Nanowire LED structure and method for manufacturing the same
View Patent ↗A light emitting diode (LED) structure includes a plurality of devices arranged side by side on a support layer. Each device includes a first conductivity type semiconductor nanowire core and an enclosing second conductivity type semiconductor shell for forming a pn or pin junction that in operation provides an active region for light generation. A first electrode layer extends over the plurality of devices and is in electrical contact with at least a top portion of the devices to connect to the shell. The first electrode layer is at least partly air-bridged between the devices.
1. A method of manufacturing a nanowire light emitting diode (LED) structure, comprising:
providing a support layer;
providing a plurality of devices arranged side by side on the support layer, wherein each device comprises a first conductivity type semiconductor nanowire core and an enclosing second conductivity type semiconductor shell for forming a pn or pin junction that in operation provides an active region for light generation;
depositing a sacrificial layer that completely covers the devices in a non-active area and partially covers the devices in a LED area, leaving top portions of the devices in the LED area exposed; and
depositing a first electrode layer on the exposed top portions of the devices and over the support layer between the devices.
2. The method of claim 1 , wherein the first conductivity type comprises n-type, the second conductivity type comprises p-type and the first electrode layer comprises a p-electrode layer.
3. The method of claim 2 , further comprising depositing a second n-electrode layer which electrically connects to the n-type nanowire cores.
4. The method of claim 3 , wherein the support layer comprise an n-type semiconductor buffer layer on a substrate, which buffer layer serves as n-contact and the n-electrode layer contacts the buffer layer.
5. The nanowire method of claim 3 , wherein the support layer comprises at least one of a transparent layer, a reflective layer or a semiconductor substrate.
6. The method of claim 4 , wherein each device comprises a core-shell nanowire containing the core, the shell and an active layer between the core and the shell.
7. The method of claim 6 , further comprising a dielectric masking layer on the support layer such that the cores protrude from the buffer layer through openings in the masking layer, and the shells are located on the masking layer.
8. The method of claim 7 , further comprising removing the sacrificial layer such that a first portion of the first electrode layer located on the sacrificial layer in the non-active area is removed and a second portion of the first electrode layer located on top of the nanowire shells forms an air-bridged p-electrode.
9. The method of claim 8 , wherein the sacrificial layer comprises a photoresist.
10. The method of claim 4 , wherein the buffer layer comprises at least one of gallium nitride or aluminum gallium nitride.
11. The method of claim 2 , wherein the p-electrode comprises a transparent conductive oxide layer.
12. The method as claimed in claim 8 , further comprising the step of temporary bonding a carrier to the side of the structure comprising the nanowires.
13. The method as claimed in claim 12 , further comprising the step of etching one or more recesses in the substrate down to the buffer layer.
14. The method as claimed in claim 13 , further comprising forming a mirror on the buffer layer in the at least one recess to render the LED structure top emitting.
15. The method as claimed in claim 14 , further comprising filling the at least one recess over the mirror with a filler material and removing the structure from the carrier.
16. The method as claimed in claim 12 , further comprising removing the substrate from the structure leaving the buffer layer exposed and applying a mirror to the buffer layer to render the LED structure top emitting.
17. The method as claimed in claim 16 , further comprising attaching a carrier to the mirror.
18. The method as claimed in claim 8 , further comprising attaching a carrier to the structure, the carrier having a mirror on one surface facing the buffer layer.