Ultra-thin ohmic contacts for p-type nitride light emitting devices
View Patent ↗A semiconductor based Light Emitting Device (LED) can include a p-type nitride layer and a metal ohmic contact, on the p-type nitride layer. The metal ohmic contact can have an average thickness of less than about 25 Å and a specific contact resistivity less than about 10 −3 ohm-cm 2 .
1. A semiconductor based Light Emitting Device (LED) comprising:
a p-type nitride layer; and
a metal ohmic contact, on the p-type nitride layer, the metal ohmic contact comprising an average thickness of less than about 5 Å and a specific contact resistivity less than about 10 −3 ohm-cm 2 .
2. An LED according to claim 1 wherein the metal ohmic contact covers about 100% of the p-type nitride layer.
3. An LED according to claim 1 wherein the metal ohmic contact covers less than 100% of the p-type nitride layer measured via an Auger analysis of the metal ohmic contact.
4. An LED according to claim 2 wherein the metal ohmic contact comprises Pt.
5. An LED according to claim 1 wherein the metal ohmic contact covers less than about 70% of the p-type nitride layer measured via an Auger analysis of the metal ohmic contact.
6. An LED according to claim 5 wherein the metal ohmic contact covers a portion of the p-type nitride layer and a remaining portion of the p-type nitride layer is un-covered by the metal ohmic contact.
7. An LED according to claim 1 wherein the metal ohmic contact covers less than about 47% of the p-type nitride layer measured via an Auger analysis of the metal ohmic contact.
8. An LED according to claim 7 wherein a normalized transmissivity of the metal ohmic contact comprises at least about 92% at a measurement wavelength of about 350 nm.
9. An LED according to claim 7 wherein the metal ohmic contact covers a portion of the p-type nitride layer and a remaining portion of the p-type nitride layer is un-covered by the metal ohmic contact.
10. An LED according to claim 1 wherein the metal ohmic contact comprises an average thickness less than about 3 Å.
11. An LED according to claim 10 wherein the metal ohmic contact covers less than about 28% of the p-type nitride layer measured via an Auger analysis of the metal ohmic contact.
12. An LED according to claim 11 wherein a normalized transmissivity of the metal ohmic contact comprises about 94% to about 96% at a measurement wavelength of about 350 nm.
13. An LED according to claim 11 wherein the metal ohmic contact covers a portion of the p-type nitride layer and a remaining portion of the p-type nitride layer is un-covered by the metal ohmic contact.
14. An LED according to claim 1 wherein the metal ohmic contact comprises an average thickness of about 1 Å.
15. An LED according to claim 14 wherein the metal ohmic contact covers less than about 13% of the p-type nitride layer measured via an Auger analysis of the metal ohmic contact.
16. An LED according to claim 15 wherein a normalized transmissivity of the metal ohmic contact comprises more than about 98% at a measurement wavelength of about 350 nm.
17. An LED according to claim 15 wherein the metal ohmic contact covers a portion of the p-type nitride layer and a remaining portion of the p-type nitride layer is un-covered by the metal ohmic contact.
18. An LED according to claim 1 wherein the metal ohmic contact comprises platinum, rhodium, zinc oxide, palladium, palladium oxide, titanium, nickel/gold, nickel oxide/gold, nickel oxide/platinum and/or titanium/gold.
19. An LED according to claim 1 further comprising:
a reflector beneath the metal ohmic contact configured to reflect light emitted through the metal ohmic contact back toward the metal ohmic contact.
20. An LED according to claim 19 wherein the reflector comprises a conductive reflector configured to provide current spreading.