Investigation of Quantum-Confinement Effect in a Single CuO Nanowire

Spatially well separated cupric oxide (CuO) nanowires grown using thermal oxidation method were examined to directly observe the scale structure evolution of lattice vibration modes. Scanning electron microscopy and high-resolution transmission electron microscopy studies revealed the single crystalline nature and microstructure of a single CuO nanowire. Phonon spectral evolution along the wire axis was investigated using confocal Raman spectroscopy by scanning a single nanowire. The Ag, Bg(1), and Bg(2) phonon modes of CuO that are quantum-confined in radial directions of the thin nanowire evidenced from the observed systematic red-shift, broadening of the peak profile. These results can be well explained based on the phonon confinement model.