JP6393078B2 - Light emitting element - Google Patents

Description

  The present invention relates to a light-emitting element that can be used in a display device for stereoscopic images and the like.

  Current stereoscopic display technology can be broadly classified into two-lens type, multi-view type, volume display type, and aerial image reproduction type. Here, the aerial image reproduction type is currently being developed with the aim of satisfying all four visual functions of binocular parallax, convergence, focus adjustment, and motion parallax. This aerial image reproduction type is a method that reproduces the light from the subject itself, and does not require special glasses for stereoscopic observation. Since this type of stereoscopic display may be able to use all of the above four visual functions, it can be a human-friendly stereoscopic video display device that does not cause eye fatigue.

 Typical methods in this spatial image reproduction type stereoscopic display technology include holography, parallax stereogram, lenticular sheet, integral photography (hereinafter referred to as IP), and the like (for example, see Non-Patent Document 1). . 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. Among them, 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 2). ).

  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 obtains partial information corresponding to the position of the observer from one element image corresponding to one element lens, and observes a stereoscopic image in which these element images are arranged by the number of element lenses. That is, 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 (see, for example, Non-Patent Document 3).

  However, even if the definition of the light emitting element and the optical element is increased, an optical system using a lens has performance limits that cannot be removed in principle, such as the diffraction limit and focal length of the lens. 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.

  In order to solve such a problem, Patent Document 1 proposes a light-emitting element that enables light beam shaping and deflection control by a single element using a columnar structure on the element surface. In the light emitting element proposed in Patent Document 1, the light emitting part is formed in a region including directly under the columnar structure part, and the area of the cross section of the light emitting part is equal to or less than the area of the circumscribed circle including all the columnar structures, And it is comprised so that it may become more than the sum total of the area of the cross section of all the columnar structures. By providing such a configuration, most of the light emitted from the light emitting unit can be incident on each columnar structure, and the element surface (especially the buffer layer) other than the emission surface of each columnar structure. Leakage from the upper surface) can be suppressed.

  Further, in Non-Patent Document 4, as in Patent Document 1, a light-emitting element that enables light beam shaping and deflection control by a single element by a columnar structure on the surface of the element, and a columnar structure arranged in an annular shape. In addition, a light emitting element in which the light emitting portion is formed in an annular shape has been proposed. By providing such a configuration, most of the light emitted from the light emitting unit can be incident on each columnar structure.

JP 2013-175536 A

Yasuo Taki et al., "Image Engineering", Corona, 1972, pp.277-326 “The Journal of the Institute of Electrical, Information and Communication Engineers”, May 2010, Vol.93, No.5, pp.372-381 Japan Association for Mechanical Systems Promotion and Japan Optical Industry Technology Promotion Association, “Survey Report on Formation of Spatial Image that Enables Natural Stereoscopic Viewing—Abstract”, System Technology Development Survey 19-R-5, pp .14-16, March 2008 2nd International Conference on Photonics, Optics and Laser Technology (PHOTOPICS 2014), 25, pp.163-169, January 8, 2014

  However, the light-emitting elements proposed in Patent Document 1 and Non-Patent Document 4 have to form a light emitting part in a circular shape or an annular shape so that the cross section includes a circumscribed circle including all columnar structures, It is not easy to control the light emitting part made of a semiconductor in such a shape.

  This invention is made | formed in view of this point, and makes it a subject to provide the light emitting element which can obtain the light beam deflection characteristic equivalent to it easily, without controlling the shape of a light emission part.

Light-emitting device according to the present invention in order to solve the above problems, the light-emitting layer and the buffer layer formed on the upper side of the light-emitting layer, upper side definitive central formed on a portion dielectric of the buffer layer And at least two pedestals formed above the pedestal, and the height of at least one column is different from the height of the other columns, and the light generated in the light emitting layer is emitted from the stigma. A columnar part and a light shielding film formed on the outside of a circumscribed circle surrounding all the columnar parts in plan view, and the pedestal part is formed in a range of the circumscribed circle in plan view, and the light shielding film is is formed so as to cover the outside of the area surface of the side surface and the circumscribed circle of the pedestal portion, the buffer layer has a structure ing a dielectric.

  In order to solve the above problems, a light emitting device according to the present invention includes a light emitting layer, a buffer layer formed above the light emitting layer, a dielectric layer formed above the buffer layer, and the dielectric layer. A pedestal portion made of a dielectric formed on the body layer, and at least two pedestals formed above the pedestal portion, and the height of at least one column is different from the height of the other columns; A columnar portion that radiates the generated light from the stigma and a light shielding film formed outside a circumscribed circle that surrounds all the columnar portions in plan view, and the dielectric layer is formed in a thickness direction from the upper surface. A first light shielding member that has a circular concave portion in plan view, and has a convex portion as the pedestal portion on the bottom surface of the concave portion, and the light shielding film covers a side surface of the pedestal portion, a bottom surface and an inner side surface of the concave portion. Covering the film and the top surface of the dielectric layer outside the recess. A second light-shielding film, was composed of configuration.

  According to the invention of the present invention, since the portion other than the region where the columnar portion is formed is covered with the light shielding film, the stray light leaking from the element surface (especially the buffer layer) other than the emission surface can be suppressed with a simple configuration. It is possible to improve the light deflection characteristics by preventing excessive interference between the light leaking from the element surface and the light emitted from the respective columnar portions.

