Micro-Raman Spectroscopy in Self-Catalyzed Indium Phosphide Nanostructures: Morphology and Substrate Effects

摘要： We report the effect of morphology and substrate of self-catalyzed indium phosphide (InP) nanostructures on phonon vibration modes. Using liquid indium as a catalyst, we grew self-catalyzed InP nanocones and nanopillars on single crystal substrates of InP(111)B, Si(111), and Si(100) via metal-organic chemical vapor epitaxy. Due to crystal symmetry breaking in one-dimensional nanostructure, longitudinal-optical (LO) and transverse-optical (TO) phonon modes are clearly resolved with the strong anisotropic behavior. Broadening and downshift of LO phonon modes are found to be sensitive to the morphology (i.e., aspect ratio and surface-to-volume ratio) and crystal structure (i.e., Wurtzite and Zinc Blende) of the as-grown nanostructures. This work demonstrated that Raman spectroscopy provides statistical insights on the quality of as-grown nanostructures (i.e., growth orientation, crystal structures, and the presence of structural defects) without destroying samples.