Light-emitting device, projector, and method for manufacturing light-emitting device

Abstract

The present invention provides a light-emitting device, a projector, and a method for manufacturing a light-emitting device, which suppress leakage current and have high luminous efficiency. The light-emitting device of the present invention includes: a substrate; a columnar part group provided on the substrate and composed of a plurality of columnar parts having a stacked structure including a first semiconductor layer, a light-emitting layer, and a second semiconductor layer; and an electrode provided on the plurality of columnar parts for injecting current into the plurality of columnar parts. The plurality of columnar parts include a plurality of first columnar parts and a plurality of second columnar parts arranged around the plurality of first columnar parts. The second columnar parts have a shape in which a part of the shape of the first columnar parts is missing, and the height of the second columnar parts is lower than the height of the first columnar parts. The electrode is electrically insulated from the plurality of second columnar parts.

Description

Technical Field

[0001] The present invention relates to a light-emitting device, a projector, and a method for manufacturing a light-emitting device. Background Art

[0002] Heretofore, a light-emitting device having a plurality of nanostructures with a periodic structure has been known. In Patent Document 1 below, a semiconductor optical element array is disclosed, which includes a semiconductor substrate, a plurality of nano-columnar crystals provided on the semiconductor substrate, and active layers provided on the plurality of nano-columnar crystals, respectively. Such a nanostructure has a columnar shape and is also referred to as a nanocolumn, a nanowire, a nanorod, a nanocolumn, etc., for example.

[0003] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013-239718

[0004] However, in a conventional light-emitting device having a nanostructure, due to the influence of leakage current, it is difficult for a predetermined amount of current to flow in the original light-emitting region, and thus there may occur problems such as failure to obtain a predetermined light-emitting amount and undesired light emission in a region other than the original light-emitting region. Summary of the Invention

[0005] In order to solve the above problems, a light-emitting device according to one aspect of the present invention includes: a substrate; a columnar portion group provided on the substrate and composed of a plurality of columnar portions having a stacked structure including a first semiconductor layer, a light-emitting layer, and a second semiconductor layer; and an electrode provided on the plurality of columnar portions for injecting current into the plurality of columnar portions. The plurality of columnar portions include a plurality of first columnar portions and a plurality of second columnar portions disposed around the plurality of first columnar portions. The second columnar portions have a shape in which a part of the shape of the first columnar portions is missing, and the height of the second columnar portions is lower than the height of the first columnar portions. The electrode is electrically insulated from the plurality of second columnar portions.

[0006] A projector according to one aspect of the present invention includes the light-emitting device according to one aspect of the present invention.

[0007] A method for manufacturing a light-emitting device according to an aspect of the present invention includes the following steps: forming a plurality of columnar portions having a stacked structure including a first semiconductor layer, a light-emitting layer, and a second semiconductor layer on a substrate; forming a group of columnar portions by etching the plurality of columnar portions; etching the group of columnar portions; and forming an electrode electrically connected to the group of columnar portions. In the step of forming the plurality of columnar portions, the plurality of columnar portions include a plurality of first columnar portions and a plurality of second columnar portions disposed around the plurality of first columnar portions, and the second columnar portions have a shape in which a part of the shape of the first columnar portions is missing. In the step of etching the group of columnar portions, the second columnar portions are etched so that the height of the second columnar portions is lower than the height of the first columnar portions. In the step of forming the electrode, the electrode is formed so that the second columnar portions are electrically insulated from the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic structural diagram of a projector according to an embodiment.

[0009] Figure 2 is a top view schematically showing a light-emitting device according to an embodiment.

[0010] Figure 3 is along Figure 2 a cross-sectional view of the light-emitting device taken along line II-II.

[0011] Figure 4A is a cross-sectional view showing one step in the manufacturing process of the light-emitting device.

[0012] Figure 4B is showing Figure 4A a cross-sectional view of the subsequent step.

[0013] Figure 4C is showing Figure 4B a cross-sectional view of the subsequent step.

[0014] Figure 4D is showing Figure 4C a cross-sectional view of the subsequent step.

[0015] Figure 4E is showing Figure 4D a cross-sectional view of the subsequent step.

[0016] Figure 4F is showing Figure 4E a cross-sectional view of the subsequent step.

[0017] Figure 5 is a top view of the light-emitting portion.

[0018] Figure 6 is a diagram for explaining problems of a conventional light-emitting device.

[0019] Description of Reference Numerals

[0020] 1R, 1G, 1B: Light-emitting devices; 10: Substrate; 31, 31c, 31d: Nanopillars (columnar portions); 31A: Nanopillar group (columnar portion group); 33: First semiconductor layer; 34: Light-emitting layer; 35: Second semiconductor layer; 60: Second electrode (electrode); 100: Projector; 311: First nanopillar (first columnar portion); 312: Second nanopillar (second columnar portion). Detailed Embodiment

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0022] Figure 1 It is a schematic structural diagram of the projector of this embodiment.

[0023] In the following respective drawings, in order to easily observe each component, the scale of the dimensions may be represented differently according to the components.

