Light emitter with metal-oxide coating
First Claim
1. A light emitting device comprising:
- a substrate portion having a top surface and a bottom surface;
a back reflector formed on the bottom surface of the substrate portion;
a light emitting portion formed on the top surface of the substrate portion, the light emitting portion having a flat top surface;
a coating layer portion comprising a first coating layer of ITO and a second coating layer, wherein the first coating layer is in direct physical contact with the flat top surface of the light emitting portion and has a contiguous flat top surface, and the second coating layer is in direct physical contact with the first coating layer and has a top surface with a three dimensional pattern formed on the flat top surface of the first coating layer, the three dimensional pattern chosen from a group consisting of ribs, cylinders, polygon shaped ribs, triangular shaped ridges, hemispherical shaped mounds, horizontal cylindrical shaped ribs, ellipsoids, hemispheres, rectilinear trenches, rectilinear solids, cones, angled cylinders, angled hemispheres, angled ellipsoids, angled rectilinear trenches, angled solids and angled cones and wherein element to element spacing may be uniform or not, wherein the second coating layer has an index of refraction greater than 2 and an optical loss factor less than 0.2 and is chosen from a group consisting of metal oxides, silicon carbide, Ta2O5, Nb2O5, TiO2, and their non-stoichiometric mixtures; and
a metal contact formed in direct contact with the first coating layer, the three dimensional pattern formed on the flat top surface of the first coating layer has a top portion higher than a top surface of the metal contact.
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Accused Products
Abstract
A light emitting device based on a AlInGaN materials system wherein a coating is used to improve the extraction of light from a device. A coating has a very low optical loss and an index of refraction greater than 2. In a preferred embodiment the coating is made from Ta2O5, Nb2O5, TiO2, or SiC and has a thickness between about 0.01 and 10 microns. A surface of a coating material may be textured or shaped to increase its surface area and improve light extraction. A surface of the coating material can also be shaped to engineer the directionality of light escaping the layer. A coating can be applied directly to a surface or multiple surfaces of a light emitting device or can be applied onto a contact material. A coating may also serve as a passivation or protection layer for a device.
35 Citations
18 Claims
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1. A light emitting device comprising:
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a substrate portion having a top surface and a bottom surface; a back reflector formed on the bottom surface of the substrate portion; a light emitting portion formed on the top surface of the substrate portion, the light emitting portion having a flat top surface; a coating layer portion comprising a first coating layer of ITO and a second coating layer, wherein the first coating layer is in direct physical contact with the flat top surface of the light emitting portion and has a contiguous flat top surface, and the second coating layer is in direct physical contact with the first coating layer and has a top surface with a three dimensional pattern formed on the flat top surface of the first coating layer, the three dimensional pattern chosen from a group consisting of ribs, cylinders, polygon shaped ribs, triangular shaped ridges, hemispherical shaped mounds, horizontal cylindrical shaped ribs, ellipsoids, hemispheres, rectilinear trenches, rectilinear solids, cones, angled cylinders, angled hemispheres, angled ellipsoids, angled rectilinear trenches, angled solids and angled cones and wherein element to element spacing may be uniform or not, wherein the second coating layer has an index of refraction greater than 2 and an optical loss factor less than 0.2 and is chosen from a group consisting of metal oxides, silicon carbide, Ta2O5, Nb2O5, TiO2, and their non-stoichiometric mixtures; and a metal contact formed in direct contact with the first coating layer, the three dimensional pattern formed on the flat top surface of the first coating layer has a top portion higher than a top surface of the metal contact. - View Dependent Claims (2, 3, 4)
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5. A light emitting device comprising:
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a substrate portion having a top surface and a bottom surface; a back reflector formed on the bottom surface of the substrate portion; a light emitting portion formed on the top surface of the substrate portion and including a gallium nitride layer which has a flat top surface; a contiguous transparent conductive layer formed in direct contact with the flat top surface of the gallium nitride layer and having a top surface; a coating layer formed in direct physical contact with the top surface of the transparent conductive layer and having a top surface with a three dimensional pattern formed on the top surface of the transparent conductive layer, the coating layer having an index of refraction greater than 2 and an optical loss factor less than 0.2 and including a material selected from a group consisting of metal oxides, Ta2O5, Nb2O5, TiO2, and their non-stoichiometric mixtures; and a metal contact formed in direct contact with the transparent conductive layer, the three dimensional pattern formed on the top surface of the transparent conductive layer has a top portion higher than a top surface of the metal contact. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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12. A light emitting device comprising:
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a substrate portion having a top surface and a bottom surface; a back reflector formed on the bottom surface of the substrate portion; a light emitting portion formed on the top surface of the substrate portion and including a gallium nitride layer which has a top surface; a contiguous transparent conductive layer formed in direct contact with the top surface of the gallium nitride layer and having a top surface; a coating layer formed in direct physical contact with the top surface of the transparent conductive layer and having a top surface with a three dimensional pattern formed on the transparent conductive layer, the coating layer having an index of refraction greater than 2 and an optical loss factor less than 0.2 and including a material selected from a group consisting of metal oxides, Ta2O5, Nb2O5, TiO2, and their non-stoichiometric mixtures; and a metal contact formed in direct contact with the transparent conductive layer, the three dimensional pattern formed on the top surface of the transparent conductive layer has a top portion higher than a top surface of the metal contact. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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Specification