Light emitting device and substrate for forming light emitting device

Abstract

A light emitting device according to the present invention comprises a plurality of pixels that are arranged in a matrix in a first direction and a second direction that intersects with the first direction; each one of the plurality of pixels comprises an amorphous substrate, a semi-transmissive reflective layer on the amorphous substrate, a first insulating alignment layer on the semi-transmissive reflective layer, a first semiconductor layer on the first insulating alignment layer, a light emitting layer on the first semiconductor layer, a second semiconductor layer on the light emitting layer, and an electrode layer on the second semiconductor layer. Each one of the first semiconductor layer, the light emitting layer and the second semiconductor layer contains gallium nitride.

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a light emitting device including gallium nitride, and also to a light emitting device forming substrate on which a plurality of light emitting devices including gallium nitride are formed. [Background technology]

[0002] Gallium nitride (GaN) is characterized as a direct transition semiconductor with a wide band gap. Utilizing the characteristics of gallium nitride, light-emitting diodes (LEDs) using gallium nitride films have already been put to practical use. Gallium nitride films for LEDs are generally grown on sapphire substrates at high temperatures of 800°C to 1000°C using MOCVD (Metal Organic Chemical Vapor Deposition) or HVPE (Hydride Vapor Phase Epitaxy).

[0003] Recently, development of so-called micro LED display devices or mini LED display devices, which incorporate tiny LED chips in the pixels of a circuit board, has been progressing as next-generation display devices (or next-generation light-emitting devices). Micro LED display devices or mini LED display devices have high efficiency, high brightness, and high reliability. Such micro LED display devices or mini LED display devices are manufactured by transferring LED chips to a backplane on which thin-film transistors made of oxide semiconductors or low-temperature polysilicon are formed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 8,791,474 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the manufacturing method of micro LED displays by transferring LED chips is expensive, making it difficult to manufacture micro LED displays inexpensively. On the other hand, if LEDs could be formed on a large-area substrate such as an amorphous glass substrate, manufacturing costs could be reduced. However, as mentioned above, gallium nitride films are formed on sapphire substrates at high temperatures, making it difficult to form gallium nitride films directly on amorphous glass substrates.

[0006] Furthermore, even when a gallium nitride film is formed directly on an amorphous glass substrate, since gallium nitride is a high refractive index material, there is a need to improve the light extraction efficiency.

[0007] In view of the above problems, one embodiment of the present invention has an object to provide a light emitting device having improved light extraction efficiency, including a gallium nitride film formed on a large-area substrate such as an amorphous glass substrate, and another object of the present invention is to provide a light emitting device forming substrate on which a plurality of light emitting devices having improved light extraction efficiency, including a gallium nitride film, are formed. [Means for solving the problem]

[0008] A light-emitting device according to one embodiment of the present invention includes a plurality of pixels arranged in a matrix in a first direction and a second direction intersecting the first direction, each of the plurality of pixels including an amorphous substrate, a semi-transmissive reflective layer on the amorphous substrate, a first insulating orientation layer on the semi-transmissive reflective layer, a first semiconductor layer on the first insulating orientation layer, a light-emitting layer on the first semiconductor layer, a second semiconductor layer on the light-emitting layer, and an electrode layer on the second semiconductor layer, and each of the first semiconductor layer, the light-emitting layer, and the second semiconductor layer includes gallium nitride.

[0009] A light-emitting device according to one embodiment of the present invention includes a plurality of pixels arranged in a matrix in a first direction and a second direction intersecting the first direction, each of the plurality of pixels including an amorphous substrate, a first insulating orientation layer on the amorphous substrate, a semi-transmissive reflective layer on the first insulating orientation layer, a first semiconductor layer on the semi-transmissive reflective layer, a light-emitting layer on the first semiconductor layer, a second semiconductor layer on the light-emitting layer, and an electrode layer on the second semiconductor layer, and each of the first semiconductor layer, the light-emitting layer, and the second semiconductor layer includes gallium nitride.

[0010] A light-emitting device according to one embodiment of the present invention includes a plurality of pixels arranged in a matrix in a first direction and a second direction intersecting the first direction, each of the plurality of pixels including an amorphous substrate, a first insulating orientation layer on the amorphous substrate, an electrode layer on the first insulating orientation layer, a first semiconductor layer on the electrode layer, a light-emitting layer on the first semiconductor layer, a second semiconductor layer on the light-emitting layer, and a semi-transmissive reflective layer on the second semiconductor layer, and each of the first semiconductor layer, the light-emitting layer, and the second semiconductor layer includes gallium nitride.

[0011] A light emitting device forming substrate according to one embodiment of the present invention includes a plurality of the light emitting devices, and the amorphous substrate is a single substrate common to the plurality of light emitting devices. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram illustrating a configuration of a light-emitting device according to one embodiment of the present invention. [Figure 2] 1 is a schematic cross-sectional view showing a configuration of a pixel of a light-emitting device according to one embodiment of the present invention. [Figure 3] FIG. 3 is a schematic cross-sectional view showing the area of ​​FIG. 2. [Figure 4A] 1 is a schematic cross-sectional view showing a configuration of a pixel of a light-emitting device according to one embodiment of the present invention. [Figure 4B] 1 is a schematic cross-sectional view showing a configuration of a pixel of a light-emitting device according to one embodiment of the present invention. [Figure 5] FIG. 4C is a schematic cross-sectional view showing the area of ​​FIG. 4A or FIG. 4B. [Figure 6] 1 is a schematic cross-sectional view showing a configuration of a pixel of a light-emitting device according to one embodiment of the present invention. [Figure 7] FIG. 7 is a schematic cross-sectional view showing the area of ​​FIG. 6. [Figure 8] 1 is a schematic cross-sectional view showing a configuration of a pixel of a light-emitting device according to one embodiment of the present invention. [Figure 9] FIG. 9 is a schematic cross-sectional view showing the area of ​​FIG. 8. [Figure 10] 4 is a graph showing current efficiency versus change in chromaticity (y-coordinate of chromaticity coordinates) in a microcavity structure in the region shown in FIG. 3. [Figure 11] 6 is a graph showing current efficiency versus change in chromaticity (y coordinate of the chromaticity coordinates) in a microcavity structure in the region shown in FIG. 5. [Figure 12] 8 is a graph showing current efficiency versus change in chromaticity (y coordinate of the chromaticity coordinates) in a microcavity structure in the region shown in FIG. 7. [Figure 13] FIG. 10 is a schematic cross-sectional view showing a region of a comparative example that does not have a microcavity structure. [Figure 14] 14 is a graph showing current efficiency relative to changes in chromaticity (y coordinate of the chromaticity coordinates) in the structure of the region of the comparative example shown in FIG. [Figure 15] 1 is a schematic diagram showing a configuration of a light emitting device formation substrate according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. Note that each embodiment is merely an example, and any embodiment that a person skilled in the art could easily come up with by making appropriate modifications while maintaining the gist of the invention is naturally included in the scope of the present invention. Furthermore, in order to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment. However, the illustrated shapes are merely examples and do not limit the interpretation of the present invention.