It is a perspective view which shows typically the structure of the light emitting element which concerns on 1st Embodiment of this invention. It is sectional drawing which shows typically the structure of the light emitting element which concerns on 1st Embodiment of this invention. It is a top view which shows typically the structure of the light emitting element which concerns on 1st Embodiment of this invention. (A)-(e) is sectional drawing which shows typically the manufacturing process of the light emitting element which concerns on 1st Embodiment of this invention. It is a perspective view which shows typically the structure of the light emitting element which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows typically the structure of the light emitting element which concerns on 2nd Embodiment of this invention. It is a top view which shows typically the structure of the light emitting element which concerns on 2nd Embodiment of this invention. (A)-(e) is sectional drawing which shows typically the manufacturing process of the light emitting element which concerns on 2nd Embodiment of this invention. It is explanatory drawing for demonstrating the performance of the light emitting element which concerns on this invention, Comprising: (a) is sectional drawing which shows the structure of the light emitting element which concerns on the comparative example of this invention, (b) is a comparative example of this invention It is a figure which shows the beam pattern of xy plane of the light emitting element which concerns on. It is explanatory drawing for demonstrating the performance of the light emitting element which concerns on this invention, Comprising: (a) is sectional drawing which shows the structure of the light emitting element which concerns on the Example of this invention, (b) is an Example of this invention. It is a figure which shows the beam pattern of xy plane of the light emitting element which concerns on. It is explanatory drawing for demonstrating the performance of the light emitting element which concerns on this invention, Comprising: (a) is a perspective view which shows the structure of the light emitting element which concerns on the comparative example of this invention, (b) is a comparative example of this invention It is a figure which shows the beam pattern of xy plane of the light emitting element which concerns on. It is explanatory drawing for demonstrating the performance of the light emitting element which concerns on this invention, Comprising: (a) is sectional drawing which shows the structure of the light emitting element which concerns on the Example of this invention, (b) is an Example of this invention. It is a figure which shows the beam pattern of xy plane of the light emitting element which concerns on.

  Hereinafter, light-emitting elements according to embodiments of the present invention will be described with reference to the drawings. In addition, the size, positional relationship, and the like of members shown in each drawing may be exaggerated for convenience of explanation. Furthermore, in the following description, the same name and reference sign indicate the same or the same members in principle, and the detailed description will be omitted as appropriate.

<First Embodiment>
[Configuration of light emitting element]
The configuration of the light-emitting element 1 according to the first embodiment of the present invention will be described with reference to FIGS. The light-emitting element 1 is an element that emits light with high directivity, and is a light-directional element that emits light in a specific direction. Examples of the light emitting element 1 include a solid light emitting element having a flat surface such as an LED element.

  As shown in FIG. 1, the light emitting element 1 has a structure in which a semiconductor layer 10, a light emitting layer 20, a buffer layer 30, and a light shielding film 60 are stacked. Further, as shown in FIG. 1, the light emitting element 1 has an opening o at the center of the light shielding film 60, and a pedestal 41 is disposed in the opening o. A plurality of columnar parts 51, 52, 53 are formed above the pedestal part 41.

  Although not shown in FIG. 1, the electrode for causing the light emitting layer 20 to emit light is provided with a step between the semiconductor layer 10 and the buffer layer 30, for example, similarly to a general LED element, It can be provided by forming an ohmic contact in a portion drawn from the step. Moreover, a general metal electrode can be used as an electrode material.

  The semiconductor layer 10 is an n-type semiconductor layer that injects electrons into the light emitting layer 20. The semiconductor layer 10 may have a structure in which, for example, an n-type GaN layer and an n-type GaN / InGaN barrier layer are stacked in this order from the substrate side (not shown).

  The light emitting layer 20 emits energy generated by recombination of electrons and holes injected from the semiconductor layer 10 and the buffer layer 30 as light. The light emitting layer 20 is formed by adding an impurity such as In to the junction between the semiconductor layer 10 and the buffer layer 30. When the light emitting element 1 is a blue light emitting element, it is formed as, for example, an InGaN quantum well layer. The

  As shown in FIGS. 1 and 2, the light emitting layer 20 is formed between the semiconductor layer 10 and the buffer layer 30. The light emitting layer 20 is formed on the entire surface of the upper region of the semiconductor layer 10 (the lower region of the buffer layer 30). That is, the light emitting layer 20 has the same area as the semiconductor layer 10 and the buffer layer 30.

  The buffer layer 30 is a p-type semiconductor layer that injects holes into the light emitting layer 20. The buffer layer 30 may have a structure in which, for example, a p-type GaN / InGaN barrier layer and a p-type GaN layer are stacked in order from the light emitting layer 20 side. Further, as shown in FIGS. 1 and 2, the buffer layer 30 has a flat surface.

The pedestal portion 41 is for arranging the columnar portions 51, 52, 53. The pedestal portion 41 is made of a dielectric material that transmits light, and can have a structure in which thin films such as SiO ₂ and Al ₂ O ₃ are laminated. The pedestal 41 can be made of a polymer material when formed by nanoimprint.

