Thermomechanical properties of amorphous hydrogenated carbon-germanium alloys

Thermomechanical properties of amorphous hydrogenated carbon-germanium allo ys prepared by the rf sputtering technique were determined for films in the Oat. % to 100 at. % carbon content range. The stress, thermal expansion co efficient, and elastic modulus were obtained using the thermally induced be nding technique. The stress was related to the concentration of hydrogen an d argon, to the difference in the Ce-Ge and Ge-C bond length, and to the ca rbon hybridization. The thermal expansion coefficients of pure amorphous ge rmanium and amorphous carbon are higher than that of their corresponding cr ystalline counterparts, which was attributed to the compressive stress of t he films. The biaxial modulus, on the other hand, are always smaller than t hat of their crystalline counterparts, but increases as the concentration o f carbon increases due to the substitution of Ce-Ge bonds by energetically stronger Ge-C and C-C bonds.