Structural and fluorescence properties of thin films fabricated by pulsed laser deposition technique from Nd:KGW single crystal

Textured and amorphous thin films were deposited by KrF laser ablation of neodymium doped potassium gadolinium tungstate, KGd1−xNdx(WO4)2 (Nd:KGW) single crystal in oxygen ambient atmosphere on MgO, YAP (YAlO3) and YAG (Y3Al5O12) substrates at temperatures up to 800 °C. The influence of substrate nature and substrate temperature (Ts) on films crystallinity and morphology were studied by conventional X-ray diffraction (XRD), micro-Raman spectroscopy (μRS) and scanning electron microscopy (SEM). Related emission and excitation spectra and fluorescence decay were examined. The strongly textured polycrystalline Nd:KGW films with fluorescence spectra very close to those of bulk single crystal were deposited only on YAG substrate at higher Ts, whereas the smoother films were obtained at Ts = 400 °C on all types of substrates. Fluorescence properties of the films corresponding to the transitions from the 4F3/2 doublet to the 4I9/2, 4I11/2 and 4I13/2 multiplets, at about 890 nm, 1.06 μm and 1.3 μm, bring a new information about the structure of the film at the scale of the Nd3+ ions environment, which could not be detected by XRD method. The fluorescence decay was almost exponential, with a lifetime of about 110 μs for polycrystalline KGW films.