“…Briefly, owing to high chemical and thermal stability (melting point is up to~2349°C) [1,2], and its mechanical properties (high strength and fracture toughness) [3], yttrium oxide films and particles have been used in thermal or reaction barrier coatings [4] and oxide dispersion strengthened steels [5,6]. Particularly, due to the excellent optical and electric properties, including a wide transmittance range, high refractive index (~2), low absorption, large band gap (~5.4 eV), and high permittivity (~14-18) accompanied with a lattice match with Si and GaAs (for the cubic phase) and graphene (for the hexagonal phase), yttrium oxide thin films become one of the most interesting materials widely used in optical waveguides [7][8][9], and as an antireflective layer [10], or as a high efficiency phosphor by doping with other rare-earth elements [11,12], as well as one component of high-quality metal-oxide-semiconductor (MOS) based devices [13][14][15][16][17][18].…”