JP2014075486A - Light emitting element and stereoscopic image display apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting element including a structure specifying an emission direction of light, and having a variable emission direction.SOLUTION: A light emitting element 1 includes: a light emitting structure part 2 having a semiconductor laminate in which a p-type semiconductor layer 21 comprising an InGaAlN semiconductor, a light emitting layer 22, and an n-type semiconductor layer 23 are laminated in the order; and an emission direction specification part 3 having a structure 3a for specifying the direction of light emitted from the light emitting structure part 2, on the upper face of the n-type semiconductor layer 23. Lower electrodes 41a, 41b and upper electrodes 44a, 44b are provided via lower insulating layers 42a, 42b and upper insulating layers 43a, 43b on the upper face and the lower face of the light emitting structure part 2, respectively, at the end parts of the light emitting structure part 2 in a plane view, and, by applying voltage between the lower electrodes 41a, 41b and the upper electrodes 44a, 44b, the light emitting structure part 2 is deformed to tilt the emission direction specification part 3, and thereby the emission direction is changed.

Description

  The present invention relates to a light-directional light emitting element and a stereoscopic image display device using the light emitting element.

  Conventionally, holography, parallax stereogram, lenticular sheet, integral photography (hereinafter referred to as IP) and the like are known as representative methods of image reproduction type stereoscopic display. Regarding the practical application of these methods, excluding holography, it is thought that it can be realized at an early stage with a simple method that does not require coherent light. Moreover, since IP can express parallax information in the vertical direction in addition to the horizontal direction, it is considered promising for early realization of a device capable of natural stereoscopic display (see, for example, Non-Patent Document 1). .

  The IP display system includes a lens array in which a large number of minute lenses (element lenses) that reproduce light rays are arranged, and a display that displays a large number of images (element images) corresponding to each lens. The observer can observe only one pixel in one element image corresponding to one element lens, and the number of light rays produced by one pixel in each element image is collected by the number of element lenses. Observe the reconstructed image at the viewpoint. Then, the observer observes the stereoscopic image from the reproduced image corresponding to the viewpoint position of the observer. In the IP display system, the resolution of the stereoscopic image is determined by the resolution of the element lens, the resolution of the element image, and the viewing distance. Further, regarding the viewing zone angle of the IP display system, the performance of the element lens is a dominant factor. Under such circumstances, in order to generate a practical stereoscopic image by the IP method, it is indispensable to increase the definition and function of the light emitting element and the optical element (for example, see Non-Patent Document 2).

  However, even as the resolution of light emitting elements and optical elements increases, optical systems that use lenses have performance limitations that cannot be removed in principle, such as lens diffraction limits, focal lengths, and aberrations. To do. For example, if the pixel size of the display is smaller than the minimum spot size of the element lens, image blurring occurs, so it is necessary to reduce the spot size at the same time, but in principle it is necessary to make the spot size smaller than the Abbe diffraction limit. Impossible.

  The viewing zone angle in a system using a lens is inversely proportional to the focal length of the element lens, but the focal length of the element lens cannot be made infinitely small in order to increase the viewing zone angle. Furthermore, since the viewing zone angle is proportional to the pitch of the element lens, if the pitch of the element lens is increased, the viewing zone angle can be enlarged, but the resolution deteriorates. There is a trade-off relationship between viewing zone angles.

  On the other hand, in the field of light-emitting elements, LEDs (Light Emitting Diodes), which are self-light-emitting elements, have attracted attention in various applications since their light-emitting characteristics have advanced dramatically in recent years. LED is a promising device for display applications because it has a high degree of light emission characteristics such as high color purity, as the light diffusivity is so strong that it needs a mechanism for diffusing light in applications such as lighting fixtures. Conceivable.

In addition, the inventors of the present application separately formed a structure having a plurality of fine columnar structures or holes (holes) on the surface of the LED, thereby emitting light only in a specific direction (light rays). An IP-type three-dimensional display in which LEDs having such structures on the surface are arrayed is proposed (for example, Japanese Patent Application No. 2011-182138).
The feature of this IP system stereoscopic display is that both horizontal and vertical parallax display is possible without using coherent light. For this reason, realization as a three-dimensional display capable of displaying a natural three-dimensional image with little eye strain and without the need for wearing glasses is desired.

Now consider the number of pixels required for an IP 3D display. For example, when an IP-type stereoscopic display in which 60 images are superimposed in the horizontal and vertical directions on an image equivalent to a high-definition image is produced by a minute LED having a light beam directivity in which a columnar structure or a hole is formed, the pixels necessary for the display The number is [1920 lens equivalent number (horizontal) × 60 image number] × [1080 lens equivalent number (vertical) × 60 image number] = 7.47 × 10 ⁹ pixels. This number of pixels is 226 times the number of pixels of Super Hi-Vision (having the maximum number of pixels) that is currently realized in a two-dimensional flat panel display (FPD: flat panel display). It is difficult to manufacture an FPD having such a large number of pixels with the current manufacturing process technology.

On the other hand, an apparatus for displaying an image on a screen by scanning LED light or laser light has been put into practical use. Examples of devices that have been put to practical use to date include LED displays mounted on mobile phones as small projectors and laser displays with a wide color reproduction range.
Further, a method using an EO (Electro-Optic) effect has been proposed as an element for scanning LED light or laser light. The EO effect is a phenomenon in which the refractive index of a substance changes with an applied electric field, and high-speed response up to the microwave region can be realized. The method using the EO effect is attracting attention because it can improve the element size and the operation speed, which are problems in the movable mirror (polygon mirror or galvano mirror) method, by one or more digits. .

For example, Patent Document 1 includes an optical element using a KTN crystal (a solid solution of KTaO ₃ and KNbO ₃ ) as an EO crystal having an EO effect, and a refractive index gradient changes according to a voltage applied to the EO crystal. A scanning device that scans laser light using the EO effect is described.
Therefore, as a technique for facilitating the production of the display having the enormous number of pixels described above, the light emitting element has light scanning property (variability in the light emitting direction) by combining the light-directional LED and the EO crystal. Therefore, it is conceivable to reduce the number of light-emitting elements mounted on the FPD.

Japanese Patent No. 4356636

“Ultra-high-definition video technology / stereoscopic video technology”, Journal of the Institute of Electronics, Information and Communication Engineers, May 2010, Vol. 93, no. 5, p. 372-381 Association for Promotion of Mechanical Systems and Optoelectronics Technology Promotion Association, “Survey Report on Formation of Spatial Image that Enables Natural Stereoscopic Vision—Summary”, Research Survey on System Technology Development 19-R-5, 2008 March, p. 14-16

However, in the case of an LN (LiNbO ₃ : lithium niobate) crystal that is most widely used for light modulation, an EO crystal needs to be applied with a high voltage of several kV, for example, with a standard crystal thickness of 2 mm. is there.
The KTN crystal described in Patent Document 1 has a performance index 20 times that of an LN crystal, but it is still necessary to apply a voltage of 120 V with a crystal thickness of 2 mm. In addition, these crystals have only a function of scanning light and are configured separately from the light source (LED or laser light emitting element), which poses a serious problem in terms of device structure and cost. This combination is possible in principle, and scanning of only a single pixel is possible, but the structure in which a large number of them are arranged is the alignment of LED and EO crystal, the point of their arrangement configuration, EO crystal Is difficult because it is necessary to operate at a high voltage.

  In view of the above, an object of the present invention is to provide a light-emitting element that has a variable light emission direction, can be driven at a low voltage, and can be downsized. Another object is to provide a stereoscopic image display device in which the number of light-emitting elements is reduced without reducing the resolution.

In order to solve the above-described problem, a light-emitting element according to claim 1 of the present invention includes a semiconductor stacked body in which a first semiconductor layer, a light-emitting layer, and a second semiconductor layer are stacked in this order. A light emitting device having a light emitting structure, wherein the light emitted from the light emitting layer is specified on a part of the second semiconductor layer or on the upper surface of the second semiconductor layer. An emission direction specifying portion having a structure is provided, and at the ends of the upper surface and the lower surface of the light emitting structure portion in plan view, a lower electrode and an upper electrode are provided so that at least a part thereof is opposed to each other through an insulating layer. It was configured as follows.
The first semiconductor layer and the second semiconductor layer are semiconductor layers having different conductivity types, and when the first semiconductor layer is an n-type semiconductor layer, the second semiconductor layer is a p-type semiconductor layer, When the first semiconductor layer is a p-type semiconductor layer, the second semiconductor layer is an n-type semiconductor layer.

  According to this configuration, the light emitting element emits light by the light emitting structure and emits light emitted by the light emitting structure by the emission direction specifying unit in a specific direction. At this time, the light emitting element generates an electric field inside the light emitting structure which is a stacked body of semiconductors by applying a voltage between the lower electrode and the upper electrode, and the light emitting structure is generated by an inverse piezoelectric effect due to the electric field. Deform. This deformation is, for example, a strain that expands or contracts or compresses the light emitting structure between the lower electrode and the upper electrode. At this time, when the bottom surface of the light emitting structure portion is fixed to the substrate, the upper surface of the light emitting structure portion is inclined with respect to the substrate surface. For this reason, the structure of the emission direction specifying part provided on the upper surface side of the light emitting structure part is also inclined. Then, the light emission direction changes by the amount the structure is inclined.

The light emitting device according to claim 2, in light emitting device according to claim 1, the laminate of the semiconductor has the general formula _{In 1-x-y Ga x} Al y N ( where, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1).
According to such a configuration, the light-emitting structure portion of the light-emitting element functions as a good semiconductor light-emitting element that emits light in the visible light region, and the semiconductor layer has a hexagonal crystal structure, thereby obtaining a large inverse piezoelectric effect. It functions as a piezoelectric element.

A light-emitting device according to a third aspect is the light-emitting device according to the second aspect, wherein the light-emitting layer has a quantum well structure. Here, the quantum well structure is, for example, a structure in which a barrier layer made of GaN and a well layer made of InN are stacked.
According to such a configuration, the luminance and color purity of the light emitting element are increased, and the inverse piezoelectric effect is enhanced due to lattice mismatch in the quantum well structure. For this reason, the light emitting layer can be deformed with a low applied voltage.

  The light-emitting element according to claim 4 is the light-emitting element according to any one of claims 1 to 3, wherein the structure emits light from the emission surface of the stigma (N is 3 or more). The N columnar portions are annularly arranged in a range in which light emitted from the light emitting layer can interfere in a plan view, and at least of the N columnar portions. The height of one pillar was different from the height of the other pillars.

  According to this configuration, light from the light emitting layer is incident on the structure and is emitted from the stigma which is the emission surface of the plurality of columnar portions. Since the light emitted from these emission surfaces has low coherence based on the properties of the light emitting element, the light emitted from the plurality of columnar portions interferes with each other and is combined to form a light beam. Further, the light emitting element is configured such that the height of at least one of the plurality of columnar portions is different from the height of the other columnar portions, thereby providing a phase difference in the light emitted from each emission surface, A light beam is emitted in a direction corresponding to the phase difference. That is, the light emitting element emits a light beam in a specific direction corresponding to a preset height difference of the columnar part.

  The light-emitting element according to claim 5 is the light-emitting element according to any one of claims 1 to 3, wherein the structure has N columns (N is an integer of 3 or more) recessed in a columnar shape from the upper surface. The N columnar recesses are provided in a ring shape within a range in which light emitted from the light emitting layer can interfere in a plan view, and at least one of the N columnar recesses is provided. The depth of the columnar recess was configured to be different from the depth of the other columnar recess.

  According to such a configuration, light from the light emitting layer enters the structure and is emitted from the bottom surface, which is the emission surface of the plurality of columnar recesses. Since the light emitted from these emission surfaces has low coherence based on the properties of the light emitting element, the light emitted from the plurality of columnar portions interferes with each other and is combined to form a light beam. Further, the light emitting element is configured such that the depth of at least one of the plurality of columnar recesses is different from the depth of the other columnar recesses, thereby providing a phase difference in the light emitted from each emission surface, A light beam is emitted in a direction corresponding to the phase difference. That is, the light emitting element emits a light beam in a specific direction corresponding to a preset difference in the depth of the columnar recess.

  A stereoscopic image display apparatus according to a sixth aspect includes a display panel in which the light-emitting elements according to any one of the first to fifth aspects are arranged as a pixel in a two-dimensional array on a substrate. The integral photography stereoscopic image display apparatus includes a light emission control unit and an emission direction control unit.

  According to such a configuration, the stereoscopic image display device outputs, by time-division, image signals corresponding to two or more emission directions to each pixel by the light emission control unit, and outputs the light signals and non-light emission of the pixels. And control. In addition, the stereoscopic image display device specifies the emission direction of the light beam from each pixel by using the interference of light by using, for example, an emission direction specifying unit including a plurality of columnar portions and a plurality of columnar concave portions. At this time, in the stereoscopic image display apparatus, the emission direction control unit emits light provided as each pixel in synchronization with the timing at which the light emission control unit switches the image signal output to each pixel corresponding to two or more emission directions. Modulates the emission direction of the element. Accordingly, the stereoscopic image display device displays an integral photography stereoscopic image.

