Light-emitting device and light-emitting device formation substrate

Abstract

To provide a light-emitting device including a gallium nitride film formed on a large substrate such as an amorphous glass substrate, in which the light extraction efficiency is improved.SOLUTION: A light-emitting device includes a plurality of pixels arranged in matrix in a first direction and a second direction intersecting with the first direction. Each of the pixels includes an amorphous substrate and a transflective layer on the amorphous substrate, a first insulating alignment layer on the transflective 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 of the first semiconductor layer, the light-emitting layer, and the second semiconductor layer contains gallium nitride.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] One embodiment of the present invention relates to a light-emitting device including gallium nitride. Another embodiment of the present invention relates to a light-emitting device forming substrate on which a plurality of light-emitting devices including gallium nitride are formed.

Background Art

[0002] Gallium nitride (GaN) has the characteristic of a direct-transition semiconductor with a large bandgap. Utilizing the characteristics of gallium nitride, light-emitting diodes (LEDs) using gallium nitride films have already been put into practical use. The gallium nitride film of the LED is generally formed on a sapphire substrate at a high temperature of 800°C to 1000°C using MOCVD (Metal Organic Chemical Vapor Deposition) or HVPE (Hydride Vapor Phase Epitaxy).

[0003] By the way, in recent years, as a next-generation display device (or next-generation light-emitting device), the development of a so-called micro-LED display device or mini-LED display device in which minute LED chips are mounted in pixels of a circuit board has been advanced. The micro-LED display device or mini-LED display device has high efficiency, high luminance, and high reliability. Such a micro-LED display device or mini-LED display device is manufactured by transferring LED chips onto a backplane on which thin-film transistors using an oxide semiconductor or low-temperature polysilicon or the like are formed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the method for manufacturing a micro-LED display device by transferring an LED chip has a high manufacturing cost and it is difficult to manufacture a micro-LED display device at a low cost. On the other hand, if LEDs can be formed on a large-area substrate such as an amorphous glass substrate, the manufacturing cost can be reduced. However, as described above, since the gallium nitride film is formed on a sapphire substrate at a high temperature, it is difficult to directly form a gallium nitride film on an amorphous glass substrate.

[0006] Also, even when a gallium nitride film is directly formed on an amorphous glass substrate, since gallium nitride is a high refractive index material, improvement in light extraction efficiency has been demanded.

[0007] One object of an embodiment of the present invention is to provide a light-emitting device including a gallium nitride film formed on a large-area substrate such as an amorphous glass substrate and having improved light extraction efficiency in view of the above problems. Another object of an embodiment of the present invention is to provide a light-emitting device forming substrate on which a plurality of light-emitting devices including a gallium nitride film and having improved light extraction efficiency are formed.

Means for Solving the Problems

[0008] A light-emitting device according to an 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 includes 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 of the first semiconductor layer, the light-emitting layer, and the second semiconductor layer contains gallium nitride.

[0009] The light-emitting device according to an 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 includes an amorphous substrate, a first insulating alignment layer on the 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 on the light-emitting layer, and an electrode layer on the second semiconductor layer. Each of the first semiconductor layer, the light-emitting layer, and the second semiconductor layer contains gallium nitride.

[0010] The light-emitting device according to an 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 includes an amorphous substrate, a first insulating alignment layer on the 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 on the light-emitting layer, and a semi-transmissive reflective layer on the second semiconductor layer. Each of the first semiconductor layer, the light-emitting layer, and the second semiconductor layer contains gallium nitride.

[0011] The light-emitting device forming substrate according to an embodiment of the present invention includes a plurality of the above-described light-emitting devices, and the amorphous substrate is a single substrate common to the plurality of light-emitting devices.

