SEMICONDUCTOR LIGHT-EMITTING DEVICES HAVING CONCAVE MICROSTRUCTURES PROVIDING IMPROVED LIGHT EXTRACTION EFFICIENCY AND METHOD FOR PRODUCING SAME
First Claim
1. A light emitting device comprising:
- at least one n-type layer;
at least one p-type layer disposed adjacent said at least one n-type layer; and
a microlens layer disposed adjacent said at least one p-type layer, said microlens layer comprising a plurality of concave microstructures.
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Accused Products
Abstract
A conventional semiconductor LED is modified to include a microlenslayer over its light-emitting surface. The LED may have an active layer including at least one quantum well layer of InGaN and GaN. The microlens layer includes a plurality of concave microstructures that cause light rays emanating from the LED to diffuse outwardly, leading to an increase in the light extraction efficiency of the LED. The concave microstructures may be arranged in a substantially uniform array, such as a close-packed hexagonal array. The microlens layer is preferably constructed of curable material, such as polydimethylsiloxane (PDMS), and is formed by soft-lithography imprinting by contacting fluid material of the microlens layer with a template bearing a monolayer of homogeneous microsphere crystals, to cause concave impressions, and then curing the material to fix the concave microstructures in the microlens layer and provide relatively uniform surface roughness.
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Citations
21 Claims
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1. A light emitting device comprising:
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at least one n-type layer; at least one p-type layer disposed adjacent said at least one n-type layer; and a microlens layer disposed adjacent said at least one p-type layer, said microlens layer comprising a plurality of concave microstructures. - View Dependent Claims (2, 3, 4, 5, 8, 9)
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6. The light emitting device of claim 6, wherein said microlens layer is formed by imprinting fluid PDMS with a template comprising a plurality of microsphere crystals, and curing the imprinted PDMS.
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7. The light emitting device of claim 7, wherein said template comprises an array an array of SiO2 microsphere crystals.
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10. A light emitting device comprising:
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a substrate; a first contact layer disposed over said substrate, said first contact layer comprising a GaN-based material having a first conduction type; an active layer disposed over said first contact layer, said active layer comprising at least one GaN-based material; a second contact layer disposed over said active layer, said second contact layer comprising a GaN-based material having a second conduction type opposite to the first conduction type; and a microlens layer disposed over said second contact layer, said microlens layer comprising a plurality of concave microstructures. - View Dependent Claims (11, 12, 13)
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14. A method for improving light extraction efficiency of a light emitting device, the method comprising:
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providing a light emitting device having a top emission surface; depositing a layer of fluid curable material on the top emission surface; imprinting the layer of fluid material by contacting the layer of fluid material with a template comprising a plurality of microspheres; heat treating the imprinted layer of fluid material to provide a microlens layer of cured material comprising a plurality of concave microstructures; and removing the template from contact with the microlens layer of cured material. - View Dependent Claims (15, 16, 17, 18)
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19. An optoelectronic device comprising:
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a multilayer semiconductor structure comprising a GaN layer and an active region, the active region comprising at least one quantum well layer of InGaN and GaN, wherein the electron quantum well layers and hole quantum well layer form a first quantum well stage, and wherein the active region comprises a plurality of quantum well stages adjacent to each other having the same structure as the first quantum well stage; and a microlens layer disposed over the multilayer semiconductor, said microlens layer comprising a plurality of concave microstructures.
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20. A method for making an optoelectronic device, the method comprising:
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providing a multilayer semiconductor structure comprising a GaN layer and an active region, the active region comprising at least one quantum well layer of InGaN and GaN, wherein the electron quantum well layers and hole quantum well layer form a first quantum well stage, and wherein the active region comprises a plurality of quantum well stages adjacent to each other having the same structure as the first quantum well stage; and providing a microlens layer comprising a plurality of concave microstructures over the multilayer semiconductor.
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21. A method for generating optical emission from an optoelectronic device, the method comprising:
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providing a GaN layer and an active region, the active region comprising at least one quantum well layer of InGaN and GaN, wherein the electron quantum well layers and hole quantum well layer form a first quantum well stage, and wherein the active region comprises a plurality of quantum well stages adjacent to each other having the same structure as the first quantum well stage; providing a microlens layer comprising a plurality of concave microstructures over the active region; and exciting the active region to produce optical emission through the microlens layer.
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Specification