[0024] As Figure 1 shown, the projector 100 of this embodiment is a projection type image display device that projects an image onto the screen SCR. The projector 100 includes light-emitting devices 1R, 1G, 1B, a cross dichroic prism 3, and a projection optical device 4. The structures of the light-emitting devices 1R, 1G, 1B will be described later.

[0025] The light-emitting device 1R emits red light. The light-emitting device 1G emits green light. The light-emitting device 1B emits blue light. The light-emitting devices 1R, 1G, 1B can directly form an image without using a light modulation device such as a liquid crystal light valve by modulating each light-emitting portion as a pixel of the image according to the image information.

[0026] The color lights respectively emitted from the light-emitting devices 1R, 1G, 1B are incident on the cross dichroic prism 3. The cross dichroic prism 3 synthesizes the color lights respectively emitted from the light-emitting devices 1R, 1G, 1B and guides them to the projection optical device 4. The projection optical device 4 magnifies and projects the image formed by the light-emitting devices 1R, 1G, 1B onto the screen SCR. The projection optical device 4 is composed of one or more projection lenses.

[0027] Specifically, the cross dichroic prism 3 is formed by bonding four right-angled prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are arranged in a cross shape on its inner surface. The three color lights are synthesized by these dielectric multilayer films to form light showing a color image. The synthesized light is projected onto the screen SCR through the projection optical device 4, and an enlarged image is displayed.

[0028] The light-emitting devices 1R, 1G, and 1B have the same basic structure except for the different wavelength bands of the emitted light. Therefore, hereinafter, the structure of the light-emitting device 1B will be described in detail as an example.

[0029] Figure 2 It is a top view schematically showing the structure of the light-emitting device 1B.

[0030] Hereinafter, the structure of each part will be described using the XYZ orthogonal coordinate system. Let the axis parallel to one side of the light-emitting region whose top view shape is rectangular when observing the light-emitting device 1B from the light-emitting direction be the X axis, the axis parallel to the other side of the light-emitting region be the Y axis, and the axis perpendicular to the X axis and the Y axis be the Z axis. If the axis parallel to the light-emitting direction is defined as the optical axis of the light-emitting device 1B, then the Z axis is parallel to the optical axis of the light-emitting device 1B.

[0031] As Figure 2 shown, the light-emitting device 1B has a plurality of light-emitting parts 30 arranged in an array. In the present embodiment, the plurality of light-emitting parts 30 are arranged in a matrix along the X axis and the Y axis. Thus, in the light-emitting device 1B, a self-luminous imager that forms an image with each light-emitting part 30 as a pixel can be constituted.

[0032] Figure 3 It is a cross-sectional view showing the main part structure of the light-emitting device 1B. In addition, Figure 3 is a view showing the cross-section along the Figure 2 II-II line, showing the cross-section of the light-emitting device 1B.

[0033] As Figure 3 shown, the light-emitting device 1B includes a substrate 10, a reflective layer 11, a semiconductor layer 12, a light-emitting part 30, an insulating layer 40, a first electrode 50, a second electrode 60, and a wiring 70.

[0034] The second electrode 60 of the present embodiment corresponds to the electrode of the technical solution.

[0035] In the present embodiment, in the Z-axis direction, it is assumed that the direction from the substrate 10 to the stacking structure constituting the light-emitting part 30 is upward, and the direction toward the opposite side of the stacking direction of the stacking structure is downward for description. However, the installation direction when using the light-emitting device 1B is not limited thereby. In addition, the case of observing from the stacking direction of the stacking structure, that is, the direction of the optical axis of the light-emitting device 1B, is called a top view.

[0036] The substrate 10 is composed of, for example, a silicon (Si) substrate, a gallium nitride (GaN) substrate, a sapphire substrate, etc. A reflective layer 11 is provided on the upper surface of the substrate 10. The reflective layer 11 is composed of, for example, a laminate formed by alternately laminating AlGaN layers and GaN layers, a laminate formed by alternately laminating AlInN layers and GaN layers, etc. The reflective layer 11 reflects the light generated by the light-emitting layer of the nanorods described later toward the side opposite to the substrate 10. In addition, a heat sink for releasing the heat generated by the light-emitting part 30 may be provided on the lower surface of the substrate 10.

[0037] The semiconductor layer 12 is provided on the reflective layer 11. The semiconductor layer 12 is a layer made of an n-type semiconductor material, for example, an n-type GaN layer, specifically, a GaN layer doped with Si.

[0038] The light-emitting part 30 has a plurality of nanorods 31 and a light propagation layer 32. The nanorods 31 are columnar crystal structures protruding and extending on the semiconductor layer 12. The shape of the nanorods 31 is, for example, a prismatic shape, a cylindrical shape, an elliptical cylindrical shape, etc. In the present embodiment, the shape of the nanorods 31 is cylindrical. The diameter of the nanorods 31 is in the nm order, specifically, for example, 10 nm or more and 500 nm or less. The dimension of the nanorods 31 in the stacking direction, that is, the height of the nanorods 31 is, for example, 0.1 μm or more and 5 μm or less.