According to the first aspect of the present invention, since the emission direction is modulated with a simple configuration in which a voltage is applied between the electrodes provided on the upper and lower sides of the light emitting structure, the light emitting element that can modulate the emission direction. Can be miniaturized.
According to the second aspect of the present invention, since the InGaAlN-based semiconductor material is used as a light emitting element and a piezoelectric element, light emission and emission direction modulation can be performed at a low voltage.
According to the invention described in claim 3, since a large inverse piezoelectric effect can be used, the modulation degree in the emission direction can be improved. In addition, the applied voltage for obtaining a certain degree of modulation in the emission direction can be reduced.

According to the invention described in claim 4 or claim 5, it is possible to specify the light emitting direction by utilizing interference of light in a structure having a simple configuration in which a plurality of columnar portions or a plurality of columnar concave portions are provided. Therefore, miniaturization and high density of the light emitting element can be facilitated.
According to the invention described in claim 6, since the direction of the light beam from each pixel is specified by the emission direction specifying unit using the interference of light, the definition is higher than that of a stereoscopic image display device using a lens. can do. In addition, since one light emitting element functions as a pixel corresponding to a plurality of emission directions, the number of light emitting elements mounted on the stereoscopic image display device can be reduced.

It is a typical perspective view which shows the structure of the light emitting element which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the structure of the light emitting element which concerns on 1st Embodiment of this invention, (a) is a top view, (b) shows sectional drawing. It is a figure for demonstrating the reverse piezoelectric effect of the gallium nitride crystal used by this invention, (a) shows the case where a compressive strain arises, (b) shows the case where a tensile strain arises. It is typical sectional drawing for demonstrating the area | region where light is radiated | emitted outside from the light emission structure part in this invention. It is a typical top view for demonstrating arrangement | positioning of the columnar part of the light emitting element which concerns on 1st Embodiment of this invention. It is a typical top view for demonstrating the relationship between arrangement | positioning of the columnar part of the light emitting element which concerns on 1st Embodiment of this invention, and a light emission area | region. It is typical sectional drawing for demonstrating the principle which pinpoints the output direction by the light emitting element which concerns on 1st Embodiment of this invention. FIG. 4 is a schematic cross-sectional view for explaining the principle of changing the emission direction in the light-emitting element according to the first embodiment of the present invention, where (a) shows a case where the upper surface of the light-emitting structure part is parallel to the substrate surface; (C) shows the case where the upper surface of the light emitting structure is inclined in different directions with respect to the substrate surface. It is a schematic diagram for demonstrating a part of process in the manufacturing method of the light emitting element which concerns on 1st Embodiment of this invention, (a)-(h) is typical sectional drawing in each process. It is a schematic diagram for demonstrating a part of process in the manufacturing method of the light emitting element which concerns on 1st Embodiment of this invention, (a)-(f) is typical sectional drawing in each process. It is a schematic diagram for demonstrating a part of process in the manufacturing method of the light emitting element which concerns on 1st Embodiment of this invention, (a)-(f) is typical sectional drawing in each process. It is a typical perspective view which shows the structure of the light emitting element which concerns on 2nd Embodiment of this invention. It is a typical perspective view which shows the structure of the light emitting element which concerns on 3rd Embodiment of this invention. It is a schematic diagram which shows the structure of the light emitting element which concerns on 3rd Embodiment of this invention, (a) is a top view, (b) shows sectional drawing. It is a conceptual diagram of the IP stereoscopic display which concerns on 4th Embodiment of this invention, (a) is a front view, (b) is a perspective view. It is a block diagram which shows the structure of the IP stereoscopic display which concerns on 4th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the size and positional relationship of members and the like shown in the drawings may be exaggerated for clarity of explanation.

<First Embodiment>
[Outline of light emitting device structure]
First, the structure of the light emitting device 1 according to the first embodiment will be described with reference to FIGS. 1 and 2. In FIG. 2 (b), the part below the break line shows a cross section taken along the line AA in FIG. 2 (a), and the part above the break line shows a cross section taken along the line BB in FIG. 2 (a). Indicates.

The light-emitting element 1 according to the present embodiment is an element that emits light with high directivity, and is a light-directional light-emitting element that emits light in a specific direction. In addition, the light emitting element 1 modulates the direction of emitting light using the inverse piezoelectric effect (inverse piezo effect) of the semiconductor layer constituting the light emitting structure 2.
As shown in FIGS. 1 and 2, the light emitting device 1 according to the present embodiment includes a light emitting structure 2 that emits light and an emission direction specifying unit that emits light emitted from the light emitting structure 2 in a specific direction. 3 is laminated.

  The light emitting structure 2 is a stacked body of semiconductor crystals having an LED structure, and emits light when power is supplied through the p-side electrode 24 and the n-side electrode 25. Further, on the lower surface side of the light emitting structure portion 2, a lower electrode 41 a and a lower electrode 41 b are provided at both ends in the X-axis direction (left end and right end in FIG. 2A) via a lower insulating layer 42 a and a lower insulating layer 42 b, respectively. The upper electrode 44a and the upper electrode 44b are provided on the upper surface side through the upper insulating layer 43a and the upper insulating layer 43b, respectively, at both ends in the Y-axis direction (upper and lower ends in FIG. 2A). . By applying an appropriate voltage between the lower electrodes 41a and 41b and the upper electrodes 44a and 44b, the semiconductor crystal of the light emitting structure 2 is distorted by the inverse piezoelectric effect, and the emission direction specifying unit 3 is placed. The upper surface of the light emitting structure 2 is inclined. Then, the light emission direction is modulated (changed) by this inclination. The relationship between the inclination of the upper surface of the light emitting structure 2 due to the inverse piezoelectric effect and the modulation of the light emission direction will be described later.

  In the light emitting structure 2, a p-type semiconductor layer (first semiconductor layer) 21, a light emitting layer 22, and an n-type semiconductor layer (second semiconductor layer) 23 are stacked in this order. A p-side electrode (first electrode) 24 that is electrically connected and an n-side electrode (second electrode) 25 that is electrically connected to the n-type semiconductor layer 23 are provided. The light emitting structure 2 applies a voltage pulse of a predetermined level between the p-side electrode 24 that is an anode and the n-side electrode 25 that is a cathode, so that holes are injected into the p-type semiconductor layer 21 and the n-type electrode. The LED element emits light when electrons are injected into the semiconductor layer 23 and holes and electrons are recombined in the light emitting layer 22. The p-side electrode 24 is provided so as to be in contact with a central portion that is a part on the lower surface side of the p-type semiconductor layer 21, and is provided so that the contact surface with the p-type semiconductor layer 21 has a circular shape. The n-side electrode 25 is provided so as to be in contact with a part of the upper surface of the n-type semiconductor layer 23.

  In the present embodiment, the mobility of electrons that are carriers (carrier mobility) in the n-type semiconductor layer 23 is sufficiently larger than the mobility of carriers that are carriers in the p-type semiconductor layer 21 (carrier mobility). In addition, the recombination time of carriers in the light emitting layer 22 is configured using a semiconductor material that is sufficiently shorter than the diffusion time of carriers. For this reason, in the light emitting layer 22, when electrons and holes recombine and emit light and disappear, electrons with high mobility are quickly replenished. On the other hand, when holes with low mobility are replenished, the holes and the previously replenished electrons are immediately recombined, and light is emitted and disappears. For this reason, the light emitting layer 22 is directly above the contact surface between the p-side electrode 24 and the p-type semiconductor layer 21, and carrier recombination frequently occurs in the light emitting region 22 a having substantially the same planar shape as the contact surface. Emits light.

The p-type semiconductor layer (first semiconductor layer) 21 is a transport layer that transports holes that are carriers injected from the p-side electrode 24, and is a p-side electrode that contacts the center of the lower surface in a circular shape in plan view 24 is provided.
The n-type semiconductor layer (second semiconductor layer) 23 is a transport layer that transports electrons that are carriers injected from the n-side electrode 25, and is provided with the n-side electrode 25 in contact with part of the upper surface. In addition, an emission direction specifying unit 3 is provided on the upper surface of the n-type semiconductor layer 23, and guides light emitted from the light emitting region 22 a of the light emitting layer 22 to the emission direction specifying unit 3. The semiconductor material is selected such that the carrier mobility in the n-type semiconductor layer 23 is larger than the carrier mobility in the p-type semiconductor layer 21.
Each of the p-type semiconductor layer 21 and the n-type semiconductor layer 23 can have a single layer structure, but can also have a multilayer structure.

  The light-emitting layer 22 is provided between the p-type semiconductor layer 21 and the n-type semiconductor layer 23, and transports holes that are carriers transported via the p-type semiconductor layer 21 and the n-type semiconductor layer 23. This layer emits light by recombination with electrons as carriers. The light emitting layer 22 is formed in the region immediately above the contact surface between the p-side electrode 24 and the p-type semiconductor layer 21 and in the vicinity thereof depending on the relationship between the carrier mobility and the recombination time in the p-type semiconductor layer 21 and the n-type semiconductor layer 23. A certain light emitting area 22a emits light, and other areas do not emit light.

  Further, the light emitting structure 2 which is a stacked body of semiconductor crystals is provided between the lower electrodes 41a and 41b provided at the left and right ends of the lower surface and the upper electrodes 44a and 44b provided at the front and rear ends of the upper surface. Due to the electric field generated by the applied voltage, the semiconductor crystal expands and contracts in the vertical direction by the inverse piezoelectric effect. In the present embodiment, for example, as shown in FIG. 8, the light emitting structure portion with respect to the upper surface of the substrate 40 (surface parallel to the XY plane) is changed by changing the thickness difference between the left and right ends of the semiconductor crystal that expands and contracts in the vertical direction. 2 is changed. Then, the emission direction of the light beam is modulated by inclining the emission direction specifying unit 3 provided on the upper surface of the light emitting structure unit 2. The principle of modulating the light emission direction will be described later.

Thus, a GaN (gallium nitride) based compound semiconductor can be used as a semiconductor material that functions as an LED element and a piezoelectric element. Further, as the semiconductor material, the general formula _{In 1-x-y Ga x} Al y N ( where, 0 ≦ x ≦ 1,0 ≦ y ≦ 1,0 ≦ x + y ≦ 1) GaN ( gallium nitride) represented by A solid solution of InN (indium nitride) or AlN (aluminum nitride) can also be used.
In particular, since AlN has a large strain of the base material itself, a large inverse piezoelectric effect can be obtained by using an AlGaN-based semiconductor material that is a solid solution with GaN.
In addition, by adjusting the composition (x, y) in the chemical formula, light having almost all wavelengths of visible light can be emitted, which is preferable as a semiconductor material of a light-emitting element for image display.

Here, the inverse piezoelectric effect will be described with reference to FIG.
Here, a GaN crystal will be described as an example. A GaN-based semiconductor crystal is a crystal having a hexagonal crystal structure and growing in the c-axis direction of the crystal. In the light emitting element 1, the semiconductor crystal is provided so that the c-axis is parallel to the Z-axis.

Here, the GaN crystal generates a polarization electric field due to its strong ionicity. Furthermore, when an electric field is applied to the GaN crystal, it expands and contracts in the vertical direction (Z-axis direction) due to crystal deformation (tensile strain or compression strain) in a horizontal manner (direction parallel to the XY plane). In an LED manufactured by epitaxially growing GaN on a substrate such as sapphire having a C-plane as a main surface by MOCVD (metal organic chemical vapor deposition), a crystal film whose interface with the substrate is a Ga polar plane grows.
In this case, as shown in FIG. 3A, when an electric field Ez is applied in the −Z-axis direction (the [000-1] direction of the GaN crystal), in-plane compressive strain is generated and the film is pulled in the c-axis direction. The GaN crystal expands due to the stress. The relationship between the direction of the electric field Ez and the expansion and contraction in the c-axis direction can be reversed. That is, as shown in FIG. 3B, by setting the direction of the electric field Ez to the + Z-axis direction (the [0001] direction of the GaN crystal), in-plane tensile strain occurs, and compressive stress acts in the c-axis direction. Thus, the GaN crystal is compressed.

  The cause of the expansion and contraction of the GaN crystal due to the inverse piezoelectric effect is considered to be that the crystal structure of GaN is a hexagonal crystal structure with low symmetry, and the crystal structure does not include central symmetry. When pressure is applied to a crystal having such a low symmetry and a crystal structure that does not have central symmetry, polarization occurs due to the pressure, and a charge is generated on the crystal surface. An electric field is generated (piezoelectric effect). The magnitude of the stretching strain is proportional to the magnitude of this polarization. A similar effect is also present in sapphire used as a growth substrate for GaN. The inverse piezoelectric effect is an effect having a relation between the piezoelectric effect and the front and back. That is, the inverse piezoelectric effect is an effect in which a strain proportional to the electric field is generated when an electric field is applied to a crystal having no central symmetry.

