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WO2009081325A1 - Diode électroluminescente - Google Patents

Diode électroluminescente Download PDF

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Publication number
WO2009081325A1
WO2009081325A1 PCT/IB2008/055302 IB2008055302W WO2009081325A1 WO 2009081325 A1 WO2009081325 A1 WO 2009081325A1 IB 2008055302 W IB2008055302 W IB 2008055302W WO 2009081325 A1 WO2009081325 A1 WO 2009081325A1
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WIPO (PCT)
Prior art keywords
led
light
sub
photonic crystals
guiding means
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2008/055302
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English (en)
Inventor
Marcus A. Verschuuren
Hendrik A. Van Sprang
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Koninklijke Philips NV
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Koninklijke Philips Electronics NV
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Publication of WO2009081325A1 publication Critical patent/WO2009081325A1/fr
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Classifications

    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H29/00—Integrated devices, or assemblies of multiple devices, comprising at least one light-emitting semiconductor element covered by group H10H20/00
    • H10H29/10—Integrated devices comprising at least one light-emitting semiconductor component covered by group H10H20/00
    • H10H29/14—Integrated devices comprising at least one light-emitting semiconductor component covered by group H10H20/00 comprising multiple light-emitting semiconductor components
    • H10H29/142—Two-dimensional arrangements, e.g. asymmetric LED layout
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
    • H10H20/80—Constructional details
    • H10H20/85—Packages
    • H10H20/855—Optical field-shaping means, e.g. lenses
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
    • H10H20/80—Constructional details
    • H10H20/81—Bodies
    • H10H20/814—Bodies having reflecting means, e.g. semiconductor Bragg reflectors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
    • H10H20/80—Constructional details
    • H10H20/83—Electrodes
    • H10H20/831—Electrodes characterised by their shape
    • H10H20/8316—Multi-layer electrodes comprising at least one discontinuous layer

Definitions

  • the present invention relates to a semiconductor light emitting diode, comprising a first and a second electrode for applying a voltage across an active region, arranged between a first type semiconductor layer and a second type semiconductor layer for generation of light, and a light emitting surface for emitting said light.
  • light emitting diodes emitting visible light
  • Applications of light emitting diodes include light emitting signs, such as exit signs or emergency signs, lights for vehicles, such as breaking lights, backlight illumination for large scale video displays and illumination systems for furniture, such as shelves.
  • light emitting diodes for applications like projection sources or car headlamps is growing less rapidly, due to the fact that the emission angle of a generic light emitting diode is wide. For these applications, it is desired to use a light source having highly co llimated light.
  • a prior art LED comprises a first electrode, an N-type semiconductor layer, a P-type semiconductor layer and a second electrode. There is formed an active region between the N-type and P-type semiconductor layers. Further, the first electrode is connected to the N- type layer and the second electrode is connected to the P-type layer. A light emitting surface of the LED is located on the opposite side of the N-type layer compared to the active region. In the second electrode there are formed holes or channels. The holes or channels are spread over the second electrode. Through these holes or channels current is conducted (without electrical contact with the second electrode) to the first electrode. In this manner, an improved current spreading over the first electrode is achieved.
  • a disadvantage of prior art LEDs is that it is difficult to use one type of LED for many different applications, since for a certain application, requiring a specific type of beam shape (or beam angle), there is, in general, a need for optimization of the light beam from the LED by means of adding secondary optics adapted to that specific LED.
  • the beam shape from such an LED with secondary optics may be unsuitable for other applications.
  • many types of LED with different secondary optics may be incorporated into a lighting system of LEDs in order to fulfill the needs of more than one application.
  • An object of the present invention is to alleviate at least some of the above- mentioned problems of the prior art.
  • a semiconductor light emitting diode comprising a first and a second electrode for applying a voltage across an active region , arranged between a first type semiconductor layer and a second type semiconductor layer for generation of light, and a light emitting surface for emitting the light. Furthermore, the LED comprises a first and a second light guiding means, arranged between the light emitting surface and the active region.
  • the second electrode comprises sub- electrodes, disposed on the opposite side of the active region compared to the light emitting surface, wherein a first sub-electrode is associated with the first light guiding means and a second sub-electrode is associated with the second light guiding means.
  • the first and second sub-electrodes are individually controllable by means of applying a respective voltage to each of the first and second sub-electrodes, whereby light emission of the LED is dynamically controllable due to light emission from the first and second light guiding means.
  • An idea of the invention is to provide an LED with segments comprising light guiding means for extracting the light out of the LED. Thereby, for example, determining the shape of the emitted beam and the angular distribution of the emitted light. Further, the means for guiding the light may influence the properties, such as color, beam angle, intensity etc., of the light generated in the active region of the LED before being emitted from the LED.