[0039] The nanorods 31 of the present embodiment correspond to the columnar part of the technical solution.

[0040] In addition, when the top view shape of the nanorods 31 is a circle, the diameter of the nanorods 31 is the diameter of the circle, and when the top view shape of the nanorods 31 is not a circle, the diameter of the nanorods 31 is the diameter of the minimum enclosing circle. For example, when the top view shape of the nanorods 31 is a polygon, the diameter of the nanorods 31 is the diameter of the smallest circle that contains the polygon inside. When the top view shape of the nanorods 31 is an ellipse, the diameter of the nanorods 31 is the diameter of the smallest circle that contains the ellipse inside.

[0041] The center of the nanorods 31 is the center of the circle when the top view shape of the nanorods 31 is a circle, and is the center of the minimum enclosing circle when the top view shape of the nanorods 31 is a non-circular shape. For example, when the top view shape of the nanorods 31 is a polygon, the center of the nanorods 31 is the center of the smallest circle that contains the polygon inside. When the top view shape of the nanorods 31 is an ellipse, the center of the nanorods 31 is the center of the smallest circle that contains the ellipse inside.

[0042] As Figure 5As shown, a plurality of nanocolumns 31 are arranged at a prescribed pitch in a prescribed direction when viewed from above. The nanocolumns 31 can exhibit the effect of a photonic crystal, confining the light emitted from the light-emitting layer 34 within the in-plane direction of the substrate 10 and emitting it in the stacking direction. The in-plane direction of the substrate 10 is the direction along the plane orthogonal to the stacking direction.

[0043] The nanocolumn 31 has a first semiconductor layer 33, a light-emitting layer 34, and a second semiconductor layer 35. Specifically, the nanocolumn 31 has a stacked structure in which the first semiconductor layer 33, the light-emitting layer 34, and the second semiconductor layer 35 are stacked in this order from the semiconductor layer 12 side. Each layer constituting the nanocolumn 31 is formed by epitaxial growth as described later.

[0044] The first semiconductor layer 33 is provided on the semiconductor layer 12. The first semiconductor layer 33 is provided between the semiconductor layer 12 and the light-emitting layer 34. The first semiconductor layer 33 is composed of an n-type semiconductor layer, for example, an n-type GaN layer doped with Si. In the present embodiment, the first semiconductor layer 33 is composed of the same material as the semiconductor layer 12.

[0045] The light-emitting layer 34 is provided on the first semiconductor layer 33. The light-emitting layer 34 is provided between the first semiconductor layer 33 and the second semiconductor layer 35. The light-emitting layer 34 has, for example, a quantum well structure in which a plurality of GaN layers and InGaN layers are alternately stacked. The light-emitting layer 34 emits light by current being injected through the first semiconductor layer 33 and the second semiconductor layer 35. In addition, the number of GaN layers and InGaN layers constituting the light-emitting layer 34 is not particularly limited. In the case of the present embodiment, the light-emitting layer 34 emits blue light in the blue wavelength band of, for example, 430 nm to 470 nm.

[0046] The second semiconductor layer 35 is provided on the light-emitting layer 34. The conductivity type of the second semiconductor layer 35 is different from that of the first semiconductor layer 33. That is, the second semiconductor layer 35 is a layer composed of a p-type semiconductor material, for example, a p-type GaN layer doped with Mg. The first semiconductor layer 33 and the second semiconductor layer 35 function as cladding layers having the function of confining light within the light-emitting layer 34.

[0047] The light propagation layer 32 is provided so as to surround each nanocolumn 31 when viewed from above. Therefore, the light propagation layer 32 is provided in the gap between adjacent nanocolumns 31. The refractive index of the light propagation layer 32 is lower than the refractive index of the light-emitting layer 34. The light propagation layer 32 is composed of, for example, a GaN layer, a titanium oxide (TiO 2 ) layer, or the like. The GaN layer constituting the light propagation layer 32 can be an i-type, an n-type, or a p-type. The light propagation layer 32 causes the light generated in the light-emitting layer 34 to propagate in the planar direction.

[0048] In the light-emitting section 30, a pin diode is formed by a stack of a p-type second semiconductor layer 35, an undoped light-emitting layer 34, and an n-type first semiconductor layer 33. The band gaps of the first semiconductor layer 33 and the second semiconductor layer 35 are larger than the band gap of the light-emitting layer 34. In the light-emitting section 30, when a voltage equivalent to the forward bias voltage of the pin diode is applied between the first electrode 50 and the second electrode 60 to inject current, recombination of electrons and holes occurs in the light-emitting layer 34. Light emission is generated through this recombination.

[0049] The light generated in the light-emitting layer 34 propagates through the light propagation layer 32 in the in-plane direction of the substrate 10 via the first semiconductor layer 33 and the second semiconductor layer 35. At this time, the light forms a standing wave through the effect of the photonic crystal of the nano-columns 31 and is confined in the in-plane direction of the substrate 10. The confined light is amplified in the light-emitting layer 34 and undergoes laser oscillation. That is, the light generated in the light-emitting layer 34 resonates in the in-plane direction of the substrate 10 through the plurality of nano-columns 31 and undergoes laser oscillation. Specifically, the light generated in the light-emitting layer 34 resonates in the in-plane direction of the substrate 10 in the resonance section formed by the plurality of nano-columns 31 and undergoes laser oscillation. Thereafter, the +1st order diffracted light and the -1st order diffracted light generated by the resonance travel as laser light in the stacking direction (Z-axis direction).

