Display device using semiconductor light-emitting diodes
Discussed is a display device having a plurality of semiconductor light-emitting diodes. At least one of the semiconductor light-emitting diodes has a first conductive electrode and a second conductive electrode; a first conductive semiconductor layer on which the first conductive electrode is disposed; a second conductive semiconductor layer that overlaps with the first conductive semiconductor layer, and the second conductive electrode being disposed on the second conductive semiconductor layer; an active layer disposed between the first conductive semiconductor layer and the second conductive semiconductor layer; an undoped semiconductor layer disposed on the second conductive semiconductor layer; and protrusions formed of a porous material allowing electropolishing, and on the undoped semiconductor layer.
1. A display device comprising:
a plurality of semiconductor light-emitting diodes,
wherein at least one of the plurality of semiconductor light-emitting diodes comprises:
a first conductive electrode and a second conductive electrode;
a first conductive semiconductor layer on which the first conductive electrode is disposed;
a second conductive semiconductor layer that overlaps with the first conductive semiconductor layer, and the second conductive electrode being disposed on the second conductive semiconductor layer;
an active layer disposed between the first conductive semiconductor layer and the second conductive semiconductor layer;
an undoped semiconductor layer disposed on the second conductive semiconductor layer; and
protrusions formed of a porous material allowing electropolishing, and on the undoped semiconductor layer,
wherein a surface on the undoped semiconductor layer has a first region, and a second region that is disposed inward of the first region,
wherein the second region contains the protrusions, and
wherein a surface roughness of the second region is greater than that of the first region.
2. The display device of claim 1 , wherein the protrusions are formed of a second conductive semiconductor, and have a higher impurity concentration than the second conductive semiconductor layer.
3. The display device of claim 1 , wherein the at least one of the plurality of semiconductor light-emitting diodes further comprises:
an intermediate layer between the second conductive semiconductor layer and the undoped semiconductor layer,
wherein the intermediate layer is formed of a second conductive semiconductor, and contains aluminum (Al).
4. The display device of claim 3 , wherein the at least one of the plurality of semiconductor light-emitting diodes further comprises:
an oxide layer covering a side surface of the intermediate layer, and
wherein the oxide layer comprises an aluminum oxide layer (AlxOy).
5. The display device of claim 1 , wherein the at least one of the plurality of semiconductor light-emitting diodes further comprises:
a passivation layer covering at least part of side surfaces of the first conductive semiconductor layer, the second conductive semiconductor layer, and the active layer.
6. The display device of claim 1 , wherein the protrusions formed have different heights of less than 2 μm.
7. A method of manufacturing a display device, the method comprising:
a thin layer forming operation of sequentially growing a conductive layer, a protective layer, a sacrificial layer, an undoped semiconductor layer, a second conductive semiconductor layer, an active layer and a first conductive semiconductor layer on a growth substrate;
a first isolation operation of etching at least part of the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer to form a passivation layer;
a second isolation operation of dry etching at least part of the passivation layer, the second conductive semiconductor layer, the undoped semiconductor layer, the sacrificial layer, and the protective layer;
an electropolishing operation of electrochemically etching the sacrificial layer to form a porous structure; and
a mechanical lift-off operation of cutting the porous structure to form protrusions,
wherein the protective layer contains aluminum (Al),
wherein the sacrificial layer is formed of a second conductive semiconductor, and has a higher impurity concentration than the second conductive semiconductor layer, and
wherein a reaction gas of dry etching in the second isolation step contains oxygen.
8. The method of claim 7 , wherein an aluminum composition ratio of the protective layer is less than 50%.
9. The method of claim 7 , wherein the protective layer is formed of a plurality of layers containing AlGaN and GaN, and
wherein at least one layer thereof contains second conductive impurities.
10. The method of claim 7 , wherein an oxide layer covering a side surface of the protective layer is formed in the second isolation operation, and
wherein the oxide layer comprises an aluminum oxide layer (AlxOy).
11. The method of claim 7 , further comprising:
an intermediate layer between the second conductive semiconductor layer and the undoped semiconductor layer,
wherein the intermediate layer is formed of a second conductive semiconductor, and contains aluminum (Al).
12. The method of claim 11 , wherein an aluminum composition ratio of the intermediate layer is less than 50%.
13. The method of claim 11 , wherein an oxide layer covering a side surface of the intermediate layer is formed in the second isolation operation, and
wherein the oxide layer comprises an aluminum oxide layer (AlxOy).
14. The method of claim 7 , further comprising:
an electrode forming operation of forming a first conductive electrode and a second conductive electrode corresponding to the first conductive semiconductor layer and the second conductive semiconductor layer, respectively.
15. The method of claim 14 , comprising:
etching the undoped semiconductor layer prior to forming the second conductive electrode.
16. The method of claim 7 , wherein the protrusions formed have different heights of less than 2 μm.
17. The method of claim 7 , wherein the electropolishing operation further forms a surface on the sacrificial layer having a first region, and a second region that is disposed inward of the first region,
wherein the second region contains the protrusions, and
wherein a surface roughness of the second region is greater than that of the first region.
18. A display device comprising:
a plurality of semiconductor light-emitting diodes,
wherein at least one of the plurality of semiconductor light-emitting diodes comprises:
a first conductive semiconductor layer, a second conductive semiconductor layer, and an active layer interposed between the first conductive semiconductor layer and the second conductive semiconductor layer; and
an undoped semiconductor layer disposed on the second conductive semiconductor layer, the undoped semiconductor layer having a surface with a first region and a second region that is disposed inward of the first region,
wherein the second region contains protrusions, and
wherein a surface roughness of the second region is greater than that of the first region.
19. The display device of claim 18 ,
wherein the protrusions in the second region have different heights of less than 2 μm.