  As shown in FIG. 2, the pedestal portion 41 is formed in a central partial region on the upper side of the buffer layer 30. Specifically, as shown in FIG. 3, the pedestal portion 41 is formed in a range of a circumscribed circle c1 that surrounds all the columnar portions 51, 52, and 53 in a plan view. That is, as shown in FIG. 3, the pedestal portion 41 has a circular planar shape that matches the shape of the circumscribed circle c <b> 1, and is formed in a disc shape as a whole. A light shielding film 60 is formed around the pedestal portion 41 so as to cover all the side surfaces of the pedestal portion 41. In other words, the pedestal 41 is formed in the opening o formed at the center of the light shielding film 60.

  Here, it is preferable that the pedestal portion 41 has the same size as the circumscribed circle c1 or a size within a predetermined range larger than the circumscribed circle c1. As shown in FIG. 3, the diameter of the pedestal 41 is preferably in the range of D to 1.05 D, for example, where D is the diameter of the circumscribed circle c1. That is, the pedestal portion 41 is preferably formed to have the same diameter as the circumscribed circle c1 or a diameter larger than the circumscribed circle c1 by a predetermined range. As described above, by limiting the diameter of the pedestal portion 41 to substantially the same size as the diameter of the region where the columnar portions 51, 52, 53 are formed, light is emitted from the element surface other than the emission surfaces 51a, 52a, 53a. Leakage can be prevented.

  The columnar portions 51, 52, and 53 are for shaping a light beam and controlling the direction of the light beam. As shown in FIG. 1, the columnar portions 51, 52, and 53 form light rays by emitting light generated in the light emitting layer 20 from the emission surfaces 51 a, 52 a, and 53 a of the column heads.

  Specifically, the columnar portions 51, 52, 53 function as a waveguide for light generated in the light emitting layer 20. Here, for example, since the LED element generally has a coherence length of about 10 μm to 50 μm, light having a different path length in the minute space as described above forms a spatial distribution due to the interference effect. Therefore, the light generated in the light emitting layer 20 and propagated through the columnar portions 51, 52, 53 is, as shown in FIG. 2, the emission surface (capillary) 51a, which is the uppermost surface of the columnar portions 51, 52, 53. After being emitted upward from 52a and 53a, interference occurs due to the light interference effect, and one light beam is generated from the center of gravity c (see FIG. 3) of the element surface in a direction inclined from the direction perpendicular to the element surface. Is done. In addition, the element surface here means the upper surface of the base part 41 shown, for example in FIG.

  As shown in FIG. 1, the columnar parts 51, 52, 53 are formed in a columnar shape having a circular cross section, and a total of six columnar parts 51 are formed on the upper side of the pedestal part 41 as an example. In addition, the columnar portions 51, 52, and 53 are formed so that the height of the columns is different by two here, and the columnar portions 53, the columnar portions 52, and the columnar portions 51 are formed in this order. . Further, as shown in FIG. 1, the height of the two columnar portions 51, the height of the two columnar portions 52, and the height of the two columnar portions 53 are configured to be equal to each other. In addition, at least two or more of these columnar portions are formed on the upper side of the pedestal portion 41, and if at least one column has a different height, it is possible to form a light beam and control its direction. Here, as shown in FIG. 1, six configurations will be described as an example.

  As shown in FIG. 3, the columnar portions 51, 52, and 53 are arranged on the circle c <b> 2 centered on the center of gravity c on the pedestal portion 41 and spaced apart at equal intervals in the direction of an equal angle. . That is, the columnar parts 51, 52, 53 are arranged along the circular direction and at an equal distance. The intervals between the columnar portions 51, 52, 53 are set in advance to such a length that light from adjacent columnar portions can interfere with each other. That is, the interval between the columnar portions 51, 52, 53 is preferably equal to or less than the coherence length of the light emitting element 1. The coherence length of light depends on the half-value width of the emission spectrum of the light source and the center wavelength. However, when the light source is an LED element, the length is about 10 μm to several tens of μm, for example.

Columnar portions 51, 52, and 53 has a wavelength lambda ₀ of about more than the diameter of the radiation in free space (e.g., diameter 2 [phi), as shown in FIG. 3 are each composed of the same diameter. Further, it is preferable that the difference in height between the columnar portions 51, 52, 53 is not more than half the length of the wavelength λ ₁ of the emitted light inside the columnar portions 51, 52, 53. As a result, the height difference between the columnar portions 51, 52, and 53 is set so that the difference between the position of the exit surface of at least one column and the position of the exit surface of the other column has a dominant influence. Since the range is set, the angle formed by the emitted light with respect to the direction perpendicular to the element surface can be made relatively large.

  As shown in FIG. 2, the columnar portions 51, 52, and 53 are formed on the upper surface of the pedestal portion 41, but may be integrally formed of the same material as the pedestal portion 41. In this case, the columnar portions 51, 52, 53 form a dielectric layer formed up to the height of the columnar portions 51, 52, 53, for example, in the manufacturing stage of the light emitting element 1, and the columnar portions 51, 52, 53 are formed. It can be formed by processing according to the height.

  Here, regarding the principle of interference of light emitted from the columnar parts 51, 52, and 53, and the principle of generation of light and its direction control, the above-mentioned Patent Document 1 (Japanese Patent Laid-Open No. 2013-175536) and other Since it has already been described in detail in a known document (for example, Japanese Patent Application Laid-Open No. 2014-27011), the description is omitted here.

