Light-emitting devices, projectors, displays, and head-mounted displays

Abstract

To provide a light emitting device that can reduce charges accumulated in an insulating layer.SOLUTION: A light emitting device includes a light emitting portion including a first semiconductor layer, a second semiconductor layer having a different conductivity type from the first semiconductor layer, and a light emitting layer provided between the first semiconductor layer and the second semiconductor layer, an insulating layer covering the light emitting portion, and a conductive layer provided in the insulating layer, and electrically isolated from the light emitting portion, and to which a predetermined potential is applied.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a light-emitting device, a projector, a display, and a head-mounted display.

Background Art

[0002] Semiconductor lasers are expected as high-brightness next-generation light sources. Among them, semiconductor lasers applying nanocolumns are expected to achieve high-output light emission with a narrow emission angle due to the effect of photonic crystals by the nanocolumns.

[0003] For example, Patent Document 1 describes a light-emitting device including an n-type GaN buffer layer, a plurality of GaN nanorods, a transparent electrode provided at the tip of the GaN nanorods, and a transparent insulating layer provided between the n-type GaN buffer layer and the transparent electrode.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a light-emitting device as described above, for example, when processing the transparent insulating layer, charges may accumulate in the transparent insulating layer. The charges accumulated in the transparent insulating layer affect the characteristics of the light-emitting device.

Means for Solving the Problems

[0006] One aspect of the light-emitting device according to the present invention is a light-emitting portion having a first semiconductor layer, a second semiconductor layer having a different conductivity type from the first semiconductor layer, and a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer, an insulating layer covering the light-emitting portion, A conductive layer is provided in the insulating layer, which is electrically isolated from the light-emitting portion and to which a predetermined potential is applied, It holds.

[0007] One aspect of the projector according to the present invention is: It has one embodiment of the aforementioned light-emitting device.

[0008] One aspect of the display according to the present invention is: It has one embodiment of the aforementioned light-emitting device.

[0009] One embodiment of the head-mounted display according to the present invention is: It has one embodiment of the aforementioned light-emitting device. [Brief explanation of the drawing]

[0010] [Figure 1] A schematic cross-sectional view showing the light-emitting device according to this embodiment. [Figure 2] A schematic plan view showing the light-emitting device according to this embodiment. [Figure 3] A schematic plan view showing the light-emitting device according to this embodiment. [Figure 4] A schematic cross-sectional view showing the manufacturing process of the light-emitting device according to this embodiment. [Figure 5] A schematic cross-sectional view showing the manufacturing process of the light-emitting device according to this embodiment. [Figure 6] A schematic cross-sectional view showing the manufacturing process of the light-emitting device according to this embodiment. [Figure 7] A schematic cross-sectional view showing the manufacturing process of the light-emitting device according to this embodiment. [Figure 8] A schematic diagram showing the projector according to this embodiment. [Figure 9] A schematic plan view showing the display according to this embodiment. [Figure 10] A schematic cross-sectional view showing the display according to this embodiment. [Figure 11] A schematic perspective view showing the head-mounted display according to this embodiment. [Figure 12]A diagram schematically showing an image forming device and a light guiding device of a head-mounted display according to this embodiment.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present invention described in the claims. Also, not all of the configurations described below are essential constituent elements of the present invention.

[0012] 1. Light Emitting Device 1.1. Configuration First, the light emitting device according to this embodiment will be described while referring to the drawings. FIG. 1 is a cross-sectional view schematically showing a light emitting device 100 according to this embodiment. FIG. 2 is a plan view schematically showing the light emitting device 100 according to this embodiment. Note that FIG. 1 is a cross-sectional view taken along line I-I of FIG. 2.

[0013] As shown in FIGS. 1 and 2, the light emitting device 100 has, for example, a substrate 10, a light emitting portion 20, an insulating layer 40, a conductive layer 50, a first electrode 60, a second electrode 62, a first wiring 70, a second wiring 72, and a third wiring 74. The light emitting device 100 is, for example, a semiconductor laser. For the sake of convenience, in FIG. 2, members other than the conductive layer 50 and the first electrode 60 are omitted, and the second wiring 72 and the third wiring 74 are shown in a perspective view.

[0014] As shown in FIG. 1, the substrate 10 has, for example, a support substrate 12 and a buffer layer 14. The support substrate 12 is, for example, a Si substrate, a GaN substrate, a sapphire substrate, a SiC substrate, or the like.

[0015] The buffer layer 14 is provided on the support substrate 12. The buffer layer 14 is, for example, a Si-doped n-type GaN layer. Although not shown in the figures, a mask layer for growing the columnar portion 30 of the light-emitting portion 20 may be provided on the buffer layer 14. The mask layer may be, for example, a titanium layer, a silicon oxide layer, a titanium oxide layer, or an aluminum oxide layer.

[0016] In this specification, when referring to the stacking direction (hereinafter simply referred to as the "stacking direction") between the first semiconductor layer 32 and the light-emitting layer 34 of the columnar portion 30, the direction from the light-emitting layer 34 toward the second semiconductor layer 36 of the columnar portion 30 is described as "up," and the direction from the light-emitting layer 34 toward the first semiconductor layer 32 is described as "down." The direction perpendicular to the stacking direction is also referred to as the "in-plane direction."

[0017] The light-emitting unit 20 is provided on the substrate 10. In the illustrated example, the light-emitting unit 20 is provided on the buffer layer 14. The light-emitting unit 20 has, for example, a plurality of columnar portions 30.

[0018] The columnar portion 30 is provided on the substrate 10. The columnar portion 30 protrudes upward from the substrate 10. The columnar portion 30 protrudes upward from the buffer layer 14 provided on the support substrate 12. The columnar portion 30 is also called, for example, a nanocolumn, nanowire, nanorod, or nanopillar. The planar shape of the columnar portion 30 is, for example, a polygon such as a regular hexagon or a circle.

