Temperature-programmed desorption (TPD) has been used to study the initial adsorption and C-incorporation of organosilanes [monomethylsilane (MMS), dimethylsilane (DMS) and trimethylsilane (TMS)] at Si(001) surfaces. Hydrogen was the only desorbing species observed in the TPD spectra from organosilanes. Organosilane molecules adsorb dissociatively on the Si(001) surfaces at room temperature. TPD spectra from DMS- and TMS-adsorbed Si surfaces present carbon-related hydrogen (H-2) desorption peaks from the initial adsorption. The carbon-incorporation ratio was found to be larger in the order of TMS > DMS > MMS, with the sticking probability of molecules being almost identical for the three organosilane molecules. (c) 2004 Elsevier B.V. All rights reserved.