Light-emitting diode for emitting ultraviolet light

• US 8,907,320 B2
• Filed: 01/31/2013
• Issued: 12/09/2014
• Est. Priority Date: 02/01/2012
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Hwang, Sung-Won, Ko, Geun-Woo, Sim, Sung-Hyun, Kim, Jung-Sub, Chung, Hun-Jae, Sone, Cheol-Soo
• Primary Examiner(s): WHALEN, DANIEL B
• Application Number:
  US13/756,241
• Publication Number:
  US 20130193408A1
• Time in Patent Office: 677 Days
• US Class Current: 257/13
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: B82Y 99/00 Subject matter not provided for in other groups of this subclass
• CPC Class Codes: H01L 2933/0016 relating to electrodes
• CPC Class Codes: H01L 33/04 with a quantum effect structure or superlattice, e.g. tunnel junction
• 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 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/40 Materials therefor
• CPC Class Codes: H01L 33/42 Transparent materials
• CPC Class Codes: Y10S 977/734 Fullerenes, i.e. graphene-based structures, such as nanohorns, nanococoons, nanoscrolls or fullerene-like structures, e.g. WS2 or MoS2 chalcogenide nanotubes, planar C3N4, etc.

Abstract

An ultraviolet (UV) light-emitting diode including an n-type semiconductor layer, an active layer disposed on the n-type semiconductor layer, a p-type semiconductor layer disposed on the active layer and formed of p-type AlGaN, and a p-type graphene layer disposed on the p-type semiconductor layer and formed of graphene doped with a p-type dopant. The UV light-emitting diode has improved light emission efficiency by lowering contact resistance with the p-type semiconductor layer and maximizing UV transmittance.

Claims

1. An ultraviolet (UV) light-emitting diode comprising:

an n-type semiconductor layer;

an active layer disposed on the n-type semiconductor layer;

a p-type semiconductor layer disposed on the active layer and formed of p-type AlGaN; and

a p-type graphene layer disposed on the p-type semiconductor layer and formed of graphene doped with a p-type dopant,

wherein the p-type graphene layer has a nanostructure.

2. The UV light-emitting diode of claim 1, wherein the p-type graphene layer is configured to lower contact resistance and maximize UV transmittance.

3. The UV light-emitting diode of claim 2, wherein the p-type graphene layer has a transmittance of 90% or more with respect to UV light with a wavelength of 280 nm.

4. The UV light-emitting diode of claim 2, wherein contact resistance between the p-type graphene layer and the p-type semiconductor layer is 10⁻

4 ohm/cm² or less.

5. The UV light-emitting diode of claim 2, wherein the p-type dopant is at least one of HNO₃ and AuCl₃.

6. The UV light-emitting diode of claim 2, further comprising a reflective layer disposed on the p-type graphene layer, the reflective layer configured to reflect UV light emitted from the active layer.

7. The UV light-emitting diode of claim 6, wherein a material used to form the reflective layer comprises a metal.

8. The UV light-emitting diode of claim 1, wherein a cross-section of the nanostructure has a triangular unit structure.

9. The UV light-emitting diode of claim 1, wherein a cross-section of the nanostructure has a rectangular unit structure.

10. The UV light-emitting diode of claim 1, wherein an upper surface of the p-type semiconductor layer corresponds to the nanostructure of the p-type graphene layer.

11. An ultraviolet (UV) light-emitting diode comprising:

an n-type semiconductor layer;

an active layer disposed on the n-type semiconductor layer;

a p-type semiconductor layer disposed on the active layer and comprising p-type AlGaN; and

a p-type graphene quantum dot layer disposed on the p-type semiconductor layer and comprising a graphene quantum dot doped with a p-type dopant.

12. The UV light-emitting diode of claim 11, wherein an upper surface of the p-type semiconductor layer has a nanostructure.

13. The UV light-emitting diode of claim 12, wherein a cross-section of the nanostructure has a triangular unit structure.

14. The UV light-emitting diode of claim 12, wherein a cross-section of the nanostructure has a rectangular unit structure.

15. The UV light-emitting diode of claim 11, further comprising a reflective layer disposed on the p-type graphene quantum dot layer, the reflective layer configured to direct UV light amplified by the p-type graphene quantum dot layer toward the n-type semiconductor layer.

16. The UV light-emitting diode of claim 15, wherein a material used to form the reflective layer comprises a metal.

17. The UV light-emitting diode of claim 11, wherein the graphene quantum dot is a plurality of graphene quantum dots, each having a nano-unit crystal structure of a sample with a three-dimensional size that is smaller than the dimension of a de Broglie'"'"'s wavelength.

18. The UV light-emitting diode of claim 17, wherein each graphene quantum dot includes 1 to 100 free electrons.

19. The UV light-emitting diode of claim 17, wherein the plurality of graphene quantum dots include graphene quantum dots having different sizes.