[0019] The diameter of the columnar portion 30 is, for example, between 50 nm and 500 nm. By setting the diameter of the columnar portion 30 to 500 nm or less, a high-quality crystalline light-emitting layer 34 can be obtained, and the strain inherent in the light-emitting layer 34 can be reduced. As a result, the light generated in the light-emitting layer 34 can be amplified with high efficiency.

[0020] Furthermore, "the diameter of the columnar portion 30" refers to the diameter if the planar shape of the columnar portion 30 is a circle, and the diameter of the smallest inclusion circle if the planar shape of the columnar portion 30 is not a circle. For example, if the planar shape of the columnar portion 30 is a polygon, the diameter of the smallest circle that contains the polygon is the diameter of the smallest circle that contains the ellipse is the diameter of the smallest circle that contains the ellipse.

[0021] Multiple columnar portions 30 are provided. The multiple columnar portions 30 are spaced apart from each other. In the illustrated example, there is a gap between adjacent columnar portions 30. The spacing between adjacent columnar portions 30 is, for example, 1 nm to 500 nm. The multiple columnar portions 30 are arranged in a predetermined direction at a predetermined pitch when viewed from the stacking direction. The multiple columnar portions 30 are arranged, for example, in a triangular lattice or a square lattice. The multiple columnar portions 30 can exhibit the effect of a photonic crystal.

[0022] The "pitch of the columnar parts 30" refers to the distance between the centers of adjacent columnar parts 30 in a predetermined direction. The "center of the columnar part 30" refers to the center of the circle if the planar shape of the columnar part 30 is a circle, and to the center of the smallest inclusion circle if the planar shape of the columnar part 30 is not a circle. For example, if the planar shape of the columnar part 30 is a polygon, the center of the smallest circle that contains the polygon is the center of the polygon, and if the planar shape of the columnar part 30 is an ellipse, the center of the smallest circle that contains the ellipse is the center of the ellipse.

[0023] The columnar portion 30 has a first semiconductor layer 32, an emissive layer 34, and a second semiconductor layer 36. The first semiconductor layer 32, the emissive layer 34, and the second semiconductor layer 36 are, for example, group III nitride semiconductors and have a wurtzite crystal structure.

[0024] The first semiconductor layer 32 is provided on the buffer layer 14. The first semiconductor layer 32 protrudes upward from the buffer layer 14. The first semiconductor layer 32 is provided between the substrate 10 and the light-emitting layer 34. The first semiconductor layer 32 is a semiconductor layer of a first conductivity type. The first conductivity type is, for example, n-type. The first semiconductor layer 32 is, for example, a Si-doped n-type GaN layer.

[0025] The light-emitting layer 34 is provided on the first semiconductor layer 32. The light-emitting layer 34 is provided between the first semiconductor layer 32 and the second semiconductor layer 36. The light-emitting layer 34 generates light when an electric current is injected. The light-emitting layer 34 has, for example, a well layer and a barrier layer. The well layer and the barrier layer are i-type semiconductor layers that are not intentionally doped with impurities. The well layer is, for example, an InGaN layer. The barrier layer is, for example, a GaN layer. The light-emitting layer 34 has an MQW (Multiple Quantum Well) structure composed of the well layer and the barrier layer.

[0026] The number of well layers and barrier layers constituting the light-emitting layer 34 is not particularly limited. For example, only one well layer may be provided, in which case the light-emitting layer 34 has an SQW (Single Quantum Well) structure.

[0027] The second semiconductor layer 36 is provided on the light-emitting layer 34. The second semiconductor layer 36 is provided between the light-emitting layer 34 and the second electrode 62. The second semiconductor layer 36 is a semiconductor layer of a second conductivity type different from the first conductivity type. The second conductivity type is, for example, p-type. The second semiconductor layer 36 is, for example, a Mg-doped p-type GaN layer. The first semiconductor layer 32 and the second semiconductor layer 36 are cladding layers that have the function of confining light in the light-emitting layer 34.

[0028] Although not shown in the figures, an Optical Confinement Layer (OCL) consisting of an i-type InGaN layer and a GaN layer may be provided between the first semiconductor layer 32 and the light-emitting layer 34, and between the light-emitting layer 34 and the second semiconductor layer 36. The second semiconductor layer 36 may also have an Electron Blocking Layer (EBL) consisting of a p-type AlGaN layer.

[0029] In the light-emitting device 100, a PIN diode is formed by a p-type second semiconductor layer 36, an i-type light-emitting layer 34 that is not intentionally doped with impurities, and an n-type first semiconductor layer 32. When a forward bias voltage of the PIN diode is applied between the first electrode 60 and the second electrode 62 in the light-emitting device 100, current is injected into the light-emitting layer 34, causing recombination of electrons and holes in the light-emitting layer 34. This recombination generates light emission. The light generated in the light-emitting layer 34 propagates in the in-plane direction, forming a standing wave due to the photonic crystal effect of the multiple columnar portions 30, and gaining in the light-emitting layer 34, resulting in laser oscillation. The light-emitting device 100 then emits the +1st-order diffracted light and -1st-order diffracted light as laser light in the stacking direction.

[0030] Although not shown in the figures, a reflective layer may be provided between the support substrate 12 and the buffer layer 14, or below the support substrate 12. This reflective layer is, for example, a DBR (Distributed Bragg Reflector) layer. This reflective layer can reflect the light generated in the light-emitting layer 34, allowing the light-emitting device 100 to emit light only from the second electrode 62 side.

[0031] The insulating layer 40 is provided on the substrate 10 and the light-emitting part 20. The insulating layer 40 covers the substrate 10 and the light-emitting part 20. The insulating layer 40 is provided with a first contact hole 42 and a second contact hole 44. The bottom surface of the first contact hole 42 is made up of a first electrode 60. The bottom surface of the second contact hole 44 is made up of a second electrode 62.