  • the LED further comprises an electrode, disposed on the opposite side of the active layer compared to the light guiding means.
  • the electrode comprises sub- electrode arrangements and each sub-electrode arrangement is associated with at least one light guiding means, whereby activation of a specific sub-electrode arrangement results in light emission from the associated at least one light guiding means. For example, by applying a voltage to an electrode arrangement (sub-electrode) associated with light guiding means, and switching off all other electrode arrangements associated with light guiding means, the emission type from the LED may be controlled.
  • the first light guiding means is of a first type and the second light guiding means is of a second type.
  • the light guiding means of the first type may differ from the light guiding means of the second type in that the emission from the respective light guiding means are different.
  • the first type may emit collimated light and the second type may emit diverging light
  • the first type may emit red light and the second type may emit blue light, and so on for any light property.
  • the LED may dynamically (without any need for hardware changes) provide different types of beam shapes, e.g. one type of beam shape (with collimated light) for reading and another type of beam shape (with broad emission) for watching television.
  • light guiding means is meant to comprise directing means, means for providing color (color filters) and/or light modification means, i.e. other means for affecting any property of the light emitted by the LED.
  • the color of the emitted light may be controlled, e.g. changed from red to blue.
  • a large variety in emission patterns from the LED may be obtained dynamically.
  • sub-electrode arrangements are associated with a number of active sub-regions (or sub-"active regions"). These active sub-regions may generate light upon activation by application of a voltage thereon. As a result different portions of the active region may be activated by selecting (activating) different sub-electrode arrangements.
  • the light guiding means comprises at least one of color filters, color conversion devices, colored areas, areas covered with luminescent materials, photonic crystals (with different beam shaping properties) or a combination thereof.
  • color mixing may be performed electrically.
  • mixing of colors may be obtained with less decrease in brightness. This is due to the fact that a color converting unit is arranged close to a light source and the light emitting surface of the LED may be confined to the active region of the LED.
  • heat transfer from the active region may be improved. This may be obtained by, for example, only activating a portion of the entire active region, which generates light. A portion where light is generated may be called an active site and a portion of the active region that is not generating light may be called a deactivated site (the associated sub-electrode is deactivated, i.e. no voltage is applied).
  • the active site When the active site is driven to emit light, it also generates heat. This heat may be dissipated in the surrounding deactivated sites, which thus provides local heat dissipation. In this manner, a higher current through the activated site may be applied than when the all sub-electrodes are addressed and there are no deactivated sited for providing local heat dissipation present.
  • the size and shape of the sub-electrodes it is preferred to match the size and shape of the sub-electrodes to the size and shape of the respective light guiding means. In this manner, easier and more predictable control of the emission may be provided. It shall be noted that some of the electrodes may be associated with a surface area of the LED that does not contain light guiding means.
  • size and shape (dimensions) of the sub-electrodes and/or segments of light guiding means may be chosen at will.
  • the smallest size of a segment depends on the type of light guiding means.
  • the light guiding means comprises photonic crystals
  • the smallest size depends on the interaction length of that specific photonic crystal.
  • the light guiding means may comprise light directing means.
  • the shape of the segments may be of polygonal shape, such as rectangular, triangular, square shape or a combination thereof. Most preferably, the segments have the same shape. In general, the segments are of square shape, in order to facilitate the manufacturing process.
  • the second type semiconductor layer being disposed on the opposite side of the active region compared to the light emitting surface, is divided into sub-elements, each sub-element being associated with a corresponding sub-electrode. Preferably, each sub-element is aligned with the corresponding sub-electrode.
  • the first type semiconductor layer is an N-type semiconductor layer and the second type semiconductor layer is a P-type semiconductor layer.
  • the N-type material usually is a better current conductor than the P-type semiconductor material, current spreading over the whole active region is achieved, and, thus, the entire light emitting, top surface can be used to generate and extract light.
  • the N-type layer may be disposed between the active region and the light emitting surface of the LED, and the P-type layer may be disposed on the opposite side of the active region compared to the N-type layer.
  • the first type semiconductor layer is a P-type semiconductor layer and the second type semiconductor layer is an N-type semiconductor layer.
  • the light guiding means may be arranged adjacent to each other for continuously covering at least a portion of the light emitting surface of the LED with light guiding means.
  • the influence of the light guiding means is maximized in this manner.
  • the application of light guiding means, however not necessarily in a continuous manner, is a key factor for obtaining different types of emission from different areas of the light emitting surface of the LED.
