Radio-frequency magnetron co-sputtered Ge-Sb-Te phase change thin films

•Ge-Sb-Te amorphous thin films within broad range of chemical composition were prepared by Co sputtering.•Electrical contrast between amorphous and crystalline films is increasing with growing content of GeTe in thin films up to Rs(cr)/Rs(am) ~2.7×10-8 for GeTe layers.•Huge optical contrast values up to |Δn|+|Δk| = 2.96 for GeTe layers at Blu-ray wavelength are observed.•Reflectivity contrast at Blu-ray wavelength reaches up to ~43% with increasing content of GeTe in Ge-Sb-Te thin films.