Raman intensity enhancement in silicon-on-insulator substrates by laser deflection at atomic force microscopy tips and particles

It is shown that Raman intensities of bulk and film in silicon-on-insulator substrates strongly depend on the incident angle of the exciting laser. In a backscattering geometry with perpendicular laser incidence, deflection at particles or atomic force microscopy tips can thereby lead to a selective enhancement of the film signal, which can be misinterpreted as surface/tip enhanced Raman scattering. The authors report strong enhancement effects by scattering at dielectric particles on silicon-on-insulator and silicon substrates as well as smaller effects for deflection at tips. In evaluating field enhancements on such substrates, this must be considered.