JP2023129868A - Light-emitting device, projector, display, and head-mounted display - Google Patents

Abstract

To provide a light-emitting device that can reduce a stress generated in a second semiconductor layer due to the difference in coefficient of thermal expansion between the second semiconductor and a conductive layer.SOLUTION: A light-emitting device has: a substrate; columnar parts that each have a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type different from the first conductivity type, and a luminous layer provided between the first semiconductor layer and the second semiconductor layer; and an electrode that is provided on the opposite side of the columnar parts with respect to the substrate, and includes a conductive layer including metal and an organic conductive layer including organic material and provided between the columnar parts and the conductive layer. The coefficient of thermal expansion of the conductive layer is different from the coefficient of thermal expansion of the second semiconductor layer. The Young's modulus of the organic conductive layer is smaller than the Young's modulus of the second semiconductor layer and the Young's modulus of the conductive layer.SELECTED DRAWING: Figure 2

Description

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

Semiconductor lasers are expected to be the next generation of high-intensity light sources. Among these, semiconductor lasers using nanocolumns are expected to be able to emit high-output light with a narrow radiation angle due to the photonic crystal effect of the nanocolumns.

For example, Patent Document 1 describes a nanocolumn in which an n-type GaN layer, a light-emitting layer, and a p-type GaN layer are sequentially laminated, and a p-type nanocolumn made of Ni/Au that can make ohmic contact with the p-type GaN layer at the tip of the nanocolumn. A semiconductor light emitting device is described that includes an electrode.

Japanese Patent Application Publication No. 2010-135858

In the semiconductor light emitting device as described above, the thermal expansion coefficient of the p-type electrode is different from that of the p-type GaN layer. Therefore, for example, when a semiconductor light emitting device is heated, stress is generated in the p-type GaN layer due to the difference in thermal expansion coefficient between the p-type electrode and the p-type GaN layer.

One embodiment of the light emitting device according to the present invention is
A substrate and
A columnar shape having a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type different from the first conductivity type, and a light emitting layer provided between the first semiconductor layer and the second semiconductor layer. Department and
an electrode provided on the opposite side of the columnar part from the substrate and including a conductive layer containing metal; and an organic conductive layer containing an organic material and provided between the columnar part and the conductive layer;
has
The thermal expansion coefficient of the conductive layer is different from the thermal expansion coefficient of the second semiconductor layer,
The Young's modulus of the organic conductive layer is smaller than the Young's modulus of the second semiconductor layer and the Young's modulus of the conductive layer.

One aspect of the projector according to the present invention is
This embodiment has one embodiment of the light-emitting device.

One aspect of the display according to the present invention is
This embodiment has one embodiment of the light-emitting device.

One aspect of the head mounted display according to the present invention is
This embodiment has one embodiment of the light-emitting device.

FIG. 1 is a cross-sectional view schematically showing a light emitting device according to the present embodiment. FIG. 1 is a cross-sectional view schematically showing a light emitting device according to the present embodiment. FIG. 2 is a cross-sectional view schematically showing the manufacturing process of the light emitting device according to the present embodiment. FIG. 2 is a cross-sectional view schematically showing the manufacturing process of the light emitting device according to the present embodiment. FIG. 3 is a cross-sectional view schematically showing a light emitting device according to a first modified example of the present embodiment. FIG. 7 is a cross-sectional view schematically showing a light emitting device according to a second modified example of the present embodiment. FIG. 7 is a cross-sectional view schematically showing a light emitting device according to a third modification of the present embodiment. FIG. 7 is a cross-sectional view schematically showing a light emitting device according to a third modification of the present embodiment. FIG. 7 is a cross-sectional view schematically showing a light emitting device according to a fourth modification of the present embodiment. FIG. 1 is a diagram schematically showing a projector according to the present embodiment. FIG. 1 is a plan view schematically showing a display according to the present embodiment. FIG. 1 is a cross-sectional view schematically showing a display according to the present embodiment. FIG. 1 is a perspective view schematically showing a head mounted display according to the present embodiment. FIG. 1 is a diagram schematically showing an image forming device and a light guide device of a head mounted display according to the present embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail using the drawings. Note that the embodiments described below do not unduly limit the content of the present invention described in the claims. Furthermore, not all of the configurations described below are essential components of the present invention.

1. Light emitting device 1.1. Overall Configuration First, a light emitting device according to this embodiment will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a light emitting device 100 according to this embodiment.

As shown in FIG. 1, the light emitting device 100 includes, for example, a substrate 10, a laminate 20, a first electrode 50, and a second electrode 52. The light emitting device 100 is, for example, a semiconductor laser.

The substrate 10 is, for example, a Si substrate, a GaN substrate, a sapphire substrate, a SiC substrate, or the like.

The laminate 20 is provided on the substrate 10. In the illustrated example, the laminate 20 is provided on the substrate 10. The laminate 20 includes, for example, a buffer layer 22, a columnar portion 30, and an insulating layer 40.

In this specification, in the stacking direction of the stacked body 20 (hereinafter also simply referred to as "stacking direction"), when the light emitting layer 34 of the columnar section 30 is used as a reference, the second semiconductor of the columnar section 30 is transferred from the light emitting layer 34. The direction toward the layer 36 will be referred to as "up", and the direction from the light emitting layer 34 toward the first semiconductor layer 32 of the columnar section 30 will be referred to as "down". Further, the direction perpendicular to the stacking direction is also referred to as the "in-plane direction." “The stacking direction of the stacked body 20” refers to the stacking direction of the first semiconductor layer 32 and the light emitting layer 34.

