title: Resonant Raman scattering in ZnO:Mn and ZnO:Mn:Al thin films grown by RF sputtering.
abstract: Raman spectroscopy results obtained under visible (non-resonant) and UV (resonant) excitation for nanocrystalline ZnO, ZnO:Mn and ZnO:Mn:Al thin films grown by radio frequency magnetron sputtering are presented and compared. The origin of the multiple longitudinal optical (LO) phonon Raman peaks, strongly enhanced under resonance conditions, and the effects of the dopants on them are discussed in the framework of the 'cascade' model. It is suggested that the observed suppression of the higher-order LO phonon lines for ZnO:Mn:Al is caused by the dissociation of excitons in the heavily n-type doped material. On the basis of the cascade model interpretation of the higher-order Raman peaks in the resonant spectra, the LO phonon frequencies for wavevectors away from the Γ point are evaluated and compared to previously published phonon dispersion curves.
authors.affiliation: Centro de Física, Campus de Gualtar, Universidade do Minho, 4710-057 Braga, Portugal. fcerqueira@fisica.uminho.pt
authors.forename: M F
authors.initials: MF
authors.lastname: Cerqueira
authors.forename: M I
authors.initials: MI
authors.lastname: Vasilevskiy
authors.forename: F
authors.initials: F
authors.lastname: Oliveira
authors.forename: A G
authors.initials: AG
authors.lastname: Rolo
authors.forename: T
authors.initials: T
authors.lastname: Viseu
authors.forename: J
authors.initials: J
authors.lastname: Ayres de Campos
authors.forename: E
authors.initials: E
authors.lastname: Alves
authors.forename: R
authors.initials: R
authors.lastname: Correia
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D003460:Crystallization; D008345:Manganese / Q000737:chemistry*; D008422:Materials Testing; D010316:Particle Size; D013059:Spectrum Analysis, Raman; D013499:Surface Properties; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D008345:Manganese; D000535:Aluminum; D015034:Zinc Oxide