Correlation study of photoluminescence properties and mechanism of hydrogenated amorphous silicon carbide films

Hydrogenated amorphous silicon carbide (a-SiCx:H) films have been deposited by plasma enhanced chemical vapor deposition (PECVD) system with different radio-frequency (RF) powers. The microstructure and optical properties of the films deposited at different RF powers have been studied. The results show that the sp(2)/sp(3) ratio and the average size of sp(2)-C rich domains increase while the hydrogen content and the density of sp(2)-C rich domains in the film decreases with increasing RF power. In addition, the sp(2) carbon domains are observed by HR-TEM, and a possible photoluminescence (PL) mechanism is also suggested: the strong PL emission originates from radiative recombination of excitons within sp(2)-C rich domains and C-Si/C-C random network. As RF power increases, the change of the PL properties can be attributed to the influence of RF power on the sp(2)-C rich domains and the C-Si/C-C random network. The corresponding color coordinates of PL spectra also show that the film has great application potential in white light emission.