Buffer layer 22 is provided on substrate 10 . The buffer layer 22 is, for example, a semiconductor layer, and is an n-type GaN layer doped with Si. Although not shown, a mask layer for growing the columnar portions 30 may be provided on the buffer layer 22. The mask layer is, for example, a titanium layer, a silicon oxide layer, a titanium oxide layer, an aluminum oxide layer, or the like.

The columnar portion 30 is provided on the buffer layer 22. The columnar portion 30 is provided on the substrate 10 with the buffer layer 22 interposed therebetween. The columnar portion 30 has a columnar shape that projects upward from the buffer layer 22 . In other words, the columnar portions 30 protrude upward from the substrate 10 with the buffer layer 22 interposed therebetween. The columnar part 30 is also called, for example, a nanocolumn, a nanowire, a nanorod, or a nanopillar. The planar shape of the columnar portion 30 is, for example, a polygon such as a regular hexagon, or a circle.

The diameter of the columnar portion 30 is, for example, 50 nm or more and 500 nm or less. 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. Thereby, the light generated in the light emitting layer 34 can be amplified with high efficiency.

In addition, the "diameter of the columnar part 30" is the diameter when the planar shape of the columnar part 30 is a circle, and when the planar shape of the columnar part 30 is a shape other than a circle, it is the diameter of the minimum enclosing circle. . For example, when the planar shape of the columnar portion 30 is a polygon, the diameter of the columnar portion 30 is the diameter of the smallest circle that includes the polygon, and when the planar shape of the columnar portion 30 is an ellipse, the diameter of the ellipse is the diameter of the smallest circle that includes the polygon. It is the diameter of the smallest circle contained inside.

A plurality of columnar parts 30 are provided. The plurality of columnar parts 30 are spaced apart from each other. In the illustrated example, there is a gap between adjacent columnar parts 30. The interval between adjacent columnar parts 30 is, for example, 1 nm or more and 500 nm or less. The plurality of columnar parts 30 are arranged in a predetermined direction at a predetermined pitch when viewed from the stacking direction. The plurality of columnar parts 30 are arranged in, for example, a regular triangular lattice shape or a square lattice shape. The plurality of columnar parts 30 can exhibit the effect of a photonic crystal.

Note that the "pitch of the columnar sections 30" is the distance between the centers of the columnar sections 30 adjacent to each other in a predetermined direction. "The center of the columnar section 30" means the center of the circle when the planar shape of the columnar section 30 is a circle, and the center of the minimum enclosing circle when the planar shape of the columnar section 30 is not a circle. be. For example, if the planar shape of the columnar portion 30 is a polygon, the center of the columnar portion 30 is the center of the smallest circle that includes the polygon, and if the planar shape of the columnar portion 30 is an ellipse, the center of the ellipse is the center of the smallest circle that includes the polygon. It is the center of the smallest circle contained inside.

The columnar portion 30 includes a first semiconductor layer 32, a light emitting layer 34, and a second semiconductor layer 36. The first semiconductor layer 32, the light emitting layer 34, and the second semiconductor layer 36 are, for example, group III nitride semiconductors and have a wurtzite crystal structure.

The first semiconductor layer 32 is provided on the buffer layer 22. The first semiconductor layer 32 is provided between the substrate 10 and the light emitting layer 34. The first semiconductor layer 32 is a first conductivity type semiconductor layer. The first conductivity type is, for example, n-type. The first semiconductor layer 32 is, for example, an n-type GaN layer doped with Si. In other words, the first semiconductor layer 32 protrudes upward from the buffer layer 22.

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 current is injected thereto. The light emitting layer 34 includes, for example, a well layer and a barrier layer. The well layer and 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 a well layer and a barrier layer.

Note that the number of well layers and barrier layers that constitute the light emitting layer 34 is not particularly limited. For example, only one well layer may be provided, and in this case, the light emitting layer 34 has an SQW (Single Quantum Well) structure.

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 52. 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 p-type GaN layer doped with Mg. 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.

Although not shown, an OCL (OCL) consisting of an i-type InGaN layer and a GaN layer is 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. Optical Confinement Layer) may be provided. Further, the second semiconductor layer 36 may include an EBL (Electron Blocking Layer) made of a p-type AlGaN layer.

In the light emitting device 100, a pin diode is configured by the p-type second semiconductor layer 36, the i-type light emitting layer 34 not intentionally doped with impurities, and the n-type first semiconductor layer 32. In the light emitting device 100, when a forward bias voltage of a pin diode is applied between the first electrode 50 and the second electrode 52, a current is injected into the light emitting layer 34, and electrons and holes are recombined in the light emitting layer 34. happens. This recombination produces light emission. The light generated in the light emitting layer 34 propagates in the in-plane direction, forms a standing wave due to the photonic crystal effect of the plurality of columnar parts 30, receives gain in the light emitting layer 34, and oscillates as a laser. Then, the light emitting device 100 emits the +1st-order diffracted light and the -1st-order diffracted light as laser beams in the stacking direction.

Although not shown, a reflective layer may be provided between the substrate 10 and the buffer layer 22 or under the substrate 10. The reflective layer is, for example, a DBR (Distributed Bragg Reflector) layer. The reflective layer can reflect the light generated in the light emitting layer 34, and the light emitting device 100 can emit light only from the second electrode 52 side.

