Long-wavelength resonant-cavity light-emitting diode

• US 8,148,186 B2
• Filed: 11/18/2009
• Issued: 04/03/2012
• Est. Priority Date: 09/29/2006
• Status: Active Grant

• Current Assignee: Innolume GmbH
• Original Assignee: Innolume GmbH
• Inventors: Kovsh, Alexey, Krestnikov, Igor, Mikhrin, Sergey, Livshits, Daniil
• Primary Examiner(s): Pham, Long
• Application Number:
  US12/620,817
• Publication Number:
  US 20100068842A1
• Time in Patent Office: 867 Days
• Field of Search: 438/34, 438/39, 438/46
• US Class Current: 438/34
• 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 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 mesa structure formed 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;

wherein an optical thickness of the resonant cavity is at least 1.5 wavelengths of a main maximum of an emission spectrum;

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

v) a quantum well, wherein an absorption peak of the quantum well is shifted to a shorter wavelength than a wavelength of a ground state luminescence of the quantum dots;

c) the n-ohmic contact; and

d) the p-ohmic contact located on the portion of the top surface of the mesa structure.

2. The method of claim 1, 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.

3. The method of claim 1, 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.

4. The method of claim 1, 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.

5. The method of claim 1, wherein the absorption peak of the quantum well approximately coincides with a wavelength of the excited-state luminescence of the quantum dot active region.

6. The method of claim 1, wherein the quantum well absorbs the excited-state luminescence of the quantum dot active region such that the intensity of the maxima other than the main maximum is suppressed.

7. The method of claim 1, wherein the quantum well absorbs the excited-state luminescence of the quantum dot active region but does not absorb the ground-state luminescence of the quantum dot active region.

8. The method of claim 1, wherein the resonant-cavity light emitting diode further comprises a current spreading region which improves a uniformity of the current density over the area of the mesa structures.

9. The method of claim 1, wherein the quantum dots comprise a plurality of (In,Ga)As quantum dots.

10. The method of claim 1, wherein the quantum dots comprise a plurality of (In,Ga)(As,N) quantum dots.

11. The method of claim 1, wherein the substrate is an n-type GaAs substrate.

12. 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 mesa structure formed 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;

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

v) a quantum well that absorbs the excited-state luminescence of the quantum dot active region such that the intensity of the maxima other than the main maximum is suppressed;

c) the n-ohmic contact; and

d) the p-ohmic contact located on the portion of the top surface of the mesa structure.

13. 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 mesa structure formed 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;

wherein an optical thickness of the resonant cavity is at least 1.5 wavelengths of a main maximum of an emission spectrum; 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 p-ohmic contact located on the portion of the top surface of the mesa structure.