Compact arrays of color-tunable pixels having two p-n junctions
AssigneeLumileds LLC
InventorRobert Armitage
Life of this patent
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Abstract
Provided is a monolithically integrated red green blue (RGB) light emitting diode (LED) array manufactured with a reduced number of mesa etching steps and contact terminals. The LED array may have two or three p-n-junctions grown sequentially on a wafer. One of the p-n junctions has the opposite order of deposition of the n- and p-layers. A light-emitting active region is embedded between the n- and p-layers of each of the p-n junctions. Each active region emits light of different wavelength. The wafer is etched into multi-level mesas, creating two separate voltage terminals and a ground contact to control the bias between particular semiconductor layers. All of the p-n junctions share a common ground contact.
Claims20
A light emitting diode (LED) array comprising:
- a first light emitting stack on a second light emitting stack on a reflective p-contact electrode bonded to a backplane, wherein
- the first light emitting stack comprises a first electrical contact on a first n-type layer, the first n-type layer on a first tunnel junction, the first tunnel junction on a first p-type layer, the first p-type layer on a first color active region, and
- the second light emitting stack comprises a second electrical contact on a second n-type layer in contact with the first color active region and on a second color active region, the second color active region on a second p-type layer.
A method of manufacturing an LED array, the method comprising:
- sequentially forming two p-n junctions on an epitaxial wafer to form an epitaxial stack, the epitaxial stack comprising at least one n-type layer and at least one p-type layer and having a color active region embedded between the at least one n-type layer and at least one p-type layer;
- depositing a reflective p-contact electrode on the epitaxial stack;
- bonding the reflective p-contact electrode to a backplane wafer;
- dry etching the epitaxial stack to access the at least one n-type layer to form electrical contacts and a mesa;
- conformally depositing a dielectric layer over the mesa;
- removing a portion of the dielectric layer to form a dielectric opening on a top surface of the mesa, the dielectric opening exposing the at least one n-type layer;
- depositing Ohmic contacts in the dielectric opening to form an electrical contact;
- depositing a conformal metal layer over a portion of the mesa and forming a gap across a center of the mesa to allow light out;
- and
- depositing an electrode grid over a top of the LED array.
Dependencies are inferred from the claim text.