Brief Description of the Drawings

[0012]

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Embodiments for Carrying Out the Invention

[0013] Hereinafter, each embodiment according to the present invention will be described with reference to the drawings. Note that each embodiment is merely an example, and those that can be easily conceived by those skilled in the art by appropriately changing while maintaining the gist of the invention are naturally included in the scope of the present invention. In addition, for the purpose of making the description clearer, the drawings may schematically show the width, thickness, shape, etc. of each part as compared with the actual aspect. However, the illustrated shapes and the like are merely examples and do not limit the interpretation of the present invention.

[0014] In this specification, 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 the case where α includes a plurality of combinations of A to C unless otherwise specified. Furthermore, these expressions do not exclude the case where α includes other elements.

[0015] In this specification, for convenience of explanation, terms such as "upper", "above", "lower", or "below" are used. In principle, with reference to the substrate on which the structure is formed, the direction from the substrate to the structure is defined as "upper" or "above". Conversely, the direction from the structure to the substrate is defined as "lower" or "below". Therefore, in the expression of a structure on a substrate, the surface of the structure facing the substrate becomes the lower surface of the structure, and the opposite surface becomes the upper surface of the structure. Also, in the expression of a structure on a substrate, it only explains the vertical relationship between the substrate and the structure, and other members may be arranged between the substrate and the structure. Furthermore, the terms "upper", "above", "lower", or "below" mean the stacking order in a structure where a plurality of layers are stacked, and they do not have to be in an overlapping positional relationship in a plan view.

[0016] In this specification, characters such as "first", "second", or "third" appended to each component are for convenience of distinguishing each component and do not have any further meaning unless otherwise specified.

[0017] In this specification and the drawings, when collectively representing a plurality of identical or similar components, the same reference numerals are used. When distinguishing and representing each of these components, it may be represented by adding a capital letter. Also, when distinguishing and representing a certain part in one component, a hyphen and a lowercase letter may be used.

[0018] The following embodiments can be combined with each other as long as no technical contradiction occurs.

[0019] <First Embodiment> Referring to FIGS. 1 to 3, the configuration of the light-emitting device 100 according to an embodiment of the present invention will be described.

[0020] FIG. 1 is a schematic diagram showing the configuration of a light-emitting device 100 according to an embodiment of the present invention. On the amorphous substrate 110, a pixel portion 100P and a terminal portion 100T are formed. The pixel portion 100P is formed at the center of the amorphous substrate 110, and the terminal portion 100T is formed at the end of the amorphous substrate 110. The pixel portion 100P includes a plurality of pixels 100-px arranged in a first direction and a second direction (intersecting) orthogonal to the first direction. Although details will be described later, a light-emitting diode (LED) is formed on the amorphous substrate 110 for each of the plurality of pixels 100-px. The terminal portion 100T includes a plurality of terminals 100-t. A power supply line is connected to each of the plurality of terminals 100-t, and a voltage can be applied (current can 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, and the light emission of the LED can be controlled by the thin film transistor.

[0021] FIG. 2 is a schematic cross-sectional view showing the configuration of the pixel 100-px of the light-emitting device 100 according to an embodiment of the present invention. Further, FIG. 3 is a schematic cross-sectional view showing the 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, a light-emitting layer 150, a second semiconductor layer 160, a first electrode layer 170, and a second electrode layer 180. That is, an LED including 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 is provided in the pixel 100-px. 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 surface side of the light-emitting layer 150. In the pixel 100-px, the light emitted from the light-emitting layer 150 is taken out through the amorphous substrate 110.

[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 for 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 for 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 on the insulating alignment layer 130 in this order. The first semiconductor layer 140 may be provided in common for a plurality of 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 a region not covered by each of the light-emitting layer 150 and 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 each of the light-emitting layer 150 and 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. That is, the first electrode layer 170 and the second electrode layer 180 are electrically separated.

[0026] Although not shown, an insulating layer may be provided over 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 of 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 of the insulating layer where the second semiconductor layer 160 is exposed. Also, 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 also be provided in an island shape within the pixel 100-px, may extend in the first direction or the second direction, and may be provided in common to a plurality of pixels 100-px arranged in the first direction or the second direction. Also in this case, the first electrode layer 170 and the second electrode layer 180 are electrically separated from each other.