  • a semiconductor light emitting diode wherein the light guiding means comprises a plurality of photonic crystals. Furthermore, at least two photonic crystals, selected among said plurality of photonic crystals, are adapted to extract light from said active region and differ from each other with respect to at least one lattice parameter. Each of said at least two photonic crystals are associated with a respective far field pattern. Furthermore, an arrangement of said plurality of photonic crystals is provided to arrange said at least two photonic crystals, such that an overall far field pattern from the light generated in the LED is created by combining said respective far field patterns associated with each of said at least two photonic crystals.
  • the far field pattern of the LED may be controlled dynamically by activation of selected sub-electrodes.
  • a light emitting diode having a light emitting area (surface), which is divided into sub-areas. At least some of the sub-areas are provided with different photonic crystals (PCs), the photonic crystals being different in that at least one of their respective lattice parameters (including lattice type, lattice pitch, fill-fraction and lattice orientation as explained further below) differs from each other.
  • the sub-areas act as many different light sources, wherein each light source has a different radiation pattern (or radiation field).
  • the different radiation patterns, associated with each corresponding light source are combined into one pattern that may have an improved uniformity compared to a far field pattern, emanating from an LED with, for example, identical photonic crystals, or that may have a collimated light emission with improved symmetry.
  • an LED comprising photonic crystals of at least two different types.
  • Two photonic crystals that differ from each other with respect to at least one lattice parameter are regarded as being of different types.
  • the photonic crystals of different types form an arrangement of photonic crystals that arranges the photonic crystals, such that the overall far field pattern of the light emitted from the LED is more uniform than each of the individual far field patterns associated with the photonic crystals of different types. In this manner, the influence from darker and/or brighter spots, dots and/or alike, hereinafter referred to as irregularities of the far field pattern, is reduced.
  • an advantageous effect of the light emitting diode according to the above-mentioned embodiment of the present invention is that it provides light emission, whose far field radiation pattern may have an improved uniformity or displays less spots (irregularities) than with only one type of photonic crystal.
  • a further advantage of the above-mentioned LED according to an embodiment of the invention is that many different far field radiation patterns, as required by any specific application, may be designed with a fixed number of optimized photonic crystals.
  • a different design may be obtained by selecting a different arrangement of the photonic crystals of the LED, i.e. the positions of the photonic crystals are changed. For example for backlight applications, it is desired to provide an LED that has the bulk of the emission between 60° and 80° to a normal of the LED.
  • the photonic crystals may be formed as a part of the semiconductor layer closest to the light emitting surface.
  • the photonic crystal layer may extend from the light emitting surface through mentioned semiconductor layer closest to the light emitting surface, possibly also though the active region. Further, the photonic crystal layer may extend into the semiconductor layer at the opposite side of the active region compared to the light emitting surface of the LED.
  • the photonic crystals may, however, also be formed in a separate layer different from the semiconductor layer closest to the light emitting surface.
  • a photonic crystal comprises a lattice of holes, poles and/or alike. In the following (and foregoing), mentioning of holes is to be interpreted as holes and/or poles and/or alike.
  • the photonic crystals may comprise quasi photonic crystals in some embodiments.
  • the light emitting surface of the LED may further comprise a roughened emitting surface of the LED. In this manner, rough surface provides a uniform background emission, which reduces contrast between the darker and lighter areas in the far field due to the photonic crystal.
  • the arrangement of photonic crystals arranges (positions or locates) the different photonic crystals in a random manner.
  • the arrangement may, in addition or alternatively, arrange the different photonic crystals in a varying (with respect to at least one lattice parameter) manner.
  • a lattice parameter may be varied according to a linear function (or a function of any type and/or order) from one photonic crystal to another (adjacent) photonic crystal, such that uniformity of the far field pattern of the light emitted from the LED is improved.
  • the arrangement of photonic crystals may, in addition or alternatively, arrange the photonic crystals of different types aperiodically within the light emitting surface (more particularly within the semiconductor layer between the active region and the light emitting surface), whereby a combined far field pattern from the different photonic crystals is improved, i.e. there are less or reduced spots or alike.
  • the arrangement is arranged to position the above-mentioned photonic crystals of at least two different types in an irregular manner within the light emitting surface.
  • an overall far field pattern of the light emitted from the LED, having an increased uniformity may be obtained by arranging, preferably irregularly as above, the different photonic crystals within the light emitting area (surface), such that the different far field patterns of the associated different photonic crystals interact in such a manner that irregularities (brighter or darker spots or dots or circles) of a far field pattern associated with a photonic crystal occur at different positions with respect to irregularities (brighter or darker spots or dots or circles) of another far field pattern associated with another photonic crystal (or, expressed differently the far field patterns of associated photonic crystals shall preferably be at least partly non-corresponding with respect to their respective spatial extensions).
