Luminescent and crystalline properties of blue-white-emitting nanocrystalline Sr2CeO4 thin films produced by laser ablation

Blue-white luminescent Sr2CeO4 thin films were deposited by using pulsed laser ablation (λ = 248 nm wavelength) on 500 °C silicon (1 1 1) substrates under an oxygen pressure of 55 mTorr. High-resolution electron transmission microscopy 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 (1 3 0) crystallographic direction. The excitation and photoluminescence spectra measured on the films maintained the characteristic emission of Sr2CeO4 however, the emission peak appeared narrower and blue-shifted as compared to the luminescence spectrum of the target. This blue-shift of about 10 nm may be related to the nanocrystalline nature of the grains and the preferential crystallographic orientation during the growth formation of the film.