Light emitting diode having transparent conductive oxide formed on the contact layer

• US 5,789,768 A
• Filed: 06/23/1997
• Issued: 08/04/1998
• Est. Priority Date: 06/23/1997
• Status: Expired due to Term

• Current Assignee: Epistar Corporation (Ennostar, Inc.)
• Original Assignee: Epistar Corporation (Ennostar, Inc.)
• Inventors: Jou, Ming-Jiunn, Lee, Biing-Jye, Tarn, Jacob C.
• Primary Examiner(s): TRAN, MINH LOAN
• Application Number:
  US08/880,590
• Time in Patent Office: 407 Days
• Field of Search: 257/14, 257/22, 257/94, 257/96, 257/98, 257/99, 257/103
• US Class Current: 257/96
• CPC Class Codes: H01L 33/02 characterised by the semiconductor bodies
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/14 with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• CPC Class Codes: H01L 33/145 with a current-blocking structure
• CPC Class Codes: H01L 33/30 containing only elements of Group III and Group V of the Periodic Table
• CPC Class Codes: H01L 33/42 Transparent materials

Abstract

A structure of a light emitting diode (LED) having high brightness is disclosed. This LED includes a substrate formed on a first electrode, a first cladding layer of a first conductivity type formed on the substrate, an active layer formed on the first cladding layer, a second cladding layer of a second conductivity type formed on the active layer, a window layer of the second conductivity type formed on the second cladding layer, wherein the electrical resistivity of the window layer is less than the electrical resistivity of the second cladding layer, a contact layer of the second conductivity type formed on the window layer for providing ohmic contact, a conductive transparent oxide layer formed on the contact layer, and a current blocking region formed in the LED. The current blocking region is approximately aligned with a second electrode, and can be the contact layer having a hollow portion therein, an insulating region formed on the contact layer, an ion implanted region in the contact layer and the window layer, or a diffused region in the contact layer and the window layer.

Claims

1. A light emitting diode comprising:

a substrate formed on a first electrode;

a first cladding layer of a first conductivity type formed on said substrate;

an active layer formed on said first cladding layer;

a second cladding layer of a second conductivity type formed on said active layer;

a window layer of the second conductivity type formed on said second cladding layer, electrical resistivity of said window layer being less than electrical resistivity of said second cladding layer;

a contact layer of the second conductivity type formed on said window layer for providing ohmic contact, said contact layer having a hollow portion extending from the top surface of said contact layer to the bottom surface of said contact layer, thereby exposing said window layer;

a conductive transparent oxide layer formed on said contact layer, and filled the hollow portion in said contact layer, electrical resistivity of said conductive transparent oxide layer being less than electrical resistivity of said window layer and said contact layer; and

a second electrode formed on a portion of said conductive transparent oxide layer, said second electrode being approximately aligned with the hollow portion in said contact layer.

2. The light emitting diode according to claim 1, wherein said active layer comprises AlGaInP.

3. The light emitting diode according to claim 2, wherein said active layer comprises an AlGaInP multiple quantum well structure.

4. The light emitting diode according to claim 1, wherein said window layer comprises a material chosen from the group consisting of GaP, GaAsP, GaInP, and AlGaAs.

5. The light emitting diode according to claim 1, wherein said contact layer comprises a material chosen from the group consisting of GaAsP, GaP, GaInP, and GaAs.

6. The light emitting diode according to claim 1, wherein said conductive transparent oxide layer comprises a material chosen from the group consisting of indium tin oxide, indium oxide, tin oxide, zinc oxide, and magnesium oxide.

7. The light emitting diode according to claim 1, wherein said substrate comprises GaAs.

8. The light emitting diode according to claim 1, wherein said first cladding layer comprises AlGaInP.

9. The light emitting diode according to claim 1, wherein said second cladding layer comprises AlGaInP.

10. The light emitting diode according to claim 1, further comprising a distributed Bragg reflector layer of a first conductivity type having a plurality of sublayers formed on said substrate and under said first cladding layer.

11. The light emitting diode according to claim 10, wherein said distributed Bragg reflector layer comprises a material chosen from the group consisting of AlGaInP and AlGaAs.

12. A light emitting diode comprising:

a substrate formed on a first electrode;

a first cladding layer of a first conductivity type formed on said substrate;

an active layer formed on said first cladding layer;

a second cladding layer of a second conductivity type formed on said active layer;

a window layer of the second conductivity type formed on said second cladding layer, electrical resistivity of said window layer being less than electrical resistivity of said second cladding layer;

a contact layer of the second conductivity type formed on said window layer for providing ohmic contact;

an insulating region formed on a portion of said contact layer;

a conductive transparent oxide layer formed on said contact layer and said insulating region, electrical resistivity of said conductive transparent oxide layer being less than electrical resistivity of said window layer and said contact layer; and

a second electrode formed on a portion of said conductive transparent oxide layer, said second electrode being approximately aligned with said insulating region.

13. The light emitting diode according to claim 12, wherein said active layer comprises AlGaInP.

14. The light emitting diode according to claim 13, wherein said active layer comprises an AlGaInP multiple quantum well structure.

15. The light emitting diode according to claim 12, wherein said window layer comprises a material chosen from the group consisting of GaP, GaAsP, GaInP, and AlGaAs.

16. The light emitting diode according to claim 12, wherein said contact layer comprises a material chosen from the group consisting of GaAsP, Gap, GaInP, and GaAs.