[0032] As shown in Figure 1, the insulating layer 40 includes, for example, a first layer 46 and a second layer 48. The first layer 46 is provided on the substrate 10 and on the light-emitting part 20. The first layer 46 is provided between the substrate 10 and the conductive layer 50. The first layer 46 is, for example, a layer made of nitride. By making the first layer 46 a layer made of nitride, the water resistance of the light-emitting device 100 can be improved. The first layer 46 is, for example, a silicon nitride (SiN) layer, a silicon oxide nitride (SiON) layer, etc. Note that the first layer 46 may also be a silicon oxide (SiO2) layer.

[0033] The second layer 48 is provided on the first layer 46 and the conductive layer 50. The second layer 48 is provided between the conductive layer 50 and the second wiring 72. The dielectric constant of the second layer 48 is, for example, smaller than the dielectric constant of the first layer 46. The second layer 48 is, for example, a layer made of organic material. By making the first layer 46 a layer made of organic material, the flatness of the upper surface of the insulating layer 40 can be improved. This can improve the flatness of the second wiring 72. The second layer 48 is, for example, a polyimide layer. The second layer 48 may also be a silicon oxide layer. That is, the material constituting the first layer 46 and the material constituting the second layer 48 may be different. The dielectric constant of the material constituting the first layer 46 and the dielectric constant of the material constituting the second layer 48 may be different.

[0034] The conductive layer 50 is provided within the insulating layer 40. In the illustrated example, the top, bottom, and side surfaces of the conductive layer 50 are in contact with the insulating layer 40. The conductive layer 50 is provided between the first layer 46 and the second layer 48 of the insulating layer 40. The conductive layer 50 is provided between the substrate 10 and the second wiring 72. The conductive layer 50 is provided between the substrate 10 and the third wiring 74. The conductive layer 50 is electrically isolated from the light-emitting part 20. The conductive layer 50 is separated from the light-emitting part 20.

[0035] The thickness of the conductive layer 50 is, for example, 10 nm to 100 nm, preferably 30 nm to 70 nm. The distance D1 in the stacking direction between the conductive layer 50 and the second wiring 72 is, for example, smaller than the distance D2 in the stacking direction between the conductive layer 50 and the substrate 10. In the stacking direction, the conductive layer 50 is located on the side opposite to the substrate 10 from the light-emitting layer 34. In the illustrated example, the conductive layer 50 is located above the light-emitting layer 34.

[0036] The conductive layer 50 surrounds the light-emitting portion 20 when viewed from the stacking direction. The conductive layer 50 does not overlap with the light-emitting portion 20 when viewed from the stacking direction. As shown in Figure 2, the conductive layer 50 has, for example, a ring-shaped first portion 52 and a rod-shaped second portion 54 connected to the first portion 52.

[0037] The sheet resistance of the conductive layer 50 is lower than the sheet resistance of the buffer layer 14. The sheet resistance of the conductive layer 50 is lower than, for example, the sheet resistance of electrodes 60, 62 and wirings 70, 72, 74. The conductive layer 50 is conductive. The conductive layer 50 is a metallic layer. The conductive layer 50 is, for example, a titanium (Ti) layer or a titanium-tungsten (TiW) layer.

[0038] A predetermined potential is applied to the conductive layer 50. The conductive layer 50 is connected to an external terminal (not shown). The conductive layer 50 is not floating. The potential applied to the conductive layer 50 is different from, for example, the potential applied to the first electrode 60. The potential applied to the conductive layer 50 is different from, for example, the potential applied to the second electrode 62.

[0039] The potential applied to the conductive layer 50 is, for example, the potential between the potential applied to the first electrode 60 and the potential applied to the second wiring 72. Alternatively, the potential applied to the conductive layer 50 is the same potential as the potential applied to the first electrode 60. Alternatively, the potential applied to the conductive layer 50 is the same potential as the potential applied to the second wiring 72. When the first electrode 60 is the cathode and the second electrode 62 is the anode, the potential applied to the conductive layer 50 is, for example, greater than the potential applied to the first electrode 60 and less than the potential applied to the second wiring 72. The potential applied to the conductive layer 50 is, for example, the potential between the potential applied to the first wiring 70 and the potential applied to the third wiring 74. The potential applied to the conductive layer 50 may also be the ground potential. The predetermined potential applied to the conductive layer 50 may change during the operation of the light-emitting device 100.

[0040] The first electrode 60 is provided on the substrate 10, as shown in Figure 1. In the illustrated example, a portion of the buffer layer 14 is recessed, and the first electrode 60 is provided in the recessed portion of the buffer layer 14. The buffer layer 14 may be in ohmic contact with the first electrode 60. The first electrode 60 is provided between the buffer layer 14 and the first wiring 70. The first electrode 60 is electrically connected to the first semiconductor layer 32. In the illustrated example, the first electrode 60 is electrically connected to the first semiconductor layer 32 via the buffer layer 14.

[0041] As the first electrode 60, for example, one can be used in which layers are stacked in the order of a Cr layer, a Ni layer, and an Au layer from the buffer layer 14 side. The first electrode 60 is one of the electrodes for injecting current into the light-emitting layer 34. The first electrode 60 is, for example, a cathode.

[0042] The second electrode 62 is provided on the side of the light-emitting unit 20 opposite to the substrate 10. The second electrode 62 is provided on the light-emitting unit 20. The second electrode 62 is provided between the light-emitting unit 20 and the second wiring 72. In the illustrated example, the second electrode 62 is provided on the second semiconductor layer 36. The second semiconductor layer 36 may be in ohmic contact with the second electrode 62. In the example shown in Figure 2, the shape of the second electrode 62 is circular.

[0043] The second electrode 62 is, for example, a stack of Pd, Pt, Ni, and Au layers in that order from the second semiconductor layer 36 side, or a single layer of metal. The electrical resistivity of the second electrode 62 is smaller than that of the second wiring 72. The thickness of the second electrode 62 is smaller than the thickness of the second wiring 72. The second electrode 62 is the other electrode for injecting current into the light-emitting layer 34. The second electrode 62 is, for example, an anode.