In addition, such a large polarization strain is enhanced in a semiconductor layer made of a GaN crystal, particularly in an LED having an InN quantum well, and exhibits a large inverse piezoelectric effect at a low voltage of about 2 to 10V. The lattice constant in the horizontal direction (a-axis) of the GaN crystal is 0.3189 nm, and the lattice constant in the same direction of the InN crystal is 0.3548 nm. Therefore, there is 11% lattice mismatch between the two. Due to this lattice mismatch, the in-plane compressive strain is further increased, and when an electric field Ez is applied in the Z-axis direction, the expansion and contraction of GaN in the c-axis direction (Z-axis direction) by the electric field Ez is further enhanced.
In the case of an LED using GaN, the electric field strength at the heterojunction portion between GaN and InN reaches 10 ⁸ V / m, although it varies depending on the solid solution ratio of InN. Since electrons and holes are separated by this electric field, the luminous efficiency of the LED is reduced, but a large reverse piezoelectric effect can be used.

Therefore, the light emitting layer 22 is preferably hetero-grown with a quantum well made of InN. By utilizing the effect described above, the crystal can be expanded and contracted at a low voltage of about 2 to 10 V or less.
In addition, since the lattice constant of AlGaN in the a-axis direction is smaller than that of GaN, a large reverse piezoelectric effect can be obtained even by configuring the semiconductor layer to have a junction structure of AlGaN and GaN. preferable.

Returning to FIGS. 1 and 2, the description of the configuration of the light-emitting element 1 will be continued.
The light emitting region 22 a is a region located immediately above and in the vicinity of the contact surface of the light emitting layer 22 between the p-side electrode 24 and the p-type semiconductor layer 21. As described above, the light emitting region 22 a is a region that selectively emits light in the light emitting layer 22 due to the relationship between carrier mobility and recombination time in the p-type semiconductor layer 21 and the n-type semiconductor layer 23.

The p-side electrode (first electrode) 24 is a positive electrode provided directly below the structure 3 a and on the lower surface of the p-type semiconductor layer 21 to inject carriers into the p-type semiconductor layer 21. The p-side electrode 24 has a cylindrical shape, and is provided so that the circular upper surface is in contact with a part of the lower surface of the p-type semiconductor layer 21. The p-side electrode 24 is made of a conductive compound such as metal or ITO (indium tin oxide). The p-side electrode 24 may have a multilayer structure in which a plurality of types of conductive materials are stacked.
Note that the shape of the p-side electrode 24 is not limited to a cylindrical shape, and may be an arbitrary shape such as a prismatic shape, a needle shape, a spherical shape, or a hemispherical shape. In addition, the shape of the contact surface with the p-type semiconductor layer 21 is not limited to a circular shape, and may be an ellipse or a polygon. The shape and size of the contact surface depends on the structure of the structure 3a. Can be determined.

  The n-side electrode (second electrode) 25 is a negative electrode that is provided on a part of the upper surface of the n-type semiconductor layer 23 and injects carriers into the n-type semiconductor layer 23. The n-side electrode 25 only needs to be provided so as to be in contact with a part of the n-type semiconductor layer 23, and is not limited to a part of the upper surface. The n-side electrode 25 is provided on a side surface or a region where the structure 3a is provided in plan view. You may provide in the outer edge part of an upper surface except. In any case, it is preferable to provide the structure 3a on the upper surface of the n-type semiconductor layer 23 so as not to become an obstacle. The n-side electrode 25 can be configured using a metal or a conductive compound, similarly to the above-described p-side electrode.

  Here, with reference to FIG. 4, a description will be given of how to obtain the maximum allowable diameter of the p-side electrode 24 when the diameter of the desired light emitting region 22a (pixel size depending on the application) is 100 μm. Although the shape of the light emitting region 22a and the shape of the p-side electrode 24 in plan view are described as circles, other shapes such as squares and ellipses can be obtained in the same manner.

As shown in FIG. 4, let the diameter of the p-side electrode 24 in plan view be Le, the diameter of the light emitting region 22 a be Lp, and the diameter of outgoing light emitted from the upper surface of the light emitting structure 2 be Ls.
As described above, when GaN is used as a semiconductor, the diameter Le of the p-side electrode 24 and the diameter Lp of the light emitting region 22a are substantially the same (Lp) due to the relationship between carrier mobility and recombination time. ≒ Le). The light emitted from the light emitting region 22a spreads when propagating through the n-type semiconductor layer 23, but when emitted from the n-type semiconductor layer 23 to the outside, the refractive index (dielectric constant) of the n-type semiconductor layer 23 is generated. ) And the critical angle θc determined by the external refractive index, the diameter of the light extracted outside is also limited. That is, light incident on the interface between the n-type semiconductor layer 23 and the outside at an incident angle larger than the critical angle θc is totally reflected at the interface and is not extracted outside. Let w be the spread from the region immediately above the light emitting region 22a when the critical angle θc is reached. The thickness of the n-type semiconductor layer 23 is d.
At this time, there is a relationship of Equation (1) between these parameters.
Ls = Lp + 2w
= Lp + 2d · tan θc (1)

  Here, for example, when d = 5 μm and θc = 19 °, the diameter Ls of the light extracted to the outside is Le + 3.4 μm. Therefore, the diameter of the p-side electrode 24 is required to be 93 μm in order to set the diameter Ls of the light extracted outside to 100 μm.

Returning to FIG. 1 and FIG. 2, the description of the configuration of the light emitting element 1 will be continued.
The emission direction specifying part 3 is provided on the upper surface of the light emitting structure part 2 and specifies the direction of the light emitted from the light emitting element 1 by using the light interference action of the light emitted from the light emitting layer 22 of the light emitting structure part 2. It has a structure 3a. In the present embodiment, the emission direction specifying part 3 has a structure 3a on the upper surface of the n-type semiconductor layer 23 which is a flat surface. Further, the structure 3a has three columnar portions 31, 32, 33 so as to surround a predetermined region, and the height of at least one columnar portion from the upper surface of the n-type semiconductor layer 23 (hereinafter simply referred to as “columnar”). Unlike the height of the other columnar portions, the height of the portion is called “the height of the portion”, and light is emitted from the upper surfaces of all the columnar portions 31, 32, 33. And it makes it have intensity | strength in a specific direction using the interference of the lights radiate | emitted from the upper surface of these columnar parts 31,32,33.

  The structure 3a specifies the direction of the light emitted from the light emitting element 1 by using the light interference action of the light emitted from the light emitting layer 22 of the light emitting structure section 2. In the present embodiment, the structure 3a is composed of three columnar portions 31, 32, 33 having a circular cross section. In the present embodiment, the columnar portion 33 is described as being lower than the columnar portions 31 and 32.

The columnar portions 31, 32, and 33 are light guide members that propagate light incident from the light emitting structure portion 2 and emit the light from the upper surfaces 31a, 32a (not shown) and 33a. The height of the columnar portion 33 is formed to be lower than the height of the columnar portions 31 and 32. The light emitted from the upper surfaces 31 a, 32 a (not shown) and 33 a of the columnar parts 31, 32 and 33 interfere with each other, and the direction according to the arrangement of the columnar parts 31, 32 and 33 (on the upper surface of the n-type semiconductor layer 23). A light beam having intensity in a parallel plane orientation and an elevation angle with respect to the plane is emitted from the emission direction specifying unit 3.
The details of the principle of specifying the light emission direction by the emission direction specifying unit 3 will be described later.

The emission direction specifying unit 3 can be made of a material having translucency with respect to incident light. For example, a dielectric material such as SiO ₂ or Al ₂ O ₃ can be used. Further, the semiconductor material similar to that of the n-type semiconductor layer 23 can be used.
Moreover, although the output direction specifying part 3 in the present embodiment is configured to provide the columnar parts 31, 32, 33 directly on the upper surface of the n-type semiconductor layer 23, the present invention is not limited to this. For example, a layer having a uniform thickness may be provided as a base on the upper surface of the n-type semiconductor layer 23, and the columnar portions 31, 32, and 33 that are the structures 3a may be provided on the upper surface of the base. Further, instead of providing the emission direction specifying portion 3 on the upper surface of the light emitting structure portion 2, a part of the n-type semiconductor layer 23 (for example, an n-type buffer layer) that is an upper portion of the light emitting structure portion 2 is processed to form a columnar shape. The portions 31, 32, and 33 may be formed.
Moreover, the columnar parts 31, 32, and 33 are not limited to a cylindrical shape, and may be polygonal columns. Moreover, the number of columnar parts should just be three or more, for example, can also be set to six.

  Next, with reference to FIG.5 and FIG.6, the shape and arrangement | positioning of the three columnar parts 31,32,33 and the light emission area | region 22a which comprise the structure 3a of the emission direction specific | specification part 3 are demonstrated.

(Space between columnar parts)
The columnar portions 31, 32, and 33 have a diameter that is approximately equal to or greater than the wavelength λ _{0 of} light emitted from the light emitting region 22 a of the light emitting element 1. Here, the wavelength λ ₀ indicates the wavelength of the emitted light in free space. 5 and 6, the shapes of the columnar portions 31, 32, and 33 in plan view are shown as circles. The thickness of each columnar part 31, 32, 33 was made equal (radius is set to φ). As shown in FIG. 5, the columnar portions 31, 32, and 33 are oriented at a uniform angle α (α = 120 degrees in this example) around a predetermined origin M on the light emission surface of the light emitting element 1. Are spaced apart from each other by a distance p. Further, the interval p between the columnar portions 31, 32, 33 is set to such an extent that light emitted from the adjacent columnar portions 31, 32, 33 can interfere. That is, it is preferable that the columnar portions 31, 32, and 33 are not longer than the coherence length of the emitted light. The coherence length of light depends on the center wavelength and the half width of the emission spectrum of light emitted from the light emitting structure 2 (see FIG. 1) that is a light source. When the light source is an LED, for example, the length is about 10 to several tens of μm in a vacuum.

(The origin M of the arrangement of the plurality of columnar portions)
In the example shown in FIG. 5, the predetermined origin M is the center of a predetermined region that is annularly surrounded by three columnar portions 31, 32, 33 on the upper surface of the light emitting structure 2 (see FIGS. 1 and 2). It is a point to be located. Further, the origin is the center O ₃ of the columnar portion 33 and the center O ₂ of the columnar portion 32, is a point from the center O ₁ Metropolitan columnar portion 31 at equal distances, the center O _1, O _2, O ₃ Is the center of gravity of an equilateral triangle with the apex at. Here, it is preferable that the three columnar parts 31, 32, and 33 are arranged in an annular shape and equally. The shape and size of the predetermined region surrounded by the columnar parts 31, 32, 33 can be appropriately designed as desired while balancing the diameter of the columnar parts 31, 32, 33. For example the diameter of the columnar portion 31, 32 and 33, if the number wavelengths about partial emission wavelength lambda _0, the size of the predetermined area may be a fraction of the wavelength to several order of the wavelength.

The distance ρ from the origin M to the columnar portions 31, 32, 33 on the lines connecting the origin M and the centers O ₁ , O ₂ , O _{3 of the} columnar portions 31, 32, 33, respectively, is in free space. It is preferable that the wavelength of the emitted light is λ ₀ or less, for example, about ¼ to 1 wavelength. In particular, when the distance ρ is set to be about ¼ of the diameter 2φ of the columnar parts 31, 32, 33, the upper surfaces 31a, 32a, 33a that are the emission surfaces of the columnar parts 31, 32, 33 (see FIG. 7). It is preferable because the light emitted from each other can interfere with each other and can be molded well and a sufficiently strong light beam can be emitted.

As shown in FIG. 7, of the columnar portions 31, 32, 33, the heights of the two columnar portions 31, 32 from the upper surface 30 a of the bottom 30 that is a reference surface are respectively set as a reference height H and To do. If the difference between the height of the columnar portion 33 and the height of the other columnar portions 31 and 32 is δ, the height of the columnar portion 33 is (H−δ). In the present embodiment, the height difference δ is set to be equal to or less than the wavelength λ ₁ of the radiated light in the columnar portions 31, 32, 33 in order to form a light beam with good directivity by light interference. preferably, it is more preferably half or less of the wavelength lambda ₁ is obtained as the result of the experiment.

Here, the wavelength λ ₁ is a wavelength when light having the wavelength λ ₀ propagates in the free space through the columnar portions 31, 32, and 33 as an optical waveguide. In general, the dielectric constant of semiconductors and dielectrics is higher than that of air (or vacuum), so the speed of light when propagating in semiconductors and dielectrics is faster than the speed of propagation in air. Become slow. Specifically, when the velocity of light in the air (or in vacuum) is c, and the refractive index of a material such as a semiconductor or a dielectric constituting the columnar portions 31, 32, 33 is n, the columnar portions 31, 32, The speed of light propagating through 33 is given by c / n.

Therefore, the wavelength λ ₁ can be obtained by dividing the value of the wavelength λ ₀ by the refractive index n inside the columnar portions 31, 32, 33. For example, the light emitting structure 2 (see FIG. 1) is made of a GaN-based semiconductor, emits blue light having a wavelength λ ₀ of 405 nm, and the columnar portions 31, 32, and 33 are made of GaN having a refractive index n = 2.6. In this case, the wavelength λ ₁ of the light propagating through the columnar parts 31, 32, 33 is about 156 nm.
In the following description, when the emission direction is specified by the columnar portions 31, 32, 33, the columnar portions 31, 32 may be referred to as a waveguide column and the columnar portion 33 may be referred to as a control column due to a difference in function.