The insulating layer 40 is provided, for example, on the buffer layer 22, and on the organic conductive layer 54 and metal layer 56 of the second electrode 52. The insulating layer 40 surrounds the plurality of columnar parts 30 when viewed from the stacking direction. A contact hole 42 is provided in the insulating layer 40 . The contact hole 42 penetrates the insulating layer 40 in the stacking direction. The insulating layer 40 is, for example, a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, a polyimide layer, or the like.

The first electrode 50 is provided on the buffer layer 22. In the illustrated example, a portion of the buffer layer 22 is dug, and the first electrode 50 is provided in the dug portion of the buffer layer 22. The buffer layer 22 may be in ohmic contact with the first electrode 50. The first electrode 50 is electrically connected to the first semiconductor layer 32. In the illustrated example, the first electrode 50 is electrically connected to the first semiconductor layer 32 via the buffer layer 22. As the first electrode 50, for example, a layer formed by laminating a Cr layer, a Ni layer, and an Au layer in this order from the buffer layer 22 side is used. The first electrode 50 is one electrode for injecting current into the light emitting layer 34.

The second electrode 52 is provided on the second semiconductor layer 36. The second electrode 52 is the other electrode for injecting current into the light emitting layer 34. Details of the second electrode 52 will be described later.

Note that although the InGaN-based light emitting layer 34 has been described above, the light emitting layer 34 may be made of various materials that can emit light when a current is injected, depending on the wavelength of the emitted light. can. For example, semiconductor materials such as AlGaN-based, AlGaAs-based, InGaAs-based, InGaAsP-based, InP-based, GaP-based, and AlGaP-based can be used.

Further, the light emitting device 100 is not limited to a laser, and may be an LED (Light Emitting Diode).

1.2. Second Electrode FIG. 2 is a cross-sectional view schematically showing the light emitting device 100 according to this embodiment, and is an enlarged view of region A in FIG.

The second electrode 52 is provided on the opposite side of the columnar section 30 from the substrate 10, as shown in FIGS. 1 and 2. The second electrode 52 includes, for example, an organic conductive layer 54, a metal layer 56, and a transparent electrode layer 58.

The organic conductive layer 54 is provided on the second semiconductor layer 36. The organic conductive layer 54 is provided between the second semiconductor layer 36 and the metal layer 56. The organic conductive layer 54 is provided over the plurality of columnar parts 30. The organic conductive layer 54 is provided above the gap between the adjacent columnar parts 30. In the illustrated example, the upper surface of the columnar portion 30 is configured with a facet surface, and the organic conductive layer 54 is provided on the facet surface. Although not shown, the upper surface of the columnar portion 30 may have a c-plane, and the organic conductive layer 54 may be provided on the c-plane.

The organic conductive layer 54 is not provided on the side surface 37 of the second semiconductor layer 36 of the columnar section 30 . Therefore, compared to, for example, a case where an organic conductive layer is provided on the side surface, the average refractive index in the in-plane direction at the exposed side surface 37 of the laminate 20 and the light emitting layer 34 of the laminate 20 are reduced. It is possible to increase the difference between the average refractive index in the in-plane direction in the portion where the Thereby, the optical confinement coefficient of the light emitting device 100 can be increased. The side surface 37 is formed of, for example, an m-plane. In the illustrated example, the side surface 37 is parallel to the stacking direction.

The thickness T1 of the organic conductive layer 54 is, for example, larger than the thickness T2 of the metal layer 56. The thickness T1 of the organic conductive layer 54 is the maximum size of the organic conductive layer 54 in the stacking direction. The thickness T2 of the metal layer 56 is the maximum size of the metal layer 56 in the stacking direction. The thickness T1 of the organic conductive layer 54 may be larger than, smaller than, or the same as the thickness of the transparent electrode layer 58.

The thickness T1 of the organic conductive layer 54 is, for example, 5 nm or more and 30 nm or less. If the thickness T1 is 5 nm or more, the stress generated in the second semiconductor layer 36 due to the difference in coefficient of thermal expansion between the second semiconductor layer 36 and the metal layer 56 can be more reliably reduced. If the thickness T1 is 30 nm or less, the electrical resistance of the second electrode 52 can be lowered.

The Young's modulus of the organic conductive layer 54 is smaller than the Young's modulus of the second semiconductor layer 36. The Young's modulus of the organic conductive layer 54 is smaller than that of the metal layer 56. The Young's modulus of the organic conductive layer 54 is smaller than that of the transparent electrode layer 58, for example. Young's modulus is measured, for example, by a resonance method, an ultrasonic pulse method, or the like.

For example, the difference between the work function of the organic conductive layer 54 and the work function of the second semiconductor layer 36 is smaller than the difference between the work function of the metal layer 56 and the work function of the second semiconductor layer 36. The work function of the organic conductive layer 54 is, for example, smaller than the work function of the second semiconductor layer 36. The work function of the metal layer 56 is, for example, smaller than the work function of the organic conductive layer 54. The work function of the transparent electrode layer 58 is smaller than that of the metal layer 56, for example. The electrical resistivity of the organic conductive layer 54 is smaller than that of the transparent electrode layer 58, for example.

Organic conductive layer 54 includes an organic material. The organic conductive layer 54 is made of, for example, an organic material. The material of the organic conductive layer 54 is a conductive polymer. The organic conductive layer 54 includes, for example, PEDOT (poly(3,4-ethylenedioxythiophene)). Further, the organic conductive layer 54 contains, for example, PSS (polystyrene sulfonic acid) as a dopant. The organic conductive layer 54 is formed by, for example, dispersing PEDOT and PSS as a dopant in water or an organic solvent to prepare a PEDOT/PSS liquid, and applying and heating the prepared PEDOT/PSS liquid. This is the PSS layer.