[0014] In this specification, unless otherwise specified, expressions such as "α includes A, B, or C," "α includes any one of A, B, and C," and "α includes one selected from the group consisting of A, B, and C" do not exclude cases where α includes multiple combinations of A to C. Furthermore, these expressions do not exclude cases where α includes other elements.

[0015] In this specification, for the sake of convenience, the terms "above" or "upper" or "below" or "belower" are used. In principle, the substrate on which the structure is formed is used as the reference, and the direction from the substrate toward the structure is referred to as "above" or "upper." Conversely, the direction from the structure toward the substrate is referred to as "below" or "belower." Therefore, in the expression "structure on a substrate," the surface of the structure facing the substrate is the lower surface of the structure, and the surface opposite to that is the upper surface of the structure. Furthermore, the expression "structure on a substrate" merely describes the vertical relationship between the substrate and the structure, and other components may be disposed between the substrate and the structure. Furthermore, the terms "above" or "upper" or "below" or "belower" refer to the stacking order in a structure in which multiple layers are stacked, and do not necessarily have to be in an overlapping positional relationship in a planar view.

[0016] In this specification, the letters "first," "second," or "third" attached to each component are convenient labels used to distinguish each component, and have no other meaning unless otherwise specified.

[0017] In this specification and drawings, the same reference numerals are used to collectively represent multiple identical or similar components, and capital letters may be used to distinguish between these multiple components. Furthermore, a hyphen and lowercase letters may be used to distinguish between parts of a single component.

[0018] The following embodiments can be combined with each other unless a technical contradiction occurs.

[0019] First Embodiment The configuration of a light emitting device 100 according to one embodiment of the present invention will be described with reference to FIGS.

[0020] FIG. 1 is a schematic diagram illustrating the configuration of a light-emitting device 100 according to one embodiment of the present invention. The light-emitting device 100 includes a pixel section 100P and a terminal section 100T formed on an amorphous substrate 110. The pixel section 100P is formed in the center of the amorphous substrate 110, and the terminal section 100T is formed at an edge of the amorphous substrate 110. The pixel section 100P includes a plurality of pixels 100-px arranged in a first direction and a second direction perpendicular to (intersecting) the first direction. As will be described in detail below, each of the plurality of pixels 100-px includes a light-emitting diode (LED) formed on the amorphous substrate 110. The terminal section 100T includes a plurality of terminals 100-t. A power supply line is connected to each of the plurality of terminals 100-t, allowing a voltage to be applied (current to be supplied) to the LED in the pixel 100-px. Although not shown in detail, a thin-film transistor may be provided in the pixel 100-px to control the light emission of the LED.

[0021] FIG. 2 is a schematic cross-sectional view showing the configuration of a pixel 100-px of a light-emitting device 100 according to one embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing a region 300 of FIG. 2. As shown in FIG. 2, the pixel 100-px includes an amorphous substrate 110, a semi-transmissive reflective layer 120, an insulating alignment layer 130, a first semiconductor layer 140, an emitting layer 150, a second semiconductor layer 160, a first electrode layer 170, and a second electrode layer 180. That is, the pixel 100-px includes an LED including the first semiconductor layer 140, the emitting layer 150, the second semiconductor layer 160, the first electrode layer 170, and the second electrode layer 180. The LED included in the pixel 100-px has a so-called horizontal electrode structure in which the first electrode layer 170 and the second electrode layer 180 are provided on one side of the emitting layer 150. In the pixel 100-px, light emitted from the light-emitting layer 150 passes through the amorphous substrate 110 and is extracted.

[0022] The semi-transmissive reflective layer 120 is provided on the amorphous substrate 110. The semi-transmissive reflective layer 120 may be provided in common to a plurality of pixels 100-px.

[0023] The insulating alignment layer 130 is provided on the semi-transmissive reflective layer 120. The insulating alignment layer 130 may be provided in common to a plurality of pixels 100-px.

[0024] The first semiconductor layer 140, the light-emitting layer 150, and the second semiconductor layer 160 are provided in this order on the insulating alignment layer 130. The first semiconductor layer 140 may be provided in common to multiple pixels 100-px. Each of the light-emitting layer 150 and the second semiconductor layer 160 is provided in an island shape within the pixel 100-px. That is, the first semiconductor layer 140 includes regions that are not covered by the light-emitting layer 150 or the second semiconductor layer 160.

[0025] The first electrode layer 170 is provided on the first semiconductor layer 140. Specifically, the first electrode layer 170 is provided in a region not covered by the light-emitting layer 150 or the second semiconductor layer 160. The second electrode layer 180 is provided on the second semiconductor layer 160. Each of the first electrode layer 170 and the second electrode layer 180 is provided in an island shape within the pixel 100-px. In other words, the first electrode layer 170 and the second electrode layer 180 are electrically isolated from each other.