(Reciprocal relationship between light emitting region and columnar part)
Next, referring to FIG. 6 (refer to FIGS. 1 and 2 as appropriate), the mutual relationship between the dimensions of the light emitting region 22a and the dimensions of the columnar portions 31, 32, 33 will be described.
In the following description, for the sake of simplicity, the n-type semiconductor layer 23 and the emission direction specifying portion 3 will be described as being made of a material having the same refractive index. In the case of being made of materials having different refractive indexes, Ls calculated by the above-described equation (1) is used as the dimension of the light emitting region 22a instead of the diameter Lp.

  As described above, in the light emitting element 1, the light emitted from the light emitting region 22 a enters the columnar portions 31, 32, 33 through the n-type semiconductor layer 23 and propagates through the columnar portions 31, 32, 33. Thus, a light beam is formed by interference of light emitted from the upper surfaces 31a, 32a, and 33a that are emission surfaces. Therefore, the intensity of the light beam formed by the interference of the light emitted from the upper surfaces 31a, 32a, 33a of the columnar portions 31, 32, 33 is such that the light emitted from the light emitting region 22a is inside the columnar portions 31, 32, 33. It depends on the amount taken. If the amount of light emitted from the light emitting region 22a is taken into the columnar portions 31, 32, and 33 is less than a certain amount, sufficient intensity from the upper surfaces 31a, 32a, 33a of the columnar portions 31, 32, 33 is obtained. Light is not emitted, and it becomes difficult to form a clear light beam due to interference of these lights.

  On the other hand, in order to improve the arbitrary control of the direction of the light beam emitted from the upper surfaces 31a, 32a, 33a of the columnar portions 31, 32, 33, light is emitted from the light emitting region 22a and the columnar portions 31, 32, 33 are made incident. The light leaking from the element surface (the upper surface of the n-type semiconductor layer 23) and the light incident on the columnar portions 31, 32, 33 and emitted from the upper surfaces 31a, 32a, 33a cause extra interference. It is necessary to suppress this.

  In order to achieve both of these, the dimensions of the light emitting region 22a and the columnar portions 31, 32, 33 are set so that the relationship described below is established between the light emitting region 22a and the columnar portions 31, 32, 33. It is desirable to define the dimensions.

As shown in FIG. 6, first, a planar figure drawn so as to be in contact with a part of the outer edges of the columnar portions 31, 32, 33 so as to surround all three columnar portions 31, 32, 33 is assumed. Here, a circular figure surrounding all of the columnar parts 31, 32, 33 is assumed as a planar figure as shown by a two-dot chain line in FIG. 6. The center of this circle coincides with the origin M, which is the center of gravity of an equilateral triangle having vertices at the centers O ₁ , O ₂ , and O ₃ of the columnar parts 31, 32, and 33 (see FIG. 5). Here, the radius _{r SO} of the smallest circle enclosing all the columnar portion 31, 32, the distance ρ from the origin M to the columnar portion 31, 32, 33, the diameter 2φ of the columnar portion 31, 32, 33 added It will be.

Therefore, as shown in FIG. 6, the area SO of the smallest circle (drawn with a two-dot chain line) surrounding all the columnar parts 31, 32, 33, the area SL of the light emitting region 22a (drawn with a broken line), and the columnar part 31 , 32, 33 can be obtained from the equations (2) to (4), respectively.
SL = πΨ ² ... Formula (2)
SO = π (2φ + ρ) ² Formula (3)
SP = πφ ² Formula (4)

Here, Ψ in formula (2) is the radius of the light emitting region 22a.
At this time, it is desirable that the relationship of the formula (5) is established between the area SL of the light emitting region 22a and the area SO of the smallest circle surrounding all the columnar portions 31, 32, and 33.
SL ≦ SO (5)

Further, it is desirable that the relationship of Expression (6) is established between the area SL of the light emitting region 22a and the area 3SP that is the sum of the areas SP of the columnar portions 31, 32, and 33.
3SP ≦ SL (6)

In Equation (6), the number to be multiplied by the area SP varies depending on the number of columnar portions installed.
Therefore, when these are put together, it is desirable that the relationship shown in Expression (7) is satisfied in order to achieve both the improvement of the clarity of the light beam and the improvement of the arbitrary control of the light beam direction.
N × SP ≦ SL ≦ SO (7)
However, N shows the installation number of the columnar part and is an integer of 3 or more.

As shown in the equation (7), by setting the area SL of the light emitting region 22a to be equal to or smaller than the area SO of the smallest circle that surrounds all the columnar parts 31, 32, 33, the light emitted from the light emitting region 22a can be obtained. Leakage from the element surface (upper surface of the n-type semiconductor layer 23) other than the columnar portions 31, 32, 33, and suppression of unnecessary interference with light emitted from the upper surfaces of the columnar portions 31, 32, 33 Therefore, it is possible to improve the arbitrary control of the direction of the light beam.
In plan view, the area SL of the light emitting region 22a is the same as the area of the p-side electrode 24 as described above, more precisely the area where the upper surface of the p-side electrode 24 and the lower surface of the p-type semiconductor layer 21 are in contact with each other. Can be considered.

  Further, as shown in the equation (7), the light emitted from the light emitting region 22a is obtained by setting the area SL of the light emitting region 22a to an area 3SP or more which is the sum of the areas SP of the columnar portions 31, 32, 33. Most of the light can enter the columnar portions 31, 32, and 33. For this reason, the intensity | strength of the light which propagates the inside of the columnar parts 31, 32, 33, and is radiate | emitted from an upper surface can be made high. Thereby, the clarity of the light beam formed by the interference of these lights can be improved.

[Principle of interference of light emitted from columnar portion of light emitting element]
Next, the principle of interference of light emitted from the columnar portions 31, 32, 33 of the light emitting element 1, which is a principle for specifying the direction of the light emitted from the light emitting element 1, is appropriately expressed with reference to FIG. Will be described. Since the columnar part 31 and the columnar part 32 have the same height, in the description using FIG. 7 and the mathematical formula, for convenience, the columnar part 31 and the columnar part 32 are emitted from the two columnar parts 32 and the columnar part 33 having different heights. An example of light interference will be described.

In the light emitting device 1 shown in FIG. 7, the upper surface of the n-type semiconductor layer 23 is set as a reference position (altitude h ₀ ). Further, altitude h ₁ the position of the upper surface 33a which is the light exit surface of the columnar portion _33, the position of the upper surface 32a which is the light exit surface of the columnar portion 32 and altitude h _2, the columnar portion 32 and the columnar portion 33 Let p be the horizontal interval. Further, in the horizontal position equidistant from the central axis of the columnar portions 32 and 33, and altitude h ₃ of the predetermined point C of the upper surface perpendicular to the axial direction of the n-type semiconductor layer 23 (drawn with dashed-dotted lines). At this time, the height H of the columnar part 32 is h ₂ −h ₀ , and the height (H−δ) of the columnar part 33 is h ₁ −h ₀ . Accordingly, the difference in height between the columnar portion 32 and the columnar portion 33 is δ = h ₂ −h ₁ .

  As shown in FIG. 7, the light emitted from the light emitting region 22 a in the light emitting element 1 branches into a high columnar portion 32 and a low columnar portion 33 and is emitted from the upper surfaces 32 a and 33 a of the respective columnar portions 32 and 33. The Here, when passing through the high columnar portion 32, the point C passes through the point A1 in the columnar portion 32 and the center point A2 of the upper surface 32a of the columnar portion 32 as one optical path (hereinafter referred to as optical path A). Assume an optical path to reach. Further, when passing through the low columnar portion 33, as one optical path (hereinafter referred to as “optical path B”), the point C passes through the center point B 1 of the upper surface 33 a of the columnar portion 33 and the position B 2 higher than the point B 1 by δ. Assume an optical path to reach.

The light passing through the optical path A and the light passing through the optical path B stay in the same phase because they travel through the medium having the same refractive index (exit direction specifying unit 3) by the same distance up to the height h ₁ . When the phase of the time the initial phase theta _0, the phase in the optical path A point A1 is theta _0, the phase in the optical path point B1 B, is theta _0.

The light passing through the optical path A and the light passing through the optical path B travel through different media from the altitude h ₁ to the altitude h ₂ . At this time, in the optical path A, the medium is a columnar portion 32 (for example, a semiconductor or a dielectric), and in the optical path B, the medium is air. Generally, since the dielectric constant of a semiconductor or a dielectric is higher than that in air (or in a vacuum), the speed of light when propagating in the semiconductor or dielectric is slower than the speed of propagating in air. Specifically, if the velocity of light in the atmosphere (or vacuum) is c and the refractive index of the semiconductor or dielectric is n, the velocity in the semiconductor or dielectric is given by c / n (for example, with GaN). For example, n = 2.6). For this reason, the light generated in the light emitting element 1 made of a semiconductor or a dielectric material is split into two, one is directly emitted into the atmosphere (or in a vacuum), and the other is propagated in the semiconductor or the dielectric. When the light is emitted after the two light beams are emitted, the optical paths are different when they are encountered after the two light beams have been emitted, so that the phases of the light beams are different. Therefore, when the wavelength in the free space of the light from the light emitting element 1 shown in FIG. 7 is λ ₀ and the phase advances by α in the semiconductor or the dielectric in the section from the height h ₁ to the height h ₂ in the optical path A. Then, in the optical path A, the phase is represented by Expression (8) at the point A2.

Further, assuming that the phase advances by β in the free space from the height h ₁ to the height h _{2 in} the optical path B, the phase in the optical path B is expressed by Expression (9) at the point B2.

Since more free space from the altitude h ₂ to advanced h _3, the light passing through the light and the optical path B passing through the optical path A travels the same medium (free space). At this time, the distance from the point A2 to the point C on the optical path A and the distance from the point B2 to the point C on the optical path B are the same. Therefore, the difference between the phase at the point A2 of the light passing through the optical path A and the phase at the point B2 of the light passing through the optical path B is also preserved at the point C. This phase difference τ is expressed by equation (10). That is, the phase difference τ between the optical path A and the optical path B can be controlled by the height difference δ between the columnar section 32 and the columnar section 33. When the equation (10) is transformed, the height difference δ is expressed by the equation (11).

  Since the light passing through the columnar part 32 is delayed as compared with the light passing through the columnar part 33, when both are mixed, a wave having a completely different wavefront from the wavefront of the two lights is generated. That is, the wave fronts of the light emitted from the columnar portions 32 and 33 interfere with each other, and light is transmitted in an azimuth (direction) determined by the relative position (position in the three-dimensional space) of the two columnar portions 32 and 33. Will be injected.

Next, interference of light emitted from the columnar part 32 as the wave source at the position r ₁ in the three-dimensional space and the columnar part 33 as the wave source at the position r ₂ in the three-dimensional space will be described.
The intensity I (r) of the light synthesized at the time r in the three-dimensional space r by the light emitted from the wave source at the position r ₁ and the wave source at the position r ₂ is expressed by the following equation (12 ).

In Equation (12), since there is a third term representing the interference of light, the light emitted from the light emitting region 22a is superimposed after being emitted from the two wave sources, and the wave travels by changing the wavefront. The direction can be changed. In Expression (12), the real part of γ in Expression (13) is used. E ^{* in the} formula (13) indicates a complex conjugate of E. As shown in Equation (13), γ takes a value from 0 to 1, and indicates how much the light emitted from the two wave sources is correlated in time and space. Therefore, γ can be divided into cases as shown in the following equations (14) to (16).

The case of Equation (14) is called fully coherent, the case of Equation (15) is called incoherent, and the case of Equation (16) is called partial coherent. Here, since the light source of LED is used as the light emitting element 1, it is partially coherent. Therefore, in the light-emitting element 1 shown in FIG. 7, the contribution of the third term of the above-described formula (12) is large in the light intensity, so that the light traveling direction is greatly bent.
When the horizontal interval p between the columnar portions 32 and 33 is very small, the magnitude of the bending of the light traveling direction is a factor that is dominant due to the height difference δ between the columnar portion 32 and the columnar portion 33. It becomes.

  In FIG. 7, for the sake of simplicity, the direction of the light beam due to the interference of the light emitted from the two columnar portions having different heights has been described. Even when there are three columnar portions as wave sources, it is possible to extend the above-described equation (12). For example, the combination of the first columnar part 31 and the second columnar part 32 is applied to the two wave sources, and the above-described formula (12) is applied, and the combination of the second columnar part 32 and the third columnar part 33 is determined. The above-described equation (12) is applied as two wave sources, the above-described equation (12) is applied using the combination of the third columnar portion 33 and the first columnar portion 31 as two wave sources, and these three combinations are By adding, a relational expression for the case where there are three columnar portions as wave sources can be obtained.

