Luminescent properties of rare earth (Er, Yb) doped yttrium aluminium garnet thin films and bulk samples synthesised by an aqueous sol-gel technique

摘要

Yttrium aluminium garnet (YAG) powders and thin films deposited on silicon substrates were prepared by an aqueous sol-gel route using metal nitrates. The sol-gel process resulted in an amorphous gel, and the thermal decomposition and successive crystallization were characterized by thermal analysis and X-ray diffraction. Powders were prepared by heat treatment of the amorphous gel, while crack-free thin films of densely packed nano-crystalline particles were obtained on silicon substrates by dip-coating technique. Photoluminescence (PL) properties as well as up-conversion (anti-stoke emission) of Er, Yb co-doped YAG phosphors were investigated. Green (555 nm) and red (650 nm) photoluminescence up-conversion emissions arising due to ~4S_(3/2) —> ~4I_(15/2) and ~4F_(9/2)-> ~4I_(15/2) transitions, respectively for Er~(3+) ion were observed. Photoluminescence and radiative life-times of the exited states of Er~(3+) in the visible and near IR ranges are also reported.