Raman scattering and photoluminescence of nitrogenated amorphous carbon films

Abstract

The structural and optical properties of nitrogenated amorphous carbon films, grown by rf-magnetron sputtering on silicon substrates, were studied by Raman and photoluminescence ͑PL͒ spectroscopy as a function of the nitrogen concentration and the substrate bias voltage V b . For films deposited with V b ϭ10 V, the photoluminescence emission was most intense at nitrogen concentrations in the carrier gas of 25% ͑75% Ar͒, while the intensity ratio I(D)/I(G) of the Raman bands of disordered graphite ͑D band͒ and graphite ͑G band͒ partially substituted by nitrogen exhibited a minimum simultaneously observed with a minimum of G-band frequency and a maximum of G-band width. Changes in spectral characteristics of Raman scattering at a concentration of 25% (Х30 at %) are indicative of an increase of sp 3 -bonded fraction and disorder. PL-enhancement coincides, in this case, with structural changes and is probably correlated to the substitution of nitrogen in the tetrahedraly bonded amorphous matrix. In the case of films deposited in a pure nitrogen atmosphere, N 2 ϭ100%, no significant PL-intensity changes appeared to exist between films deposited at low positive ͑10 V͒ and highly negative (Ϫ200 V) substrate bias. After several months of sample storage in air, samples grown at negative V b were found to preserve their structural and optical properties, while films grown at positive bias (V b ϭ10) and nitrogen concentrations in the carrier gas above 70% (Х40 at %) delaminated.

Sputter deposited NbCxNy films: Effect of nitrogen content on structure and mechanical and tribological properties

“…The spectrum exhibits an asymmetric peak which can be fit using two Gaussian peaks centered around 1350 and 1550 cm −1 , which are associated with D and G bands, respectively. The D peak is typically attributed to breathing modes of sp 2 bonded atoms in benzene rings or microcrystalline disordered graphite, and the G peak to sp 2 stretch vibrations in graphite, rings or conjugated chains [39,40]. It is known empirically that the sp 2 /sp 3 ratio can be quantified by the G peak position and the Raman intensity ratio I D /I G [41].…”

Synthesis and luminescence mechanism of multicolor-emitting g-C3N4 nanopowders by low temperature thermal condensation of melamine

“…Nowadays, several works about the visible photoluminescence (PL) of carbon nitride have been reported41011. However, the systematic investigation on the tunable PL of carbon nitride is scarce, and it is much rarer for g-C 3 N 4 compounds.…”

“…However, the systematic investigation on the tunable PL of carbon nitride is scarce, and it is much rarer for g-C 3 N 4 compounds. Researchers have tried to propose the explanations about the mechanism of visible PL of carbon nitride4101213. But there is no unambiguous PL mechanism or tunable PL mechanism about carbon nitride, such as g-C 3 N 4 , has been proposed in detail so far, which restricts the preparation and design of carbon nitride with multicolor-emitting and efficient luminescence.…”

Large‐Scale Synthesis of Nitrogen‐Rich Carbon Nitride Microfibers by Using Graphitic Carbon Nitride as Precursor

“…130 nm. It is widely accepted that nitrogen incorporation plays a key role in PL emission; [24] and that the photoluminescence properties of carbon nitride may correlate with the p ! p* electronic transitions in the p-conjugated polymeric units.…”