Abstract
Highly luminescent ZnO:Ga-polystyrene composite (ZnO:Ga-PS) with ultrafast subnanosecond decay was prepared by homogeneous embedding the ZnO:Ga scintillating powder into the scintillating organic matrix. The powder was prepared by photo-induced precipitation with subsequent calcination in air and Ar/H2 atmospheres. The composite was subsequently prepared by mixing the ZnO:Ga powder into the polystyrene (10 wt% fraction of ZnO:Ga) and press compacted to the 1 mm thick pellet. Luminescent spectral and kinetic characteristics of ZnO:Ga were preserved. Radioluminescence spectra corresponded purely to the ZnO:Ga scintillating phase and emission of polystyrene at 300-350 nm was absent. These features suggest the presence of non-radiative energy transfer from polystyrene host towards the ZnO:Ga scintillating phase which is confirmed by the measurement of X-ray excited scintillation decay with picosecond time resolution. It shows an ultrafast rise time below the time resolution of the experiment (18 ps) and a single-exponential decay with the decay time around 500 ps.
Highlights
ZnO:Ga-polystyrene composite (ZnO) is a wide direct band gap (~3.3 eV) semiconductor with high exciton binding energy (60 meV), ultrafast excitonic photoluminescence decay and strong room temperature defect related luminescence [1,2]
The powder was prepared by photo-induced precipitation with subsequent calcination
The composite was subsequently prepared by mixing the ZnO
Summary
ZnO is a wide direct band gap (~3.3 eV) semiconductor with high exciton binding energy (60 meV), ultrafast excitonic photoluminescence decay and strong room temperature defect related luminescence [1,2]. High attention is devoted to preparation of various thin film or composite materials where scintillating (nano)particles are incorporated into the optically transparent matrix of organic or inorganic origin. Wet electrochemical etching of porous silicon with subsequent ZnO deposition by magnetron sputtering was used for the preparation of zinc oxide- porous silicon nanocomposites Both white light and UV emission were observed simultaneously via photo- and cathodoluminescence spectroscopy [9]. This may be useful for some applications (such as white LEDs), while it prohibits the application of studied materials in fast scintillation detectors It is the aim of this paper to report the preparation of highly luminescent composite consisting of ultrafast ZnO:Ga scintillating powder, incorporated into the scintillating polystyrene matrix. The efficient non-radiative energy transfer from the host matrix towards ZnO:Ga is evidenced
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