Photonic crystal light emitting device using photon-recycling

1. A photonic crystal light emitting device comprising:

a light emitting diode (LED) light emitting structure including a first conductive semiconductor layer, a second conductive semiconductor layer, and an active layer interposed between the first and second conductive semiconductor layers;

a first photon-recycling light emitting layer formed on one surface of the first conductive semiconductor layer, opposite to an interface between the first conductive semiconductor layer and the active layer; and

a transparent substrate disposed between the first photon-recycling light emitting layer and the first conductive semiconductor layer,

wherein the first photon-recycling light emitting layer has a photonic crystal structure, which absorbs a primary light emitted from the LED light emitting structure and emits a light having a different wavelength from a wavelength of the primary light,

wherein the photonic crystal structure includes a periodic pattern of semiconductor posts extending across an entire thickness of the first photon-recycling light emitting layer from a top surface of the first photon-recycling light emitting layer to a bottom surface of the first photon-recycling light emitting layer,

the photonic crystal structure is comprised of an AlGalnP semiconductor, and

the light emitted by the photonic crystal structure of the AlGalnP semiconductor and having the different wavelength from the wavelength of the primary light is yellow.

2. The photonic crystal light emitting device of claim 1 , wherein a conductivity of the first conductive semiconductor layer is an n-type and a conductivity of the second conductive semiconductor layer is a p-type.

3. The photonic crystal light emitting device of claim 1 , wherein the first and second conductive semiconductor layers and the active layer are formed of a nitride semiconductor.

4. The photonic crystal light emitting device of claim 1 , wherein the LED light emitting structure is formed in a mesa structure to expose a portion of the first conductive semiconductor layer to an outer space, and

an n-side electrode is formed on the exposed portion of the first conductive semiconductor layer.

5. The photonic crystal light emitting device of claim 1 , wherein the photonic crystal light emitting device is mounted on a submount in such a way that the second conductive semiconductor layer faces the submount and the first photon-recycling light emitting layer faces in the opposite direction to the submount, and

a light is outputted to one surface of the first photon-recycling light emitting layer opposed to an interface between the second conductive semiconductor layer and the active layer.

6. The photonic crystal light emitting device of claim 5 , further comprising a reflective metal layer formed on one surface of the second conductive semiconductor layer opposed to an interface between the second conductive semiconductor layer and the active layer.

7. The photonic crystal light emitting device of claim 1 , wherein the photonic crystal light emitting device outputs a white light.

8. The photonic crystal light emitting device of claim 1 , wherein the active layer emits a blue light and the first photon-recycling light emitting layer emits a yellow light.