Light emitting device with LED stack for display and display apparatus having the same

1. A light emitting diode pixel for a display, comprising:

a first subpixel, a second subpixel, and a third subpixel, each of the first, second, and third subpixels comprising:

a first LED sub-unit including a first type of semiconductor layer and a second type of semiconductor layer;

a second LED sub-unit disposed on the first LED sub-unit and including a first type of semiconductor layer and a second type of semiconductor layer; and

a third LED sub-unit disposed on the second LED sub-unit and including a first type of semiconductor layer and a second type of semiconductor layer,

wherein:

the second and third LED sub-units of the first subpixel are electrically floated;

the first and third LED sub-units of the second subpixel are electrically floated; and

the first and second LED sub-units of the third subpixel are electrically floated.

2. The light emitting diode pixel of claim 1 , wherein:

the first LED sub-units of the first, second, and third subpixels are separated from each other;

the second LED sub-units of the first, second, and third subpixels are separated from each other;

the third LED sub-units of the first, second, and third subpixels are separated from each other;

each of the first LED sub-unit of the first subpixel, the second LED sub-unit of the second subpixel, and the third LED sub-unit of the third subpixel is configured to emit light;

light generated from the first LED sub-unit of the first subpixel is configured to be emitted to the outside of the light emitting diode pixel through the second and third LED sub-units of the first subpixel; and

light generated from the second LED sub-unit of the second subpixel is configured to be emitted to the outside of the light emitting diode pixel through third LED sub-unit of the second subpixel.

3. The light emitting diode pixel of claim 1 , wherein the first LED sub-unit of the first subpixel, the second LED sub-unit of the second subpixel, and the third LED sub-unit of the third subpixel comprise a first LED stack, a second LED stack, and a third LED stack configured to emit red light, green light, and blue light, respectively.

4. The light emitting diode pixel of claim 1 , wherein:

the first subpixel further comprises a first upper ohmic electrode forming ohmic contact with the first type of semiconductor layer of the first LED sub-unit, and a first lower ohmic electrode forming ohmic contact with the second type of semiconductor layer of the first LED sub-unit;

the second subpixel further comprises a second upper ohmic electrode forming ohmic contact with the first type of semiconductor layer of the second LED sub-unit, and a second lower ohmic electrode forming ohmic contact with the second type of semiconductor layer of the second LED sub-unit; and

the third subpixel further comprises a third upper ohmic electrode forming ohmic contact with the first type of semiconductor layer of the third LED sub-unit, and a third lower ohmic electrode forming ohmic contact with the second type of semiconductor layer of the third LED sub-unit.

5. The light emitting diode pixel of claim 4 , wherein:

the first upper ohmic electrode is electrically separated from the first LED sub-units of the second and third subpixels;

the second upper ohmic electrode is electrically separated from the second LED sub-units of the first and third subpixels; and

the third upper ohmic electrode is electrically separated from the third LED sub-units of the first and second subpixels.

6. The light emitting diode pixel of claim 4 , wherein:

the first lower ohmic electrode comprises a reflection layer configured to reflect light generated from the first LED sub-unit of the first subpixel; and

each of the second lower ohmic electrode and the third lower ohmic electrode is transparent.

7. The light emitting diode pixel of claim 6 , wherein the first lower ohmic electrode forms ohmic contact with the first LED sub-units of the first, second, and third subpixels.

8. The light emitting diode pixel of claim 4 , wherein each of the first, second, and third subpixels further comprises:

a first color filter interposed between the first LED sub-unit and the second LED sub-unit to transmit light generated from the first LED sub-unit of the first subpixel and reflect light generated from the second LED sub-unit of the second subpixel; and

a second color filter interposed between the second LED sub-unit and the third LED sub-unit to transmit light generated from the first LED sub-unit of the first subpixel and light generated from the second LED sub-unit of the second subpixel and reflect light generated from the third LED sub-unit of the third subpixel.

