Facebook Technologies, LLC

Christopher Pynn

Anneli Munkholm

Hee Yoon Lee

David Hwang

Disclosed herein are techniques for improving the light emitting efficiency of micro light emitting diodes. According to certain embodiments, micro-LEDs having small physical dimensions are fabricated on III-nitride materials with semi-polar crystal lattice orientations to reduce the surface recombination of excess charge carriers that does not generate photons and to reduce the polarization induced internal field that may cause energy band shift and aggravate the Quantum-Confined Stark Effect, thereby increasing the peak quantum efficiencies and/or reducing the peak efficiency current density of the micro-LEDs.

III-nitride micro-LEDs on semi-polar oriented GaN

An optical system includes an optical waveguide, a micro light emitting diode (micro-LED) configured to emit at least partially polarized light, and a waveguide coupler configured to couple the at least partially polarized light from the micro-LED into the optical waveguide with a coupling efficiency higher than a coupling efficiency of the waveguide coupler for unpolarized light. The micro-LED includes a substrate including a hexagonal lattice and having a first surface parallel to a semi-polar plane of the hexagonal lattice, and a plurality of layers grown on the first surface. The plurality of layers includes an active layer that includes a III-nitride material and has a top surface parallel to the semi-polar plane and the first surface of the substrate, such that the light emitted by the micro-LED is at least partially polarized and can be more efficiently coupled into the optical waveguide.

Waveguide in-coupling using polarized light emitting diodes

Disclosed herein are techniques for improving performance of micro light emitting diodes. According to certain embodiments, a semi-polar-oriented light emitting diode (LED) (e.g., grown on (201) plane or (112) plane) includes a buried p-GaN layer that is grown before the active region and the n-GaN layer of the LED are grown, such that the polarization-induced (including strain-induced piezoelectric polarization and spontaneous polarization) electrical field and the built-in depletion field in the active region are in opposite directions during normal operations, thereby reducing or minimizing the overall internal electric field that can contribute to Quantum-Confined Stark Effect. The buried p-GaN layer is grown on an n-i-n sacrificial etch junction, which can be laterally wet-etched to separate the semi-polar-oriented LED from the underlying substrate and expose the p-GaN layer for planar or vertical (rather than horizontal or lateral) activation.

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Cork, Ireland

Christopher Pynn