[0050] In the light-emitting device 1B, the refractive indices and thicknesses of the first semiconductor layer 33, the second semiconductor layer 35, and the light-emitting layer 34 are designed such that the intensity of the light propagating in the plane direction is maximum at the light-emitting layer 34 in the Z-axis direction.

[0051] In the present embodiment, the laser light traveling toward the substrate 10 side among the laser light traveling in the stacking direction is reflected by the reflection layer 11 and travels toward the second electrode 60 side. As a result, the light-emitting section 30 can emit light from the second electrode 60 side.

[0052] As Figure 3 shown, a mask layer 37 is provided on the semiconductor layer 12. The mask layer 37 is provided between the light propagation layer 32 and the semiconductor layer 12. The mask layer 37 functions as a mask for selectively growing the film forming each nano-column 31 in a specific region on the semiconductor layer 12 in the manufacturing process of the light-emitting section 30. The mask layer 37 is formed of, for example, a silicon oxide layer, a silicon nitride layer, or the like.

[0053] An insulating layer 40 is provided between adjacent light-emitting sections 30 on the semiconductor layer 12. The insulating layer 40 is formed of, for example, a silicon oxide layer. The insulating layer 40 has a function of planarizing the unevenness on the semiconductor layer 12 formed by the light-emitting section 30 and protecting the light-emitting section 30.

[0054] The first electrode 50 is provided on the semiconductor layer 12 on the side of the light-emitting portion 30. The first electrode 50 is provided corresponding to the light-emitting portion 30 and is electrically connected to the light-emitting portion 30 via the semiconductor layer 12. For example, the first electrode 50 constitutes a part of a transistor provided corresponding to the light-emitting portion 30, such as a gate, and can control the amount of current injected into the nanocolumns 31.

[0055] The first electrode 50 may be in ohmic contact with the semiconductor layer 12. In Figure 3 the example of, the first electrode 50 is electrically connected to the first semiconductor layer 33 of each nanocolumn 31 via the semiconductor layer 12. The first electrode 50 is an electrode on the side for injecting current into the light-emitting layer 34. The first electrode 50 is composed of a metal layer such as Ni, Ti, Cr, Pt, or Au, or a laminated metal film formed by laminating them.

[0056] The second electrode 60 is provided on the light-emitting portion 30. The second electrode 60 is another electrode for injecting current into the light-emitting layer 34. The second electrode 60 is provided corresponding to the light-emitting portion 30. The second electrode 60 is provided in contact with a part of the nanocolumns 31 and the light propagation layer 32.

[0057] The second electrode 60 needs to have conductivity and light transmittance. Therefore, the second electrode 60 is composed of a metal layer such as Ni, Ti, Cr, Pt, or Au, or a laminated metal film formed by laminating them, a transparent conductive layer such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), etc. In the case of using a metal layer, in order to have light transmittance, it is preferable to reduce the film thickness of the metal layer to about several tens of nanometers. In addition, the second electrode 60 may also have a laminated structure of a contact layer composed of the above metal layer and a transparent conductive layer. In this case, the contact layer serves to improve the conductivity between the transparent conductive layer and each nanocolumn 31. The light generated in the light-emitting layer 34 is emitted through the second electrode 60.

[0058] The wiring 70 is provided on the insulating layer 40 so as to overlap a part of the second electrode 60 in a top view. The wiring 70 is electrically connected to the second semiconductor layer 35 of each nanocolumn 31 in the light-emitting portion 30 via the second electrode 60. The wiring 70 is composed of a metal layer such as Ni, Ti, Cr, Pt, or Au, or a laminated metal film formed by laminating them.

[0059] The wiring 70 is connected to a driving circuit in an area (not shown) provided on the substrate 10 via, for example, a bonding wire. In addition, the first electrode 50 is connected to a driving circuit in an area (not shown) provided on the substrate 10 via, for example, a bonding wire. Based on such a structure, the light-emitting portion 30 can inject current into the light-emitting layer 34 of each nanocolumn 31 via the first electrode 50 and the second electrode 60 by driving the driving circuit.

[0060] Figure 5 is a top view of the light-emitting part 30. In Figure 5 , all of the nanocolumns 31 initially formed in the manufacturing process described later are represented by dashed lines, and the finally remaining nanocolumns 31 are represented by solid lines. In addition, in Figure 5 , illustration of wirings 70 and the like is omitted.

[0061] As Figure 5 shown, the light-emitting part 30 of the present embodiment is formed in a circular shape in a top view. As described above, the light-emitting part 30 has a nanocolumn group 31A composed of a plurality of nanocolumns 31 having a stacked structure including a first semiconductor layer 33, a light-emitting layer 34, and a second semiconductor layer 35.

