Raman spectra of single micrometer-sized tubular ZnO

Micrometer-sized tubular ZnO crystal was fabricated by a hydrothermal method, and was characterized by scanning electron microscopy (SEM). Back-scattering micro-Raman spectrum was applied to investigate the vibrational modes of the microtubes with the comparison to that of ZnO powder. Raman scattering in a single micrometer-sized tubular ZnO was also recorded with different polarization configurations consequently. Most of the observed vibrational modes were assigned on the basis of group theoretical analysis. Besides the typical Raman-active modes assigned to ZnO, a new mode with Raman shift of 860 cm−1 was observed which has not been reported in previous relative researches yet. In addition to this, the Raman signal of E1T mode at 410 cm−1 increased dramatically and become asymmetric in some cases.