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

[0028] The amorphous substrate 110 is a base material (support substrate) of the light-emitting device 100. Although details will be described later, in the light-emitting device 100, each of the first semiconductor layer 140, the light-emitting layer 150, and the second semiconductor layer 160 is formed on the amorphous substrate 110 using sputtering film formation. Therefore, the amorphous substrate 110 may have a heat resistance of about 400°C, which is relatively low, for example. As the amorphous substrate 110, for example, an amorphous glass substrate can be used. Also, instead of the amorphous substrate 110, a resin substrate such as a polyimide substrate, an acrylic substrate, a siloxane substrate, or a fluororesin substrate can be used. Such an amorphous glass substrate or resin substrate is a substrate that can be made large in area. Also, instead of the amorphous substrate 110, a polycrystalline substrate can be used. The polycrystalline substrate can be made larger in area than a sapphire substrate generally used in the film formation of a gallium nitride film, and can be used as a base material of the light-emitting device 100 in the same manner as an amorphous glass substrate or a resin substrate. Note that a thin film transistor for controlling an LED may be provided in the amorphous substrate.

[0029] Explaining the amorphous substrate 110 in more detail, the amorphous substrate 110 preferably has a low coefficient of thermal expansion, a high strain point, and high surface flatness. For example, the amorphous substrate 110 has a coefficient of thermal expansion less than 50×10 -7 / °C and preferably has a strain point of 600°C or higher. Note that the amorphous substrate 110 only needs to have a heat resistance of about 400°C and does not require a heat resistance of 1000°C or higher like a sapphire substrate. When the amorphous substrate 110 is an amorphous glass substrate, as the amorphous substrate 110 satisfying the above-described characteristics, for example, a glass substrate formed of aluminoborosilicate glass or aluminosilicate glass can be used. Such a glass substrate is used in a liquid crystal display and an organic electroluminescence (organic EL) display, and a large-area glass substrate called mother glass is provided on the market. Further, the amorphous substrate 110 preferably has a content of an alkali metal such as sodium (Na) of 0.1% or less.

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

[0031] The semi-transmissive reflective layer 120 can transmit or reflect the light emitted from the light-emitting layer 150 or the light reflected by the second electrode layer 180. That is, the pixel 100-px includes a region 300 having a microcavity structure that repeats reflection between the semi-transmissive reflective layer 120 and the second electrode layer 180. Thereby, the light extraction efficiency of the light-emitting device 100 is improved. Also, in the light-emitting device 100, the change in light extraction efficiency due to the chromaticity change is small. As the semi-transmissive reflective layer 120, for example, a metal such as silver (Ag) or magnesium (Mg), or an alloy thereof can be used. These metals or alloys have a film thickness that can transmit the light emitted from the light-emitting layer 150 or the light reflected by the second electrode layer 180. For example, the film thickness of the semi-transmissive reflective layer 120 is 1 nm or more and 50 nm or less, preferably 5 nm or more and 30 nm or less.

