Reduction of surface recombination losses in micro-LEDs
Disclosed herein are systems and methods for reducing surface recombination losses in micro-LEDs. In some embodiments, a method includes increasing a bandgap in an outer region of a semiconductor layer by implanting ions in the outer region of the semiconductor layer and subsequently annealing the outer region of the semiconductor layer to intermix the ions with atoms within the outer region of the semiconductor layer. The semiconductor layer includes an active light emitting layer. A light outcoupling surface of the semiconductor layer has a diameter of less than 10 μm. The outer region of the semiconductor layer extends from an outer surface of the semiconductor layer to a central region of the semiconductor layer that is shaded by a mask during the implanting of the ions.
1. A method comprising:
increasing a bandgap in an outer region of a semiconductor layer by implanting ions in the outer region of the semiconductor layer and subsequently annealing the outer region of the semiconductor layer to intermix the ions with atoms within the outer region of the semiconductor layer, wherein:
the semiconductor layer comprises an active light emitting layer,
a light outcoupling surface of the semiconductor layer has a diameter of less than 10 μm,
the outer region of the semiconductor layer extends from an outer surface of the semiconductor layer to a central region of the semiconductor layer that is shaded by a mask during the implanting of the ions, and
the semiconductor layer further comprises an n-side semiconductor layer and a p-side semiconductor layer.
2. The method of claim 1 , wherein the ions are implanted from a top surface of the p-side semiconductor layer to a depth of approximately 460 nm within the semiconductor layer.
3. The method of claim 1 , wherein the ions are implanted from a top surface of the p-side semiconductor layer to a depth within the active light emitting layer.
4. The method of claim 1 , wherein the ions are implanted at an angle between 0° and 7° with respect to an axis that is normal to a plane of the mask.
5. The method of claim 1 , wherein the outer region of the semiconductor layer has a cross-sectional annular shape.
6. The method of claim 1 , wherein the mask comprises at least one of a metal, a resist, or a hard mask.
7. The method of claim 6 , wherein the metal has a thickness of less than 1000 nm, the resist has a thickness of less than 2500 nm, and the hard mask has a thickness of less than 800 nm.
8. The method of claim 1 , wherein the ions comprise Al ions.
9. The method of claim 8 , wherein a concentration of Al in the outer region of the semiconductor layer after the Al ions have been implanted is between 0.3 and 0.5.
10. The method of claim 8 , wherein the ions have an implantation energy of approximately 400 keV.
11. A light-emitting diode comprising:
a semiconductor layer comprising an active light emitting layer, wherein:
a light outcoupling surface of the semiconductor layer has a diameter of less than 10 μm,
a bandgap in an outer region of the semiconductor layer is greater than a bandgap in a central region of the semiconductor layer,
the outer region of the semiconductor layer comprises ions that are implanted in the outer region of the semiconductor layer and intermixed with atoms within the outer region of the semiconductor layer, and
the semiconductor layer further comprises an n-side semiconductor layer and a p-side semiconductor layer.
12. The light-emitting diode of claim 11 , wherein the ions are implanted from a top surface of the p-side semiconductor layer to a depth of approximately 460 nm within the semiconductor layer.
13. The light-emitting diode of claim 11 , wherein the ions are implanted from a top surface of the p-side semiconductor layer to a depth within the active light emitting layer.
14. The light-emitting diode of claim 11 , wherein the outer region of the semiconductor layer has a cross-sectional annular shape.
15. The light-emitting diode of claim 11 , wherein the ions comprise Al ions.
16. The light-emitting diode of claim 15 , wherein a concentration of Al in the outer region of the semiconductor layer is between 0.3 and 0.5.