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Amorphous non-hydrogenated germanium carbide (a-Ge 1Àx C x ) films have been deposited using magnetron co-sputtering technique by varying the sputtering power of germanium target (P Ge ). The effects of P Ge on composition and structure of the a-Ge 1Àx C x films have been analyzed. The FTIR spectrum shows that the C-Ge bonds were formed in the a-Ge 1Àx C x films according to the absorption peak at~610 cm À1 . 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 P Ge increased from 40 to 160 W. The fraction of sp 3 C-C bonds remains almost constant when increasing P Ge from 40 to 160 W. The sp 2 C-C content of a-Ge 1Àx C x film decreases gradually to 35.9% with P Ge up to 160 W. Nevertheless, sp 3 C-Ge sites rose with increasing P Ge . Furthermore, the hardness and the refractive index gradually increased with increasing P Ge . The excellent optical transmission of annealed a-Ge 1-x C x double-layer coating at 400 C suggests that a-Ge 1Àx C x films can be used as an effective anti-reflection coating for the ZnS IR window in the wavelength region of 8-12 mm, and can endure higher temperature than hydrogenated amorphous germanium carbide do.

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