor layer provided on a third region having a third lattice constant different from the first in-plane lattice constant and the second in-plane lattice constant; a third light emitting layer composed of the same elements as the first light emitting layer and the second light emitting layer but having a different elemental composition; and a third upper semiconductor layer laminated in this order. The multi-wavelength light source further comprises: (15) forming a first lower semiconductor layer on the first region having a first in-plane lattice constant; forming a first light emitting layer on the first lower semiconductor layer; forming a first upper semiconductor layer on the first light emitting layer; forming a second lower semiconductor layer on a second region having a second in-plane lattice constant different from the first in-plane lattice constant; forming a second light emitting layer on the second lower semiconductor layer; A second upper semiconductor layer is formed on the second light emitting layer. A method for manufacturing a multi-wavelength light source. (16) A method for producing a multi-wavelength light source according to (15) above, forming the first lower semiconductor layer and the second lower semiconductor layer together; forming the first light-emitting layer and the second light-emitting layer together; The first upper semiconductor layer and the second upper semiconductor layer are formed together. A method for manufacturing a multi-wavelength light source. (17) A method for manufacturing a multi-wavelength light source according to (15) or (16), Before forming the first lower semiconductor layer and the second lower semiconductor layer, forming a mask on a substrate having the first in-plane lattice constant, a portion of which constitutes the first region, the mask partially covering the substrate including at least the portion; A second underlayer having the second in-plane lattice constant is formed on the substrate through the mask to form the second region. The method for manufacturing a multi-wavelength light source further comprises: (18) A method for manufacturing a multi-wavelength light source according to (15) or (16), Before forming the first lower semiconductor layer and the second lower semiconductor layer, forming a first underlayer having the first in-plane lattice constant on the entire surface of the substrate, the first underlayer being a part of the first region; forming a mask on the first underlayer so as to partially cover the first underlayer including at least the portion; forming a second underlayer having the second in-plane lattice constant on the first underlayer through the mask to form the second region; The method for manufacturing a multi-wavelength light source further comprises: (19) A method for manufacturing a multi-wavelength light source according to (15) or (16), Before forming the first lower semiconductor layer and the second lower semiconductor layer, forming a first mask partially covering the substrate; forming a first underlayer having the first in-plane lattice constant on the substrate through the first mask to form the first region; removing the first mask; forming a second mask on the substrate, the second mask including at least the first underlayer and partially covering the substrate; forming a second underlayer having the second in-plane lattice constant on the substrate through the second mask to form the second region; The method for manufacturing a multi-wavelength light source further comprises: (20) a first light emitting element provided on a first region having a first in-plane lattice constant, the first light emitting element being formed by sequentially stacking a first lower semiconductor layer, a first light emitting layer, and a first upper semiconductor layer; a second lower semiconductor layer provided on a second region having a second in-plane lattice constant different from the first in-plane lattice constant; a second light emitting layer composed of the same elements as the first light emitting layer but having a different elemental composition; and a second upper semiconductor layer laminated in this order; A multi-wavelength light source comprising: A display device comprising: [Explanation of symbols]