[0026] Although not shown, an insulating layer may be provided on the first semiconductor layer 140, the light-emitting layer 150, and the second semiconductor layer 160 so as to cover the light-emitting layer 150 and the second semiconductor layer 160. In this case, an opening is provided in the insulating layer. The first electrode layer 170 is provided so as to cover the opening in the insulating layer where the first semiconductor layer 140 is exposed, and the second electrode layer 180 is provided so as to cover the opening in the insulating layer where the second semiconductor layer 160 is exposed. In this case, at least one of the first electrode layer 170 and the second electrode layer 180 may be provided in an island shape within the pixel 100-px. The other of the first electrode layer 170 and the second electrode layer 180 may be provided in an island shape within the pixel 100-px, or may extend in a first direction or a second direction and be provided in common to a plurality of pixels 100-px arranged in the first direction or the second direction. In this case as well, the first electrode layer 170 and the second electrode layer 180 are electrically isolated from each other.

[0027] Next, the materials of each component will be described.

[0028] The amorphous substrate 110 is the base material (support substrate) of the light-emitting device 100. As will be described in detail later, in the light-emitting device 100, the first semiconductor layer 140, the light-emitting layer 150, and the second semiconductor layer 160 are each formed on the amorphous substrate 110 by sputtering. Therefore, the amorphous substrate 110 only needs to be heat-resistant to a relatively low temperature of, for example, approximately 400°C. The amorphous substrate 110 may be, for example, an amorphous glass substrate. Alternatively, a resin substrate such as a polyimide substrate, an acrylic substrate, a siloxane substrate, or a fluororesin substrate may be used instead of the amorphous substrate 110. Such an amorphous glass substrate or resin substrate can be made large. Alternatively, a polycrystalline substrate may be used instead of the amorphous substrate 110. A polycrystalline substrate can be made larger than a sapphire substrate, which is typically used in the formation of gallium nitride films, and can be used as the base material of the light-emitting device 100, similar to an amorphous glass substrate or a resin substrate. The amorphous substrate may be provided with a thin film transistor for controlling the LED.

[0029] To explain the amorphous substrate 110 in more detail, it is preferable that the amorphous substrate 110 has a low thermal expansion coefficient, a high strain point, and a high surface flatness. For example, the amorphous substrate 110 has a thermal expansion coefficient of 50×10 -7 / °C and a strain point of 600°C or higher. The amorphous substrate 110 only needs to be heat-resistant to about 400°C, and is not required to be heat-resistant to 1000°C or higher like a sapphire substrate. When the amorphous substrate 110 is an amorphous glass substrate, a glass substrate made of, for example, aluminoborosilicate glass or aluminosilicate glass can be used as the amorphous substrate 110 satisfying the above-mentioned characteristics. Such glass substrates are used in liquid crystal displays and organic electroluminescence (organic EL) displays, and large-area glass substrates known as "mother glass" are commercially available. Furthermore, the amorphous substrate 110 preferably contains 0.1% or less of an alkali metal, such as sodium (Na).

[0030] Although not shown, an underlayer may be provided on the amorphous substrate 110. The underlayer can prevent the diffusion of impurities from the amorphous substrate 110 or external impurities (e.g., moisture or sodium (Na)). The underlayer can be made of, for example, silicon nitride (SiN x ) film or the like can be used as the underlayer. x ) film and silicon nitride (SiN x ) film may also be used.

[0031] The semi-transmissive reflective layer 120 can transmit or reflect light emitted from the light-emitting layer 150 or light reflected by the second electrode layer 180. That is, the pixel 100-px includes a region 300 having a microcavity structure that repeatedly reflects light between the semi-transmissive reflective layer 120 and the second electrode layer 180. This improves the light extraction efficiency of the light-emitting device 100. Furthermore, the light-emitting device 100 exhibits little change in light extraction efficiency due to changes in chromaticity. The semi-transmissive reflective layer 120 can be made of, for example, a metal such as silver (Ag) or magnesium (Mg), or an alloy thereof. These metals or alloys have a thickness that allows the semi-transmissive reflective layer 120 to transmit light emitted from the light-emitting layer 150 or light reflected by the second electrode layer 180. For example, the thickness of the semi-transmissive reflective layer 120 is 1 nm to 50 nm, preferably 5 nm to 30 nm.

[0032] The insulating orientation layer 130 can improve the crystallinity of the first semiconductor layer 140 formed thereon. Specifically, the insulating orientation layer 130 can be controlled so that the first semiconductor layer 140 has a c-axis orientation. "A layer has a c-axis orientation" means that the c-axis of the crystal structure of the layer is oriented in a direction substantially perpendicular to the surface on which it is formed. The insulating orientation layer 130 can be made of an insulating material having a hexagonal close-packed structure, a face-centered cubic structure, or a structure equivalent thereto. Here, a hexagonal close-packed structure or a structure equivalent thereto includes a crystal structure in which the c-axis is not 90° relative to the a-axis and b-axis. An insulating orientation layer 130 made of an insulating material having a hexagonal close-packed structure or a structure equivalent thereto is oriented in the (0001) direction, i.e., the c-axis direction, relative to the amorphous substrate 110 (hereinafter referred to as the (0001) orientation of the hexagonal close-packed structure). Furthermore, the insulating orientation layer 130 made of a material having a face-centered cubic structure or a structure equivalent thereto is oriented in the (111) direction relative to the amorphous substrate 110 (hereinafter referred to as the (111) orientation of the face-centered cubic structure). When the insulating orientation layer 130 has the (0001) orientation of the hexagonal close-packed structure or the (111) orientation of the face-centered cubic structure, crystal growth in the c-axis direction of the film formed on the insulating orientation layer 130 is promoted, and the first semiconductor layer 140 on the insulating orientation layer 130 has c-axis orientation. For example, aluminum nitride (AlN x ), aluminum oxide (AlO x ), lithium niobate (LiNbO), BiLaTiO, SrFeO, BiFeO, BaFeO, ZnFeO, PMnN-PZT, or biological apatite (BAp) can be used. The insulating orientation layer 130 can be formed using any method (apparatus) such as sputtering or CVD.

