Bright emission from amorphous sicn thin films

Amorphous silicon carbon nitride (SiCN) films were deposited by a plasma enhanced chemical vapor deposition (PECVD) technique using hexamethyl-disilazane as a main precursor by varying discharge power. The films were characterized with X-ray diffraction (XRD), Auger spectroscopy, Atomic force microscope (AFM), Fourier transform infrared spectroscopy (FTIR). The atomic and electronic structures of the amorphous Si_0.5N_0.5 and Si_0.375C_0.375N_0.25 alloys were studied within a first-principles molecular dynamics (MD) simulation. Both experimental and theoretical results show that, in amorphous SiCN films, the main bonds such as Si-C, Si-N, Si-O, C-C, C-H, N-H and C-N are formed. For all the films, the bright emission that has a three-peak structure at 530, 600 and 720 nm was detected at room temperature. Infrared spectra and the results of first-principles MD simulations point to that the 530 nm emission band can be due to tail-to-tail recombination inside the amorphous Si-C-based matrix, whereas the broad signal in the spectral range 600-750 nm can be assigned to the SiC clusters with Si-O bonds. An increase in discharge power promotes an improvement of the amorphous Si-C network and enhances the surface roughness, which leads to the enhancement of PL intensity. It is suggested that hydrogenated SiCN films will be promising for optoelectronic applications.