A simple and economical method to obtain nano-ZnO films by oxygen-plasma-assisted E-beam eva-poration of metallic Zn onto a Si substrate at 250℃

followed by low-temperature thermal annealing from 300℃ to 500℃ for 1 h in oxygen ambient was described in this paper.The effect of the interface layers between Zn and ZnO on the structural and luminescent properties of the samples was studied employing X-ray diffraction(XRD)

Raman scattering and room-temperature photoluminescence(PL) spectra.XRD patterns indicated that the nano-ZnO films had a polycrystalline hexagonal wurtzite structure.The interface mode(Es) centered at about 534 cm

-1

which is from the surface of Zn particles coated with ZnO nano-particles.With increasing the annealing temperature

the Es shifted to lower wavenumber with a decrease of intensity.When annealing at 400℃ for 1 h

the Es disappeared

indicating Zn was fully transformed to ZnO.The result of XPS showed the stoichiometric nano-ZnO film was obtained when the sample was annealed at 400℃.Room-temperature PL spectra showed a very strong ultraviolet emission peak at about 381 nm.With increasing the annealing temperature

the intensity of the interface mode decreased.So the bound exciton(from the interface mode) emission decreased and the free exciton emission increased.The film annealed at 400℃ for 1 h had the maximum value of the ratio of UV band to visible emission.All these indicated that stoichiometric

high quality nano-ZnO film was obtained when the sample was annealed at 400℃.