LONG-WAVELENGTH RESONANT-CAVITY LIGHT-EMITTING DIODE

• US 20080079016A1
• Filed: 09/28/2007
• Published: 04/03/2008
• Est. Priority Date: 09/29/2006
• Status: Active Grant

• Current Assignee: Innolume GmbH
• Original Assignee: Innolume GmbH
• Inventors: Kovsh, Alexey, Krestnikov, Igor, Livshits, Daniil, Mikhrin, Sergey
• Granted Patent: US 7,642,562 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 27/15 including semiconductor components having potential barriers, specially adapted for light emission
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/105 with a resonant cavity structure

Abstract

An efficient long-wavelength light-emitting diode has a resonant-cavity design. The light-emitting diode preferably has self-organized (In,Ga)As or (In,Ga)(As,N) quantum dots in the light-emitting active region, deposited on a GaAs substrate. The light-emitting diode is capable of emitting in a long-wavelength spectral range of preferably 1.15-1.35 μm. The light-emitting diode also has a high efficiency of preferably at least 6 mW and more preferably at least 8 mW at an operating current of less than 100 mA and a low operating voltage of preferably less than 3V. In addition, the light-emitting diode preferably has an intensity of maxima, other than the main maximum of the emission spectrum, of less than 1% of an intensity of the main maximum. This combination of parameters makes such a device useful as an inexpensive optical source for various applications.

Claims

1. A resonant-cavity light-emitting diode comprising:

a) a substrate;

b) a layered structure deposited on the substrate, comprising;

i) an n-type bottom-side distributed Bragg reflector;

ii) a top-side distributed Bragg reflector;

iii) a resonant cavity located between the bottom-side distributed Bragg reflector and the top-side distributed Bragg reflector, comprising a light-emitting quantum dot active region including a plurality of self-organized quantum dots; and

iv) a p-n junction, which is capable of providing electrons and holes to the active region under forward bias;

c) an n-ohmic contact located on a bottom surface of the substrate; and

d) an array of mesa structures comprising the layered structure and a p-ohmic contact located on a portion of a top surface of each of the mesa structures, wherein each mesa structure is a discrete device;

wherein an emission spectrum of the resonant-cavity light-emitting diode includes a main maximum of the emission spectrum which falls into a spectral range from approximately 1.15 to 1.35 μ

m; and

wherein an intensity of maxima, other than the main maximum of the emission spectrum, is less than or equal to 1% of an intensity of the main maximum.

2. The resonant-cavity light-emitting diode of claim 1, wherein the quantum dots comprise a plurality of (In,Ga)As quantum dots.

3. The resonant-cavity light-emitting diode of claim 1, wherein the quantum dots comprise a plurality of (In,Ga)(As,N) quantum dots.

4. The resonant-cavity light-emitting diode of claim 1, wherein the substrate is an n-type GaAs substrate.

5. The resonant-cavity light-emitting diode of claim 4, wherein the quantum dots comprise a plurality of (In,Ga)As quantum dots.

6. The resonant-cavity light-emitting diode of claim 4, wherein the quantum dots comprise a plurality of (In,Ga)(As,N) quantum dots.

7. The resonant-cavity light-emitting diode of claim 1 further comprising a current spreading region which improves a uniformity of the current density over the area of the mesa structure.

8. The resonant-cavity light-emitting diode of claim 1, further comprising a quantum well, which is capable of absorbing the excited-state luminescence of the quantum dot active region.

9. A resonant-cavity light-emitting diode comprising:

a) a substrate;

b) a layered structure deposited on the substrate, comprising;

i) an n-type bottom-side distributed Bragg reflector;

ii) a top-side distributed Bragg reflector;

iii) a resonant cavity located between the bottom-side distributed Bragg reflector and the top-side distributed Bragg reflector, comprising a light-emitting quantum dot active region including a plurality of self-organized quantum dots; and

iv) a p-n junction, which is capable of providing electrons and holes to the active region under forward bias;

c) an n-ohmic contact located on a bottom surface of the substrate; and

d) an array of mesa structures comprising the layered structure and a p-ohmic contact located on a portion of a top surface of each of the mesa structures, wherein each mesa structure is a discrete device;

wherein an emission spectrum of the resonant-cavity light-emitting diode includes a main maximum and a plurality of other maxima, wherein an intensity of the other maxima is less than or equal to 1% of an intensity of the main maximum.

10. The resonant-cavity light-emitting diode of claim 9, wherein the quantum dots comprise a plurality of (In,Ga)As quantum dots.

11. The resonant-cavity light-emitting diode of claim 9, wherein the quantum dots comprise a plurality of (In,Ga)(As,N) quantum dots.

12. The resonant-cavity light-emitting diode of claim 9, wherein the substrate is an n-type GaAs substrate.

13. The resonant-cavity light-emitting diode of claim 12, wherein the quantum dots comprise a plurality of (In,Ga)As quantum dots.

14. The resonant-cavity light-emitting diode of claim 12, wherein the quantum dots comprise a plurality of (In,Ga)(As,N) quantum dots.

15. The resonant-cavity light-emitting diode of claim 9, further comprising a current spreading region which improves a uniformity of the current density over of the area of the mesa structure.

16. The resonant-cavity light-emitting diode of claim 9, further comprising a quantum well, which is capable of absorbing the excited-state luminescence of the quantum dot active region.

17. A method of manufacturing a resonant-cavity light-emitting diode, comprising the steps of:

a) forming an array of mesa structures by etching through a resonant cavity;

b) forming an n-ohmic contact on a bottom surface of a substrate;

c) forming a p-ohmic contact on a portion of a top surface of each of the mesa structures; and

d) dicing the array of mesa structures into discrete devices;

wherein the resonant-cavity light-emitting diode comprises;

a) the substrate;

b) a layered structure deposited on the substrate, comprising;

i) an n-type bottom-side distributed Bragg reflector;

ii) a top-side distributed Bragg reflector;

iii) a resonant cavity located between the bottom-side distributed Bragg reflector and the top-side distributed Bragg reflector, comprising a light-emitting quantum dot active region including a plurality of self-organized quantum dots; and

iv) a p-n junction, which is capable of providing electrons and holes to the active region under forward bias;

c) the n-ohmic contact; and

d) the array of mesa structures comprising the layered structure and a p-ohmic contact, wherein each mesa structure is a discrete device.

18. The method of claim 17, wherein an emission spectrum of the resonant-cavity light-emitting diode includes a main maximum of the emission spectrum which falls into a spectral range from approximately 1.15 to 1.35 μ

m.

19. The method of claim 17, wherein an emission spectrum of the resonant-cavity light-emitting diode includes a main maximum and a plurality of other maxima, wherein an intensity of the other maxima is less than or equal to 1% of an intensity of the main maximum.

20. The method of claim 17, wherein an emission spectrum of the resonant-cavity light-emitting diode includes a main maximum which falls into a spectral range from approximately 1.15 to 1.35 μ

m and a plurality of other maxima, wherein an intensity of the other maxima is less than or equal to 1% of an intensity of the main maximum.