III-Nitride Light-emitting device with increased light generating capability

• US 6,521,914 B2
• Filed: 03/29/2002
• Issued: 02/18/2003
• Est. Priority Date: 12/22/1999
• Status: Expired due to Term

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Tan, Tun S, Kish, Fred A. Jr., Wierer, Jonathan J. Jr., Steigerwald, Daniel A., Krames, Michael R, Rajkomar, Pradeep
• Primary Examiner(s): Meier, Stephen D.
• Application Number:
  US10/112,175
• Publication Number:
  US 20020171087A1
• Time in Patent Office: 326 Days
• Field of Search: 257/99, 257/81
• US Class Current: 257/81
• CPC Class Codes: G09G 2360/148 the light being detected by light detection means within each pixel
• 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 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05572 the external layer extending out of an opening
• CPC Class Codes: H01L 2224/06051 Bonding areas having different shapes
• CPC Class Codes: H01L 2224/14 of a plurality of bump connectors
• CPC Class Codes: H01L 24/05 of an individual bonding area
• CPC Class Codes: H01L 24/06 of a plurality of bonding areas
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H01L 33/641 characterized by the materials
• CPC Class Codes: H01L 33/647 the elements conducting electric current to or from the semiconductor body

Abstract

The present invention is an inverted III-nitride light-emitting device (LED) with enhanced total light generating capability. A large area device has an n-electrode that interposes the p-electrode metallization to provide low series resistance. The p-electrode metallization is opaque, highly reflective, and provides excellent current spreading. The p-electrode at the peak emission wavelength of the LED active region absorbs less than 25% of incident light per pass. A submount may be used to provide electrical and thermal connection between the LED die and the package. The submount material may be Si to provide electronic functionality such as voltage-compliance limiting operation. The entire device, including the LED-submount interface, is designed for low thermal resistance to allow for high current density operation. Finally, the device may include a high-refractive-index (n>1.8) superstrate.

Claims

1. A light-emitting device comprising:

a heterostructure of III-V material comprising a first light emitting unit;

the first light emitting unit comprising an active region, an n-type layer and a p-type layer;

an opaque p-electrode, attached to the p-type layer;

n-electrode, attached to the n-type layer, interposing portions of the p-electrode; and

a p-conductive interface and an n-conductive interface, the p-conductive interface affixed to the p-electrode and the n-conductive interface affixed to the n-electrode;

wherein one of the p-conductive interface and the n-conductive interface includes one or more portions elongated along a first direction.

2. A light emitting device, as defined in claim 1, wherein the column V material is Nitrogen.

3. A light-emitting device, as defined in claim 1, wherein the lateral cross-sectional area of one of the p-conductive interface and the n-conductive interface is at least 15% of an area of the p-electrode.

4. A light-emitting device, as defined in claim 1, wherein the lateral cross-sectional area of one of the p-conductive interface and the n-conductive interface is at least 50% of an area of the p-electrode.

5. A light-emitting device, as defined in claim 1, further including a dielectric material covering a portion of one of the p-conductive interface and the n-conductive interface.

6. A light-emitting device, as defined in claim 1, wherein one of the p-conductive interface and the n-conductive interface covers the corresponding one of the p-electrode and n-electrode substantially uniformly in an area.

7. A light-emitting device, as defined in claim 1, wherein one of the p-conductive interface and the n-conductive interface covers a region of the corresponding one of the p-electrode and n-electrode and the covered region comprises portions of substantially equal area.

8. A light-emitting device, as defined in claim 1, further comprising a submount electrically coupled to the p-electrode via the p-conductive interface and to the n-electrode via the n-conductive interface.

9. A light-emitting device, as defined in claim 8, wherein the heterostructure has a plane and the submount has a plane, and the plane of the heterostructure is substantially parallel to the plane of submount.

10. A light-emitting device, as defined in claim 8, wherein the submount comprises a submount conductive interface, including one or more portions elongated along a second direction, wherein the first direction of the one of the p-conductive interface and the n-conductive interface is substantially parallel to the second direction of the submount conductive interface.

11. A light-emitting device, as defined in claim 8, wherein the submount comprises a submount conductive interface, the submount conductive interface including a group of regions, wherein an elongated portion of the one of the p-conductive interface and n-conductive interface is electrically coupled to a subgroup of the group of regions of the submount conductive interface.

12. A light-emitting device, as defined in claim 11, wherein the regions of the group of regions of the submount conductive interface are arranged in a substantially periodic array.

13. A light-emitting device, as defined in claim 1, wherein the area of one of the p-conductive interface and the n-conductive interface is larger than the submount conductive interface.

14. A light-emitting device, as defined in claim 8, further comprising:

an n-interconnect connecting the n-electrode to the submount; and

a p-interconnect connecting the p-electrode to the submount.

15. A light-emitting device, as defined in claim 14, wherein the n-interconnect and p-interconnect are selected from the group consisting of solder, elemental metals, metal alloys, semiconductor-metal alloys, thermally and electrically conductive pastes, thermally and electrically conductive compounds, epoxies, eutectic joints, Au stud-bumps, and solder bumps.

16. A light-emitting device, as defined in claim 14, wherein the layout of at least one of the p-conductive interface, the n-conductive interface, and the submount conductive interface is selected to decrease the thickness of at least one of the p-interconnect and the n-interconnect.

17. A light-emitting device, as defined in claim 14, wherein the layout of at least one of the p-conductive interface, the n-conductive interface, and the submount conductive interface is selected to increase the area of at least one of the p-interconnect and the n-interconnect.

18. A light-emitting device, as defined in claim 14, wherein the lateral cross sectional area of one of the p-interconnect and the n-interconnect is larger than 15% of an area of the p-electrode.

19. A light-emitting device, as defined in claim 14, wherein the lateral cross sectional area of one of the p-interconnect and the n-interconnect is larger than 50% of an area of the p-electrode.