Light emitting diode having enhanced side emitting capability

• US 20070181905A1
• Filed: 02/07/2006
• Published: 08/09/2007
• Est. Priority Date: 02/07/2006
• Status: Abandoned Application

• Current Assignee: Epistar Corporation
• Original Assignee: Epistar Corporation
• Inventors: Liu, Jin-Hsiang, Wang, Hui-Heng, Lin, Kun-Chuan
• Application Number:
  US11/348,650
• Publication Number:
  US 20070181905A1
• Time in Patent Office: Days
• US Class Current: 257/103
• CPC Class Codes: H01L 2224/48091 Arched
• 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 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector

Abstract

A LED structure with enhanced side-emitting capability is provided. An embodiment of The LED structure comprises, on top of a substrate, a metallic layer, a non-alloy ohmic contact layer, a thick transparent layer, a light generating structure, sequentially arranged in the this order from bottom to top. The metallic layer functions a reflective mirror and is made of a pure metal or a metal nitride for superior reflectivity. The non-alloy ohmic contact layer is interposed between the light generating structure and the metallic layer so as to achieve the required low resistance electrical conduction. The thick transparent layer extracts a significant portion of the light to the sides of the LED structure. The thick transparent layer, made of a semiconductor material or a dielectric material having an refractive index between 1.5 to 3.5, could be located either above, below or both above and below the light generating structure.

Claims

1. A light emitting diode structure, comprising:

a substrate;

a metallic layer above said substrate;

a non-alloy ohmic contact layer above said metallic layer;

a light generating structure above said non-alloy ohmic contact layer; and

a thick transparent layer positioned at least in one of the following locations;

above said light generating structure, and between said light generating structure and said non-alloy ohmic contact layer.

2. The light emitting diode structure according to claim 1, wherein said metallic layer is made of one of a pure metal and a metal nitride.

3. The light emitting diode structure according to claim 2, wherein said metallic layer is made of one of the following materials:

Au, Al, Ag, TiN_x, and ZrN_x.

4. The light emitting diode structure according to claim 1, further comprising an optically transparent and electrically conductive dielectric layer positioned between said metallic layer and said non-alloy ohmic contact layer.

5. The light emitting diode structure according to claim 4, wherein said dielectric layer is made of a transparent conductive oxide.

6. The light emitting diode structure according to claim 5, wherein said dielectric layer is made of one of the following materials:

ITO, IZO, SnO, Antimony-doped SnO, Fluorine-doped SnO, Phosphorus-doped SnO, ZnO, Aluminum-doped ZnO, InO, CdO, CTO, CuAlO, CuCaO, and SrCuO.

7. The light emitting diode structure according to claim 1, wherein the thickness of said thick transparent layer is at least 1 μ

m.

8. The light emitting diode structure according to claim 1, wherein said thick transparent layer is at least as thick as said light generating structure.

9. The light emitting diode structure according to claim 1, wherein said thick transparent layer is at least as thick as 0.005 times of the lateral dimension of said light generating structure.

10. The light emitting diode structure according to claim 1, wherein said thick transparent layer is made of one of a semiconductor material and a dielectric material, having a refractive index between 1.5 and 3.5 and a bandgap larger than the light energy emitted from said light generating structure.

11. The light emitting diode structure according to claim 10, wherein said thick transparent layer is made of one of the following materials:

AlP, GaP, AlN, AlAs, AlGaP, GaAsP, AlGaAs, and Al_l-xGa_xIn_yP (x≦

0.5, 0<

y≦

l).

12. The light emitting diode structure according to claim 1, wherein said non-alloy ohmic contact layer is a made of a doped semiconductor material.

13. The light emitting diode structure according to claim 12, wherein said non-alloy ohmic contact layer is made of one of the following materials:

carbon-doped AlAs, carbon-doped GaP, carbon-doped AIP, carbon-doped AlGaAs, carbon-doped InAlAs, carbon-doped InGaP, carbon-doped InAIP, carbon-doped AlGaP, carbon-doped GaAsP, carbon-doped AlAsP, carbon-doped AlGaInP, carbon-doped AlGaInAs, carbon-doped InGaAsP, carbon-doped AlGaAsP, carbon-doped AlInAsP, carbon-doped InGaAlAsP, Mg-doped AlAs, Mg-doped GaP, Mg-doped AIP, Mg-doped AlGaAs, Mg-doped InAlAs, Mg-doped InGaP, Mg-doped InAIP, Mg-doped AlGaP, Mg-doped GaAsP, Mg-doped AlAsP, Mg-doped AlGaInP, Mg-doped AlGaInAs, Mg-doped InGaAsP, Mg-doped AlGaAsP, Mg-doped AlInAsP, Mg-doped InGaAlAsP, Zn-doped AlAs, Zn-doped GaP, Zn-doped AIP, Zn-doped AlGaAs, Zn-doped InAlAs, Zn-doped InGaP, Zn-doped InAIP, Zn-doped AlGaP, Zn-doped GaAsP, Zn-doped AlAsP, Zn-doped AlGaInP, Zn-doped AlGaInAs, Zn-doped InGaAsP, Zn-doped AlGaAsP, Zn-doped AlInAsP, Zn-doped InGaAlAsP, carbon-doped InP, carbon-doped InAs, carbon-doped GaAs, carbon-doped InAsP, Mg-doped InP, Mg-doped InAs, Mg-doped GaAs, Mg-doped InAsP, carbon-doped InP, Zn-doped InAs, Zn-doped GaAs, and Zn-doped InAsP.

14. The light emitting diode structure according to claim 1, wherein said non-alloy ohmic contact layer has a plurality of recesses along the surface facing said metallic layer.