[0032] The insulating alignment layer 130 can improve the crystallinity of the first semiconductor layer 140 formed on the insulating alignment layer 130. Specifically, the insulating alignment layer 130 can be controlled such that the first semiconductor layer 140 has c-axis orientation. "A layer having c-axis orientation" means that the c-axis of the crystal structure of the layer is oriented in a direction substantially perpendicular to the formation surface. As the insulating alignment layer 130, an insulating material having a hexagonal close-packed structure, a face-centered cubic structure, or a structure similar thereto can be used. Here, a structure similar to the hexagonal close-packed structure or the face-centered cubic structure includes a crystal structure in which the c-axis is not 90° with respect to the a-axis and the b-axis. The insulating alignment layer 130 using an insulating material having a hexagonal close-packed structure or a structure similar thereto is oriented in the (0001) direction, that is, the c-axis direction, with respect to the amorphous substrate 110 (hereinafter referred to as the (0001) alignment of the hexagonal close-packed structure). Further, the insulating alignment layer 130 using a material having a face-centered cubic structure or a structure similar thereto is oriented in the (111) direction with respect to the amorphous substrate 110 (hereinafter referred to as the (111) alignment of the face-centered cubic structure). Since the insulating alignment layer 130 has the (0001) alignment of the hexagonal close-packed structure or the (111) alignment of the face-centered cubic structure, crystal growth in the c-axis direction of the film formed on the insulating alignment layer 130 is promoted, and the first semiconductor layer 140 on the insulating alignment layer 130 has c-axis orientation. As the insulating alignment layer 130, for example, aluminum nitride (AlN x ), aluminum oxide (AlO x ), lithium niobate (LiNbO), BiLaTiO, SrFeO, BiFeO, BaFeO, ZnFeO, PMnN-PZT, or bioapatite (BAp) can be used. Note that the insulating alignment layer 130 can be formed by using any method (apparatus) such as sputtering or CVD.

[0033] The crystallinity of the first semiconductor layer 140 on the insulating alignment layer 130 is affected by the surface state of the insulating alignment layer 130. Therefore, the insulating alignment layer 130 preferably has a surface with few irregularities and is smooth. For example, the arithmetic mean roughness (Ra) of the surface of the insulating alignment layer 130 is preferably less than 2.3 nm. Also, the root mean square roughness (Rq) of the surface of the insulating alignment layer 130 is preferably less than 2.9 nm. When the surface roughness of the insulating alignment layer 130 is within these conditions, the first semiconductor layer 140 has a higher crystallinity c-axis orientation. Note that the film thickness of the insulating alignment layer 130 is preferably 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. As the n-type semiconductor layer, for example, a gallium nitride film doped with silicon (Si) can be used. 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. As the p-type semiconductor layer, for example, a gallium nitride film doped with magnesium (Mg) can be used. The 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 and emits light. The light-emitting layer 150 has a multiple quantum well structure. As the light-emitting layer 150, for example, a laminated film in which indium gallium nitride (InGaN) films and gallium nitride films are alternately laminated can be used. 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 using sputtering on the insulating alignment layer 130 will be described.

[0037] In a vacuum chamber, an amorphous substrate 110 on which an insulating alignment layer 130 is formed is disposed facing a gallium nitride target. The composition ratio of gallium nitride in the gallium nitride target is preferably such that the ratio of gallium to nitrogen is 0.7 or more and 2 or less. Further, nitrogen can be supplied to the vacuum chamber separately from a sputtering gas (such as argon or krypton). In that case, the composition ratio of gallium nitride in the gallium nitride target preferably has more gallium than nitrogen. For example, nitrogen can be supplied using a nitrogen radical source. The sputtering power supply may be any of 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, it is more preferably 100°C or more and 400°C or less. At this temperature, it can be applied to the amorphous substrate 110 which has a lower film formation temperature than MOCVD or HVPE and lower heat resistance than a sapphire substrate.

[0039] After sufficiently evacuating the inside of the vacuum chamber, a sputtering gas is supplied. Further, a voltage is applied between the amorphous substrate 110 and the gallium nitride target at a predetermined pressure to generate plasma, and a gallium nitride film is formed.