  Note that the emission direction shown in FIG. 7 is schematically shown in order to explain the state of the light beam emitted from the emission direction specifying unit 3. That is, the columnar structure shown in FIG. 7 does not always indicate that the light is emitted while being inclined toward the shorter columnar part. The direction of the emission direction depends on the number and arrangement of the columns, the interval between the columns, and the like, and there are cases where the emission direction is inclined toward the long columnar part.

Returning to FIGS. 1 and 2, the description of the configuration of the light-emitting element 1 will be continued.
The lower electrode 41a and the lower electrode 41b are band-like electrodes provided along the left end and the right end of the lower surface of the light emitting structure 2 via the lower insulating layer 42a and the lower insulating layer 42b, respectively.
Further, the upper electrode 44a and the upper electrode 44b are band-like electrodes provided along the front end and the rear end of the upper surface of the light emitting structure portion 2 through the upper insulating layer 43a and the upper insulating layer 43b, respectively. The lower electrode 41a and the upper electrode 44a, and the lower electrode 41b and the upper electrode 44b are provided so as to partially face each other with the light emitting structure 2 interposed therebetween.
The lower electrodes 41a and 41b and the upper electrodes 44a and 44b cause distortion of the semiconductor crystal of the light emitting structure 2 using the inverse piezoelectric effect, thereby tilting the upper surface of the light emitting structure 2 and This is an electrode for changing the emission direction for changing the emission direction of the light specified by the emission direction specification unit 3 provided on the upper surface by the inclination angle of the upper surface of the light emitting structure unit 2.

Here, with reference to FIG. 8 (refer to FIGS. 1 and 2 as appropriate), the principle of modulating the emission direction of the light beam will be described. In FIG. 8, the upper electrodes 44a and 44b are not shown.
Here, the modulation of the light emission direction will be described by taking as an example the case where the upper surface of the light emitting structure 2 is inclined in the left-right direction (X-axis direction).
As shown in FIG. 8A, when no voltage is applied between the lower electrodes 41a and 41b and the upper electrodes 44a and 44b (see FIG. 2) of the light emitting structure 2, the upper surface of the light emitting structure 2 is It is parallel to the upper surface of the substrate 40 (a surface parallel to the XY plane). At this time, it is assumed that the emission direction of the light beam specified by the emission direction specification unit 3 is θx with respect to the normal line of the upper surface of the light emitting structure unit 2.

  Next, as shown in FIG. 8B, a voltage is applied between the lower electrode 41a and the upper electrode 44a (see FIG. 2), and a tensile stress acts on the right end of the light emitting structure 2 in the vertical direction. Apply an electric field to Thereby, the upper surface of the light emitting structure 2 is inclined upward. Here, this inclination angle with respect to the upper surface of the substrate 40 is defined as φx. Since the emission direction specifying unit 3 emits light rays in the direction of θx with respect to the normal line of the upper surface of the light emitting structure unit 2, the light rays are emitted in the direction of (θx + φx) with respect to the normal line of the upper surface of the substrate 40. Will be.

  Further, as shown in FIG. 8C, a voltage is applied between the lower electrode 41b and the upper electrode 44b (see FIG. 2), and a tensile stress acts on the left end of the light emitting structure 2 in the vertical direction. Apply an electric field. As a result, the upper surface of the light emitting structure 2 is inclined upward. Here, this inclination angle with respect to the upper surface of the substrate 40 is defined as −φx. Since the emission direction specifying unit 3 emits a light beam in the direction of θx with respect to the normal line of the upper surface of the light emitting structure unit 2, the light beam is emitted in the direction of (θx−φx) with respect to the normal line of the upper surface of the substrate 40. It will be emitted.

As described above, by tilting the upper surface of the light emitting structure portion 2 using the inverse piezoelectric effect, the direction of the light beam emitted from the emission direction specifying portion 3 that is tilted in conjunction with this can be modulated. .
In this example, modulation is possible in three directions depending on how the voltage is applied, but it is also possible to modulate in more stages by finely controlling the applied voltage. Conversely, the modulation may be performed in two states inclined to the left or right, that is, in two stages of (θx + φx) and (θx−φx). In this case, the degree of modulation can be 2φx, which is the difference between the left and right tilt angles.

  In this example, the voltage is applied to one of the left end and the right end to expand it. Compared to the voltage applied when the semiconductor crystal of the light emitting structure 2 is stretched (forward bias), the voltage applied when compressing the semiconductor crystal (reverse bias) needs to be high. is there. For this reason, by applying a voltage only to the expansion side, the applied voltage can be lowered, and the expansion can be performed at a higher speed than the compression.

Further, the present invention is not limited to the configuration using only the expansion mode, and the voltage may be applied to the left end and the right end in the opposite direction at the same time. Thereby, an inclination angle can be increased more.
Alternatively, an electrode may be provided only at one of the left end and the right end, and a voltage may be applied to expand or / and compress.
In addition, the upper electrode and the lower electrode may be provided separately on four sides in plan view, and the light emission direction may be modulated not only in the X-axis direction but also in the Y-axis direction.

In addition, when using the light emitting element 1 of this invention as a pixel of an IP solid display, the above-mentioned inclination | tilt angle (phi) x may be about 0.1 degree or less, and it is preferable that it is about 0.3 degree or more. .
For example, consider a case where the element image of the IP stereoscopic display is an element pixel group corresponding to 60 × 60 pixels and the viewing angle at which stereoscopic viewing is possible is assumed to be 40 °. At this time, the angle pitch (angular resolution) when one light emitting element 1 modulates the emission direction and emits the light beam in the adjacent direction at a constant angle unit in the unit corresponding to the adjacent pixel of the element image is
40 ° / 60 = 0.66667 °
It becomes.

The above is a case where the element image is composed of an element pixel group corresponding to 60 × 60 pixels. However, when the element image has a structure corresponding to multiple pixels, this angular resolution becomes even finer. That is, in the case of a 600 × 600 element pixel group in which the number of element pixels is increased by one digit, the angle pitch (angle resolution) is
40 ° / 600 = 0.06667 °
It becomes.
When configuring such an IP stereoscopic display corresponding to a large number of element pixels, the inverse luminance effect is used to continuously change the emission luminance of the LED while changing the emission direction in increments of angular resolution. The luminance is modulated.

In the above-described example (element pixel is equivalent to 60 × 60 pixels), if one light emitting element 1 is tilted to the left and right to modulate the emission direction and emit light in two emission directions, The angle difference (2φx) may be set to 0.66 °. Therefore, the inclination angle φx≈0.3 ° can be set.
The tilt angle φx described above is an example, and can be appropriately determined according to the observation distance from the display panel and the density in the emission direction.

  Note that the emission direction shown in FIG. 8 is schematically shown in order to explain the state of the light beam emitted from the emission direction specifying unit 3, similarly to the emission direction shown in FIG. 7. That is, the columnar structure shown in FIG. 8 does not always indicate that the light is emitted while being inclined toward the shorter columnar part. The direction of the emission direction depends on the number and arrangement of the columns, the interval between the columns, and the like, and there are cases where the emission direction is inclined toward the long columnar part.

[Operation of light emitting element]
Next, the operation of the light emitting device 1 according to the first embodiment will be described with reference to FIGS. 1 and 2.
In the light-emitting element 1 according to the first embodiment, by supplying power between the n-side electrode 25 and the p-side electrode 24, the light-emitting layer 22 of the light-emitting structure unit 2 emits light, and the light enters the emission direction specifying unit 3. Is done. Light incident on the emission direction specifying unit 3 from the light emitting structure unit 2 is output in a direction specified by the configuration of the columnar parts 31, 32, and 33 that are structures of the emission direction specifying unit 3. When a voltage is applied between the lower electrodes 41a and 41b and the upper electrodes 44a and 44b, the semiconductor layer constituting the light emitting structure 2 is deformed according to the applied voltage due to the inverse piezoelectric effect. And according to the applied voltage, the upper surface of the light emission structure part 2 inclines, and the emission direction specific | specification part 3 inclines in response to this. At this time, the direction of the light beam emitted from the emission direction specifying unit 3 is modulated by the amount by which the emission direction specifying unit 3 is inclined.

[Method for Manufacturing Light-Emitting Element]
Next, with reference to FIG. 9 to FIG. 11 (refer to FIG. 1 and FIG. 2 as appropriate), a method for manufacturing the light emitting device according to this embodiment will be described.
In this example, the case where an LED structure is formed using a GaN-based compound semiconductor as the light emitting structure 2 will be described.

(Light emitting structure preparation process)
First, in the light emitting structure preparing step, the light emitting structure 2 is prepared as shown in FIG.
The light emitting structure 2 is formed on a substrate 50 made of sapphire, GaN, AlN, GaAs, SiC, Si, ZnO or the like, for example, by MBE (molecular beam epitaxy) method, MOCVD (metal organic chemical vapor deposition) method or the like. The peeling layer 51, the n-type semiconductor layer 23, the light emitting layer 22, and the p-type semiconductor layer 21 can be sequentially stacked by a film method.

  More specifically, the n-type semiconductor layer 23 is formed by growing a crystal made of GaN doped with Si, which is an n-type impurity, through an underlayer (buffer layer) made of non-doped GaN or the like. The n-type semiconductor layer 23 may be formed in a two-layer structure of, for example, an n-type contact layer made of GaN and an n-type clad layer made of AlGaN. The underlayer can be omitted depending on the combination of materials of the substrate 1 and the n-type semiconductor layer 23.

  The light emitting layer 22 is provided between the n-type semiconductor layer 23 and the p-type semiconductor layer 21 and is formed by stacking, for example, InGaN or the like on the n-type semiconductor layer 23. Note that an active layer made of InGaN can be formed as the light emitting layer 22 to form a double hetero structure, or an active layer made of a different material is not provided between the n-type semiconductor layer 22 and the p-type semiconductor layer 21. The n-type semiconductor layer 23 and the p-type semiconductor layer 21 may be directly joined, and the pn junction surface (interface) may be the light emitting layer 22. Further, as the light emitting layer 3, for example, an active layer having a quantum well structure, preferably a multiple quantum well structure, in which barrier layers made of non-doped GaN and well layers made of non-doped InN or InGaN are alternately stacked may be formed. Good.

The p-type semiconductor layer 21 is formed on the light emitting layer 22 by growing a crystal made of GaN doped with Mg, which is a p-type impurity. Similarly to the n-type semiconductor layer 23, the p-type semiconductor layer 21 may be formed, for example, in a two-layer structure of a p-type cladding layer made of GaN and a p-type contact layer made of AlGaN.
Note that it is preferable to provide a bonding surface that is lattice-mismatched in each semiconductor layer because a large inverse piezoelectric effect can be used.

The peeling layer 51 peels off the substrate 50 used for growing the light emitting structure 2 which is a semiconductor layer in the peeling process described later after bonding the substrate 40 and the light emitting structure 2 in the bonding process described later. It is a layer to do. For example, when the substrate 50 is peeled off by the laser lift-off method, for example, the base layer when forming the n-type semiconductor layer 23 can be used as the peeling layer 51 (see, for example, Reference 1). This peeling layer 51 is decomposed by laser irradiation in a peeling process described later, and the substrate 50 can be peeled from the light emitting structure 2.
(Reference 1): Japanese Patent No. 4653804

When the substrate 50 is peeled off by the chemical lift-off method, a nitride layer of a metal layer such as Cr can be formed on the substrate 50 as the peeling layer 51 (see, for example, Reference 2). ). The peeling layer 51 made of the metal nitride is removed by chemical etching using a liquid agent in a peeling process described later, and the substrate 50 can be peeled from the light emitting structure 2. Compared with the laser lift-off method, the chemical lift-off method is high in productivity because it can process a large number of wafers at the same time. Also, the yield is high because there is less stress on the semiconductor layer during peeling and the generation of cracks is suppressed. Is expensive.
The release layer 51 made of metal nitride can be formed on the substrate 50 by MOCVD. As another method, after forming a metal film on the substrate 50 by sputtering or vapor deposition, the metal film is nitrided in an ammonia-containing gas atmosphere at a temperature of 1040 ° C. or more to form a metal nitride film. You can also
(Reference Document 2): JP 2009-54888 A

(Lower insulation layer formation process)
Next, in the lower insulating layer forming step, the lower insulating layers 42a and 42b are formed by photolithography.
In this step, first, as shown in FIG. 9B, an insulating layer 42 is formed on the entire surface of the p-type semiconductor layer 21. The insulating layer 42 can be formed using an insulating material such as SiO ₂ or Al ₂ O ₃ by, for example, a sputtering method or a CVD method.
Next, as shown in FIG. 9C, a mask 52 for patterning the insulating layer 42 is formed. The mask 52 is formed by applying a photoresist to the surface of the insulating layer 42, irradiating it with UV light in a desired shape, and developing it. Next, as shown in FIG. 9D, the insulating layer 42 is etched using the mask 52 until the p-type semiconductor layer 21 is exposed, and the remaining insulating layer 42 becomes lower insulating layers 42a and 42b. When SiO ₂ is used as the insulating material of the insulating layer 42, as an etching method, for example, wet etching using an aqueous solution of HF (hydrogen fluoride) or KOH (potassium hydroxide), SF ₆ , CHF ₃ gas plasma is used. The dry etching used can be used.
In the present embodiment, the mask 52 is not removed here because it is used in the p-side electrode forming process which is the next process.

