Enhancement of green-light photoluminescence of Ta2O5 nanoblock stacks

In this study we have explored the structural, electronic, and photoluminescence (PL) properties of Ta2O5 nanoblock stacks. The Ta2O5 nanoblocks were synthesized by the hot filament metal-oxide vapor deposition (HFMOVD) technique and randomly arranged in large-area stacks. Field-emission scanning electron microscopy (FESEM) showed most of the stacking Ta2O5 nanoblocks to be 21 nm wide. Energy dispersive spectroscopy (EDS) analysis verified the presence of only the elements Ta and O. X-Ray photoemission spectroscopy (XPS) not only revealed the electronic structures and chemical properties of the stacking Ta2O5 nanoblocks but also their stoichiometric Ta/O ratio of similar to 0.416 (i.e. Ta : O = 2.08 : 5). Photoluminescence (PL) spectroscopy showed very strong green-light emissions, which emerged from the trap-levels of the oxygen vacancies within the Ta2O5 bandgap. The PL intensities were linearly enhanced by increasing the laser power and the excitation time. The PL results suggest that the nanoblocks are excellent visible-light emitters.