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

[0041] In the light-emitting device 100, each of the first semiconductor layer 140, the light-emitting layer 150, and the second semiconductor layer 160 contains gallium nitride. The gallium nitride film of the first semiconductor layer 140 is formed directly on the insulating alignment layer 130, but the gallium nitride films of the light-emitting layer 150 and the second semiconductor layer 160 are not formed directly on the insulating alignment layer 130. However, since the first semiconductor layer 140 on the insulating alignment layer 130 has a highly crystalline c-axis orientation, the first semiconductor layer 140 has the same function as the insulating alignment layer 130. Therefore, the crystal growth in the c-axis direction of the gallium nitride film formed on the first semiconductor layer 140 is promoted, 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 polarities of the electrodes of the first electrode layer 170 and the second electrode layer 180 are determined according to the first semiconductor layer 140 and the second semiconductor layer 160. As the n-type electrode, for example, a metal such as silver (Ag) or indium (In), or an alloy thereof can be used. As the p-type electrode, for example, a metal such as palladium (Pd) or gold (Au), or an alloy thereof can be used. These metals or alloys have a film thickness that does not transmit the light emitted from the light-emitting layer 150 or the light reflected by the semi-transmissive reflective layer 120.

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

[0044] As described above, the light-emitting device 100 according to the present embodiment includes a region 300 having a microcavity structure. Therefore, in the light-emitting device 100, the light extraction efficiency is improved, and the change in the light extraction efficiency due to the chromaticity change is small. Further, in the light-emitting device 100, since the LED is formed using the amorphous substrate 110, the manufacturing cost of the light-emitting device 100 can be suppressed.

[0045] <Second Embodiment> With reference to FIGS. 4A to 5, another configuration of the light-emitting device 100 according to an embodiment of the present invention will be described. In the following, the description of the same configuration as the above-described configuration may be omitted.

[0046] FIGS. 4A and 4B are schematic cross-sectional views showing the configurations of the pixel 100A1-px and the pixel 100A2-px of the light-emitting device 100 according to an embodiment of the present invention, respectively. Further, FIG. 5 is a schematic cross-sectional view showing the region 300A of FIG. 4A or FIG. 4B. As shown in FIG. 4A, the pixel 100A1-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, a first electrode layer 170, and a second electrode layer 180. That is, the pixel 100A1-px is provided with an LED including 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. The LED included in the pixel 100A1-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 surface side of the light-emitting layer 150. In the pixel 100A1-px, the light emitted from the light-emitting layer 150 is extracted through the amorphous substrate 110.

[0047] Also, as shown in FIG. 4B, 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. Although details will be described later, the semi-transmissive reflective layer 120A can function as an electrode of the LED. Therefore, 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 is provided in the pixel 100A2-px. The LED included in the pixel 100A2-px has a so-called vertical electrode structure in which a semi-transmissive reflective layer 120A that functions as an electrode is provided on one surface side of the light-emitting layer 150, and a second electrode layer 180 is provided on the other surface side of the light-emitting layer 150. In the pixel 100A2-px, the light emitted from the light-emitting layer 150 is extracted through the amorphous substrate 110.

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

[0049] In each of the pixel 100A1-px and the pixel 100A2-px, the insulating alignment layer 130A is provided on the amorphous substrate 110. The semi-transmissive reflective layer 120A is provided on the insulating alignment layer 130A. The 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 film thickness of the semi-transmissive reflective layer 120A is small enough for light to pass through, and the insulating alignment layer 130A can control the crystallinity of the first semiconductor layer 140 through 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] In addition, in pixel 100A2-px, the semi-transmissive reflective layer 120A can be used as an electrode of the LED. When the resistance of the semi-transmissive reflective layer 120A is large, 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, a laminated film of a metal or alloy and a transparent conductive oxide may be provided on at least a part of the semi-transmissive reflective layer 120A. Thereby, the resistance of the semi-transmissive reflective layer 120A can be reduced.

[0051] As described above, the light-emitting device 100 according to the present embodiment includes a region 300A having a microcavity structure. Therefore, in the light-emitting device 100, the light extraction efficiency is improved, and the change in the light extraction efficiency due to the chromaticity change is small. Further, in the light-emitting device 100, since the LED is formed using the amorphous substrate 110, the manufacturing cost of the light-emitting device 100 can be suppressed.

