System and method for micro-led optical interconnects

A pixel structure of a micro-light-emitting diode device comprising:

• a mesa defined by etching through a p-type GaN layer of an epitaxial stack and at least partially into an InGaN active region of the epitaxial stack, the mesa having a lateral dimension less than 15 micrometers, wherein sidewalls of the mesa have a tapered, conical, or parabolic profile;
• isolation trenches extending through the epitaxial stack laterally bounding the mesa;
• a conformal dielectric passivation layer on the sidewalls of the mesa;
• a transparent conductive current-spreading layer over the mesa;
• a reflector over the transparent conductive current-spreading layer;
• an adhesion/barrier stack between the reflector and the transparent conductive current-spreading layer;
• a planarization dielectric surrounding the mesa, the planarization dielectric including vias to the transparent conductive current-spreading layer and to an n-type GaN layer of the epitaxial stack;
• a p-contact metallization coupled to the transparent conductive current-spreading layer;
• an n-contact metallization coupled to the n-type GaN layer, the n-contact at least partly surrounding the mesa;
• an anti-reflection coating disposed on the reflector;
• and
• an emission-collimation feature aligned to the mesa comprising one of:
• a micro-lens, or
• a surface-textured region configured to increase coupling of emitted light.

A method of fabricating a structure for a micro-light-emitting diode, the method comprising:

• obtaining a crystalline substrate selected from silicon, sapphire, silicon carbide, and GaN, the substrate having a surface orientation selected from c-plane, m-plane, or semi-polar orientations;
• epitaxially forming an n-type GaN layer doped with a donor selected from silicon and germanium on the crystalline substrate, the n-type GaN layer having a thickness of 0.5 μm to 5.0 μm;
• epitaxially forming an active region comprising a plurality of InGaN quantum wells, wherein each quantum well has a thickness less than or equal to 3 nanometers, and at least one of the quantum wells has an indium mole fraction greater than 0.10;
• depositing an electron blocking layer adjacent the active region, the electron blocking layer having a thickness less than 100 nanometers;
• and
• epitaxially forming a p-type GaN layer comprising magnesium over the electron blocking layer.