[0044] As shown in Figure 1, the first wiring 70 is provided on the first electrode 60 and on the insulating layer 40. The first wiring 70 is located in the first contact hole 42. The first wiring 70 is connected to the first electrode 60. The material of the first wiring 70 is, for example, a laminated structure with a Cr layer and an Au layer in that order from the first electrode 60 side, or a single layer of metal.

[0045] The second wiring 72 is provided on the second electrode 62 and on the insulating layer 40. The second wiring 72 is located in the second contact hole 44. The second wiring 72 is connected to the second electrode 62. When viewed from the lamination direction, the second wiring 72 overlaps with the light-emitting section 20 and the second electrode 62. The material of the second wiring 72 is a material that transmits light generated in the light-emitting layer 34. The material of the second wiring 72 is, for example, ITO (Indium Tin Oxide) or ZnO.

[0046] The third wiring 74 is provided on the second wiring 72 and on the insulating layer 40. The third wiring 74 is not located in the second contact hole 44. When viewed from the lamination direction, the third wiring 74 does not overlap with, for example, the second electrode 62. The third wiring 74 is electrically connected to the second electrode 62 via the second wiring 72. The material of the third wiring 74 is, for example, the same as that of the first wiring 70.

[0047] Although the above description focused on an InGaN-based light-emitting layer 34, various material systems capable of emitting light when current is injected according to the wavelength of the emitted light can be used as the light-emitting layer 34. For example, semiconductor materials such as AlGaN, AlGaAs, InGaAs, InGaAsP, InP, GaP, and AlGaP can be used.

[0048] Furthermore, the light-emitting device 100 is not limited to a laser; it may also be an LED (Light Emitting Diode).

[0049] Furthermore, the number of light-emitting units 20 is not particularly limited. For example, as shown in Figure 3, there may be multiple light-emitting units 20. In this case, the conductive layer 50 is arranged between adjacent light-emitting units 20. The first electrode 60 and the second electrode 62 may be configured to supply current independently to each of the multiple light-emitting units 20. In the illustrated example, when viewed from the stacking direction, the multiple light-emitting units 20 are arranged in a regular triangular grid. For convenience, other components besides the light-emitting units 20 are omitted from the illustration in Figure 3.

[0050] 1.2. Effects The light-emitting device 100 includes a substrate 10, a light-emitting section 20 having a first semiconductor layer 32, a second semiconductor layer 36 having a different conductivity type from the first semiconductor layer 32, and a light-emitting layer 34 provided between the first semiconductor layer 32 and the second semiconductor layer 36, an insulating layer 40 covering the light-emitting section 20, and a conductive layer 50 provided in the insulating layer 40, which is electrically isolated from the light-emitting section 20 and to which a predetermined potential is applied.

[0051] Therefore, in the light-emitting device 100, the conductive layer 50 can release the charge accumulated in the insulating layer 40 to the outside. This reduces the charge accumulated in the insulating layer 40. As a result, the influence of the charge accumulated in the insulating layer 40 on the characteristics of the light-emitting device 100 can be reduced.

[0052] For example, if a large amount of charge accumulates in the insulating layer, the response of the light-emitting part will decrease, making quick switching, i.e., on / off operation, impossible. Therefore, for example, if there are multiple light-emitting parts, some light-emitting parts may turn off later than the others when the goal is to turn off all of them, or some light-emitting parts may turn on later than the goal is to turn on all of them. Also, if there are light-emitting parts that emit red light, green light, and blue light, even if the goal is to turn off all of them, a small amount of blue light may remain, causing a white cast instead of black, or the blue light may turn on later than the goal is to turn on all of them, disrupting the color balance and causing a color shift.

[0053] As described above, in the light-emitting device 100, the conductive layer 50 can reduce the charge accumulated in the insulating layer 40, thus avoiding such problems.

[0054] The light-emitting device 100 includes a substrate 10, a first electrode 60 provided on the substrate 10 and electrically connected to a first semiconductor layer 32, a second electrode 62 provided on the opposite side of the light-emitting section 20 from the substrate 10 and electrically connected to a second semiconductor layer 36, and a second wiring 72 provided on the insulating layer 40 and connected to the second electrode 62. The first semiconductor layer 32 is provided between the substrate 10 and the light-emitting layer 34, and the conductive layer 50 is provided between the substrate 10 and the second wiring 72. The predetermined potential applied to the conductive layer 50 is the potential between the potential applied to the first electrode 60 and the potential applied to the second wiring 72, the same potential as the potential applied to the first electrode 60, or the same potential as the potential applied to the second wiring 72. Therefore, in the light-emitting device 100, the conductive layer 50 can block the electric field between the substrate 10 and the second wiring 72, thereby reducing the capacitance, i.e., parasitic capacitance, caused by the substrate 10, the second wiring 72, and the insulating layer 40.

[0055] In the light-emitting device 100, the light-emitting section 20 has a plurality of columnar sections 30, and each of the columnar sections 30 has a first semiconductor layer 32, a second semiconductor layer 36, and a light-emitting layer 34. Therefore, in the light-emitting device 100, dislocations occurring in the light-emitting layer 34 can be reduced, and a high-quality crystalline light-emitting layer 34 can be obtained.

[0056] In the light-emitting device 100, the distance D1 between the conductive layer 50 and the second wiring 72 is smaller than the distance D2 between the conductive layer 50 and the substrate 10. The second wiring 72 is located in a position that is more exposed to noise than the substrate 10. Therefore, by making the distance D1 smaller than the distance D2, the conductive layer 50 can block noise that has entered from the second wiring 72 before it reaches deep into the insulating layer 40. This stabilizes the characteristics of the light-emitting device 100.

[0057] In the light-emitting device 100, the conductive layer 50 is located on the opposite side of the substrate 10 from the light-emitting layer 34 in the stacking direction. Therefore, in the light-emitting device 100, noise entering from the second wiring 72 can be blocked by the conductive layer 50 before it reaches the depth of the light-emitting layer 34. This stabilizes the characteristics of the light-emitting device 100.