(P-side electrode formation process)
Next, in the lower insulating layer forming step, the p-side electrode 24 is formed on the surface of the p-type semiconductor layer 21 exposed from the lower insulating layers 42a and 42b by a lift-off method.
In this step, first, as shown in FIG. 9E, a conductive layer 53 is formed using a conductive material such as Al or Cu. At this time, the conductive layer 53 is also formed on the mask 52.
Next, as shown in FIG. 9F, the conductive layer 53 is patterned by removing the mask 52 together with the unnecessary conductive layer 53 formed on the mask 52, and the p-side electrode 24 is formed.

(Lower electrode formation process)
Next, in the lower electrode formation manufacturing process, lower electrodes 41a and 41b are formed on the lower insulating layers 42a and 42b by a lift-off method.
In this step, first, as shown in FIG. 9G, a mask 54 is formed to cover the p-side electrode 24 and a part of the lower insulating layers 42a and 42b which are the periphery thereof. The reason why the lower insulating layers 42a and 42b are partially covered is to prevent a short circuit between the p-side electrode 24 and the lower electrodes 41a and 41b formed in this step. The mask 54 is formed by applying a photoresist to the entire surface of the p-side electrode 24 and the lower insulating layers 42a and 42b, irradiating UV light in a desired shape, and developing. Next, as shown in FIG. 9H, a conductive layer 55 such as Al or Cu is formed on the lower insulating layers 42a and 42b and the mask 54 by, for example, a vapor deposition method. Then, as shown in FIG. 10A, by removing the mask 54 together with the unnecessary conductive layer 55 formed on the mask 54, the conductive layer 55 is patterned, and the lower electrodes 41a and 41b are formed.

(Lamination process)
Next, in the bonding step, as shown in FIG. 10B, the light emitting structure 2 provided with the p-side electrode 24 and the lower electrodes 41a and 41b manufactured in the steps up to the lower electrode formation step is formed into a p-type. The substrate 40 is bonded to the semiconductor layer 12 side. The substrate 40 is provided with a bonding layer 40b for fusing to the light emitting structure 2 on a base body 40a. The substrate 40a can be a glass plate or a metal plate such as Cu or Al. The bonding layer 40b can be made of a resin that melts at about 300 ° C. In the bonding process, the substrate 40 is fused to the light emitting structure 2 including the p-side electrode 24 and the lower electrodes 41a and 41b by heating to about 300 ° C. while applying pressure between the substrate 40 and the substrate 50. Let
When the substrate 40 is, for example, a display panel substrate of an IP stereoscopic display and the plurality of light emitting elements 1 are arranged and supported, the p-side electrode 24 and the lower electrodes 41a and 41b of the plurality of light emitting elements 1 are respectively provided. A wiring pattern for electrical connection may be provided.

(Peeling process)
Next, in the peeling step, the substrate 50 is peeled from the light emitting structure 2 as shown in FIG.
In the case of peeling by the laser lift-off method described above, the GaN underlayer of the peeling layer 51 is irradiated with, for example, a nanosecond pulse of an excimer laser of near-ultraviolet light to decompose GaN, and the substrate 50 is separated from the light emitting structure 2. Can be peeled off.
Moreover, when peeling by the above-described chemical lift-off method, the metal nitride layer which is the peeling layer 51 can be removed by chemical etching using a liquid agent, and the substrate 50 can be peeled from the light emitting structure 2. For example, when the metal nitride is CrN, a mixed liquid of perchloric acid and dicerium ammonium nitrate can be used as an etching liquid.
In addition, the substrate 50 and the light emitting structure 2 can be peeled using a void peeling method. In the void peeling method, a layer having fine voids (holes) at a high density and a low mechanical strength is formed as a peeling layer 51 as a base layer between the substrate 50 and the light emitting structure 2 that is a semiconductor layer. In this method, the light emitting structure 2 and the substrate 50 are naturally peeled off using the thermal stress generated when the temperature drops after the semiconductor layer is formed.

  Further, by performing the bonding process and the peeling process, the light emitting structure 2 is transferred from the substrate 50 to the substrate 40, and sequentially from the lower layer side close to the substrate 40, the p-type semiconductor layer 21, the light emitting layer 22, and the n-type semiconductor. The layer 23 is laminated.

(Upper insulating layer formation process)
Next, in the upper insulating layer forming step, as shown in FIG. 10D, the upper insulating layers 43a and 43b and the emission direction specifying portion 3 (on the upper layer of the light emitting structure portion 2 are formed on the n-type semiconductor layer 23. An insulating layer 43, which is a layer for forming (see FIGS. 1 and 2), is formed. The insulating layer 43 can be formed by using a dielectric such as SiO ₂ or Al ₂ O ₃ by sputtering or CVD.
10 (d) to 10 (f) and FIGS. 11 (a) to 11 (f), the upper portion from the broken line described in the drawing is the YZ plane as in FIG. 2 (b). The cross section by (refer FIG. 2) is shown.

(N-side electrode forming step)
Next, the n-side electrode 25 that is electrically connected to the upper surface of the n-type semiconductor layer 23 is formed using a photolithography method and a lift-off method.
In this step, first, as shown in FIG. 10E, a mask 56 having an opening in a region for forming the n-side electrode 25 for patterning the insulating layer 43 is formed. The mask 56 is formed by applying a photoresist to the surface of the insulating layer 43, irradiating it with UV light in a desired shape, and developing it.

Next, as shown in FIG. 10F, the insulating layer 43 is etched using the mask 56 until the n-type semiconductor layer 23 is exposed. When SiO ₂ is used as the insulating material of the insulating layer 43, as an etching method, for example, wet etching using an aqueous solution of HF (hydrogen fluoride) or KOH (potassium hydroxide), SF ₆ , CHF ₃ gas plasma is used. The dry etching used can be used.

Next, as shown in FIG. 11A, a conductive layer 57 is formed using a conductive material such as Al or Cu. At this time, the conductive layer 57 is also formed on the mask 56.
Next, as shown in FIG. 11B, by removing the mask 56 together with the unnecessary conductive layer 57 formed on the mask 56, the conductive layer 57 is patterned and the n-side electrode 25 is formed.

(Exit direction specific part forming process)
Next, in the emission direction specifying part forming step, the insulating layer 43 is processed to form the emission direction specifying part 3.
In the emission direction specifying portion forming step, as shown in FIG. 11C, the insulating layer 43 is processed by an FIB (Focused Ion Beam) method or the like to form a columnar structure that is a structure of the emission direction specifying portion 3. Portions 31, 32 and 33 (see FIG. 2) are formed. In addition, the emission direction specifying portion 3 is formed by masking regions where the columnar portions 31, 32, 33 are formed, and performing dry etching such as RIE (reactive ion etching) or wet etching using a chemical solution on the other regions. It can also be formed. At this time, the mask formed in the region where the columnar portions 31 and 32 are formed and the mask formed in the columnar portion 33 are made different in thickness so that one of the masks can be quickly removed by etching, and the insulating layer 43 By etching a part of the columnar parts 31, 32 and the columnar part 33 can be formed to have different heights.
Further, by performing the emission direction specifying portion forming step, as shown in FIG. 11C, the insulating layer 43 remaining at the end of the upper surface of the n-type semiconductor layer 23 becomes the upper insulating layers 43a and 43b.

In the present embodiment, the emission direction specifying portion 3 is formed by processing the insulating layer 43, but is not limited to this, and is a step separate from the step of forming the upper insulating layers 43a and 43b. A semiconductor layer may be stacked and processed. Alternatively, a part of the n-type semiconductor layer 23 corresponding to the uppermost layer of the light emitting structure part 2 after being transferred to the substrate 40 may be processed to form the emission direction specifying part 3.
Note that when the emission direction specifying portion 3 is formed using a material having a refractive index smaller than that of the n-type semiconductor layer 23 made of a GaN-based semiconductor material, such as SiO ₂ , the height of the columnar portions 31, 32, 33 is high. The accuracy can be relaxed.

(Upper electrode formation process)
Next, upper electrodes 44a and 44b are formed on the upper insulating layers 43a and 44b by a lift-off method.
In this step, first, as shown in FIG. 11D, a mask 58 is formed to cover the n-side electrode 25, the emission direction specifying portion 3, and a part of the upper insulating layers 43a and 43b which are the periphery thereof. The reason why the upper insulating layers 43a and 43b are partially covered is to prevent a short circuit between the n-side electrode 25 and the upper electrodes 44a and 44b formed in this step. The mask 58 is formed by applying a photoresist to the entire surface of the n-side electrode 25, the emission direction specifying portion 3, and the upper insulating layers 43a and 43b, irradiating UV light in a desired shape, and developing. Next, as shown in FIG. 11E, a conductive layer 59 is formed on the upper insulating layers 43a and 43b and the mask 58 using a conductive material such as Al or Cu, for example, by vapor deposition. Then, as shown in FIG. 11F, by removing the mask 58 together with the unnecessary conductive layer 59 formed on the mask 54, the conductive layer 59 is patterned, and the upper electrodes 44a and 44b are formed.
The light emitting element 1 is completed through the above steps.

  As described above, the light emitting element 1 according to the embodiment of the present invention can form a light beam by the light interference effect by forming three or more columnar portions on the surface. In addition, the light emitting element 1 appropriately adjusts the arrangement of the columnar portions 31, 32, and 33 in the emission direction specifying portion 3 and the height difference between the columnar portion 33 that is the control column and the columnar portions 31 and 32 that are the waveguide columns. Thus, it is possible to form a light beam radiating in an arbitrary direction including a direction perpendicular to the display panel surface. Moreover, since the light emitting element 1 can control the direction of the light beam only by forming the columnar portions 31, 32, 33 on the surface, the structure thereof is simple. Furthermore, the lower electrodes 41a and 41b and the upper electrodes 44a and 44b are formed, and by applying a voltage between these electrodes, the surface of the light emitting element 1 on which the columnar portions 31, 32, and 33 are formed is inclined. The direction of light emission can be changed.

Second Embodiment
Next, a light emitting device according to a second embodiment of the invention will be described with reference to FIG.
The light emitting device 1A according to the second embodiment shown in FIG. 12 is a light emitting structure formed on the substrate 50 in place of the light emitting structure 2 in the light emitting device 1 according to the first embodiment shown in FIGS. 2A, an n-side electrode 25A instead of the n-side electrode 25, a p-side electrode 24A and a transparent electrode 24Aa instead of the p-side electrode 24, and the upper electrodes 44a and 44b and the upper insulating layers 43a and 44b. Instead, upper electrodes 44Aa and 44Ab and upper insulating layers 43Aa and 44Ab are provided.
In the light emitting element 1A according to the second embodiment, the light emitting structure 2A has a configuration in which an n-type semiconductor layer 23, a light emitting layer 22, and a p-type semiconductor layer 21 are stacked on a substrate 50, which is a growth substrate of a semiconductor layer. ing. That is, unlike the first embodiment, the semiconductor stacked body is used without being inverted and without peeling off the substrate 50.

For this purpose, the lower electrodes 41a and 42b are provided on the lower surface of the substrate 50 via the lower insulating layers 42a and 42b. The n-side electrode 25 </ b> A is provided on a part of the side surface of the n-type semiconductor layer 23. In the case where an insulating substrate such as sapphire is used as the substrate 5, the lower insulating layers 42a and 42b can be omitted.
The p-side electrode 24A is provided on the upper surface of the p-type semiconductor layer 21 via the transparent electrode 24Aa. The transparent electrode 24Aa is provided in a region where the emission direction specifying portion 3 is provided in a plan view, and diffuses a current supplied from the p-side electrode 24A made of a good electric conductor such as a metal into the p-type semiconductor layer 21 so that the emission direction This is a current diffusion layer for causing the light emitting layer 22 immediately below the specific portion 3 to emit light satisfactorily. The transparent electrode 24Aa can be formed using a light-transmitting conductive material such as ITO.
The transparent electrode 24Aa is provided on almost the entire upper surface of the p-type semiconductor layer 21, and the p-side electrode 24A is a plan view of the transparent electrode 24Aa in the region excluding the region where the structure of the emission direction specifying portion 3 is provided. You may make it provide in the whole upper surface.

The upper electrodes 44Aa and 44Ab are formed in a strip shape extending in the Y-axis direction on the left end and the right end of the upper surface of the light emitting structure portion 2A via the upper insulating layers 43Aa and 43Ab. That is, the upper electrodes 44Aa and 44Ab are disposed so that the entire surfaces thereof face the lower electrodes 41a and 41b. For this reason, an electric field can be effectively applied to the semiconductor layer of the light emitting structure 2.
The upper electrodes 44Aa and 44Ab extend in the X-axis direction to the front end and the rear end of the upper surface of the light emitting structure portion 2A, similarly to the upper electrodes 44a and 44b in the first embodiment shown in FIGS. It may be provided as follows. Further, the upper electrodes 44a and 44b in the first embodiment may be provided at the left end and the right end of the upper surface of the light emitting structure 2 so as to extend in the Y-axis direction, similarly to the upper electrodes 44Aa and 44Ab in the present embodiment. Good.
Since other configurations are the same as those of the light-emitting element 1 according to the first embodiment, the same reference numerals are given and description thereof is omitted.

