Diamond layers on silicon: Feasibility of interface assessment by infrared and raman spectroscopies

Abstract

Using diamond films which were grown by plasma-assisted chemical vapour deposition on Si(100) and Si(111) substrates as samples, Fourier-transform infrared and Raman spectroscopies were applied with particular emphasis on the investigation of interface properties such as silicon carbide (SiC) formation and strain distribution. While SiC interlayers can be detected with nanometre sensitivity by infrared spectroscopy it lacks the high spatial resolution obtainable in a micro-Raman experiment. It will thus be demonstrated that the presence of a thin SiC interfacial layer can also be observed in the Raman spectra even despite the low scattering efficiency of SiC. Furthermore, Raman spectra taken in the conventional plane-view geometry are employed to evaluate the lateral homogeneity of the diamond deposition. Cross-sectional Raman spectra, on the other hand provide information e.g. on the strain distribution across the interface. The combination of infrared results with those from conventional plane-view as well as cross-sectional Raman spectra consequently give a detailed insight in the nature of diamond/Si interfaces.