Enhanced light extraction in leds through the use of internal and external optical elements
First Claim
1. A light emitting diode (LED) with enhanced light extraction structures, comprising:
- an LED structure having;
an epitaxially grown p-type layer;
an epitaxially grown n-type layer; and
an epitaxially grown active layer between said p-type and n-type layers;
a first spreader layer adjacent to said LED structure;
a second spreader layer adjacent to said LED structure, opposite said first spreader layer; and
light extraction structures disposed integral with said LED, said light extraction structures providing surfaces to allow light trapped within said LED to disperse, reflect and/or refract out of said LED.
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Abstract
This invention describes new LEDs having light extraction structures on or within the LED to increase its efficiency. The new light extraction structures provide surfaces for reflecting, refracting or scattering light into directions that are more favorable for the light to escape into the package. The structures can be arrays of light extraction elements or disperser layers. The light extraction elements can have many different shapes and are placed in many locations to increase the efficiency of the LED over conventional LEDs. The disperser layers provide scattering centers for light and can be placed in many locations as well. The new LEDs with arrays of light extraction elements are fabricated with standard processing techniques making them highly manufacturable at costs similar to standard LEDs. The new LEDs with disperser layers are manufactured using new methods and are also highly manufacturable.
61 Citations
40 Claims
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1. A light emitting diode (LED) with enhanced light extraction structures, comprising:
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an LED structure having;
an epitaxially grown p-type layer;
an epitaxially grown n-type layer; and
an epitaxially grown active layer between said p-type and n-type layers;
a first spreader layer adjacent to said LED structure;
a second spreader layer adjacent to said LED structure, opposite said first spreader layer; and
light extraction structures disposed integral with said LED, said light extraction structures providing surfaces to allow light trapped within said LED to disperse, reflect and/or refract out of said LED. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A light emitting diode with enhanced light extraction, comprising
a p-type layer; -
an n-type layer;
an active layer between said p-type and n-type layers wherein either said p-type or n-type layer is a top layer and the other said layer is a bottom layer;
a first spreader layer adjacent to said bottom layer;
a second spreader layer on said top layer;
respective electrical contacts on said spreader layers so that a bias applied across said contacts causes said active layer to emit light;
a substrate adjacent to said first spreader layer; and
light extraction structures integral with said layers, running parallel to said layers and substantially covering said LED, said light extraction structures providing surfaces to allow light trapped within said LED to disperse, reflect and/or refract out of said LED. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A light emitting diode (LED) with enhanced light extraction, comprising:
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an LED structure having;
an epitaxially grown p-type layer;
an epitaxially grown n-type layer; and
an epitaxially grown active layer between said p-type and n-type layers;
a reflective layer deposited on said LED structure;
a second spreader layer on said reflective layer;
a submount on said second spreader layer;
a first spreader layer adjacent said LED structure, opposite said reflective layer;
a bias applied across said first and second spreader layers causing said active layer to emit light, said substrate becoming the primary light emission surface; and
light extraction structures integral with said LED, said light extraction structures running parallel to said LED structure and substantially covering the area of said LED. - View Dependent Claims (34, 35, 36)
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37. A method for growing a light emitting diode having an internal disperser layer to enhance light extraction, comprising:
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placing a substrate in a reactor for growing semiconductor materials;
growing a first semiconductor layer on said substrate, said first layer having a rough surface;
stopping growth of said semiconductor layer;
growing a disperser layer of semiconductor material on said roughened layer, said disperser layer having a different index of refraction than said first layer;
growing a second layer on said disperser layer, said second layer having a similar index of refraction as said first layer; and
growing a semiconductor light emitting structure on said second layer. - View Dependent Claims (38, 39)
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40. A method for manufacturing an AlInGaN light emitting diode with an internal disperser layer to enhance light extraction, comprising:
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placing a substrate in a reactor for growing semiconductor materials;
growing uncoalesced islands of material made of AlxInyGa1-x-yN, 0≦
x≦
1, 0≦
y≦
1, on said substrate;
stopping the growth of islands;
depositing a disperser layer on said uncoalesced islands, said disperser layer having a different index of refraction from said highly doped GaN material;
growing a layer of material made of AlxInyGa1-x-yN, 0≦
x≦
1, 0≦
y≦
1, on said disperser layer, said layer having a smooth surface; and
growing a light emitting structure on said layer.
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Specification