• magnetron co-sputtering;
  • Germanium carbide film;
  • chemical bonding;
  • optical properties

Amorphous non-hydrogenated germanium carbide (a-Ge1−xCx) films have been deposited using magnetron co-sputtering technique by varying the sputtering power of germanium target (PGe). The effects of PGe on composition and structure of the a-Ge1−xCx films have been analyzed. The FTIR spectrum shows that the C–Ge bonds were formed in the a-Ge1−xCx films according to the absorption peak at ~610 cm−1. The Raman results indicate that the amorphous films also contain both Ge and C clusters. The XPS results reveal that the carbon concentration decreased as PGe increased from 40 to 160 W. The fraction of sp3 C–C bonds remains almost constant when increasing PGe from 40 to 160 W. The sp2 C–C content of a-Ge1−xCx film decreases gradually to 35.9% with PGe up to 160 W. Nevertheless, sp3 C–Ge sites rose with increasing PGe. Furthermore, the hardness and the refractive index gradually increased with increasing PGe. The excellent optical transmission of annealed a-Ge1–xCx double-layer coating at 400 °C suggests that a-Ge1−xCx films can be used as an effective anti-reflection coating for the ZnS IR window in the wavelength region of 8–12 µm, and can endure higher temperature than hydrogenated amorphous germanium carbide do. Copyright © 2012 John Wiley & Sons, Ltd.