Microstructures and photoluminescence of hydrogenated amorphous carbon films produced by using organic hydrocarbon source

Abstract.

Thin layers of hydrogenated amorphous carbon were prepared by using organic hydrocarbon source, xylene (C₈H₁₀), in plasma-enhanced chemical vapor deposition (PECVD) system. The microstructures were characterized by using Fourier-transform infrared and Raman scattering spectra. The appearance of a sharp vibration signal in 1600 cm^-1 strongly suggests the existence of sp² carbon clusters with aromatic rings. With increasing the deposition rf power, the content of these aromatic structures is increased in the films. In contrast to a broad single PL peak in methane (CH₄)-baseda-C:H films, the PL band of xylene-based a-C:H films contains multiple peaks in blue-green light region, which is influenced by rf power. We tentatively attributed it to the radiative recombination of electron-hole pairs through some luminescent centers associated with aromatic structures.