Optical and electrical properties of nonstoichiometric a-Ge1−xCx films prepared by magnetron co-sputtering

► The effect of the Ge/C ratio on chemical bonding, optical and electrical properties of germanium carbide films that is rarely reported in literature is represented in this article. ► The chemical bonding and microstructure characterization are focused in detail. ► The relationship between chemical bonding and optoelectronic properties is discussed in detail.