Raman scattering is a powerful probe of local bonding, strain, temperature, and other properties of materials via their influence on vibrational modes or optical phonons. Tip-enhanced Raman spectroscopy (TERS), in which plasmonic modes are excited at the apex of a metal-coated scanning probe tip, enables Raman scattering signals to be detected from nanoscale volumes with precise positional control. We discuss the application of TERS to characterize a variety of semiconductor nanostructures. In studies of Ge-SiGe core-shell nanowires, we measure spatially resolved Raman spectra along the length of a tapered nanowire to demonstrate the ability to measure local strain distributions with nanoscale spatial resolution. In tip-induced resonant Raman spectroscopy of monolayer and bilayer MoS<sub>2</sub>, we observe large enhancements in Raman signal levels measured for MoS<sub>2</sub> associated with excitation of plasmonic gap modes between an Au-coated probe tip and Au substrate surface onto which MoS<sub>2</sub> has been transferred. Transitions in B exciton photoluminescence intensity between monolayer and bilayer regions of MoS<sub>2</sub> are observed and discussed. Significant differences in nanoscale Raman spectra between monolayer and bilayer MoS<sub>2</sub> are also observed. The origins of specific resonant Raman peaks, their dependence on Mo<sub>S</sub>2 layer thickness, and spatial resolution associated with the transition in Raman spectra between monolayer and bilayer regions are described.
Vertically aligned bundles of TiO<sub>2</sub> nanocrystals were fabricated by pulsed laser deposition (PLD) and tested as a
photoanode material in dye sensitized solar cells (DSSC) using scanning electron microscopy (SEM), light absorption
spectroscopy (UV-Vis), and incident photon-to-current efficiency (IPCE) experiments. An optimal background pressure
of oxygen during deposition was discovered to produce a photoanode structure that simultaneously achieves high surface
area and improves charge transport for enhanced photoelectrochemical performance. UV-Vis studies show that there is
a 1.4x enhancement of surface area for PLD-TiO<sub>2</sub> photoanodes compared to the best sol-gel films. PLD-TiO<sub>2</sub> DSSC
IPCE values are comparable to 3x thicker sol-gel films and nearly 92% APCE values have been observed for optimized