9. The light emitting diode pixel of claim 8 , wherein each of the first color filter and the second color filter comprises at least one of a low pass filter, a band pass filter, and a band stop filter.

10. The light emitting diode pixel of claim 1 , further comprising a support substrate,

wherein:

each of the first, second, and third subpixels further comprises:

a first bonding layer interposed between the support substrate and the first LED sub-unit;

a second bonding layer interposed between the first and second LED sub-units; and

a third bonding layer interposed between the second and third LED sub-units;

the second bonding layer is transparent to light generated from the first LED sub-unit of the first subpixel; and

the third bonding layer is transparent to light generated from the first LED sub-unit of the first subpixel and light generated from the second LED sub-unit of the second subpixel.

11. The light emitting diode pixel of claim 1 , further comprising a light blocking layer surrounding the first, second, and third subpixels.

12. The light emitting diode pixel of claim 11 , wherein the light blocking layer comprises at least one of a light reflective white material or a light absorptive black material.

13. The light emitting diode pixel of claim 1 , wherein the first LED sub-unit of the first subpixel, the second LED sub-unit of the second subpixel, and the third LED sub-unit of the third subpixel have different areas from each other.

14. The light emitting diode pixel of claim 1 , wherein:

the first, second, and third subpixels comprise a micro LED having a surface area less than about 10,000 square μm;

the first LED sub-unit is configured to emit any one of red, green, and blue light;

the second LED sub-unit is configured to emit one of red, green, and blue light different from the first LED sub-unit; and

the third LED sub-unit is configured to emit one of red, green, and blue light different from the first and second LED sub-units.

15. The light emitting diode pixel of claim 1 , wherein at least one of the first and second type of semiconductor layers of the electrically floated LED sub-units is not connected any ohmic electrode.

16. A display apparatus comprising:

a plurality of pixels disposed on a support substrate, at least one of the pixels includes a light emitting diode pixel comprising:

a first subpixel, a second subpixel, and a third subpixel, each of the first, second, and third subpixels comprising:

a first LED sub-unit including a first type of semiconductor layer and a second type of semiconductor layer;

a second LED sub-unit disposed on the first LED sub-unit and including a first type of semiconductor layer and a second type of semiconductor layer; and

a third LED sub-unit disposed on the second LED sub-unit and including a first type of semiconductor layer and a second type of semiconductor layer,

wherein:

the second and third LED sub-units of the first subpixel are electrically floated;

the first and third LED sub-units of the second subpixel are electrically floated; and

the first and second LED sub-units of the third subpixel are electrically floated.

17. The display apparatus of claim 16 , wherein:

the second type of semiconductor layer of the first LED sub-unit of the first subpixel, the second type of semiconductor layer of the second LED sub-unit of the second subpixel, and the second type of semiconductor layer of the third LED sub-unit of the third subpixel are electrically connected to a common line; and

the first type of semiconductor layer of the first LED sub-unit of the first subpixel, the first type of semiconductor layer of the second LED sub-unit of the second subpixel, and the first type of semiconductor layer of the third LED sub-unit of the third subpixel are electrically connected to different lines.

18. The display apparatus of claim 17 , wherein:

the first lower ohmic electrode is commonly disposed under the first, second, and third subpixels; and

the second type of semiconductor layer of the second LED sub-unit of the second subpixel and the second type of semiconductor layer of the third LED sub-unit of the third subpixel are electrically connected to the first lower ohmic electrode.

19. The display apparatus of claim 18 , wherein the first lower ohmic electrode comprises a reflective electrode.

20. The display apparatus of claim 19 , wherein the reflective electrode is continuously disposed over the plurality of pixels and comprises the common line.

21. The display apparatus of claim 16 , wherein each of the first upper ohmic electrode, the second upper ohmic electrode, and the third upper ohmic electrode comprises a pad and a projection.

22. The display apparatus of claim 16 , wherein, in each pixel, the first LED sub-unit of the first subpixel, the second LED sub-unit of the second subpixel, and the third LED sub-unit of the third subpixel have different areas from each other.