[0062] The nanocolumn group 31A of the present embodiment corresponds to the columnar part group of the technical solution.

[0063] The plurality of nanocolumns 31 include a plurality of first nanocolumns 311 and a plurality of second nanocolumns 312 disposed around the plurality of first nanocolumns 311. The number of the second nanocolumns 312 is smaller than the number of the first nanocolumns 311. In a top view, the second electrode 60 overlaps with the plurality of first nanocolumns 311 and the plurality of second nanocolumns 312.

[0064] The first nanocolumn 311 of the present embodiment corresponds to the first columnar part of the technical solution. The second nanocolumn 312 of the present embodiment corresponds to the second columnar part of the technical solution.

[0065] In a top view, the plurality of first nanocolumns 311 are disposed at positions closer to the central part of the nanocolumn group 31A. The top view shape of the first nanocolumn 311 is circular. In contrast, the plurality of second nanocolumns 312 are disposed around the plurality of first nanocolumns 311 at the peripheral part of the nanocolumn group 31A.

[0066] The top view shape of the second nanocolumn 312 is a shape in which a part of a circle is missing. That is, in a top view, the second nanocolumn 312 has a shape in which a part of the shape of the first nanocolumn 311 is missing. Therefore, in a top view, the area of the second nanocolumn 312 is smaller than the area of the first nanocolumn 311. The ratio of the area of the second nanocolumn 312 to the area of the first nanocolumn 311 is not particularly limited. In addition, the top view shape of the second nanocolumn 312 is not constant for all of the second nanocolumns 312 and is randomly different for each second nanocolumn 312. Furthermore, in the present embodiment, the top view shape of the second nanocolumn 312 has a shape in which a part of a circle is missing, that is, in a top view, the second nanocolumn 312 has a shape in which a part of the shape of the first nanocolumn 311 is missing, but not limited to a top view, the shape of the second nanocolumn 312 may also be a shape in which a part of the shape of the first nanocolumn 311 is missing.

[0067] As Figure 3 shown, the height of the second nanocolumn 312 is lower than that of the first nanocolumn 311. Specifically, the height of the second nanocolumn 312 is 4 / 5 or less of the height of the first nanocolumn 311. The height of the second nanocolumn 312 is not constant among all the second nanocolumns 312 and varies randomly according to each second nanocolumn 312. As described above, the height of the nanocolumn 31 is 0.1 μm or more and 5 μm or less. More specifically, the height of the first nanocolumn 311 is, for example, about 800 to 1500 nm. Therefore, the height of the second nanocolumn 312 is, for example, about 640 to 1200 nm.

[0068] The second semiconductor layers 35 of the plurality of first nanocolumns 311 are respectively in contact with the second electrode 60. Therefore, the second electrode 60 is electrically connected to the plurality of first nanocolumns 311 at the central portion of the nanocolumn group 31A. In contrast, the plurality of second nanocolumns 312 are not respectively in contact with the second electrode 60. Therefore, the second electrode 60 is electrically insulated from the plurality of second nanocolumns 312 at the peripheral portion of the nanocolumn group 31A. In addition, in the present embodiment, the second electrode 60 is electrically insulated from the second nanocolumn 312 via the insulating layer 40. Alternatively, the second electrode 60 and the second nanocolumn 312 may be insulated with a gap therebetween.

[0069] Hereinafter, a method for manufacturing the light-emitting device 1B of the present embodiment will be described.

[0070] Figures 4A to 4F is a cross-sectional view showing one step in the manufacturing process of the light-emitting device 1B.

[0071] First, a metal film is formed on the substrate 10 by, for example, sputtering, evaporation, or the like to form the reflective layer 11. Next, a semiconductor layer 12 is formed on the reflective layer 11 by epitaxial growth. As the epitaxial growth method, for example, MOCVD (Metal-Organic Chemical Vapor Deposition) method, MBE (Molecular Beam Epitaxy) method, or the like can be cited.

[0072] Next, as Figure 4A shown, a plurality of nanocolumns 31 are formed over the entire surface of the semiconductor layer 12. Specifically, before forming the nanocolumns 31, a mask layer 37 having a plurality of openings is formed on the semiconductor layer 12. The mask layer 37 is formed, for example, by film formation based on CVD (Chemical Vapor Deposition) method, sputtering method, or the like, and patterning based on photolithography and etching.

[0073] Next, using the mask layer 37 having the opening as a mask, the first semiconductor layer 33 , the light emitting layer 34 , and the second semiconductor layer 35 are epitaxially grown in this order on the semiconductor layer 12 by, for example, MOCVD or MBE, thereby forming a plurality of nanorods 31 simultaneously.

[0074] Then, if Figure 4B As shown, an insulating film is formed around the nanorods 31 to form the light propagation layer 32. At this time, in order to form a film even in a minute gap between adjacent nanorods 31, it is preferable to use, for example, an ALD (Atomic Layer Deposition) method.

