We present the results of the Raman-scattering measurements of ZnO nanorods by self-catalyzed vapor-liquid-solid(VLS)process and GaN microstructures grown by epitaxial lateral overgrowth(ELO)using hydride vapor phase epitaxy(HVPE). The Raman spectrum of the ZnO nanorods exhibit three sharp phonon peaks at ~ 101,379, and 438 cm-1, corresponding to symmetries E2(low), A1(TO), and E2(high), respectively . It reveals a low concentration of oxygen vacancies in these ZnO nanorods and their high optical quality. By varying the carrier gas composition (hydrogen versus nitrogen), the growth mode of GaN microstructure can be modified during deposition. The Raman-active E2 (high) phonon is found to gauge the strain distributions of the sample, which gives evidence of the biaxial strain of -0.81 GPa, -0.51GPa, and -0.38 GPa in hydrogen, 1:1 mixed hydrogen/nitrogen, and nitrogen content. Moreover, the peak shift and the broadening of the linewidths as well as asymmetric shape observed in A1(LO) phonon agree with those calculated on the basis of the LO phonon-plasmon model, suggesting a low carrier density of 1 × 1017 cm-3 in hydrogen and 1:1 mixed hydrogen/nitrogen content.