[0058] In the light-emitting device 100, the conductive layer 50 surrounds the light-emitting section 20 when viewed from the stacking direction. Therefore, in the light-emitting device 100, the conductive layer 50 can reduce the charge accumulated around the light-emitting section 20.

[0059] In the light-emitting device 100, the insulating layer 40 has a first layer 46 provided between the substrate 10 and the conductive layer 50, and a second layer 48 provided between the conductive layer 50 and the second wiring 72. The dielectric constant of the second layer 48 is smaller than that of the first layer 46. Therefore, in the light-emitting device 100, the parasitic capacitance on the second wiring 72 side, which is susceptible to noise intrusion, can be reduced. This stabilizes the characteristics of the light-emitting device 100.

[0060] 2. Method for manufacturing a light-emitting device Next, the manufacturing method of the light-emitting device 100 according to this embodiment will be described with reference to the drawings. Figures 4 to 7 are schematic cross-sectional views showing the manufacturing process of the light-emitting device 100 according to this embodiment.

[0061] As shown in Figure 4, a buffer layer 14 is epitaxially grown on the support substrate 12. Examples of epitaxial growth methods include MOCVD (Metal Organic Chemical Vapor Deposition) and MBE (Molecular Beam Epitaxy). This process allows for the formation of the substrate 10.

[0062] Next, a mask layer (not shown) is formed on the buffer layer 14. The mask layer is formed by, for example, electron beam deposition or sputtering.

[0063] Next, using the mask layer as a mask, the first semiconductor layer 32, the light-emitting layer 34, and the second semiconductor layer 36 are epitaxially grown on the buffer layer 14 in that order. Examples of epitaxial growth methods include MOCVD and MBE. This process can form multiple columnar portions 30. In the illustrated example, after forming the multiple columnar portions 30, a portion of the buffer layer 14 may be etched away.

[0064] As shown in Figure 5, a second electrode 62 is formed on the columnar portion 30. Next, a first electrode 60 is formed on the buffer layer 14. The first electrode 60 and the second electrode 62 are formed by, for example, sputtering or vacuum deposition. The order of the steps for forming the first electrode 60 and forming the second electrode 62 is not particularly limited.

[0065] Next, a first layer 46 is formed to cover the buffer layer 14, the first electrode 60, and the second electrode 62. The first layer 46 is formed, for example, by spin coating or CVD (Chemical Vapor Deposition).

[0066] As shown in Figure 6, a conductive layer 50 is formed on the first layer 46. The conductive layer 50 is formed, for example, by sputtering, CVD, or vacuum deposition.

[0067] Next, a second layer 48 is formed to cover the first layer 46 and the conductive layer 50. The second layer 48 is formed, for example, by a spin coating method or a CVD method. The method for forming the second layer 48 may be the same as or different from the method for forming the first layer 46. Through this step, an insulating layer 40 can be formed.

[0068] As shown in Figure 7, the insulating layer 40 is patterned to form a first contact hole 42 that exposes the first electrode 60 and a second contact hole 44 that exposes the second electrode 62. Patterning is performed, for example, by photolithography and etching. Etching may be wet etching or dry etching. In this process, charge may be trapped and accumulate in the insulating layer 40, but in the light-emitting device 100, the conductive layer 50 can reduce the charge accumulated in the insulating layer 40.

[0069] As shown in Figure 1, the second wiring 72 is formed on the second electrode 62. Next, on the first electrode 60 A first wiring 70 is formed on the first wiring 70, and a third wiring 74 is formed on the second wiring 72. The first wiring 70 and the third wiring 74 are formed, for example, in the same process. Wires 70, 72, and 74 are formed, for example, by sputtering, CVD, or vacuum deposition.

[0070] The light-emitting device 100 can be manufactured through the above process.

[0071] 3. Projector Next, the projector according to this embodiment will be described with reference to the drawings. Figure 8 is a schematic diagram showing the projector 700 according to this embodiment.

[0072] The projector 700 has, for example, a light-emitting device 100 as a light source.

[0073] The projector 700 includes a housing (not shown) and red light source 100R, green light source 100G, and blue light source 100B located inside the housing, which emit red light, green light, and blue light, respectively. For convenience, the red light source 100R, green light source 100G, and blue light source 100B are simplified in Figure 8.

[0074] The projector 700 further includes a first optical element 702R, a second optical element 702G, a third optical element 702B, a first optical modulator 704R, a second optical modulator 704G, a third optical modulator 704B, and a projection device 708, all of which are located within the housing. The first optical modulator 704R, the second optical modulator 704G, and the third optical modulator 704B are, for example, transmissive liquid crystal light bulbs. The projection device 708 is, for example, a projection lens.

[0075] Light emitted from the red light source 100R is incident on the first optical element 702R. The light emitted from the red light source 100R is focused by the first optical element 702R. The first optical element 702R may have functions other than focusing. The same applies to the second optical element 702G and the third optical element 702B, which will be described later.

[0076] Light focused by the first optical element 702R is incident on the first optical modulator 704R. The first optical modulator 704R modulates the incident light according to the image information. The projection device 708 then magnifies the image formed by the first optical modulator 704R and projects it onto the screen 710.

[0077] Light emitted from the green light source 100G enters the second optical element 702G. The light emitted from the green light source 100G is focused by the second optical element 702G.

[0078] The light focused by the second optical element 702G is incident on the second optical modulator 704G. The second optical modulator 704G modulates the incident light according to the image information. Then, the projection device 708 magnifies the image formed by the second optical modulator 704G and projects it onto the screen 710.

[0079] Light emitted from the blue light source 100B enters the third optical element 702B. The light emitted from the blue light source 100B is focused by the third optical element 702B.

[0080] The light focused by the third optical element 702B is incident on the third optical modulator 704B. The third optical modulator 704B modulates the incident light according to the image information. Then, the projection device 708 magnifies the image formed by the third optical modulator 704B and projects it onto the screen 710.