[0052] <Third Embodiment> With reference to FIGS. 6 and 7, another configuration of the light-emitting device 100 according to an embodiment of the present invention will be described. In the following, the description of the configuration similar to the above-described configuration may be omitted.

[0053] FIG. 6 is a schematic cross-sectional view showing the configuration of pixel 100B-px of the light-emitting device 100 according to an embodiment of the present invention. As shown in FIG. 6, 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, in pixel 100B-px, an LED including 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 is provided. The LED included in 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 surface side of the light-emitting layer 150. In pixel 100B-px, the light emitted from the light-emitting layer 150 is extracted through the amorphous substrate 110.

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

[0055] In pixel 100B-px, the first insulating alignment layer 130B-1 is provided on the amorphous substrate 110. The semi-transmissive reflective layer 120B is provided on the first insulating alignment layer 130B-1. The second insulating alignment layer 130B-2 is provided on the semi-transmissive reflective layer 120B. The first semiconductor layer 140 is provided on the second insulating alignment 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 not be sufficient. In that case, the second insulating alignment layer 130B-2 is provided on the first semiconductor layer 140. Thereby, since the second insulating alignment layer 130B-2 can control the crystallinity of the first semiconductor layer 140, the first semiconductor layer 140 has a highly crystalline c-axis orientation. Further, 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 distance of the microcavity structure can also be adjusted by the film thickness of the second insulating alignment layer 130B-2. For example, the film thickness of the second insulating alignment layer 130B-2 can be made larger than the film thickness of the first insulating alignment layer 130B-1.

[0056] As described above, the light-emitting device 100 according to the present embodiment includes the region 300B having a microcavity structure. Therefore, in the light-emitting device 100, the light extraction efficiency is improved, and the change in the light extraction efficiency due to the chromaticity change is small. Further, in the light-emitting device 100, since the LED is formed using the amorphous substrate 110, the manufacturing cost of the light-emitting device 100 can be suppressed. <Fourth Embodiment> With reference to FIGS. 8 and 9, another configuration of the light-emitting device 100 according to an embodiment of the present invention will be described. Note that hereinafter, the description of the configuration similar to the above-described configuration may be omitted.

[0057] FIG. 8 is a schematic cross-sectional view showing the configuration of the pixel 100C-px of the light-emitting device 100 according to an 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 each function as the first electrode and the second electrode of the LED, respectively. Therefore, the pixel 100C-px is provided with an LED including a conductive alignment layer 170C as the first electrode layer, a first semiconductor layer 140, a light-emitting layer 150, a second semiconductor layer 160, and a semi-transmissive reflective layer 120C as the second electrode layer. The LED included in the pixel 100C-px has a so-called vertical electrode structure in which a conductive alignment layer 170C functioning as the first electrode layer is provided on one surface side of the light-emitting layer 150, and a semi-transmissive reflective layer 120C functioning as the second electrode layer is provided on the other surface side of the light-emitting layer 150. In the pixel 100C-px, the light emitted from the light-emitting layer 150 is taken out through the insulating layer 200C.

[0058] The conductive alignment layer 170C can improve the crystallinity of the first semiconductor layer 140 formed on the conductive alignment layer 170C. As the conductive alignment layer 170C, for example, titanium (Ti), titanium nitride (TiN 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, etc. can be used. Note that the conductive alignment layer 170C can be formed by 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 for a plurality of pixels 100C-px. Also, 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 for a plurality of pixels 100C-px. Also, although not shown, the conductive alignment layer 170C may extend in a first direction and be provided in common for a plurality of 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 for a plurality of 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, as the wavelength of the light to be extracted becomes longer, the film thickness of the optical distance adjustment layer 190C is increased. As the optical distance adjustment layer 190C, for example, gallium nitride can be used, and it is preferably the same material as the material of the first semiconductor layer 140. In that case, the optical distance adjustment layer 190C can be said to be a part of the first semiconductor layer 140. Therefore, by changing the film thickness of the first semiconductor layer 140, the optical distance of the microcavity structure can be adjusted.

