Optical properties of single-crystalline ZnO nanowires on m-sapphire

Abstract

ZnO nanowires have been synthesized using a catalyst-assisted heteroepitaxial carbothermal reduction approach on a m-sapphire substrate. Intricate and uniform arrays have been obtained with each nanowire forming an angle ∼30° with the substrate normal. Photoluminescence studies at room temperature for wavelengths between 335 and 620 nm reveal a strong single exciton peak at ∼380 nm (3.26 eV) with accompanying deep-level blueshifted emission peaks at ∼486, 490, and 510 nm. UV resonant Raman spectroscopy has been used to characterize the nanowires at room temperature with multiphonon scattering exhibiting phonon quantum confinement.

Enhanced Resonant Raman Scattering and Electron−Phonon Coupling from Self-Assembled Secondary ZnO Nanoparticles

“…41 The weak peak, which is contributed to the E 2 (high) mode around 437 cm -1 , is almost imperceptible as a result of other stronger RRS peaks. Multiphonon scattering processes also have been previously reported for single crystalline bulk ZnO 42 and recently for ZnO films, 43 ZnO opal structures, 44 and ZnO nanowires 45,46 but rarely mentioned for ZnO NPs. From the RRS spectra, it is remarkable that the intensities of the first-order Raman mode and its overtones are enhanced in the as-grown ZnO NPs compared with the postannealed samples.…”

Annealing effects on optical properties of low temperature grown ZnO nanorod arrays

“…This is referred to as incoming and outgoing resonances, respectively. 46 Multiphonon scattering processes were previously reported for single crystalline bulk ZnO, 19 and recently for ZnO films, 20 ZnO nanowires, 21,22 and ZnO nanorods. 23,24 In all these cases the samples were excited by the 325 nm line of a He-Cd laser.…”

“…Multiphonon scattering processes were previously reported for single crystalline bulk ZnO, 19 and recently for ZnO films, 20 ZnO nanowires, 21,22 and ZnO nanorods. 23,24 Although several RRS studies have been devoted to analyze the structure property of ZNAs, very few efforts have been made to address RRS in the postannealing effects on the ZNAs grown by low temperature chemical method, particularly to correlate with the change in defects.…”

Growth and luminescence properties of micro- and nanotubes in sintered tin oxide

“…ZnO has attracted much attention, and the growth of different one-dimensional nanostructures of this semiconductor has been reported in the past years. [1][2][3][4][5] Low dimensional nanostructures of other semiconductor oxides with gas sensing applications, such as Ga 2 O 3 , TiO 2 , and SnO 2 , have been also developed. The high surface-to-volume ratio of the nanostructures provides a high sensitivity to the interaction with gases.…”