Nitride based led with a p-type injection region

• US 20070181895A1
• Filed: 03/16/2005
• Published: 08/09/2007
• Est. Priority Date: 03/18/2004
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Nagai, Hideo
• Granted Patent: US 7,420,218 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• 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 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/385 the electrode extending at least partially onto a side surface of the semiconductor body
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

An LED chip (2) is composed of a p-GaN layer (10), an n-GaN layer (14), and an MQW emission layer (12) that is sandwiched between the GaN layers (10 and 14). Each layer is made of a GaN semiconductor. Light exits the LED chip (2) through the n-GaN layer (14). A p-electrode (16) of the LED chip (2) has a surface profile (24B) defined by a plurality of columnar projections (24A) formed in a uniformly distributed relation on the surface facing toward the p-GaN layer (10). The p-electrode (16) is in contact with the p-GaN layer (10) at the top surface of each projection (24A).

Claims

1. A semiconductor light emitting device, comprising:

a semiconductor multilayer structure composed of a p-semiconductor layer, a quantum well emission layer, and an n-semiconductor layer each made of a nitride semiconductor and laminated in the stated order, light from the emission layer exiting through the n-semiconductor layer; and

a p-electrode facing and in ohmic contact with the p-semiconductor layer, wherein

the p-semiconductor layer has an intensive-injection region into which an electric current from the p-electrode is injected more intensively than another region, the intensive-injection region spanning substantially across an entire surface of the p-semiconductor layer.

2. The semiconductor light emitting device according to claim 1, wherein

the intensive-injection region is realized by a contact structure of the p-electrode with the p-semiconductor layer.

3. The semiconductor light emitting device according to claim 2, wherein

the p-electrode has, on a surface facing toward the p-semiconductor layer, a plurality of projections or depressions that are distributed substantially uniformly, and

the p-electrode is in contact with the p-semiconductor layer at a top surface thereof.

4. The semiconductor light emitting device according to claim 3, wherein

the p-electrode is made of a metal that reflects light from the emission layer toward the n-semiconductor layer.

5. The semiconductor light emitting device according to claim 4, further comprising

an insulator disposed on a recessed surface of the p-electrode to fill a space between the recessed surface and the p-semiconductor layer.

6. The semiconductor light emitting device according to claim 5, wherein

the insulator is made of a material transparent to light emitted by the emission layer.

7. The semiconductor light emitting device according to claim 5, wherein

the insulator has a substantially same refractive index as a refractive index of the nitride semiconductor forming the p-semiconductor layer.

8. The semiconductor light emitting device according to claim 3, wherein

a drive current for driving the semiconductor light emitting device is maintained within such a range that results in an average current density not exceeding 50 A/cm², the average current density being calculated by dividing the drive current by an area of a main surface of the emission layer,

the p-electrode faces substantially entirely of the main surface of the emission layer, and

a ratio between the top and recessed surfaces of the p-electrode is determined so that an electric current flowing through the top surface of the p-electrode measures at least 100 A/cm² in current density.

9. The semiconductor light emitting device according to claim 3, wherein

the p-semiconductor layer has, on a surface facing toward the p-electrode, a high-defect region in which lattice defects are localized and a low-defect region formed adjacent to the high-defect region, and

the p-electrode is in contact with the low-defect region of the p-semiconductor layer.

10. The semiconductor light emitting device according to claim 1, wherein

the intensive-injection region is realized by a contact structure of the p-semiconductor layer with the p-electrode.

11. The semiconductor light emitting device according to claim 10, wherein

the semiconductor multilayer structure has, on a surface facing toward the p-electrode, a plurality of projections or depressions that are distributed substantially uniformly, and

the semiconductor multilayer structure is in contact with the p-electrode at a top surface of the p-semiconductor layer.

12. The semiconductor light emitting device according to claim 11, wherein

the p-electrode is made of a metal that reflects light from the emission layer toward the n-semiconductor layer.

13. The semiconductor light emitting device according to claim 11, wherein

a recessed surface of the semiconductor multilayer structure is present in the n-semiconductor layer.

14. The semiconductor light emitting device according to claim 11, wherein

the semiconductor multilayer structure has, on the surface facing toward the p-electrode, a high-defect region in which lattice defects are localized and a low-defect region formed adjacent to the high-defect region, and

the low-defect region is present at the top surface of the semiconductor multilayer structure.

15. The semiconductor light emitting device according to claim 1, further comprising:

a base substrate supporting the semiconductor multilayer structure from a direction of the p-semiconductor layer; and

a phosphor film disposed on a main surface of the semiconductor multilayer structure facing away from the base substrate, the phosphor film extending across a side surface of the semiconductor multilayer structure to the base substrate.

16. A lighting module comprising:

a mounting substrate; and

the semiconductor light emitting device as defined in claim 1.

17. A lighting device comprising, as a light source, the lighting module as defined in claim 16.

18. A surface mounting device comprising:

a substrate;

a semiconductor light emitting device as defined in claim 1, and mounted on the substrate; and

a resin molding the semiconductor device.

19. A dot-matrix display device comprising:

semiconductor light emitting devices as defined in claim 1 and are arranged in a matrix.