[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 the light incident on the insulating layer 200C from the semi-transmissive reflective layer 120C to the outside. In order to improve the light extraction efficiency of the light-emitting device 100, the insulating layer 200C preferably has a high refractive index. As the insulating layer 200C, for example, aluminum nitride (AlN) or the like can be used. Note that the insulating layer 200C can be formed using any method (apparatus) such as sputtering or CVD.

[0064] Note that, although not shown, irregularities may be provided on the surface of the insulating layer 200C. Thereby, the light extraction efficiency of the light-emitting device 100 can be further improved.

[0065] In the pixel 100C-px, the first semiconductor layer 140 is not provided in contact with the insulating alignment layer 130C, but is provided in contact with the conductive alignment layer 170C. Therefore, the first semiconductor layer 140 has a highly crystalline c-axis orientation. Moreover, the conductive alignment layer 170C provided on the insulating alignment layer 130C has crystallinity in which the influence of the insulating alignment layer 130C is reflected, and the first semiconductor layer 140 provided on such a conductive alignment layer 170C is affected by the insulating alignment layer 130C. Therefore, the first semiconductor layer 140 formed on the insulating alignment layer 130C and the conductive alignment layer 170C has a higher crystalline c-axis orientation.

[0066] As described above, the light-emitting device 100 according to this embodiment includes a region 300C having a microcavity structure. Therefore, in the light-emitting device 100, the light extraction efficiency is improved, and the change in the light extraction efficiency due to the chromaticity change is small. In addition, in the light-emitting device 100, since the LED is formed using the amorphous substrate 110, the manufacturing cost of the light-emitting device 100 can be suppressed.

[0067] <Example> Regarding the microcavity structures of regions 300 to 300B of the light-emitting device 100 according to the first to third embodiments, simulations of current efficiency and chromaticity changes in current efficiency were performed. The simulations were carried out using Setfos (manufactured by Fluxim). Also, in the simulations, the film thickness of the insulating alignment layer was changed, and the other film thicknesses were set as fixed values.

[0068] [1. Example 1] FIG. 10 is a graph showing current efficiency with respect to changes in chromaticity (y-coordinate of chromaticity coordinates) in the microcavity structure of region 300 shown in FIG. 3. In the simulation of region 300 shown in FIG. 3, for the amorphous substrate 110, semi-transmissive reflective layer 120, insulating alignment layer 130, and second electrode layer 180, the parameters of glass, magnesium silver (MgAg), aluminum nitride (AlN), and silver (Ag) were used respectively. For the first semiconductor layer 140, light-emitting layer 150, and second semiconductor layer 160, the parameters of gallium nitride (GaN) were used in all cases. Also, the film thicknesses of the amorphous substrate 110, semi-transmissive reflective layer 120, first semiconductor layer 140, light-emitting layer 150, second semiconductor layer 160, and second electrode layer 180 were set to 0.5 mm, 15 nm, 10 nm, 20 nm, 20 nm, and 100 nm respectively. Also, the emission spectrum of the light-emitting layer 150 was set as 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 with respect to the change in chromaticity (y-coordinate of the chromaticity coordinates) in the microcavity structure of the region 300A shown in FIG. 5. In the simulation of the region 300A shown in FIG. 5, for the amorphous substrate 110, the insulating alignment layer 130A, the semi-transmissive reflective layer 120A, and the second electrode layer 180, the parameters of glass, aluminum nitride (AlN), magnesium silver (MgAg), and silver (Ag) were used, respectively. For the first semiconductor layer 140, the light-emitting layer 150, and the second semiconductor layer 160, the parameters of gallium nitride (GaN) were used. Also, 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 0.5 mm, 15 nm, 10 nm, 20 nm, 20 nm, and 100 nm, respectively. Also, the emission spectrum of the light-emitting layer 150 was a normal distribution with a peak at a wavelength of 460 nm.

