Light emitting diodes with improved light extraction efficiency
First Claim
1. A light emitting device having a stack of layers including semiconductor layers comprising an active region, said device comprising:
- a transparent optical element bonded to said stack by a bond at an interface disposed between said optical element and said stack, wherein said optical element is bonded to a surface of said stack, wherein a smallest ratio of a length of a base of said optical element to a length of said surface is greater than one.
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Accused Products
Abstract
Light emitting devices with improved light extraction efficiency are provided. The light emitting devices have a stack of layers including semiconductor layers comprising an active region. The stack is bonded to a transparent optical element having a refractive index for light emitted by the active region preferably greater than about 1.5, more preferably greater than about 1.8. A method of bonding a transparent optical element (e.g., a lens or an optical concentrator) to a light emitting device comprising an active region includes elevating a temperature of the optical element and the stack and applying a pressure to press the optical element and the light emitting device together. A block of optical element material may be bonded to the light emitting device and then shaped into an optical element. Bonding a high refractive index optical element to a light emitting device improves the light extraction efficiency of the light emitting device by reducing loss due to total internal reflection. Advantageously, this improvement can be achieved without the use of an encapsulant.
136 Citations
64 Claims
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1. A light emitting device having a stack of layers including semiconductor layers comprising an active region, said device comprising:
a transparent optical element bonded to said stack by a bond at an interface disposed between said optical element and said stack, wherein said optical element is bonded to a surface of said stack, wherein a smallest ratio of a length of a base of said optical element to a length of said surface is greater than one. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
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31. A light emitting device having a stack of layers including semiconductor layers comprising an active region, said device comprising:
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a transparent optical element bonded to said stack by a bond at an interface disposed between said optical element and said stack; and
a transparent bonding layer comprising a material different from a material forming the optical element, the transparent bonding layer being disposed between said optical element and a surface of said stack and bonding said optical element to said stack. - View Dependent Claims (46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60)
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61. A light emitting device having a stack of layers including semiconductor layers comprising an active region, said device comprising:
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an optical element bonded to said stack, the optical element comprising one of sapphire and SiC; and
a first contact and a second contact electrically coupled to apply a voltage across said active region;
wherein said stack of layers comprises at least one III-Nitride semiconductor layer and said first contact and said second contact are disposed on a same side of said stack.
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62. A light emitting device having a stack of layers including semiconductor layers comprising an active region, said device comprising:
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an optical element bonded to said stack;
wherein said optical element comprises one of sapphire and SiC. - View Dependent Claims (63, 64)
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Specification