Light emitting device having light extraction structure and method for manufacturing the same

• US 7,893,451 B2
• Filed: 12/14/2009
• Issued: 02/22/2011
• Est. Priority Date: 05/08/2006
• Status: Active Grant

• Current Assignee: Suzhou Lekin Semiconductor Company Limited
• Original Assignee: LG Electronics, Inc. (LG Corporation), LG Innotek Company Limited (LG Corporation)
• Inventors: Jang, Jun Ho, Kim, Sun Kyung, Cho, Hyun Kyong
• Primary Examiner(s): Soward; Ida M
• Application Number:
  US12/637,646
• Publication Number:
  US 20100090243A1
• Time in Patent Office: 435 Days
• Field of Search: 257/98, 257/E33.067, 257/E33.068, 257/E33.072
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48257 connecting the wire to a die pad of the item
• 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 2224/73265 Layer and wire connectors
• 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 2933/0016 relating to electrodes
• CPC Class Codes: H01L 2933/0033 relating to semiconductor body packages
• CPC Class Codes: H01L 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/42 Transparent materials
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/48 characterised by the semiconductor body packages
• CPC Class Codes: H01L 33/60 Reflective elements
• 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: Y10S 438/977 : Thinning or removal of substrate

Abstract

A nitride-based light emitting device capable of achieving an enhancement in emission efficiency and an enhancement in reliability is disclosed. The light emitting device includes a semiconductor layer, and a light extracting layer arranged on the semiconductor layer and made of a material having a refractive index equal to or higher than a reflective index of the semiconductor layer.

Claims

1. A light emitting device comprising:

a reflective electrode;

a semiconductor layer over the reflective electrode, the semiconductor layer comprising a light emitting layer; and

a light extraction structure arranged on the semiconductor layer,

wherein a distance between the reflective electrode and a center of the light emitting layer falls within the ranges represented by an odd multiple of λ

/(4n)±

α

, where “

λ

”

represents a wavelength of light emitted from the light emitting layer, “

n”

represents a refractive index of the semiconductor layer, and “

α

”

represents 0.14λ

/n.

2. The light emitting device according to claim 1, wherein the reflective electrode comprises an ohmic electrode.

3. The light emitting device according to claim 1, wherein the reflective electrode has a reflectance of 50% or more.

4. The light emitting device according to claim 1, wherein the light emitting layer has a thickness of 0.05λ

/n to 0.25λ

/n.

5. The light emitting device according to claim 1, wherein the light extraction structure comprises holes or rods formed on the semiconductor layer.

6. The light emitting device according to claim 5, wherein the holes have a depth of 300 to 3,000 nm, and the rods have a height of 300 to 3,000 nm.

7. The light emitting device according to claim 6, wherein the holes or rods have a diameter of 0.25a to 0.45a where “

a”

represents an average periodicity of the light extraction structure.

8. The light emitting device according to claim 1, wherein the light extraction structure has an average periodicity of 0.8 to 5 μ

m.

9. The light emitting device according to claim 1 further comprising:

an ohmic electrode between the reflective electrode and the semiconductor layer.

10. The light emitting device according to claim 9, wherein the ohmic electrode comprises a transparent electrode.

11. The light emitting device according to claim 1, wherein a p-type semiconductor layer is arranged between the reflective electrode and the light emitting layer.

12. The light emitting device according to claim 1, wherein the reflective electrode is located over a support layer comprising a semiconductor or a metal.

13. The light emitting device according to claim 1, wherein a distance between the reflective electrode and a center of the light emitting layer is in the range of 0.19λ

/n to 0.38λ

/n or 0.65λ

/n to 0.93λ

/n, where “

λ

”

represents a wavelength of light emitted from the light emitting layer and “

n”

represents a refractive index of the semiconductor layer.

14. The light emitting device according to claim 1, wherein the light extraction structure is formed on the semiconductor layer.

15. The light emitting device according to claim 14, wherein the light extraction structure is formed by etching the semiconductor layer.

16. The light emitting device according to claim 1, wherein the light extraction structure comprises the same material as that of the semiconductor layer.