[0033] The crystallinity of the first semiconductor layer 140 on the insulating orientation layer 130 is affected by the surface condition of the insulating orientation layer 130. Therefore, it is preferable that the insulating orientation layer 130 has a smooth surface with little unevenness. For example, the arithmetic mean roughness (Ra) of the surface of the insulating orientation layer 130 is preferably smaller than 2.3 nm. Furthermore, it is preferable that the root mean square roughness (Rq) of the surface of the insulating orientation layer 130 is smaller than 2.9 nm. When the surface roughness of the insulating orientation layer 130 satisfies these conditions, the first semiconductor layer 140 has a c-axis orientation with higher crystallinity. It is preferable that the film thickness of the insulating orientation layer 130 is 50 nm or more.

[0034] One of the first semiconductor layer 140 and the second semiconductor layer 160 transports electrons and injects electrons into the light-emitting layer 150. That is, one of the first semiconductor layer 140 and the second semiconductor layer 160 is an n-type semiconductor layer. For example, a gallium nitride film doped with silicon (Si) can be used as the n-type semiconductor layer. The other of the first semiconductor layer 140 and the second semiconductor layer 160 transports holes and injects holes into the light-emitting layer 150. That is, the other of the first semiconductor layer 140 and the second semiconductor layer 160 is a p-type semiconductor layer. For example, a gallium nitride film doped with magnesium (Mg) can be used as the p-type semiconductor layer. A gallium nitride film doped with silicon or magnesium can be formed by sputtering.

[0035] The light-emitting layer 150 recombines the injected electrons and holes to emit light. The light-emitting layer 150 has a multiple quantum well structure. For example, a laminated film in which indium gallium nitride (InGaN) films and gallium nitride films are alternately stacked can be used as the light-emitting layer 150. The indium gallium nitride film or the gallium nitride film can be formed by sputtering.

[0036] Here, a method for forming a gallium nitride film on the insulating orientation layer 130 using sputtering will be described.

[0037] An amorphous substrate 110 on which an insulating orientation layer 130 has been formed is placed in a vacuum chamber, facing the gallium nitride target. The gallium nitride composition ratio in the gallium nitride target is preferably 0.7 to 2 (gallium to nitrogen). Nitrogen can be supplied to the vacuum chamber separately from the sputtering gas (argon, krypton, etc.). In this case, the gallium nitride composition ratio in the gallium nitride target is preferably higher in gallium than in nitrogen. For example, nitrogen can be supplied using a nitrogen radical supply source. The sputtering power supply may be a DC power supply, an RF power supply, or a pulsed DC power supply.

[0038] The amorphous substrate 110 in the vacuum chamber may be heated. For example, the amorphous substrate 110 can be heated from room temperature to less than 600°C. Preferably, the temperature is 100°C or higher and 400°C or lower. This temperature is lower than the film formation temperature of MOCVD or HVPE, and can be applied to an amorphous substrate 110 that has lower heat resistance than a sapphire substrate.

[0039] After the vacuum chamber is fully evacuated, a sputtering gas is supplied, and a voltage is applied between the amorphous substrate 110 and the gallium nitride target at a predetermined pressure to generate plasma, which deposits a gallium nitride film.

[0040] Although the method for forming a gallium nitride film by sputtering has been described above, the configuration or conditions of the sputtering can be changed as appropriate. Furthermore, if a silicon-doped gallium nitride target or a magnesium-doped gallium nitride target is used instead of a gallium nitride target, an n-type semiconductor film or a p-type semiconductor film can be formed. Furthermore, if an indium gallium nitride target or a gallium nitride target is used, a laminated film in which indium gallium nitride films and gallium nitride films are alternately stacked can be formed.

[0041] In the light-emitting device 100, the first semiconductor layer 140, the light-emitting layer 150, and the second semiconductor layer 160 each contain gallium nitride. The gallium nitride film of the first semiconductor layer 140 is deposited directly on the insulating orientation layer 130, but the gallium nitride films of the light-emitting layer 150 and the second semiconductor layer 160 are not deposited directly on the insulating orientation layer 130. However, because the first semiconductor layer 140 on the insulating orientation layer 130 has a highly crystalline c-axis orientation, the first semiconductor layer 140 functions similarly to the insulating orientation layer 130. This promotes crystal growth in the c-axis direction of the gallium nitride film deposited on the first semiconductor layer 140, and the light-emitting layer 150 on the first semiconductor layer 140 has a c-axis orientation. Similarly, the second semiconductor layer 160 on the light-emitting layer 150 also has a c-axis orientation.

[0042] One of the first electrode layer 170 and the second electrode layer 180 is an n-type electrode, and the other of the first electrode layer 170 and the second electrode layer 180 is a p-type electrode. The polarity of the first electrode layer 170 and the second electrode layer 180 is determined depending on the first semiconductor layer 140 and the second semiconductor layer 160. For example, a metal such as silver (Ag) or indium (In), or an alloy thereof, can be used as the n-type electrode. For example, a metal such as palladium (Pd) or gold (Au), or an alloy thereof can be used as the p-type electrode. These metals or alloys have a thickness that does not transmit light emitted from the light-emitting layer 150 or light reflected by the semi-transmissive reflective layer 120.

[0043] Although not shown, a protective layer can be provided to cover the LED as needed. A silicon nitride film can be used as the protective layer. Alternatively, a laminated film of a silicon oxide film and a silicon nitride film can be used as the protective layer.

[0044] As described above, the light emitting device 100 according to this embodiment includes the region 300 having a microcavity structure. Therefore, the light emitting device 100 has improved light extraction efficiency and little change in light extraction efficiency due to chromaticity change. Furthermore, in the light emitting device 100, the LED is formed using the amorphous substrate 110, so the manufacturing cost of the light emitting device 100 can be reduced.

[0045] Second Embodiment 4A to 5, another configuration of the light emitting device 100 according to one embodiment of the present invention will be described. Note that, in the following, description of the same configuration as the above-described configuration may be omitted.

