Systems and methods for coaxial multi-color LED

A micro-LED display chip, comprising:

• a substrate supporting an array of pixel drivers;
• an array of single pixel multi-color micro light-emitting diode (LED) devices, each single pixel multi-color LED device comprising:
• three LED structure layers stacked on top of the substrate and pixel drivers, with a bonding layer between adjacent LED structure layers, each of the LED structure layers further comprising:
• an epitaxial structure forming a micro LED configured to produce a single color light,
• a lower conductive layer electrically connected to and contacting an entire surface of a bottom of the micro LED;
• an upper transparent conductive layer electrically connected to and contacting an entire surface of a top of the micro LED;
• and
• a single continuous electrode metal contact pad layer electrically connected to and in direct contact with the lower conductive layer of each of the three LED structure layers, and
• a metal bonding layer between the substrate and a first LED structure layer of the three LED structure layers, wherein the single continuous electrode metal contact pad layer is electrically connected to a pixel driver of the array of pixel drivers on the substrate by contacting the metal bonding layer;
• wherein:
• the array of single pixel multi-color LEDs is electrically connected to the array of pixel drivers and common electrodes,
• the lower conductive layer of each of the LED structure layers is also electrically connected to the pixel driver and the upper transparent conductive layer of each of the LED structure layers is also electrically connected to a common electrode,
• the three LED structure layers overlap laterally with one another to form a light propagation path through the micro LEDs directly stacked together, and,
• the micro LEDs of different LED structure layers produce light of different wavelengths.

A method for fabricating a single pixel tri-color micro light-emitting diode (LED) device for a display panel, comprising:

• providing a substrate;
• forming a metal bonding layer between the substrate and a first LED structure layer;
• fabricating a first LED structure layer stacked on top of the substrate;
• fabricating a second LED structure layer stacked on top of the first LED structure layer;
• fabricating a third LED structure layer stacked on top of the second LED structure layer;
• for each of the first, second and third LED structure layers comprising an epitaxial structure:
• patterning the epitaxial structure to form an LED within the respective LED structure layer;
• coating a lower conductive layer to electrically connect to and contact an entire surface of a bottom of the LED;
• coating an upper transparent conductive layer to electrically connect to and contact an entire surface of a top of the LED;
• and
• coating a single continuous anode metal contact pad to electrically connect to and in direct contact with the lower conductive layer of each of the first, second and third LED structure layers, wherein the single continuous anode metal contact pad is electrically connected to a pixel driver on the substrate by contacting the metal bonding layer;
• wherein the lower conductive layer is also electrically connected to the pixel driver and the upper transparent conductive layer is also electrically connected to a common electrode,
• wherein the first LED structure layer, the second LED structure layer, and the third LED structure layer substantially overlap laterally with one another to form a light path that combines light emitted from the first LED structure layer, the second LED structure layer and the third LED structure layer.