Joseph J. Laski

Study of GaN : Eu3 + Thin Films Deposited by Metallorganic Vapor-Phase Epitaxy

Using metallorganic vapor-phase epitaxy, thin films of gallium nitride activated by Eu 3+ (GaN:Eu 3+ ) have been deposited on sapphire substrates at atmospheric pressure. Luminescence from Eu 3+ ions in GaN has been investigated using photoluminescence (PL) and PL excitation spectroscopy. Experimental results show that Eu 3+ ions are excited via energy transfer from the host. Analyses of the observed emission and excitation spectra indicate occupancy of multiple sites in the nitride lattice. Using a pulsed laser source, variation of emission intensity with increasing excitation intensity has also been examined. The possibility of emission saturation at high excitation intensity is discussed from the perspective of application in light-emitting diode sources.

Study of Luminescence from GaN : Tb3 + Powders and Thin Films Deposited by MOVPE and PLD Methods

accompanied by near-band-edge emission and defect emissions from the GaN host was observed for the MOVPE films made using tris2,2,6,6-tetramethyl-3,5-heptanedionatoterbium but not films made with trisisopropylcyclopentadienylterbium. Despite visible luminescence from Tb 3+ in GaN powders and thin films, no energy transfer from the host to activator ions was observed. This suggests that Tb 3+ is unlikely to fluoresce if used in a GaN-based optoelectronic device.