LIGHT-EMITTING DIODE AND METHOD FOR FABRICATION THEREOF

• US 20090278148A1
• Filed: 12/22/2006
• Published: 11/12/2009
• Est. Priority Date: 12/22/2005
• Status: Active Grant

• Current Assignee: Showa Denko KK (Resonac Holdings Corp.)
• Original Assignee: Showa Denko KK (Resonac Holdings Corp.)
• Inventors: Nabekura, Wataru, Takeuchi, Ryouichi
• Granted Patent: US 7,915,619 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• 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 2224/49107 on the semiconductor or solid-state body
• 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 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/38 with a particular shape

Abstract

A transparent-substrate light-emitting diode (10) has a light-emitting layer (133) made of a compound semiconductor, wherein the area (A) of a light-extracting surface having formed thereon a first electrode (15) and a second electrode (16) differing in polarity from the first electrode (15), the area (B) of a light-emitting layer (133) formed as approximating to the light-extracting surface and the area (C) of the back surface of a light-emitting diode falling on the side opposite the side for forming the first electrode (15) and the second electrode (16) are so related as to satisfy the relation of A>C>B. The light-emitting diode (10) of this invention, owing to the relation of the area of the light-emitting layer (133) and the area of the back surface (23) of the transparent substrate and the optimization of the shape of a side face of the transparent substrate (14), exhibits high brightness and high exoergic property never attained heretofore and fits use with an electric current of high degree.

Claims

1. A light-emitting diode possessing a transparent substrate and a light-emitting layer made of a compound semiconductor, wherein an area (A) of a light-extracting surface having formed thereon a first electrode and a second electrode differing in polarity from the first electrode, an area (B) of the light-emitting layer formed as approximating to the light-extracting surface, and an area (C) of a back surface of the light-emitting diode falling on a side opposite a side for forming the first electrode and the second electrode are so related as to satisfy a relation of formula A>

C>

B.

2. A light-emitting diode according to claim 1, wherein the light-emitting layer has a composition of formula (Al_XGa_1-X)_YIn_1-YP;

wherein 0≦

X≦

1, 0<

Y≦

1, and the transparent substrate has a heat transfer coefficient of 100 W/m·

k or more.

3. A light-emitting diode according to claim 1, wherein the transparent substrate possesses a side face comprising a first side face approximating to the light-emitting layer and a second side face approximating to a back surface of the transparent substrate and wherein the first side face has an angle of inclination smaller than an angle of inclination of the second side face.

4. A light-emitting diode according to claim 3, wherein the first side face is perpendicular and the second side face is slanted.

7. A light-emitting diode according to claim 3, wherein the angle of inclination of the second side face is 10 degrees or more and 30 degrees or less.

8. A light-emitting diode according to claim 3, wherein the angle of inclination of the second side face is 10 degrees or more and 20 degrees or less.

10. A light-emitting diode according to claim 3, wherein the first side face has a length of 50 μ

m or more and 100 μ

m or less and the second side face has a length of 100 μ

m or more and 250 μ

m or less.

12. A light-emitting diode according to claim 1, wherein the transparent substrate is made of gallium phosphide (GaP).

16. A light-emitting diode according to claim 1, wherein the transparent substrate has a back surface that is a coarsened surface capable of scattering light.

17. A light-emitting diode according to claim 1, wherein the transparent substrate has a back surface having a metal film formed thereon.

18. A light-emitting diode according to claim 17, wherein the metal film on the back surface of the transparent substrate contains a metal having a melting point of 400°

C. or less.

19. A light-emitting diode according to claim 17, wherein the metal film is made of an AuSn alloy.

20. A light-emitting diode according to claim 1, wherein the light-emitting diode is used with an electric power of 1.5 W or more and the area of the back surface thereof is 0.6 mm or more.

21. A light-emitting diode according to claim 16, wherein the transparent substrate is a GaP substrate the back surface thereof results from treatment of the GaP substrate with hydrochloric acid.

22. A light-emitting diode according to claim 3, wherein the first and second side faces of the transparent substrate are those formed by the dicing method.

5. A light-emitting diode comprising a compound semiconductor layer furnished with a light-emitting part containing a light-emitting layer having a composition of formula (Al_XGa_1-X)_YIn_1-YP;

in which 0≦

X≦

1 and 0<

Y≦

1, a transparent substrate having the compound semiconductor layer joined thereto and a main light-extracting surface having formed thereon a first electrode and a second electrode differing in polarity from the first electrode, wherein the second electrode is formed on the compound semiconductor layer exposed to a side opposite the first electrode and the transparent substrate has a side face comprising a first side face roughly perpendicular to the light-emitting surface of the light-emitting layer on a side approximating to the light-emitting layer and a second side face slanted to the light-emitting surface on a side distant from the light-emitting layer.