A metal layer 56 is provided on the organic conductive layer 54. A metal layer 56 is provided between the organic conductive layer 54 and the transparent electrode layer 58. Metal layer 56 defines the bottom surface of contact hole 42 . Seen from the stacking direction, the area of the metal layer 56 is smaller than the area of the organic conductive layer 54, for example.

The thickness T2 of the metal layer 56 is smaller than the thickness of the transparent electrode layer 58. The electrical resistivity of the metal layer 56 is, for example, smaller than the electrical resistivity of the organic conductive layer 54 and the electrical resistivity of the transparent electrode layer 58. The coefficient of thermal expansion of the metal layer 56 is different from the coefficient of thermal expansion of the second semiconductor layer 36. The thermal expansion coefficient of the metal layer 56 is larger than that of the second semiconductor layer 36.

The metal layer 56 is a conductive layer containing metal. The metal layer 56 is made of an inorganic material. Specifically, the metal layer 56 is made of metal. The metal layer 56 is, for example, a Pd layer, a Pt layer, a Ni layer, and an Au layer stacked in this order.

A transparent electrode layer 58 is provided on the metal layer 56. Furthermore, the transparent electrode layer 58 is provided on the side surface of the insulating layer 40 that defines the contact hole 42 and on the top surface of the insulating layer 40 .

The transparent electrode layer 58 has higher translucency than the metal layer 56 with respect to the light generated in the light emitting layer 34 . The transparent electrode layer 58 is made of an inorganic material. Specifically, the transparent electrode layer 58 is made of a transparent electrode material. The transparent electrode layer 58 is, for example, an ITO (Indium Tin Oxide) layer, a ZnO layer, or the like.

1.3. Effects The light emitting device 100 includes a metal layer 56 as a conductive layer containing metal, and an organic conductive layer 54 containing an organic material and provided between the columnar portion 30 and the metal layer 56. The thermal expansion coefficient of the metal layer 56 is different from that of the second semiconductor layer 36, and the Young's modulus of the organic conductive layer 54 is smaller than the Young's modulus of the second semiconductor layer 36 and the Young's modulus of the metal layer 56.

Therefore, in the light emitting device 100, even if the light emitting device 100 is heated, for example, the stress generated in the second semiconductor layer 36 due to the difference in thermal expansion coefficients between the second semiconductor layer 36 and the metal layer 56 can be absorbed by the organic The conductive layer 54 can reduce the size. For example, when the second semiconductor layer 36 expands by the first dimension when viewed from the stacking direction due to heating of the light emitting device 100, the portion of the organic conductive layer 54 on the second semiconductor layer 36 side is expanded by the second semiconductor layer 36. 36 can be expanded by a first dimension. Further, for example, when the metal layer 56 expands by a second dimension larger than the first dimension, the portion of the organic conductive layer 54 on the metal layer 56 side expands by the second dimension as the metal layer 56 expands. I can do it. In this way, the organic conductive layer 54 has a function of buffering the difference in thermal expansion coefficient between the second semiconductor layer 36 and the metal layer 56. The same thing can be said not only in the case of thermal expansion but also in the case of thermal contraction. This can reduce the possibility that defects such as crystal defects will occur in the second semiconductor layer 36. As a result, an increase in contact resistance and a leak path between the second semiconductor layer 36 and the second electrode 52 can be suppressed, and good light-emitting characteristics can be obtained. Furthermore, for example, the possibility that cracks will occur in the metal layer 56 due to the difference in thermal expansion coefficients between the second semiconductor layer 36 and the metal layer 56 can be reduced.

In the light emitting device 100, the thickness T1 of the organic conductive layer 54 is greater than the thickness T2 of the metal layer 56. Therefore, in the light emitting device 100, compared to the case where the thickness T1 is smaller than the thickness T2, for example, generation of heat in the second semiconductor layer 36 due to the difference in coefficient of thermal expansion between the second semiconductor layer 36 and the metal layer 56 occurs. The stress caused by this can be more reliably reduced.

In the light emitting device 100, the organic conductive layer 54 is a PEDOT/PSS layer. The PEDOT/PSS layer is formed, for example, by a wet process such as a spin coating method or an inkjet method. Therefore, compared to the case where no organic conductive layer is formed and a metal layer is directly formed on the second semiconductor layer by sputtering or vapor deposition, the amount of damage to the second semiconductor layer 36 caused by forming the second electrode 52 increases. Damage can be reduced. The damage includes crystal defects. Crystal defects cause carrier loss.

In the light emitting device 100, the second electrode 52 has a transparent electrode layer 58, and the metal layer 56 is provided between the organic conductive layer 54 and the transparent electrode layer 58. Therefore, in the light emitting device 100, the transmittance of the second electrode 52 for light generated in the light emitting layer 34 can be made higher than in the case where a layer made of metal is provided instead of the transparent electrode layer.

2. Method for Manufacturing Light-Emitting Device Next, a method for manufacturing the light-emitting device 100 according to the present embodiment will be described with reference to the drawings. 3 and 4 are cross-sectional views schematically showing the manufacturing process of the light emitting device 100 according to this embodiment.

As shown in FIG. 3, a buffer layer 22 is epitaxially grown on the substrate 10. Examples of epitaxial growth methods include MOCVD (Metal Organic Chemical Vapor Deposition) and MBE (Molecular Beam Epitaxy).

Next, a mask layer (not shown) is formed on the buffer layer 22. The mask layer is formed by, for example, an electron beam evaporation method or a sputtering method.

