Authors: Y-R Ma, J-H Lin, W-D Ho, R.S. Devan
Affilation: National Dong Hwa University, Taiwan
Pages: 45 - 48
Keywords: Ta2O5, nanorod, photoluminescence
In this study we analyzed the structural, electronic, and photoluminescence (PL) properties of a new morphological form, stacking Ta2O5 nanobrick arrays that were synthesized by hot filament metal-oxide vapor deposition. Field-emission scanning electron microscopy (FESEM) showed the stacking Ta2O5 nanobricks to be arranged in a large-area array, and they were averagely ~20.7 nm wide and ~27.1 nm long. X-ray diffractometery (XRD) displayed the stacking Ta2O5 nanobricks to be orthorhombic (β) phase that was assigned to the space group P21212 with lattice constants of a = 0.6198 nm, b = 4.029 nm, c = 0.3880 nm and α = β = γ = 90º (JCPDS 25-0922). X-ray photoemis-sion spectroscopy (XPS) revealed not only the electronic structures and chemical properties of the stacking Ta2O5 nanobricks but also their stoichiometric Ta and O compositions. Photoluminescence (PL) spectra showed very strong green-light emissions, which were first observed at room-temperature. These green-strong light emissions emerged from the trap-levels of oxygen vacancies within the Ta2O5 bandgap. One of the trap-levels, called the midgap state, can provide a green-light emission with 44.0 and 69.8 % of the intensities of the incident 486.8 and 499.5 nm lasers, strongly indicating that the stacking Ta2O5 nanobricks are good room-temperature visible-light emitters.