Photonic crystal light emitting device and manufacturing method of the same
View Patent ↗There is provided a photonic crystal light emitting device including: a light emitting structure including first and second conductivity type semiconductor layers and an active layer interposed therebetween; a transparent electrode layer formed on the second conductivity type semiconductor layer, the transparent electrode layer having a plurality of holes arranged with a predetermined size and period so as to form a photonic band gap for light emitted from the active layer, whereby the transparent electrode layer includes a photonic crystal structure; and first and second electrode electrically connected to the first conductivity type semiconductor layer and the transparent electrode layer, respectively. The photonic crystal light emitting device has a transparent electrode layer formed of a photonic crystal structure defined by minute holes, thereby improved in light extraction efficiency.
1. A photonic crystal light emitting device comprising:
a light emitting structure including first and second conductivity type semiconductor layers and an active layer interposed therebetween;
a transparent electrode layer disposed on the second conductivity type semiconductor layer, the transparent electrode layer having a plurality of holes formed therein, arranged with a predetermined size and period so as to form a photonic band gap for light emitted from the active layer, whereby the transparent electrode layer comprises a photonic crystal structure; and
first and second electrodes electrically connected to the first conductivity type semiconductor layer and the transparent electrode layer, respectively, wherein:
the photonic crystal structure is formed only in the transparent electrode layer,
the plurality of holes are formed completely through from a first surface to a second surface of the transparent electrode layer,
the transparent electrode layer is formed of a material selected from a group consisting of indium tin oxide (ITO), Indium(III) oxide (In 2 O 3 ), Tin dioxide (SnO 2 ), Magnesium oxide (MgO), Gallium(III) oxide (Ga 2 O 3 ), Zinc oxide (ZnO) and Aluminium oxide (Al 2 O 3 ),
the holes are filled with Silicon Oxide (SiO 2 ) having a refractivity different from a refractivity of the material of the transparent electrode layer,
the second electrode is made of a metal,
the second electrode is disposed on a surface of the transparent electrode layer, such that the second electrode covers only a portion of all of the holes, and
the transparent electrode layer is configured to form the photonic band gap for a transverse magnetic (TM) mode, such that the ratio of the radius of each hole to the predetermined period of the holes ranges between 0.2 and 0.5 and the ratio of the predetermined period to the wavelength of the emitted light ranges between 0.65 and 0.7.
2. The photonic crystal light emitting device of claim 1 , wherein the transparent electrode layer is formed of a metal oxide.
3. The photonic crystal light emitting device of claim 1 , wherein the holes each are shaped as one of a circle, a square and a hexagon.
4. The photonic crystal light emitting device of claim 1 , wherein the second electrode is formed on a top of the transparent electrode layer.
5. The photonic crystal light emitting device of claim 1 , wherein the first and second conductivity type semiconductor layers are n-type and p-type semiconductor layers, respectively.
6. The photonic crystal light emitting device of claim 1 , wherein the first conductivity type semiconductor layer, the active layer and the second conductivity type layer are formed of a nitride.