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

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

[0072] Further, FIG. 14 is a graph showing the current efficiency with respect to the change in chromaticity (y coordinate of the chromaticity coordinates) in the structure of the region 500 of the comparative example shown in FIG. 13. In the simulation of the region 500 shown in FIG. 13, the amorphous substrate 110, the insulating alignment layer 130, and the second electrode layer 180 used the parameters of 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 the parameters of gallium nitride (GaN). Also, 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. Further, the emission spectrum of the light-emitting layer 150 was a normal distribution with a peak wavelength of 460 nm.

[0073] [5. Results] The results of the simulation were compared between Examples 1 to 3 and the comparative example. The results of the simulation are shown in Tables 1 and 2. Specifically, Table 1 shows the current efficiency (η 0.04 ) at CIE-y (y coordinate of the chromaticity coordinates) = 0.04 and the current efficiency (η 0.05 ) at CIE-y = 0.05, and the change rate of the current efficiency of CIE-y = 0.05 with respect to CIE-y = 0.04 ((η 0.05 -η 0.04 ) / η 0.04(×100). Table 2 shows the ratio of the difference in the examples normalized by the current efficiency of the comparative examples ((η (example) - η (comparative example)) / η (comparative example) × 100). From Table 1, it was found that in Examples 1 to 3 compared with the comparative examples, the change in current efficiency in the chromaticity change was small. Also, from Table 2, it was found that in Examples 1 to 3 compared with the comparative examples, the current efficiency was improved. Therefore, in Examples 1 to 3 having the microcavity structure, the light extraction efficiency is improved, and the change in light extraction efficiency due to the chromaticity change becomes small.

[0074]

Table 1

[0075]

Table 2

[0076] <Fifth Embodiment> Referring to FIG. 15, the light-emitting device forming substrate 10 according to an embodiment of the present invention will be described.

[0077] FIG. 15 is a schematic diagram showing the configuration of the light-emitting device forming substrate 10 according to an 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 one amorphous substrate 110. The amorphous substrate 110 is a so-called large-area substrate. In the light-emitting device forming substrate 10, since a plurality of light-emitting devices 100 can be manufactured at once using a large-area substrate, the manufacturing cost of the light-emitting device 100 can be suppressed.

[0078] Each of the embodiments described above as embodiments of the present invention can be implemented in appropriate combination as long as they do not contradict each other. Also, based on each embodiment, those in which those skilled in the art have appropriately added, deleted, or changed the design of components, or added, omitted, or changed the conditions of the process, are also included in the scope of the present invention as long as they have the gist of the present invention.

[0079] Even if there are other operational effects different from those brought about by the above-described embodiments, those that are apparent from the description in this specification or can be easily predicted by those skilled in the art are naturally construed as being brought about by the present invention.

Description of Reference Numerals

[0080] 10: Light-emitting device formation substrate, 100: Light-emitting device, 100P: Pixel portion, 100-px, 100A1-px, 100A2-px, 100B-px, 100C-px: Pixels, 100T: Terminal portion, 100-t: Terminals, 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: Regions, 500: Region

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 has a hexagonal close-packed structure, a face-centered cubic structure, or a structure similar to a hexagonal close-packed structure or a face-centered cubic structure; 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 has a hexagonal close-packed structure, a face-centered cubic structure, or a structure similar to a hexagonal close-packed structure or a face-centered cubic structure; 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; 3. The light emitting device of claim 2, wherein the second insulating oriented layer has a hexagonal close-packed structure, a face-centered cubic structure, or a structure quasi-hexagonal close-packed or face-centered cubic structure.

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 has a hexagonal close-packed structure, a face-centered cubic structure, or a structure similar to a hexagonal close-packed structure or a face-centered cubic structure; 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. 7. 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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