III-nitride light-emitting device with increased light generating capability

• US 6,486,499 B1
• Filed: 12/22/1999
• Issued: 11/26/2002
• Est. Priority Date: 12/22/1999
• Status: Expired due to Term

• Current Assignee: Agilent Technologies Europe BV (Agilent Technologies, Inc.), Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Kish, Fred A. Jr., Wierer, Jonathan J. Jr., Steigerwald, Daniel A., Tan, Tun S, Krames, Michael R, Rajkomar, Pradeep
• Primary Examiner(s): Meier, Stephen D.
• Application Number:
  US09/469,657
• Time in Patent Office: 1,070 Days
• Field of Search: 257/81, 257/103
• 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-nitride 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;

an 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 the lateral cross-sectional area of the p conductive interface and n conductive interface is at least 15% of an area of the p electrode.

2. 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.

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

4. A light-emitting device, as defined in claim 1, further including a barrier layer interposing a portion of the one of the p and n-electrodes and a portion of the corresponding conductive interface.

5. A light-emitting device, as defined in claim 1, further including an intermetal dielectric material covering portions of one of the p and n electrodes.

6. A light-emitting device, as defined in claim 1, wherein an area of the active region is greater than 0.16 mm².

7. A light-emitting device, as defined in claim 1, wherein the p-electrode has an absorption less than 25%.

8. A light-emitting device, as defined in claim 7, wherein the p-electrode is comprised of Ni and Ag.

9. A light-emitting device, as defined in claim 7, wherein the p-electrode is comprised of Au, NiO_x, and Al.

10. A light-emitting device, as defined in claim 1, wherein at least one of the layers comprising the heterostructure is textured.

11. A light-emitting device, as defined in claim 1, wherein the specific contact resistivity of the p-electrode is less than 10⁻

2 Ω

cm².

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

13. A light-emitting device, as defined in claim 12, wherein the submount is silicon.

14. A light-emitting device, as defined in claim 12, wherein the submount includes a circuit consisting of at least one diode electrically connected in anti-parallel with the first light emitting unit.

15. A light-emitting device, as defined in claim 12, wherein the submount includes a circuit consisting of at least one photodetector in the path of light emitted from the light-emitting device.

16. A light-emitting device, as defined in claim 12, wherein the submount has a shape selected from a group including hexagons, circles, squares, and octagons.

17. A light-emitting device, as defined in claim 1, wherein:

the III-nitride heterostructure further comprises a second light emitting unit and a trench; and

the first and second light emitting units are positioned on opposing sides of the trench and are electrically connected in series.

18. A light-emitting device, as defined in claim 7, wherein the p-electrode comprises Ag.