17. The light emitting diode according to claim 12, wherein said conductive transparent oxide layer comprises a material chosen from the group consisting of indium tin oxide, indium oxide, tin oxide, zinc oxide, and magnesium oxide.

18. The light emitting diode according to claim 12, wherein said substrate comprises GaAs.

19. The light emitting diode according to claim 12, wherein said first cladding layer comprises AlGaInP.

20. The light emitting diode according to claim 12, wherein said second cladding layer comprises AlGaInP.

21. The light emitting diode according to claim 12, further comprising a distributed Bragg reflector layer of a first conductivity type having a plurality of sublayers formed on said substrate and under said first cladding layer.

22. The light emitting diode according to claim 21, wherein said distributed Bragg reflector layer comprises a material chosen from the group consisting of AlGaInP and AlGaAs.

23. The light emitting diode according to claim 12, wherein said insulating region comprises a material chosen from the group consisting of silicon oxide, silicon nitride, and aluminum oxide.

24. A light emitting diode comprising:

a substrate formed on a first electrode;

a first cladding layer of a first conductivity type formed on said substrate;

an active layer formed on said first cladding layer;

a second cladding layer of a second conductivity type formed on said active layer;

a window layer of the second conductivity type formed on said second cladding layer, electrical resistivity of said window layer being less than electrical resistivity of said second cladding layer;

a contact layer of the second conductivity type formed on said window layer for providing ohmic contact, portions of said contact layer and said window layer being ion implanted to form a resistive region of the second conductivity type;

a conductive transparent oxide layer formed on said contact layer, electrical resistivity of said conductive transparent oxide layer being less than electrical resistivity of said window layer and said contact layer; and

a second electrode formed on a portion of said conductive transparent oxide layer, said second electrode being approximately aligned with the resistive region in said contact layer and said window layer.

25. The light emitting diode according to claim 24, wherein said active layer comprises AlGaInP.

26. The light emitting diode according to claim 25, wherein said active layer comprises an AlGaInP multiple quantum well structure.

27. The light emitting diode according to claim 24, wherein said window layer comprises a material chosen from the group consisting of GaP, GaAsP, GaInP, and AlGaAs.

28. The light emitting diode according to claim 24, wherein said contact layer comprises a material chosen from the group consisting of GaAsP, GaP, GaInP, and GaAs.

29. The light emitting diode according to claim 24, wherein said conductive transparent oxide layer comprises a material chosen from the group consisting of indium tin oxide, indium oxide, tin oxide, zinc oxide, and magnesium oxide.

30. The light emitting diode according to claim 24, wherein said substrate comprises GaAs.

31. The light emitting diode according to claim 24, wherein said first cladding layer comprises AlGaInP.

32. The light emitting diode according to claim 24, wherein said second cladding layer comprises AlGaInP.

33. The light emitting diode according to claim 24, further comprising a distributed Bragg reflector layer of a first conductivity type having a plurality of sublayers formed on said substrate and under said first cladding layer.

34. The light emitting diode according to claim 33, wherein said distributed Bragg reflector layer comprises a material chosen from the group consisting of AlGaInP and AlGaAs.

35. The light emitting diode according to claim 24, wherein ions of said ion implantation are H⁺ or O⁺ ions.

36. A light emitting diode comprising:

a substrate formed on a first electrode;

a first cladding layer of a first conductivity type formed on said substrate;

an active layer formed on said first cladding layer;

a second cladding layer of a second conductivity type formed on said active layer;

a window layer of the second conductivity type formed on said second cladding layer, electrical resistivity of said window layer being less than electrical resistivity of said second cladding layer;

a contact layer of the second conductivity type formed on said window layer for providing ohmic contact, portions of said contact layer and said window layer being ion diffused to form a diffused region of the second conductivity type, thereby resulting in a potential barrier between said window layer and the diffused region;

a conductive transparent oxide layer formed on said contact layer, electrical resistivity of said conductive transparent oxide layer being less than electrical resistivity of said window layer and said contact layer; and

a second electrode formed on a portion of said conductive transparent oxide layer, said second electrode being approximately aligned with the diffused region in said contact layer and said window layer.

37. The light emitting diode according to claim 36, wherein said active layer comprises AlGaInP.

38. The light emitting diode according to claim 37, wherein said active layer comprises an AlGaInP multiple quantum well structure.

39. The light emitting diode according to claim 36, wherein said window layer comprises a material chosen from the group consisting of GaP, GaAsP, GaInP, and AlGaAs.

40. The light emitting diode according to claim 36, wherein said contact layer comprises a material chosen from the group consisting of GaAsP, GaP, GaInP, and GaAs.

41. The light emitting diode according to claim 36, wherein said conductive transparent oxide layer comprises a material chosen from the group consisting of indium tin oxide, indium oxide, tin oxide, zinc oxide, and magnesium oxide.

42. The light emitting diode according to claim 36, wherein said substrate comprises GaAs.

43. The light emitting diode according to claim 36, wherein said first cladding layer comprises AlGaInP.

44. The light emitting diode according to claim 36, wherein said second cladding layer comprises AlGaInP.

45. The light emitting diode according to claim 36, further comprising a distributed Bragg reflector layer of a first conductivity type having a plurality of sublayers formed on said substrate and under said first cladding layer.

46. The light emitting diode according to claim 45, wherein said distributed Bragg reflector layer comprises a material chosen from the group consisting of AlGaInP and AlGaAs.

47. The light emitting diode according to claim 36, wherein ions of said diffusion are Zn ions.