Vertical LED with current-guiding structure

• US 8,546,818 B2
• Filed: 02/21/2012
• Issued: 10/01/2013
• Est. Priority Date: 06/12/2007
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc., Semileds Optoelectronics Company Limited (SemiLEDs Inc)
• Original Assignee: Semileds Optoelectronics Company Limited (SemiLEDs Inc)
• Inventors: CHU, JIUNN-YI, Fan, Feng-Hsu, Cheng, Chao-Chen, Chang, Yuan-Hsiao, Cheng, Hao-Chun, Liu, Wen-Huang, Chu, Chen-Fu
• Primary Examiner(s): Soward, Ida M
• Application Number:
  US13/401,446
• Publication Number:
  US 20120146083A1
• Time in Patent Office: 588 Days
• Field of Search: 257/13, 257/79, 257/94, 257/E33.001, 257/E33.002, 257/E33.012, 257/E33.013, 257/E33.014
• US Class Current: 257/79
• CPC Class Codes: H01L 2224/0603 Bonding areas having different sizes, e.g. different heights or widths
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/4903 Connectors having different sizes, e.g. different diameters
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 27/15 including semiconductor components having potential barriers, specially adapted for light emission
• 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 2924/00014 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 33/14 with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/385 the electrode extending at least partially onto a side surface of the semiconductor body
• CPC Class Codes: H01L 33/40 Materials therefor
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating

Abstract

Techniques for controlling current flow in semiconductor devices, such as LEDs are provided. For some embodiments, a current-guiding structure may be provided including adjacent high and low contact areas. For some embodiments, a second current path (in addition to a current path between an n-contact pad and a substrate) may be provided. For some embodiments, both a current-guiding structure and second current path may be provided.

Claims

1. A light emitting diode (LED) device comprising:

an n-electrode;

an LED stack comprising an n-type semiconductor layer in electrical contact with the n-electrode, an active layer configured to emit light, and a p-type semiconductor layer on the active layer; and

a p-electrode in electrical contact with the active layer configured as an electrically conductive current guiding structure for guiding current through the active layer, the p-electrode comprising a high contact resistance area aligned with the n-electrode configured to provide a first current path to an area of the active layer aligned with the n-electrode and to provide a second current path to at least one area of the active layer not aligned with the n-electrode, with the first current path providing less electrical current than the second current path,

wherein the p-electrode comprises a barrier metal layer and a reflective layer on the barrier metal layer having a space aligned with the high contact resistance area.

2. The LED device of claim 1 wherein the reflective layer comprises a first material and the barrier metal layer comprises a second material, with the first material having a lower electrical resistance than the second material.

3. A light emitting diode (LED) device comprising:

an n-electrode;

an LED stack comprising an n-type semiconductor layer in electrical contact with the n-electrode, an active layer configured to emit light, and a p-type semiconductor layer on the active layer; and

a p-electrode in electrical contact with the active layer configured as an electrically conductive current guiding structure for guiding current through the active layer, the p-electrode comprising a high contact resistance area aligned with the n-electrode configured to provide a first current path to a first area of the active layer and to provide a second current path to at least one second area of the active layer, with the first current path providing less electrical current than the second current path,

wherein the p-electrode comprises a barrier metal layer aligned with the active layer and a reflective layer on the barrier metal layer having a space aligned with the high contact resistance area.

4. The LED device of claim 3 wherein an electrical resistance of the high resistance area is at least double an electrical resistance of the low resistance area.

5. The LED device of claim 3 further comprising a substrate on the p-electrode.

6. The LED device of claim 3 wherein the LED comprises a vertical light-emitting diode (VLED).

7. A light emitting diode (LED) device comprising:

an LED stack comprising a first-type semiconductor layer, an active layer on the first-type semiconductor layer configured to emit light, and a second-type semiconductor layer on the active layer;

a first electrode in electrical contact with the first-type semiconductor layer covering a first area of the active layer; and

a second electrode in electrical contact with the active layer configured as an electrically conductive current guiding structure for guiding current through the active layer, the second electrode comprising a barrier metal layer and a reflective layer on the barrier metal layer having a space, the barrier metal layer comprising a high contact resistance area aligned with the space in the reflective layer configured to provide a first current path to the first area of the active layer and to provide a second current path to at least one second area of the active layer, with the first current path providing less electrical current than the second current path.

8. The light emitting diode (LED) device of claim 7 wherein the reflective layer comprises a deposited layer patterned to include the space.

9. The light emitting diode (LED) device of claim 7 wherein the reflective layer comprises a first material and the barrier metal layer comprises a second material, with the first material having a lower electrical resistance than the second material.