Ultra-Thin and Lithography-Free Transmissive Color Filter Based on Doped Indium Gallium Zinc Oxide with High Performance.

A kind of ultra-thin transmissive color filter based on a metal-semiconductor-metal (MSM) structure is proposed. The displayed color can cover the entire visible range and switches after H treatment. An indium gallium zinc oxide (IGZO) semiconductor was employed, as the concentration of charge carriers can be controlled to adjust the refractive index and achieve certain colors. The color modulation in the designed structure was verified using the rigorous coupled wave analysis (RCWA) method. The angular independence of the relative transmission could reach up to 60°, and polarization-insensitive performance could also be maintained. Numerical results demonstrated that the thickness of IGZO was the key parameter to concentrate the incident light. The overall structure is planar and lithography-free and can be produced with simple preparation steps. The obtained results can also be extended to other similar resonators where a proper cavity allows dynamical functionality.