[0081] Projector 700 further includes a first optical modulator 704R and a second optical modulator 704G It also has a cross dichroic prism 706 that synthesizes the light emitted from the third light modulator 704B and guides it to the projection device 708.

[0082] Three colored lights modulated by the first light modulator 704R, the second light modulator 704G, and the third light modulator 704B are incident on the cross dichroic prism 706. The cross dichroic prism 706 is formed by bonding together four right-angle prisms, and its inner surface is arranged with a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light. The three colored lights are combined by these dielectric multilayer films to form light that represents a color image. The combined light is then projected onto the screen 710 by the projection device 708, and an enlarged image is displayed.

[0083] Furthermore, the red light source 100R, the green light source 100G, and the blue light source 100B may directly form an image without using the first optical modulator 704R, the second optical modulator 704G, and the third optical modulator 704B by controlling the light-emitting device 100 as pixels of the image according to the image information. The projection device 708 may then enlarge the image formed by the red light source 100R, the green light source 100G, and the blue light source 100B and project it onto the screen 710.

[0084] Furthermore, while a transmissive liquid crystal light bulb was used as the light modulation device in the above example, other types of light bulbs may be used, as well as reflective light bulbs. Examples of such light bulbs include reflective liquid crystal light bulbs and digital micro mirror devices. The configuration of the projection device will also be appropriately modified depending on the type of light bulb used.

[0085] Furthermore, this can also be applied to the light source device of a scanning type image display device, which has a scanning means that displays an image of a desired size on a display surface by scanning the light from the light source across a screen.

[0086] 4. Display Next, the display according to this embodiment will be described with reference to the drawings. Figure 9 is a schematic plan view showing the display 800 according to this embodiment. Figure 10 is a schematic cross-sectional view showing the display 800 according to this embodiment. In Figure 9, the X-axis and Y-axis are shown as two mutually orthogonal axes.

[0087] The display 800 has, for example, a light-emitting device 100 having a plurality of light-emitting units 20 as a light source.

[0088] The display 800 is a display device that displays images. The images include those that display only text information. The display 800 is a self-emissive display. As shown in Figures 9 and 10, the display 800 includes, for example, a circuit board 810, a lens array 820, and a heat sink 830.

[0089] The circuit board 810 is equipped with a drive circuit for driving the light-emitting unit 20. The drive circuit is a circuit that includes, for example, a CMOS (Complementary Metal Oxide Semiconductor). The drive circuit drives the light-emitting unit 20 based on input image information, for example. Although not shown in the figure, a light-transmitting substrate is placed on the circuit board 810 to protect the circuit board 810.

[0090] The circuit board 810 includes, for example, a display area 812, a data line drive circuit 814, a scan line drive circuit 816, and a control circuit 818.

[0091] The display area 812 is composed of multiple pixels P. In the illustrated example, the pixels P are arranged along the X and Y axes. The light-emitting device 100 is located in the display area 812. In other words, multiple light-emitting units 20 are located in the display area 812. For convenience, in Figure 10, only the light-emitting units 20 and the conductive layer 50 of the light-emitting device 100 are shown, and the other components of the light-emitting device 100 are omitted. Also, in Figure 10, the light-emitting units 20 and the conductive layer 50 are shown in a simplified manner.

[0092] Although not shown in the diagram, the circuit board 810 is provided with multiple scan lines and multiple data lines. For example, the scan lines extend along the X-axis, and the data lines extend along the Y-axis. The scan lines are connected to the scan line drive circuit 816. The data lines are connected to the data line drive circuit 814. Pixels P are provided corresponding to the intersections of the scan lines and data lines.

[0093] One pixel P has, for example, one light-emitting device 100, one lens 822, and a pixel circuit (not shown). In other words, one pixel P has, for example, one light-emitting unit 20, one lens 822, and a pixel circuit (not shown). The pixel circuit has a switching transistor that functions as a switch for the pixel P, with the gate of the switching transistor connected to the scan line and either the source or drain connected to the data line.

[0094] The data line drive circuit 814 and the scan line drive circuit 816 are circuits that control the driving of the light-emitting devices 100 that constitute the pixels P. The control circuit 818 controls the display of the image.

[0095] Image data is supplied to the control circuit 818 from the higher-level circuit. The control circuit 818 supplies various signals based on the image data to the data line drive circuit 814 and the scan line drive circuit 816.

[0096] When the scan line drive circuit 816 activates the scan signal and a scan line is selected, the switching transistor of the selected pixel P turns on. At this time, the data line drive circuit 814 supplies a data signal to the selected pixel P from the data line, causing the light-emitting device 100 of the selected pixel P to emit light in accordance with the data signal.

[0097] The lens array 820 has multiple lenses 822. For example, one lens 822 is provided for each light-emitting unit 20. Light emitted from the light-emitting unit 20 enters one lens 822.

[0098] The conductive layer 50 is positioned between adjacent light-emitting sections 20. In a cross-sectional view along a direction perpendicular to the stacking direction, the conductive layer 50 overlaps with the outer edge of the lens 822 in the stacking direction. That is, in a cross-sectional view along a direction perpendicular to the stacking direction, the conductive layer 50 overlaps with both adjacent lenses 822 in the stacking direction. Although not shown in the figures, in a plan view from the stacking direction, the conductive layer 50 overlaps with the outer edge of the lens 822. That is, in a plan view from the stacking direction, the conductive layer 50 overlaps with both adjacent lenses 822. The outer edge of lens 822 is the boundary between adjacent lenses 822.

[0099] The heatsink 830 is in contact with the circuit board 810. The material of the heatsink 830 is, for example, a metal such as copper or aluminum. The heatsink 830 dissipates the heat generated by the light-emitting device 100.

[0100] 5. Head-mounted display 5.1. Overall structure Next, the head-mounted display according to this embodiment will be described with reference to the drawings. Figure 11 is a schematic perspective view showing the head-mounted display 900 according to this embodiment. In Figure 11, the X-axis, Y-axis, and Z-axis are shown as three mutually orthogonal axes.