[0046] 4A and 4B are schematic cross-sectional views showing the configurations of pixels 100A1-px and 100A2-px, respectively, of a light-emitting device 100 according to one embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing region 300A of FIG. 4A or 4B. As shown in FIG. 4A, pixel 100A1-px includes an amorphous substrate 110, an insulating alignment layer 130A, a semi-transmissive reflective layer 120A, a first semiconductor layer 140, an emitting layer 150, a second semiconductor layer 160, a first electrode layer 170, and a second electrode layer 180. That is, pixel 100A1-px includes an LED including the first semiconductor layer 140, the emitting layer 150, the second semiconductor layer 160, the first electrode layer 170, and the second electrode layer 180. The LED included in pixel 100A1-px has a so-called horizontal electrode structure in which a first electrode layer 170 and a second electrode layer 180 are provided on one side of light-emitting layer 150. In pixel 100A1-px, light emitted from light-emitting layer 150 passes through amorphous substrate 110 and is extracted.

[0047] As shown in FIG. 4B , the pixel 100A2-px includes an amorphous substrate 110, an insulating alignment layer 130A, a semi-transmissive reflective layer 120A, a first semiconductor layer 140, a light-emitting layer 150, a second semiconductor layer 160, and a second electrode layer 180. As will be described in detail later, the semi-transmissive reflective layer 120A can function as an electrode for an LED. Therefore, the pixel 100A2-px includes an LED including the semi-transmissive reflective layer 120A, the first semiconductor layer 140, the light-emitting layer 150, the second semiconductor layer 160, and the second electrode layer 180. The LED included in the pixel 100A2-px has a so-called vertical electrode structure in which the semi-transmissive reflective layer 120A, which functions as an electrode, is provided on one side of the light-emitting layer 150, and the second electrode layer 180 is provided on the other side of the light-emitting layer 150. In the pixel 100A2-px, the light emitted from the light-emitting layer 150 passes through the amorphous substrate 110 and is extracted.

[0048] Note that the pixel 100A1-px and the pixel 100A2-px both include a region 300A having a microcavity structure that repeatedly reflects light between the semi-transmissive reflective layer 120A and the second electrode layer 180.

[0049] In each of the pixels 100A1-px and 100A2-px, an insulating alignment layer 130A is provided on the amorphous substrate 110. A semi-transmissive reflective layer 120A is provided on the insulating alignment layer 130A. A first semiconductor layer 140 is provided on the semi-transmissive reflective layer 120A. That is, the first semiconductor layer 140 is not provided in contact with the insulating alignment layer 130A. However, the thickness of the semi-transmissive reflective layer 120A is small enough to allow light to pass through, and the insulating alignment layer 130A can control the crystallinity of the first semiconductor layer 140 via the semi-transmissive reflective layer 120A. Therefore, the first semiconductor layer 140 provided on the semi-transmissive reflective layer 120A has a highly crystalline c-axis orientation.

[0050] Furthermore, in the pixel 100A2-px, the semi-transmissive reflective layer 120A can be used as an electrode for the LED. If the semi-transmissive reflective layer 120A has a high resistance, the semi-transmissive reflective layer 120A may contain a transparent conductive oxide such as indium tin oxide (ITO) or indium zinc oxide (IZO). That is, at least a portion of the semi-transmissive reflective layer 120A may be provided with a laminated film of a metal or alloy and a transparent conductive oxide. This can reduce the resistance of the semi-transmissive reflective layer 120A.

[0051] As described above, the light emitting device 100 according to this embodiment includes the region 300A having a microcavity structure. Therefore, the light emitting device 100 has improved light extraction efficiency and little change in light extraction efficiency due to chromaticity change. Furthermore, in the light emitting device 100, the LED is formed using the amorphous substrate 110, which reduces the manufacturing cost of the light emitting device 100.

[0052] <Third embodiment> Another configuration of the light emitting device 100 according to one embodiment of the present invention will be described with reference to Figures 6 and 7. Note that, in the following, description of the same configuration as that described above may be omitted.

[0053] FIG. 6 is a schematic cross-sectional view showing the configuration of a pixel 100B-px of a light-emitting device 100 according to one embodiment of the present invention. As shown in FIG. 6, the pixel 100B-px includes an amorphous substrate 110, a first insulating alignment layer 130B-1, a semi-transmissive reflective layer 120B, a second insulating alignment layer 130B-2, a first semiconductor layer 140, a light-emitting layer 150, a second semiconductor layer 160, a first electrode layer 170, and a second electrode layer 180. That is, the pixel 100B-px includes an LED including the first semiconductor layer 140, the light-emitting layer 150, the second semiconductor layer 160, the first electrode layer 170, and the second electrode layer 180. The LED included in the pixel 100B-px has a so-called horizontal electrode structure in which the first electrode layer 170 and the second electrode layer 180 are provided on one side of the light-emitting layer 150. In the pixel 100B-px, light emitted from the light-emitting layer 150 passes through the amorphous substrate 110 and is extracted.

[0054] The pixel 100B-px includes a region 300B having a microcavity structure that repeatedly reflects light between the semi-transmissive reflective layer 120B and the second electrode layer 180.

[0055] In the pixel 100B-px, a first insulating orientation layer 130B-1 is provided on the amorphous substrate 110. A semi-transmissive reflective layer 120B is provided on the first insulating orientation layer 130B-1. A second insulating orientation layer 130B-2 is provided on the semi-transmissive reflective layer 120B. A first semiconductor layer 140 is provided on the second insulating orientation layer 130B-2. When the first semiconductor layer 140 is provided on the semi-transmissive reflective layer 120B, the c-axis orientation of the first semiconductor layer 140 may be insufficient. In this case, a second insulating orientation layer 130B-2 is provided on the first semiconductor layer 140. This allows the second insulating orientation layer 130B-2 to control the crystallinity of the first semiconductor layer 140, so that the first semiconductor layer 140 has a highly crystalline c-axis orientation. Furthermore, since the second insulating alignment layer 130B-2 is located between the semi-transmissive reflective layer 120B and the second electrode layer 180, the optical path length of the microcavity structure can be adjusted by adjusting the thickness of the second insulating alignment layer 130B-2. For example, the thickness of the second insulating alignment layer 130B-2 can be made larger than the thickness of the first insulating alignment layer 130B-1.

