Photonic crystal optical filter, reflective color filter, display apparatus using the reflective color filter, and method of manufacturing the reflective color filter

1. A photonic crystal optical filter comprising:

a transparent substrate;

a barrier layer on the transparent substrate, the barrier layer entirely covering a surface of the transparent substrate; and

a photonic crystal layer on the barrier layer, the photonic crystal layer having a first material periodically arranged within a second material and an optical cut-off layer on the first material, the first material being formed into island-shaped patterns, the second material being formed to entirely cover the first material and the optical cut-off layer and to entirely fill spaces between the island-shaped patterns of the first material, and a refractive index of the first material being higher than a refractive index of the second material, the photonic crystal layer configured to reflect light having a wavelength band corresponding to a photonic band gap.

2. The photonic crystal optical filter of claim 1 , wherein a difference between real parts of the refractive indices of the first material and the second material is about 2 or greater.

3. The photonic crystal optical filter of claim 1 , wherein imaginary parts of the refractive indices of the first material and the second material are about 0.1 or smaller in a visible light wavelength band.

4. The photonic crystal optical filter of claim 1 , wherein the first material is one selected from the group consisting of mono-crystal Si, poly Si, AlSb, AlAs, AlGaAs, AlGaInP, BP, ZnGeP 2 , and mixtures thereof.

5. The photonic crystal optical filter of claim 1 , wherein the second material is one selected from the group consisting of Air, PC, PS, PMMA, Si 3 N 4 , SiO 2 , and mixtures thereof.

6. The photonic crystal optical filter of claim 1 , wherein the optical cut-off layer is a silicon oxide layer (SiO 2 ) or a silicon nitride layer (Si 3 N 4 ).

7. The photonic crystal optical filter of claim 1 , wherein an absorption layer is on a lower portion of the transparent substrate.

8. The photonic crystal optical filter of claim 1 , wherein the second material is formed as a supporting layer that supports the island-shaped patterns.

9. The photonic crystal optical filter of claim 8 , wherein the barrier layer is formed of a same material as the second material.

10. A reflective color filter comprising:

a transparent substrate;

a barrier layer on the transparent substrate and having a plurality of pixel areas, the barrier layer entirely covering a surface of the transparent substrate; and

a plurality of photonic crystal units on the plurality of pixel areas, each photonic crystal unit having a first material periodically arranged within a second material and an optical cut-off layer on the first material, the first material being formed into island-shaped patterns, the second material being formed to entirely cover the first material and the optical cut-off layer and to entirely fill spaces between the island-shaped patterns of the first material, a refractive index of the first material being higher than a refractive index of the second material, the photonic crystal unit configured to reflect light having a wavelength band corresponding to a photonic band gap.

11. The reflective color filter of claim 10 , wherein the plurality of photonic crystal units include:

a plurality of red photonic crystal units reflecting red color light;

a plurality of green photonic crystal units reflecting green color light; and

a plurality of blue photonic crystal units reflecting blue color light.

12. The reflective color filter of claim 11 , wherein the plurality of red photonic crystal units, green photonic crystal units, and blue photonic crystal units are arranged in striped patterns, in mosaic patterns, or in delta patterns.

13. The reflective color filter of claim 10 , wherein the first material is formed into island-shaped patterns.

14. The reflective color filter of claim 10 , wherein a difference between real parts of refractive indices of the first material and the second material is about 2 or greater.

15. The reflective color filter of claim 10 , wherein imaginary parts of the refractive indices of the first material and the second material are about 0.1 or smaller in a visible light wavelength band.

16. The reflective color filter of claim 10 , wherein the first material is one selected from the group consisting of mono-crystal Si, poly Si, AlSb, AlAs, AlGaAs, AlGaInP, BP, ZnGeP 2 , and mixtures thereof.

17. The reflective color filter of claim 10 , wherein the second material is one selected from the group consisting of Air, PC, PS, PMMA, Si 3 N 4 , SiO 2 , and mixtures thereof.

18. The reflective color filter of claim 10 , wherein the optical cut-off layer is a silicon oxide layer (SiO 2 ) or a silicon nitride layer (Si 3 N 4 ).

19. The reflective color filter of claim 10 , wherein an absorption layer is on a lower portion of the transparent substrate.

20. The reflective color filter of claim 10 , wherein the second material is formed as a supporting layer that supports the island-shaped patterns.

21. The reflective color filter of claim 20 , wherein the barrier layer is formed of a same material as the second material.

22. A display apparatus comprising:

a liquid crystal layer of which transmissivity with respect to incident light is electrically controlled;

the reflective color filter of claim 20 that reflects light having a wavelength band corresponding to a photonic band gap among light incident on the liquid crystal layer;

an absorption layer on a lower portion of the transparent substrate; and

a thin film transistor (TFT)-array layer having a plurality of TFTs that drive the liquid crystal layer according to image information.

23. The display apparatus of claim 22 , wherein the plurality of TFTs are formed in each of the pixel areas adjacent to the plurality of photonic crystal units,

wherein the plurality of TFTs and the plurality of photonic crystal units are on the transparent substrate.

24. A method of manufacturing a reflective color filter, comprising:

forming a barrier layer on a transparent substrate, the barrier layer entirely covering a surface of the transparent substrate; and

forming a photonic crystal layer on the barrier layer, the photonic crystal layer having a first material periodically arranged as island-shaped patterns within a second material and an optical cut-off layer formed on the first material, the second material being formed to entirely cover the first material and the optical cut-off layer and to entirely fill spaces between the island-shaped patterns of the first material, a refractive index of the first material being higher than a refractive index of the second material, the photonic crystal layer configured to reflect light having a wavelength band corresponding to a photonic band gap.

25. The method of claim 24 , wherein forming the photonic crystal layer includes:

forming a silicon layer on the barrier layer, the silicon layer corresponding to the first material;

forming a hard mask layer on the silicon layer, the hard mask layer corresponding to the optical cut-off layer;

forming a resist pattern on the hard mask layer using an imprinting process;

etching the hard mask layer using the resist pattern as a mask to form the optical cut-off layer;

etching the silicon layer until the barrier layer is exposed using the resist pattern and the hard mask layer as a mask to form island-shaped patterns of the first material; and

recrystallizing the silicon layer.

26. The method of claim 25 , further comprising:

forming a supporting layer that fills spaces between the island-shaped patterns before recrystallizing the silicon layer.

27. The method of claim 25 , wherein the recrystallizing is performed using an excimer laser (EL) annealing process.

28. The method of claim 27 , wherein a scanning direction during the EL annealing process is at about 45° relative to a direction along which the island-shaped patterns are arranged.