Defect energy levels in Ta2O5 and nitrogen-doped Ta2O5

Abstract

Crystalline Ta2O5 has very rich defect energy levels as compared to the previously known ones. Thermal treatment of Ta2O5 in a reducing atmosphere increases the photoluminescence (PL) intensity of the deep energy levels in the band gap as compared to the shallow ones. Nitrogen doping creates no new defect energy levels, but rather shifts the maximum PL intensity position of the deep energy levels to even deeper states. The doped nitrogen is interpreted to fill the oxygen vacancy at “in-plane” lattice sites when it is doped to TaO6 octahedron.

A Co‐catalyst‐Loaded Ta3N5 Photoanode with a High Solar Photocurrent for Water Splitting upon Facile Removal of the Surface Layer

“…Two similar emission peaks are also observed in the commercial Ta 2 O 5 powders, whereas no peaks are observed for the Ta 3 N 5 powders. [30] Therefore, the 510 nm and 610 nm peaks may stem from the amount of residual O 2À in the surface passivation layer, which form recombination centers of photogenerated carriers. The EIS and PL results suggest that the density of the surface recombination centers becomes less after removal of the surface passivation layer, which remarkably reduces recombination of photogenerated carriers and enhances the photocurrent.…”

A Co‐catalyst‐Loaded Ta3N5 Photoanode with a High Solar Photocurrent for Water Splitting upon Facile Removal of the Surface Layer

“…To identify the emission peaks, photoluminescence spectra of commercial Ta 2 O 5 and Ta 3 N 5 powders prepared by nitridation of commercial Ta 2 O 5 were also measured and the results are shown in Figure S9. Two similar emission peaks are also observed in the commercial Ta 2 O 5 powders, whereas no peaks are observed for the Ta 3 N 5 powders 30. Therefore, the 510 nm and 610 nm peaks may stem from the amount of residual O 2− in the surface passivation layer, which form recombination centers of photogenerated carriers.…”

Effect of Nitrogen Doping on Variability of TaOx -RRAM for Low-Power 3-Bit MLC Applications

“…This lower intense Ta 4f 7/2 peak (26.6 eV) indicates the presence of small amount of Ta 2 O 5-x . 14 On the other hand, the high intense peak corresponding to Ta 4f 7/2 (23.8 eV) is shifted to lower binding energy compared to that of Ta 2 O 5 (26.6 eV) and the value of BE is higher than that of the TaN (23 eV). 15 This phenomena is appeared due to the substitution of O atoms with N species The same effect is also found in case of nitrogen doped TaO x in several literatures.…”

“…15 This phenomena is appeared due to the substitution of O atoms with N species The same effect is also found in case of nitrogen doped TaO x in several literatures. 14,17 From the XPS analysis and the above literature review, it can be said that, nitrogen doping reduces the variability by eliminating the extra leakage path of the filament in the N-TaO x layer. Y. E. Syu et al showed another important effect of nitrogen in the oxide layer.…”