[0116] 1, 10, 15, 18, 20, 21, 22...Multi-wavelength light source 2...GaN substrate (substrate made of gallium nitride) 3B...Blue light emitting element (first light emitting element) 3G: Green light emitting element (second light emitting element) 3R: Red light emitting element (third light emitting element) 3Y... Yellow light emitting element (second light emitting element, third light emitting element) 3IR: Infrared light emitting element (light emitting element) 4B: Blue n-type semiconductor layer (first lower semiconductor layer) 4G: Green n-type semiconductor layer (second lower semiconductor layer) 4R: Red n-type semiconductor layer (third lower semiconductor layer) 4Y: Yellow n-type semiconductor layer (second lower semiconductor layer, third lower semiconductor layer) 4IR: Infrared n-type semiconductor layer (lower semiconductor layer) 5B: Blue light-emitting layer (first light-emitting layer) 5G…Green light-emitting layer (second light-emitting layer) 5R: Red light emitting layer (third light emitting layer) 5Y: Yellow light-emitting layer (second light-emitting layer, third light-emitting layer) 5IR…Infrared light emitting layer (light emitting layer) 6B: Blue p-type semiconductor layer (first upper semiconductor layer) 6G: Green p-type semiconductor layer (second upper semiconductor layer) 6R: Red p-type semiconductor layer (third upper semiconductor layer) 6Y... Yellow p-type semiconductor layer (second upper semiconductor layer, third upper semiconductor layer) 6IR: Infrared p-type semiconductor layer (upper semiconductor layer) 7G…Second base layer 7R…Third base layer 8B: Blue n-electrode (first lower electrode) 8G: Green n-electrode (second lower electrode) 8R...Red n-electrode (third lower electrode) 9B...Blue p-electrode (first upper electrode) 9G…Green p-electrode (second upper electrode) 9R…Red p-electrode (third upper electrode) 12...Substrate 14, 17, 19…First base layer 71...First Mask (Mask) 73...First Mask 74...Second Mask 76...First Mask (Mask) 81...First area 82...Second Area 83…Third Region

Claims

1. a first light emitting element provided on a first region having a first in-plane lattice constant, the first light emitting element being formed by sequentially stacking a first lower semiconductor layer, a first light emitting layer, and a first upper semiconductor layer; a second lower semiconductor layer provided on a second region having a second in-plane lattice constant different from the first in-plane lattice constant; a second light emitting layer composed of the same elements as the first light emitting layer but having a different elemental composition; and a second upper semiconductor layer laminated in this order; Equipped with the first region is made of gallium nitride or a nitride containing gallium and indium, and the second region is made of a nitride containing gallium and indium, The first light emitting element and the second light emitting element are each made of a nitride containing gallium and indium. Multi-wavelength light source.

2. 2. The multi-wavelength light source according to claim 1, The first light emitting layer and the second light emitting layer have different indium compositions. Multi-wavelength light source.

3. 2. The multi-wavelength light source according to claim 1, a substrate having the first in-plane lattice constant constituting the first region; a second underlayer that is provided on a portion of the substrate and that constitutes the second region; A multi-wavelength light source comprising:

4. 4. The multi-wavelength light source according to claim 3, the substrate is made of gallium nitride; The second underlayer is made of a nitride containing gallium and indium. Multi-wavelength light source.

5. 2. The multi-wavelength light source according to claim 1, A substrate; a first underlayer provided on a portion of the substrate and constituting the first region; a second underlayer provided on another portion of the substrate and constituting the second region; A multi-wavelength light source comprising:

6. 6. The multi-wavelength light source according to claim 5, the first underlayer is made of gallium nitride or a nitride containing gallium and indium; The second underlayer is made of a nitride containing gallium and indium. Multi-wavelength light source.

7. 2. The multi-wavelength light source according to claim 1, A substrate; a first underlayer provided on the substrate, a portion of which constitutes the first region; a second undercoat layer that constitutes the second region and is provided on the first undercoat layer in a region other than the first region; A multi-wavelength light source comprising:

8. 8. A multi-wavelength light source according to claim 7, the first underlayer is made of gallium nitride; The second underlayer is made of a nitride containing gallium and indium. Multi-wavelength light source.

9. 2. The multi-wavelength light source according to claim 1, the first lower semiconductor layer and the second lower semiconductor layer are composed of the same elements but have different elemental compositions; the first upper semiconductor layer and the second upper semiconductor layer are composed of the same elements but have different elemental compositions; The first light emitting layer and the second light emitting layer are separated, and the first upper semiconductor layer and the second upper semiconductor layer are separated. Multi-wavelength light source.

10. 2. The multi-wavelength light source according to claim 1, the first light emitting element includes a first lower electrode electrically connected to the first lower semiconductor layer and a first upper electrode electrically connected to the first upper semiconductor layer; the second light emitting element includes a second lower electrode electrically connected to the second lower semiconductor layer and a second upper electrode electrically connected to the second upper semiconductor layer; The first upper electrode and the second upper electrode are separated from each other. Multi-wavelength light source.

