Nitride semiconductor LED with embossed lead-out surface
First Claim
Patent Images
1. A semiconductor light emitting device comprising:
- a light emitting portion made of a nitride compound semiconductor;
a light lead-out surface on which an embossment is formed to improve the external quantum efficiency of light emitted from said light emitting portion;
a nitride compound semiconductor layer; and
a transparent electrode;
said embossment being formed on one surface of said nitride compound semiconductor layer, and said transparent electrode being formed on said one surface of said nitride compound semiconductor layer.
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Abstract
Efficiency of leading out light released from an active layer, i.e. the external quantum efficiency, can be improved remarkably by processing a light lead-out surface to have an embossment. A layer containing a p-type dopant like magnesium (Mg) is deposited near the surface of a p-type GaN layer to diffuse it there, and a p-side electrode is made on the p-type GaN layer after removing the deposited layer. This results in ensuring ohmic contact with the p-side electrode, preventing exfoliation of the electrode and improving the reliability.
357 Citations
13 Claims
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1. A semiconductor light emitting device comprising:
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a light emitting portion made of a nitride compound semiconductor;
a light lead-out surface on which an embossment is formed to improve the external quantum efficiency of light emitted from said light emitting portion;
a nitride compound semiconductor layer; and
a transparent electrode;
said embossment being formed on one surface of said nitride compound semiconductor layer, and said transparent electrode being formed on said one surface of said nitride compound semiconductor layer. - View Dependent Claims (2, 3, 4)
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5. A semiconductor light emitting device comprising:
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a light emitting portion made of a nitride compound semiconductor;
a light lead-out surface on which an embossment is formed to improve the external quantum efficiency of light emitted from said light emitting portion;
a nitride compound semiconductor layer; and
a transparent electrode;
said embossment being formed on one surface of said nitride compound semiconductor layer, and said transparent electrode being formed on said one surface of said nitride compound semiconductor layer;
wherein said embossment includes a plurality of cylindrical lens-shaped convex portions.
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6. A semiconductor light emitting device comprising:
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a light emitting portion made of a nitride compound semiconductor;
a light lead-out surface on which an embossment is formed to improve the external quantum efficiency of light emitted from said light emitting portion;
a nitride compound semiconductor layer; and
a transparent electrode;
said embossment being formed on one surface of said nitride compound semiconductor layer, and said transparent electrode being formed on said one surface of said nitride compound semiconductor layer;
wherein said embossment includes a hemispherical convex portion.
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7. A semiconductor light emitting device comprising:
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a light emitting portion made of a nitride compound semiconductor;
a light lead-out surface on which an embossment is formed to improve the external quantum efficiency of light emitted from said light emitting portion;
a nitride compound semiconductor layer;
a transparent electrode;
a nitride compound semiconductor layer having an even surface; and
a transparent electrode formed on said nitride compound semiconductor layer;
said embossment being formed on one surface of said nitride compound semiconductor layer, and said transparent electrode being formed on said one surface of said nitride compound s conductor layer and said embossment being formed on a surface of said transparent electrode.
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8. A semiconductor light emitting device comprising:
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a light emitting portion made of a nitride compound semiconductor;
a light readout surface on which an embossment is formed to improve the external quantum efficiency of light emitted from said light emitting portion;
a nitride compound semiconductor layer having an even surface;
a transparent electrode formed on said even surface of said nitride compound semiconductor layer; and
a light lead-out layer formed on said transparent electrode and having a transparency;
said embossment being formed on a surface of said light lead-out layer. - View Dependent Claims (9, 10)
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11. A semiconductor light emitting device comprising:
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a light emitting portion made of a nitride compound semiconductor;
a light lead-out surface on which an embossment is formed to improve the external quantum efficiency of light emitted from said light emitting portion;
a substrate made of a material other than nitride compound semiconductor; and
a reflector reflecting a light emitted from said light emitting portion to release said light outside through said substrate;
wherein said reflector also serves as an electrode injecting a current into said light emitting portion; and
said light emitting portion being provided on one side of said substrate, and said embossment being provided on another side of said substrate.
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12. A semiconductor light emitting device comprising:
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a light emitting portion made of a nitride compound semiconductor;
a light lead-out surface on which an embossment is formed to improve the external quantum efficiency of light emitted from said light emitting portion;
a substrate made of nitride compound semiconductor; and
a reflector reflecting a light emitted from said light emitting portion to release said light outside through said substrate;
wherein said reflector also serves as an electrode injecting a current into said light emitting portion; and
said light emitting portion being provided on one side of said substrate, and said embossment being provided on another side of said substrate.
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13. A semiconductor light emitting device comprising:
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a substrate;
a mesa provided on one side of said substrate and including a light emitting portion;
a reflector provided on said mesa and reflecting a light emitted from said light emitting portion to release said light outside through said substrate;
a light-transmissive portion provided on a side surface of said mesa;
a reflective layer coated on a surface of said light-transmissive portion; and
an embossment provided on another side of said substrate to improve the external quantum efficiency of lights emitted from said light emitting portion, said reflective layer reflecting a light leaking sideward from said light emitting portion of said mesa so as to release the light outside through said substrate.
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Specification