Next, the first semiconductor layer 32, the light emitting layer 34, and the second semiconductor layer 36 are epitaxially grown in this order on the buffer layer 22 using the mask layer as a mask. Examples of epitaxial growth methods include MOCVD, MBE, and the like. Through this step, a plurality of columnar parts 30 can be formed. Note that after forming the plurality of columnar portions 30, a portion of the buffer layer 22 may be etched.

As shown in FIG. 4, an organic conductive layer 54 is formed on the plurality of columnar parts 30. The organic conductive layer 54 is formed by, for example, applying a PEDOT/PSS liquid by a spin coating method or an inkjet method, and heating and baking the applied PEDOT/PSS liquid. Note that the organic conductive layer 54 may be formed by a vacuum evaporation method.

Next, a metal layer 56 is formed on the organic conductive layer 54. The metal layer 56 is formed by, for example, a sputtering method or a vacuum evaporation method.

Next, an insulating layer 40 is formed to cover the buffer layer 22, the organic conductive layer 54, and the metal layer 56. The insulating layer 40 is formed, for example, by applying a precursor liquid using a spin coating method and heating and baking the applied precursor liquid. The organic conductive layer 54 can reduce the stress generated in the second semiconductor layer 36 due to the difference in thermal expansion coefficient between the second semiconductor layer 36 and the metal layer 56 when the precursor liquid is heated. Note that the insulating layer 40 may be formed by a CVD (Chemical Vapor Deposition) method.

As shown in FIG. 1, the insulating layer 40 is patterned to form a contact hole 42 in the insulating layer 40. As shown in FIG. Patterning is performed, for example, by photolithography and etching. Although not shown, a portion of the metal layer 56 may be etched by over-etching during patterning.

Next, a transparent electrode layer 58 is formed on the metal layer 56 and the insulating layer 40. The transparent electrode layer 58 is formed by, for example, a sputtering method, a vacuum evaporation method, or the like. Through this step, the second electrode 52 having the organic conductive layer 54, the metal layer 56, and the transparent electrode layer 58 can be formed.

Next, a first electrode 50 is formed on the buffer layer 22. The first electrode 50 is formed by, for example, a sputtering method, a vacuum evaporation method, or the like. Note that the order of the step of forming the first electrode 50 and the step of forming the transparent electrode layer 58 is not particularly limited.

Through the above steps, the light emitting device 100 can be manufactured.

3. Modifications of light emitting device 3.1. First Modification Next, a light emitting device according to a first modification of the present embodiment will be described with reference to the drawings. FIG. 5 is a cross-sectional view schematically showing a light emitting device 200 according to a first modification of the present embodiment.

Hereinafter, in the light emitting device 200 according to the first modification of the present embodiment, members having the same functions as the constituent members of the light emitting device 100 according to the present embodiment described above will be denoted by the same reference numerals, and detailed description thereof will be given. omitted. This also applies to light emitting devices according to second to fourth modified examples of the present embodiment, which will be described later.

In the light emitting device 100 described above, as shown in FIG. 2, the organic conductive layer 54 was not provided on the side surface 37 of the second semiconductor layer 36 of the columnar section 30.

On the other hand, in the light emitting device 200, as shown in FIG. 5, the organic conductive layer 54 is provided on the side surface 37 of the second semiconductor layer 36 of the columnar section 30. The organic conductive layer 54 is provided between adjacent columnar parts 30. For example, the organic conductive layer 54 can be formed on the side surface 37 of the second semiconductor layer 36 of the columnar part 30 by adjusting the interval between adjacent columnar parts 30 or by adjusting the film formation conditions of the organic conductive layer 54. can. The organic conductive layer 54 is not provided on the side surface of the light emitting layer 34 of the columnar section 30. The organic conductive layer 54 is not provided on the side surface of the first semiconductor layer 32 of the columnar section 30.

In the light emitting device 200, the organic conductive layer 54 is further provided on the side surface 37 of the second semiconductor layer 36 of the columnar section 30. Therefore, in the light emitting device 200, the contact area between the organic conductive layer 54 and the second semiconductor layer 36 can be increased compared to a case where an organic conductive layer is not provided on the side surface of the second semiconductor layer of the columnar part. . Thereby, the contact resistance between the organic conductive layer 54 and the second semiconductor layer 36 can be lowered.

3.2. Second Modification Next, a light emitting device according to a second modification of the present embodiment will be described with reference to the drawings. FIG. 6 is a cross-sectional view schematically showing a light emitting device 300 according to a second modification of the present embodiment.

In the light emitting device 100 described above, the laminate 20 had a plurality of columnar parts 30, as shown in FIG.

On the other hand, in the light emitting device 300, the stacked body 20 has only one columnar part 30, as shown in FIG. Light emitting device 300 is an LED. The first semiconductor layer 32 has a film shape, for example. The light emitting layer 34 is, for example, in the form of a film. The second semiconductor layer 36 has a film shape, for example.

3.3. Third Modification Next, a light emitting device according to a third modification of the present embodiment will be described with reference to the drawings. FIG. 7 is a cross-sectional view schematically showing a light emitting device 400 according to a third modification of the present embodiment.

As shown in FIG. 7, the light emitting device 400 differs from the light emitting device 100 described above in that it includes a wall member 60.

The wall member 60 is provided on the columnar part 30. The thickness of wall member 60 is greater than the thickness of organic conductive layer 54. The thickness of the wall member 60 is the maximum size of the wall member 60 in the stacking direction. In the illustrated example, the thickness of wall member 60 is greater than the sum of the thickness of organic conductive layer 54 and the thickness of metal layer 56.