[0056] As described above, the light emitting device 100 according to this embodiment includes the region 300B having a microcavity structure. Therefore, the light emitting device 100 has improved light extraction efficiency and little change in light extraction efficiency due to chromaticity change. Furthermore, in the light emitting device 100, the LEDs are formed using the amorphous substrate 110, which reduces the manufacturing cost of the light emitting device 100. <Fourth embodiment> Another configuration of the light emitting device 100 according to one embodiment of the present invention will be described with reference to Figures 8 and 9. Note that, in the following, description of the same configuration as that described above may be omitted.

[0057] FIG. 8 is a schematic cross-sectional view illustrating the configuration of a pixel 100C-px of a light-emitting device 100 according to one embodiment of the present invention. As shown in FIG. 8, the pixel 100C-px includes an amorphous substrate 110, an insulating alignment layer 130C, a conductive alignment layer 170C, a first semiconductor layer 140, an optical distance adjustment layer 190C, a light-emitting layer 150, a second semiconductor layer 160, a semi-transmissive reflective layer 120C, and an insulating layer 200C. The conductive alignment layer 170C and the semi-transmissive reflective layer 120C can function as the first and second electrodes of the LED, respectively. Therefore, the pixel 100C-px includes an LED including the conductive alignment layer 170C as a first electrode layer, the first semiconductor layer 140, the light-emitting layer 150, the second semiconductor layer 160, and the semi-transmissive reflective layer 120C as a second electrode layer. The LED included in pixel 100C-px has a so-called vertical electrode structure in which a conductive alignment layer 170C functioning as a first electrode layer is provided on one surface of light-emitting layer 150, and a semi-transmissive reflective layer 120C functioning as a second electrode layer is provided on the other surface of light-emitting layer 150. In pixel 100C-px, light emitted from light-emitting layer 150 passes through insulating layer 200C and is extracted.

[0058] The conductive orientation layer 170C can improve the crystallinity of the first semiconductor layer 140 formed on the conductive orientation layer 170C. Examples of the conductive orientation layer 170C include titanium (Ti), titanium nitride (TiN), and the like. x ), titanium oxide (TiO x ), graphene, zinc oxide (ZnO), magnesium diboride (MgB2), aluminum (Al), silver (Ag), calcium (Ca), nickel (Ni), copper (Cu), strontium (Sr), rhodium (Rh), palladium (Pd), cerium (Ce), ytterbium (Yb), iridium (Ir), platinum (Pt), gold (Au), lead (Pb), actinium (Ac), thorium (Th), BiLaTiO, SrFeO, BiFeO, BaFeO, ZnFeO, or PMnN-PZT can be used. The conductive alignment layer 170C can be formed using any method (apparatus) such as sputtering or CVD.

[0059] The insulating alignment layer 130C is provided on the amorphous substrate 110. The conductive alignment layer 170C is provided on the insulating alignment layer 130C. The first semiconductor layer 140 is provided on the conductive alignment layer 170C. The optical distance adjustment layer 190C is provided on the first semiconductor layer 140. The light emitting layer 150 is provided on the optical distance adjustment layer 190C. The second semiconductor layer 160 is provided on the light emitting layer 150. The semi-transmissive reflective layer 120C is provided on the second semiconductor layer 160. The insulating layer 200C is provided on the semi-transmissive reflective layer 120C.

[0060] Each of the insulating alignment layer 130C, the conductive alignment layer 170C, the first semiconductor layer 140, the optical distance adjustment layer 190C, the light-emitting layer 150, the second semiconductor layer 160, the semi-transmissive reflective layer 120C, and the insulating layer 200C may be provided in common to multiple pixels 100C-px. Alternatively, although not shown, the conductive alignment layer 170C may be provided in an island shape within the pixel 100C-px, and the semi-transmissive reflective layer 120C may be provided in common to multiple pixels 100C-px. Alternatively, although not shown, the conductive alignment layer 170C may extend in a first direction and be provided in common to multiple pixels 100C-px arranged in the first direction, and the semi-transmissive reflective layer 120C may extend in a second direction and be provided in common to multiple pixels 100C-px arranged in the second direction.

[0061] The optical distance adjustment layer 190C can adjust the optical distance of the microcavity structure. Specifically, the film thickness of the optical distance adjustment layer 190C is increased as the wavelength of the extracted light becomes longer. For example, gallium nitride can be used as the optical distance adjustment layer 190C, and it is preferably the same material as the first semiconductor layer 140. In that case, the optical distance adjustment layer 190C can be said to be part of the first semiconductor layer 140. Therefore, the optical distance of the microcavity structure can be adjusted by changing the film thickness of the first semiconductor layer 140.

[0062] Although not shown, the optical distance adjustment layer 190C may be provided between the conductive alignment layer 170C and the first semiconductor layer 140.

[0063] The insulating layer 200C can emit light incident on the insulating layer 200C from the semi-transmissive reflective layer 120C to the outside. To improve the light extraction efficiency of the light emitting device 100, the insulating layer 200C preferably has a high refractive index. For example, aluminum nitride (AlN) can be used as the insulating layer 200C. The insulating layer 200C can be formed using any method (apparatus) such as sputtering or CVD.

[0064] Although not shown, the surface of the insulating layer 200C may be provided with irregularities, which can further improve the light extraction efficiency of the light emitting device 100.

[0065] In pixel 100C-px, the first semiconductor layer 140 is not provided in contact with the insulating orientation layer 130C, but is provided in contact with the conductive orientation layer 170C. Therefore, the first semiconductor layer 140 has a highly crystalline c-axis orientation. Furthermore, the conductive orientation layer 170C provided on the insulating orientation layer 130C has a crystallinity that reflects the influence of the insulating orientation layer 130C, and the first semiconductor layer 140 provided on such a conductive orientation layer 170C is influenced by the insulating orientation layer 130C. Therefore, the first semiconductor layer 140 formed on the insulating orientation layer 130C and the conductive orientation layer 170C has an even more crystalline c-axis orientation.

[0066] As described above, the light emitting device 100 according to this embodiment includes the region 300C having a microcavity structure. Therefore, the light emitting device 100 has improved light extraction efficiency and little change in light extraction efficiency due to chromaticity change. Furthermore, in the light emitting device 100, the LEDs are formed using the amorphous substrate 110, which reduces the manufacturing cost of the light emitting device 100.

