Luminescent and crystalline properties of blue-white-emitting nanocrystalline Sr_2CeO_4 thin films produced by laser ablation

摘要

Blue-white luminescent Sr_2CeO_4 thin films were deposited by using pulsed laser ablation (λ = 248 nm wavelength) on 500 ℃ silicon (111) 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 Sr_2CeO_4 grains of the order of 20-30 nm with a preferential orientation in the (130) crystallographic direction. The excitation and photolummescence spectra measured on the films maintained the characteristic emission of Sr_2CeO_4 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.