The adsorption and decomposition of diethylgermane and triethylgermane on the Ge(100) surface are investigated. These molecules are potential Ge sources for the deposition of epitaxial Ge thin films. Room temperature adsorption of either ethylgermane leads to the formation of surface germanium hydrides and ethyl groups. The ethyl groups decompose at higher temperatures and form ethylene via a beta-hydride elimination reaction. Isotopic labeling experiments are used to confirm this reaction step. This is in contrast to the Si(100) surface where both alpha and beta-hydride elimination is observed for the decomposition of surface ethyl groups. Low energy electron diffraction is used to evaluate the quality of the deposited germanium films.