Study on liquid crystal alignment characteristics by the surface treatment of hydrogenated amorphous carbon thin films

Liquid crystal alignment characteristics were investigated using hydrogenated amorphous carbon (a-C:H) thin films. a-C:H thin films were deposited by a remote plasma-enhanced chemical vapor deposition (RPECVD) method using C₂H₂ and He gases. The surface property of a-C:H thin films was controlled by Ar ion beams. Ion beam irradiation results in the decrease of the optical band gap, the increase of the refractive index, and the increase of the P-base energy of a-C:H thin films. The liquid crystal alignment and pretilt angle were generated by ion beam irradiation. The pretilt angle was affected by the graphitization of a-C:H thin films and the P-base energy of a-C:H thin films.