Etch removal of current distribution layer for LED current confinement
A method and structure for forming an array of LED devices is disclosed. The LED devices in accordance with embodiments of the invention may include a confined current injection area in which a current spreading layer protrudes away from a cladding layer in a pillar configuration so that the cladding layer is wider than the current spreading layer pillar.
1. An LED device comprising:
a top current spreading layer;
a top cladding layer below the top current spreading layer;
an active layer below the top cladding layer;
a bottom cladding layer below the active layer, the bottom cladding layer including a bottom surface;
sidewalls spanning the top current spreading layer, the top cladding layer, the active layer, and the bottom cladding layer, wherein the bottom surface of the bottom cladding layer extends between the sidewalls; and
a singular bottom current spreading layer pillar below the bottom cladding layer and in direct contact with the bottom cladding layer, wherein the bottom current spreading layer pillar is centrally located at and protrudes from the bottom cladding layer, and the bottom surface of the bottom cladding layer that extends between the sidewalls is wider than a maximum width of the bottom current spreading layer pillar, and the bottom current spreading layer pillar is doped with a first dopant type and the second current spreading layer is doped with a second dopant type opposite the first dopant type.
2. The LED device of claim 1 , further comprising a passivation layer spanning along the bottom surface of the bottom cladding layer and sidewalls of the bottom current spreading layer pillar.
3. The LED device of claim 2 , further comprising an opening in the passivation layer on a bottom surface of the bottom current spreading layer pillar opposite the bottom cladding layer.
4. The LED device of claim 3 , further comprising a conductive contact within the opening in the passivation layer and in electrical contact with the bottom current spreading layer pillar.
5. The LED device of claim 4 , wherein the conductive contact is not in direct electrical contact with the bottom cladding layer.
6. The LED device of claim 1 , wherein the top current spreading layer is wider than the bottom current spreading layer pillar.
7. The LED device of claim 1 , wherein the bottom current spreading layer pillar is doped with a p-dopant.
8. The LED device of claim 7 , wherein the bottom current spreading layer pillar comprises GaP and the bottom cladding layer comprises a material selected from the group consisting of AlInP, AlGaInP, and AlGaAs.
9. The LED device of claim 1 , wherein the active layer of the LED device has a maximum width of 100 μm or less, and the bottom current spreading layer pillar maximum width is 10 μm or less.
10. The LED device of claim 1 , wherein the active layer of the LED device has a maximum width of 20 μm or less, and the bottom current spreading layer pillar maximum width is 10 μm or less.
11. The LED device of claim 1 , wherein the active layer includes 1-3 quantum well layers.
12. A display system comprising:
a display substrate including a display area;
an LED device bonded to the display substrate within the display area and in electrical connection with working circuitry in the display substrate, the LED device comprising:
a top current spreading layer;
a top cladding layer below the top current spreading layer;
an active layer below the top cladding layer;
a bottom cladding layer below the active layer, the bottom cladding layer including a bottom surface;
sidewalls spanning the top current spreading layer, the top cladding layer, the active layer, and the bottom cladding layer, wherein the bottom surface of the bottom cladding layer extends between the sidewalls; and
a singular bottom current spreading layer pillar below the bottom cladding layer and in direct contact with the bottom cladding layer, wherein the bottom current spreading layer pillar is centrally located at and protrudes from the bottom cladding layer, and the bottom surface of the bottom cladding layer that extends between the sidewalls is wider than a maximum width of the bottom current spreading layer pillar, and the bottom current spreading layer pillar is doped with a first dopant type and the second current spreading layer is doped with a second dopant type opposite the first dopant type.
13. The display system of claim 12 , wherein the LED device is in electrical connection with a micro chip bonded to the display substrate within the display area.