The wall member 60 surrounds the organic conductive layer 54 when viewed from the stacking direction. The planar shape of the wall member 60 is, for example, a ring shape. The wall member 60 is in contact with the side surface of the organic conductive layer 54. In the illustrated example, the wall member 60 is spaced apart from the side surface of the metal layer 56. Note that the wall member 60 may be in contact with the side surface of the metal layer 56, as shown in FIG. The material of the wall member 60 is, for example, an organic material such as acrylic resin, or an inorganic material such as silicon oxide.

The wall member 60 is formed on the columnar section 30 after the columnar section 30 is formed and before the organic conductive layer 54 is formed. The wall member 60 is formed by, for example, a CVD method, a spin coating method, or the like.

After forming the wall member 60, a PEDOT/PSS liquid that will become the organic conductive layer 54 is applied to the inside of the wall member 60 when viewed from the stacking direction. The PEDOT/PSS liquid is applied by, for example, an inkjet method. The wall member 60 can suppress leakage of the PEDOT/PSS liquid to the outside of the wall member 60 when viewed from the stacking direction. Thereby, the organic conductive layer 54 can be formed at a desired position. Furthermore, the organic conductive layer 54 can be formed with high uniformity in thickness.

3.4. Fourth Modification Next, a light emitting device according to a fourth modification of the present embodiment will be described with reference to the drawings. FIG. 9 is a cross-sectional view schematically showing a light emitting device 500 according to a fourth modification of the present embodiment.

In the light emitting device 100 described above, the metal layer 56 was provided as shown in FIG.

In contrast, in the light emitting device 500, as shown in FIG. 9, the metal layer 56 is not provided. In the illustrated example, the transparent electrode layer 58 is provided on the organic conductive layer 54. The transparent electrode layer 58 is a conductive layer containing metal.

4. Projector Next, a projector according to the present embodiment will be described with reference to the drawings. FIG. 10 is a diagram schematically showing a projector 700 according to this embodiment.

The projector 700 includes, for example, a light emitting device 100 as a light source.

The projector 700 includes a casing (not shown), and a red light source 100R, a green light source 100G, and a blue light source 100B that are provided inside the casing and emit red, green, and blue light, respectively. Note that, for convenience, the red light source 100R, green light source 100G, and blue light source 100B are simplified in FIG.

The projector 700 further includes a first optical element 702R, a second optical element 702G, a third optical element 702B, a first light modulation device 704R, and a second light modulation device 704G, which are provided inside the housing. It has a third light modulation device 704B and a projection device 708. The first light modulator 704R, the second light modulator 704G, and the third light modulator 704B are, for example, transmissive liquid crystal light valves. Projection device 708 is, for example, a projection lens.

The light emitted from the red light source 100R enters the first optical element 702R. The light emitted from the red light source 100R is focused by the first optical element 702R. Note that the first optical element 702R may have a function other than focusing. The same applies to a second optical element 702G and a third optical element 702B, which will be described later.

The light focused by the first optical element 702R enters the first light modulation device 704R. The first light modulator 704R modulates the incident light according to image information. Then, the projection device 708 magnifies the image formed by the first light modulation device 704R and projects it onto the screen 710.

The light emitted from the green light source 100G enters the second optical element 702G. The light emitted from the green light source 100G is collected by the second optical element 702G.

The light focused by the second optical element 702G enters the second light modulation device 704G. The second light modulation device 704G modulates the incident light according to image information. Then, the projection device 708 magnifies the image formed by the second light modulation device 704G and projects it onto the screen 710.

The 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.

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

The projector 700 further includes a cross dichroic prism 706 that combines the light emitted from the first light modulation device 704R, the second light modulation device 704G, and the third light modulation device 704B and guides it to the projection device 708. .

The three colored lights modulated by the first light modulator 704R, the second light modulator 704G, and the third light modulator 704B enter the cross dichroic prism 706. The cross dichroic prism 706 is formed by bonding four right-angled prisms together, and has a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light arranged on its inner surface. These dielectric multilayer films combine three colored lights to form light representing a color image. The combined light is then projected onto a screen 710 by a projection device 708, and an enlarged image is displayed.

Note that the red light source 100R, the green light source 100G, and the blue light source 100B are controlled according to image information using the light emitting device 100 as a pixel of an image, thereby controlling the first light modulation device 704R, the second light modulation device 704G, and the second light modulation device 704G. An image may be directly formed without using the three-light modulator 704B. Then, the projection device 708 may enlarge and project the image formed by the red light source 100R, the green light source 100G, and the blue light source 100B onto the screen 710.

Further, in the above example, a transmissive liquid crystal light valve is used as the light modulation device, but a light valve other than liquid crystal may be used, or a reflective light valve may be used. Examples of such light valves include reflective liquid crystal light valves and digital micro mirror devices. Further, the configuration of the projection device is changed as appropriate depending on the type of light valve used.

Further, a light source device of a scanning type image display device having a scanning means, which is an image forming device that displays an image of a desired size on a display surface by scanning the light from the light source on a screen. It can also be applied to

5. Display Next, the display according to the present embodiment will be described with reference to the drawings. FIG. 11 is a plan view schematically showing a display 800 according to this embodiment. FIG. 12 is a cross-sectional view schematically showing a display 800 according to this embodiment. Note that in FIG. 11, the X axis and the Y axis are illustrated as two axes that are orthogonal to each other.

