Fresnoite thin films grown by pulsed laser deposition: photoluminescence and laser crystallization

Fresnoite (Ba2TiSi2O8-BTS) thin films were grown on fused quartz, silicon (100), MgO (100), and a-plane sapphire by pulsed laser deposition, and crystallized by subsequent thermal or flash lamp annealing. The corresponding texture evolution of the BTS thin films was studied by X-ray diffraction. The preferential (001) texture of the crystallised BTS films was found to be most pronounced on sapphire substrates. The broad photoluminescence band of the BTS thin films depends only weakly on temperature. The intensity of the BTS luminescence can be as high as that of the most efficient oxide scintillator materials. In order to qualify the fresnoite thin films for photonic applications, we demonstrate infrared-laser direct writing in amorphous BTS films which allows a local crystallisation and patterning. A subsequent considerable enhancement of luminescence intensity can be applied for UV-sensitive marking of nearly any object.