Structural and luminescent properties of YAG:Ce thin film phosphor

This work investigated the structural and luminescent properties of YAG:Ce (Ce-doped Y3Al5O12) thin films grown at different deposition conditions. The YAG:Ce phosphor thin films were deposited on quartz at room temperature by rf magnetron sputtering. It was shown that the oxygen partial pressure in the sputtering gas and the rf power strongly affected the Al/Y atomic ratio, growth rate, crystallinity and luminescent properties of YAG:Ce films. The effect of the O2/(Ar + O2) ratio on the composition prepared at RT differs from that prepared at high temperature. The growth rate of YAG:Ce films deposited at the gas ratio of O2/(Ar + O2) = 0% was significantly enhanced. Stoichiometric and polycrystalline YAG:Ce films were obtained in pure Ar. YAG:Ce films that were annealed in N2 had a higher PL emission intensity than those annealed in air because annealing in N2 prevents Ce3+ from the oxidation. We also found that transparency of YAG:Ce/quartz annealed at 1100 °C still was maintained, and YAG:Ce thin film has a transmittance of 75% including the substrate in the visible region. Annealing at temperatures above 1200 °C results in formation of SiO2 crystalline phase. The sample annealed at 1200 °C has much lower transmittance but higher PL intensity than those of the sample annealed at 1100 °C.