Display device using micro LED and method of manufacturing same
The present specification provides a display device using a semiconductor light emitting element that self-assembles in a fluid, and a method for manufacturing same. The semiconductor light emitting element is a horizontal semiconductor light emitting element, and has a plurality of mesa structures on one surface thereof to enable unidirectional assembly in a fluid. Further, a transparent electrode layer can be formed on the one surface including the mesa structures to improve luminous efficiency.
1. A device comprising a plurality of semiconductor light emitting elements positioned within an assembly substrate using at least one of an electric field and a magnetic field,
wherein each of at least one of the plurality of semiconductor light emitting elements includes:
a first conductivity type semiconductor layer;
a second conductivity type semiconductor layer positioned on the first conductivity type semiconductor layer, wherein the second conductivity type semiconductor layer includes an opening defined therein;
an active layer positioned between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer;
a first conductivity type electrode positioned in the opening of the second conductivity type semiconductor layer, and electrically connected to the first conductivity type semiconductor layer; and
a second conductivity type electrode positioned on the second conductivity type semiconductor layer,
wherein the second conductivity type semiconductor layer includes a first region being adjacent to the opening and a second region being adjacent to the first region, and
wherein the first region has a mesa structure protruding beyond a top surface of the second region.
2. The device of claim 1 , wherein the second conductivity type electrode is composed of a transparent electrode, and
wherein the second conductivity type electrode is provided on an entire top surface of the second conductivity type semiconductor layer including a top surface of the mesa structure of the first region.
3. The device of claim 1 , wherein the assembly substrate includes a plurality of assembly electrodes configured to generate a dielectrophoretic force to be applied to one of the plurality of semiconductor light emitting elements by the electric field.
4. The device of claim 3 , wherein the mesa structure of the first region in the second conductivity type semiconductor layer includes:
a first sidewall formed by partially etching the second conductivity type semiconductor layer, and
a second sidewall adjacent to the opening and formed by partially etching the second conductivity type semiconductor layer, the active layer, and the first conductivity type semiconductor layer.
5. The device of claim 4 , wherein a height of the first sidewall of the mesa structure is equal to or greater than an effective distance of the dielectrophoretic force acting on the one of the plurality of semiconductor light emitting elements by the assembly substrate.
6. The device of claim 1 , wherein the each semiconductor light emitting element further includes a passivation layer covering a surface of the semiconductor light emitting element.
7. The device of claim 6 , wherein the passivation layer includes at least one of the following:
a first passivation layer surrounding a top surface and side surfaces of the semiconductor light emitting element, and
a second passivation layer surrounding a bottom surface of the semiconductor light emitting element.
8. The device of claim 4 , wherein the each semiconductor light emitting element further includes a passivation layer covering a surface of the semiconductor light emitting element, and
wherein the second conductivity type electrode is positioned on the first sidewall of the mesa structure, and the passivation layer is positioned on the second sidewall of the mesa structure.
9. The device of claim 1 , wherein the mesa structure of the first region in the second conductivity type semiconductor layer is a ring-shaped mesa structure.
10. The device of claim 1 , wherein the each semiconductor light emitting element further includes an un-doped semiconductor layer on a bottom surface of the first conductivity type semiconductor layer.
11. The device of claim 1 , wherein the each semiconductor light emitting element further includes a magnetic layer.
12. The device of claim 1 , wherein the each semiconductor light emitting element is a light emitting diode (LED) having a size of a micrometer unit (a micro-LED).
13. The device of claim 1 , wherein the device is a display device having the plurality of semiconductor light emitting elements configured to generate different colors.
14. A semiconductor light emitting device comprising:
a first conductivity type semiconductor layer;
an active layer provided on the first conductivity type semiconductor layer;
a second conductivity type semiconductor layer provided on the active layer,
wherein an opening is defined through the second conductivity type semiconductor layer, the active layer and a portion of the first conductivity type semiconductor layer;
a first conductivity type electrode provided in the opening and on the first conductivity type semiconductor layer; and
a second conductivity type electrode provided on the second conductivity type semiconductor layer,
wherein a portion of the second conductivity type semiconductor layer surrounding the opening is raised in a mesa shape in comparison to a remaining portion of the second conductivity type semiconductor layer.
15. The semiconductor light emitting device of claim 14 , wherein the raised mesa shaped portion of the second conductivity type semiconductor layer has a ring configuration.
16. The semiconductor light emitting device of claim 14 , further comprising:
a first passivation layer covering the second conductivity type electrode, side and bottom surfaces of the opening, and the first conductivity type electrode provided; and
a second passivation layer provided below a bottom surface of the first conductivity type semiconductor layer.