Light emitting device having commonly connected LED sub-units
A light emitting device including first, second, and third LED sub-units, and electrode pads disposed on the first LED sub-unit, electrically connected to the LED sub-units, and including a common electrode pad electrically connected to each of the LED sub-units, and first, second, and third electrode pads connected to a respective one of the LED sub-units, in which the common electrode pad, the second electrode pad, and the third electrode pad are electrically connected to the second LED sub-unit and the third LED sub-unit through holes that pass through the first LED sub-unit, the first, second, and third LED sub-units are configured to be independently driven, light generated in the first LED sub-unit emitted to the outside through the second and third LED sub-units, and light generated in the second LED sub-unit is emitted to the outside through the third LED sub-unit.
1. A light emitting device for a display, comprising:
a first LED sub-unit;
a second LED sub-unit disposed adjacent to the first LED sub-unit;
a third LED sub-unit disposed adjacent to the second LED sub-unit; and
electrode pads disposed on the first LED sub-unit and electrically connected to the first, second, and third LED sub-units, the electrode pads comprising a common electrode pad electrically connected to each of the first, second, and third LED sub-units, and first, second, and third electrode pads connected to a respective one of the first, second, and third LED sub-units,
wherein:
the common electrode pad, the second electrode pad, and the third electrode pad are electrically connected to the second LED sub-unit and the third LED sub-unit through holes that pass through the first LED sub-unit;
the first LED sub-unit, the second LED sub-unit, and the third LED sub-unit are configured to be independently driven;
light generated in the first LED sub-unit is configured to be emitted to the outside of the light emitting device through the second LED sub-unit and the third LED sub-unit; and
light generated in the second LED sub-unit is configured to be emitted to the outside of the light emitting device through the third LED sub-unit.
2. The light emitting device of claim 1 , wherein:
the first, second, and third LED sub-units comprise a first LED stack, a second, LED stack, and a third LED stack, respectively; and
the first, second, and third LED stacks are configured to emit red light, green light, and blue light, respectively.
3. The light emitting device of claim 1 , further comprising a first reflective electrode disposed between the electrode pads and the first LED sub-unit and in ohmic contact with the first LED sub-unit,
wherein the common electrode pad is connected to the first reflective electrode.
4. The light emitting device of claim 3 , wherein the first reflective electrode comprises an ohmic contact layer in ohmic contact with an upper surface of the first LED sub-unit and a reflective layer that covers the ohmic contact layer.
5. The light emitting device of claim 4 , wherein:
the first reflective electrode has a hollow portion defined by a substantially annular-shaped member; and
the common electrode pad passes through the hollow portion of the substantially annular-shaped member.
6. The light emitting device of claim 4 , further comprising:
a second transparent electrode interposed between the second LED sub-unit and the third LED sub-unit and in ohmic contact with a lower surface of the second LED sub-unit; and
a third transparent electrode in ohmic contact with an upper surface of the third LED sub-unit,
wherein the common electrode pad is electrically connected to the second transparent electrode and the third transparent electrode.
7. The light emitting device of claim 6 , wherein the common electrode pad is connected to an upper surface of the second transparent electrode and an upper surface of the third transparent electrode.
8. The light emitting device of claim 7 , wherein:
each of the first LED sub-unit and the third LED sub-unit comprises a first conductivity type semiconductor layer and a second conductivity type semiconductor layer disposed on a partial region of the first conductivity type semiconductor layer; and
the first electrode pad and the third electrode pad are electrically connected to the first conductivity type semiconductor layer of the first LED sub-unit and the third LED sub-unit, respectively.
9. The light emitting device of claim 8 , further comprising a first ohmic electrode disposed on the first conductivity type semiconductor layer of the first LED sub-unit,
wherein the first electrode pad is connected to the first ohmic electrode.
10. The light emitting device of claim 9 , wherein the third electrode pad is directly connected to the first conductivity type semiconductor layer of the third LED sub-unit.
11. The light emitting device of claim 8 , further comprising:
a first color filter disposed between the third transparent electrode and the second LED sub-unit; and
a second color filter disposed between the first and second LED sub-units.
12. The light emitting device of claim 11 , wherein the first color filter and the second color filter comprise insulating layers having different refractive indices.
13. The light emitting device of claim 1 , wherein the common electrode pad and the third electrode pad are electrically connected to the third LED sub-unit through holes that pass through the second LED sub-unit.
14. The light emitting device of claim 1 , further comprising a substrate on which the third LED sub-unit is disposed.
15. The light emitting device of claim 14 , wherein the substrate comprises a sapphire substrate or a gallium nitride substrate.
16. The light emitting device of claim 1 , further comprising an insulating layer disposed between the first LED sub-unit and the electrode pads,
wherein the electrode pads are electrically connected to the first, second, and third LED sub-units through the insulating layer.
17. The light emitting device of claim 16 , wherein the insulating layer comprises at least one of a distributed Bragg reflector and a light blocking material.
18. The light emitting device of claim 1 , wherein:
the first LED sub-unit is configured to emit one of red, green, and blue light;
the second LED sub-unit is configured to emit a different one of red, green, and blue light from the first LED sub-unit; and
the third LED sub-unit is configured to emit a different one of red, green, and blue light from the first and second LED sub-units.
19. A display apparatus comprising:
a circuit board; and
a plurality of light emitting devices arranged on the circuit board, at least some of the light emitting devices comprise the light emitting device of claim 1 ,
wherein the electrode pads are electrically connected to the circuit board.
20. The display apparatus of claim 19 , wherein:
each of the light emitting devices comprise a substrate coupled to the third LED sub-unit; and
the substrates of the light emitting devices are spaced apart from each other.