In this study, rf sputtered hydrogenated amorphous silicon-germanium thin films deposited at room temperature have been investigated by spectroscopic ellipsometry and Rutherford backscattering. Technological parameters were determined for good layer quality of amorphous material. The layer thicknesses were first evaluated from the Rutherford backscattering and spectroscopic ellipsometry measurements, then measured directly by step-profiler, and compared to each other. The inherence of technological parameters and composition of the layers is discussed.