  • the far field patterns of associated photonic crystals should, preferably, be at least slightly out of phase with each other.
  • the LED according to the present invention it may be desirable to position (arrange or locate) the photonic crystals of different types in a regular manner.
  • the brighter and/or darker spots in the far field patterns from the photonic crystals must overlap sufficiently, such as to provide an emitted power in a solid angle within a specific range.
  • the spots in the far field patterns may overlap, and, thereby render a far field pattern with fewer and/or less distinct (blurred) irregularities (spots etc.).
  • the lattice parameters may be one of lattice orientation, lattice pitch, lattice type or fill fraction or a combination thereof.
  • lattice parameter includes lattice orientation, i.e. two photonic crystals are regarded as being different (or different types), if they are oriented differently, even if they have the same pitch, fill fraction and lattice type.
  • the photonic crystals may have the same or similar short-range order, but slightly different pitch, or the same or similar pitch, but different fill fraction.
  • the photonic crystals may have the same (or similar) pitch and shape, but being different in that the lattice type is different, i.e.
  • a hexagonal structure is different from a triangular (or cubic) lattice structure. It is to be observed that some of the photonic crystals may have the same lattice parameters, i.e. it is not required that all the photonic crystals of the LED have at least one different lattice parameter. It is to be understood that the term "fill fraction" refers to the dimensions of the photonic crystal constituents, such as holes, poles or alike, i.e. the diameter of the holes differ from one photonic crystal to another photonic crystal. Typically, the diameter of the holes (or poles) is in the range of 30 nm to 700 nm for visible light.
  • the pitch (or the lattice constant) of a photonic crystal is defined as the distance from the center of a hole (or pole or alike) to the center of an adjacent hole in the photonic crystal lattice. For visible light, this distance is typically in the range from 80 nm to 800 nm. In general, the optimal pitch (or lattice pitch) increases with the wavelength of the emitted light.
  • the pitch and fill fraction of the LED may be varied by means of filling the holes (or gaps between poles) in the semiconductor material with a material, whose refractive index is different for air and the semiconductor material.
  • a material whose refractive index is different for air and the semiconductor material.
  • (porous) silica, tantalum-, zirconium- and titanium oxide may be used.
  • the above-mentioned lattice type may comprise at least one of a hexagonal, triangular and cubic structure. Many types of crystal structures are known in the art, which all may be used in the LED according to embodiments of the invention.
  • the above-mentioned low order structures (hexagonal structure etc.) are not intended to limit the scope of the invention to these types. Any low order structure may be employed. High order structures, such as sunflower structure or different types of Archimedean tiling may also be used. Even random crystals structures may be applicable.
  • the lattice type provides a non- rotational symmetric far field pattern. An example is quasi-crystals like the spiral structure in the sunflower, which are suitable for applications like beamers, LCD back lights and car front lights. It shall, however, be observed that, in some embodiments, is it preferred to have a rotationally symmetric far field pattern. This is the case for applications like spot lights.
  • Fig. 1 shows a cross-sectional view of a light emitting diode according to an embodiment of the present invention
  • Fig. 2 shows a cross-sectional view of a light emitting diode according to another embodiment of the present invention
  • Fig. 3 shows a cross-sectional view of a light emitting diode according to a further embodiment of the present invention
  • Fig. 4 shows a cross-sectional view of a light emitting diode according to yet another embodiment of the present invention
  • Fig. 5 shows a cross-sectional view of a light emitting diode according to a still further embodiment of the present invention
  • Fig. 6a and 6b show far field patters from a respective type of photonic crystal
  • Fig. 6d and 6e show two photonic crystals, being different with respect to at least one lattice parameter
  • Fig. 6c and Fig. 6f illustrate interference between different far fields originating from areas having photonic crystals of different types, as shown in Fig. 6a-6b and Fig. 6d-6e;
  • Fig. 7 shows a top, plan view of a light emitting diode according to another embodiment of the present invention.
  • Fig. 8 shows a top, plan view of a light emitting diode according to a further embodiment of the present invention.
  • Fig. 1 there is shown a working example of the LED 1 according to the present invention.
  • the LED 1 comprises, from bottom to top, non-conducting barriers 51 for electrically separating sub-electrodes 41-45, a P-type semiconductor layer 30 connected to said sub-electrodes 41-45, an active region 4 for generation of light, an N-type layer 21 connected to a electrode arrangement (not shown) and light guiding segments 201, 202 and 203.
  • the light guiding segments may be color filters of different colors or all light guiding segments may have the same color. In practice, there may be more than three segments, but for reasons of clarity only three segments are shown.
