Enhancement of green-light photoluminescence of Ta2O5 nanoblock stacks

Abstract

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 ∼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.