  The light shielding film 60 shields light generated in the light emitting layer 20. Here, when the light emitting element 1 is driven, the light generated in the light emitting layer 20 propagates in the buffer layer 30 and the columnar portions 51, 52, 53, and the emission surfaces 51 a of the columnar portions 51, 52, 53 are generated. Radiated to the outside from 52a and 53a. At this time, if light leaks from the element surface (especially the buffer layer 30) other than the emission surfaces 51a, 52a and 53a, the leaked light and the light emitted from the emission surfaces 51a, 52a and 53a interfere with each other. This adversely affects the generation and control of light rays. Therefore, the light emitting element 1 includes a light shielding film 60 in order to prevent such light leakage.

  As shown in FIG. 1, the light shielding film 60 is formed on the upper side of the buffer layer 30, and as shown in FIG. 3, the light shielding film 60 is formed outside the circumscribed circle c1 surrounding all the columnar portions 51, 52, 53 in a plan view. ing. Specifically, as shown in FIGS. 2 and 3, the light shielding film 60 covers all the side surfaces of the pedestal portion 41 formed in the range of the circumscribed circle c <b> 1 and covers the surface of the region outside the circumscribed circle c <b> 1. Is formed. Therefore, when viewed in plan as shown in FIG. 3, the entire region other than the pedestal portion 41 is covered with the light shielding film 60. In other words, as shown in FIGS. 1 to 3, the light shielding film 60 has a circular opening o at the center, and a pedestal 41 is formed so as to fill the opening o. The above-mentioned “region surface outside the circumscribed circle c1” specifically means a region outside the pedestal portion 41.

  Here, the light shielding film 60 is preferably formed at a position lower than the maximum radiation angle of the light emitted from the columnar parts 51, 52, 53. Thereby, it is possible to prevent the light emitted from the emission surfaces 51a, 52a and 53a from receiving unnecessary interference by the light shielding film 60. In addition, since the spread of light rays generally falls within the range of +10 degrees to −10 degrees, the light shielding film 60 is positioned at a position lower than the maximum radiation angle of light emitted from the columnar portions 51, 52, 53. More preferably, it is formed.

Here, the above-mentioned maximum light emission angle means the maximum value of the central angle of the controlled light beam. Further, when specifying the range of the maximum emission angle of light, for example, in relation to the columnar portions 51, 52, 53, as shown in FIG. 2, the side surfaces of the columnar portions 51, 52, 53 when viewed from the front, and the columnar shape The angle θ ₁ formed with the straight line extending from the bottom of the portions 51, 52, 53 is in the range of 15 degrees, and the perpendicular extends from the center of the upper surface of the columnar portions 51, 52, 53 (ie, the emission surfaces 51a, 52a, 53a). The range of the angle θ ₂ formed by the straight line extending from the center of the upper surface of each of the columnar portions 51, 52, and 53 can be set as the range of the maximum light emission angle.

  The light shielding film 60 is preferably formed with a thickness that allows the transmitted light to be 1% or less in consideration of the extinction coefficient with respect to the center frequency of the light beam. Thus, by forming the light shielding film 60 with a predetermined thickness, it is possible to prevent light from leaking from the element surfaces other than the emission surfaces 51a, 52a, and 53a.

  Further, the light shielding film 60 has a height on the side facing the pedestal portion 41 that is equal to or lower than the height of the surface of the pedestal portion 41, that is, the height of the surface of the pedestal portion 41. preferable. Thereby, since the upper surface of the light shielding film 60 is formed at a position equal to or lower than the bottom surfaces of the columnar portions 51, 52, 53, the light emitted from the emission surfaces 51 a, 52 a, 53 a is transmitted by the light shielding film 60. It is possible to prevent unnecessary interference.

  The material of the light shielding film 60 is not particularly limited as long as it can shield light, and examples thereof include metal materials such as Al, Au, Ni, and W.

  The light emitting element 1 having the above configuration emits light from the light emitting layer 20 provided on the lower side of the buffer layer 30 having a flat surface, and the columnar parts 51, 52, 53 provided on the pedestal part 41. The light beam is shaped by the interference effect of the light emitted from. In the light emitting element 1, since the height of at least one columnar portion 51, 52, 53 is different from the other, it propagates through the inside of at least one columnar portion 51, 52, 53, and exit surfaces 51a, 52a. , 53a, and the propagation distance in the solid (inside the column) of the light radiated from the exit surfaces 51a, 52a, 53a by propagating through the inside of the other columnar parts 51, 52, 53. be able to. Thereby, the radiation direction of the light beam formed by the interference of the respective radiation lights having different phases can be inclined from the direction perpendicular to the element surface.

  Further, since the light emitting element 1 is covered with the light shielding film 60 except for the region where the columnar parts 51, 52, 53 are formed, the element surface other than the emission surfaces 51a, 52a, 53a (especially, in particular) The stray light leaking from the buffer layer 30) can be suppressed, and extra interference caused by the light leaking from the element surface and the light emitted from the respective columnar portions 51, 52, 53 can be prevented. The light deflection characteristics can be improved.

[Specific examples of light emitting element design]
The light-emitting element 1 is, for example, an LED element obtained by adding In to GaN, and the center wavelength (λ ₀ ) of the emission spectrum is 830 nm. SiO ₂ was used for the pedestal portion 41 made of a dielectric, Au was used for the light shielding film 60, and the thickness of the buffer layer 30 was about 500 nm.

