Evaluation of the surface structure of diamond films prepared in a combustion flame by surface-enhanced Raman scattering

Abstract

Surface-enhanced Raman scattering (SERS) was performed on the surface characterization of polycrystalline diamond films prepared in a C2H2-O2 combustion flame. The conventional Raman spectra of a diamond film showed only the peak at 1333 cm−1 corresponding to diamond. However, if Ag island films were coated onto the diamond surface (Ag overlayer method), the resultant spectra changed drastically. The peaks around 1580 and 1355 cm−1 were remarkably enhanced; the former is assigned to the sp2 graphite structure and the latter is assigned to the disordered microcrystalline graphite structure, respectively. This would indicate that the diamond surface has a sp2-like structure, which is different from the sp3 structure in bulk. This surface configuration is discussed from the viewpoint of the surface reconstruction.