High reflectivity p-contacts for group lll-nitride light emitting diodes

• US 20060186552A1
• Filed: 03/23/2006
• Published: 08/24/2006
• Est. Priority Date: 04/07/2004
• Status: Abandoned Application

• Current Assignee: Gelcore (General Electric Company)
• Original Assignee: Gelcore (General Electric Company)
• Inventors: Venugopalan, Hari S.
• Application Number:
  US11/387,157
• Publication Number:
  US 20060186552A1
• Time in Patent Office: Days
• US Class Current: 257/778
• CPC Class Codes: H01L 2224/05001 Internal layers
• CPC Class Codes: H01L 2224/05023 the whole internal layer protruding from the surface
• CPC Class Codes: H01L 2224/0508 being stacked
• CPC Class Codes: H01L 2224/05124 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05144 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/05155 Nickel [Ni] as principal constituent
• CPC Class Codes: H01L 2224/05166 Titanium [Ti] as principal constituent
• CPC Class Codes: H01L 2224/05169 Platinum [Pt] as principal constituent
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05644 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/05655 Nickel [Ni] as principal constituent
• CPC Class Codes: H01L 2224/05666 Titanium [Ti] as principal constituent
• CPC Class Codes: H01L 2224/05669 Platinum [Pt] as principal constituent
• CPC Class Codes: H01L 2224/0603 Bonding areas having different sizes, e.g. different heights or widths
• CPC Class Codes: H01L 2224/06102 the bonding areas being at different heights
• CPC Class Codes: H01L 2224/14 of a plurality of bump connectors
• CPC Class Codes: H01L 2224/1703 Bump connectors having different sizes, e.g. different diameters, heights or widths
• CPC Class Codes: H01L 24/03 Manufacturing methods
• CPC Class Codes: H01L 24/05 of an individual bonding area
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2933/0016 : relating to electrodes
• CPC Class Codes: H01L 33/20 : with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/32 : containing nitrogen
• CPC Class Codes: H01L 33/38 : with a particular shape
• CPC Class Codes: H01L 33/405 : Reflective materials

Abstract

A flip-chip LED device (10) includes a plurality of group III-nitride semiconductor layers (22) defining a p/n junction and including a top p-type group III-nitride layer (28), and a p-contact (30, 30′, 30″) for flip-chip bonding the top p-type group III-nitride layer. The p-contact includes an aluminum layer (32) disposed on the top p-type group III-nitride layer (28), and an interface layer (40, 66, 72, 80) disposed between the aluminum layer and the top p-type group III-nitride layer. The interface layer reduces a contact resistance between the aluminum layer (32) and the top p-type group III-nitride layer (28). The interface layer comprises one or more group III-nitride layers.

Claims

1. A flip-chip LED device comprising:

a plurality of group III-nitride semiconductor layers defining a p/n junction and including a top p-type group III-nitride layer; and

a p-contact for flip-chip bonding the top p-type group III-nitride layer, the p-contact including;

an aluminum layer disposed on the top p-type group III-nitride layer, and

an interface layer disposed between the aluminum layer and the top p-type group III-nitride layer and reducing a contact resistance therebetween, the interface layer comprising one or more group III-nitride layers.

2. The flip-chip LED device as set forth in claim 1, wherein the p-contact further comprises:

a bonding stack including at least one layer disposed adjacent to the aluminum layer, the bonding stack being adapted for flip-chip bonding the flip-chip LED device to an associated bonding pad.

3. The flip-chip LED device as set forth in claim 1, wherein the interface layer of the p-contact is formed by a process comprising:

exposing the top p-type group III-nitride layer to hydrochloric acid; and

subsequent to the exposing to hydrochloric acid, exposing the top p-type group III-nitride layer to a piranha solution.

4. The flip-chip LED device as set forth in claim 1, wherein the top p-type group III-nitride layer is a p-GaN layer, and the interface layer of the p-contact comprises:

a p-InGaN layer.

5. The flip-chip LED device as set forth in claim 1, wherein the interface layer of the p-contact comprises:

a tunnel junction.

6. The flip-chip LED device as set forth in claim 5, wherein the interface layer of the p-contact further comprises:

an n-type group III-nitride layer disposed between the tunnel junction and the aluminum layer of the p-contact.

7. The flip-chip LED device as set forth in claim 1, wherein the interface layer of the p-contact comprises:

a degenerately doped p-type group III-nitride layer adjacent the top p-type group III-nitride layer; and

a degenerately doped n-type group III-nitride layer adjacent the degenerately doped p-type group III-nitride layer.

8. The flip-chip LED device as set forth in claim 7, wherein the interface layer of the p-contact further comprises:

an n-type group III-nitride layer adjacent the degenerately doped n-type group III-nitride layer.