Robust Group III Light Emitting Diode for High Reliability in Standard Packaging Applications
AssigneeCree, Inc.
InventorJohn A. Edmond
Life of this patent
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Abstract
Abstract of the Disclosure A physically robust light emitting diode is disclosed that offers high-reliability in standard packaging and that will withstand high temperature and high humidity conditions. The diode comprises a Group III nitride heterojunction diode with a p-type Group III nitride contact layer, an ohmic contact to the p-type contact layer, and a sputter-deposited silicon nitride composition passivation layer on the ohmic contact. A method of manufacturing a light emitting diode and an LED lamp incorporating the diode are also disclosed.
Claims33
A light emitting diode comprising:
- a Group III nitride active region;
- a p-type Group III nitride contact layer on said active region;
- a metal contact on said p-type contact layer;
- a sputter-deposited silicon nitride composition passivation layer on said metal contact.
A light emitting diode according to Claim 2 wherein said silicon nitride composition is silicon-poor.
A light emitting diode according to Claim 1 wherein said contact layer comprises gallium nitride and said metal contact is thin enough to be semi-transparent.
A light emitting diode according to Claim 3 wherein said passivation layer has a thickness of about 1000 Å.
A light emitting diode according to Claim 1 and further comprising:
- a silicon carbide substrate;
- an ohmic contact to said substrate;
- and
- a buffer structure on said substrate for supporting said active region.
A light emitting diode according to Claim 6 wherein said substrate is n-type and said ohmic contact to said substrate is nickel.
A light emitting diode according to Claim 1 wherein said metal contact and said passivation layer are substantially nonreactive with one another.
A light emitting diode according to Claim 1 wherein said metal contact and said passivation layer adhere well to one another.
A light emitting diode according to Claim 1 wherein said metal contact is selected from the group consisting of platinum, palladium, gold, a combination of titanium and gold, a combination of platinum and gold, a combination of titanium, platinum and gold, and a combination of platinum and indium tin oxide.
A light emitting diode according to Claim 1 wherein said metal contact comprises platinum.
A display that incorporates a plurality of light emitting diodes according to Claim 1.
A pixel comprising:
- a light emitting diode according to Claim 1 that emits in the blue portion of the visible spectrum;
- a red light emitting diode;
- and
- a green light emitting diode.
An LED lamp comprising:
- a plastic lens;
- and
- a light emitting diode;
- said light emitting diode comprising,
- a Group III nitride heterojunction diode with a p-type Group III nitride contact layer;
- a metal contact to said p-type contact layer;
- and
- a passivation layer on said metal contact;
- wherein said passivation layer comprises a sputter-deposited silicon nitride composition.
An LED lamp according to Claim 14 wherein said contact layer comprises gallium nitride.
A light emitting diode comprising:
- a silicon carbide substrate;
- a buffer structure on said substrate;
- an n-type gallium nitride epitaxial layer on said buffer structure;
- an n-type Group III-nitride active region;
- a p-type gallium nitride contact layer on said active region;
- an ohmic contact on said substrate;
- a platinum contact on said p-type gallium nitride contact layer;
- and
- a sputter-deposited silicon nitride composition passivation layer on said platinum contact.
A light emitting diode according to claim 16 wherein said silicon carbide substrate is a single crystal having a polytype selected from the group consisting of the 3C, 4H, 6H, and 15R polytypes of silicon carbide.
A light emitting diode according to claim 16 wherein said substrate is n-type.
A light emitting diode according to claim 16 wherein said active region is selected from the group consisting of single heterostructures, double heterostructures, single quantum wells and multiple quantum wells.
A light emitting diode according to claim 16 wherein the sputter-deposited silicon nitride composition is selected from the group consisting of Si3N4, non-stoichiometric compositions of silicon and nitrogen, and combinations thereof.
A method of manufacturing a light emitting diode comprising:
- forming a buffer layer on a substrate;
- forming an active region on the buffer layer;
- forming a p-type contact layer on the active region;
- forming a metal contact on the contact layer;
- and
- sputter-depositing a layer of a silicon nitride composition on the metal contact.
A method according to claim 22 comprising forming the contact layer from Mg-doped GaN.
A method according to claim 23 comprising depositing the silicon nitride composition layer at a temperature greater than 200 ºC.
A method according to claim 24 comprising depositing the silicon nitride composition at a temperature greater than 400 ºC.
A method according to claim 22 comprising depositing the silicon nitride composition at a sputter rate of about 45 Å/min.
A method according to claim 22 comprising depositing the silicon nitride omposition layer to a thickness of about 1000 Åthick.
A method according to claim 22 comprising sputter depositing the silicon nitride composition layer at an ambient pressure of less than about 20 mTorr.
A method according to claim 22 comprising is sputter depositing the silicon nitride composition layer at an ambient pressure of about 10-20 mTorr.
A method according to claim 22 comprising sputter depositing the silicon nitride composition layer at an ambient pressure of about 80-100 mTorr.
A method according to claim 22 comprising sputter depositing the silicon nitride composition layer at room temperature and at an ambient pressure of about 80-100 mTorr.
A method according to claim 22 comprising sputter depositing the silicon nitride composition layer using a pulsed DC power supply.
A method according to claim 22 comprising depositing the silicon nitride composition layer to a thickness of about 1000 Å.
Dependencies are inferred from the claim text.