High efficiency group-III nitride light emitting diode
View Patent ↗A method of improving high-current density efficiency of an LED, said method comprising: (a) preparing a series of LEDs having decreasing defect densities, wherein each LED of said series has a peak IQE of at least 50%, and wherein each LED of said series has the same epitaxial structure; (b) determining an increase in IQEs at high-current density between at least two LEDs of said series; (c) preparing at least an additional LED of said series by reducing defect density relative to the previously obtained lowest defect density; and (d) reiterating steps (b) and (c) until said increase is at least 3% between two LEDs of said series having a decrease X in defect densities.
1. A method of improving high-current density efficiency of an LED, said method comprising:
(a) preparing a series of LEDs having decreasing defect densities, wherein each LED of said series has a peak Internal Quantum Efficiency (IQE) of at least 50%, and wherein each LED of said series has the same epitaxial structure;
(b) determining an increase in IQEs at high-current density between at least two LEDs of said series;
(c) preparing at least an additional LED of said series by reducing defect density relative to the previously obtained lowest defect density; and
(d) reiterating steps (b) and (c) until said increase in IQEs is at least 3% between two LEDs of said series having a decrease X in defect densities.
2. The method of claim 1 , wherein X is at least 50%.
3. The method of claim 1 , further comprising:
(e) reiterating steps (b) and (c) until said increase in IQE at high current density between two LEDs in said series having a decrease in defect densities of at least said X is less than 2%.
4. The method of claim 1 , wherein said high current density is above 100 A.cm-2.
5. The method of claim 1 , wherein, in step (b), defect density between said two LEDs is reduced by a factor of 1/X, and said increase in IQEs is 0.1 *ln(1/X), at 100A.cm-2.
6. The method of claim 1 , wherein, in, step (b), defect density between said two LEDs is reduced by a factor of 1/X, and said increase in IQEs is -k*ln(1/X), where k is in the range 0.05-0.15 or in, the range 0.03-0.2.
7. An LED from the process of claim 1 , said LED having said increase of at least 3% over another LED of said series.
8. A method of improving high-current density efficiency of an LED, said method comprising:
(a) preparing a series of LEDs having decreasing defect densities, wherein each LED of said series has an IQE at J_low, and wherein each LED of said series has substantially the same epitaxial structure;
(b) determining an increase in IQEs at J_low between at least two LEDs of said series;
(c) preparing at least an additional LED of said series by reducing defect density relative to the previously obtained lowest defect density; and
(d) reiterating steps (b) and (c) until said increase is at least 10% between two LEDs of said series having a decrease X in defect densities, wherein said increase corresponds to an increase in IQE at high current density of more than 3%.
9. The method of claim 8 , further comprising determining said increase in IQE at high current density of more than 3%.
10. The method of claim 8 , wherein X is at least 50%.
11. The method of claim 10 , further comprising:
(e) reiterating steps (b) and (c) until said increase in IQE at J_low between two LEDs in said series having a decrease in defect densities of at least said X is less than 2%.
12. An LED from the process of claim 8 , said LED having said increase of at least 3% over another LED of said series.
13. A device comprising:
a III-Nitride LED having a light-emitting region characterized by an emission wavelength longer than 550 nm, and having recombination coefficients A, B, c with A/B less than 5E18 cm 3 and c/B less than 5E-19 cm −3 , and a peak IQE above 40%.
14. The device of claim 13 , wherein the recombination coefficients are evaluated from a fit of the IQE within +/1 one decade of current around a peak current corresponding to the peak IQE.
15. The device of claim 13 , wherein the light-emitting region comprises at least one light-emitting layer with an indium composition larger than 25%.
16. The device of claim 13 , wherein an SRH-causing defect in the active region has a surface density less than 1E8 cm-2.
17. The device of claim 13 , wherein an SRE-causing defect in the active region has a surface density less than 1E7 cm-2.
18. The device of claim 13 , wherein an SRH-causing defect in the active region has a surface density less than 1E6 cm-2.
19. The device of claim 18 , wherein the SRH-causing defect is an impurity.
20. The device of claim 18 , wherein the SRH-causing defect is an intrinsic defect selected from: an interstitial, a vacancy, a complex.
21. The device of claim 20 , wherein the intrinsic defect pertains to Ga.
22. The device of claim 20 , wherein the intrinsic defect pertains to N.