Silicon carbonitride films were synthesised in a remote plasma chemical vapour deposition process using novel single-source precursors [(CH3)(2)HSiNHN(CH3)(2) and (CR3)(2)Si[NHN(CH3)(2)](2), which are silyl derivatives of 1,1-dimethylhydrazine. The films were characterised by X-ray photoelectron (XPS), Fourier transform infrared (FTIR) and UV-Vis absorption spectroscopy. The microstructure of the films was examined by scanning electron microscopy and diffraction of synchrotron radiation methods. XPS and FTIR spectroscopic studies showed the Si-C and Si-N to be the basic bonds for the films deposited in the system with excited hydrogen, whereas the C-N and Si-N bonds are mainly peculiar to the films synthesised in the system with excited helium. The films were found to be predominately amorphous with a number of crystallites embedded in an unstructured matrix. The crystalline phase can be indexed in tetragonal cell with lattice parameters a = 9.6 Angstrom and c = 6.4 Angstrom. Appearance of the crystals, their dimensions and crystal forms did not depend on the substrate temperature. We hypothesised the crystallisation to be occurring either in the gas phase during deposition or in the solid as a result of the increase in mechanical stress with increasing film thickness. The FTIR and XPS data demonstrate the chemical bonding and the atomic local order in the amorphous matrix to be much more complicated than those of Si3N4-SiC or Si3N4-C3N4 mixtures. This novel material has an optical band gap varying within the energy range from 2.0 to 4.7 eV. The films obtained were highly resistant to thermal degradation. (C) 2003 Elsevier Science B.V. All rights reserved.