Triethylamine borane (TEAB) and He, N(2) or NH(3) were applied as additional reaction gases in the production of BC(x)N(y) layers by low-pressure chemical vapor deposition (LPCVD). These layers were deposited on Si(100) wafers and characterized chemically by X-ray photoelectron spectroscopy (XPS) and synchrotron radiation-based total-reflection X-ray fluorescence analysis combined with near-edge X-ray absorption fine-structure spectroscopy (TXRF-NEXAFS). The composition of the material produced without NH(3) was found to be dominated by B-C bonds with the stoichiometric formula B(2)C(3)N. B-N bonds with the formula B(2)CN(3) were preferred when NH(3) was added. A first attempt was made to compare the results obtained by applying trimethylamine borane and TEAB as single-source precursors.