Light-emitting diode

• US 5,698,865 A
• Filed: 04/12/1996
• Issued: 12/16/1997
• Est. Priority Date: 05/13/1995
• Status: Expired due to Fees

• Current Assignee: Temic Telefunken Microelectronic GmbH (Continental AG)
• Original Assignee: Temic Telefunken Microelectronic GmbH (Continental AG)
• Inventors: Gerner, Jochen, Gillessen, Klaus
• Primary Examiner(s): Crane, Sara W.
• Assistant Examiner(s): Wille, Douglas A.
• Application Number:
  US08/631,330
• Time in Patent Office: 613 Days
• Field of Search: 257/94, 257/81, 257/99, 257/473
• US Class Current: 257/94
• 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 33/38 with a particular shape

Abstract

The light-emitting diode consists of a substrate and a light-emission-generating layer located on the substrate and embedded between the cladding layers of a double heterostructure. On the top cladding layer, a current diffusion layer is located on which there is a further contact layer structure. The current diffusion layer is sufficiently thin so as to hardly absorb any light-emission. Thus, it can be economically produced by means of the MOCVD process. At the same time, the contact layer structure is provided with branched and finger-type electrodes for distributing the current together with the current diffusion layer onto the surface of the light-emission-generating layer. However, the structural size of the branched and finger-type electrodes is selected such that these can still be manufactured by the standard processes used in LED manufacture.

Claims

1. Light-emitting diode comprising a substrate, a light-emission-generating layer embedded between respective cladding layers of a double heterostructure and located on the substrate, a current diffusion layer located on the top cladding layer, on which current diffusion layer there is a contact layer structure, wherein the current diffusion layer has a thickness in the range of from approximately 50-500 nm and absorbs hardly any light-emission, and wherein the contact layer structure has branched and finger-type electrodes which extend outwardly from a control area for bonding and which ohmically contact the current diffusion layer to distribute the current across the surface of the light-emission-generating layer, said branched and finger-type electrodes having a width in the range of approximately 4-12 μ

m and with the degree of coverage of the current diffusion layer by the branched and finger-type electrodes being in the range of approximately 5-25%.

2. Light-emitting diode according to claim 1 wherein the double heterostructure consists of InGaAlP.

3. Light-emitting diode according to claim 2 wherein the current diffusion layer consists of GaAs.

4. Light-emitting diode according to claim 1 wherein the current diffusion layer consists of Ga_1-x Al_x As, with x≦

0.6.

5. Light-emitting diode according to claim 1 wherein the current diffusion layer has a thickness of approximately 100 nm.

6. Light-emitting diode according to claim 1 wherein the current diffusion layer has a doping within the range from 1·

10¹⁸ cm^-3 to 2·

10¹⁹ cm^-3.

7. Light-emitting diode according to claim 6 wherein the current diffusion layer has a doping of approximately 1·

10¹⁹ cm^-3.

8. Light-emitting diode according to claim 1 wherein the current diffusion layer has a layer resistance equal to or less than 250 Ω

.

9. Light-emitting diode according to claim 1 wherein the branched and finger-type electrodes of the contact layer structure consist of a gold alloy.

10. Light-emitting diode according to claim 9 wherein the gold alloy has been taken from the group comprising AuZn, AuBe, AuGe, and AuGeNi.

11. Light-emitting diode according to claim 9 wherein the branched and finger-type electrodes of the contact layer structure have a thickness in the range from 0.1 to 1 μ

m.

12. Light-emitting diode according to claim 11 wherein the branched and finger-type electrodes of the contact layer structure have a thickness of 0.5 μ

m.

13. Light-emitting diode according to claim 1 wherein the branched and finger-type electrodes of the contact layer structure have a width of 8 μ

m.

14. Light-emitting diode according to claim 1 wherein the degree of covering in relation to the current diffusion layer covered by the branched and finger-type electrodes of the contact layer structure is 20%.

15. Light-emitting diode according to claim 1 wherein the central surface area for bonding is insulated from the current diffusion layer.

16. Light-emitting diode according to claim 15 wherein an insulating layer is inserted between the current diffusion layer and the central surface area for bonding.

17. Light-emitting diode according to claim 16 wherein the insulating layer consists of SiO₂.

18. Light-emitting diode according to claim 15 wherein the central surface area for bonding is insulated from the current diffusion layer by means of a reverse biased Schottky barrier.

19. Light-emitting diode according to claim 18 wherein the central surface area for bonding consists of a double layer made of NiAu.

20. Light-emitting diode according to claim 19 wherein the central surface area for bonding has a thickness in the range of 1 to 2.5 μ

m.

21. Light-emitting diode according to claim 20 wherein the first sublayer of the double layer consists of Ni and has a thickness of approximately 5 nm, and wherein the second sublayer consists of Au and has a thickness of approximately 1 μ

m.

22. Light-emitting diode according to claim 18 wherein the central surface area for bonding consists of a double layer made of TiWN--Au.

23. Light-emitting diode according to claim 22 wherein the central surface area for bonding has a thickness within the range from 2 to 4.5 μ

m.

24. Light-emitting diode according to claim 23 wherein the first sublayer of the double layer consists of TiWN and has a thickness of approximately 0.25 μ

m, and wherein the second sublayer consists of Al and has a thickness of approximately 3 μ

m.