Further, when the same hexagonal sapphire or GaN-based semiconductor as the GaN-type semiconductor crystal constituting the light emitting structure 2A is used as the substrate 50, the substrate 50 also expands and contracts similarly to the light emitting structure 2 due to the inverse piezoelectric effect. This can contribute to modulation in the emission direction.
In order to effectively apply an electric field to a semiconductor layer that can obtain a large reverse piezoelectric effect, the thinner the substrate 50 is, the better. Therefore, in the manufacturing process, it is preferable that the back surface of the substrate 50 is polished and thinned after the semiconductor layer is grown.
The light emitting element 1A according to the second embodiment is a method of manufacturing the light emitting element 1 according to the first embodiment. In the bonding process, the light emitting structure 2A is bonded to the substrate 40 on the substrate 50 side, and the substrate 50 is peeled off. Do not. Since the other steps are the same as those in the first embodiment, description of the manufacturing method is omitted.

Next, the operation of the light emitting device 1A according to the second embodiment will be described.
In the light emitting element 1A according to the second embodiment, by supplying power between the n-side electrode 25A and the p-side electrode 24A, the light emitting layer 22 of the light emitting structure 2A emits light, and the light enters the emission direction specifying unit 3 Is done. The light incident on the emission direction specifying unit 3 from the light emitting structure 2A is in a direction specified by the configuration of the columnar parts 31, 32, 33 (see FIGS. 1 and 2) that are structures of the emission direction specifying unit 3. Emitted.
Further, when a voltage is applied between the lower electrodes 41a and 41b and the upper electrodes 44Aa and 44Ab, the semiconductor layer constituting the light emitting structure 2A is deformed by the inverse piezoelectric effect. And according to the applied voltage, the upper surface of 2 A of light emission structure parts inclines, and the output direction specific | specification part 3 inclines in response to this. At this time, the direction of the light beam emitted from the emission direction specifying unit 3 is modulated by the amount by which the emission direction specifying unit 3 is inclined.

<Third Embodiment>
Next, with reference to FIG.13 and FIG.14, the light emitting element which concerns on 3rd Embodiment is demonstrated.
As shown in FIGS. 13 and 14, the light emitting device 1B according to the third embodiment is different from the light emitting device 1 according to the first embodiment shown in FIGS. The direction specifying unit 3B is provided. About the structure similar to the light emitting element 1 which concerns on 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted suitably.
In FIG. 14B, the part below the break line shows a cross section taken along line AA in FIG. 14A, and the part above the break line shows a cross section taken along line BB in FIG.

  As shown in FIGS. 13 and 14, the light emitting element 1 </ b> B has three or more holes (columnar recesses) as the structure 3 </ b> Ba so as to surround a predetermined region on the flat upper surface 30 </ b> Ba, and has at least one hole. The depth is different from others, and it is characterized in that light is emitted from all these holes. In the following description, it is assumed that the light emitting element 1B has three holes 31B, 32B, and 33B, and the hole 33B is shallower than the holes 31B and 32B as an example.

The light emitting element 1B according to the present embodiment has three columnar recesses (columnar recesses) 31B, 32B, and 33B as the structure 3Ba as the emission direction specifying portion 3B. The holes 31 </ b> B, 32 </ b> B, 33 </ b> B are structures that replace the columnar parts 31, 32, 33 of the emission direction specifying part 3 in the first embodiment. As described above, the depth of the bottom surface 33Ba of the hole 33B is smaller than the depth of the bottom surfaces 31Ba and 32Ba of the holes 31B and 32B with respect to the upper surface 30Ba of the emission direction specifying portion 3B.
In the present embodiment, the shape of the holes 31B, 32B, and 33B is a columnar shape with a circular cross section, but is not limited to this, and the cross section is a columnar shape with another shape such as a polygon or an ellipse. You can also

The light emitted from the light emitting region 22a of the light emitting structure 2 enters the holes 31B, 32B, and 33B, and exits from the bottom surfaces 31Ba, 32Ba, and 33Ba of the holes 31B, 32B, and 33B, and these emitted lights interfere with each other. A light beam having intensity in a direction corresponding to the arrangement of the holes 31B, 32B, 33B is emitted from the emission direction specifying unit 3B. The emission direction specifying portion 3B is configured such that the depths of the holes 31B, 32B, and 33B are different from each other, and the phase difference between the light emitted from the bottom surfaces 31Ba, 32Ba, and 33Ba of the holes 31B, 32B, and 33B due to the difference in depth. It will cause.
The principle of specifying the light emission direction by the emission direction specifying unit 3B is the same as that of the emission direction specifying unit 3 in the first embodiment, and thus the description thereof is omitted. The operation of the light emitting structure 2 is also the same as that of the light emitting structure 2 in the first embodiment, and a description thereof will be omitted.

Further, the preferable relationship between the light emitting region 22a in the plan view and the arrangement of the holes 31B, 32B, and 33B is the same as that of the light emitting region 22a and the columnar portions 31, 32, and 33 in the light emitting element 1 according to the first embodiment. . That is, if the area of the light emitting region 22a is SL, the area of the holes 31B, 32B, 33B is SP, and the area of the circumscribed circle including the holes 31B, 32B, 33B is SO, the clarity of the light beam is improved and the direction control of the light beam is performed. In order to achieve both improvement in the arbitraryness of the above, it is desirable that the relationship of the above-described formula (7) is satisfied.
However, in Formula (7), N shall show the installation number of a hole, and is an integer greater than or equal to 3.

  In addition, the light emitting device 1B according to the present embodiment is different from the method of manufacturing the light emitting device 1 according to the first embodiment in that the holes 31B, 31B, It can be manufactured by processing the insulating layer 43 (see FIG. 11C) so as to form 32B and 33B. The other steps are the same as those in the first embodiment, and thus description thereof is omitted.

<Fourth embodiment>
[Concept of IP stereoscopic display]
Next, with reference to FIG. 15, an IP stereoscopic display (stereoscopic image display device) using the light emitting element of the present invention will be described as a fourth embodiment.
As shown in FIG. 15A and FIG. 15B, the IP stereoscopic display according to the present embodiment is an IP display by arranging a large number of light emitting elements 1 according to the first embodiment on the substrate 11. A certain IP stereoscopic display 100 is configured. Although illustration is omitted, the IP stereoscopic imaging apparatus corresponding to the IP stereoscopic display 100 may acquire an element image group in which a subject such as a cylinder or a cube illustrated in FIG. Although it is convenient for displaying (reproducing) a three-dimensional object, it is created by multi-view video or a three-dimensional model rendering process, and the data is configured according to the arrangement of the light emitting elements 1 in the IP three-dimensional display 100. You may use.

In a conventional IP display, for example, an element image group is displayed on a liquid crystal panel, and each element image is simply projected through each element lens of an element lens array similar to that at the time of photographing and accumulated. The image can be observed as a stereoscopic reproduction image corresponding to the subject.
In the case of the IP stereoscopic display 100 according to the present invention, a plurality of light emitting elements 1 arranged densely form an element image as a unit pixel group, and correspond to individual element lenses of a conventional IP stereoscopic display. The corresponding element pixel groups (one unit structure) are arranged side by side.

  Here, the element image is an image projected in correspondence with one element lens in a conventional IP system display using an element lens array which is an assembly of minute optical lenses. In a conventional IP display, light rays emitted from each pixel of the element pixel group constituting one element image are emitted in a direction connecting each pixel position and the center of the element lens. For this reason, the light rays emitted from each pixel constituting one set of element pixel groups are emitted in different directions.

In the present invention, in place of the element lens in the conventional IP display, the emission direction is set for each light emitting element 1 used as a pixel. For this purpose, the IP stereoscopic display 100 shown in FIG. 15A has the columnar portions 31, 32, 33 (as the emission direction specifying portion 3 so that each light emitting element 1 emits a light beam in a predetermined direction. Structures such as FIG. 1 and FIG. 2) are installed.
In addition, as described above, the light emitting element 1 of the present invention can modulate the emission direction by applying a voltage between the lower electrodes 41a and 41b and the upper electrodes 44a and 44b (see FIGS. 1 and 2). It is configured as follows.
As described above, it is possible to provide the IP three-dimensional display 100 by arranging a large number of the light emitting elements 1 on the substrate 11. In this case, the light emitting elements 1 themselves are inclined with respect to the substrate 11. By doing so, the emission direction can be set in a wider range.

Here, one set of element pixel groups indicates a set of pixels that emit light rays corresponding to all directions at a certain pixel position. For example, if the number of directions of light emitted from each element pixel group in the IP stereoscopic display 100 is 60 in the horizontal (horizontal) direction and 60 in the vertical (vertical) direction, the total number of directions is 60 × 60 = 3600. The corresponding light beam is emitted.
When one light emitting element 1 of the present invention can emit light in two directions by modulating the emission direction, it emits light in 3600 directions per set of element pixel groups. In addition, by providing 3600/2 = 1800 light-emitting elements 1, the IP stereoscopic display 100 can be realized. When one light-emitting element 1 can be modulated in more directions, the IP stereoscopic display 100 can be realized by including the number of light-emitting elements 1 obtained by dividing the total number of light emission directions by the modulation number. .

FIG. 15B shows an example of the state of light rays emitted from the IP stereoscopic display 100 in the direction of the observation point at a certain observation point. At the observation point 1, light rays (solid arrow lines) emitted in the direction of the observation point 1 in each element pixel group are accumulated, and an image such as a cylinder or a cube can be observed, for example. At observation point 2 near observation point 1, light rays (dotted arrow lines) modulated and emitted in other directions from light emitting element 1 that emits light rays in the direction of observation point 1 are accumulated. An image corresponding to the direction is observed.
In this way, by modulating the emission direction of the light emitting element 1, it is possible to project a stereoscopic image by the light emitting elements 1 that are fewer than the number of emission directions.

  In addition, since the light emitting elements 1 and 1 of the IP stereoscopic display 100, that is, between the pixels, are arranged with a distance equal to or longer than the coherence length, an interference wave is generated between lights emitted from different pixels. It will never be done. Therefore, for example, the intensity of the light synthesized from the light emitted from the three pixels is simply an addition of the intensity of each light emitted from the three pixels. That is, the intensity of the light synthesized between the pixels is obtained by an operation corresponding to the first term and the second term of Equation (17) when the three pixels are regarded as three wave sources. .

  A display panel in which a large number of light emitting elements 1 having such a fine structure are arranged has the same function as a device in which a lens plate and a light emitting surface are joined in the prior art. In the IP stereoscopic display 100 created in this way, the resolution of the stereoscopic display depends only on the definition of the light emitting element 1, and image blur due to insufficient resolution of the optical system does not occur. Further, the maximum value of the viewing zone angle in the IP display using the light emitting element 1 depends only on the maximum value of the angle (control angle) of the radiated light with respect to the direction perpendicular to the element surface, and the resolution and the viewing zone angle are determined. It is possible to improve independently.

[Configuration of IP stereoscopic display]
Next, the configuration of the IP stereoscopic display 100 according to the present embodiment will be described in detail with reference to FIG.
As shown in FIG. 16, the IP stereoscopic display 100 according to the present embodiment includes a display panel (display element) 10, a light emission control unit 60, and an emission direction control unit 63. The IP stereoscopic display 100 is a stereoscopic image display device that displays an image signal input via the external display control unit 70 on the display panel 10 as an IP stereoscopic image.

The display panel (display element) 10 is provided in two dimensions (3 × 3 in FIG. 16) on the substrate 11 with the light emitting element 1 as a pixel, and is a display element that displays an IP stereoscopic image. It is. The substrate 11 is an alternative to the substrate 40 in FIGS. 1 and 2, and the light emitting elements 1 are arranged on the common substrate 11.
On the surface of the substrate 11, for each of the light emitting elements 1 arranged in the column direction (vertical direction), the wiring electrode 12 electrically connected to the p-side electrode 24 and the wiring electrode electrically connected to the lower electrode 41a An electrode 13a and a wiring electrode 13b that is electrically connected to the lower electrode 41b are provided. The p-side electrode 24, the lower electrode 41a, and the lower electrode 41b of the light emitting elements 1 belonging to the same column are electrically connected via the wiring electrode 12, the wiring electrode 13a, and the wiring electrode 13b, respectively.
Further, in the light emitting elements 1 arranged in the same row (lateral direction), the n-side electrodes 25 are electrically connected to each other by the wire 15, the upper electrodes 44 a are electrically connected to each other by the wire 14 a, and the upper electrode 44b is electrically connected to each other by a wire 14b.
For example, gold wires or carbon tape can be used as the wires 14a, 14b, and 15.
Moreover, the connection between these electrodes is not limited to a wire or a tape, but can also be performed using a metal wiring pattern made of Al, Cu or the like formed on a multilayer wiring board.