[0101] The head-mounted display 900, as shown in Figure 11, is a head-mounted display device with the appearance of eyeglasses. The head-mounted display 900 is worn on the observer's head. The observer is the user of the head-mounted display 900. The head-mounted display 900 allows the observer to see a virtual image and also allows them to see the external world through it. The head-mounted display 900 can also be called a virtual image display device.

[0102] The head-mounted display 900 includes, for example, a first display unit 910a, a second display unit 910b, a frame 920, a first temple 930a, and a second temple 930b.

[0103] The first display unit 910a and the second display unit 910b display images. Specifically, the first display unit 910a displays a virtual image for the observer's right eye. The second display unit 910b displays a virtual image for the observer's left eye. In the illustrated example, the first display unit 910a is located in the -X axis direction of the second display unit 910b. The display units 910a and 910b include, for example, an image forming apparatus 911 and a light guide apparatus 915.

[0104] The image forming apparatus 911 forms image light. The image forming apparatus 911 includes, for example, an optical system such as a light source and a projection device, and an external member 912. The external member 912 houses the light source and the projection device.

[0105] The light guide device 915 covers the area in front of the observer's eyes. The light guide device 915 guides the image light formed by the image forming device 911, and also allows the observer to see the external light and the image light overlapping. Details of the image forming device 911 and the light guide device 915 will be described later.

[0106] Frame 920 supports the first display unit 910a and the second display unit 910b. The frame 920 surrounds the display units 910a and 910b, for example, when viewed from the Y-axis direction. In the illustrated example, the image forming apparatus 911 for the first display unit 910a is mounted on the -X-axis end of frame 920. The image forming apparatus 911 for the second display unit 910b is mounted on the +X-axis end of frame 920.

[0107] The first temple 930a and the second temple 930b extend from the frame 920. In the illustrated example, the first temple 930a extends from the -X-axis end of the frame 920 in the +Y-axis direction. The second temple 930b extends from the +X-axis end of the frame 920 in the +Y-axis direction.

[0108] The first temple 930a and the second temple 930b are suspended over the observer's ears when the head-mounted display 900 is worn by the observer. The observer's head is positioned between the temples 930a and 930b.

[0109] 5.2. Image forming apparatus and light guide apparatus Figure 12 is a schematic diagram showing the image forming apparatus 911 and light guide apparatus 915 of the first display unit 910a of the head-mounted display 900 according to this embodiment. Note that the first display unit 910a and the second display unit 910b have basically the same configuration. Therefore, the following The description of the first display unit 910a can be applied to the second display unit 910b.

[0110] As shown in Figure 12, the image forming apparatus 911 includes, for example, a light-emitting device 100 as a light source, a light modulation device 913, and a projection device 914 for image formation.

[0111] The light modulator 913 modulates the light incident from the light emitter 100 according to the image information and emits image light. The light modulator 913 is a transmissive liquid crystal light bulb. The light emitter 100 may be a self-emitting light emitter that emits light according to the input image information. In this case, the light modulator 913 is not provided.

[0112] The projection device 914 projects the image light emitted from the optical modulator 913 toward the light guide device 915. The projection device 914 is, for example, a projection lens. A lens with an axially symmetric plane as its lens surface may be used as the lens component of the projection device 914.

[0113] The light guide device 915 is precisely positioned relative to the projection device 914, for example, by being screwed to the lens barrel of the projection device 914. The light guide device 915 includes, for example, an image light guide member 916 for guiding image light and a transparent member 918 for viewing.

[0114] The image light emitted from the projection device 914 enters the image light guide member 916. The image light guide member 916 is a prism that guides the image light toward the observer's eye. The image light that enters the image light guide member 916 is reflected repeatedly on the inner surface of the image light guide member 916, then reflected by the reflective layer 917 and emitted from the image light guide member 916. The image light emitted from the image light guide member 916 reaches the observer's eye. In the illustrated example, the reflective layer 917 reflects the image light in the +Y axis direction. The reflective layer 917 is made of, for example, a metal or a dielectric multilayer film. The reflective layer 917 may also be a half mirror.

[0115] The transparent member 918 is adjacent to the image light guide member 916. The transparent member 918 is fixed to the image light guide member 916. The outer surface of the transparent member 918 is continuous with, for example, the outer surface of the image light guide member 916. The transparent member 918 allows the observer to see through to the outside light. In addition to its function of guiding image light, the image light guide member 916 also has the function of allowing the observer to see through to the outside light.

[0116] The light-emitting device according to the above embodiment can be used in applications other than projectors, displays, and head-mounted displays. For example, the light-emitting device according to the above embodiment can be used as a light source for indoor and outdoor lighting, laser printers, scanners, in-vehicle lights, light-using sensing equipment, communication equipment, etc.

[0117] The embodiments and variations described above are examples only and are not limited thereto. For example, each embodiment and each variation can be combined as appropriate.

[0118] The present invention includes configurations substantially identical to those described in the embodiments, for example, configurations with the same function, method, and results, or configurations with the same purpose and effect. Furthermore, the present invention includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as those described in the embodiments. Finally, the present invention includes configurations that add known technology to the configurations described in the embodiments.

[0119] The following can be derived from the embodiments and modifications described above.

[0120] One embodiment of a light-emitting device is: A light-emitting section having a first semiconductor layer, a second semiconductor layer with a different conductivity type from the first semiconductor layer, and a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer, An insulating layer covering the light-emitting portion, A conductive layer is provided in the insulating layer, which is electrically isolated from the light-emitting portion and to which a predetermined potential is applied, It holds.

[0121] This light-emitting device can reduce the electric charge accumulated in the insulating layer.