[0075] Then, if Figure 4C As shown, the plurality of nanopillars 31 are patterned by photolithography and etching using a resist pattern (not shown). As a result, the plurality of nanopillars 31 are divided into islands to form a plurality of nanopillar groups 31A. In addition, in this process, a hard mask capable of ensuring a larger etching selectivity may be used instead of the resist pattern.

[0076] At this time, if Figure 5 As shown, a plurality of nanocolumns 31 are arranged at equal intervals in the nanocolumn group 31A, so at least a portion of the nanocolumns 31 arranged along the periphery of the nanocolumn group 31A overlaps only a portion of the peripheral portion of the resist pattern. Therefore, the portion of the nanocolumn 31 exposed from the resist pattern is etched and lost. Alternatively, even if the nanocolumn 31 completely overlaps with the resist pattern, the nanocolumn 31 located at the periphery is partially etched due to overetching and is easily lost. As a result, a portion of the peripheral portion of the nanocolumn group 31A is lost, thereby forming a nanocolumn 31d that is thinner than the nanocolumn 31c in the central portion. At this moment, the thin nanocolumn 31d in the peripheral portion of the nanocolumn group 31A has the same height as the nanocolumn 31c in the central portion.

[0077] Then, if Figure 4D As shown, etching is performed to reduce the height of the thin nanocolumns 31d in the peripheral portion of the nanocolumn group 31A. Specifically, wet etching using an alkaline solution or plasma etching to which a chlorine-based gas is added is performed. At this time, by appropriately adjusting the etching time, etching is performed in such a way that the height of the nanocolumns 31d in the peripheral portion of the nanocolumn group 31A becomes about 4 / 5 or less of the height of the nanocolumns 31c in the central portion. The etching in this process is preferably performed under milder conditions than the etching in the previous process. In addition, in this process, it can be performed with the resist pattern in the previous process remaining, or it can be performed after the resist pattern in the previous process is removed.

[0078] Then, if Figure 4EAs shown, an insulating film is formed in such a way as to fill the spaces between the respective nano-column groups 31A, serving as the insulating layer 40. At this time, the insulating layer 40 can be formed, for example, by film formation based on a coating method such as spin coating. The film thickness of the insulating layer 40 is preferably the same as the height of the nano-columns 31 or thicker than the height of the nano-columns 31. In addition, when the film thickness of the insulating layer 40 is thicker than the height of the nano-columns 31 and the respective nano-column groups 31A are buried in the insulating layer 40, an opening for contacting the second electrode 60 may be formed in the next process.

[0079] Next, as Figure 4F shown, a second electrode 60 electrically connected to each nano-column 31 of the nano-column group 31A is formed. Specifically, the second electrode 60 is formed, for example, by film formation and patterning of a metal film or a transparent conductive layer based on a sputtering method, a vacuum evaporation method, etc.

[0080] Next, a wiring 70 is formed by film formation and patterning using a sputtering method or a vacuum evaporation method. Thus, the Figure 3 light-emitting device 1B of the present embodiment shown is completed. Furthermore, formation of the first electrode 50, installation of a driving circuit, electrical connection of the driving circuit to the first electrode 50 and the second electrode 60 based on wire bonding, etc. are performed.

[0081] (Effect of the present embodiment)

[0082] First, the problems of the existing light-emitting device will be described.

[0083] Figure 6 is a diagram for explaining the problems of the conventional light-emitting device 80. In Figure 6 , the same reference numerals are assigned to the same components as Figure 3 .

[0084] As also described in the above description of the manufacturing method, as Figure 6 shown, a part of the defective thin nano-columns 31d is likely to remain on the outer periphery of the nano-column group 31A. Although the shape of such nano-columns 31d is incomplete, they are electrically connected to the second electrode 60, so they become paths of the leakage current L due to disorders in the crystal structure, etc. As a result, there may be problems such as a decrease in luminous efficiency and failure to obtain a specified luminous amount, instability of the emission wavelength, and unwanted emission in areas other than the original emission area.

[0085] In view of the above problems, the light-emitting device 1B of the present embodiment includes: a substrate 10; a nano-column group 31A composed of a plurality of nano-columns 31 having a stacked structure including a first semiconductor layer 33, a light-emitting layer 34, and a second semiconductor layer 35; and a second electrode 60 provided on the plurality of nano-columns 31 to inject current into the plurality of nano-columns 31. The plurality of nano-columns 31 include a plurality of first nano-columns 311 and a plurality of second nano-columns 312 disposed around the plurality of first nano-columns 311. In a plan view, the second nano-column 312 has a shape in which a part of the shape of the first nano-column 311 is missing, the height of the second nano-column 312 is lower than the height of the first nano-column 311, and the second electrode 60 is electrically insulated from the plurality of second nano-columns 312 at the peripheral portion of the nano-column group 31A.

[0086] That is, in the light-emitting device 1B of the present embodiment, the second nano-column 312 having a shape in which a part of the shape of the first nano-column 311 is missing remains at the peripheral portion of the nano-column group 31A, but the height of the remaining second nano-column 312 is lower than the height of the first nano-column 311, and the second electrode 60 is electrically insulated from the second nano-column 312. Thus, the second nano-column 312 does not become a path for leakage current. Therefore, according to the light-emitting device 1B of the present embodiment, the light-emitting efficiency can be improved, and a desired light-emitting amount and light-emitting wavelength can be obtained in the original light-emitting region.