The display 800 includes, for example, a light emitting device 100 as a light source.

Display 800 is a display device that displays images. Images include those that display only text information. Display 800 is a self-luminous display. The display 800 includes, for example, a circuit board 810, a lens array 820, and a heat sink 830, as shown in FIGS. 11 and 12.

A drive circuit for driving the light emitting device 100 is mounted on the circuit board 810. The drive circuit is, for example, a circuit including a CMOS (Complementary Metal Oxide Semiconductor). The drive circuit drives the light emitting device 100 based on input image information, for example. Although not shown, a light-transmitting substrate for protecting the circuit board 810 is arranged on the circuit board 810.

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

The display area 812 is composed of a plurality of pixels P. In the illustrated example, the pixels P are arranged along the X axis and the Y axis.

Although not shown, the circuit board 810 is provided with a plurality of scanning lines and a plurality of data lines. For example, scan lines run along the X-axis and data lines run along the Y-axis. The scan lines are connected to a scan line drive circuit 816. The data line is connected to a data line drive circuit 814. Pixels P are provided corresponding to intersections of scanning lines and data lines.

One pixel P includes, for example, one light emitting device 100, 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, the gate of the switching transistor is connected to the scanning line, and one of the source or drain is connected to the data line.

The data line drive circuit 814 and the scanning line drive circuit 816 are circuits that control driving of the light emitting device 100 that constitutes the pixel P. Control circuit 818 controls the display of images.

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

When a scanning line is selected by the scanning line drive circuit 816 activating a scanning signal, the switching transistor of the selected pixel P is turned on. At this time, the data line drive circuit 814 supplies the selected pixel P with a data signal from the data line, so that the light emitting device 100 of the selected pixel P emits light in accordance with the data signal.

Lens array 820 has a plurality of lenses 822. For example, one lens 822 is provided for one light emitting device 100. Light emitted from the light emitting device 100 enters one lens 822.

Heat sink 830 is in contact with circuit board 810. The material of the heat sink 830 is, for example, metal such as copper or aluminum. The heat sink 830 radiates heat generated by the light emitting device 100.

6. Head-mounted display 6.1. Overall Configuration Next, a head-mounted display according to the present embodiment will be described with reference to the drawings. FIG. 13 is a perspective view schematically showing a head mounted display 900 according to this embodiment. Note that in FIG. 13, the X-axis, Y-axis, and Z-axis are illustrated as three axes that are orthogonal to each other.

The head-mounted display 900, as shown in FIG. 13, is a head-mounted display device that looks like glasses. Head-mounted display 900 is mounted on the viewer's head. An observer is a user who uses head-mounted display 900. The head-mounted display 900 allows the viewer to view image light from a virtual image, and also allows the viewer to view an external image in a see-through manner. Head mounted display 900 can also be called a virtual image display device.

The head mounted display 900 includes, for example, a first display section 910a, a second display section 910b, a frame 920, a first temple 930a, and a second temple 930b.

The first display section 910a and the second display section 910b display images. Specifically, the first display section 910a displays a virtual image for the observer's right eye. The second display section 910b displays a virtual image for the observer's left eye. In the illustrated example, the first display section 910a is provided in the -X axis direction of the second display section 910b. Display portions 910a and 910b include, for example, an image forming device 911 and a light guide device 915.

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

The light guiding 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 allows the observer to see the external world light and the image light in an overlapping manner. Note that details of the image forming device 911 and the light guiding device 915 will be described later.

The frame 920 supports a first display section 910a and a second display section 910b. For example, the frame 920 surrounds the display sections 910a and 910b when viewed from the Y-axis direction. In the illustrated example, the image forming device 911 of the first display section 910a is attached to the end of the frame 920 in the −X-axis direction. The image forming device 911 of the second display section 910b is attached to the end of the frame 920 in the +X-axis direction.

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

The first temple 930a and the second temple 930b are suspended from the viewer's ears when the head mounted display 900 is worn by the viewer. The observer's head is located between temples 930a and 930b.

6.2. Image Forming Device and Light Guide Device FIG. 14 is a diagram schematically showing an image forming device 911 and a light guide device 915 of the first display section 910a of the head mounted display 900 according to the present embodiment. Note that the first display section 910a and the second display section 910b have basically the same configuration. Therefore, the following description of the first display section 910a can be applied to the second display section 910b.

As shown in FIG. 14, the image forming device 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.

The light modulation device 913 modulates the light incident from the light emitting device 100 according to image information, and emits image light. The light modulator 913 is a transmissive liquid crystal light valve. Note that the light emitting device 100 may be a self-luminous type light emitting device that emits light according to input image information. In this case, the light modulation device 913 is not provided.

Projection device 914 projects the image light emitted from light modulation device 913 toward light guide device 915 . The projection device 914 is, for example, a projection lens. As the lens constituting the projection device 914, a lens whose lens surface is an axially symmetrical surface may be used.

The light guide device 915 is precisely positioned with respect to the projection device 914 by being screwed to the lens barrel of the projection device 914, for example. The light guide device 915 includes, for example, an image light guide member 916 that guides image light, and a see-through member 918 for see-through.

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 viewer's eyes. The image light that has entered the image light guide member 916 is repeatedly reflected on the inner surface of the image light guide member 916, is reflected by the reflective layer 917, and is emitted from the image light guide member 916. The image light emitted from the image light guide member 916 reaches the observer's eyes. 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, metal or a dielectric multilayer film. The reflective layer 917 may be a half mirror.