[0122] In one embodiment of the light-emitting device, circuit board and A first electrode is provided on the substrate and electrically connected to the first semiconductor layer, A second electrode is provided on the side of the light-emitting portion opposite to the substrate and is electrically connected to the second semiconductor layer, A wiring provided in the insulating layer and connected to the second electrode, It has, The first semiconductor layer is provided between the substrate and the light-emitting layer. The conductive layer is provided between the substrate and the wiring. The predetermined potential is The potential between the potential applied to the first electrode and the potential applied to the wiring, The same potential as the potential applied to the first electrode, Alternatively, the potential may be the same as the potential applied to the wiring.

[0123] This light-emitting device can reduce parasitic capacitance caused by the substrate, wiring, and insulating layer.

[0124] In one embodiment of the light-emitting device, The light-emitting part has a plurality of columnar parts, Each of the plurality of columnar portions may have the first semiconductor layer, the second semiconductor layer, and the light-emitting layer.

[0125] This light-emitting device can reduce dislocations that occur in the light-emitting layer.

[0126] In one embodiment of the light-emitting device, The distance between the conductive layer and the wiring may be smaller than the distance between the conductive layer and the substrate.

[0127] According to this light-emitting device, noise that enters through the wiring can be blocked by the conductive layer before it reaches deep into the insulating layer.

[0128] In one embodiment of the light-emitting device, In the stacking direction of the first semiconductor layer and the light-emitting layer, the conductive layer may be provided on the side opposite to the substrate from the light-emitting layer.

[0129] With this light-emitting device, noise that enters through the wiring can be blocked by the conductive layer before it reaches the depth of the light-emitting layer.

[0130] In one embodiment of the light-emitting device, Viewed from the stacking direction of the first semiconductor layer and the light-emitting layer, the conductive layer may surround the light-emitting portion.

[0131] According to this light-emitting device, the conductive layer can reduce the electric charge accumulated around the light-emitting part.

[0132] In one embodiment of the light-emitting device, The aforementioned insulating layer is A first layer provided between the substrate and the conductive layer, A second layer is provided between the conductive layer and the wiring, It has, The dielectric constant of the second layer may be smaller than that of the first layer.

[0133] This light-emitting device can reduce parasitic capacitance on the wiring side, which is susceptible to noise intrusion.

[0134] One form of projector is, It has one embodiment of the aforementioned light-emitting device.

[0135] One form of display is, It has one embodiment of the aforementioned light-emitting device.

[0136] One form of head-mounted display is: It has one embodiment of the aforementioned light-emitting device. [Explanation of Symbols]

[0137] 10...Substrate, 12...Support substrate, 14...Buffer layer, 20...Light-emitting part, 30...Columnar part, 32...First semiconductor layer, 34...Light-emitting layer, 36...Second semiconductor layer, 40...Insulating layer, 42...First contact hole, 44...Second contact hole, 46...First layer, 48...Second layer, 50...Conductive layer, 52...First part, 54...Second part, 60...First electrode, 62...Second electrode, 70...First wiring, 72...Second wiring, 74...Third wiring, 100...Light-emitting device, 100R...Red light source, 100G...Green light source, 100B...Blue light source, 700...Projector, 702R...First optical element, 702G...Second optical element, 702B...Third optical element, 704R...First optical modulator, 704G...Second optical modulator, 7 04B…Third optical modulator, 706…Cross dichroic prism, 708…Projection device, 710…Screen, 800…Display, 810…Circuit board, 812…Display area, 814…Data line drive circuit, 816…Scan line drive circuit, 818…Control circuit, 820…Lens array, 822…Lens, 830…Heat sink, 900…Head-mounted display, 910a…First display unit, 910b…Second display unit, 911…Image forming device, 912…External components, 913…Optical modulator, 914…Projection device, 915…Light guide device, 916…Image light guide member, 917…Reflective layer, 918…Transparent member, 920…Frame, 930a…First temple, 930b…Second temple

Claims

1. A light-emitting section having a first semiconductor layer, a second semiconductor layer with a different conductivity type from the first semiconductor layer, and a light-emitting layer provided between the first semiconductor layer and the second semiconductor layer, An insulating layer covering the light-emitting portion, A conductive layer is provided in the insulating layer, which is electrically isolated from the light-emitting portion and to which a predetermined potential is applied, A light-emitting device having the following features.

2. In claim 1, circuit board and A first electrode is provided on the substrate and electrically connected to the first semiconductor layer, A second electrode is provided on the side of the light-emitting portion opposite to the substrate and is electrically connected to the second semiconductor layer, A wiring provided in the insulating layer and connected to the second electrode, It has, The first semiconductor layer is provided between the substrate and the light-emitting layer. The conductive layer is provided between the substrate and the wiring. The predetermined potential is The potential between the potential applied to the first electrode and the potential applied to the wiring, The same potential as the potential applied to the first electrode, Alternatively, a light-emitting device having the same potential as the potential applied to the aforementioned wiring.

3. In claim 2, The light-emitting part has a plurality of columnar parts, A light-emitting device in which each of the plurality of columnar portions has the first semiconductor layer, the second semiconductor layer, and the light-emitting layer.

4. In claim 2, A light-emitting device in which the distance between the conductive layer and the wiring is smaller than the distance between the conductive layer and the substrate.

5. In claim 2, A light-emitting device in which, in the stacking direction of the first semiconductor layer and the light-emitting layer, the conductive layer is provided on the side opposite to the substrate from the light-emitting layer.

6. In claim 2, A light-emitting device in which, viewed from the stacking direction of the first semiconductor layer and the light-emitting layer, the conductive layer surrounds the light-emitting portion.

7. In claim 2, The insulating layer is A first layer provided between the substrate and the conductive layer, A second layer is provided between the conductive layer and the wiring, It has, A light-emitting device wherein the dielectric constant of the second layer is smaller than that of the first layer.

8. A projector having a light-emitting device according to any one of claims 1 to 7.

9. A display having a light-emitting device according to any one of claims 1 to 7.

10. A head-mounted display having a light-emitting device according to any one of claims 1 to 7.

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