  • the LED 1, in Fig. 1 comprises secondary optics (not shown) for projection of the light from the segments.
  • the secondary optics is used to reproduce (image) an enlarged image of the light from selected segments.
  • image By selecting different sets of segments, it is possible to project simple signs or short texts onto, for example, a wall or alike.
  • the LED 1 may be seen as a very tiny and simple display device or projector apparatus.
  • no light is wasted, i.e. all light that is generated is used for the projection of the desired sign or text.
  • the light guiding segments 201, 202, 203 are larger than the sub-electrodes 41-45.
  • FIG. 2 A more common example of a LED similar to the one shown in Fig. 1, may be described with reference to Fig. 2.
  • the light guiding means 301-305 and the sub-electrodes 41-45. This enables the light guiding segments to be controlled more intuitively, since activation of one sub-electrode causes one light guiding segment (which may be regarded as a pixel in this case) to be activated.
  • the light guiding segments (201-203, 301-305) are smaller than the sub-electrodes 41-45. Thereby, the activation of one sub-electrode will cause more than one (for example, two or one and a half) light guiding segment to be activated. Any number of light guiding means may be activated as required by a specific application.
  • Fig. 2 is, hence, used to describe different examples of the present LED.
  • a luminescent material at the surface of the LED, there has been applied a luminescent material at each segment 301-305.
  • each segment has been applied with a different material, it is also possible to apply the same material to some segments. In general, at least two types of materials are required.
  • the LED 1 further comprises semiconductor layers, electrodes and an active region as described for the LED of Fig. 1. It is to be noted that the sub-electrodes 41-45 are aligned with the segments 301-305. The size and shape of the sub-electrodes are matched to the size and shape of the segments comprising luminescent materials.
  • a 1 W standard LED with a surface area of 1 mm 2 is used as starting point.
  • the surface area of the LED is divided into 25 segments.
  • Each segment is about 200x200 ⁇ m 2 for a lmm 2 LED surface.
  • the segments are grouped into a first group of 12 segments and a second group of 13 segments.
  • the first group of segments are associated with a corresponding group of sub- electrodes.
  • the second group of segments are associated with another corresponding group of sub-electrodes.
  • Onto the segments of the first group photonic crystals, which confine light into a 30 degree cone, are applied. In this manner, a spotlight of the light from the segments of the first group is implemented.
  • the segments of the second group are unmodified.
  • the light from the first group of segments may be used for reading and the light from the second group of segments may be used for illumination of a room as a whole.
  • the light from the first and the second group of segments may be activated in order to obtain an illumination that combines the illumination of the light from the two groups of segments, comprising PCs.
  • the examples in Fig. 3 to Fig. 8 relates to an LED, wherein the light guiding means comprises photonic crystals.
  • the electrode is divided into sub-electrodes in all these examples, even though it is not shown in Fig. 6a to Fig. 6f, Fig. 7 and Fig. 8. In manner, in which the electrode (furthest away from the light emitting surface) is separated into sub- electrodes is shown in, for instance, Fig. 3 and Fig. 4.
  • Fig. 3 there is shown an exemplifying light emitting diode 1 (LED), which comprises a semiconductor stack of epitaxial layers 21, 30.
  • the semiconductor stack has a total thickness of 400 nm and is manufactured from GaN.
  • the stack comprises (from bottom to top according to Fig. 3) electrode layer 41-45, a P-type semiconductor layer 30 in connection with the electrode layer 41-45, an active region 4, an N-type layer 21, a second electrode (or electrode arrangement, not shown) in connection with the N-type layer 21 and a light emitting area 6.
  • the electrode layer is horizontally separated into a number of sub-electrodes 41, 42, 43, 44, 45.
  • the bottom, reflective electrode layer is divided into a number of sub-electrode layers 41, 42, 43, 44, 45, being separated by non-conducting barriers 51.
  • the barriers 51 extend from, and including, the bottom sub-electrodes 41-45 up to, but not including, the P-type layer 30.
  • the photonic crystals 101, 102 and 103 in Fig. 3 are formed as quantum wells
  • the thickness of the photonic crystal layer 101, 102 may be increased such as to extend into the active region and/or into the P-type layer.
  • the size (diameter) of the holes for photonic crystal type 101 in the N-type layer 21 is, in this example, approximately 100 nm and the depth of the holes is 250 nm. In this example, it is preferred to use essentially the entire depth of the N-type layer for the holes and poles, making the photonic crystals 101, 102 and 103. It is, hence, preferred that the photonic crystal layer extends as far into the N-type layer as possible.
  • an N-type layer of less than one micrometer in thickness, comprising a photonic crystal structure of approximately the same depth, is desired.
