Desorption rates of surface hydrogen from hydrogenated SiGe (001) surfaces with various Ge concentrations have been investigated with thermal desorption spectroscopy. The activation energy of the hydrogen desorption slightly decreases with an addition of Ge in the SiGe film where the frequency factor of the desorption increases. This implies that the desorption center is the Si site. Fourier transform infrared spectroscopy clearly indicates that the hydrogen desorbs not from Ge but mainly from Si at the substrate temperatures in excess of 430 degrees C, while the surface hydrogen desorbs both from Si and Ge sites below 430 degrees C. (c) 2005 Elsevier B.V. All rights reserved.