Raman spectroscopy and high-resolution luminescence spectroscopy of Ce3+ doped Tb3Al5O12 single crystalline film phosphors grown onto Gd3Al2.5Ga2.5O12 and Y3Al5O12 substrates

Abstract

We present the results of a study on Raman and high-resolution luminescence spectroscopy of Ce3+-doped Tb3Al5O12 single crystalline films (SCFs) grown by the liquid phase epitaxy (LPE) method onto Y3Al5O12 and Gd3Al2.5Ga2.5O12 single crystal (SC) substrates. The Ce3+-doped Tb3Al5O12 films exhibit a strong Ce3+ 5d–4f emission band centred at 560 nm when excited around 488 nm in the vicinity of the 4f–5d absorption band of Ce3+ and the 4f–4f absorption bands of Tb3+ ions in the visible range. To avoid overlapping with this luminescence, Raman spectra were recorded using a 785 nm excitation wavelength. The lattice mismatch between the Tb3Al5O12:Ce films and the Y3Al5O12 and Gd3Al2.5Ga2.5O12 substrates was found to be +0.53% and −1.32%, respectively. The film grown on the Gd3Al2.5Ga2.5O12 substrate exhibits negative and higher residual stress compared to its counterpart grown onto the Y3Al5O12 substrate. The observed shifts in the positions of the Raman modes for the two epitaxial structures correlate with the differences in lattice constants between the films and their respective substrates. High-resolution luminescence spectra recorded at 488 nm and 785 nm excitation wavelengths reveal 5d–4f and 4f–4f electronic transitions of Ce3+ ions and lanthanide trace impurities, respectively.