Hydrogenated amorphous silicon carbon nitride (a-SiCN:H) thin films were deposited by hot wire chemical vapor deposition (HWCVD) using SiH4, CH4, NH3 and H-2 as precursors. The effects of the H-2 dilution on structural and chemical bonding of a-SiCN:H has been investigated by Raman and X-ray photoelectron spectroscopy (XPS). Increasing the H-2 flow rate in the precursor gas more carbon is introduced into the a-SiCN:H network resulting in decrease of silicon content in the film from 41 at.% to 28.8 at.% and sp(2) carbon cluster increases when H-2 flow rate is increased from 0 to 20 sccm. (c) 2008 Elsevier B.V. All rights reserved.