The effect of different gas atmospheres on luminescent properties of pulsed laser ablated SrAl2O4:Eu2+,Dy3+ thinfilms

Abstract

Abstract SrAl2O4:Eu2+,Dy3+ thin films were grown on Si (1 0 0) substrates using the pulsed laser deposition (PLD) technique to investigate the effect of vacuum, oxygen (O2) and argon (Ar) deposition atmospheres on the structural, morphological, photoluminescence (PL) and cathodoluminescence (CL) properties of the films. The films were ablated using a 248 nm KrF excimer laser. Atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and fluorescence spectrophotometry were used to characterize the thin films. Auger electron spectroscopy (AES) combined with CL spectroscopy were employed for the surface characterization and electron-beam induced degradation of the films. Better PL intensities were obtained from the unannealed films prepared in Ar and O2 atmospheres with respect to those prepared in vacuum. A stable green emission peak at 515 nm, attributed to 4f65d1→4f7 Eu2+ transitions were obtained with less intense peaks at 619 nm, which were attributed to transitions in Eu3+. After annealing the films prepared in vacuum at 800 °C for 2 h, the intensity of the green emission (520 nm) of the thin film increased considerably. The amorphous thin film was crystalline after the annealing process. The CL intensity increased under prolonged electron bombardment during the removal of C due to electron stimulated surface chemical reactions (ESSCRs) on the surface of the SrAl2O4:Eu2+, Dy3+ thin films. The CL stabilized and stayed constant thereafter.