The interval between the columnar portions 51, 52, 53 was set to 1000 nm corresponding to 1.2 times the wavelength λ ₀ in the free space of the emitted light. The radius φ of the columnar parts 51, 52, 53 was set to 400 nm corresponding to 1/2 of the wavelength λ ₀ in the free space of the emitted light. The height of the columnar portion 51, and a wavelength of in the columnar portion 51, i.e., a 1050nm which corresponds to about two wavelengths of the wavelength lambda ₁ of a dielectric of the radiation (SiO _2). The height of the columnar part 52 was set to 850 nm which is lower than the columnar part 51 by 200 nm corresponding to ¼ of the wavelength λ ₀ in free space. The height of the columnar portion 53 was set to 650 nm lower than that of the columnar portion 51 by 400 nm corresponding to 1/2 of the wavelength λ ₀ in free space. By changing the height of the columnar parts 51, 52, 53 in this way, the light beam direction is controlled.

[Method for Manufacturing Light-Emitting Element]
Hereinafter, an example of a method for manufacturing the light-emitting element 1 according to the first embodiment of the present invention will be described with reference to FIG.

  As a method for manufacturing the light-emitting element 1, various known fine processing techniques can be used. The light emitting element 1 can be manufactured by preparing a light emitting element having a flat radiation surface such as an LED element and finely processing the surface thereof. As an example of the manufacturing method of the light emitting element 1, first, as shown in FIG. 4A, for example, a molecular beam epitaxy (MBE) method, an organic material is applied to a substrate S made of a semiconductor such as GaAs or Si. The semiconductor layer 10 and the buffer layer 30 are stacked by a film forming method such as a metal chemical vapor deposition (MOCVD) method, and an impurity such as In is added to the junction to form the light emitting layer 20.

  Next, as shown in FIG. 4B, a light shielding film 60 is formed by laminating a metal material on the buffer layer 30 by vapor deposition, sputtering, or the like. Next, as shown in FIG. 4B, a region other than the region where the pedestal 41 is formed on the light shielding film 60 is masked, and reactive ion etching (RIE) or the like is performed on the mask. By performing dry etching or wet etching using a chemical solution, an opening o is formed as shown in FIG.

Next, the region of the light shielding film 60 is masked, and as shown in FIG. 4D, a dielectric such as SiO ₂ is formed in the opening o using the vapor deposition method (CVD method) or the like. A cylindrical dielectric layer 40A is formed. At that time, the dielectric layer 40A is formed with a thickness equal to or greater than the uppermost portion of the columnar portions 51, 52, and 53. Then, the mask is removed together with the dielectric layer 40A thereon. Next, as shown in FIG. 4 (e), the dielectric layer 40A is etched stepwise based on a focused ion beam (FIB) method or the various etching methods described above, so that three steps are performed. Columnar portions 51, 52, and 53 are formed to have a height. In addition, by passing through such a process, as shown in FIG.4 (e), the base part 41 will also be formed simultaneously. By performing the above process, the light emitting element 1 as shown in FIG. 1 can be manufactured.

Second Embodiment
[Configuration of Light Emitting Element]
The configuration of the light emitting element 1A according to the second embodiment of the present invention will be described with reference to FIGS. In the following description, a configuration that overlaps with the light emitting element 1 according to the first embodiment will be described in a simplified manner or will not be described.

  As shown in FIG. 5, the light emitting element 1A has a structure in which a semiconductor layer 10, a light emitting layer 20, a buffer layer 30, a dielectric layer 40, and a light shielding film 60A are stacked. In the light emitting element 1A, as shown in FIG. 5, a recess 40a is formed from the light shielding film 60A to the dielectric layer 40, and a pedestal 41A is formed in the recess 40a. A plurality of columnar portions 51, 52, 53 are formed on the upper side of the pedestal portion 41A.

The dielectric layer 40 is a layer made of a dielectric material that transmits light. The dielectric layer 40 may have a structure in which thin films such as SiO ₂ and Al ₂ O ₃ are stacked. When the dielectric layer 40 is formed by nanoimprinting, a polymer material can be used.

  As shown in FIG. 6, the dielectric layer 40 has a circular recess 40 a formed in a thickness direction from the upper surface in a plan view. And the dielectric material layer 40 has a convex part as the base part 41A in the bottom face of the said recessed part 40a. That is, the dielectric layer 40 includes a pedestal portion 41A as a part thereof.

  The light shielding film 60 </ b> A shields light generated in the light emitting layer 20 in the same manner as the light shielding film 60 described above, but has a configuration different from that of the light shielding film 60. That is, as shown in FIG. 6, the light shielding film 60 </ b> A is formed so as to cover the side surface of the pedestal 41 </ b> A, the bottom surface and the inner surface of the recess 40 a, and the upper surface of the dielectric layer 40 outside the recess 40 a. Specifically, as shown in FIGS. 6 and 7, the light shielding film 60A covers the entire side surface of the pedestal portion 41A formed to include the range of the circumscribed circle c1, and also the region outside the circumscribed circle c1, that is, the pedestal. It is formed so as to cover the bottom surface of the recess 40a excluding the portion 41A, the inner surface of the recess 40a formed upright from the bottom surface, and the region other than the recess 40a in the dielectric layer 40. Therefore, when viewed in a plan view as shown in FIG. 7, the entire region other than the base portion 41A is covered with the light shielding film 60A.