[0067] <Example> Simulations were performed on the current efficiency and the change in chromaticity with the current efficiency for the microcavity structures of the regions 300 to 300B of the light-emitting device 100 according to the first to third embodiments. The simulations were performed using Setfos (manufactured by Fluxim). In the simulations, the thickness of the insulating alignment layer was varied, while the other thicknesses were fixed.

[0068] 1. Example 1 FIG. 10 is a graph showing the current efficiency versus change in chromaticity (y-coordinate of the chromaticity coordinate system) in the microcavity structure of the region 300 shown in FIG. 3. In the simulation of the region 300 shown in FIG. 3, the amorphous substrate 110, the semi-transmissive reflective layer 120, the insulating alignment layer 130, and the second electrode layer 180 were made using parameters for glass, magnesium silver (MgAg), aluminum nitride (AlN), and silver (Ag), respectively. The first semiconductor layer 140, the light-emitting layer 150, and the second semiconductor layer 160 were made using parameters for gallium nitride (GaN). The film thicknesses of the amorphous substrate 110, the semi-transmissive reflective layer 120, the first semiconductor layer 140, the light-emitting layer 150, the second semiconductor layer 160, and the second electrode layer 180 were set to 0.5 mm, 15 nm, 10 nm, 20 nm, 20 nm, and 100 nm, respectively. The emission spectrum of the light-emitting layer 150 had a normal distribution with a peak at a wavelength of 460 nm.

[0069] 2. Example 2 FIG. 11 is a graph showing the current efficiency versus chromaticity (y-coordinate of the chromaticity coordinate system) in the microcavity structure of the region 300A shown in FIG. 5. In the simulation of the region 300A shown in FIG. 5, the amorphous substrate 110, the insulating orientation layer 130A, the semi-transmissive reflective layer 120A, and the second electrode layer 180 were made using parameters for glass, aluminum nitride (AlN), magnesium silver (MgAg), and silver (Ag), respectively. The first semiconductor layer 140, the light-emitting layer 150, and the second semiconductor layer 160 were made using parameters for gallium nitride (GaN). The film thicknesses of the amorphous substrate 110, the semi-transmissive reflective layer 120A, the first semiconductor layer 140, the light-emitting layer 150, the second semiconductor layer 160, and the second electrode layer 180 were set to 0.5 mm, 15 nm, 10 nm, 20 nm, 20 nm, and 100 nm, respectively. The emission spectrum of the light-emitting layer 150 had a normal distribution with a peak at a wavelength of 460 nm.

[0070] 3. Example 3 12 is a graph showing the current efficiency versus chromaticity (y-coordinate of the chromaticity coordinate system) in the microcavity structure of region 300B shown in FIG. 7. In the simulation of region 300B shown in FIG. 7, the amorphous substrate 110, the first insulating orientation layer 130B-1, the semi-transmissive reflective layer 120B, the second insulating orientation layer 130B-2, and the second electrode layer 180 used parameters of glass, aluminum nitride (AlN), magnesium silver (MgAg), aluminum nitride (AlN), and silver (Ag), respectively. The first semiconductor layer 140, the light-emitting layer 150, and the second semiconductor layer 160 all used parameters of gallium nitride (GaN). The amorphous substrate 110, the first insulating orientation layer 130B-1, the semi-transmissive reflective layer 120A, the first semiconductor layer 140, the light-emitting layer 150, the second semiconductor layer 160, and the second electrode layer 180 had thicknesses of 0.5 mm, 60 nm, 15 nm, 10 nm, 20 nm, 20 nm, and 100 nm, respectively. The emission spectrum of the light-emitting layer 150 had a normal distribution with a peak at a wavelength of 460 nm.

[0071] [4. Comparative Example] 13 is a schematic cross-sectional view showing a comparative example region 500 having no microcavity structure. In the region 500, an insulating orientation layer 130, a first semiconductor layer 140, a light-emitting layer 150, a second semiconductor layer 160, and a second electrode layer 180 are provided in this order on an amorphous substrate 110. In the comparative example region 500, light emitted from the light-emitting layer 150 passes through the amorphous substrate 110 and is extracted.

[0072] FIG. 14 is a graph showing the current efficiency versus change in chromaticity (y-coordinate of the chromaticity coordinate system) in the structure of the comparative example region 500 shown in FIG. 13. In the simulation of the region 500 shown in FIG. 13, the amorphous substrate 110, the insulating orientation layer 130, and the second electrode layer 180 used parameters for glass, aluminum nitride (AlN), and silver (Ag), respectively. The first semiconductor layer 140, the light-emitting layer 150, and the second semiconductor layer 160 all used parameters for gallium nitride (GaN). The film thicknesses of the amorphous substrate 110, the first semiconductor layer 140, the light-emitting layer 150, the second semiconductor layer 160, and the second electrode layer 180 were 0.5 mm, 10 nm, 20 nm, 20 nm, and 100 nm, respectively. The emission spectrum of the light-emitting layer 150 was a normal distribution with a peak at a wavelength of 460 nm.

[0073] [5. Results] The simulation results were compared between Examples 1 to 3 and the Comparative Example. The simulation results are shown in Tables 1 and 2. Specifically, Table 1 shows the current efficiency (η 0.04 ) and CIE-y=0.05 current efficiency (η 0.05 ) from the current efficiency change rate of CIE-y=0.05 relative to CIE-y=0.04 ((η 0.05 -η 0.04 ) / η 0.04×100). Table 2 shows the ratio of difference between the Examples normalized by the current efficiency of the Comparative Example ((η(Example)-η(Comparative Example)) / η(Comparative Example)×100). Table 1 shows that Examples 1 to 3 have a smaller change in current efficiency with chromaticity change than the Comparative Example. Table 2 shows that Examples 1 to 3 have improved current efficiency compared to the Comparative Example. Therefore, Examples 1 to 3, which have a microcavity structure, have improved light extraction efficiency and a smaller change in light extraction efficiency with chromaticity change.

[0074] [Table 1]

[0075] [Table 2]

[0076] Fifth Embodiment A light emitting device forming substrate 10 according to one embodiment of the present invention will be described with reference to FIG.