  • the lattice pitch of the photonic crystal of type 101 is 470 nm in Fig. 3.
  • the size (diameter) of the holes for the other type of photonic crystal 102 in the N-type layer 21 is 120 nm and the depth of the holes is 250 nm.
  • the lattice pitch of the photonic crystal of type 101 is 490 nm.
  • the lattice type of photonic crystals 101, 102 is hexagonal lattice type (for other examples the lattice type may be different).
  • the areas of the photonic crystals have hexagonal shape and have a diameter of approximately 50 ⁇ m in diameter (not shown). Even though not shown, the number of photonic crystals areas on the LED in Fig. 1 is, normally, in the range from 50 to 2500 for a light emitting surface of 1 mm 2 .
  • the sub-electrodes 41-45 are individually controllable for activation of different portions of the active region. Consequently, different photonic crystal structures will be activated when different portions of the active region are activated. In this manner, the far field pattern of the entire LED 1 may be controlled dynamically
  • the photonic crystals have a size and shape that matches the size and shape of the sub-electrodes 41-45.
  • the photonic crystals are aligned such that each photonic crystal corresponds to a matching sub-electrode. Since each sub-electrode, having a corresponding active region portion, may be activated individually, an increased control of the far field pattern is provided.
  • the N-type layer 21 comprises the PCs, but it shall be noted that the photonic crystal layer may extend into the active region and, possibly, into the P-type layer 30 as well.
  • the LED 1 further comprises a P-type layer, which is horizontally separated into a number of sub-regions 31-35. In other words, the P-type layer is divided into a number of sub-P-type layers 31, 32, 33, 34, 35, being separated by nonconducting barriers 51.
  • the barriers 51 extend from, and including the bottom electrode up to, but not including, the active region 4.
  • the sub-electrodes 41-45 (and the corresponding sub-regions of the P-type layer) are individually controllable for activation of different portions of the active region. As in the previous working example, different photonic crystal structures will be activated when different portions of the active region is activated. Thereby, the far field pattern of the entire LED 1 may be controlled dynamically.
  • the sub-electrodes may be grouped into, for example, three groups, which groups are individually controllable for selecting a far field pattern associated with a respective group of sub-electrodes and their corresponding photonic crystals.
  • Figs. 6a to 6f illustrate how different far field patterns from areas, comprising photonic crystals of different types add-up (interfere or combine) for improving uniformity of the overall far field, resulting from the light emitted from the entire LED.
  • Fig. 6a and Fig. 6b there are shown two different far field patterns, wherein each pattern corresponds to a respective type of photonic crystal.
  • the indications -90, 0 and 90 refer to degrees from a normal axis of an LED, placed at the center of the semi circle in Fig. 6a and Fig. 6b, respectively.
  • the far field pattern in Fig. 6a is brighter closer to the periphery of the far field pattern as indicated by the lines originating from a center of the semi circle, whereas the far field pattern in Fig. 6b is brighter near the center of the far field pattern, similarly as indicated by the lines originating from a center of another semi circle.
  • the far field patterns of Fig. 6a and 6b are associated with a respective type of phonic crystal, which are shown in Fig. 6d and Fig. 6e, respectively.
  • the photonic crystals differ from each other with respect to the lattice type.
  • the photonic crystal in Fig. 6d is formed of a triangular lattice type (structure) and the photonic crystal in Fig. 6e is formed of a hexagonal lattice type. Other combinations of lattice types, pitch or fill fraction are also possible.
  • Fig. 6f an LED, comprising the photonic crystals, which are illustrated in
  • Fig. 6d and 6e is shown.
  • the orientation of at least some photonic crystals, as illustrated in Fig. 6d, is different.
  • only two types of photonic crystals are shown, but in order to obtain a far field pattern with an increased uniformity it is preferred to use more than two types of photonic crystals.
  • the exact number of photonic crystal types required depends on the application and the required homogeneity of the far field. For many applications between 5 and 15 different photonic crystals will be enough to obtain the required far field emission.
  • the far field pattern resulting from the light emitted by the LED according to Fig. 6f, is displayed in Fig. 6c. It can be seen that the far field pattern of the photonic crystal of Fig. 6d and the far field pattern of the photonic crystal of Fig. 6e together generates a far field pattern that is more uniform than the individual far field patterns shown in Fig. 6a and Fig. 6b.
  • the brighter areas of the different far field patterns are non-coincidental, i.e. the brighter areas of the patterns are non-overlapping or out of phase.
  • the introduced, improved, overall far field pattern of the LED arising from the positions of the areas, which generate different emission patterns in the far field, is decoupled from the location of the individual photonic crystals. Hence, the individual properties of the photonic crystals of the LED are not visible in the overall far field pattern of the LED.