  Here, the light shielding film 60A is formed of a metal film in which the light shielding film in the recess 40a is different from the light shielding film on the surface of the other dielectric layer 40. That is, in the light shielding film 60A, as shown in FIG. 6, the first light shielding film 61 made of tungsten (W), for example, is formed in the recess 40a, and the surface of the other dielectric layer 40 is made of gold (Au), for example. Two light shielding films 62 are formed. The first light shielding film 61 is formed so as to cover the bottom surface of the concave portion 40a excluding the pedestal portion 41A from the side surface of the pedestal portion 41A and the inner side surface of the concave portion 40a. The first light shielding film 61 on the inner surface of the recess 40a is provided so as to be inclined in a mortar shape. The second light shielding film 62 is formed so as to cover a region other than the recess 40a in the dielectric layer 40, that is, the upper surface outside the recess 40a.

  The light emitting element 1A having the above-described configuration has a simple configuration because the region other than the base portion 41A, that is, the portion other than the region where the columnar portions 51, 52, 53 are formed is covered with the light shielding film 60A. The stray light leaking from the element surface (especially the buffer layer 30) other than the emission surfaces 51a, 52a, 53a can be suppressed, and the light leaking from the element surface and the respective columnar portions 51, 52, 53 are emitted. Since extra interference with light can be prevented, light deflection characteristics can be improved.

  Here, the second light shielding film 62 is preferably formed at a position lower than the maximum radiation angle of the light emitted from the columnar parts 51, 52, 53. Thereby, it is possible to prevent the light emitted from the emission surfaces 51a, 52a, and 53a from receiving unnecessary interference by the second light shielding film 62. In other words, by appropriately adjusting at least one of the height of the pedestal portion 41A, the depth of the recess 40a, the diameter of the recess 40a, and the thickness of the second light shielding film 62, the columnar portions 51, 52, and 53 are radiated. Light can be sent out without unnecessary interference. In addition, since the spread of light rays generally falls within a range of +10 degrees to −10 degrees, the second light shielding film 62 is lower than the maximum radiation angle of light emitted from the columnar portions 51, 52, 53. More preferably, it is formed at a position.

Here, when specifying the range of the maximum emission angle of light, for example, in relation to the columnar portions 51, 52, 53, as shown in FIG. 6, the side surfaces of the columnar portions 51, 52, 53 when viewed from the front, angle theta ₁ between the straight line extending from the bottom of the columnar portion 51, 52, 53 in a range of 15 degrees, extending from the center of the upper surface of the columnar portion 51, 52 and 53 (i.e. the exit plane 51a, 52a, 53a) and the perpendicular, the angle θ range ₂ to 60 degrees between the straight line extending from the center of the upper surface of the columnar portion 51, 52, 53, may be in the range of maximum emission angle of the light.

  The first light-shielding film 61 and the second light-shielding film 62 are preferably formed with a thickness that allows the transmitted light to be 1% or less in consideration of the extinction coefficient with respect to the center frequency of the light beam. In this manner, by forming the first light shielding film 61 and the second light shielding film 62 with a predetermined thickness, it is possible to prevent light from leaking from the element surfaces other than the emission surfaces 51a, 52a, and 53a.

  Furthermore, it is preferable that the height of the first light-shielding film 61 on the side facing the pedestal portion 41A is equal to or lower than the surface of the pedestal portion 41A. The first light shielding film 61 is formed at a position and height that shields the inner surface of the recess 40a and does not reach the light emitted from the emission surfaces 51a, 52a, and 53a. Thereby, the 1st light shielding film 61 can prevent that the light radiated | emitted from the output surfaces 51a, 52a, 53a receives unnecessary interference by the light from the inner surface of the recessed part 40a.

[Method for Manufacturing Light-Emitting Element]
Hereinafter, a manufacturing method of the light emitting device 1A according to the second embodiment of the present invention will be described with reference to FIG.

The manufacturing method of the light emitting element 1A is the same as the manufacturing method of the light emitting element 1 according to the first embodiment described above until the step of forming the buffer layer 30 (see FIG. 4B). ), A dielectric layer 40 made of SiO ₂ or the like is formed on the buffer layer 30 by using a vapor deposition method (CVD method) or the like. At that time, the dielectric layer 40 is formed with a thickness greater than or equal to the uppermost portion of the columnar portions 51, 52, 53. Next, as shown in FIG. 8B, a second light shielding film 62 is formed by laminating a metal material on the dielectric layer 40 by vapor deposition, sputtering, or the like.

  Next, using the focused ion beam method, specifically, by applying a focused ion beam of gallium (Ga) to repel atoms on the surface (by sputtering), the second light shielding film 62 and the dielectric layer 40 is etched to form a circular recess 40a in plan view as shown in FIG. Further, the dielectric layer 40 is finely processed by the focused ion beam method, and columnar portions 51, 52, and 53 are formed so as to have three levels as shown in FIG. 8C. Further, etching by the focused ion beam method is advanced to form a pedestal portion 41A as shown in FIG.

  Next, using a focused ion beam assisted deposition method, specifically, after W (CO) 6 gas is adsorbed on the bottom surface and the inner surface of the recess 40a, the W (CO) gas is focused by the focused ion beam of gallium (Ga). The first light shielding film 61 is formed as shown in FIG. 8E by decomposing the (CO) 6 gas and depositing tungsten (W) on the bottom surface and the inner surface of the recess 40a. Accordingly, the first light shielding film 61 is formed on the inner surface of the recess 40a so as to be inclined in a mortar shape. By performing the above steps, a light emitting device 1A as shown in FIG. 5 can be manufactured.

