Visible photoluminescence from silicon-incorporated diamond like carbon films synthesized via direct current PECVD technique

Silicon-incorporated diamond like carbon (Si-DLC) films were deposited via DC plasma-enhanced chemical vapor deposition (PECVD) on glass and alumina substrates at a substrate temperature of 473 K. The precursor gas used was acetylene and for silicon incorporation tetraethyl orthosilicate dissolved in methanol was used. Silicon atomic percentage in the films was varied from 0% to 19.3% as measured from energy dispersive X-ray analysis. Fourier transformed infrared spectroscopy studies depicted the presence of Si-C, Si-H and Si-H-2 bonding within the films. The binding energies of C 1s, Si 2s and Si 2p were determined from X-ray photoelectron spectroscopic studies. UV-vis-NIR spectroscopic studies were used to determine the optical gaps as well as the Urbach parameters of the samples. Room temperature photoluminescence study showed a broad peak centered at around 467 nm. Also the peak intensity was found to increase monotonically with Si percentages. The results are discussed in terms of the electronic structure of a-C:H, the doping induced defect states and the enhanced carbon dangling bonds via the formation of more sp(3) hybridized carbon network. (C) 2011 Elsevier B.V. All rights reserved.