Nanocrystalline Sr2CeO4 thin films grown on silicon by laser ablation

Blue-white luminescent Sr2CeO4 thin films were deposited by using pulsed laser ablation (λ = 248 nm wavelength) on 500 deg. C silicon (111) substrates under an oxygen pressure of 55 mTorr. High-resolution electron transmission microscopy, electron diffraction and X-ray diffraction analysis revealed that the films were composed of nanocrystalline Sr2CeO4 grains of the order of 20-30 nm with a preferential orientation in the (130) crystallographic direction. The excitation and photoluminescence spectra measured on the films maintained the characteristic emission of bulk Sr2CeO4 however, the emission peak appeared narrower and blue-shifted as compared to the luminescence spectrum of the target. The blue-shift and a preferential crystallographic orientation during the growth formation of the film is related to the nanocrystalline nature of the grains due to the quantum confinement behavior and surface energy minimization in nanostructured systems