[Performance of light emitting element]
In order to confirm the performance of the light emitting device according to the present invention, a simulation by a FDTD (Finite-Difference Time Domain) method was performed. In this simulation, the light emitting elements of the comparative example and the example of the present invention were prepared, and the light deflection characteristics of both were evaluated. In the drawings referred to below, the semiconductor layer 10 and the light emitting layer 20 may be omitted for convenience of explanation.

  First, the results of comparing the light deflection characteristics of Comparative Example 1 and Example 1 of the present invention will be described with reference to FIGS. 9 and 10.

(Comparative Example 1)
As shown in FIG. 9A, the light emitting element 101 according to the comparative example 1 has six columnar parts 51, 52, 53 formed on the buffer layer 30. That is, the light emitting element 101 according to the comparative example 1 does not include the light shielding film 60 unlike the first embodiment of the present invention described above.

Example 1
In the light emitting element 1 according to Example 1, as shown in FIG. 10A, a pedestal portion 41 is formed on the buffer layer 30, and six columnar portions 51, 52, 53 are formed on the pedestal portion 41. did. In the light emitting element 1 according to Example 1, the light shielding film 60 was formed so as to cover the periphery of the pedestal portion 41. That is, the light-emitting element 1 according to Example 1 has the same configuration as that of the first embodiment of the present invention described above.

Comparing the beam patterns of Comparative Example 1 and Example 1, as shown in FIG. 9B and FIG. 10B, Comparative Example 1 shows that the main axis of the light beam is changed only by 0.8 degrees. Thus, Example 1 changes by 4.4 degrees. Even if the same columnar portions 51, 52, 53 are used, stray light leaking from the area around the columnar portions 51, 52, 53 is suppressed unless the structure including the light shielding film 60 as in the first embodiment is used. This indicates that it is difficult to deflect the light beam. Therefore, by providing the light shielding film 60 like the light emitting element 1 according to the first embodiment of the present invention, it is possible to significantly improve the light deflection characteristics compared to the case where the light shielding film 60 is not provided. is there. 9 and 10, the angle θ _p represents the angle of the principal axis of the light beam measured from the direction (z axis) perpendicular to the element surface.

In FIG. 9B and FIG. 10B, the region indicated by the symbol r (red) indicates that the intensity of light is approximately 0.1 W / m ² , and the region indicated by the symbol y (yellow) Indicates that the light intensity is approximately 0.07 W / m ² . Further, the region indicated by the symbol g (green) indicates that the light intensity is approximately 0.05 W / m ² , and the region indicated by the symbol b (blue) has an intensity of light of approximately 0 W / m ² . It is shown that. Here, the power density obtained by taking the square of the electric field in the FDTD method was used as the light intensity.

  Next, the result of comparing the light deflection characteristics of the comparative example 2 and the embodiment 2 of the present invention will be described with reference to FIGS.

(Comparative Example 2)
In the light emitting element 101A according to Comparative Example 2, as shown in FIG. 11A, a recess 30a is formed in the thickness direction of the buffer layer 30A, and six columnar portions 51, 52, 53 are formed in the recess 30a. did. Further, the light shielding film 60B is formed so as to cover the upper surface of the recess 30a of the buffer layer 30A. An annular light emitting portion 20A was formed below the buffer layer 30A in a range corresponding to all the columnar portions 51, 52, 53 in plan view. That is, although the light emitting element 101A according to the comparative example 2 includes the light shielding film 60B as in the first embodiment, the light emitting unit 20A has an annular shape only in a range corresponding to the columnar parts 51, 52, and 53. Is formed.

(Example 2)
In the light emitting element 1 according to Example 2, as shown in FIG. 12A, a pedestal portion 41 is formed on the buffer layer 30, and six columnar portions 51, 52, 53 are formed on the pedestal portion 41. did. In the light emitting device 1 according to Example 1, the light shielding film 60 was formed so as to cover the periphery of the pedestal portion 41. The light emitting layer 20 was formed on the entire surface below the buffer layer 30. That is, the light-emitting element 1 according to Example 1 has the same configuration as that of the first embodiment of the present invention described above.

Comparing the beam patterns of Comparative Example 2 and Example 2, as shown in FIGS. 11B and 12B, Comparative Example 2 changes the principal axis of the light beam by 4.3 degrees. .4 degrees change. In Comparative Example 2, since the annular light emitting portion 20A is formed in a range corresponding to the columnar portions 51, 52, and 53, it is considered that the light deflection characteristic is improved as compared with Comparative Example 1 (see FIG. 9).
However, in the manufacturing process of the light emitting element, it is not easy to control the shape of the light emitting layer so as to be an annular light emitting portion 20A as in Comparative Example 2, and actually the light emitting element as shown in Comparative Example 2 is used. It is difficult to manufacture 101A. On the other hand, the light-emitting element 1 according to Example 2 can obtain light deflection characteristics that exceed those of Comparative Example 2 without performing shape control of the light-emitting layer as described above.

