Surface plasmon enhanced light emitting diode and method of operation for the same
First Claim
1. An improvement in a light emitting diode comprising:
- an active light emitting semiconductor layer having a first and second parallel surface;
an optically reflecting layer disposed on said first surface of said semiconductor layer; and
an optically reflecting grating disposed on said second surface of said active light emitting semiconductor layer, said grating having a pattern which is selected so that surface plasmon waves are coupled through said grating.
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Accused Products
Abstract
The emission properties of light-emitting diodes are enhanced by coupling to surface plasmons. The semiconductor emitter layer of the light-emitting diode is thinner than λ/2 and is sandwiched between two metal films. A periodic pattern is defined in the top semitransparent metal layer by lithography with the result that it efficiently couples out the light emitted from the semiconductor and simultaneously enhances the spontaneous emission rate. Extraction efficiencies of up to 35% and Purcell factors of up to 4.5 are obtainable. Photoluminescence intensities of up to 46 times higher in fabricated structures compared to unprocessed wafers are obtained. The increased light emission is due to an increase in the efficiency and an increase in the pumping intensity resulting from trapping of pump photons within the microcavity.
191 Citations
20 Claims
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1. An improvement in a light emitting diode comprising:
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an active light emitting semiconductor layer having a first and second parallel surface;
an optically reflecting layer disposed on said first surface of said semiconductor layer; and
an optically reflecting grating disposed on said second surface of said active light emitting semiconductor layer, said grating having a pattern which is selected so that surface plasmon waves are coupled through said grating. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An improved light emitting diode comprising:
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an active light emitting semiconductor layer having a first and second parallel and opposing surface;
an conductive layer disposed on said first surface of said semiconductor layer; and
an conductive grating disposed on said second surface of said active light emitting semiconductor layer, said conductive layer and conductive grating with said semiconductor layer therebetween defining a cavity, said grating having a pattern which is selected so that surface plasmon waves within said cavity are coupled through said grating. - View Dependent Claims (13, 14, 15, 16)
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17. A method of improving emission from a light emitting diode comprising:
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providing an active light emitting semiconductor layer having a first and second parallel surface;
providing an optically reflecting layer disposed on said first surface of said semiconductor layer;
providing an optically reflecting grating with a selected pattern defined therein, said grating being disposed on said second surface of said active light emitting semiconductor layer; and
coupling surface plasmon waves through said optically reflecting grating, said selected pattern characterized by said surface plasmon waves being coupled therethrough. - View Dependent Claims (18, 19, 20)
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Specification