[0087] Ideally, no nano-columns with partial defects remain, but this is difficult in reality. This is because if the second etching is overperformed in order to completely remove the nano-columns remaining in the first etching, the inner nano-columns that were not originally defective in the first etching will be damaged. From this perspective, as in the present embodiment, even if the second etching is performed lightly and the second nano-column 312 remains around the first nano-column 311, as long as it is separated from the second electrode 60 and electrically insulated, it will not become a path for leakage current. Therefore, as in the present embodiment, compared with the case where the second nano-column 312 is completely removed, the generation of leakage current can be efficiently suppressed when the second nano-column 312 remains.

[0088] In addition, in the light-emitting device 1B of the present embodiment, the height of the second nano-column 312 is 4 / 5 or less of the height of the first nano-column 311.

[0089] For example, if the height of the first nano-column 311 is the minimum value of 800 nm within the range of the present embodiment, the height of the second nano-column 312 is 640 nm, which is 160 nm lower than the height of the first nano-column 311. At this time, as Figure 3As shown, there is an insulating layer 40 with a film thickness of 160 nm between the second nanocolumn 312 and the second electrode 60. Generally, when considering the case of applying a voltage of about 20 V between the first electrode 50 and the second electrode 60, it is considered that if there is an insulating layer 40 with a film thickness of 160 nm, an electrically insulating state can be generally ensured. According to the insight of the present inventor, if a voltage is gradually applied to an insulating film with a film thickness of 100 nm formed by CVD method, a minute leakage current starts to occur from the moment when the voltage becomes about 20 V. Therefore, it is considered that if the film thickness is 1.5 times or more the film thickness at which the minute leakage current starts to occur, there is almost no problem.

[0090] In addition, in the light-emitting device 1B of the present embodiment, the number of the second nanocolumns 312 is smaller than the number of the first nanocolumns 311.

[0091] According to this structure, since the majority of the first nanocolumns 311 having a normal top view shape and no defects, a light-emitting portion 30 having a desired area can be ensured.

[0092] In addition, in the light-emitting device 1B of the present embodiment, in a top view, the second electrode 60 overlaps with a plurality of the first nanocolumns 311 and a plurality of the second nanocolumns 312.

[0093] According to this structure, even if a plurality of defective second nanocolumns 312 and the second electrode 60 overlap with each other in a top view, generation of leakage current can be suppressed.

[0094] In addition, the technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

[0095] For example, in the above-described embodiment, the light-emitting layer made of an InGaN-based material has been described, but as the light-emitting layer, various semiconductor materials can be used according to the wavelength of the emitted light. For example, semiconductor materials such as AlGaN-based, AlGaAs-based, InGaAs-based, InGaAsP-based, InP-based, GaP-based, and AlGaP-based can be used. In addition, the diameter or pitch of the columnar structure can be appropriately changed according to the wavelength of the emitted light.

[0096] In addition, the specific descriptions of the shapes, numbers, arrangements, materials, etc. of the respective components of the light-emitting device and the projector are not limited to the above-described embodiment, and can be appropriately changed. In the above-described embodiment, an example of using the light-emitting device of the present invention as a self-luminous imager has been given, but the present invention can also be applied to a projector that uses the light-emitting device of the present invention as a lighting device and uses, for example, a transmissive liquid crystal display element as a light modulation device. In addition, the present invention can also be applied to a projector that uses a reflective liquid crystal display element or a digital micromirror device as a light modulation device.

[0097] In the above-described embodiments, an example in which the light-emitting device of the present invention is mounted on a projector is shown, but it is not limited thereto. The light-emitting device of the present invention can also be applied to a light-emitting element of a μLED (micro-Light Emitting Diode) display in which minute light-emitting elements are arranged in an array to display an image. In addition, the light-emitting device of the present invention can also be applied to lighting fixtures, headlamps of automobiles, and the like.

[0098] The light-emitting device according to one embodiment of the present invention may also have the following configuration.

[0099] The light-emitting device according to one embodiment of the present invention includes: a substrate; a columnar portion group provided on the substrate and composed of a plurality of columnar portions having a stacked structure including a first semiconductor layer, a light-emitting layer, and a second semiconductor layer; and an electrode provided on the plurality of columnar portions to inject current into the plurality of columnar portions. The plurality of columnar portions include a plurality of first columnar portions and a plurality of second columnar portions disposed around the plurality of first columnar portions. The second columnar portions have a shape in which a part of the shape of the first columnar portions is missing, the height of the second columnar portions is lower than the height of the first columnar portions, and the electrode is electrically insulated from the plurality of second columnar portions.

[0100] In the light-emitting device according to one embodiment of the present invention, the height of the second columnar portions may be 4 / 5 or less of the height of the first columnar portions.