  • a top, plan view of a light emitting diode 1 according to an embodiment of the invention.
  • the light emitting surface is partitioned into several sub-segments 61, 62, 63, 64, each sub-segment comprising a photonic crystal 103, 104, 105, 106, which completely covers the corresponding sub-segment.
  • all sub-segments and all photonic crystals have not been assigned a reference numeral.
  • For a light emitting surface 6 of approximately 1 mm 2 it is preferred to partition the light emitting surface (light emitting area) 6 into approximately 100 to 2500 sub-segments.
  • the photonic crystals of the different sub-segments have different properties (lattice parameters).
  • the sub-segments (or areas) having small dots denote photonic crystals with a certain diameter of the holes (or poles)
  • the sub-segments having small circles denote photonic crystals with another certain diameter of the holes (or poles), i.e. different fill fractions.
  • the vertically lined areas denote photonic crystals with a specific orientation
  • the areas lined in other directions denote photonic crystals with another specific orientation.
  • the different photonic crystals are rotated with respect to its neighbors (all other lattice parameters are the same for the photonic crystals).
  • the far field pattern exhibits rotational asymmetry, i.e. the far field pattern should, for example, not comprise concentric circles centered with respect to a center of the far field pattern.
  • the far field pattern is hexagonal, it may be rotated such that it is identical to the appearance before rotation, i.e. a rotational symmetry angle exists for that particular far field pattern.
  • the different sub-segments 101, 102 comprising photonic crystals, are spaced apart from each other.
  • An area 200 between the photonic crystals is formed. Light may be emitted from the area 200. It is preferred that the area 200 is as small as possible, or even non-existent (as in Fig. 3).
  • the different sub-segments 101, 102 are in the shape of squares, but other shapes, such as rectangular or hexagonal may also be possible to use. It is even possible to use a more or less random polygonal shape of the photonic crystals.
  • roughened areas R disposed in between the photonic crystals 101, 102, which photonic crystals 101, 102 are different from each other with respect to at least one lattice parameter.

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Abstract

La présente invention a pour objet une diode semi-conductrice électroluminescente (1) qui comprend une première et une seconde électrode pour appliquer une tension à travers une région active (4) afin de produire de la lumière, et une surface émettrice de lumière (6) pour émettre de la lumière. La diode électroluminescente (LED) comprend en outre des premier et second moyens de guidage de la lumière (201, 202, 203). En outre, une première électrode secondaire (41, 42, 43, 44, 45) est associée au premier moyen de guidage de la lumière (201, 202, 203) et une seconde électrode secondaire (41, 42, 43, 44, 45) est associée au second moyen de guidage de la lumière (201, 202, 203). Les première et seconde électrodes secondaires (41, 42, 43, 44, 45) peuvent être commandées individuellement grâce à l'application d'une tension respectivement à chacune des première et seconde électrodes secondaires (41, 42, 43, 44, 45).
PCT/IB2008/055302 2007-12-18 2008-12-15 Diode électroluminescente Ceased WO2009081325A1 (fr)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3385990A1 (fr) * 2017-04-06 2018-10-10 ACER Incorporated Dispositifs d'affichage et leurs procédés de fabrication
WO2019125690A1 (fr) * 2017-12-22 2019-06-27 Illumina, Inc. Dispositifs de détection de lumière à deux filtres et procédés associés
WO2019170226A1 (fr) * 2018-03-07 2019-09-12 Photonik Inkubator Gmbh Dispositif à semi-conducteur destiné à émettre un rayonnement électromagnétique et procédé de fabrication pour ledit dispositif
CN110504280A (zh) * 2018-05-16 2019-11-26 财团法人工业技术研究院 显示阵列
KR20200040299A (ko) * 2017-08-30 2020-04-17 오스람 오엘이디 게엠베하 광전자 반도체 부품을 제조하기 위한 방법, 및 광전자 반도체 부품
