Composite character of the photoluminescence in hydrogenated amorphous carbon films

Abstract Composite photoluminescence (PL) spectra, consisting of numerous characteristic bands, are presented for hydrogenated amorphous carbon (a-C:H) layers, prepared from methane or benzene. Some of these appear already in the visible range of excitation, the others can be excited by UV light only. Three peaks with maximum position in the range 4.34–4.50, 3.93–4.01 and 3.64–3.70 eV are in the ultraviolet region. Additional peaks appear in the ranges 3.17–3.22 and 2.85–2.92 eV beside the well-known broad PL band with maximum in the 2.1–2.33 eV range. The relative intensities vary on deposition conditions. Our results measured on numerous samples strongly suggest the existence of some type of intrinsic radiative centers.