[0101] In the light-emitting device according to one embodiment of the present invention, the number of the second columnar portions may be smaller than the number of the first columnar portions.

[0102] In the light-emitting device according to one embodiment of the present invention, when viewed from above in the stacking direction of the stacked structure, the electrode may overlap with the plurality of first columnar portions and the plurality of second columnar portions.

[0103] The light-emitting device according to one embodiment of the present invention may also have an insulating layer covering the columnar portion group, and the electrode is electrically insulated from the second columnar portions via the insulating layer.

[0104] The projector according to one embodiment of the present invention may also have the following structure.

[0105] The projector according to one embodiment of the present invention includes the light-emitting device according to one embodiment of the present invention.

[0106] The manufacturing method of the light-emitting device according to one embodiment of the present invention may also have the following configuration.

[0107] A manufacturing method of a light-emitting device according to an aspect of the present invention includes: a step of forming a plurality of columnar portions having a stacked structure including a first semiconductor layer, a light-emitting layer, and a second semiconductor layer on a substrate; a step of forming a columnar portion group by etching the plurality of columnar portions; a step of etching the columnar portion group; and a step of forming an electrode electrically connected to the columnar portion group. In the step of forming the plurality of columnar portions, the plurality of columnar portions include a plurality of first columnar portions and a plurality of second columnar portions disposed around the plurality of first columnar portions, and the second columnar portions have a shape in which a part of the shape of the first columnar portions is missing. In the step of etching the columnar portion group, the second columnar portions are etched such that the height of the second columnar portions is lower than the height of the first columnar portions. In the step of forming the electrode, the electrode is formed such that the second columnar portions are electrically insulated from the electrode.

[0108] In a manufacturing method of a light-emitting device according to an aspect of the present invention, it may also be that, in the step of forming the electrode, the electrode is formed such that, in a plan view observed from the stacking direction of the stacked structure, the electrode overlaps with the plurality of first columnar portions and the plurality of second columnar portions.

[0109] In a manufacturing method of a light-emitting device according to an aspect of the present invention, it may also be that it includes a step of forming an insulating layer covering the columnar portion group, and in the step of forming the electrode, the electrode is formed such that the electrode is electrically insulated from the second columnar portions via the insulating layer.

Claims

1. A light-emitting device, comprising: a substrate; a columnar portion group provided on the substrate and composed of a plurality of columnar portions having a stacked structure including a first semiconductor layer, a light-emitting layer, and a second semiconductor layer; and an electrode provided on the plurality of columnar portions for injecting current into the plurality of columnar portions, the plurality of columnar portions including a plurality of first columnar portions and a plurality of second columnar portions disposed around the plurality of first columnar portions, when viewed from above in the stacking direction of the stacked structure, the top view shape of the second columnar portion has a shape formed by lacking a part of the top view shape of the first columnar portion, the height of the second columnar portion is lower than the height of the first columnar portion, the electrode is electrically insulated from the plurality of second columnar portions.

2. The light-emitting device according to claim 1, wherein the height of the second columnar portion is 4 / 5 or less of the height of the first columnar portion.

3. The light-emitting device according to claim 1 or 2, wherein the number of the second columnar portions is smaller than the number of the first columnar portions.

4. The light-emitting device according to claim 1 or 2, wherein when viewed from above in the stacking direction of the stacked structure, the electrode overlaps with the plurality of first columnar portions and the plurality of second columnar portions.

5. The light-emitting device according to claim 4, wherein the light-emitting device has an insulating layer covering the columnar portion group, the electrode is electrically insulated from the second columnar portion with the insulating layer therebetween.

6. A projector having the light-emitting device according to any one of claims 1 to 5.

7. A method for manufacturing a light-emitting device, comprising the following steps: forming a plurality of columnar portions having a stacked structure including a first semiconductor layer, a light-emitting layer, and a second semiconductor layer on a substrate; forming a columnar portion group by etching the plurality of columnar portions; etching the columnar portion group; and forming an electrode electrically connected to the columnar portion group, in the step of forming the plurality of columnar portions, the plurality of columnar portions include a plurality of first columnar portions and a plurality of second columnar portions disposed around the plurality of first columnar portions, when viewed from above in the stacking direction of the stacked structure, the top view shape of the second columnar portion has a shape formed by lacking a part of the top view shape of the first columnar portion, in the step of etching the columnar portion group, etching the second columnar portion so that the height of the second columnar portion is lower than the height of the first columnar portion, in the step of forming the electrode, forming the electrode so that the second columnar portion is electrically insulated from the electrode.

8. The method for manufacturing a light-emitting device according to claim 7, wherein in the step of forming the electrode, forming the electrode so that when viewed from above in the stacking direction of the stacked structure, the electrode overlaps with the plurality of first columnar portions and the plurality of second columnar portions.

9. The method for manufacturing a light-emitting device according to claim 8, wherein the method for manufacturing the light-emitting device has a step of forming an insulating layer covering the columnar portion group, In the process of forming the electrode, the electrode is formed in such a manner that the electrode and the second columnar portion are electrically insulated from each other with the insulating layer therebetween.

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