Multi-phonon excitations in ZnO textured crystalline films by Raman spectroscopy

Perfect ZnO crystalline films were prepared by magnetron sputtering. In the Raman spectra of the films we observed from 6 to 8 phonon repetitions, similar to the bulk ZnO crystal. The Raman spectra were analyzed using a theory which takes into account many-particle interaction between electrons and phonons. Our calculations show a rather good correlation with the experimental multi-phonon spectra and enable one to calculate correctly an important parameter of ZnO films—the constant of electron-phonon coupling and accordingly to estimate the film quality.