Vibronic Fine Structures on the ${\sim}3.0$ eV Violet Emission in Ion-Implanted ZnO Nanorods

Abstract

Unusual vibronic fine structures of the ∼3.0 eV violet emission from ion-implanted ZnO nanorods have been investigated by photoluminescence (PL). A set of equally separated peaks with energy spacing of 72 meV, which corresponds to the longitudinal optical (LO) phonon energy of ZnO, were well resolved in the low-temperature PL spectra. The overall emission band can be perfectly described on the basis of the LO phonon-assisted transition with the Huang–Rhys factor of 1.98, indicating intermediate electron-phonon coupling. The thermal quenching of PL gives rise to an activation energy of ∼160 meV, which is attributed to the energy level of acceptor-like defects introduced by implantation.

Extraordinary near-band-edge photoluminescence in the highly epitaxial ZnO films deposited by PLD

“…Phenomenologically, the shape, energy position, and temperature dependence of our broad NBE emissions have the similarity with Liu et al's [3] observation in the Ne-implanted ZnO nanorods. However, we have no reason assigning the NBE PL to the transition related to interstitial zinc (Zn i ) or zinc vacancy (V Zn ) because the NBE emission was observed in the samples deposited in quite large a range of working pressure.…”

“…Therefore, the emission bands contain controversies and have been less frequently addressed on unambiguous electron transitions. Liu et al [3] reported emission at 3.0 eV with unusual spectral feature from neon-implanted ZnO nanorods, and ascribed it to acceptor-like defects introduced by implantation. Zhao et al [4] observed the violet emission in the 414-420 nm range of Ag-nanoclusters doped ZnO thin films and suggested the transition to interstitial zinc level and zinc vacancy.…”

Violet Emission in ZnO Nanorods Treated with High-Energy Hydrogen Plasma

“…Considering that large amounts of H diffusing out of ZnO at 400 °C, there may exist a correlation between the violet emission and H. Such a strong violet emission at 3.18 eV at 13 K has been rarely reported in ZnO nanorod arrays, and its mechanism has been limited so far. He et al 29 reported the violet emission at 3.0 eV with unusual fine structures from neon-implanted ZnO nanorods, and they attributed it to acceptor-like defects in ZnO induced by neon implantation. Zeng et al 30 introduced a high concentration of defects into nanoscale ZnO and observed a dominant blue emission.…”