Light emitting device having a plurality of light emitting cells connected in series and method of fabricating the same
View Patent ↗Disclosed are a light emitting device having a plurality of light emitting cells connected in series and a method of fabricating the same. The light emitting device includes a buffer layer formed on a substrate. A plurality of rod-shaped light emitting cells are located on the buffer layer to be spaced apart from one another. Each of the light emitting cells has an n-layer, an active layer and a p-layer. Meanwhile, wires connect the spaced light emitting cells in series or parallel. Accordingly, arrays of the light emitting cells connected in series are connected to be driven by currents flowing in opposite directions. Thus, there is provided a light emitting device that can be directly driven by an AC power source.
1. A light emitting device comprising:
a buffer layer formed on a substrate;
a plurality of light emitting cells formed in rod shapes and spaced apart from one another on the buffer layer, each of the light emitting cells having an n-layer, an active layer and a p-layer;
wires connecting the spaced light emitting cells in series to form a first serial array of light emitting cells; and
an insulating film,
wherein at least one of the n-layer and the p-layer is cylindrical rod-shaped, and
wherein an upper surface of the buffer layer comprises first areas and a second area surrounding the first areas, and the light emitting cells are disposed directly on the upper surface of the buffer layer in the first areas, respectively, and the insulating film is disposed directly on the upper surface of the buffer layer in the second area.
2. The light emitting device as claimed in claim 1 , wherein the buffer layer is formed of a III-N group material.
3. The light emitting device as claimed in claim 1 , wherein the rod-shaped light emitting cells are formed of a gallium nitride based compound.
4. The light emitting device as claimed in claim 1 , wherein the insulating film fills empty spaces between the light emitting cells.
5. The light emitting device as claimed in claim 1 , wherein an upper surface of the p-layer is coplanar with an upper surface of the insulating film.
6. The light emitting device as claimed in claim 1 , wherein each of the active layer and the p-layer comprise a side surface that extends in a direction away from the buffer layer, and the side surface of the active layer and the side surface of the p-layer are etched surfaces, and
wherein at least a portion of a side surface of the n-layer extending in a direction away from the buffer layer is a non-etched surface.
7. The light emitting device as claimed in claim 6 , wherein the n-layer is rod-shaped.
8. The light emitting device as claimed in claim 7 , wherein the n-layer is cylindrical rod-shaped.
9. The light emitting device as claimed in claim 1 , further comprising:
a plurality of second light emitting cells formed in rod shapes and spaced apart from one another on the buffer layer, each of the second light emitting cells having an n-layer, an active layer and a p-layer; and
wires connecting the spaced second light emitting cells in series to form a second serial array of second light emitting cells,
wherein the first serial array of light emitting cells is configured to be driven by a positive phase of an alternating current power source, and the second serial array of second light emitting cells is configured to be driven by a negative phase of the alternating current power source.
10. A light emitting device comprising:
a buffer layer formed on a substrate;
a plurality of light emitting cells formed in rod shapes and spaced apart from one another on the buffer layer, each of the light emitting cells having an n-layer, an active layer and a p-layer;
wires connecting the spaced light emitting cells in series to form a first serial array of light emitting cells; and
an insulating film,
wherein an upper surface of the buffer layer comprises first areas and a second area surrounding the first areas, and the light emitting cells are disposed directly on the upper surface of the buffer layer in the first areas, respectively, and the insulating film is disposed directly on the upper surface of the buffer layer in the second area.
11. The light emitting device as claimed in claim 10 , wherein an upper surface of the p-layer is coplanar with an upper surface of the insulating film.
12. A light emitting device comprising:
a buffer layer formed on a substrate;
a plurality of light emitting cells formed in rod shapes and spaced apart from one another on the buffer layer, each of the light emitting cells having an n-layer, an active layer and a p-layer;
wires connecting the spaced light emitting cells in series to form a first serial array of light emitting cells; and
an insulating film,
wherein each of the active layer and the p-layer comprise a side surface that extends in a direction away from the buffer layer, and the side surface of the active layer and the side surface of the p-layer are etched surfaces,
wherein at least a portion of a side surface of the n-layer extending in a direction away from the buffer layer is a non-etched surface,
wherein the n-layer is cylindrical rod-shaped, and
wherein an upper surface of the buffer layer comprises first areas and a second area surrounding the first areas, and the light emitting cells are disposed directly on the upper surface of the buffer layer in the first areas, respectively, and the insulating film is disposed directly on the upper surface of the buffer layer in the second area.
13. The light emitting device as claimed in claim 12 , wherein an upper surface of the p-layer is coplanar with an upper surface of the insulating film.