[0077] 15 is a schematic diagram showing the configuration of a light emitting device forming substrate 10 according to one embodiment of the present invention. The light emitting device forming substrate 10 includes a plurality of light emitting devices 100. That is, in the light emitting device forming substrate 10, a plurality of light emitting devices 100 are manufactured using a single amorphous substrate 110. The amorphous substrate 110 is a so-called large-area substrate. In the light emitting device forming substrate 10, a plurality of light emitting devices 100 can be manufactured at once using a large-area substrate, thereby reducing the manufacturing cost of the light emitting devices 100.

[0078] The above-described embodiments of the present invention may be combined as appropriate as long as they are not mutually inconsistent. Furthermore, even if a person skilled in the art appropriately adds or deletes components or modifies the design based on each embodiment, or adds or omits steps or modifies conditions, such combinations are included within the scope of the present invention as long as they include the gist of the present invention.

[0079] Even if there are other effects and advantages different from those brought about by the above-mentioned embodiments, if they are clear from the description in this specification or can be easily predicted by a person skilled in the art, they are naturally understood to be brought about by the present invention. [Explanation of symbols]

[0080] 10: Light emitting device forming substrate, 100: light-emitting device, 100P: pixel portion, 100-px, 100A1-px, 100A2-px, 100B-px, 100C-px: pixel, 100T: terminal portion, 100-t: terminal, 110: amorphous substrate, 120, 120A, 120B, 120C: semi-transmissive reflective layer, 130, 130A, 130B-1, 130B-2, 130C: insulating alignment layer, 140: first semiconductor layer, 150: light-emitting layer, 160: second semiconductor layer, 170: first electrode layer, 170C: conductive alignment layer, 180: second electrode layer, 190C: optical distance adjustment layer, 200C: insulating layer, 300, 300A, 300B, 300C: area, 500: area

Claims

1. a plurality of pixels arranged in a matrix on an amorphous substrate in a first direction and a second direction intersecting the first direction; Each of the plurality of pixels is a semi-transmissive reflective layer on the amorphous substrate; a first insulating alignment layer on the semi-transmissive reflective layer; a first semiconductor layer on the first insulating orientation layer; a light emitting layer on the first semiconductor layer; a second semiconductor layer over the light emitting layer; and an electrode layer on the second semiconductor layer; the first insulating orientation layer is a layer that controls crystallinity so that the first semiconductor layer has a c-axis orientation when the first semiconductor layer is formed in contact with the first insulating orientation layer; the semi-transmissive reflective layer, the first insulating alignment layer, and the first semiconductor layer are provided in common to the plurality of pixels; the light emitting layer, the second semiconductor layer, and the electrode layer are provided in an island shape in each of a plurality of pixels; The first semiconductor layer, the light emitting layer, and the second semiconductor layer each comprise gallium nitride.

2. a plurality of pixels arranged in a matrix on an amorphous substrate in a first direction and a second direction intersecting the first direction; Each of the plurality of pixels is a first insulating alignment layer on said amorphous substrate; a semi-transmissive reflective layer on the first insulating alignment layer; a first semiconductor layer on the semi-transmissive reflective layer; a light emitting layer on the first semiconductor layer; a second semiconductor layer over the light emitting layer; and an electrode layer on the second semiconductor layer; the first insulating orientation layer is a layer that controls crystallinity so that the first semiconductor layer has a c-axis orientation when the first semiconductor layer is formed in contact with the first insulating orientation layer; the first insulating alignment layer, the semi-transmissive reflective layer, and the first semiconductor layer are provided in common to the plurality of pixels; the light emitting layer, the second semiconductor layer, and the electrode layer are provided in an island shape in each of a plurality of pixels; The first semiconductor layer, the light emitting layer, and the second semiconductor layer each comprise gallium nitride.

3. Each of the plurality of pixels further includes a second insulating alignment layer between the semi-transmissive reflective layer and the first semiconductor layer; The light-emitting device of claim 2, wherein the second insulating orientation layer is a layer that controls crystallinity so that the first semiconductor layer has a c-axis orientation when the first semiconductor layer is formed in contact with the second insulating orientation layer.

4. The light emitting device of claim 3 , wherein the second insulating alignment layer has a thickness greater than a thickness of the first insulating alignment layer.

5. a plurality of pixels arranged in a matrix on an amorphous substrate in a first direction and a second direction intersecting the first direction; Each of the plurality of pixels is a first insulating alignment layer on said amorphous substrate; an electrode layer on the first insulating alignment layer; a first semiconductor layer on the electrode layer; a light emitting layer on the first semiconductor layer; a second semiconductor layer over the light emitting layer; and a semi-transmissive reflective layer on the second semiconductor layer; the first insulating orientation layer is a layer that controls crystallinity so that the first semiconductor layer has a c-axis orientation when the first semiconductor layer is formed in contact with the first insulating orientation layer; the first insulating alignment layer, the first semiconductor layer, the light emitting layer, the second semiconductor layer, and the semi-transmissive reflective layer are provided in common to the plurality of pixels; the electrode layer is provided in an island shape for each of a plurality of pixels, The first semiconductor layer, the light emitting layer, and the second semiconductor layer each comprise gallium nitride.

6. The light emitting device according to claim 5 , wherein each of the plurality of pixels further comprises an insulating layer on the semi-transmissive reflective layer.

7. Each of the plurality of pixels further includes an optical distance adjustment layer between the first semiconductor layer and the light emitting layer, The light emitting device according to claim 1 , wherein the optical distance adjustment layer contains gallium nitride.

8. 7. The light emitting device according to claim 1, wherein the first insulating alignment layer comprises at least one selected from aluminum nitride and aluminum oxide.

9. The light emitting device according to claim 1 , wherein the semi-transmissive reflective layer contains at least one selected from the group consisting of silver and magnesium.

10. The light emitting device according to claim 1 , wherein the amorphous substrate is an amorphous glass substrate.

11. A light emitting device according to any one of claims 1 to 6, The amorphous substrate is a substrate common to the plurality of light emitting devices.

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