9. A light-emitting diode according to claim 5, wherein the second side face and a surface parallel to the light-emitting surface form therebetween an angle in a range of 55 degrees 80 degrees.

11. A light-emitting diode according to claim 5, wherein the first side face has a length in a range of 30 μ

m˜

100 μ

m.

13. A light-emitting diode according to claim 5, wherein the transparent substrate is an n-type GaP single crystal in substance and has a surface orientation of (100) or (111).

14. A light-emitting diode according to claim 5, wherein the transparent substrate has a thickness in a range of 50 μ

m˜

300 μ

m.

15. A light-emitting diode according to claim 5, wherein the transparent substrate is made of silicon carbide (SiC).

23. A light-emitting diode according to claim 5, wherein the second electrode has a periphery thereof encircled with a semiconductor layer.

25. A light-emitting diode according to claim 5, wherein the first electrode has a shape of a lattice.

26. A light-emitting diode according to claim 5, wherein the first electrode comprises a pad electrode and a linear electrode having a width of 10 μ

m or less.

27. A light-emitting diode according to claim 5, wherein the light-emitting part contains a GaP layer and the second electrode is formed on the GaP layer.

28. A light-emitting diode according to claim 5, wherein the first electrode possesses an n-type polarity and the second electrode possesses a p-type polarity.

29. A light-emitting diode according to claim 5, wherein the inclined second face of the transparent substrate has coarseness.

6. A light-emitting diode comprising a compound semiconductor layer furnished with a light-emitting part containing a light-emitting layer having a composition of formula (Al_XGa_1-X)_YIn_1-YP;

in which 0≦

X≦

1 and 0<

Y≦

1), a transparent substrate having the compound semiconductor layer joined thereto and a main light-extracting surface having formed thereon a first electrode and a second electrode differing in polarity from the first electrode, wherein the second electrode is formed at a corner position on the compound semiconductor layer exposed to a side opposite the first electrode and the transparent substrate has a side face comprising a first side face roughly perpendicular to the light-emitting surface of the light-emitting layer on a side approximating to the light-emitting layer and a second side face slanted to the light-emitting surface on a side distant from the light-emitting layer.

24. A light-emitting diode according to claim 6, wherein the second electrode is positioned above an inclined structure of the second side face.

30. A method for the fabrication of a light-emitting diode, comprising the steps of:

forming a light-emitting part containing a light-emitting layer having a composition of formula (Al_XGa_1-X)_YIn_1-YP;

in which 0≦

X≦

1 and 0<

Y≦

1);

subsequently causing a compound semiconductor layer containing the light-emitting part to be joined to a transparent substrate;

causing a first electrode attached to a main light-emitting surface on a side opposite the transparent substrate and a second electrode differing in polarity from the first electrode to be formed on an exposed part of the compound semiconductor layer in such a manner that the second electrode may be disposed on a side opposite the first electrode; and

allowing side faces of the transparent substrate to form a first side face roughly perpendicular to the light-emitting surface of the light-emitting layer on a side approximating to the light-emitting layer and a second side face inclined to the light-emitting surface on a side distant from the light-emitting layer by a dicing method.

32. A method for the fabrication of a light-emitting diode according to claim 30, wherein the first side face is formed by a scribe and break method.

33. A method for the fabrication of a light-emitting diode according to claim 30, wherein the first side face is formed by a dicing method.

31. A method for the fabrication of a light-emitting diode, comprising the steps of:

forming a light-emitting part containing a light-emitting layer having a composition of formula (Al_XGa_1-X)_YIn_1-YP;

in which 0≦

X≦

1 and 0<

Y≦

1);

subsequently causing a compound semiconductor layer containing the light-emitting part to be joined to a transparent substrate;

causing a first electrode attached to a main light-emitting surface on a side opposite the transparent substrate and a second electrode differing in polarity from the first electrode to be formed at a corner position on an exposed part of the semiconductor layer in such a manner that the second electrode may be disposed on a side opposite the first electrode; and

allowing side faces of the transparent substrate to form a first side face roughly perpendicular to the light-emitting surface of the light-emitting layer on a side approximating to the light-emitting layer and a second side face inclined to the light-emitting surface on a side distant from the light-emitting layer by a dicing method.