Anharmonicity effects in Cu-doped ZnO nanocombs by temperature-dependent Raman scattering

Abstract

Micro-Raman spectra of E2(high) phonon mode in Cu-doped ZnO nanocombs have been presented in detail with different Cu compositions under the temperature ranging from 83 to 443 K grown by a simple catalyst-free chemical vapor deposition method. The alloy disorder effect has been investigated by analyzing the asymmetric broadening of E2(high) phonon mode and Cu-induced localized vibration mode at room temperature. In addition, we resort to a theory model including the lattice thermal expansion and anharmonic phonon–phonon interaction, which can well describe the temperature dependence of Raman shift and linewidth of E2(high) phonon. In combining with the theory model, we have revealed an increasing anharmonic effect on the Raman shift and linewidth behaviors with increasing Cu composition. Furthermore, it is found that the lifetime of E2(high) phonon mode shortens with enhancing the anharmonicity.