Substrate temperature effect on the structural and photoluminescence properties of (Y-Gd)3Al5O12:Ce3+ thin films prepared by pulsed laser deposition

Abstract

Thin films of (Y-Gd)3Al5O12:Ce3+ phosphor was laser ablated on Si (100) substrates by pulsed laser deposition (PLD) method. The deposition was done under 2.7 × 10−2 mbar oxygen atmosphere and 4.5 cm target to substrate distance using 266 nm Nd:YAG laser. The effect of growth temperature on the structural, photoluminescence and optical properties is explored by x-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–visible spectroscopy, respectively. X-ray diffraction results show that the films crystallized in the cubic crystal structure with the crystallites’ size varying non-uniformly with the growth temperature. SEM images show non-compacted surface morphology comprising of spherical micro size particles for Ts = 100 °C and on increasing the substrate temperature, smooth surface morphologies were observed with the appearance of grain growth at 700 °C. Chemical composition analysis by the EDX method confirms the presence of Y, Gd, Al, O and Ce elements in the films, with estimated percentage atomic weight observed to depend on the growth temperature. Photoluminescence (PL) spectra show, broad band emission in the greenish yellow region attributed to the 5d to 4f electronic transitions of Ce3+. With increasing substrate temperature, a shift in PL emission to longer wavelength accompanied by changes in PL intensity was observed. Film deposited at 500 °C gave the highest PL intensity, in close agreement with the improved crystallinity from the XRD results at this temperature. UV-Vis analysis shows the films depicting high reflectance and low absorption above the visible and near infrared regions, with diffuse reflectance which depends on the growth temperature.