Raman scattering of amorphous carbon/semiconductor interface layers

Abstract

Using Raman spectroscopy we have studied the film/substrate interface of hard hydrogenated amorphous carbon (a-C:H) films deposited on crystalline silicon and germanium. For film thicknesses below ∼ 100 Å a frequency down shift of the main a-C:H Raman peak is observed. This substrate dependent frequency shift provides evidence for the formation of an amorphous SiC interfacial layer for a-C:H deposited on silicon. This assignment is supported by the comparative study of thick (∼ 1 μm) a-Si 1−xC x:H films. The Raman data for a-C:H deposited on germanium and for a-Ge 1−xC x:H, respectively, are also compatible with the concept of an amorphous carbide interface layer.