NITRIDE-BASED SEMICONDUCTOR LIGHT EMITTING DEVICE AND METHOD FOR FABRICATING SAME

• US 20090020781A1
• Filed: 04/14/2008
• Published: 01/22/2009
• Est. Priority Date: 07/19/2007
• Status: Active Grant

• Current Assignee: Foxsemicon Integrated Technology Incorporated
• Original Assignee: Foxsemicon Integrated Technology Incorporated
• Inventors: LAI, CHIH-MING
• Granted Patent: US 7,595,514 B2
• Time in Patent Office: Days
• US Class Current: 257/103
• CPC Class Codes: H01L 33/16 with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

An exemplary nitride-based semiconductor light emitting device includes a substrate, a nitride-based multi-layered structure epitaxially formed on the substrate, a first-type electrode and a second-type electrode. The multi-layered structure includes a first-type layer, an active layer, and a second-type layer. The multi-layered structure has a developed mesa structure which at least includes the second-type layer and the active layer and whereby the first-type layer is partially exposed to form an exposed portion. The mesa structure has a roughened top surface and a plurality of roughened side surfaces adjoining the top surface. A crystal growth orientation of the multi-layered structure intersects with <0001 > crystal orientation thereof. The first-type electrode and the second-type electrode respectively come into ohmic contact with the first-type layer and the second-type layer.

Claims

1. A nitride-based semiconductor light emitting device, comprising:

a substrate;

a nitride-based multi-layered structure epitaxially formed on the substrate, the multi-layered structure including a first-type layer, an active layer and a second-type layer arranged along a direction away from the substrate in the order written, the second-type layer and the active layer cooperatively forming a developed mesa structure, the first-type layer having an exposed portion, the mesa structure having a top surface facing away from the substrate and a plurality of side surfaces adjoining the top surface, wherein a crystal growth orientation of the multi-layered structure intersects with <

0001>

crystal orientation thereof, and the top surface and the side surfaces are roughened surfaces;

a first-type electrode formed on the exposed portion and brought into ohmic contact with the first-type layer; and

a second-type electrode formed on the top surface and brought into ohmic contacted with the second-type layer.

2. The nitride-based semiconductor light emitting device of claim 1, wherein the substrate is a single crystal plate, the single crystal plate has a crystal face on which the multi-layered structure epitaxially formed, the crystal growth orientation matches with a crystal orientation of the crystal face.

3. The nitride-based semiconductor light emitting device of claim 2, wherein the single crystal plate is made from a material selected from the group consisting of sapphire, silicon carbide, silicon, gallium arsenide, lithium aluminate, magnesium oxide, zinc oxide, gallium nitride, aluminum nitride and indium nitride.

4. The nitride-based semiconductor light emitting device of claim 1, wherein the first-type layer, the active layer and the second-type layer are made from group III-nitride compound materials.

5. The nitride-based semiconductor light emitting device of claim 1, wherein surface atoms of the multi-layered structure comprises metal atoms and nitrogen atoms.

6. The nitride-based semiconductor light emitting device of claim 1, wherein the crystal growth orientation of the multi-layered structure is substantially perpendicular to the <

0001>

crystal orientation.

7. The nitride-based semiconductor light emitting device of claim 1, wherein the roughened surfaces are formed using a wet etching process.

8. The nitride-based semiconductor light emitting device of claim 1, wherein the top surface and the side surfaces have a plurality of recesses formed thereon.

9. A method for fabricating a nitride-based semiconductor light emitting device, comprising:

providing a substrate;

epitaxially growing a nitride-based multi-layered structure on the substrate, the multi-layered structure comprising a first-type layer, an active layer and a second-type layer arranged along a direction away from the substrate in the order written, wherein a crystal growth orientation of the multi-layered structure intersects with <

0001>

crystal orientation thereof;

patterning the multi-layered structure to form a mesa structure thereon and whereby the first-type layer is partially exposed to form an exposed portion, the mesa structure having a top surface facing away from the substrate and a plurality of side surfaces adjoining the top surface;

forming a first-type electrode and a second-type electrode respectively on the exposed portion and the top surface, so as to respectively come into ohmic contact with first-type layer and the second-type layer; and

wet etching the patterned multi-layered structure so as to roughen the top surface and the side surfaces of the mesa structure.

10. The method of claim 9, wherein the substrate is a single crystal plate, the single crystal plate has crystal face on which the multi-layered epitaxially grown, and the crystal growth orientation matches with a crystal orientation of the crystal face.

11. The method of claim 9, wherein the first-type layer, the active layer and the second-type layer are made from group III-nitride compound materials.

12. The method of claim 9, wherein the crystal growth orientation is substantially perpendicular to the <

0001>

crystal orientation.

13. The method of claim 9, wherein the wet etching is performed by an acid etching solution containing phosphoric acid and sulfuric acid or an alkaline etching solution containing potassium hydroxide.

14. The method of claim 11, further comprising a step of:

irradiating the mesa structure by an electromagnetic wave during the wet etching step, an energy of the electromagnetic wave is equal to or higher than an energy gap of one of the group III-nitride compound materials which is etched.

15. The method of claim 9, wherein an etching temperature during the wet etching step is higher than 150 degree Celsius.

16. A method for fabricating a nitride-based semiconductor light emitting device, comprising:

providing a single crystal substrate having a crystal face, wherein the crystal face is one of a non-polar face and a semi-polar face;

epitaxially growing a nitride-based multi-layered structure on the crystal face, wherein a crystal growth orientation of the multi-layered structure matches with an crystal orientation of the crystal face;

treating the multi-layered structure to form a mesa structure thereon;

forming a plurality of electrodes on the patterned multi-layered structure and electrically therewith; and

wet etching the patterned multi-layered structure to roughen the mesa structure.

17. The method of claim 16, further comprising a step of:

irradiating the mesa structure by an electromagnetic wave during the wet etching step, the multi-layered structure being made from group III-nitride compound materials, and an energy of the electromagnetic wave is equal to or higher than an energy gap of one of the group III-nitride compound materials which is etched.

18. The method of claim 16, wherein the mesa structure comprises a top surface facing away from the single crystal substrate and a plurality of side surfaces adjoining the top surface, wherein at least one of the top surface and the side surfaces is roughened during the wet etching step.