Raman-enhancing structures include a photonic crystal having a resonant cavity and at least one waveguide coupled to the resonant cavity. A nanostructure comprising a Raman-enhancing material is disposed proximate the resonant cavity of the photonic crystal. Raman-enhancing structures include a microdisk resonator, at least one waveguide coupled to the microdisk resonator, and a nanostructure comprising a Raman-enhancing material disposed proximate the microdisk resonator. Methods for performing Raman spectroscopy include generating radiation, guiding the radiation through a waveguide to a resonant cavity in a photonic crystal or a microdisk resonator, resonating the radiation in the resonant cavity or microdisk resonator, providing an analyte proximate the resonant cavity or microdisk resonator, subjecting the analyte to the resonating radiation, and detecting Raman scattered radiation.