Photoluminescence from polymer-like hydrogenated and nitrogenated amorphous carbon films

The mechanism of photoluminescence (PL) in hydrogenated amorphous carbon (a -C:H), and nitrogenated and hydrogenated amorphous carbon (a-C:H:N) thin fi lms grown by radio frequency driven plasma enhanced chemical vapor depositi on is still a subject of much debate. In this work, we investigate the PL s ignal obtained from a-C:H and a-C:H:N films, paying particular attention to the effect of nitrogen flow rate during growth, and postgrowth, ex situ an nealing on the PL properties of the films. We also correlate the PL spectra to the electronic structure of the films. The films had a low paramagnetic defect density (10(17) cm(-3)). The PL spectra were obtained using the 488 nm (2.54 eV) line of an argon ion laser, as the excitation source. It was observed that the nitrogenation of the films leads to the creation of new b ands in the PL signal, which were correlated to the bond fraction of CN tri ple bonds, as measured by infrared spectroscopy. (C) 2000 American Institut e of Physics. [S0021-8979(00)01122-1].