  Further, for each column, an image signal is input as a column selection signal from the column selection unit 62 to the p-side electrode 24 via the wiring electrode 12, and for each row, the right side light emission of each row is emitted to the n-side electrode 25. A scanning signal is input as a row selection signal from the row selection unit 61 via the n-side electrode 25 of the element 1. In the display panel 10, the n-side electrode 25 to which the row selection signal is input and the light emitting element 1 connected to the wiring electrode 12 to which the column selection signal is input are selected, and the light emission time (light emission / non-light emission) is selected. Be controlled.

In addition, a signal for controlling the emission direction is input from the lower electrode control unit 64 to the lower electrode 41a of each light emitting element 1 via the wiring electrode 13a, and the wiring electrode 13b is connected to the lower electrode 41b. Then, a signal for controlling the emission direction is input from the lower electrode control unit 64.
In addition, a signal for controlling the emission direction is input to the upper electrode 44a of each light emitting element 1 from the upper electrode control unit 65 via the upper electrode 44a of the leftmost light emitting element 1, and the upper electrode 44b includes A signal for controlling the emission direction is input from the upper electrode control unit 65 via the upper electrode 44b of the light emitting element 1 at the left end. In the display panel 10, the direction of the light beam emitted from the light emitting element 1 is modulated left and right in accordance with the voltage applied between the lower electrodes 41a and 41b and the upper electrodes 44a and 44b.

The light emission control unit 60 includes a row selection unit 61 and a column selection unit 62, and the light emitting elements 1 arranged as pixels on the display panel 10 based on an image signal input via the external display control unit 70. The light emission time is controlled by selecting sequentially.
The row selection unit 61 receives a scanning signal synchronized with the row of the image signal from the display control unit 70, and outputs it to the n-side electrode (row electrode) 25 corresponding to the row. A row to which a row selection signal having a predetermined potential (for example, 0 V) indicating selection is input is a target whose light emission time is controlled.
The column selection unit 62 receives the image signal from the display control unit 70, divides it into image signals corresponding to each column, and uses the image signals divided into the wiring electrodes 12 corresponding to each column in parallel as column selection signals. Output.
At this time, the column selection unit 62 switches the image signals corresponding to the two directions in a time division manner as column selection signals in synchronization with the timing when the emission direction control unit 63 changes the emission direction of the light emitting element 1. Output.

  The light emitting element 1 emits light during a period in which a column selection signal having a predetermined level potential (for example, 5 V) indicating that it has been selected is input. Therefore, the light-emitting element 1 emits light during a period in which the row selection signal is input and a column selection signal of a predetermined level is input, and the light-emitting element 1 does not emit light in other periods. By increasing / decreasing the period of the predetermined level in the column selection signal according to the corresponding pixel data in the image signal, the luminance displayed as the pixel of the light emitting element 1 can be modulated.

  The emission direction control unit 63 includes a lower electrode control unit 64 and an upper electrode control unit 65, and controls the voltage applied between the lower electrodes 41 a and 41 b and the upper electrodes 44 a and 44 b to control the light emitting elements 1. The emission direction is modulated in a direction inclined to the left or right. At this time, the emission direction control unit 63 synchronizes with the switching timing of the image signals for the two directions output from the light emission control unit 60 to each pixel based on the synchronization signal input from the display control unit 70. Thus, the voltage applied between the lower electrodes 41a and 41b and the upper electrodes 44a and 44b is controlled so that the emission direction is switched.

The lower electrode control unit 64 is connected to the lower electrode 41a with respect to the wiring electrode 13a electrically connected to the lower electrode 41a of each light emitting element 1 and the wiring electrode 13b electrically connected to the lower electrode 41b. A predetermined level signal (for example, 0 V) is output so that a predetermined voltage is obtained between the upper electrode 44a and between the lower electrode 41b and the upper electrode 44b.
The upper electrode control unit 65 has a predetermined voltage between the lower electrode 41a and the upper electrode 44a and between the lower electrode 41b and the upper electrode 44b with respect to the upper electrode 44a and the upper electrode 44b of each light emitting element 1. A signal of a predetermined level (for example, 4V) is output so that

For example, the potential of the lower electrode 41a is set to 0V, the upper electrode 44a is set to 4V, and no voltage is applied between the lower electrode 41b and the upper electrode 44b, whereby the light emitting structure portion 2 (see FIG. 2)), a downward electric field (−Z axis direction) is generated on the paper surface, and the semiconductor layer is stretched. As a result, the emission direction specifying unit 3 is inclined upward to the left, and the emission direction of the light emitting element 1 is modulated rightward.
Further, the potential of the lower electrode electrode 41b is set to 0V, the upper electrode 44b is set to 4V, and no voltage is applied between the lower electrode 41a and the upper electrode 44a, so that the light emitting structure portion 2 (see FIG. 2)), a downward electric field (−Z axis direction) is generated on the paper surface, and the semiconductor layer is stretched. As a result, the emission direction specifying unit 3 is tilted upward to the right, so that the emission direction of the light emitting element 1 is modulated leftward.

  The display control unit 70 inputs an image signal, outputs the input image signal to the column selection unit 62, and outputs a scanning signal synchronized with the image signal to the row selection unit 61 as a row selection signal. . The display control unit 70 also outputs a synchronization signal such as a pixel clock to the emission direction control unit 63, the image signal display switching timing in the two directions in the light emission control unit 60, and the emission direction control unit 63. The output direction switching timing is synchronized.

[Operation of IP stereoscopic display]
Next, the operation of the IP stereoscopic display 100 according to the present embodiment will be described with reference to FIG.
The IP stereoscopic display 100 receives a scanning signal synchronized with the row of the image signal together with the image signal from the display control unit 70. In the IP stereoscopic display 100, the row selection unit 61 sequentially selects the n-side electrode 25 and outputs the scanning signal input from the display control unit 70 as a row selection signal. In parallel with this, the IP stereoscopic display 100 divides the image signal of one row input from the display control unit 70 into the data signals corresponding to the columns by the column selection unit 62, and the divided data signals are respectively Output to the wiring electrode 12 in the corresponding column. At this time, the IP stereoscopic display 100 receives image signals corresponding to two directions for one column by the column selection unit 62, converts the image signals into data signals corresponding to these two directions, and performs time division. Output to the wiring electrode 12.
In the display panel 10 of the IP stereoscopic display 100, the light emitting time of each light emitting element 1 belonging to the row selected by the row selecting unit 61 is controlled according to the data signal input from the column selecting unit 62.
In addition, the IP stereoscopic display 100 synchronizes with the timing of switching the output of the data signal corresponding to the two directions by the column selection unit 62, and the emission direction control unit 63 changes the emission direction of the light emitting element 1 to a predetermined left and right direction. The voltage applied between the lower electrodes 41a and 41b and the upper electrodes 44a and 44b is switched so as to switch from one to the other.
Thereby, each light emitting element 1 can display the pixel of the image corresponding to two directions.

When the IP stereoscopic display 100 receives a scanning signal for the next row from the display control unit 70, the IP stereoscopic display 100 outputs a row selection signal for selecting the next row by the row selection unit 61 to the corresponding n-side electrode 25. In parallel with this, the IP stereoscopic display 100 uses the column selection unit 62 to divide the image signal of the next row input from the display control unit 70 into data signals corresponding to the columns, Each is output to the wiring electrode 12 in the corresponding column. At this time, the IP stereoscopic display 100 receives the image signals corresponding to the two directions for one column by the column selection unit 62, converts the image signals into the data signals corresponding to the two directions, and performs wiring in a time division manner. Output to the working electrode 12. Thereby, the light emission time of the light emitting elements 1 belonging to the next row is controlled.
Hereinafter, the IP stereoscopic display 100 controls the light emission times of the light emitting elements 1 belonging to the selected row by sequentially changing the selected row. By repeating this, the IP stereoscopic display 100 can project an image signal input via the display control unit 70 from the display panel 10 as a stereoscopic image.

In the present embodiment, the light-emitting element 1 according to the first embodiment is used as a pixel. However, the light-emitting element 1A according to the second embodiment, the light-emitting element 1B according to the third embodiment, or a light-emitting element obtained by modifying these elements is used. It can also be used as a pixel.
Further, the emission direction to be modulated is not limited to the horizontal direction, and may be the vertical direction or the horizontal direction and the vertical direction. Also, the number of modulations can be 3 or more.
Furthermore, by changing the voltage applied between the lower electrodes 41 a and 41 b and the upper electrodes 44 a and 44 b for each light emitting element 1, the modulation degree (tilt angle) in the emission direction differs for each light emitting element 1. Also good. Further, by changing the thickness of the lower insulating layers 42a and 42b and / or the upper insulating layers 43a and 43b for each light emitting element 1 and changing the electric field strength applied to the light emitting structure 2, the applied voltage is constant. The degree of modulation (tilt angle) may be different for each.

[Possibility of using light emitting elements]
The light-emitting elements 1, 1A, 1B of the present invention can be applied to general devices that require light beam shaping and direction control. For example, it is suitable for a light source for a projector, a connector used for spatial light interconnection, an illumination light source that does not require a diffuser.

DESCRIPTION OF SYMBOLS 1, 1A, 1B Light emitting element 2, 2A Light emission structure part 3, 3B Output direction specific | specification part 3a, 3Ba Structure 10 Display panel 11 Substrate 12 Wiring electrode 13a, 13b Wiring electrode 14a, 14b Wire 15 Wire 21 P-type semiconductor Layer (first semiconductor layer, second semiconductor layer)
22 light emitting layer 22a light emitting region 23 n-type semiconductor layer (second semiconductor layer, first semiconductor layer)
24 p-side electrode (first electrode, second electrode)
25, 25A, 25C n-side electrode (second electrode, first electrode)
31, 32 Columnar part 33 Columnar part 31a, 32a, 33a Upper surface 34 Structure part formation layer 30Ba Upper surface 31B, 32B Hole (columnar recessed part)
33B hole (columnar recess)
31Ba, 32Ba, 33Ba Bottom 40 Substrate 40a Base 40b Bonding layer 41a, 41b Lower electrode (electrode)
42 Insulating layer 42a, 42b Lower insulating layer (insulating layer)
43 Insulating layer 43a, 43b, 43Aa, 43Ab Upper insulating layer (insulating layer)
44a, 44b, 44Aa, 44Ab Upper electrode (electrode)
50 substrate 51 peeling layer 52, 54, 56, 58 mask 53, 55, 57, 59 conductive layer 60 light emission control unit 61 row selection unit 62 column selection unit 63 emission direction control unit 64 lower electrode control unit 65 upper electrode control unit 70 Display control unit 100 IP stereoscopic display (stereoscopic image display device)

Claims (6)

A light emitting device having a light emitting structure including a semiconductor laminate in which a first semiconductor layer, a light emitting layer, and a second semiconductor layer are laminated in this order,
An emission direction specifying part having a structure for specifying the emission direction of the light emitted from the light emitting layer from the light emitting element on a part of the second semiconductor layer or the upper surface of the second semiconductor layer;
The lower electrode and the upper electrode are provided at the end portions in plan view of the upper surface and the lower surface of the light emitting structure portion, respectively, with an insulating layer interposed therebetween so that at least a part thereof faces each other.
A light emitting element, wherein a voltage is applied between the lower electrode and the upper electrode to deform the light emitting structure and change the emission direction. Laminate of the semiconductor is configured formula from _{In 1-x-y Ga x} Al y N ( where, 0 ≦ x ≦ 1,0 ≦ y ≦ 1,0 ≦ x + y ≦ 1) semiconductor material represented by The light-emitting element according to claim 1.   The light emitting device according to claim 2, wherein the light emitting layer has a quantum well structure. The structure includes N (N is an integer of 3 or more) columnar portions that emit light from the emission surface of the stigma.
The N columnar portions are arranged in a ring shape within a range in which light emitted from the light emitting layer can interfere in a plan view, and at least one of the N columnar portions has a height other than that. The light-emitting element according to claim 1, wherein the light-emitting element has a height different from that of the column. The structure is composed of N (N is an integer of 3 or more) columnar recesses recessed in a columnar shape from the upper surface,
The N columnar recesses are provided in a ring shape within a range in which light emitted from the light emitting layer can interfere in a plan view, and the depth of at least one columnar recess among the N columnar recesses is The light emitting device according to any one of claims 1 to 3, wherein the light emitting device has a depth different from that of the other columnar recesses. An integral photography type stereoscopic image display device comprising a display panel provided with the light emitting elements according to any one of claims 1 to 5 as pixels arranged in a two-dimensional array on a substrate. Because
A light emission control unit that controls time-division switching and output of image signals corresponding to two or more emission directions displayed by the stereoscopic image display device to the pixels, and controls light emission and non-light emission of the pixels;
An emission direction control unit that modulates an emission direction of the pixel in synchronization with a timing of switching an image signal output to the pixel corresponding to the two or more emission directions. 3D image display device.

Images