US11515299B2 (en) 2018-05-16 2022-11-29 Industrial Technology Research Institute Method for manufacturing display array
US11837628B2 (en) 2018-05-16 2023-12-05 Industrial Technology Research Institute Display array

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0855751A2 (fr) * 1997-01-24 1998-07-29 International Business Machines Corporation Diode électroluminescente
WO2001037351A1 (fr) * 1999-11-19 2001-05-25 Cree Lighting Company Diode electroluminescente / laser a solide multicolore
US20020139987A1 (en) * 2001-03-29 2002-10-03 Collins William David Monolithic series/parallel led arrays formed on highly resistive substrates
US20050173714A1 (en) * 2004-02-06 2005-08-11 Ho-Shang Lee Lighting system with high and improved extraction efficiency
US20060062540A1 (en) * 2004-09-22 2006-03-23 Mesophotonics Limited Light emitting diode structures
WO2007034367A1 (fr) * 2005-09-19 2007-03-29 Koninklijke Philips Electronics N.V. Dispositif photoemetteur de couleur variable

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0855751A2 (fr) * 1997-01-24 1998-07-29 International Business Machines Corporation Diode électroluminescente
WO2001037351A1 (fr) * 1999-11-19 2001-05-25 Cree Lighting Company Diode electroluminescente / laser a solide multicolore
US20020139987A1 (en) * 2001-03-29 2002-10-03 Collins William David Monolithic series/parallel led arrays formed on highly resistive substrates
US20050173714A1 (en) * 2004-02-06 2005-08-11 Ho-Shang Lee Lighting system with high and improved extraction efficiency
US20060062540A1 (en) * 2004-09-22 2006-03-23 Mesophotonics Limited Light emitting diode structures
WO2007034367A1 (fr) * 2005-09-19 2007-03-29 Koninklijke Philips Electronics N.V. Dispositif photoemetteur de couleur variable

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* Cited by examiner, † Cited by third party
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US10727270B2 (en) 2017-04-06 2020-07-28 Acer Incorporated Display devices and methods of manufacturing the same
US10475850B2 (en) 2017-04-06 2019-11-12 Acer Incorporated Display devices and methods of manufacturing the same
KR20200040299A (ko) * 2017-08-30 2020-04-17 오스람 오엘이디 게엠베하 광전자 반도체 부품을 제조하기 위한 방법, 및 광전자 반도체 부품
KR102421288B1 (ko) * 2017-08-30 2022-07-18 오스람 오엘이디 게엠베하 광전자 반도체 부품을 제조하기 위한 방법, 및 광전자 반도체 부품
JP2021504672A (ja) * 2017-12-22 2021-02-15 イラミーナ インコーポレーテッド 二フィルタ光検出デバイスおよびそれに関連する方法
KR102300442B1 (ko) 2017-12-22 2021-09-09 일루미나, 인코포레이티드 2개의 필터 광 검출 디바이스 및 그에 관한 방법
WO2019125690A1 (fr) * 2017-12-22 2019-06-27 Illumina, Inc. Dispositifs de détection de lumière à deux filtres et procédés associés
US10649145B2 (en) 2017-12-22 2020-05-12 Illumina, Inc. Two-filter light detection devices and methods related to same
CN109959642B (zh) * 2017-12-22 2022-05-24 伊鲁米那股份有限公司 双过滤片光检测设备及与其相关的方法
TWI700839B (zh) * 2017-12-22 2020-08-01 美商伊路米納有限公司 雙濾光器光偵測裝置及其相關的方法
RU2737847C1 (ru) * 2017-12-22 2020-12-03 Иллюмина, Инк. Устройства детектирования света с двойной фильтрацией и относящиеся к ним способы
CN109959642A (zh) * 2017-12-22 2019-07-02 伊鲁米那股份有限公司 双过滤片光检测设备及与其相关的方法
AU2018390429B2 (en) * 2017-12-22 2021-06-17 Illumina, Inc. Two-filter light detection devices and methods related to same
KR20200020685A (ko) * 2017-12-22 2020-02-26 일루미나, 인코포레이티드 2개의 필터 광 검출 디바이스 및 그에 관한 방법
KR20210113421A (ko) * 2017-12-22 2021-09-15 일루미나, 인코포레이티드 2개의 필터 광 검출 디바이스 및 그에 관한 방법
US11256033B2 (en) 2017-12-22 2022-02-22 Illumina, Inc. Two-filter light detection devices and methods related to same
KR102381842B1 (ko) 2017-12-22 2022-04-01 일루미나, 인코포레이티드 2개의 필터 광 검출 디바이스 및 그에 관한 방법
WO2019170226A1 (fr) * 2018-03-07 2019-09-12 Photonik Inkubator Gmbh Dispositif à semi-conducteur destiné à émettre un rayonnement électromagnétique et procédé de fabrication pour ledit dispositif
JP2022171868A (ja) * 2018-03-07 2022-11-11 テクニシェ・ユニヴェルシタット・ブラウンシュヴァイク・コールペルシャフト デス オフレントリーヘン レクツ 電磁波を放射する半導体デバイス及びその製造方法
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US11967666B2 (en) 2018-03-07 2024-04-23 Technische Universität Braunschweig Korperschaft Des Offentlichen Rechts Semiconductor device for transmitting electromagnetic radiation and method for production thereof
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