  The light-emitting element according to the present invention has been specifically described above with reference to modes and examples for carrying out the invention. However, the gist of the present invention is not limited to these descriptions, and the description of the claims Should be interpreted widely. Needless to say, various changes and modifications based on these descriptions are also included in the spirit of the present invention.

  For example, since the light emitting elements 1 and 1A described above are assumed to be LED elements, the base portions 41 and 41A made of a dielectric are provided on the buffer layer 30, and the columnar portions 51 are provided on the base portions 41 and 41A. , 52, 53. For example, by forming the buffer layer 30 with the same dielectric as the dielectric layers 40, 40A, the light emitting element can be configured without the dielectric layers 40, 40A. In this case, in the manufacturing process of the light emitting element, the buffer layer 30 is formed with a thickness greater than or equal to the uppermost portion of the columnar portions 51, 52, 53, and the buffer layer 30 is stepped on the basis of the focused ion beam method or the various etching methods described above. It is sufficient to form the columnar portions 51, 52, 53 having three levels of height by etching.

  Further, in the light emitting element 1A described above, the light emitting layer 20 that is a light source is sandwiched between the buffer layer 30 that is a p-type semiconductor layer and the semiconductor layer 10 that is an n-type semiconductor layer, and the dielectric layer 40 and the columnar portion 51 are disposed on the upper side. , 52, 53 and a light-shielding film 60A are provided. For example, an LED element or a laser or an optical fiber using the LED element as a light source is directly placed under the dielectric layer 40, and the same as the light-emitting element 1A. It is also possible to produce an effect.

  In addition, since the light-emitting elements 1 and 1A according to the present invention can control the direction of light rays simply by forming the columnar portions 51, 52, and 53 on the surface, providing a three-dimensional display of an IP system by arranging a large number on a plane. Is possible. A display element (FPD: Flat Panel Display) in which a large number of such light emitting elements 1 and 1A are arranged has the same function as an apparatus in which a lens plate and a light emitting surface are joined in the prior art without using a lens plate. It becomes like this. Further, in the IP stereoscopic display created in this way, the resolution of the stereoscopic display depends only on the definition of the light emitting elements 1 and 1A, and image blur due to insufficient resolution of the optical system does not occur. Further, the viewing zone angle in IP display using the light emitting elements 1 and 1A depends only on the maximum value of the angle of the emitted light with respect to the direction perpendicular to the element surface, and the resolution and the viewing zone angle are improved independently. Is possible.

  The light-emitting device according to the present invention can be applied to 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 diffusion plate, and the like.

1, 1A, 101, 101A Light emitting element 10 Semiconductor layer 20 Light emitting layer 20A Light emitting part 30, 30A Buffer layer 30a, 40a Recess 40, 40A Dielectric layer 41, 41A Pedestal part 51, 52, 53 Columnar part 51a, 52a, 53a Outgoing surface 60, 60A, 60B Light shielding film 61 First light shielding film 62 Second light shielding film c Center of gravity c1 circumscribed circle c2 circle o opening

Claims (8)

A light emitting layer;
A buffer layer formed on the light emitting layer;
A pedestal portion formed of upper side definitive central formed on a portion dielectric of the buffer layer,
At least two or more columns are formed on the upper side of the pedestal portion, and the height of at least one column is different from the height of the other columns, and the columnar portion that radiates light generated in the light emitting layer from the column heads;
A light-shielding film formed on the outside of a circumscribed circle surrounding all the columnar parts in plan view,
The pedestal portion is formed in a range of the circumscribed circle in a plan view,
The light shielding film is formed so as to cover a side surface of the pedestal and an outer region surface of the circumscribed circle,
The light emitting device , wherein the buffer layer is made of a dielectric . A light emitting layer;
A buffer layer formed on the light emitting layer;
A dielectric layer formed on the buffer layer;
A pedestal made of a dielectric formed in the dielectric layer;
At least two or more columns are formed on the upper side of the pedestal portion, and the height of at least one column is different from the height of the other columns, and the columnar portion that radiates light generated in the light emitting layer from the column heads;
A light-shielding film formed on the outside of a circumscribed circle surrounding all the columnar parts in plan view,
The dielectric layer has a circular concave portion in plan view formed in the thickness direction from the upper surface, and has a convex portion as the pedestal portion on the bottom surface of the concave portion,
The light-shielding film includes a first light-shielding film that covers a side surface of the pedestal portion, a bottom surface and an inner side surface of the concave portion, and a second light-shielding film that covers an upper surface of the dielectric layer outside the concave portion. Light emitting element.   The light-emitting element according to claim 1, wherein the light-shielding film is formed at a position lower than a maximum radiation angle of light emitted from the columnar part.   4. The light emitting device according to claim 1, wherein a diameter of the pedestal portion is within a range of D to 1.05 D, where D is a diameter of the circumscribed circle. 5. element.   The said light shielding film is formed in the thickness from which the transmitted light will be 1% or less from the loss | disappearance coefficient with respect to the center frequency of a light ray, The Claim 1 characterized by the above-mentioned. Light emitting element.   6. The light emitting device according to claim 1, wherein the light shielding film has a height on a side facing the pedestal portion that is equal to or lower than a surface of the pedestal portion. .   7. The light emitting device according to claim 1, wherein a difference in height between the columnar portions is equal to or less than a half of a wavelength of radiated light in the columnar portions. .   The light emitting device according to claim 2, wherein the first light shielding film and the second light shielding film are formed of different metal films.