Optical chracterization of semiconductor nanowires by non-resonant, resonant and surface-enhanced Raman Spectroscopy

Raman scattering is a non-destructive optical technique used to study different properties of nanomaterials by the characterization of the lattice vibrations. However, Raman scattering efficiency tend to be low in the case of semiconductor nanostructures hindering the presence of relevant peaks and demanding large integration times. In this work, InP and InN NWs are functionalized with the plasmonic nanoparticles (NPs) an achieving enhancement of up two orders of magnitude in the Raman signal. Furthermore, we have identified vibrational modes which were nominally forbidden in backscattering configuration by SERS experiments. This unexpected contribution is attributed to the near-field scattering around the NPs which enables a new tool for the characterization of complex systems and an additional scenario to study the light-matter interaction at the nanoscale. In addition, I performed resonant Raman measurements of ultrathin GaN NWs. In the experimental characterization of the ensembles, anomalous results appeared; e.g. supplementary peaks attributed to forbidden silent mode B1l and huge Raman intensities. I will exhaustively present a careful analysis of the different physical mechanisms that allow the forbidden mode to appear and the physics underlying the non-zero dipole moment in the B1l mode, as well as the reason why this dipole moment is not present in the B1h mode.