11. 2. The multi-wavelength light source according to claim 1, The elemental composition of the first region is different from that of the second region. Multi-wavelength light source.

12. 2. The multi-wavelength light source according to claim 1, At least one of the first region and the second region is constituted by a surface of a layer having a multilayer structure composed of a plurality of layers having different elemental compositions. Multi-wavelength light source.

13. 2. The multi-wavelength light source according to claim 1, a third lower semiconductor layer provided on a third region having a third lattice constant different from the first in-plane lattice constant and the second in-plane lattice constant; a third light emitting layer composed of the same elements as the first light emitting layer and the second light emitting layer but having a different elemental composition; and a third upper semiconductor layer laminated in this order. The multi-wavelength light source further comprises:

14. forming a first lower semiconductor layer on the first region having a first in-plane lattice constant; forming a first light emitting layer on the first lower semiconductor layer; forming a first upper semiconductor layer on the first light emitting layer to form a first light emitting element; forming a second lower semiconductor layer on a second region having a second in-plane lattice constant different from the first in-plane lattice constant; forming a second light emitting layer on the second lower semiconductor layer; A second upper semiconductor layer is formed on the second light emitting layer to form a second light emitting element. A method for manufacturing a multi-wavelength light source, comprising the steps of: the first region is made of gallium nitride or a nitride containing gallium and indium, and the second region is made of a nitride containing gallium and indium, The first light emitting element and the second light emitting element are each made of a nitride containing gallium and indium. A method for manufacturing a multi-wavelength light source.

15. A method for manufacturing a multi-wavelength light source according to claim 14, comprising the steps of: The first lower semiconductor layer and the second lower semiconductor layer are formed together; The first light-emitting layer and the second light-emitting layer are formed simultaneously; The first upper semiconductor layer and the second upper semiconductor layer are formed together. A method for manufacturing a multi-wavelength light source.

16. A method for manufacturing a multi-wavelength light source according to claim 14, comprising the steps of: Prior to forming the first lower semiconductor layer and the second lower semiconductor layer, forming a mask on a substrate having the first in-plane lattice constant, a portion of which constitutes the first region, the mask partially covering the substrate including at least the portion; A second underlayer having the second in-plane lattice constant is formed on the substrate through the mask to form the second region. The method for manufacturing a multi-wavelength light source further comprises:

17. A method for manufacturing a multi-wavelength light source according to claim 14, comprising the steps of: Prior to forming the first lower semiconductor layer and the second lower semiconductor layer, forming a first underlayer having the first in-plane lattice constant on the entire surface of the substrate, the first underlayer being a part of the first region; forming a mask on the first underlayer so as to partially cover the first underlayer including at least the portion; A second underlayer having the second in-plane lattice constant is formed on the first underlayer through the mask to form the second region. The method for manufacturing a multi-wavelength light source further comprises:

18. A method for manufacturing a multi-wavelength light source according to claim 14, comprising the steps of: Prior to forming the first lower semiconductor layer and the second lower semiconductor layer, forming a first mask partially covering the substrate; forming a first underlayer having the first in-plane lattice constant on the substrate through the first mask to form the first region; removing the first mask; forming a second mask on the substrate, the second mask including at least the first underlayer and partially covering the substrate; A second underlayer having the second in-plane lattice constant is formed on the substrate through the second mask to form the second region. The method for manufacturing a multi-wavelength light source further comprises:

19. a first light emitting element provided on a first region having a first in-plane lattice constant, the first light emitting element being formed by sequentially stacking a first lower semiconductor layer, a first light emitting layer, and a first upper semiconductor layer; a second lower semiconductor layer provided on a second region having a second in-plane lattice constant different from the first in-plane lattice constant; a second light emitting layer composed of the same elements as the first light emitting layer but having a different elemental composition; and a second upper semiconductor layer laminated in this order; A multi-wavelength light source comprising: A display device comprising: the first region is made of gallium nitride or a nitride containing gallium and indium, and the second region is made of a nitride containing gallium and indium, The first light emitting element and the second light emitting element are each made of a nitride containing gallium and indium. Display device.

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