Transparent member 918 is adjacent to 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 the outer surface of the image light guide member 916, for example. The transparent member 918 allows the observer to see through the external light. Note that the image light guide member 916 also has a function of allowing the observer to see through external light in addition to the function of guiding the image light.

The light emitting device according to the embodiments described above can be used for things other than projectors, displays, and head-mounted displays. The light emitting device according to the embodiment described above is used, for example, as a light source for indoor and outdoor lighting, laser printers, scanners, vehicle lights, sensing devices that use light, communication devices, and the like.

The above-described embodiments and modifications are merely examples, and the present invention is not limited thereto. For example, it is also possible to combine each embodiment and each modification as appropriate.

The present invention includes a configuration that is substantially the same as the configuration described in the embodiment, for example, a configuration that has the same function, method, and result, or a configuration that has the same purpose and effect. Further, the present invention includes a configuration in which non-essential parts of the configuration described in the embodiments are replaced. Further, the present invention includes a configuration that has the same effects or a configuration that can achieve the same objective as the configuration described in the embodiment. Further, the present invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

The following content is derived from the above-described embodiment and modification.

One aspect of the light emitting device is
A substrate and
A columnar shape having a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type different from the first conductivity type, and a light emitting layer provided between the first semiconductor layer and the second semiconductor layer. Department and
an electrode provided on the opposite side of the columnar part from the substrate and including a conductive layer containing metal; and an organic conductive layer containing an organic material and provided between the columnar part and the conductive layer;
has
The thermal expansion coefficient of the conductive layer is different from the thermal expansion coefficient of the second semiconductor layer,
The Young's modulus of the organic conductive layer is smaller than the Young's modulus of the second semiconductor layer and the Young's modulus of the conductive layer.

According to such a light emitting device, stress generated in the second semiconductor layer due to the difference in thermal expansion coefficient between the second semiconductor layer and the conductive layer can be reduced.

In one embodiment of the light emitting device,
The organic conductive layer may further be provided on a side surface of the second semiconductor layer of the columnar portion.

According to such a light emitting device, the contact resistance between the organic conductive layer and the second semiconductor layer can be reduced.

In one embodiment of the light emitting device,
The thickness of the organic conductive layer may be greater than the thickness of the conductive layer.

According to such a light emitting device, the stress generated in the second semiconductor layer due to the difference in thermal expansion coefficient between the second semiconductor layer and the conductive layer can be more reliably reduced.

In one embodiment of the light emitting device,
The organic conductive layer may be a PEDOT/PSS layer.

According to such a light emitting device, damage to the second semiconductor layer caused by forming the electrode can be reduced.

In one embodiment of the light emitting device,
The conductive layer is a metal layer,
The electrode has a transparent electrode layer,
The metal layer may be provided between the organic conductive layer and the transparent electrode layer.

According to such a light emitting device, the transmittance of the electrode to light generated in the light emitting layer can be increased.

One aspect of the projector is
This embodiment has one embodiment of the light-emitting device.

One aspect of the display is
This embodiment has one embodiment of the light-emitting device.

One aspect of the head-mounted display is
This embodiment has one embodiment of the light-emitting device.

DESCRIPTION OF SYMBOLS 10... Substrate, 20... Laminated body, 22... Buffer layer, 30... Columnar part, 32... First semiconductor layer, 34... Light emitting layer, 36... Second semiconductor layer, 37... Side surface, 40... Insulating layer, 42... Contact Hole, 50... First electrode, 52... Second electrode, 54... Organic conductive layer, 56... Metal layer, 58... Transparent electrode layer, 60... Wall member, 100, 200, 300, 400, 500... Light emitting device, 700 ...Projector, 702R...First optical element, 702G...Second optical element, 702B...Third optical element, 704R...First light modulator, 704G...Second light modulator, 704B...Third light modulator, 706... Cross dichroic prism, 708... Projection device, 710... Screen, 800... Display, 810... Circuit board, 812... Display area, 814... Data line drive circuit, 816... Scanning line drive circuit, 818... Control circuit, 820... Lens array , 822... Lens, 830... Heat sink, 900... Head mounted display, 910a... First display section, 910b... Second display section, 911... Image forming device, 912... External member, 913... Light modulation device, 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 (8)

A substrate and
A columnar shape having a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type different from the first conductivity type, and a light emitting layer provided between the first semiconductor layer and the second semiconductor layer. Department and
an electrode provided on the opposite side of the columnar part from the substrate and including a conductive layer containing metal; and an organic conductive layer containing an organic material and provided between the columnar part and the conductive layer;
has
The thermal expansion coefficient of the conductive layer is different from the thermal expansion coefficient of the second semiconductor layer,
The light emitting device, wherein the Young's modulus of the organic conductive layer is smaller than the Young's modulus of the second semiconductor layer and the Young's modulus of the conductive layer. In claim 1,
In the light emitting device, the organic conductive layer is further provided on a side surface of the second semiconductor layer of the columnar portion. In claim 1 or 2,
The light emitting device, wherein the thickness of the organic conductive layer is greater than the thickness of the conductive layer. In any one of claims 1 to 3,
The light emitting device, wherein the organic conductive layer is a PEDOT/PSS layer. In any one of claims 1 to 4,
The conductive layer is a metal layer,
The electrode has a transparent electrode layer,
The light emitting device, wherein the metal layer is provided between the organic conductive layer and the transparent electrode layer. A projector comprising the light emitting device according to claim 1. A display comprising the light emitting device according to any one of claims 1 to 5. A head mounted display comprising the light emitting device according to any one of claims 1 to 5.

Images